Accumulation of 8-nitroguanine in human gastric epithelium induced by Helicobacter pylori infection

Helicobacter pylori infection causes chronic inflammation, which can lead to gastric carcinoma. A double immunofluorescence labeling study demonstrated that the level of 8-nitroguanine and 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) apparent in gastric gland epithelium was significantly higher in gastritis patients with H. pylori infection than in those without infection. A significant accumulation of proliferating cell nuclear antigen, a prognostic factor for gastric cancer, was observed in gastric gland epithelial cells in patients with H. pylori infection as compared to those without infection, and its accumulation was closely correlated with the formation of 8-nitroguanine and 8-oxodG. These results suggest that nitrosative and oxidative DNA damage in gastric epithelial cells and their proliferation by H. pylori infection may lead to gastric carcinoma. 8-Nitroguanine could be not only a promising biomarker for inflammation but also a useful indicator of the risk of gastric cancer development in response to chronic H. pylori infection.     

A novel in vitro infection model of Helicobacter pylori using mucin-producing murine gastric surface mucous cells

BACKGROUND: Helicobacter pylori is found within the gastric surface mucous gel layer and in the epithelial surface. Gastric cancer cells have been used in experimental H. pylori infection in vitro, although cancer cells have some abnormalities in cellular properties. The aim of this study was to develop an in vitro H. pylori infection model using normal gastric surface cells that produce gastric mucin. MATERIALS AND METHODS: Normal murine gastric surface mucous cells (GSM06) were cultured by the liquid interface method using a serum-free medium and a collagen gel containing a fibroblast cell line (L929) and infected with H. pylori. Infection by H. pylori was assessed by enumerating the colony-forming units (CFU) of H. pylori adhered to GSM06 cells and by transmission electron microscopy. The production of mucin was determined by a lectin binding assay, sugar analysis, and MUC5AC gene expression. RESULTS: GSM06 cells cultured under these conditions produced mucin containing N-acetylgalactosamine and MUC5AC as the core protein. Significantly higher numbers of H. pylori adhered to GSM06 cells under mucin-producing conditions than under nonproducing conditions. Microscopic observation showed a filamentous structure resembling a type IV secretion system apparatus formed between the surface of GSM06 cells and H. pylori. CONCLUSIONS: This study demonstrates a novel in vitro H. pylori infection model using mucin-producing murine GSM06 cells for early stages of infection.     

Influence of vitamin E on gastric mucosal injury induced by Helicobacter pylori infection

We investigated the effect of vitamin E on gastric mucosal injury induced by Helicobacter pylori (H. pylori) infection. Male Mongolian gerbils were divided into 4 groups (normal group without H. pylori infection, vitamin E-deficient, -sufficient and -supplemented groups with H. pylori infection). Following oral inoculation with H. pylori (ATCC43504 2 x 10(8) CFU), animals were fed diets alpha-tocopherol 2 mg/100 g diet in the normal and vitamin E-sufficient groups and alpha-tocopherol 0.1 mg/100 g and 50 mg/100 g in the vitamin E-deficient and -supplemented groups, respectively, for 24 weeks. Chronic gastritis was detected in all gerbils inoculated H. pylori. Gastric ulcer was detected in 2 of 7 gerbils only in the vitamin E-deficient group. In the vitamin E-deficient group, myeloperoxidase activity and mouse keratinocyte derived chemokine (KC) in gastric mucosa was significantly higher than in the vitamin E supplemented group. Subsequently, in an in vitro study expression of CD11b/CD18 on neutrophils was enhanced by H. pylori water extract. This effect was suppressed in a dose dependent manner by the addition of alpha-tocopherol. These results suggest that vitamin E has a protective effect on gastric mucosal injury induced by H. pylori infection in gerbils, through the inhibition of accumulation of activated neutrophils.     

