Diabetic Wound Keratinocytes Induce Macrophage JMJD3-Mediated Nlrp3 Expression via IL-1R Signaling

Macrophage (M phi) plasticity is critical for normal wound repair; however, in type 2 diabetic wounds, M phi s persist in a low-grade inflammatory state that prevents the resolution of wound inflammation. Increased NLRP3 inflammasome activity has been shown in diabetic wound M phi s; however, the molecular mechanisms regulating NLRP3 expression and activity are unclear. Here, we identified that diabetic wound keratinocytes induce Nlrp3 gene expression in wound M phi s through IL-1 receptor-mediated signaling, resulting in enhanced inflammasome activation in the presence of pathogen-associated molecular patterns and damage-associated molecular patterns. We found that IL-1 alpha is increased in human and murine wound diabetic keratinocytes compared with nondiabetic controls and directly induces M phi Nlrp3 expression through IL-1 receptor signaling. Mechanistically, we report that the histone demethylase, JMJD3, is increased in wound M phi s late post-injury and is induced by IL-1 alpha from diabetic wound keratinocytes, resulting in Nlrp3 transcriptional activation through an H3K27me3-mediated mechanism. Using genetically engineered mice deficient in JMJD3 in myeloid cells (Jmjd3f/flyz2Cre+), we demonstrate that JMJD3 controls M phi-mediated Nlrp3 expression during diabetic wound healing. Thus, our data suggest a role for keratinocyte-mediated IL-1 alpha/IL-1R signaling in driving enhanced NLRP3 inflammasome activity in wound M phi s. These data also highlight the importance of cell cross-talk in wound tissues and identify JMJD3 and the IL-1R signaling cascade as important upstream therapeutic targets for M phi NLRP3 inflammasome hyperactivity in nonhealing diabetic wounds.