Atypical antineutrophil cytoplasmic antibodies with perinuclear fluorescence in chronic inflammatory bowel diseases and hepatobiliary disorders colocalize with nuclear lamina proteins

Autoantibodies to beta tubulin in autoimmune liver diseases-Relation to pANCA and clinical relevance

There was evidence that perinuclear antineutrophil cytoplasmic antibodies (pANCA) in autoimmune liver diseases react with human beta-tubulin-5 (TBB5). Here, we reevaluate the specificity and clinical relevance of anti-TBB5 antibodies. Patients with untreated autoimmune hepatitis (AIH; n = 53), AIH under immunosuppressive therapy (AIH-IS; n = 125), primary sclerosing cholangitis (PSC; n = 40), primary biliary cholangitis (PBC; n = 250), nonautoimmune liver diseases (n = 158), inflammatory bowel diseases (IBD; n = 30), and healthy individuals (n = 62) were tested by enzyme-linked immunosorbent assay for IgG- and IgA-antibodies against recombinant human TBB5. pANCA were detected by immunofluorescence test. Sera were absorbed with TBB5 coupled to cyanogen bromide-activated sepharose. Prevalence and reactivity of IgG anti-TBB5 were significantly higher in patients with untreated AIH (68%; arbitrary units [AU] median: 369) than in PSC (28%; AU median: 84, P < 0.001), other liver diseases (14%; AU median: 185, P < 0.0001), IBD (3%; AU median: 111, P < 0.0001), and healthy controls (3%; AU median: 135; P < 0.0001). Anti-TBB5 did not correlate with pANCA, and immunoprecipitation with TBB5 did not abolish pANCA reactivity. In untreated AIH, anti-TBB5-reactivity was significantly higher than in AIH-IS. Transaminases decreased under IS preferentially in anti-TBB5-negative patients. There was no correlation between anti-TBB5-reactivity and histological stages. IgA-anti-TBB5 was mainly found in alcohol-associated liver disease (ALD; 39%). Our data do not support TBB5 as an autoantigenic target of pANCA. However, IgG-anti-TBB5 showed high specificity for (untreated) AIH. While they did not correlate with histological and laboratory parameters, their presence may indicate a poor response to IS.

Autoimmune Hepatitis: Serum Autoantibodies in Clinical Practice

Circulating autoantibodies are a key diagnostic tool in autoimmune hepatitis (AIH), being positive in 95% of the cases if tested according to dedicated guidelines issued by the International Autoimmune Hepatitis Group. They also allow the distinction between type 1 AIH, characterized by positive anti-nuclear and/or anti-smooth muscle antibody, and type 2 AIH, characterized by positive anti-liver kidney microsomal type 1 and/or anti-liver cytosol type 1 antibody. Anti-soluble liver antigen is the only AIH-specific autoantibody, and is found in 20-30% of both type 1 and type 2 AIH. Anti-neutrophil cytoplasmic antibody is frequently positive in type 1 AIH, being associated also with inflammatory bowel disease and with primary/autoimmune sclerosing cholangitis. The reference method for autoantibody testing remains indirect immunofluorescence on triple tissue (rodent liver, kidney and stomach), allowing both the detection of the majority of liver-relevant reactivities, including those autoantibodies whose molecular target antigens are unknown. Of note, the current knowledge of the clinical significance of autoantibodies relies on studies based on this technique. However, immunofluorescence requires trained laboratory personnel, is observer-dependent, and lacks standardization, leading to ongoing attempts at replacing this method with automated assays, the sensitivity, and specificity of which, however, require further studies before they can be used as a reliable alternative to immunofluorescence; currently, they may be used as complementary to immunofluorescence.

Autoantibodies in Autoimmune Liver Disease-Clinical and Diagnostic Relevance

Testing for liver-related autoantibodies should be included in the workup of patients with hepatitis or cholestasis of unknown origin. Although most of these autoantibodies are not disease specific, their determination is a prerequisite to diagnose autoimmune hepatitis (AIH) and primary biliary cholangitis (PBC), and they are components of the diagnostic scoring system in these diseases. In primary sclerosing cholangitis (PSC), on the other hand, autoantibodies are frequently present but play a minor role in establishing the diagnosis. In PSC, however, data on antibodies suggest a link between disease pathogenesis and the intestinal microbiota. This review will focus on practical aspects of antibody testing in the three major autoimmune liver diseases AIH, PBC, and PSC.