Diverse H. pylori strains,IL-10 promoter polymorphisms with high morbidity of gastric cancer in Hexi area of Gansu Province,China

In Hexi area of Gansu Province, people have a higher susceptibility of gastric cancer than people in the rest area of China. There is substantial geographic variation in the incidence of gastric cancer. In this article, the present author explored the roles of H. pylori infection and IL-10 promoter polymorphisms in development of gastric cancer in this area. A total of 304 participants were admitted to our study, and they were divided into two groups: control group and case group. Blood samples from all subjects were collected for gene extraction using DNA extraction kits. IL-10 polymorphisms were determined by SNaPshot Multiplex. To test H. pylori infection and its typing H. pylori antibody Immunoblotting Kits were used. This research suggested that environmental factor played an important role in the pathogenesis of gastric carcinoma in the area, H. pylori infection increased the risk of gastric cancer (OR = 2.612, 95% CI 1.636-4.170) and subject with H. pylori I-type positive was at significantly higher risk for progression to gastric cancer (OR = 4.712, 95% CI 2.656-8.537). For subjects with the ATA/GCC or GCC/GCC haplotype of the IL-10-1082/-819/-592 polymorphism relative to the ATA/ATA haplotype group, the risk of gastric cancer development was significantly increased. It has been demonstrated that the presence of IL-10-819 C alleles and IL-10-592 C alleles was associated with an increased risk for gastric cancer development in H. pylori-infected patients and IL-10 promoter polymorphisms and H. pylori have a synergistic effect on gastric cancer in Hexi population.     

Role of tumor necrosis factor-alpha and interferon-gamma in Helicobacter pylori infection

Immune responses to Helicobacter pylori infection play important roles in gastroduodenal diseases. The contributions of tumor necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma) to the induction of gastric inflammation and to the protection from H. pylori infection were investigated using TNF-alpha geneknockout (TNF-alpha(-/-)) mice and IFN-gamma gene-knockout (IFN-gamma(-/-)) mice. We first examined the colonizing ability of H. pylori strain CPY2052 in the stomach of C57BL/6 wild-type and knockout mice. The number of H. pylori colonized in the stomach of IFN-gamma(-/-) and TNF-alpha(-/-) mice was higher than that of wild-type mice. These findings suggest that TNF-alpha and IFN-gamma may play a protective role in H. pylori infection. Furthermore, we examined the contribution of TNF-alpha and IFN-gamma to gastric inflammation. The CPY2052-infected TNF-alpha(-/-) mice showed a moderate infiltration of mononuclear cells in the lamina propria and erosions in the gastric epithelium as did wild-type mice, whereas the CPY2052-infected IFN-gamma(-/-) mice showed no inflammatory findings even 6 months after infection. These results demonstrate that IFN-gamma may play an important role in gastric inflammation induced by H. pylori infection, whereas TNF-alpha may not participate in the development of inflammatory response.     

Proliferative activity of gastric epithelial cells in Helicobacter pylori infected children

Helicobacter pylori infection has been associated with gastric carcinogenesis. Gastric epithelial cells proliferative rate is accelerated in H. pylori infected adult patients. Our study was performed to evaluate proliferative cell activity in gastric epithelium in the course of H. pylori infection in the early stage of its natural history. Gastric antral biopsy specimens were obtained from thirteen H. pylori positive and seven negative children. To assess replication rates we used nucleolar organiser regions staining with colloidal silver nitrate technique (AgNOR). The number of AgNORs per nucleus, area of single AgNOR, and the quotient of these two parameters (AgNOR content) were analysed. The mean area of AgNOR was lower in H. pylori positive than in negative children. Conversely, both the mean number of AgNOR per nucleus and AgNOR content were higher in infected than non infected subjects. These results show accelerated proliferation of gastric antral epithelial cells in the course of H. pylori infection in children. Such alteration of cell replication occurring in an initial phase of natural history of long lasting infection provides an explanation for the association between acquisition of H. pylori infection in the first years of life and the development of gastric cancer.     

