Abstract: Objective To study the effect of rapamycin(RAP)modulating macrophage phenotypes on pulmonary artery hypertension(PAH)and the correlated mechanism. Methods Thirty male Sprague-Dawley rats were randomly divided into the control, PAH and PAH+RAP groups, ten in each group. PAH rat model was induced by left pneumonectomy(PE)and monocrotaline(MCT). Five days after PAH model establishment, the control group and the PAH+RAP group received an intramuscular injection of solvent and RAP for thirty days, respectively. The mean pulmonary artery pressure(mPAP)and right ventricular hypertrophy index(RVHI)were measured in each group via the right cardiac catheter. The degrees of macrophages infiltration and the proliferation of pulmonary arteriolar smooth muscle cells 山 东 大 学 学 报 (医 学 版)56卷4期 -王波,等.雷帕霉素调控巨噬细胞表型改善肺动脉高压 \=-were evaluated by immunohistochemistry, the expression of α-SMA protein was detected by Western blotting, and the expression levels of M2 macrophages was detected by immunofluorescence. The expression levels of TNF-α, IL-1, IL-6 and IL-10 mRNA in each group were detected by RT-PCR. Macrophages were cultured in vitro and treated with LPS+INF-γ, IL-4, and LPS+INF-γ+RAP, respectively; the cells were divided into the blank control group, LPS+INF-γ group, IL-4 group, and LPS+INF-γ+RAP group accordingly. The phenotypes of macrophages were detected by flow cytometry, and the mRNA expression levels of the inflammatory factors were dected by RT-PCR. Results PHA rat models were established successfully. The mPAP, RVHI, α-SMA protein expression level, macrophage infiltration degree and mRNA expression levels of inflammatory factors TNF-α, IL-1β, IL-6, and IL-10 in PAH group were higher than those in the control group(all P<0.05). The mPAP, RVHI, α-SMA protein expression level, and mRNA expression levels of inflammatory factors TNF-α, IL-1β, IL-6, and IL-10 in PAH+RAP group were lower than those in PAH group(all P<0.05). The expression level of M2-type macrophages in PAH+RAP group was higher than that in PAH group(P<0.05). CD86 positive macrophages percentage and mRNA expression levels of TNF-α, IL-1β, IL-6, and IL-10 in LPS+INF-γ group were higher than those in the blank control group in vitro(all P<0.05). CD86 positive macrophages percentage and mRNA expression levels of TNF-α, IL-1β, IL-6, and IL-10 in LPS+IFN-γ+RAP group were lower than those in LPS+INF-γ group(all P<0.05). Conclusion PAH occurrence is accompanied with macrophage infiltration and expression level increase of inflammatory factors. RAP improves PAH via reducing inflammatory response partly depending on inducing the macrophages transformation into M2.

Key words: Rapamycin, Pulmonary arterial hypertension, Macrophages, Pulmonary arterial smooth muscle cells, Phenotype transformation, Interleukin-lβ, Interleukin-6