Inducible and neuronal nitric oxide synthase involvement in lipopolysaccharide-induced sphincteric dysfunction

The role of the esophageal and intestinal microbiome in gastroesophageal reflux disease: past, present, and future

Gastroesophageal reflux disease (GERD) is one of the common diseases of the digestive system, and its incidence is increasing year by year, in addition to its typical symptoms of acid reflux and heartburn affecting the quality of patients' survival. The pathogenesis of GERD has not yet been clarified. With the development of detection technology, microbiome have been studied in depth. Normal microbiome are symbiotic with the host and can assist the host to fulfill the roles of digestion and absorption, and promote the development of the host. Dysbiosis of the microbiome forms a new internal environment, under which it may affect the development of GERD from the perspectives of molecular mechanisms: microbial activation of Toll-like receptors, microbial stimulation of cyclooxygenase-2 expression, microbial stimulation of inducible nitrous oxide synthase, and activation of the NLRP3 inflammatory vesicle; immune mechanisms; and impact on the dynamics of the lower gastrointestinal tract. This review will explore the esophageal microbiome and intestinal microbiome characteristics of GERD and the mechanisms by which dysbiotic microbiome induces GERD.

The oral microbiome and oral and upper gastrointestinal diseases

Background

Microbiomes are essential components of the human body, and their populations are substantial. Under normal circumstances, microbiomes coexist harmoniously with the human body, but disturbances in this equilibrium can lead to various diseases. The oral microbiome is involved in the occurrence and development of many oral and gastrointestinal diseases. This review focuses on the relationship between oral microbiomes and oral and upper gastrointestinal diseases, and therapeutic strategies aiming to provide valuable insights for clinical prevention and treatment.

Methods

To identify relevant studies, we conducted searches in PubMed, Google Scholar, and Web of Science using keywords such as "oral microbiome," "oral flora, " "gastrointestinal disease, " without any date restrictions. Subsequently, the retrieved publications were subject to a narrative review.

Results

In this review, we found that oral microbiomes are closely related to oral and gastrointestinal diseases such as periodontitis, dental caries, reflux esophagitis, gastritis, and upper gastrointestinal tumors (mainly the malignant ones). Oral samples like saliva and buccal mucosa are not only easy to collect, but also display superior sample stability compared to gastrointestinal tissues. Consequently, analysis of the oral microbiome could potentially serve as an efficient preliminary screening method for high-risk groups before undergoing endoscopic examination. Besides, treatments based on the oral microbiomes could aid early diagnosis and treatment of these diseases.

Conclusions

Oral microbiomes are essential to oral and gastrointestinal diseases. Therapies centered on the oral microbiomes could facilitate the early detection and management of these conditions.

Lactic acid bacteria in relieving constipation: mechanism, clinical application, challenge, and opportunity

Constipation is a prevalent gastrointestinal symptom that can considerably affect a patients' quality of life. Although several drugs have been used to treat constipation, they are associated with high costs, side effects, and low universality. Therefore, alternative intervention strategies are urgently needed. Traditional lactic acid bacteria (LAB), such as Bifidobacterium and Lactobacillus, play a vital role in regulating intestinal microecology and have demonstrated favorable effects in constipation; however, a comprehensive review of their constipation relief mechanisms is limited. This review summarizes the pathogenesis of constipation and the relationship between intestinal motility and gut microbiota, elucidates the possible mechanism by which LAB alleviates of constipation through a systematic summary of animal and clinical research, and highlights the challenges and applications of LAB in the treatment of constipation. Our review can improve our understanding of constipation, and advance targeted microecological therapeutic agents, such as LAB.

Evidence for proton-pump inhibitor (PPI)-associated dysbiosis in metabolically unhealthy obesity

Obesity adversely impacts millions of American adults by predisposing them to significant health risks and further complications. Obesity is differentiated into two groups: metabolically healthy and metabolically unhealthy. In contrast to metabolically healthy counterparts, obese individuals who are metabolically unhealthy display hallmark symptoms of metabolic syndrome (e.g., hypertension, dyslipidemia, hyperglycemia, abdominal obesity). Gastroesophageal reflux disease (GERD) commonly occurs in all obese populations, as do poor dietary habits. Proton-pump inhibitors (PPIs), due to their wide availability, are most often used to treat GERD-related heartburn and other symptoms. Here, we review the evidence on how poor diet as well as short- and long-term use of PPIs adversely affect the gastrointestinal microbiota to cause dysbiosis. Key components of dysbiosis-induced metabolically unhealthy obesity (MUO) associated with PPI use include "leaky gut," systemic low-grade inflammation, and reduced amounts of short-chain fatty acids (SCFAs) such as butyrate that promote metabolic health. The benefit of using probiotics to mitigate PPI-induced dysbiosis and MUO is also discussed.

The Role of Microbiota in the Pathogenesis of Esophageal Adenocarcinoma

Simple Summary

Esophageal adenocarcinoma has a poor 5-year survival rate and is among the highest mortality cancers. Changes in the esophageal microbiome have been associated with cancer pathogenesis; however, the molecular mechanism remains obscure. This review article critically analyzes the molecular mechanisms through which microbiota may mediate the development and progression of esophageal adenocarcinoma and its precursors-gastroesophageal reflux disease and Barrett’s esophagus. It summarizes changes in esophageal microbiome composition in normal and pathologic states and subsequently discusses the role of altered microbiota in disease progression. The potential role of esophageal microbiota in protecting against the development of esophageal adenocarcinoma is also discussed. By doing so, this article highlights specific directions for future research developing microbiome-mediated therapeutics for esophageal adenocarcinoma.

Abstract

Esophageal adenocarcinoma (EAC) is associated with poor overall five-year survival. The incidence of esophageal cancer is on the rise, especially in Western societies, and the pathophysiologic mechanisms by which EAC develops are of extreme interest. Several studies have proposed that the esophageal microbiome may play an important role in the pathophysiology of EAC, as well as its precursors—gastroesophageal reflux disease (GERD) and Barrett’s esophagus (BE). Gastrointestinal microbiomes altered by inflammatory states have been shown to mediate tumorigenesis directly and are now being considered as novel targets for both cancer treatment and prevention. Elucidating molecular mechanisms through which the esophageal microbiome potentiates the development of GERD, BE, and EAC will provide a foundation on which new therapeutic targets can be developed. This review summarizes current findings that elucidate the molecular mechanisms by which microbiota promote the pathogenesis of GERD, BE, and EAC, revealing potential directions for additional research on the microbiome-mediated pathophysiology of EAC.

Dietary habits in Greek children with functional constipation based on Rome III criteria: a school-based, cross-sectional multivariate analysis

Background

Functional constipation (FC) is the most common gastrointestinal disorder of childhood and has a multifactorial etiology. We aimed to assess dietary habits in Greek children with FC compared to the general population (control group, CG).

Methods

This was a subgroup analysis of a school-based, cross-sectional study carried out in children 6-18 years of age, between January and June 2014, using the Rome III criteria for the diagnosis of FC. Dietary parameters, as well as socioeconomic and demographic data and their association with the likelihood of FC, were analyzed through multivariate logistic regression analysis and expressed as odds ratios (OR).

Results

A total of 1439 children (1218 CG, 221 FC) were included in the analysis. The final model showed that consumption of was the only dietary parameter significantly related to FC; higher frequency of consumption was inversely related to the likelihood of FC (OR: 0.98, 95% CI: 0.96, 0.99, P=0.048). Significant socioeconomic confounders with a positive association with FC were: parental educational level, victimization, physical activity and number of adults at home.

Conclusions

Increased frequency of fiber consumption is significantly associated with higher odds of FC irrespective of socioeconomic background and lifestyle parameters. Interventional studies are required to validate these cross-sectional observations.

