Biomarker Diagnosis for Alzheimer's Disease

Biomarker Diagnosis for

Alzheimer’s Disease

Trinh Xuan Son

Saw Thu Wah

Thet Su Win

Introduction • Alzheimer’s disease (AD)

• Biomarkers definition

Biomarkers for AD Biomarkers in CSF

Biomarkers in Blood

Genetic biomarkers

Techniques for detect biomarkers

- ELISA

- miRNA microarray and RT-PCR

- MS

Conclusion

overview

“Re”- defining Alzheimer’s disease AD is a progressive neurodegenerative disorder that culminates

in end-organ (brain) failure which manifests as dementia.

AD can be conceptualized as having two major stages:

1) Preclinical (pre-symptomatic)

2) Symptomatic - Prodromal (incipient/MCI)

- Dementia of the Alzheimer type

Amyloid-beta metabolism and related neurotoxic cascades

J.L. Cummings / Alzheimer’s & Dementia 7 (2011) e13–e44

• A biomarker is an object that measured and evaluated as an indicator of normal biologic processes, pathogenic processes or pharmacologic responses to therapeutic intervention

What is a biomarker?

Biomarker

Detect disease

Stage disease

Monitor progression/ recurrence

Treatment efficacy

Response to treatment

Longitudinal changes of Alzheimer disease

biomarkers during the disease progression.

Babić et al: CSF core and developing biomarkers in diagnosis of AD, Croat Med J. 2014;55:347-65

Characteristics of Alzheimer disease (AD)

biomarkers


Biomarkers for AD in CSF

Diagnostic usefulness of established Alzheimer disease biomarkers


Genetic markers - 1

• Mutations in the genes encoding amyloid

precursor protein (APP), presenilin 1

(PSEN1) and presenilin 2 (PSEN2) are

responsible for early-onset autosomal

dominant AD

• more than 30 different APP missense

mutations have been identified and

approximately 25 of these are pathogenic,

in most cases resulting in autosomal

dominant early-onset AD.

• A673V – autosomal recessive AD

• A673T – strong protective effect

Genetic markers - 2

• Mutations in PSEN1 are the most common

cause of early-onset AD and account for

18–50% of autosomal dominant early-onset

AD

• Missense mutations in the PSEN2 gene

causing early-onset AD are rare and show

an older age of onset compared with

PSEN1

Genetic markers - 3

• APOE isoforms are also related with AD

• APOE E4 allele increases the risk of

sporadic late-onset AD

• circulating microRNAs (miRNAs) in the

cerebrospinal fluid (CSF) and blood serum

of AD patients can be used as biomarkers

in AD diagnosis

Technology for AD biomarkers

Analytical method Biomarker

ELISA Aβ42, tau, proteins

miRNA qPCR array miRNA (e.g. miR-125b, miR-132

family, miR-134 family, etc)

Mass Spectrometry Aβ species, proteins markers

DNA/RNA chips,

GeneChips Genetic markers

ELISA

Bio

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Inc. 2012

Internationally established biomarkers in CSF used

to diagnose AD

Humpel, C. Trends in Biotechnology, Jan 2011, vol.29, No.1

Aβ in CSF

CSF Aβ42 shows a highly significant

reduction in AD patients.

level of shorter Aβ40 is unchanged or

inceased in AD.

it is suggested that Aβ42/Aβ40 ratio can

improve AD diagnosis.

Plasma levels of Aβ are increased in familial

AD and Down syndrome.

But results are inconsistent.

So plasma Aβ level is not specific for early

diagnosis.

Tau in CSF

Total tau is the second hallmark of AD.

total tau in CSF increase with age.

It significantly enhance in AD patients as

compared with age control subjects.

Phosphorylated tau also increase in AD.

Tau-related biomarkers in peripheral blood do

not seem to be useful in AD

miRNA in AD

• Many previous studies have documented that a

number of miRNA (such as miR-9, miR-29a,

miR-29b, miR101, miR-125b and miR-181c)

were dysregulated in AD brain.

• They play a vital role in pathogenesis of AD.

– miRNA are proposed to be a novel

biomarkers for AD diagnosis.

miRNA qPCR array

http://www.tebu-bio.com/?module=tech-

info&id_cms=892&type_cms=3#.VN4OhgEv8V0

http://www.tebu-bio.com/?module=tech-

info&id_cms=892&type_cms=3#.VN4OhgEv8V miRNA qPCR array

Validation by RT-PCR

http://www.ncbi.nlm.nih.gov/core/lw/2.0/html

/tileshop_pmc/tileshop_pmc_inline.html?

MS base biomarkers - 1

S.Lista et al. / Progress in Neurobiology 101–102 (2013) 1–17







• ELISA

• WB

• RIA

Interpretation

• Analyze protein of upregulated and

downregulated

• Various types of protein based on

method of MS

• Proteins are concerned with

inflammatory pathway, immune

regulation , lipid peroxidation, apotosis

and neuroprotective activity, etc

• Currently, no proteins have been

satisfactorily recognized as AD marker

Conclusion - 1

• CSF biomarkers like Aβ (1-42) and tau (total

tau and phospho-tau) allows reliable,

sensitive and specific diagnosis of AD.

• But lumbar puncture and collection of CSF

is an invasive treatment with potential side

effects.

• Follow-up analysis is difficult.

• Although saliva and urine can be easily

collected, blood is the gold standard.

Conclusion - 2

• Blood plasma levels of Aβ proteins and tau

are inconsistent with sporadic AD.

• Circulating miRNAs are stable, reproducible

and possible candidates for novel non-

invasive biomarkers of AD.

• Proteins have a high potential as dynamic

biomarkers for diagnosis, prediction and

monitoring the development of the disease.

Conclusion - 3

• Efforts are underway to discover reliable

blood biomarkers.

• Early, fast and cheap diagnosis using

modern, ultrasensitive analytical methods

(e.g. microarrays or MS) will become

important for future diagnosis of AD.

Health & Medicine

Biomarker Diagnosis for Alzheimer's Disease