Oral nitrate reductase activity and erosive gastro-esophageal reflux disease: a nitrate hypothesis for GERD pathogenesis

Chinese expert consensus on diagnosis and management of gastroesophageal reflux disease in the elderly (2023)

Gastroesophageal reflux disease (GERD) in the elderly is characterized by atypical symptoms, relatively severe esophageal injury, and more complications, and when GERD is treated, it is also necessary to fully consider the general health condition of the elderly patients. This consensus summarized the epidemiology, pathogenesis, clinical manifestations, and diagnosis and treatment characteristics of GERD in the elderly, and provided relevant recommendations, providing guidance for medical personnel to correctly understand and standardize the diagnosis and treatment of GERD in the elderly.

From nitrate to NO: potential effects of nitrate-reducing bacteria on systemic health and disease

Current research has described improving multisystem disease and organ function through dietary nitrate (DN) supplementation. They have provided some evidence that these floras with nitrate (NO3-) reductase are mediators of the underlying mechanism. Symbiotic bacteria with nitrate reductase activity (NRA) are found in the human digestive tract, including the mouth, esophagus and gastrointestinal tract (GT). Nitrate in food can be converted to nitrite under the tongue or in the stomach by these symbiotic bacteria. Then, nitrite is transformed to nitric oxide (NO) by non-enzymatic synthesis. NO is currently recognized as a potent bioactive agent with biological activities, such as vasodilation, regulation of cardiomyocyte function, neurotransmission, suppression of platelet agglutination, and prevention of vascular smooth muscle cell proliferation. NO also can be produced through the conventional L-arginine-NO synthase (L-NOS) pathway, whereas endogenous NO production by L-arginine is inhibited under hypoxia-ischemia or disease conditions. In contrast, exogenous NO3-/NO2-/NO activity is enhanced and becomes a practical supplemental pathway for NO in the body, playing an essential role in various physiological activities. Moreover, many diseases (such as metabolic or geriatric diseases) are primarily associated with disorders of endogenous NO synthesis, and NO generation from the exogenous NO3-/NO2-/NO route can partially alleviate the disease progression. The imbalance of NO in the body may be one of the potential mechanisms of disease development. Therefore, the impact of these floras with nitrate reductase on host systemic health through exogenous NO3-/NO2-/NO pathway production of NO or direct regulation of floras ecological balance is essential (e.g., regulation of body homeostasis, amelioration of diseases, etc.). This review summarizes the bacteria with nitrate reductase in humans, emphasizing the relationship between the metabolic processes of this microflora and host systemic health and disease. The potential effects of nitrate reduction bacteria on human health and disease were also highlighted in disease models from different human systems, including digestive, cardiovascular, endocrine, nervous, respiratory, and urinary systems, providing innovative ideas for future disease diagnosis and treatment based on nitrate reduction bacteria.

Nitrate and the Origin of Saliva Influence Composition and Short Chain Fatty Acid Production of Oral Microcosms

Nitrate is emerging as a possible health benefactor. Especially the microbial conversion of nitrate to nitrite in the oral cavity and the subsequent conversion to nitric oxide in the stomach are of interest in this regard. Yet, how nitrate influences the composition and biochemistry of the oral ecosystem is not fully understood. To investigate the effect of nitrate on oral ecology, we performed a 4-week experiment using the multiplaque artificial mouth (MAM) biofilm model. This model was inoculated with stimulated saliva of two healthy donors. Half of the microcosms (n = 4) received a constant supply of nitrate, while the other half functioned as control (n = 4). Additionally, all microcosms received a nitrate and sucrose pulse, each week, on separate days to measure nitrate reduction and acid formation. The bacterial composition of the microcosms was determined by 16S rDNA sequencing. The origin of the saliva (i.e., donor) showed to be the strongest determinant for the development of the microcosms. The supplementation of nitrate was related to a relatively high abundance of Neisseria in the microcosms of both donors, while Veillonella was highly abundant in the nitrate-supplemented microcosms of only one of the donors. The lactate concentration after sucrose addition was similarly high in all microcosms, irrespective of treatment or donor, while the concentration of butyrate was lower after nitrate addition in the nitrate-receiving microcosms. In conclusion, nitrate influences the composition and biochemistry of oral microcosms, although the result is strongly dependent on the inoculum.

