Helicobacter pylori (H. pylori) is the main cause of chronic gastritis and a major risk factor for gastric cancer. This pathogen has also been considered a potential trigger of gastric autoimmunity, and in particular of autoimmune gastritis. However, a considerable number of reports have attempted to link H. pylori infection with the development of extra-gastrointestinal autoimmune disorders, affecting organs not immediately relevant to the stomach. This review discusses the current evidence in support or against the role of H. pylori as a potential trigger of autoimmune rheumatic and skin diseases, as well as organ specific autoimmune diseases. We discuss epidemiological, serological, immunological and experimental evidence associating this pathogen with autoimmune diseases. Although over one hundred autoimmune diseases have been investigated in relation to H. pylori, we discuss a select number of papers with a larger literature base, and include Sjögrens syndrome, rheumatoid arthritis, systemic lupus erythematosus, vasculitides, autoimmune skin conditions, idiopathic thrombocytopenic purpura, autoimmune thyroid disease, multiple sclerosis, neuromyelitis optica and autoimmune liver diseases. Specific mention is given to those studies reporting an association of anti-H. pylori antibodies with the presence of autoimmune disease-specific clinical parameters, as well as those failing to find such associations. We also provide helpful hints for future research.
Autoimmunity; Helicobacter pylori; Infection; Gastritis; Mimicry; Rheumatology
Background and Aim. Neonatal hemochromatosis (NH) is characterised by severe liver injury and extrahepatic siderosis sparing the reticuloendothelial system. Its aetiology is obscure, although it has been proposed as an alloimmune disease, resulting from immunological reaction to self-antigens (alloantigens) which the body recognizes as foreign. We studied an infant with NH and his mother whose sera contained antimitochondrial antibody (AMA), the hallmark of primary biliary cirrhosis (PBC). Material and Methods. To investigate the origin of AMA in the infant, we studied isotype distributions in serum from the mother and infant. Serum samples were obtained at diagnosis of NH, after liver transplantation (LT; age 1 month), and over the ensuing 17 months. Results. At NH diagnosis, infant and maternal serum contained AMA of the IgG isotype, predominantly of the G3 and G1 subclasses. AMA strongly reacted against the pyruvate dehydrogenase complex E2 subunit (PDC-E2), the major PBC-specific AMA autoantigen. Anti-PDC-E2 responses in both infant and mother declined over time, being present 2 months after LT (mother and child) and absent 10 months later (mother) and 17 months later (child). Conclusion. The association of maternally transferred IgG1 and IgG3 subclass AMA with the appearance of liver damage in an infant with NH may suggest a causal link between antibody and liver damage.
p38 mitogen activated protein kinase (p38 MAPK) signaling plays a major role in the modulation of immune-mediated inflammatory responses and therefore has been linked with several autoimmune diseases. The extent of the involvement of p38 MAPK in the pathogenesis of autoimmune blistering diseases has started to emerge, but whether it pays a critical role is a matter of debate. The activity of p38 MAPK has been studied in great detail during the loss of keratinocyte cell-cell adhesions and the development of pemphigus vulgaris (PV) and pemphigus foliaceus (PF). These diseases are characterised by autoantibodies targeting desmogleins (Dsg). Whether autoantibody-antigen interactions can trigger signaling pathways (such as p38 MAPK) that are tightly linked to the secretion of inflammatory mediators which may perpetuate inflammation and tissue damage in pemphigus remains unclear. Yet, the ability of p38 MAPK inhibitors to block activation of the proapoptotic proteinase caspase-3 suggests that the induction of apoptosis may be a consequence of p38 MAPK activation during acantholysis in PV. This review discusses the current evidence for the role of p38 MAPK in the pathogenesis of pemphigus. We will also present data relating to the targeting of these cascades as a means of therapeutic intervention.
