Blood–brain barrier (BBB) breakdown and the associated microvascular hyperpermeability are hallmark features of several neurological disorders, including traumatic brain injury (TBI). However, there is no viable therapeutic strategy to rescue BBB function. Tissue inhibitor of metalloproteinase-1 (TIMP1) has been considered to be beneficial for vascular integrity, but the molecular mechanisms underlying the functions of TIMP1 remain elusive. Here, we report that TIMP1 executes a protective role on neuroprotective function via ameliorating BBB disruption in mice with experimental TBI. In human brain microvessel endothelial cells (HBMECs) exposed to hypoxia and inflammation injury, the recombinant TIMP1 (rTIMP1) treatment maintained integrity of junctional proteins and trans-endothelial tightness. Mechanistically, TIMP1 interacts with CD63/integrin β1 complex and activates downstream FAK signaling, leading to attenuation of RhoA activation and F-actin depolymerization for endothelial cells structure stabilization. Notably, these effects depend on CD63/integrin β1 complex, instead of the MMP-inhibitory function. Together, our results identified a novel MMP-independent function of TIMP1 in regulating endothelial barrier integrity. Therapeutic interventions targeting TIMP1 and its downstream signaling may be beneficial to protect BBB function following brain injury and neurological disorders.

血脑屏障（BBB）破坏和相关的微血管通透性过高是包括创伤性脑损伤（TBI）在内的多种神经系统疾病的标志特征。然而，尚无可行的治疗策略来挽救 BBB 功能。金属蛋白酶组织抑制剂 1 (TIMP1) 被认为有益于血管完整性，但 TIMP1 功能背后的分子机制仍不清楚。在此，我们报告 TIMP1通过改善实验性 TBI 小鼠的 BBB 破坏而对神经保护功能发挥保护作用。在暴露于缺氧和炎症损伤的人脑微血管内皮细胞 (HBMEC) 中，重组 TIMP1 (rTIMP1) 治疗保持了连接蛋白的完整性和跨内皮的紧密性。从机制上讲，TIMP1 与 CD63/整合素β 1 复合物相互作用，并激活下游 FAK 信号传导，导致 RhoA 激活减弱和 F-肌动蛋白解聚，从而稳定内皮细胞结构。值得注意的是，这些作用取决于 CD63/整合素β 1 复合物，而不是 MMP 抑制功能。总之，我们的结果确定了 TIMP1 在调节内皮屏障完整性方面的一种新的独立于 MMP 的功能。针对 TIMP1 及其下游信号传导的治疗干预可能有益于保护脑损伤和神经系统疾病后的 BBB 功能。