Gyula Mózsik

Gastric mucosal integrity: gastric mucosal blood flow and microcirculation. An overview

The stomach is in a state of continuous exposure to potentially hazardous agents. Hydrochloric acid together with pepsin constitutes a major and serious threat to the gastric mucosa. Reflux of alkaline duodenal contents containing bile and pancreatic enzymes are additional important injurious factors of endogenous origin. Alcohol, cigarette smoking, drugs and particularly aspirin and aspirin-like drugs, and steroids are among exogenous mucosal irritants that can inflict mucosal injury. The ability of the stomach to defend itself against these noxious agents has been ascribed to a number of factors constituting the gastric mucosal defense. These include mucus and bicarbonate secreted by surface epithelial cells, prostaglandins, sulfhydryl compounds and gastric mucosal blood flow. The latter is considered by several researchers to be of paramount importance in maintaining gastric mucosal integrity. The aim of this paper is to review the experimental and clinical data dealing with the role of mucosal blood flow and in particular the microcirculation in both damage and protection of the gastric mucosa.

Decrease in CD3-negative-CD8dim+ and Vδ2/Vγ9 TcR + peripheral blood lymphocyte counts, low perforin expression and the impairment of natural killer cell activity is associated with chronic hepatitis C virus infection

BACKGROUND/AIMS As chronic hepatitis C virus (HCV) infection is associated with impaired natural killer (NK) cell cytotoxicity, we examined the phenotypes and perforin expression of peripheral blood lymphocytes, as well as the effect of interferon-alpha2b (IFN-alpha2b) therapy. METHODS Thirty-three patients had chronic hepatitis C, and of them 12 had been on IFN-alpha2b treatment. Eleven individuals had been treated earlier with IFN-alpha2b and completely cured, and eight were HCV carriers with persistently normal serum alanine aminotransferase. Three-colour flow cytometry was used to measure the percentage of CD3(+/-)CD8+, CD3+CD4+, gammadeltaTcR+, Vdelta2 TcR+, Vgamma9 TcR+, Vdelta1 TcR+, CD3-CD16+, CD3-CD56+, CD19+ and perforin-positive cells. NK cell activity was assessed by single cell cytotoxic and flow cytometric assay. RESULTS Patients with chronic hepatitis C showed an impaired NK cytotoxicity, decreased percentage of CD3-negative-CD8dim-positive (NK subtype) and Vgamma9/Vdelta2 TcR+ as well as perforin-positive T lymphocytes, compared to controls and to those who were cured from HCV infection. IFN-alpha2b increased NK cell cytotoxicity and the percentage of perforin-positive lymphocytes. CONCLUSIONS Our findings suggest that in chronic HCV infection a decreased percentage of CD3(-)CD8+, Vgamma9/Vdelta2 TcR+ and perforin-positive T cells and simultaneous decreased peripheral NK activity may contribute to the impaired cellular immune response and the chronicity of the disease.

Protective effect of lactulose on dextran sulfate sodium-induced colonic inflammation in rats

Promising results have recently been obtained with pre- and probiotic therapy in ulcerative colitis (UC). The prebiotic potential of lactulose is well established, but it has not yet been investigated in experimental colitis models. The purpose of the study was to examine the effect of lactulose on an UC model induced by 3% dextran sulfate sodium (DSS) solution added to drinking water for 7 days in male Wistar rats. Lactulose (300–1000 mg/kg) or 5-aminosalicylic acid (5-ASA; 150 mg/kg) was administered orally twice daily for 6 days. Colonic ulceration area, colon length, body weight changes, diarrhea/bloody feces, colonic mucosal myeloperoxidase activity (MPO), thiobarbituric acid reactive substances (TBARS), and histology were examined. Treatment of animals with DSS for 7 days resulted in severe colonic lesions accompanied by diarrhea, bloody feces, a decrese in body weight, shortening of the colon length, and an increase in MPO activity as well as TBARS, compared to normal rats. Lactulose treatment ameliorated DSS-induced colitis in a dose-dependent manner, and at 1000 mg/kg all of the parameters examined, except TBARS, were shown to improve significantly as compared to controls. Daily administration of 5-ASA also significantly reduced the severity of colonic lesions following DSS treatment. These results demonstrated the protectiv effect of lactulose in this rat colitis model and suggested that the background of this lactulose effect may be due to alterations of colonic microflora.

