Okayama University


Okayama University Medical Research Updates (OU-MRU) Vol.60

December 26, 2018

Source: Okayama University (JAPAN), Public Relations and Information Strategy
For immediate release: 26 December 2018
Okayama University research: Role of commensal microbiota in bone remodeling

(Okayama, 26 December) Researchers at Okayama University report in the journal Molecules that commensal microbiota — microorganisms present in the human body — may play a key role in human-bone remodeling by enhancing the activity of both cells breaking down bone tissue and cells synthesizing bone.

Humans are host to several types of microorganisms like bacteria, fungi and viruses. Those residing in the human body without harming it are collectively called commensal microbiota. While it has been established that commensal microbiota play an important role in the body’s energy management and the development of its immune system, recent findings have suggested that they affect the regulation of human bone formation too. Now, by performing comparative experiments on mice, Professor Manabu Morita, Yoko Uchida (D.D.S.) and colleagues from Okayama University confirmed the link between commensal microbiota and bone cell regulation. Specifically, they found that the presence of the microorganisms enhances the activity of both osteoclasts (cells that break down bone tissue) and osteoblasts (cells that synthesize bone).

Professor Morita and colleagues worked with two types of mouse: germ-free (GF) mice, free of any microorganisms, and specific-pathogen-free (SPF) mice, which are guaranteed to be free of certain pathogens but at the same time host to commensal microbiota.

The researchers investigated the activity of osteoclasts and osteoblasts in 8-week-old GF and SPF mice. They first looked at body weight and size. The SPF mice were found to have larger body size but lower bone mineral density in alveolar bones (the bones that contain the tooth sockets on the jaw bones), an observation attributed to the presence of commensal microbiota. In addition, by analyzing blood serum of the mice for substances that are associated with osteoclast activity, Professor Morita and colleagues were able to conclude that commensal microbiota cause greater development and activity of osteoclasts.

The scientists also discovered that the expression of osteocalcin messenger RNA— a maker of bone mineralization — is significantly higher in SPF mice, providing a further link between commensal microbiota and bone-remodeling processes.
While the precise mechanism of commensal microbiota affecting the expression of osteo-blast-specific genes such as osteocalcin needs to be further investigated in order to be completely understood, quoting Professor Morita and colleagues, “[these results] suggest that the commensal microbiota prevents excessive mineralization possibly by stimulating osteocalcin expression in osteoblasts, and enhances both osteoblast and osteoclast activity by regulating specific transcription factors.”

Commensal microbiota

The term microbiota refers to the collective of bacteria and other microorganisms in an animal’s body. The term commensal is used when the presence of the microbiota is not harmful for the animal host. Professor Manabu Morita, Yoko Uchida (D.D.S.) and colleagues from Okayama University have now studied the influence of commensal microbiota on bone remodeling in mice. Their findings show that commensal microbiota have a regulatory effect on bone formation, as shown by differences in body weight and size between mice with and without commensal microbiota.

Osteocalcin. Bone density
Osteocalcin is a protein occurring in bone, produced by osteoblasts (bone-synthesizing cells). It is known to play a role in bone mineralization. As such, osteocalcin is often used as a biochemical marker for bone-formation activity. Professor Morita and colleagues were able to show that in specific-pathogen-free (SPF) mice, the expression of osteocalcin is related to the presence of commensal microbiota.
The study also involved measurements of bone density, or bone mineral density — the amount of bone mineral in bone tissue. While the SPF mice exhibited a larger body size, their bone density was found to be lower.

Yoko Uchida, Koichiro Irie, Daiki Fukuhara, Kota Kataoka, Takako Hattori, Mitsuaki Ono, Daisuke Ekuni, Satoshi Kubota, Manabu Morita. Commensal microbiota enhance both osteoclast and osteoblast activities. Molecules, 2018 Jun 23;23(7). pii: E1517.
DOI: 10.3390/molecules23071517.

