Chronic Chagas’ heart disease – From pathogenesis to ... · Chronic Chagas’ heart disease 55 Applied Cardiopulmonary Pathophysiology 16: 55-81, 2012 Chronic Chagas’ heart

55Chronic Chagas’ heart disease

Applied Cardiopulmonary Pathophysiology 16: 55-81, 2012

Chronic Chagas’ heart disease – From pathogenesis to treatment regimes1

Silvia Gilka Munoz-Saravia, Annekathrin Haberland, Gerd Wallukat, Ingolf Schimke

Charité - Universitätsmedizin Berlin, Berlin, Germany

Abstract

Chagas’ disease, caused by Trypanosoma cruzi infection, was discovered nearly 100 years ago(1909) by the Brazilian physician Carlos Chagas. Chronic Chagas’ disease is still ranked as themost serious parasitic disease in Latin America. Infected patients remain lifelong parasite carri-ers. With a latency of 10 to 30 years, nearly one third of parasite carriers develop life-threaten-ing complications: the majority develop Chagas’ heart disease (90%). Gastrointestinal disor-ders (megaesophagus, megacolon) and neuronal afflictions mainly affecting the parasympa-thetic nerve system were found in the others. Chagas’ heart disease presenting with suddendeath, heart failure, malign cardiac arrhythmia, and thromboembolism is currently the majorcause of morbidity and mortality in Latin America, enormously burdening economic resourcesand dramatically affecting patients’ social and employment situations. Chagas’ disease is start-ing to become a worldwide problem due to migration, international tourism and parasite trans-fer by blood contact, intrauterine transfer and organ transplantation. In this review, we reflecton the epidemiology and etiopathology of Chagas’ heart disease. We summarize the mecha-nisms that have been suggested to drive Chagas’ heart disease, mainly those based on autoim-munity phenomena. In this context, we focus on autoantibodies directed to G-protein coupledreceptors. Following the autoimmunity story in chronic Chagas’ heart disease – and in addi-tion to antiparasitic therapy, the treatment of heart failure, arrhythmia and thromboembolismand under study strategies such as heart transplantation and cell therapy – we describe regimesthat use peptides and aptamers for autoantibody removal or neutralization. At present, suchregimes are mostly proposed for beta-1-receptor autoantibodies in patients with dilated car-diomyopathy but, in principle, they can be adapted for patients with chronic Chagas’ heart dis-ease who are positive for comparable autoantibodies.

Key words: autoantibodies, Chagas’ heart disease, epidemiology, G-protein coupled receptors,pathogenesis, treatment, Trypanosoma cruzi

1 The paper contains excerpts from "Chronic Chagas' heart disease: a disease on its way to becoming a world-wide health problem: epidemiology, etiopathology, treatment, pathogenesis and laboratory medicine.” Munoz-Saravia SG, Haberland A, Wallukat G, Schimke I. Heart Fail Rev. 2010 Dec 17 [Epub ahead of print]; with per-mission of Springer-Verlag, Berlin-Heidelberg-New York; License Number: 2701860576037.

56 S. G. Munoz-Saravia, A. Haberland, G. Wallukat, I. Schimke

1. Introduction

Chagas’ disease (American: trypanosomiasis)is an endemic parasitic disease that mainlyoccurs in Latin American countries and iscaused by the flagellate protozoan Try-panosoma cruzi (T. cruzi). The disease wasnamed in honor of the Brazilian physicianCarlos Chagas (born in 1879 in Oliveira, diedin 1934 in Rio de Janeiro) who, in 1909, dis-covered a new trypanosome species in theintestine of the triatomine bug, which henamed T. cruzi in honor of his mentor Oswal-do Cruz. A biographical sketch of CarlosChagas was recently published in memory ofthe discovery of T. cruzi one hundred yearsago [1].

Trypanosoma cruzi (Fig. 1) is commonlytransmitted to humans and other mammalsby the blood-sucking triatomine bug (Reduvi-dae), also colloquially referred to as the kiss-ing bug (Fig. 2), which can transmit T. cruzithroughout its lifetime (up to 2 years). As car-tooned in Figure 3, besides infected humans,more than 100 mammals, including dogs,cats, rats, sloths, armadillos, and bats, areknown to be parasite reservoirs. Due to tri-atomine bug cannibalism, T. cruzi can also bespread throughout triatomine populations.Birds and reptiles do not carry T. cruzi. Onceinfected with T. cruzi, subjects become life-long parasite carriers and pass through sever-al stages of the disease, as illustrated in Figure

4, which is based on some excellent reviews[2-6]. Despite lifelong parasite persistence,two thirds of patients remain asymptomatic.Of the remaining third, and sometimes onlyafter decades, 90% can develop heart dis-ease, which causes enormous socio-econom-ic problems in Latin American countries. Theother 10% are affected by gastrointestinaldiseases and neuronal afflictions.

Consequently, initiatives and control pro-grams were started, which include 1) initia-tives for interrupting the domestic andperidomestic transmission cycles by chemi-cal control of the vectors, animal reservoirs,and infected humans, 2) initiatives for im-proving housing conditions and health edu-cation, and 3) screening for infected blooddonors, who form one of the main non-vec-tor routes of transmission.

For subjects who are already infected,strategies for an earlier diagnosis, improvedmonitoring of the progression of the disease,and optimal treatment guidance are essentialelements of disease control. In our view, im-provements in the understanding of thepathogenesis of chronic Chagas’ disease ingeneral and specifically of Chagas’ heart dis-ease are the most important conditions forguaranteeing this.

Figure 1: Electron micrograph image ofTrypanosoma cruzi (Reproduced withpermission of Rubem F. S. Menna-Bar-reto, Instituto Oswaldo Cruz – FIO-CRUZ, Rio de Janeiro)


Figure 2: Triatomine bug (Reduvidae) (Reproducedfrom [25] with permission of F. Torrico and M. Castro;Universidad Mayor de San Simon, Cochabamba, Bo-livia and E. van der Enden; ITGPRESS, Antwerpen,Bergium)

Figure 3: Sylvaticand domestic net-work of infectionwith Trypanosomacruzi including thepathogen (Trypano-soma cruzi), vector(Reduvidae) andhosts (more than100 wild and do-mestic animals).Beside in humans,pathology of Cha-gas’ cardiomyopathywas seen in dogs.

Figure 4: Timecourse from Trypa-nosoma cruzi in-fection to chronicChagas’ disease


2. Epidemiology

The geographic distribution of the triatominevector and consequently the area of infectionrisk extend from the southern USA down tosouthern Argentina. The main endemic areaof Chagas’ disease covers more than 20countries from Mexico down to northern Ar-gentina (Fig. 5). As indicated in Table 1(adapted from Dias et al. [7] and Salvatella[8]), there were 30 million cases of infectionin the 1980s, with an annual rate of 700,000newly-infected subjects and more than45,000 fatalities. Following successful multi-national initiatives for interrupting Chagas’disease transmission, in 2006 it was estimat-ed that there were 28 million people at risk,15 million infected cases, and an annual inci-dence and mortality of 41,200 and 12,500,respectively. The number of endemic areasdecreased from 21 countries in the 1980s to18 countries at present.

Chagas’ disease, which historically was adisease of poor, rural areas, proliferated dueto continuous rural-urban migration, whichwas widespread throughout urban centerssuch as Sao Paulo, with about 300,000 in-fected individuals, and Rio de Janeiro andBuenos Aires, with more than 200,000 infect-ed individuals [9].

For the United States, only a very smallnumber of autochthonous vector-borne cas-es of infection have been reported, located inthe south [10].

Due to the international migration of Lat-in Americans, Chagas’ disease is increasinglybecoming a worldwide problem for health

systems. For the USA, it was estimated thatthere are more than 300,000 infected peo-ple, based on the immigrant population of 23million Latin Americans and the knownprevalence of T. cruzi in their countries of ori-gin [11]. Figure 6 shows that “Europe is notspared” from Chagas’ disease [12]. In Spain,with nearly 1,700,000 immigrants, 87,000 in-dividuals could be infected. For the remain-der of Europe, with a total of 500,000 immi-grants, nearly 3,000 people were estimatedto be infected. For Australia and Canada with85,000 and 157,000 immigrants, 3000 and5000 infected subjects were calculated, re-spectively [13]. Since unknown T. cruzi carri-ers can serve as blood donors, about 100million people are at risk of becoming infect-ed via contaminated blood [14,15]. Othergroups at risk of T. cruzi infection via contact

Figure 5: Endemic area of Chagas’ disease (Re-produced from Wikipedia public domain)

Table 1: Changes in some epidemiological parameters following the interruption of Chagas’ diseasetransmission, 1999-2006; adapted from [7] and [8]

1990 2000 2006

Annual death (thousand) > 45 21 12,5

Cases of infection (million) 30 18 15

Annual incidence (thousand) 700 200 41, 2

Population at risk (million) 100 40 28

Distribution (countries) 21 19 18


with the blood of infected subjects are occu-pational groups such as social and healthcareemployees. Consequently, blood donorscreening began in 2007 in the USA [16].Since 2005 [17], Spanish regulatory law re-quires that all at-risk donors (people born inan endemic area, people whose motherswere native to an endemic area, people whohave undergone blood transfusions in an en-demic area) are screened for Chagas’ diseaseor otherwise be excluded from donation.Chagas’ disease is also being increasingly rec-ognized as an emerging public health prob-lem in other European countries [18,19].However up to now, strategies for detectingT. cruzi-infected blood such as established inSpain did not exist for other European coun-tries.

International tourism is increasingly be-coming another route for the worldwidespread of Chagas’ disease. In endemic areas,

it has been reported that diaplacental and/orperinatal transfer from the mother to her fe-tus can contribute to T. cruzi transmission[20]. Outside Latin America, one case of thecongenital transmission of T. cruzi has beendocumented in Spain [21].

Europe is colonized by different subfami-lies of the triatomine bug. However, there isno indication of T. cruzi transmission by tri-atomine bugs in Europe. As previously report-ed [22], fleas, flies, bedbugs, mosquitos andlice have been suggested as possible candi-dates for T. cruzi transmission in Europe.Some subspecies of ticks (Ixodida) are poten-tial T. cruzi carriers; some of these live in Eu-rope. However, at present, there is no indica-tion that insects transfer T. cruzi to humans inEurope.

Figure 6: Estimated numberof Chagas’ disease (in-fected) patients in Europe.(Color code denotes ex-pected frequency). (Repro-duced from [12] with permis-sion of Oxford UniversityPress, License Number:2692410596257)


3. Etiopathology

3.1 The vicious cycle of Trypanosoma cruzi infection

The life cycle of T. cruzi involves stages in thedigestive tract of the triatomine bug (sec-ondary host), which is the vector, and stagesin the blood and tissues of mammals (host,reservoir). Parasites freely circulating in thehost’s blood are unable to replicate, but afterthey colonize phagocytic and non-phagocyt-ic cells of host tissues, large quantities of T.cruzi are produced via replication and aresubsequently released into the blood. Afterinfection, the parasites exhibit clear tropismfor heart, skeletal, and smooth muscle cells,as well as neuronal cells, which can act asreservoirs for the parasites. Trypanosomacruzi parasites are taken up by triatominebugs when they suck human blood or bloodfrom any other contaminated mammal; theythen multiply in the gut of the bugs. After abug has fed on blood, it excretes the parasitein its feces onto the skin of the host, fromwhere it can enter and continue the viciouscycle of T. cruzi infection. A bug’s infectiousfeces pass via the bug’s bite or other smallwounds into human blood, but the parasitecan also pass from the feces through intactmucous membranes, especially those in themouth and eyes. The feces remain infectiousfor a long time, most likely even when theyare outside of the bug. Consequently, infec-tion via the ingestion of food contaminated

with infected feces has been reported. However, genetic variations in the para-

site and its hosts could be responsible for theregional differences found in the incidence ofthis disease [23,24].

