Markus Gerhard | Technische Universität München (original) (raw)

Papers by Markus Gerhard

International Journal of Molecular Sciences

Helicobacter pylori infection induces a number of pro-inflammatory signaling pathways contributin... more Helicobacter pylori infection induces a number of pro-inflammatory signaling pathways contributing to gastric inflammation and carcinogenesis and has been identified as a major risk factor for the development of gastric cancer (GC). Janus kinase-signal transducer and activator of transcription (JAK-STAT) signaling mediates immune regulatory processes, including tumor-driven immune escape. Programmed death ligand 1 (PD-L1) expressed on gastric epithelium can suppress the immune system by shutting down T cell effector function. In a human cohort of subjects with gastric lesions and GC analyzed by proteomics, STAT1 increased along the cascade of progression of precancerous gastric lesions to GC and was further associated with a poor prognosis of GC (Hazard Ratio (95% confidence interval): 2.34 (1.04–5.30)). We observed that STAT1 was activated in human H. pylori-positive gastritis, while in GC, STAT1, and its target gene, PD-L1, were significantly elevated. To confirm the dependency of...

Cell Reports, 2021

T cell immunity is crucial for the control of SARS-CoV-2 infections and has been widely studied o... more T cell immunity is crucial for the control of SARS-CoV-2 infections and has been widely studied on a quantitative level. However, quality of responses, in particular of CD8+ T cells, has only been marginally investigated so far. Here, we isolate T cell receptor (TCR) repertoires specific for immunodominant SARS-CoV-2 epitopes restricted to common Human Leucocyte Antigen (HLA) class I molecules in convalescent individuals. SARS-CoV-2-specific CD8+ T cells are detected up to twelve months from infection. TCR repertoires are diverse, with heterogeneous functional avidity and cytotoxicity towards virus-infected cells, as demonstrated for TCR-engineered T cells. High TCR functionality correlates with gene signatures that, remarkably, could be retrieved for each epitope:HLA combination analyzed. Overall, our data demonstrate that polyclonal and highly functional CD8+ TCRs – classical features of protective immunity - are recruited upon mild SARS-CoV-2 infection, providing tools to assess the quality and to potentially restore functional CD8+ T cell immunity.

Viszeralmedizin 2021 Gemeinsame Jahrestagung Deutsche Gesellschaft für Gastroenterologie, Verdauungs- und Stoffwechselkrankheiten (DGVS), Sektion Endoskopie der DGVS, Deutsche Gesellschaft für Allgemein und Viszeralchirurgie (DGAV), 2021

Carcinogenesis, 2018

Ring finger protein 43 (RNF43) is an E3 ubiquitin ligase that has been described to be frequently... more Ring finger protein 43 (RNF43) is an E3 ubiquitin ligase that has been described to be frequently mutated in gastrointestinal cancers. RNF43 downregulation was associated with distant metastasis, TNM stage and poorer survival in patients with gastric and colorectal cancers. Functional analysis has shown that overexpressed RNF43 negatively regulates Wnt signalling by ubiquitinating Frizzled receptors and targeting them for degradation and by sequestering T-cell factor 4 (TCF4) to the nuclear membrane, thereby inhibiting Wnt-mediated transcription. In the stomach, RNF43 overexpression was shown to impair stem-like properties and to be negatively correlated with expression of Wnt-target genes. In this study, we show that RNF43 knockdown enhances the tumourigenic potential of gastric and colorectal cancer cell lines in vitro and in vivo. Thus, loss of RNF43 leads to increased proliferation and anchorage-independent growth as well as increased invasive capacity. In a xenograft model, RNF43 depletion enhanced tumour growth. Furthermore, we established two mouse models in which mutations in the RING domain of RNF43 were introduced. In the intestine and colon, loss of Rnf43 did not induce changes in epithelial architecture or proliferation. In contrast, in the stomach, thickening of the mucosa, hyperplasia and cellular atypia were observed in these mice. Notably, this was independent of elevated Wnt signalling. Together, our results show that RNF43 plays a tumour suppressive role in gastric and colorectal cancer cells and that the loss of its function alters gastric tissue homeostasis in vivo.

