微囊藻毒素-LR长期低剂量暴露诱导小鼠肾脏结构和功能损伤:基于激活PI3K/AKT信号通路

Long-term low-dose microcystin-LR exposure induces renal injury in mice by activating PI3K/AKT signaling pathway

目的 探讨微囊藻毒素-LR(MC-LR)长期低剂量暴露对肾脏的毒性作用及其潜在的分子机制。方法 构建MC-LR慢性染毒体内模型,将20只C57BL/6小鼠随机分成4组,分别给予含0、1、60、120μg/L MC-LR的饮用水染毒12月。构建MC-LR染毒体外模型,将HEK293细胞分为对照组,MC-LR染毒组,PI3K抑制剂LY294002组,LY294002+MC-LR组。在体内模型中监测小鼠体质量和肾脏质量,观察小鼠肾脏组织损伤。在体内外模型中检测小鼠肾脏和HEK293细胞的肾功能指标,炎症因子IL-6、TNF-α和IL-10的mRNA表达水平以及PI3K/AKT通路蛋白的相对表达水平。结果 体内模型中:各组小鼠体质量变化的总体趋势一致,肾脏绝对质量和肾脏指数也无明显改变。与对照组相比,60和120μg/L染毒组小鼠出现肾结构损伤,BUN和SCr水平显著上升,且差异有统计学意义(P<0.05)。促炎因子IL-6和TNF-α水平在60和120μg/L染毒组中上调,抗炎因子IL-10在所有染毒组中下降,且差异有统计学意义(P<0.05)。p-PI3K/PI3K、p-AKT/AKT的蛋白相对表达量均在60和120μg/L染毒组上升,且差异有统计学意义(P<0.05)。体外模型中:在HEK293细胞中,BUN和Cr水平在MC-LR组呈升高趋势而在MC-LR+LY294002组中显著下降,且差异有统计学意义(P<0.05)。促炎因子IL-6和TNF-α的mRNA表达水平在MC-LR组呈升高趋势而在MC-LR+LY294002组中显著下降,抗炎因子IL-10的mRNA表达水平在MC-LR组呈下降趋势而在MC-LR+LY294002组中显著升高,且差异均具有统计学意义(P<0.05)。p-PI3K/PI3K、p-AKT/AKT的表达水平也同样在MC-LR组上调而在MC-LR+LY294002组中显著下调,且差异具有统计学意义(P<0.05)。结论 MC-LR可通过调控PI3K/AKT信号通路,激活炎症反应,诱导小鼠肾脏结构和功能损伤。

Objective To investigate the toxic effect of long-term low-dose exposure to microcystin-LR(MC-LR) on kidney and its underlying molecular mechanism. Methods Forty male C57BL/6 mice were randomized into 4 groups for exposure to 0, 1,60, and 120 μg/L MC-LR(mixed in drinking water) for 12 months, and the body and kidney weight changes and renal pathologies of the mice were observed. The renal function indexes, the mRNA expression levels of IL-6, TNF-α and IL-10, and relative expression levels of PI3K/AKT pathway proteins in the kidney of the mice were detected. These parameters were also detected in HEK293 cells treated with MC-LR, LY294002, or both. Results The overall trend of body weight changes was consistent among the 4 groups of mice, and their kidney mass and kidney index underwent no significant changes. In mice exposed to 60 and 120 μg/L MC-LR, obvious renal structural damage and significant elevation of the BUN and SCr levels were observed(P<0.05) with up-regulated levels of IL-6 and TNF-α mRNA and increased protein expressions of p-PI3K/PI3K and p-AKT/AKT in the renal tissues(P<0.05). IL-10 mRNA expression was significantly decreased in all the exposure groups(P<0.05). The levels of BUN and Cr increased significantly in MC-LR-treated HEK293 cells and decreased in cells treated with both MC-LR and LY294002(P<0.05). The m RNA expression levels of IL-6 and TNF-α increased and the level of IL-10 mRNA decreased obviously in MC-LR-treated cells, and the opposite changes were observed in the cells with the combined treatment(P<0.05). The proteins levels of p-PI3K/PI3K and p-AKT/AKT were significantly up-regulated in MC-LR group and down-regulated in the combined treatment group(P<0.05). Conclusion MC-LR can activate inflammatory response and induce renal structural and functional damages in mice by activating the PI3K/AKT signaling pathway.