Mannose receptor high, M2 dermal macrophages mediate nonhealing Leishmania major infection in a Th1 immune environment

SH Lee, M Charmoy, A Romano, A Paun… - Journal of Experimental …, 2018 - rupress.org
SH Lee, M Charmoy, A Romano, A Paun, MM Chaves, FO Cope, DA Ralph, DL Sacks
Journal of Experimental Medicine, 2018rupress.org
The origin and functional specialization of dermal macrophages in cutaneous infections
have been little studied. In this paper, we show that a strain of Leishmania major (L. major
Seidman [LmSd]) that produces nonhealing cutaneous lesions in conventionally resistant
C57BL/6 mice was more efficiently taken up by M2-polarized bone marrow (BM)–derived
macrophages (BMDMs) in vitro and by mannose receptor (MR) hi dermal macrophages in
vivo compared with a healing strain (L. major Friedlin V1). Both in steady and in T helper …
The origin and functional specialization of dermal macrophages in cutaneous infections have been little studied. In this paper, we show that a strain of Leishmania major (L. major Seidman [LmSd]) that produces nonhealing cutaneous lesions in conventionally resistant C57BL/6 mice was more efficiently taken up by M2-polarized bone marrow (BM)–derived macrophages (BMDMs) in vitro and by mannose receptor (MR)hi dermal macrophages in vivo compared with a healing strain (L. major Friedlin V1). Both in steady and in T helper type 1 (Th1) cell–driven inflammatory states, the MRhi dermal macrophages showed M2 characteristics. The dermal macrophages were radio resistant and not replaced by monocytes or adult BM-derived cells during infection, but were locally maintained by IL-4 and IL-10. Notably, the favored infection of M2 BMDMs by LmSd in vitro was MR dependent, and genetic deletion of MR or selective depletion of MRhi dermal macrophages by anti–CSF-1 receptor antibody reversed the nonhealing phenotype. We conclude that embryonic-derived, MRhi dermal macrophages are permissive for parasite growth even in a strong Th1-immune environment, and the preferential infection of these cells plays a crucial role in the severity of cutaneous disease.
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