胃癌前病变患者胃蛋白酶原、促胃液素-17水平变化及幽门螺杆菌感染情况

目的研究胃癌前病变患者胃蛋白酶原、促胃液素-17及幽门螺杆菌(H.pylori)感染情况变化。方法试验组患者选取2017年8月至2018年8月间于我院进行治疗的100例胃癌前病变患者,对照组选取来我院体检中心进行体检的健康人员60例,对比两组人群胃蛋白酶原、促胃液素-17及H.pylori感染情况变化。结果试验组PGI(57.45±11.52)、PGII(8.65±1.75)、PGR(5.89±1.26)和促胃液素-17(8.05±1.45)水平显著低于对照组(均P<0.05);试验组H.pylori感染率81.00%显著高于对照组感染率41.67%,差异有统计学意义(P<0.05)。结论胃癌前病变患者PGI、PGII、PGR和促胃液素-17水平较低,并且H.pylori感染率高,患病与H.pylori感染有一定关系,胃蛋白酶原、促胃液素-17和H.pylori感染率对胃癌前病变临床诊断有重要作用,能够作为胃癌前病变患者筛查参考指标。     

Synergism of Helicobacter pylori infection and stress on the augmentation of gastric mucosal damage and its prevention with alpha-tocopherol

Despite evidence that Helicobacter pylori (H. pylori) infection is closely associated with stress in gastric ulcer patients, the underlying mechanism why ulcer recurrence after stress is augmented especially in patients with H. pylori remains unknown. In this study, we found that oxidative stress played a critical role in the augmented mucosal damage provoked by water immersion restraint stress (WIRS) in H. pylori infection and that an antioxidant, alpha-tocopherol, could ameliorate the aggravation of stress-associated gastric mucosal damage. Two hundred forty SD rats were divided into two groups according to H. pylori inoculation, and after 24 weeks of H. pylori infection, the water immersion restraint stress was imposed for 30, 120, or 480 min, respectively. To evaluate the therapeutic effects of an antioxidant, alpha-tocopherol was administrated 40 mg/kg daily prior to imposing WIRS. Remarkably increased hemorrhagic lesions and bleeding indexes were noted in the H. pylori-infected group with statistical significance (P < 0.05) compared to the noninfected group at the same duration of WIRS. Significantly higher oxidative stress documented by iNOS, lipid peroxides, and GSH level was detected in gastric homogenates of the H. pylori-infected group. Proteomic analysis using 2-dimensional electrophoresis showed a decrease of HSP27 and other chaperone proteins. alpha-Tocopherol pretreatment significantly prevented the gastric mucosal damage, caused by WIRS in the presence of H. pylori. alpha-Tocopherol induced HSP27 expression, which was well correlated with downregulation of iNOS mRNA. Conclusively, the presence of H. pylori caused significant deterioration of stress-induced gastric mucosal lesions through increased oxidative stress and thus antioxidant treatment such as alpha-tocopherol protected the gastric injuries.     

胃息肉与幽门螺杆菌感染关系研究

目的探讨胃息肉与幽门螺杆菌（Helicobacter pylori,H.pylori）感染关系。方法对1218例胃息肉同时进行H．pylori检查患者进行回顾性分析,分析胃息肉患者H.pylori感染率、胃息肉部位与H.pylori感染关系、胃息肉病理类型与H.pylori感染关系。结果发现胃息肉Hpylori感染患者532例,Hpylori感染率为43．7％。男性胃息肉患者H.pylori感染率为47．5％（216／455）,女性Hpriori感染率感染率为41．4％（316／763）（P〉0．05）,年龄〈20岁、20～39岁、40—59岁和≥60岁胃息肉H.priori感染率分别为41．7％、44．7％、41．6％和47．2％（P〉0．05）;胃窦胃角息肉H.pylori感染率高于其他部位（胃体、胃底和贲门）（P〈0．05）;炎性和增生性胃息肉H.priori感染率高于胃底腺和腺瘤性息肉（P〈0．05）。结论H.pylori感染可能与部分胃息肉发生有一定关系,需要进一步深入研究胃息肉的发生机制。     

Helicobacter pylori and apoptosis.

