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Kumar S, Dhiman M. Helicobacter pylori secretary Proteins-Induced oxidative stress and its role in NLRP3 inflammasome activation. Cell Immunol 2024; 399-400:104811. [PMID: 38518686 DOI: 10.1016/j.cellimm.2024.104811] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2023] [Revised: 01/09/2024] [Accepted: 01/15/2024] [Indexed: 03/24/2024]
Abstract
Helicobacter pylori-associated stomach infection is a leading cause of gastric ulcer and related cancer. H. pylori modulates the functions of infiltrated immune cells to survive the killing by reactive oxygen and nitrogen species (ROS and RNS) produced by these cells. Uncontrolled immune responses further produce excess ROS and RNS which lead to mucosal damage. The persistent oxidative stress is a major cause of gastric cancer. H. pylori regulates nicotinamide adenine dinucleotide phosphate (NADPH) oxidases (NOXs), nitric oxide synthase 2 (NOS2), and polyamines to control ROS and RNS release through lesser-known mechanisms. ROS and RNS produced by these pathways differentiate macrophages and T cells from protective to inflammatory phenotype. Pathogens-associated molecular patterns (PAMPs) induced ROS activates nuclear oligomerization domain (NOD), leucine rich repeats (LRR) and pyrin domain-containing protein 3 (NLRP3) inflammasome for the release of pro-inflammatory cytokines. This study evaluates the role of H. pylori secreted concentrated proteins (HPSCP) related oxidative stress role in NLRP3 inflammasome activation and macrophage differentiation. To perceive the role of ROS/RNS, THP-1 and AGS cells were treated with 10 μM diphenyleneiodonium (DPI), 50 μM salicyl hydroxamic acid (SHX), 5 μM Carbonyl cyanide-4-(trifluoromethoxy) phenylhydrazone (FCCP), which are specific inhibitors of NADPH oxidase (NOX), Myeloperoxidase (MPO), and mitochondrial oxidative phosphorylation respectively. Cells were also treated with 10 μM of NOS2 inhibitor l-NMMA and 10 μM of N-acetyl cysteine (NAC), a free radical scavenger·H2O2 (100 μM) treated and untreated cells were used as positive controls and negative control respectively. The expression of gp91phox (NOX2), NOS2, NLRP3, CD86 and CD163 was analyzed through fluorescent microscopy. THP-1 macrophages growth was unaffected whereas the gastric epithelial AGS cells proliferated in response to higher concentration of HPSCP. ROS and myeloperoxidase (MPO) level increased in THP-1 cells and nitric oxide (NO) and lipid peroxidation significantly decreased in AGS cells. gp91phox expression was unchanged, whereas NOS2 and NLRP3 downregulated in response to HPSCP, but increased after inhibition of NO, ROS and MPO in THP-1 cells. HPSCP upregulated the expression of M1 and M2 macrophage markers, CD86 and CD163 respectively, which was decreased after the inhibition of ROS. This study concludes that there are multiple pathways which are generating ROS during H. pylori infection which further regulates other cellular processes. NO is closely associated with MPO and inhibition of NLRP3 inflammasome. The low levels of NO and MPO regulates gastrointestinal tract homeostasis and overcomes the inflammatory response of NLRP3. The ROS also plays crucial role in macrophage polarization hence alter the immune responses duing H. pylori pathogenesis.
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Affiliation(s)
- Sandeep Kumar
- Department of Microbiology, School of Basic Sciences, Central University of Punjab, Bathinda, 151 401 Punjab, India
| | - Monisha Dhiman
- Department of Microbiology, School of Basic Sciences, Central University of Punjab, Bathinda, 151 401 Punjab, India.
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Mohamed YT, Naguib IA, Abo-Saif AA, Mohamed WR. Protective effects of perindopril against indomethacin-induced gastric mucosal damage through modulation of DDAH-1/ADMA and ACE-2/ANG-(1-7) signaling pathways. Drug Chem Toxicol 2021; 45:2509-2518. [PMID: 34384315 DOI: 10.1080/01480545.2021.1962672] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
Indomethacin is a widely used nonsteroidal anti-inflammatory drug; however, its clinical utility is accompanied by serious adverse reactions including peptic ulcers. The current study aims to investigate the protective potential of perindopril against indomethacin-induced gastric injury in rats. Perindopril (4 mg/kg) was administered orally for 7 days and indomethacin (60 mg/kg, single oral dose) was administered on the 7th day, 1 h after perindopril administration. Pantoprazole was used as a standard agent. Ulcer index (UI), preventive index ratio (PI), histopathological examination, oxidative stress, and inflammatory biomarkers were investigated. Perindopril significantly decreased UI while increased PI and counteracted histopathological aberrations induced by indomethacin. It alleviated indomethacin-induced oxidative stress by lowering NO while increasing GSH content and superoxide dismutase activity. Perindopril significantly downregulated TNF-α and asymmetric dimethylarginine (ADMA), while significantly upregulated COX-2, PGE-2, dimethylarginine dimethylaminohydrolase-1 (DDAH-1), ANG-(1-7), and ACE-2 expression. Together, these findings suggest the gastroprotective effects of perindopril through modulation of DDAH-1/ADMA and ACE-2/ANG-(1-7) signaling.HIGHLIGHTSPerindopril attenuated gastric histopathological damage.It increased GSH content and SOD activity while decreased NO content.It modulated gastric ADMA and DDAH-1 activity.It reduced TNF-α, while increased COX-2 and PGE-2 expression.It upregulated ACE-2 activity and ANG-(1-7) protein expression.
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Affiliation(s)
- Yasmin T Mohamed
- Department of Pharmacology and Toxicology, Faculty of Pharmacy, Nahda University, Beni-Suef, Egypt
| | - Ibrahim A Naguib
- Department of Pharmaceutical Chemistry, College of Pharmacy, Taif University, Taif, Saudi Arabia
| | - Ali A Abo-Saif
- Department of Pharmacology and Toxicology, Faculty of Pharmacy, Nahda University, Beni-Suef, Egypt
| | - Wafaa R Mohamed
- Department of Pharmacology and Toxicology, Faculty of Pharmacy, Beni-Suef University, Beni-Suef, Egypt
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Helicobacter pylori infection downregulates duodenal CFTR and SLC26A6 expressions through TGFβ signaling pathway. BMC Microbiol 2018; 18:87. [PMID: 30119655 PMCID: PMC6098588 DOI: 10.1186/s12866-018-1230-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2017] [Accepted: 08/09/2018] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND The pathogenesis of Helicobacter pylori (H. pylori) infection-induced duodenal ulcer remains to be elucidated. Duodenal mucosal bicarbonate secretion is the most important protective factor against acid-induced mucosal injury. We previously revealed that H. pylori infection downregulated the expression and functional activity of duodenal mucosal cystic fibrosis transmembrane conductance regulator (CFTR) and solute linked carrier 26 gene family A6 (SLC26A6) which are the two key duodenal mucosal epithelial cellular bicarbonate transporters to mediate duodenal bicarbonate secretion. In this study, we investigated the mechanism of H. pylori infection-induced duodenal CFTR and SLC26A6 expression downregulation. RESULTS We found that H. pylori infection induced the increase of serum transforming growth factor β (TGFβ) level and duodenal mucosal TGFβ expression and the decrease of duodenal mucosal CFTR and SLC26A6 expressions in C57 BL/6 mice. The results from the experiments of human duodenal epithelial cells (SCBN) showed that H. pylori increased TGFβ production and decreased CFTR and SLC26A6 expressions in SCBN cells. TGFβ inhibitor SB431542 reversed the H. pylori-induced CFTR and SLC26A6 expression decreases. The further results showed that TGFβ directly decreased CFTR and SLC26A6 expressions in SCBN cells. TGFβ induced the phosphorylation of p38 mitogen-activated protein kinase (MAPK) and P38 MAPK inhibitor SB203580 reversed the TGFβ-induced CFTR and SLC26A6 expression decreases. CONCLUSIONS H. pylori infection downregulates duodenal epithelial cellular CFTR and SLC26A6 expressions through TGFβ-mediated P38 MAPK signaling pathway, which contributes to further elucidating the pathogenesis of H. pylori-associated duodenal ulcer.
