Increased prevalence of seropositivity for non-gastric Helicobacter species in patients with autoimmune liver disease

Helicobacter mastomyrinus infection induces autoimmune hepatitis in mice

Background

Autoimmune hepatitis (AIH) is a chronic progressive liver disease caused by the immune system mistakenly attacking its own hepatocytes. The role of the gut microbiome in the pathogenesis and progression of AIH is of considerable significance. However, the dearth of suitable animal models has significantly constrained advancements in the pathogenesis and the development of therapeutic strategies for AIH. Helicobacter mastomyrinus (H. mastomyrinus, Hm) is a potentially zoonotic pathogenic microorganism capable of causing diseases of the enterohepatic system in rodent laboratory animals. Nevertheless, research on its role and mechanisms in causing liver disease is severely limited.

Methods

In this study, male BALB/c mice were infected with Hm isolate Hm-17, and were sacrificed at 4 w, 8 w, 14 w and 22 w after infection, respectively. The serum was collected for detecting a number of AIH indicators, including the aminotransferases level, IgG content and autoantibody level. Additionally, the liver tissue was examined for pathological analysis, fibrosis, bacterial content, and the distribution of immune cells.

Results

It was observed that the infection initially caused focal necrotizing hepatitis and subsequently progressed to interface hepatitis with lymphocyte/plasma cell infiltration, as well as hypergammaglobulinemia and autoantibody reactions, predominantly to Anti-nuclear and anti-smooth muscle antibodies. Furthermore, as the infection persisted, the mice exhibited a progressive increase in liver fibrosis and mild steatosis. Despite the maintenance of a low level of Hm colonization in the liver, there was a notable infiltrate of macrophages, T and B lymphocytes. In particular, the inflammatory foci in the Hm-infected liver were highly enriched for IL17+ cells.

Conclusion

The present study provides an animal model of immunological liver injury induced by Hm infection that exhibits main characteristics similar to those observed in AIH-1 patients. This model may serve as a novel animal model for the study of the pathogenesis and potential therapeutic strategies for human AIH.

Helicobacter infection and hepatobiliary cancer: epidemiology and pathogenesis

Hepatobiliary cancer is one of the leading causes of cancer death and a major public health problem in both developed and developing countries. Chronic infections are common risk factors for cancer. Animal studies have shown that Helicobacter pylori (H. pylori) infection can cause hepatitis, colitis, and liver cancer in susceptible individuals. Data from clinical and experimental studies point to the involvement of the gastrointestinal microbiota in the pathogenesis of the non-alcoholic fatty liver disease, including H. pylori infection. The researchers included H. pylori infection in the list of etiopathogenetic factors of primary biliary cholangitis due to the detection of its DNA in the liver tissue and antibodies to H. pylori in the bile and serum of patients with primary biliary cholangitis. A growing body of evidence suggests that H. pylori may be a risk factor for the development of liver cirrhosis and hepatocellular carcinoma in patients with viral hepatitis B and C. The contribution of H. pylori infection to the development of hepatic encephalopathy and hyperammonemia has been identified. H. pylori infection is associated with liver inflammation, fibrosis, and necrosis by inducing the synthesis of systemic inflammatory mediators and increasing intestinal permeability. Along with these consequences, bacterial translocation through the biliary tract can also lead to direct liver damage, predisposing or even triggering the carcinogenic process. The study of subspecies of Helicobacter shows that they can lead to the development of not only hepatocellular carcinoma but also other malignant neoplasms of the hepatobiliary system. This review presents current data on the epidemiology and mechanisms of the influence of H. pylori infection on malignant neoplasms of the hepatobiliary tract, with an emphasis on possible prevention strategies.

HELICOBACTER AND HEPATOBILIARY DISEASES: UPDATE 2023

•Clinical studies have shown that hepatobiliary diseases of inflammatory and neoplastic origin are associated with Helicobacter infection. •Translocation and the ascending pathway are putative mechanisms for Helicobacter spp to enter the hepatobiliary system. •H. pylori infection has a systemic effect through the activity of pro-inflammatory cytokines, TNF-α, leukotrienes, interferon-β, interferon-γ, and acute phase proteins. •Histopathological confirmation is needed to present that H. pylori eradication prevents or improves hepatobiliary disease progression. Helicobacter Pylori (H. pylori) is one of the main infectious causes of gastroduodenal diseases, however, its role in developing different extragastric diseases has been proven. The possible involvement of H. pylori in the pathogenesis of cardiovascular, metabolic, neurodegenerative, skin, and hepatobiliary diseases is suggested. The bacterium has been found in tissue samples from the liver, biliary tract, and gallstones of animals and humans. However, the role of H. pylori infection in the pathogenesis of liver and biliary diseases has not been finally established. The histopathological confirmation of the positive effect of H. pylori eradication is needed. In addition, there are discussions on the clinical significance of other Helicobacter species. The review presents the data available for and against the involvement of H. pylori in hepatobi-liary disease development and progression.

Helicobacter Pylori and Autoimmune Diseases: Involving Multiple Systems

The modern Gastroenterology have witnessed an essential stride since Helicobacter pylori was first found in the stomach and then its pathogenic effect was discovered. According to the researches conducted during the nearly 40 years, it has been found that this bacterium is associated with a natural history of many upper gastrointestinal diseases. Epidemiological data show an increased incidence of autoimmune disorders with or after infection with specific microorganisms. The researches have revealed that H. pylori is a potential trigger of gastric autoimmunity, and it may be associated with other autoimmune diseases, both innate and acquired. This paper reviews the current support or opposition about H. pylori as the role of potential triggers of autoimmune diseases, including inflammatory bowel disease, autoimmune thyroiditis, type 1 diabetes mellitus, autoimmune liver diseases, rheumatoid arthritis, idiopathic thrombocytopenic purpura, systemic lupus erythematosus, as well as Sjogren’s syndrome, chronic urticaria and psoriasis, and tried to explain the possible mechanisms.

Aryl Hydrocarbon Receptor Deficiency in Intestinal Epithelial Cells Aggravates Alcohol-Related Liver Disease

BACKGROUND & AIMS

The ligand-activated transcription factor, aryl hydrocarbon receptor (AHR) can sense xenobiotics, dietary, microbial, and metabolic cues. Roles of Ahr in intestinal epithelial cells (IECs) have been much less elucidated compared with those in intestinal innate immune cells. Here, we explored whether the IEC intrinsic Ahr could modulate the development of alcohol-related liver disease (ALD) via the gut-liver axis.

METHODS

Mice with IEC specific Ahr deficiency (Ahr^ΔIEC) were generated and fed with a control or ethanol diet. Alterations of intestinal microbiota and metabolites were investigated by 16S ribosomal RNA sequencing, metagenomics, and untargeted metabolomics. AHR agonists were used to evaluate the therapeutic potentials of intestinal Ahr activation for ALD treatment.

