Gut Microbiota, Immune System, and Bone

Abstract

The gut microbiota (GM) is the whole of commensal, symbiotic, and pathogenic microorganisms living in our intestine. The GM-host interactions contribute to the maturation of the host immune system, modulating its systemic response. It is well documented that GM can interact with non-enteral cells such as immune cells, dendritic cells, and hepatocytes, producing molecules such as short-chain fatty acids, indole derivatives, polyamines, and secondary bile acid. The receptors for some of these molecules are expressed on immune cells, and modulate the differentiation of T effector and regulatory cells: this is the reason why dysbiosis is correlated with several autoimmune, metabolic, and neurodegenerative diseases. Due to the close interplay between immune and bone cells, GM has a central role in maintaining bone health and influences bone turnover and density. GM can improve bone health also increasing calcium absorption and modulating the production of gut serotonin, a molecule that interacts with bone cells and has been suggested to act as a bone mass regulator. Thus, GM manipulation by consumption of antibiotics, changes in dietary habits, and the use of pre- and probiotics may affect bone health. This review summarizes evidences on the influence of GM on immune system and on bone turnover and density and how GM manipulation may influence bone health.

Effects of Allium hookeri on gut microbiome related to growth performance in young broiler chickens

“…We speculated that the association with bone strength and IBD in common genera might be explained by the relationship between immune and bone cells. The interaction is mediated via circulating blood cells containing T and B cells in bone marrow [28]. T and B cells play important roles in cell-mediated immunity to regulate bone resorption and bone formation by producing large amounts of cytokines [50], which explains the connection between bone and immune cells.…”

“…hookeri not only affects the microbiome composition, but also the growth traits such as body weight, bone strength, and levels of infectious bursal disease (IBD) antibody. These traits were linked to gut microbiome in several studies [27,28]. The abundance of genera was correlated with growth traits.…”

Recovery of Human Gut Microbiota Genomes Substantially With Third-generation Sequencing

“…/prokaryotes/). There are 266319 prokaryote genomes up to now (Chromosome (3,186), Complete (19,702), Contig(141,127), Scaffold(102,304))( Supplementary Fig. 1).…”

“…There are growing evidences that gut microbiota-the human commensals-in uences normal physiological functions from the maintenance of barrier homeostasis to the modulation of metabolism, in ammation, immunity, and development [1][2][3]. Further, its disorder is a potential risk factor of various chronic diseases such as type 2 diabetes, gastrointestinal cancer, and brain disorders [4][5][6].…”

Microbiota and Bone Health: The Gut-Musculoskeletal Axis

“…A GM-host interaction contributes to control the host immune system development. A series of GM-produced factors influence immune cells, suggesting a link between dysbiosis and autoimmune, metabolic, and degenerative disorders as reviewed by d'Amelio and Sassi [11]. By modulating the immune system, GM is becoming a new player in the regulators of bone turnover and function.…”