Wu Fan, Zhao Yan, Shao Qingqing, Fang Ke, Dong Ruolan, Jiang Shujun, Lu Fuer, Luo Jinlong, Chen Guang
Institute of Integrated Traditional Chinese and Western Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.
Department of Integrated Traditional Chinese and Western Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.
Front Pharmacol. 2021 May 13;12:646331. doi: 10.3389/fphar.2021.646331. eCollection 2021.
Natural product, osthole, has been proven to have a protective effect on organ fibrosis, including renal fibrosis. All of these studies are mainly focused on the regulation of TGF-β/Smad signaling pathway. However, due to the pleiotropic roles of TGF-β/Smad signaling, direct TGF-β-targeted treatments are unlikely to be therapeutically feasible in clinic. Recently, the downstream IL-11/ERK1/2 signaling of TGF-β has become an attractive therapeutic target without upstream disadvantages. Based on that, this study was designed to identify the potential effects of osthole on IL-11/ERK1/2 signaling pathway in renal fibrosis. The renal fibrosis model was established and , we investigated the effects of osthole on unilateral ureteral obstruction (UUO)-induced renal fibrosis and TGF-β-induced HK-2 cells. After preliminarily confirming the antifibrogenic effects of osthole and the link between its antifibrogenic effects and the inhibition of IL-11/ERK1/2 signaling, we applied a direct IL-11-induced HK-2 cells fibrosis model to further explore the inhibitory effects of osthole on IL-11/ERK1/2 signaling pathway. Our results confirmed that osthole can decrease the secretion of fibrosis proteins, such as α-smooth muscle actin (α-SMA), collagen I, and fibronectin, ameliorate experimental renal fibrosis and , and the effect was associated with suppressing TGF-β1/Smad signaling. More importantly, we found that IL-11/ERK1/2 signaling in UUO-induced renal fibrosis and TGF-β-induced HK-2 cell model was obviously upregulated, and osthole treatment also significantly inhibited the abnormal IL-11/ERK1/2 signaling activation. Given the direct link between TGF-β/Smad signaling and IL-11/ERK1/2 signaling pathway, we have verified that osthole has a direct inhibitory effect on IL-11/ERK1/2 signaling independent of TGF-β signaling by using an IL-11-induced HK-2 cells fibrosis model. Osthole treatment decreased the protein expression of α-SMA, collagen I and fibronectin without changing their mRNA levels in IL-11-induced HK-2 cells. Moreover, it was observed that the IL-11/ERK1/2 inhibitor, U0126, partly blocked the antifibrogenic effects of osthole. In this study, we found that osthole has a previously unrecognized role in inhibiting IL-11/ERK1/2 signaling pathway. Our work demonstrated that the antifibrogenic effect of osthole is not only mediated by TGF-β/Smad2/3 signaling, but also directly mediated by IL-11/ERK1/2 signaling pathway independent of TGF-β1 signaling.
天然产物蛇床子素已被证明对包括肾纤维化在内的器官纤维化具有保护作用。所有这些研究主要集中在TGF-β/Smad信号通路的调节上。然而，由于TGF-β/Smad信号具有多效性作用，直接以TGF-β为靶点的治疗在临床上不太可能具有治疗可行性。最近，TGF-β的下游IL-11/ERK1/2信号已成为一个有吸引力的治疗靶点，且没有上游靶点的缺点。基于此，本研究旨在确定蛇床子素对肾纤维化中IL-11/ERK1/2信号通路的潜在影响。建立了肾纤维化模型，我们研究了蛇床子素对单侧输尿管梗阻（UUO）诱导的肾纤维化和TGF-β诱导的HK-2细胞的影响。在初步证实蛇床子素的抗纤维化作用及其抗纤维化作用与抑制IL-11/ERK1/2信号之间的联系后，我们应用直接IL-11诱导的HK-2细胞纤维化模型进一步探索蛇床子素对IL-11/ERK1/2信号通路的抑制作用。我们的结果证实，蛇床子素可以减少纤维化蛋白如α-平滑肌肌动蛋白（α-SMA）、I型胶原和纤连蛋白的分泌，改善实验性肾纤维化，且该作用与抑制TGF-β1/Smad信号有关。更重要的是，我们发现UUO诱导的肾纤维化和TGF-β诱导的HK-2细胞模型中的IL-11/ERK1/2信号明显上调，蛇床子素治疗也显著抑制了异常的IL-11/ERK1/2信号激活。鉴于TGF-β/Smad信号与IL-11/ERK1/2信号通路之间的直接联系，我们通过使用IL-11诱导的HK-2细胞纤维化模型验证了蛇床子素对IL-11/ERK1/2信号具有独立于TGF-β信号的直接抑制作用。蛇床子素治疗降低了IL-11诱导的HK-2细胞中α-SMA、I型胶原和纤连蛋白的蛋白表达，但未改变其mRNA水平。此外，观察到IL-11/ERK1/2抑制剂U0126部分阻断了蛇床子素的抗纤维化作用。在本研究中我们发现蛇床子素在抑制IL-11/ERK1/2信号通路方面具有以前未被认识的作用。我们的工作表明，蛇床子素的抗纤维化作用不仅由TGF-β/Smad2/3信号介导，还由独立于TGF-β1信号的IL-11/ERK1/2信号通路直接介导。
