LncRNA HOTAIR/miR-9-5p/FOXP1 axis modulates cerebral ischemia-reperfusion injury via NLRP3 inflammasome activation.

OBJECTIVE

This study aimed to investigate the association between the HOTAIR-miR-9-5p axis and the inflammatory response in ischemic stroke (IS) and elucidate the underlying molecular mechanisms.

METHODS

Middle cerebral artery occlusion/reperfusion (MCAO/R) and oxygen-glucose deprivation/reoxygenation (OGD/R) were applied to simulate ischemic/reperfusion conditions in vivo and in vitro. The expression levels of HOTAIR and miR-9-5p in the serum of patients or in the brain tissue of MCAO/R mice were assessed by qRT-PCR, and the secretion levels of IL-1β and IL-18 were analyzed by ELISA. Dual-luciferase reporter assays, RNA-binding protein immunoprecipitation (RIP), and RNA pull-down assays were performed to validate the target relationship. Western blotting was applied to assess the expression of NLRP3, CASP1, and FOXP1. Moreover, MCAO/R mice with intracerebroventricular injection of antagomir-9-5p were used to evaluate the effect of antagomir-9-5p on cerebral ischemia-reperfusion injury (CIRI).

RESULTS

A significant association was observed between the HOTAIR-miR-9-5p axis and inflammation in both IS patients and MCAO/R mice. HOTAIR was abnormally expressed at a low level, whereas miR-9-5p and the associated protein NLRP3 inflammatory response were increased in the serum of IS patients, as well as in the brain tissue of MCAO/R mice and in SH-SY5Y cells. Mechanistically, miR-9-5p negatively regulated the expression of HOTAIR and FOXP1. Furthermore, HOTAIR was found to regulate NLRP3 expression via the miR-9-5p/FOXP1 pathway. Functional experiments revealed that silencing miR-9-5p protected against cerebral ischemia/reperfusion injury and suppressed NLRP3 inflammasome activation.

CONCLUSION

These findings collectively demonstrate that the HOTAIR/miR-9-5p/FOXP1 axis plays a critical role in NLRP3 inflammasome activation following IS, suggesting that its blockade could be a potential therapeutic strategy for ischemic brain injury.