Serology in autoimmune hepatitis: A clinical-practice approach

Serology is key to the diagnosis of autoimmune hepatitis (AIH). Clinicians need to be aware of which tests to request, how to interpret the laboratory reports, and be familiar with the laboratory methodology. If correctly tested, >95% of AIH patients show some serological reactivity. Indirect immunofluorescence on triple rodent tissue is recommended as first screening step, since it allows the detection of all liver-relevant autoantibodies, except for anti-soluble liver antigen (SLA) antibody, which needs to be detected by molecular based assays. The threshold of immunofluorescence positivity is a titer equal or exceeding 1/40, but for patients younger than 18years even lower titers are clinically significant. Anti-nuclear antibody (ANA) and/or anti-smooth muscle (SMA) antibody characterize type 1 AIH. ANA in AIH typically shows a homogeneous staining pattern on HEp2 cells, without any specific target antigen. Anti-SMA displays different staining patterns on indirect immunofluorescence: the vascular/glomerular (VG) and the vascular/glomerular/tubular (VGT) patterns are considered specific for AIH, whilst the V pattern can be found in a variety of diseases. Type 2 AIH, which is rare and affects mostly children/adolescents, is characterized by anti-liver kidney microsomal 1 and/or anti-liver cytosol 1 antibodies. The presence of anti-neutrophil cytoplasmic antibody (ANCA), particularly atypical p-ANCA (pANNA), points to the diagnosis of AIH, especially in absence of other autoantibodies. Since it is associated with sclerosing cholangitis and inflammatory bowel disease, these conditions have to be ruled out. The only antibody specific for AIH is anti-SLA, which is associated with a more severe disease course.

Diagnostic approach to autoimmune hepatitis

INTRODUCTION

Autoimmune hepatitis (AIH) is a chronic inflammatory liver disease which, if left without treatment, can evolve into cirrhosis and possibly liver failure. The diagnosis of AIH is hampered by the lack of specific and reliable markers of the disease and a number of clinical, biochemical, immunological, histological and genetic factors should be considered to reach a confident diagnosis Areas covered: Clinical expression of AIH, histological features, serological and genetic profiles, differential diagnosis, overlap with other autoimmune liver diseases, assessed on the basis of personal experience and review of published literature in the last 10 years through a systematic Medline search (keywords: autoimmune hepatitis, diagnosis) Expert commentary: Notwithstanding numerous efforts to identify simple and reliable markers of the disease, the diagnosis of AIH is still based on the combination of histological, immunological and biochemical features and often can represent a real challenge for the hepatologist.

The Role of Genetic and Immune Factors for the Pathogenesis of Primary Sclerosing Cholangitis in Childhood

Primary sclerosing cholangitis (PSC) is a rare cholestatic liver disease characterized by chronic inflammation of the biliary tree resulting in liver fibrosis. PSC is more common in male less than 40 years of age. The diagnosis of PSC is based on clinical, laboratory, image, and histological findings. A biochemical profile of mild to severe chronic cholestasis can be observed. Endoscopic retrograde cholangiography is the golden standard method for diagnosis, but magnetic resonance cholangiography is currently also considered a first-line method of investigation. Differences in clinical and laboratory findings were observed in young patients, including higher incidence of overlap syndromes, mostly with autoimmune hepatitis, higher serum levels of aminotransferases and gamma-glutamyl transferase, and lower incidence of serious complications as cholangiocarcinoma. In spite of the detection of several HLA variants as associated factors in large multicenter cohorts of adult patients, the exact role and pathways of these susceptibility genes remain to be determined in pediatric population. In addition, the literature supports a role for an altered immune response to pathogens in the pathogenesis of PSC. This phenomenon contributes to abnormal immune system activation and perpetuation of the inflammatory process. In this article, we review the role of immune and genetic factors in the pathogenesis of PSC in pediatric patients.

Autoantibodies in Autoimmune Liver Diseases-Methods of Detection and Interpretation: An Update for the Reporting Pathologist

Autoimmune liver disease (AILD) is a type of chronic liver disease with autoimmune etiology. The diagnosis of the disease is multipronged and detection of autoantibodies in AILDs is an important diagnostic tool and it also helps in the classification of the disease. There are multiple autoantibodies that are detected in AILDs but none is diagnostic. Moreover, these autoantibodies are detected in many other pathological and nonpathological conditions. So the significance of seropositivity for these autoantibodies should be known by both the pathologists as well as the clinicians. In addition, there is prognostic significance associated with some of the antibodies and they also sometimes help in the disease monitoring. The whole array of antibodies detected in AILDs is discussed in detail in this review along with their clinical significance and interpretation.

Mechanisms of tissue injury in autoimmune liver diseases

Autoimmune diseases affecting the liver are mainly represented by autoimmune hepatitis (AIH), primary biliary cirrhosis (PBC) and primary sclerosing cholangitis (PSC). The characteristic morphologic patterns of injury are a chronic hepatitis pattern of damage in AIH, destruction of small intrahepatic bile ducts in PBC and periductal fibrosis and inflammation involving larger bile ducts in PSC. The factors responsible for initiation and perpetuation of the injury in all the three autoimmune liver diseases are not understood completely but are likely to be environmental triggers on the background of genetic variation in immune regulation. In this review, we summarise the current understanding of the mechanisms underlying the breakdown of self-tolerance in autoimmune liver diseases.