Immunohistochemical distribution of vanilloid receptor, calcitonin-gene related peptide and substance P in gastrointestinal mucosa of patients with different gastrointestinal disorders.

The immunohistochemical distribution of capsaicin/vanilloid (transient receptor potential vanilloid 1, TRPV1) receptors and neuropeptides (CGRP, SP) was studied in the gastrointestinal mucosal biopsies of patients with gastritis, erosions, ulcers, polyps, adenocarcinoma, chronic inflammatory bowel diseases, polyps without and with hyperplasia, dysplasia and adenocarcinoma in colon. The studies were carried out in 127 patients and 30 people with only functional dyspepsia (without any histological alteration). The results were: (1) the positivity of TRPV1 receptor and CGRP was detected, and weak participation of SP was detected in patients with different gastric diseases; (2) the presence of TRPV1, CGRP and SP could be detected in chronic inflammation of bowel disease; (3) SP could not detected in patients with colon polyps, dysplasia and adenocarcinoma; (4) the presence of TRPV1 and CGRP was proved in colon dysplasia and adenocarcinoma. We conclude that (1) the immunohistochemical distribution of TRPV1, CGRP and SP differs in gastrointestinal diseases of the upper and lower tract, and (2) the participation of TRPV1, CGRP and SP differs significantly in these different gastrointestinal diseases.

Capsaicin-sensitive afferent sensory nerves in modulating gastric mucosal defense against noxious agents

In the rat stomach, evidence has been provided that capsaicin-sensitive sensory nerves (CSSN) are involved in a local defense mechanism against gastric ulcer. In the present study capsaicin or resiniferatoxin (RTX), a more potent capsaicin analogue, was used to elucidate the role of these sensory nerves in gastric mucosal protection, mucosal permeability, gastric acid secretion and gastrointestinal blood flow in the rat. In the rat stomach and jejunum, intravenous RTX or topical capsaicin or RTX effected a pronounced and long-lasting enhancement of the microcirculation at these sites, measured by laser Doppler flowmetry technique. Introduction of capsaicin into the rat stomach in very low concentrations of ng-microg x mL(-1) range protected the gastric mucosa against damage produced by topical acidified aspirin, indomethacin, ethanol or 0.6 N HCl. Resiniferatoxin exhibited acute gastroprotective effect similar to that of capsaicin and exerted marked protective action on the exogenous HCl, or the secretagogue-induced enhancement of the indomethacin injury. The ulcer preventive effect of both agents was not prevented by atropine or cimetidine treatment. Capsaicin given into the stomach in higher desensitizing concentrations of 6.5 mM markedly enhanced the susceptibility of the gastric mucosa and invariably aggravated gastric mucosal damage evoked by later noxious challenge. Such high desensitizing concentrations of capsaicin, however, did not reduce the cytoprotective effect of prostacyclin (PGI2) or beta-carotene. Capsaicin or RTX had an additive protective effect to that of atropine or cimetidine. In rats pretreated with cysteamine to deplete tissue somatostatin, capsaicin protected against the indomethacin-induced mucosal injury. Gastric acid secretion of the pylorus-ligated rats was inhibited with capsaicin or RTX given in low non-desensitizing concentrations, with the inhibition being most marked in the first hour following pylorus-ligation. Low intragastric concentrations of RTX reduced gastric hydrogen ion back-diffusion evoked by topical acidified salicylates. It is concluded that the gastropotective effect of capsaicin-type agents involves primarily an enhancement of the microcirculation effected through local release of mediator peptides from the sensory nerve terminals. A reduction in gastric acidity may contribute to some degree in the gastric protective action of capsaicin-type agents. The vasodilator and gastroprotective effects of capsaicin-type agents do not depend on vagal efferents or sympathetic neurons, involve prostanoids, histaminergic or cholinergic pathways.