In an attempt to understand the diverse effects of infection with Helicobacter pylori on epithelial mucosal mass and consequent clinical outcome, the relationship between H. pylori infection and gastric epithelial cellular turnover has been investigated. Our results indicate that H. pylori increases epithelial cell proliferation and apoptosis in vivo, but that infection with bacteria of the cagA genotype leads to relatively more proliferation than apoptosis. This review explores the causes of the induction of apoptosis in gastric epithelial cells by H. pylori and the consequences of alterations in apoptosis to the maintenance of gastric mucosal homeostasis.     

Role of gastrin in gastric cancerogenesis in Helicobacter pylori infected humans.

Numerous epidemiological studies demonstrated the association between Helicobacter pylori (H. pylori) infection and gastric cancer but the mechanism of the involvement of H. pylori in gastric cancerogenesis remains virtually unknown. This study was designed to determine the seropositivity of H. pylori and cytotoxin associated gene A (CagA), serum gastrin and gastric lumen gastrin levels under basal conditions and following stimulation with histamine in gastric cancer patients and controls. 100 gastric cancer patients aging from 21 to 60 years and 300 gender- and age-adjusted controls hospitalized with non-ulcer dyspepsia (NUD) entered this study. 13C-Urea Breath Test (UBT), serum immunoglobulin (IgG) antibodies to H. pylori and CagA were used to assess the H. pylori infection and serum levels of IL-1beta, IL-8 and TNFalpha were measured by enzyme-linked immunosorbent assay (ELISA) to evaluate the degree of gastric inflammation by H. pylori . Gastrin-17 mRNA and gastrin receptors (CCK(B)) mRNA expression in gastric mucosal samples taken by biopsy from the macroscopically intact fundic and antral mucosa as well as from the gastric tumor was determined using RT-PCR. The overall H. pylori seropositivity in gastric cancer patients at age 21-60 years was about 92%, compared, respectively, to 68%, in controls. A summary odds ratio (OR) for gastric cancer in H. pylori infected patients was about 5.0 . The H. pylori CagA seropositivity in gastric cancer patients was about 58.5% compared to 32.4% in controls, giving the summary OR for gastric cancer in CagA positive patients about 8.0. The prevalence of H. pylori- and H. pylori CagA-seropositivity was significantly higher in cancers than in controls, irrespective of the histology of gastric tumor (intestinal, diffuse or mixed type). Median IL-1beta and IL-8 reached significantly higher values in gastric cancer patients (9.31 and 30.8 pg/ml) than in controls (0.21 and 3.12, respectively). In contrast, median serum gastrin in cancers (as total group) was several folds higher (62.6 pM) than in controls (19.3 pM). Also median luminal gastrin concentration in gastric cancer patients was many folds higher (310 pM) than in controls (20 pM). This study shows for the first time that cancer patients are capable of releasing large amounts of gastrin into the gastric lumen to increase luminal hormone concentration to the level that was recently reported to stimulate the growth of H. pylori. There was no any correlation between plasma gastrin levels and gastric luminal concentration of gastrin suggesting that: 1) luminal gastrin originates from different source than plasma hormone, most probably from the cancer cells, 2) cancer cells are capable of expressing gastrin and releasing it mainly into the gastric juice and 3) the gastric cancer cells are equipped with gastrin-specific (CCK(B)) receptor so they exhibit the self-growth promoting activity in autocrine fashion. This notion is supported by direct detection of gastrin mRNA and gastrin receptor (CCK(B)-receptors) mRNA using RT-PCR in cancer tissue. To our knowledge this is the first study showing an important role of gastrin as self-stimulant of cancer cells in patients infected with H. pylori. Basal and histamine maximally stimulated acid outputs were significantly lower in gastric cancer patients than in controls despite of enhanced gastrin release, particularly in cancer patients and this might reflect the mucosal inflammatory changes (increased serum levels of proinflammtory interleukins - IL-1beta and IL-8), that are known to increase gastrin release. We conclude that: 1) H. pylori infected patients, particularly those showing CagA-seropositivity, are at greatly increased risk of development of gastric cancer, 2) H. pylori-infected cancer patients produce significantly more IL-1beta and IL-8 that might reflect an H. (ABSTRACT TRUNCATED)     