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Wen G, Jin H, Deng S, Xu J, Liu X, Xie R, Tuo B. Effects of Helicobacter pylori Infection on the Expressions and Functional Activities of Human Duodenal Mucosal Bicarbonate Transport Proteins. Helicobacter 2016; 21:536-547. [PMID: 27004488 DOI: 10.1111/hel.12309] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
BACKGROUND The mechanisms for Helicobacter pylori (H. pylori)-induced duodenal ulcerogenesis are not fully understood. In this study, we investigated the effects of H. pylori infection on the expressions and functional activities of human duodenal mucosal bicarbonate transport proteins and hope to further clarify the pathogenesis of H. pylori-associated duodenal ulcer. MATERIALS AND METHODS The experiments were performed in the patients with H. pylori-associated duodenal ulcers, H. pylori-associated chronic gastritis, and H. pylori-negative healthy subjects. Duodenal mucosal bicarbonate secretion was measured by Ussing Chamber technology. RESULTS The expressions of duodenal mucosal bicarbonate transport proteins, CFTR (cystic fibrosis transmembrane conductance regulator) and SLC26A6 (solute-linked carrier 26 gene A6), in the patients with H. pylori-associated duodenal ulcers were markedly lower than those in healthy controls. Basal and both forskolin- and prostaglandin E2 -stimulated duodenal mucosal bicarbonate secretions in the patients with H. pylori-associated duodenal ulcers were also lower than those in healthy controls. After anti-H. pylori treatment for H. pylori-associated duodenal ulcers, duodenal mucosal bicarbonate secretion and CFTR and SLC26A6 expressions in H. pylori-eradicated patients recovered to levels comparable to healthy controls, but those were found to be not significantly altered in non-H. pylori-eradicated patients. The further results showed that decreases in the H. pylori-induced CFTR and SLC26A6 expression were related to the severity and virulent factors of H. pylori infection. CONCLUSION H. pylori infection impairs the expressions and functional activities of duodenal mucosal bicarbonate transport proteins, CFTR and SLC26A6, which contributes to the development of duodenal ulcer.
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Affiliation(s)
- Guorong Wen
- Department of Gastroenterology, Affiliated Hospital, Zunyi Medical College, Zunyi, China.,Digestive Disease Institute of Guizhou Province, Zunyi, China.,Research Center of Medicine and Biology, Zunyi Medical College, Zunyi, China
| | - Hai Jin
- Department of Gastroenterology, Affiliated Hospital, Zunyi Medical College, Zunyi, China.,Digestive Disease Institute of Guizhou Province, Zunyi, China.,Research Center of Medicine and Biology, Zunyi Medical College, Zunyi, China
| | - Shili Deng
- Department of Gastroenterology, Affiliated Hospital, Zunyi Medical College, Zunyi, China.,Digestive Disease Institute of Guizhou Province, Zunyi, China
| | - Jingyu Xu
- Department of Gastroenterology, Affiliated Hospital, Zunyi Medical College, Zunyi, China.,Digestive Disease Institute of Guizhou Province, Zunyi, China.,Research Center of Medicine and Biology, Zunyi Medical College, Zunyi, China
| | - Xuemei Liu
- Department of Gastroenterology, Affiliated Hospital, Zunyi Medical College, Zunyi, China.,Digestive Disease Institute of Guizhou Province, Zunyi, China
| | - Rui Xie
- Department of Gastroenterology, Affiliated Hospital, Zunyi Medical College, Zunyi, China.,Digestive Disease Institute of Guizhou Province, Zunyi, China
| | - Biguang Tuo
- Department of Gastroenterology, Affiliated Hospital, Zunyi Medical College, Zunyi, China.,Digestive Disease Institute of Guizhou Province, Zunyi, China.,Research Center of Medicine and Biology, Zunyi Medical College, Zunyi, China
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Abstract
Numerous reports have indicated that the plasma concentration of endogenously produced inhibitors of nitric oxide synthase are elevated in human disease states. In this review we discuss recent advances in our understanding of the enzymes responsible for the synthesis of these inhibitors.
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Affiliation(s)
- Shelagh Anthony
- Centre for Clinical Pharmacology, The British Heart
Foundation Laboratories, University College London, UK
| | - James Leiper
- Centre for Clinical Pharmacology, The British Heart
Foundation Laboratories, University College London, UK
| | - Patrick Vallance
- Centre for Clinical Pharmacology, The British Heart
Foundation Laboratories, University College London, UK
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Gobert AP, Wilson KT. The Immune Battle against Helicobacter pylori Infection: NO Offense. Trends Microbiol 2016; 24:366-376. [PMID: 26916789 DOI: 10.1016/j.tim.2016.02.005] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2015] [Revised: 02/01/2016] [Accepted: 02/05/2016] [Indexed: 01/07/2023]
Abstract
Helicobacter pylori is a successful pathogen of the human stomach. Despite a vigorous immune response by the gastric mucosa, the bacterium survives in its ecological niche, thus favoring diseases ranging from chronic gastritis to adenocarcinoma. The current literature demonstrates that high-output of nitric oxide (NO) production by the inducible enzyme NO synthase-2 (NOS2) plays major functions in host defense against bacterial infections. However, pathogens have elaborated several strategies to counteract the deleterious effects of NO; this includes inhibition of host NO synthesis and transcriptional regulation in response to reactive nitrogen species, allowing the bacteria to face the nitrosative stress. Moreover, NO is also a critical mediator of inflammation and carcinogenesis. In this context, we review the recent findings on the expression of NOS2 in H. pylori-infected gastric tissues and epithelial cells, the role of NO in H. pylori-related diseases and H. pylori gene expression, and the mechanisms whereby H. pylori regulates NO synthesis by host cells.