RESULTS

Ahr^ΔIEC mice showed more severe liver injury after ethanol feeding than control mice. Ahr deficiency in IECs altered the intestinal metabolite composition, creating an environment that promoted the overgrowth of Helicobacter hepaticus and Helicobacter ganmani in the gut, enhancing their translocation to mesenteric lymph nodes and liver. Among the altered metabolites, isobutyric acid was increased in the cecum of ethanol-fed Ahr^ΔIEC mice relative to control mice. Furthermore, both H.hepaticus and isobutyric acid administration aggravated ethanol-induced liver injury in vivo and in vitro. Supplementation with AHR agonists, 6-formylindolo[3,2-b]carbazole and indole-3-carbinol, protected mice from ALD development by specifically activating intestinal Ahr without affecting liver Ahr function. Alcoholic patients showed lower intestinal AHR expression and higher H.hepaticus levels compared with healthy individuals.

CONCLUSIONS

Our results indicate that targeted restoration of IEC intrinsic Ahr function may present as a novel approach for ALD treatment.

Association between H. pylori infection and health Outcomes: an umbrella review of systematic reviews and meta-analyses

OBJECTIVE

Systematic reviews and meta-analyses have revealed the associations between H. pylori infection and various health outcomes. We aimed to evaluate the strength and breadth of evidence on the associations.

DESIGN

Umbrella review of systematic reviews and meta-analyses.

SETTING

No settings.

PARTICIPANTS

No patients involved.

DATA SOURCES

Embase, PubMed, Web of Science, Cochrane Library Databases, CNKI, VIP database and Wangfang database from inception to February 1, 2019.

OUTCOMES MEASURES

Diverse diseases (such as cancer and ischaemic heart disease).

RESULTS

Sixty articles reporting 88 unique outcomes met the eligible criteria. 74 unique outcomes had nominal significance (p<0.05). Of the outcomes with significance, 61 had harmful associations and 13 had beneficial associations. Furthermore, 73% (64) of the outcomes exhibited significant heterogeneity . Of the these meta-analyses, 32 had moderate to high heterogeneity (I²=50%-75%) and 24 had high heterogeneity (I²>75%). Moreover, 20% exhibited publication bias (p<0.1). In addition, 97% of the methodological qualities were rated 'critically low'. 36% of the evidence qualities of outcomes were rated 'low', 56% of the evidence qualities were rated 'very low' and 8% of the evidence qualities were rated 'moderate'. H. pylori infection may be associated with an increased risk of five diseases and a decreased risk of irritable bowel syndrome.

CONCLUSION

Although 60 meta-analyses explored 88 unique outcomes, moderate quality evidence only existed for six outcomes with statistical significance. H. pylori infection may be associated with a decreased risk of irritable bowel syndrome and an increased risk of hypertriglyceridemia, chronic cholecystitis and cholelithiasis, gestational diabetes mellitus, gastric cancer and systemic sclerosis.

TRIAL REGISTRATION

CRD42019124680.

No evidence to support a role for Helicobacter pylori infection and plasminogen binding protein in autoimmune pancreatitis and IgG4-related disease in a UK cohort

BACKGROUND AND OBJECTIVES

Helicobacter pylori (H.pylori) plasminogen binding protein (PBP) has been proposed as an antigen triggering autoimmune pancreatitis (AIP), the pancreatic manifestation of IgG4-related disease (IgG4-RD). We investigated exposure to H. pylori infection, cytokine response and immunological memory to H. pylori PBP in a prospective IgG4-RD cohort in the UK.

METHODS

Clinical and endoscopic evidence of peptic ulceration, serological H. pylori exposure and serum IgG4 levels were obtained in 55 IgG4-RD patients and 52 disease controls (DC) with autoimmune or inflammatory conditions with an elevated serum IgG4. Gastric and duodenal tissues were assessed for H. pylori and immunostained for IgG4. B and T cell ELISpot and cytokine luminex assays were used to detect immune responses to H. pylori PBP.

RESULTS

85% of IgG4-RD patients had pancreatic and/or biliary disease, 89% had extra-pancreatic manifestations, and 84% had an increased serum IgG4. Clinical dyspepsia (35.2%), gastritis (58%), peptic ulceration (7.4%) and H. pylori colonisation (24%) in IgG4-RD was similar to DC. In IgG4-RD, gastric tissue contained a chronic inflammatory infiltrate with a low IgG4+ plasma-cell count (<10/HPF; range 1-4/HPF), and duodenal specimens had an increased IgG4 count (>10/HPF; range 7-54) compared with DC (p < 0.01). Th1 and Th2 cytokine response and immunological B-cell memory to H. pylori PBP did not differ between IgG4-RD and DC.

CONCLUSIONS

In a prospective UK cohort, the prevalence of gastric ulceration, exposure to H. pylori, cytokine response and immunological memory to H. pylori PBP did not differ in IgG4-RD patients compared with DC. This study does not support a role for H. pylori PBP as a microbial antigen in IgG4-RD.

KEYWORDS FOR ABSTRACT

Peptic ulceration, Antigens, B cells, T cells, Interleukins, Helicobacter pylori.

Development and clinical application of a nested-PCR assay for Helicobacter hepaticus detection

AIM: To develop a nested-PCR assay for the detection of Helicobacter hepaticus (H. hepaticus) with a high sensitivity and specificity and to analyze its clinical application.

METHODS: The nested primers were designed based on the sequences of 16S rRNA gene of nine subtypes of H. hepaticus. After optimizing reaction condition, the sensitivity and specificity of the assay were examined using simulated feces and bile samples, related bacteria, mouse infection model and clinical inpatients samples.

RESULTS: The detection limit for H. hepaticus strain in simulated feces and bile samples was 10² CFU/mL. No specific PCR product was detected with DNA from Helicobacter pylori, Helicobacter bilis, Campylobacter jejuni, Escherichia coli, Enterococcus faecalis, Pseudomonas aeruginosa and Staphylococcus aureus. H. hepaticus was successfully detected in the liver, caecum and feces of experimentally infected mice. Moreover, H. hepaticus was successfully detected in the gallbladder bile, gallbladder mucosa and fecal samples from two of ten patients with cholelithiasis. PCR methods, medical intervention, sample type and management may all influence the detection.

CONCLUSION: Due to the high sensitivity and specificity of the PCR assay, it may be used to detect H. hepaticus infection. H. hepaticus may be associated with the pathogenesis of human cholelithiasis. PCR methods, medical intervention, sample type and management may all influence the detection of clinical samples.

Antibodies to Lactobacilli and Bifidobacteria in young children with different propensity to develop islet autoimmunity

The intestinal microbiota is essential to the maturation and homeostasis of the immune system. Immunoblot assays were used to establish the prevalence of serum IgG, IgM, and IgA antibodies specific for Bifidobacterium adolescentis, Bifidobacterium longum, and Lactobacillus rhamnosus GG proteins in young children presenting with or without type 1 diabetes (T1D). We demonstrated that children between the ages of 6 and 12 months had a substantial increase in the frequency of IgG antibodies specific for L. rhamnosus GG proteins. We measured IgG, IgM, and IgA class antibody reactivity against B. adolescentis DSM 20083, B. adolescentis DSM 20086, and B. longum DSM 20088 proteins demonstrating significantly higher IgA responses against B. adolescentis DSM 20083 strain proteins in children who developed islet autoimmunity and T1D later in life. B. adolescentis strains showed more IgM type antibodies in children who developed T1D later in life, but the difference was not statistically significant. B. longum proteins were recognized by IgG and IgA antibodies to a higher extent compared to other bacteria studied. These results confirm that differences in immune reactivity against some commensal strains in young children may represent a different risk factor for developing T1D.