Role of the intestinal microbiome in liver disease

The liver integrates metabolic outcomes with nutrient intake while preventing harmful signals derived from the gut to spread throughout the body. Direct blood influx from the gastrointestinal tract through the portal vein makes the liver a critical firewall equipped with a broad array of immune cells and innate immune receptors that recognize microbial-derived products, microorganisms, toxins and food antigens that have breached the intestinal barrier. An overwhelming amount of evidence obtained in the last decade indicates that the intestinal microbiota is a key component of a wide variety of physiological processes, and alterations in the delicate balance that represents the intestinal bacterial communities are now considered important determinants of metabolic syndrome and immunopathologies. Moreover, it is now evident that the interaction between the innate immune system and the intestinal microbiota during obesity or autoimmunity promotes chronic liver disease progression and therefore it might lead to novel and individualized therapeutic approaches. In this review, we discuss a growing body of evidence that highlights the central relationship between the immune system, the microbiome, and chronic liver disease initiation and progression.

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.

Role of gut microbiota in liver diseases

The liver constantly encounters food-derived antigens and bacterial components such as lipopolysaccharide translocated from the gut into the portal vein. Bacterial components stimulate Toll-like receptors (TLR), which are expressed on Kupffer cells, biliary epithelial cells, hepatocytes, hepatic stellate cells, endothelial cells and dendritic cells and recognize specific pathogen-associated molecular patterns. The signaling of TLR to its main ligand triggers inflammation. Usually, in order to protect against hyperactivation of the immune system and to prevent organ failure by persistent inflammation, TLR tolerance to repeated stimuli is induced. In chronic liver diseases, a breakdown in TLR tolerance occurs. Furthermore, Kupffer cells, hepatic stellate cells and natural killer T cells are key components of innate immunity. Decreased numbers and impaired ability of these cells lead to failures in immune tolerance, resulting in persistent inflammation. Recently, the activation of inflammasome was revealed to control the secretion of pro-inflammatory cytokines such as interleukin-1β in response to bacterial pathogens. Innate immunity seems to be an important contributor to the pathogenesis of fatty liver disease and autoimmune liver disease. Recently, probiotics were reported to affect various liver diseases via shifts in gut microbiota and the stability of intestinal permeability. However, many unresolved questions remain. Further analysis will be needed to gain a more comprehensive understanding of the association of innate immunity with the pathogenesis of various liver diseases.

The intestinal microbiota in chronic liver disease

Recent evidence indicates that the intestinal microflora plays a critical role in physiological and pathological processes; in particular, it is now considered a key determinant of immune pathologies and metabolic syndrome. Receiving the majority of its blood supply from the portal vein, the liver represents the first line of defense against food antigens, toxins, microbial-derived products, and microorganisms. Moreover, the liver is critically positioned to integrate metabolic outcomes with nutrient intake. To accomplish this function, the liver is equipped with a broad array of immune networks. It is now evident that, during pathological processes associated with obesity, alcohol-intake, or autoimmunity, the interaction between these immune cell populations and the intestinal microbiota promotes chronic liver disease progression and therefore they represent a novel therapeutic target. Herein, we highlight recent studies that have shed new light on the relationship between the microbiome, the innate immune system, and chronic liver disease progression.

Evolving concepts in primary sclerosing cholangitis

Patients suffering from primary sclerosing cholangitis (PSC) show considerable differences regarding clinical manifestations (i.e. large duct versus small-duct PSC, presence or absence of concomitant inflammatory bowel disease), disease progression, risk for malignancy and response to therapy, raising the question whether PSC may represent a mixed bag of diseases of different aetiologies. The growing list of secondary causes and diseases 'mimicking' or even overlapping with PSC (e.g. IgG4-associated sclerosing cholangitis), which frequently causes problems in clear-cut discrimination from classic PSC and the emerging knowledge about potential disease modifier genes (e.g. variants of CFTR, TGR5 and MDR3) support such a conceptual view. In addition, PSC in children differs significantly from PSC in adults in several aspects resulting in distinct therapeutic concepts. From a clinical perspective, appropriate categorization and careful differential diagnosis are essential for the management of concerned patients. Therefore, the aim of the current review is to summarize current and evolving pathophysiological concepts and to provide up-to-date perspectives including future treatment strategies for PSC.

Recurrence and rejection in liver transplantation for primary sclerosing cholangitis

Primary sclerosing cholangitis (PSC) is a chronic progressive inflammatory disease affecting the bile ducts, leading to fibrosis and eventually cirrhosis in most patients. Its etiology is unknown and so far no effective medical therapy is available. Liver transplantation (LTX) is the only curative treatment and at present PSC is the main indication for LTX in the Scandinavian countries. Close to half of the PSC patients experience one or more episodes of acute cellular rejection (ACR) following transplantation and approximately 1/5 of the transplanted patients develop recurrent disease in the graft. In addition, some reports indicate that ACR early after LTX for PSC can influence the risk for recurrent disease. For these important post-transplantation entities affecting PSC patients, we have reviewed the current literature on epidemiology, pathogenesis, treatment and the possible influence of rejection on the risk of recurrent disease in the allograft.

Autoantibodies pANCA, GAB and PAB in inflammatory bowel disease: prevalence, characteristics and diagnostic value

BACKGROUND

The diagnosis of inflammatory bowel disease (IBD), particularly the differentiation between ulcerative colitis (UC) and Crohn's disease (CD), is difficult and delayed in many cases, despite invasive diagnostic tools.

