Protective Effect of miR-340-5p against Brain Injury after Intracerebral Hemorrhage by Targeting PDCD4

<b><i>Objective:</i></b> Intracerebral hemorrhage (ICH) is a common cerebrovascular disease. Increasing evidence has documented the crucial role of microRNAs in ICH. The present study aimed to investigate the role and underlying mechanism of miR-340-5p in ICH. <b><i>Methods:</i></b> The collagenase-induced ICH rat model was established. The neurological function of rats and the cerebral water content of rat brain tissue were measured to assess the brain injury. BV-2 cells were recruited and treated by LPS to mimic ICH-induced inflammatory response. qRT-PCR was used for the measurement of miR-340-5p. The protein levels of TNF-α, IL-6, and IL-1β were detected using ELISA. Luciferase reporter gene assay was performed to confirm the target gene. <b><i>Results:</i></b> Downregulation of miR-340-5p was detected in the serum of ICH patients and the brain tissues of ICH rats. Overexpression of miR-340-5p reversed the influence of ICH on the neurological function score and cerebral water content and inhibited the production of proinflammatory cytokines (TNF-α, IL-6, and IL-1β), which were induced by ICH in vivo. In in vitro study, levels of TNF-α, IL-6, and IL-1β were significantly enhanced in cells after LPS treatment, but these increases were eliminated by overexpression of miR-340-5p. PDCD4 was a direct target gene of miR-340-5p. <b><i>Conclusion:</i></b> miR-340-5p protects against brain injury after ICH. miR-340-5p might exert an anti-inflammatory effect during the occurrence of ICH via targeting PDCD4.