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Affiliation(s)
- Alain P Gobert
- Division of Gastroenterology, Hepatology, and Nutrition, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232, USA; Center for Mucosal Inflammation and Cancer, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Keith T Wilson
- Division of Gastroenterology, Hepatology, and Nutrition, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232, USA; Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, TN 37232, USA; Department of Cancer Biology, Vanderbilt University Medical Center, Nashville, TN 37232, USA; Center for Mucosal Inflammation and Cancer, Vanderbilt University Medical Center, Nashville, TN 37232, USA; Veterans Affairs Tennessee Valley Healthcare System, Nashville, TN 37212, USA.
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Elfvin A, Edebo A, Hallersund P, Casselbrant A, Fändriks L. Oxidative and nitrosative stress enzymes in relation to nitrotyrosine in Helicobacter pylori-infected humans. World J Gastrointest Pathophysiol 2014; 5:373-379. [PMID: 25133038 PMCID: PMC4133535 DOI: 10.4291/wjgp.v5.i3.373] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/28/2014] [Revised: 04/25/2014] [Accepted: 06/11/2014] [Indexed: 02/06/2023] Open
Abstract
AIM: To compare a possible relation between Helicobacter pylori (H. pylori) and the oxygen- and nitrogen radical system in humans.
METHODS: Mechanisms for H. pylori to interfere with the oxygen and nitrogen radical system is of great importance for understanding of the H. pylori persistence and pathogenesis. Biopsies were obtained from the gastric wall of 21 individuals. Ongoing infection with H. pylori was detected using direct analyze from the biopsies using campylobacter-like organism test (CLO-test) and/or by using 14C-urea breath test. The individuals were divided in a negative H. pylori and a positive H. pylori group. Expression in the gastric mucosa of inducible nitric oxide syntase (iNOS), nicotinamide adenine dinucleotide phosphate-oxidase (NADPH-oxidase) myeloperoxidase (MPO), and nitrotyrosine were assessed by Western blotting.
RESULTS: The individuals who undervent gastroscopy were divided in a H. pylori neg. [n = 13, m/f = 7/6, age (mean) = 39] and a H. pylori pos. group [n= 8, m/f = 5/3, age (mean) = 53]. Using western blot analysis iNOS was detected as a 130 kDa band. The iNOS expression was upregulated in the antrum of H. pylori infected individuals in comparison to the controls, mean ± SD being 12.6 ± 2.4 vs 8.3 ± 3.1, P < 0.01. There was a markedly upregulated expression of MPO in the antrum of H. pylori infected individuals in comparison to the control group without infection. In several of non-infected controls it was not possible to detect any MPO expression at all, whereas the expression was high in all the infected subjects, mean ± SD being 5.1 ± 3.4 vs 2.1 ± 1.9, P < 0.05. The NADPH-oxidase expression was analysed by detecting the NADPH-oxidase subunit p47-phox expression. P47-phox was detected as a 47 kDa band using Western blot, and showed a significantly higher expression of p47-phox in the antrum of the H. pylori infected individuals compared to the controls, mean ± SD being 3.1 ± 2.2 vs 0.3 ± 0.2, P < 0.01. Regarding nitrotyrosine formation, Western blot did not show any significant increase or decrease compared to controls, 7.0 ± 0.9 vs 6.9 ± 1.1, not significant.
CONCLUSION: iNOS, MPO and NADPH-oxidase was up-regulated among H. pylori infected. Regarding nitrotyrosine no difference was found. This support an H. pylori related inhibition of radical formation.
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Zhang Z, Zou YY, Li FJ, Hu CP. Asymmetric dimethylarginine: A novel biomarker of gastric mucosal injury? World J Gastroenterol 2011; 17:2178-80. [PMID: 21633526 PMCID: PMC3092868 DOI: 10.3748/wjg.v17.i17.2178] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/14/2010] [Revised: 12/13/2010] [Accepted: 12/20/2010] [Indexed: 02/06/2023] Open
Abstract
Nitric oxide (NO), a multifunctional endogenous gas molecule, is metabolized from L-arginine by enzymatic reaction in the presence of nitric oxide synthase. NO, an important gas signaling molecule, is a gastric mucosa protective factor that contributes significantly to maintain normal gastric mucosa integrity. NO increases gastric mucosa blood flow, regulates the secretion of mucus and bicarbonate, and inhibits the secretion of gastric juice. Asymmetric dimethylarginine (ADMA) has been identified as the major endogenous inhibitor of nitric oxide synthase. The function of ADMA is to decrease NO production via inhibiting nitric oxide synthase activity. Besides inhibiting NO synthesis, ADMA also directly induces oxidative stress and cell apoptosis, and participates in inflammation reaction. Its systemic accumulation was observed in conjunction with several cardiovascular and metabolic diseases. ADMA also mediates gastric ulcer injury induced by ethanol, stress, helicobacter pylori and indomethacin. The mechanism of ADMA directly producing adverse effect in gastric mucosa is incompletely understood. It is widely accepted that NO bioavailability decrease is the majority reason. Promotion of apoptosis and aggravation of inflammation may be other important mechanisms of ADMA-induced gastric injury. ADMA might be a novel clinical and experimental biomarker related to gastric mucosa disorder. Although therapeutic tool targeting to ADMA is available in multiple cardiovascular diseases, it is unknown in gastrointestinal disease. The strategy to inhibit ADMA is beneficial to gastric ulcer induced by ethanol in rats. Thus, ADMA might be a candidate of therapeutic target in gastric mucosa damage.
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Helicobacter pylori eradication lowers serum asymmetric dimethylarginine levels. Mediators Inflamm 2010; 2010:685903. [PMID: 21197413 PMCID: PMC3010707 DOI: 10.1155/2010/685903] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2010] [Accepted: 11/03/2010] [Indexed: 02/07/2023] Open
Abstract
Introduction. Microbial pathogens, one of them is Helicobacter pylori (H. pylori), have frequently been implicated in the atherogenesis. Endothelium-derived nitric oxide (NO) is synthesized from L-arginine by nitric oxide synthase (NOS) and plays a pivotal role in the regulation of vascular tone. Asymmetric dimethylarginine (ADMA) is the most potent endogenous NOS inhibitor. Elevated levels of ADMA have been reported in many circumstances associated with a high cardiovascular risk. The aim of the present study was to investigate whether the eradication of H. pylori infection affects serum ADMA levels. Materials and Methods. Forty-two H. pylori-positive patients were enrolled in the study. Triple therapy for 14 days were given to all patients. Serum ADMA levels were measured at baseline and 2 months after therapy. Results. Eradication was achieved in 34 (81%) patients. The mean serum ADMA levels before and after therapy were 1, 77 ± 0, 30 and 1, 67 ± 0, 29 ng/mL in the group with H. pylori eradicated and 1, 63 ± 0, 28 and 1, 56 ± 0, 32 ng/mL in the noneradicated, respectively. We detected statistically significant decreased serum ADMA levels after therapy in H. pylori eradicated group. Conclusion. These findings have indicated that eradication of H. pylori infection may decrease the risk of atherosclerosis and cardiovascular events.
