Late Breaking Abstract-17-oxo-DHA inhibits the NLRP3 inflammasome downstream of mitochondrial ROS and ERK pathway

17-oxo-DHA is an anti-inflammatory derivative of the omega-3 fatty acid docosahexaenoic acid. When administered in combination with fluticasone propionate (FP), 17-oxo-DHA displays additive anti-inflammatory effects by acting via transcriptional and post-transcriptional mechanisms. In particular, 17-oxo-DHA, but not FP, inhibits the NLRP3 inflammasome. Mitochondrial reactive oxygen species (mROS) are both a trigger and a downstream effect of inflammasome activation. ROS-related PI3K-AKT and ERK signaling have been involved in inflammasome activation. Herein we investigated whether inflammasome inhibition by 17-oxo-DHA was mediated by an effect on mROS generation, as well as by modulation of AKT and ERK signaling. Lipopolysaccharide-primed or unprimed THP1 macrophages were treated with nigericin. The release of IL-1? and IL-18 was significantly higher in primed compared to unprimed cells. Nigericin induced AKT and ERK phosphorylation as well as mROS in unprimed and primed cells. In the latter, higher mROS was in part associated with increased cell death probably linked to stronger inflammasome activation. 17-oxo-DHA inhibited IL-1? and IL-18 release in primed and unprimed cells and reduced mROS associated with cell death. 17-oxo-DHA inhibited AKT but not ERK phosphorylation. However, inhibition of AKT phosphorylation by wortmannin did not reduce IL-1? and IL-18 release thus excluding a role for this pathway in inflammasome activation. On the contrary, inhibition of ERK phosphorylation reduced IL-1? and IL-18 release. Overall, our data support that 17-oxo-DHA inhibits the NLRP3 inflammasome downstream of mROS and ERK pathway and reduces inflammasome-dependent mitochondrial damage.