Popular and unpopular infectious agents linked to primary biliary cirrhosis

Primary biliary cirrhosis (PBC) is a progressive cholestatic liver disease characterized by the autoimmune destruction of the biliary epithelial cells of the small and medium-size bile ducts. The disease affects middle aged women and usually affects more than one member within a family. The pathognomonic serological hallmark of the disease is the presence of circulating anti-mitochondrial antibodies, and disease-specific anti-nuclear antibodies. Susceptibility genes and environmental risk factors such as infections and smoking have been reported as important for the development of the disease. Among the environmental agents, infectious triggers are the best studied. Most of the work published so far has investigated the role of infections caused by Novosphingobium aromaticivorans and Escherichia coli. This review will discuss the popular and unpopular infectious agents causatively linked to PBC. It will also examine reports investigating the epidemiological aspects of the disease and their direct or indirect implications to bacterial-induced PBC.

Cholangiopathy with respect to biliary innate immunity

Biliary innate immunity is involved in the pathogenesis of cholangiopathies in cases of biliary disease. Cholangiocytes possess Toll-like receptors (TLRs) which recognize pathogen-associated molecular patterns (PAMPs) and play a pivotal role in the innate immune response. Tolerance to bacterial PAMPs such as lipopolysaccharides is also important to maintain homeostasis in the biliary tree, but tolerance to double-stranded RNA (dsRNA) is not found. Moreover, in primary biliary cirrhosis (PBC) and biliary atresia, biliary innate immunity is closely associated with the dysregulation of the periductal cytokine milieu and the induction of biliary apoptosis and epithelial-mesenchymal transition (EMT), forming in disease-specific cholangiopathy. Biliary innate immunity is associated with the pathogenesis of various cholangiopathies in biliary diseases as well as biliary defense systems.

Primary biliary cirrhosis associated with systemic sclerosis: diagnostic and clinical challenges

Patients with primary biliary cirrhosis (PBC) often have concurrent limited systemic sclerosis (SSc). Conversely, up to one-fourth of SSc patients are positive for PBC-specific antimitochondrial antibodies (AMA). The mechanisms responsible for the co-occurrence of these diseases are largely unknown. Genetic, epigenetic, environmental, and infectious factors appear to be important for the pathogenesis of the disease, but the hierarchy of events are not well defined. Patients with SSc and PBC have an increased morbidity and mortality compared with the general population, but whether the presence of both diseases in an affected individual worsens the prognosis and/or outcome of either disease is not clear. Some case reports suggested that the presence of SSc in PBC patents is associated with a more favorable prognosis of the liver disease, whereas others report an increased mortality in patients with PBC and SSc compared to patients with PBC alone. This paper discusses the features of patients with PBC-associated SSc. Our aims are to clarify some of the pathogenetic, diagnostic, and clinical challenges that are currently faced in the routine management of these patients. We also intend to provide some practical hints for practitioners that will assist in the early identification of patients with PBC-associated SSc.

Serodiagnosis of Helicobacter hepaticus infection in patients with liver and gastrointestinal diseases: western blot analysis and ELISA using a highly specific monoclonal antibody for H. hepaticus antigen

BACKGROUND

Helicobacter hepaticus infection might be associated with liver and biliary tract diseases. To investigate its pathogenic role, the properties of anti-H. hepaticus serum antibody in patients with liver and diseases were elucidated.

METHODS

Serum samples were collected from 166 patients-69 with liver diseases, 38 with upper gastrointestinal diseases, 17 with lower gastrointestinal diseases, 26 with biliary tract diseases, and 16 with pancreas diseases; 30 control sera were obtained from 30 healthy blood donors. Serum samples were analyzed by enzyme-linked immunosorbent assay (ELISA) and western blot using the new monoclonal antibody HR II-51.

RESULTS

Anti-H. hepaticus serum antibody concentrations in patients with liver disease (n = 69) were significantly increased compared with those in other disease groups (p = 0.014 to <0.001). Particularly, liver cirrhosis (n = 19) showed a significantly higher antibody level compared with other liver diseases (n = 50, p = 0.005) and healthy donors (n = 30, p = 0.0005), as well as a higher seroprevalence (68.4%) compared with other liver diseases (p = 0.05) and healthy donors (p = 0.004). Furthermore, the ELISA value in liver cirrhosis (n = 19) was significantly higher than that in patients with hepatitis B virus (HBV)-and/or hepatitis C virus (HCV)-infected chronic hepatitis (n = 15) (0.389 ± 0.084 vs. 0.350 ± 0.084, p = 0.029). However, there was no relationship between the total immunoglobulin concentration and the anti-H. hepaticus antibody level in each liver disease (Spearman's rank correlation coefficient [rs] < 0.225).

CONCLUSIONS

H. hepaticus infection might play a role in the development of liver diseases; in particular, it might increase the risk of the development of HBV- and/or HCV-infected liver diseases.

Serodiagnosis of Helicobacter hepaticus infection in patients with liver and gastrointestinal diseases: western blot analysis and ELISA using a highly specific monoclonal antibody for H. hepaticus antigen

BACKGROUND

Helicobacter hepaticus infection might be associated with liver and biliary tract diseases. To investigate its pathogenic role, the properties of anti-H. hepaticus serum antibody in patients with liver and diseases were elucidated.

METHODS

Serum samples were collected from 166 patients-69 with liver diseases, 38 with upper gastrointestinal diseases, 17 with lower gastrointestinal diseases, 26 with biliary tract diseases, and 16 with pancreas diseases; 30 control sera were obtained from 30 healthy blood donors. Serum samples were analyzed by enzyme-linked immunosorbent assay (ELISA) and western blot using the new monoclonal antibody HR II-51.

RESULTS

Anti-H. hepaticus serum antibody concentrations in patients with liver disease (n = 69) were significantly increased compared with those in other disease groups (p = 0.014 to <0.001). Particularly, liver cirrhosis (n = 19) showed a significantly higher antibody level compared with other liver diseases (n = 50, p = 0.005) and healthy donors (n = 30, p = 0.0005), as well as a higher seroprevalence (68.4%) compared with other liver diseases (p = 0.05) and healthy donors (p = 0.004). Furthermore, the ELISA value in liver cirrhosis (n = 19) was significantly higher than that in patients with hepatitis B virus (HBV)-and/or hepatitis C virus (HCV)-infected chronic hepatitis (n = 15) (0.389 ± 0.084 vs. 0.350 ± 0.084, p = 0.029). However, there was no relationship between the total immunoglobulin concentration and the anti-H. hepaticus antibody level in each liver disease (Spearman's rank correlation coefficient [rs] < 0.225).

CONCLUSIONS

H. hepaticus infection might play a role in the development of liver diseases; in particular, it might increase the risk of the development of HBV- and/or HCV-infected liver diseases.

Celiac disease in patients with type 1 diabetes: a condition with distinct changes in intestinal immunity?

