Leukemia inhibitory factor protects against experimental periodontitis through immuno‐modulations of both macrophages and periodontal ligament fibroblasts

Abstract Background To explore the role of leukemia inhibitory factor (LIF) in periodontitis via in vivo and in vitro experiments. Methods The second upper molar of LIF knockout mice and their wild‐type littermates were ligated for 8 days. Micro‐computed tomography (micro‐CT), histological analysis, and quantitative real‐time polymerase chain reaction (qRT‐PCR) were performed. The expression levels of proinflammatory cytokines were examined in mouse bone marrow derived macrophages and human periodontal ligament fibroblasts (HPDLFs) after lipopolysaccharide (LPS) treatment. Results LIF deficiency promoted alveolar bone loss, inflammatory cells infiltration, osteoclasts formation and collagen fiber degradation in ligature‐induced mouse, along with higher expressions of proinflammatory cytokines, including interleukin‐6 (IL6), IL‐1β (IL1B), tumor necrosis factor‐α (TNFA), matrix metalloproteinase 13 (MMP13), and RANKL/OPG ratio. Additionally, LIF deletion led to higher expression levels of these proinflammatory cytokines in mouse bone marrow‐derived macrophages from both femur and alveolar bone and HPDLFs when treated with LPS. Administration of recombined LIF attenuated TNFA, IL1B , and RANKL/OPG ratio in HPDLFs. Conclusions These findings indicate that LIF deficiency promotes the progress of periodontitis via modulating immuno‐inflammatory responses of macrophages and periodontal ligament fibroblasts, and the application of LIF may be an adjunctive treatment for periodontitis to resolute inflammation.