RÉSUMÉ
Antitumour necrosis factor-alpha (TNF-α) therapy is used as a clinical intervention for rheumatoid arthritis (RA) but differences exist in response to the treatment which makes the candidature of the screening of TNF-α alteration(s) at genetic and expression levels an important agenda prior to treatment. This study aims to determine the associative role of TNF-α –308G/A polymorphism and differential expression of TNF-α in the pathogenesis of RA. A case–control study where a total of 126 RA patients were enrolled based on ACR-EULAR (2010) criteria, along with 160 community matched age and sex controls over a period of three years. The differential expression level of TNF-α mRNA and protein level was studied and TNF-α –308G/A polymorphism was screened by T-ARMS PCR assay. All statistical analysis was performed using SPSS software. mRNA expression level of TNF-α was upregulated in RA cases (avg. 15.85 ± 9.52 fold) compared to control. TNF-α protein level was found to be higher in RA cases (28.62±7.17 pg/mL) compared to control (23.14±6.91 pg/mL). TNF-α –308 variant GA genotype was higher in RA (46.03%) than in control (25%). The presence of TNF-α –308 variant A allele was associated with increased risk of RA susceptibility (odds ratio (OR) = 2.559 at 95% confidence interval (CI), P< 0.001) but not severity (OR = 1.617 at 95% CI, P = 0.571). The presence of –308 variant genotype was associated with a higher TNF-α mRNA and protein expression. The presence of TNF-α –308A allele is associated with increased risk of RA susceptibility and differential TNF-α expression, and has prognostic significance. Association of higher TNF-α pro-inflammatory cytokine levels with northeast Indian patients makes them suitable subjects for anti-TNF-α therapy.