Helicobacter pylori impairs DNA mismatch repair in gastric epithelial cells

BACKGROUND & AIMS

Helicobacter pylori infection is a major gastric cancer risk factor. H. pylori gastritis occurs more frequently in individuals with microsatellite instability-positive than those with microsatellite instability-negative gastric cancers, raising the possibility that H. pylori infection affects DNA mismatch repair (MMR). The aim of this study was to determine the effect of H. pylori on the expression of DNA MMR proteins and RNA in gastric epithelial cells.

METHODS

Gastric cancer cell lines were cocultured with H. pylori, bacterial extracts, and Campylobacter jejuni or Escherichia coli. MutS (hMSH2 and hMSH6) and MutL (hMLH1, hPMS2, and hPMS1) DNA MMR protein and RNA levels were determined.

RESULTS

All cell lines examined showed decreased levels of MutS and MutL DNA MMR proteins in a dose-dependent manner after coculture with H. pylori strains. The reduction in DNA MMR protein levels was caused by heat-sensitive H. pylori products. The levels of DNA MMR proteins were affected by C. jejuni but not by E. coli. RNA levels of hMSH2 and hMSH6 were also reduced after exposure to H. pylori.

CONCLUSIONS

H. pylori infection of gastric epithelial cells leads to a decrease in DNA MMR proteins that is at least in part related to an H. pylori-induced decrease in messenger RNA levels of repair genes. These data suggest that H. pylori infection might lead to a deficiency of DNA MMR in gastric epithelial cells that may increase the risk of mutation accumulation in gastric mucosa cells and the risk of gastric cancer during chronic H. pylori infection.

Levofloxacin-based triple therapy vs. quadruple therapy in second-line Helicobacter pylori treatment: a randomized trial

BACKGROUND

Levofloxacin has been shown to be effective in Helicobacter pylori eradication. Two 10-day levofloxacin-based triple therapies were compared with standard 7- and 14-day quadruple regimens in second-line treatment.

METHODS

Two hundred and eighty consecutive patients who failed to respond to standard triple therapy (clarithromycin, amoxicillin, rabeprazole) were randomly assigned to four groups: (1) levofloxacin 500 mg o.d., amoxicillin 1 g b.d., rabeprazole 20 mg b.d. for 10 days (LAR, n = 70); (2) levofloxacin 500 mg o.d., tinidazole 500 mg b.d., rabeprazole 20 mg b.d. for 10 days (LTR, n = 70); (3) tetracycline 500 mg q.d.s., metronidazole 500 mg t.d.s., bismuth salt 120 mg q.d.s., rabeprazole 20 mg b.d. for 7 days (7TMBR, n = 70); and (4) for 14 days (14TMBR, n = 70). Helicobacter pylori status and side-effects were assessed 6 weeks after treatment.

RESULTS

The eradication rate was 94% in the LAR group and 90% in the LTR group in both intention-to-treat and per protocol analyses. Helicobacter pylori eradication was achieved in 63 and 69% of the 7TMBR group and in 69 and 80% of the 14TMBR group in intention-to-treat and per protocol analysis, respectively. Side-effects were significantly lower in the LAR and LTR groups than in the 14TMBR group.

CONCLUSION

Ten-day levofloxacin-based therapies are better than standard quadruple regimens as second-line option for H. pylori eradication.

Screening of gene expression profiles in gastric epithelial cells induced by Helicobacter pylori using microarray analysis

BACKGROUND

H. pylori infection is a major risk factor in gastric cancer development. The availability of cDNA microarrays creates the unprecedented opportunity to examine simultaneously dynamic changes of multiple pathways affected by H. pylori infection.

AIM

In this study we examined broad patterns of gene expression induced by H. pylori in the gastric cancer cell line 1739-CRL AGS cells in culture using the U95A microarray.

METHODS

H. pylori were cocultured with AGS cells for 4, 12, 24 and 48 h. Total RNA was extracted and after labelling was used for detection of genes represented in the human U95A microarray set. Data analyses were performed using GeneChip and CLUSFAVOR software.

RESULTS

Nearly 6000 genes present in the array were expressed by AGS cells. We report approximately 200 genes that showed the most marked changes. Our studies confirm the up-regulation of c-jun, jun-B, c-fos and cyclin D1 by H. pylori. We report for the first time the induction of the serine threonine kinase pim-1 and ATF3 by H. pylori infection of AGS cells.

CONCLUSIONS

In this microarray analysis of gene expression induced by H. pylori in gastric epithelial cells, we identified a large number of unsuspected genes affected by H. pylori. Further, we show that unsupervised hierarchical cluster analysis can provide useful insight into the possible contribution of genes in specific pathways, based on their profile of expression.

