High mobility group (HMG) non-histone chromosomal proteins HMG1 and HMG2 are significant target antigens of perinuclear anti-neutrophil cytoplasmic antibodies in autoimmune hepatitis

Antineutrophil cytoplasmic antibodies (ANCA)-positive patient with infective endocarditis and chronic hepatitis B virus: a case report and review of the literature

Background

Antineutrophil cytoplasmic antibodies comprise a family of autoantibodies that are often used as biomarkers for certain forms of small-vessel vasculitis; however, chronic infections tend to induce the production of antineutrophil cytoplasmic antibodies. Infective endocarditis and hepatitis B virus infection have been reported to exhibit antineutrophil cytoplasmic antibody positivity and to mimic antineutrophil cytoplasmic antibody–associated vasculitis, which may lead to misdiagnosis and inappropriate treatment.

Case presentation

We report a case of a 46-year-old Han Chinese man with untreated chronic hepatitis B virus infection who featured proteinase-3 antineutrophil cytoplasmic antibody positivity while hospitalized with infective endocarditis. Cardiac ultrasound echocardiography disclosed mitral and aortic regurgitation with vegetation. On the 15th hospital day, the patient underwent mitral and aortic valve replacement and was then treated with antibiotics for more than 1 month. On the 57th hospital day, the patient was discharged. His urinary abnormalities and renal function were gradually recovering. Four months after being discharged, his proteinase-3 antineutrophil cytoplasmic antibody levels had returned to the normal range.

Conclusions

The findings in this study update and expand current understanding of antineutrophil cytoplasmic antibody positivity in patients with both infective endocarditis and hepatitis B virus. Treatment (including surgery, antibiotics, corticosteroids and/or cyclophosphamide, antiviral agents, and even plasma exchange) is challenging when several diseases are combined. Renal biopsy is suggested if the patient’s condition allows. Antineutrophil cytoplasmic antibody testing should be repeated after therapy, because some cases might require more aggressive treatment.

[Viewing sepsis and autoimmune disease in relation with infection and NETs-formation]

Neutrophil has been widely recognized as body's first line of defence against pathogens. NETosis was first reported in 2004 as a programmed cell death of neutrophil and distinguished from apoptosis and necrosis. This phenomenon has been already observed in both basic and clinical research. NETosis is induced by various stimulants such as PMA, IL-8, DAMPs/PAMPs, bacteria, and antigen-antibody complex including self-antibody such as ANCA. It is known that there are two types of NETosis following bacterial infections. Although both of them have the ability to capture and kill bacteria, they also damage the host tissues. The inhibition of the NETs-related enzymes prevents the NETs formation at that time. The production of O₂^- from respiratory burst of neutrophils triggers NETs formation. In the first type of NETosis, neutrophils are completely collapsed, while in the second type, they maintain the morphology and the ability of phagocytosis. However, bacteria can escape from NETs by degrading NETs with their secreting nucleases. Thus the animal models of infection, using these bacteria, oftentimes suffer from severe infectious diseases. Human CGD (Chronic Granulomatosis Disease) patients who do not have Nox2 are immunocompromised, and highly susceptible to infection due to the defect of NETs formation. On the other hand, SLE patients are unable to break down the NETs as their serum inhibits the DNase1 activity, which results in autoantibody generation against NETs as well as self-DNA. It is getting clear that there is a relationship between inflammatory diseases, including infectious diseases, Sepsis and autoimmune diseases, and NETs. Therefore, it is important to re-evaluate the inflammatory disorders from NETs' perspective, and to incorporate the emerging concepts for better understanding the mechanisms involved.

Diagnosis and Management of Autoimmune Hepatitis: Current Status and Future Directions

Autoimmune hepatitis is characterized by autoantibodies, hypergammaglobulinemia, and interface hepatitis on histological examination. The features lack diagnostic specificity, and other diseases that may resemble autoimmune hepatitis must be excluded. The clinical presentation may be acute, acute severe (fulminant), or asymptomatic; conventional autoantibodies may be absent; centrilobular necrosis and bile duct changes may be present; and the disease may occur after liver transplantation or with features that suggest overlapping disorders. The diagnostic criteria have been codified, and diagnostic scoring systems can support clinical judgment. Nonstandard autoantibodies, including antibodies to actin, α-actinin, soluble liver antigen, perinuclear antineutrophil antigen, asialoglycoprotein receptor, and liver cytosol type 1, are tools that can support the diagnosis, especially in patients with atypical features. Prednisone or prednisolone in combination with azathioprine is the preferred treatment, and strategies using these medications in various doses can ameliorate treatment failure, incomplete response, drug intolerance, and relapse after drug withdrawal. Budesonide, mycophenolate mofetil, and calcineurin inhibitors can be considered in selected patients as frontline or salvage therapies. Molecular (recombinant proteins and monoclonal antibodies), cellular (adoptive transfer and antigenic manipulation), and pharmacological (antioxidants, antifibrotics, and antiapoptotic agents) interventions constitute future directions in management. The evolving knowledge of the pathogenic pathways and the advances in technology promise new management algorithms.

PR3-ANCA: a promising biomarker in primary sclerosing cholangitis (PSC)

Background and Aims

The only recognized biomarker for primary sclerosing cholangitis (PSC) is atypical anti-neutrophil cytoplasmic antibodies (aANCA), which, in addition to having low sensitivity and specificity, is an indirect immunofluorescence (IIF) test lacking the advantages of high throughput and objectivity. Recent reports have shown that antibodies to proteinase-3 (PR3-ANCA) might add diagnostic value in inflammatory bowel disease (IBD), specifically in ulcerative colitis (UC). As PSC is associated with IBD, the objective of this study was to evaluate the frequency and clinical significance of PR3-ANCA in a large cohort of patients.

Methods

A total of 244 PSC and 254 control [autoimmune hepatitis (AIH), primary biliary cirrhosis (PBC), hepatitis C viral infection (HCV), hepatitis B viral infection (HBV), and healthy controls] sera and their clinical correlations were retrospectively analyzed for PR3-ANCA determined by ELISA and a new chemiluminescence immunoassay (CIA). Testing was also performed for aANCA by IIF.

Results

When measured by CIA, PR3-ANCA was detected in 38.5% (94/244) of PSC patients compared to 10.6% (27/254) controls (p<0.0001). By ELISA, PR3-ANCA was detected in 23.4% (57/244) of PSC patients compared to 2.7% (6/254) controls (p<0.0001). PR3-ANCA in PSC patients was not associated with the presence or type of underlying IBD, and, in fact, it was more frequent in Crohn's disease (CD) patients with PSC than previously reported in CD alone. PR3-ANCA in PSC measured by CIA correlated with higher liver enzymes.

Conclusion

PR3-ANCA is detected in a significant proportion of PSC patients compared to other liver diseases including PBC and AIH. PR3-ANCA is associated with higher liver enzyme levels in PSC, and is not solely related to underlying IBD.

Coherent somatic mutation in autoimmune disease

BACKGROUND

Many aspects of autoimmune disease are not well understood, including the specificities of autoimmune targets, and patterns of co-morbidity and cross-heritability across diseases. Prior work has provided evidence that somatic mutation caused by gene conversion and deletion at segmentally duplicated loci is relevant to several diseases. Simple tandem repeat (STR) sequence is highly mutable, both somatically and in the germ-line, and somatic STR mutations are observed under inflammation.

