miR-146b-3p regulates PI3K/AKT signaling pathway in septic mice with acute respiratory distress syndrome

Abstract

Background: This study aimed to explore the effect of miR-146b-3p on acute respiratory distress syndrome in septic mice by regulating PI3K/AKT signaling pathway. Methods: Seventy C57BL/6 mice were divided into normal group ( n = 10) and modeling group ( n = 60, mice for constructing septic mice models with acute respiratory distress syndrome). Model mice were subdivided into model group (without any treatment), negative control (NC) mimic group (injection with miRNA NC), miR-146b-3p mimic group (injection with miR-146b-3p mimic), si-NC group (injection with PI3Kγ siRNA NC), si-PI3Kγ group (injection with PI3Kγ interference sequence), and miR-146b-3p mimic + oe-PI3Kγ group (injection with miR-146b-3p mimic + PI3Kγ overexpression plasmid). Dual-luciferase reporter assay was conducted to determine the target relationship between miR-146b-3p and PI3Kγ. Wet weight/dry weight (W/D) ratio of the left lung was measured. Hematoxylin and eosin stain was used to detect the pathological change of mouse lung. ELISA was employed to measure serum interleukin (IL) -1β and IL-18 levels. miR-146b-3p and PI3Kγ expressions were detected by qRT-PCR. PI3Kγ, AKT, NLRP3, apoptosis-associated speck-like protein caspase recruitment domain (ASC) and Caspase-1 protein expressions were detected by Western blotting. Results: miR-146b-3p negatively regulated PI3Kγ. The lung tissues in other groups compared with normal group had down-regulated miR-146b-3p, up-regulated PI3Kγ, p-AKT, ASC, NLRP3 and Caspase-1 proteins, higher W/D ratio, and more serum IL-1β and IL-18 (all P < 0.05). All indicators in miR-146b-3p mimic group and si-PI3Kγ group were significantly improved as compared to model group (all P < 0.05). Up-regulated PI3Kγ, p-AKT, ASC, NLRP3 and Caspase-1 proteins and higher W/D ratio and IL-1β and IL-18 levels in serum existed in miR-146b-3p mimic + oe-PI3Kγ group compared with miR-146b-3p mimic group (all P < 0.05). Conclusions: Up-regulation of miR-146b-3p can restrain PI3K/AKT signaling pathway, thereby improving acute respiratory distress syndrome in septic mice.