Fluorofenidone inhibits macrophage IL-1β production by suppressing inflammasome activity

Interleukin-1 beta (IL-1β) is a potent pro-inflammatory and pro-fibrotic cytokine that plays an important role in renal fibrosis. Fluorofenidone (AKF-PD) is a novel pyridone agent that exerts a strong renal anti-fibrotic effect. We previously found that administration of AKF-PD could significantly attenuate IL-1β production in vitro and in vivo. However, the underlying mechanism is not fully understood. Here we show that AKF-PD has no effect on the expression of pro-IL-1β in activated mouse macrophages in vitro. Instead, AKF-PD inhibits the inflammasome, lowering caspase-1 levels and thereby decreasing cleavage of pro-IL-1β into IL-1β. AKF-PD was found to block inflammasome activity induced by various signals, including ATP, alum crystals, and Salmonella typhimurium. These results provide a novel mechanistic insight into how AKF-PD exerts its anti-inflammatory and anti-fibrotic activities, and suggest that AKF-PD might block IL-1β production via suppression of inflammasomes in renal fibrosis. In addition, the results suggest that AKF-PD may be of therapeutic potential in other inflammasome-related diseases.