Vitamin A mediates conversion of monocyte-derived macrophages into tissue resident macrophages during alternative activation

Whether activated inflammatory macrophages can adopt features of tissue resident macrophages and what mechanisms mediate this phenotypic conversion remain unclear. Here we show that vitamin A was required for phenotypic conversion of interleukin 4 (IL-4)-activated monocyte-derived F4/80(int)CD206(+)PD-L2(+)MHCII(+) macrophages into macrophages with a tissue-resident F4/80(hi)CD206(−)PD-L2(−)MHCII(−)UCP1(+) phenotype in the peritoneal cavity of mice and during liver granuloma formation in mice infected with Schistosoma mansoni. Phenotypic conversion of F4/80(int)CD206(+) macrophages into F4/80(hi)CD206(−) macrophages was associated with almost complete remodeling of the chromatin landscape, as well as alteration of the transcriptional profiles. Vitamin A deficient mice infected with S. mansoni had disrupted liver granuloma architecture and increased mortality, indicating that failure to convert from F4/80(int)CD206(+) macrophages to F4/80(hi)CD206(−) macrophages may lead to dysregulated inflammation during helminth infection.