The oral microbiome: Role of key organisms and complex networks in oral health and disease

Abstract

The field of human microbiome research has undergone a revolution in its approach toward understanding how microorganisms influence the physiology of their host. 1 Development of culture-independent methods has resulted in increased detection and classification of microbial species within microbial communities. 2 technologies, biomarker sequencing, and shotgun metagenomics have become standard tools used to determine the composition and genetic makeup of the human microbiome. 3 Other "-omics" technologies, such as proteomics and metabolomics, support mechanistic hypotheses involved in causal microbial pathways that are related to states of health and disease. 4,5 Since Antonie van Leeuwenhoek first discovered the existence of microbes in the 1700s while analyzing dental plaque under a microscope, the composition of oral microbial communities has been extensively studied. 6 Over 250 species from the oral cavity have been isolated in culture and characterized, including several key pathogens, such as Streptococcus mutans, Porphyromonas gingivalis, Tannerella forsythia, and Aggregatibacter actinomycetemcomitans, involved in the etiology of dental caries and periodontal disease. [7][8][9] An integrated approach toward understanding states of oral disease from the polymicrobial perspective has emerged over time, attributing disease pathology not only to key pathogens but rather to networks of co-occurring microbes, the collective activities of which contribute to pathogenesis. [9][10][11][12] As such, the importance of understanding the divergences, between oral health and disease, in the microbes comprising the system as well as their relative abundance and functional activity, in addition to genetic factors and ecological pressures that drive such changes, is a primary focus of research within the field of oral health research. 9,[13][14][15][16][17] In recent decades, genetic approaches have shed light on the functional capacity of members of oral microbiomes, the mechanistic underpinnings of caries and periodontal disease pathogenesis, and the complex dynamics and fitness factors of key organisms in oral microbiomes. 3,18 The oral microbial ecosystem is constantly exposed to exogenous foreign substances. 17 Such circumstances are defining factors for founding microbes and their ability to persist in this environment, and make for distinct relationships between microbe and host that rely on selective pressures. Pioneer microbial colonizers of the oral cavity, such as Streptococcus mitis, Streptococcus sanguinis, Streptococcus gordonii, and Streptococcus salivarius, display core characteristics that make them well suited to this specific niche as they are able to bind selectively to tongue and cheek cells before the teeth emerge and can outcompete other microbial species. 17,19 Emerging teeth acquire a protective glycoprotein coat, which sets in motion successional microbial colonization, resulting in the development of complex polymicrobial biofilm communities, namely dental plaque. 20 These complex dental plaque m...

Oral Microbiota-Host Interaction Mediated by Taste Receptors

“…Another plausible explanation rests on the fact that bacterial metabolites of the compounds can activate or modulate host taste perception. For instance, host sensitivity to sucrose is correlated with the sucrose catabolism of different oral bacteria in vivo ( Gardner et al., 2020 ; Sedghi et al., 2021 ). Some specific intraoral bacteria like Porphyromonas gingivalis ( P. gingivalis ) are capable of utilizing salivary glutamates so as to modulate their concentration, ultimately affecting the taste perception ( Takahashi, 2015 ).…”

The antimicrobial effect of Rosmarinus officinalis extracts on oral initial adhesion ex vivo

“…Biofilm formation, defined as an organizational form of oral microorganisms and salivary components that irreversibly attach to oral surfaces and are embedded in a matrix of extracellular polymeric substances (EPS), leads to a change in the properties of microorganisms compared to those in the planktonic form [8][9][10][11]. Thus, biofilms show significantly higher resistance to antimicrobial substances (100 to 1,000-fold) [2,12,13].…”

The effects of mouthwashes in human gingiva epithelial progenitor (HGEPp) cells

“…Mouthwashes are most commonly encountered by patients at home, for their antibacterial effects so it is especially important to know their effects due to the uncontrolled conditions in which they are applied [2][3][4]. Biofilm can be considered as a special tissue formation (constantly changing microbiome) that, due to its complexity, can be reduced by the combined application of mechanical and chemical factors [5,6]. Fortunately, these interventions mainly affect biofilm pathogens, but the effect of some mouthwash components on the oral epithelium cannot be ruled out [7][8][9].…”