Does a lack of reactivity to alpha-fodrin indicate the existence of primary autoimmune pancreatitis?

Autoimmune pancreatitis--a new evolving pancreatic disease?

INTRODUCTION

Recent advances support the concept of autoimmune pancreatitis as a unique systemic disease because occasional extrapancreatic lesions such as sclerosing cholangitis, sclerosing sialoadenitis, and retroperitoneal fibrosis show similar pathological features with fibrosis and abundant infiltration of IgG4-positive plasma cells, and are steroid responsive. Based on these findings, several diagnostic criteria have been proposed.

MATERIALS AND METHODS

Although AIP is accepted worldwide as a unique clinical entity, pathogenetic mechanism still remains unclear. To clarify it, genetic background, humoral immunity, candidates of target antigens including self-antigens and molecular mimicry from microbes, cellular immunity including regulatory T cells, complement system, and experimental models are reviewed.

RESULTS

Based on these findings, we have proposed a hypothesis for the pathogenesis of AIP in the biphasic mechanism of "induction" and "progression." In the early stage, initial response to self-antigens (LF, CA-II, CA-IV, PSTI, or α-fodrin) or molecular mimicry (Helicobacter pylori) is induced by decreased naive regulatory T cells (Tregs), and Th1 cells release proinflammatory cytokines (IFN-γ, IL-1b, IL-2, and TNF-α).

DISCUSSION

In the chronic stage, progression is supported by increased memory Tregs and Th2 immune responses. The classical pathway of complement system may be activated by IgG1 immune complex.

CONCLUSION

As Tregs seem to take important roles in progression as well as induction of the disease, further studies are necessary to clarify the pathogenesis.

Recent advances in autoimmune pancreatitis: concept, diagnosis, and pathogenesis

Recent advances support the concept of autoimmune pancreatitis (AIP) as a unique systemic disease, because it shows occasional extrapancreatic lesions such as sclerosing cholangitis, sclerosing sialoadenitis, and retroperitoneal fibrosis, pathological features similar to those of fibrosis, and abundant infiltration of IgG4-positive plasma cells, and it is steroid responsive. Based on these findings, several diagnostic criteria have been proposed. Although AIP is accepted worldwide as a unique clinical entity, its pathogenetic mechanism remains unclear. To clarify its pathogenesis, its genetic background, humoral immunity, candidate target antigens including self-antigens and molecular mimicry by microbes, and cellular immunity including regulatory T cells, the complement system, and experimental models are reviewed. On the basis of this review, we hypothesize that the pathogenesis of AIP involves a biphasic mechanism consisting of "induction" and "progression." In the early stage, the initial response to self-antigens [lactoferrin, carbonic anhydrase (CA)-II, CA-IV, pancreatic secretory trypsin inhibitor, and alpha-fodrin] and molecular mimicry (Helicobacter pylori) are induced by decreased naïve regulatory T cells (Tregs), and T-helper (Th) 1 cells release proinflammatory cytokines [interferon-gamma, interleukin (IL)-1beta, IL-2, and tumor necrosis factor alpha]. In the chronic stage, progression is supported by increased memory Tregs and Th2 immune responses. The classical complement system pathway may be activated by the IgG1 immune complex. As Tregs seem to play an important role in progression as well as in induction of the disease, further studies are necessary to clarify the pathogenesis of AIP.

T cell lymphoplasmacellular and eosinophilic infiltration of the pancreas with involvement of the gallbladder and duodenum in non-alcoholic duct-destructive chronic pancreatitis

BACKGROUND

Non-alcoholic duct destructive chronic pancreatitis is a rare entity with specific pathological features. The majority of the patients are from Japan. We report a case with involvement of the distal bile duct, the gallbladder, the duodenum and the ampulla, and present a review of patients from Europe and the USA since 1997.

CASE PRESENTATION

A 56-year-old man presented with a 3-month history of mild acute pancreatitis and obstructive jaundice, followed by increasing weight loss, lethargy and epigastric pain. CT showed a mass in the head of the pancreas. ERCP demonstrated a smooth stricture of the intra-pancreatic main bile duct and an irregular, incomplete, stricture in the main pancreatic duct. A pancreatic cancer could not be reliably excluded, and, therefore, he underwent a pylorus-preserving Kausch-Whipple's pancreatoduodenectomy.

RESULTS

Histopathology showed typical peri-ductal T cell-rich lymphoplasmacellular and eosinophilic infiltration of the pancreas, with involvement of the distal bile duct but, also, unusual inflammatory infiltration of the gallbladder, the duodenum and the ampulla.

CONCLUSION

The inflammatory process in non-alcoholic duct-destructive chronic pancreatitis can affect the entire pancreato-biliary region and mimics pancreatic cancer. Currently, there are no definitive criteria for pre-operative diagnosis, so it is very difficult for one to avoid resection.