RESULTS

Protein-coding genes spanning STRs having markers of mutability, including germ-line variability, high total length, repeat count and/or repeat similarity, are evaluated in the context of autoimmunity. For the initiation of autoimmune disease, antigens whose autoantibodies are the first observed in a disease, termed primary autoantigens, are informative. Three primary autoantigens, thyroid peroxidase (TPO), phogrin (PTPRN2) and filaggrin (FLG), include STRs that are among the eleven longest STRs spanned by protein-coding genes. This association of primary autoantigens with long STR sequence is highly significant (p<3.0x10(-7)). Long STRs occur within twenty genes that are associated with sixteen common autoimmune diseases and atherosclerosis. The repeat within the TTC34 gene is an outlier in terms of length and a link with systemic lupus erythematosus is proposed.

CONCLUSIONS

The results support the hypothesis that many autoimmune diseases are triggered by immune responses to proteins whose DNA sequence mutates somatically in a coherent, consistent fashion. Other autoimmune diseases may be caused by coherent somatic mutations in immune cells. The coherent somatic mutation hypothesis has the potential to be a comprehensive explanation for the initiation of many autoimmune diseases.

Autoantibodies in liver disease: important clues for the diagnosis, disease activity and prognosis

It has been well established that numerous kinds of autoantibodies have been detected in liver disease. Some kinds of autoantibodies may be helpful in the diagnosis of autoimmune liver diseases including autoimmune hepatitis, primary biliary cirrhosis or primary sclerosing cholangitis. However, these autoantibodies are present even in sera of patients with viral hepatitis, drug-induced hepatitis, alcoholic liver disease, non-alcoholic fatty liver disease and hepatocelluar carcinoma as well as in sera of patients with autoimmune liver diseases. Other kinds of autoantibodies are recognized as predictive hallmarks for disease activity or prognosis in liver diseases. On the other hand, treatment with interferon initiates the production of several types of autoantibodies in patients with chronic hepatitis C virus infection. Some of autoantibodies induced by interferon may postulate the treatment outcome in those patients. Recent studies also revealed the close correlation between oxidative stress and the production of autoantibodies in liver diseases. This article primarily reviews the recent advances of autoantibodies in the liver diseases and discusses the clinical significance of these autoantibodies.

Anti-high mobility group box 1 and box 2 non-histone chromosomal proteins (HMGB1/HMGB2) antibodies and anti-Saccharomyces cerevisiae antibodies (ASCA): accuracy in differentially diagnosing UC and CD and correlation with inflammatory bowel disease phenotype

BACKGROUND

The development of a supportive diagnostic method has long been required to differentially diagnose ulcerative colitis (UC) and Crohn's disease (CD). Several antibodies circulate in the sera of patients with inflammatory bowel disease. We previously identified the high mobility group box 1 and box 2 non-histone chromosomal proteins (HMGB1 and HMGB2) as novel antigens of perinuclear type anti-neutrophil cytoplasmic antibodies (pANCA) and discovered anti-HMGB1/HMGB2 antibodies in sera from patients with UC. Here, we evaluated the ability of anti-HMGB1/HMGB2 antibodies combined with anti-Saccharomyces cerevisiae antibodies (ASCA) to differentially diagnose UC and CD.

METHODS

We measured titers of anti-HMGB1/HMGB2 antibodies and ASCA in the sera of 213 patients with UC and 93 with CD, using enzyme-linked immunosorbent assays.

RESULTS

Among the patients with UC, 26.8% were positive for anti-HMGB1/HMGB2 antibodies, with 85.0% specificity towards CD and a positive predictive value of 80.3%. Corticosteroids significantly suppressed the titer of anti-HMGB1/HMGB2 antibodies. Among the patients with CD, 24.7% were positive for ASCA, with 96.2% specificity towards UC and a positive predictive value of 74.2%. Interestingly, the positivity rate of anti-HMGB/HMGB2 antibodies was higher (35.7%) in patients with the ileitis type of CD than in patients with CD in the colon (6.2%; significant difference, P < 0.01). The specificity of anti-HMGB1/HMGB2 antibodies in UC for CD in the colon was 93.8%.

CONCLUSIONS

CD in the colon and UC can be differentially diagnosed using anti-HMGB/HMGB2 antibodies combined with ASCA.

Uveitis Seroreactivity to Candidate pANCA Antigens: Mycobacterial HupB and Histone H1(69-171)

PURPOSE

Certain uveitis patients express the disease-marker antibody pANCA. Histone H1 (H1) and mycobacterial HupB (HupB) are recently identified candidate pANCA antigens. This study addresses the hypothesis that H1 and HupB are targets of disease-associated seroreactivity in pANCA+ uveitis.

METHODS

Sera from 293 uveitis patients were categorized for pANCA activity. H1(69-171) and HupB recombinant proteins were used as antigenic targets in ELISA studies. Selected sera were analyzed for reactivity by Western blot.

RESULTS

Seroreactivities to ANCA, H1(69-171), and HupB were frequently detected in uveitis patients. No significant relationship existed between the level of ANCA antibody and reactivity to either recombinant antigen. There was, however, a significant, positive correlation between H1(69-171) and HupB seroreactivities.

CONCLUSIONS

Correlation between H1(69-171) and HupB reactivities suggests the presence of a shared dominant epitope, which is recognized by antibodies in a substantial number of uveitis patients. Seroreactivities to ANCA and HupB/H1 are independent immunologic markers that may identify biologically distinctive subsets of uveitis.

Multidimensional degradomics identifies systemic autoantigens and intracellular matrix proteins as novel gelatinase B/MMP-9 substrates

The action radius of matrix metalloproteinases or MMPs is not restricted to massive extracellular matrix (ECM) degradation, it extends to the proteolysis of numerous secreted and membrane-bound proteins. Although many instances exist in which cells disintegrate, often in conjunction with induction of MMPs, the intracellular MMP substrate repertoire or degradome remains relatively unexplored. We started an unbiased exploration of the proteolytic modification of intracellular proteins by MMPs, using gelatinase B/MMP-9 as a model enzyme. To this end, multidimensional degradomics technology was developed by the integration of broadly available biotechniques. In this way, 100-200 MMP-9 candidate substrates were isolated, of which 69 were identified. Integration of these results with the known biological functions of the substrates revealed many novel MMP-9 substrates from the intracellular matrix (ICM), such as actin, tubulin, gelsolin, moesin, ezrin, Arp2/3 complex subunits, filamin B and stathmin. About 2/3 of the identified candidates were autoantigens described in multiple autoimmune conditions and in cancer (e.g. annexin I, nucleolin, citrate synthase, HMGB1, alpha-enolase, histidyl-tRNA synthetase, HSP27, HSC70, HSP90, snRNP D3). These findings led to the insight that MMPs and other proteases may have novel (immuno)regulatory properties by the clearance of toxic and immunogenic burdens of abundant ICM proteins released after extensive necrosis. In line with the extracellular processing of organ-specific autoantigens, proteolysis might also assist in the generation of immunodominant 'neo-epitopes' from systemic autoantigens. The study of proteolysis of ICM molecules, autoantigens, alarmins and other crucial intracellular molecules may result in the discovery of novel roles for proteolytic modification.

