MicroRNA-18a regulates the Pyroptosis, Apoptosis, and Necroptosis (PANoptosis) of osteoblasts induced by tumor necrosis factor- via hypoxia-inducible factor-1

Background: Tumor necrosis factor-alpha (TNF-alpha) is involved in inflammatory responses and promotes cell death and the inhibition of osteogenic differentiation. MicroRNA (miRNA) plays a crucial role in the infected bone diseases, however, the biological role of miRNAs in inflammation-induced impaired osteogenic differentiation remains unclear. This study aimed to explore the role of miRNA-18a-5p (miR-18a) in regulating PANoptosis and osteogenic differentiation in an inflammatory environment via hypoxia-inducible factor-1 alpha (HIF1-alpha). Methods: The expression of miR-18a in MC3T3-E1 cells was analyzed using quantitative reverse transcription-polymerase chain reaction in an inflammatory environment induced by TNF-alpha. The expression of HIF1-alpha and NLRP3 in LV-miR-18a or sh-miR-18a cells was analyzed using western blotting. Fluorescence imaging for cell death, flow cytometry, and alkaline phosphatase activity analysis were used to analyze the role of miR-18a in TNF-alpha-induced PANoptosis and the inhibition of osteogenic differentiation. An animal model of infectious bone defect was established to validate the regulatory role of miR-18a in an inflammatory environment. Results: The expression of miRNA-18a in the MC3T3-E1 cell line was significantly lower under TNF-alpha stimulation than in the normal environment. miR-18a significantly inhibited the expression of HIF1-alpha and NLRP3, and inhibition of HIF1-alpha expression further inhibited NLRP3 expression. Furthermore, inhibition of miR-18a expression promoted the TNF-alpha-induced PANoptosis and inhibition of osteogenic differentiation, whereas miR-18a overexpression and the inhibition of both HIF1-alpha and NLRP3 reduced the effects of TNF-alpha. These findings are consistent with those of the animal experiments. Conclusion: miRNA-18a negatively affects HIF1-alpha/NLRP3 expression, inhibits inflammation-induced PANoptosis, and impairs osteogenic differentiation. Thus, it is a potential therapeutic candidate for developing antiinflammatory strategies for infected bone diseases.