Background. Previous studies reported associations between specific alleles of non-HLA immunoregulatory genes and higher fatigue scores in patients with primary biliary cirrhosis (PBC). Aim. To study the relationship between variables of health-related quality of life (HRQoL) and single nucleotide polymorphisms of TRAF1-C5, a member of the tumor necrosis factor receptor family. Patients and Methods. TRAF1-C5 gene polymorphisms, rs2900180 and rs3761847, were analysed in 120 Caucasian PBCs. The HRQoL was assessed with SF-36, PBC-40, and PBC-27 questionnaires. Results. We found a negative association between TT genotype of rs2900180 and SF-36's domains vitality (P < 0.05), mental health (P < 0.05), and mental component summary score (P < 0.05). GG homozygotes of rs3761847 had lower vitality (P < 0.05), mental health (P < 0.05), mental component summary score (P < 0.05) and impairment of social functioning (P < 0.01). Allelic analysis has shown that T allele of rs2900180 and G allele of rs3761847 related to SF-36's vitality (P < 0.05 and P < 0.01), social functioning (P < 0.05 and P < 0.05), mental health (P < 0.01 and P < 0.05), and mental component summary score (P < 0.01 and P < 0.05), respectively. Genotyping and allelic analysis did not reveal correlation with PBC-40 and PBC-27 domains. Conclusion. The association between rs2900180 and rs3761847 polymorphisms and HRQoL variables indicates that TRAF1 is involved in the induction of impaired QoL in PBC.
Primary biliary cirrhosis (PBC) is a progressive cholestatic liver disease characterised serologically by cholestasis and the presence of high-titre antimitochondrial antibodies, and histologically by chronic nonsuppurative cholangitis and granulomata. As PBC is a granulomatous disease and Mycobacterium tuberculosis is the most frequent cause of granulomata, a causal relation between tuberculosis and PBC has been suggested. Attempts to find serological evidence of PBC-specific autoantibodies such as AMA have been made and, conversely, granulomatous livers from patients with PBC have been investigated for molecular evidence of Mycobacterium tuberculosis. This paper discusses in detail the reported data in support or against an association between Mycobacterium tuberculosis infection and PBC. We discuss the immunological and microbiological data exploring the association of PBC with exposure to Mycobacterium tuberculosis. We also discuss the findings of large epidemiologic studies investigating the association of PBC with preexistent or concomitant disorders and the relevance of these findings with tuberculosis. Genome-wide association studies in patients with tuberculosis as well as in patients with PBC provide conclusive hints regarding the assumed association between exposure to this mycobacterium and the induction of PBC. Analysis of these data suggest that Mycobacterium tuberculosis is an unlikely infectious trigger of PBC.
Primary biliary cirrhosis (PBC) is a progressive cholestatic liver disease characterized serologically by cholestasis and the presence of high-titre antimitochondrial antibodies and histologically by chronic nonsuppurative cholangitis and granulomata. PBC patients often have concomitant autoimmune diseases, including arthropathies. This raises the question as to whether there are shared features in the pathogenesis of those diseases with the pathogenesis of PBC. Epidemiological and large case studies have indicated that although the incidence of rheumatoid arthritis (RA) is not significantly raised in PBC patients, there appears to be a higher rate of RA in PBC patients and their relatives. Genetic studies have demonstrated that several genes implicated in PBC have also been implicated in RA. Epigenetic studies provided a wealth of data regarding RA, but the findings on epigenetic changes in PBC are very limited. As well, certain infectious agents identified in the pathogenesis of PBC may also play a role in the pathogenesis of RA. These data suggest that although RA is not significantly present in PBC, some individuals with certain genetic traits and environmental exposures may develop both conditions. This concept may also apply to other concomitant diseases found in PBC patients.
Why zymogen glycoprotein 2 (GP2), the Crohn's disease (CD)-specific pancreatic autoantigen, is the major target of humoral autoimmunity in inflammatory bowel diseases (IBD) is uknown. Recent evidence demonstrates that GP2 is also present on the apical surface of microfold (M) intestinal cells. As the colon lacks GP2-rich M cells, we assumed that patients with colonic CD are seronegative for anti-GP2. Anti-GP2 antibodies were tested in 225 CDs, including 45 patients with colonic location (L2), 45 with terminal ileum (L1) and 135 with ileocolonic involvement; 225 patients with ulcerative colitis (UC) were also tested. Anti-GP2 reactivity was detected in 59 (26.2%) CDs and 15 (6.7%) UCs (P < 0.001). Only 5 CDs with L2 had anti-GP2 antibodies, compared to 54/180 (30.0%, P = 0.0128) of the CDs with L1 and L3. Anti-GP2 antibody positive CD patients had higher ASCA titres compared to seronegative cases. Amongst the 128 CD patients with previous surgical intervention, 45 (35.0%) were anti-GP2 antibody positive compared to 14/97 (14.0%) without surgical (P < 0.001). Our data support the assumption that ileal inflammation is required for the development of anti-GP2 antibodies in CD, and suggest that the intestine rather than the pancreatic juice is the antigenic source required for the initiation of anti-GP2 antibodies.
