Frequency of Tongue Cleaning Impacts the Human Tongue Microbiome Composition and Enterosalivary Circulation of Nitrate.

The oral microbiome has the potential to provide an important symbiotic function in human blood pressure physiology by contributing to the generation of nitric oxide (NO), an essential cardiovascular signaling molecule. NO is produced by the human body via conversion of arginine to NO by endogenous nitric oxide synthase (eNOS) but eNOS activity varies by subject. Oral microbial communities are proposed to supplement host NO production by reducing dietary nitrate to nitrite via bacterial nitrate reductases. Unreduced dietary nitrate is delivered to the oral cavity in saliva, a physiological process termed the enterosalivary circulation of nitrate. Previous studies demonstrated that disruption of enterosalivary circulation via use of oral antiseptics resulted in increases in systolic blood pressure. These previous studies did not include detailed information on the oral health of enrolled subjects. Using 16S rRNA gene sequencing and analysis, we determined whether introduction of chlorhexidine antiseptic mouthwash for 1 week was associated with changes in tongue bacterial communities and resting systolic blood pressure in healthy normotensive individuals with documented oral hygiene behaviors and free of oral disease. Tongue cleaning frequency was a predictor of chlorhexidine-induced changes in systolic blood pressure and tongue microbiome composition. Twice-daily chlorhexidine usage was associated with a significant increase in systolic blood pressure after 1 week of use and recovery from use resulted in an enrichment in nitrate-reducing bacteria on the tongue. Individuals with relatively high levels of bacterial nitrite reductases had lower resting systolic blood pressure. These results further support the concept of a symbiotic oral microbiome contributing to human health via the enterosalivary nitrate-nitrite-NO pathway. These data suggest that management of the tongue microbiome by regular cleaning together with adequate dietary intake of nitrate provide an opportunity for the improvement of resting systolic blood pressure.

Poor Oral Health Linked with Increased Risk of Infectious Complications in Adults with Leukemia.

OBJECTIVE: The objective of this study is to examine the impact of the presence of gingivitis/periodontitis on the occurrence of infectious complications (including septicemia, bacterial infections, and mycoses) in hospitalized leukemic adults in the United States. METHODS: A retrospective analysis of the Nationwide Inpatient Sample (NIS) for the years 2004-2010 was performed. All hospitalized leukemic patients aged 18 to 65 years were selected. The association between occurrence of gingivitis/periodontitis and infectious complications was examined by multivariable logistic regression models. A total of 135,692 hospitalizations were due to leukemias during the study period. Among these, gingivitis/periodontitis was present in 0.6%. Septicemia occurred in 27.8% of those who had gingivitis/periodontitis (compared to 19.6% in those without gingivitis/periodontitis), bacterial infections occurred in 19.5% of those who had gingivitis/periodontitis (compared to 10.1% in those without gingivitis/periodontitis), and mycoses occurred in 20.7% of those who had gingivitis/periodontitis (compared to 10.7% in those without gingivitis/periodontitis). Patients who had gingivitis/periodontitis were associated with significantly higher odds for septicemia (OR = 1.58, 95% CI = 1.14-2.19, p = 0.01), bacterial infections (OR = 2.15, 95% CI = 1.51-3.07, p<0.01), mycoses (OR = 2.16, 95% CI = 1.43-3.28, p<0.01), or any infectious complication (OR = 2.15, 95% CI = 1.63-2.84, p<0.01) when compared to their counterparts following adjustment for multiple patient and hospital-level confounding factors. CONCLUSIONS: Poor oral health (as defined by the presence of gingivitis/periodontitis) is an independent predictor of increased risk of infectious complications in hospitalized leukemic adults in the United States.

Hospital-based emergency department visits with herpetic gingivostomatitis in the United States.

OBJECTIVES: The objectives of this study were to determine the number of hospital emergency department (ED) visits with a diagnosis of herpetic gingivostomatitis (HGS) for 2007 in the United States and to identify the possible comorbid conditions associated with HGS. STUDY DESIGN: The Nationwide Emergency Department Sample for 2007 was used in this study. Patients who visited the ED with a diagnosis of HGS were selected. Estimates were projected to the national levels using the discharge weights. Presence of comorbid conditions in these patients was also analyzed. RESULTS: A total of 23,124 patients had ED visits and received the diagnosis of HGS. Most of the patients were young females and those belonging to the lower socioeconomic strata. All patients with HGS also presented with comorbid conditions. CONCLUSIONS: Physicians should be trained to diagnose, manage, and refer common dental emergencies. In the long term, improving access to dental care for these patients is crucial to managing this problem.

MMP-9/TIMP-1 imbalance induced in human dendritic cells by Porphyromonas gingivalis.

Matrix metalloproteinase-9 (MMP-9) cleaves collagen, allowing leukocytes to traffic toward the vasculature and the lymphatics. When MMP-9 is unregulated by tissue inhibitor of metalloproteinase-1 (TIMP-1), this can lead to tissue destruction. Dendritic cells (DCs) infiltrate the oral mucosa increasingly in chronic periodontitis, characterized by infection with several pathogens including Porphyromonas gingivalis. In this study, human monocyte-derived DCs were pulsed with different doses of lipopolysaccharide of P. gingivalis 381 and of Escherichia coli type strain 25922, as well as whole live isogenic fimbriae-deficient mutant strains of P. gingivalis 381. Levels of induction of MMP-9 and TIMP-1, as well as interleukin-10 (IL-10), which reportedly inhibits MMP-9 induction, were measured by several approaches. Our results reveal that lipopolysaccharide of P. gingivalis, compared with lipopolysaccharide from E. coli type strain 25922, is a relatively potent inducer of MMP-9, but a weak inducer of TIMP-1, contributing to a high MMP-9/TIMP-1 ratio.Whole live P. gingivalis strain 381, major fimbriae mutant DPG-3 and double mutant MFB were potent inducers of MMP-9, but minor fimbriae mutant MFI was not. MMP-9 induction was inversely proportional to IL-10 induction. These results suggest that lipopolysaccharide and the minor and the major fimbriae of P. gingivalis may play distinct roles in induction by DCs of MMP-9, a potent mediator of local tissue destruction and leukocyte trafficking.