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Tuo B, Song P, Wen G, Sewald X, Gebert-Vogl B, Haas R, Manns M, Seidler U. Helicobacter pylori vacuolating cytotoxin inhibits duodenal bicarbonate secretion by a histamine-dependent mechanism in mice. J Infect Dis 2009; 199:505-12. [PMID: 19099486 DOI: 10.1086/596318] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
BACKGROUND The pathogenic mechanisms involved in Helicobacter pylori-induced duodenal mucosal injury are incompletely understood. In the present study, we sought to investigate the effect of H. pylori vacuolating cytotoxin (VacA) on duodenal mucosal bicarbonate (HCO3-) secretion. METHODS Concentrated bacterial culture supernatants from an H. pylori wild-type strain producing VacA with s1/m1 genotypes (P12) and from an isogenic mutant lacking VacA (P12DeltavacA) were used. HCO3- secretion by murine duodenal mucosa was examined in vitro in Ussing chambers. Duodenal mucosal histamine release was measured using enzyme-linked immunosorbent assay. The expression of histamine H2 receptor was examined by immunohistochemical analysis. RESULTS In a dose-dependent manner, the VacA-positive supernatant P12 reduced prostaglandin E2 (PGE2)-stimulated duodenal mucosal HCO3- secretion to a maximum of 49% (P<.0001), whereas P12DeltavacA did not result in significant inhibition (P>.05). Purified VacA had a similar effect. Histamine H2 receptor antagonists attenuated the effect of P12 on PGE2-induced HCO3- secretion. P12 stimulated duodenal histamine release in a dose-dependent manner, and exogenous histamine inhibited PGE2-stimulated duodenal HCO3- secretion. H2 receptor expression was found in duodenal epithelial cells, the enteric nerve plexus, and lymphocytes in Peyer's patch. CONCLUSIONS H. pylori VacA inhibits PGE2-stimulated duodenal epithelial HCO3- secretion by a histamine-dependent mechanism. This effect likely contributes to the damaging effect of H. pylori in the duodenal mucosa.
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Affiliation(s)
- Biguang Tuo
- Department of Gastroenterology, Affiliated Hospital of Zunyi Medical College, Zunyi, China.
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Henriksnäs J, Atuma C, Phillipson M, Sandler S, Engstrand L, Holm L. Acute effects of Helicobacter pylori extracts on gastric mucosal blood flow in the mouse. World J Gastroenterol 2009; 15:219-25. [PMID: 19132773 PMCID: PMC2653315 DOI: 10.3748/wjg.15.219] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
AIM: To investigate the mechanisms underlying the reduction in gastric blood flow induced by a luminal water extract of Helicobacter pylori (HPE).
METHODS: The stomachs of isoflurane-anesthetized mice were exteriorized, and the mucosal surface exposed. Blood flow was measured with the laser-Doppler technique, and systemic arterial blood pressure monitored. C57BL/6 mice were exposed to water extract produced from H pylori strain 88-23. To investigate the role of a nerve- or iNOS-mediated pathway, we used intraluminal lidocaine and iNOS-/- mice. Blood flow response to the endogenous nitric oxide synthase inhibitor asymmetric dimethyl arginine (ADMA) was also assessed.
RESULTS: In wild-type mice, HPE decreased mucosal blood flow by approximately 30%. This reduction was abolished in iNOS-deficient mice, and by pre-treatment with lidocaine. Luminally applied ADMA resulted in reduction in blood flow similar to that observed in wild-type mice exposed to HPE.
CONCLUSION: A H pylori water extract reduces gastric mucosal blood flow acutely through iNOS- and nerve-mediated pathways.
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Alpha-defensin-like product and asymmetric dimethylarginine increase in mesenteric lymph after hemorrhage in anesthetized rat. Shock 2008; 30:411-6. [PMID: 18391861 DOI: 10.1097/shk.0b013e31816a71cb] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Mesenteric lymph contains unidentified proinflammatory mediators that increase in concentration after hemorrhage. In the search for candidate mediators, we examined mesenteric lymph for the presence of proinflammatory substances that are known to be produced in the gut: (a) antimicrobial peptides and antimicrobial proteins produced in the Paneth cells of the intestine (alpha-defensin 4, secretory phospholipase A2 [sPLA2], and Reg 2 protein) and (b) asymmetric dimethylarginine (ADMA), an endogenous inhibitor of NOS. Anesthetized male rats were hemorrhaged to 40 mmHg and maintained at that pressure by intermittent blood withdrawal until the pressure fell to less than 40 mmHg (decompensation) at which point they were resuscitated with three times the shed blood volume of Ringer's lactate solution administered over 1 h. Mesenteric lymph samples were analyzed for ADMA by enzyme-linked immunosorbent assay and for alpha-defensin 4, sPLA2, and Reg2 by Western blotting. Protein concentration in lymph was unchanged by hemorrhage, but alpha-defensin 4 increased significantly (12-fold greater than control) as did ADMA (2-fold greater than control). The sPLA2 could not be detected in lymph, and Reg 2 was unchanged during hemorrhage. During resuscitation, lymph flow tended to increase, but the concentration of ADMA and alpha-defensin 4 by volume did not increase. Reg 2 decreased during resuscitation. The results indicate that ADMA and immunoreactive product to alpha-defensin 4 may contribute to the increase in inflammatory activity of mesenteric lymph during hemorrhage, but they are unlikely to be the mediators responsible for the increase in the concentration of inflammatory mediators in postresuscitation lymph.
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Wang L, Zhou Y, Peng J, Zhang Z, Jiang DJ, Li YJ. Role of endogenous nitric oxide synthase inhibitor in gastric mucosal injury. Can J Physiol Pharmacol 2008; 86:97-104. [PMID: 18418436 DOI: 10.1139/y08-003] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
To explore the role of the endogenous nitric oxide synthase (NOS) inhibitor asymmetric dimethylarginine (ADMA) in gastric mucosal injury, 3 models of gastric mucosal injury induced by ethanol, indomethacin, or cold stress were used in rats. The cultured human gastric mucosal epithelial cell line GES-1 infected by Helicobacter pylori (Hp) was selected to mimic human gastric mucosal injury. Gastric mucosal ulcer index (UI), levels of ADMA and NO, and activity of dimethylarginine dimethylaminohydrolase (DDAH) were determined in the mucosal injury models; in Hp-infected or ADMA-treated GES-1 cells, levels of ADMA, NO, and TNF-alpha and activity of DDAH were measured. The results showed that UI and levels of ADMA were markedly increased and accompanied by significantly decreased DDAH activity in the mucosal injury models. Incubation of GES-1 cells with Hp increased levels of TNF-alpha and ADMA and decreased activity of DDAH. Administration of ADMA also increased levels of TNF-alpha. The results suggest that ADMA plays an important role in facilitating gastric mucosal injury, an effect which is associated with inhibiting NO synthesis and inducing inflammatory reaction.
