Pathophysiology of acute pancreatitis and identification of steps having

potential for intervention in order to control severity

Moderator- Prof. Anoop SarayaSpeaker- Dr. Moka Praneeth

Contents

• Introduction

• Animal models

• Pathophysiology & clinical phases

• Pathogenesis & possible interventions at each step

• Nutrition

• Probiotics & Antibiotics

• Therapeutic trials

Introduction

• Pathogenesis of AP elusive despite significant advances in the last

25 years

• Upto 25% of patients suffer from a severe attack of acute

pancreatitis

• A complex cascade of immunological events not only affects the

pathogenesis but also the course of the disease

Animal models

• Cerulein (Hyperstimulating - CCK analog) model

• Obstructive (Ligating the pancreatic duct) model

• Duct perfusion (induced by antegrade and retrograde infusion of

Sodium taurocholate) model

• Closed (distal & proximal to junction of hepatopancreatic duct)

duodenal loop models

• Choline-deficient and Ethionine supplement diet → severe

hemorrhagic acute pancreatitis with changes in CNS, liver)models

1st week 2nd weekHours 3rd-4th week

EARLY MIDDLEINITIAL LATE

Inappropriateactivation of

proteases

Necrosis

Microcirculatorydisorders

Progression ofnecrosis

Gut and biliarybacteria

Infection of necrosis

Altered intra-acinar protein traffic

Accumulation of trypsinogen in the interstitial space Macrophage

activation

PHASE

TIMING

MAJOREVENTS

? 19% 37%32% 12%DEATHS??

0 012% 28%

26%0%

0%5%

M.O.F.

InfectionCauses

R. Pezzilli, et al. Ospedali Italiani Chirurgia 2004; 10: 314-23. [1]

Pathophysiology and Clinical Phases of Acute Pancreatitis

ACUTE PANCREATITIS

TIME COURSE

0 12 24 36 48 60 72 84 96

hours from pain onset

ER presentation cytokine release organ failure

Cathepsin B blockade

Intravenous administration of Cathepsin B inhibitor, CA-074me (10

mg/kg) before induction of either secretagogue-elicited pancreatitis in

mice or duct infusion-elicited pancreatitis in rats markedly reduced the

extent of intrapancreatic trypsinogen activation and substantially

reduced the severity of both pancreatitis models

Van Acker GJ et al. Am J Physiol Gastrointest Liver Physiol. 2002

Trypsin activation and pH

Trypsinogen autoactivation requires an acidic pH and is enhanced in

the presence of Ca2+

The affinity of pancreatic trypsin inhibitor is greatest at a neutral pH

and is reduced at an acidic pH.

The generation of low-pH compartments within the acinar cell during

experimental pancreatitis may be important to trypsinogen activation

Figarella et al. Biol Chem Hoppe-Seyler 1988

Factors that determine the cellular fate of pancreatic acinar cell.

Pancreatic necrosis vs apoptosis

• Necrosis has classically been considered the major form of cell death in acute

pancreatitis , whereas apoptosis was suggested to mediate atrophy in the organ

• Severe acute pancreatitis (e.g., that induced by PD ligation in the opossum, by

choline-deficient and ethionine-supplemented diet in the mouse, and by

cerulein in the mouse) is associated primarily with necrosis, whereas mild acute

pancreatitis (e.g., that induced by PD ligation and by caerulein in the rat) is

associated primarily with apoptotic cell death

Apoptosis- affects severity

• Crambene (1-cyano 2-hydroxy 3-butene) administered 12 hours

before cerulein (in mice) results in a maximal time-dependent

pancreatic acinar cell apoptosis and reduces the severity of acute

pancreatitis maximally

Bhatia M et al. Biochem Biophys Res Commun. 1998

Inflammation

• Acinar cells are the site of onset of inflammatory cascade before the

innate immune response sets in

• NF-kB activation takes place in the acinar cells

• Nuclear translocation of NF-kB dimer p50/p65 causes transcription

of proinflammatory cytokines

Inflammation

• TNF-α is secreted by the acinar cells in cerulein model of acute

pancreatitis

• Pancreatic stellate cells, ductal cells and resident macrophages may

take part in the initial inflammatory activity

Pathophysiology of disease progression in Acute Pancreatitis

Innate immune response

• Neutrophils infiltrate the pancreas within 3 hours of initiating

experimental acute pancreatitis

• Neutrophils mediate their effects through MPO and proteases (eg:

elastase)

