MALAT1 modulates miR-146’s protection of microvascular endothelial cells against LPS-induced NF-κB activation and inflammatory injury

To investigate the role of miR-146 and its possible relationship with MALAT1 in LPS-induced inflammation in human microvascular endothelial cells (HMECs), HMEC-1 cells were treated with LPS to construct an inflammatory injury cell model, and the cell viability, TNF-α and IL-6 secretion and the expression levels of VCAM-1, SELE and ICAM-1 were analysed as markers of inflammatory injury. The regulation mechanisms of miR-146 interacted with MALAT1 and the downstream NF-κB signalling were also verified by dual-luciferase assay and knockdown technology. LPS significantly decreased the cell viability, increased levels of VCAM-1, SELE and ICAM-1 and also up-regulated miR-146a/b, TNF-α and IL-6 in a dose-dependent manner. Over-expression of miR-146a resulted in down-regulation of TNF-α and IL-6, as well as VCAM-1, SELE and ICAM-1, while inhibition of miR-146a led to opposite results. The dual-luciferase reporter assay showed both miR-146a and miR-146b directly targeted and negatively regulated the expression of MALAT1. Silencing of MALAT1 suppressed LPS-induced NF-κB activation and TNF-α and IL-6 secretion, reducing the cell inflammatory injury, but these changes were reversed after combined treatment with miR-146a inhibitor. Taken together, we demonstrate that miR-146 protects HMECs against inflammatory injury by inhibiting NF-κB activation. This process is modulated by MALAT1.