NOX4 promotes wear particle-stimulated inflammation and osteolysis by ROS-dependent NLRP3 inflammasome activation

Periprosthetic osteolysis (PIO) induced by wear particles is a major cause of implant failure, yet the underlying molecular mechanisms remain incompletely understood. Oxidative stress and inflammation are key pathological features, but the role of nicotinamide adenine dinucleotide phosphate oxidase 4 (NOX4) in this process is unclear.

This study aimed to investigate the role and mechanism of NOX4 in wear particle-stimulated inflammation and osteolysis, with a focus on the reactive oxygen species (ROS)/NLRP3 inflammasome signaling pathway.

In-vivo and in-vitro PIO models were established using mice and Raw264.7 cells stimulated with cobalt-chromium-molybdenum alloy (Co-Cr-Mo) particles. NOX4 expression, inflammatory factor levels (TNF-α, IL-1β, IL-6), ROS production, and NLRP3 inflammasome activation (NLRP3, ASC, Caspase-1) were examined. The effects of NOX4 silencing, along with NLRP3 and ROS inhibition, were assessed.

Relative to normal mice and control group, the levels of inflammatory factors and NOX4 expression in PIO mice and cobalt-chromium-molybdenum alloy (Co-Cr-Mo)-stimulated Raw264.7 cells were higher. After NOX4 silencing, the levels of inflammatory factors in Raw264.7 cells were lower under situation of Co-Cr-Mo stimulation. The elevated NLRP3 inflammasome activation and ROS level caused by Co-Cr-Mo stimulation were reversed following NOX4 silencing. Co-Cr-Mo elevated the levels of NLRP3, apoptosis-associated speck-like protein containing a CARD (ASC) and Caspase-1 levels, but this effect was reversed after NOX4 silencing. NLRP3 inflammasome inhibitor or ROS inhibitor could reverse the elevated inflammation in Raw264.7 cells under Co-Cr-Mo stimulation.

NOX4 promotes wear particle-induced inflammation and osteolysis by activating the ROS-dependent NLRP3 inflammasome, providing new targets for treating periprosthetic osteolysis.