Targeting Irgm1 to combat osteoporosis: suppressing ROS and restoring bone remodeling

Area of Science:

• Cell Biology
• Immunology
• Bone Biology

Background:

• Reactive oxygen species (ROS) accumulation drives osteoclast activity and bone destruction in postmenopausal osteoporosis.
• Immunity-related GTPase family M member 1 (Irgm1) influences intracellular ROS production.
• Elevated Irgm1 levels are observed in osteoporosis models.

Purpose of the Study:

• To investigate if Irgm1 deletion suppresses osteoclastogenesis via cellular redox regulation.
• To explore the role of Irgm1 in ovariectomy (OVX)-induced bone loss.
• To elucidate the molecular mechanisms by which Irgm1 affects bone metabolism.

Main Methods:

• Evaluation of Irgm1 levels in bone marrow-derived monocytes/macrophages (BMDMs) from OVX mice.
• Bioinformatics network analysis to identify key genes in osteoclast differentiation.
• Macrophage-specific Irgm1 knockout (Irgm1-cKO) in OVX mice.
• Assessment of bone loss, osteoclast differentiation, and bone resorption.
• Investigation of Irgm1 interaction with Keap1 and Nrf2 pathways.
• Analysis of osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) and M1 polarization.

Main Results:

• Irgm1 is a key upregulated gene during osteoclast differentiation.
• Macrophage-specific Irgm1 knockout significantly slowed bone loss in OVX mice.
• Loss of Irgm1 inhibited osteoclast differentiation and bone resorption by suppressing ROS accumulation.
• Irgm1 deficiency led to Keap1 downregulation, Nrf2 nuclear translocation, and activation of the antioxidant system.
• Irgm1 deficiency promoted BMSC osteogenic differentiation by inhibiting M1 polarization.

Conclusions:

• Loss of Irgm1 alleviates OVX-induced bone loss by regulating cellular redox balance and inhibiting osteoclastogenesis.
• Irgm1 deficiency enhances the antioxidant system and promotes osteogenesis.
• Irgm1 represents a promising novel therapeutic target for osteoporosis treatment.