Oleic acid suppresses NLRP3 inflammasome activation to prevent dermal macrophage death and limit imiquimod-induced psoriasis

Abstract

Psoriasis is associated with altered lipid metabolism, including reduced expression of fatty acid metabolism genes and decreased circulating oleic acid. Here we report that oral oleic acid supplementation normalized serum oleic acid levels and protected from skin thickening and epidermal hyperplasia in a imiquimod mice model of psoriasis. These effects were associated with preserved skin-resident macrophage numbers and reduced expression of key psoriasis-associated inflammatory markers. Mechanistically, imiquimod induces dermal macrophage death via NLRP3/caspase-1 inflammasome activation, while adoptive transfer of dermal macrophages attenuates psoriasiform inflammation. Oleic acid rescued macrophages from imiquimod and nigericin-induced death in vitro by suppressing NF-{kappa}B and NLRP3/caspase-1 signaling, lowering IL-1{beta} and reactive oxygen species production, and restoring mitochondrial homeostasis, independently of TLR7. Together, our results position dermal macrophage survival as a previously unrecognized checkpoint in psoriasiform inflammation, and suggest that restoring lipid metabolic fitness, rather than solely targeting downstream inflammatory mediators, may offer an additional mechanism-based strategy to limit tissue- damaging inflammation.