Streptococcus mutans adhesion to Liver affects Non-alcoholic Steatohepatitis
Development
S. NAKA*, K. TABATA, S. NAKANO, M. MATSUMOTO-NAKANO
Department of Pediatric Dentistry, Okayama University Graduate School of Medicine,
Dentistry and Pharmaceutical Sciences, Japan

Objectives
Non-alcoholic steatohepatitis (NASH) is steatohepatitis with inflammation. A recent
study noted frequent detection of collagen-binding protein (Cnm)- and 190-kDa cellsurface protein antigen (PA)-positive Streptococcus mutans strains in NASH patients.
Furthermore, those strains were found to invade the bloodstream and exacerbate thedisease in animal models. The present study examined localization of S. mutans isolated
from the oral cavity of a NASH patient in a mouse model and the association with diseasedevelopment.
Methods
Six-week old C57BL/6J mice were fed a high-fat diet for four weeks, then (Cnm+/PA+)
S. mutans KT3 strains isolated from a severe NASH patient were intravenously
administered under general anesthesia. Euthanasia at 12 weeks after administration andconventional clinical evaluations of NASH were performed, while liver tissues were
histopathologically evaluated. To examine bacteria localization, KT3, KT4 (Cnm-/PA+),and KT2 (Cnm+/PA-) strains were also injected. After one or three hours, liver, visceral,and subcutaneous fat specimens were collected and inoculated into Mitis-salivarius agar
plates containing bacitracin, and then the number of bacterial colonies was counted.
Results were compared with control group mice that received PBS.
Results
Liver weight and serum levels of ALT, AST, TC, and LDL were significantly of KT3
group were significantly higher in the KT3 group (P<0.05). Histopathologic findings inKT3 group livers also showed prominent lipid accumulation with inflammatory cell
infiltration and fibrosis. All S. mutans strains were detected in all specimens from injected
mice, though the number was significantly higher in liver specimens obtained at one hourafter infection with the KT3 strain (P<0.01). Additionally, the numbers of KT3 strains invisceral and subcutaneous fat after one hour were greater as compared to the other strains.
Conclusion
These findings suggest that Cnm- and PA-positive S. mutans that invade blood may reachthe liver and adipose tissue, and become involved with development of NASH.
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Summary: Streptococcus mutans localization in adipose tissue and liver has effects onpathogenesis in a NASH mouse model
Key words
1. Non-alcoholic steatohepatitis
2. Streptococcus mutans
3. Collagen-binding protein
4. Protein antigen

IgA adherence to Streptococcus mutans Cnm for IgA Nephropathy Onset
Daiki Matsuoka*1, Kana Suehara1, Shuhei Naka1, Taro Misaki2, Yasuyuki Nagasawa3,
Seigo Ito4, Ryota Nomura5, Kazuhiko Nakano6
Michiyo Matsumoto-Nakano1
1

Department of Pediatric Dentistry, Okayama University Graduate School of Medicine,Dentistry and Pharmaceutical Sciences, Japan
2
Division of Nephrology, Seirei Hamamatsu General Hospital, Hamamatsu, Shizuoka,Japan
Department of General Internal Medicine, Hyogo College of Medicine, Nishinomiya,
Hyogo, Japan
4
Department of Internal Medicine, Japan Self-Defense Force Iruma Hospital, Iruma,Saitama, Japan
5
Department of Pediatric Dentistry, Graduate School of Biomedical and HealthSciences, Hiroshima University
6
Department of Pediatric Dentistry, Division of Oral infection and Disease Control,Osaka University Graduate School of Dentistry, Suita, Japan
3

ObjectiveStreptococcus mutans, the major causative bacteria of dental caries, has several surface
proteins related to its pathogenicity including Cnm, which shows collagen binding
protein (Cnm). The most common form of chronic glomerulonephritis in pediatricpatients is IgA nephropathy (IgAN), defined immunohistologically as a diseaseassociated with IgA deposited in the renal glomerular mesangial region. We haveconducted examinations of IgAN onset focused on Cnm-positive S. mutans organisms,with findings in a previous study indicating that administration of S. mutans with Cnm
caused transient induction of IgAN-like lesions in rats. In the present study, adherence

of Cnm to IgA, and invasion by and deposition of Cnm in kidney tissue were examined.
Methods
Human IgA (IgA1) was coated onto 96-well microplates, then recombinant Cnm(rCnm) was added. Washing with phosphate buffer saline was performed, then antirabbit-Cnm followed by an alkaline phosphatase-conjugated rabbit immunoglobulin
antibody were added to all wells. After washing, a color detection solution was added
and OD430 measured. Next, rCnm was blotted onto a polyvinylidene difluoride
membrane using a Bio-Dot® microfiltration apparatus and reacted with IgA1. The
procedure noted above was again performed. Following visualization, membrane
intensities were determined using ImageJ®. Additionally, biotin-labeled rCnm wasadministered into the jugular vein of specific pathogen-free 4-week-old male SpragueDawley rats, then the kidneys were evaluated following immunofluorescent staining
with IgA antibodies.
Results
The rate of binding of IgA1 to rCnm was significantly increased in a dose-dependentmanner in both experiments (P<0.05). Immunofluorescence staining showed IgAdeposition in the glomerular mesangial region, with biotin-labeled rCnm observed in thesame region as IgA deposition.

Conclusion
The present results indicate that IgAN-like nephritis is induced by binding of Cnm toIgA and its deposition in renal glomeruli. It is considered that Cnm is likely an importantfactor related to onset of IgAN.

Summary: Collagen-binding protein Cnm of Streptococcus mutans binds IgA and induces
IgA nephropathy-like nephritis.
Keywords: Streptococcus mutans, IgA nephropathy, Cnm-protein, Biotin, human IgA*Daiki Matsuoka
Department of Pediatric Dentistry, Okayama University Graduate School of Medicine,Dentistry and Pharmaceutical Sciences, Okayama, Japan, pgzf1o9d@s.okayama-u.ac.jp