• Monocytes secrete IL-1, IL-6 and TNF-α

• IL-6 levels in the blood correlate with organ injury and severity of

pancreatitis in humans

Experimental Treatment of Acute Pancreatitis

More than 2,000 papers on the treatment of acute pancreatitis in

experimental models have been published in the last 10 years

About a half of these studies were carried out on edematous pancreatitis

Only a few of the substances tested in these studies have been applied in

clinical practice

Infliximab, a monoclonal TNF antibody, was tested in 100 rats randomly

assigned to 10 groups

In acute edematous pancreatitis and in severe necrotizing pancreatitis, the

drug significantly decreased serum amylase activity and the histopathologic

score

In severe necrotizing pancreatitis, it ameliorated both parenchymal and

fatty tissue necrosis of the pancreas

It also alleviated alveolar edema and ARDS-like pulmonary complications,

but this difference was not significant

Infliximab in Acute Pancreatitis

Oruc N, et al. Pancreas 2004; 28:E1-8. [26]

Targeting PAF – key molecule in murine models

• 290 patients with APACHE-2 score > 6

• Randomised to Lexipafant 100 mg/day i.v. × 7 days commenced within

72 hours of onset of symptoms

• Overall, 80/138 (58%) patients in the placebo group and 85/148 (57%) in

the lexipafant group developed one or more organ failures.

• The primary hypothesis was invalidated by the unexpected finding that

44% of patients had organ failure on entry into the study; only 39 (14%)

developed new organ failure.

• Deaths attributable to acute pancreatitis were not significantly different.

Johnson CD et al. Gut. 2001

Zou WG, et al. J Surg Res 2002; 103:121-6. (modified) [29]

0

20

40

60

80

100

IL-10 PlaceboN

ew o

rgan

fai

lure

(%

)

P NS

Villoria A, et al. Pancreatology 2003; 3:466. [30]

Interleukin-10 in Acute Pancreatitis

0

20

40

60

80

100

0 1 2 3 4 5 6 7 8Days

Sur

viva

l (%

)

IL-10Untreated

P<0.05

Efficacy in experimental studyNo effect in humans

Neutrophil elastase

• 75 patients with acute pancreatitis were matched to 20 controls

• NE activity was assessed using venous blood samples obtained on

patient admission and after 1, 2 and 14 days.

• NE activity was higher overall in patients with predicted severe AP

than in those with predicted mild AP (p = 0.027).

• Patients with respiratory failure had higher NE activity than those

without (p = 0.0024).

Novovic S et al. Scand J Clin Lab Invest. 2013

Resveratrol-mechanisms

• Administration of resveratrol can inhibit NF-kB activity as well as

reduce the concentrations of TNF-alpha, IL-6 and IL-1.

• It can also scavenge reactive oxygen species that are capable of

extensive tissue damage.

• Furthermore, resveratrol also exhibits anti-apoptotic properties via

regulation of apoptotic mediators such as Bax, Bcl-2, and caspase-3.

• It prevents Calcium overload, improves microcirculation and

alleviates SAP-induced histopathological distortions in the pancreas.

Jha RK et al. Front Biosci (Schol Ed). 2010

Resveratrol in Acute Pancreatitis

To evaluate the protective and antioxidative effect of resveratrol, a

stilbene derivative, in acute pancreatitis induced by tert-butyl

hydroperoxide injection

Changes in pancreata were much less pronounced in the rats which

received resveratrol for 8 days prior to tert-butyl hydroperoxide

injection

In this way it seems that stilbene derivatives may prevent pancreatic

cells from undergoing structural changes during acute pancreatitis

experimentally induced in rats

Lawinski M, et al. Pancreas 2005; 31:43-7. [27]

Resveratrol-therapeutic effect

• 72 male Sprague-Dawley rats randomised into sham operation

group, SAP group and RESV-group

• Pancreatitis was induced by intraductal administration of 0.1 mL/kg

4% sodium taurocholate.

• RESV was given intravenously at a dose of 20 mg/kg body weight.

