| Objective To investigate the effect of pretreatment with receptor activator of nuclear factor kappa B ligand (RANKL) on sepsis associated acute lung injury (SA-ALI) and explore its possible mechanism of action through inflammatory response. Methods Twentyfour male C57BL/6 mice were randomly divided into sham operation group, CLP group, RANKL group, and anti RANKL group. Each group consists of six animals. Each group of mice was given pre-treatment. The RANKL group and anti RANKL group were intraperitoneally injected with recombinant RANKL and anti RANKL antibodies, while the sham surgery group and CLP group were given equal amount of physiological saline. One hour later, the sham surgery group opened the abdomen, flipped the cecum, and closed the abdomen. The other groups used cecal ligation and puncture (CLP) to establish the SA-ALI model. After 24 hours of modeling, the mice were euthanized and samples were taken. HE staining method was used to detect pathological changes in lung tissue; Enzyme linked immunosorbent assay was used to detect the levels of IL- 6, TNF - α, and IL-1 β in serum; Real time fluorescence quantitative PCR and protein immunoblotting were used to detect the mRNA and protein expression levels of RANKL, RANK, and Toll like receptor 4 (TLR4) in lung tissue. Results In the CLP induced SA-ALI mouse model, there was significant infiltration of inflammatory cells in the lung tissue, and the levels of IL-6, TNF - α, and IL-1 β in the serum increased compared to the sham operation group. After RANKL pretreatment, the pathological damage to lung tissue was reduced, and the levels of IL-6, TNF - α, and IL-1 β in serum, as well as the protein and mRNA expression of RANK and TLR4 in lung tissue decreased compared to the CLP group. The expression of RANKL protein and mRNA increased. After treatment with anti RANKL, the pathological damage to the lung tissue of mice worsened, and the levels of IL-6, TNF - α, and IL-1 β in serum, as well as the protein and mRNA expression of RANK and TLR4 in lung tissue increased compared to the CLP group. The expression of RANKL protein and mRNA decreased, with P values less than 0.05, indicating statistical significance. Conclusion Pretreatment with RANKL can alleviate lung injury in SA-ALI mice by regulating inflammatory response, and its mechanism may be related to the RANKL/RANK/TLR4 signaling pathway. |
