M2-like, dermal macrophages are maintained via IL-4/CCL24–mediated cooperative interaction with eosinophils in cutaneous leishmaniasis

Abstract

infected dermis is not clear. Here, we show that, in infected mice lacking IL-4/13 from eosinophils, dermal TRMs shifted to a proinflammatory state, their numbers declined, and disease was attenuated. Intravital microscopy revealed a rapid infiltration of eosinophils followed by their tight interaction with dermal TRMs. IL-4-stimulated dermal TRMs, in concert with IL-10, produced a large amount of CCL24, which functioned to amplify eosinophil influx and their interaction with dermal TRMs. An intraperitoneal helminth infection model also demonstrated a requirement for eosinophil-derived IL-4 to maintain tissue macrophages through a CCL24-mediated amplification loop. CCL24 secretion was confined to resident macrophages in other tissues, implicating eosinophil-TRM cooperative interactions in diverse inflammatory settings.