A new study shows that a bacterium present in the intestinal microbiota can influence the immune system and disrupt bone growth after puberty.
Depression or anxiety, health of the arteries… The role of the bacteria populating our intestines, of our microbiome, is multiple. It can actually regulate our biological functions, including the skeleton. Researchers from the Medical University of South Carolina (USA) examined the influence of specific bacteria, segmented filamentous bacteria, on post-pubertal skeletal development. Their results, published in the Journal of Bone and Mineral Research More, demonstrates that these bacteria increase the response of immune cells located in the intestine and the liver. This disrupts the buildup of bone mass.
“This is the first known report to show that within the gut microbiota, specific microbes have the ability to achieve normal skeletal growth and maturation,” says Chad M. Novince, lead author of the study. With his team, he focuses on post-pubertal skeletal development. During this period, a person’s bone mass increases by 40%. To analyze the effects of segmented filamentous bacteria on skeletal health, the researchers worked on mice with a defined microbiota.
An imbalance “detrimental to the skeleton”
One group of mice had segmented filamentous bacteria, and the other lacked them. The composition of a bone is based on the balance between osteoblasts and osteoclasts. Osteoblasts participate in bone formation and osteoclasts participate in bone resorption, which is necessary to maintain bone strength. “Colonization by the segmented filamentous bacteria caused a shift on both sides of the axis: osteoclast activity increased and osteoblast activity decreased, which is detrimental to the skeleton,” Prof. Novince describes.
Additionally, the researchers found that the presence of segmented filamentous bacteria boosted hepatic immunity. In particular, they have allowed the increase of immune factors, which are produced in the liver. Among these factors is lipocalin-2, which influences bone metabolism. These results demonstrate that segmented filamentous bacteria have effects in the intestine, but also in the liver, which influences bone metabolism.
Altering the microbiome to preserve bone mass
“If we can prevent colonization or deplete specific microbes such as segmented filamentous bacteria from the microbiome, there is clinical potential to optimize bone mass accumulation during post-pubertal skeletal development,” predicts Chad Novince. The majority of a person’s bone mass accumulates during adolescence and after puberty.
As a person ages, they slowly begin to lose bone mass, which puts them at risk for fractures or osteoporosis. Modulating the levels of segmented filamentous bacteria could limit the risks associated with aging. We already know, for example, that diet, probiotics and antibiotics have important effects on the composition of the microbiota.
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