丁酸钠通过调控TGF-β1/SGK1信号通路改善UUO大鼠肾间质纤维化

Sodium butyrate ameliorates renal interstitial fibrosis in UUO rats by regulating the TGF-β1/SGK1 signaling pathway

目的探讨丁酸钠对单侧输尿管梗阻(unilateral ureteral obstruction,UUO)诱导的肾间质纤维化的影响及其作用机制。方法将大鼠随机分为假手术组、UUO组及UUO+丁酸钠低剂量组(1 g·kg^(-1)·d^(-1))、UUO+丁酸钠高剂量组(2 g·kg^(-1)·d^(-1)),每组10只。在术后第7、14 d,每组分别随机选取5只大鼠处死,HE染色观察大鼠肾脏组织形态,Masson染色观察大鼠肾间质纤维化情况,免疫组化和RT-PCR方法检测Ⅰ型胶原(collagen I,Col-I)、α-平滑肌肌动蛋白(alpha-smooth muscle actin,α-SMA)、肿瘤坏死因子-α(tumour necrosis factor alpha,TNF-α)、白介素6(interleukin 6,IL-6)、转化生长因子β1(transforming growth factor-β1,TGF-β1)、血清/糖皮质激素调节的激酶1(serum/glucocorticoid regulated kinase 1,SGK1)、结缔组织生长因子(connective tissue growth factor,CTGF)和p65的表达水平。结果与假手术组相比,UUO组的HE染色可见肾小管扩张、炎症细胞浸润等病理改变,Masson染色可见蓝色胶原沉积明显增多,且随着时间延长,其肾脏病变加重;经丁酸钠干预后可减轻肾脏的损伤、病理改变以及肾间质纤维化程度,且UUO+丁酸钠高剂量组较UUO+丁酸钠低剂量组改善更明显。此外,与假手术组相比,UUO组大鼠肾组织中α-SMA、Col-I、TNF-α及IL-6的蛋白及mRNA表达水平显著增加(P<0.05);丁酸钠干预后UUO模型中α-SMA、Col-I、IL-6及TNF-α的蛋白及mRNA表达水平降低,且UUO+丁酸钠高剂量组较UUO+丁酸钠低剂量组下降明显。同时,与假手术组相比,UUO组大鼠TGF-β1、SGK1及其下游靶点p65和CTGF的蛋白及mRNA表达水平均显著上调(P<0.05);经过丁酸钠干预后,可以改善UUO模型中TGF-β1/SGK1信号通路的变化,且UUO+丁酸钠高剂量组改善更明显。结论丁酸钠可能通过改善炎症及调节TGF-β1/SGK1信号通路明显改善UUO大鼠的肾间质纤维化。

Objective To investigate the effect of sodium butyrate on renal interstitial fibrosis induced by unilateral ureteral obstruction(UUO)and its mechanism.Methods The rats were randomly divided into four groups:the sham operation group,the UUO group,the UUO+sodium butyrate low-dose group(1 g·kg^(-1)·d^(-1)),and the UUO+sodium butyrate high-dose group(2 g·kg^(-1)·d^(-1)),with 10 rats in each group.On the 7th and 14th postoperative days,5 rats in each group were randomly selected for execution,and the renal tissue morphology was observed by HE staining,and the interstitial fibrosis was observed by Masson staining.The level of expression of alpha-smooth muscle actin(α-SMA),collagen I(Col-I),tumour necrosis factor alpha(TNF-α),interleukin 6(IL-6),transforming growth factor-β1(TGF-β1),serum/glucocorticoid regulated kinase 1(SGK1),p65,and connective tissue growth factor(CTGF)were detected by immunohistochemistry and RT-PCR.Results Compared with the sham group,HE staining showed pathological changes such as dilated renal tubules and inflammatory cell infiltration in the UUO group.Masson staining showed a significant increase in blue collagen deposition and aggravation of renal lesions with time in the UUO group.But intervention with sodium butyrate reduced renal damage,pathological changes and the degree of interstitial fibrosis.The improvement was significant in the UUO+sodium butyrate highdose group compared to the UUO+sodium butyrate low-dose group.In addition,the expression levels of proteins and mRNAs ofα-SMA,Col-I,TNF-α,and IL-6 in the renal tissues of rats in the UUO group were significantly higher than those in the sham group(P<0.05),whereas sodium butyrate intervention reduced the protein and mRNA expression ofα-SMA,Col-I,TNF-α,and IL-6 in the UUO model,and the UUO+sodium butyrate high-dose group decreased significantly compared with the UUO+sodium butyrate lowdose group.Meanwhile,compared to the sham-operated group,the expression levels of proteins and mRNAs of TGF-β1,SGK1,and their downstream targets p65 and CTGF were significantly up-regulated in UUO rats(P<0.05),while the changes of TGF-β1/SGK1 signaling pathway in UUO model could be improved after sodium butyrate intervention,and the improvement was more obvious in the UUO+sodium butyrate high-dose group.Conclusion Sodium butyrate may significantly ameliorate renal interstitial fibrosis in UUO rats by reducing inflammation and modulating the TGF-β1/SGK1 signaling pathway.