Multiparameter analysis of immunogenetic mechanisms in clinical diagnosis and management of inflammatory bowel disease

The integrity of the intestinal mucosa depends on a functional coordination of the epithelium, lumenal microorganisms, and the local immune system. The mammalian immune system is superbly organized for innate and adaptive recognition of microbial antigens, a defensive capacity that must be balanced against the tissue damage produced by immune activity to preserve normal intestinal function. Inflammatory bowel disease (IBD) is generally thought to reflect an impairment in this balance, due to a combination of host genetic traits that shift the balance of immune and epithelial function to commensal microbiota, and perhaps the composition or activity of certain microbial elements as well. There has been much progress defining the fundamental disorders of these host traits, immunologic processes, and microbial targets in inflammatory bowel disease. Other fields of clinical and geologic microbiology are teaching us about the dynamic interaction of commensal bacteria with their host environment. These lines of investigation have revealed not only important insights about inflammatory bowel disease (IBD) pathogenesis, but also defined technologies and tools useful for its diagnosis and clinical management. This review focuses on these advances at the translational interface. We will first consider the innate anti-microbial response, centering on the utility of NOD2 genotyping for predicting disease susceptibility, prognosis, and therapeutic response profile. We will then turn to the adaptive anti-microbial response, focusing on the application of antibodies to fungal and bacterial species and products for Crohn's disease (CD) diagnosis and prognosis, and immunogenetics of T cell immunosuppression management. Finally, we will describe autoimmune mechanisms in IBD, with particular attention to autoantibodies in IBD diagnosis and infliximab responsiveness. We will conclude with the concept of multiparameter analysis of patients, to refine patient characterization and stratification in diagnosis and clinical management.

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.

Lupus antibodies to the HMGB1 chromosomal protein: epitope mapping and association with disease activity

The high mobility group box 1 (HMGB1) protein is a non-histone chromosomal protein that acts as a potent proinflammatory cytokine when actively secreted from LPS- or TNF-activated macrophages, monocytes, and other cells. Anti-HMGB1/2 antibodies have been previously identified in sera from a high proportion of patients with autoimmune diseases. In this study, we examined anti-HMGB1 antibody titers in sera of patients with systemic rheumatic diseases and the correlations between the presence of anti-HMGB1 antibodies and disease activity in systemic lupus erythematosus (SLE) patients by enzyme-linked immunosorbent assay and western blotting. We detected increases in both the levels and the frequency of anti-HMGB1 antibodies in sera from SLE and polymyositis/dermatomyositis (PM/DM) patients, and observed that the presence of anti-HMGB1 antibodies positively correlates with SLE disease activity index. Through epitope mapping, we found that multiple HMGB1 epitopes were recognised in SLE sera, with the major epitope mapping to box A. Another epitope, the joiner region of HMGB1, was preferentially recognized by SLE sera, but not by PM/DM sera. Collectively, these observations suggest that the presence of anti-HMGB1 antibodies correlates with disease activity in SLE patients.

Abnormal mucosal immune response to altered bacterial flora following restorative proctocolectomy in patients with ulcerative colitis: serologic measures, immunogenetics, and clinical correlations

A patient from the University of North Carolina Hospitals is presented who developed Crohn's disease of the ileal J-pouch following restorative proctocolectomy for ulcerative colitis. Inflammation of the ileal pouch in human inflammatory bowel disease (IBD) represents the best clinical example of the importance of host-enteric microbial interactions, and this case highlights rapid advances in our understanding of the role of the enteric microbiota in the immunopathogenesis of IBD, impacting on clinical care. Successful management of this patient necessitated accurate diagnosis as there are several inflammatory and non-inflammatory conditions of the pouch that present with similar symptoms. Diagnostic measures included serologic assays of response to microbial antigens, including ASCA, anti-OmpC, anti-Cbir1, and pANCA with DNAse sensitivity. Although the serologic detection of selective loss of tolerance to microbial antigens defines clinically important subgroups of inflammatory bowel disease patients, the clinical value of these serodiagnostic tests is a matter of debate. Genome wide screens have also identified NOD2/CARD15, IL23 receptor, and ATG16L1 variants as important in IBD susceptibility and pathogenesis. These genetic associations have also provided new insights into the importance of interaction between the host and microbes in the pathogenesis of IBD, but the precise mechanisms by which these gene variants contribute to disease development remain to be determined. Genetic associations and serological markers will ultimately be used to define important clinical subgroups of disease, predict natural history, and ultimately identify patient populations for early therapeutic intervention.

Autoantibodies in primary sclerosing cholangitis

The aetiology of primary sclerosing cholangitis (PSC) is not known and controversy exists as to whether PSC should be denominated an autoimmune disease. A large number of autoantibodies have been detected in PSC patients, but the specificity of these antibodies is generally low, and the frequencies vary largely between different studies. The presence of autoantibodies in PSC may be the result of a nonspecific dysregulation of the immune system, but the literature in PSC points to the possible presence of specific antibody targets in the biliary epithelium and in neutrophil granulocytes. The present review aims to give an overview of the studies of autoantibodies in PSC, with a particular emphasis on the prevalence, clinical relevance and possible pathogenetic importance of each individual marker.

Primary biliary cirrhosis and autoantibodies

Fifty years have passed since anti-mitochondrial antibodies were found in patients with primary biliary cirrhosis (PBC). PBC is an autoimmune hepatic disease in which 85-90% of patient antibodies bind to mitochondrial antigens that include pyruvate dehydrogenase complex (PDC)-E2 and other members of the oxaloacid dehydrogenase family. In addition, indirect immunofluorescence (IIF) assays utilizing HEp-2 cell substrates have been used to identify anti-centromere antibodies in 20-30% of PBC sera. These antibodies are generally easily recognized, however, anti-nuclear envelope and anti-multiple nuclear dot antibodies are occasionally more difficult to recognize with certainty by IIF. The use of enzyme linked immunosorbent assays that utilize recombinant gp210 (an autoantigen of the nuclear envelope) and/or sp100 (a protein target represented by multiple nuclear dots) should be particularly considered in anti-mitochondrial antibody negative PBC sera. Although the clinical significance of these antibodies still remains to be determined, there is evidence that the existence of anti-gp210 antibodies are related to poorer prognosis and more aggressive disease progression.

High mobility group box chromosomal protein 1 in patients with renal diseases

BACKGROUND/AIM

The high mobility group box chromosomal protein 1 (HMGB1), a nuclear DNA-binding protein, has recently been recognized as a new proinflammatory cytokine. The purpose of this study was to examine the significance of HMGB1 in patients with renal diseases.

METHODS

HMGB1 concentrations in sera were measured by enzyme-linked immunosorbent assay, and antibodies against HMGB1 were examined by Western blotting in patients who underwent renal biopsies and in healthy controls. Immunohistochemistry for HMGB1 was also performed.

RESULTS

Serum HMGB1 was more likely to be positive in patients who underwent renal biopsies as compared with the controls. Patients with anti-neutrophil cytoplasmic antibody-related glomerulonephritis (ANCA-GN) and those with Henoch-Schonlein purpura nephritis showed a significantly higher tendency to be HMGB1 positive. The presence of anti-HMGB1 antibody was not associated with the presence of serum HMGB1. Immunohistochemistry revealed that HMGB1 was expressed in mononuclear cells in the interstitium or in the glomeruli of some patients with ANCA-GN or IgA nephropathy (IgAN). Subanalysis demonstrated that among patients with IgAN, those who had crescent formation showed a higher tendency to be HMGB1 positive than those who did not.

CONCLUSIONS

HMGB1 was expressed in the sera of patients with renal diseases who underwent renal biopsies, especially among those who had vasculitis including ANCA-GN, Henoch-Schonlein purpura nephritis, and IgAN with glomerular crescents.

Post-translational methylation of high mobility group box 1 (HMGB1) causes its cytoplasmic localization in neutrophils

High mobility group box 1 (HMGB1) protein plays multiple roles in transcription, replication, and cellular differentiation. HMGB1 is also secreted by activated monocytes and macrophages and passively released by necrotic or damaged cells, stimulating inflammation. HMGB1 is a novel antigen of anti-neutrophil cytoplasmic antibodies (ANCA) observed in the sera of patients with ulcerative colitis and autoimmune hepatitis, suggesting that HMGB1 is secreted from neutrophils to the extracellular milieu. However, the actual distribution of HMGB1 in the cytoplasm of neutrophils and the mechanisms responsible for it are obscure. Here we show that HMGB1 in neutrophils is post-translationally mono-methylated at Lys42. The methylation alters the conformation of HMGB1 and weakens its DNA binding activity, causing it to become largely distributed in the cytoplasm by passive diffusion out of the nucleus. Thus, post-translational methylation of HMGB1 causes its cytoplasmic localization in neutrophils. This novel pathway explains the distribution of nuclear HMGB1 to the cytoplasm and is important for understanding how neutrophils release HMGB1 to the extracellular milieu.