Primary biliary cirrhosis (PBC) is a progressive cholestatic liver disease characterized by the immune-mediated destruction of biliary epithelial cells in small intrahepatic bile ducts. The disease is characterized by circulating antimitochondrial antibodies (AMAs) as well as disease-specific antinuclear antibodies, cholestatic liver function tests, and characteristic histological features, including granulomas. A variety of organisms are involved in granuloma formation, of which mycobacteria are the most commonly associated. This has led to the hypothesis that mycobacteria may be involved in the pathogenesis of PBC, along with other infectious agents. Additionally, AMAs are found in a subgroup of patients with mycobacterial infections, such as leprosy and pulmonary tuberculosis. Antibodies against species-specific mycobacterial proteins have been reported in patients with PBC, but it is not clear whether these antibodies are specific for the disease. In addition, data in support of the involvement of the role of molecular mimicry between mycobacterial and human mitochondrial antigens as triggers of cross-reactive immune responses leading to the loss of immunological tolerance, and the induction of pathological features have been published. Thus, antibodies against mycobacterial heat shock protein appear to cross-recognize AMA-specific autoantigens, but it is not clear whether these autoantibodies are mycobacterium-species-specific, and whether they are pathogenic or incidental. The view that mycobacteria are infectious triggers of PBC is intriguing, but the data provided so far are not conclusive.
Antimitochondrial antibodies; Autoantibody; Autoimmunity; Cholestasis; Heat shock; Infection; Liver disease; Liver failure; Mycobacterium; Tuberculosis
Unlike other autoimmune liver diseases, primary biliary cirrhosis (PBC) has never been reported in early childhood, while type 2 autoimmune hepatitis (AIH) is eminently a paediatric disease.
We describe a case of type 2 AIH with serological positivity for PBC-specific anti-mitochondrial antibodies (AMA) in a 3-year old girl. We found this observation intriguing as AMA and indeed an overlap with PBC are virtually absent in Type 2 AIH, a pediatric form of AIH which is distinct precisely because it is characterized by pathognomonic anti-liver kidney microsomal type 1 (LKM-1) showing a remarkable antigen-specificity directed against cytochrome P4502D6. We also review the literature in relation to AMA positivity in paediatric age and adolescence. In our case, the presence of AIH-2-specific anti-LKM-1 and PBC-specific AMA was confirmed by indirect immunofluorescence (IIF), and immunoblotting and ELISA based on recombinant mitochondrial antigens. The clinical, laboratory and histological features of the child are given in detail. Interestingly the mother was AMA positive without other features of PBC. The child was successfully treated with immunosuppression and five years after the original diagnosis is on a low dose of prednisolone and azathioprine, with no signs of relapse. Anti-LKM-1 antibodies are still present in low titres. AMA were detectable for the first 4 years after the diagnosis and disappeared later.
This is the first case report in the literature of AIH type 2 with an unexpected PBC-specific AMA positivity in a young child. Response to immunosuppressive treatment was satisfactory and similar to that described in AIH. A review of published reports on AMA positivity in paediatric age shows that the antibody may arise in the context of immunodeficiency and is variably associated with liver damage.
Autoantibody; Autoimmunity; Autoimmune cholangitis; Epidemiology; Environment; Paediatric liver diseases.
Primary biliary cirrhosis (PBC) is a cholestatic liver disease of autoimmune origin, characterised by the destruction of small intrahepatic bile ducts. The disease has an unpredictable clinical course but may progress to fibrosis and cirrhosis. The diagnostic hallmark of PBC is the presence of disease-specific antimitochondrial antibodies (AMA), which are pathognomonic for the development of PBC. The disease overwhelmingly affects females, with some cases of male PBC being reported. The reasons underlying the low incidence of males with PBC are largely unknown. Epidemiological studies estimate that approximately 7–11% of PBC patients are males. There does not appear to be any histological, serological, or biochemical differences between male and female PBC, although the symptomatology may differ, with males being at higher risk of life-threatening complications such as gastrointestinal bleeding and hepatoma. Studies on X chromosome and sex hormones are of interest when studying the low preponderance of PBC in males; however, these studies are far from conclusive. This paper will critically analyze the literature surrounding PBC in males.