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Affiliation(s)
- Li Wang
- Department of Pharmacology, School of Pharmaceutical Sciences, Central South University, No.110 Xiang-Ya Road, Changsha 410078, China
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Glasgow RE, Rollins MD. Stomach and Duodenum. Surgery 2008. [DOI: 10.1007/978-0-387-68113-9_46] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Henriksnäs J, Phillipson M, Storm M, Engstrand L, Soleimani M, Holm L. Impaired mucus-bicarbonate barrier in Helicobacter pylori-infected mice. Am J Physiol Gastrointest Liver Physiol 2006; 291:G396-403. [PMID: 16614375 DOI: 10.1152/ajpgi.00017.2006] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
To resist the harsh intrinsic milieu, several lines of defense exist in the stomach. The aim of this study was to investigate the effect of the gastric pathogen Helicobacter pylori on these mechanisms in vivo. We used FVB/N mice expressing human alpha-1,3/4-fucosyl transferase (producing Lewis b epitopes) and inoculated with H. pylori 1. Mice were anesthetized with isoflurane or Hypnorm-midazolam, the stomach was exteriorized, and the surface of the corpus mucosa was exposed. Mucus thickness was measured with micropipettes, juxtamucosal pH (pH(jm)) was measured with pH-sensitive microelectrodes, blood flow was measured with laser-Doppler flowmetry, and mRNA levels of the bicarbonate transporter SLC26A9 were quantified with real-time PCR. The increase in mucosal blood flow seen in response to luminal acid (pH 1.5) in control animals (140 +/- 9% of control) was abolished in infected mice. The firmly adherent mucus layer was significantly thinner in infected mice (31 +/- 2 microm) than in control mice (46 +/- 5 microm), and no mucus accumulation occurred in infected mice. pH(jm) decreased significantly more on exposure to luminal acid in infected mice (luminal pH 1.5, pH(jm) 2.4 +/- 0.7) than in control mice (pH(jm) 6.4 +/- 0.5). Despite reduced pH(jm), SLC26A9 mRNA expression was significantly, by increased 1.9-fold, in infected mice. The reduction in pH(jm) by infection with H. pylori might be due to a reduced firmly adherent mucus layer, increased mucus permeability to H(+), and/or inhibition of bicarbonate transport. The upregulation of SLC26A9 in H. pylori-infected epithelium might be a result of continuous inhibition of the transporter, e.g., by ammonium, a H. pylori product, which has been previously shown to inhibit SLC26A9.
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Affiliation(s)
- Johanna Henriksnäs
- Dept. of Medical Cell Biology, Uppsala Univ., PO Box 571, Uppsala SE-751 23, Sweden.
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16
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Abstract
Numerous reports have indicated that the plasma concentration of endogenously produced inhibitors of nitric oxide synthase are elevated in human disease states. In this review we discuss recent advances in our understanding of the enzymes responsible for the synthesis of these inhibitors.
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Affiliation(s)
- Shelagh Anthony
- Centre for Clinical Pharmacology, The British Heart Foundation Laboratories, University College London, UK
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17
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Knipp M. How to Control NO Production in Cells: Nω,Nω-Dimethyl-L-Arginine Dimethylaminohydrolase as a Novel Drug Target. Chembiochem 2006; 7:879-89. [PMID: 16680784 DOI: 10.1002/cbic.200500527] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Affiliation(s)
- Markus Knipp
- Department of Chemistry, University of Arizona, 1306 East University Boulevard, Tucson, AZ 85721-0041, USA.
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Marra M, Bonfigli AR, Bonazzi P, Galeazzi R, Sirolla C, Testa I, Cenerelli S, Boemi M, Testa R. Asymptomatic Helicobacter pylori infection increases asymmetric dimethylarginine levels in healthy subjects. Helicobacter 2005; 10:609-14. [PMID: 16302987 DOI: 10.1111/j.1523-5378.2005.00359.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/09/2022]
Abstract
BACKGROUND Chronic infections have been demonstrated to be early factors of atherosclerosis and cardiovascular diseases, and their relevance increases when they are caused by agents with extremely broad spectrum of disease outcome such as Helicobacter pylori. The consequent endothelial impairment leads to a reduced bioavailability of nitric oxide. Increasing evidences have pointed out that the endogenous inhibitor of nitric oxide synthase, asymmetric dimethylarginine, defined as a risk factor for cardiovascular disease, may increase in infections and plays an important role impairing the vascular functions of the endothelium. Starting from these findings, we aim to investigate whether H. pylori may affect asymmetric dimethylarginine levels. MATERIALS AND METHODS The study was carried out on a group of 186 subjects (age 46.2 +/- 14.9 years). We evaluated asymmetric dimethylarginine, symmetric dimethylarginine, L-arginine, presence of H. pylori by 13C-urea breath test, and the main parameters of glyco and lipo metabolic balance. RESULTS Increased levels of asymmetric dimethylarginine were found in H. pylori-positive subjects with respect to H. pylori-negative subjects (0.46 x/ / 1.13 versus 0.42 x/ / 1.23 mol/l, p < .001, respectively). No differences were detected in L-arginine levels between the two groups. Multiple regression analysis performed in H. pylori-positive subjects and H. pylori-negative subjects showed profound differences in the variables related to asymmetric dimethylarginine (R2 = 66.9%, p < .01 versus 34.3%, p < .01, respectively) and symmetric dimethylarginine (R2 = 39.2%, p < .01 versus 20.6%, p = .09, respectively) levels. CONCLUSIONS Our data clearly demonstrate that H. pylori infection increases asymmetric dimethylarginine levels. Moreover, this infection causes a profound metabolic modification that alters the role of the known determinants of asymmetric dimethylarginine levels. We conclude that H. pylori infection must be taken into account as a cause of increased asymmetric dimethylarginine levels and that the eradication of H. pylori may therefore lead to a decrease in asymmetric dimethylarginine levels, which is a further reason for the reduction of the risk for cardiovascular disease in this large portion of population.
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Affiliation(s)
- Maurizio Marra
- Department of Gerontological Research, Diabetology Unit, INRCA, Ancona, Italy.
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Bergamini S, Vandelli L, Bellei E, Rota C, Manfredini P, Tomasi A, Albertazzi A, Iannone A. Relationship of asymmetric dimethylarginine to haemodialysis hypotension. Nitric Oxide 2005; 11:273-8. [PMID: 15566974 DOI: 10.1016/j.niox.2004.10.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2004] [Revised: 09/02/2004] [Indexed: 10/26/2022]
Abstract
Hypotension is one of the major complications in patients undergoing haemodialysis (HD), that is well evident in patients defined as "hypotension-prone." The mechanisms underlying the hypotensive episodes are not known. We carried out a clinical study on hypotension-prone HD patients to test the existence of a dysregulation in the nitric oxide (NO) generating pathway. Since asymmetric dimethylarginine (ADMA) is an endogenous compound which regulates NO synthesis, we measured its variation in plasma of stable-HD and hypotension-prone patients before, during, and at the end of HD. Before HD, the hypotension-prone patients have higher ADMA levels than stable-HD patients. The HD procedure significantly removes ADMA from plasma of stable-HD patients, while in the hypotension-prone ADMA levels are unchanged at the end of the HD. Moreover, in the hypotension-prone patients, during the hypotensive episode, a dramatic drop of ADMA levels is observed, followed by a rapid increase at the end of the HD. The symmetric dimethylarginine (SDMA), which has no effect on NO synthesis, is also high in plasma of both groups of HD patients compared to normal subjects, and in both groups its levels at the end of HD are significantly reduced. The hypotension-prone patients have basal TNF-alpha levels lower than the stable-HD groups, that significantly increase during the hypotensive episode. On the basis of these findings, we suggest that the hypotensive syndrome could be related to a dysregulation between ADMA metabolism and clearance due both to cytokines release and to an extremely fast ADMA clearance during HD, leading to an increase in NO blood levels.