LI ZD et al. World J Gastroenterol. 2006

Resveratrol-therapeutic effect

• All animals were killed at 3, 6, 12 h after induction of the model.

• RESV’s protective effect aginst lipid peroxidation reduced cellular

oxidative damage, as reflected by lower serum amylase, less severe

pancreatic lesions, normal pancreatic MDA levels, as well as

diminished neutrophil infiltration in pancreas.

LI ZD et al. World J Gastroenterol. 2006

Treatment of Acute Pancreatitis with Protease

Inhibitors

10 RCTs (n = 1036) evaluating the effects of protease inhibitors (Aprotinin

275000-800000 Units/day i.v. – 4 studies and Gabexate 600-4000 mg/day

i.v. infusion – 6 studies) in acute pancreatitis

Treatment with protease inhibitors did not significantly reduce the mortality

rate from acute pancreatitis (pooled risk difference, -0.03).

Seta T, et al. Eur J Gastroenterol Hepatol 2004; 16:1287-93. [37]

Treatment of Acute Pancreatitis with Protease Inhibitors

Subgroup analyses showed that protease inhibitors significantly

reduced the mortality rate in patients with moderate to severe

pancreatitis (pooled risk difference, -0.07)

There was no significant difference between protease inhibitors and

placebo in the formation of pancreatic pseudocysts, intra-abdominal

abscesses and need of surgery

Seta T, et al. Eur J Gastroenterol Hepatol 2004; 16:1287-93.

Microcirculatory alterations

• 88 male sprague Dawley rats randomised to controls (n =18), mild

AP (n=18), moderate AP (n=18), severe AP (n = 34)

• Within each group, rats were studied 0.5, 3.0, or 6.0 hours after

induction of pancreatitis, with DRS

• Total hemoglobin content in the pancreas remained constant

in all groups.

Bassi et al. J Am Coll Surg. 1994

Microcirculatory alterations

• Hemoglobin oxygenation increased significantly in rats in the control

group and in rats with mild pancreatitis for the duration of the

experiment, but not in rats with moderate or severe pancreatitis.

• Rats with severe pancreatitis had a significant decrease in ISO2 six

hours after the induction of pancreatitis compared with baseline

values as well as rats in control group studied after 6 hours

Bassi et al. J Am Coll Surg. 1994

Microcirculatory alterations

• There was marked variability in IHb and ISO2 at different locations

within the same pancreas in rats with severe pancreatitis, which

was not observed in the control group or in the rats with mild or

moderate pancreatitis.

Bassi et al. J Am Coll Surg. 1994

Modulating microrheological changes

• In female rats, 10 μg/kg cerulein s.c. was administered and 2 hours

later, microcirculation was tested by laser Doppler flowmetry on the

tongue and after performing laparotomy on the small intestine,

liver and pancreas prior to terminal blood sampling.

• From blood samples hematological parameters, blood pH, lactate

concentration, erythrocyte deformability, osmoscan parameters

and erythrocyte aggregation were tested.

Szentkereszty Z. Clin Hemorheol Microcirc. 2013

Modulating microrheological changes

• Compared to normal control in acute pancreatitis group severe

deterioration was noted in tissue microcirculation together with

impaired erythrocyte deformability and enhanced aggregation,

accompanied by acidic pH and increasing lactate concentration

• Improvement was found when using flunixin (s.c.), pentoxifylline

(i.p.) or enoxaparin (s.c.).

Szentkereszty Z. Clin Hemorheol Microcirc. 2013

Modulating microrheological changes

• These drugs could partly improve the blood flux on the surface of

the investigated organs

• Flunixin had the most expressed improving effects on micro-

rheological parameters.

• The improving effect of pentoxifylline on micro-rheological

parameters was not obvious (RBC deformability did not improve

better than in the other treated groups)

Szentkereszty Z. Clin Hemorheol Microcirc. 2013

Early fluid resuscitation reduces morbidity among patients with acute pancreatitis

• A retrospective study

• Stratification into early (: receiving ≥ 1/3 of total 72-hour fluid

volume within 24 hours of presentation) (n=340) or late (n= 94)

resuscitation

• Early resuscitation was associated with decreased SIRS at 24 hours

(15% vs 32%), 48 hours and 72 hours, as well as reduced organ

failure (5% vs 10%) at 72 hours and a reduced length of hospital stay

Warndorff et al. Clin Gastroenterol Hepatol. 2011

Type of fluids to be administered- RL vs NS

• RCT of 40 patients

• The volumes of fluids administered during a 24 hour period were

similar among patients given goal-directed or standard fluid

resuscitation.

