Raghuwansh P. Sah

Differences in Clinical Profile and Relapse Rate of Type 1 Versus Type 2 Autoimmune Pancreatitis

BACKGROUND & AIMS Autoimmune pancreatitis (AIP) has been divided into subtypes 1 (lymphoplasmacytic sclerosing pancreatitis) and 2 (idiopathic duct centric pancreatitis). We compared clinical profiles and long-term outcomes of types 1 and 2 AIP. METHODS We compared clinical presentation, relapse, and vital status of 78 patients with type 1 AIP who met the original HISORt criteria and 19 patients with histologically confirmed type 2 AIP. RESULTS At presentation, patients with type 1 AIP were older than those with type 2 AIP (62 +/- 14 vs 48 +/- 19 years; P < .0001) and had a greater prevalence of increased serum levels of immunoglobulin G4 (47/59 [80%] vs 1/6 [17%]; P = .004). Patients with type 1 were more likely than those with type 2 to have proximal biliary, retroperitoneal, renal, or salivary disease (60% vs 0; P < .0001). Inflammatory bowel disease was associated with types 1 and 2 (6% vs 16%; P = .37). During median clinical follow-up periods of 42 and 29 months, respectively, 47% of patients with type 1 and none of those with type 2 experienced a relapse. In type 1 AIP, proximal biliary involvement (hazard ratio [HR], 2.12; P = .038) and diffuse pancreatic swelling (HR, 2.00; P = .049) were predictive of relapse, whereas pancreaticoduodenectomy reduced the relapse rate (vs the corticosteroid-treated group; HR, 0.15; P = .0001). After median follow-up periods of 58 and 89 months (types 1 and 2, respectively), the 5-year survival rates for both groups were similar to those of the age- and sex-matched US population. CONCLUSIONS Types 1 and 2 AIP have distinct clinical profiles. Patients with type 1 AIP have a high relapse rate, but patients with type 2 AIP do not experience relapse. AIP does not affect long-term survival.

Serologic issues in IgG4-related systemic disease and autoimmune pancreatitis

Purpose of reviewIgG4-related systemic disease (ISD) is a recently recognized syndrome affecting multiple organs. Autoimmune pancreatitis (AIP) is the pancreatic manifestation of ISD and mimics pancreatic cancer. Current data show frequent association with serum IgG4 elevation and other serologic abnormalities. Here we explore the diagnostic and possible prognostic utility and pathogenetic implications of serologic abnormalities in ISD. Recent findingsSerum IgG4 elevations (>140 mg/dl) are seen in 70–80% of AIP patients and also in 5% of normal population and 10% of pancreatic cancer making it an unsuitable single marker for diagnosis. However, when combined with other features of AIP, it can be of great diagnostic value though its utility in monitoring of therapy or as a marker or predictor of relapse is limited. Several other antibodies have been identified in AIP against pancreas-specific antigens like trypsinogens I and II, pancreatic secretory trypsin inhibitor (PSTI) and plasminogen binding protein (PBP) and other nonpancreas-specific antigens. Anti-PBP antibodies appear to have potential diagnostic utility but require further validation. SummaryNo single serologic marker is diagnostic of ISD. Serum IgG4 elevation has convincing diagnostic utility when combined with other disease features although its value in disease monitoring may be limited.

Intra-acinar trypsinogen activation mediates early stages of pancreatic injury but not inflammation in mice with acute pancreatitis.

BACKGROUND & AIMS The role of trypsinogen activation in the pathogenesis of acute pancreatitis (AP) has not been clearly established. METHODS We generated and characterized mice lacking trypsinogen isoform 7 (T7) gene (T(-/-)). The effects of pathologic activation of trypsinogen were studied in these mice during induction of AP with cerulein. Acinar cell death, tissue damage, early intra-acinar activation of the transcription factor nuclear factor κB (NF-κB), and local and systemic inflammation were compared between T(-/-) and wild-type mice with AP. RESULTS Deletion of T7 reduced the total trypsinogen content by 60% but did not affect physiologic function. T(-/-) mice lacked pathologic activation of trypsinogen, which occurs within acinar cells during early stages of AP progression. Absence of trypsinogen activation in T(-/-) mice led to near complete inhibition of acinar cell death in vitro and a 50% reduction in acinar necrosis during AP progression. However, T(-/-) mice had similar degrees of local and systemic inflammation during AP progression and comparable levels of intra-acinar NF-κB activation, which was previously shown to occur concurrently with trypsinogen activation during early stages of pancreatitis. CONCLUSIONS T7 is activated during pathogenesis of AP in mice. Intra-acinar trypsinogen activation leads to acinar death during early stages of pancreatitis, which accounts for 50% of the pancreatic damage in AP. However, progression of local and systemic inflammation in AP does not require trypsinogen activation. NF-κB is activated early in acinar cells, independently of trypsinogen activation, and might be responsible for progression of AP.

