|Yoshihisa Yamashita||Last modified date：2018.06.22|
Professor / Division of Oral Health, Growth and Development / Department of Dental Science / Faculty of Dental Science
|Yoshihisa Yamashita||Last modified date：2018.06.22|
|1.||Yoshihisa Yamashita, Diagnostic value of salivary microbiome to grasp periodontal health condition and susceptibility to periodontal disease, 3rd Microbiome R&D and Business Collaboration Congress: Asia, 2017.03.|
|2.||Shinya Kageyama, Toru Takeshita, Mikari Asakawa, Yukie Shibata, Matsumi, R., Michiko Furuta, Kenji Takeuchi, Yoshihisa Yamashita, Exploration of IgA-binding bacteria in salivary microbiome, Kyudai Oral Bioscience 2017, 2017.02.|
|3.||Toru Takeshita, Shinya Kageyama, Mikari Asakawa, Michiko Furuta, Kenji Takeuchi, Toshiharu Ninomiya, Yoshihisa Yamashita, Identification of salivary microbiome in orally-healthy Japanese adults, 6th International Human Microbiome Congress, 2016.11.|
|4.||Shinya Kageyama, Toru Takeshita, Mikari Asakawa, Yukie Shibata, Matsumi, R., Michiko Furuta, Kenji Takeuchi, Yoshihisa Yamashita, Identification of IgA-binding bacteria in salivary microbiome, 6th International Human Microbiome Congress, 2016.11.|
|5.||Yoshihisa Yamashita, Toru Takeshita, Michiko Furuta, Kenji Takeuchi, Yukie Shibata, Toshiharu Ninomiya, Characteristics of bacterial composition in saliva of edentulous adults, 4th World Congress on Targeting Microbiota, 2016.10.|
|6.||Mikari Asakawa, Toru Takeshita, Shinya Kageyama, Yoshihisa Yamashita, Development of oral indigenous microbiota and factors associated with maturation in early childhood, 第58回歯科基礎医学会総会, 2016.08.|
|7.||影山伸哉, 竹下 徹, 朝川美加李, 山下喜久, 唾液マイクロバイオームは歯周病の重症度を反映する, 第58回歯科基礎医学会総会, 2016.08.|
|8.||Toru Takeshita, Mikari Asakawa, Shinya Kageyama, Yoshihisa Yamashita, Succession of tongue microbiota in early childhood and its related factors, ISME16, 2016.08.|
|9.||Michiko Furuta, Yoshihiro Shimazaki, Takashi Shinagawa, An Lu, Kenji Takeuchi, Yoshihisa Yamashita, Interrelationship between Metabolic Syndrome and Periodontal Health Condition: A Prospective Cohort Study, Europerio8, 2015.06.|
|10.||Junko Obata, Toru Takeshita, Yukie Shibata, Masako Unemori, Akifumi Akamine, Yoshihisa Yamashita, Relationship among carious dentin, dental plaque and salivary microbiota, 93rd General session & exhibition of the IADR, 2015.03.|
|11.||Myrna Zakaria, Toru Takeshita, Michiko Furuta, Hidefumi Maeda, Akifumi Akamine, Yutaka Kiyohara, Toshiharu Ninomiya, Yoshihisa Yamashita, Oral Mycobiome in Japanese Elderly Adults, 93rd General session & exhibition of the IADR, 2015.03.|
|12.||山下 喜久, 竹下 徹, Tongue Microbiome in Edentulous Infants and Dentate Children, Targeting Microbiota, 2014.10.|
|13.||Yamashita Yoshihisa, Toru Takeshita, Kazuki Matsuo, Dong-Hun Han, Hyun-Duck Kim, Comparison of salivary microbiota between Japanese and Koreans, Cell Symposia; Microbiome and Host Health, 2013.05.|
|14.||古田 美智子, 嶋﨑 義浩, 竹下 徹, 柴田 幸江, 秋房 住郎, 江島 伸興, 清原 裕, 二ノ宮, 平川 洋一郎, 向井 直子, 永田 雅治, 山下 喜久, Gender differences in the association between periodontitis and metabolic syndrome, 91st General session & exhibition of the IADR, 2013.03.|
|15.||嶋﨑 義浩, 岸本, 二ノ宮, 清原 裕, 熊谷, 山下 喜久, Relationship between Physical Activity and Periodontal Disease: The Hisayama Study, 91st General session & exhibition of the IADR, 2013.03.|
