Denitrification in human dental plaque

Schreiber, Frank; Stief, Peter; Gieseke, Armin; Heisterkamp, Ines; Verstraete, Willy; Beer, Dirk de; Stoodley, Paul

doi:10.1186/1741-7007-8-24

Cited by 73 publications

(87 citation statements)

References 61 publications

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“…As suggested by work looking at nitrogen oxide production in the oral cavity, it is likely that salivary NO 2 − is converted to further reduced nitrogen oxides such as NO, nitrous oxide, ammonia, and/or nitrogen gas [41; 42] and also reactive nitrogen oxide species [43] by bacteria which make up the human oral microbiome [44]. Additionally, the acidic milieu of the gastric lumen will likely affect the levels of plasma NO 2 − as evident in research showing increased NO levels after swallowing NO 2 − containing saliva [21; 22].…”

Section: Discussionmentioning

confidence: 99%

The relationship between plasma and salivary NOx

et al. 2015

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Several studies have shown that fasting plasma nitrite (NO2−) is an indicator of endothelial nitric oxide synthase (NOS) activity while plasma nitrate (NO3−) or the sum of NO2− and NO3− (NOx) do not reflect NOS function. Plasma NO2− can also be elevated through dietary NO3− where the NO3− is partially reduced to NO2− by oral bacteria and enters the plasma through the digestive system. NO3− is taken up from plasma by salivary glands and the cycle repeats itself. Thus, one may propose that salivary NO2− is an indicator of plasma NO2− and consequently of NO production. Many brands of nitric oxide (NO) saliva test strips have been developed that suggest that their product is indicative of circulatory NO availability. However, data supporting a relationship between salivary and plasma NO2− or NO bioavailability is lacking. Here we have measured basal salivary and plasma NO2− and NO3− to determine if any correlation exists between these in 13 adult volunteers. We found no significant correlation between basal salivary and plasma NO2−. Also no correlation exists between salivary NO3− and plasma NO2−. However, we did see a correlation between salivary NO3− and plasma NO3−, and between salivary NO2− and plasma NO3−. In a separate study, we compared the efficiency of salivary NO3− reduction with the efficacy of increasing plasma NO3− and NO2− after drinking beet juice, a high NO3−-containing beverage, in 10 adult volunteers. No significant correlation was observed between the ex vivo salivary reduction of NO3− to NO2− and plasma increases in NO3− or NO2−. These results suggest that measures of salivary NO3−, NO2− or NOx are not good indicators of endothelial function. In addition, the efficiency of saliva to reduce NO3− to NO2− ex-vivo does not demonstrate one’s ability to increase plasma NO2− following consumption of dietary NO3−.

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Section: Discussionmentioning

confidence: 99%

The relationship between plasma and salivary NOx

et al. 2015

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“…In a recent set of experiments using gut facultative anaerobes, Escherichia coli and several Lactobacillus sp ., there was an increase in the expression of nitrate reductase enzymes, an increase in nitrite formation, and a clear growth benefit in the setting of adequate nitrate as oxygen concentration decreases below 4% [233]. Conversely, microbiota isolated from dental plaque were capable of denitrification under aerobic conditions, supporting the idea that biological activity is regulated by multiple forms of nitrate reductase enzymes[192]. Biologically important nitrate reduction, therefore, arises from regional interactions between oxygen tension, nitrate concentration, and microbial genetics.…”

Section: The Oral Microbiome and Bacterial Nitrate Reductionmentioning

confidence: 99%

Enterosalivary nitrate metabolism and the microbiome: Intersection of microbial metabolism, nitric oxide and diet in cardiac and pulmonary vascular health