AIMS

To determine the presence and evaluate the diagnostic accuracy of the potential serological diagnostic markers perinuclear antineutrophil cytoplasmic antibodies (pANCA), autoantibodies to intestinal goblet cells (GAB) and autoantibodies to exocrine pancreas (PAB), together with combinations of these, in the diagnosis of IBD and differential diagnosis of UC and CD.

METHODS

The presence of pANCA, GAB and PAB was determined in indirect immunofluorescence assay of serum samples from 71 patients with IBD (CD 43, UC 28) and 41 healthy controls. The antigen specificity of ANCA was determined using ELISA.

RESULTS

Compared with the control group, we confirmed a statistically significant presence of pANCA (71.4%) and GAB (46.4%) in patients with UC and the presence of PAB only in patients with CD (30.2%) (P < 0.001). In healthy controls, neither PAB nor GAB was detected and pANCA was present in only 4.8%. The sensitivity, specificity and positive and negative predictive values in differentiation of IBD from healthy controls were as follows: pANCA(+): 71%, 95%, 91%, 83%; GAB(+): 46%, 100%, 100%, 73%; PAB(+): 30%, 100%, 100%, 58%; combination of (pANCA(+) or GAB(+))/PAB(-): 82%, 95%, 92%, 87%; and to distinguish UC from CD: pANCA(+): 71%, 98%, 95%, 84%; GAB(+): 46%, 98%, 93%, 74%; PAB(+): 30%, 100%, 100%, 48%; (pANCA(+) or GAB(+))/PAB(-): 82%, 98%, 96%, 89%.

CONCLUSIONS

All three autoantibodies may be helpful tools in non-invasive diagnosis and differential diagnosis of UC and CD. Combination of the autoantibodies may be particularly helpful, as the diagnostic sensitivity is considerably improved.

Autoantibodies as prognostic markers in autoimmune liver disease

Certain autoantibodies in autoimmune liver disease have prognostic implications that are under-utilized and under-developed. The goals of this review are to indicate progress in characterizing the autoantibodies with prognostic connotations and to indicate the feasibility and importance of discovering other markers. Prime source and review articles in English were selected by a Medline search through 2010. Antibodies to soluble liver antigen, actin, liver cytosol type 1, asialoglycoprotein receptor, chromatin, cyclic citrullinated peptide, and uridine glucuronosyltransferases have been associated with the occurrence, severity, and progression of autoimmune hepatitis, and antibodies to Sp100, gp210, and centromere have had similar implications in primary biliary cirrhosis. Antibodies to soluble liver antigen have shown the most promise in autoimmune hepatitis as they have been associated with severe histological changes, long durations of treatment, relapse after drug withdrawal, and high frequency of liver failure. Antibodies to the nuclear rim pore protein, gp210, have shown the most promise in primary biliary cirrhosis as they have been associated with severe interface hepatitis, lobular inflammation, and progression to liver failure. The major limitations of the autoantibodies have been their lack of standardized assays, low negative predictabilities, and fluctuating levels. Performance parameters will improve as critical pathogenic pathways, comprehensive testing batteries, and standardized assays through international exchange workshops are developed. Progress has been made in identifying the serological markers of prognosis in autoimmune liver disease, and they promise to reflect critical disease mechanisms and enhance patient management.

The role of autoantibodies as diagnostic markers of autoimmune hepatitis

Autoantibody testing is the first step towards the diagnosis of autoimmune hepatitis, and it is essential in the evaluation of acute and chronic hepatitis of undetermined cause and allograft dysfunction following liver transplantation. A standard diagnostic repertoire has been promulgated, and other autoantibodies are emerging that may have prognostic value. Supplemental autoantibodies may prove useful in assessing patients who lack the standard markers or who are distinctive among those with conventional markers. Serologic testing will improve as assays are standardized by serum exchange workshops, core diagnostic batteries are codified and promulgated, and markers emerge that are tightly associated with pathogenic mechanisms, and closely reflect disease activity and outcome.

Update on primary sclerosing cholangitis

Early studies in primary sclerosing cholangitis (PSC) were concerned with disease characterization, and were followed by epidemiological studies of PSC and clinical subsets of PSC as well as a large number of treatment trials. Recently, the molecular pathogenesis and the practical handling of the patients have received increasing attention. In the present review we aim to give an update on the pathogenesis of PSC and cholangiocarcinoma in PSC, as well as to discuss the current opinion on diagnosis and treatment of PSC in light of the recent European Association for the Study of the Liver and the American Association for the Study of Liver Diseases practice guidelines.

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.

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.