|16.||Yamashita Yoshihisa, Gender difference in the association of periodontal status and metabolic syndrome, 60th Annual Meeting of Japanese Association for Dental Research, 2012.12, Concept of the association between periodontal disease and diabetes mellitus has been well established based on a huge number of previous studies. Our study with Hisayama survey in 1998 also showed that subjects comprised of both male and female with deeper periodontal pockets or more sever attachment loss was significantly associated with diabetes as compared with those who had healthy periodontal tissue. The result confirmed that periodontal disease is more prevalent in diabetic patients. On the other hand, there was a significant association of deep periodontal pocket depth with impaired glucose tolerance, a pre-diabetic state of hyperglycemia, while that with attachment loss was not observed. Since periodontal pocket depth reflects strength of current inflammation than the attachment loss does, it is suggested that the association between periodontal status and glucose tolerance status is derived from the effect of inflammatory condition on insulin resistance rather than sharing characteristics of inherited susceptibility to both diseases.
On the other hand, obesity is an important risk factor of the development of diabetes and is related to low-grade systemic inflammation. Visceral obesity links to decreased glucose tolerance, leading to a reduction in insulin-mediated glucose uptake. At the same time, obesity is well known to be an important risk marker of periodontal diseases. When we examined the association among three health conditions in multivariate analysis in female subjects of the above-mentioned Hisayama survey in 1998, we observed that periodontal pocket depth was significantly associated with obesity, but not with glucose tolerance status. On the other hands, there was not significant association of obesity and glucose tolerance status with attachment loss. Because both obesity and periodontal pocket depth are associated with inflammation, these two health condition may be linked through a common pathophysiological pathway. These could explain that periodontal status has a more closer connection with obesity than with glucose tolerance status.
Obesity and glucose intolerance commonly occur with dyslipidemia and hypertension, and this constellation of metabolic disturbances calls the metabolic syndrome. Our study with Hisayama survey in 1998 on periodontal disease and metabolic syndrome showed that female population having more components of metabolic syndrome had significantly higher odds ratios for a greater pocket depth and attachment loss than did those who with no components. However, such an association was not observed in male population. When we analyzed data obtained from the latest Hisayama survey in 2007 with around 3-folds larger number of subjects than the previous study’s one in 1998, the association between periodontal disease and metabolic syndrome in females was similar to that in the survey in 1998, but that in males was weaker as compared with that in females and depended on the definition of periodontal disease severity, suggesting gender differences in the association between periodontal disease and metabolic syndrome. The mechanism of association between periodontal disease and metabolic syndrome has not yet elucidated and analyzing its gender difference might be a good stepping stone towards the clarification of such a complex association.
|17.||山下 喜久, Comparison of Oral Health Environment between Korean and Japanese Adult Population, The 2012 Annual Meeting of Korean Academy of Oral Health, 2012.10, We previously compared the national survey of oral health between Korean and Japanese and the results indicated that better Korean oral heath status as compared with that of Japanese. The findings is very interesting when considering the fact that genetic background of Korean and Japanese is the same based on the similarity of SNPs between both populations. The findings indicate that environmental factors play an important role in discrepancy of oral health between two countries. Therefore, we further compared the oral health condition between Korean and Japanese population based on both the Yangpyong study performed by Prof. Hyun-Duck Kim and the Hisayama study carried out in our laboratory.
