A concept on the role of Helicobacter pylori infection in 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.

IgG4-related sclerosing disease: a critical appraisal of an evolving clinicopathologic entity

An elevated serum titer of immunoglobulin G4 (IgG4), the least common (3% to 6%) of the 4 subclasses of IgG, is a surrogate marker for the recently characterized IgG4-related sclerosing disease. The syndrome affects predominantly middle-aged and elderly patients, with male predominance. The patients present with symptoms referable to the involvement of 1 or more sites, usually in the form of mass lesions. The prototype is IgG4-related sclerosing pancreatitis (also known as autoimmune pancreatitis), most commonly presenting as painless obstructive jaundice with or without a pancreatic mass. Other common sites of involvement are the hepatobiliary tract, salivary gland, orbit, and lymph node, but practically any organ-site can be affected, such as retroperitoneum, aorta, mediastinum, soft tissue, skin, central nervous system, breast, kidney, prostate, upper aerodigestive tract, and lung. The patients usually have a good general condition, with no fever or constitutional symptoms. Common laboratory findings include raised serum globulin, IgG, IgG4, and IgE, whereas lactate dehydrogenase is usually not raised. Some patients have low titers of autoantibodies (such as antinuclear antibodies and rheumatoid factor). The disease often shows excellent response to steroid therapy. The natural history is characterized by the development of multiple sites of involvement with time, sometimes after many years. However, the disease can remain localized to 1 site in occasional patients. The main pathologic findings in various extranodal sites include lymphoplasmacytic infiltration, lymphoid follicle formation, sclerosis and obliterative phlebitis, accompanied by atrophy and loss of the specialized structures of the involved tissue (such as secretory acini in pancreas, salivary gland, or lacrimal gland). The relative predominance of the lymphoplasmacytic and sclerotic components results in 3 histologic patterns: pseudolymphomatous, mixed, and sclerosing. Immunostaining shows increased IgG4+ cells in the involved tissues (>50 per high-power field, with IgG4/IgG ratio >40%). The lymph nodes show multicentric Castleman disease-like features, reactive follicular hyperplasia, interfollicular expansion, or progressive transformation of germinal centers, with the unifying feature being an increase in IgG4+ plasma cells on immunostaining. The nature and pathogenesis of IgG4-related sclerosing disease are still elusive. Occasionally, the disease can be complicated by the development of malignant lymphoma and possibly carcinoma.

Effect of Helicobacter bilis infection on human bile duct cancer cells

BACKGROUND

Helicobacter pylori infection is known to be associated with chronic atrophic gastritis, peptic ulcers, and gastric malignancies. However, the effects of other Helicobacter species have not been investigated extensively. In mice, a close relationship is observed between Helicobacter hepaticus and hepatocellular carcinoma, and Helicobacter species can be found in humans, most commonly in extragastric organs. There have also been reports that H. bilis may be associated with biliary malignancies in humans. The effect of H. bilis infection on a human bile duct cancer cell line was investigated in this study.

METHODS

We prepared HuCCT-1, the human bile duct cancer cell line, which was cocultured with H. bilis and cultured alone as a control. HuCCT-1 with and without H. bilis were transfected with the NF-kappaB, E2 transcription factor (E2F), and cyclic AMP response element (CRE) luciferase vectors. The activity of NF-kappaB between H. bilis and the infected and noninfected HuCCT-1 cells was also measured by dual luciferase reporter assay. The concentration of vascular endothelial growth factor (VEGF) in the cocultured medium and control medium were measured by ELISA. To investigate the effect of H. bilis infection on HuCCT-1 with regard to human umbilical vein endothelial cell (HUVEC) tube formation, HUVECs and fibroblasts were cocultured in 24-well plates with and without the conditioned medium.

RESULTS

NF-kappaB, E2F and CRE activity, production of VEGF, and angiogenesis in H. bilis-infected cell lines were enhanced compared with controls.

CONCLUSIONS

H. bilis infection in a human bile duct cancer cell line activates transcript factors such as NF-kappaB that stimulate production of VEGF and lead to enhancement of angiogenesis. H. bilis infection may play an important role in malignancies in the biliary tract.