3.2 Acute Chagas’ disease

The acute stage of Chagas’ disease can besymptomless or it can present with only mildclinical symptoms and therefore remain undi-agnosed. A typical sign that is often ignoreddue to its non-specificity is chagoma, a localinfection characterized by swelling aroundthe bug’s bite. If the route of parasite entry isthrough the conjunctiva of the eye, patientspresent after 4 to 12 days with a more typi-cal symptom called Romaña’s sign [25],which comprises conjunctivitis, unilateralpalpebral edema and pre-auricular lym-phadenopathy (Fig. 7). However, other symp-toms are less common and only 5-10% of pa-tients present with fever, malaise and lym-phadenopathy.

In a small number of patients, especiallychildren, hepatosplenomegaly, myocarditis,and meningoencephalitis are occasionallyseen. The mortality rate due to acute Chagas’disease is 2-6%, which is mainly caused bymyocarditis and meningoencephalitis[3,4,5,26,27].

Figure 7: Child with Romana'ssign (also named chagoma); uni-lateral painless periorbital swel-ling associated with the acutestage of Chagas' disease. (Re-produced from [25] with permis-sion of F. Torrico and M. Castro;Universidad Mayor de San Si-mon, Cochabamba, Bolivia andE. van der Enden; ITGPRESS,Antwerpen, Bergium)


3.3 Mechanisms of parasite control

Both humoral and cellular immune responsesparticipate in parasite control, but their high-ly complex interactions are far from beingclarified [28]. The humoral immune responsecomprises CD8+ T cells and macrophages, aswell as IFN-γ secretion, which seem to be es-sential players. Perforin/granzyme-dependentkilling of infected cells and FAS-mediatedapoptosis, as well as the macrophage pro-duction of IL-12, for induction of T. cruzi re-sistance, must be considered [29,30]. Otherimportant players in parasite defense via reg-ulation of the immune response and due totheir cytotoxic properties are cytokines suchas e.g. IFN-γ and TNF-α and NO [31-37]. Incontrast, there is evidence to show thatCD8+ T cells can lose their activity and thatimmune suppression elements come directlyfrom T. cruzi, causing ineffective parasitecontrol by the immune system, which couldbe a reason for the incomplete parasite erad-ication and consequent life-long parasite per-sistence that result in chronically infected pa-tients [38].

3.4 Chronic Chagas’ disease

Typical signs of chronic Chagas’ disease arepositivity for anti-T. cruzi antibodies and – byusing modern analytical equipment suchPCR techniques – the detection of parasitesin patient tissue samples [39,40]. Despite thispermanent parasitic load in all patients, onlyone third of patients progress from theasymptomatic phase to the symptomaticstage of chronic Chagas’ disease (Fig. 4).

3.4.1 Asymptomatic chronic Chagas’disease (latency stage, indeterminate stage)

Asymptomatic patients are only diagnosedby chance or by screening for T. cruzi anti-bodies, for example in the case of enrolmentinto the blood donor system or in prepara-

tion for surgery. The heart and the gastroin-testinal tract have no distinct pathologicalfindings on ECG, sonography, or radiology.However, small focal inflammatory lesionshave been detected in tissue samples of theheart, skeletal muscle and the gastrointestinaltract from asymptomatic patients [41-43].The asymptomatic stage might be interruptedby episodes showing non-specific character-istics of acute infection. In particular, patientswith immunosuppressive disorders, such asHIV-positive patients, show such episodes[3,4,44].

3.4.2 Symptomatic chronic Chagas’disease (symptomatic stage)

Genetic variability has been discussed as be-ing responsible [23,24,45] for whether pa-tients are asymptomatic or develop heart dis-ease, gastrointestinal disease or neuronal dis-orders, but this debate has not yet been con-cluded [46]. With respect to the relationshipbetween the HLA polymorphism and themanifestation of chronic Chagas’ disease, as-sociations were observed between distinctHLA alleles and an increased risk of develop-ing chronic Chagas’ disease in some studies[47,48], but others denied finding any suchrelationships [49].

3.4.2.1 Chagas’ heart disease

Chagas’ heart disease becomes manifest inmen and women with a comparable frequen-cy, and it mainly begins between the ages of30 and 50 years old. In line with the diagnos-tic options available in endemic areas, car-diac arrhythmia, found by Holter ECG exam-ination, is often the first clinical indication ofthe development of Chagas’ cardiomyopathy[50,51]. With increasing severity, right bun-dle branch block, left anterior hemiblock,ventricular extrasystoles, sinus bradycardia,auricular fibrillation and complete atrioven-tricular block were found to be the most fre-quent symptoms [3,5,25]. Consequently, for


newly diagnosed chronic Chagas’ patientsbased on T. cruzi antibody positivity, it wasrecommended that patients should undergoa medical history interview, a physical exam-ination, and a resting 12-lead ECG with a 30-second lead rhythm strip [52]. In the case ofnormality, examinations should be repeatedannually. Where Chagas’ heart disease is di-agnosed, a comprehensive cardiac evalua-tion is recommended, which should includeHolter ECG examination and echocardiogra-phy, which is clearly more sensitive than ECG[53,54]. Cardiac MRI can successfully com-plete the diagnosis and aid planning of themanagement of chronic Chagas’ disease[55,56]. From a clinical point of view, my-ocarditis, thromboembolic events, suddencardiac death and congestive heart failureare typical of advanced Chagas’ heart dis-ease. However, about 30% of Chagas’ heartpatients die from sudden cardiac death with-

out any characteristic signs of advanced Cha-gas’ heart disease.

Chagas’ cardiomyopathy is characterizedby progressive heart enlargement resultingfrom chamber dilatation. Figures 8A (photo-graph of explanted chagasic hearts) and 8B(thorax radiography) show typically enlargedchagasic hearts. Whereas microscopic para-site detection was found to be successful inonly 10-20% of cardiomyopathic hearts,DNA amplification tests showed the appear-ance of parasites in almost all patients withChagas’ heart disease [57,58].

However, the severity of cardiomyopathydid not correlate with the occurrence of par-asite DNA. Therefore, direct heart damage inrelation to parasite load and inflammationdoes not seem to be the only mechanism re-sponsible for heart damage. The histopatho-logical pattern of the chagasic heart showsnests of focal inflammation with T cells and

Figure 8: A) Explanted hearts of patients with chronic Chagas disease demonstrating increasing car-diomegaly. (reproduced with permission of E. van der Enden, Institut voor Tropische GeneeskundeAntwerpen, Belgium). B) Cardiomegaly of a chronic Chagas’ patient with implanted pacemaker, de-monstrated by thorax radiography (Reproduced with permission of R. Araujo, Santa Barbara Hospi-tal, Sucre, Bolivia)


varying numbers of B cells and macrophages,diffuse interstitial fibrosis, and a disturbedmorphology of the myocytes. The conduc-tion system in the heart also shows alter-ations [59-61].

The often apically aneurysmatic Chagas’heart is thought to be the cause of thrombusformation, which may lead to thromboem-bolic events in the brain and lungs, andwhich are thought to be responsible for thehigh rate of sudden death in Chagas’ heartdisease. However, the main life-threateningcomplication of chronic Chagas’ disease isthe continuous progress towards severe heartfailure. Nearly 60% of patients die due to car-diomyopathy.

3.4.2.2 Chagas’ gastrointestinaldisease (megaesophagus andmegacolon)

Malnutrition caused by swallowing problemsand regurgitation leading to weight loss, aswell as obstipation with abdominal pain,mark the progress of chronic Chagas’ diseaseinto megacolon (Fig. 9) and megaesophagusconditions. Radiological investigations em-ploying barium as the contrast agent can be

used for early diagnosis; however, a simpleradiological investigation is often sufficient.

3.4.2.3 The nerve system in chronicChagas’ disease

Damage to the parasympathetic nervous sys-tem could be the main driver of alterations inthe vegetative nervous system in chronicChagas’ disease [62]. Damage to theparasympathetic nervous system starts in theacute phase and proceeds into the chronicphase. The central nervous system, however,is mostly affected during the acute phase ofthe disease. Rare cases of changes in the psy-che of chronically infected Chagas’ patientsare also a sign of nerve damage during thechronic phase of the disease [3].

4. Pathogenesis of chronicChagas’ heart disease

Several hypotheses – extensively summa-rized by Gironés et al. [28] and Engman andLeon [63] – have been formulated: A: Primary damage of the neuronal system

with denervation of the autonomous

Figure 9: Photographof the megacolon of apatient with chronicChagas disease. (Re-produced with per-mission G. Valda,Santa Barbara Hospi-tal Succre, Bolivia)


parasympathetic system in the heart. Thisneuronal damage starts in the acute phaseof the disease and accelerates in thechronic stage, resulting in lesions.

B: Cardiomyocyte toxicity due to T. cruziand/or T. cruzi-derived products resultingin host myocytolysis in the acute stage, isthought to start the progress toward Cha-gas’ heart disease. Due to the finding ofmyocardial parasite persistence, chronicmyocytolysis could aggravate Chagas’heart disease. However, with the excep-tion of immunosuppressed subjects andthe minority of Chagas’ patients with ahigh parasite titer, the generally low para-site titer in the chronic stage should meanthat parasite cytotoxicity and/or the cyto-toxicity of parasite-derived productsshould only be of limited relevance.

C: Parasite-induced microvascular alter-ation is based on the assumption that par-asites interact with essential metabolic re-actions in microvascular cells, causing hy-poperfusion, subsequent hypoxic/is-chemic damage of the cardiomyocytesand inflammatory conditions in the heart.All together could drive Chagas’ heart dis-ease.

D: Polyclonal B cell activation following thedisruption of normal immune regulationand leading to immunosuppression andautoimmune processes could supportpathogenetic events.

E: Persistent T. cruzi antigens might trigger Tcell-mediated responses of the delayed-type hypersensitivity cells or cytotoxiccells, leading to damage of the host’s in-fected and/or bystander cells.

F: Autoimmunity induced by T. cruzi-specif-ic antigens or by host antigens might re-sult from T. cruzi antigen-associated molec-ular mimicry, as well as from bystander ac-tivation.

Although none of these hypotheses claimexclusivity, autoimmunity is being increasing-ly accepted as a pathogenetic driver of Cha-gas’ heart disease. The potential cooperationbetween molecular mimicry and bystanderactivation for T. cruzi-induced “autoimmune”Chagas’ heart disease is demonstrated in Fig-ure 10, which is based on [28].