Reference (Okayama University OU-MRU) : Professor Morita’s team
OU-MRU Vol.59:Role of commensal flora in periodontal immune response investigated

Correspondence to
Professor Manabu Morita, D.D.S., Ph.D.
Department of Preventive Dentistry,
OkayamaUniversity Graduate School of Medicine, Dentistry and
Pharmaceutical Sciences, 2-5-1 Shikata-cho, Kita-ku, Okayama,
700-8558, Japan.
E-mail: mmorita@md.okayama-u.ac.jp

Further information
Okayama University
1-1-1 Tsushima-naka , Kita-ku , Okayama 700-8530, Japan
Public Relations and Information Strategy
E-mail: www-adm (a) adm.okayama-u.ac.jp
For inquiries, please contact us by replacing (a) with the @ mark.
Website: //www.okayama-u.ac.jp/index_e.html
Okayama Univ. e-Bulletin: //www.okayama-u.ac.jp/user/kouhou/ebulletin/
About Okayama University (You Tube): https://www.youtube.com/watch?v=iDL1coqPRYI
Okayama University Image Movie (You Tube): https://www.youtube.com/watch?v=KU3hOIXS5kk

Okayama University Medical Research Updates (OU-MRU)
The whole volume : OU-MRU (1- )
Vol.1:Innovative non-invasive ‘liquid biopsy’ method to capture circulating tumor cells from blood samples for genetic testing
Vol.2:Ensuring a cool recovery from cardiac arrest
Vol.3:Organ regeneration research leaps forward
Vol.4:Cardiac mechanosensitive integrator
Vol.5:Cell injections get to the heart of congenital defects
Vol.6:Fourth key molecule identified in bone development
Vol.7:Anticancer virus solution provides an alternative to surgery
Vol.8:Light-responsive dye stimulates sight in genetically blind patients
Vol.9:Diabetes drug helps towards immunity against cancer
Vol.10:Enzyme-inhibitors treat drug-resistant epilepsy
Vol.11:Compound-protein combination shows promise for arthritis treatment
Vol.12:Molecular features of the circadian clock system in fruit flies
Vol.13:Peptide directs artificial tissue growth
Vol.14:Simplified boron compound may treat brain tumours
Vol.15:Metamaterial absorbers for infrared inspection technologies
Vol.16:Epigenetics research traces how crickets restore lost limbs
Vol.17:Cell research shows pathway for suppressing hepatitis B virus
Vol.18:Therapeutic protein targets liver disease
Vol.19:Study links signalling protein to osteoarthritis
Vol.20:Lack of enzyme promotes fatty liver disease in thin patients
Vol.21:Combined gene transduction and light therapy targets gastric cancer
Vol.22:Medical supportive device for hemodialysis catheter puncture
Vol.23:Development of low cost oral inactivated vaccines for dysentery
Vol.24:Sticky molecules to tackle obesity and diabetes
Vol.25:Self-administered aroma foot massage may reduce symptoms of anxiety
Vol.26:Protein for preventing heart failure
Vol.27:Keeping cells in shape to fight sepsis
Vol.28:Viral-based therapy for bone cancer
Vol.29:Photoreactive compound allows protein synthesis control with light
Vol.30:Cancer stem cells’ role in tumor growth revealed
Vol.31:Prevention of RNA virus replication
Vol.32:Enzyme target for slowing bladder cancer invasion
Vol.33:Attacking tumors from the inside
Vol.34:Novel mouse model for studying pancreatic cancer
Vol.35:Potential cause of Lafora disease revealed
Vol.36:Overloading of protein localization triggers cellular defects
Vol.37:Protein dosage compensation mechanism unravelled
Vol.38:Bioengineered tooth restoration in a large mammal
Vol.39:Successful test of retinal prosthesis implanted in rats
Vol.40:Antibodies prolong seizure latency in epileptic mice
Vol.41:Inorganic biomaterials for soft-tissue adhesion
Vol.42:Potential drug for treating chronic pain with few side effects
Vol.43:Potential origin of cancer-associated cells revealed
Vol.44:Protection from plant extracts
Vol.45:Link between biological-clock disturbance and brain dysfunction uncovered
Vol.46:New method for suppressing lung cancer oncogene
Vol.47:Candidate genes for eye misalignment identified
Vol.48:Nanotechnology-based approach to cancer virotherapy
Vol.49:Cell membrane as material for bone formation
Vol.50:Iron removal as a potential cancer therapy
Vol.51:Potential of 3D nanoenvironments for experimental cancer
Vol.52:A protein found on the surface of cells plays an integral role in tumor growth and sustenance
Vol.53:Successful implantation and testing of retinal prosthesis in monkey eyes with retinal degeneration
Vol.54:Measuring ion concentration in solutions for clinical and environmental research
Vol.55:Diabetic kidney disease: new biomarkers improve the prediction of the renal prognosis
Vol.56:New device for assisting accurate hemodialysis catheter placement
Vol.57:Possible link between excess chewing muscle activity and dental disease
Vol.58:Insights into mechanisms governing the resistance to the anti-cancer medication cetuximab
Vol.59:Role of commensal flora in periodontal immune response investigated