Heat shock protein 70 (HSP70) in gastric adaptation to aspirin in Helicobacter pylori infection.

We have recently shown that adaptation of gastric mucosa to aspirin (ASA) is disturbed in Helicobacter pylori (H. pylori)-infected human stomach, but can be restored by eradication of the bacterium. The aim of this study was 1) to evaluate the influence of H. pylori on expression of heat shock protein 70 (HSP70) during ASA ingestion in these subjects and in mice model and 2) to evaluate, whether altered HSP70 expression might be associated with different adaptation to ASA in H. pylori-positive and eradicated subjects. The gastric mucosal HSP 70 gene expression was determined by quantitative RT-PCR and Western blot and immunohistochemistry during 14 days of ASA ingestion (1 g bid) in the same 8 subjects before and 3 months after successful eradication of H. pylori. In addition, HSP70 mRNA and protein expression were examined in 30 mice without and with H. pylori infection and eradication. During 14 days of ASA treatment, human H. pylori-infected mucosa revealed a decrease of HSP70 expression, while after eradication a higher expression and further increase of HSP70 expression during ASA ingestion were observed. Mice inoculated with H. pylori also exhibited decreased gastric mucosal HSP70 mRNA expression that was restored after eradication therapy. Decreased basal and ASA-induced expression of HSP70 may partly be responsible for impaired gastric adaptation to ASA in H. pylori-positive subjects. We conclude that 1. The HSP70 gene and protein expression is reduced during infection with H. pylori in men and mice and that gastric adaptation to ASA in H. pylori eradicated subjects is accompanied by increased HSP70 expression; 2. It is reasonable to assume that decreased HSP70 expression might contribute to disturbed gastric adaptation in H. pylori infection in humans and 3. The expression of HSP70 plays an important role in the mechanism of gastric adaptation to ASA and that H. pylori infection interferes with this adaptation due to decrease of HSP70 expression in gastric mucosal cells.     

幽门螺杆菌感染者CD4~+ CD25~+调节性T细胞的检测及其相关性分析

目的检测幽门螺杆菌(Helicobacter pylori,H.pylori)感染阳性的胃部疾病患者外周血中CD4+CD25+调节性T细胞(Treg细胞)的百分含量及转化生长因子-β1(transforming growth factor-β1,TGF-β1)的水平,探讨CD4+CD25+调节性T细胞在H.pylori感染中的免疫调节作用及意义。方法采用流式细胞术检测H.pylori感染的慢性浅表性胃炎、胃癌前病变和胃癌患者外周血中CD4+CD25+调节性T细胞的含量、CD4+CD25+T细胞中表达FOXP3的细胞比例;并采用ELISA方法检测H.pylori感染者血清中TGF-β1的含量,无H.pylori感染的患者作为阴性对照。结果 H.pylori感染的患者外周血中CD4+CD25+调节性T细胞的百分含量及TGF-β1的水平较不伴有H.pylori感染的患者显著升高(P<0.05);H.pylori感染的浅表性胃炎、胃癌前病变及胃癌患者外周血中CD4+CD25+T淋巴细胞的百分含量及CD4+CD25+T细胞中表达FOXP3的细胞比例随病变严重程度的进展逐渐升高,差异有统计学意义(P<0.05);H.pylori感染的患者血清中TGF-β1水平也随病变严重程度的进展逐渐升高,差异有统计学意义(P<0.05)。结论 H.pylori感染可增加CD4+CD25+调节性T细胞的含量和TGF-β1的水平;随着病变严重程度的进展,CD4+CD25+调节性T细胞的含量和TGF-β1的水平逐渐升高,CD4+CD25+调节性T细胞百分含量和TGF-β1水平可作为临床判断病情进展的指标。     

