Role of oral and gut microbiome in nitric oxide-mediated colon motility.

Periodontal disease (PD), a severe form of gum disease, is among the most prevalent chronic infection in humans and is associated with complex microbial synergistic dysbiosis in the subgingival cavity. The immune system of the body interacts with the microbes as the plaque extends and propagates below the gingival sulcus. Once bacteria reach the gingival sulcus, it can enter the blood stream and affect various areas of the human body. The polymicrobial nature of periodontal disease, if left untreated, promotes chronic inflammation, not only within the oral cavity, but also throughout the human body. Alterations seen in the concentrations of healthy gut microbiota may lead to systemic alterations, such as gut motility disorders, high blood pressure, and atherosclerosis. Although gut microbiome has been shown to play a vital role in intestinal motility functions, the role of oral bacteria in this setting remains to be investigated. It is unclear whether oral microbial DNA is present in the large intestine and, if so, whether it alters the gut microbiome. In addition, polybacterial infection induced PD reduced nitric oxide (NO) synthesis and antioxidant enzymes in rodent colon. In this review, we will discuss the interactions between oral and gut microbiome, specifics of how the oral microbiome may modulate the activities of the gut microbiome, and possible ramifications of these alterations.

Porphyromonas gingivalis infection alters Nrf2-phase II enzymes and nitric oxide in primary human aortic endothelial cells.

BACKGROUND: Periodontal disease (PD) is known to be associated with endothelial dysfunction in patients with coronary artery and/or cardiovascular disease. In our study, we sought to explore the virulence of P. gingivalis (Pg) affecting glycogen synthase kinase 3 beta (GSK-3ß)/nuclear factor (erythroid-derived 2)-like 2 (Nrf2)/tetrahydrobiopterin (BH4 )/ nitric oxide synthase (NOS) expression in primary human aortic endothelial cells (pHAECs). METHODS: pHAECs were infected for 48 hours with Pg in vitro using the Human oxygen-Bacteria anaerobic coculture technique. Cell viability was determined, and target gene expression changes were evaluated by quantitative real-time polymerase chain reaction at the end of each incubation period. RESULTS: Pg impaired pHAEC viability 24 hours post-infection. Pg infection reduced mRNA expression levels of endothelial NOS (eNOS), Nrf2, and Phase II enzymes (heme oxygenase-1, catalase, superoxide dismutase-1) in a time-dependent manner. Significant (P <0.05) increase in the inflammatory markers (interleukin [IL]-1ß, IL-6, and tumor necrosis factor-α) were observed in the medium as well as in the infected cells. Interestingly, inducible NOS mRNA levels showed a significant (P <0.05) increase at 12 hours and 24 hours and were reduced at later time points. BH4 (cofactor of eNOS) biosynthesis enzyme dihydrofolate reductase (DHFR, salvage pathway) mRNA levels showed a significant (P <0.05) decrease, while mRNA levels of GSK-3ß were elevated. CONCLUSIONS: These results suggest that periodontal bacterial infection may cause significant changes in the endothelial GSK-3ß/BH4 /eNOS/Nrf2 pathways, which may lead to impaired vascular relaxation. Greater understanding of the factors that adversely affect endothelial cell function could contribute to the development of new therapeutic compounds to treat PD-induced vascular diseases.

Sugar-Sweetened Beverage Consumption and Caries Prevalence in Underserved Black Adolescents.