Two common chronic childhood diseases-celiac disease (CD) and type 1 diabetes (T1D)-result from complex pathological mechanisms where genetic susceptibility, environmental exposure, alterations in intestinal permeability and immune responses play central roles. In this study, we investigated whether these characteristics were universal for CD independently of T1D association. For this purpose, we studied 36 children with normal small-bowel mucosa and 26 children with active CD, including 12 patients with T1D. In samples from the small-bowel mucosa, we detected the lowest expression of tight junction protein 1 (TJP1) mRNA in CD patients with T1D, indicating an increase in intestinal permeability. Furthermore, these samples displayed the highest expression of forkhead box P3 (FoxP3) mRNA, a marker for regulatory T cells, as compared with other patient groups. At the same time, serum levels of IgA antibodies specific for the CD-related antigens deamidated gliadin and tissue transglutaminase (tTG) were the highest in CD patients with T1D. In contrast, no significant differences were found in IgA or IgG antibodies specific for bovine beta-lactoglobulin or Bifidobacterium adolescentis DSM 20083-derived proteins. There were also no differences in the transamidating activity of serum autoantibodies between patients and control individuals. Our results show that patients with T1D and newly detected CD exhibit severely altered intestinal permeability, strong local immune activation and increased immunoregulatory mechanisms in the small bowel. Further study is required to determine whether these extreme changes in this CD subgroup are due to some specific environmental factors (virus infections), unknown genetic effects or autoimmune reactions to antigenic targets in intracellular tight junctions.

Horizontal gene transfers with or without cell fusions in all categories of the living matter

This article reviews the history of widespread exchanges of genetic segments initiated over 3 billion years ago, to be part of their life style, by sphero-protoplastic cells, the ancestors of archaea, prokaryota, and eukaryota. These primordial cells shared a hostile anaerobic and overheated environment and competed for survival. "Coexist with, or subdue and conquer, expropriate its most useful possessions, or symbiose with it, your competitor" remain cellular life's basic rules. This author emphasizes the role of viruses, both in mediating cell fusions, such as the formation of the first eukaryotic cell(s) from a united crenarchaeon and prokaryota, and the transfer of host cell genes integrated into viral (phages) genomes. After rising above the Darwinian threshold, rigid rules of speciation and vertical inheritance in the three domains of life were established, but horizontal gene transfers with or without cell fusions were never abolished. The author proves with extensive, yet highly selective documentation, that not only unicellular microorganisms, but the most complex multicellular entities of the highest ranks resort to, and practice, cell fusions, and donate and accept horizontally (laterally) transferred genes. Cell fusions and horizontally exchanged genetic materials remain the fundamental attributes and inherent characteristics of the living matter, whether occurring accidentally or sought after intentionally. These events occur to cells stagnating for some 3 milliard years at a lower yet amazingly sophisticated level of evolution, and to cells achieving the highest degree of differentiation, and thus functioning in dependence on the support of a most advanced multicellular host, like those of the human brain. No living cell is completely exempt from gene drains or gene insertions.

Xanthogranulomatous cholecystitis complicated with primary sclerosing cholangitis: report of a case

Patients with primary sclerosing cholangitis (PSC) are at an increased risk for biliary tract carcinoma. The preoperative diagnosis of a biliary tract tumor as a malignancy is difficult, even using new modalities such as multidetector computed tomography (MD-CT), magnetic resonance cholangiopancreatography (MRCP), endoscopic retrograde cholangiography (ERC), and (18)F-fluorodeoxyglucose positron emission tomography (FDG-PET). Surgery is considered to be first line of treatment when these examinations suggest the presence of malignancy in the biliary tract, depending on both the curability of the cancer and the impaired liver function due to PSC. The management of gallbladder masses in patients with PSC remains problematic due to difficulties with the precise diagnosis and adequate surgery. Xanthogranulomatous cholecystitis (XGC) is a type of chronic cholecystitis, and sometimes coexists with gallbladder cancer. It is very difficult to make a preoperative diagnosis differentiating these two diseases. This report presents the case of a patient with XGC, who had been suspected of having gallbladder cancer before surgery, because the tumorous lesion emerged within a year and showed a focally increased uptake by FDG-PET during the follow up for PSC for years. This is the first case of XGC discovered during treatment for PSC.

Biliary innate immunity: function and modulation

Biliary innate immunity is involved in the pathogenesis of cholangiopathies in patients with primary biliary cirrhosis (PBC) and biliary atresia. Biliary epithelial cells possess an innate immune system consisting of the Toll-like receptor (TLR) family and recognize pathogen-associated molecular patterns (PAMPs). Tolerance to bacterial PAMPs such as lipopolysaccharides is also important to maintain homeostasis in the biliary tree, but tolerance to double-stranded RNA (dsRNA) is not found. In PBC, CD4-positive Th17 cells characterized by the secretion of IL-17 are implicated in the chronic inflammation of bile ducts and the presence of Th17 cells around bile ducts is causally associated with the biliary innate immune responses to PAMPs. Moreover, a negative regulator of intracellular TLR signaling, peroxisome proliferator-activated receptor-γ (PPARγ), is involved in the pathogenesis of cholangitis. Immunosuppression using PPARγ ligands may help to attenuate the bile duct damage in PBC patients. In biliary atresia characterized by a progressive, inflammatory, and sclerosing cholangiopathy, dsRNA viruses are speculated to be an etiological agent and to directly induce enhanced biliary apoptosis via the expression of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL). Moreover, the epithelial-mesenchymal transition (EMT) of biliary epithelial cells is also evoked by the biliary innate immune response to dsRNA.

Antigenic proteins of Lactobacillus acidophilus that are recognised by serum IgG antibodies in children with type 1 diabetes and coeliac disease

Immune responses to lactobacilli have been so far insufficiently investigated in patients with autoimmune diseases. We used whole-cell lysate of an indigenous Lactobacillus acidophilus strain isolated from an Estonian child to study serum IgG antibodies in children groups with type 1 diabetes [insulin dependent diabetes mellitus (IDDM)] (n = 21, age 4-18 yr) and with acute coeliac disease (CD) (n = 20, age 0.6-15 yr) and to compare the results with the controls (n = 24, age 2-17 yr). We found that our developed 1-D immunoblot assay readily enables to reveal antibodies against 28 L. acidophilus antigenic proteins in patients' and controls' sera. As verified by immunoproteomics analysis with 2-D and LC ESI-MS/MS the antigens of L. acidophilus were mainly common cytoplasmic proteins GroEL (HSP60), enolase, transcription factor EF-Ts and EF-Tu. However, in addition we identified formyl-CoA transferase being target for antibodies in every tested IDDM patients' serum. We have characterized for the first time the antigenic profile of L. acidophilus whole-cell lysate using sera from children with IDDM, CD, and controls. The different prevalence of reactions against tested antigens in patients and controls sera may indicate significant differences in immune system and commensal bacteria cross-talk in these groups.

