Panax quinquefolius-derived nanovesicles: a synergistic nanotherapy for postmenopausal osteoporosis via modulating gut microbiota, MYC-mediated inflammation, and Nrf2/HO-1 antioxidant pathway.

BACKGROUND

Plant-derived nanovesicles (NVs) have emerged as promising natural nanotherapeutics for metabolic and inflammatory diseases due to their inherent biocompatibility, multi-target potential, and ability to mediate cross-kingdom communication. Postmenopausal osteoporosis (PMOP), a prevalent skeletal disorder driven by estrogen deficiency, is characterized by gut-bone axis dysregulation, chronic inflammation, and excessive oxidative stress-pathological features that demand synergistic multi-target interventions. This study aimed to characterize Panax quinquefolius-derived nanovesicles (PQs) and systematically validate their anti-osteoporotic efficacy, bone-targeting property, and underlying molecular mechanisms in preclinical models.

METHODS

PQs were isolated via modified differential centrifugation and characterized using transmission electron microscopy (TEM), nanoparticle tracking analysis (NTA), and high-performance liquid chromatography (HPLC). Their bone-targeting capacity was evaluated via in vivo biodistribution and cellular uptake assays. Anti-osteoporotic efficacy was assessed in ovariectomized (OVX) mice using dual-energy X-ray absorptiometry (DXA), micro-computed tomography (μCT), and histomorphometric analysis. Gut microbiota modulation was analyzed via 16S rRNA gene sequencing. Network pharmacology, molecular docking, and loss-of-function experiments (pharmacological inhibition and siRNA-mediated Nrf2 silencing) were employed to elucidate the core mechanisms.

RESULTS

PQs exhibited a typical cup-shaped morphology (mean diameter ~89 nm), negative zeta potential (-42.21 ± 0.12 mV), and stable batch-to-batch naringin content (0.65 ± 0.03 μg/mL). In vivo studies confirmed intrinsic bone-targeting of PQs, with >35% uptake by mouse bone marrow mesenchymal stem cells (mBMSCs) at 48 h post-injection. In OVX mice, PQs dose-dependently improved bone mineral density (BMD), trabecular microarchitecture (increased BV/TV, Tb. N, Tb. Th; decreased Tb. Sp), and serum osteogenic markers (ALP, OCN, Ca), while reducing osteoclastic markers (TRAP5b, CTX-I) and systemic inflammation (IL-6, KC, LPS). PQs treatment was associated with normalization Firmicutes/Bacteroidetes ratio, enriching probiotics (Bifidobacterium, Lactobacillus), and suppressing pathogenic bacteria (Desulfovibrio, Enterococcus). Mechanistically, PQs exerted therapeutic effects by synergistically suppressing MYC-mediated inflammatory signaling and activating the Nrf2/HO-1 antioxidant pathway. Pharmacological inhibition (ML385 for Nrf2, HY-11798 for HO-1) or genetic silencing of Nrf2 completely abolished the osteoprotective, anti-inflammatory, and antioxidant effects of PQs.

CONCLUSION

Panax quinquefolius-derived nanovesicles represent a novel synergistic nanotherapy for PMOP. Their therapeutic effects are mediated by concurrent modulation of gut microbiota homeostasis, suppression of MYC-dependent inflammation, and activation of the Nrf2/HO-1 pathway. Given their natural origin, biocompatibility, and multi-target action, PQs hold significant potential for clinical translation as a safe and effective alternative for PMOP management.