The molecular mechanisms of probiotic strains in improving ageing bone and muscle of d‐galactose‐induced ageing rats.

Aim: The aim of this study was to evaluate the molecular mechanisms of Lactobacillus strains in improving ageing of the musculoskeletal system. Methods and Results: The anti‐ageing mechanism of three probiotics strains Lactobacillus fermentum DR9, Lactobacillus paracasei OFS 0291 and L. helveticus OFS 1515 were evaluated on gastrocnemius muscle and tibia of d‐galactose‐induced ageing rats. Upon senescence induction, aged rats demonstrated reduced antioxidative genes CAT and SOD expression in both bone and muscle compared to the young rats (P < 0·05). Strain L. fermentum DR9 demonstrated improved expression of SOD in bone and muscle compared to the aged rats (P < 0·05). In the evaluation of myogenesis‐related genes, L. paracasei OFS 0291 and L. fermentum DR9 increased the mRNA expression of IGF‐1; L. helveticus OFS 1515 and L. fermentum DR9 reduced the expression of MyoD, in contrast to the aged controls (P < 0·05). Protective effects of L. fermentum DR9 on ageing muscle were believed to be contributed by increased AMPK‐α2 expression. Among the osteoclastogenesis genes studied, TNF‐α expression was highly elevated in tibia of aged rats, while all three probiotics strains ameliorated the expression. Lactobacillus fermentum DR9 also reduced the expression of IL‐6 and TRAP in tibia when compared to the aged rats (P < 0·05). All probiotics treatment resulted in declined proinflammatory cytokines IL‐1β in muscle and bone. Conclusions: Lactobacillus fermentum DR9 appeared to be the strongest strain in modulation of musculoskeletal health during ageing. Significance and Impact of the Study: The study demonstrated the protective effects of the bacteria on muscle and bone through antioxidative and anti‐inflammatory actions. Therefore, L. fermentum DR9 may serve as a promising targeted anti‐ageing therapy. [ABSTRACT FROM AUTHOR]