HIF-1 alpha controls palatal wound healing by regulating macrophage motility via S1P/S1P(1) signaling axis

Objectives To investigate the role of hypoxia-inducible factor 1 alpha (HIF-1 alpha) signaling, the expression profile of M1 and M2 macrophages, and the role of the sphingosine 1-phosphate (S1P)/S1P receptor system in palatal wound healing of heterozygous HIF-1 alpha-deficient (HIF-1 alpha HET) mice. Materials and methods HIF-1 alpha HET and wild-type (WT) littermates underwent palatal tissue excision at the mid-hard palate. Histological analysis, immunostaining, real-time PCR, Western blotting (WB), and cellular migration assays were performed to analyze wound closure and macrophage infiltration. Results DMOG pretreatment showed an acceleration of palatal wound closure in WT mice. In contrast, the delayed palatal wound closure was observed in HIF-1 alpha HET mice with diminished production of Col1a1, MCP-1, and MIP-1 alpha, compared with WT mice. Decreased infiltration of M1 macrophage (F4/80(+)TNF-alpha(+), F4/80(+)iNOS(+)) and M2 macrophage (F4/80(+)Arginase-1(+), F4/80(+)CD163(+)) was observed. The numbers of F4/80(+)S1P(1)(+) macrophages of HIF-1 alpha HET wounded tissues were significantly lower compared with WT tissues. S1P treatment of bone marrow macrophages (BMMs) significantly upregulated expression of S1P(1) in WT mice compared with HIF-1 alpha HET. Phosphorylation of MAPK rapidly decreased in BMMs of HIF-1 alpha HET mice than in BMMs of WT mice by S1P stimulation. Moreover, S1P enhanced HIF-1 alpha expression via S1P(1) receptors to affect macrophage migration. Conclusions HIF-1 alpha deficiency aggravates M1 and M2 macrophage infiltration and controls macrophage motility via S1P/S1P(1) signaling. These results suggest that HIF-1 alpha signaling may contribute to the regulation of palatal wound healing.