Microbiome of the Aerodigestive Tract in Health and Esophageal Disease

The diverse human gut microbiome is comprised of approximately 40 trillion microorganisms representing up to 1000 different bacterial species. The human microbiome plays a critical role in gut epithelial health and disease susceptibility. While the interaction between gut microbiome and gastrointestinal pathology is increasingly understood, less is known about the interaction between the microbiome and the aerodigestive tract. This review of the microbiome of the aerodigestive tract in health, and alterations in microbiome across esophageal pathologies highlights important findings and areas for future research. First, microbiome profiles are distinct along the aerodigestive tract, spanning the oral cavity to the stomach. In patients with reflux-related disease such as gastro-esophageal reflux disease, Barrett's esophagus, and esophageal adenocarcinoma, investigators have observed an overall increase in gram negative bacteria in the esophageal microbiome compared to healthy individuals. However, whether differences in microbiome promote disease development, or if these shifts are a consequence of disease remains unknown. Interestingly, use of proton pump inhibitor therapy is also associated with shifts in the microbiome, with distinct shifts and patterns along the aerodigestive tract. The relationship between the human gut microbiome and esophageal pathology is a ripe area for investigation, and further understanding of these pathways may promote development of novel targets in prevention and therapy for esophageal diseases.

Mucosa-Associated Microbiota in Barrett's Esophagus, Dysplasia, and Esophageal Adenocarcinoma Differ Similarly Compared With Healthy Controls

INTRODUCTION

Alterations in the composition of the human gut microbiome and its metabolites have been linked to gut epithelial neoplasia. We hypothesized that differences in mucosa-adherent Barrett's microbiota could link to risk factors, providing risk of progression to neoplasia.

METHODS

Paired biopsies from both diseased and nonaffected esophagus (as well as gastric cardia and gastric juice for comparison) from patients with intestinal metaplasia (n = 10), low grade dysplasia (n = 10), high grade dysplasia (n = 10), esophageal adenocarcinoma (n = 12), and controls (n = 10) were processed for mucosa-associated bacteria and analyzed by 16S ribosomal ribonucleic acid V4 gene DNA sequencing. Taxa composition was tested using a generalized linear model based on the negative binomial distribution and the log link functions of the R Bioconductor package edgeR.

RESULTS

The microbe composition of paired samples (disease vs nondisease) comparing normal esophagus with intestinal metaplasia, low grade dysplasia, high grade dysplasia, and adenocarcinoma showed significant decreases in the phylum Planctomycetes and the archaean phylum Crenarchaeota (P < 0.05, false discovery rate corrected) in diseased tissue compared with healthy controls and intrasample controls (gastric juice and unaffected mucosa). Genera Siphonobacter, Balneola, Nitrosopumilus, and Planctomyces were significantly decreased (P < 0.05, false discovery rate corrected), representing <10% of the entire genus community. These changes were unaffected by age, tobacco use, or sex for Crenarcha.

DISCUSSSION

There are similar significant changes in bacterial genera in Barrett's esophageal mucosa, dysplasia, and adenocarcinoma compared with controls and intrapatient unaffected esophagus. Further work will establish the biologic plausibility of these specific microbes' contributions to protection from or induction of esophageal epithelial dysplasia.

Caspase-11-mediated enteric neuronal pyroptosis underlies Western diet-induced colonic dysmotility

Enteric neuronal degeneration, as seen in inflammatory bowel disease, obesity, and diabetes, can lead to gastrointestinal dysmotility. Pyroptosis is a novel form of programmed cell death but little is known about its role in enteric neuronal degeneration. We observed higher levels of cleaved caspase-1, a marker of pyroptosis, in myenteric ganglia of overweight and obese human subjects compared with normal-weight subjects. Western diet-fed (WD-fed) mice exhibited increased myenteric neuronal pyroptosis, delayed colonic transit, and impaired electric field stimulation-induced colonic relaxation responses. WD increased TLR4 expression and cleaved caspase-1 in myenteric nitrergic neurons. Overactivation of nitrergic neuronal NF-κB signaling resulted in increased pyroptosis and delayed colonic motility. In caspase-11-deficient mice, WD did not induce nitrergic myenteric neuronal pyroptosis and colonic dysmotility. To understand the contributions of saturated fatty acids and bacterial products to the steps leading to enteric neurodegeneration, we performed in vitro experiments using mouse enteric neurons. Palmitate and lipopolysaccharide (LPS) increased nitrergic, but not cholinergic, enteric neuronal pyroptosis. LPS gained entry to the cytosol in the presence of palmitate, activating caspase-11 and gasdermin D, leading to pyroptosis. These results support a role of the caspase-11-mediated pyroptotic pathway in WD-induced myenteric nitrergic neuronal degeneration and colonic dysmotility, providing important therapeutic targets for enteric neuropathy.

Prebiotic UG1601 mitigates constipation-related events in association with gut microbiota: A randomized placebo-controlled intervention study

BACKGROUND

Constipation is a common functional gastrointestinal disorder and its etiology is multifactorial. Growing evidence suggests that intestinal dysbiosis is associated with the development of constipation. Prebiotics are subjected to bacterial fermentation in the gut to produce short-chain fatty acids (SCFAs), which can help relieve constipation symptoms. The prebiotic UG1601 consists of inulin, lactitol, and aloe vera gel, which are known laxatives, but randomized, controlled clinical trials that examine the effects of this supplement on gut microbiota composition are lacking.

AIM

To assess the efficacy of the prebiotic UG1601 in suppressing constipation-related adverse events in subjects with mild constipation.

METHODS

Adults with a stool frequency of less than thrice a week were randomized to receive either prebiotics or a placebo supplement for 4 wk. All participants provided their fecal and blood samples at baseline and at the end of intervention. Gastrointestinal symptoms and stool frequency were evaluated. The concentrations of serum endotoxemia markers and fecal SCFAs were determined. The relative abundance of SCFA-producing bacteria and the gut microbial community in the responders and non-responders in the prebiotics supplementation group were evaluated.

RESULTS

There were no significant differences in gastrointestinal symptoms between groups, although the prebiotic group showed greater symptom improvement. However, after prebiotic usage, serum cluster of differentiation (CD) 14 and lipopolysaccharide (LPS) concentrations were significantly decreased (CD14, P = 0.012; LPS, P < 0.001). The change in LPS concentration was significantly larger in the prebiotic group than in the placebo group (P < 0.001). Fecal SCFAs concentrations did not differ between groups, while the relative abundance of Roseburia hominis, a major butyrate producer, was significantly increased in the prebiotic group (P = 0.045). The abundances of the phylum Firmicutes and the family Lachnospiraceae (phylum Firmicutes, class Clostridia) (P = 0.009) were decreased in the responders within the prebiotic group. In addition, the proportions of the phylum Firmicutes, the class Clostridia, and the order Clostridiales were inversely correlated with several fecal SCFAs (P < 0.05).

CONCLUSION

Alterations in gut microbiota composition, including a decrease in the phylum Firmicutes and an increase in butyrate-producing bacteria, following prebiotic UG1601 supplementation might help alleviate symptom scores and endotoxemia.

Achalasia and associated esophageal cancer risk: What lessons can we learn from the molecular analysis of Barrett's-associated adenocarcinoma?

Idiopathic achalasia and Barrett's esophagus (BE) are preneoplastic conditions of the esophagus. BE increases the risk of esophageal adenocarcinoma (EAC), while achalasia is associated with both EAC and esophageal squamous cell carcinoma (ESCC). However, while the molecular mechanisms underlying the transformation of esophageal epithelial cells in BE are relatively well characterized, less is known regarding these processes in achalasia. Nevertheless, both conditions are associated with chronic inflammation and BE can occur in achalasia patients, and it is likely that similar processes underlie cancer risk in both diseases. The present review will discuss possible lessons that we can learn from the molecular analysis of BE for the study of achalasia-associated cancer and contrast findings in BE with those in achalasia. First, we will describe cellular fate during development of BE, EAC, and ESCC, and consider the inflammatory status of the epithelial barrier in BE and achalasia in terms of its contribution to carcinogenesis. Next, we will summarize current data on genetic alterations and molecular pathways involved in these processes. Lastly, the plausible role of the microbiota in achalasia-associated carcinogenesis and its contribution to abnormal lower esophageal sphincter (LES) functioning, the maintenance of chronic inflammatory status and influence on the esophageal mucosa through carcinogenic by-products, will be discussed.

