Predicting and preventing autoimmunity: the case of anti-mitochondrial antibodies

Sequence of events leading to primary biliary cholangitis

Primary biliary cholangitis (PBC) is a chronic cholestatic liver disease that is observed more frequently in middle-aged women. This disorder is considered an autoimmune disease, since liver injury is sustained by the presence of self-directed antimitochondrial antibodies targeting the bile duct cells. The prognosis may vary depending on an early diagnosis and response to therapy. However, nearly a third of patients can progress to liver cirrhosis, thus requiring a liver transplant. Traditional immunosuppressive therapies, commonly employed for other autoimmune diseases, have limited effects on PBC. In fact, dramatic functional changes that occur in the biliary epithelium in the course of inflammation play a major role in perpetuating the injury. In this minireview, after a background on the disease and possible predisposing factors, the sequential cooperation of cellular/molecular events leading to end-stage PBC is discussed in detail. The rise and maintenance of the autoimmune process, as well as the response of the biliary epithelia during inflammatory injury, are key factors in the progression of the disease. The so-called "ductular reaction (DR)", intended as a reactive expansion of cells with biliary phenotype, is a process frequently observed in PBC and partially understood. However, recent findings suggest a strict relationship between this pathological picture and the progression to liver fibrosis, cell senescence, and loss of biliary ducts. All these issues (onset of chronic inflammation, changes in secretive and proliferative biliary functions, DR, and its relationship with other pathological events) are discussed in this manuscript in an attempt to provide a snapshot, for clinicians and researchers, of the most relevant and sequential contributors to the progression of this human cholestatic disease. We believe that interpreting this disorder as a multistep process may help identify possible therapeutic targets to prevent evolution to severe disease.

Can Antinuclear Antibodies (ANA) be Monoclonal?

Background

Nuclear staining by immunofluorescence in a kidney biopsy is often seen in patients with positive antinuclear antibodies (ANA) in the serum. These ANA are usually polyclonal, but herein we report 9 cases with an unusual finding of monoclonal nuclear staining by immunofluorescence on kidney biopsy. Case Presentation. Nine cases with predominant stain for kappa or lambda light chain were identified by searching the renal pathology laboratory database for the past 10 years. All cases had positive stain for only kappa (six cases) or lambda (three cases) light chain in the nuclei. Eight out of nine cases had positive nuclear IgG stain, and one case had positive nuclear IgA stain. Among cases with positive nuclear IgG staining, six cases were positive for IgG1 subclass, one case was positive for IgG2 subclass, and one case was positive for IgG3 subclass. All patients with positive IgG nuclear stain, who had testing for ANA, had positive ANA. Patients with positive IgG1 subclass did not have monoclonal protein in the serum or urine, but the patient with positive IgG2 subclass and lambda light chain stain in the nuclei had IgG lambda monoclonal gammopathy.

Conclusions

We identified a new unique pattern of nuclear stain by immunofluorescence in kidney biopsies that suggests the presence of monoclonal ANA. Workup for underlying monoclonal gammopathy is warranted in such patients.

Multiple Autoimmune Syndrome: An Unusual Combination of Autoimmune Disorders

BACKGROUND

Autoimmune diseases are multifactorial with environmental and heritable factors. Autoimmunity reflects an altered immune status, therefore the presence of more than one disorder is not uncommon. The coexistence of three or more autoimmune diseases in a patient constitutes multiple autoimmune syndrome (MAS). This is an interesting case of a middle-aged female who had celiac disease, primary biliary cholangitis, autoimmune hepatitis and evolving CREST (Calcinosis, Rhaynaud's phenomenon, Esophageal dysmotility, Sclerodactyly and Telangiectasia) syndrome.

CASE REPORT

Fifty years old female patient presented with generalized fatigue, fever, weight loss, vertigo and constipation. She was a diagnosed case of celiac disease, and responded well to glutenfree diet. Family history was unremarkable for any autoimmune disorder. Laboratory workup showed normal complete blood counts, markedly elevated transaminases and alkaline phosphates. Her antinuclear antibodies (ANA) test was strongly positive (>1:320) and showed an anti-centromere pattern. Anti-extractable nuclear antibody(ENA) assay showed anti-mitochondrial and anti- CENP B antibodies. Liver biopsy revealed overlap syndrome (primary biliary cholangitis and autoimmune hepatitis). This patient had celiac disease, primary biliary cholangitis and autoimmune hepatitis. Extensive immunological workup unexpectedly revealed the presence of anti-centromere protein B (anti-CENP B) antibodies which are strongly associated with CREST syndrome. Clinical re-evaluation of the patient gave clues of the evolving CREST syndrome. This case report highlights the importance of adequate immunological investigations in conjunction with clinical information for adequate patient management to achieve favorable consequences in the future.

CONCLUSION

Patients suffering from an autoimmune disease need special attention as multiple immune- mediated disorders may be present simultaneously or sequentially during the course of the disease process. MAS patients are at a higher risk of acquiring infections and tumor development due to prolonged use of immunosuppressants. These patients need close surveillance for the development of another autoimmune disease, so as to control the current disease and to prevent future complications. This case report emphasizes the importance of a multidisciplinary team approach including an immunologist who may facilitate a better understanding of disorders related to the breakdown of immune tolerance.

Evaluation of a novel extended automated particle-based multi-analyte assay for the detection of autoantibodies in the diagnosis of primary biliary cholangitis

Background

Anti-mitochondrial autoantibodies (AMA) detected by indirect immunofluorescence (IIF) on rodent tissues are the diagnostic marker of primary biliary cholangitis (PBC). However, up to 15% of patients with PBC are AMA-negative by IIF. In the effort to close the serological gap and improve the diagnostic sensitivity of PBC testing, recently, novel autoantibodies specific for PBC, such as kelch-like 12 (KLHL12, KLp epitope) and hexokinase 1 (HK1) have been described. In this study, we evaluated the autoantibody profile in a large cohort of PBC patients and in patients with other liver disease, including anti-HK1 and anti-KLp autoantibodies.

Methods

Sera of 194 PBC patients (126 AMA-IIF-positive and 68 AMA-IIF-negative) and 138 disease controls were tested for a panel of PBC-specific antibodies (MIT3, sp100, gp210, HK1, KLp) using a new automated particle-based multi-analyte technology (PMAT) assay on the Aptiva instrument (Inova).

Results

Selecting a cutoff yielding a specificity of >95% for all the markers, the sensitivity for anti-MIT3, anti-sp100, anti-gp210, anti-HK1 and anti-KLp in the PBC AMA-IIF-negative cohort was 20.6%, 16.2%, 23.5%, 22.0%, 17.6 and 13.2%, respectively. Six out of the 68 (8.8%) AMA-IIF negative sera were positive for anti-HK1 or anti-KLp alone. Using these new markers in addition to anti-MIT3, anti-sp100 and anti-gp210, the overall sensitivity in this cohort of AMA-IIF-negative patients increased from 53% to 61.8%, reducing the serological gap in AMA-negative PBC patients.

Conclusions

PBC antibody profiling, made possible by the new Aptiva-PMAT technology, allows recognition of a higher number of AMA-negative PBC patients than conventional immunoassays and may represent a useful tool to evaluate the prognostic significance of autoantibody association in PBC patients.