Association of IL-10 and TNFalpha genotypes with ANCA appearance in ulcerative colitis

The appearance of autoantibodies is a common characteristic of ulcerative colitis (UC). Specifically, anti-neutrophil cytoplasmic antibodies (ANCA) are the most prevalent in this disease and their synthesis may be genetically conditioned. The aim of the present study was to test the influence on appearance of autoantibodies of IL-10 and TNFalpha genes promoter polymorphisms, which control cytokine levels. Genetic polymorphisms of TNFalpha (-308 G/A) and IL-10 (-1082 G/A) and ANCA and anti-goblet cells antibodies (GAB) presence were determined in 99 UC patients. The -308A* allele and -308AA/AGTNFalpha genotypes (high producer), clearly correlated with ANCA positivity (p = 0.004 and p = 0.007, respectively). Additionally, homozygous carriage of the -1082A*IL-10 allele (low producer) significantly associated with ANCA presence (p = 0.007). Furthermore, combination of both genotypes (low IL-10/high TNFalpha producer genotype) had a greater influence on ANCA positivity than each individual genotype (p = 0.008). ANCA production in UC thus appears to be conditioned by IL-10 and TNFalpha genotypes.

Detection of autoantibodies for diagnosis of autoimmune hepatitis

AIM: To evaluate the clinical significance of autoantibody detection in the diagnosis of autoimmune hepatitis (AIH).

METHODS: Indirect immunofluorescence was used to detect the expression of anti-nuclear antibody (ANA), anti-smooth muscle antibody (SMA), antineutropil cytoplasmic antibody (ANCA), and anti-mitochondrial antibody (AMA) in patients with autoimmune hepatitis (AIH, n = 47), non-autoimmune hepatitis (n = 158) and healthy controls (n = 40). Enzyme linked immunosorbent assay (ELISA) was used to examine the content of anti-myeloperoxidase (MPO) antibody. The result was retrospectively analyzed.

RESULTS: Comparison between the rates of ANA, SMA and ANCA showed that SMA was found the highest in AIH patients (66.0%, 31/47), significantly higher than that in non-AIH patients (6.3%, 10/158). After chi-square test, SMA and AMA and MPO were markedly different between AIH and primary biliary cirrhosis (PBC) patients (P < 0.01). Finally, ANA, SMA and ANCA were correlated with AIH-Ⅰ, anti-liver/kidney microsomal antibody (LKM) with AIH-Ⅱ, and anti-soluble liver antigen antibody (SLA), ANCA with AIH-Ⅲ.

CONCLUSION: Detection of autoantibodies is helpful in the diagnosis and therapy of AIH.

Antineutrophil cytoplasmic antibodies

Much like other autoantibodies (eg, anti-double stranded DNA in systemic lupus erythematosus or antiglomerular basement membrane antibodies in Goodpasture's syndrome), antineutrophil cytoplasmic antibodies (ANCA) have provided doctors with a useful serological test to assist in diagnosis of small-vessel vasculitides, including Wegener's granulomatosis, microscopic polyangiitis, Churg-Strauss syndrome, and their localised forms (eg, pauci-immune necrotising and crescentic glomerulonephritis). 85-95% of patients with Wegener's granulomatosis, microscopic polyangiitis, and pauci-immune necrotising and crescentic glomerulonephritis have serum ANCA. ANCA directed to either proteinase 3 or myeloperoxidase are clinically relevant, yet the relevance of other ANCA remains unknown. Besides their diagnostic potential, ANCA might be valuable in disease monitoring. In addition, data seem to confirm the long-disputed pathogenic role of these antibodies. Present treatments for ANCA-associated vasculitis are not free from side-effects and as many as 50% of patients relapse within 5 years. Accurate understanding of the key pathogenic points of ANCA-associated vasculitis can undoubtedly provide a more rational therapeutic approach.

HMGB1, a novel inflammatory cytokine

High mobility group box 1 (HMGB1) exhibits unique biochemical functions as a biologically intrinsic requisite factor and as a toxin. As such, it is imperative to understand the mechanism by which these seemingly and diametrically opposed functions are exerted. To effectively discriminate these actions is important to accurately and precisely determine the concentration of HMGB1 in biological samples. Research in this fascinating field, however, has been lacking due to the absence of a simple analytical system for HMGB1 that can be adapted for large sample numbers. In this report, we review the physiological and pathological significance of HMGB1 and describe the development of an assay method for this pleiotropic protein.

Role of auto-antibodies for the diagnosis of chronic cholestatic liver diseases

Auto-antibodies are an integral part of the diagnostic armentarium in chronic cholestatic liver disorders, such as primary sclerosing cholangitis (PSC), primary biliary cirrhosis (PBC),auto-immune cholangitis, or overlap syndromes among these disorders. However, care should be taken not to overestimate the diagnostic specificity. Auto-antibodies to mitochondrial antigens(AMAs) with reactivity to the E2 subunit of the pyruvate dehydrogenase complex represent the hallmark antibody for the diagnosis of PBC, whereas antinuclear antibodies (ANAs)with low disease specificity are found in up to 50% of these sera. Antibodies that recognize nuclear envelope proteins exert a similarly high diagnostic specificity as AMA in PBC but occur at a rather low prevalence. The role of auto-antibodies is less well-studied for patients with PSC, but there is growing evidence that only antineutrophil cytoplasmic antibodies(ANCAs) are of relevant diagnostic significance. In contrast, auto-antibodies-particularlyAMAs-do not contribute to the diagnosis of auto-immune cholangitis, whereas ANCAs,ANAs, smooth muscle antibodies, and AMAs are of varying significance in PBC-auto-immune hepatitis (AIH) or PSC-AIH overlap syndromes. It has been widely accepted that the course of the auto-antibody serum end point titers are not suited for the clinical management of patients with chronic cholestatic liver disorders. Additionally, auto-antibodies in these disorders usually do not contribute to the immunopathogenesis of the disease.

Autoantibodies directed against the UDP-glucuronosyltransferases in human autoimmune hepatitis

Liver-Kidney Microsomes Type 3 (LKM3) autoantibodies (aAbs) have been described in chronic hepatitis D virus infection in 1983. The detection of such aAbs in autoimmune hepatitis (AIH) Type 2 was thereafter reported. The molecular targets of LKM3 aAbs have been identified as enzymes belonging to the UDP-glucuronosyltransferase family 1. Since 20-30% of suspected AIH are negative for the classical autoimmune serological markers, such as aAbs directed against antinuclear autoantibodies, smooth muscle autoantibodies and Liver-Kidney Microsomes Type 1 aAbs, LKM3 aAbs could be of great interest in the diagnosis of such negative AIH. In this review, we discuss the sensitivity and specificity of these aAbs in AIH in order to stress out their potential clinical use as a marker.