Alteration of Esophageal Microbiome by Antibiotic Treatment Does Not Affect Incidence of Rat Esophageal Adenocarcinoma

BACKGROUND

Recent studies suggest that chronic inflammation-associated cancer is relevant to microbiome. Esophageal adenocarcinoma arises from an inflammatory condition called Barrett's esophagus, which is caused by gastroesophageal reflux. We hypothesized that esophageal microbiome plays a role in carcinogenesis of esophageal adenocarcinoma.

AIM

We investigated whether alteration of microbiome using antibiotics affects the development of esophageal adenocarcinoma in a rat model.

METHODS

Seven-week-old male Wistar rats which had undergone esophagojejunostomy were divided into control (n = 21) and antibiotic groups (n = 22) at 21 weeks after surgery. Control animals were given drinking water, while the other group was given penicillin G and streptomycin in drinking water until rats were killed at 40 weeks after operation. Incidence rates of Barrett's esophagus and adenocarcinoma in each group were evaluated by histological analysis. DNA was extracted from a portion of the distal esophagus, and the microbiome was investigated using terminal restriction fragment length polymorphism (T-RFLP) analysis.

RESULTS

All rats in both groups developed Barrett's esophagus. Incidence of esophageal adenocarcinoma was similar between both groups with a trend to reduced incidence in the antibiotics group (89 % in the control group, 71 % in the antibiotics group, P = 0.365). T-RFLP analysis showed that esophageal microbiome was different between two groups such as the proportion of Lactobacillales was lower in the antibiotics group and Clostridium cluster XIVa and XVIII was higher in the antibiotics group.

CONCLUSIONS

Alteration of microbiome does not affect the incidence of esophageal adenocarcinoma. Microbiome may not contribute to the development of esophageal adenocarcinoma.

Potential Role of the Microbiome in Barrett's Esophagus and Esophageal Adenocarcinoma

Esophageal adenocarcinoma and its precursor Barrett's esophagus have been rapidly increasing in incidence for half a century, for reasons not adequately explained by currently identified risk factors such as gastroesophageal reflux disease and obesity. The upper gastrointestinal microbiome may represent another potential cofactor. The distal esophagus has a distinct microbiome of predominantly oral-derived flora, which is altered in Barrett's esophagus and reflux esophagitis. Chronic low-grade inflammation or direct carcinogenesis from this altered microbiome may combine with known risk factors to promote Barrett's metaplasia and progression to adenocarcinoma.

Intestinal microbiota and chronic constipation

Chronic constipation is a prevalent, burdensome gastrointestinal disorder whose aetiology and pathophysiology remains poorly understood and is most likely multifactorial. Differences in the composition of the intestinal microbiota have been demonstrated when constipated patients and healthy controls have been compared. Growing evidence indicates that alterations of intestinal microbiota may contribute to constipation and constipation-related symptoms. The intestinal microbiota is a collection of microorganisms that live within the gastrointestinal tract, and perform many important health-promoting functions. The intestinal microbiota aids in the breakdown of food products into absorbable nutrients, stimulates the host immune system, prevents growth of pathogenic bacteria and produces a great variety of biologically important compounds. In this review, we will summarize the current evidence supporting roles of the intestinal microbiota in the pathogenesis and management of chronic constipation. The discussion will shed light on the novel mechanisms of intestinal microbiota and gut function interactions, which is invaluable in ultimately developing new therapeutic tools for the treatment of chronic constipation.

Microbiome and potential targets for chemoprevention of esophageal adenocarcinoma

Esophageal cancer is one of the deadliest cancers, with a dismal prognosis. It is increasingly recognized that esophageal cancer is a heterogeneous disease. It can be subdivided into two distinct groups: squamous cell carcinoma and adenocarcinoma, based on histological appearance. In the Western world, the incidence of squamous cell carcinoma was considerably higher than esophageal adenocarcinoma (EA) until the 1990s when, due to a dramatic increase, the incidence of EA surpassed that of squamous cell carcinoma. EA typically follows a well-established stepwise evolution from chronic inflammation due to reflux esophagitis (RE) that progresses to metaplasia (Barrett's esophagus [BE]) to dysplasia, which often culminates in EA. The pathophysiology of EA is complex and involves diverse factors, including gastroesophageal reflux, gastric acid secretion, dysfunction of the antireflux barrier, gastric emptying disturbances, and abnormalities in esophageal defense mechanisms. The current understanding of the etiology of EA is mainly derived from epidemiological studies of risk factors such as cigarette smoking, obesity, gastroesophageal reflux disorders (GERD), and low fruit and vegetable consumption. Numerous studies have been done, but the factors that drive the dynamic increase in the incidence of EA remain elusive. The advent of widespread antibiotic use occurred in the 1950s, preceding the surge of EA. Based on this temporal sequence, it has been hypothesized that antibiotics alter the microbiome to which the esophagus is exposed in patients who have GERD and that chronic exposure to this abnormal microbiome (ie, changes in species diversity or abundance) accounts for the increase in EA. If changes in the proposed factors alter the stepwise progression (RE-BE-dysplasia-EA), they may represent potential targets for chemoprevention. New discoveries will help improve our understanding of the biology and pathogenesis of these cancers, and aid in finding novel therapeutic targets.

The Influence of the Gut Microbiome on Obesity, Metabolic Syndrome and Gastrointestinal Disease

There is a fine balance in the mutual relationship between the intestinal microbiota and its mammalian host. It is thought that disruptions in this fine balance contribute/account for the pathogenesis of many diseases. Recently, the significance of the relationship between gut microbiota and its mammalian host in the pathogenesis of obesity and the metabolic syndrome has been demonstrated. Emerging data has linked intestinal dysbiosis to several gastrointestinal diseases including inflammatory bowel disease, irritable bowel syndrome, nonalcoholic fatty liver disease, and gastrointestinal malignancy. This article is intended to review the role of gut microbiota maintenance/alterations of gut microbiota as a significant factor as a significant factor discriminating between health and common diseases. Based on current available data, the role of microbial manipulation in disease management remains to be further defined and a focus for further clinical investigation.

Nitric oxide-mediated injury of interstitial cells of Cajal and intestinal dysmotility under endotoxemia of mice

Gastrointestinal dysmotility is frequently observed under septic conditions, yet its precise mechanisms remain to be elucidated. In this study, we have investigated the mechanisms of intestinal dysmotility by lipopolysaccharides (LPS) and the role of the interstitial cells of Cajal (ICCs) in motility disorders using a mouse endotoxin model. The injection of LPS caused time- and dose-dependent decreases in the intestinal contractility, which was associated with similar time- and dose-dependent decreases in the number of KIT-positive fibroblast-like cells located in the intermuscular layer. iNOS inhibitors, L-NAME and aminoguanidine (AG), but not 7-nitroindazole (7NI), a specific nNOS inhibitor, inhibited the LPS-induced decreases in both the contractility and the number of KIT-positive cells. A spontaneous NO releaser, FK409, not only diminished spontaneous electrical potential and phasic contractions, but also decreased the number of KIT-positive cells. Pretreatment with gadolinium inhibited the activation of macrophages and the induction of iNOS in intestinal resident macrophages, and restored the number of KIT-positive cells and intestinal contractions. These results suggested that NO produced from intestinal macrophages via iNOS induced by LPS, may be involved in the ICCs injury and intestinal dysmotility under septic conditions.

Viruses, Other Pathogenic Microorganisms and Esophageal Cancer

BACKGROUND

Esophageal cancer (EC) is the eighth most prevalent malignant tumor and the sixth leading cause of cancer mortality throughout the world. Despite the technical developments in diagnosis and treatment, the 5-year survival rate is still low. The etiology of EC remains poorly understood; multiple risk factors may be involved and account for the great variation in EC incidence in different geographic regions.

