NF-κB/miR-455-5p/SOCS3 Axis Aggravates Sepsis-Induced Acute Kidney Injury through Promoting Renal Inflammation.

Introduction: Sepsis is the leading contributor to acute kidney injury (AKI), responsible for 45-70% of AKI occurrences. Despite this, septic AKI is a highly multifactorial and complex condition, and our grasp of its pathogenesis is still not fully developed. Consequently, there remains a significant gap in effective diagnostic and therapeutic strategies for septic AKI.

Methods: In the in vitro experiments, BUMPT cells were exposed to lipopolysaccharides (LPS). In vivo experiments involved inducing sepsis in mice through administration of LPS injections. Additionally, in certain experiments, either a miR-455-5p mimic or an anti-miR-455-5p LAN was administered to the mice via injections into the tail vein. The mice were then sacrificed 24 h following LPS administration for subsequent analysis.

Results: We observed a significant elevation in miR-455-5p levels within renal tubular cells following LPS-induced septic AKI. Our investigation revealed that NF-κB plays a crucial role in the upregulation of miR-455-5p. Inhibition of NF-κB using TPCA-1 prevented the rise in miR-455-5p levels in BUMPT cells (mouse proximal tubular cells from Boston University) cultured in vitro. Chromatin immunoprecipitation assays confirmed that NF-κB directly interacts with the promoter region of the miR-455-5p gene in response to LPS treatment. Functionally, introducing miR-455-5p mimics intensified cell apoptosis, kidney damage, and the production of inflammatory cytokines, while silencing miR-455-5p had protective effects in septic mice. Notably, administering anti-miR-455-5p enhanced SOCS3 expression, whereas miR-455-5p mimics reduced SOCS3 levels following LPS exposure. Furthermore, our luciferase reporter assays demonstrated that SOCS3 is a direct target of miR-455-5p.

Conclusion: This study indicates an NF-κB/miR-455-5p/SOCS3 axis which can exacerbate kidney damage by enhancing renal inflammation. This process highlights potential therapeutic targets for managing septic AKI.