Autoimmune liver serology: Current diagnostic and clinical challenges

Liver-related autoantibodies are crucial for the correct diagnosis and classification of autoimmune liver diseases (AiLD), namely autoimmune hepatitis types 1 and 2 (AIH-1 and 2), primary biliary cirrhosis (PBC), and the sclerosing cholangitis variants in adults and children. AIH-1 is specified by anti-nuclear antibody (ANA) and smooth muscle antibody (SMA). AIH-2 is specified by antibody to liver kidney microsomal antigen type-1 (anti-LKM1) and anti-liver cytosol type 1 (anti-LC1). SMA, ANA and anti-LKM antibodies can be present in de-novo AIH following liver transplantation. PBC is specified by antimitochondrial antibodies (AMA) reacting with enzymes of the 2-oxo-acid dehydrogenase complexes (chiefly pyruvate dehydrogenase complex E2 subunit) and disease-specific ANA mainly reacting with nuclear pore gp210 and nuclear body sp100. Sclerosing cholangitis presents as at least two variants, first the classical primary sclerosing cholangitis (PSC) mostly affecting adult men wherein the only (and non-specific) reactivity is an atypical perinuclear antineutrophil cytoplasmic antibody (p-ANCA), also termed perinuclear anti-neutrophil nuclear antibodies (p-ANNA) and second the childhood disease called autoimmune sclerosing cholangitis (ASC) with serological features resembling those of type 1 AIH. Liver diagnostic serology is a fast-expanding area of investigation as new purified and recombinant autoantigens, and automated technologies such as ELISAs and bead assays, become available to complement (or even compete with) traditional immunofluorescence procedures. We survey for the first time global trends in quality assurance impacting as it does on (1) manufacturers/purveyors of kits and reagents, (2) diagnostic service laboratories that fulfill clinicians’ requirements, and (3) the end-user, the physician providing patient care, who must properly interpret test results in the overall clinical context.

Analysis of serum antibodies in patients suspected of having inflammatory bowel disease

Inflammatory bowel disease (IBD) is the general term used for a heterogeneous group of intestinal disorders, including Crohn's disease (CD) and ulcerative colitis (UC). Serological markers such as anti-Saccharomyces cerevisiae antibodies (ASCA) and atypical perinuclear antineutrophilic cytoplasmic antibody (atypical pANCA) have proven useful in the diagnosis and differentiation of CD and UC. Immunoglobulin A (IgA) antibody directed against the outer membrane protein C (OmpC) of Escherichia coli is said by one group to have clinical utility in diagnosing IBD, specifically in ASCA-negative CD patients. Our objective in this study was to compare the results obtained from two separate laboratories offering similar IBD tests using sera from suspected IBD patients. One hundred ninety-seven sera received for IBD testing were included in the study. The agreement between the two laboratories was 93.4% for ASCA IgA, 90.9% for ASCA IgG, and 87.8% for atypical pANCA IgG. There were 25 sera with ASCA-negative/OmpC-positive results reported by one laboratory. Thirteen of these 25 (52.0%) ASCA-negative/OmpC-positive sera were also atypical pANCA positive (9 as determined by both laboratories, 3 by one, and 1 by the other). Atypical pANCA antibody is found primarily in IBD patients with UC and colon-limited CD (Crohn's colitis). We conclude that the ASCA and atypical pANCA assays showed good agreement between the two laboratories, but the data for ASCA-negative/OmpC-positive sera suggest that many (52.0%) of these patients were more likely to have had UC or Crohn's colitis based on the presence of an atypical pANCA.

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 in autoimmune liver disease

Autoantibodies indicate an immune reactive state, but in liver disease they lack pathogenicity and disease specificity. Antinuclear antibodies, smooth muscle antibodies, antibodies to liver/kidney microsome type 1, antimitochondrial antibodies, and perinuclear antineutrophil cytoplasmic antibodies constitute the standard serological repertoire that should be assessed in all liver diseases of undetermined cause. Antibodies to soluble liver antigen/liver pancreas, asialoglycoprotein receptor, actin, liver cytosol type 1, nuclear antigens specific to primary biliary cirrhosis, and pore complex antigens constitute an investigational repertoire that promises to have prognostic and diagnostic value. These autoantibodies may emerge as predictors of treatment response and outcome. Antibodies to histones, doubled-stranded DNA, chromatin, and lactoferrin constitute a supplemental repertoire, and they support the immune nature of the liver disease. Final diagnoses and treatment strategies do not depend solely on serological markers. Autoantibodies are floating variables, and their behavior does not correlate closely with disease activity. There are no minimum levels of significant seropositivity, especially in children. Over-interpretation is the major pitfall in the clinical application of the serological results. New autoantibodies will emerge as the search for target antigens and key pathogenic pathways continues.

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.

Clinical applications of antineutrophil cytoplasmic antibody testing

PURPOSE OF REVIEW

Antineutrophil cytoplasmic antibodies are closely associated with Wegener granulomatosis, microscopic polyangiitis, and Churg-Strauss syndrome and have contributed to new pathogenetic concepts and improved nomenclature of systemic vasculitides (antineutrophil cytoplasmic antibody-associated vasculitides). However, the application of antineutrophil cytoplasmic antibody testing as a clinical diagnostic tool is still regarded as controversial. This review summarizes the most recent developments in the field, identifies areas of uncertainty, and gives practical guidelines.

