The Function Changes of the Ala348to Thr Polymorphism in the P2X7R Closely Related to the Onset of Gout

Abstract Gout is a common disease of inflammatory arthritis caused by hyperuricemia and the deposition of MSU crystals. Our previous study has shown that ATP action on P2X7R could be the second signal to induce the onset of gouty arthritis. However, the biological function changes of SNPs in the P2X7R, which affect the ATP-P2X7R-IL-1β signaling pathway with high uric acid, remained unknown. To further research P2RX7 gene variant (encoded by the SNP as rs1718119) polymorphism association between the gout susceptibility and the functional effect, 270 patients with gout and 70 hyperuricemia patients without history of gout flare (over 5-years course) were recruited in this study. The current study first time analyzed the genotyping study in genomic DNA samples from gout and hypeluricemia patients, then flow cytometry was used to test the transfected Ala348to Thr mutant in HEK-293T cells. Expression levels of IL-1β, NLRP3, ASC, caspase-1 mRNA in THP-1 cells were analyzed by quantitative real-time polymerase chain reaction. Expression levels of IL-1β were measured by enzyme-linked immunosorbent assay. The gout-sensitivity allele at rs1718119 was A. The AA and AG genotypes exhibited a higher risk of gout and the gout-sensitivity allele at rs1718119 was A. Moreover, Ala348to Thr increased P2X7-dependent ethidium+ bromide uptake. What’s more, Ala348 to Thr significantly up-regulated the serum and mRNA levels of IL-1β compared with wild type (P=0.0007;P=0.0334,respectively). Expression levels of NLRP3 mRNA in cells with Ala348 to Thr also showed a higher level than wild type(p=0.0003). However, no statistical significance were found in the mRNA expression of ASC and caspase-1 between Ala348to Thr and wild type in all three groups(P＞0.05). Our study revealed that the biological function changes of one SNP (rs1718119) mutation affected the ATP-P2X7R-IL-IL-1β signaling pathway with high uric acid. And, both rs1718119 was dominant gene. The genetic variability of the P2X7R rs1718119 gene might, in part, be associated with susceptibility for gout onset.