Autoantibodies and autoantigens in autoimmune hepatitis: important tools in clinical practice and to study pathogenesis of the disease

Autoimmune hepatitis (AIH) is a chronic necroinflammatory disease of the liver characterized by hypergammaglobulinemia, characteristic autoantibodies, association with HLA DR3 or DR4 and a favorable response to immunosuppressive treatment. The etiology is unknown. The detection of non-organ and liver-related autoantibodies remains the hallmark for the diagnosis of the disease in the absence of viral, metabolic, genetic, and toxic etiology of chronic hepatitis or hepatic injury. The current classification of AIH and the several autoantibodies/target-autoantigens found in this disease are reported. Current aspects on the significance of these markers in the differential diagnosis and the study of pathogenesis of AIH are also stated. AIH is subdivided into two major types; AIH type 1 (AIH-1) and type 2 (AIH-2). AIH-1 is characterized by the detection of smooth muscle autoantibodies (SMA) and/or antinuclear antibodies (ANA). Determination of antineutrophil cytoplasmic autoantibodies (ANCA), antibodies against the asialoglycoprotein receptor (anti-ASGP-R) and antibodies against to soluble liver antigens or liver-pancreas (anti-SLA/LP) may be useful for the identification of patients who are seronegative for ANA/SMA. AIH-2 is characterized by the presence of specific autoantibodies against liver and kidney microsomal antigens (anti-LKM type 1 or infrequently anti-LKM type 3) and/or autoantibodies against liver cytosol 1 antigen (anti-LC1). Anti-LKM-1 and anti-LKM-3 autoantibodies are also detected in some patients with chronic hepatitis C (HCV) and chronic hepatitis D (HDV). Cytochrome P450 2D6 (CYP2D6) has been documented as the major target-autoantigen of anti-LKM-1 autoantibodies in both AIH-2 and HCV infection. Recent convincing data demonstrated the expression of CYP2D6 on the surface of hepatocytes suggesting a pathogenetic role of anti-LKM-1 autoantibodies for the liver damage. Family 1 of UDP-glycuronosyltransferases has been identified as the target-autoantigen of anti-LKM-3. For these reasons the distinction between AIH and chronic viral hepatitis (especially of HCV) is of particular importance. Recently, the molecular target of anti-SLA/LP and anti-LC1 autoantibodies were identified as a 50 kDa UGA-suppressor tRNA-associated protein and a liver specific enzyme, the formiminotransferase cyclodeaminase, respectively. Anti-ASGP-R and anti-LC1 autoantibodies appear to correlate closely with disease severity and response to treatment suggesting a pathogenetic role of these autoantibodies for the hepatocellular injury. In general however, autoantibodies should not be used to monitor treatment, predict AIH activity or outcome. Finally, the current aspects on a specific form of AIH that may develop in some patients with a rare genetic syndrome, the autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy syndrome (APECED) are also given. Autoantibodies against liver microsomes (anti-LM) are the specific autoantibodies detected in AIH as a disease component of APECED but also in cases of dihydralazine-induced hepatitis. Cytochrome P450 1A2 has been identified as the target-autoantigen of anti-LM autoantibodies in both APECED-related AIH and dihydralazine-induced hepatitis. The latter may indicate that similar autoimmune pathogenetic mechanisms can lead to liver injury in susceptible individuals irrespective of the primary defect. Characterization of the autoantigen-autoantibody repertoire continues to be an attractive and important tool to get access to the correct diagnosis and to gain insight into the as yet unresolved mystery of how hepatic tolerance is given up and AIH ensues.

Over-expression of TATA binding protein (TBP) and p53 and autoantibodies to these antigens are features of systemic sclerosis, systemic lupus erythematosus and overlap syndromes

The aim of this study was to determine the expression levels of p53 and TATA binding protein (TBP) and the presence of autoantibodies to these antigens in Asian Indian patients with systemic sclerosis (SSc), overlap syndromes (OS) and systemic lupus erythematosus (SLE). Fifty patients with SSc, 20 with OS, including mixed connective tissue diseases (MCTD), 20 with SLE, 10 disease controls (DC) and 25 controls (C) were studied. The over-expression of p53 and TBP antigen was determined quantitatively by sandwich enzyme-linked immunosorbent assay (ELISA), varies between four- and sevenfold higher in patients with SSc, OS and SLE, in comparison to DC and C. The expressed protein antigens were not present as free antigens but as immune-complexes. Autoantibodies to p53 were detected by ELISA in 78% subjects with SSc, 100% with OS and 80% with SLE. Autoantibodies to TBP were observed in 28% patients with SSc, 25% with OS and 15% with SLE. In comparison to healthy controls, the titre of antibodies to p53 was significantly higher in patients with SSc (P = 0.00001) than the patients with OS (P = 0.00279) and SLE (P = 0.00289), whereas the titre of antibodies to TBP was higher in patients with OS (P = 0.00185) than the SLE (P = 0.00673) and the SSc (P = 0.00986) patients. Autoantibodies to p53 and TBP were detected in all these patients and the levels of these two autoantibodies showed weak negative correlation with each other. We propose that the over-expression of these antigens might be due to hyperactive regulatory regions in the p53 and TBP gene.

Advances in clinical laboratory tests for inflammatory bowel disease

Inflammatory bowel disease (IBD) is a generic term that refers to Crohn's disease and chronic ulcerative colitis (UC). The CD and UC are considered to be distinct forms of IBD; but there is a subgroup of CD with a UC-like presentation. The genetic factors play a significant role in IBD. IBD is associated with a strong familial pattern. Recent studies support the hypothesis that IBD patients have a dysregulated immune response to endogenous bacteria in the gastrointestinal tract. The serologic responses seen in Crohn's disease include antibodies to Saccharomyces cerevisiae, mycobacteria, bacteroides and E. coli. The pANCA antibody seen in UC and CD has been demonstrated to react with epitopes of H1 histone, Bacteroides caccae (Ton-B linked outer membrane protein), Pseudomonas fluorescens-associated bacterial protein I-2, mycobacterial histone 1 homologue called Hup B. In recent years, several serologic markers have been found to be useful for the diagnosis and differentiation of CD and UC. These markers include the following antibodies: (a) pANCA, (b) ASCA, (c) anti-pancreatic antibody, (d) OmpC antibody and (e) I-2 antibody and antibodies to anaerobic coccoid rods. The application of a panel of markers with the use of an algorithm (i.e. IBD First Step) can identify specific subtypes of IBD that have different clinical courses and progression of the diseases. The serologic markers are useful for the diagnosis and management of CD and UC patients.

IgA class antineutrophil cytoplasmic antibodies in primary sclerosing cholangitis and autoimmune hepatitis

Antineutrophil cytoplasmic antibodies (ANCA) of IgG class have been described at high prevalence in autoimmune hepatitis (AIH) and primary sclerosing cholangitis (PSC). Data on IgA class ANCA in these diseases are limited. The aim of this study was to determine the prevalence and fluorescence patterns of IgA class ANCA in AIH and PSC and to examine a relationship between the presence of IgA ANCA and clinical characteristics in these patients. Sera from 35 patients with PSC (21 with concomitant inflammatory bowel disease), 40 patients with AIH and 10 healthy controls were studied. ANCA were detected on ethanol-fixed neutrophils using an indirect immunofluorescence technique. ANCA of the IgA class were found in 20% of sera from patients with PSC and in 50% of AIH sera. The majority of AIH patients with IgA class ANCA showed a 'classical' perinuclear staining pattern, whereas the 'classical' and 'atypical' perinuclear fluorescence patterns were distributed equally in PSC. In sera containing IgG and IgA class ANCA simultaneously, IgG class ANCA showed an 'atypical' pANCA fluorescence pattern whereas IgA class ANCA produced a 'classical' perinuclear staining. The presence of IgA class ANCA was not associated with disease-specific clinical characteristics. IgA class ANCA are more frequently detected in sera of patients with AIH than PSC. The diversity of fluorescence patterns points to different target antigens of IgA class ANCA with distinct subcellular localizations.