SUMMARY

Infection with carcinogenetic pathogens has been proposed as a risk factor for EC. This review explores the recent studies on the association of human papillomavirus (HPV), Epstein-Barr virus (EBV), Helicobacter pylori and esophageal bacterial biota with EC.

KEY MESSAGE

Among the above-mentioned pathogens, HPV most likely contributes to esophageal squamous cell carcinoma (ESCC) in high-risk populations. New techniques are being applied to studies on the role of infection in EC, which will inevitably bring novel ideas to the field in the near future.

PRACTICAL IMPLICATIONS

Multiple meta-analyses support the finding of a higher HPV detection rate in regions associated with high risk for ESCC compared to low-risk areas. A potential role of HPV in the rise of esophageal adenocarcinoma (EAC) was proposed recently. However, further studies are required before a firm conclusion can be drawn. Less work has been done in studying the association between EBV and ESCC, and the results are quite controversial. H. pylori infection is found to be inversely related to EC, which is probably due to the reduced incidence of gastroesophageal reflux disease. Analysis of the esophageal bacterial biota revealed distinct clusters of bacteria in normal and diseased esophagi. A type II microbiome rich in Gram-negative bacteria potentially contributes to EAC by inducing chronic inflammation. Novel findings from such studies as these may benefit public health by justifying anti-infection measures to prevent EC.

Lower esophageal microbiota species are affected by the eradication of Helicobacter pylori infection using antibiotics

The aim of this study was to investigate the effect of Helicobacter pylori (H. pylori) infection on the lower esophageal microbiota and the eradication of H. pylori through the use of antibiotics. Forty-five BALB/C mice were randomly divided into negative control, infection and treatment groups. The mice were sacrificed and DNA was extracted from the lower esophageal microbiota. Polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) was performed to determine the composition of the microbiota. Quantity One^® 1-D Analysis Software was used for the analysis of the DGGE profiles. The different bands from the groups were amplified with 16S rDNA V6 region primers. DNA sequencing and Basic Local Alignment Search Tool analysis were performed for the identification of the bands. H. pylori colonization led to severe ulcers in the stomachs of the mice, and these ulcers were alleviated by antibiotic treatment. The infection group had an increased number of bacterial species in the stomach compared with the control and treatment groups. DGGE fingerprinting of the lower esophagus showed that there were significant differences in the number of bands (P<0.05), diversity index and abundance among the groups (P<0.05); however, no significant differences in homogeneity were observed (P>0.05). Although the composition of flora species in the lower espohagus varied, the dominant species, and their relative contents, were similar in the control, infection and treatment groups. The present study provided a microecological basis for the understanding of the pathogenesis of lower esophageal diseases, following the eradication of H. pylori infection with antibiotics.

Cancer and the microbiome: potential applications as new tumor biomarker

Microbial communities that colonize in humans are collectively described as microbiome. According to conservative estimates, about 15% of all types of neoplasms are related to different infective agents. However, current knowledge is not sufficient to explain how the microbiome contributes to the growth and development of cancers. Large and thorough studies involving colonized, diverse and complex microbiome entities are required to identify microbiome as a potential cancer marker and to understand how the immune system is involved in response to pathogens. This article reviews the existing evidence supporting the enigmatic association of transformed microbiome with the development of cancer through the immunological modification. Ascertaining the connection between microbiome and immunological responses with risk of cancer may direct to explaining significant advances in the etiology of cancer, potentially disclosing a novel paradigm of research for the management and prevention of cancer.

The impact of proton pump inhibitors on the human gastrointestinal microbiome

Potent gastric acid suppression using proton pump inhibitors (PPIs) is common in clinical practice but may have important effects on human health that are mediated through changes in the gastrointestinal microbiome. In the esophagus, PPIs change the normal bacterial milieu to decrease distal esophageal exposure to inflammatory gram-negative bacteria. In the stomach, PPIs alter the abundance and location of gastric Helicobacter pylori and other bacteria. In the small bowel, PPIs cause polymicrobial small bowel bacterial overgrowth and have been associated with the diagnosis of celiac disease. In the colon, PPIs associate with incident but not recurrent Clostridium difficile infection.

The role of obesity in oesophageal cancer development

The incidence of oesophageal adenocarcinoma has increased dramatically in the developed world in the last half century. Over approximately the same period there has been an increase in the prevalence of obesity. Multiple epidemiological studies and meta-analyses have confirmed that obesity, especially abdominal, visceral obesity, is a risk factor for gastro-oesophageal reflux, Barrett's oesophagus and oesophageal adenocarcinoma. Although visceral obesity enhances gastro-oesophageal reflux, the available data also show that visceral obesity increases the risk of Barrett's oesophagus and adenocarcinoma via reflux-independent mechanisms. Several possible mechanisms could link obesity with the risk of oesophageal adenocarcinoma in addition to mechanical effects increasing reflux. These include reduced gastric Helicobacter pylori infection, altered intestinal microbiome, factors related to lifestyle, the metabolic syndrome and associated low-grade inflammation induced by obesity and the secretion of mediators by adipocytes which may directly influence the oesophageal epithelium. Of these adipocyte-derived mediators, increased leptin levels have been independently associated with progression to oesophageal adenocarcinoma and in laboratory studies leptin enhances malignant behaviours in cell lines. Adiponectin is also secreted by adipocytes and levels decline with obesity: decreased serum adiponectin levels are associated with malignant progression in Barrett's oesophagus and experimentally adiponectin exerts anticancer effects in Barrett's cell lines and inhibits growth factor signalling. At present there are no proven chemopreventative interventions that may reduce the incidence of obesity-associated oesophageal cancer: observational studies suggest that the combined use of a statin and aspirin or another cyclo-oxygenase inhibitor is associated with a significantly reduced cancer incidence in patients with Barrett's oesophagus.

Microbiome, innate immunity, and esophageal adenocarcinoma

With the development of culture-independent technique, a complex microbiome has been established and described in the distal esophagus. The incidence of esophageal adenocarcinoma (EAC) has increased dramatically in the United States. Studies documenting an altered microbiome associated with EAC and its precedents suggest that dysbiosis may be contributing to carcinogenesis, potentially mediated by interactions with toll-like receptors. Investigations attempting to associate viruses with EAC have not been as consistent. Currently available data are cross-sectional and therefore cannot prove causal relationships. Prospectively, microbiome studies open a new avenue to the understanding of the etiology and pathogenesis of reflux disorders and EAC.

Infection and esophageal cancer

The following, from the 12th OESO World Conference: Cancers of the Esophagus, includes commentaries on infection and cancer, and includes commentaries on the influence of bacterial infections on mucin expression and cancer risk; the role of esophageal bacterial biota in the incidence of esophageal disease; the association between human papilloma virus (HPV) and esophageal squamous cell carcinoma; the role of HPV in esophageal adenocarcinoma; the role of Helicobacter pylori in cardiac carcinoma; and the role of Epstein-Barr virus infection in esophageal cancer.

Gastrointestinal malignancy and the microbiome

Microbial species participate in the genesis of a substantial number of malignancies-in conservative estimates, at least 15% of all cancer cases are attributable to infectious agents. Little is known about the contribution of the gastrointestinal microbiome to the development of malignancies. Resident microbes can promote carcinogenesis by inducing inflammation, increasing cell proliferation, altering stem cell dynamics, and producing metabolites such as butyrate, which affect DNA integrity and immune regulation. Studies in human beings and rodent models of cancer have identified effector species and relationships among members of the microbial community in the stomach and colon that increase the risk for malignancy. Strategies to manipulate the microbiome, or the immune response to such bacteria, could be developed to prevent or treat certain gastrointestinal cancers.

