The zoonotic pathogen Helicobacter heilmannii from feline origin : aspects of virulence and gastric colonization

Gastrale Helicobacter species, afkomstig van dieren, kunnen net zoals de typisch humane bacterie Helicobacter pylori de maag van de mens koloniseren en ziekte veroorzaken. Deze zogenaamde niet-H. pylori Helicobacter species (NHPH) werden reeds geassocieerd met gastritis, maagulcera en mucosa-geassocieerde-lymfoïd-weefsel (MALT) lymfomen. Bovendien is het risico op het ontwikkelen van MALT lymfomen hoger na een infectie met gastrale NHPH dan met H. pylori. NHPH omvatten een groep van nauwverwante maar verschillende Helicobacter species die worden teruggevonden in verschillende diersoorten. Zo koloniseren H. felis, H. salomonis, H. bizzozeronii, H. heilmannii, H. cynogastricus en H. baculiformis de maag van hond en kat, terwijl H. suis voornamelijk wordt teruggevonden in varkens. Gastrale NHPH zijn bijzonder moeilijk te kweken in het laboratorium, waardoor er wereldwijd maar weinig in vitro isolaten beschikbaar zijn. H. heilmannii werd in 2011 voor het eerst succesvol geïsoleerd uit kattenmagen en in vitro in cultuur gebracht. Dit doctoraatsonderzoek had tot doel om een beter inzicht te verwerven in de pathogenese van maaginfecties met H. heilmannii, om de mogelijke virulentiefactoren van H. heilmannii in kaart te brengen en om het repertoire aan buitenste membraan-proteïnen van deze kiem te vergelijken met deze van andere gastrale Helicobacter species

Voorkomen van gastrale helicobacters in speeksel en feces van honden en katten

Gastric Helicobacter species are present in the stomach of more than 50% of dogs and cats. These bacteria have also been associated with severe gastric pathologies in humans. The route of transmission between pets and from pets to humans remains unclear, but it has been suggested that direct contact might play a role. In order to determine whether transfer might occur through contact with saliva and feces, the presence of Helicobacter DNA was determined in oral swabs and feces of dogs and cats. In this study, 155 saliva samples and141 fecal samples were collected from 106 dogs and 58 cats. From 22 dogs, a gastric biopsy sample was also collected, aiming to investigate whether the same Helicobacter species found in saliva and/or feces could also be detected in the stomach of these animals. All samples were screened for the presence of DNA from gastric Helicobacter species associated with dogs and cats, using species-specific qPCRs and amplicon sequencing. In 43% of the dogs and 41% of the cats, one or more positive samples were found. Helicobacter DNA was detected in 29 % of the saliva samples, 37 % of the fecal samples and 41% of the gastric biopsies. Several dogs and cats were infected with more than one Helicobacter species. No clear correlation between the presence of a Helicobacter species in the stomach of dogs and the detection of this species in their saliva and/or feces was shown. Moreover, the present study did not allow to determine whether the detected Helicobacter DNA originated from viable Helicobacter bacteria, highlighting the need of additional studies in order to determine the importance of saliva and feces in transfer of these gastric Helicobacter species between animals and from animals to humans

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

Diversity in bacterium-host interactions within the species Helicobacter heilmannii sensu stricto

Helicobacter (H.) heilmannii sensu stricto (s.s.) is a zoonotic bacterium that naturally colonizes the stomach of dogs and cats. In humans, this microorganism has been associated with gastritis, peptic ulcer disease and mucosa associated lymphoid tissue (MALT) lymphoma. Little information is available about the pathogenesis of H. heilmannii s.s. infections in humans and it is unknown whether differences in virulence exist within this species. Therefore, a Mongolian gerbil model was used to study bacterium-host interactions of 9 H. heilmannii s.s. strains. The colonization ability of the strains, the intensity of gastritis and gene expression of various inflammatory cytokines in the stomach were determined at 9 weeks after experimental infection. The induction of an antrum-dominant chronic active gastritis with formation of lymphocytic aggregates was shown for 7 strains. High-level antral colonization was seen for 4 strains, while colonization of 4 other strains was more restricted and one strain was not detected in the stomach at 9 weeks post infection. All strains inducing a chronic active gastritis caused an up-regulation of the pro-inflammatory cytokine IL-1 beta in the antrum. A reduced antral expression of H+/K+ ATPase was seen in the stomach after infection with 3 highly colonizing strains and 2 highly colonizing strains caused an increased gastrin expression in the fundus. In none of the H. heilmannii s.s.-infected groups, IFN-gamma expression was up-regulated. This study demonstrates diversity in bacterium-host interactions within the species H. heilmannii s.s. and that the pathogenesis of gastric infections with this microorganism is not identical to that of an H. pylori infection

Oral glutathione supplementation drastically reduces Helicobacter-induced gastric pathologies