• Goal-directed resuscitation did not significantly reduce incidence of

SIRS, compared with standard resuscitation (11.8% vs 13.0%, P = .85)

or levels of CRP after 24 hours (P = .75).

• There was a significant reduction in SIRS after 24 hours among

subjects resuscitated with RL vs NS (84% reduction vs 0% ; P = .035)

• Administration of RL also reduced levels of CRP, compared with NS

(51.5 vs 104 mg/dL; P = .02). Wu Bu et al. Clin Gastroenterol Hepatol. 2011

Quantity of fluids to be given

• Prospective cohort study of 247 adults with acute pancreatitis

• Administration of >4.1 l during the initial 24 h was significantly and

independently associated with persistent OF, acute collections, respiratory

insufficiency, and renal insufficiency.

• Administration of <3.1 l during the initial 24 h was not associated with OF, local

complications, or mortality.

• Patients who received between 3.1 and 4.1 l during the initial 24 h had an

excellent outcome.

Caution: Continuous monitoring should be done and cardiovascular and

renal morbidities should be taken into account

de Madaria et al. Am J Gastroenterol. 2011

September 1st, 2013

September 7th, 2013

October 26th, 2013

The Prevention of Infection of the Necrosis

Nutrition - Rationale

Hyper metabolic state

Total energy expenditure 1.5 x resting energy requirement

Nutrition depletion

Starvation

Preexisting protein-calorie malnutrition & micronutrient

deficiency

Crit care Med 1991;19:484-90; J parenter Enter Nutr 1989;13:26-29.

Parenteral Nutrition

Rationale against :

Pancreatic rest Poorly defined

Increased risk of sepsis Gut atrophy - increased bacterial translocation Hyperglycemia

Greater costs

Nutrition – who needs it?

Mild AP

70-80% recover within 4-7 days

Moderate to severe AP

– Ranson score > 3

– APACHE II > 8

– Necrotic pancreas

– Organ failure

Windsor et al. Gut 1998,42:431-35;

Kalfatentzos et al. Br J Surg 1997,84:1665-69

Parenteral Nutrition

Nine uncontrolled retrospective studies

Safe, well tolerated with few complications

No impact on the outcome

TPN

Prospective randomized controlled trial

54

TPN IV F

Duration of hospital stay 16 10

Line sepsis 10 1

Sax et al. Am J Surg 1987,153:117-22Sax et al. Am J Surg 1987,153:117-22

Enteral feeding vs Total parenteral nutrition

6 RCTs of patients with APACHE-2 score ≥ 8

Randomised to TEN vs TPN

Compared with TPN, EN was associated with a significantly lower incidence of:

pancreatic infection complications (P < .001), MOF (P = .003), surgical interventions (P < .001), and mortality (P = .167).

There was no statistic significance in non-pancreatitis-related complications (P = .017).

However, EN had a significantly higher incidence of non-infection-related complications (RR = 2.697, 95% CI 1.947∼3.735, P = .994).

Heming Quan et al. Gastroenterol Res Pract. 2011

Early Naso-Gastric vs. Naso-Jejunal Feeding

in Severe Acute Pancreatitis – meta-analysis

3 RCTs involving a total of 157 patients of predicted severe acute pancreatitis

82 were randomized to NG feeding vs 75 to NJ feeding

Comparable demographics between both the groups

No significant differences in:

the incidence of mortality (RR = 0.69, 95% CI: 0.37 to 1.29, P = 0.25); tracheal aspiration (RR = 0.46, 95% CI: 0.14 to 1.53, P = 0.20); diarrhea (RR = 1.43, 95% CI: 0.59 to 3.45, P = 0.43); exacerbation of pain (RR = 0.94, 95% CI: 0.32 to 2.70, P = 0.90); and meeting energy balance (RR = 1.00, 95% CI: 0.92 to 1.09, P = 0.97) between the two groups. 