Review article: bacteria and pathogenesis of disease in the upper gastrointestinal tract--beyond the era of Helicobacter pylori

BACKGROUND

Study of the upper gastrointestinal microbiome has shown that other bacteria besides Helicobacter pylori flourish despite the hostile environment. Whilst H. pylori is the most studied bacteria in this region with a defined role in inflammation and neoplasia, it is apparent that other bacteria may contribute to UGI disease.

AIM

To review current knowledge of bacteria inhabiting the oesophagus, stomach and duodenum.

METHODS

Published studies on the upper gastrointestinal microbiome (extracted from PubMed during the last 20 years).

RESULTS

The stomach is a hostile environment for bacteria; however, recent studies categorising the microbiota have shown surprising results. Helicobacter pylori has been intensively studied since 1984 and recent sequencing analysis of other gastric microbiota shows that H. pylori is not alone. Composition can be influenced by acid suppression, gastritis and abundance of H. pylori. Eradication of H. pylori, whilst decreasing gastric cancer is associated with an increase in asthma, reflux and obesity. A future approach may be to selectively eradicate bacteria which predispose to inflammation and cancer as opposed to a comprehensive knockout policy. In the oesophagus, viridans streptococci are the most common bacteria influenced by both oral and gastric bacteria. Oesophagitis and Barrett's oesophagus are characterised by a significant decrease in Gram-positive bacteria and an increase in Gram-negative bacteria. An inverse association of H. pylori and oesophageal adenocarcinoma is described. The duodenal microbiome has been shown to influence small intestinal bacterial overgrowth, irritable bowel syndrome and coeliac disease. The numbers of bacteria recoverable by culture are variable in the stomach mucosa and gastric juice, typically 10(2) -10(4) colony-forming units (CFU)/g or mL and in the oesophagus, up to 10(4) bacteria per mm(2) mucosal surface. In the small bowel, in health, 10(3) CFU/mL are normal.

CONCLUSION

This review highlights current knowledge of upper gastrointestinal bacteria and associations with disease.

Molecular pathways: pathogenesis and clinical implications of microbiome alteration in esophagitis and Barrett esophagus

Esophageal adenocarcinoma is preceded by the development of reflux-related intestinal metaplasia or Barrett esophagus, which is a response to inflammation of the esophageal squamous mucosa, reflux esophagitis. Gastroesophageal reflux impairs the mucosal barrier in the distal esophagus, allowing chronic exposure of the squamous epithelium to the diverse microbial ecosystem or microbiome and inducing chronic inflammation. The esophageal microbiome is altered in both esophagitis and Barrett esophagus, characterized by a significant decrease in gram-positive bacteria and an increase in gram-negative bacteria in esophagitis and Barrett esophagus. Lipopolysaccharides (LPS), a major structure of the outer membrane in gram-negative bacteria, can upregulate gene expression of proinflammatory cytokines via activation of the Toll-like receptor 4 and NF-κB pathway. The potential impact of LPS on reflux esophagitis may be through relaxation of the lower esophageal sphincter via inducible nitric oxide synthase and by delaying gastric emptying via cyclooxygenase-2. Chronic inflammation may play a critical role in the progression from benign to malignant esophageal disease. Therefore, analysis of the pathways leading to chronic inflammation in the esophagus may help to identify biomarkers in patients with Barrett esophagus for neoplastic progression and provide insight into molecular events suitable for therapeutic intervention in prevention of esophageal adenocarcinoma development in patients with reflux esophagitis and Barrett esophagus.

Chronic alcohol consumption induces an overproduction of NO by nNOS- and iNOS-expressing myenteric neurons in the murine small intestine

BACKGROUND

There are indications that alterations in the nitric oxide (NO) system of relaxation mediate gastrointestinal motor disturbances induced by chronic alcohol consumption (CAC). As CAC is known to inhibit the motility of the mouse small intestine, we investigated in this model if CAC affects basal NO synthesis by myenteric neurons and which NOS isoforms are involved.

METHODS

The instantaneous NO synthesis of individual neurons was optically measured in whole-mount preparations loaded with the NO synthesis indicator DAF-FM, and the expression of nNOS, iNOS and eNOS was determined by immunohistochemistry.

KEY RESULTS

The DAF-FM recordings showed that CAC induced an increase in neuronal NO synthesis (absolute fluorescence: control 34±12; CAC 140±56; mean±SD; P<0.0004). Neurons of control mice expressed the nNOS (29±3% of total) and iNOS (28±1%) isoforms. eNOS expression was observed in <0.5% of the neurons. Chronic alcohol consumption caused an increase in the proportion of iNOS-expressing neurons (to 33±5%; P<0.01) and a decrease in nNOS-expressing neurons (to 22±3%; P<0.0001), without altering the proportion of NO-producing neurons (control 55±13%; CAC 56± 11%; P=0.82).

CONCLUSIONS & INFERENCES

Chronic alcohol consumption induces a marked increase in NO synthesis by jejunal myenteric neurons, accompanied by an up-regulation of iNOS-expressing neurons and a downregulation of nNOS neurons. We conclude that the overproduction of NO may be a direct cause of gastrointestinal motility disturbances.

Chronic alcohol consumption affects gastrointestinal motility and reduces the proportion of neuronal NOS-immunoreactive myenteric neurons in the murine jejunum

Alcohol consumption interferes with gastrointestinal transit causing symptoms in alcoholic patients. Nitric oxide (NO), synthesized by neuronal nitric oxide synthase (nNOS) plays an important role in the control of gastrointestinal motility. Our aim was to investigate whether chronic alcohol intake in a murine model induces gastrointestinal motility disturbances and affects the nitrergic myenteric neurons in the stomach and jejunum. Gastric emptying, small intestinal transit and geometric centre were measured in vivo after intragastric gavage of Evans blue. Nitrergic relaxations to electrical field stimulation (EFS) and exogenous NO were recorded in jejunal muscle strips in vitro. The proportion of nNOS-immunopositive myenteric neurons was assessed using PGP9.5 and nNOS immunostaining. After chronic alcohol consumption, gastric emptying and small intestinal transit were delayed compared with control mice, and the nitrergic nerve-mediated relaxations to EFS in the jejunum were decreased, whereas relaxations to exogenous NO did not differ. The proportion of nNOS-immunoreactive neurons did not change in the stomach, whereas in the jejunum the percentage decreased from 33% to 27% (P < 0.001) after chronic alcohol intake. The total number of myenteric neurons remained unchanged. These results suggest that chronic alcohol consumption disturbs gastric and small intestinal motility in vivo and in vitro and is associated with a decrease in the proportion of nNOS-immunoreactive myenteric neurons in the murine jejunum.

Endothelin A receptors mediate relaxation of guinea pig internal anal sphincter through cGMP pathway

BACKGROUND

Endothelin (ET) modulates motility of the internal anal sphincter through unclear receptor subtypes.

METHODS

We measured relaxation of guinea pig internal anal sphincter strips caused by ET-related peptides and binding of (125)I-ET-1 to cell membranes prepared from the internal anal sphincter muscle. Visualization of (125)I-ET-1 binding sites in tissue was performed by autoradiography.

KEY RESULTS

In the guinea pig internal anal sphincter, ET-1 caused a marked relaxation insensitive to tetrodotoxin, atropine, or omega-conotoxin GVIA. ET-2 was as potent as ET-1. ET-3 caused a mild relaxation. The relative potencies for ETs to cause relaxation were ET-1 = ET-2 > ET-3. The ET-1-induced relaxation was inhibited by BQ-123, an ET(A) antagonist, but not by BQ-788, an ET(B) antagonist. These indicate that ET(A) receptors mediate the relaxation. The relaxant response of ET-1 was attenuated by LY 83583, KT 5823, Rp-8CPT-cGMPS, tetraethyl ammonium, 4-aminopyridine and N(omega)-nitro-L-arginine, but not significantly affected by N(G)-nitro-L-arginine methyl ester, N(G)-methyl-L-arginine, charybdotoxin, apamin, KT 5720, and Rp-cAMPS. These suggest the involvement of cyclic guanosine 3',5'-cyclic monophosphate (cGMP), and potassium channels. Autoradiography localized (125)I-ET-1 binding to the internal anal sphincter. Binding of (125)I-ET-1 to the cell membranes prepared from the internal anal sphincter revealed the presence of two subtypes of ET receptors, ET(A) and ET(B) receptors.