Value of the Gastroesophageal Reflux Disease Questionnaire (GerdQ) in predicting the proton pump inhibitor response in coronary artery disease patients with gastroesophageal reflux-related chest pain

Chest pain experienced by patients with coronary artery disease can be partly due to gastroesophageal reflux-induced chest pain (GERP). Empirical proton pump inhibitor (PPI) therapy has been recommended as an initial clinical approach for treating GERP. However, PPI use may lead to some health problems. The Gastroesophageal Reflux Disease Questionnaire (GerdQ) may represent a noninvasive and cost-effective approach for avoiding PPI misuse and for identifying the appropriate patients for the PPI trial test. The aim of this pilot study was to prospectively evaluate the association between GerdQ scores and PPI response in patients with coronary artery disease (CAD) and GERP to determine whether the GerdQ predicts the PPI response in patients with CAD and GERP and to further validate the clinical application value of the GerdQ. A total of 154 consecutive patients with potential GERP were recruited to complete a GerdQ with subsequent PPI therapy. Based on the PPI trial result, patients were divided into a PPI-positive response group and a PPI-negative response group. The difference in the GerdQ scores between the two groups was assessed. The receiver operating characteristic (ROC) curve of GerdQ score was drawn according to the PPI response as the gold standard. The ability of GerdQ to predict the PPI response was assessed. A total of 96 patients completed the entire study; 62 patients (64.6%) were assigned to the PPI-positive response group, and 34 patients (35.4%) to the PPI-negative response group. The GerdQ score of the PPI-positive response group (8.11 ± 3.315) was significantly higher than that of the PPI-negative response group (4.41 ± 2.743), and the difference was statistically significant (t = 5.863, P = 0.000). The ROC curve was drawn according to a PPI response assessment result with a score above 2 as the gold standard. The area under curve was 0.806. When the critical value of GerdQ score was 7.5, Youden index was up to 0.514, the diagnostic sensitivity was 0.661, and the diagnostic specificity was 0.853. A GerdQ score greater than 7.5 better predicts the response to the PPI trial therapy. There is a strong association between the GerdQ score and the response to PPI therapy. Higher GerdQ scores were predictive of a positive PPI response in CAD patients with GERP. The GerdQ may be a reasonable screening tool for GERP in patients with CAD who are prepared to accept PPI therapy.

Clinical effects of mosapride plus ranitidine vs mosapride plus rabeprazole for treatment of esophageal reflux laryngitis

AIM: To investigate the clinical effects of mosapride plus rabeprazole in patients with esophageal reflux laryngitis.

METHODS: One hundred and thirty esophageal reflux laryngitis patients treated at the Affiliated People's Hospital of Hubei Medical College from July 2011 to July 2014 were randomly divided into either a control group to receive mosapride plus ranitidine or a study group to receive mosapride and rabeprazole, with 65 cases in each group. The total response rate, percentage of time with pH < 4, and clinical symptom score were compared for the two groups.

RESULTS: The total response rate was significantly higher in the study group than in the control group (95.38% vs 67.69%, P < 0.05). After treatment, percentage of time with pH < 4 and clinical symptom score were significantly improved in both groups compared with pretreatment values, and the improvement was more significant in the study group than in the control group (P < 0.05). There was no significant difference between the two groups in the incidence of adverse reactions (P > 0.05).

CONCLUSION: Mosapride plus rabeprazole has a significant therapeutic effect in treating esophageal reflux laryngitis, and the combination therapy can reduce symptoms and has high safety.