NG feeding was safe and well-tolerated as compared with NJ feeding

Y Chang et al. Critical Care. 2013

Evolution in Nutrition

Fasting

TPN is better

Early jejunal feeding is safe

Early jejunal feeding is superior

Gastric feeding is as good as jejunal feeding

Sax et al. Am J Surg 1987,153:117-22

Glutamine supplementation

12 RCTs of 505 patients with acute pancreatitis

Glutamine supplementation resulted in a significantly reduced risk of

mortality (RR 0.30; 95% CI, 0.15 to 0.60; P < 0.001) and total infectious

complications (RR 0.58; 95% CI, 0.39 to 0.87; P = 0.009) but not length

of hospital stay (MD -1.35; 95% CI, -3.25 to 0.56, P = 0.17).

In the subgroup analyses, only patients who received parenteral

nutrition and those who received glutamine in combination with other

immunonutrients demonstrated a statistically significant benefit in

terms of all the studied outcomes.

Asrani et al. Pancreatology. 2013

Polyunsaturated Fatty Acids in Acute Pancreatitis

0

20

40

60

80

100

IL-10 values(pg/mL)

Urine output(mL)

Respiratorydysfunction (%)

Fish oil Placebo

P<0.05

P<0.01

P<0.05

0

20

40

60

80

100

Lenght ofhospitalization

(days)

Jejunal feeding(days)

New complications(%)

Fish oil Placebo

P<0.05 P<0.05

P NS

Foitzik T, et al. JPEN 2002; 26:351-6. [31] Lasztity N, et al. Clin Nutr 2005; 24:198-205. [32]

Efficacy in experimental study …… and in humans

Probiotics in severe acute pancreatitis (PROPATRIA)

298 patients with predicted Severe acute pancreatitis were

randomly assigned within 72 hours of onset of symptoms

to receive a multispecies probiotic (n=153) or placebo

(n=145) given enterally BD for 28 days

Groups comparable at baseline in terms of patient’s

characteristics and disease severity

Infectious complications occurred in 46 (30%) patients in

the probiotics group and 41 (28%) of those in the placebo

group..

Probiotics in severe acute pancreatitis (PROPATRIA)

24 (16%) patients in the probiotics group died,

compared with nine (6%) in the placebo group. 9

patients in the probiotics group developed bowel

ischaemia (8 with fatal outcome), compared with none

in the placebo group (p=0.004).

In patients with predicted severe acute pancreatitis,

probiotic prophylaxis with this combination of probiotic

strains did not reduce the risk of infectious

complications and was associated with an increased risk

of mortality

Prophylactic antibiotics in severe acute pancreatitis

Early studies in 1970’s looked at all acute pancreatitis (mild to

severe), also used antibiotics now known to have poor pancreatic

penetrance, showed no benefit for antibiotic prophylaxis

Newer studies have looked at only severe pancreatitis, with drugs

now known to have good bioavailability in viable pancreatic tissue

tissue.

Pooling the Data:

Cochrane Review 2003:

4 studies examined, looking at prophylactic antibiotics in CTdiagnosed necrotizing pancreatitis. (Pederzoli 1993, Saino 1995, Schwarz 1997, Nordback 2001)

Conclusions:

Mortality advantage with Abx: (6/109 pts vs 18/109 pts, p=0.02)

Infected pancreatitis advantage with Abx: (23/109 pts vs 35/109 pts,

p=0.04)

No significant difference for extra-pancreatic infections, operative

interventions

The full results of the international meropenem study…

Dellinger et al, 2007:

Prospective, Double-Blinded RCT

100 pts, 50 in control (placebo), vs 50 in treatment group (meropenem)

Administration of study drug < 120 hrs after onset of sx

CT-proven pancreatic necrosis >30%, OR Balthazar Grade E on CT with

CRP >120 or MOD >2

The full results of the international meropenem study…

Dellinger et al, 2007:

Pancreatic/peripancreatic infection: Meropenem: n = 9/50 (18%) vs

Placebo: n = 6/50 (12%). (p=0.401)

Time to Onset of Infection: Meropenem: 21 days, vs Placebo: 21 days

Operative/Percutaneous Intervention: Meropenem: 13/50 (26%), vs

Placebo: 10/50 (20%). (p=0.476)

