Clinical Report: Targeting bone marrow pathway may curb bone loss

Overview

In male mouse models, bone marrow macrophage STING signaling increased with age and was linked to inflammatory changes, NAD+ depletion, and impaired osteogenic function. Genetic or pharmacologic targeting of the STING–CD38 pathway attenuated age-related bone loss in these preclinical experiments; efficacy and safety in humans have not been established.

Background

Osteoporosis is a chronic metabolic bone disease associated with fracture burden, and its molecular mechanisms include bone remodeling and communication among bone-cell populations. The supplied related review describes advances in understanding these pathways, while the present study examines age-related changes in the bone marrow microenvironment. The study focused on interactions among marrow adipocytes, macrophages, and mesenchymal stem cells, and on how STING signaling may affect bone formation. Its findings are from mouse and cellular experiments rather than clinical trials.

Data Highlights

Key Findings

• STING signaling in bone marrow macrophages progressively increased with age in the mouse experiments.
• Myeloid-specific STING deletion was associated with lower bone mass in early adulthood but attenuated bone loss from 10 to 24 months; the higher bone mass at 24 months was not statistically significant.
• Macrophage-targeted STING knockdown from 12 to 18 months improved several microcomputed tomography measures and was accompanied by increased bone formation and reduced marrow adipocyte accumulation.
• Soluble DPP4 from aging marrow adipocytes interacted with macrophage Toll-like receptor 4 and, together with accumulated mitochondrial DNA, contributed to STING activation.
• Downstream CD38 activity was reported to amplify inflammation and reduce NMN availability, impairing NAD+ metabolism and mitochondrial function in neighboring mesenchymal stem cells.
• H-151 plus NMN and macrophage-targeted CD38 knockdown each attenuated skeletal deterioration in mice; the combination experiment did not establish the separate contribution of either treatment.

Clinical Implications

The study provides preclinical evidence for a role of the STING–CD38 pathway in age-related changes to the bone marrow microenvironment, but it does not establish efficacy or safety in humans. The supplied current-guidance context describes osteoporosis screening and approved antiresorptive and osteoanabolic treatment approaches; it does not discuss STING-targeted therapies.

Conclusion

In these mouse and cellular models, targeting STING-associated signaling was linked to reduced age-related bone loss and improved measures of bone formation and microarchitecture. Translation to human care remains unestablished, and the study’s stated model and intervention limitations constrain interpretation.

Related Resources & Content

1. Bone Marrow Macrophage STING Signaling is a Direct Nexus Linking Marrow Adipose Expansion to NAD+ Depletion and Osteogenic Decline in Skeletal Aging, PMC, year not provided
2. Frontiers in Endocrinology, 2026 — Understanding Molecular Pathways and Future Applications in Osteoporosis Management
3. United States Preventive Services Task Force, 2025 — Final Recommendation Statement: Osteoporosis to Prevent Fractures: Screening
4. ASCO Publications — Targeting the RANKL Pathway: Putting the Brakes on Prostate Cancer Progression in Bone
5. ASCO Publications — Targeting the RANKL Pathway: Putting the Brakes on Prostate Cancer Progression in Bone
6. ASCO Publications — Bone marrow vascular architecture: Implications for targeting bone marrow cancers.
7. Bone Marrow Macrophage STING Signaling is a Direct Nexus Linking Marrow Adipose Expansion to NAD+ Depletion and Osteogenic Decline in Skeletal Aging
8. Understanding Molecular Pathways and Future Applications in Osteoporosis Management
9. Final Recommendation Statement: Osteoporosis to Prevent Fractures: Screening
10. Final Recommendation Statement: Osteoporosis to Prevent Fractures: Screening | United States Preventive Services Taskforce
11. Potent bisphosphonate therapy for preventing fractures after denosumab discontinuation in osteoporosis: A GRADE-assessed systematic review and meta-analysis - PMC
12. Bone Marrow Macrophage STING Signaling is a Direct Nexus Linking Marrow Adipose Expansion to NAD+ Depletion and Osteogenic Decline in Skeletal Aging - PMC