Endoscopic retrograde pancreatography criteria to diagnose autoimmune pancreatitis: an international multicentre study

Background Characteristic pancreatic duct changes on endoscopic retrograde pancreatography (ERP) have been described in autoimmune pancreatitis (AIP). The performance characteristics of ERP to diagnose AIP were determined. Methods The study was done in two phases. In phase I, 21 physicians from four centres in Asia, Europe and the USA, unaware of the clinical data or diagnoses, reviewed 40 preselected ERPs of patients with AIP (n=20), chronic pancreatitis (n=10) and pancreatic cancer (n=10). Physicians noted the presence or absence of key pancreatographic features and ranked the diagnostic possibilities. For phase II, a teaching module was created based on features found most useful in the diagnosis of AIP by the four best performing physicians in phase I. After a washout period of 3 months, all physicians reviewed the teaching module and reanalysed the same set of ERPs, unaware of their performance in phase I. Results In phase I the sensitivity, specificity and interobserver agreement of ERP alone to diagnose AIP were 44, 92 and 0.23, respectively. The four key features of AIP identified in phase I were (i) long (>1/3 the length of the pancreatic duct) stricture; (ii) lack of upstream dilatation from the stricture (<5 mm); (iii) multiple strictures; and (iv) side branches arising from a strictured segment. In phase II the sensitivity (71%) of ERP significantly improved (p<0.05) without a significant decline in specificity (83%) (p>0.05); the interobserver agreement was fair (0.40). Conclusions The ability to diagnose AIP based on ERP features alone is limited but can be improved with knowledge of some key features.

New insights into pancreatic cancer-induced paraneoplastic diabetes

Up to 85% of patients with pancreatic cancer have diabetes or hyperglycaemia, which frequently manifests as early as 2–3 years before a diagnosis of pancreatic cancer. Conversely, patients with new-onset diabetes have a 5–8-fold increased risk of being diagnosed with pancreatic cancer within 1–3 years of developing diabetes. Emerging evidence now indicates that pancreatic cancer causes diabetes. As in type 2 diabetes, β-cell dysfunction and peripheral insulin resistance are seen in pancreatic cancer-induced diabetes. However, unlike in patients with type 2 diabetes, glucose control worsens in patients with pancreatic cancer in the face of ongoing, often profound, weight loss. Diabetes and weight loss, which precede cachexia onset by several months, are paraneoplastic phenomena induced by pancreatic cancer. Although the pathogenesis of these pancreatic cancer-induced metabolic alterations is only beginning to be understood, these are likely mechanisms to promote the survival and growth of pancreatic cancer in a hostile and highly desmoplastic microenvironment. Interestingly, these metabolic changes could enable early diagnosis of pancreatic cancer, if they can be distinguished from the ones that occur in patients with type 2 diabetes. One such possible biomarker is adrenomedullin, which is a potential mediator of β-cell dysfunction in pancreatic cancer-induced diabetes.

New Insights into the Pathogenesis of Pancreatitis

Purpose of review In this article, we review important advances in our understanding of the mechanisms of pancreatitis. Recent findings The relative contributions of intrapancreatic trypsinogen activation and nuclear factor kappa B (NF&kgr;B) activation, the two major early independent cellular events in pancreatitis, have been investigated using novel genetic models. Trypsinogen activation has traditionally held the spotlight for many decades as the central pathogenic event of pancreatitis. However, recent experimental evidence points to the role of trypsin activation in early acinar cell damage but not in the inflammatory response of acute pancreatitis, which was shown to be induced by NF&kgr;B activation. Further, chronic pancreatitis developed independently of trypsinogen activation in the caerulein model. Sustained NF&kgr;B activation, but not persistent intra-acinar expression of active trypsin, was shown to result in chronic pancreatitis. Calcineurin-NFAT (nuclear factor of activated T-cells) signaling was shown to mediate downstream effects of pathologic rise in intracellular calcium. Interleukin-6 was identified as a key cytokine mediating pancreatitis-associated lung injury. Summary Recent advances challenge the long-believed trypsin-centered understanding of pancreatitis. It is becoming increasingly clear that activation of intense inflammatory signaling mechanisms in acinar cells is crucial to the pathogenesis of pancreatitis, which may explain the strong systemic inflammatory response in pancreatitis.

Pathogenic mechanisms of acute pancreatitis.