Helicobacter hepaticus cytolethal distending toxin causes cell death in intestinal epithelial cells via mitochondrial apoptotic pathway

BACKGROUND

Helicobacter hepaticus, the prototype for enterohepatic Helicobacter species, colonizes the lower intestinal and hepatobiliary tracts of mice and causes typhlocolitis, hepatitis, and hepatocellular carcinoma in susceptible mouse strains. Cytolethal distending toxin (CDT) is the only known virulence factor found in H. hepaticus. CDT of several Gram-negative bacteria is associated with double-stranded DNA breaks resulting in cell cycle arrest and death of a wide range of eukaryotic cells in vitro. We previously observed H. hepaticus CDT (HhCDT) mediated apoptosis in INT407 cells. However, the exact mechanism for the induction of the apoptotic pathway by HhCDT is unknown. The objective of this study was to identify the apoptotic signaling pathway induced by HhCDT in INT407 cells.

MATERIALS AND METHODS

INT407 cells were incubated with or without recombinant HhCDT for 0-72 hours. H2AX phosphorylation and apoptotic parameters were analyzed.

RESULTS

H2AX was phosphorylated 24 hours postexposure to HhCDT. Expression of pro-apoptotic Bax protein was upregulated after 24 hours, while Bcl(2) expression decreased. Cytochrome c was released from mitochondria after 12-24 hours of exposure. Concurrently, caspase 3/7 and 9 were activated. However, pretreatment of INT407 cells with caspase inhibitor (Z-VAD-FMK) inhibited the activation of caspase 3/7 and 9. Significant activity of caspase 8 was not observed in toxin treated cells. Activation of caspase 3/7 and caspase 9 confirms the involvement of the mitochondrial apoptotic pathway in HhCDT-treated cells.

CONCLUSION

These findings show, for the first time, the ability of HhCDT to induce apoptosis via the mitochondrial pathway.

Helicobacter species DNA in liver and gastric tissues in children and adolescents with chronic liver disease

OBJECTIVE

Enterohepatic Helicobacter species (EHS) have previously been found in adults with hepatobiliary diseases. Here, we report the prevalence of Helicobacter pylori and EHS in liver and gastric tissue in children and adolescents with chronic liver disease (CLD).

MATERIAL AND METHODS

Seventy-seven consecutive children and adolescents with CLD with or without ulcerative colitis or Crohn's disease (UC/CD) were investigated. Tissue samples were analysed using a Helicobacter genus-specific 16S rDNA polymerase chain reaction (PCR) assay and DNA-sequence analysis. Sera from 61 subjects were also analysed using enzyme immunoassay and immunoblotting.

RESULTS

The Helicobacter PCR was positive in 3/23 (13%) livers from patients with primary sclerosing cholangitis and UC, and in 1/2 livers from patients with autoimmune hepatitis (AIH) and UC. Sequenced PCR products matched the 16S rDNA of H. hepaticus, H. muridarum, H. canis, and H. pylori, respectively. H. ganmani and H. bilis were detected in gastric tissues from two AIH patients. H. hepaticus and H. pullorum were found in livers from two patients with acute liver failure and intrahepatic cholestasis. Antibody reactivity to Helicobacter cell-surface proteins was negative.

CONCLUSIONS

H. pylori and EHS can be detected in the livers of some patients with UC and concomitant liver disease, as well as in other children with liver diseases. Multicentre studies from different locations are needed to find out whether these bacteria play a pathogenetic role or whether their presence is an epiphenomenon.

Immunoblot analysis as an alternative method to diagnose enterohepatic Helicobacter infections

INTRODUCTION

Enterohepatic Helicobacter species have been associated with chronic infections of the hepatobiliary tract and lower bowel in naturally and experimentally infected mice, Helicobacter-infected animals should thus not be used in studies of diseases associated with chronic inflammation. Helicobacter species induce inflammation and modulate host immune responses, thus emphasizing the need to diagnose these infections in laboratory animals.

MATERIALS AND METHODS

An immunoblot assay was developed to analyze antibodies to enterohepatic Helicobacter species in naturally colonized laboratory mouse colonies. We evaluated the serum antibody responses to cell surface proteins of H. bilis, H. hepaticus, and H. ganmani in 188 mouse sera from four different university animal facilities. Lower bowel tissue specimens from 56 of these animals were available and analyzed by polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) and the results compared with matched immunoblot patterns.

RESULTS

Specific antibody reactivity to H. bilis was detected in 8 of 186 (4.3%) sera, to H. hepaticus in 45 of 184 (24%) sera, and to H. ganmani in 51 of 188 (27%) of tested sera. These results were compared with PCR-DGGE analyses of tissue samples of corresponding animals, and concordance between the two diagnostic tests was found in 96% for H. bilis, in 91% for H. hepaticus, and in 82% for H. ganmani. The PCR-DGGE also detected DNA of H. typhlonius, H. sp. flexispira, and H. rodentium.

CONCLUSIONS

Infection with enterohepatic species was common in the laboratory mouse colonies tested, independent of strain and stock. Immunoblot analysis seems to be a promising diagnostic tool to monitor enterohepatic Helicobacter species infections of laboratory rodents.

Atypical p-ANCA in PSC and AIH: a hint toward a "leaky gut"?

Primary sclerosing cholangitis (PSC) and autoimmune hepatitis (AIH) are enigmatic chronic inflammatory diseases of the liver, which are frequently associated with chronic inflammatory bowel diseases. Both types of liver disease share various distinct autoantibodies such as atypical perinuclear antineutrophil cytoplasmic antibodies (p-ANCA), and thus are considered autoimmune disorders with atypical features. The discovery that atypical p-ANCA recognize both tubulin beta isoform 5 in human neutrophils and the bacterial cell division protein FtsZ has renewed the discussion on the potential role of microorganisms in the pathogenesis of both diseases. In this paper, we review the evidence for microbial infection in PSC and AIH and discuss new concepts how cross-recognition between microbial antigens in the gut and host components by the immune system along with stimulation of pattern recognition receptors might give rise to chronic hepatic inflammatory disorders with features of autoimmunity.

Bacteria and primary biliary cirrhosis

Infectious agents have been postulated to play a pathogenic role in the loss of immunological tolerance and the induction of primary biliary cirrhosis, an immune-mediated cholestatic liver disease characterized by progressive destruction of the small intrahepatic bile ducts and subsequent cirrhosis and liver failure. This review discusses emerging issues implicating infectious agents such as Escherichia coli, mycobacteria, chlamydia, helicobacter species, lactobacilli, Novosphingobium aromaticivorans, and betaretroviruses in the pathogenesis of primary biliary cirrhosis. We also review the immunopathological mechanisms responsible for the induction of the disease with special emphasis on the role of molecular mimicry and microbial/self immunological cross-reactivity.

Characterization and application of a new monoclonal antibody with high specificity for Helicobacter hepaticus

BACKGROUND AND AIMS

Infection with Helicobacter hepaticus is suggested to play a role in the pathogenesis of chronic liver disease in humans. However, reactive antigens among Helicobacter species make the development of an H. hepaticus ELISA test with high specificity difficult. A new monoclonal antibody from a hybridoma clone (HRII-51) showed high specificity to H. hepaticus without cross-reaction to other gastrointestinal bacteria.

