Thrombocytes-derived Dickkopf1 promotes wound-healing macrophage polarization
Immune responses are crucial to maintaining tissue homeostasis upon tissue injury. Upon various types of challenges, macrophages play a central role in regulating inflammation and tissue repair processes. While an immunomodulatory role of Wnt antagonist Dickkopf1 (DKK1) has been implicated, the role of Wnt antagonist DKK1 in regulating macrophage polarization in inflammation and the tissue repair process remains elusive. Here we found that DKK1 induces differential gene expression profiles from type 2-cytokine-activated macrophages to promote inflammation and tissue repair. Importantly, DKK1 induced pro-inflammatory and pro-resolving gene expressions via JNK (c-jun N-terminal kinase) in macrophages. Furthermore, DKK1 potentiated IL-13-mediated macrophage polarization and activation. Co-inhibition of JNK and STAT6 markedly decreased pro-inflammatory and pro-resolving gene expressions by DKK1 and IL-13. Interestingly, thrombocyte-specific deletion of DKK1 in mice reduced monocyte-derived macrophages in the acute sterile bleomycin (BLM)-induced lung injury model, suggesting that thrombocytes communicate with macrophages via DKK1 to orchestrate inflammation-induced injury repair process. Taken together, our study demonstrates DKK1's role as a key regulatory role in macrophage polarization in the injury-induced inflammation and repair process. Overall design: Three biological replicates were analyzed for each of 4 conditions BMDMs: untreated BMDMs: IL-13 stimulation for 24 hr BMDMs: DKK1 stimulation for 24 hr BMDMs: IL-13+DKK1 stimulation for 24 hr