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Affiliation(s)
- Stefania Bergamini
- Department of Biomedical Sciences, University of Modena and Reggio Emilia, Modena, Italy
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Chang FY, Chen CY, Lu CL, Luo JC, Lu RH, Lee SD. Response of blood endothelin-1 and nitric oxide activity in duodenal ulcer patients undergoing Helicobacter pylori eradication. World J Gastroenterol 2005; 11:1048-51. [PMID: 15742413 PMCID: PMC4250770 DOI: 10.3748/wjg.v11.i7.1048] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
AIM: To investigate the effect of Helicobacter pylori eradication on endothelin-1 (ET-1) and nitric oxide (NO) in duodenal ulcer (DU) patients.
METHODS: Sixty-six H pylori-infected active DU patients were consecutively enrolled to receive one-week triple therapy (rabeprazole, amoxicillin and metronidazole) and then one-month rabeprazole therapy. They were asked back to determine ulcer and H pylori status using endoscopy one month later. Thirty-seven healthy controls (H pylori +/-: 17/20) were enrolled for comparison. Blood samples were collected in each visit to measure plasma ET-1 and nitrate/nitrite levels using an enzyme immunoassay kit.
RESULTS: Sixty DU patients finished trial per protocol. The ulcer healing and H pylori-eradication rates were 86.7% and 83.3%, respectively. Plasma ET-1 level in DU patients was higher than that of H pylori-negative and positive controls (3.59±0.96 vs 0.89±0.54 vs 0.3±0.2 pg/mL, P<0.01), while nitrate/nitrite levels among them were also significantly different (8.55±0.71 vs 5.27±0.68 vs 6.39±0.92 µmol/L, P<0.05). H pylori eradication diminished ET-1 levels (3.64±0.55 vs 2.64±0.55 pg/mL, P<0.01) but elevated nitrate/nitrite level (8.16±0.84 vs 11.41±1.42 µmol/L, P<0.05).
CONCLUSION: Both plasma ET-1 and nitrate/nitrite levels increase in active DU patients. After an effective H pylori eradication, DU healing is associated with diminished blood ET-1 level and elevated nitrate/nitrite level.
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Affiliation(s)
- Full-Young Chang
- Chief, Division of Gastroenterology, Taipei Veterans General Hospital, 201, Section 2, Shih-Pai Road, Taipei 112, Taiwan, China.
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Tuo BG, Sellers ZM, Smith AJ, Barrett KE, Isenberg JI, Dong H. A role for CagA/VacA in Helicobacter pylori inhibition of murine duodenal mucosal bicarbonate secretion. Dig Dis Sci 2004; 49:1845-52. [PMID: 15628715 DOI: 10.1007/s10620-004-9582-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Duodenal mucosal bicarbonate secretion is diminished in patients with Helicobacter pylori (HP)-associated duodenal ulcer disease. We examined whether HP water extracts inhibit murine duodenal mucosal bicarbonate secretion in vitro, and the mechanisms involved. Murine duodenal mucosae were mounted in Ussing chambers. Short-circuit current and bicarbonate secretion was measured. CagA/VacA-positive HP water extract (HPWE+/+) markedly inhibited PGE2-, carbachol-, or the calcium ionophore A23187-stimulated bicarbonate secretion in a dose-dependent manner. While 3-isobutyl-1-methylxanthine-stimulated bicarbonate secretion was not affected by HPWE+/+, HPWE+/+ did diminish forskolin-stimulated bicarbonate secretion. HPWE+/+ markedly diminished PGE2-induced increases in duodenal mucosal cAMP. CagA/VacA of HP decreases Ca2+-mediated bicarbonate secretion downstream of increases in intracellular Ca2+. Dimunition of PGE2-stimulated bicarbonate secretion occurs, in part, by inhibition of adenylate cyclase, which leads to decreased cAMP levels. The ability of virulent HP strains to inhibit duodenal bicarbonate secretion through multiple intracellular pathways likely contributes to the pathogenesis of HP-associated duodenal ulcer disease.
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Affiliation(s)
- Bi-Guang Tuo
- Division of Gastroenterology, Department of Medicine, University of California, San Diego, School of Medicine, San Diego, California 92103, USA
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Abstract
An increasing number of reports in the literature indicate that endogenously produced inhibitors of nitric oxide synthase (NOS), particularly asymmetric dimethylarginine (ADMA) regulate nitric oxide generation in numerous disease states. Two dimethylarginine dimethylaminohydrolase (DDAH) enzymes metabolise ADMA. We and others have postulated that activity of DDAH is a key determinant of ADMA levels in vivo. This review summarises recent advances in the regulation and function of DDAH enzymes and its role in the regulation of nitric oxide generation.
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Affiliation(s)
- Cam T L Tran
- Centre for Clinical Pharmacology and Therapeutics, BHF Laboratories, Division of Medicine, University College London, 5 University Street, London, WC1E 6JJ, UK
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24
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Yoshida N, Ishikawa T, Ichiishi E, Yoshida Y, Hanashiro K, Kuchide M, Uchiyama K, Kokura S, Ichikawa H, Naito Y, Yamamura Y, Okanoue T, Yoshikawa T. The effect of rebamipide on Helicobacter pylori extract-mediated changes of gene expression in gastric epithelial cells. Aliment Pharmacol Ther 2003; 18 Suppl 1:63-75. [PMID: 12925142 DOI: 10.1046/j.1365-2036.18.s1.7.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
BACKGROUND Recent studies have shown that Helicobacter pylori affects intracellular signal transduction in host cells, leading to the activation of transcriptional factors and the induction of pro-inflammatory cytokines. On the other hand, rebamipide, an anti-gastritis and anti-ulcer agent, could scavenge reactive oxygen species and reduce interleukin-8 (IL-8) expression in gastric epithelial cells induced by H. pylori-stimulation through the attenuated activation of nuclear factor-kappaB (NF-kappaB). AIMS In this study, we investigated the effects of rebamipide on gene expression in H. pylori-stimulated epithelial cells using DNA chip. METHODS H. pylori water extract (HPE) was prepared from NCTC11637, the type strain of H. pylori. Total RNA was extracted from MKN45 cells, a human gastric cancer cell line, following HPE-stimulation with and without rebamipide for 3 h, and differences in gene expression profiles were observed using GeneChip and Human 6800 probe array. RESULTS The GeneChip analysis demonstrated that 132 up-regulated genes and 873 down-regulated genes, such as growth factors, chemokines and transcription factors, were detected in MKN45 cells 3 h after stimulation of H. pylori. Among them, several genes, including bFGF, RANTES and MIP-2beta, were previously unknown to be expressed in H. pylori-stimulated human gastric cells. Rebamipide reduced expression of 119 genes encoding cytokines, growth factors and their receptors and transcription factors. CONCLUSIONS These findings suggest that rebamipide could inhibit inflammatory reactions and tumour progression by modifying H. pylori infection-induced gene expression in gastric epithelial cells.