Bystander activation means that parasites,especially in the case of strong intracellularparasite replication, cause pro-inflammatoryconditions (release of cytokines, NO/peroxy -

Figure 10: Sug-gested mecha-nisms of T. cru-zi pathogenicityby molecularmimicry and by-stander activati-on adaptedfrom [28]


nitrite, chemokines), which lead to cardiomy-ocyte damage and the subsequent liberationof autoantigens and cryptic epitopes thatnormally have no access to the host’s im-mune system but which are now recogniza-ble by autoreactive T cells. In parallel, T-cellsproliferate and are activated in order to per-petuate the immune response against theheart structures.

In molecular mimicry, T. cruzi proteinscross-react with proteins of the host’s heart,which now are recognized by the host’s acti-vated immune system. Molecular mimicry isincreasingly being suggested as being thefirst driver of autoimmunity in chagasic pa-tients. This is supported by the finding ofeven more cross-reactions between T. cruziand host antigens. A number of such cross-re-actions – without claiming completeness –are listed in Table 2, which was adapted fromCunha-Neto et al. [64]. It has been clearly in-dicated in animal experiments that immu-nization with T. cruzi antigens, as well as thetransfer of T. cruzi-activated T cells, producesmyocardial alterations, mainly focal my-ocarditis, demyelination, and conduction sys-tem defects. Additionally, autoantibodies

were found that affected the essential struc-tures and functions of the heart.

Antigens, T cell clones and autoantibod-ies found after infection with T. cruzi are long-persisting, which supports the autoimmunitytheory in Chagas’ heart disease [65].

4.1 G-protein-coupled receptors asautoantigen

In view of the autoimmunity story of Chagas’heart disease, G-protein-coupled receptors(GPCRs) are receiving more and more atten-tion as human antigens that show molecularmimicry of T. cruzi antigens. A variety ofGPCRs for which autoantibodies (AABs)have been identified in patients with diseasesof the heart and circulatory systems areshown in Table 3, adapted from Wallukat etal. [66].

The GPCRs are members of the large su-perfamily of heptahelical transmembraneproteins, to which about 80% of all receptorsbelong. The GPCRs are highly important con-trol elements for the regulation of metabo-lism. The GPCRs sense signal molecules out-

Table 2: Cross reactivity of Trypanosoma cruzi and human antigens favoring molecular mimicry(adapted from [64)

Human antigens T. cruzi antigens

Neurons Sulphated glycolipid

Neuronal 47kD protein FL-160

Heart and skeletal muscle Microsomal fraction

Smooth and striated muscle 150 kDa protein

Cardiac myosin heavy chain B13 protein

Sacroplasmatic reticulum antigen (SRA) SRA

Glycosphingolipids Glycosphingolipids

Microtuboli-associated protein (MAP) (brain) MAP

28 kD lymphocyte membrane protein 55kD membrane protein

23 kD ribosomal protein 23 kD ribosomal protein

Beta 1-adrenoreceptor, M2 muscarinic receptor,

M2 cholinergic receptor, cardiac

Ribosomal P0, P2ß and 150 kD protein

Cardiac muscarinic acetylcholine receptor Unknown


side the cell and change their conformationto activate G-proteins, which – depending ontheir type – modulate the cAMP or phospho-inositol pathways to translate the outside sig-nal into an internal cellular response. Theyare involved in sensory perception, inflamma-tory processes, chemotaxis, endo- and exo-cytosis, cell growth, and differentiation. Theeffects of glandular hormones, tissue hor-mones and neurotransmitters, such as cate-cholamines, glucagon, endothelin, an-giotensin, acetylcholine, and serotonin,amongst others, are mediated via the GPCRs.

Due to the central role of GPCRs in theregulation of metabolism, it is not surprisingthat altering GPCR-dependent signal trans-duction results in a wide variety of patho-genetic consequences.

4.1.1 Autoantibodies against G-protein coupled receptors inChagas’ heart disease

4.1.1.1 Basic remarks

With respect to the AABs against GPCRsfound in Chagas’ patients, those directed tothe beta-1-adrenergic receptor (beta1-AABs),the beta-2-adrenergic receptor (beta2-AABs),and the muscarinergic-2 receptor (M2-AABs)have received particular attention. The AABstarget the negatively-charged region of thesecond extracellular receptor loop of GPCRsand the binding of AABs enables receptordimerization, stabilizing active receptor con-formation [67,68]. Figure 11 shows theschematic structure of the beta-1-adrenergicreceptor in relation to beta1-AABs. Onlymonovalent Fab fragments did not stabilizethe receptors.

Table 3: The G-protein-coupled receptors and their functional autoantibodies which were suggestedas driving the pathogenesis of heart and circulatory diseases (adapted from adapted from [66]. α-R,α-adrenergic receptor; β-R, β-adrenergic receptor; AT1-R, angiotensin II-receptor 1; M2-R, muscari-nic 2-receptor; 5HT4-R, serotonin receptor; AcCh-R, muscarinic acetylcholine receptor; GluR3, gluta-mate receptor, TSH-R, thyroid stimulating hormone receptor; aa, amino acid; AAB, autoantibody

Receptor Disease AAB effect Corresponding epitope

α1-R Hypertension agonist-like Loop 1,2

β1-R Dilated cardiomyopathy agonist-like Loop 1,2

β1-R Myocarditis agonist-like Loop 1,2

β1-R Chagas disease agonist-like Loop 2

β2-R Chagas disease agonist-like Loop 2

β2-R Allergic asthma inhibitory Loop 3

AT1-R Preeclampsia agonist-like Loop 2

AT1-R Malignant hypertension agonist-like Loop 2

AT1-R Vascular renal rejection agonist-like Loop 2

M2-R Chagas disease agonist-like Loop 2

M2-R Dilated cardiomyopathy agonist-like Loop 2

5HT4-R Systemic lupus erythematodes agonist-like Loop 2

AcCh-R Myasthenia gravis inhibitory N-terminal extracellular domain

GluR3 Rassmussen’s encephalitis, non-in-

flammatory focal epilepsy, catastro-

phic epilepsy

agonist-like aa 372-386

TSH-R Graves disease Agonist extracellular domain, conforma-

tional epitope


There is now growing evidence to showthat AABs are important pathogenetic sub-strates of Chagas’ heart disease, particularlybeta1-AABs. This is not least because of thesimilarities between Chagas’ heart diseaseand dilated cardiomyopathy (DCM). Both pa-tient groups carry a high percentage of be-ta1-AAB. Consequently, a “cross-talk” [69]was suggested between the beta1-AABsfound in Chagas’ heart disease and the be-ta1-AABs found in DCM, which means thatthe results from in vitro and animal experi-ments, as well as from human studies, whichfocused on the latter case, can consolidatethe beta1-AAB-associated history of the for-mer. The first indication for beta1-AABs in theserum of patients with DCM was – although

often ignored – supplied in 1987 by Wallukatand Wollenberger [70], followed in 1989 byLimas et al. [71]. Already years before (1976),Sterin-Borda et al. [72] described – in ourview for the first time – an antibody isolatedfrom chagasic sera which interacted withbeating rat atrial preparations. The agonisticeffect of this antibody was prevented in thepresence of the beta-receptor blockers. In1984, the specificity of this antibody to thebeta1-receptor was suggested [73].

A variety of functional responses inducedby beta1-AABs and thought to drive car-diomyopathy were recently summarized byYoshikawa et al. [74]. Most important werethe experiments that showed heart alter-ations typical of cardiomyopathy [75,76] fol-

Figure 11: The human beta-adrenergic receptor as a model of G-protein coupled receptors targetedby the corresponding autoantibody. The N-terminal domain usually contains less than 50 amino acidsand is located in the extracellular space, whereas the C-terminal part of the protein varies from 23(muscarinergic2 receptor) to about 100 amino acids (beta2-adrenergic receptor). The transmembra-ne regions usually contain between 23 and 24 amino acids, limited by the helical secondary structu-re and the thickness of the hydrophobic lipid bilayer. The homology varies throughout the whole su-perfamily. However, the homology is higher (35%; 90%) in the transmembrane helices and functio-nally important side chains in the transmembrane helices, and the loops are strongly conserved bet-ween different vertebrate species. Agonists bind to a hydrophobic cave formed by the transmembra-ne helices. Indicated epitops on the second extracellular loop are the targets of beta1-adrenergic re-ceptor autoantibodies present in patients with cardiomyopathies.


lowing the transfer of beta1-AAB to animals.At cellular and subcellular levels, changes inthe action potential duration and contractilityof cardiomyocytes have been observed fol-lowing the addition of beta1-AAB and alsoM2-AAB [77,78].

Beta1-, beta2-, and M2-AABs which werefound in patients with Chagas’ heart diseaseare agonistic. However, depending on the dif-ferent downstream effects – the activation ofadenylate cyclase by beta1-AAB and beta2-AAB and its inhibition by M2-AAB – positiveor negative chronotropy was evident. Inagreement with this, IgGs prepared from theblood of Chagas’ patients, which preferential-ly contained beta1-AAB and beta2-AAB, acti-vated adenylate cyclase and increased cAMPformation in heart cell membranes and car-diomyocytes. This occurred in parallel withincreased contractility [79,80].

Activation of the L-type calcium canalwas a further characteristic reaction in thepresence of especially beta1-AAB. This mightresult from the protein kinase A-dependentphosphorylation of the canal protein, but itcould also result from a direct interaction be-tween the activated G-protein subunits andthe canal proteins [81,82]. It has generallybeen accepted that changes in the calciumflow caused by AABs are an essential compo-nent in the pathogenesis of myocarditis anddilated cardiomyopathy [83].

Apoptosis induced by beta1-AAB couldbe another key event in the pathogenesis ofcardiomyopathy [84].

As previously mentioned, alterations ofthe parasympathetic nervous system couldbe one of the key events in the pathogenesisof both Chagas’ heart disease and gastroin-testinal disease. M2-AABs reduced the con-tractility of the rat atrium, increasing cGMPand reducing cAMP formation [85]. Howev-er, it has been suggested that M2-receptor-dependent pathogenetic mechanisms couldbe more profound in gastrointestinal manifes-tations. M2-AABs increased the tonus (basal)at the colon and esophageal strips and re-duced the concentration of cAMP [86,87].

It has been assumed that the binding ofM2-AAB activates pertussis-sensitive G pro-teins that inhibit adenylate cyclase. Addition-ally, it has also been suggested that M2-AABinduces receptor desensibilization and se-questering, which would support dysautono-mia of the colon and esophagus [88]. How-ever, with respect to the high prevalence ofM2-AAB in Chagas’ heart disease, theseAABs should not be underestimated as driv-ers of Chagas’ cardiomyopathy.

4.1.1.2 Autoantibody pattern and frequency

Positivity for beta1-, beta2-, and M2-AABswas frequently found in a distinct percentageof chronically infected Chagas’ patients[89,90]. As indicated in Table 4, we foundpositivity for beta1-AAB, beta2-AAB, andM2-AAB in nearly one third of all asympto-matic patients [91]. Chagas’ heart patientspresented with nearly 100% positivity for be-ta1-AAB and M2-AAB but only 38% of theheart patients had beta2-AAB positivity. Ofthe megacolon patients, 90% were positivefor all three receptors. Patients who were suf-fering from cardiomyopathy and megacolonwere found to carry all three receptors with afrequency of nearly 100%.

