Related Experiment Video
Updated: Jun 30, 2025
Author Spotlight: Developing a Rat Model for Weight-Bearing Intervention to Investigate Osteonecrosis of the Femoral Head
Published on: September 27, 2024
Excess glucocorticoids inhibit murine bone turnover via modulating the immunometabolism of the skeletal
Xu Li1,2, Tongzhou Liang1,2, Bingyang Dai1,2
1Musculoskeletal Research Laboratory, Department of Orthopedics and Traumatology, Faculty of Medicine.
Abstract:
Elevated bone resorption and diminished bone formation have been recognized as the primary features of glucocorticoid-associated skeletal disorders. However, the direct effects of excess glucocorticoids on bone turnover remain unclear. Here, we explored the outcomes of exogenous glucocorticoid treatment on bone loss and delayed fracture healing in mice and found that reduced bone turnover was a dominant feature, resulting in a net loss of bone mass. The primary effect of glucocorticoids on osteogenic differentiation was not inhibitory; instead, they cooperated with macrophages to facilitate osteogenesis. Impaired local nutrient status - notably, obstructed fatty acid transportation - was a key factor contributing to glucocorticoid-induced impairment of bone turnover in vivo. Furthermore, fatty acid oxidation in macrophages fueled the ability of glucocorticoid-liganded receptors to enter the nucleus and then promoted the expression of BMP2, a key cytokine that facilitates osteogenesis. Metabolic reprogramming by localized fatty acid delivery partly rescued glucocorticoid-induced pathology by restoring a healthier immune-metabolic milieu. These data provide insights into the multifactorial metabolic mechanisms by which glucocorticoids generate skeletal disorders, thus suggesting possible therapeutic avenues.
Insights
Glucocorticoids reduce bone turnover, causing bone loss and delayed healing by impairing fatty acid transport. Restoring fatty acid metabolism in macrophages partially reversed these effects, offering new therapeutic strategies for glucocorticoid-induced skeletal disorders.
Area of Science:
- Biochemistry
- Bone Biology
- Immunometabolism
Background:
- Glucocorticoids are known to cause skeletal disorders characterized by increased bone resorption and decreased bone formation.
- The precise mechanisms by which excess glucocorticoids impact bone turnover remain incompletely understood.
Purpose of the Study:
- To investigate the direct effects of exogenous glucocorticoid treatment on bone loss and fracture healing in a mouse model.
- To elucidate the role of nutrient status, specifically fatty acid transport and metabolism, in glucocorticoid-induced bone pathology.
Main Methods:
- Administration of exogenous glucocorticoids to mice to induce bone loss and delayed fracture healing.
- Analysis of bone turnover markers and osteogenic differentiation.
- Investigation of macrophage function and fatty acid metabolism in the bone microenvironment.
- Assessment of therapeutic interventions involving localized fatty acid delivery.
Main Results:
- Glucocorticoid treatment led to reduced bone turnover, net bone mass loss, and delayed fracture healing.
- Glucocorticoids did not directly inhibit osteogenic differentiation but rather cooperated with macrophages to facilitate it.
- Impaired fatty acid transport and oxidation in macrophages were identified as key factors in glucocorticoid-induced bone turnover impairment.
- Targeted delivery of fatty acids partially rescued the glucocorticoid-induced pathology by improving the immune-metabolic environment.
Conclusions:
- Glucocorticoids induce skeletal disorders through multifactorial metabolic mechanisms, primarily involving impaired fatty acid metabolism and altered macrophage function.
- Fatty acid oxidation within macrophages is crucial for glucocorticoid receptor-mediated BMP2 expression and osteogenesis.
- Metabolic interventions targeting fatty acid delivery present a promising therapeutic strategy for mitigating glucocorticoid-induced bone damage.
Related Concept Videos
01:29Bone Disorders
Bone deposition is also affected by the levels of sex hormones like estrogen and testosterone that promote osteoblast activity and bone matrix synthesis. When the level of these hormones decreases due to aging, it causes a reduction in bone deposition. As a result, bone resorption by osteoclasts...
01:31Osteoclasts in Bone Remodeling