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Okayama University Medical Research Updates (OU-MRU) Vol.59

December 10, 2018

Source: Okayama University (JAPAN), Public Relations and Information Strategy
For immediate release: 26 2018
Okayama University research: Role of commensal flora in periodontal immune response investigated

(Okayama, 26 November) Researchers at Okayama University report in the Journal of Periodontology that the presence of commensal flora in the mouth may play a key role in the functioning of the immune system against periodontal infections.

The development of an animal’s immune system relies on commensal flora — microorganisms such as bacteria present in certain parts of the body. In the case of immunity against periodontal diseases — infections of the areas surrounding teeth — it is unclear, however, what exactly the role of commensal flora is. Now, Professor Manabu Morita from Okayama University and colleagues have investigated the relation between commensal flora in the mouth and the immune response to a bacterium called Porphyromonas gingivalis (P. gingivalis), which contains lipopolysaccharide (LPS), a known periodontal pathogen.

The researchers tested the immune response of mice after the application of P. gingivalis/LPS. Two types of mouse were used in the experiments: germ-free and specific-pathogen-free mice. The former are free of any microorganisms, including commensal flora; the latter are mice guaranteed to be free of certain pathogens — in this case, periodontal pathogens — but not of commensal flora.

The response to the bacterium was assessed by the amounts of particular types of cells that are characteristic of immune system activation. Four groups of mice were monitored: a ‘baseline’ group not exposed to P. gingivalis and three groups to which the bacterium was applied; each of the three groups was then examined at different points in time after the application of LPS.

The scientists observed that exposure to P. gingivalis led to an increase in the number of a certain type of cell associated with immune system activity in the specific-pathogen-free mice, after 3 hours, indicating that application of the bacterium indeed triggered the immune system. At the same time, the germ-free mice did not show similar increased levels of these cells, suggesting that commensal flora contribute to the development and functioning of the periodontal immune system.

Professor Morita and colleagues are aware of the limitations of their study. They did not, for example, investigate the effect of repeatedly applying LPS. They also acknowledge that only a limited set of cell types characteristic of immune system activity was monitored. Therefore, the scientists concluded that “[the] results, though suggestive, should be interpreted with caution.”

Background
R Commensal flora

Flora is the term for a community of bacteria and other microorganisms in a part of an animal’s body. The term commensal flora is used when the presence of the flora is not harmful for the animal host. Professor Manabu Morita from Okayama University and colleagues have now studied the role of commensal flora in the gingival sulcus — the area between a tooth and surrounding tissues — on the development of proper periodontal immune responses.

Lipopolysaccharide
A lipopolysaccharide (LPS) is a large organic molecule consisting of a lipid and a polysaccharide; LPS molecules occur in certain types of bacteria. LPS is known to be toxic, and typically triggers immune response activation. Professor Morita and colleagues have now investigated whether immune response to LPS, when applied via the bacterium Porphyromonas gingivalis (P. gingivalis), is influenced by the presence of commensal flora in the gingival sulcus.

Reference
Daiki Fukuhara, Koichiro Irie, Yoko Uchida, Kota Kataoka, Kentaro Akiyama, Daisuke Ekuni, Takaaki Tomofuji, Manabu Morita. Impact of commensal flora on periodontal immune response to lipopolysaccharide. Journal of Periodontology, 2018;89:1213–1220.
DOI: 10.1002/JPER.17-0567
Impact of commensal flora on periodontal immune response to lipopolysaccharide


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(a)md.okayama-u.ac.jp
For inquiries, please contact us by replacing (a) with the @ mark.



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Okayama University Medical Research Updates (OU-MRU)
The whole volume : OU-MRU (1- )
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Vol.2:Ensuring a cool recovery from cardiac arrest
Vol.3:Organ regeneration research leaps forward
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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
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Vol.38:Bioengineered tooth restoration in a large mammal
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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

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