We obtained the baseline data of 3000 people (aged 40-79) in Hisayama survey at 2007. Data of oral health are as follows; periodontal condition based on NHANES criteria, dental caries experience, oral hygiene condition (Plaque Index (Löe & Sileness)), occlusal condition (Eichner's classification), and denture's condition in addition to volume of stimulated saliva and bacterial composition in it. On the other hand, oral health status and oral environment including oral microbiota corresponding to the Hisayama study (2007) were obtained in the Yangpyong study by Prof. Kim's laboratory in 2011. Bacterial composition in saliva is analyzed by T-RFLP analysis. T-RFLP is an effective approach for the rapid assessment and comparison of complex bacterial communities, including oral microbiota. For each sample, internal region of 16S rRNA gene was amplified using the bacterial universal primer 8F labeled at the 5’ end with a fluorescent dye, 6-FAM, and 806R labeled at the 5’ end with HEX. Following the gel purification, the amplicons were digested with restriction enzyme (HaeIII). The restriction digestion products were mixed with deionized formamide and internal standards, and the sample mixtures were electrophoresed on ABI 3130 genetic analyzer. The bacterial community structure was displayed as peak pattern and was able to be statistically and objectively compared with other samples.
Periodontal status of subjects in Yangpyong study was better than that in the Hisayama study as observed in the previous comparison of the national oral health surveys between Koreans and Japanese. When the subjects were limited to those with healthy oral condition (with > 20 teeth, without decayed teeth and mean periodontal pocket depth < 2.0 mm), the T-RFLP profiles were distinct between Korean and Japanese populations. The difference was confirmed statistically using permutaional multivariate analysis of variance (perMANOVA). Of 281 distinct peaks detected in the T-RFLP peak patterns, the relative peak area abundances of two specific peaks were characteristically larger in Koreans than those in Japanese. These peaks putatively corresponded to Neisseria and Haemophilus species. On the other hand, the relative abundances of 5 peaks were larger in Japanese than those in Koreans, and they corresponded to Prevotella and Veillonella species. It is suggested that oral indigenous microbiota in Koreans were more dominated by Neisseria and Haemophilus species and less dominated by Prevotella species. These characteristics were coincided with those in periodontally-healthy subjects reported in our previous study (Takeshita et al, ISME J 3:65-78, 2009), implying that Koreans exhibited better environment of oral microbiota for periodontal health than Japanese, probably resulted in better periodontal tissue condition in Koreans. The further study needed to clarify the factors of geographic difference of oral microbiota between Koreans and Japanese.
|18.||Yamashita Yoshihisa, Toru Takeshita, Masaki Yasui, Yukie Shibata, Yuiji Saeki, Hiro Ito, Structural shift of microbiota in dental plaque formed on a hydroxyapatite disk surfaces in vivo
, 6th ASM Conference on Biofilms , 2012.09, Background:
In the human oral cavity, microbial communities form biofilms on saliva bathed tooth surfaces and matured dental plaque becomes causes of oral diseases, dental caries and periodontal diseases. However, course of the maturation remains uncharacterized using culture-independent molecular techniques.
In this study, using a retrievable hydroxyapatite disk model, plaque samples accumulated on disks after 1, 2, 3, 4, 5 and 7 days were collected from 19 subjects (23 ± 6 years, 6 females and 13 males). Amounts of total bacteria were estimated based on quantitative real-time PCR using bacterial universal primers. The composition of developing bacterial community day-by-day was pursued by barcoded pyrosequencing analysis of 16S rRNA gene.
Total bacterial amount and species richness and diversity of bacterial community on the disk gradually increased during 7 days. Of 59 bacterial genera detected in this study, Streptococcus, Abiotrophia, Neisseria and Haemophilus appeared to predominate during the early stages. The relative abundances of Porphyromonas, Gemella and Granulicatella increased in the middle stage, whereas anaerobes such as Prevotella, Veillonella, Fusobactrium and Capnocytophaga become
predominant in the late stage. On the other hand, Neisseria, Gemella, and Fusobacteirum exhibited relatively large inter-individual variances, suggesting that these variances might be associated with the virulence of dental plaque biofilm.