The autoantibody frequency (ca. 30%) ofthe asymptomatic Chagas’ patients clearlyparallels the epidemiological data on the inci-dence (ca. 30%) of Chagas’ heart disease inchronically infected patients. Consequently,we suggested that autoantibody detection inasymptomatic Chagas’ patients could indi-cate the patients’ risk for symptomatic Cha-gas’ disease, especially for Chagas’ heart dis-ease, even before traditional diagnostic toolsdiagnose Chagas’ heart disease. Further-more, beta1-AAB together with M2-AABshould be indicative of Chagas’ heart diseaserisk, whereas beta2- and M2-AAB positivityshould be indicative of the risk of gastroin-testinal disease.

Recently, we presented the first indica-tions to support this hypothesis [92]. Thirty-


one (27-47) months (median, range) after theprimary classification of chronic Chagas’ pa-tients as being asymptomatic and with orwithout autoantibody positivity, we contact-ed a sub-cohort of 36 of these patients, ofwhom 15 were autoantibody negative and21 autoantibody positive. None of the AAB-negative patients reported clinical symptomsor ECG characteristics indicative of progres-sion to symptomatic Chagas’ disease. Amongthe group of AAB-positive patients, one pa-tient presented with cardiomyopathy diag-nosed by ECG, demonstrating the progres-sion to symptomatic chronic Chagas’ dis-ease. In the primary study, this woman hadhad the typical cardiomyopathic AAB com-position of beta1-AAB combined with M2-AAB. A second patient, a 31-year-oldwoman, presented with clinically diagnosedmegacolon. This woman was burdened in

the primary investigation with M2-AAB posi-tivity and borderline positivity for beta2-AAB.

5. Therapy

5.1 Acute Chagas’ disease

Therapy in the acute stage concentrates onthe elimination of the parasites, preferably byusing Nifurtimox or Benznidazol [4,15,93]While Nifurtimox has to be taken for be-tween 50 and 120 days, Benznidazol is ad-ministrated for up to 60 days and, due to itssafety and efficacy profile, is the first-linetreatment option [94]. However, some T.cruzi strains can develop resistance againstthese drugs. Consequently, only 50% oftreated patients are drug responders. Further-more, the existing drugs show enormous po-

Table 4: Basic data and percentages of positivity for autoantibodies (AAB) against beta 1-adrenergic,beta 2-adrenergic, and muscarinergic 2 receptors (beta1-AAB, beta2-AAB, M2-AAB) of 228 Chagas'disease patients and 29 healthy subjects [1].

C I CM MC CM+MC

n (male/female) 29 (9/20) 96 (26/70) 57 (34/23) 30 (11/19) 45 (21/24)

Age (yrs), median

(min/max)

30 (19/61) 30 (18/82) 47 (18/82) 46 (19/78) 54 (29/81)

AAB positivity (%)

Beta1-AAB 0 34 100 38 96

Beta2-AAB 3 33 89 97 98

M2-AAB 0 42 98 100 100

Beta1-/M2-AAB 0 29 98 38 96

Beta2-/M2-AAB 0 24 89 97 98

Beta1-/M2-AAB or

beta2-/M2-AAB

0 34 98 99 96

Categories of car-

diomyopathy (%)

Mild 5 15

Moderate 44 56

Severe 51 29

C = healthy control subjects; CM = patients with chronic Chagas' disease manifested as cardiomyopathy;

CM+MC = patients with chronic Chagas' disease manifested as cardiomyopathy combined with megacolon;

I = patients with Chagas' disease in the indeterminate (asymptomatic) state; MC = patients with chronic

Chagas' disease manifested as megacolon only. CM > MC, p ≤ 0.001.


tential for toxic side effects, which manifest inthe liver and as an allergic reaction, mainly after long-term administration. Side effectsare inversely related to the age of patients. Asreviewed recently by Rassi et al. [95], thereare clear recommendations for the use of an-ti-T. cruzi treatment in cases of acute and re-activated infection. Anti-T. cruzi treatmentcan be offered to children and adults who donot have advanced Chagas heart disease, butit is contraindicated in pregnant women andsubjects who suffer from kidney and liver in-sufficiency. Regardless of the PCR-detectedmyocardial parasite persistence, its suggestedrole in the pathogenesis of chronic Chagas’heart disease, and animal experimentsdemonstrating the prevention of cardiomyo -pathy development following parasite reduc-tion [96], a clear benefit of anti-T. cruzi treat-ment in the transition from the asymptomaticstage to the cardiomyopathic stage and fur-ther to severe cardiomyopathy still remains tobe found. “BENEFIT”, which is an under-studymulticenter trial on 3,000 Latin Americanswith mild to moderate Chagas’ heart disease,could clarify the relationship between try-panosomiasis interruption and cardiac dis-ease progression and death [97].

The whole-genome sequencing of T.Cruzi in 2005 revealed kinomes, which areknown to contain a large and diverse set ofprotein kinases and phosphatases, and whichcould be used as targets in the future to stim-ulate the development of highly specific anti-T. Cruzi drugs [98].

5.2 Chronic Chagas’ heart disease

5.2.1 Drug treatment

In contrast as reported in several recent re-views [95,99,100], a wide range of therapeu-tic possibilities are available after the manifes-tation of Chagas’ heart disease, which, ingeneral, do not differ much from the treat-ment of cardiomyopathies of other etiolo-gies. The drug treatment of heart failure, ar-rhythmias and thromboembolism, as well aspacemaker and cardioverter-defibrillator im-

plantation and resynchronization therapy areclearly indicated.

Although beta-blocker treatment inchronic Chagas’ cardiomyopathy has beencritically viewed due to bradyarrhythmia andconduction defects, today there is also evi-dence of its beneficial effects in Chagas’ car-diomyopathy patients [101,102]. After the es-tablishment of a cardioembolic risk score forchagasic patients, anticoagulation was rec-ommended in particular for cardioembolicstroke prophylaxis [103].

Irrespective of the continuous optimiza-tion of drug therapy, the outcome of chronicChagas’ patients with severe heart failure isvery poor, as seen for patients with heart fail-ure due to other etiologies. One-year survivalrates from 20% to 70% were documented[104,105].

5.2.2 Heart transplantation and assistdevice and cell-based therapy

Heart transplantation is one of the optionsfor Chagas’ patients with refractory heart fail-ure. In Brazil, Chagas’ cardiomyopathy is, fol-lowing idiopathic dilated cardiomyopathyand ischemic cardiomyopathy, the third indi-cation for heart transplantation [106,107].The survival of chagasic heart recipients wasfound to be better compared to heart recipi-ents of other etiologies. In 27% to 39% ofthe recipients, reactivation of T. cruzi wasseen, which could have been favored by theimmunosuppressive protocol required forpreventing graft rejection [108].

Whereas heart transplantation could be-come a viable option for chagasic patientswith severe heart failure who live in devel-oped countries, unfortunately, in the endem-ic area of Latin America, this therapeutic op-tion will not be available to many due to thehigh costs of heart transplantation and the re-stricted numbers of heart donors. The sameis true for assist device treatment for bridgingto heart transplantation, but also sometimesfor destination therapy or bridging to recov-ery. However, assist devices for bridging to


heart transplantation have only been testedin a low number of chagasic patients [109].

As is the case for cardiomyopathy in gen-eral, cell-based therapy is being increasinglydiscussed for Chagas’ cardiomyopathy [56].Although cell-based therapy is only in its ear-ly stages and the number of patients treatedso far is very low, the first promising resultsdemonstrating the benefits, for example animprovement in NYHA class, have been pub-lished [110]. At present, we are awaiting theresults of a clinical trial conducted between2006 and 2010 in Brazil to evaluate the effi-cacy of cell-based therapy in Chagas’ car-diomyopathy [111].

5.2.3 Autoimmunity-targeted therapy

Considering the increasing acceptance of anautoimmune background in the pathogene-sis of life-threatening complications of chron-ic Chagas’ disease in general but particularlyfor Chagas’ heart disease, new treatmentregimes similar to those generally used in au-toimmune diseases, such as treatment withanti-inflammatory or immunosuppressivedrugs, could become increasingly important.Another promising option could be the elim-ination or neutralization of the high percent-age of pathogenetic AABs found in chronicChagas’ heart disease patients.

5.2.3.1 Autoantibody immunoapheresis

Lobovsky et al. [112] demonstrated for thefirst time the possibility of clearing serumfrom chagasic patients positive for beta1-AABs using an apheresis technique. In this invitro experiment, beta1-AABs of chagasicsera was immunoadsorbed using a commer-cially available Coraffin matrix (FreseniusMedical Care, Bad Homburg, Germany) con-taining a peptide representing the second ex-tracellular loop of the beta1-receptor. At theend of this procedure, the beta1-AAB activi-ty of the sera was clearly abolished, which

was tested using ELISA and a bioassay thatmeasured the chronotropic response ofneonatal rat cardiomyocytes. Consequently,Lobovsky stated that “further experimentsare needed to confirm that this proceduremay be an efficient therapeutic tool forchronic Chagas patients with cardiac com-plex and measurable levels of circulating be-ta1-AABs.” Lobovsky’s idea to use im-munoadsorption for the treatment of Chagas’heart disease had come from the well-docu-mented benefits of beta1-AAB immunoad-sorption in patients with DCM.

The first evidence of the benefit of beta1-AAB clearance in DCM patients was sup-plied by Wallukat et al. [113], who used theIg-Therasorb (Baxter Corp., München, Ger-many), which carries immobilized antibodiesagainst the immunoglobulin kappa and lamb-da light chains and IgG heavy chains for Igimmunoadsorption in DCM patients. Afterapheresis, a marked decrease in serum levelsof immunoglobulins and – as suggested – theaccompanying beta1-AABs was observed.This reduction in beta1-AABs was accompa-nied by an improvement in heart functionand a shift to a lower NYHA class. Subse-quent studies using adequate protocols repli-cated these results [114]. An improvementin cardiovascular function was seen immedi-ately after successful immunoadsorption[113,114] but, even more importantly, thefunctional and clinical benefits to patientswere prolonged up to 3 and 12 months, re-spectively [115,116]. In parallel, renewed be-ta1-AAB generation was not seen until theend of these studies. With respect to the 12month lack in the beta1-AAB re-increase, theauthors speculated that the ex juvantibus tak-ing of antioxidants prevented the renewedformation of beta1-AAB. Indeed, reduction ofoxidative stress was demonstrated after im-munoadsorption of beta1-AAB positive DCMpatients [117].