Koch

Gladwin

Freeman

et al. 2017

Free Radical Biology and Medicine

141

127

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Recent insights into the bioactivation and signaling actions of inorganic, dietary nitrate and nitrite now suggest a critical role for the microbiome in the development of cardiac and pulmonary vascular diseases. Once thought to be the inert, end-products of endothelial-derived nitric oxide (NO) heme-oxidation, nitrate and nitrite are now considered major sources of exogenous NO that exhibit enhanced vasoactive signaling activity under conditions of hypoxia and stress. The bioavailability of nitrate and nitrite depend on the enzymatic reduction of nitrate to nitrite by a unique set of bacterial nitrate reductase enzymes possessed by specific bacterial populations in the mammalian mouth and gut. The pathogenesis of pulmonary hypertension (PH), obesity, hypertension and CVD are linked to defects in NO signaling, suggesting a role for commensal oral bacteria to shape the development of PH through the formation of nitrite, NO and other bioactive nitrogen oxides. Oral supplementation with inorganic nitrate or nitrate-containing foods exert pleiotropic, beneficial vascular effects in the setting of inflammation, endothelial dysfunction, ischemia-reperfusion injury and in pre-clinical models of PH, while traditional high-nitrate dietary patterns are associated with beneficial outcomes in hypertension, obesity and CVD. These observations highlight the potential of the microbiome in the development of novel nitrate- and nitrite-based therapeutics for PH, CVD and their risk factors.

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“…Salivary nitrate and the capacity of the microbiota to reduce nitrate to nitrite also appear to have an anti-caries effect, possibly due the production of ammonia and antimicrobial nitric oxide or the consumption of lactate by nitrate reducing species (Doel 2004;Li 2007). Additionally, at pH 5 or lower, acidic decomposition of nitrite to nitric oxide takes place (Schreiber 2010), which could provide negative feedback to acidification (figure 3, blue box "nitrite  nitric oxide").…”

Section: Resilience To Carbohydrate Consumption and Acidificationmentioning

confidence: 99%

“…Nitrate is an electron acceptor used in the respiration of nitrate-reducing bacteria, leading to the production of nitric oxide, a molecule with antimicrobial properties (Schreiber 2010).…”

Section: Role Of Saliva In Ecological Stabilitymentioning

confidence: 99%

Resilience of the Oral Microbiota in Health: Mechanisms That Prevent Dysbiosis

2017

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word count: 278Reference number: 61 Figures: 6 2 AbstractDental diseases are now viewed as a consequence of a deleterious shift in the balance of the normally stable resident oral microbiome. It is known that frequent carbohydrate consumption or reduced saliva flow can lead to caries, and excessive plaque accumulation increases the risk of periodontal diseases. However, when these disease drivers are present, while some individuals appear to be susceptible, others are more tolerant or resilient to suffering from undesirable changes in their oral microbiome. Health-maintaining mechanisms that limit the effect of disease drivers include the complex set of metabolic and functional inter-relationships that develop within dental biofilms and between biofilms and the host. In contrast, 'positive feedback loops' can develop within these microbial communities that disrupt resilience and provoke a large and abrupt change in function and structure of the ecosystem (a microbial 'regime shift'), that promotes dysbiosis and oral disease. For instance, acidification due to carbohydrate fermentation or inflammation in response to accumulated plaque select for a cariogenic or periopathogenic microbiota, respectively, in a chain of selfreinforcing events. Conversely, in tolerant individuals, health-maintaining mechanisms, including negative feedback to the drivers, can maintain resilience and promote resistance to and recovery from disease drivers. Recently studied health-maintaining mechanisms include ammonium production, limiting a drop in pH that can lead to caries, and denitrification, which could inhibit several stages of disease-associated positive feedback loops. OMICS studies comparing the microbiome of, and its interaction with, susceptible and tolerant hosts can detect markers of resilience. The neutralization or inhibition of these 'disease drivers', together with the identification and promotion of health-promoting species and functions, for example by pre-and probiotics, could enhance microbiome resilience and lead to new strategies to prevent disease.3

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Denitrification in human dental plaque

Cited by 73 publications

References 61 publications

The relationship between plasma and salivary NOx

The relationship between plasma and salivary NOx

Enterosalivary nitrate metabolism and the microbiome: Intersection of microbial metabolism, nitric oxide and diet in cardiac and pulmonary vascular health

Resilience of the Oral Microbiota in Health: Mechanisms That Prevent Dysbiosis

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