Identification of a novel antibody associated with autoimmune pancreatitis

BACKGROUND

Autoimmune pancreatitis is characterized by an inflammatory process that leads to organ dysfunction. The cause of the disease is unknown. Its autoimmune origin has been suggested but never proved, and little is known about the pathogenesis of this condition.

METHODS

To identify pathogenetically relevant autoantigen targets, we screened a random peptide library with pooled IgG obtained from 20 patients with autoimmune pancreatitis. Peptide-specific antibodies were detected in serum specimens obtained from the patients.

RESULTS

Among the detected peptides, peptide AIP(1-7) was recognized by the serum specimens from 18 of 20 patients with autoimmune pancreatitis and by serum specimens from 4 of 40 patients with pancreatic cancer, but not by serum specimens from healthy controls. The peptide showed homology with an amino acid sequence of plasminogen-binding protein (PBP) of Helicobacter pylori and with ubiquitin-protein ligase E3 component n-recognin 2 (UBR2), an enzyme highly expressed in acinar cells of the pancreas. Antibodies against the PBP peptide were detected in 19 of 20 patients with autoimmune pancreatitis (95%) and in 4 of 40 patients with pancreatic cancer (10%). Such reactivity was not detected in patients with alcohol-induced chronic pancreatitis or intraductal papillary mucinous neoplasm. The results were validated in another series of patients with autoimmune pancreatitis or pancreatic cancer: 14 of 15 patients with autoimmune pancreatitis (93%) and 1 of 70 patients with pancreatic cancer (1%) had a positive test for anti-PBP peptide antibodies. When the training and validation groups were combined, the test was positive in 33 of 35 patients with autoimmune pancreatitis (94%) and in 5 of 110 patients with pancreatic cancer (5%).

CONCLUSIONS

The antibody that we identified was detected in most patients with autoimmune pancreatitis but also in some patients with pancreatic cancer, making it an imperfect test to distinguish between these two conditions.

Diagnostic utility of biopsy specimens for autoimmune pancreatitis

BACKGROUND AND AIMS

Infiltration of IgG4-positive plasma cells in the pancreas and other organs is characteristic of autoimmune pancreatitis (AIP). However, it is undetermined whether needle or forceps biopsy of pancreas or other organs is indeed useful for the diagnosis of AIP. We aimed to clarify this point.

METHODS

Among 39 AIP patients, tissue sampling without laparotomy was performed in 27. Biopsy of pancreas, gastric mucosa, liver, bile duct, and duodenal papilla was performed in 15, 17, 11, 5 and 7, respectively. The obtained specimens were examined for IgG4-positive plasma cells. We also examined gastric mucosa of 18 patients with pancreatic cancer as controls. When the number of IgG4-positive plasma cells was more than 10 per high-power field, we regarded it as diagnostic.

RESULTS

Diagnostic sensitivity in pancreas, gastric mucosa, liver, bile duct, and duodenal papilla was 47% (7/15), 47% (8/17), 36% (4/11), 0% (0/5), and 57% (4/7), respectively.

CONCLUSIONS

Sensitivity of IgG4 immunostaining was unsatisfactory when tissue sampling was performed by needle or forceps biopsy. Biopsy of gastric mucosa might be a good subsidiary diagnostic tool.

Autoimmune pancreatitis/IgG4-associated cholangitis and primary sclerosing cholangitis--overlapping or separate diseases?

Autoimmune pancreatitis is a recently described fibroinflammatory disease which is characterised by raised serum levels of IgG4 (in >70% of cases), and an IgG4-positive lymphoplasmacytic tissue infiltrate. A favourable and rapid clinical response to oral steroid therapy is often seen. Biliary involvement is common, and the term IgG4-associated cholangitis has recently been coined. The cholangiographic appearances of IgG4-associated cholangitis and primary sclerosing cholangitis can be difficult to differentiate. Moreover, raised levels of serum IgG4 have been recently found in 9% of patients with primary sclerosing cholangitis (a much higher frequency than for other gastrointestinal diseases), and those with raised levels appear to progress more rapidly to liver failure. Here we review the similarities and differences between the biliary disease in autoimmune pancreatitis and primary sclerosing cholangitis, and address the issue of disease overlap. Improvements in understanding the relationship between these conditions might lead to an enhanced understanding of the aetiopathogenesis, and improved treatment of both conditions.

