A specific Streptococcus mutans strain aggravates non-alcoholic fatty liver disease

ObjectiveStreptococcus mutans, a major dental caries pathogen, has shown to be associated with the aggravation of cerebral hemorrhage and inflammatory bowel diseases. In this study, we evaluated the effects of S.mutans on the development of non-alcoholic steatohepatitis (NASH) in a mouse model. Materials and methodsStreptococcus mutans oral strain MT8148 (serotype c) and a blood isolate TW871 (k) were used. C57BL/6J mice (6weeks old) were fed a high-fat diet for 4weeks; the test strains or phosphate-buffered saline was then intravenously administered. Mice were euthanized after 8 or 12weeks. Whole body, extirpated liver, and visceral fat weights were determined, and histopathological evaluations of the liver specimens were performed. ResultsMice infected with TW871 showed significantly greater body and liver weights than those administered MT8148 or phosphate-buffered saline. Histopathological analyses revealed prominent infiltration of inflammatory cells and adipocellular deposition in livers extirpated 8weeks after an infection with TW871; fibrosis was also observed in livers extirpated after 12weeks. ConclusionThese results suggest that a specific strain of S.mutans could induce NASH.