RECENT FINDINGS

The problems of antineutrophil cytoplasmic antibody testing include the diversity of antineutrophil cytoplasmic antibody target antigens, assay standardization and performance, the application of antineutrophil cytoplasmic antibody testing in a clinical setting with a low pretest probability, and, finally, the widespread assumption that antineutrophil cytoplasmic antibody titers alone may closely reflect disease activity and therefore may be used to guide therapy.

SUMMARY

Recent findings demonstrate that the combined use of indirect immunofluorescence tests and solid phase assays to detect antineutrophil cytoplasmic antibody directed against myeloperoxidase and proteinase 3 can minimize the occurrence of false-positive antineutrophil cytoplasmic antibody results. Furthermore, the yield of antineutrophil cytoplasmic antibody testing can be improved by the use of a well-standardized test, adherence to published guidelines, and restricting the use of the tests to clinical situations with a rather high pretest probability for antineutrophil cytoplasmic antibody-associated vasculitides. However, treatment decisions should be based on the clinical presentation of the patient and histologic findings and not on the results of antineutrophil cytoplasmic antibody testing alone.

Autoantibodies in the diagnosis and management of liver disease

Autoantibodies are nonpathogenic manifestations of immune reactivity, and they may occur in acute and chronic liver diseases. Autoantibodies may be consequences rather than causes of the liver injury, and they should be regarded as diagnostic clues rather than etiologic markers. Conventional autoantibodies used in the categorization of autoimmune liver disease are antinuclear antibodies, smooth muscle antibodies, antibodies to liver/kidney microsome type 1, antimitochondrial antibodies, and atypical perinuclear anti-neutrophil cytoplasmic antibodies. Ancillary autoantibodies that enhance diagnostic specificity, have prognostic connotation, or direct treatment are antibodies to endomysium, tissue transglutaminase, histones, doubled-stranded DNA, and actin. Autoantibodies that have an emerging diagnostic and prognostic significance are antibodies to soluble liver antigen/liver pancreas, asialoglycoprotein receptor, liver cytosol type 1, and nuclear pore complex antigens. Autoantibodies of uncertain clinical value that remain under investigation are antibodies to chromatin, lactoferrin, and Saccharomyces cervisiae. Continued recognition and characterization of autoantibodies should improve diagnostic precision, provide prognostic indices, and elucidate target autoantigens. These advances may in turn clarify pathogenic mechanisms, facilitate the development of animal models, and generate novel site-specific therapies.

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.

New autoantibodies and autoantigens in autoimmune hepatitis

The molecular characterization of the autoreactivities associated with autoimmune liver disease will improve their diagnosis and enhance understanding of their pathogenic mechanisms. Surprisingly, little is known about the nature of the major autoreactivities associated with type 1 AIH, including homogeneous ANA and antibodies to microfilaments [3]. Type 1 AIH is, however, the prototype of autoimmune liver disease [103].

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.

Osteoporosis and other complications of inflammatory bowel disease

Osteoporosis has received increasing attention as a potential complication of inflammatory bowel disease (IBD). The first population-based data on incidence of fractures in an IBD population were published this past year. The incidence of fractures was one per 100 patient years. Compared with the general population, the fracture rate was increased; however, the relative risk was 1.4 and, therefore, not as high as might be expected from the myriad of studies reporting high rates of osteopenia measured by dual energy x-ray absorptiometry (DXA). Another area receiving increasing attention is that of the enhanced risk of venous thrombosis in patients with IBD. The first population-based incidence rates of venous thrombosis in IBD were also published this past year and showed that IBD patients are affected by venous thrombosis at a rate of approximately one per 200 patient years. The relative risk for venous thrombosis compared with the general population was 3.5. Several studies have reported on associated risk markers or genetic clotting abnormalities, but no clear paradigm has emerged to account for those patients who will suffer a clot. Finally, the first North American population-based study was published, quantifying the prevalence rates of extraintestinal manifestations in patients with IBD for at least 10 years. Some gender- and disease-specific findings emerged. This study found that iritis and uveitis were more common in female patients with ulcerative colitis (3.2%), primary sclerosing cholangitis (PSC) was most common in male patients with ulcerative colitis (3%), ankylosing spondylitis was most common in male patients with Crohn disease (2.7%), and erythema nodosum was most likely to occur in female patients with Crohn disease (1.9%).

Hepatobiliary disease in inflammatory bowel disease

Many hepatobiliary diseases are seen in IBD. PSC is the most common, occurring in 7.5% of patients with UC. The cause of PSC is not well understood, but PSC seems to be associated with genetic susceptibility, sharing some immunologic abnormalities with UC. A characteristic cholangiogram in a patient with abnormal liver function tests usually establishes the diagnosis. Liver biopsy is not essential but can help make the diagnosis of small duct PSC in patients with a normal cholangiogram. There are no medications that treat PSC effectively. Endoscopic dilation of dominant strictures reduces the frequency of cholangitis and may improve survival. OLT remains the only proven treatment of advanced PSC. Cholangiocarcinoma is a feared complication of PSC that is difficult to diagnose. Cholelithiasis, PBC, portal vein thrombosis, and hepatic abscess are hepatobiliary disorders that occur less frequently in IBD patients.