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Affiliation(s)
- N Yoshida
- Molecular Gastroenterology and Hepatology and Inflammation and Immunology, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto, Japan.
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25
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von Bothmer C, Bölin I, Pettersson A, Fändriks L. Stimulated murine macrophages as a bioassay for H. pylori-related inhibition of nitric oxide production. Scand J Gastroenterol 2003; 38:380-6. [PMID: 12739709 DOI: 10.1080/00365520310000816] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
BACKGROUND Interference with the L-arginine/nitric oxide pathway may be a virulence strategy for the gastric pathogen Helicobacter pylori. This study evaluates a bioassay for such inhibitory actions on nitric oxide synthase. METHODS Cultured murine macrophages were stimulated by lipopolysaccharide and interferon-gamma. Nitric oxide synthesis and the expression of inducible nitric oxide synthase (iNOS) at increasing concentrations of L-arginine were analysed using chemiluminescence and Western blotting, respectively. RESULTS The bioassay was evaluated against nitrite accumulation and two established NOS inhibitors. Bacterial extracts or whole cells of one H. pylori strain inhibited nitric oxide production at low L-arginine concentrations (2-20 microM). A higher concentration of L-arginine (200 microM) was not associated with such inhibition. The iNOS expression was not affected by any of the additives compared to stimulated controls. CONCLUSIONS This bioassay is a reliable and simple method for analysing iNOS inhibition, resolving effects on enzyme activity or enzyme expression. H. pylori water extract and whole cells exert an L-arginine-dependent NOS inhibition, not influencing iNOS expression.
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Affiliation(s)
- C von Bothmer
- Dept. of Gastrosurgical Research, Sahlgrenska Academy, Göteborg University, Gothenburg, Sweden.
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26
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Abstract
The discovery of Helicobacter pylori has greatly changed our approach to peptic ulcer disease. Bacterial, host, and environmental factors all have a role in peptic-ulcer disease. Although the prevalence of uncomplicated peptic ulcers is falling, hospital admissions for ulcer complications associated with non-steroidal anti-inflammatory drugs (NSAIDs) are rising. Evidence suggests that prescription of NSAIDs along with potent antiulcer agents and the use of highly selective cyclo-oxygenase-2 inhibitors reduce gastroduodenal ulceration. Whether these therapeutic advances will translate into clinical benefits remains to be seen. The interaction between H pylori and NSAIDs is one of the most controversial issues in peptic ulcer disease. With the fall in rates of H pylori infection, the proportion of ulcers not related to this organism and NSAIDs has risen, which will affect the management of peptic ulcer.
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Affiliation(s)
- Francis K L Chan
- Department of Medicine and Therapeutics, Prince of Wales Hospital, Chinese University of Hong Kong, Hong Kong, China.
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27
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Olbe L, Fandriks L, Hamlet A, Svennerholm AM, Thoreson AC. Mechanisms involved in Helicobacter pylori induced duodenal ulcer disease: an overview. World J Gastroenterol 2000; 6:619-623. [PMID: 11819661 PMCID: PMC4688830 DOI: 10.3748/wjg.v6.i5.619] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
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Lamarque D, Moran AP, Szepes Z, Delchier JC, Whittle BJ. Cytotoxicity associated with induction of nitric oxide synthase in rat duodenal epithelial cells in vivo by lipopolysaccharide of Helicobacter pylori: inhibition by superoxide dismutase. Br J Pharmacol 2000; 130:1531-8. [PMID: 10928954 PMCID: PMC1572225 DOI: 10.1038/sj.bjp.0703468] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
The products released by Helicobacter pylori (H. pylori) in the gastric antral and duodenal mucosa may be involved in mucosal ulceration by stimulating the local formation of cytotoxic factors such as nitric oxide (NO), superoxide or peroxynitrite. The present study investigates the ability of purified H. pylori lipopolysaccharide (LPS) to induce nitric oxide synthase (iNOS) in rat duodenal epithelial cells following in vivo challenge and its interaction with superoxide in promoting cellular damage and apoptosis. H. pylori LPS (0.75-3 mg kg(-1) i.v. or 3-12 mg kg(-1) p.o.) induced a dose - dependent expression of iNOS activity after 5 h in the duodenal epithelial cells, determined by [(14)C] arginine conversion to citrulline. The epithelial cell viability, as assessed by Trypan Blue exclusion and MTT conversion, was reduced 5 h after challenge with H. pylori LPS, while the incidence of apoptosis was increased. The iNOS activity and reduction in cell viability following H. pylori LPS challenge i.v. was inhibited by the selective iNOS inhibitor, 1400 W (0.2-5 mg kg(-1) i.v.). Concurrent administration of superoxide dismutase conjugated with polyethylene glycol (250 - 500 i.u. kg(-1), i.v.), which did not modify the cellular iNOS activity, reduced the epithelial cell damage provoked by i.v. H. pylori LPS, and abolished the increased incidence of apoptosis. These results suggest that expression of iNOS following challenge with H. pylori LPS provokes duodenal epithelial cell injury and apoptosis by a process involving superoxide, implicating peroxynitrite involvement. These events may contribute to the pathogenic mechanisms of H. pylori in promoting peptic ulcer disease.
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Affiliation(s)
- D Lamarque
- Institut National de la Santé et de la Recherche Médicale (INSERM U.99) et Service d'Hépatologie et de Gastroentérologie, Hôpital Henri Mondor, F-94010 Créteil, France
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29
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Olbe L, Fändriks L, Hamlet A, Svennerholm AM. Conceivable mechanisms by which Helicobacter pylori provokes duodenal ulcer disease. Best Pract Res Clin Gastroenterol 2000; 14:1-12. [PMID: 10749085 DOI: 10.1053/bega.1999.0055] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
A conceivable concept for the development of duodenal ulcers in Helicobacter pylori (H. pylori) infected subjects is presented in this chapter. The concept includes an explanation of the fact that only a minority of all H. pylori-infected subjects will develop a duodenal ulcer. Helicobacter pylori infection of the antrum induces a hypersecretion of gastric acid secretion, giving rise to gastric metaplasia in the duodenal bulb. This gastric metaplasia is a prerequisite for H. pylori colonization of the bulb. These events are common to all H. pylori-infected subjects. However, a much higher density of H. pylori bacteria and colonization with virulent organisms has been found in the bulb of duodenal ulcer patients, resulting in a much stronger inflammatory reaction with active duodenitis and an impaired bicarbonate secretion. These characteristics, together with acid hypersecretion, seem to be the important factors in evoking a duodenal ulcer.