The symptomatic effects of intra-articular administration of hylan G-F 20 on osteoarthritis of the hip: clinical data of 6 months follow-up

Hip osteoarthritis (OA) is usually managed with systemic treatments such as nonsteroidal anti-inflammatory drugs (NSAIDs) and/or symptomatic slow-acting drugs. Unfortunately, many patients either cannot tolerate NSAIDs or suffer serious, even fatal, NSAID-induced side effects, predominantly gastrointestinal ulceration and bleeding. Viscosupplementation, which aims to restore physiological and rheological features of the synovial fluid, is a well-accepted therapeutic option in knee OA patients, but limited data exist in the literature about its potential benefit for the treatment of hip OA. The purpose of this study is to observe the effects of hylan G-F 20 administered through ultrasound (US)-guided intra-articular (IA) injections in patients with symptomatic hip OA. We treated 30 patients with symptomatic hip OA. Under US guidance, 7 patients received one injection, 21 patients had two injections, and 2 patients received three injections, each with 2 ml of hylan G-F 20. Lequesne index, VAS scale of hip pain, and NSAID consumption were evaluated at baseline as well as 2 and 6 months after the beginning of the treatment. No systemic adverse events were observed. Lequesne index, VAS pain score, and NSAID consumption showed a reduction that was statistically significant to the baseline. The present observation suggests the potentiality for the safety and efficacy of hylan G-F 20 injected under US guidance in patients with symptomatic hip OA. Further controlled studies are needed.

Epidemiology of pertussis in Italy: Disease trends over the last century

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Alterations of DNA mismatch repair proteins and microsatellite instability levels in gastric cancer cell lines

Alterations in DNA mismatch repair (MMR) proteins result in microsatellite instability (MSI), increased mutation accumulation at target genes and cancer development. About one-third of gastric cancers display high-level microsatellite instability (MSI-High) and low-level microsatellite instability (MSI-Low) is frequently detected. To determine whether variations in the levels of MMR proteins or mutations in the main DNA MMR genes are associated with MSI-Low and MSI-High in gastric cancer cell lines, the MSI status (MSI-High, MSI-Low or MS-Stable (MSS)) of 14 gastric cancer lines was determined using multiple clone analysis with a panel of five microsatellite markers. Protein levels of hMLH1, hMSH2, hMSH6, hPMS2 and hPMS1 were determined by Western blot. Sequence analysis of hMLH1 and hMSH2 was performed and the methylation status of the hMLH1 promoter was examined. The cell lines SNU1 and SNU638 showed MSI-High, decreased to essentially absent hMLH1 and hPMS2 and reduced hPMS1 and hMSH6 protein levels. The hMLH1 promoter region was hypermethylated in SNU638 cells. The MKN28, MKN87, KATOIII and SNU601 cell lines showed MSI-Low. The MMR protein levels of cells with MSI-Low status was similar to the levels detected in MSS cells. A marked decrease in the expression levels of MutL MMR proteins (hMLH1, hPMS2 and hPMS1) is associated with high levels of MSI mutations in gastric cancer cells. Gastric cancer cell lines with MSI-Low status do not show significant changes in the levels of the main DNA MMR proteins or mutations in the DNA mismatch repair genes hMSH2 and hMLH1. These well-characterized gastric cancer cell lines are a valuable resource to further our understanding of DNA MMR deficiency in cancer development, progression and prognosis.

Helicobacter pylori and extragastric diseases--other Helicobacters

Reports on Helicobacter pylori and extragastric diseases have almost doubled this year compared with last year, bearing witness to the persistent scientific interest in this branch of Helicobacter-related pathology. Data belong increasingly to the area of vascular medicine, as well as hematology, dermatology, pediatrics and other fields. Unfortunately, these studies show overall controversial results, due to the impact of several confounding factors, and to the difficulty of recruiting homogeneous patient populations. Furthermore, many studies continue to be conducted on Helicobacter species other than H. pylori, focusing on animal models of gastroenterological illnesses which may retain strong similarities with human diseases. In this paper, taxonomy, detection and characterisation of Helicobacter spp. will be reviewed, together with the most important data issued this year on other Helicobacters and animal models.

Helicobacter pylori and extragastric diseases -- other helicobacters

The role of Helicobacter pylori infection is explored in more and more extragastric diseases without definite proof in most of the studies, except possibly some hematologic diseases. In cardiovascular diseases, including stroke, the presence of CagA positive strains may be involved. The possible role of helicobacters in hepatobiliary diseases goes beyond that of H. pylori to involve enterohepatic helicobacters. New Helicobacter species are regularly described and molecular methods are developed to improve their detection. Helicobacter felis remains the major species to be used in animal models of Helicobacter infection.