CONCLUSIONS & INFERENCES

Taken together, these results demonstrate that ET(A) receptors mediate relaxation of guinea pig internal anal sphincter through the cGMP pathway.

Ethanol upregulates iNOS expression in colon through activation of nuclear factor-kappa B in rats

BACKGROUND

Alcohol inhibits colonic motility but the mechanism is unknown. The goal of this study was to test the possibility that nuclear factor-kappa B (NF-kappaB) is involved in the upregulation of inducible nitric oxide synthase (iNOS) expression induced by ethanol in colon.

METHODS

The isometric contraction of longitudinal muscle strips of proximal colon (LP) was monitored by polygraph. Western blot analysis was used to measure the amount of iNOS and I-kappaB in the cytoplasm and P65 in the nucleus. Immunohistochemistry was applied to locate iNOS in colon.

RESULTS

Ethanol (87mM) inhibited the contraction of LP. Pretreatment of S-methylisothioure (SMT) (1 mM), a specific iNOS inhibitor, Pyrrolidine dithiocarbamate (PDTC) (10 mM) and BAY11-7082(10 mM), specific inhibitors of NF-kappaB significantly reversed the inhibitory effect of ethanol on LP contraction. Ethanol increased the amount of iNOS and content of NO in colon, and these effects were attenuated by pretreatment of PDTC. Following ethanol administration, the amount of I-kappaB in the cytoplasm decreased, but that of P65, the subunit of NF-kappaB in the nucleus, increased. The iNOS was located in the cell body of myenteric plexus in colon.

CONCLUSION

Ethanol inhibited the contraction of LP in colon mainly through activation of NF-kappaB, the subsequent upregulation of iNOS expression and increase of NO release in myenteric plexus.

Gastroesophageal reflux in mechanically ventilated pediatric patients and its relation to ventilator-associated pneumonia

INTRODUCTION

The objective was to determine the frequency of gastroesophageal reflux (GER) in mechanically ventilated pediatric patients and its role as a risk factor for ventilator-associated pneumonia (VAP), which may be enhanced among those patients.

METHODS

The study is a prospective cohort study of mechanically ventilated pediatric patients in the pediatric intensive care unit (PICU) of Ain Shams University Children's Hospital. It was conducted in 24 mechanically ventilated patients (16 of them developed VAP and 8 did not, with mean age of 16.6 +/- 20.5 and 18.6 +/- 22.4 months respectively). Esophageal 24-hour pH-metry beside clinical and laboratory evaluation of their underlying problem and severity of their condition were carried out.

RESULTS

All VAP patients had GER (50% alkaline reflux, 12.5% acidic reflux and 37.5% combined reflux) compared to 75% of non-VAP ones (100% alkaline reflux). The mean total reflux time was significantly longer among VAP (50 minutes) versus non-VAP (3 minutes) patients. There was significant increase in acidic reflux parameters among non-survivors versus survivors (P < 0.001). For VAP mortality, total acidic reflux at a cut-off value of 28.6 minutes is found to be a mortality predictor with a sensitivity of 100% and a specificity of 100%.

CONCLUSIONS

GER is a constant incident in mechanically ventilated pediatric patients, with alkaline reflux being more common than acidic reflux. Both acidic and alkaline refluxes were found to be associated with the development of VAP and total reflux time was found to be a reliable predictor of VAP. Moreover, acidic reflux was found to be more related to mortality than alkaline reflux.

Inflammation and intestinal metaplasia of the distal esophagus are associated with alterations in the microbiome

BACKGROUND & AIMS

Gastroesophageal reflux causes inflammation and intestinal metaplasia and its downstream sequelum adenocarcinoma in the distal esophagus. The incidence of esophageal adenocarcinoma has increased approximately 6-fold in the United States since the 1970s, accompanied with a significant increase in the prevalence of gastroesophageal reflux disease (GERD). Despite extensive epidemiologic study, the cause for GERD and the unexpected increases remain unexplainable. Microbes are among the environmental factors that may contribute to the etiology of GERD, but very little research has been done on the esophageal microbiome, particularly in its relation to GERD. This is the first comprehensive reported correlation between a change in the esophageal microbiome and esophageal diseases.

METHODS

Biopsy samples of the distal esophagus were collected from 34 patients. Host phenotypes were histologically defined as normal, esophagitis, or Barrett's esophagus (intestinal metaplasia). Microbiomes from the biopsy samples were analyzed by bacterial 16S ribosomal RNA gene survey and classified into types using unsupervised cluster analysis and phenotype-guided analyses. Independence between host phenotypes and microbiome types were analyzed by Fisher exact test.

RESULTS

Esophageal microbiomes can be classified into 2 types. The type I microbiome was dominated by the genus Streptococcus and concentrated in the phenotypically normal esophagus. Conversely, the type II microbiome contained a greater proportion of gram-negative anaerobes/microaerophiles and primarily correlated with esophagitis (odds ratio, 15.4) and Barrett's esophagus (odds ratio, 16.5).

CONCLUSIONS

In the human distal esophagus, inflammation and intestinal metaplasia are associated with global alteration of the microbiome. These findings raise the issue of a possible role for dysbiosis in the pathogenesis of reflux-related disorders.

The alpha2-adrenergic receptor antagonist yohimbine improves endotoxin-induced inhibition of gastrointestinal motility in mice

BACKGROUND

Sepsis inhibits gastrointestinal motility. Although the exact mechanism of this is unclear, lipopolysaccharide is known to activate macrophages in the gastrointestinal wall, which upregulate their expression of inducible nitric oxide synthase (iNOS). This leads to an increased production of nitric oxide, which relaxes the gastrointestinal muscles. We studied endotoxaemic mice to determine whether yohimbine improved delayed gastric emptying and gastrointestinal transit.

METHODS

Male Balb/c mice (n = 49) were randomly allocated to two groups, and either yohimbine 25 microg or saline was injected s.c. Four hours later, mice in each group were further randomly allocated to two groups, and either lipopolysaccharide 100 microg or saline was injected intraperitoneally. Eight hours later, liquid containing fluorescent microbeads was infused into the stomach, and 30 min later, gastric emptying and gastrointestinal transit were measured using flow cytometry. We also studied whether yohimbine given after injection of lipopolysaccharide was effective (n = 22). In another group of mice (n = 32), iNOS in the gastrointestinal tract was measured using western blotting.

RESULTS

Lipopolysaccharide significantly inhibited gastric emptying and gastrointestinal transit. Yohimbine, given before or after lipopolysaccharide, significantly attenuated the inhibitory effects of lipopolysaccharide. Lipopolysaccharide increased the expression of iNOS in the small intestine and yohimbine suppressed the effects of lipopolysaccharide.

CONCLUSIONS

In endotoxaemic mice, yohimbine improved delayed gastric emptying and gastrointestinal transit, possibly by downregulating lipopolysaccharide-induced increased expression of iNOS.

[The effect of bacterial lipopolysaccharide on the gastric emptying of rats: a pretreatment evaluation using Nw-nitro-L-arginine methyl ester (L-NAME)]

BACKGROUND

There is evidence that nitric oxide plays a role in the decrease in gastric emptying induced by bacterial lipopolysaccharide.

AIM

To evaluate the effect of pretreatment with Nw-nitro-L-arginine methyl to ester, one competitive inhibitor of the nitric oxide synthases, on the gastric emptying delay induced by lipopolysaccharide.