Helicobacter (H.) suis causes gastric pathologies in both pigs and humans. Very little is known on the metabolism of this bacterium and its impact on the host. In this study, we have revealed the importance of the glutamate-generating metabolism, as shown by a complete depletion of glutamine (Gln) in the medium during H. suis culture. Besides Gln, H. suis can also convert glutathione (GSH) to glutamate, and both reactions are catalyzed by the H. suis gamma-glutamyltranspeptidase (GGT). Both for H. pylori and H. suis, it has been hypothesized that the degradation of Gln and GSH may lead to a deficiency for the host, possibly initiating or promoting several pathologies. Therefore the in vivo effect of oral supplementation with Gln and GSH was assessed. Oral supplementation with Gln was shown to temper H. suis induced gastritis and epithelial (hyper) proliferation in Mongolian gerbils. Astonishingly, supplementation of the feed with GSH, another GGT substrate, resulted in inflammation and epithelial proliferation levels returning to baseline levels of uninfected controls. This indicates that Gln and GSH supplementation may help reducing tissue damage caused by Helicobacter infection in both humans and pigs, highlighting their potential as a supportive therapy during and after Helicobacter eradication therapy

In silico proteomic and phylogenetic analysis of the outer membrane protein repertoire of gastric Helicobacter species

Helicobacter (H.) pylori is an important risk factor for gastric malignancies worldwide. Its outer membrane proteome takes an important role in colonization of the human gastric mucosa. However, in zoonotic non-H. pylori helicobacters (NHPHs) also associated with human gastric disease, the composition of the outer membrane (OM) proteome and its relative contribution to disease remain largely unknown. By means of a comprehensive survey of the diversity and distribution of predicted outer membrane proteins (OMPs) identified in all known gastric Helicobacter species with fully annotated genome sequences, we found genus- and species-specific families known or thought to be implicated in virulence. Hop adhesins, part of the Helicobacter-specific family 13 (Hop, Hor and Horn) were restricted to the gastric species H. pylori, H. cetorum and H. acinonychis. Hof proteins (family 33) were putative adhesins with predicted Occ- or MOMP-family like 18-stranded beta-barrels. They were found to be widespread amongst all gastric Helicobacter species only sporadically detected in enterohepatic Helicobacter species. These latter are other members within the genus Helicobacter, although ecologically and genetically distinct. LpxR, a lipopolysaccharide remodeling factor, was also detected in all gastric Helicobacter species but lacking as well from the enterohepatic species H. cinaedi, H. equorum and H. hepaticus. In conclusion, our systemic survey of Helicobacter OMPs points to species and infection-site specific members that are interesting candidates for future virulence and colonization studies.Peer reviewe

The role of confined placental mosaicism in fetal growth restriction:A retrospective cohort study

Objective: To evaluate which cytogenetic characteristics of confined placental mosaicism (CPM) detected in the first trimester chorionic villi and/or placentas in terms of chromosome aberration, cell lineage involved and trisomy origin will lead to fetal growth restriction and low birthweight. Methods: Cohort study using routinely collected perinatal data and cytogenetic data of non-invasive prenatal testing, the first trimester chorionic villi sampling and postnatal placentas. Results: 215 CPM cases were found. Fetal growth restriction (FGR) and low birthweight below the 10 th percentile (BW &lt; p10) were seen in 34.0% and 23.1%, respectively. Excluding cases of trisomy 16, 29.1% showed FGR and 17.9% had a BW &lt; p10. The highest rate of FGR and BW &lt; p10 was found in CPM type 3, but differences with type 1 and 2 were not significant. FGR and BW &lt; p10 were significantly more often observed in cases with meiotic trisomies. Conclusion: There is an association between CPM and FGR and BW &lt; p10. This association is not restricted to trisomy 16, neither to CPM type 3, nor to CPM involving a meiotic trisomy. Pregnancies with all CPM types and origins should be considered to be at increased risk of FGR and low BW &lt; p10. A close prenatal fetal monitoring is indicated in all cases of CPM.</p

Colonization capacity of Helicobacter heilmannii sensu stricto strains in a Mongolian gerbil model

Helicobacter (H.) heilmannii sensu stricto (s.s.) is a zoonotic bacterium that naturally colonizes the stomach of dogs and cats. In humans, this microorganism has been associated with gastritis, peptic ulcer disease and mucosa associated lymphoid tissue (MALT) lymphoma. For determination of the colonization capacity of nine H. heilmannii s.s. strains, all originally isolated from the gastric mucosa of cats, Mongolian gerbils were intragastrically inoculated with these bacteria. At nine weeks after inoculation, the animals were euthanized and samples from the fundus and antrum of the stomach and from the duodenum were taken for histological examination and quantitative PCR analysis. Histology showed induction of a chronic active gastritis with formation of lymphocytic aggregates for seven H. heilmannii isolates. The lymphocytic aggregates were predominantly located in the antrum of the stomach. Two H. heilmannii strains (ASB 7.1 and ASB 9.4) did not cause inflammation. Detection of H. heilmannii with quantitative PCR revealed high-level colonization of strains ASB 1.4, ASB 2.1, ASB 3.2 and ASB 6.3, predominantly in the antrum. In contrast, colonization of strains ASB 11.2, ASB 13.1 and ASB 14.1 was more restricted while ASB 7.1 and ASB 9.4 were not detected in the stomach. These results indicate that H. heilmannii s.s. strains may differ in virulence. In an ongoing study, the host response to the nine H. heilmannii s.s. strains is further characterized by measuring the expression of several cytokines in the stomach of the experimentally infected gerbils