[Autoimmune pancreatitis]

Autoimmune pancreatitis has been established as a special entity of pancreatitis. It is an enigmatic disease since it is adding an autoimmune etiology to the existing causes of pancreatitis. Morphological hallmarks of the disease are narrowing of the pancreatic duct system and the bile duct by periductal lymphoplasmocytic inflammation. This results in many cases in obstructive jaundice due to a mass-forming lesion in the pancreatic head mimicking pancreatic ductal adenocarcinoma. Therefore, patients will frequently undergo surgery. Histopathologically, the disease can be diagnosed by IgG4-positive plasma cells. Serologically, patients may present with elevated serum IgG and IgG4 levels. Other autoantibodies are also described. Association with other autoimmune manifestations in a wide range of organs is frequent. Autoimmune pancreatitis will respond to steroid treatment, which is of specific importance because pancreatic cancer is one of its clinical differential diagnoses. It is important to positively diagnose autoimmune pancreatitis, especially if the bile ducts are affected, since cholangitis may be or become a prominent problem before or after surgery.

From the "little brain" gastrointestinal infection to the "big brain" neuroinflammation: a proposed fast axonal transport pathway involved in multiple sclerosis

The human central nervous system (CNS) is targeted by different pathogens which, apart from pathogens' intranasal inoculation or trafficking into the brain through infected blood cells, may use a distinct pathway to bypass the blood-brain barrier by using the gastrointestinal tract (GIT) retrograde axonal transport through sensory or motor fibres. The recent findings regarding the enteric nervous system (often called the "little brain") similarities with CNS and GIT axonal transport of infections resulting in CNS neuroinflammation are mainly reviewed in this article. We herein propose that the GIT is the vulnerable area through which pathogens (such as Helicobacter pylori) may influence the brain and induce multiple sclerosis pathologies, mainly via the fast axonal transport by the afferent neurones connecting the GIT to brain.

Autoimmune pancreatitis associated with high prevalence of gastric ulcer independent of Helicobacter pylori infection status

OBJECTIVES

The relationship between Helicobacter pylori status and host tumor necrosis factor alpha (TNF-alpha) promoter susceptibility in ulcers inautoimmune pancreatitis (AIP) is unknown. We sought to study the frequency of peptic ulcer, the association of peptic ulcer with H. pylori and host TNF-alpha promoter haplotype in AIP and nonautoimmune chronic pancreatitis.

METHODS

Esophagogastroduodenoscopy (EGD) was performed in 40 patients with AIP and 113 patients with nonautoimmune chronic pancreatitis (CP). The status of H. pylori infection was determined. Genotyping and 5-locus haplotype assembly of the TNF-alpha promoter were performed. The correlation between clinical characteristics, endoscopic findings, Helicobacter pylori infection status, and TNF-alpha promoter polymorphism and haplotype was analyzed.

RESULTS

The frequencies of gastric ulcer (GU) was higher in patients with AIP compared with patients with nonautoimmune CP (22.5% vs 4.4%, P = 0.001). Duodenal ulcer (DU) was more prevalent than GU in both patients with AIP and patients with nonautoimmune CP. There was no difference in the positive status of H. pylori and TNF-alpha promoter polymorphism/haplotype.

CONCLUSIONS

Our results demonstrated that GU was more prevalent in AIP compared with nonautoimmune CP. Positive H. pylori status and host TNF-alpha promoter susceptibility could not explain the pathogenesis of higher GU prevalence and pathogenesis of AIP in our population.

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.

Current diagnosis and management of unusual pancreatic tumors

BACKGROUND

The finding of a solid or cystic mass in the pancreas is becoming more common secondary to the increasing use of cross-sectional imaging and the improved sensitivity of such studies for the detection of pancreatic abnormalities. Because of the aggressive natural history of pancreatic cancer, this has caused concern that all pancreatic abnormalities may be cancer as well as confusion over proper diagnostic and treatment algorithms. This review provides an overview of the natural history, diagnostic considerations, and treatment recommendations for the less common tumors of the pancreas which can be misinterpreted as pancreatic cancer including: solid pseudopapillary tumors (SPT), acinar cell carcinoma (ACC), lymphoplasmacytic sclerosing pancreatitis (LPSP), primary pancreatic lymphoma (PPL), and metastatic renal cell carcinoma to the pancreas.