METHODS

The molecular weight of HRII-51 immunoreactive antigen was examined by Western blot of H. hepaticus probed with the monoclonal antibody HRII-51. A HRII-51-immunoreactive antigen capture ELISA was prepared in which the specific antigen was anchored by HRII-51-immobilized ELISA plate. Accuracy of HRII-51 antigen capture ELISA was examined using sera obtained from mice inoculated with Helicobacter species. Specificity of HRII-51 antigen capture ELISA was compared to that of H. hepaticus antigen-based ELISA using human sera with absorption by H. pylori cell lysate.

RESULTS

HRII-51 immunoreactive antigen had a molecular weight of 15 kDa. Sensitivity and specificity of HRII-51 antigen capture ELISA were 87.0% and 97.6% in mice inoculated with Helicobacter species. In human sera, modification of the results by absorption with H. pylori lysate was smaller in HRII-51 antigen capture ELISA comparing with H. hepaticus-antigen-based ELISA.

CONCLUSION

Use of the HRII-51 antigen capture ELISA would be a useful approach for the serodiagnosis of H. hepaticus infection in both experimental animals and humans.

The unfinished business of primary biliary cirrhosis

In nearly every multifactorial human disease, there are three periods that characterize our understanding and definition. First, there is a period in which there is rapid accumulation of descriptive data. Second, there is a longer and slower period as information is obtained that redefines and expands basic and clinical knowledge that lacks the final and important area of understanding aetiology and therapeutic intervention. Third, which is much less common for most diseases, is the vigorous definition of pathobiology and treatment. These phases are well illustrated by our current understanding of primary biliary cirrhosis (PBC). The term PBC was first used nearly 60 years ago and for the first 40 or so years, the primary research efforts were directed at clinical definitions and pathology. Subsequently, with the advent of molecular biology, there began a rigorous dissection of the immune response and, in particular, a better understanding of anti-mitochondrial antibodies. These efforts have greatly helped in our understanding of not only the effector mechanisms of disease, but also the uniqueness of the primary target tissue, biliary epithelium. However, this research has still not led to successful translation for specific therapy.

Cross-reactivity between immune responses to Helicobacter bilis and Helicobacter pylori in a population in Thailand at high risk of developing cholangiocarcinoma

Helicobacter bilis DNA has been detected in human tissue and is a candidate for etiologic investigations on the causes of hepatic and biliary tract diseases, but reliable serologic tests need to be developed in order to pursue such investigations. The scope of this study was to assess the specificity of two assays for H. bilis immune response allowing for H. pylori, and their cross-reactivity in a population in Thailand at high risk for cholangiocarcinoma. Plasma samples from 92 Thai volunteers were independently tested in two laboratories (Massachusetts Institute of Technology [MIT] and Lund). MIT performed three analyses of H. pylori and H. bilis based either on (i) outer membrane protein (OMP) with no preabsorption or on antigens derived from whole-cell sonicate before (ii) or after (iii) preabsorption with H. pylori sonicate protein. Lund used cell surface proteins from H. pylori and H. bilis as antigens. Testing for H. bilis was preabsorbed with a whole-cell lysate of H. pylori. More than 80% of the samples were positive for H. pylori in both laboratories. As tested by MIT, 58.7% (95% confidence interval, 47.9 to 68.9%) were positive for H. bilis by OMP and 44.5% (34.1 to 55.3%) were positive for H. bilis sonicate protein, but only 15.2% (8.6 to 24.2%) remained positive after preabsorption with H. pylori sonicate protein. Lund found 34.5% of the samples positive for H. bilis (22.0 to 41.0%), which was statistically compatible with all three MIT results. Serologic responses to OMPs of the two bacteria coincided in 66 and 45% of the samples in the MIT and Lund assays, respectively. We found high cross-reactivity between the immune responses to H. pylori and H. bilis antigens. More-specific H. bilis antigens need to be isolated to develop serologic tests suitable for epidemiological studies.

Biliary innate immunity and cholangiopathy

The intrahepatic biliary tree is a conduit of bile which contains pathogen-associated molecular patterns (PAMPs) such as lipopolysaccharide (LPS) originated from intestinal flora. Human biliary epithelial cells (BEC) express toll-like receptors (TLR) and intracellular adaptor molecules and secrete antibiotic peptides and (pro)inflammatory cytokines via the activation of nuclear transcription factors. However, although human bile contains several PAMPs in normal as well as diseased livers, PAMPs physiologically do not elicit an inflammatory response in the biliary tree, suggesting that tolerance against commensal PAMPs including LPS (endotoxin tolerance) is important in maintaining the homeostasis of biliary innate immunity. Negative regulators of intracellular TLR signalings, peroxisome proliferator activating receptor-gamma (PPAR-gamma) and IRAK-M, are associated with the endotoxin tolerance in BEC. In vivo, PPAR-gamma and IRAK-M are ubiquitously expressed in intrahepatic biliary epithelium, while the expression of PPAR-gamma is reduced in damaged bile ducts of primary biliary cirrhosis (PBC). In addition to antibiotic peptides, several cytokines andchemokines are also secreted from BEC as an innate immune response and these humoral components participate in attracting immunocytes and modulating peribiliary cytokine milieu. BEC have receptors for several cytokines and the expression of TLR in BEC is affected by cytokines, suggesting that biliary innate immunity is regulated by an acquired immunity. A T-helper (Th)1-type cytokine, interferon-gamma, downregulates PPAR-gamma and upregulates TLR, and consequently increases the susceptibility of biliary innate immunity. Because periductal cytokine milieu in PBC is Th1-dominant, the increased susceptibility to PAMPs may be associated with the development of cholangiopathy in PBC. Biliary innate immunity is speculated to be associated with the pathogenesis of biliary diseases as well as the defense against biliary microbial infection.

Biliary epithelial cell antibodies link adaptive and innate immune responses in primary sclerosing cholangitis

BACKGROUND & AIMS

Primary sclerosing cholangitis (PSC) is an autoimmune liver disease with destruction of hepatic bile ducts. A high frequency of biliary epithelial cell antibodies (BEC-Ab) is present in PSC. Here, we studied the mechanisms and signaling pathways used by these Ab in causing BEC dysfunction.

METHODS

Immunoassays were performed using freshly isolated BECs to study the signaling capacity of purified immunoglobulin (Ig) G and F(ab)'(2) fractions from 33 patients with PSC with anti-BEC-Ab.

RESULTS

We provide evidence that stimulation of BECs with PSC IgG, but not control IgG, induced expression of Toll-like receptor (TLR) 4 and TLR9 and specific phosphorylation of extracellular signal-regulated kinase (ERK) 1/2 as well as the transcription factors ELK-1 and nuclear factor kappaB. A specific inhibitor of ERK1/2 abrogated phosphorylation of ELK-1 and protein expression of TLR4 but not TLR9 on BECs. TLR-expressing BECs, when further stimulated with lipopolysaccharide and CpG DNA, produced high levels of interleukin-1beta, interleukin-8, interferon gamma, tumor necrosis factor alpha, granulocyte-macrophage colony-stimulating factor, and transforming growth factor beta. Bile ducts stained positively for TLR4 and TLR9 in 58% of liver specimens taken from patients with PSC with BEC-Ab, as compared with 14% in those without BEC-Ab and also less frequently in diseased control livers.