The results in the present study revealed microbial developing pattern on hydroxyapatite surfaces in human oral cavity considering individual variance..
|19.||山下 喜久, Individual variance of dental plaque maturation process related with oral health , 第54回歯科基礎医学会学術大会・総会, 2012.09, In the human oral cavity, microbial communities form biofilms on saliva-bathed tooth surfaces and matured dental plaque becomes causes of oral diseases, e.g. dental caries and periodontal diseases. However, course of the maturation remains uncharacterized using culture-independent molecular techniques. To explore a more ‘healthy’ pattern of dental plaque maturation, we focused on subjects without caries experience. Using a retrievable hydroxyapatite disk model, dental plaque samples accumulated for 1, 2, 3, 4, 5 and 7 days were collected from 9 caries-free young adults and 10 who have ≥9 teeth with caries experience (23 ± 6 years, 6 females and 13 males). Amounts of total bacteria were estimated based on quantitative real-time PCR using bacterial universal primers. The composition of developing bacterial community day-by-day was pursued by barcoded pyrosequencing analysis of 16S rRNA gene. In both caries-free and -active subjects, total bacterial amount and microbial diversity steadily increased over time. Total bacterial amount and species richness and diversity of bacterial community on the disk gradually increased during 7 days. Of 59 bacterial genera detected in this study, four genus including Streptococcus appeared to predominate during the early stages. On the other hand, anaerobes such as Prevotella become predominant in the late stage. In addition, some genus exhibited relatively large inter-individual variances, suggesting that these variances might be associated with the virulence of dental plaque biofilm. Plaque microbiota of caries-free subjects showed significantly lower bacterial amount but higher microbial diversity than caries-active subjects in the early stage of plaque development. Neisseria and Gemella of caries-free subjects were significantly more predominant especially in the early stage, whereas Streptococcus, that is the most predominant member of the microbiota were present in less proportion. Furthermore, the relative abundances of such as Granulicatella less drastically increased in the late stage in caries-free subjects than caries-active subjects. The results in the present study revealed microbial developing pattern on hydroxyapatite surfaces in human oral cavity considering individual variance and a characteristic succession pattern of plaque microbiota development in caries-free subjects. It might lead to their low susceptibility to dental caries..|
|20.||Kazuki Matsuo, Wataru Yamanaka, Toru Takeshita, Yukie Shibata, Nobuoki Eshima, Takeshi Yokoyama, Yoshihisa Yamashita, Structural Stability of a Salivary Bacterial Population against Supragingival Microbiota Shift Following Periodontal Therapy, International symposium of Microbial Ecology 13, 2012.08.|
|21.||Toru Takeshita, Masaki Yasui, Yuji Saeki, Yukie Shibata, Yoshihisa Yamashita, Bacterial community succession on a hydroxyapatite disk in oral cavity in caries-active and caries-free subjects, International symposium of Microbial Ecology 13, 2012.08.|
|22.||山下 喜久, Oral Microflora and Oral and General Health Connection, The 2010 Annual Meeting of Korean Academy of Oral Health, 2010.10, It has been well know that oral bacteria are closely related to oral health condition. Previous works demonstrated that mutans streptococci are major etiologic agents of dental caries and that Porphyromonas gingivalis, Tannerella forsythia, Treponema denticola and their complex are prime suspects in the development of periodontitis. However, recent epidemiological studies suggested that these performers are not enough to explain the etiology of such oral diseases. In oral cavity, numerous species and huge amount of indigenous bacteria inhabit and pathogens of oral diseases are regulated by numerous interactions with indigenous bacteria in addition to host responses. A large number of past studies using conventional methods based on cultivation and culture-independent molecular techniques have identified over 700 bacterial species in the human oral cavity.
One molecular method, terminal restriction fragment length polymorphism (T-RFLP) analysis, is an effective approach for the rapid assessment and comparison of complex bacterial communities such as oral microflora. The advantage of this method is that the composition of the bacterial community can be converted to a peak pattern. The peak patterns from numerous subjects can be classified based on the similarity of their compositions, and the composition pattern associated with a clinical symptom can be explored. In addition, comparing the size of terminal restriction fragments (TRFs) determined in a T-RFLP analysis with those from known 16S rRNA gene sequences enable to identify the respective bacterial population. Moreover, we have reduced the large error in the sizing of DNA fragments in T-RFLP analysis to more accurately assign bacteria to TRFs.
In this lecture, I would like to introduce the recent our projects of high throughput analysis of oral microflora utilizing T-RFLP analysis relating to periodontitis, oral malordor and pneumonia. Furthermore I will discuss the utility of the diagnosis of indigenous oral microflora in future dentistry..