Autoantibodies to the transcriptional factor SOX13 in primary biliary cirrhosis compared with other diseases

The molecule SOX13 was initially identified as an autoantigen (ICA12) in Type 1 diabetes. SOX13 is a member of the SOX family of transcriptional regulatory proteins that contain a high mobility group (HMG) motif with structural similarity to HMG proteins 1 and 2. Antibodies to HMG 1 and 2 occur in autoimmune diseases of the liver and in ulcerative colitis. We measured the occurrence and levels of anti-SOX13 by radioimmunoprecipitation in primary biliary cirrhosis (PBC) and other diseases, and compared frequencies with anti-HMG measured by ELISA. Anti-SOX13 was detected in 18% of patients with PBC, 13% with autoimmune hepatitis, 18% with Type 1 diabetes, at lower frequencies in other conditions including the multisystem autoimmune diseases, systemic lupus erythematosus and rheumatoid arthritis, and in 1% of normal sera. Anti-HMG1 and anti-HMG2 occurred at frequencies of 30% and 35% respectively in PBC. Serum levels of anti-SOX13 and anti-HMG correlated significantly for PBC although not for Type 1 diabetes. Anti-SOX13 in PBC may occur merely as an immune response to products of damage to parenchymal tissue, or may be illustrative of a general proclivity of transcriptional regulatory proteins to elicit autoimmune responses.

A DNA microarray study of nitric oxide-induced genes in mouse hepatocytes: implications for hepatic heme oxygenase-1 expression in ischemia/reperfusion

Nitric oxide (NO) can modulate numerous genes directly; however, some genes may be modulated only in the presence of the inflammatory stimuli that increase the expression of the inducible nitric oxide synthase (iNOS). One method by which to examine changes in NO-mediated gene expression is to carry out a gene array analysis on NO-nai;ve cells. Herein, we report a gene array analysis on mRNA from iNOS-null (iNOS(-/-)) mouse hepatocytes harvested from mice exposed to NO by infection with an adenovirus expressing human iNOS (Ad-iNOS). Of the 6500 genes on this array, only approximately 200 were modulated either up or down by the increased iNOS activity according to our criteria for significance. Several clearly defined families of genes were modulated, including genes coding for proinflammatory transcription factors, cytokines, cytokine receptors, proteins associated with cell proliferation and cellular energetics, as well as proteins involved in apoptosis. Our results suggest that iNOS has a generally anti-inflammatory and anti-apoptotic role in hepatocytes but also acts to suppress proliferation and protein synthesis. The expression of iNOS results in increased expression of stress-related proteins, including heme oxygenase-1 (HO-1). We used HO-1 to confirm that a significant change identified by an analysis could be demonstrated as significant in cells and tissues. The elevation of HO-1 was confirmed at the protein level in hepatocytes in vitro. Furthermore, iNOS(-/-) mice experienced greatly increased liver injury subsequent to intestinal ischemia/reperfusion injury, associated with an inability to upregulate HO-1. This is the first study to address the global gene changes induced by iNOS in any cell type, and the findings presented herein may have clinical relevance for conditions such as septic or hemorrhagic shock in which hepatocytes, NO, and HO-1 play a crucial role.

Autoantibodies and defined target autoantigens in autoimmune hepatitis: an overview

Autoimmune hepatitis (AIH) is a disease of unknown aetiology characterised by hypergammaglobulinaemia, non-organ and liver-related autoantibodies, association with HLA-DR3 or DR4 and a favourable response to immunosuppression. The current classification of AIH and the several autoantibodies/target autoantigens found in this disease are reported. The importance of these markers in the differential diagnosis and the study of pathogenesis of AIH is also given. AIH is subdivided into two major types: AIH type 1 (AIH-1) and AIH type 2 (AIH-2). AIH-1 is characterised by the detection of smooth muscle autoantibodies (SMA) and/or antinuclear antibodies (ANA). Antineutrophil cytoplasmic autoantibodies (ANCA), in most cases of perinuclear pattern (p-ANCA), by the indirect immunofluorescence assay, antibodies against the asialoglycoprotein receptor (anti-ASGP-R) and antibodies to soluble liver antigens or liver-pancreas (anti-SLA/LP) may be useful for the identification of individuals who are seronegative for ANA/SMA. AIH-2 is characterised by the presence of specific autoantibodies against liver and kidney microsomal antigens (anti-LKM type 1 or infrequently anti-LKM type 3) and/or autoantibodies against liver cytosol 1 antigen (anti-LC1). Anti-LKM-1 and anti-LKM-3 autoantibodies are also detected in some patients with chronic hepatitis C (HCV) and chronic hepatitis D (HDV). For these reasons, the distinction between AIH and chronic viral hepatitis is of particular importance. Cytochrome P450 2D6 (CYP2D6) is the major target autoantigen of anti-LKM-1 autoantibodies in both conditions (AIH-2 and HCV infection). Recent data have demonstrated the expression of CYP2D6 on the surface of hepatocytes, suggesting a pathogenetic role of anti-LKM-1 autoantibodies in liver injury. Family 1 of UDP-glycuronosyltransferases has been identified as the target autoantigen of anti-LKM-3. The molecular target of anti-SLA/LP autoantibodies has been identified recently as a 50 kDa protein with unknown structure and function. A liver-specific enzyme, the formiminotransferase cyclodeaminase, was identified as the target autoantigen of anti-LC1 autoantibodies. Anti-ASGP-R and anti-LC1 autoantibodies appear to correlate better with the severity of AIH and the response to treatment. The latter may suggest a pathogenic role of these autoantibodies in the hepatocellular damage in AIH. In general, however, autoantibodies should not be used to monitor treatment or to predict AIH activity or outcome. Finally, current knowledge concerning a specific form of AIH that may develop in some patients with a rare genetic syndrome, the autoimmune polyglandular syndrome type-1 (APS-1), is also discussed. Autoantibodies against liver microsomes (anti-LM) are the specific autoantibodies found in AIH as a disease component of APS-1. However, anti-LM autoantibodies have also been described in cases of dihydralazine-induced hepatitis. Cytochrome P450 1A2 has been identified as the target autoantigen of anti-LM autoantibodies in both disease entities.

Differentiation of antineutrophil nuclear antibodies in inflammatory bowel and autoimmune liver diseases from antineutrophil cytoplasmic antibodies (p-ANCA) using immunofluorescence microscopy

Perinuclear antineutrophil cytoplasmic antibodies (p-ANCA) directed against cytoplasmic proteins of neutrophils have been studied extensively in patients with systemic vasculitides. Recent data indicate that antineutrophil antibodies in sera from patients with chronic inflammatory bowel diseases (IBD) or autoimmune liver disorders, currently called 'atypical p-ANCA', recognize a nuclear target antigen, rendering the term 'ANCA' inaccurate. Specific microscopic criteria to distinguish atypical p-ANCA from p-ANCA are lacking. We used planar and confocal laser scanning indirect immunofluorescence microscopy to examine the labelling characteristics of ethanol-, methanol- and formaldehyde-fixed neutrophils by antineutrophil antibodies in 153 serum samples from patients with IBD, autoimmune liver disorders, systemic vasculitides or healthy blood donors. On ethanol- or methanol-fixed neutrophils, multiple intranuclear fluorescent foci together with either a rim-like peripheral nuclear staining ('type A') or a combined cytoplasmic and peripheral nuclear staining ('type B') was noted exclusively with atypical p-ANCA in sera from patients with IBD or autoimmune liver disorders. Intranuclear foci, which probably corresponded to invaginations of the nuclear envelope, were not labelled by p-ANCA from patients with microscopic polyangiitis or cytoplasmic ANCA (c-ANCA) from patients with Wegener's granulomatosis. On formaldehyde-fixed neutrophils, atypical p-ANCA gave a fine rim-like staining of the nuclear periphery, whereas ANCA diffusely labelled the cytoplasm. To distinguish reliably between the patterns produced by atypical p-ANCA or p-ANCA, particularly p-ANCA, careful indirect immunofluorescence microscopy on ethanol- as well as on formaldehyde-fixed neutrophils is necessary, with particular emphasis on the presence of multiple intranuclear fluorescent foci.