CONCLUSIONS

Our data show that binding of PSC BEC-Ab initiates ERK1/2 signaling and up-regulation of TLR, which upon ligation induces BECs to produce cytokines/chemokines, leading to the possible recruitment of inflammatory cells. Thus, in PSC, BECs are not only targets of the immune attack but may also be active participants and mediators of their own destruction. BEC-Ab may be critical regulators of cholangitis in PSC.

Detection of Helicobacter species in chronic liver disease and chronic inflammatory bowel disease

AIM

To study the association between helicobacters and chronic liver diseases and chronic inflammatory bowel diseases.

PATIENTS AND METHODS

Thirty-two patients with various chronic liver diseases and 137 patients with inflammatory bowel disease were enrolled. Antibodies to H. pylori, H. hepaticus, H. bilis, and H. pullorum were measured by enzyme immunoassay (EIA), and sera positive in a non-pylori helicobacter EIA were further examined by immunoblot assay. Detection of Helicobacter DNA in liver biopsies was done by denaturating gradient gel electrophoresis of PCR products (PCR-DGGE) and DNA sequence analysis.

RESULTS

Six inflammatory bowel disease patients, four with ulcerative colitis and two with Crohn's disease, and one liver disease patient with autoimmune cholangitis had antibodies to non-pylori helicobacters by an immunoblot assay. Four immunoblot assay-negative patients, three with autoimmune and one with non-autoimmune liver disease, had Helicobacter DNA in liver biopsies; three of the polymerase chain reaction (PCR) products were closely related to non-pylori helicobacters.

CONCLUSION

Evidence for non-pylori helicobacters was scant in Finnish patients with inflammatory bowel disease or chronic but not end stage liver disease. We cannot, however, rule out their role in these diseases.

Immunopathogenesis of primary sclerosing cholangitis

Primary sclerosing cholangitis (PSC) is a chronic cholestatic liver disease of unknown etiology;however, lymphocytic portal tract infiltration is suggestive of an immune-mediated basis for PSC. Associations with inflammatory bowel disease--especially ulcerative colitis--and with other auto-immune diseases, together with genetic associations, further suggest that PSC may be an immune-mediated disease. The immunogenetics of PSC have been the subject of active research, and several human leukocyte antigen (HLA)- and non-HLA-associated genes have been implicated in the development of the disease. Lymphocytes derived from the inflamed gut may enter the liver via the enterohepatic circulation to cause hepatic disease.PSC may be triggered in genetically susceptible individuals by infections or toxins entering the portal circulation through a permeable colon and, therefore, evoking an abnormal immune response.

Differential detection of five mouse-infecting helicobacter species by multiplex PCR

Several species of helicobacter have been isolated from laboratory mice, including H. bilis, H. hepaticus, H. muridarum, H. rodentium, and H. typhlonius, which appear to be the most common. The most widely used published method for molecular detection of these agents is PCR amplification of a conserved region of 16S rRNA, but differential speciation requires restriction enzyme digestion of the amplicons. This study was undertaken to determine PCR conditions that would simultaneously and specifically identify each of the five common species without restriction enzyme analyses. First, we designed novel and specific PCR primers for H. bilis, H. hepaticus, H. muridarum, H. rodentium, and H. typhlonius, using sequences from the heterologous regions of 16S rRNA. Because of comigration of amplified products, we next identified P17, an H. bilis-specific protein; P25, an H. hepaticus-specific protein; and P30, an H. muridarum-specific protein by screening genomic DNA expression libraries of each species. Primers were designed from these three genes, plus newly designed, species-specific 16S rRNA primers for H. rodentium and H. typhlonius that could be utilized for a five-plex PCR. The sizes of the amplicons from H. bilis, H. hepaticus, H. muridarum, H. rodentium, and H. typhlonius were 435, 705, 807, 191, and 122 bp, respectively, allowing simultaneous detection and effective discrimination among species.

Extension of the species Helicobacter bilis to include the reference strains of Helicobacter sp. flexispira taxa 2, 3 and 8 and Finnish canine and feline flexispira strains

The evolution and taxonomy of enterohepatic Helicobacter species with flexispira morphology were studied by a polyphasic approach including phenotypic characterization, analysis of 16S rRNA and ureB gene sequences and dot-blot DNA-DNA hybridization of whole genomic DNA. In addition, available phylogenetic data on the HSP60 gene were used in the analysis. The study included 14 Finnish canine and feline flexispira strains, the reference strains of Helicobacter sp. flexispira taxa 2, 3 and 8 and Helicobacter bilis ATCC 51630(T). Phenotypically, all canine and feline strains were similar to H. bilis. Analysis of 16S rRNA gene sequences of these strains revealed a similarity of 97-99.5 %. Similarity of ureB nucleotide and amino acid sequences within the studied flexispira group was 97-100 % and 99-100 %, respectively, revealing close relatedness. ureB sequences of Helicobacter hepaticus had only 64-66 % similarity to the flexispira group. The similarity to Helicobacter trogontum was 81.5-82.1 %. High levels of DNA-DNA hybridization between the strains were found in dot-blot tests. Polyphasic analysis of the phenotypic and genotypic characteristics of the Finnish flexispira strains and the reference strains of taxa 2, 3 and 8 showed that they differed from other Helicobacter species and are members of the previously described species H. bilis. In addition, canine strain F56 differed in all phylogenetic analyses from the H. bilis group and probably represents a novel Helicobacter species.

A concept on the role of Helicobacter pylori infection in autoimmune pancreatitis

Autoimmune pancreatitis, an inflammatory process of the pancreas due to an autoimmune mechanism establishing etiology of chronic pancreatitis, is characterized by the presence of autoantibodies, hypergammaglobulinemia, pancreatic enlargement, pancreatic duct strictures, and pathologic features of fibrotic changes with intense, mainly lymphocytic infiltrations, which may contribute to tissue destruction probably by apoptosis. In almost 60% of the cases, this type of pancreatitis coexists with other autoimmune diseases such as Sjogren's syndrome, sclerosing extrahepatic cholangitis, primary biliary cirrhosis, autoimmune hepatitis, or other extrapancreatic disorders, and recently with gastric peptic ulceration. The diversity of extrapancreatic lesions with similar histopathologic findings suggests general involvement of the digestive system in this disease, although the presence of such involvement has not been fully elucidated. Similarly, Helicobacter pylori (H. pylori) infection, a well known cause of gastric ulcer, has been associated, via molecular mimicry of host structures by its constituents with the same autoimmune conditions, also characterized by fibrotic changes and/or lymphoplasmacytic inflammations, accompanied by aberrations of T cell apoptosis that contribute to hepatobiliary- or extrahepatic-tissue destruction. Considering that H. pylori is involved in the pathogenesis and pathophysiology of these autoimmune disorders, we propose that this organism might trigger autoimmune pancreatitis through induction of autoimmunity and apoptosis.