Helicobacter pylori. One bacterium and a broad spectrum of human disease! An overview

Since the historical rediscovery of gastric spiral Helicobacter pylori in the gastric mucosa of patients with chronic gastritis by Warren and Marshall in 1983, peptic ulcer disease has been largely viewed as being of infectious aetiology. Indeed, there is a strong association between the presence of H. pylori and chronic active gastritis in histology. The bacterium can be isolated in not less than 70% of gastric and in over 90% of duodenal ulcer patients. Eradication of the organism has been associated with histologic improvement of gastritis, lower relapse rate and less risk of bleeding from duodenal ulcer. The bacterium possesses several virulence factors enabling it to survive the strong acid milieu inside the stomach and possibly damaging host tissues. The sequence of events by which the bacterium might cause gastric or duodenal ulcer is still not fully elucidated and Kochs postulates have never been fulfilled. In the majority of individuals, H. pylori infection is largely or entirely asymptomatic and there is no convincing data to suggest an increase in the prevalence of peptic ulcer disease among these subjects. An increasingly growing body of literature suggests an association between colonization by H. pylori in the stomach and a risk for developing gastric mucosa-associated lymphoid tissue (MALT), MALT lymphoma, gastric adenocarcinoma and even pancreatic adenocarcinoma. The bacterium has been implicated also in a number of extra-gastrointestinal disorders such as ischaemic heart disease, ischaemic cerebrovascular disease, atherosclerosis, and skin diseases such as rosacea, but a causal role for the bacterium is missing. Eradication of H. pylori thus seems to be a beneficial impact on human health. Various drug regimens are in use to eradicate H. pylori involving the administration of three or four drugs including bismuth compounds, metronidazole, clarithromycin, tetracyclines, amoxycillin, ranitidine, omeprazole for 1-2 weeks. The financial burden, side effects and emergence of drug resistant strains due to an increase in the use in antibiotics for H. pylori eradication therapy need further reconsideration.

Capsaicin increases gastric emptying rate in healthy human subjects measured by 13C-labeled octanoic acid breath test

The role of capsaicin-sensitive primary afferent sensory nerves in the regulation of gastrointestinal motility in human is not clarified yet. In this study, we investigated the effect of 400 microg capsaicin given intragastrically on gastric emptying measured by 13C-octanoic acid breath test in ten healthy human subjects. Four parameters of gastric emptying curves were taken into consideration: 1) maximum value of the curve, 2) time belonging to this maximum, 3) slope of the rising part of the curve and 4) time belonging to the 50% of the area under the curve. Administration of 400 microg capsaicin significantly increased the slope of gastric emptying curve (from 0.1 +/- 0.01 to 0.139 +/- 0.014 U x min(-1), P < 0.05) and significantly decreased the time belonging to the maximum value of emptying curve (from 150 +/- 18 to 75 +/- 12 min, P < 0.05) and the time belonging to the 50% of the area under the curve (from 112 +/- 15 to 99 +/- 14 min, P < 0.05). According to our results 400 microg capsaicin enhances gastric emptying rate in healthy human subjects.

Studies on the effect of intragastric capsaicin on gastric ulcer and on the prostacyclin-induced cytoprotection in rats

The effect of intragastric (i.g.) capsaicin on experimental gastric ulcer was studied in the 1 h pylorus-ligated rats. Capsaicin applied in 40 ng ml-1 concentration (0.1 microgram kg-1) protected against gastric mucosal injury evoked by i.g. application of acidified aspirin, 96% ethanol or 0.6 M HCl. After a capsaicin concentration of 400 micrograms ml-1 (1 mg kg-1) protection occurred initially, while several hours later mucosal damage evoked by acidified aspirin was enhanced. Capsaicin in 2 and 6 ml kg-1 (10 and 30 mg kg-1) invariably aggravated the aspirin and ethanol-induced gastric mucosal damage. Capsaicin in 0.1 microgram kg-1 did not modify the mucosal protective action of prostacyclin (5 micrograms kg-1) on gastric mucosal injury produced by i.g. application of acidified aspirin, 96% ethanol or 0.6 M HCl. Local capsaicin desensitization induced by application of capsaicin in 2 mg ml-1 (10 mg kg-1) did not interfere with the mucosal cytoprotective effects of prostacyclin against ethanol and aspirin-induced mucosal damage. It is concluded that i.g. capsaicin exerts a dual dose-dependent effect on development of experimental gastric ulcer. Neither i.g. capsaicin in small doses nor local capsaicin desensitization modify the mucosal cytoprotective effects of prostacyclin.