Frontiers in cellular and infection microbiology, 2018

Eradication of has been found to be effective for gastric cancer prevention, but uncertainties re... more Eradication of has been found to be effective for gastric cancer prevention, but uncertainties remain about the possible adverse consequences such as the potential microbial dysbiosis. In our study, we investigated the association between gut microbiota and -related gastric lesions in 47 subjects by deep sequencing of microbial 16S ribosomal RNA (rRNA) gene in fecal samples. The dominant phyla in fecal samples were , and with average relative abundances of 54.77, 31.37 and 12.91%, respectively. Microbial diversity analysis showed that observed species and Shannon index were increased in subjects with past or current infection compared with negative subjects. As for the differential bacteria, the average relative abundance of was found to significantly decrease from negative (66.16%) to past infection group (33.01%, = 0.007), as well as from normal (76.49%) to gastritis (56.04%) and metaplasia subjects (46.83%, = 0.027). For and , the average relative abundances showed elevated trend...

Scientific reports, May 18, 2017

The performance of diagnostic tests in intervention trials of Helicobacter pylori (H.pylori) erad... more The performance of diagnostic tests in intervention trials of Helicobacter pylori (H.pylori) eradication is crucial, since even minor inaccuracies can have major impact. To determine the cut-off point for (13)C-urea breath test ((13)C-UBT) and to assess if it can be further optimized by serologic testing, mathematic modeling, histopathology and serologic validation were applied. A finite mixture model (FMM) was developed in 21,857 subjects, and an independent validation by modified Giemsa staining was conducted in 300 selected subjects. H.pylori status was determined using recomLine H.pylori assay in 2,113 subjects with a borderline (13)C-UBT results. The delta over baseline-value (DOB) of 3.8 was an optimal cut-off point by a FMM in modelling dataset, which was further validated as the most appropriate cut-off point by Giemsa staining (sensitivity = 94.53%, specificity = 92.93%). In the borderline population, 1,468 subjects were determined as H.pylori positive by recomLine (69.5%)....

Nature microbiology, Jan 17, 2016

Helicobacter pylori specifically colonizes the human gastric epithelium and is the major causativ... more Helicobacter pylori specifically colonizes the human gastric epithelium and is the major causative agent for ulcer disease and gastric cancer development. Here, we identify members of the carcinoembryonic antigen-related cell adhesion molecule (CEACAM) family as receptors of H. pylori and show that HopQ is the surface-exposed adhesin that specifically binds human CEACAM1, CEACAM3, CEACAM5 and CEACAM6. HopQ-CEACAM binding is glycan-independent and targeted to the N-domain. H. pylori binding induces CEACAM1-mediated signalling, and the HopQ-CEACAM1 interaction enables translocation of the virulence factor CagA into host cells and enhances the release of pro-inflammatory mediators such as interleukin-8. Based on the crystal structure of HopQ, we found that a β-hairpin insertion (HopQ-ID) in HopQ's extracellular 3+4 helix bundle domain is important for CEACAM binding. A peptide derived from this domain competitively inhibits HopQ-mediated activation of the Cag virulence pathway, as ...

PLOS ONE, 2016

The Dsb protein family is responsible for introducing disulfide bonds into nascent proteins in pr... more The Dsb protein family is responsible for introducing disulfide bonds into nascent proteins in prokaryotes, stabilizing the structure of many proteins. Helicobacter pylori HP0231 is a Dsb-like protein, shown to catalyze disulfide bond formation and to participate in redox homeostasis. Notably, many H. pylori virulence factors are stabilized by the formation of disulfide bonds. By employing H. pylori HP0231 deficient strains we analyzed the effect of lack of this bacterial protein on the functionality of virulence factors containing putative disulfide bonds. The lack of H. pylori HP0231 impaired CagA translocation into gastric epithelial cells and reduced VacA-induced cellular vacuolation. Moreover, H. pylori HP0231 deficient bacteria were not able to colonize the gastric mucosa of mice, probably due to compromised motility. Together, our data demonstrate an essential function for H. pylori HP0231 in gastric colonization and proper function of bacterial virulence factors related to gastric pathology.

