Association between activity and genotypes of paraoxonase1 L55M (rs854560) increases the disease activity of rheumatoid arthritis through oxidative stress

Rheumatoid arthritis (RA) is considered as a long-term autoimmune disorder. Gene polymorphism and oxidative stress might be involved in the pathogenesis of the disease. We aimed to determine the association between PON-1L55M polymorphism and its effects on inflammatory markers such as anti-cytroline circulated-peptide (CCP)-antibodies, C-reactive protein (CRP), neopterin serum concentration, arylesterase (ARE) and butyrylcholinesterase (BuChE) activities and total-antioxidant-capacity (TAC) level with the activity of disease in RA patients. This case-control study consisted of 419 RA patients and 397 gender–age-matched unrelated healthy controls from the west of Iran. PON1-L55M polymorphism was detected by real-time-PCR. The TAC level, serum BuChE and ARE activities were determined spectrophotometrically. Anti-CCP-antibody and CRP were measured by ELISA and neopterin level was detected by HPLC. The PON1-M55 allele was associated with increased risk of the RA in cases with moderate or high activity (OR = 1.43, p = 0.023) and also in cases with the presence of anti-CCP antibody (OR = 1.51, p = 0.009). Synergistic effects of PON1 M55 and Q192 alleles resulted in 2.14 times (p = 0.021) increased disease activity among RA patients with moderate or high activity of the disease. RA patients carried both M (PON1 L55M) and Q alleles (PON1Q192R) had higher concentrations of neopterin (p = 0.003), anti-CCP-antibody (p < 0.001) and CRP (p = 0.026) and significantly lower TAC level (p < 0.001) and ARE (p < 0.001) activity compared to controls. The current study suggests there might be a relationship between genetic and activity of PON. Also, the PON1L55M and PON1Q192R could act in synergy to increase the risk of RA and enhance the level of oxidative stress markers.