COVID-19 and Immunological Dysregulation: Can Autoantibodies be Useful?

Coronavirus disease 2019 (COVID-19) is often associated with interstitial pneumonia. However, there is insufficient knowledge on the presence of autoimmune serological markers in patients with COVID-19. We analyzed the presence and role of autoantibodies in patients with COVID-19-associated pneumonia. We prospectively studied 33 consecutive patients with COVID-19, 31 (94%) of whom had interstitial pneumonia, and 25 age-matched and sex-matched patients with fever and/or pneumonia with etiologies other than COVID-19 as the pathological control group. All patients were tested for the presence of antinuclear antibodies (ANAs), anti-antiphospholipid antibodies, and anti-cytoplasmic neutrophil antibodies (ANCAs). Clinical, biochemical, and radiological parameters were also collected. Fifteen of 33 patients (45%) tested positive for at least one autoantibody, including 11 who tested positive for ANAs (33%), 8 who tested positive for anti-cardiolipin antibodies (immunoglobulin (Ig)G and/or IgM; 24%), and 3 who tested positive for anti-ß2-glycoprotein antibodies (IgG and/or IgM; 9%). ANCA reactivity was not detected in any patient. Patients that tested positive for auto-antibodies had a significantly more severe prognosis than other patients did: 6 of 15 patients (40%) with auto-antibodies died due to COVID-19 complications during hospitalization, whereas only 1 of 18 patients (5.5%) who did not have auto-antibodies died (P = 0.03). Patients with poor prognosis (death due to COVID-19 complications) had a significantly higher respiratory rate at admission (23 breaths per minute vs. 17 breaths per minute; P = 0.03) and a higher frequency of auto-antibodies (86% vs. 27%; P = 0.008). In conclusion, auto-antibodies are frequently detected in patients with COVID-19 possibly reflecting a pathogenetic role of immune dysregulation. However, given the small number of patients, the association of auto-antibodies with an unfavorable prognosis requires further multicenter studies.

Antiendomysial and antihuman recombinant tissue transglutaminase antibodies in the diagnosis of coeliac disease: a biopsy-proven European multicentre study.

OBJECTIVE: To investigate the value of serum antitissue transglutaminase IgA antibodies (IgA-TTG) and IgA antiendomysial antibodies (IgA-EMA) in the diagnosis of coeliac disease in cohorts from different geographical areas in Europe. The setting allowed a further comparison between the antibody results and the conventional small-intestinal histology. METHODS: A total of 144 cases with coeliac disease [median age 19.5 years (range 0.9-81.4)], and 127 disease controls [median age 29.2 years (range 0.5-79.0)], were recruited, on the basis of biopsy, from 13 centres in nine countries. All biopsy specimens were re-evaluated and classified blindly a second time by two investigators. IgA-TTG were determined by ELISA with human recombinant antigen and IgA-EMA by an immunofluorescence test with human umbilical cord as antigen. RESULTS: The quality of the biopsy specimens was not acceptable in 29 (10.7%) of 271 cases and a reliable judgement could not be made, mainly due to poor orientation of the samples. The primary clinical diagnosis and the second classification of the biopsy specimens were divergent in nine cases, and one patient was initially enrolled in the wrong group. Thus, 126 coeliac patients and 106 controls, verified by biopsy, remained for final analysis. The sensitivity of IgA-TTG was 94% and IgA-EMA 89%, the specificity was 99% and 98%, respectively. CONCLUSIONS: Serum IgA-TTG measurement is effective and at least as good as IgA-EMA in the identification of coeliac disease. Due to a high percentage of poor histological specimens, the diagnosis of coeliac disease should not depend only on biopsy, but in addition the clinical picture and serology should be considered.

Celiac disease in autoimmune cholestatic liver disorders.

OBJECTIVES: In this study, serological screening for celiac disease (CD) was performed in patients with autoimmune cholestasis to define the prevalence of such an association and to evaluate the impact of gluten withdrawal on liver disease associated with gluten sensitive enteropathy. METHODS: Immunoglobulin A endomysial, human and guinea pig tissue transglutaminase antibodies, and immunoglobulin A and G gliadin antibodies were sought in 255 patients with primary biliary cirrhosis, autoimmune cholangitis, and primary sclerosing cholangitis. RESULTS: Immunoglobulin A endomysial and human tissue transglutaminase antibodies were positive in nine patients (seven primary biliary cirrhosis, one autoimmune cholangitis, and one primary sclerosing cholangitis), whose duodenal biopsy results showed villous atrophy consistent with CD. Two of these patients had a malabsorption syndrome, and one had iron-deficiency anemia. Clinical and biochemical signs of cholestasis did not improve after gluten withdrawal in the three patients with severe liver disease. A longer follow-up of the six celiac patients with mild liver damage is needed to clarify whether gluten restriction can contribute to slow down the progression of liver disease. CONCLUSIONS: The high prevalence of CD (3.5%) in autoimmune cholestasis suggests that serological screening for CD should be routinely performed in such patients by immunoglobulin A endomysial or human tissue transglutaminase antibodies.

Smooth muscle antibodies and type 1 autoimmune hepatitis.

BACKGROUND/AIM: Smooth muscle antibodies (SMA) characterize type 1 autoimmune hepatitis. Our aim was to evaluate sensitivity and specificity of different immunofluorescence substrates for the detection of SMA. METHODS: Sera from 55 patients with type 1 AIH 20 with primary biliary cirrhosis, 20 with HCV-related chronic hepatitis and 25 blood donors were studied for SMA and anti-microfilaments reactivity by immunofluorescence on rat tissue sections, cultured fibroblasts and commercially available HEp-2 cells (collectively revealing the so called anti-actin pattern), and for the XR1 system by counterimmunoelectrophoresis. SMA was classified on the basis of its immunofluorescence pattern (V--vessels, G--glomerular, T--tubular). As further control group, we studied 26 patients with a diagnosis other than AIH, selected on the basis of a SMA-non-T/XR1 positivity. RESULTS: In patients with AIH the SMA-T pattern on rodent tissue, and anti-MF on fibroblasts and on HEp-2 cells were present in 80, 82 and 80%, respectively. Five out of 11 SMA-non T positive AIH patients were anti-MF positive. None of the pathological and healthy controls was positive for SMA-T or anti-MF reactivity. XR1 system was present in 84% of AIH patients and in 5% of pathological controls (p = 0.01). Two out of 26 SMA-non-T/XR1 positive sera were positive for anti-MF by fibroblasts and HEp-2 cells. A significant correlation was found between SMA-T pattern and anti-MF reactivity; no correlation was found between XR1 system and SMA-T pattern or anti-MF reactivity. CONCLUSIONS: SMA-T pattern is highly sensitive and specific first diagnostic test for type 1 AIH; anti-MF can be used as additional tool for the diagnosis, particularly when, despite the absence of the SMA-T pattern, AIH is strongly suspected.