The pathogenesis of autoimmune diseases includes a combination of genetic factors and environmental exposures including infectious agents. Infectious triggers are commonly indicated as being involved in the induction of autoimmune disease, with Epstein-Barr virus (EBV) being implicated in several autoimmune disorders. EBV is appealing in the pathogenesis of autoimmune disease, due to its high prevalence worldwide, its persistency throughout life in the host's B lymphocytes, and its ability to alter the host's immune response and to inhibit apoptosis. However, the evidence in support of EBV in the pathogenesis varies among diseases. Autoimmune liver diseases (AiLDs), including autoimmune hepatitis (AIH), primary biliary cirrhosis (PBC), and primary sclerosing cholangitis (PSC), have a potential causative link with EBV. The data surrounding EBV and AiLD are scarce. The lack of evidence surrounding EBV in AiLD may also be reflective of the rarity of these conditions. EBV infection has also been linked to other autoimmune conditions, which are often found to be concomitant with AiLD. This paper will critically examine the literature surrounding the link between EBV infection and AiLD development. The current evidence is far from being conclusive of the theory of a link between EBV and AiLD.
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.
Primary biliary cirrhosis (PBC) is a cholestatic liver disease characterised by the autoimmune destruction of the small intrahepatic bile ducts. The disease has an unpredictable clinical course, but may progress to fibrosis and cirrhosis. Although medical treatment with urseodeoxycholic acid is largely successful, some patients may progress to liver failure requiring liver transplantation. PBC is characterised by the presence of disease specific anti-mitochondrial (AMA) antibodies, which are pathognomonic for PBC development. The disease demonstrates an overwhelming female preponderance and virtually all women with PBC present in middle age. The reasons for this are unknown; however several environmental and immunological factors may be involved. As the immune systems ages, it become less self tolerant, and mounts a weaker response to pathogens, possibly leading to cross reactivity or molecular mimicry. Some individuals display immunological changes which encourage the development of autoimmune disease. Risk factors implicated in PBC include recurrent urinary tract infection in females, as well as an increased prevalence of reproductive complications. These risk factors may work in concert with and possibly even accelerate, immune system ageing, contributing to PBC development. This review will examine the changes that occur in the immune system with ageing, paying particular attention to those changes which contribute to the development of autoimmune disease with increasing age. The review also discusses risk factors which may account for the increased female predominance of PBC, such as recurrent UTI and oestrogens.
ageing; apoptosis; autoantibody; autoimmunity; infection
Primary biliary cirrhosis (PBC) is a chronic immune-mediated cholestatic liver disease of unknown aetiology which affects mostly women in middle age. Familial PBC is when PBC affects more than one member of the same family, and data suggest that first-degree relatives of PBC patients have an increased risk of developing the disease. Most often, these familial clusters involve mother-daughter pairs, which is consistent with the female preponderance of the disease. These clusters provide evidence towards a genetic basis underlying PBC. However, clusters of nonrelated individuals have also been reported, giving strength to an environmental component. Twin studies have demonstrated a high concordance for PBC in monozygotic twins and a low concordance among dizygotic twins. In conclusion, studies of PBC in families clearly demonstrate that genetic, epigenetic, and environmental factors play a role in the development of the disease.
Various environmental factors have been proposed as triggers of primary biliary cirrhosis (PBC), a progressive autoimmune cholestatic liver disease which is characterised by the destruction of the small intrahepatic bile ducts. Support for their pathogenic role in PBC is provided by epidemiological studies reporting familial clustering and clusters of the disease within a given geographical area. The seminal study by Triger reporting that the great majority of PBC cases in the English city of Sheffield drank water from a specific water reservoir, has been followed by studies reporting disease 'hot spots' within a restricted geographic region of the former coal mining area of Newcastle. The New York study reporting an increased risk and significant clustering of PBC cases near toxic federal waste disposal sites has added strength to the notion that environmental factors, possibly in the form of infectious agents or toxic/chemical environmental factors in areas of contaminated land, water or polluted air may play a key role in the development of the disease. This review discusses the findings of reports investigating environmental factors which may contribute to the cause of primary biliary cirrhosis.
Autoimmunity; disease; bile ducts; cholestasis; liver; immunity; tolerance; mimicry; cross-reactivity; environment