Besides the apheresis techniques, whichfocused on whole immunoglobulin adsorp-tion for beta1-AAB elimination and thereforeneeded subsequent immunoglobulin substi-tution, there is also a technique for selective


beta1-AAB removal that has the advantage ofnot requiring immunoglobulin substitution.Using the Coraffin column apheresis tech-nique in DCM patients – in the same waythat Lobovsky introduced the clearance ofbeta1-AAB from chagasic sera – the out-come indicated by clinical, functional andbiochemical markers was comparable towhole immunoglobulin adsorption [118,119]. Now we know that the benefits of im-munoadsorption in DCM patients continuedfor 3 and 5 years, respectively [120, 121]and, based on preliminary data [122], evenfor 14.5 years. For the last cohort, this wasmost impressively demonstrated by long-termcardiac stability in end-stage DCM, which inturn could spare many patients from hearttransplantation or delayed heart transplanta-tion listing for many years. The authors sug-gested that in beta1-AAB-positive patientsthe benefits of both specific and unspecificimmunoadsorption are comparable, and thatconsequently the possible removal of otherAABs during unspecific immunoadsorptionappears to have no relevant influence on thetherapeutic results.

Besides Ig-Terasorb and Coraffincolumns, columns with other matrices suchas protein A (Immunosorba) and Peptid-GAM (Globaffin), both from Fresenius Med-ical Care, Bad Homburg, Germany and Tryp-tophan (Immunsorba TR from Asahi KurarayMedical, Tokyo, Japan) are also currentlyused [123,124]; apheresis with the Trypto-phan column was reported to not require im-munoglobulin substitution.

Recently, we supplied basic results for theintroduction of aptamers in the apheresistechnique for cardiomyopathy patients. Ap-tamers are synthetic, highly-structured single-or double-stranded oligonucleotide ligandswhich, if well selected, bind to their corre-sponding target molecules with high speci-ficity but possess low immunogenicity andtoxicity in their applications [125]. Conse-quently, some aptamers have already enteredthe clinical pipeline, including specific ap-tamers designed to protect the cardiovascu-lar system from coagulation and thrombosis

[126-128]. Recently, we selected and patent-ed an aptamer with highly specific targetingof the beta1-AABs which are directed to thesecond loop of the human beta1-receptor.Consequently, this aptamer targeted beta1-AABs found in DCM, Chagas’ cardiomyopa-thy and peripartum cardiomyopathy. We sug-gested the use of this aptamer as an adsorberfor beta1-AAB apheresis in patients sufferingfrom the above mentioned cardiomyopathies[129,130].

However, at present, it is not knownwhich of the AABs (beta1-, beta2- or M2-AAB) found in Chagas’ cardiomyopathy isthe leading pathogenic driver. Therefore, inour view, apheresis techniques that removewhole immunoglobulins should be the first-line option but, as already indicated, this pro-cedure requires post-apheresis immunoglob-ulin substitution. Concepts to find aptamersthat target the whole class of AABs directedto the G-protein coupled receptors in Chagaspatients could complement or substitutewhole immunoglobulin apheresis, and thiscould possibly open new windows in theapheresis of Chagas’ heart disease.

The apheresis procedure is initially cost-intensive but the significantly better survivalrates lead to reasonable costs per life-yeargained [121]. However, for Chagas’ patients,mainly those living in endemic areas, the costfactors and logistical problems could be soimportant that they prevent the wide use ofapheresis as a treatment option for manychronic Chagas’ heart patients.

5.2.3.2 In vivo autoantibody neutralization

A new treatment strategy that focuses on thein vivo blockade of AABs against the GPCRscould possibly overcome the problems asso-ciated with the apheresis technique. Twomain concepts are being studied. The firstconcept is still exclusively focused on theneutralization of beta1-AAB found in DCMpatients and was introduced and patentedfor the first time in 1999 [131]. For this


patent, it was shown that peptides which re-flect the second extracellular loop of the be-ta-1-receptor are able to abolish thechronotropic response of neonatal rat car-diomyocytes on beta1-AABs isolated fromDCM patient sera. Recently, this concept wasexpanded to include cyclic peptides, whichalso contain sequences that correspond tothe second extracellular loop of the beta-1-re-ceptor. After the application of these pep-tides, abolishment of the beta1-AAB re-sponse was shown in vitro and in vivo [132].There is no information on whether or notthe peptide concept for beta1-AAB neutral-ization can be used for the blockage of thebeta1-AABs of patients with Chagas’ heartdisease.

The second concept, based on the select-ed aptame [129,130] which was already in-troduced in 5.2.3.1. This aptamer was notonly shown to neutralize beta1-AABs fromDCM patients, but it was also found to neu-tralize those in patients with Chagas’ car-diomyopathy. This finding could possiblyopen the door to a totally new treatmentstrategy in both DCM and Chagas’ heart dis-ease.

Although highly speculative, our presentactivities in expanding the aptamer conceptto aptamers that target the whole class of car-diotoxic AABs directed to GPCRs couldstrongly promote the use of aptamers in thetreatment of Chagas’ heart disease.

Whatever strategy of autoantibody-direct-ed blocking therapy is administered to pa-tients with Chagas’ heart disease in the fu-ture, asymptomatic but autoantibody-positivepatients should be included in the treatmentfor cardiomyopathy risk reduction.

6. Autoantibody detection andmonitoring

Last but not least, 1) assessment of patientsrisk for Chagas heart disease, 2) guidance ofautoantibody-targeted treatment regimes,and 3) patient after treatment control and fol-

low up require the detection and monitoringof the respective AABs.

Well-established tools are available to di-agnose infected subjects and to monitor Cha-gas’ heart disease progress, as summarizedby Munoz Saravia et al. [133]. Situationswhere AABs must be measured in order toestimate patient positivity and to monitorAAB-directed treatments are more critical.

Currently, a bioassay is mostly used forAAB measurement [70, 91,134]. In this assay,cultured neonatal rat cardiomyocytes are thesubstrate for AABs. The AABs are quantifiedby monitoring the chronotropic effects in-duced by the AAB-containing IgG fractionprepared from the patient’s blood. The addi-tion of specific antagonists enables the differ-entiation between beta1-, beta2-, and M2-AABs. The beating frequency measured inthis bioassay – as an integral parameter ofcell functionality – is an advantage as it cor-responds to the concentration of AABs.Moreover, the bioassay measures beta1-AAB, beta2-AAB, and M2-AAB in parallel.However, the limitations of this bioassay in-clude the sophisticated assay standardiza-tion, a lack of adequate control materials,and extensive turnaround times.

There are other cell-based AAB quantifi-cation methods. In particular, the quantifica-tion of beta1-AABs was performed via cAMPformation in cultured cells that were engi-neered to express the recombinant receptorprotein for beta1-AABs. The quantification ofcAMP is then possible using RIA or ELISAtechnology. Quantifying the formation ofcAMP using FRET technology might becomeimportant in the future [135].

Considering the time, cost, and capacityof cell-based assays, the development of lesscostly but well-standardized and more univer-sally available ELISAs seems to be an essen-tial prerequisite for AAB measurement.Whereas the bioassay quantifies AABs bymeasuring their functionality, ELISA and RIAexclusively use AAB binding to small pep-tides that are homologous to extracellular re-ceptor epitopes recognized by the AABs. TheELISA and RIA tests do not indicate AAB


functionality. This might be one of the rea-sons for previous discrepancies in the resultsbetween bioassays and ELISA tests [136].Nevertheless, ELISA tests specific for beta1-AAB, beta2-AAB, and M2-AAB have fre-quently been used in different studies[137,138]. However, to the best of ourknowledge, no RIA or ELISA tests for Chagas’disease-relevant AABs against GPCRs arepresently commercially available. Whetheraptamer-based assays (ALISA) will comple-ment or substitute the presently availabletools for the quantification of AABs directedto GPCRs remains to be seen.

7. Summary

Chagas’ disease is the most serious parasiticdisease in Latin America and has the poten-tial to become a worldwide problem. Its man-ifestation as Chagas’ heart disease places anenormous burden on economic resources,mainly in Latin America. In order to counter-act the negative effects of Chagas’ heart dis-ease, detailed knowledge of its epidemiologyand pathogenesis is crucial. In this context,Chagas’ heart disease is increasingly consid-ered as an autoimmune disease where AABsagainst GPCRs such as beta1-AABs, beta2-AABs, and M2-AABs drive the pathogenesis.Consequently, in order to complement or re-place the conventional therapies for Chagas’heart disease, treatment strategies for the re-moval (apheresis) or neutralization of the car-diotoxic AABs should be introduced. Suchstrategies could be based on the already sug-gested treatment concepts for AAB-positiveDCM patients. Besides peptides for bindingand blockade, aptamers that specifically tar-get AABs against GPCRs are, in our view,promising for such treatment.

References

1. Moncayo A. Carlos Chagas: Biographicalsketch. Acta Trop 2010; 115: 1-4

2. Prata A. Chagas’ disease. Infect Dis ClinNorth Am 1994; 8: 61-76

3. Prata A. Clinical and epidemiological as-pects of Chagas disease. The Lancet InfectDis 2001; 1: 92-100

4. Teixeira AR, Nitz N, Guimaro MC, GomesC, Santos-Buch CA. Chagas disease. Post-grad Med 2006; 82: 788-798

5. Teixeira AR, Nascimento RJ, Sturm NR. Evo-lution and pathology in Chagas disease – areview. Mem Inst Oswaldo Cruz 2006; 101:463-491

6. Marin-Neto JA, Cunha-Nerto E, Maciel BC,Simoes MV. Pathogenesis of chronic Cha-gas heart disease. Circulation 2007; 115:1109-1123

7. Dias JC, Prata A, Correia D. Problems andperspectives for Chagas disease control: insearch of realistic analysis. Rev Soc BrasMed Trop 2008; 41: 193-196

8. Salvatella R. Achievements in controllingChagas disease in Latin America. Confer-ence Geneva (WHO). 2007 July 6

9. Dias JC. Epidemiology of Chagas’ disease.In: Wendel S, Brener Z, Camargo ME, RassiA (Eds). Chagas’ Disease (American Try-panosomiasis): its impact on transfusionand clinical medicine. Sao Paulo 2001: So-ciedade Brasileira de Hematologia e Hemo-terapia; pp. 49-80

10. Dorn PL, Perniciaro L, Yabsley MJ, RoellingDM, Balsamo G, Diaz J, Wesson D. Au-tochthonous transmission of Trypanosomacruzi, Louisiana. Emerg Infect Dis 2007; 13:605-607

11. Bern C, Montgomery SP. An estimate of theburden of Chagas disease in the UnitedStates. Clin Infect Dis 2009; 49: e52-54

12. Guerri-Guttenberg RA, Grana DR, Ambro-sio G, Milei J. Chagas cardiomyopathy: Eu-rope is not spared! Eur Heart J 2008; 29:2587-2591

13. Schmunis GA, Yadon ZE. Chagas disease: ALatin American health problem becoming aworld health problem. Acta Trop 2010; 115:14-21

14. Schmunis GA. Risk of Chagas diseasethrough transfusions in the Americans.Medicina (B Aires) 1999; 59: 125-134


15. Dias JCP, Schofield CJ. The evolution ofChagas disease (American trypanosomiasis)control after 90 years since Carlos Chagas’discovery. Men Inst Oswaldo Cruz 1999;94 (suppl. 1): 103-121

16. Centers for Disease Control and Prevention(CDC): Blood donor screening for Chagasdisease-United States, 2006-2007. MMWRMorb Mortal Wkly Rep 2007; 56: 141-143