Effect of probiotics and triple eradication therapy on the cyclooxygenase (COX)-2 expression, apoptosis, and functional gastric mucosal impairment in Helicobacter pylori-infected Mongolian gerbils

BACKGROUND: Helicobacter pylori infection in Mongolian gerbils is an established experimental model of gastric carcinogenesis that mimics H. pylori-positive patients developing gastric ulcer and gastric cancer, but the effect of probiotic therapy on functional aspects of this infection remains unknown. METHODS: We compared the effects of intragastric inoculation of gerbils with H. pylori strain (cagA+ vacA+, 5 x 10(6) colony forming units/ml) with or without triple therapy including omeprazole, amoxicillin, and tinidazol or probiotic bacteria Lacidofil. Histology of glandular mucosa, the viable H. pylori, and density of H. pylori colonization were evaluated. The gastric blood flow was measured by H2-gas clearance method; the plasma gastrin and gastric luminal somatostatin were determined by RIA and expression of cyclooxygenase (COX)-2 and apoptotic Bax and Bcl-2 proteins were evaluated by Western blot. RESULTS: The gastric H. pylori infection was detected in all animals by histology and H. pylori culture. Basal gastric acid was significantly reduced in H. pylori-infected animals but not in those with triple therapy or Lacidofil. Early lesions were seen already 4 weeks upon H. pylori inoculation and consisted of chronic gastritis and glandular atypia associated with typical regenerative hyperplasia and increased mitotic activity and formation of apoptotic bodies. The H. pylori infection was accompanied by the fall in gastric blood flow, the marked increase in plasma gastrin, the significant fall in gastric somatostatin levels and Bcl-2 protein expression, and the rise in expression of COX-2 and Bax proteins. These mucosal changes were counteracted by the triple therapy and Lacidofil. CONCLUSIONS: H. pylori infection in gerbils, associated with regenerative hyperplasia of glandular structure, results in the suppression of gastric secretion, overexpression of COX-2, and enhancement in apoptosis and impairment of both, gastric blood flow and gastrin-somatostatin link that were reversed by anti-H. pylori triple therapy and attenuated by probiotics.     

Low concentrations of zinc in gastric mucosa are associated with increased severity of Helicobacter pylori-induced inflammation

BACKGROUND: Chronic Helicobacter pylori infection is the most common cause of gastric cancer. H. pylori induces oxidative stress while zinc deficiency results in increased sensitivity to it. In Ecuador, the prevalence of gastric cancer and zinc deficiency are high. We hypothesized that zinc deficiency in Ecuadorian people would cause increased H. pylori-induced inflammation in the gastric mucosa associated with lower tissue zinc concentrations. METHODS: Three hundred and fifty-two patients with dyspepsia underwent endoscopy to obtain gastric mucosa biopsies. Diagnosis of H. pylori infection and its severity, histopathology, mucosal zinc concentration, and inflammation intensity were determined. RESULTS: H. pylori-infected patients with non-atrophic chronic gastritis had lower concentrations of zinc in gastric mucosa than uninfected patients with the same type of gastritis (251.3 +/- 225.3 vs. 426.2 +/- 279.9 ng/mg of protein; p = .016). Considering all patients, the more severe the H. pylori infection, the higher the percentage of subjects with infiltration by polymorphonuclear (PMN) cells (p = .0001). Patients with high PMN infiltration had lower mucosal zinc concentrations than patients with low PMN infiltration (35.2 +/- 20.7 vs. 242.9 +/- 191.8 ng/mg of protein; p = .021). CONCLUSIONS: The degree of inflammation in H. pylori-induced gastritis appears to be modulated by gastric tissue zinc concentrations.     