Jundishapur Journal of Microbiology, 2015

Background: Helicobacter pylori infection and related diseases outcome are mediated by a complex ... more Background: Helicobacter pylori infection and related diseases outcome are mediated by a complex interplay between bacterial, host and environmental factors. Several distinct virulence factors of H. pylori have been shown to be associated with different clinical outcomes. Here we focused on vacA and cagA genotypes of H. pylori strains isolated from patients with gastric disorder. Objectives: The aim of this study was to determine the frequency of two toxins and genotypes of VacA toxin in patients referred to a central hospital in the west of Iran (Imam Reza hospital, Kermanshah) during 2011-2012. Patients and Methods: Samples were collected from patients infected with H. pylori. Gastric biopsy specimens from the stomach antrum and corpus were cultured. PCR analysis was performed for genotyping H. pylori vacA and cagA genes. Results: Helicobacter pylori was isolated from 48% (96/200) of patients with gastroduodenal disorders. In 81/96 (84%) cases, the cagA gene was present. Among different genotypes of vacA, two s1m2 and s2m2 genotypes were dominant with frequency of 39.5% and 50%, respectively. The frequency of the s1m1 genotype was 7.2% (7/96), which is much lower than elsewhere. H. pylori isolates with positive results for cagA gene and vacA s1m2 genotypes showed statistically significant correlation with peptic ulcer (s1m2 13/34 [38.2%] P = 0.003). However, isolates of H. pylori infection with cagA gene and vacA s2m2 genotypes were significantly associated with development of gastritis (s2m2 41/42 [97.6%] P = 0.000). Conclusions: About 90% of H. pylori strains potentially contained vacA s2m2 and s1m2 genotypes. Infection with H. pylori strain containing the cagA gene or the vacA s1m1 and s1m2 genotypes was associated with increased incidence of peptic ulcer disease (PUD).

Diseases, 2015

Since the first evidence demonstrating the dramatically high incidence of H. pylori infection and... more Since the first evidence demonstrating the dramatically high incidence of H. pylori infection and the subsequent medical challenges it incurs, health management of H. pylori infection has been a high priority for health authorities worldwide. Despite a decreasing rate of infection in western countries, prevalence of H. pylori infection in developing and in some industrial countries is still very high. Whereas treatment and vaccination against H. pylori is a contemporary issue in medical communities, selective treatment and prior high-throughput screening of the subject population is a major concern of health organizations. So far, diagnostic tests are either elaborative and require relatively advanced medical care infrastructure or they do not fulfill the criteria recommended by the Maastricht IV/Florence consensus report. In this review, in light of recent scientific studies, we highlight current and possible future approaches for the diagnosis of H. pylori. We point out that novel non-invasive tests may not only cover the requirements of gold standard methods in H. pylori detection but also offer the potential for risk stratification of infection in a high throughput manner.

Journal of immunology (Baltimore, Md. : 1950), 2014

Infection with the gram-negative bacterium Helicobacter pylori is the most prevalent chronic bact... more Infection with the gram-negative bacterium Helicobacter pylori is the most prevalent chronic bacterial infection, affecting ∼50% of the world's population, and is the main risk factor of gastric cancer. The proinflammatory cytokine IL-1β plays a crucial role in the development of gastric tumors and polymorphisms in the IL-1 gene cluster leading to increased IL-1β production have been associated with increased risk for gastric cancer. To be active, pro-IL-1β must be cleaved by the inflammasome, an intracellular multiprotein complex implicated in physiological and pathological inflammation. Recently, H. pylori was postulated to activate the inflammasome in murine bone marrow-derived dendritic cells; however, the molecular mechanisms as well as the bacterial virulence factor acting as signal 2 activating the inflammasome remain elusive. In this study, we analyzed the inflammasome complex regulating IL-1β upon H. pylori infection as well as the molecular mechanisms involved. Our res...