Screening of a HUVEC cDNA library with transplant-associated coronary artery disease sera identifies RPL7 as a candidate autoantigen associated with this disease

A HUVEC cDNA library was screened with sera from two patients who had developed transplant-associated coronary artery disease (TxCAD) following cardiac transplantation. A total of six positive clones were isolated from a primary screen of 40 000 genes. Subsequent DNA sequence analysis identified these to be lysyl tRNA synthetase, ribosomal protein L7, ribosomal protein L9, beta transducin and TANK. Another gene whose product could not be identified showed homology to a human cDNA clone (DKFZp566M063) derived from fetal kidney. Full-length constructs of selected genes were expressed as his-tag recombinant fusion proteins and used to screen a wider patient base by ELISA to determine prevalence and association with TxCAD. Of these ribosomal protein L7 showed the highest prevalence (55.6%) with TxCAD sera compared to 10% non-CAD.

Anti-neutrophil antibodies in primary sclerosing cholangitis

Anti-neutrophil specific antibodies are detected in up to 88% of patients with PSC. The labelling pattern of neutrophils produced by these antibodies when examined by indirect immunofluorescence microscopy is distinct from that produced by anti-neutrophil cytoplasmic antibodies (ANCA) in vasculitic diseases. The antigen(s) recognized by anti-neutrophil antibodies in PSC is not yet known but appears to be localized to the periphery of the nucleus. Accordingly, the term peripheral anti-neutrophil nuclear antibodies (p-ANNA) is more appropriate than the frequently used p-ANCA. As the titre of p-ANNA in PSC does not correlate with disease-specific clinical parameters, they are not useful markers for the management of patients. However, the high prevalence of p-ANNA in PSC makes them a reasonable diagnostic marker if used in conjunction with other standard diagnostic tests. The role of anti-neutrophil antibodies in the pathogenesis of PSC, if any, remains to be established.

Cytotoxic effect of an anti-liver monoclonal autoantibody obtained after neonatal thymectomy in mice

A monoclonal autoantibody, LSA-1, against murine liver antigen was obtained by fusing spleen cells from a neonatally thymectomized BALB/c mouse with SP2/0 murine myeloma cells. The LSA-1 isotype was IgG2b and kappa. LSA-1 was specific to the liver, especially, to a liver-specific membrane lipoprotein (LSP) fraction. By Western blotting analysis, LSA-1 mainly detected a 100 kDa protein of LSP fraction. LSA-1 stained cytoplasm of the cryostat sections of liver in immunohistochemical analysis. Furthermore, the antigen recognized with LSA-1 was highly expressed on the surface of a murine hepatoma cell line, MH134, slightly on a murine normal liver cell line, C1469, and on freshly prepared hepatocytes, but not on spleen cells. LSA-1 had a cytotoxic activity on liver cell lines in the presence of a complement in vitro. Furthermore, injection of LSA-1 into mice-induced liver injury. These results suggest that anti-liver autoantibody plays an important role in the induction of autoimmune hepatitis. Accordingly, this antibody will be a useful tool for the analysis of the pathogenesis of autoimmune hepatitis.

Hepatitis C and D, retroviruses and autoimmune manifestations

Chronic infections with hepatitis C virus (HCV) are associated with various autoimmune manifestations, i.e. mixed cryoglobulinemia, membranoproliferative glomerulonephritis, autoimmune thyroid diseases, sporadic porphyria cutanea tarda and B cell lymphoma. Since exacerbation of hepatitis occurs in 5-10% of HCV patients receiving interferon-alpha treatment and may be successfully treated by immunosuppression afterwards, hepatitis C was also suspected to be associated with autoimmune hepatitis. LKM3 autoantibodies in chronic hepatitis D virus (HDV) infection and epitope recognition are discussed. Lately, endogenous and exogenous retroviruses have been investigated for the induction of autoimmune diseases. Human A type retroviral particles (HIAP), reverse transcriptase activity and anti-HIAP autoantibodies were detected in patients with Sjögren's syndrome. Anti-HIAP and anti-HIV p24 autoantibodies are seen in systemic lupus erythematosus, primary biliary cirrhosis and multiple sclerosis. Multiple sclerosis was even associated with a new human retrovirus called multiple sclerosis associated retrovirus (MSRV). In diabetes long terminal repeats (LTR) were detected in the HLA DQB1 locus, which was shown to associate with an increased risk of diabetes. A second retrovirus called IDDMK(1,2)22 was reported to code for a superantigen, which was implicated as a potential cause of diabetes. This hypothesis, however, was challenged repeatedly. Until now it is unknown whether endogenous retroviruses are aetiological agents of autoimmune diseases or an epiphenomenon, induced by coinfecting viruses (e.g. herpes viruses) and inflammatory processes.

Detection of anti-neutrophil cytoplasmic antibodies in MRL/Mp-lpr/lpr mice and analysis of their target antigens

Anti-neutrophil cytoplasmic antibodies (ANCA) have been widely studied and recognized to be clinically very important for some human diseases including systemic rheumatic diseases. We analyzed ANCA response and their target antigens in MRL/Mp-lpr/lpr (MRL-lpr) mice, an animal model of systemic rheumatic disease. P-ANCA was detected in 57% of the mice. Antibodies to the known P-ANCA target antigens at the same age were examined. Among these, antibodies to high mobility group (HMG) proteins HMG1 and HMG2 were detected in 57% of the mice, 75% of which were also positive for P-ANCA. These anti-HMG1/HMG2 activities were absorbed by preincubation with a mixture of HMG1 and HMG2. In contrast, antibodies to myeloperoxidase and cathepsin G were detected in 14% and 7%, respectively, but these activities were not inhibited by preincubation with corresponding antigens. In addition, the titers of P-ANCA and anti-HMG1/HMG2 antibodies in MRL-lpr mice were significantly correlated with each other. Thus, HMG1 and HMG2 were considered to be significant target antigens of P-ANCA in MRL-lpr mice.

Rheumatic disorders associated with hepatitis C

The hepatitis C virus (HCV) is a common virus of world-wide distribution affecting up to 3% of the world's population. Its genetic diversity, with multiple subtypes, and existence in the form of quasispecies in individual hosts, is, in part, responsible for high rates of chronic infection. Individuals with HCV infection will undoubtedly present to rheumatologists and other health care professionals with rheumatic and other immunological disorders related to what was usually a remote and asymptomatic acute infection. The goals of this review are: (1) to summarize clinical observations regarding rheumatological and immunological diseases linked with HCV infection; (2) to provide relevant information on the molecular biology of HCV; (3) to discuss the state of the art regarding the use of diagnostic studies; (4) to consider the differential diagnosis of liver disease and rheumatic disorders; and (5) to provide a practical guide to the history, physical examination, laboratory work-up, disease monitoring, and therapy of HCV patients with rheumatic disorders.

"Atypical p-ANCA" in IBD and hepatobiliary disorders react with a 50-kilodalton nuclear envelope protein of neutrophils and myeloid cell lines

BACKGROUND & AIMS

Atypical "antineutrophil cytoplasmic antibodies" (ANCA) are present in patients with ulcerative colitis (UC), primary sclerosing cholangitis (PSC), and autoimmune hepatitis (AIH). Recently, we showed that atypical p-ANCA react with nuclear envelope proteins of neutrophils. Based on this observation, we aimed to characterize the nuclear antigen recognized by atypical p-ANCA.

