FOXP3+ macrophage represses acute ischemic stroke-induced neural inflammation.

ABSTRACT

Proper termination of cell-death-induced neural inflammation is the premise of tissue repair in acute ischemic stroke (AIS). Macrophages scavenge cell corpses/debris and produce inflammatory mediators that orchestrate immune responses. Here, we report that FOXP3, the key immune-repressive transcription factor of Tregs, is conditionally expressed in macrophages in stroke lesion. FOXP3 ablation in macrophages results in detrimental stroke outcomes, emphasizing the beneficial role of FOXP3+ macrophages. FOXP3+ macrophages are distinct from the M1 or M2 subsets and display superactive efferocytic capacity. With scRNAseq and analysis of FOXP3-bound-DNA isolated with CUT & RUN, we show that FOXP3 facilitates macrophage phagocytosis through enhancing cargo metabolism. FOXP3 expression is controlled by macroautophagic/autophagic protein degradation in resting macrophages, while initiation of LC3-associated phagocytosis (LAP) competitively occupies the autophagic machineries, and thus permits FOXP3 activation. Our data demonstrate a distinct set of FOXP3+ macrophages with enhanced scavenging capability, which could be a target in immunomodulatory therapy against AIS.Abbreviations ADGRE1/F4/80 adhesion G protein-coupled receptor E1; AIF1/Iba1 allograft inflammatory factor 1; AIS acute ischemic stroke; ARG1 arginase 1; ATP adenosine triphosphate; BECN1/Beclin1 Beclin 1, autophagy related; BMDM bone marrow-derived macrophages; CKO conditional knockout; CSF1/M-CSF colony stimulating factor 1 (macrophage); CSF2/GM-CSF colony stimulating factor 2; CSF3/G-CSF colony stimulating factor 3; CUT & RUN cleavage under targets and release using nuclease; CyD cytochalasin D; DAMP danger/damage-associated molecular pattern; DIL dioctadecyl-3,3,3,3-tetramethylin docarbocyanine; ELISA enzyme linked immunosorbent assay; GO Gene Ontology; FCGR3/CD16 Fc receptor, IgG, low affinity III; HMGB1 high mobility group box 1; IFNG/IFNγ interferon gamma; IP immunoprecipitation; KEGG Kyoto Encyclopedia of Genes and Genomes; ITGAM/CD11b integrin subunit alpha M; ITGAX/CD11c integrin subunit alpha X; LAP LC3-associated phagocytosis; LC-MS liquid chromatography-mass spectrometry; LPS lipopolysaccharide; MRC1/CD206 mannose receptor, C type 1; O4 oligodendrocyte marker O4; PBMC peripheral blood mononuclear cells; RBC red blood cells; PTPRC/CD45 protein tyrosine phosphatase, receptor type, C; RBFOX3/NeuN RNA binding protein, fox 1 homolog (C. elegans) 3; RUBCN/Rubicon RUN domain and cysteine-rich domain containing, Beclin 1-interacting protein; scRNAseq single cell RNA sequencing; SQSTM1/p62 (sequestosome 1); TGFB/TGFß transforming growth factor, beta; tMCAO transient middle cerebral artery occlusion; TNF/TNFα tumor necrosis factor; Treg regulatory T cell.