Neutrophil-derived thrombospondin-1 (THBS1) drives type 2 diabetes-induced osteoporosis via CD36-PPARγ-POU2F2 signaling.

OBJECTIVE

Type 2 diabetes (T2D) is associated with osteoporosis. Although chronic inflammation and immune dysregulation are implicated in T2D-induced bone loss, the specific roles of immune cells remain poorly understood. This study aimed to investigate how neutrophils in T2D contribute to osteoporosis and to identify the underlying molecular mechanisms and potential therapeutic targets.

METHODS

We utilized a combination of in vivo and in vitro approaches, including T2D and control mouse models, primary cell cultures, and publicly available single-cell RNA sequencing data from the GEO database. Osteoporosis was assessed through TRAP staining, micro-CT imaging, and quantitative PCR. Molecular interactions were examined using Western blotting, chromatin immunoprecipitation followed by qPCR, and flow cytometry. Additionally, virtual screening was employed to identify potential inhibitors of thrombospondin-1(THBS1).

RESULTS

Neutrophils isolated from T2D mice promoted osteoclast activity and bone loss when transferred into wild-type mice, as evidenced by increased TRAP-positive cells and deteriorated bone microarchitecture. We identified THBS1, a glycoprotein secreted at higher levels by T2D neutrophils, as a mediator of osteoclast differentiation. THBS1 engaged the CD36 receptor on macrophages, activating PPARγ, which transcriptionally upregulates POU2F2-a transcription factor that enhances osteoclastogenesis via c-FOS induction. Genetic ablation of THBS1 attenuated osteoclast formation and bone loss in T2D mice. Virtual screening identified nasunin as a potent THBS1 inhibitor. Treatment with nasunin suppressed the CD36-PPARγ-POU2F2-c-FOS axis, reduced osteoclast differentiation in vitro, and ameliorated T2D-induced osteoporosis in vivo.

CONCLUSION

Our findings reveal a novel pathway through which neutrophil-derived THBS1 exacerbates diabetic osteoporosis by promoting osteoclastogenesis via CD36-PPARγ-POU2F2 signaling.