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Helicobacter pylori induces an antimicrobial response in rhesus macaques in a cag pathogenicity island-dependent manner.

ABSTRACT: We used the rhesus macaque model to study the effects of the cag pathogenicity island (cag PAI) on the H pylori host-pathogen interaction.H pylori-specific pathogen-free (SPF) monkeys were experimentally challenged with wild-type (WT) H pylori strain J166 (J166WT, n = 4) or its cag PAI isogenic knockout (J166Deltacag PAI, n = 4). Animals underwent endoscopy before and 1, 4, 8, and 13 weeks after challenge. Gastric biopsies were collected for quantitative culture, histopathology, and host gene expression analysis.Quantitative cultures showed that all experimentally challenged animals were infected with J166WT or its isogenic J166Deltacag PAI. Histopathology demonstrated that inflammation and expansion of the lamina propria were attenuated in animals infected with J166Deltacag PAI compared with J166WT. Microarray analysis showed that of the 119 up-regulated genes in the J166WT-infected animals, several encode innate antimicrobial effector proteins, including elafin, siderocalin, DMBT1, DUOX2, and several novel paralogues of human-beta defensin-2. Quantitative RT-PCR confirmed that high-level induction of each of these genes depended on the presence of the cag PAI. Immunohistochemistry confirmed increased human-beta defensin-2 epithelial cell staining in animals challenged with J166WT compared with either J166Deltacag PAI-challenged or uninfected control animals.We propose that one function of the cag PAI is to induce an antimicrobial host response that may serve to increase the competitive advantage of H pylori in the gastric niche and could even provide a protective benefit to the host.

SUBMITTER: Hornsby MJ

PROVIDER: S-EPMC2386437 | biostudies-literature | 2008 Apr

REPOSITORIES: biostudies-literature

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Helicobacter pylori induces an antimicrobial response in rhesus macaques in a cag pathogenicity island-dependent manner.

Hornsby Michael J MJ Huff Jennifer L JL Kays Robert J RJ Canfield Don R DR Bevins Charles L CL Solnick Jay V JV

Gastroenterology 20080111 4

<h4>Background & aims</h4>We used the rhesus macaque model to study the effects of the cag pathogenicity island (cag PAI) on the H pylori host-pathogen interaction.<h4>Methods</h4>H pylori-specific pathogen-free (SPF) monkeys were experimentally challenged with wild-type (WT) H pylori strain J166 (J166WT, n = 4) or its cag PAI isogenic knockout (J166Deltacag PAI, n = 4). Animals underwent endoscopy before and 1, 4, 8, and 13 weeks after challenge. Gastric biopsies were collected for quantitative ...[more]

PMID: 18395086

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Project description:We used the rhesus macaque model to study the effects of the cag pathogenicity island (cag PAI) on the H. pylori host-pathogen interaction. Specific pathogen free (SPF) monkeys with no prior exposure to H. pylori were experimentally challenged with wild type (WT) H. pylori strain J166 (N=4) or its cag PAI isogenic knockout (KO, N=4). Animals underwent endoscopy before and 1, 4, 8, and 13 wks after challenge. Gastric biopsies were collected for quantitative culture, histopathology, and host gene expression. Quantitative cultures showed that all experimentally challenged animals were infected with WT H. pylori or its isogenic cag PAI KO. Histopathology demonstrated that inflammation and expansion of the lamina propria were attenuated in animals infected with KO compared to WT. Microarray analysis was performed on challenged animals before and 1 and 13 wks after challenge, and on unchallenged control animals (N=4). Of the 119 up-regulated genes in the WT-infected animals, several encode innate antimicrobial; effector proteins, including elafin, siderocalin, DMBT, DUOX2, and several novel paralogues of human defensin-2. Quantitative RT-PCR analysis showed that high level induction of each of these genes was dependent upon the presence of the cag PAI. Immunohistochemistry confirmed increased defensin epithelial cell staining in animals challenged with WT H. pylori compared to either KO-challenged or uninfected control animals. We propose that one function of the cag PAI is to induce an antimicrobial host response that serves to increase the competitive advantage of H. pylori in the gastric niche. Experiment Overall Design: Twelve male and female rhesus macaques (Macaca mulatta) housed at the California National Primate Research Center (CNPRC) were hand raised by nursery staff to obtain Specific Pathogen (Helicobacter pylori) Free (SPF) experimental animals. At six months of age the animals were documented to be uninfected with H. pylori by serology, histology, and cultures of gastric biopsies using methods reported previously (Solnick et al., 1999). Two experimental groups of four SPF animals were challenged with either wild type (WT) H. pylori J166 or an isogenic PAI knockout (KO). A third group of four SPF animals served as uninoculated controls. Monkeys were housed indoors in separate cages throughout the duration of the experiment. All experiments were approved by the Research Advisory Committee of the CNPRC and the Institutional Animal Care and Use Committee at the University of California.Antrum and corpus stomach biopsies from rhesus macaques infected with wild type Helicobacter pylori J166, isogenic cag-PAI knockout strain, or mock infected were pooled. Biopsies were taken prior to bacterial inoculation and at 1 and 13 weeks post infection. Control biopsies were taken according to the same time line. Four animals were used for each experimental condition.

Project description:Several genes including the cagA in the cag pathogenicity island (cag PAI) of Helicobacter pylori are thought to be associated with the gastroduodenal diseases and hence variation in the genetic structure of the cag PAI might be responsible for different clinical outcomes. Our study was undertaken to characterize the cag PAI of H. pylori strains from duodenal ulcer (DU) patients and asymptomatic or non-ulcer dyspepsia (NUD/AV) subjects from Kolkata, India. Strains isolated from 52 individuals (30DU and 22NUD/AV) were analyzed by PCR using 83 different primers for the entire cag PAI and also by dot-blot hybridization. Unlike H. pylori strains isolated from other parts of India, 82.6% of the strains used in this study had intact cag PAI, 9.6% had partially deleted cag PAI, and 7.7% of the strains lacked the entire cag PAI. Dot-blot hybridization yielded positive signals in 100% and 93.8% of PCR-negative strains for HP0522-523 and HP0532-HP0534 genes, respectively. An intact cagA promoter region was also detected in all cagA-positive strains. Furthermore, the expression of cagA mRNA was confirmed by RT-PCR for the representative strains from both DU and NUD/AV subjects indicating the active cagA promoter regions of these strains. A total of 66.7% of Kolkata strains produced a ?390-bp shorter amplicon than the standard strain 26695 for the HP0527 gene, homologue of virB10. However, sequence analyses confirmed that the deletion did not alter the reading frame of the gene, and mRNA transcripts were detected by RT-PCR analysis. The strains isolated from DU and NUD/AV express CagA protein and possess a functional type IV secretion system, as revealed by Western blot analyses. Interestingly, no significant differences in cag PAI genetic structure were found between DU and NUD/AV individuals suggesting that other bacterial virulence factors, host susceptibility, and environmental determinants also influence the disease outcome at least in certain geographical locations.

Dataset Information

Helicobacter pylori induces an antimicrobial response in rhesus macaques in a cag pathogenicity island-dependent manner.

Publications

Helicobacter pylori induces an antimicrobial response in rhesus macaques in a cag pathogenicity island-dependent manner.

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