Analysis of TNFSF13B polymorphisms and BAFF expression in rheumatoid arthritis and primary Sjogren's syndrome patients

Background: The increased expression of B cell-activating factor (BAIT) has been linked to au toantibody production in au toimmune diseases (ADs). The aim of this study was to investigate the association among TNFSFI3B gene (OMIM: 603969) single nucleotide polymorphisms (SNPs), TNFSF13B mRNA, and soluble BAFF (sBAFF) expression in patients with rheumatoid arthritis (RA) and primary Sjogren's syndrome (pSS). The diagnostic value of sBAFF also was evaluated by the area under the curve (AUC) of receiver operating characteristic or receptor (ROC) curves. Methods: Genotypes of the TNFSFI3B rs9514827 (-2841T> C), rs1041569 (-2701 A> T) and rs9514828 (-871 C> T) SNPs were determined by PCR-RFLP assay. TNFSFI3B mRNA and sBAFF expression were performed by RT-OCR and ELISA, respectively. The study included 320 RA patients, 101 pSS patients, and 309 healthy subjects (HS). Results: The rs9514828 T allele and the TAT haplotype were associated with an increased risk to develop RA. In both ADs, the TNFSFI3B mRNA levels were increased in comparison with I IS. The rs9514828 (-871 C> T) polymorphism was associated with increased gene expression in RA patients. Also, sBAFF levels were higher in both ADs, however pSS patients showed the highest sBAFF levels. sBAFF showed higher diagnostic performance for pSS with an AUC of 0.968, with a similar accuracy of anti-SSA/Ro antibody diagnosis (AUC = 0.974). Conclusions: Our findings demonstrate that the TNFSFI3B rs9514828 (-871 C> T) polymorphism is a risk factor for RA in the western Mexican population. sBAFF levels may be a potential diagnosis biomarker in pSS.