A concept on the role of Helicobacter pylori infection in autoimmune pancreatitis

Autoimmune pancreatitis, an inflammatory process of the pancreas due to an autoimmune mechanism establishing etiology of chronic pancreatitis, is characterized by the presence of autoantibodies, hypergammaglobulinemia, pancreatic enlargement, pancreatic duct strictures, and pathologic features of fibrotic changes with intense, mainly lymphocytic infiltrations, which may contribute to tissue destruction probably by apoptosis. In almost 60% of the cases, this type of pancreatitis coexists with other autoimmune diseases such as Sjogren's syndrome, sclerosing extrahepatic cholangitis, primary biliary cirrhosis, autoimmune hepatitis, or other extrapancreatic disorders, and recently with gastric peptic ulceration. The diversity of extrapancreatic lesions with similar histopathologic findings suggests general involvement of the digestive system in this disease, although the presence of such involvement has not been fully elucidated. Similarly, Helicobacter pylori (H. pylori) infection, a well known cause of gastric ulcer, has been associated, via molecular mimicry of host structures by its constituents with the same autoimmune conditions, also characterized by fibrotic changes and/or lymphoplasmacytic inflammations, accompanied by aberrations of T cell apoptosis that contribute to hepatobiliary- or extrahepatic-tissue destruction. Considering that H. pylori is involved in the pathogenesis and pathophysiology of these autoimmune disorders, we propose that this organism might trigger autoimmune pancreatitis through induction of autoimmunity and apoptosis.

A concept on the role of Helicobacter pylori infection in autoimmune pancreatitis

Autoimmune pancreatitis, an inflammatory process of the pancreas due to an autoimmune mechanism establishing etiology of chronic pancreatitis, is characterized by the presence of autoantibodies, hypergammaglobulinemia, pancreatic enlargement, pancreatic duct strictures, and pathologic features of fibrotic changes with intense, mainly lymphocytic infiltrations, which may contribute to tissue destruction probably by apoptosis. In almost 60% of the cases, this type of pancreatitis coexists with other autoimmune diseases such as Sjogren's syndrome, sclerosing extrahepatic cholangitis, primary biliary cirrhosis, autoimmune hepatitis, or other extrapancreatic disorders, and recently with gastric peptic ulceration. The diversity of extrapancreatic lesions with similar histopathologic findings suggests general involvement of the digestive system in this disease, although the presence of such involvement has not been fully elucidated. Similarly, Helicobacter pylori (H. pylori) infection, a well known cause of gastric ulcer, has been associated, via molecular mimicry of host structures by its constituents with the same autoimmune conditions, also characterized by fibrotic changes and/or lymphoplasmacytic inflammations, accompanied by aberrations of T cell apoptosis that contribute to hepatobiliary- or extrahepatic-tissue destruction. Considering that H. pylori is involved in the pathogenesis and pathophysiology of these autoimmune disorders, we propose that this organism might trigger autoimmune pancreatitis through induction of autoimmunity and apoptosis.

Identification of cholelithogenic enterohepatic helicobacter species and their role in murine cholesterol gallstone formation

BACKGROUND & AIMS

Helicobacter spp are common inhabitants of the hepatobiliary and gastrointestinal tracts of humans and animals and cause a variety of well-described diseases. Recent epidemiologic results suggest a possible association between enterohepatic Helicobacter spp and cholesterol cholelithiasis, chronic cholecystitis, and gallbladder cancer. To test this, we prospectively investigated the effects of Helicobacter spp infection in cholesterol gallstone pathogenesis in the highly susceptible C57L/J mouse model.

METHODS

Helicobacter spp-free adult male C57L mice were infected with several different enterohepatic Helicobacter spp or left uninfected and fed either a lithogenic diet or standard mouse chow for 8 and 18 weeks. At the conclusion of the study, bile was examined microscopically and diagnostic culture and polymerase chain reaction were performed.

RESULTS

Mice infected with Helicobacter bilis or coinfected with Helicobacter hepaticus and Helicobacter rodentium and fed a lithogenic diet developed cholesterol gallstones at 80% prevalence by 8 weeks compared with approximately 10% in uninfected controls. Monoinfections with H hepaticus , Helicobacter cinaedi , and H rodentium gave a cholesterol gallstone prevalence of 40%, 30%, and 20%, respectively; the latter 2 groups did not differ significantly from uninfected animals. Neither infected nor uninfected mice fed a chow diet developed cholesterol gallstones.

CONCLUSIONS

These findings, along with prior epidemiologic studies, suggest that Helicobacter spp play a major role in the pathophysiology of cholesterol gallstone formation in mice and perhaps humans.

Extensive homology between the major immunodominant mitochondrial antigen in primary biliary cirrhosis and Helicobacter pylori does not lead to immunological cross-reactivity

BACKGROUND

Primary biliary cirrhosis (PBC) is an immune-mediated chronic cholestatic disease characterized by the presence of antibodies directed predominantly against the E2 subunit of the pyruvate dehydrogenase complex (PDC-E2). What provokes tolerance breakdown in PBC remains to be established, though there is evidence to indicate that microbes may induce anti-mitochondrial antibodies (AMA) through a mechanism of molecular mimicry.

METHODS

Having found that urease beta (UREB)(22-36) antigen of Helicobacter pylori (HELPY) shares extensive (87%) similarity with PDC-E2(212-226), the major mitochondrial autoepitope, it was hypothesized that this would also lead to cross-reactivity. The UREB/PDC-E2 mimics were thus constructed and tested by ELISA in 112 PBC patients and 114 controls.

RESULTS

Reactivity to PDC-E2(212-226) was found in 104 patients but to UREB(22-36) in only 2. In these two patients, the double reactivity was not cross-reactive. The lack of surface antibody accessibility to UREB(22-36), as demonstrated through three-dimensional model prediction analysis, may explain this unexpected finding. There was some speculation on whether HELPY UREB(22-36) might act as a cross-reactive CD4 T-cell epitope. All seven PBC patients, tested in a standard proliferation assay against PDC-E2(212-226), gave a positive response. All seven were unresponsive to HELPY UREB(22-36). The pattern of reactivity to HELPY antigens by immunoblot was similar between anti-PDC-E2-positive and negative PBC cases, as well as between PBC patients and controls.

CONCLUSION

Contrary to common belief, extensive sequence homology (molecular mimicry) between self and microbe does not necessarily result in cross-reactivity. It is therefore likely that, when present, cross-reactivity between self and microbes is of biological importance.

Helicobacter pylori: current status and future prospects

Helicobacter pylori is a global pathogen that causes severe gastrointestinal diseases leading to a significant morbidity and mortality. There is an effective treatment for peptic ulcer disease, however, this is being compromised by an increase in the prevalence of antibiotic resistance. Although alternative rescue regimens have been advocated, the best strategy would be to prevent disease, especially in the case of gastric cancer for which there is still no treatment. One approach is to inhibit the first step in the pathogenic process - adhesion of the organism to the host tissue. Another and probably a better approach is vaccination, but clinical trials have so far been unsuccessful. There is still a large uncertainty in relation to how H. pylori causes disease. Knowledge from genomics, proteomics, and the relationship between polymorphism of the bacterium and the host, as well as the continuing investigation of the role played by important virulence factors in the outcome of the disease, will help both in understanding pathogenesis of disease and in the design of the best vaccine.