Characterization of gene expression profile in rat Kupffer cells stimulated with IFN-alpha or IFN-gamma

BACKGROUND AND AIM

Kupffer cells are intrasinusoidal space located macrophages with phagocytic capacity. Interferons are cytokines with antiviral, antiproliferative and immunomodulatory activities which may influence the activity of Kupffer cells. Aim of this study was to evaluate Kupffer cell gene expression after interferon-alpha or interferon-gamma stimulation in order to investigate a link between these cytokines and macrophage activation.

METHODS

Rat Kupffer cells were cultured for 24 h and divided into three groups: unstimulated; stimulated with interferon-alpha and stimulated with interferon-gamma. After 8 h stimulation total RNA was extracted and processed according to Affymetrix protocols and hybridised on R34A microarray gene set. Data analyses was performed using Microarray Analysis Suite 5.0 software. Genes showing remarkably different expression in microarray analysis were confirmed by real-time PCR.

RESULTS

Nearly 4000 out of the 8800 genes represented in the array were expressed by Kupffer cells. Among these, interferon-alpha up-regulates 91 genes by over two-fold (antiviral, antigen processing and presentation, and tumour suppressor/proapoptotic genes) and down-regulates 72 genes by 50% or more. Interferon-gamma up-regulates 70 genes by over two-fold and down-regulates 78 genes by 50% or more. Most of the genes induced by interferon-alpha are also induced by interferon-gamma. Down-regulated genes include growth factors and genes involved in cell cycle/proliferation. Real-time PCR confirms the results of the array.

CONCLUSION

Interferons directly target rat Kupffer cells and are involved in the regulation of a wide variety of genes. Their expression profile shed light onto molecular mechanism of Kupffer cells activation in specific pathways such as antiviral and antitumour processes.

Treatment of H. pylori infection: a review

Helicobacter pylori infection has been indicated as the main pathogenic factor in the development of chronic gastritis, peptic ulcer disease, and gastric malignancies. Although the vast majority of infected subjects do not carry but a mild, asymptomatic gastritis, still there are some cases in which the eradication of the infection appears mandatory. This review addresses current anti-Helicobacter regimens and pharmacological resources, and highlights the pros and cons of each of them, according to the most recent and reliable clinical trials. Also, basic recommendations are given, regarding treatment choice in the event of the failure of a first or second line eradicating strategy, and about the implementation of standard regimens with newer antibacterial devices as probiotics.

Proteomic changes and molecular effects associated with Cr(III) and Cr(VI) treatments on germinating kiwifruit pollen

The present study is aimed at identifying molecular changes elicited by Cr(III) and Cr(VI) on germinating kiwifruit pollen. To address this question, comparative proteomic and DNA laddering analyses were performed. While no genotoxic effect was detected, a number of proteins whose accumulation levels were altered by treatments were identified. In particular, the upregulation of some proteins involved in the scavenging response, cell redox homeostasis and lipid synthesis could be interpreted as an oxidative stress response induced by Cr treatment. The strong reduction of two proteins involved in mitochondrial oxidative phosphorylation and a decline in ATP levels were also observed. The decrease of pollen energy availability could be one of the causes of the severe inhibition of the pollen germination observed upon exposure to both Cr(III) and Cr(VI). Finally, proteomic and biochemical data indicate proteasome impairment: the consequential accumulation of misfolded/damaged proteins could be an important molecular mechanism of Cr(III) toxicity in pollen.

Delta13CO2 excretion and expression of dyspeptic symptoms in patients evaluated for Helicobacter pylori infection by [13C] urea breath test

Previous studies showed that either the urease activity possessed by H. pylori and the bacterial load may influence the results of the [13C] urea breath test. However, the correlation between urease activity and dyspepsia is unclear. The aim of our study was to evaluate whether the urease activity of the gastroduodenal tract may influence the severity of dyspeptic symptoms. In all, 2520 dyspeptic patients (1109 men, 1411 women; mean age 47 +/- 16 years) without gastroesophageal reflux disease, diabetes, vascular disorders, liver and biliary tract diseases, and tumors of the gastrointestinal tract and with a normal appearing abdominal ultrasonography were enrolled. All these patients underwent a [13C] urea breath test and filled out a questionnaire on dyspeptic symptoms. Subjects were divided in five different groups according to delta over baseline (DOB) values (group 1 < 3.5, group 2 = 3.5-6; group 3 = 6.1-11, group 4 = 11.1-23, group 5 > 23.1). The prevalence and intensity of dyspeptic symptoms were compared among groups. In all, 1688 patients (67%, 928 females and 760 males; mean age 48 +/- 15 years) were H. pylori-positive. The chi-squared test and analysis of variance showed increase of frequency and intensity of each dyspeptic symptom according to DOB values. In conclusion, Dyspepsia may parallel gastric urease activity. However, whether higher DOB values are related to higher bacterial load or, alternatively, to the presence of particular H. pylori strains able to produce larger amounts of urease is uncertain.

