miR-142a-3p Enhances FlaA N/C Protection Against Radiation-Mediated Intestinal Injury by Modulating the IRAK1/NF-κB Signaling Pathway

Abstract

Purpose: Our purpose was to investigate the role of recombinant protein flagellin A N/C (FlaA N/C) protein-mediated pyroptosis inhibition and related miRNA in radiation protection.

Methods and materials: Mice received 10 Gy irradiation after FlaA N/C pretreatment, IRAK-1/4 Inhibitor I treatment, or pyrrolidine dithiocarbamate treatment. Human intestinal epithelial cells (HIEC) received 10 Gy irradiation after FlaA N/C pretreatment, overexpressed miR-142a-3p with miR-142a-3p mimics, or inhibited miR-142a-3p with miR-142a-3p inhibitor. Mouse & Rat miRNA OneArray determined the change in relevant miRNA after FlaA N/C pretreatment; real-time polymerase chain reaction detected IRAK1 and miR-142a-3p expression; a CCK-8 assay evaluated cell viability; LDH release analyzed cytotoxicity; caspase-1 activity assay, interleukin-1β level, and flow cytometry analyzed pyroptosis in cells; hematoxylin-eosin staining evaluated the damage to intestinal tissue; CO-IP detected the inflammation activation; immunohistochemistry, Western blot analysis, and immunofluorescence analyzed activation of pyroptosis-related proteins and the activation of NF-kB signaling pathways; and luciferase reporter assay and fluorescence in situ hybridization detected the interaction between miR-142a-3p and IRAK1.

Results: FlaA N/C reduced radiation-induced pyroptosis in vivo and in vitro, and miR-142a-3p expression increased after FlaA N/C pretreatment. Upregulating the expression of miR-142a-3p inhibited radiation-induced pyroptosis in HIEC, and downregulating the expression of miR-142a-3p led to radiation-induced pyroptosis in HIEC after FlaA N/C pretreatment. IRAK1 was a direct target of miR-142a-3p and played an important role in radiation-induced pyroptosis in HIEC. Inhibiting IRAK1 reduced radiation-mediated pyroptosis in mice intestines. miR-142a-3p downregulated IRAK1 and suppressed the NF-kB pathway. Inhibiting the NF-kB signaling pathway can reduce radiation-mediated pyroptosis in mice intestines.

Conclusions: Our findings indicated this new radioprotectant protein regulates miR-142a-3p, effectively inhibiting radiation-induced pyroptosis mediated by the IRAK1/NF-κB signaling pathway in intestinal cells.