Extraintestinal manifestations of inflammatory bowel disease

Patients with inflammatory bowel disease (IBD) may confront a variety of nonintestinal problems. The first North American population-based data describing the incidence rates of several of these disorders have been reported over the past year. Reports have also documented our expanding knowledge of peristomal pyoderma gangrenosum, and of ulcerative colitis following liver transplantation in patients with primary sclerosing cholangitis. Osteopenia continues to receive considerable attention. Factors such as osteoprotegrin ligand, and its interaction with receptor activator of nuclear factor kappa B, are connected with T-cell activity, inflammation, and osteoclastogenesis. Studies in these and other areas are addressed in this review.

Current concepts in the diagnosis, pathogenesis, and treatment of autoimmune hepatitis

Autoimmune hepatitis has a global distribution and affects all ages. Genetic factors strongly influence susceptibility, clinical expression, and treatment response. The diagnosis of autoimmune hepatitis has been codified by an international panel. An acute or fulminant presentation is recognized but not a cholestatic form. Subclassifications by predominant autoantibody profile have been proposed, but they lack etiologic and prognostic differences. Autoantibodies continue to be characterized to improve diagnostic specificity, predict outcome, and identify pertinent antigenic targets. Cytosolic enzymes are prime candidates as autoantigens. DRB1*0301 and DRB1*0401 are the susceptibility alleles in Caucasoid Northern Europeans and North Americans, and they also affect clinical expression and treatment outcome. Other autoimmune promoters affecting cytokine production and immunocyte activation may act in synergy with the susceptibility alleles to affect disease behavior. Cell-mediated and antibody-dependent forms of cytotoxicity are probably interactive pathogenic mechanisms, and novel site-specific therapies are feasible because these mechanisms are defined. Potent new immunosuppressive agents are emerging from the transplantation arena, but prednisone alone or in combination with azathioprine remains the mainstay of treatment. Corticosteroid therapy is effective but not ideal.

Diagnostic methodologies: serology, endoscopy, and radiology

The two major inflammatory bowel diseases, Crohn's disease (CD) and ulcerative colitis (UC), represent clinicopathologic entities that traditionally have been diagnosed on the basis of a combination of clinical, radiologic, endoscopic, and histologic features. Serum perinuclear antineutrophil cytoplasmic antibodies (pANCA) and anti-Saccharomyces cerevisiae antibodies (ASCA) have recently been added to our diagnostic armamentarium. Several studies have demonstrated that UC-associated pANCAs recognize nuclear antigens. Additional studies have demonstrated that the pANCA human monoclonal antibody (mAb) Fab 5-3 reacts with histone H1 and with bacterial and mycobacterial antigens. Several reports have suggested that, in CD, pANCA and ASCA are correlated with colonic and small bowel disease respectively. One study found that higher ASCA levels were correlated with more aggressive CD. Serology may prove to be useful in predicting the evolution of indeterminate colitis. Magnetic resonance imaging (MRI) and leukocyte scintigraphy hold promise in identifying inflammatory CD. MRI enteroclysis is useful in identifying both luminal small bowel disease and extraluminal complications. A recent study of surveillance colonoscopy in extensive Crohn's colitis showed a high risk of dysplasia and cancer.

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.

Sclerosing cholangitis

Primary sclerosing cholangitis is a chronic cholestatic disease that may have an autoimmune basis. Most patients have a circulating antineutrophil cytoplasmic antibody that appears to be targeted against a 50-kD nuclear envelope protein. The clinical applications of this antibody have not yet been defined. Other autoantibodies directed against antigens, such as cathepsin G, elastase, and anticardiolipin, may also be detected in some patients. It is suggested that primary sclerosing cholangitis may have a bacterial cause. Helicobacter gene sequences have been detected in liver tissues in primary sclerosing cholangitis. The role of Helicobacter spp and other bacteria in the etiopathogenesis of primary sclerosing cholangitis remains to be determined. Primary sclerosing cholangitis may overlap with autoimmune hepatitis in some cases, although the real prevalence of this association remains to be determined. Many prognostic models have been created, but they lack cross-validation, and their clinical usefulness remains limited. Endoscopic retrograde cholangiography remains the gold standard for diagnosis, but magnetic resonance imaging may be a viable alternative in many cases. Clinical trials with cladibrine, pentoxifylline, and budesonide have failed to demonstrate benefits. Orthotopic liver transplantation remains the only effective treatment.

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.