Exitianus obscurinervis (Hemiptera: Cicadellidae), a new experimental vector of Spiroplasma kunkelii

"Corn stunt" caused by the mollicute Spiroplasma kunkelii (Whitcomb) is potentially one of the most severe diseases affecting the corn (Zea mays L.) crop in the Americas, and the leafhopper Dalbulus maidis (DeLong & Wolcott) is considered its most important vector. However, other insects seen quite frequently in corn crops might well be its vectors in Argentina To identify any leafhoppers species other than D. maidis that can transmit S. kunkelii, transmission assays were conducted, using individuals of Exitianus obscurinervis (Stål) collected in field and reared under controlled conditions. S. kunkelii was transmitted to corn plants by E. obscurinervis. The pathogen was transmitted to seven of the 11 plants, which showed characteristic corn stunt symptoms, and the presence of the pathogen was confirmed by DAS-ELISA. The presence of S. kunkelii in the E. obscurinervis individuals used in transmission experiments was confirmed by polymerase chain reaction and electron microscopy. The current study shows the existence of a new experimental vector of S. kunkelii, the leafhopper E. obscurinervis, which acquired spiroplasmas from infected plants and inoculated it to healthy plants.

Presence of Dalbulus maidis (Hemiptera: Cicadellidae) and of Spiroplasma kunkelii in the temperate region of Argentina

"Corn stunt" is one of the main corn (Zea mays L.) diseases in the Americas and Dalbulus maidis (DeLong & Wolcott) is the key vector of the pathogen Spiroplasma kunkelii Whitcomb. In Argentina, the corn-producing area is in the temperate region, where vector and pathogen prevalence levels are unknown. In this study, the prevalence and distribution of D. maidis and S. kunkelii in the temperate region of Argentina and D. maidis overwintering ability in this region were determined. Surveys were conducted in 2005-2006 and 2006-2007 seasons to determine D. maidis and S. kunkelii presence, and in winter 2006 to determine the vector overwintering ability. The highest S. kunkelii prevalence and incidence levels were found in the transition area from the temperate to the subtropical region, related to the highest D. maidis prevalence and insects sampled per location. D. maidis adults were found in volunteer corn plants and spontaneous vegetation in autumn and winter months, which were inoculative for the pathogen S. kunkelii. This overwintering ability was related to detection of D. maidis insects in corn crops at early growth stages in the following growing season. This work emphasizes that corn stunt disease is present in the temperate region of Argentina, and this highlights the need to develop proper agronomic practices like monitoring insect vector populations and controlling voluntary plants. This study also indicates that further research is needed to understand the potential yield reduction caused by this pathogen on symptomless plants and population dynamics of the insect vector.

Sacroileitis and peripheral arthropathy associated with ulcerative colitis: effect of infliximab on both articular and intestinal symptoms

Infliximab has been proven to be an effective therapy in a miscellany of rheumatic diseases and has been approved for the treatment of moderate-to-severe Crohn's disease with an inadequate response to conventional therapy and for the management of enterocutaneous fistulas. Data about the role of infliximab in ulcerative colitis are still controversial. Here, we report a case of a patient with sacroileitis and peripheral arthropathy associated with left-sided ulcerative colitis who achieved a sustained clinical remission after infliximab therapy.

Role of sucralfate in gastrointestinal diseases

Sucralfate is a cytoprotective drug widely used in clinical practice to prevent or treat several gastrointestinal diseases such as gastro-esophageal reflux, gastritis, peptic ulcer, stress ulcer and dyspepsia. Sucralfate is a safe and well tolerated drug, as demonstrated by the quite complete lack of side effects and it is, for this reason, one of the most important therapeutic choices in the management of acid related diseases during pregnancy. Moreover, sucralfate has recently been shown to be useful in non-acid related gastrointestinal disease as well. In fact, sucralfate has also been administered topically in patients with radiation-induced mucosal procto-sigmoiditis or ulcerative colitis with surprising results. The drug is actually able to form a physical barrier between epithelium and damaging agents (-bile salts, drugs, refluxate...). Moreover, sucralfate increases the local levels of fibroblast growth factors and induces a rise in the mucosal concentration of prostaglandins which are considered important factors in mucosal healing. The aim of this paper is to describe the current and probably forthcoming uses of sucralfate in the field of gastrointestinal disorders. Moreover, we investigate the role of sucralfate as a reliable means to prevent the occurrence of reflux-like symptoms after Helicobacter pylori eradication and in the management of Helicobacter pylori negative patients affected by non-ulcer dyspepsia.