Monosodium urate (MSU) has been shown to promote interleukin-1β (IL-1β) secretion in human monocytes, but the priming signals for NOD-like receptor family pyrin domain containing 3 (NLRP3) inflammasome pathway remains elusive. In this study, we investigated the role of Tumor necrosis factor-alpha (TNF-α) on MSU-mediated IL-1β induction in human neutrophils.
Human neutrophils were stimulated with MSU, in the presence or absence of TNF-α priming. The cellular supernatants were analyzed for IL-1β, IL-18, and caspase-1 by enzyme-linked immunosorbent assay (ELISA) methods. Pro-IL-1β mRNA expressions in human neutrophils were analyzed by real-time PCR method.
TNF-α stimulation induced pro-IL-1β mRNA expression; however, MSU stimulation did not induce pro-IL-1β mRNA expression in human neutrophils. TNF-α alone or MSU stimulation did not result in efficient IL-1β secretion in human neutrophils, whereas in TNF-α-primed neutrophils, MSU stimulation resulted in a marked IL-1β and IL-18 secretion. TNF-α-primed neutrophils secreted cleaved caspase-1 (p20), in response to MSU stimulation.
Our data demonstrate that priming of human neutrophils with TNF-α promotes uric acid-mediated IL-1β secretion in the absence of microbial stimulation. These findings provide insights into the neutrophils-mediated inflammatory processes in gouty arthritis.