Manhas, V. | Search bioRxiv

bioRxiv2026

Deoxycholic Acid (DCA) a Secondary Bile Acid, Mitigates Ovariectomy-Induced Bone Loss and promotes Bone Healing: A Novel Candidate for Orthopaedic Applications

Introduction Postmenopausal osteoporosis (PMO) is a metabolic disorder, characterized by accelerated bone loss, gut microbiota (GM) dysbiosis and altered microbial metabolites. Deoxycholic acid (DCA) is a secondary bile acid with an FDA-approved drug status for submental fat treatment in adults; however its effect on bone health remains underexplored. Materials and Methods This study investigated the effects of DCA on bone health using both preclinical animal model of PMO and clinical samples from PMO women. DCA (20 mg/kg) was administered to ovariectomised (OVX) mice for 45 days, and its effects on bone microarchitecture and serum cytokines were analysed. Osteoclastogenesis and osteoblastogenesis were evaluated using murine and human samples. Untargeted and targeted metabolomics analyses were performed using an ultra-high-performance liquid chromatographic system coupled with high-resolution Orbitrap mass spectrometry (HRMS). Secondary analysis of 16S rRNA sequencing data was performed using R programming. Results GM analysis and plasma metabolomics revealed an alteration in bacterial taxa associated with secondary BA synthesis and reduced circulating DCA levels. DCA administration improved impaired trabecular and cortical bone microarchitecture in the OVX mice by inhibiting osteoclastogenesis and enhancing osteoblastogenesis. Moreover, DCA altered circulating osteoclastogenic (IL-6, Il-9, IL-17A, IFN-{gamma}, RANKL) and osteoblastogenic (OPG, TGF-{beta}, IL-10) factors. Mechanically, DCA suppressed osteoclast differentiation and the expression of genes associated with osteoclast formation (NFATC1, NFKB, TRAF6, TREM2, SYNB), fusion (CSF1R, DC-STAMP, CD47), and resorption (CTSK, ATP6VOD1, ATP6VOD2, CAR2, SPP1) in human peripheral blood mononuclear cells (PBMCs), while promoting osteogenic differentiation and matrix mineralization in bone marrow-derived mesenchymal stem cells (BMSCs) from PMO women. Additionally, DCA enhanced the nascent calcium deposition at the fracture site and improved bone healing via inhibiting osteoclastogenesis. Conclusion Overall, reduced DCA availability was associated with PMO, while DCA treatment mitigated OVX-induced bone loss and improved bone healing. This study highlights the therapeutic potential of DCA for maintaining both bone homeostasis in PMO and fracture healing with immense orthopaedic applications.

pharmacology and toxicology↗

bioRxiv2026

Vitamin D mitigates Inflammatory Bone Loss in Postmenopausal Osteoporosis via modulating the Gut-Immune-Bone axis

Osteoporosis is a prevalent skeletal disorder characterized by deterioration of bone microarchitecture and loss of bone mineral density, leading to increased fracture risk and substantial health and economic burdens, particularly among older adults. Bone remodeling is orchestrated by a complex interplay of systemic and local regulators, among which vitamin D plays a central role in maintaining skeletal homeostasis. Although numerous studies have examined the effects of vitamin D on bone metabolism, outcomes have been inconsistent across populations, dosing regimens, and experimental models. To clarify the net skeletal impact of vitamin D, we investigated its effects in postmenopausal osteoporosis (PMO). Vitamin D (1,25-dihydroxyvitamin D3- active form of vitamin D) supplementation effectively prevented bone loss in ovariectomized mice, at both lower and higher concentrations. Mechanistically, vitamin D promoted osteoclast differentiation in vitro, consistent with its RANKL-dependent pro-osteoclastogenic activity, yet paradoxically conferred bone protection in vivo. This discrepancy was explained by vitamin Ds profound immunomodulatory effects, which reshaped both innate and adaptive immune responses to suppress osteoclast formation and function. Concurrently, vitamin D improved intestinal barrier integrity and restored gut microbial composition, thereby stabilizing the gut-immune-bone axis and reducing pro-resorptive inflammatory signaling. Together, these findings demonstrate that vitamin D prevents bone loss through the coordinated regulation of immune and gut homeostasis, reconciling its apparent pro-resorptive effects in vitro with its overall anti-resorptive outcomes in vivo. This integrated mechanism highlights immune-gut microbial modulation as a key mediator of vitamin D-induced bone preservation and supports the development of vitamin D as an immunotherapeutic adjunct for the prevention and management of PMO. Altogether, our findings for the first time dissect the paradox surrounding the osteoprotective property of vitamin D supplementation. O_FIG O_LINKSMALLFIG WIDTH=186 HEIGHT=200 SRC="FIGDIR/small/735433v1_ufig1.gif" ALT="Figure 1"> View larger version (73K): org.highwire.dtl.DTLVardef@1550497org.highwire.dtl.DTLVardef@a06ab4org.highwire.dtl.DTLVardef@1bd55e5org.highwire.dtl.DTLVardef@1526acd_HPS_FORMAT_FIGEXP M_FIG O_FLOATNOGraphical Abstract:C_FLOATNO Vitamin D strengthens intestinal barrier integrity and restores gut microbial composition, which stabilizes the gut-bone axis and suppresses pro-resorptive inflammatory signaling. Vitamin D enhances osteoclastogenesis both directly and through ILC3- and Th17-mediated pathways, while inhibiting osteoclastogenesis via Treg- and Breg-dependent mechanisms. In circulation, vitamin D maintains the homeostasis between IL-10 and IL-17 cytokines. Collectively, these results indicate that vitamin D helps prevent bone loss by orchestrating the immune system and maintaining gut homeostasis. C_FIG

immunology↗