The Effects of <i>Lactobacillus rhamnosus</i> GG on Mechanical Properties of Long Bones and Body Composition in Immunodeficient Mice

This study aimed to assess whether a daily supplementation with Lactobacillus rhamnosus GG (LGG) can alter the body composition as well as bone turnover and the mechanical properties of the bones in systemic immunodeficiency. For this, we use an in vivo model of severe combined immunodeficient (scid) mice supplemented daily with LGG over 8 weeks period. After 8 weeks of the treatment, the animals were assessed by DEXA and then the blood was collected from the hepatic portal vein for bone turnover biomarkers; post-mortem, the caecum was removed for isolation and enumeration of the gut bacteria, while femurs/tibiae were excised for the assessment of their mechanical properties. LGG treatment affected the composition of the gut microbiota at the order level, and it decreased (P = 0.002) total adipose tissue content. Moreover, LGG treatment decreased the stiffness (N/mm) of both femurs (P = 0.008) and tibiae (P = 0.011). To conclude, this study shows that dietary supplementation with LGG in immunodeficient animals can alter mechanical properties of the long bones and concomitantly it can modify host’s total adiposity level.