DATA SOURCES

A Medline search was conducted to identify studies investigating the clinicopathologic features, molecular genetics, pathogenesis, diagnosis, and treatment of SPT, ACC, LPSP, PPL, and pancreatic metastases.

CONCLUSIONS

It is often possible to obtain an accurate pretreatment diagnosis for these unusual pancreatic tumors and to successfully differentiate them from the more common pancreatic malignancies.

Acute recurrent pancreatitis: An autoimmune disease?

In this review article, we will briefly describe the main characteristics of autoimmune pancreatitis and then we will concentrate on our aim, namely, evaluating the clinical characteristics of patients having recurrence of pain from the disease. In fact, the open question is to evaluate the possible presence of autoimmune pancreatitis in patients with an undefined etiology of acute pancreatitis and for this reason we carried out a search in the literature in order to explore this issue. In cases of recurrent attacks of pain in patients with “diopathic”pancreatitis, we need to keep in mind the possibility that our patients may have autoimmune pancreatitis. Even though the frequency of this disease seems to be quite low, we believe that in the future, by increasing our knowledge on the subject, we will be able to diagnose an ever-increasing number of patients having acute recurrence of pain from autoimmune pancreatitis.

Successful treatment of autoimmune pancreatitis complicated with autoimmune thrombocytopenia and interstitial pneumonia by prednisolone

We report the second patient diagnosed with autoimmune pancreatitis complicated with autoimmune thrombocytopenia and interstitial pneumonia. The patient was treated with prednisolone and responded favorably. We demonstrated that anti-platelet (PLT) antibody of the patient was IgG4 and that it may react with HLA, not specific antigen, on both pancreas and PLT.

Molecular and cellular key players in human islet transplantation

Human islet transplantation could represent an attractive alternative to insulin injections for the treatment of diabetes type 1. However, such an approach requires a better understanding of the molecular and cellular switches controlling β-cell function in general as well as after transplantation into the liver. Although much research has been done into the suitability of stem or progenitor cells to generate a limitless supply of human β-cells, a reproducible and efficient protocol for the differentiation of such cells into stably insulin-secreting β-cells suitable for transplantation has yet to be reported. Fueled by recent findings showing that mature β-cells are able to regenerate, many efforts have been undertaken to expand this cell pool. Unfortunately, also these approaches had problems to yield sufficiently differentiated human islet cells. The aim of this review is to summarize recent findings describing some of the molecular and cellular key players of islet biology. A more complete understanding of their orchestration and the use of new methods such as real time confocal imaging for the assessment of islet quality may yield the necessary advancements for more successful human islet transplantation.

Advances in autoimmune pancreatitis

Autoimmune Pancreatitis (AIP) is a special kind of chronic pancreatitis, and its essential quality remains unclear. At present, deeper researches showed that AIP was different from other pancreatitis, and had a variety of clinical features. Therefore, it was attracting more and more attention as an independent disease. In this article, we summarized the advances in the pathogenic mechanisms, clinical symptoms, diagnosis and treatment of autoimmune pancreatitis in the past few years.

Alzheimer's disease and Helicobacter pylori infection: Defective immune regulation and apoptosis as proposed common links

