Systemic lupus erythematosus (SLE) is an autoimmune disease with complex underlying mechanisms that have not been fully elucidated. Tumor necrosis factor-α induces protein 3 (TNFAIP3) has been identified as an SLE susceptibility gene. This study aimed to investigate the association between TNFAIP3 levels in peripheral blood mononuclear cells (PBMCs), TNFAIP3 single nucleotide polymorphisms (SNPs), and SLE genetic susceptibility. The mRNA expression level of the TNFAIP3 and the concentration of A20 protein were significantly reduced and negatively correlated with disease activity in patients with active SLE. The C allele of rs377482653 was positively correlated with SLE susceptibility (T vs C: OR = 1.74, 95 %CI: 1.09-2.78, p = 0.02). There were no significant differences in the allele frequencies of rs582757 (p = 0.60), rs583522 (p = 0.40) and rs10499194 (p = 0.38) between SLE and healthy controls. Individuals with the rs377482653 C allele and CT genotype were more likely to develop arthritis (C: OR = 1.94, 95 %CI: 1.03-3.63, p = 0.04
CT: OR = 2.54, 95 %CI: 1.19-5.43, p = 0.02). Thus, we established that SLE shows a lower expression of TNFAIP3 and that rs377482653 polymorphism is associated with SLE.