Spectrum of autoantibodies for gastrointestinal autoimmune diseases in systemic lupus erythematosus patients

Background Organ-specific autoimmune diseases may appear in patients with systemic lupus erythematosus (SLE). Gastrointestinal symptoms are well documented in SLE and may be similar to those related to autoimmune gastrointestinal diseases. Objective Our aim was to search for gastrointestinal organ-specific autoantibodies in 194 patients with systemic lupus and 103 healthy controls from Southern Brazil. Methods Anti-endomysium antibodies (IgA-EmA), anti-gastric parietal cells (GPC) antibodies, anti-smooth muscle antibodies (ASMA), anti-mitochondrial antibodies (AMA) and anti-LKM-1 (liver-kidney microsomal) were searched for using indirect immunofluorescence in the sera of patients and controls. Results The total positivity of antibodies in SLE patients was 14.4% (28/194) and differed significantly from healthy individuals (0.97%; p<0.001). IgA-EmA was more common in lupus patients than in controls (11/194; p=0.009), and one of these patients had dermatitis herpetiformis. Clinical association revealed that IgA-EmA was more common in SLE patients with discoid lesions. The frequency of anti-GPC (p=0.10), ASMA (p=0.16) and AMA (p=0.55) did not differ significantly between groups. No patient presented LKM-1 autoantibodies. One patient presenting anti-GPC was diagnosed with atrophic gastritis and pernicious anemia. Conclusion Only IgA-EmA was significantly associated with lupus and with the presence of discoid lesions. Until now, no obvious association with celiac disease has been found.