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Affiliation(s)
- L Olbe
- Department of Surgery, Sahlgren Hospital, Göteborg, Sweden
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Atuma C, Engstrand L, Holm L. Helicobacter pylori extracts reduce gastric mucosal blood flow by a nitric oxide-independent but mast cell- and platelet-activating factor receptor-dependent pathway in rats. Scand J Gastroenterol 1999; 34:1183-9. [PMID: 10636064 DOI: 10.1080/003655299750024689] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
BACKGROUND We have previously shown that water extracts from Helicobacter pylori reduce gastric mucosal blood flow by approximately 15%. It has also been suggested that H. pylori can inhibit endogenous nitric oxide (NO) biosynthesis. Our aim was to examine whether the reduction in blood flow induced by H. pylori is the direct consequence of an NO synthase inhibition and the possible involvement of mast cell degranulation. METHODS A water extract was produced from wildtype strain 88-23. The extract was applied on the exteriorized gastric corporal mucosa in inactin-anesthetized rats, after removing as much as possible of the mucus layer, during intravital microscopy. Blood flow was measured with laser-Doppler flowmetry. RESULTS In rats pretreated with the NO synthase inhibitor N-nitro-L-arginine there was a 19% +/- 6% reduction in blood flow 40 min after application of the extract, and a 27% +/- 9% reduction after another 20 min with saline. The reduction was abolished by concomitant pretreatment with the mast cell stabilizer ketotifen or the platelet-activating factor (PAF) receptor antagonist WEB2086. CONCLUSION The reduction in mucosal blood flow induced by the extract was probably mediated through an acute inflammatory response involving mast cell degranulation with consequent PAF secretion. The effect on blood flow was not the result of a decrease in vascular tone due to an inhibition of endogenous NO biosynthesis.
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Affiliation(s)
- C Atuma
- Dept. of Physiology, Uppsala University, Sweden
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31
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Takeuchi K, Ukawa H, Kato S, Furukawa O, Araki H, Sugimoto Y, Ichikawa A, Ushikubi F, Narumiya S. Impaired duodenal bicarbonate secretion and mucosal integrity in mice lacking prostaglandin E-receptor subtype EP(3). Gastroenterology 1999; 117:1128-35. [PMID: 10535876 DOI: 10.1016/s0016-5085(99)70398-7] [Citation(s) in RCA: 81] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
BACKGROUND & AIMS To examine the involvement of EP(3) receptors in physiological regulation of duodenal HCO(3)(-) secretion, we disrupted the gene encoding EP receptors in mice by homologous recombination and evaluated acid-induced HCO(3)(-) secretion, which is physiologically important in the mucosal defense against acid injury, using EP(1)- and EP(3)-receptor knockout mice. METHODS The experiments were performed in the following 3 groups of mice after 18 hours of fasting: wild-type [WT (+/+)] mice, EP(1)-receptor knockout [EP(1) (-/-)] mice, and EP(3)-receptor knockout [EP(3) (-/-)] mice. Under urethane anesthesia, the proximal duodenal loop was perfused with saline that was gassed with 100% O(2), heated at 37 degrees C, and kept in a reservoir, and HCO(3)(-) secretion was measured at pH 7.0 using a pH-stat method and by adding 5 mmol/L HCl. RESULTS The duodenum of WT (+/+) mice increased HCO(3)(-) secretion in response to luminal perfusion of prostaglandin E(2) and forskolin as well as mucosal acidification. The latter effect was significantly inhibited by prior administration of indomethacin. HCO(3)(-) response to acid was observed in EP(1) (-/-) mice but disappeared totally in EP(3) (-/-) animals, although the acidification increased mucosal PGE(2) generation by similar degrees in all groups. The HCO(3)(-) stimulatory action of PGE(2) was also absent in EP(3) (-/-) but not EP(1) (-/-) mice, but forskolin effect was observed in both groups of animals, similar to WT (+/+) mice. Perfusion of the duodenum with 20 mmol/L HCl for 4 hours caused severe damage in EP(3) (-/-) mice and WT (+/+) animals pretreated with indomethacin, but not in EP(1) (-/-) mice. CONCLUSIONS The presence of EP(3)-receptors is essential for maintaining duodenal HCO(3)(-) secretion and mucosal integrity against luminal acid.
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Affiliation(s)
- K Takeuchi
- Department of Pharmacology, Kyoto Pharmaceutical University, Yamashina, Kyoto, Japan.
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Flemström G, Hällgren A, Nylander O, Engstrand L, Wilander E, Allen A. Adherent surface mucus gel restricts diffusion of macromolecules in rat duodenum in vivo. THE AMERICAN JOURNAL OF PHYSIOLOGY 1999; 277:G375-82. [PMID: 10444452 DOI: 10.1152/ajpgi.1999.277.2.g375] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/13/2023]
Abstract
The aim of this study was to investigate the permeability of the adherent mucus gel layer in rat duodenum in vivo to macromolecules applied in the lumen. Rats were anesthetized with thiobarbiturate, and the duodenum was perfused with isotonic NaCl solution containing large-molecular-size secretagogues. Effects on mucosal HCO(-)(3) secretion and blood-to-lumen (51)chromium-labeled EDTA clearance were used as indexes that compounds had migrated across the mucus layer. Exposure to a low concentration of papain (10 U/100 ml) for 30 min removed the mucus layer without damage to the epithelium and induced or markedly enhanced HCO(-)(3) secretory responses to cholera toxin (molecular mass of 85 kDa) or glucagon (3.5 kDa). Water extracts from a VacA cytotoxin (89 kDa) producing Helicobacter pylori strain, but not from a toxin-negative isogenic mutant, caused a small increase in HCO(-)(3) secretion but only after the mucus layer had been removed by papain. The duodenal surface mucus gel thus significantly restricts migration of macromolecules to the duodenal surface. Release of bacterial toxins at the cell-mucus interface may enhance or be a prerequisite for their effects on the gastrointestinal mucosa.
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Affiliation(s)
- G Flemström
- Department of Physiology, Uppsala University, SE-751 23 Uppsala, Sweden.
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Abstract
Helicobacter pylori is a gram-negative spiral bacterium confined to the habitat of gastric-type epithelium. H. pylori causes duodenal ulceration by a cumulative effect of antral predominant gastritis with increased acid secretion, consequent gastric metaplasia in the duodenum (a site of further colonization by H. pylori), duodenitis, reduced duodenal bicarbonate secretion, and mucosal damage. Bacterial factors influence outcome. Major determinants are the production of a vacuolating toxin and the presence of CagA, an immunodominant product of a nonconserved gene cagA, a marker for the cag pathogenicity island that encodes virulence genes involved in induction of epithelial chemokine responses. In ulcer patients the mucosal immune response is polarized to a T-helper-1 (Th1) cell-mediated response, which may contribute to mucosal damage. Eradication of H. pylori restores acid output to normal. Loss of both acid and bacteria halts gastroduodenitis and allows ulcer healing. Gastric metaplasia does not regress in the short term.
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Affiliation(s)
- M M Walker
- Department of Histopathology, Imperial College School of Medicine at St Mary's, London, United Kingdom
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