MATERIAL AND METHODS

Male Wistar rats, SPF, were used after 24 h fast and 1 h-water withdrawn. The pretreatment was done intravenously with vehicle (saline) or N(w)-nitro-L-arginine methyl to ester in the doses of 0.5, 1, 2.5 e 5 mg/kg. After 10 min, the animals were treated iv with lipopolysaccharide (50 microg/kg) or received vehicle (saline). The gastric emptying was evaluated 1 h after the lipopolysaccharide administration. A saline solution containing phenol red was used as the test meal. The gastric emptying was indirectly assessed by the determination of percent gastric retention of the test meal 10 min after orogastric administration.

RESULTS

The animals pretreated with vehicle and treatment with lipopolysaccharide have significant rise of the gastric retention (average = 57%) in comparison with the controls receiving only vehicle (38.1%). The pretreatment with the different doses of N(w)-nitro-L-arginine methyl to ester did not modify per se the gastric retention in comparison with the animals pretreated with vehicle. Pretreatment with N(w)-nitro-L-arginine methyl to ester with the dose of 1 mg/kg determined a discrete but significant reduction in the gastric retention (52%) of animals treated with lipopolysaccharide in comparison with vehicle-pretreated rats. Paradoxically, animals pretreated with 2.5 or 5 mg of N(w)-nitro-L-arginine methyl to ester/kg followed by treatment with lipopolysaccharide displayed a significantly higher gastric retention (74.7% and 80.5%, respectively) as compared to their controls, pretreated with the same doses of the inhibitor and treated with vehicle (40.5% and 38.7%, respectively) and to those pretreated with vehicle and treated with the same toxin.

CONCLUSION

The pretreatment with N(w)-nitro-L-arginine methyl to ester at low dose (1 mg/kg) resulted in a discrete inhibition of the gastric emptying delay induced by lipopolysaccharide. Nevertheless, N(w)-nitro-L-arginine methyl to ester at higher doses (2.5 and 5 mg/kg) induced an enhancement of the lipopolysaccharide effect on gastric emptying, despite not interfering with the gastric emptying per se.

Interactions between commensal bacteria and gut sensorimotor function in health and disease

Commensal bacteria inhabiting the human intestine (i.e., intestinal microflora) participate in the development and maintenance of gut sensory and motor functions, including the promotion of intestinal propulsive activity. On the other hand, intestinal motility represents one of the major control systems of gut microflora, through the sweeping of excessive bacteria from the lumen. There is emerging evidence indicating that changes in this bidirectional interplay contribute to the pathogenesis of gut diseases, such as small intestinal bacterial overgrowth and intestinal pseudo-obstruction. Recent interest has also been directed to the potential role of intestinal microflora in the pathogenesis of the irritable bowel syndrome. Although the status of intestinal microflora in the irritable bowel syndrome remains unsettled, small intestinal bacterial overgrowth (as detected with breath testing) and increased fermentation of foods with gas production, provide indirect evidence that microflora may contribute to symptom generation in irritable bowel syndrome. The potential benefit of antibiotic and probiotic therapy is currently under investigation and opens new perspectives in irritable bowel syndrome treatment.

Effects and mechanism of changes of local neurotransmitters in rats' pylorus and bile reflux to the stomach with stress ulcer

Stress ulcer occurs primarily in severe conditions, with a high incidence and mortality in intensive care units. However, studies on the association between stress ulcer and bile reflux to the stomach with stress ulcer are still inconclusive. Therefore, our research aimed to determine whether or not bile reflux exists during stress ulcer and then to investigate the effects and mechanism of changes of pyloric local neurotransmitters on bile reflux in such circumstances so as to provide a new pathway for clinical intervention. Cold water immersion was used to copy the stress ulcer model of rats. Sixty-five adult Sprague-Dawley rats of either sex were randomly divided into three groups: the normal control group (n = 10), the stress group (n = 30), and the antagonist group (n = 25). The gastric ulcer index, pH, and bile acid of gastric juice were measured before and after stress. Radio Immunoassay Detection Kit and Biochemic Detection Kit were used to measure local contents of CGRP (calcitonin gene-related peptide) and nitric oxide, respectively, in rats' pylorus. The local contents of nitric oxide in rats' pylorus reached a maximum at 1 hr after stress. The bile acid and pH of gastric juice peaked at 2 hr after stress and the ulcer index peaked at 4 hr after stress. But the local contents of CGRP in rats' pylorus decreased to the minimum at 4 hr after stress. The bile acid and ulcer index in the L-NAME group were significantly lower than in the antagonist control group. However, the bile acid in the hCGRP8-37 group was less than in the antagonist control group. Compared with hCGRP8-37 group, there was a significant reduction in bile acid in the L-NAME group. There was a significant reduction in the ulcer index of the hCGRP8-37 group compared with the L-NAME group and the antagonist control group. There was a certain kind of positive correlation between nitric oxide in rats' pylorus and bile acid to the stomach, for nitric oxide could loosen the pyloric sphincter and increase the bile acid to the stomach. L-NAME might reduce the local nitric oxide contents in rats' pylorus so that bile acid to the stomach might be decreased, obviously with a looser tight pyloric sphincter. Meanwhile, the CGRP in rats' pylorus was negatively associated with the ulcer index, hence CGRP might protect gastric mucosa under stress conditions.

Effects of acupuncturing Tsusanli (ST36) on expression of nitric oxide synthase in hypothalamus and adrenal gland in rats with cold stress ulcer

AIM: To study the protective effect of acupuncturing Tsusanli (S_T36) on cold stress ulcer, and the expression of nitric oxide synthase (NOS) in hypothalamus and adrenal gland.

METHODS: Ulcer index in rats and RT-PCR were used to study the protective effect of acupuncture on cold stress ulcer, and the expression of NOS in hypothalamus and adrenal gland. Images were analyzed with semi-quantitative method.

RESULTS: The ulcer index significantly decreased in rats with stress ulcer. Plasma cortisol concentration was up regulated during cold stress, which could be depressed by pre-acupuncture. The expression of NOS1 in hypothalamus increased after acupuncture. The increased expression of NOS2 was related with stress ulcer, which could be decreased by acupuncture. The expression of NOS3 in hypothalamus was similar to NOS2, but the effect of acupuncture was limited. The expression of NOS2 and NOS3 in adrenal gland increased after cold stress, only the expression of NOS1 could be repressed with acupuncture. There was no NOS2 expression in adrenal gland in rats with stress ulcer.

CONCLUSION: The protective effect of acupuncturing Tsusanli (S_T36) on the expression of NOS in hypothalamus and adrenal gland can be achieved.

Effect of lipopolysaccharide on diarrhea and gastrointestinal transit in mice: Roles of nitric oxide and prostaglandin E2

AIM: To investigate the effect of lipopolysaccharide (LPS) on the diarrheogenic activity, gastrointestinal transit (GIT), and intestinal fluid content and the possible role of nitric oxide (NO) and prostaglandin E₂ (PGE₂) in gastrointestinal functions of endotoxin-treated mice.

METHODS: Diarrheogic activity, GIT, and intestinal fluid content as well as nitric oxide and PGE₂ products were measured after intraperitoneal administration of LPS in mice.

RESULTS: LPS dose-dependently accumulated abundant fluid into the small intestine, induced diarrhea, but decreased the GIT. Both nitric oxide and PGE₂ were found to increase in LPS-treated mice. Western blot analysis indicated that LPS significantly induced the protein expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 in mice intestines. Pretreatment with N^G-nitro-L-arginine-methyl ester (L-NAME, a non-selective NOS inhibitor) or indomethacin (an inhibitor of prostaglandin synthesis) significantly attenuated the effects of LPS on the diarrheogenic activity and intestine content, but reversed the GIT.

CONCLUSION: The present study suggests that the pathogenesis of LPS treatment may mediate the stimulatory effect of LPS on nitric oxide and PGE2 production and NO/prostaglandin pathway may play an important role on gastrointestinal function.

