The Notch signal mediates macrophage polarization by regulating miR-125a/miR-99b expression

Abstract We aimed to explore the mediating role of Notch signal in macrophage polarization. This signal was knocked out from macrophages of Lyz2 cre and RBP-J flox mice. Bone marrow-derived macrophages (BMDMs) were isolated and polarized. The expressions of polarization markers in BMDMs 24？h after transfection were detected by qPCR. After Notch knockout, the expressions of M1 markers decreased but those of M2 markers increased significantly. MiR-125a/miR-99b and Spaca6 were highly and lowly expressed upon M1 and M2 polarizations, respectively. The expressions of experimental group were significantly lower than those of control group. Overexpression of miR-125a significantly promoted the expressions of M1 markers, whereas inhibited those of M2 markers. NO release in the culture supernatant of miR-125a overexpression group significantly exceeded that of control group. Transfection with miR-125a inhibitor significantly down-regulated IL-12 expression but up-regulated MR expression in BMDMs. The supernatant secreted by M1 macrophages significantly facilitated BS524 cell apoptosis, which was enhanced after miR-125a overexpression. The TNF-α expression of miR-99b overexpression group increased whereas that of MR decreased significantly. The miR-125a/miR-99b cluster contained an RBP-J specific recognition site in the first intron of initial transcript. The Notch signalling pathway promoted macrophage polarization into M1 phenotype by up-regulating miR-125a/miR-99b expression