Antineutrophil cytoplasmic antibodies in autoimmune hepatitis

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.

Sulphite oxidase (SO) - a mitochondrial autoantigen as target for humoral and cellular immune reactions in primary sclerosing cholangitis

Background

In a recent study we had evidence that sulphite oxidase (SO) may be a relevant autoantigen in primary sclerosing cholangitis (PSC). Aim of the present study was, therefore, to analyse humoral and cellular immune-reactivity towards SO in these patients in more detail.

Methods

Sera from 53 patients with PSC (30 untreated and 23 treated with ursodeoxycholic acid [UDCA] at time of analysis), from 422 patients with different hepatic and non-hepatic disorders, and from 50 healthy individuals were tested by ELISA for antibodies against full-length-SO (SO-fl) and its three major domains expressed in E.coli (SO-I, SO-II, SO-III). For epitope-mapping, 29 overlapping peptides were used. Peripheral blood mononuclear cells (PBMC) were obtained from 33 PSC-patients and analysed for SO-induced proliferation, production of cytokines, and expression of the activation marker cluster of differentiation (CD) 69.

Results

43% of the 30 untreated and 26% of the 23 treated PSC-patients had IgG anti-SO-antibodies predominantly reacting with SO-fl, SO-I and SO-II. Antibody-reactivity decreased after UDCA-treatment. Prevalence and reactivity of anti-SO-antibodies were significantly higher in PSC than in patients with other hepatic and non-hepatic disorders. Epitope mapping revealed no distinct immuno-dominant regions within SO. Incubation of PBMC from PSC-patients (but not from controls) with SO-antigens revealed an activation of B-cells and a T-helper cell type-2 reaction pattern (production of interleukin [IL]-13, IL-10).

Conclusions

PSC-patients show humoral and cellular immune response towards SO. Antibodies may be predominantly directed against conformational epitopes. SO enhances in vitro especially T-helper cell type-2 immune-reactions, which may be pro-fibrotic. SO is a detoxifying enzyme present also in bacteria; further studies analysing its role in the aetiology and pathogenesis in PSC may, therefore, be important.

Electronic supplementary material

The online version of this article (10.1186/s12876-018-0787-x) contains supplementary material, which is available to authorized users.

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.

Clinical profile of primary sclerosing cholangitis in Singapore

BACKGROUND AND AIM

Primary sclerosing cholangitis (PSC) is a rare chronic disease in Singapore and its epidemiological profile has not been described previously. The present study aimed to define the demographic and clinical profile of patients with PSC in Singapore.

METHODS

The case records of patients with PSC seen at Changi General Hospital were analyzed in terms of demographic profile, clinical presentation, clinical course, treatment and complications.

RESULTS

Ten cases of PSC were diagnosed over a 10-year period. The male:female ratio was 9:1. The median age of diagnosis was 49.5 years (mean: 50.9 years; range: 35-63 years). With regards to clinical presentation, seven patients had hepatobiliary sepsis, two patients had asymptomatic liver biochemistry abnormalities while one patient had cholestatic jaundice. Prevalence rate of perinuclear antineutrophil cytoplasmic antibody (pANCA) was 20%. Symptomatic inflammatory bowel disease (IBD) was diagnosed in 20% of PSC cases. Eight patients (80%) had intrahepatic ductal involvement while two patients (20%) had combined intrahepatic and extrahepatic ductal involvement on endoscopic retrograde cholangiopancreatography (ERCP). The prevalence rate of recurrent cholangitis was 30% while that of recurrent liver abscess, cirrhosis and common bile duct stricture were all 10%. The mean duration of follow up was 6.6 years with one death from liver failure.

CONCLUSION

The clinical profile of patients with PSC in Singapore appears to differ with other published data, with a greater number presenting with hepatobiliary sepsis and less frequent association with IBD and pANCA. It is hypothesized that this may be related to differences in environmental triggers and genetic susceptibility.

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.

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.

Autoimmune liver disease. Current standards, future directions

The diagnosis and management of autoimmune hepatitis continues to evolve as new diagnostic tests and new therapies are added to the armamentarium. Also encouraging are the advances in the understanding of the human immune system and its involvement in the origin and course of auto immune diseases in general and in the variants of autoimmune liver disease. Promising changes are expected in the next few years as new medications become available to the practicing hepatologist. New immune tests may allow therapies to be customized to patients, and antiviral therapies may also eventually be used in the management of this autoimmune liver diseases.

Antilactoferrin antibodies in autoimmune liver diseases

OBJECTIVE

Lactoferrin, an immunoregulatory protein in mucosal secretions, is one of the target antigens to perinuclear antineutrophil cytoplasmic antibodies (P-ANCAs). Circulating lactoferrin is cleared in the liver, but little is known about the implication of lactoferrin in hepatic inflammation. To evaluate the implication of immunological response to lactoferrin, we examined antilactoferrin antibodies in autoimmune liver diseases.

METHODS

Fourteen patients with primary biliary cirrhosis (PBC), 14 with autoimmune hepatitis (AIH), five with autoimmune cholangitis (AIC), six with chronic hepatitis C, and five with chronic hepatitis B were studied. We evaluated autoantibodies to lactoferrin in the sera of the patients by the Western Immunoblotting method.

RESULTS

Sera of five of the 14 patients (35.7%) with PBC, four of the 14 patients (28.6%) with AIH, and five of the five patients (100%) with AIC contained autoantibodies to human lactoferrin, but none with hepatitis B or C had them. The higher prevalence of serum antibodies to human lactoferrin was shown to be higher in patients with AIC than with hepatitis B (p < 0.01), hepatitis C (p < 0.01), PBC (p < 0.05), and AIH (p < 0.05).

CONCLUSION

Lactoferrin located in bile ducts and liver cells is one of the candidates of target antigens in autoimmune liver diseases, especially in AIC.