Assessment of the association between TNIP1 polymorphism with clinical features and risk of systemic lupus erythematosus

Objective: Over the past decades, TNIP1 has been identified as a strong risk locus in multiple genome-wide association studies (GWAS), spanning multiple populations and various autoimmune diseases. TNIP1 is a polyubiquitin-binding protein that works as a physiological inhibitor of NF-κB and maintains immune homeostasis. Some studies have confirmed that TNIP1 is downregulated in autoimmune diseases such as rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE). In the current study, for the first time, we evaluated the possible association between rs6889239 polymorphism in the TNIP1 gene with the risk and clinical characteristics of RA and SLE in the Iranian population.

Method: In this case-control study, 115 patients with RA, 115 patients with SLE, and 115 unrelated healthy subjects were enrolled to estimate rs6889239 genotypes with real-time PCR high resolution melting (HRM) method.

Results: Our results demonstrated considerable associations between CC genotype and C allele of rs6889239 with augmented risk of SLE (OR for CC genotype= 2.23; 95%CI [1.175-4.307], OR for C allele= 1.84; 95%CI [1.254-2.720]). However, there was an insignificant association between genotypes and allele frequencies of rs6889239 with the occurrence risk of RA in the population under study (p > 0.05). Additionally, stratification analysis specified that the C allele in rs6889239 was linked with the incidence of renal involvement in SLE patients and lower age of onset in the RA group (p < 0.05).

Conclusion: These findings propose a significant association between TNIP1 polymorphism and higher risk of SLE and some clinical characteristics of RA and SLE.