17. Piron M, Verges M, Munoz J, CasamitjanaN, Sanz S, Maymó RM, Hernández JM, PuigL, Portús M, Gascón J, Sauleda S. Seropreva-lence of Trypanosoma cruzi infection in at-risk blood donors in Catalonia (Spain).Transfusion 2008; 48: 1862-1868

18. Guerri-Guttenberg RA, Ciannameo A, DiGirolamo C, Milei JJ. Chagas disease: anemerging public health problem in Italy? In-fez Med 2009; 17: 5-13

19. Société de pathologie exotique: Chagas dis-ease. American trypanosomiasis. Recom-mendation for non-endemic zones. MedTrop (Mars) 2010; 70: 131-132

20. Azogue E. Women and congenital Chagas’disease in Santa Cruz, Bolivia: epidemiolog-ical and sociocultural aspects. Soc Sci Med1993; 37: 503-511

21. Riera C, Guarro A, Kassab HE, Jorba JM,Castro M, Angrill R, Gállego M, Fisa R, Mar-tin C, Lobato A, Portús M. Congenital trans-mission of Trypanosoma cruzi in Europe(Spain): a case report. Am J Trop Med Hyg2006; 75: 1078-1081

22. Dias JC, Schofield CJ, Machado EM, Fernan-des AJ. Ticks, ivermectin, and experimentalChagas disease. Mem Inst. Oswldo Cruz2005; 100: 829-832

23. Macedo AM, Machado CR, Oliveira RP, Pe-na SD. Trypanosoma cruzi: Genetic struc-ture of populations and relevance of genet-ic variability to the pathogenesis of Chagasdisease. Mem Inst Oswaldo Cruz 2004; 99:1-12

24. Manoel-Caetano Fda S, Silva AE. Implica-tions of genetic variability of Trypanosomacruzi for the pathogenesis of Chagas dis-ease. Cad Saude Publica 2007; 23: 2263-2274

25. Torrico F, Castro M. Enfermedad de Chagas.In: Medicina tropical, CD-Rom, ITGPRESS;2002; ISBN 90-76070-237

26. Moncayo A, Ortiz Yanine MI. An update onChagas disease (human American try-

panosomiasis). Ann Trop Med parasitol2006; 100: 663-677

27. Ochs DE, Hnilica VS, Moser DR, Smith JK,Kirchhoff LV. Postmortem diagnosis of au-tochthonous acute chagasic myocarditis bypolymerase chain reaction amplification ofa species-specific DNA sequence of Try-panosoma cruzi. Am J Trop Med Hyg 1996;54: 526-529

28. Gironés N, Cuervo H, Fresno M. Trypanoso-ma cruzi-induced molecular mimicry andChagas’ disease. Curr Top Microbiol Im-munol 2005; 296: 89-123

29. Kumar S, Tarleton RL. The relative contribu-tion of antibody production and CD8+ Tcell function to immune control of Try-panosoma cruzi. Parasite Immunol 1998;20: 207-216

30. Aliberti JC, Cardoso MA, Martins GA, Gazz-inelli RT, Vieira LQ, Silva JS. Interleukin-12mediates resistance to Trypanosoma cruziin mice and is produced by murinemacrophage in response to live trypo-mastigotes. Infect Immun 1996; 64: 1961-1967

31. Fresno M, Kopf M, Rivas L. Cytokines andinfectious diseases. Immunol Today 1997;18: 56-58

32. Gazzinelli RT, Oswald IP, Hieny S James SL,Sher A. The microbicidal activity of interfer-on-gamma-treated macrophages againstTrypanosoma cruzi involves an L-arginine-dependent, nitrogen oxide-mediated mech-anism inhibitable by interleukin-10 andtransforming growth factor-beta. Eur J Im-munol 1992; 22: 2501-2506

33. Munoz-Fernandez MA, Fernandez MA,Fresno M. Synergism between tumor necro-sis factor-alpha and interferon-gamma onmacrophage activation for the killing of in-tracellular Trypanosoma cruzi through a ni-tric oxide-dependent mechanism. Eur J Im-munol 1992; 22: 301-307

34. Silva JS, Morrissey PJ, Grabstein KH, MohlerKM, Anderson D, Reed SG. Interleukin 10and interferon gamma regulation of experi-mental Trypanosoma cruzi infection. J ExpMed 1992; 175: 169-174

35. Torrico F, Heremans H, Rivera MT, van Mar-ck E, Billiau A, Carlier Y. Endogenous IFN-gamma is required for resistance to acuteTrypanosoma cruzi infection in mice. J Im-munol 1991; 146: 3626-3632


36. Holscher C, Kohler G, Muller U. Defectivenitric oxide effector functions lead to ex-treme susceptibility of Trypanosoma cruzi-infected mice deficient in gamma interferonreceptor or inducible nitric oxide synthase.Infect Immun 1998; 66: 1208-1215

37. Castanos-Velez E, Maerlan S, Osorio LM,Aberg F, Biberfeld P, Orn A, Rottenberg ME.Trypanosoma cruzi infection in tumornecrosis factor receptor p55-deficient mice.Infect Immun 1998; 66: 2960-2968

38. Martin D, Tarleton R. Generation, specifici-ty, and function of CD8+ T cells in Try-panosoma cruzi infection. Immunol Rev2004; 201: 304-317

39. Avila HA, Sigman DS, Cohen LM, MillikanRC, Simpson L (1991) Polymerase chain re-action amplification of Trypanosoma cruzikinetoplast minicircle DNA isolated fromwhole blood lysates: diagnosis of chronicChagas’ disease. Mol Biochem Parasitol 48:211-221

40. Kirchhoff LV, Votava JR, Ochs DE, MoserDR. Comparison of PCR and microscopicmethods for detecting Trypanosoma cruzi. JClin Microbiol 1996; 34: 1171-1175

41. Mady C, de Moraes AV, Galiano N, Dé-court LV. Hemodynamic study of the inde-terminate form of Chagas’ disease. Arq BrasCardiol 1982; 38: 271-275

42. Sicca RE, Gonzalez Cappa SM, Sanz OP,Mirkin G. Peripheral nervous system in-volvement in human and experimentalchronic American trypanosomiasis. Bull SocPathol Exot 1995; 88: 156-163

43. Lopes ER. Sudden death in patients withChagas disease. Mem Inst Oswaldo Cruz1999; 94 (Suppl. 1): 321-324

44. Karp CL, Auwaerter PG. Coinfection withHIV and Tropical Infectious Diseases. I. Pro-tozoal Pathogens. Clin Infect Dis 2007; 45:1208-1213

45. Andrade LO, Machado CR, Chiari E, PenaSD, Macedo AM. Trypanosoma cruzi: roleof host genetic background in the differen-tial tissue distribution of parasite clonal pop-ulations. Exp Parasitol 2002; 100: 269-275

46. Tibayrenc M. Human genetic diversity andthe epidemiology of parasitic and othertransmissible diseases. Adv Parasitology2007; 64: 377-462

47. Layrisse Z, Fernandez MT, Montagnani S,Matos M, Balbas O, Herrera F, Colorado IA,

Catalioti F, Acquatella H. HLA-C*03 is a riskfactor for cardiomyopathy in Chagas dis-ease. Human Immunol 2000; 61: 925-929

48. Garcia Borras S, Racca L, Cotorruelo C,Biondi C, Beloscar J, Racca A. Distributionof HLA-DRB1 alleles in Argentinian patientswith Chagas’ disease cardiomyopathy. Im-munol Invest 2009; 38: 268-275

49. Fae KC, Drigo SA, Cunha-Neto E, Ianni B,Mady C, Kalil J, Goldberg AC. HLA and ß-myosin heavy chain do not influence sus-ceptibility to Chagas’ disease cardiomyopa-thy. Microbes and Infection 2000; 2: 745-751

50. Yacoub S, Birks EJ, Slavik Z, Henein M. Ear-ly detection of myocardial dysfunction inChagas disease using novel echocardio-graphic indices. Trans R Soc Trop Med Hyg2003; 97: 528-534

51. Dubner S, Schapachnik E, Riera AR, ValeroE. Chagas disease: state-of-the-art of diagno-sis and management. Cardiol J 2008; 15:493-504

52. Bern C, Montgomery SP, Herwaldt BL, Ras-si A Jr, Marin-Neto JA, Dantas RO, MaguireJH, Acquatella H, Morillo C, Kirchhoff LV,Gilman RH, Reyes PA, Salvatella R, MooreAC. Evaluation and treatment of Chagas dis-ease in the United States: a systematic re-view. JAMA 2007; 298: 2171-2181

53. Viotti RJ, Vigliano C, Laucella S, Lococo B,Petti M, Bertocchi G, Ruiz Vera B, ArmentiH. Value of echocardiography for diagnosisand prognosis of chronic Chagas diseasecardiomyopathy without heart failure. Heart90: 655-660

54. Acuatella H. Echocardiography in Chagasheart disease. Circulation 2004; 115: 1124-1131

55. Shehata ML, Turkbey EB, Vogel-Claussen J,Bluemke DA. Role of cardiac magnetic res-onance imaging in assessment of nonis-chemic cardiomyopathies. Top Magn ResonImaging 2008; 19: 43-57

56. Tanowitz HB, Machado FS, Jelicks LA Shi-rani J, de Carvalho AC, Spray DC, FactorSM, Kirchhoff LV, Weiss LM. Perspectiveson Trypanosoma cruzi-induced heart dis-ease (Chagas disease). Prog Cardiovasc Dis2009; 51: 524-539

57. Braga MS, Lauria-Pires L, Argañaraz ER,Nascimento RJ, Teixeira AR. Persistent infec-tions in chronic Chagas’ disease patients


treated with anti-Trypanosoma cruzi ni-troderivatives. Rev Inst Med Trop Sao Paulo2000; 42: 1571-1561

58. Lauria-Pires L, Braga MS, Vexenat AC, NitzN, Simões-Barbosa A, Tinoco DL, TeixeiraAR. Progressive chronic Chagas heart dis-ease ten years after treatment with anti-Try-panosoma cruzi nitroderivatives. Am J TropMed Hyg 2000; 63: 111-118

59. Tafuri WL, Maria TA, Lopes ER, ChapadeiroE. Electron microscopy of the myocardiumin human trypanosomiasis cruzi. Rev InstMed Trop Sao Paulo 1973; 15: 347-370

60. Rossi MA. Connective tissue skeleton in thenormal left ventricle and in hypertensive leftventricular hypertrophy and chronic chaga-sic myocarditis. Med Sci Monit 2001; 7:820-832

61. Oliveira JS. A natural human model of intrin-sic heart nervous system denervation: Cha-gas’ cardiopathy. Am Heart J 1985; 110:1092-1098

62. Py M, Pedrosa R, Silveira J, Medeiros A, An-dre C. Neurological manifestations in Cha-gas disease without cardiac dysfunction:correlation between dysfunction of theparasympathetic nervous system and whitematter lesions in the brain. J Neuroimaging2009; 19: 332-336

