Serum concentrations of IL-1β and IL-18 in gout patients out of flare are not connected to cardiovascular alterations

Abstract

Background: In the literature there are reports that the key interleukins, IL-1β and IL-18, for the initiation and maintenance of gouty inflammation are associated with renal and cardiovascular disorders. They have a major regulatory function in the innate immune response and in vascular pathology. Objective: We aimed to determine serum levels of IL-1β and IL-18 in controls with inactivated osteoarthritis, patients with asymptomatic hyperuricemia, gouty arthritis without tophi subjects and gouty tophi individuals out of flare, and to establish whether their serum concentrations are connected to ultrasound alterations of the kidneys and heart. Materials and methods: The study is cross-sectional in design. A total of 83 consecutive patients were included: 18 with inactivated osteoarthritis, 29 with asymptomatic hyperuricemia, 22 gouty arthritis without tophi and 18 gouty tophi individuals out of flare. Serum interleukin concentrations were determined by enzyme-linked immunosorbent assay (ELISA) with Human IL-1β and IL-18 ELISA kits (Platinum, eBioscience, Vienna, Austria). By applying ultrasound were measured: renal resistive index (RRI) with 3.5 MHz transducer working with pulse Doppler frequency of 2.5 MHz and left ventricular mass index (LVMi), determined with 2.5 MHz transducer Phased Array. Data were analyzed by One-Sample Kolmogorov-Smirnov, ANOVA, Tukey HSD, Kruskal Wallis, Mann-Whitney and Fisher’s exact test. Correlational analyzes were performed by using the Spearman correlation coefficient. Results: In gouty tophi subjects serum IL-1β level was undetectable compared to the other three groups, (p<0.001). The serum concentration of IL-18 was comparable across the groups, (p=0.154). Given that the level of IL-1β was undetectable in gouty tophi patients, a correlation analysis in this group with serum uric acid concentration, RRI and LVMi was not performed. In the remaining three groups, which had values of IL-1β above zero, we did not detect an association with the above mentioned parameters. No correlation was found between IL-18 concentration and serum uric acid, RRI and LVMi in the groups. Conclusion: We suggest that serum IL-1β and IL-18 levels do not reflect the severity of the disease and cardiovascular risk in the examined gout patients.