Osteomicrobiology: A New Cross-Disciplinary Research Field

Abstract

The mutualistic interaction between the gut microbiota (GM) and its host profoundly shapes many aspects of our physiology. The composition and activity of the gut microbiota is modulated by environmental factors such as dietary habits and antibiotic treatments. In rodents, studies demonstrate that the GM is a crucial regulator of bone metabolism and that modulation of the GM composition by probiotic interventions can prevent castration-induced bone loss. Short-term colonization of germ-free mice with GM results in an activation of CD4+T cells, resulting in increased levels of pro-inflammatory cytokines in bone and thereby activation of osteoclastic bone resorption. Besides these immune-mediated effects on bone mass, the GM is involved in nutritional uptake and may, thereby, regulate overall body growth and bone sizes possibly mediated via altered IGF-I levels. We recently introduced a new term “osteomicrobiology” for the rapidly emerging research field of the role of the microbiota in bone health. This research field is aimed to bridge the gaps between bone physiology, gastroenterology, immunology, and microbiology. Future studies will determine if the GM is a novel therapeutic target for osteoporosis and if the GM composition might be used as a biomarker for fracture prediction.

Specific Commensal Bacterium Critically Regulates Gut Microbiota Osteoimmunomodulatory Actions During Normal Postpubertal Skeletal Growth and Maturation

“…Commensal gut microbiota effects on the skeleton have commonly been proposed to occur through a direct gut–bone axis . Our prior work revealed that the commensal gut microbiota profoundly stimulates innate and adaptive immunity in the liver, which led us to postulate that gut microbiota effects on the skeleton are mediated, in part, by a gut–liver–bone axis .…”

“…(39)(40)(41)(42) Commensal gut microbiota effects on the skeleton have commonly been proposed to occur through a direct gut-bone axis. (43,44) Our prior work revealed that the commensal gut microbiota profoundly stimulates innate and adaptive immunity in the liver, which led us to postulate that gut microbiota effects on the skeleton are mediated, in part, by a gut-liver-bone axis. (13) The current report reveals that SFB has pro-osteoclastic/antiosteoblastic actions impairing postpubertal skeletal development, which appear to be mediated through immunomodulatory effects in both the gut and liver.…”

Osteoimmunology: Inflammatory osteolysis and regeneration of the alveolar bone

“…In reality, subsets of immune cells, various differentiation stages of bone cells (Ducy, Schinke, & Karsenty, ; Teitelbaum, ), and different modes of local and systemic cell activation generate a complex picture of this research area. Osteoimmunology was recently open to a new field which considers the impact of the microbiome on bone homeostasis in health and disease—osteomicrobiology (Ohlsson & Sjogren, ). For example, short‐chain fatty acids, the main metabolites derived from microbial fermentation of dietary fibres, can regulate osteoclast metabolism and bone homeostasis (Lucas et al., ).…”

“…Osteomicrobiology, based on the mutual interaction of not only the gut microbiota but also the microbiome of the oral cavity with the host, is a new term and an emerging research field that bridges the gap between the microbiome and osteoimmunology (Hsu & Pacifici, ; Ohlsson & Sjogren, ). Consistent observations are based on periodontitis models treated with probiotics.…”

Microbiota and Bone Health: The Gut-Musculoskeletal Axis

“…By modulating the immune system, GM is becoming a new player in the regulators of bone turnover and function. Considering the interplay between bone physiology, gastrointestinal tract content, microbiology, and immunology, Ohlsson and Sjögren are proposing the term "Osteomicrobiology" to cover this field where GM changes are capable of preventing ovariectomy-induced bone loss [12]. Such a cross-talk appears to exist between GM and skeletal muscle too.…”