miR146a/circKMT2c regulates inflammation in fracture-induced acute lung injury via p65 nuclear translocation

Surgical intervention for fractures in elderly patients may lead to severe complications, notably acute lung injury (ALI). miR146a, a microRNA regulating cellular physiological activities, plays a crucial role in maintaining immune homeostasis and modulating inflammatory responses. circKMT2c, a non-coding circular RNA that functions as a competitive endogenous RNA by binding to miRNA response elements, regulates mRNA expression. In this study, we investigated whether the interaction between miR146a and circKMT2c modulates ALI induced by postoperative inflammatory responses. We assessed the inflammatory response using both the LPS-induced in vitro cellular model and a fracture-induced in vivo rat model. In distinct experimental groups, we evaluated postoperative inflammatory factors, lung injury severity, and expression level of p65 in lung tissue. Notably, ALI was significantly attenuated by either inhibiting miR146a or up-regulating circKMT2c. Our findings demonstrate that miR146a level was significantly elevated in response to LPS stimulation or fracture surgery. miR146a suppressed circKMT2c expression and promoted the release of inflammatory factors. Inhibition of miR146a expression reduced inflammatory factor production in lung tissue macrophages, consequently attenuating lung injury. Furthermore, the NF-κB/p65 signaling pathway mediates both the release of inflammatory factors and the exacerbation of lung injury. In the context of fracture surgery-induced ALI, the miR146a/circKMT2c regulates NF-κB p65 nuclear translocation, thereby driving pro-inflammatory cytokine release from lung tissue macrophages.