Cancer research, 2001

Helicobacter pylori has been assigned as a class I carcinogen because of its relation to gastric ... more Helicobacter pylori has been assigned as a class I carcinogen because of its relation to gastric adenocarcinoma. Chronic H. pylori infection may lead to severe gastritis, glandular atrophy (AT), and intestinal metaplasia (IM). Strains secreting the vacuolating toxin VacA and producing the cytotoxin-associated antigen CagA (type 1 strains), as well as the blood group antigen binding adhesin (BabA) targeting Lewis(b) antigens, have been associated previously with distal gastric adenocarcinoma (M. Gerhard et al., Proc. Natl. Acad. Sci. USA, 96: 12778-12783, 1999) and may therefore also be related to lesions preceding gastric cancer. Antral and corpus biopsies were collected from 451 patients; 151 were H. pylori positive, as determined by PCR. Gastric biopsies were histologically evaluated for activity of gastritis (G0-G3, granulocyte infiltration), chronicity of gastritis (L1-L3, lymphocyte infiltration), and the presence of IM and/or AT according to the Sydney classification. Simultan...

American Journal of Physiology-Gastrointestinal and Liver Physiology, 2002

Gastric Helicobacter pylori infection may lead to multifocal atrophic corpus gastritis associated... more Gastric Helicobacter pylori infection may lead to multifocal atrophic corpus gastritis associated with loss of epithelial cells as well as glandular structures. The current work investigated H. pylori effects on cell death of isolated, nontransformed rat parietal cells (PC). Highly enriched rat PC (>97%) were isolated from gastric mucosa and cultured in serum-free medium over 24 h. The cells were cocultured over 8 h with cytotoxin-associated immunodominant protein (cagA)+/vacuolating toxin (vacA)+or with cagA−/vacA−H. pylori laboratory strains and also with H. pylori mutants deleted in several genes of the cag pathogenicity island. Staphylococcus aureus or Campylobacter jejuni were used as controls. Apoptosis was determined by terminal deoxynucleotidyl transferase dUTP nick-end labeling staining and electron microscopy. Interleukin (IL)-8 and cytokine-induced neutrophil chemoattractant (CINC)-1 secretion was measured by ELISA. Activation of nuclear factor-κB (NF-κB) was studied i...

PLoS One, 2010

Amongst the most severe clinical outcomes of lifelong infections with Helicobacter pylori is the ... more Amongst the most severe clinical outcomes of lifelong infections with Helicobacter pylori is the development of peptic ulcers and gastric adenocarcinoma-diseases often associated with an increase of regulatory T cells. Understanding H. pylori-driven regulation of T cells is therefore of crucial clinical importance. Several studies have defined mammalian microRNAs as key regulators of the immune system and of carcinogenic processes. Hence, we aimed here to identify H. pylori-regulated miRNAs, mainly in human T cells. MicroRNA profiling of non-infected and infected human T cells revealed H. pylori infection triggers miR-155 expression in vitro and in vivo. By using single and double H. pylori mutants and the corresponding purified enzymes, the bacterial vacuolating toxin A (VacA) and c-glutamyl transpeptidase (GGT) plus lipopolysaccharide (LPS) tested positive for their ability to regulate miR-155 and Foxp3 expression in human lymphocytes; the latter being considered as the master regulator and marker of regulatory T cells. RNAi-mediated knockdown (KD) of the Foxp3 transcription factor in T cells abolished miR-155 expression. Using adenylate cyclase inhibitors, the miR-155 induction cascade was shown to be dependent on the second messenger cyclic adenosine monophosphate (cAMP). Furthermore, we found that miR-155 directly targets the protein kinase A inhibitor a (PKIa) mRNA in its 39UTR, indicative of a positive feedback mechanism on the cAMP pathway. Taken together, our study describes, in the context of an H. pylori infection, a direct link between Foxp3 and miR-155 in human T cells and highlights the significance of cAMP in this miR-155 induction cascade.

