IL-38 通过调控PI3K/ Akt/ GSK3β/ NFATc1 信号通路抑制骨质疏松的机制研究

目的:探讨IL-38 抑制骨质疏松的作用并研究其分子机制。方法:共纳入2014 年6 月~2016 年12 月我院收治的138 例骨质疏松患者作为研究对象。另选取120 例同期在我院骨科进行骨折手术的无骨质疏松患者作为对照。采用ELISA 法检测实验对象血清IL-38 水平。构建IL-38-C57BL/6J 转基因小鼠,建立骨质疏松小鼠模型,将野生型、IL-38 转基因小鼠分别设置为假手术组(Sham 组)与卵巢切除组(Ovariectomy,OVX 组)。术后8 周取小鼠血清,检测碱性磷酸酶(ALP)、血钙及血磷水平。另取小鼠的脊柱与双侧股骨,通过病理切片分析股骨组织形态结构,用骨密度仪检测脊柱骨密度变化。将各组小鼠的骨髓基质细胞(BMSCs)进行分离并检测其体外增殖能力,Western blot 检测各组BMSCs 的PI3K、Akt、GSK3β与NFATc1 的磷酸化水平。小鼠成骨细胞MC3T3-E1 转染IL-38 后,Western blot 检测PI3K、Akt、GSK3β与NFATc1 磷酸化水平的变化,流式细胞术检测IL-38 对细胞凋亡的影响。结果:骨质疏松组患者的血清IL-38 水平显著低于对照组(P<0.05)。野生型与IL-38 转基因OVX 小鼠的血钙、血磷水平均显著高于Sham 组(P<0.05),而ALP 水平显著低于Sham 组(P<0.05)。另外,IL-38 转基因OVX 小鼠的血钙和血磷水平均显著低于野生型OVX 小鼠(P<0.05)。股骨病理切片及脊柱骨密度分析显示,野生型与IL-38 转基因OVX 小鼠均出现骨组织形态结构破坏和骨密度下降,并且IL-38 转基因OVX 小鼠的骨组织形态结构破坏和骨密度下降情况均较野生型OVX 小鼠显著减轻(P<0.05)。IL-38 转基因OVX 小鼠BMSCs 的体外增殖能力显著高于野生型OVX 组(P<0.05)。IL-38 转基因OVX 小鼠BMSCs 的PI3K、Akt 与NFATc1 磷酸化水平均显著低于野生型OVX 组(P<0.05),GSK3β磷酸化水平显著高于野生型OVX 组(P<0.05)。MC3T3-E1 细胞转染IL-38 后PI3K、Akt 与NFATc1 的磷酸化水平均显著降低(P<0.05),GSK3β的磷酸化水平显著升高(P<0.05)。流式细胞检测显示转染IL-38 后MC3T3-E1 细胞的凋亡显著减少(P<0.05)。结论:骨质疏松患者的血清IL-38 水平显著降低,IL-38 可能通过调控PI3K/ Akt/ GSK3β/ NFATc1 信号通路促进BMSCs 增殖、抑制成骨细胞凋亡,从而抑制骨质疏松的进展。

IL-38 inhibits osteoporosis via regulating PI3K / Akt / GSK3β/ NFATc1 signaling pathway

Objective:To investigate the role and mechanism of IL-38 in inhibiting osteoporosis.Methods: A total of 138 cases of patients with osteoporosis in our hospital from June 2014 to December 2016 were recruited.Another 120 cases of fracture surgery patients without osteoporosis were selected as control.Serum levels of IL-38 in different groups were determined using a commercially available sandwich ELISA (Enzyme-Linked ImmunoSorbent Assay).Construction of IL-38-C57BL/6J transgenic mice,the wild type and IL-38 transgenic mice were set to sham operation group (Sham),operation group (ovariectomy,group OVX) respectively.After 8 weeks of the operation,the serum level of alkaline phosphatase (ALP),calcium and phosphorus were detected.The bilateral femur and spine of mice were collected after sacrifice,the morphology and structure of the femur were analyzed,and the bone density was measured by bone density meter.The bone marrow stromal cells (BMSCs) were isolated and the invitro proliferation ability of BMSCs were measured.Western blot were used to detect the phosphorylation level of PI3K,Akt,GSK3βand NFATc1 in BMSCs.After transfection of IL-38 into mouse osteoblast MC3T3-E1 cell,the phosphorylation level of PI3K,Akt,GSK3βand NFATc1 were detected by Western Blot.Apoptosis of MC3T3-E1 cells were detected by flow cytometry.Results: The serum level of IL-38 in patients with osteoporosis were significant lower than control group (P<0.05).The serum level of estrogen,calcium and phosphorus in OVX group of wild type and IL-38 transgenic mice were significant lower than the sham operation group (P<0.05),while the level of ALP was significant higher than sham operation group (P < 0.05),but the serum level of calcium and phosphorus in OVX group of IL-38 transgenic mice were significant higher than wild type mice (P<0.05).The pathological section of femur and spine BMD showed that the bone tissue in wild type mice and IL-38 transgenic mice in OVX group were damaged and the bone density decreased significantly,but IL-38 transgenic mice was significant better than wild type mice (P<0.05).The proliferation ability of BMSCs in OVX group of IL-38 transgenic mice was significant higher than wild type mice (P<0.05).The phosphorylation level of PI3K,Akt and NFATc1 in OVX group of IL-38 transgenic mice were significant lower than wild type mice (P<0.05),while the phosphorylation level of GSK3βwas significant higher than wild type mice (P<0.05).After transfection of IL-38 into MC3T3-E1 cell,the phosphorylation level of PI3K,Akt and NFATc1 were significant decreased (P<0.05),while the phosphorylation level of GSK3βwas significant increased (P<0.05).Flow cytometry assay showed that IL-38 transfection significant decreased the apoptosis of MC3T3-E1 cells (P<0.05).Conclusion: The serum level of IL-38 in patients with osteoporosis is decreased significantly.IL-38 may inhibit the proliferation of BMSCs and inhibit the apoptosis of osteoblasts by regulating the PI3K/ Akt/ GSK3β/ NFATc1 signaling pathway.