Diabetic wound keratinocytes induce macrophage JMJD3-mediated Nlrp3 expression via IL-1R signaling

<p dir="ltr"><b>Abstract</b></p><p dir="ltr">Macrophage (Mφ) plasticity is critical for normal wound repair; however, in type 2 diabetic wounds, Mφs persist in a low-grade inflammatory state that prevents the resolution of wound inflammation. Increased NLRP3 inflammasome activity has been shown in diabetic wound Mφs; however, the molecular mechanisms regulating NLRP3 expression and activity are unclear. Here, we identified that diabetic wound keratinocytes induce <i>Nlrp3 </i>gene expression in wound Mφs through IL-1 receptor-mediated signaling, resulting in enhanced inflammasome activation in the presence of PAMPs and DAMPs. We found that IL-1 alpha is increased in human and murine wound diabetic keratinocytes compared to non-diabetic controls and directly induces Mφ <i>Nlrp3</i> expression through IL-1 receptor signaling. Mechanistically, we report that the histone demethylase, JMJD3, is increased in wound Mφs late post-injury and is induced by IL-1 alpha from diabetic wound keratinocytes, resulting in <i>Nlrp3</i> transcriptional activation through an H3K27me3-mediated mechanism. Using genetically engineered mice deficient in JMJD3 in myeloid cells (<i>Jmjd3</i>^fl/fl<i>lyz2</i>^cre+), we demonstrate that JMJD3 controls Mφ-mediated <i>Nlrp3</i> 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 Mφs. These data also highlight the importance of cell crosstalk in wound tissues and identify JMJD3 and the ILR signaling cascade as important upstream therapeutic targets for Mφ NLRP3 inflammasome hyperactivity in nonhealing diabetic wounds.</p><p><br></p><p><br></p><p><br></p><p><br></p><p dir="ltr"><b>Article Highlights</b></p><p dir="ltr">· The molecular mechanism regulating macrophage NLRP3 inflammasome activity in diabetic wounds remains unclear.</p><p dir="ltr">· Diabetic wound keratinocytes induce <i>Nlrp3 </i>gene expression and enhance inflammasome activation in wound Mφs through IL-1 receptor mediated signaling.</p><p dir="ltr">· IL-1 alpha is increased in human and murine wound diabetic keratinocytes compared to non-diabetic controls and directly induces Mφ <i>Nlrp3</i> expression via histone demethylase, JMJD3.</p><p dir="ltr">· JMJD3 controls Mφ-mediated <i>Nlrp3</i> expression during wound healing.</p>