Anti-TRIM21 antibody seropositivity is related to B-cell abnormalities in systemic lupus erythematosus

Abstract

Abstract Background/Purpose TRIM21 is one of the autoantigens which react with anti-SS-A antibody (Ab). Previous studies have shown that TRIM21 dysfunction promotes aberrant B-cell differentiation in systemic lupus erythematosus (SLE). Here we examined the relationship between anti-TRIM21 Ab and clinical and immunological characteristics in SLE patients. Methods Twenty-seven patients with SLE before immunosuppressive therapies and four healthy controls (HC) were enrolled in the study. Serum anti-TRIM21 Ab levels were measured using enzyme-linked immunosorbent assays. The serum levels of cytokines and immunoglobulins were measured using cytometer beads arrays. The protein expression levels of TRIM21 in peripheral blood mononuclear cells (PBMCs) were evaluated by western blotting. Results Nineteen and 8 patients showed seronegativity and seropositivity for anti-TRIM21 Ab, respectively. There were no significant differences in the background parameters, including SLE activity and laboratory data. The serum levels of interferon (IFN)-α2 were significantly higher in patients with anti-TRIM21 Ab as compared with those without anti-TRIM21 Ab (p = 0.03). The levels of IgG1, IgG2, and IgA were significantly higher in patients with anti-TRIM21 Ab as compared with those without anti-TRIM21 Ab (p = 0.005, 0.04 and 0.01, respectively). The PBMCs of patients with anti-TRIM21 Ab showed a significantly higher expression of TRIM21 protein as compared with those of patients without anti-TRIM21 Ab. Conclusion Anti-TRIM21 Ab seropositivity is related to B-cell abnormalities and type I IFN overproduction in SLE patients, which may be due to the inhibitory effect of anti-TRIM21 Ab on TRIM21 functions.