PLoS ONE, 2013

Helicobacter bilis (H. bilis) infection is associated with cases of inflammatory bowel Disease, t... more Helicobacter bilis (H. bilis) infection is associated with cases of inflammatory bowel Disease, thyphlocolitis, hepatitis and cholecystitis. However, little is known about the bacterial virulence determinants or the molecular mechanisms involved. Recently, H. bilis γ-glutamyltranspeptidase (HBgGT) was shown to be a virulence factor decreasing host cell viability. Bacterial gGTs play a key role in synthesis and degradation of glutathione and enables the bacteria to utilize extracellular glutamine and glutathione as sources of glutamate. gGT-mediated loss of cell viability has so far been linked to DNA damage via oxidative stress, but the signaling cascades involved herein have not been described. In this study, we identified enhanced ROS production induced by HBgGT as a central factor involved in the activation of the oxidative stress response cascades, which finally activate CREB, AP-1 and NF-κB in H. bilis infected colon cancer cells. IL-8, an important pro-inflammatory chemokine that is a common downstream target of these transcription factors, was up-regulated upon H. bilis infection in an HBgGT dependent manner. Moreover, the induction of these signaling responses and inflammatory cytokine production in host cells could be linked to HBgGTmediated glutamine deprivation. This study implicates for the first time HBgGT as an important regulator of signaling cascades regulating inflammation in H. bilis infected host epithelial cells that could be responsible for induction of inflammatory disorders by the bacterium.

Zeitschrift für Gastroenterologie, 2009

Helicobacter pylori (H.p.) is the most widespread bacterial infection, affecting half of the worl... more Helicobacter pylori (H.p.) is the most widespread bacterial infection, affecting half of the world population and causing peptic ulcers and gastric cancer. Although big efforts have been initiated to develop a vaccine against this pathogen none of these experimental approaches led to successful results in human studies and thus failed to generate an approved vaccine in humans. It is unclear if this is due to the antigens used, the vaccine formulations tested to induce protective immunity or the laboratory infection models applied. Our group described a virulence factor of H. pylori, the H.p. gamma-glutmyltranspeptidase (HPgGT) that inhibits the proliferation of T-cells and thus prevents the generation of an effective immune response. We used HPgGT in an experimental mouse infection model for a novel vaccination approach. Immunization with this antigen induces strong antibody responses, which blocks its enzymatic activity, thereby counteracting the immunosuppressive activity of HPgGT. Different formulations and routes of application were tested, revealing a need for mucosal immunization. As HPgGT is a secreted protein, HPgGT specific T-cells can hardly target the pathogen. Therefore we combine this protein with outer membrane proteins to induce protective T-cell responses. In infection experiments this vaccination lead to a substantial decrease of bacterial colonization in the stomach, making this new approach of a “liberating vaccine“ a promising candidate for a new immunization strategy.

Zeitschrift für Gastroenterologie, 2009

The Journal of Infectious Diseases, 2005

Background. Infection of the gastric mucosa with Helicobacter pylori leads to increased apoptosis... more Background. Infection of the gastric mucosa with Helicobacter pylori leads to increased apoptosis. Cytokines and receptors of the tumor necrosis factor (TNF) family are known to be involved in this process. The role that the death-inducing TNF-a-related apoptosis-inducing ligand (TRAIL) and its receptors play, in the context of H. pylori infection, is unknown. Methods. In 74 H. pylori-infected and 51 H. pylori-uninfected gastric antral biopsy specimens, levels of TRAIL mRNA and TRAIL receptor mRNA were determined quantitatively by TaqMan reverse-transcriptase polymerase chain reaction. Recombinant TRAIL-induced apoptosis was measured in human and rat gastric epithelial cells by end-labeling of DNA with fluorescein-dTUP and by fluorescence-activated cell sorter analysis. Results. In patients infected with cagA + /vacAs1 + H. pylori strains, expression of TRAIL and the proapoptotic receptors TRAIL-R1 and-R2 was down-regulated, whereas expression of the antiapoptotic receptors TRAIL-R3 and-R4 was up-regulated. Furthermore, expression of TRAIL and TRAIL-R1 and-R2 correlated inversely with the severity of gastric inflammation. Significant apoptosis of isolated human gastric epithelial cells and highly enriched rat parietal and chief cells was induced by 100 ng/mL TRAIL. Conclusions. Down-regulation of the TRAIL system, in the context of H. pylori infection, may limit exaggerated apoptosis of gastric epithelial cells and destruction of tissue and, therefore, may enable H. pylori to maintain its niche.

