Association of TNF-α, IGF-1, and IGFBP-1 levels with the severity of osteopenia in mice with non-alcoholic fatty liver disease

Backgrounds: Nonalcoholic fatty liver disease (NAFLD) exhibits a close association with osteoporosis. This work aims to assess the potential effects of NAFLD on the progression of osteopenia in animal models. Methods: Forty-eight C57BL/6 female mice were randomly divided to wild-type (WT) group and high fat diet (HFD) group. The corresponding detections were performed after sacrifice at 16, 24 and 32 weeks, respectively . Results: At 16 weeks, an remarkable increase of body weight and lipid aggregation in the hepatocytes of HFD group was observed compared to the WT group, while the bone structure parameters showed no significant difference. At 24 weeks, the levels of TNF-α and IL-6 in NAFLD mice were significantly increased, while the level of Osteoprotegerin (OPG) mRNA in bone tissue was decreased, and the level of receptor activator of nuclear factor Kappa-B ligand (RANKL) mRNA was increased. Meanwhile, the function of osteoclasts was increased, and the bone microstructure parameters showed significant changes. At 32 weeks, in the HFD mice, the mRNA levels of insulin-like growth factor-1 (IGF-1), Runt-related transcription factor 2 (Runx2), and Osterix (OSX) mRNA were reduced, while the insulin-like growth factor binding protein-1 (IGFBP-1) level was increased. Meanwhile, the osteoblast function was decreased, and the differences in bone structure parameters were more significant, showing obvious osteoporosis. Conclusions: The bone loss in HFD mice is pronounced as NAFLD progresses, and the changes of the TNF-α, IL-6, IGF-1, and IGFBP-1 levels may play critical roles at the different stages of NAFLD in HFD.