METHODS

We prepared cytoplasmic and nuclear extracts of human neutrophils, human HL-60, and murine 32D myeloid cells. Proteins were resolved by 1- and 2-dimensional gel electrophoresis. Reactive proteins were detected by immunoblotting with sera from 118 individuals (UC, 25; PSC, 28; AIH, 35; disease and normal controls, 30). Atypical p-ANCA (n = 64) were affinity-purified against the reactive protein and investigated for their immunofluorescence pattern using confocal microscopy.

RESULTS

Immunoblotting showed reactivity to a myeloid-specific 50-kilodalton nuclear protein with an isoelectric point of pH 6.0 detected in 92% (59 of 64) of the patients with inflammatory bowel or hepatobiliary diseases and atypical p-ANCA. Affinity-purified antibodies against the 50-kilodalton protein gave a nuclear rim-like fluorescence on myeloid cells examined by immunofluorescence microscopy. Affinity-purified antibodies did not recognize antigens in nonmyeloid cells.

CONCLUSIONS

Atypical p-ANCA in UC, PSC, or AIH recognize a 50-kilodalton myeloid-specific nuclear envelope protein.

Autoimmunity and primary biliary cirrhosis

The history of primary biliary cirrhosis (PBC) began in 1851, with autoimmunity introduced in 1958 and expanded from the 1960s on. In PBC, autoantibodies are present to mitochondria-located antigens (AMA) and to nuclear-located antigens (ANA). The AMA react with E2 subunits of three members of the 2-oxoacid dehydrogenase complex family, but most frequently with pyruvate dehydrogenase complex (PDC); the inner lipoyl domain of PDC-E2 contains a major B- and T-cell epitope. The ANA react with three nuclear components, centromeric proteins, nuclear dot proteins and nuclear pore complex. Autoimmune diseases including PBC reflect a failure in mechanisms of self-tolerance which is developed in central lymphoid tissues in embryonic life by deletion of self-reactive lymphocytes, and maintained in peripheral tissues in post-natal life by regulatory processes. Primary biliary cirrhosis has not yet been identified with failure in any one particular tolerance mechanism. Genetic influences are revealed by familial occurrences and by associations with HLA alleles, and environmental influences by epidemiological data. A lead to pathogenesis is the accumulation uniquely in PBC of PDC-E2-like material at the plasma membrance of biliary epithelial cells (BECs). Although the origin of this accumulation of PDC-E2 at the surface of BECs is uncertain, it provides a credible 'tissue-specific' target for an autoimmune attack by T and B lymphocytes at the site of the actual pathology.

Autoimmune liver disease

Regional differences in the manifestations of autoimmune hepatitis underscore the importance of genetic and/or environmental factors in its expression. The -308 polymorphism of TNF-A increases susceptibility to type 1 autoimmune hepatitis; HLA DRB1*13 is an important risk factor in South America; and DRB1*07 characterizes type 2 autoimmune hepatitis. Minocycline and mesalazine can trigger the disease, and interferon therapy can accentuate autoimmune manifestations. Autoimmune cholangitis in Japan is similar to primary biliary cirrhosis, and assays for carbonic anhydrase II lack diagnostic specificity. Perinuclear antineutrophil cytoplasmic antibodies are reactive to diverse nuclear antigens, but high mobility nonhistone chromosomal proteins may be important targets in autoimmune hepatitis. T cells can cross-react with viral and host peptides, and the candidacy of glutathione S-transferases as target autoantigens has been weakened. A murine model of PBC will be useful in studying mechanisms of autoreactivity, and cyclosporine has shown promise in the treatment of children with autoimmune hepatitis. Recurrence after liver transplantation is common, and it may require retransplantation. The human transplantation model will be valuable in understanding the host-and organ-specific contributions to disease expression.

Autoimmune hepatitis

Autoimmune hepatitis (AIH) is a rare disease, characterized by female predominance, hypergammaglobulinemia, autoantibodies, association with HLA DR3 and HLA DR4 and a good response to immunosuppression. Different subtypes of AIH may be distinguished, based on differences in the autoantibody patterns. AIH type 1 is characterized by anti-nuclear (ANA) and/or anti-smooth muscular (SMA) autoantibodies. AIH type 2 is characterized by liver/kidney microsomal autoantibodies (LKM). AIH type 3 may be distinguished by autoantibodies to soluble liver proteins (SLA) or the liver pancreas antigen (LP). AIH-2 affects predominantly pediatric patients and is characterized by a more severe clinical course, a higher frequency of relapse under immunosuppressive treatment and a more frequent progression to cirrhosis. In contrast, AIH types 1 and 3 show a higher age of onset and a better long-term response to immunosuppressive treatment. At present, the treatment of choice is prednisone alone or a combination with prednisone and azathioprine. Both treatment protocols show high survival rates. However, a rate of 13% of treatment failures and the failure to induce permanent remission in most patients underlines the urgent need to develop additional treatment regimens. A yet unknown genetic predisposition is believed to act as the underlying etiological factor in AIH. This genetic predisposition includes a few known risk factors such as the presence of HLA DR3 or HLA DR4, deletions of C4A alleles and female gender. Furthermore, it has to be postulated that defects in immunoregulatory genes exist. A model for such defects may be the autoimmune polyglandular syndrome type 1 (APS1), which results from the defects in a single gene, the autoimmune regulator type 1 (AIRE-1). Patients with APS1 suffer from mucocutaneous candidiasis and a number of organ-specific autoimmune diseases. Characteristic is a high variability in the number and character of the disease components in APS1, indicating that other genetic and environmental factors may strongly modulate the outcome of disease. Environmental factors may comprise chemical influences, such as nutritional compounds and drugs, or virus infections. Several drugs or chemicals were shown to induce hepatitis with autoimmune involvement, e.g. tienilic acid, dihydralazine and halothane. Adduct formation of an activated metabolite is believed to act as a trigger and to induce a specific immune response. Similarly, viruses were repeatedly shown to trigger autoimmune hepatitis. In virus infections, sequence similarities between viral and self-proteins may trigger autoimmune processes and the simultaneous presence of inflammatory cytokines during virus infection may further increase the risk of developing self-perpetuating autoimmune reactions which overshoot.

Colonic bacteria express an ulcerative colitis pANCA-related protein epitope

Bacteria are a suspected pathogenic factor in inflammatory bowel disease, but the identity of the relevant microbial species remains unresolved. The pANCA autoantibody is associated with most cases of ulcerative colitis (UC) and hence reflects an immune response associated with the disease process. This study addresses the hypothesis that pANCA identifies an antigen(s) expressed by bacteria resident in the human colonic mucosa. Libraries of colonic bacteria were generated using aerobic and anaerobic microbiologic culture conditions, and bacterial pools and clonal isolates were evaluated for cross-reactive antigens by immunoblot analysis using the pANCA monoclonal antibody Fab 5-3. Two major species of proteins immunoreactive to pANCA monoclonal antibodies were detected in bacteria from the anaerobic libraries. Colony isolates of the expressing bacteria were identified as Bacteroides caccae and Escherichia coli. Isolation and partial sequencing of the B. caccae antigen identified a 100-kDa protein without database homologous sequences. The E. coli protein was biochemically and genetically identified as the outer membrane porin OmpC. Enzyme-linked immunosorbent assay with human sera demonstrated elevated immunoglobulin G anti-OmpC in UC patients compared to healthy controls. These findings demonstrate that a pANCA monoclonal antibody detects a recurrent protein epitope expressed by colonic bacteria and implicates colonic bacterial proteins as a target of the disease-associated immune response.