Purpose of review In this article, recent advances in the pathogenesis of acute pancreatitis have been reviewed. Recent findings Pathologic intra-acinar trypsinogen activation had been hypothesized to be the central mechanism of pancreatitis for over a century. This hypothesis could be explored for the first time with the development of a novel mouse model lacking pathologic intra-acinar trypsinogen activation. It became clear that intra-acinar trypsinogen activation contributes to early acinar injury, but local and systemic inflammation progress independently during pancreatitis. Early intra-acinar nuclear factor kappa B (NF&kgr;B) activation, which occurs parallel to but independent of trypsinogen activation, may be crucial in pancreatitis. Although the mechanism of NF&kgr;B and trypsinogen activation is not entirely clear, further insights have been made into key pathogenic cellular events such as calcium signaling, mitochondrial dysfunction, endoplasmic reticulum (ER) stress, autophagy and impaired trafficking, and lysosomal and secretory responses. Cellular intrinsic damage-sensing mechanisms that lead to activation of the inflammatory response aimed at repair, but lead to disease when overwhelmed, are beginning to be understood. Summary New findings necessitate a paradigm shift in our understanding of acute pancreatitis. Intra-acinar trypsinogen activation leads to early pancreatic injury, but the inflammatory response of acute pancreatitis develops independently, driven by early activation of inflammatory pathways.

Molecular mechanisms of pancreatic injury.

Purpose of reviewDespite being a subject of much scientific scrutiny, the pathogenesis of acute pancreatitis is still not well understood. This article reviews recent advances in our understanding of acute pancreatitis. Recent findingsZymogen activation, observed within acini early during acute pancreatitis for a long time, was shown to be sufficient to induce acute pancreatitis. Another key early event, NF&kgr;B activation, has previously been shown to induce acute pancreatitis. The relationship between these two key early steps is beginning to be clarified. Mechanisms of zymogen activation – pathologic calcium signaling, pH changes, colocalization and autophagy, and of NF&kgr;B activation have been investigated intensively along with potential therapeutic targets both upstream and downstream of these key events. Additional key findings have been elucidation of the role of bioenergetics and the dual role of oxidative stress in acute pancreatitis, recognition of endoplasmic reticulum stress as an early step and the status of duct cells as important entities in pancreatic injury. SummaryCurrent findings have provided further insight into the roles and mechanisms of zymogen activation and inflammatory pathways in pancreatic injury. Future studies, which will be of great importance in identifying therapeutic targets, are being undertaken to establish the relative contributions of these pathways during acute pancreatitis.

Prevalence, diagnosis, and profile of autoimmune pancreatitis presenting with features of acute or chronic pancreatitis.

BACKGROUND & AIMS Little is known about how many patients with features of acute pancreatitis (AP) or chronic pancreatitis (CP) have autoimmune pancreatitis (AIP); most information comes from case reports. We explored the clinical profiles and relationship between these diseases. METHODS We evaluated 178 patients presenting to our Pancreas Clinic between January 2005 and June 2006 for evaluation of the etiology of their suspected pancreatitis; AIP was diagnosed when patients met HISORt (Histology, Imaging features, Serology, Other organ involvement and Response to steroid treatment) criteria. In a separate cohort of patients with AIP from our database, we identified patients who presented with features of AP (>/=2 of abdominal pain, increased pancreatic enzymes, pancreatic inflammation determined by imaging analyses) or CP (>/=1 of pancreatic calcification, irregular main pancreatic duct dilation, or marked atrophy) and determined their clinical profile. RESULTS Only 7/178 (3.9%) patients evaluated for etiology of suspected pancreatitis had AIP. Among 63 AIP patients in our database, 22 (34.9%) had features of AP (n = 15) or CP (n = 7) at presentation (average age 53.4 +/- 19.0 years, all males). Patients with AIP and pancreatitis were characterized by presence of obstructive jaundice (59.1%), increased levels of liver enzymes (81.8%), increased levels of serum immunoglobulin G4 (80.9%), and other organ involvement (69.1%). All 19 patients presenting with pancreatitis who were treated with steroids responded to treatment. CONCLUSIONS While AIP is an uncommon etiology for acute or chronic pancreatitis, >33% of AIP have features of acute or chronic pancreatitis at presentation.

Autoimmune pancreatitis: An update on classification, diagnosis, natural history and management

Autoimmune Pancreatitis (AIP) is a recently recognized chronic fibro-inflammatory disease of the pancreas. Although rare, its recognition continues to increase worldwide. Patients often present with painless obstructive jaundice mimicking pancreatic cancer. Two subtypes of AIP are known-type 1 is a multi-organ disease associated with IgG4; type 2 appears to be a pancreas-specific disorder. Dramatic response to steroid treatment is characteristic of both forms. A non-invasive diagnosis of type 1 AIP may be possible using diagnostic criteria (in ~70% cases) while diagnosis of type 2 requires histology. These subtypes differ in natural history- type 1 often relapses while initial reports suggest that type 2 does not. Long term complications include endocrine and exocrine insufficiency and in case of type 1, disease relapses and complications from extra-pancreatic involvement. Neither form affects long term survival. The treatment and follow-up guidelines continue to evolve with our increasing experience in AIP.