Bone transcriptomics reveals that juzentaihoto remodels and activates multiple pathways in Klotho-deficient mice

Aging-related osteoporosis arises from an imbalance between bone formation and resorption. The traditional Japanese Kampo formula juzentaihoto (JTT) is used in the clinic to improve imbalances in systemic homeostasis, especially in elderly individuals; however, its effects on age-associated bone loss remain unclear. Here, we confirmed the effect of JTT on the osteoporotic phenotype in a model of aging, and explored its underlying mechanisms through transcriptomic analysis.

Klotho-deficient mice, which have a shortened lifespan and display an aging-like phenotype that includes osteoporosis, were analyzed. Femoral bone mineral density (BMD) and cortical parameters were assessed by micro-computed tomography. RNA sequencing of femoral tissue was performed to identify differentially expressed genes in response to JTT administration, followed by Gene Ontology analysis and validation by RT-qPCR.

JTT treatment attenuated the decreased in BMD and cortical bone mass and increased cortical void volume, suggesting the potentially reflecting a reactivation of bone remodeling. Consistent with these findings, JTT restored the expression of genes involved in collagen biosynthesis, osteoblast differentiation, mineralization, and transcription factor NFATc1-centered osteoclast maturation. JTT also attenuated aberrant neurotransmitter-related signaling and induced the expression of genes encoding antioxidant enzymes, suggesting additional supportive effects on skeletal homeostasis. These changes occurred without recovery of the Klotho-fibroblast growth factor 23 (FGF23) or vitamin D pathways.

JTT ameliorates low-turnover osteoporosis in Klotho-deficient mice by modulating multiple regulatory pathways that collectively promote bone remodeling. These multitarget actions highlight the therapeutic potential of JTT for age-related bone fragility and other conditions characterized by impaired bone formation.