Knocking Down KCNQ1OT1 Suppressed LPS-Induced Neuroinflammation and Neuronal Apoptosis in HMC3 Cells For further exploring the function of KCNQ1OT1, we transfected HMC3 cells with pc-KCNQ1OT1 or si-KCNQ1OT1. The expression of KCNQ1OT1 was evaluated by RT-qPCR. Compared with control cells (cells transfected with pc-NC or si-NC), the expression of KCNQ1OT1 in HMC3 cells transfected with pc-KCNQ1OT1 was significantly increased, while the expression of KCNQ1OT1 in cells transfected with si-KCNQ1OT1 was significantly decreased (Figure 2A). Subsequently, we used RT-qPCR and ELISA kits to examine the expressions of TNF-α, IL-1β and IL-6 to evaluate the inflammatory response. The results indicated that LPS treatment markedly promoted the expression levels of inflammatory cytokines TNF-α, IL-1β and IL-6 in HMC3 cells; overexpression of KCNQ1OT1 promoted the expressions of inflammatory cytokines, while KCNQ1OT1 knockdown inhibited their expression (Figure 2B and C). The expression of M1 polarization marker CD86 was significantly increased with LPS treatment, and M2 polarization marker CD206 decreased notably; the overexpression of KCNQ1OT1 further promoted the expression of CD86 and inhibited CD206 expression, while KCNQ1OT1 knockdown had the opposite effects (Figure 2D and E). In addition, MTT and LDH assays were used to detect the cell survival and apoptosis. The results showed that after LPS treatment, the cell viability was markedly reduced and the LDH release was remarkably elevated; overexpression of KCNQ1OT1 promoted these effects, while knocking down KCNQ1OT1 reversed these LPS-induced effects (Figure 2F and G). In addition, KCNQ1OT1 knockout significantly reduced the generation of NO and ROS of HMC3 cells (Figure 2H and I). These results indicated that the inhibition of KCNQ1OT1 could inhibit LPS-induced activation of microglia, neuroinflammation and neuronal apoptosis in HMC3 cells.