Antilactoferrin antibodies in autoimmune liver disease

Antilactoferrin antibodies have been reported in patients with several autoimmune disorders, including primary biliary cirrhosis, autoimmune hepatitis and autoimmune cholangitis. We investigated the prevalence and the clinical significance of such autoreactivity in patients with autoimmune and viral chronic liver disease. Sera from 39 patients with autoimmune hepatitis, 51 with primary biliary cirrhosis, 17 with autoimmune cholangitis, 24 with primary sclerosing cholangitis and 28 with HCV-related chronic hepatitis were studied. Positivity for antilactoferrin antibodies was evaluated by Western immunoblotting with purified human lactoferrin. Antilactoferrin antibodies were detected more often in autoimmune liver disorders (25% autoimmune hepatitis, 25% primary biliary cirrhosis, 35% autoimmune cholangitis, 29% primary sclerosing cholangitis) than in HCV-related chronic hepatitis (3.5%, P < 0.02 versus all). Positivity for antilactoferrin antibodies was not associated with a particular clinical or biochemical profile of the underlying liver disease. No correlation was observed between antilactoferrin reactivity and perinuclear antineutrophil cytoplasmic antibodies. Antilactoferrin antibodies are present significantly more often in autoimmune than in viral liver disorders, but they cannot be considered the serological marker of a specific autoimmune liver disease.

Anti-nuclear envelope antibodies: Clinical associations

OBJECTIVES

Characterization of the clinical associations and clinical implications of antibodies reacting with antigens of the nuclear envelope.

METHODS

Description of an illustrative case and a MEDLINE search-assisted literature review of relevant cases.

RESULTS

With indirect immunofluorescence, autoantibodies directed against various antigens of the nuclear envelope stain the nucleus in a ring-like (rim) pattern. Autoantibodies against 5 antigenic components of the nuclear envelope have been described: anti-gp210, p62, lamina, lamina-associated polypeptides, and lamin B receptor. Antibodies to antigens of the nuclear pore complex, such as gp210 and p62, are highly specific (> 95%) for primary biliary cirrhosis and may aid in the serologic diagnosis of this condition, especially in cases in which antimitochondrial antibodies are not detectable. In contrast, antilamin antibodies are not disease-specific but seem to be associated with lupus anticoagulant or anticardiolipin antibodies, antiphospholipid syndrome, thrombocytopenia, autoimmune liver diseases, and arthralgia. High-titered antilamin antibodies help to define a subset of lupus patients with antiphospholipid antibodies who are at a lower risk of developing thrombotic events. In addition, preliminary data suggest that the presence of antilamin antibodies may be helpful in the diagnosis of chronic fatigue syndrome.

CONCLUSIONS

Each of the antibodies reacting with nuclear membrane antigens has its own spectrum of disease associations.

RELEVANCE

Determination of anti-nuclear envelope antibody pattern by indirect immunofluorescence, with subsequent determination of the specific antibody, carries important diagnostic and prognostic implications in various autoimmune conditions.

Anti-Saccharomyces cerevisiae antibodies (ASCA), phenotypes of IBD, and intestinal permeability: a study in IBD families

BACKGROUND

Serologic markers anti-Saccharomyces cerevisiae antibodies (ASCA) and antineutrophil cytoplasmic antibodies with perinuclear staining (pANCA) have been proposed to study the immunopathogenesis of IBD. Their measurement may allow better phenotyping of the disease and the detection of subclinical disease.

AIMS

To test the hypothesis that serological markers identify an immunologic trait related to disease susceptibility. We also wanted to test the hypothesis that ASCA is a marker related to abnormal tissue permeation by common antigens.

METHODS

We studied the prevalence of pANCA and ASCA in a large cohort of sporadic and familial inflammatory bowel diseases and their unaffected relatives and spouses. Kinetics of ASCA was studied and the relationship between ASCA and 51Cr-EDTA intestinal permeation was investigated.

RESULTS

ASCA was associated with sporadic Crohn's disease (CD) (63%), with Crohn's patients belonging to pure CD families (62%) and also with their unaffected family members (21%). pANCA was associated with UC (58%). The prevalence of ASCA in CD patients belonging to mixed families was strikingly low (33%). ASCA was a stable marker throughout the disease and was not related to an increased small intestinal permeability.

CONCLUSION

ASCA is strongly associated with familial CD in Belgium, and 21% of healthy family members also display the marker. The association is much weaker in patients belonging to mixed families. ASCA is a stable marker and is not a secondary phenomenon due to increased intestinal permeability.

Immunopathogenesis of cholestatic autoimmune liver diseases

Primary biliary cirrhosis and primary sclerosing cholangitis are well recognized chronic cholestatic liver diseases that are considered to have an autoimmune basis. Recent progress in the study of autoimmune liver diseases has improved the recognition and characterization of these conditions. An important component of this progress has been the identification of liver disease-associated autoantibodies and their respective target antigens, and the development of specific assays for these autoantibodies. In addition, some nonhumoral immunological findings imply an involvement of specific immunopathogenic mechanisms in the development of these conditions. Furthermore, immunogenetic factors associated with increased susceptibility to some of these diseases have been identified. This article reviews the most relevant information relating to the postulated autoimmune pathogenesis of these diseases, with special emphasis on their associated humoral and cellular immunological abnormalities and immunopathogenetic factors. Some of the remaining important unresolved issues relating to the pathogenesis of these diseases, that need to be addressed in further research, are highlighted.