Effect of Helicobacter pylori infection on the expression of DNA mismatch repair protein

BACKGROUND: Helicobacer pylori infection is a major gastric cancer risk factor. Deficient DNA mismatch repair (MMR) caused by H. pylori may underlie microsatellite instability (MSI) in the gastric epithelium and may represent a major mechanism of mutation accumulation in the gastric mucosa during the early stages of H. pylori-associated gastric carcinogenesis. In this study, we examined the expression of DNA MMR protein (hMLH1 and hMSH2) in patients with chronic H. pylori infection before and after eradication of the infection. MATERIALS AND METHODS: Gastric tissue samples were collected from 60 patients with H. pylori gastritis and peptic ulcer disease before and after eradication of the infection. The DNA MMR protein expression (hMLH1 and hMSH2) was determined by immunohistochemical staining in 60 patients before and after H. pylori eradication. The percentage of epithelial cell nuclei and intensity of staining were then compared in gastric biopsies before and after eradication. RESULTS: The percentage of hMLH1 (76.60 +/- 20.27, 84.82 +/- 12.73, p=.01) and hMSH2 (82.36 +/- 12.86, 88.11 +/- 9.27, p<.05) positive epithelial cells significantly increased in 53 patients who became H. pylori-negative after eradication therapy. However, the intensity of hMLH1 and hMSH2 staining was not significantly different. In those 7 patients, who did not respond to the eradication therapy and were still H. pylori-positive, the percent positivity and intensity of hMLH1 and hMSH2 staining did not change. CONCLUSIONS: The expression of DNA MMR proteins increased in the gastric mucosa after H. pylori eradication, indicating that H. pylori gastritis may be associated with a reduced DNA MMR system during infection. The effect of H. pylori infection on MMR protein expression appears to be at least partially reversible after H. pylori eradication. These data suggest that H. pylori gastritis might lead to a deficiency of DNA MMR in gastric epithelium that may increase the risk of mutation accumulation in the gastric mucosa cells during chronic H. pylori infection.     

Helicobacter pylori encoding the pathogenicity island activates matrix metalloproteinase 1 in gastric epithelial cells via JNK and ERK

Helicobacter pylori colonizes the human gastric epithelium and induces an inflammatory response that is a trigger for gastric carcinogenesis. Matrix metalloproteinases (MMPs) have recently been shown to be up-regulated in gastric epithelial cells infected with H. pylori and might contribute to the pathogenesis of peptic ulcer. The aim of this study was to extend the knowledge about the effect of H. pylori infection on MMP-1 expression by gastric epithelial cells, the kinetics of induction, the pathogenetic properties of the bacterium, and the intracellular signaling pathways required for MMP-1 up-regulation. Expression of MMP-1 was induced more than 10-fold by co-culture of AGS+cells with H. pylori strains carrying the pathogenicity island (PAI). H. pylori strains with mutations in the PAI and a defective type IV secretion system had no effect on MMP-1. Double immunofluorescence revealed strong MMP-1 staining in epithelial cells of gastric biopsies at sites of bacterial attachment. In vitro, MMP-1 is up-regulated by interleukin-1beta and tumor necrosis factor-alpha, but these regulatory mechanisms are not operating in H. pylori infection as shown by inhibitory antibodies. Specific inhibitors of JNK kinase and ERK1/2 kinase were found to suppress the H. pylori-induced MMP-1 expression and activity. AGS cells treated with antisense MMP-1 showed a significantly reduced potential to degrade reconstituted basement membrane. Our results suggest that in gastric epithelial cells, H. pylori up-regulates MMP-1 in a type IV secretion system-dependent manner via JNK and ERK1/2. Induction of MMP-1 is further implicated in complex processes induced by H. pylori, resulting in tissue degradation and remodeling of the gastric mucosa.