Association between halitosis diagnosed by a questionnaire and halimeter and symptoms of gastroesophageal reflux disease

Background/Aims

The relationship between halitosis and gastroesophageal reflux disease (GERD) remains controversial. The aim of this study was to investigate an association between subjective and objective halitosis and GERD.

Methods

The subjects were enrolled from participants who visited a health promotion center at Seoul National University Bundang Hospital. For diagnosis of halitosis, a questionnaire was requested, and volatile sulfur compounds (VSCs) were measured by Halimeter. Self-conscious halitosis was defined as halitosis perceived by himself or herself. Informed halitosis was defined as halitosis perceived by others. Objective halitosis was defined when mean VSCs values were > 100 parts per billion. GERD was defined based on a questionnaire and endoscopy, including erosive esophagitis and non-erosive reflux disease (NERD).

Results

A total of 54 subjects (male:female = 33:21) with mean age of 46.0 ± 11.4 years were analyzed. The mean VSCs values were not significantly different between presence and absence of self-conscious halitosis (P = 0.322), but significantly different between presence and absence of informed halitosis (P = 0.021). Informed halitosis was associated with objective halitosis (P = 0.039). GERD, erosive esophagitis and NERD did not correlate with objective halitosis (P = 0.556, 0.206 and 0.902, respectively). In multivariable analysis, the relationship between objective halitosis and GERD symptoms including chest pain, heart burn, acid regurgitation, epigastric pain, hoarseness, globus sensation and coughing was not significant. Besides, GERD was not associated with self-conscious halitosis, informed halitosis and objective halitosis, respectively.

Conclusions

GERD might not be associated with self-conscious, informed halitosis and objective halitosis indicated by Halimeter results. Informed halitosis could be correlated with objective halitosis determined by the Halimeter.

Involvement of luminal nitric oxide in the pathogenesis of the gastroesophageal reflux disease spectrum

Over the last 3 decades, the incidence of esophageal adenocarcinoma has dramatically increased in Western countries; a similar increase may be observed in Asian countries in the near future. Esophageal adenocarcinoma arises from a sequential gastroesophageal reflux disease (GERD) spectrum from reflux erosive esophagitis, to Barrett's esophagus, and finally to esophageal adenocarcinoma. At present, gastric acid and bile are assumed to be primarily involved in the etiology of the GERD spectrum. We reported in 2002 that, at the gastroesophageal junction in humans, abundant amounts of nitric oxide (NO) are generated luminally through the entero-salivary re-circulation of dietary nitrate. Since then, we have carried out a series of experiments to demonstrate that NO diffuses into the adjacent epithelium at cytotoxic levels. This diffusion results in disruption of the epithelial barrier function, exacerbation of inflammation, acceleration of columnar transformation in the esophagus (Barrett's esophagus) via the induction of caudal-type homeobox 2, and the shifting of carcinogenic N-nitroso compound formation from the luminal to epithelial compartment. These results suggest that, in addition to conventionally recognized causative factors, luminal NO could also be involved in the pathogenesis of the GERD spectrum. In addition, we recently showed that there is a prominent gender-related difference in NO-related cytotoxicity in the esophagus and that estrogen attenuated the esophageal tissue damage via the estrogen receptor in female rats. The role of estrogen in attenuating the esophageal tissue damage in NO-related esophageal damage could explain the well-recognized male predominance in the GERD spectrum in humans.

Optimization of Nitrite Reductase Production Conditions in Lactobacillus plantarum from Salted Fish

The conditions for nitrite reductase (NiRs) produced by Lactobacillus plantarum from salted fish were optimized. Enzyme activity of nitrite reductase was used as evaluation index. The results showed that the pH value had greatest influence on enzyme activity. The optimum conditions of producing nitrite reductase were inoculate quantity 4 %, pH 6.3, culture temperature 35 °C, incubation time 48 h. The enzyme activity of nitrite reductase reached to 89.672 U/mL, which increased by 71 % after optimization. This work provided the foundation for the research of enzymatic properties of nitrite reductase. This may be useful to the production of salted fish products.