Dermis resident macrophages orchestrate localized ILC2 eosinophil circuitries to promote non-healing cutaneous...

Tissue-resident macrophages are critical for tissue homeostasis and repair. We previously showed that dermis-resident macrophages produce CCL24 which mediates their interaction with IL-4⁺ eosinophils, required to maintain their M2-like properties in the T_H1 environment of the Leishmania major infected skin. Here, we show that thymic stromal lymphopoietin (TSLP) and IL-5⁺ type 2 innate lymphoid cells are also required to maintain dermis-resident macrophages and promote infection. Single cell RNA sequencing reveals the dermis-resident macrophages as the sole source of TSLP and CCL24. Generation of Ccl24-cre mice permits specific labeling of dermis-resident macrophages and interstitial macrophages from other organs. Selective ablation of TSLP in dermis-resident macrophages reduces the numbers of IL-5⁺ type 2 innate lymphoid cells, eosinophils and dermis-resident macrophages, and ameliorates infection. Our findings demonstrate that dermis-resident macrophages are self-maintained as a replicative niche for L. major by orchestrating localized type 2 circuitries with type 2 innate lymphoid cells and eosinophils.