BioProject

Most tissue-resident macrophage populations develop during embryogenesis, self-renew in the steady state, and can expand during type 2 immunity. More...

Most tissue-resident macrophage populations develop during embryogenesis, self-renew in the steady state, and can expand during type 2 immunity. Whether shared mechanisms regulate macrophage proliferation in homeostasis and disease is unclear. We found that the transcription factor Bhlhe40 was cell-intrinsically required in large peritoneal macrophages (LPMs) for self-renewal and maintenance, but was not required in other resident macrophages. Bhlhe40 was selectively necessary in LPMs for proliferation, but not polarization, in response to IL-4. During a helminth infection, Bhlhe40 was required for normal LPM cell cycling. Bhlhe40 repressed the expression of Maf and Mafb and directly promoted expression of cell cycle-related transcripts to enable proliferation of LPMs. Genomic sites bound by Bhlhe40 in LPMs included some co-bound by the macrophage lineage-determining factor PU.1 and others uniquely bound by Bhlhe40, including Maf and cell cycle-related loci. Our findings demonstrate a tissue-specific control mechanism regulating resident macrophage proliferation in homeostasis and type 2 immunity. Overall design: Bhlhe40+/+=Bhlhe40WT, Bhlhe40-/-=Bhlhe40KO, LysM-Cre+ Bhlhe40fl/fl=Bhlhe40LysM. AMs, 2 Bhlhe40+/+ and 2 Bhlhe40-/- samples sorted from naïve mice. Naïve LPMs, 3 Bhlhe40+/+ and 3 Bhlhe40-/- samples sorted from naïve mice. IL-4c-stimulated LPMs, 2 Bhlhe40+/+, 2 Bhlhe40-/-, and 2 LysM-Cre+ Bhlhe40fl/fl samples sorted from IL-4c-treated mice Less...