Lactobacillus rhamnosus attenuates bone loss and maintains bone health by skewing Treg-Th17 cell balance in Ovx mice

Osteoporosis is a systemic-skeletal disorder characterized by enhanced fragility of bones leading to increased rates of fractures and morbidity in large number of populations. Probiotics are known to be involved in management of various-inflammatory diseases including osteoporosis. But no study till date had delineated the immunomodulatory potential of Lactobacillus rhamnosus (LR) in bone-health. In the present study, we examine the effect of probiotic-LR on bone-health in osteoporotic (Ovx) mice model. We observed that administration of LR attenuated bone-loss in Ovx mice. Both the cortical and trabecular bone-content of LR treated group was significantly higher than Ovx-group. Remarkably, the percentage of osteoclastogenic-CD4+Rorγt+Th17 cells at distinct immunological sites such as BM, spleen, LN and PP were significantly reduced, whereas the percentage of anti-osteoclastogenic-CD4+Foxp3+Tregs and CD8+Foxp3+Tregs were significantly enhanced in LR-treated group thereby resulting in inhibition of bone-loss. The immunomodulatory-role of LR was further supported by serum-cytokine data with a significant reduction in proinflammatory-cytokines (IL-6, IL-17 and TNF-α) along with enhancement in anti-inflammatory-cytokines (IL-10, IFN-γ) in LR treated-group. Altogether, the present study for the first time establishes the osteoprotective role of LR on bone-health, thus highlighting the potential of LR in the treatment and management of various bone related diseases including osteoporosis.