63. Engman DM, Leon JS. Pathogenesis of Cha-gas heart disease: role of autoimmunity. Ac-ta Trop 2002; 81: 123-132

64. Cunha-Neto E, Bilate AM, Hyland KV Fonse-ca SG, Kalil J, Engman DM. Induction of car-diac autoimmunity in Chagas heart disease:a case for molecular mimicry. Autoimmuni-ty 2006; 39: 41-54

65. Reis DD, Gazzinelli RT, Gazzinelli G, ColleyDG. Antibodies to Trypanosoma cruzi ex-press idiotypic patterns that can differenti-ate between patients with asymptomatic orsevere Chagas’ disease. J Immunol 1993;150: 1611-1618

66. Wallukat G, Nissen E, Müller J, BrinckmannR, Schimke I, Kunze R. The pathophysiolog-ical role of autoantibodies directed to G-protein coupled receptors and therapeuticstrategies of antibody removal. In: Brinck-mann R, Kunze R (eds) G-protein coupledreceptors and autoantibodies. Pabst Sci-ence Publishers, 2002; pp. 7-47

67. Masuda MO, Levin M, De Oliveira SF, DosSantos Costa PC, Bergami PL, Dos Santos

Almeida NA, Pedrosa RC, Ferrari I, Hoe-beke J, Campos de Carvalho AC. Function-ally active cardiac antibodies in chronicChagas’ disease are specifically blocked byTrypanosoma cruzi antigens. FASEB J 1998;12: 1551-1558

68. Gouldson PR, Higgs C, Smith RE, Dean MK,Gkoutos GV, Reynolds CA. Dimerizationand domain swapping in G-protein-coupledreceptors: a computational study. Neu-ropsychopharmacology 2000; 23: S60-77

69. Levin MJ, Hoebeke J. Cross-talk betweenanti-beta1-adrenoceptor antibodies in dilat-ed cardiomyopathy and Chagas’ heart dis-ease. Autoimmunity 2008; 41: 429-433

70. Wallukat G, Wollenberger A. Effects of theserum gamma globulin fraction of patientswith allergic asthma and dilated cardiomy-opathy on chronotropic beta adrenoceptorfunction in cultured neonatal rat heart myo -cytes. Biomed Biochim Acta 1987; 46:S634-639

71. Limas CJ, Goldenberg IF, Limas C. Autoanti-bodies against beta-adrenoceptors in hu-man idiopathic dilated cardiomyopathy.Circ Res 1989; 64: 97-103

72. Sterin-Borda L, Cossio PM, Gimeno MF, Gi-meno AL, Diez C, Laguens RP, Meckert PC,Arana RM: Effect of chagasic sera on the ratisolated atrial preparation: immunological,morphological and function aspects. Car-diovasc Res 1976; 10: 613-622

73. Borda E, Pascual J, Cossio P, De La Vega M,Arana R, Sterin-Borda L. A circulating IgG inChagas’ disease which binds to beta-adrenoceptors of myocardium and modu-lates their activity. Clin Exp Immunol 1984;57: 679-686

74. Yoshikawa T, Baba A, Nagatomo Y. Autoim-mune mechanism underlying dilated car-diomyopathy. Circ J 2009; 73: 602-607

75. Jahns R, Boivin V, Hein L, Triebel S, Anger-mann CE, Ertl G, Lohse MJ. Direct evidencefor a beta 1-adrenergic receptor-directedautoimmune attack as a cause of idiopathicdilated cardiomyopathy. J Clin Invest 2004;113: 1419-1429

76. Jahns R, Boivin V, Lohse MJ. Beta 1-adrener-gic receptor-directed autoimmunity as acause of dilated cardiomyopathy in rats. IntJ Cardiol 2006; 112: 7-14

77. Elies R, Fu LX, Eftekhari P, Wallukat G,Schulze W, Granier C, Hjalmarson A, Hoe-


beke J. Immunochemical and functionalcharacterization of an agonist-like mono-clonal antibody against the M2 acetyl-choline receptor. Eur J Biochem 1998; 251:659-666

78. Christ T, Wettwer E, Dobrev D, Adolph E,Knaut M, Wallukat G, Ravens U. Autoanti-bodies against the beta1 adrenoceptor frompatients with dilated cardiomyopathy pro-long action potential duration and enhancecontractility in isolated cardiomyocytes. JMol Cell Cardiol 2001; 33: 1515-1525

79. Labovsky V, Smulski CR, Gómez K, Levy G,Levin MJ. Anti-beta1-adrenergic receptorautoantibodies with chronic Chagas heartdisease. Clin Exp Immunol 2007; 148: 440-449

80. Sterin-Borda L, Perez Leiros C, Wald M, Cre-maschi G, Borda E: Antibodies to beta 1 be-ta 2 adrenoreceptors in Chagas’ disease.Clin Exp Immunol 1988; 74: 349-354

81. Magnusson Y, Wallukat G, Waagstein F,Hjalmarson A, Hoebeke J: Autoimmunity inidiopathic dilated cardiomyopathy. Charac-terization of autoantibodies against the be-ta 1-adrenoceptor with positive chronotrop-ic effect. Circulation 1994; 89: 2760-2767

82. Krause EG, Bartel S, Beyerdorfer I, WallukatG. Activation of cyclic AMP-dependent pro-tein kinase in cardiomyocytes by anti-beta1-adrenoceptor autoantibodies from pa-tients with idiopathic dilated cardiomyopa-thy. Blood Press 1996; Suppl 3: 37-40

83. Ford CE, Skiba NP, Bae H, Daaka Y, Reuve-ny E, Shekter LR, Rosal R, Weng G, Yang CS,Iyengar R, Miller RJ, Jan LY, Lefkowitz RJ,Hamm HE. Molecular basis for interactionsof G protein betagamma subunits with ef-fectors. Science 1998; 280: 1271-1274

84. Jane-wit D, Altuntas CZ, Johnson JM, YongS, Wickley PJ, Clark P, Wang Q, Popovic ZB,Penn MS, Damron DS, Perez DM, TuohyVK. Beta 1-adrenergic receptor autoanti-bodies mediate dilated cardiomyopathy byagonistically inducing cardiomyocyte apop-tosis. Circulation 2007; 116: 399-410

85. Goin JC, Leiros CP, Borda E, Sterin-Borda L.Interaction of human chagasic IgG with thesecond extracellular loop of the humanheart muscarinic acetylcholine receptor:functional and pathological implications.FASEB J 1997; 11: 77-83

86. Goin JC, Sterin-Borda L, Bilder CR, VarricaLM, Iantorno G, Ríos MC, Borda E. Func-tional implications of circulatin muscariniccholinergic receptor autoantibodies in Cha-gasic patients with achalasia. Gastroenterol-ogy 1999; 117: 798-805

87. Sterin-Borda L, Goin JC, Bilder CR, IantornoG, Hernando AC, Borda E. Interaction of hu-man chagasic IgG with human colon mus-carínico acetylcholine receptor: molecularand functional evidence. Gut 2001; 49:699-705

88. Leiros CP, Sterin-Borda L, Borda ES, Goin JC,Hosey MM. Desensitization and sequestra-tion of human m2 muscarinic acetylcholinereceptors by autoantibodies from patientswith Chagas’ disease. J Biol Chem 1997;272: 12989-12993

89. Elies R, Ferrari I, Wallukat G, Lebesgue D,Chiale P, Elizari M, Rosenbaum M, HoebekeJ, Levin MJ. Structural and functional analy-sis of the B cell epitopes recognized by an-ti-receptor autoantibodies in patients withChagas’ disease. Journal of Immunology1996; 157: 4203-4211

90. Wallukat G, Nissen E, Morwinski R, MüllerJ. Autoantibodies against the beta- and mus-carinic receptors in cardiomyopathy. Herz2000; 25: 261-266

91. Wallukat G, Munoz Saravia GS, HaberlandA, Bartel S, Araujo R, Valda G, Duchen D,Diaz Ramirez I, Borges AC, Schimke I. Dis-tinct patterns of autoantibodies against G-protein-coupled receptors in Chagas’ car-diomyopathy and megacolon. Their poten-tial impact for early risk assessment inasymptomatic Chagas’ patients. J Am CollCardiol 2010; 55: 463-468

92. Munoz Saravia SG, Haberland A, Bartel S,Araujo R, Valda G, Duchen D, DiazRamirez I, Borges AC, Wallukat G, SchimkeI. Distinct patterns of autoantibodies againstG-protein-coupled receptors in Chagas’ car-diomyopathy and megacolon: their poten-tial impact for early risk assessment inasymptomatic Chagas’ patients. J Am CollCardiol 2010; 56: 526-527

93. Gallerano RH, Marr JJ, Sosa RR. Therapeuticefficacy of allopurinol in patients withchronic Chagas’ disease. Am J Trop MedHyg 1990; 43: 159-166

94. Viotti R, Vigliano C, Lococo B, AlvarezMG, Petti M, Bertocchi G, Armenti A. Side


effects of benznidazole as treatment inchronic Chagas disease: fears and realities.Expert Rev Anti Infect Ther 2009; 7: 157-163

95. Rassi A Jr, Rassi A,, Marin-Neto JA. Chagasdisease. Lancet 2010; 375: 1388-1402

96. Garcia S, Ramos CO, Senra JF, Vilas-BoasF, Rodrigues MM, Campos-de-CarvalhoAC, Ribeiro-Dos-Santos R, Soares MBTreatment with benznidazole during thechronic phase of experimental Chagas’disease decreases cardiac alterations. An-timicrob Agents Chemother 2005; 49:1521-1528

97. Marian-Neto JA, Rassi AJr; Morillo CA,Avezum A, Connolly SJ, Sosa-Estani S,Rosas F, Yusuf S. BENEFIT Investigators Ra-tionale and design of a randomized place-bo-controlled trial assessing the effects ofetiologic treatment in Chagas’ cardiomy-opathy: the BENznidazole Evaluation ForInterrupting Trypanosomiasis (BENEFIT).Am Heart J 2008; 156: 37-43

98. El-Sayed NM, Myler PJ, Bartholomeu DC,Nilsson D, Aggarwal G, Tran AN, GhedinE, Worthey EA, Delcher AL, Blandin G,Westenberger SJ, Caler E, Cerqueira GC,Branche C, Haas B, Anupama A, Arner E,Aslund L, Attipoe P, Bontempi E, BringaudF, Burton P, Cadag E, Campbell DA, Car-rington M, Crabtree J, Darban H, da Sil-veira JF, de Jong P, Edwards K, Englund PT,Fazelina G, Feldblyum T, Ferella M, FraschAC, Gull K, Horn D, Hou L, Huang Y, Kind-lund E, Klingbeil M, Kluge S, Koo H, Lacer-da D, Levin MJ, Lorenzi H, Louie T, Macha-do CR, McCulloch R, McKenna A, MizunoY, Mottram JC, Nelson S, Ochaya S, Osoe-gawa K, Pai G, Parsons M, Pentony M, Pet-tersson U, Pop M, Ramirez JL, Rinta J,Robertson L, Salzberg SL, Sanchez DO,Seyler A, Sharma R, Shetty J, Simpson AJ,Sisk E, Tammi MT, Tarleton R, Teixeira S,Van Aken S, Vogt C, Ward PN, WicksteadB, Wortman J, White O, Fraser CM, StuartKD, Andersson B. The genome sequenceof Trypanosoma cruzi, etiologic agent ofChagas disease. Science 2005; 15; 309:409-415

