巨细胞病毒在平滑肌细胞表型转化中的作用及调控机制

Correlation and modulation of smooth muscle cells phenotypic switching induced by cytomegalovirus

目的通过体内及体外实验探讨小鼠巨细胞病毒（murine cytomegalovirus，MCMV）对血管平滑肌细胞（vascular smooth muscle cell，VSMC）表型转化的影响及表型转化P13K／Akt通路的调控作用。方法2×10^5PFUMCMV腹腔注射雄性载脂蛋白E基因敲除（apoE^-/-）小鼠，饲养16周后取主动脉分别行HE染色、平滑肌22a（smooth muscle 22 alpha，SM22α）和骨桥蛋白（osteopontin，OPN）免疫组化染色。小鼠主动脉血管平滑肌细胞（MOVAS）传代培养后，与MCMV共孵育，检测MOVAS增殖程度，以及SM22a和OPN的表达。进一步应用Western blot检测MCMV在平滑肌细胞表型转化P13K／Akt通路中的作用。结果MCMV感染组的apoE^-/-小鼠主动脉的动脉粥样硬化程度较对照组严重，动脉壁以表达合成期的标志蛋白OPN为主。3×10^4PFU MCMV感染MOVAS24h细胞后，SM22a表达较对照组下降，OPN表达较对照组增加（P=0．023，P=0．034）。MCMV刺激磷酸化Akt蛋白表达上调（P=0．035），P13K通路的抑制剂LY294002不仅抑制MCMV促平滑肌细胞表型转化，而且还阻断MCMV感染后的Akt蛋白磷酸化（P=0．031），而对对照组无明显影响（P=0．081）。结论MCMV诱导了平滑肌细胞的表型转化，P13K／Akt信号途径可能参与了MCMV促平滑肌细胞表型转化的过程。

Objective To explore modulation of vascular smooth muscle cell and the influence of murine cytomegalovirus on phenotypic modulation of PI3K/Akt pathway. Methods Male apoE knockout mice were injected abdominally with 2×10^5 PFU MCMV, followed by 16 weeks feeding. Then aortas were sectioned for HE staining and immunohistochemical staining of smooth muscle 22 alpha （SM22α） and osteopontin （OPN）. Mouse aortic smooth muscle cells （MOVAS）were incubated with MCMV, then proliferation of MOVAS and expression of SM22a and OPN were tested. Western blotting test was applied to reveal MCMV＇ s modulation of PI3K/Akt pathway. Results The degree of atherosclerosis of apoE^-/- mice in MCMV infection group was severe than that in control group, and OPN stain positive signals predominated in the arterial wall. After 24 hours of incubation with MCMV by 3 ×10^4 PFU, the expression of SM22a decreased （P = 0. 023） , while OPN increased （P = 0. 034） in MOVAS. MCMV increased expression of Akt phosphorylation compared with the control group （P = 0. 035 ）. The inhibitor of PI3K pathway LY294002 not only inhibited the phenotypic modulation of smooth muscle by MCMV, but also blocked the Akt phosphorylation after MCMV infection （P = 0. 031 ）, however no significant influence was observed in control group. Conclusions MCMV induces phenotypie modulation of vascular smooth muscle, PI3K/Akt signaling pathway may be involved in the process of MCMV promoting the phenotype transformation of smooth muscle cells.