Purpose: The purpose of this study was to examine the association between sugar-sweetened beverage (SSB) consumption and dental caries prevalence among underserved Black adolescents. Methods: This was a cross-sectional study of 545 Black adolescents, ages 12 to 17 years, who participated in the Howard Meharry Adolescent Caries Study (HMACS). The outcome was dental caries prevalence, measured using the decayed, missing, and filled permanent tooth surfaces (DMFS) index. Participants were recruited from middle and high schools in Washington, D.C., USA, and Nashville, Tenn., USA. Questionnaires were used to assess beverage intake, demographic, and health-related behavioral characteristics. The multivariable analysis used marginalized zero-inflated Poisson regression (MZIP) stratified by toothbrushing frequency to estimate adjusted mean caries ratios (MRs), adjusted odds ratios (ORs), and 95 percent confidence intervals (95 percent CIs). Results: The mean age of the participants was 14.1 years. Participants in the highest quartile for SSB consumption had a higher caries ratio than those in the lowest quartile [MR equals (=) 1.59, 95 percent CI equals 1.15 to 2.20] and a lower odds of not being at risk for caries (OR = 0.24, 95 percent CI = 0.09 to 0.61). These findings were only observed among those brushing once a day or less (n =202). Conclusions: Among Black adolescents in this study who brushed once a day or less, high levels of sugar-sweetened beverage consumption were associated with greater caries prevalence and a reduced likelihood of remaining caries-free than those with lower levels of SSB consumption. Future studies will focus on interventions to reduce SSB consumption.

Food Insecurity, Meal Behaviors, Beverage Intake, and Body Mass Index in Underserved Adolescents.

OBJECTIVE: Associations between food insecurity, meal patterns, beverage intake, and body mass index (BMI) were investigated using data from the Howard Meharry Adolescent Caries Study. METHODS: Secondary analyses of food security status used the Wilcoxon rank sum, chi-square, and Fisher's exact tests. RESULTS: The group of adolescents (n=627) was 42.1% male, 14.2±1.9 years, 86.9% African American, and 19.9% food-insecure. Meal frequency, meal structure, most beverage intake, and BMI did not differ by food-security status. Adolescents from Washington, DC were more likely to be food insecure than adolescents from Nashville, TN (P=0.003). Most had unstructured meal patterns and irregular breakfast intake. Median milk intake was below and sugar-sweetened beverage intake above dietary recommendations. CONCLUSIONS: This study extends our knowledge concerning food insecurity in urban African American adolescents and suggests public health initiatives designed to encourage meal structure, increase milk intake, and reduce sugar-sweetened beverage intake can improve diet quality of underserved youth.

An Approach to Engaging Schools In Oral Health Initiatives: The Howard Meharry Adolescent Caries Study (HMACS).

Use of community-based participatory research (CBPR) principles can help identify strategies for development and implementation of studies that can address oral health disparities disfavoring African American youth. This paper summarizes approaches of the Howard Meharry Adolescent Caries Study (HMACS) to provide sustained oral health services beyond the life of a research study.

Identification of Specific Oral and Gut Pathogens in Full Thickness Colon of Colitis Patients: Implications for Colon Motility.

Impaired colon motility is one of the leading problems associated with inflammatory bowel disease (IBD). An expanding body of evidence supports the role of microbiome in normal gut function and in progression of IBD. The objective of this work is to determine whether diseased full thickness colon specimens, including the neuromuscular region (critical for colon motility function), contain specific oral and gut pathogens. In addition, we compared the differences in colon microbiome between Caucasians (CA) and African Americans (AA). Thirty-nine human full thickness colon (diseased colon and adjacent healthy colon) specimens were collected from Crohn's Colitis (CC) or Ulcerative Colitis (UC) patients while they underwent elective colon surgeries. We isolated and analyzed bacterial ribosomal RNA (rRNA) from colon specimens by amplicon sequencing of the 16S rRNA gene region. The microbiome proportions were quantified into Operational Taxonomic Units (OTUs) by analysis with Quantitative Insights Into Microbial ecology (QIIME) platform. Two hundred twenty-eight different bacterial species were identified by QIIME analysis. However, we could only decipher the species name of fifty-three bacteria. Our results show that proportion of non-detrimental bacteria in CC or UC colon samples were altered compared to adjacent healthy colon specimens. We further show, for the first time in full thickness colon specimens, that microbiome of CC and UC diseased specimens is dominated by putative oral pathogens belonging to the Phyla Firmicutes (Streptococcus, Staphylococcus, Peptostreptococcus), and Fusobacteria (Fusobacterium). In addition, we have identified patterns of differences in microbiome levels between CA and AA specimens with potential implications for health disparities research. Overall, our results suggest a significant association between oral and gut microbes in the modulation of colon motility in colitis patients.