Peroxisome-Mediated Metabolism Is Required for Immune Response to Microbial Infection

The innate immune response is critical for animal homeostasis and is conserved from invertebrates to vertebrates. This response depends on specialized cells that recognize, internalize, and destroy microbial invaders through phagocytosis. This is coupled to autonomous or non-autonomous cellular signaling via reactive oxygen species (ROS) and cytokine production. Lipids are known signaling factors in this process, as the acute phase response of macrophages is accompanied by systemic lipid changes that help resolve inflammation. We found that peroxisomes, membrane-enclosed organelles central to lipid metabolism and ROS turnover, were necessary for the engulfment of bacteria by Drosophila and mouse macrophages. Peroxisomes were also required for resolution of bacterial infection through canonical innate immune signaling. Reduced peroxisome function impaired the turnover of the oxidative burst necessary to fight infection. This impaired response to bacterial challenge affected cell and organism survival and revealed a previously unknown requirement for peroxisomes in phagocytosis and innate immunity.