Role of γ-glutamyltranspeptidase in the pathogenesis of Helicobacter suis and Helicobacter pylori infections

Helicobacter (H.) suis can colonize the stomach of pigs as well as humans, causing chronic gastritis and other gastric pathological changes including gastric ulceration and mucosa-associated lymphoid tissue (MALT) lymphoma. Recently, a virulence factor of H. suis, gamma-glutamyl transpeptidase (GGT), has been demonstrated to play an important role in the induction of human gastric epithelial cell death and modulation of lymphocyte proliferation depending on glutamine and glutathione catabolism. In the present study, the relevance of GGT in the pathogenesis of H. suis infection was studied in mouse and Mongolian gerbil models. In addition, the relative importance of H. suis GGT was compared with that of the H. pylori GGT. A significant and different contribution of the GGT of H. suis and H. pylori was seen in terms of bacterial colonization, inflammation and the evoked immune response. In contrast to H. pylori Delta ggt strains, H. suis Delta ggt strains were capable of colonizing the stomach at levels comparable to WT strains, although they induced significantly less overall gastric inflammation in mice. This was characterized by lower numbers of T and B cells, and a lower level of epithelial cell proliferation. In general, compared to WT strain infection, ggt mutant strains of H. suis triggered lower levels of Th1 and Th17 signature cytokine expression. A pronounced upregulation of B-lymphocyte chemoattractant CXCL13 was observed, both in animals infected with WT and ggt mutant strains of H. suis. Interestingly, H. suis GGT was shown to affect the glutamine metabolism of gastric epithelium through downregulation of the glutamine transporter ASCT2

The Yin and Yang of regulatory T cells in infectious diseases and avenues to target them

International audienceCD4+CD25+FoxP3+ regulatory T cells (Tregs) are key players for maintaining immune tolerance. Tregs are critical for reducing the inflammation-mediated tissue damage following infection. However, Tregs also suppress protective immune responses to pathogens (including virus, bacteria, parasites and fungi) and vaccines, and enhance pathogen persistence by inhibiting the activation and functions of both innate and adaptive immune cells such as dendritic cells, macrophages, T and B lymphocytes, and by promoting immunosuppressive environment. Therefore, equilibrium in the Treg number and function is important to ensure pathogen clearance and protection from infection-associated immunopathologies. Recent advances in understanding of Treg influence on the outcome of infection opened new avenues to target them. Various small molecules, pharmacological inhibitors, monoclonal antibodies that target Tregs provided proof of concept in experimental models. The field also benefits from advances in other subjects; particularly oncology and autoimmunity, where Treg targeted therapies are exploited in the clinic to a greater extent. The future research should aim at translating this pre-clinical success to human application

In Silico Adjuvant Design and Validation

International audienc

Effect of Different Adjuvants on Protection and Side-Effects Induced by Helicobacter suis Whole-Cell Lysate Vaccination.

Helicobacter suis (H. suis) is a widespread porcine gastric pathogen, which is also of zoonotic importance. The first goal of this study was to investigate the efficacy of several vaccine adjuvants (CpG-DNA, Curdlan, Freund's Complete and Incomplete, Cholera toxin), administered either subcutaneously or intranasally along with H. suis whole-cell lysate, to protect against subsequent H. suis challenge in a BALB/c infection model. Subcutaneous immunization with Freund's complete (FC)/lysate and intranasal immunization with Cholera toxin (CT)/lysate were shown to be the best options for vaccination against H. suis, as determined by the amount of colonizing H. suis bacteria in the stomach, although adverse effects such as post-immunization gastritis/pseudo-pyloric metaplasia and increased mortality were observed, respectively. Therefore, we decided to test alternative strategies, including sublingual vaccine administration, to reduce the unwanted side-effects. A CCR4 antagonist that transiently inhibits the migration of regulatory T cells was also included as a new adjuvant in this second study. Results confirmed that immunization with CT (intranasally or sublingually) is among the most effective vaccination protocols, but increased mortality was still observed. In the groups immunized subcutaneously with FC/lysate and CCR4 antagonist/lysate, a significant protection was observed. Compared to the FC/lysate immunized group, gastric pseudo-pyloric metaplasia was less severe or even absent in the CCR4 antagonist/lysate immunized group. In general, an inverse correlation was observed between IFN-γ, IL-4, IL-17, KC, MIP-2 and LIX mRNA expression and H. suis colonization density, whereas lower IL-10 expression levels were observed in partially protected animals

Comparative virulence of in vitro-cultured primate- and pig-associated Helicobacter suis strains in a BALB/c mouse and a Mongolian gerbil model

Background: Helicobacter suis (H.suis) is the most prevalent gastric non-H.pylori Helicobacter species in humans. This bacterium mainly colonizes the stomach of pigs, but it has also been detected in the stomach of nonhuman primates. The aim of this study was to obtain better insights into potential differences between pig- and primate-associated H.suis strains in virulence and pathogenesis. Materials and Methods: In vitro-isolated H.suis strains obtained from pigs, cynomolgus monkeys (Macaca fascicularis), and rhesus monkeys (Macaca mulatta) were used for intragastric inoculation of BALB/c mice and Mongolian gerbils. Nine weeks and six months later, samples of the stomach of inoculated and control animals were taken for PCR analysis and histopathological examination. Results: The cynomolgus monkey-associated H.suis strain only colonized the stomach of mice, but not of Mongolian gerbils. All other H.suis strains colonized the stomach in both rodent models. In all colonized animals, severe gastric inflammation was induced. Gastric lymphoid follicles and destruction of the antral epithelium were observed in infected gerbils, but not in mice. Infection with both pig- and primate-associated H.suis strains evoked a similar marked Th17 response in mice and gerbils, accompanied by increased CXCL-13 expression levels. Conclusions: Apart from the cynomolgus monkey-associated strain which was unable of colonizing the stomach of Mongolian gerbils, no substantial differences in virulence were found in rodent models between in vitro-cultured pig-associated, cynomolgus monkey-associated and rhesus monkey-associated H. suis strains. The experimental host determines the outcome of the immune response against H. suis infection, rather than the original host

The chemical structure of the CCR4 antagonist.

<p>The CCR4 antagonist AF-399/42018025 is a small chemical molecule with a molecular weight of 565.93. It contains containing six 5 or 6 membered aromatic rings and 3 nitrogen, sulfur, and oxygen atoms. The chemical name of the molecule is 4-(1-benzofuran-2-ylcarbonyl)-1-{5-[4-chlorobenzyl)sulfanyl]-1,3,4-thiadiazol-2-yl}-3-hydroxy-5-(2-thienyl)-1,5-dihydro-2H-pyrrol-2-one [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0131364#pone.0131364.ref005" target="_blank">5</a>].</p

H&E and PAS staining of the fundus, showing mild inflammation and pseudo-pyloric metaplasia.

<p>H&E (A) and PAS staining (B) of the fundus of an animal from the CCR4 antagonist subcutaneously immunized and challenged group, showing mild inflammation and pseudo-pyloric metaplasia (original magnification: 100x).</p

H&E and PAS staining of a normal fundus.

<p>H&E (A) and PAS staining (B) of a normal fundus of an animal from the negative control group (original magnification: 100x).</p