Auto-antibodies in autoimmune hepatitis: anti-smooth muscle antibodies (ASMA)

Non-organ-specific autoantibodies with unspecific patterns are a frequent para-infectious feature of chronic hepatitis D

Infections with hepatotropic viruses are associated with various immune phenomena. Hepatitis D virus (HDV) causes the most severe form of viral hepatitis. However, few recent data are available on non-disease-specific and non-organ-specific antibody (NOSA) titers and immunoglobulin G (IgG) levels in chronic hepatitis D (CHD) patients. Here, we examined the NOSA titers and IgG levels of 40 patients with CHD and different disease courses and compared them to 70 patients with chronic hepatitis B (CHB) infection. 43% of CHD patients had previously undergone treatment with pegylated interferon-α (IFN-α). The antibody display of 46 untreated patients diagnosed with autoimmune hepatitis (AIH) was used as a reference. The frequency of elevated NOSA titers (CHD 69% vs. CHB 43%, p < 0.01), and the median IgG levels (CHD 16.9 g/L vs. CHB 12.7 g/L, p < 0.01) were significantly higher in CHD patients than in patients with CHB, and highest in patients with AIH (96%, 19.5 g/L). Also, the antinuclear antibody pattern was homogeneous in many patients with AIH and unspecific in patients with viral hepatitis. Additionally, f-actin autoantibodies were only detectable in patients with AIH (39% of SMA). In CHD patients, IgG levels correlated with higher HDV viral loads, transaminases, and liver stiffness values. IgG levels and NOSA were similar in CHD patients irrespective of a previous IFN-α treatment. In summary, autoantibodies with an unspecific pattern are frequently detected in CHD patients with unclear clinical relevance.

Working Algorithms and Detection Methods of Autoantibodies in Autoimmune Liver Disease: A Nationwide Study

Autoantibody detection is the cornerstone of autoimmune liver diseases (AILD) diagnosis. Standardisation of working algorithms among autoimmunity laboratories, as well as being aware of the sensitivity and specificity of various commercial techniques in daily practice, are still necessary. The aim of this nationwide study is to report the results of the 2020 Autoimmunity Workshop organised by the Autoimmunity Group of the Spanish Society of Immunology and to provide useful information to clinicians and laboratory specialists to improve the management of autoantibody detection in AILD diagnoses. Serum samples from 17 patients with liver diseases were provided by the organisers of the 2020 Autoimmunity Workshop and were subsequently analysed by the 40 participating laboratories. Each laboratory used different techniques for the detection of autoantibodies in each patients’ serum sample, according to their working algorithm. Thus, almost 680 total complete patient reports were obtained, and the number of results from different autoantibody detection techniques was >3000. Up to eight different working algorithms were employed, including indirect immunofluorescence assays (IFA) and antigen-specific techniques (AgST). The IFA of HEp-2 cells was more sensitive than IFA of rat triple tissue for the study of anti-nuclear autoantibodies (ANA) associated with AILD. The IFA of a human neutrophil study for the analysis of anti-neutrophil cytoplasmic autoantibodies was not carried out systemically in all patients, or by all laboratories. AgSTs were the most sensitive methods for the detection of anti-smooth muscle/F-actin, soluble liver antigen, liver cytosol-1, M2-mitochondrial autoantibodies, and ANA associated with primary biliary cholangitis. The main differences in AMA detection were due to patients with autoantibodies against the non-dominant epitope of pyruvate dehydrogenase complex. Given that they are complementary, IFA and AgST should be performed in parallel. If there is high suspicion of AILD, AgST should always be performed.

Brain Atrophy, Anti-Smooth Muscle Antibody and Cognitive Impairment: An Association Study

Cortical atrophy, neuronal loss, beta-amyloid deposition, neuritic plaques, and neurofibrillary tangles are neuropathological key features in the Alzheimer's disease (AD). Antibodies against beta-amyloid, neurotransmitters, microvascular endothelium components and microglial cells have been detected in AD serum suggesting that AD could be another autoimmune disease and provides a link between vascular pathology, endothelium dysfunction and neuronal cells death. Aim of the present study was to evaluate the association between autoantibody profile and cognitive impairment in geriatric patients, accounting for ApoE genotype as a potential confounding factor. Three hundred and forty-four geriatric patients, attending the clinic for the cognitive decline, underwent a biochemical and immunological profile, chest X-ray, cerebral computed tomography scan and complete cognitive evaluation. All patients were also screened for the ApoE genotype. A significantly higher prevalence of Anti-Smooth Muscle Antibody (ASMA) positivity was found in 89/204 (43.63%) patients with diagnosed neuroradiological signs of cerebral atrophy compared with 15/140 (10.71%) patients without the condition (p<0.001). Multivariable logistic model evidenced that such association was independent of patient's age, gender and Mini-Mental State Examination (OR=8.25, 95%CI: 4.26-15.99) and achieved a good discriminatory power (c-statistic=0.783). Results were also independent of ApoE genotype, which resulted not associated both with the presence of brain atrophy and with the presence of ASMA positivity. Our results shows a strong association between brain atrophy and ASMA positivity and are consistent with several studies that focused attention on the mechanisms of endothelial immune response in the development of dementia.

Antibodies to soluble liver antigen in patients with various liver diseases: a multicentre study

BACKGROUND

Antibodies to soluble liver antigen (anti-SLA) are specific serological markers of autoimmune hepatitis (AIH). The clinical significance and frequency of anti-SLA have never been reported among AIH patients from Italy and Turkey. To retrospectively assess the estimated prevalence, sensitivity, specificity and clinical significance of anti-SLA in AIH and various liver diseases.

METHODS

A total of 986 patients who had been tested for serum anti-SLA were included in study. The presence of anti-SLA was detected using recombinant enzyme linked immunosorbent assay and immuno-blot. The general characteristics and outcome of patients were obtained from their medical records.

RESULTS

Antibodies to SLA were found in 30 (3%) of 986 patients. Of these, 27 (90%) had AIH and its variants, whereas the remaining three (10%) had primary biliary cirrhosis. The prevalence of anti-SLA was 9% in AIH patients from Italy and 15% in patients from Turkey. The specificity of these antibodies was 99.5%, whereas sensitivity was 11%. The positive predictive and negative predictive values were 90% and 77.5% respectively (95% confidence interval). Biochemical remission was achieved in 90% of anti-SLA positive AIH patients, but relapse after immunosuppressive withdrawal or during maintenance therapy was observed in 53% of the patients.

CONCLUSIONS

Seropositivity for anti-SLA occurs at similar frequencies in AIH patients from different geographical regions and ethnic groups. The sensitivity of anti-SLA is low, but it has high specificity for AIH. Additional studies are necessary to prove clinical significance of anti-SLA in AIH.