PDF(Pubmed)
Abstract：
Integrin-mediated activation of the profibrotic mediator transforming growth factor-β1 (TGF-β1), plays a critical role in idiopathic pulmonary fibrosis (IPF) pathogenesis. Galectin-3 is believed to contribute to the pathological wound healing seen in IPF, although its mechanism of action is not precisely defined. We hypothesized that galectin-3 potentiates TGF-β1 activation and/or signaling in the lung to promote fibrogenesis. We show that galectin-3 induces TGF-β1 activation in human lung fibroblasts (HLFs) and specifically that extracellular galectin-3 promotes oleoyl-L-α-lysophosphatidic acid sodium salt-induced integrin-mediated TGF-β1 activation. Surface plasmon resonance analysis confirmed that galectin-3 binds to αv integrins, αvβ1, αvβ5, and αvβ6, and to the TGFβRII subunit in a glycosylation-dependent manner. This binding is heterogeneous and not a 1:1 binding stoichiometry. Binding interactions were blocked by small molecule inhibitors of galectin-3, which target the carbohydrate recognition domain. Galectin-3 binding to β1 integrin was validated in vitro by coimmunoprecipitation in HLFs. Proximity ligation assays indicated that galectin-3 and β1 integrin colocalize closely (≤40 nm) on the cell surface and that colocalization is increased by TGF-β1 treatment and blocked by galectin-3 inhibitors. In the absence of TGF-β1 stimulation, colocalization was detectable only in HLFs from IPF patients, suggesting the proteins are inherently more closely associated in the disease state. Galectin-3 inhibitor treatment of precision cut lung slices from IPF patients\' reduced Col1a1, TIMP1, and hyaluronan secretion to a similar degree as TGF-β type I receptor inhibitor. These data suggest that galectin-3 promotes TGF-β1 signaling and may induce fibrogenesis by interacting directly with components of the TGF-β1 signaling cascade.
摘要：
整合素介导的促纤维化介质转化生长因子-β1（TGF-β1）的激活，在特发性肺纤维化（IPF）的发病机制中起着至关重要的作用。半乳糖凝集素-3被认为有助于IPF中看到的病理性伤口愈合，虽然它的作用机制没有明确的定义。我们假设半乳糖凝集素-3增强TGF-β1激活和/或在肺中的信号传导以促进纤维发生。我们显示半乳糖凝集素-3在人肺成纤维细胞（HLF）中诱导TGF-β1活化，特别是细胞外半乳糖凝集素-3促进油酰基-L-α-溶血磷脂酸钠盐（LPA）诱导的整合素介导的TGF-β1活化。表面等离子体共振（SPR）分析证实半乳糖凝集素-3与αv整合素结合，αvβ1，αvβ5和αvβ6，并以糖基化依赖性方式转化为TGFβRII亚基。这种结合是异质的,而不是1:1的结合化学计量。结合相互作用被靶向碳水化合物识别结构域的半乳糖凝集素-3的小分子抑制剂阻断。半乳糖凝集素-3与β1整联蛋白的结合在体外通过在HLF中的共免疫沉淀进行验证。邻近连接实验表明半乳糖凝集素-3和β1整联蛋白紧密地(≤40nm)在细胞表面上,TGF-β1治疗增加了共定位，并被半乳糖凝集素-3抑制剂阻断。在没有TGF-β1刺激的情况下，仅在IPF患者的HLF中可检测到共定位，这表明这些蛋白质在疾病状态中固有地更紧密相关。Galectin-3抑制剂治疗IPF患者的精确切肺切片可减少Col1a1，TIMP1和HA的分泌，其程度与TGF-βI型受体抑制剂相似。这些数据表明半乳糖凝集素-3促进TGF-β1信号传导，并可能通过直接与TGF-β1信号传导级联的组分相互作用来诱导纤维形成。
