Sestrin2 Restricts Endothelial-to-Mesenchymal Transition Induced by Lipolysaccharide via Autophagy.

ABSTRACT

OBJECTIVES: Endothelial-to-mesenchymal transition (EndoMT) is a significant biological phenomenon wherein endothelial cells undergo a loss of their endothelial traits and progressively acquire mesenchymal characteristics. Consequently, this transformation leads to both a compromised ability to maintain lumen permeability and alterations in vascular structure, which hampers the preservation of blood-brain barrier integrity. This study aimed to investigate inflammation-induced EndoMT and its etiology, with the goal of impeding the infiltration of peripheral inflammation into the central nervous system. MATERIALS AND METHODS: Lipolysaccharide (LPS) was administered intraperitoneally to mice several times to establish a chronic inflammatory model. A cellular inflammatory model was established by LPS in human brain microvascular endothelial cells (HBMECs). The mRNA expressions of inflammatory cytokines interleukin-1ß (IL-1ß) and IL-6 were detected by real-time polymerase chain reaction (PCR). Immunofluorescence staining of platelet endothelial cell adhesion molecule-1 (CD31) and alpha smooth muscle actin (α-SMA) was conducted to assess the level of EndoMT. The expression levels of Occludin, zona occludens protein 1 (ZO-1), Sestrin2, microtubule-associated protein1 light chain 3 (LC3) and inducible nitric oxide synthase (iNOS) were detected by western blotting. RESULTS: LPS treatment induced the downregulation of ZO-1 and Occludin, which was accompanied by the elevated expressions of iNOS, α-SMA, Sestrin2 and LC3-II in the mouse cortex and HBMECs. Mechanistically, the knockdown of Sestrin2 in HBMECs exacerbated the EndoMT induced by LPS treatment, while the overexpression of Sestrin2 inhibited this process. Moreover, the induction of autophagy by rapamycin rescued the EndoMT induced by Sestrin2 knockdown. CONCLUSION: This study revealed that Sestrin2 inhibited endothelial inflammation and EndoMT via enhanced autophagy, which may provide a potential drug target for cerebrovascular inflammatory injury.