99. Muratore CA, Baranchuk A. Current andemerging therapeutic options for the treat-ment of chronic chagasic cardiomyopathy.Vasc Health Risk Manag 2010; 6: 593-601

100. Biolo A, Ribeiro AL, Clausell N. Chagascardiomyopathy – where do we stand after a hundred years? Prog CardiovascDis 2010; 52: 300-316

101. Botoni FA, Poole-Wilson PA,Ribeiro AL,Okonko DO, Oliveira BM, Pinto AS, Teix-eira MM, Teixeira AL Jr, Reis AM, DantasJB, Ferreira CS, Tavares WC Jr, Rocha MO.A randomized trial of carvedilol afterrenin-angiotensin system inhibition inchronic Chagas cardiomyopathy. AmHeart J 2007; 153: 544.e1-8

102. Issa VS, Amaral AF, Cruz FD, Ferreira SM,Guimarães GV, Chizzola PR, Souza GE,Bacal F, Bocchi EA. Beta-blocker therapyand mortality of patients with Chagas car-diomyopathy: a subanalysis of the RE-MADHE prospective trial. Circ Heart Fail2010; 3: 82-88

103. Sousa, Xavier SS, Freitas GR, Hasslocher-Moreno A. Prevention strategies of car-dioembolic ischemic stroke in Chagas’ dis-ease. Arq Bras Cardiol 2008; 91: 306-310

104. Mady C, Cardoso RH, Barretto AC, da LuzPL, Bellotti G, Pileggi F. Survival and pre-dictors of survival in patients with conges-tive heart failure due to Chagas’ cardiomy-opathy. Circulation 1994; 90: 3098-3102

105. Bertolino ND, Villafanha DF, Cardinalli-Ne-to A, Cordeiro JA, Arcanjo MJ, Theodor-opoulos TA, Bestetti RB. Prognostic impactof Chagas’ disease in patients awaitingheart transplantation. J Heart Lung Trans-plant 2010; 29: 449-453

106. Bocchi EA, Fiorelli A. First GuidelineGroup for Heart Transplantation of theBrazilian Society of Cardiology: The Brazil-ian experience with heart transplantation:a multicenter report. J Heart Lung Trans-plant 2001; 20: 637-645

107. Parra AV, Rodrigues V, Cancella S,Cordeiro JA, Bestetti RB. Impact of socio -economic status on outcome of a Brazilianheart transplant recipients cohort. Int JCardiol 2008; 125: 142-143

108. Campos SV, Strabelli TM, Amato Neto V,Silva CP, Bacal F, Bocchi EA, Stolf NA. Riskfactors for Chagas’ disease reactivation after heart transplantation. J Heart LungTransplant 2008; 27: 597-602

109. Moreira LF, Galantier J, Benício A, LeirnerAA, Cestari IA, Stolf NA. Left ventricularcirculatory support as bridge to heart


transplantation in Chagas’ disease car-diomyopathy. Artif Organs 2007; 31: 253-258

110. Vilas-Boas F, Feitosa GS, Soares MB, MotaA, Pinho-Filho JA, Almeida AJ, AndradeMV, Carvalho HG, Dourado-Oliveira A,Ribeiro-dos-Santos R. Early results of bonemarrow cell transplantation to the myo -cardium of patients with heart failure dueto Chagas disease. Arq Bras Cardiol 2006;87: 159-166

111. Clinical Trials: Cell therapy in Chagas car-diomyopathy 2010 http/www.clinicaltri-als.gov/ct2/show/NCT00349271

112. Labovsky V, Smulski CR, Gómez K, LevyG, Levin MJ. Anti-beta1-adrenergic recep-tor autoantibodies in patients with chronicChagas heart disease. Clin Exp Immunol2007; 148: 440-449

113. Wallukat G, Reinke P, Dörffel WV, LutherHP, Bestvater K, Felix SB, Baumann G. Re-moval of autoantibodies in dilated car-diomyopathy by immunoadsorption. Int JCardiol 1996; 54: 191-195

114. Dörffel WV, Felix SB, Wallukat G, BrehmeS, Bestvater K, Hofmann T, Kleber FX, Bau-mann G, Reinke P. Short-term hemody-namic effect of immunoadsorption in dilat-ed cardiomyopathy. Circulation 1997; 95:1994-1997

115. Felix SB, Staudt A, Dorffel WV, Stangl V,Merkel K, Pohl M, Döcke WD, Morgera S,Neumayer HH, Wernecke KD, WallukatG, Stangl K. Hemodynamic effects of im-munoadsorption and subsequent im-munoglobulin substitution in dilated car-diomyopathy: three-month results from arandomized study. J Am Coll Cardiol2000; 35: 1590-1598

116. Müller J, Wallukat G, Dandel M, Bieda H,Brandes K, Spiegelsberger S, Nissen E,Kunze R, Hetzer R. Immunoglobulin ad-sorption in patients with idiopathic dilatedcardiomyopathy. Circulation 2000; 101:385-391

117. Schimke I, Müller J, Priem F, Kruse I, SchönB, Stein J, Kunze R, Wallukat G, Hetzer R.Decreased oxidative stress in patients withidiopathic dilated cardiomyopathy oneyear after immunoglobulin adsorption. JAm Coll Cardiol 2001; 38: 178-783

118. Wallukat G, Müller J, Hetzer R. Specific re-moval of beta1-adrenergic autoantibodies

from patients with idiopathic dilated car-diomyopathy. N Engl J Med 2002; 347:1806

119. Schimke I, Müller J, Dandel M, GremmelsHD, Bayer W, Wallukat B, Wallukat G,Hetzer R. Reduced oxidative stress in par-allel to improved cardiac performance oneyear after selective removal of anti-beta 1-adrenoreceptor autoantibodies in patientswith idiopathic dilated cardiomyopathy:data of a preliminary study. J Clin Apher2005; 20: 137-142

120. Dörffel WV, Wallukat G, Dörffel Y, FelixSB, Baumann G. Immunoadsorption in id-iopathic dilated cardiomyopathy, a 3-yearfollow-up. Int J Cardiol 2004; 97: 529-534

121. Hessel FP, Wegner C, Müller J, Glaveris C,Wasem J. Economic evaluation and sur-vival analysis of immunoglobulin adsorp-tion in patients with idiopathic dilated car-diomyopathy. Eur J Health Econ 2004; 5:58-63

122. Dandel M, Wallukat G, Englert A,Lehmkuhl HB, Knosalla C, Hetzer R.Longterm outcome after beta1 adrenore-ceptor autoantibody removal in hearttransplant candidates with dilated car-diomyopathy. J Am Col Cardiol 2011; 57(17) Abstr E194

123. Doesch AO, Mueller S, Konstandin M, Ce-lik S, Kristen A, Frankenstein L, Goeser S,Kaya Z, Zugck C, Dengler TJ, Katus HA. Ef-fects of protein A immunoadsorption inpatients with chronic dilated cardiomyopa-thy. J Clin Apher 2010; 25: 315-322

124. Nagatomo Y, Baba A, Ito H, Naito K,Yoshizawa A, Kurita Y, Nakamura I,Monkawa T, Matsubara T, Wakabayashi Y,Ogawa S, Akaishi M, Yoshikawa T. Specif-ic immunoadsorption therapy using a tryp-tophan column in patients with refractoryheart failure due to dilated cardiomyopa-thy. J Clin Apher 2011; 26: 1-8

125. Marquis JK, Grindel JM. Toxicological eval-uation of oligonucleotide therapeutics.Curr Opin Mol Ther 2000; 2: 258-63

126. Keefe AD, Schaub RG. Aptamers as candi-date therapeutics for cardiovascular indi-cations. Curr Opin Pharmacol 2008; 8:147-152

127. Bouchard PR, Hutabarat RM, ThompsonKM. Discovery and development of thera-peutic aptamers. Annu Rev PharmacolToxicol 2010; 50: 237-257


128. Keefe AD, Pai S, Ellington A. Aptamers astherapeutics. Nature Rev 2010; 9: 537-550

129. Schimke I, Haberland A, Kage A, WallukatG, Dahmen C. EP2011/060572. Aptamersthat inhibit interaction between antibodyand 2nd extracellular loop of human be-ta1-adrenergic receptor (29.06.2010)

130. Aptamers for treatment and diagnosis ofautoantibody based dilated cardiomyopa-thy (28.07.2010 | Ref.Nr. 09014)www.ipal.de/t/Life-Science

131. Rönspeck W, Kunze R, Wallukat G. EP1086955. Peptide gegen DCM hervor-rufende Autoantikörper (21.09.1999)

132. Jahns R, Jahns V, Lohse MJ, Palm D. US2009/0215675: Means for the inhibitionof anti-adrenergic receptor antibodies(Aug. 27, 2009)

133. Munoz Saravia SG, Haberland A, WallukatG, Schimke I. Chronic Chagas’ heart dis-ease: a disease on its way to becoming aworldwide health problem: epidemiology,etiopathology, treatment, pathogenesisand laboratory medicine. Heart Fail Rev2010; [Epub ahead of print]

134. Wallukat G, Podlowski S, Nissen E, Mor-winski R, Csonka C, Tosaki A, Blasig IE.Functional and structural characterizationof anti-beta1-adrenoceptor autoantibodiesof spontaneously hypertensive rats. MolCell Biochem 2003; 251: 67-75

135. Nikolaev VO, Boivin V, Störk S, Anger-mann CE, Ertl G, Lohse MJ, Jahns R. A nov-el fluorescence method for the rapid de-tection of functional beta1-adrenergic re-ceptor autoantibodies in heart failure. JAm Coll Cardiol 2007; 50: 423-431

136. Jahns R, Boivin V, Siegmund C, InselmannG, Lohse MJ, Boege F. Autoantibodies ac-

tivating human beta1-adrenergic receptorsare associated with reduced cardiac func-tion in chronic heart failure. Circulation1999; 99: 649-654

137. Limas CJ, Goldenberg IF, Limas C. Assess-ment of immune modulation of beta-adrenergic pathways in human dilated car-diomyopathy: influence of methodologicfactors. Am Heart J 1992; 123: 967-970

138. Del Corsso C, de Carvalho AC, MartinoHF, Varanda WA. Sera from patients withidiopathic dilated cardiomyopathy de-crease Ca in cardiomyocytes isolated fromrabbits. Am J Physiol Heart Circ Physiol2004; 287: H1928-1936

Acknowledgements

We are grateful to “Deutsche Gesellschaft fürKlinische Chemie und Laboratoriumsmedi-zin” and “Europäischer Fonds für regionaleEntwicklung” for providing financial supportto S.G. Munoz Saravia.

Correspondence addressProf. Ingolf Schimke, M.D.Medizinische Klinik mit Schwerpunkt Kardiologie, Pulmologie und Angiologie CCMCharité – Universitätsmedizin BerlinCharité-Platz 110117 BerlinGermany [email protected]

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