Silencing miR-155-5p expression improves intestinal damage through inhibiting inflammation and ferroptosis in necrotizing enterocolitis

Background: Necrotizing enterocolitis (NEC) is a condition characterized by acquired damage to the mucosal lining, predominantly affecting premature infants. Bioinformatics assessments uncovered a notable rise in miR-155-5p expression in the intestinal tissues of infants suffering from NEC. Nevertheless, the development of NEC's underlying mechanisms and the role of miR-155-5p are still not well understood. This research aimed to explore the role of miR-155-5p in NEC and to elucidate its underlying mechanisms. Methods: To replicate NEC in vitro, lipopolysaccharide (LPS) was employed, whereas an in vivo rat model of NEC was established using formula feeding and exposure to hypoxia. Subsequently, levels of inflammatory cytokines, cell survival, and apoptosis rates were assessed. Various biochemical indicators such as glutathione (GSH), superoxide dismutase (SOD), catalase (CAT), and malondialdehyde (MDA) were measured utilizing a purchased diagnostic kit. For the assessment of reactive oxygen species (ROS) and mitochondrial membrane potential (MMP) within FHC cells, analysis by flow cytometry was conducted. Additionally, the technique of Western blotting was utilized to analyze the levels of ferroptosis-associated proteins. Moreover, hematoxylin and eosin (H&E) staining was carried out to observe the histopathological alterations in the intestinal tissue samples from rats with necrotizing enterocolitis (NEC). Results: Reducing miR-155-5p improved the survival of FHC cells exposed to LPS, decreased cell apoptosis, inflammation, and ferroptosis, and mitigated intestinal damage in NEC rats. Furthermore, SLC7A11 was found to be a direct target of miR-155-5p. The inhibition of miR-155-5p decreased LPS-induced inflammation and ferroptosis in both FHC cells and NEC rats by promoting SLC7A11 expression. This effect was evidenced by increased levels of ferroptosis-related proteins FTH1 and GPX4, decreased COX-2 and ACSL4 levels, lower lipid peroxidation marker MDA, reduced antioxidant markers GSH, SOD, and CAT, fewer IL-6 and TNF-alpha, and suppression of the I kappa B alpha/NF-kappa B p65 signaling pathway. Conclusions: In conclusion, reducing miR-155-5p could improve intestinal damage in NEC by inhibiting inflammation and ferroptosis. These findings may provide theoretical insights for the development of new therapies for NEC.