Mechanism of internal anal sphincter relaxation by CORM-1, authentic CO, and NANC nerve stimulation

The present studies compared the effects of CO-releasing molecule (CORM-1), authentic CO, and nonadrenergic noncholinergic (NANC) nerve stimulation in the internal anal sphincter (IAS). Functional in vitro experiments and Western blot studies were conducted in rat IAS smooth muscle. We examined the effects of CORM-1 (50-600 microM) and authentic CO (5-100 microM) and NANC nerve stimulation by electrical field stimulation (EFS; 0.5-20 Hz, 0.5-ms pulse, 12 V, 4-s train). The experiments were repeated after preincubation of the tissues with the neurotoxin TTX, the guanylate cyclase inhibitor 1H-(1,2,4)oxadiazolo-(4,3-a)quinoxalin-1-one (ODQ), the selective heme oxygenase (HO) inhibitor tin protoporphyrin IX (SnPP-IX), the nitric oxide synthase inhibitor N(omega)-nitro-L-arginine (L-NNA), and SnPP-IX + L-NNA. We also investigated the effects of the HO substrate hematin (100 microM). CORM-1, as well as CO, produced concentration-dependent IAS relaxation, whereas hematin had no effect. TTX abolished and L-NNA significantly blocked IAS relaxation by EFS without any effect on CORM-1 and CO. ODQ blocked IAS relaxation by CORM-1, authentic CO, and EFS. SnPP-IX had no significant effect on IAS relaxation by CORM-1, CO, or EFS. The presence of neuronal nitric oxide synthase, HO-1, and HO-2 in IAS smooth muscle was confirmed by Western blot studies. CORM-1 and CO, as well as NANC nerve stimulation, produced IAS relaxation via guanylate cyclase/cGMP-dependent protein kinase activation. The advent of CORM-1 with potent effects in the IAS has significant implications in anorectal motility disorders with regard to pathophysiology and therapeutic potentials.

[The effect of bacterial lipopolysaccharide on the gastric emptying of rats: a pretreatment evaluation using dexamethasone and methylene blue]

BACKGROUND

The nitric oxide might be a putative mediator of the decrease in gastric emptying induced by bacterial lipopolysaccharide in rats.

AIM

For that, we evaluated the effect of the pretreatment intravenous with dexamethasone and methylene blue in the retardation process of gastric emptying induced by intravenous application of lipopolysaccharide in rats. Dexamethasone has been shown to inhibit the induction of NOS II (induced NO-synthase) while the methylene blue, that blocks the soluble guanylyl cyclase, inhibits nitric oxide synthases and, in addition, inactivates nitric oxide directly.

MATERIAL AND METHODS

Male Wistar rats, specific patogenic free, were used after a 24 hour fast and 1 hour-water withdrawn. The pretreatment was performed using dexamethasone solutions (3 and 6 mg/kg), methylene blue (2 mg/kg) or sterile vehicle. The treatment consisted in the application of lipopolysaccharide (50 mug/kg) or vehicle. The time period between the pretreatment and treatment was 10 minutes, excluding the study with dexamethasone 6 mg/kg that was 1 hour. The gastric emptying was evaluated 1 hour after the lipopolysaccharide application, except for two studies with dexamethasone 3 mg/kg in which the time periods were 2 and 8 hours. A saline solution containing phenol red was used as the test meal. The gastric emptying was determined by measuring gastric retention 10 minutes after the orogastric infusion of the test meal.

RESULTS

The pretreatment with dexamethasone or methylene blue and treatment with vehicle did not have effect in the gastric emptying comparing to the control group. We found that pretreatment with dexamethasone in the studies for 1 hour and 2 hours did not interfere in the retardation of the gastric emptying produced by endotoxin. Nevertheless, in the eighth period study with this drug there was a significant reduction of gastric retention in the endotoxin-treated animals in relation to the unpretreated ones. Meanwhile, the pretreatment with the methylene blue completely blocked the action of endotoxin on the gastric emptying in rats.

CONCLUSION

These results suggest a possible involvement of nitric oxide on the effect of lipopolysaccharide in rat gastric emptying.

Downregulation of nNOS and synthesis of PGs associated with endotoxin-induced delay in gastric emptying

A single intraperitoneal injection of endotoxin (40 microg/kg) significantly delayed gastric emptying of a solid nutrient meal. Blockade of nitric oxide synthase (NOS) with 30 mg/kg ip N(G)-nitro-L-arginine methyl ester or 20 mg/kg ip 7-nitroindazole [neuronal NOS (nNOS) inhibitor] significantly delayed gastric emptying in control animals but failed to modify gastric emptying in endotoxin-treated rats. Administration of 2.5, 5, and 10 mg/kg ip N(6)-iminoethyl-L-lysine [inducible NOS (iNOS) inhibitor] had no effect in either experimental group. Indomethacin (5 mg/kg sc), NS-398 (cyclooxygenase-2 inhibitor; 10 mg/kg ip), and dexamethasone (10 mg/kg sc) but not quinacrine (20 mg/kg ip) significantly prevented delay in gastric emptying induced by endotoxin but failed to modify gastric emptying in vehicle-treated animals. Ca(2+)-dependent NOS activity in the antrum pylorus of the stomach was diminished by endotoxin, whereas Ca(2+)-independent NOS activity was not changed. In addition, decreased nNOS mRNA and protein were observed in the antrum pylorus of endotoxin-treated rats. Our results suggest that downregulation of nNOS in the antrum pylorus of the stomach and synthesis of prostaglandins mediate the delay in gastric emptying of a solid nutrient meal induced by endotoxin.

Animal model for angiotensin II effects in the internal anal sphincter smooth muscle: mechanism of action

Effect of ANG II was investigated in in vitro smooth muscle strips and in isolated smooth muscle cells (SMC). Among different species, rat internal and sphincter (IAS) smooth muscle showed significant and reproducible contraction that remained unmodified by different neurohumoral inhibitors. The AT(1) antagonist losartan but not AT(2) antagonist PD-123319 antagonized ANG II-induced contraction of the IAS smooth muscle and SMC. ANG II-induced contraction of rat IAS smooth muscle and SMC was attenuated by tyrosine kinase inhibitors genistein and tyrphostin, protein kinase C (PKC) inhibitor H-7, Ca(2+) channel blocker nicardipine, Rho kinase inhibitor Y-27632 or p(44/42) mitogen-activating protein kinase (MAPK(44/42)) inhibitor PD-98059. Combinations of nicardipine and H-7, Y-27632, and PD-98059 caused further attenuation of the ANG II effects. Western blot analyses revealed the presence of both AT(1) and AT(2) receptors. We conclude that ANG II causes contraction of rat IAS smooth muscle by the activation of AT(1) receptors at the SMC and involves multiple intracellular pathways, influx of Ca(2+), and activation of PKC, Rho kinase, and MAPK(44/42).

Biphasic alterations in gastrointestinal transit following endotoxaemia in mice

Lipopolysaccharide (LPS)-induced alterations of gastrointestinal transit were studied in mice using activated charcoal. LPS (10 mg kg-1) induced biphasic alterations of intestinal transit. Increase (acceleration phase) and delay (lag phase) in gastrointestinal transit were observed at 90 and 480 min after LPS injection, respectively. LPS administration induced significant increases in tumour necrosis factor (TNF)-alpha, interleukin (IL)-1beta and nitrate levels in blood serum with maximal levels observed at 1.5, 4, and 8 h after LPS administration, respectively. The effects of recombinant human lzactoferrin (rhLF) on LPS- induced alteration of gastrointestinal transit, and production of TNF-alpha, IL-1beta and nitrate were also studied. Animals were pretreated with rhLF 24 hours before intraperitoneal administration of LPS. RhLF significantly increased gastrointestinal transit during the lag phase. In addition, rhLF decreased the level of TNF-alpha in endotoxaemic animals. The levels of IL-1beta and nitrate were not significantly changed by rhLF. In conclusion, the effect of LPS on gastrointestinal transit is biphasic and the mechanism controlling the second phase most likely depends on TNF-alpha production, while the first phase most likely does not depend on TNF-alpha. On the other hand, it may be regulated by IL-1beta and nitric oxide production.