Capsaicin research as a new tool to approach of the human gastrointestinal physiology, pathology and pharmacology

Abstract.Background:Capsaicin has been found to act on the capsaicin sensitive afferent nerves in animal experiments.Aim:The specific action of capsaicin on sensory afferent nerves affecting gastrointestinal (GI) functions was investigated in human GI physiology and pathology using pharmacological approaches.Materials and Methods:Observations were carried out in 98 normal healthy human subjects and in 178 patients with different gastrointestinal diseases (gastritis, erosions, ulcer, polyps, cancer, inflammatory bowel diseases, colorectal polyps, cancers). The gastric secretory responses and their chemical composition, gastric emptying, sugar loading test, gastric transmucosal potential difference (GTPD) were investigated following with administration of (a) capsaicin alone, (b) ethanol alone or with capsaicin, and (c) indomethacin-induced gastric mucosal microbleeding with or without capsaicin, both before and after 2 weeks capsaicin treatment. Immunohistochemical investigations were performed to establish the presence of the capsaicin (vanillinoid) receptor (TRVP1), CGRP and SP in the whole GI tract. Conventional molecular pharmacological methods were applied to study the effects of capsaicin and other drugs for their inhibitory effects on the gastric basal acid output.Results:Capsaicin decreased the gastric basal output, enhanced the “non parietal” (buffering) component of gastric secretory responses, gastric emptying, release of glucagon. Capsaicin prevents the indomethacin- and ethanol-induced gastric mucosal injury, while capsaicin itself enhanced the gastric transmucosal potential difference (GTPD). The capsaicin reactive receptors, TRVP1, CGRP, SP were detected in the GI mucosa in patients with different GI disorders, but their presence varied in acute and chronic GI disorders.Conclusion:Application of capsaicin offers a new research tool for understanding the vanilloid-related events of human GI functions in relation to normal physiology and in disease states and the use of pharmacological agents affecting these receptor mediated changes.

Four response stages of capsaicin-sensitive primary afferent neurons to capsaicin and its analog: gastric acid secretion, gastric mucosal damage and protection.

Abstract Capsaicin is the active component of red hot peppers, which modifies specifically the capsaicin‐sensitive sensory afferent nerves. The action of capsaicin is an initial short‐lasting stimulation, which is followed by desensitization to capsaicin itself, and to other stimuli of afferent sensory nerves. Four response stages of capsaicin‐sensitive primary afferents exist to capsaicin, depending on the dose and duration of exposure to the drug. These are excitation, a sensory blocking effect, long‐term selective neurotoxic impairment, and irreversible cell destruction. The possible roles of four stages of capsaicin‐sensitive primary afferents can be evaluated in relation to gastric acid secretion, and to the details of the defensive side of gastric mucosa against different chemicals, physical agents, drugs and other pathological stress. Capsaicin inhibited the gastric acid secretion in pylorus‐ligated rats when it was given intragastrically at a dose of 0.4–1.8 μg/kg. Small doses of capsaicin (up to 800 μg, i.g.) produced a dose‐dependent inhibition (ID50 = 400 μg), and its inhibitory effect was exerted for 1 h in healthy human subjects. While a small dose (5 μg/kg) of capsaicin caused inhibition, a high dose (50–100 mg/kg) enhanced the gastric mucosal lesions productivity by causing hyperacidity in pylorus‐ligated animals. Capsaicin and its analog inhibited the development of different chemically induced gastric mucosal damage in various experimental models if they were given intragastric doses (μg/kg). The final effects of capsaicin depend on the dosage and timing. The different effects are excitation, a sensory‐blocking effect, long‐term selective neurotoxic impairment and irreversible cell destruction.