Non-Pancreatic Infections: Meropenem: 16/50 (32%), vs Placebo: 24/50

(48%). (p<0.20)

Mortality: Meropenem: 10/50 (20%), vs Placebo: 9/50 (18%)

Antibiotic therapy for prophylaxis against infection of pancreatic (CT-proven) necrosis

in acute pancreatitis 404 patients from 7 RCTs

Conclusions:

Antibiotic vs control: No significant differences in mortality (8.4 vs 14.4%), infected pancreatic necrosis (19.7 vs 24.4%), nonpancreatic infections (23.7 vs 36%), operative interventions

Beta-Lactam vs control: No significant difference in mortality (9.4% vs 15%), infected pancreatic necrosis (16.8 vs 24.2%), nonpancreatic infections (21 vs 32.5%), operative interventions

Imipenem vs control: No significant difference in mortality, infected pancreatic necrosis, operative intervention but there was Significant difference in infections overall (25.6% vs 52.4%, p=0.02)

Villatoro E, Bassi C, Larvin M. Cochrane Database of Systematic Reviews 2010, Issue 5.

Antibiotic prophylaxis in severe acute pancreatitis

No reduced risk of mortality, infection of necrotic pancreas, operative interventions

Studies are underpowered, heterogeneous in inclusion

criteria/treatment type/duration.

Trends do exist but are non-statistically significant

Potential for production of antibiotic resistant

organisms, fungal infection

While no definite increase in mortality, studies are small

Known increased mortality in resistant infection in VAP, bacteremia

Goals of Treatment

Limit systemic injury support and resuscitation – effective decrease pancreatic secretion – ineffective /

harmful? inhibit inflammatory mediators – (in) effective ? inhibit circulating trypsin – ineffective (too late)

Prevent necrosis – how?

Prevent infection antibiotics (imipenem and ciprofloxacin) – probably

ineffective in necrotic pancreatitis Probiotics- harmful Enteral nutrition

A Critical Appraisal of the Clinical Trials in Acute

Pancreatitis

ColipaseElastase

ChymotrypsinPhospholipase A2

Xanthynedehydrogenase

KallycreinC3aC5a

PlasminogenXIIa Factor

Systemic circulation

Alfa2 + TrypsinAlfa2-M

RESLiver

SpleenBone marrow

Nodes

Clearance

ProcolipaseProelastase

ChymotrypsinogenProphospholipase A2

Xanthynedehydrogenase

ProkallycreinC3C5PlasminogenXII Factor

Kininogens

Kinins

Trypsinogen

Trypsin

Trypsin

PSTI + TrypsinPSTI

Alfa1-AT + TrypsinAlfa1-AT

MesotrypsinEnzyme Y

Several steps may have to be blocked at the same time and this may be achieved by using combinations of several drugs at the same time or by the multiple actions of a single drug

Norman J. Am J Surg 1998; 175:76-83. (modified) [2]

Acute Pancreatitis

Complications: • Vascular leakage• Hypovolemia• Shock• ARDS• Acute renal tubular necrosis

IL-1 TNF

N.O. PAF

IL-6IL-8

Other leucocyte products

Oxygen radicalsElastaseIFN-α,γIL-10IL-2

Designing Future Clinical Trials in Acute Pancreatitis

Mason J, Siriwardena AK. Pancreatology 2005; 5:113-5. [33]

Therapeutic trials need to record the time from onset of symptoms to intervention

There is the need of using widely accepted prognostic indices to categorize the severity of acute pancreatitis

There is the need for relevant and interpretable end-points: Mortality is important but more work is necessary in developing patient

outcomes Good alternatives include the measurement of permanent target organ

damage, disability, quality of life, pain scores, category of intervention, surgery, in-patient stay and return to work

There is the need of including patients with a single etiology of acute pancreatitis, or at least only patients with a predominant etiology of the disease in the specific country

Conclusion

Knowing the various steps of pathophysiology of acute pancreatitis will

help in designing new therapeutic trials and in finding new therapeutic

targets

Adequate hydration, early enteral feeding definitely reduce the severity

of acute pancreatitis

Thank you