Although degenerative diseases of the central nervous system, including Alzheimer's disease (AD), have an increasingly high impact on aged population their association with Helicobacter pylori (H. pylori) infection has not as yet been thoroughly researched. Current H. pylori infection appears to induce irregular humoral and cellular immune responses that, owing to the sharing of homologous epitopes (molecular mimicry), cross-react with components of nerves, thereby contributing and possibly perpetuating the apoptotic neural tissue damage observed in neurodegenerative diseases including AD. An association between AD and H. pylori infection has been recently addressed by two studies. A higher seropositivity for anti-H. pylori immunoglobulin G antibodies in 30 patients with AD than in 30 age-matched controls was reported in one study; this serological test, however, has limitations because it does not discriminate between current and old infections. In the other study, by introducing the histological method (the actual gold standard) for diagnosis of H. pylori infection, we reported a higher prevalence of H. pylori infection in 50 AD patients than in 30 anemic controls. This pathogen may influence the pathophysiology of AD by promoting platelet and platelet-leukocyte aggregation; releasing various pro-inflammatory and vasoactive substances; developing cross-mimicry with host antigens; producing reactive oxygen metabolites and circulating lipid peroxides; influencing the apoptotic process; and increasing, through induction of atrophic gastritis, homocysteine, which contributes to vascular disorders implicated in endothelial damage and neurodegeneration.

Helicobacter pylori and autoimmune pancreatitis: role of carbonic anhydrase via molecular mimicry?

Autoimmune pancreatitis is a recently defined nosological entity, which accounts for 4.6-6% of all forms of chronic pancreatitis and is often associated with other autoimmune diseases, particularly Sjogren's syndrome. Possession of the HLA DRB1*0405-DQB1*0401 genotype confers a risk for the development of autoimmune pancreatitis. Autoantibodies against carbonic anhydrase II and lactoferrin are frequently present in affected subjects and are suspected to have a pathogenic role. A link between gastric infection by Helicobacter pylori and autoimmune pancreatitis has been hypothesized. We used in silico protein analysis and search for HLA binding motifs to verify this hypothesis. We found a significant homology between human carbonic anhydrase II and alpha-carbonic anhydrase of Helicobacter pylori, an enzyme which is fundamental for the survival and proliferation of the bacterium in the gastric environment. Moreover, the homologous segments contain the binding motif of the HLA molecule DRB1*0405. Our data strengthen the hypothesis that gastric Helicobacter pylori infection can trigger autoimmune pancreatitis in genetically predisposed subjects.

Helicobacter pylori and autoimmune pancreatitis: role of carbonic anhydrase via molecular mimicry?

Autoimmune pancreatitis is a recently defined nosological entity, which accounts for 4.6-6% of all forms of chronic pancreatitis and is often associated with other autoimmune diseases, particularly Sjogren's syndrome. Possession of the HLA DRB1*0405-DQB1*0401 genotype confers a risk for the development of autoimmune pancreatitis. Autoantibodies against carbonic anhydrase II and lactoferrin are frequently present in affected subjects and are suspected to have a pathogenic role. A link between gastric infection by Helicobacter pylori and autoimmune pancreatitis has been hypothesized. We used in silico protein analysis and search for HLA binding motifs to verify this hypothesis. We found a significant homology between human carbonic anhydrase II and alpha-carbonic anhydrase of Helicobacter pylori, an enzyme which is fundamental for the survival and proliferation of the bacterium in the gastric environment. Moreover, the homologous segments contain the binding motif of the HLA molecule DRB1*0405. Our data strengthen the hypothesis that gastric Helicobacter pylori infection can trigger autoimmune pancreatitis in genetically predisposed subjects.

Helicobacter pylori and autoimmune pancreatitis: role of carbonic anhydrase via molecular mimicry?

Autoimmune pancreatitis is a recently defined nosological entity, which accounts for 4.6-6% of all forms of chronic pancreatitis and is often associated with other autoimmune diseases, particularly Sjogren's syndrome. Possession of the HLA DRB1*0405-DQB1*0401 genotype confers a risk for the development of autoimmune pancreatitis. Autoantibodies against carbonic anhydrase II and lactoferrin are frequently present in affected subjects and are suspected to have a pathogenic role. A link between gastric infection by Helicobacter pylori and autoimmune pancreatitis has been hypothesized. We used in silico protein analysis and search for HLA binding motifs to verify this hypothesis. We found a significant homology between human carbonic anhydrase II and alpha-carbonic anhydrase of Helicobacter pylori, an enzyme which is fundamental for the survival and proliferation of the bacterium in the gastric environment. Moreover, the homologous segments contain the binding motif of the HLA molecule DRB1*0405. Our data strengthen the hypothesis that gastric Helicobacter pylori infection can trigger autoimmune pancreatitis in genetically predisposed subjects.