Journal of Allergy and Clinical Immunology, 2009

Journal of Allergy and Clinical Immunology, 2011

Based on a recent positional cloning approach, it was claimed that the collagen 29A1 gene (COL29A... more Based on a recent positional cloning approach, it was claimed that the collagen 29A1 gene (COL29A1), which encodes an epidermal collagen, represents a major risk gene for eczema underlying a previously reported linkage to chromosome 3q21. However, thus far, not a single replication attempt has been published, and no definitive functional data have been provided. We aimed to determine whether COL29A1 polymorphisms contribute to eczema susceptibility and whether COL29A1 expression is altered in eczema. We investigated the reported association of COL29A1 variants with eczema, subtypes of eczema, and eczema-related traits in 5 independent and large study populations comprehensively phenotyped for allergic diseases: a set of 1687 German patients with eczema and 2387 population control subjects, a collection of 274 German families with eczema-diseases children, a cross-sectional population of German children (n = 3099), the Swedish population-based birth cohort Children Allergy and Milieu in Stockholm, an Epidemiologic Study (BAMSE) (n = 2033), and the European cross-sectional Prevention of Allergy-Risk Factors for Sensitization Related to Farming and Anthroposophic Lifestyle (PARSIFAL) study (n = 3113). An additional set of 19 COL29A1 coding single nucleotide polymorphisms was analyzed in BAMSE and PARSIFAL. COL29A1 expression was investigated by using in situ hybridization. We found no evidence for a relationship between COL29A1 polymorphisms and eczema. The equivalence test rejected the hypothesis of association even excluding small effects. In situ hybridization carried out on biopsy specimens from lesional and nonlesional skin of patients with eczema and from healthy control subjects did not show any differences in the cellular distribution pattern of COL29A1 expression at the mRNA level. Our results suggest that COL29A1 is unlikely to contain genetic variants that have a major effect on eczema or atopy susceptibility.

International Journal of Molecular Sciences

Helicobacter pylori infection induces a number of pro-inflammatory signaling pathways contributin... more Helicobacter pylori infection induces a number of pro-inflammatory signaling pathways contributing to gastric inflammation and carcinogenesis and has been identified as a major risk factor for the development of gastric cancer (GC). Janus kinase-signal transducer and activator of transcription (JAK-STAT) signaling mediates immune regulatory processes, including tumor-driven immune escape. Programmed death ligand 1 (PD-L1) expressed on gastric epithelium can suppress the immune system by shutting down T cell effector function. In a human cohort of subjects with gastric lesions and GC analyzed by proteomics, STAT1 increased along the cascade of progression of precancerous gastric lesions to GC and was further associated with a poor prognosis of GC (Hazard Ratio (95% confidence interval): 2.34 (1.04–5.30)). We observed that STAT1 was activated in human H. pylori-positive gastritis, while in GC, STAT1, and its target gene, PD-L1, were significantly elevated. To confirm the dependency of...

Cell Reports, 2021

T cell immunity is crucial for the control of SARS-CoV-2 infections and has been widely studied o... more T cell immunity is crucial for the control of SARS-CoV-2 infections and has been widely studied on a quantitative level. However, quality of responses, in particular of CD8+ T cells, has only been marginally investigated so far. Here, we isolate T cell receptor (TCR) repertoires specific for immunodominant SARS-CoV-2 epitopes restricted to common Human Leucocyte Antigen (HLA) class I molecules in convalescent individuals. SARS-CoV-2-specific CD8+ T cells are detected up to twelve months from infection. TCR repertoires are diverse, with heterogeneous functional avidity and cytotoxicity towards virus-infected cells, as demonstrated for TCR-engineered T cells. High TCR functionality correlates with gene signatures that, remarkably, could be retrieved for each epitope:HLA combination analyzed. Overall, our data demonstrate that polyclonal and highly functional CD8+ TCRs – classical features of protective immunity - are recruited upon mild SARS-CoV-2 infection, providing tools to assess the quality and to potentially restore functional CD8+ T cell immunity.

Viszeralmedizin 2021 Gemeinsame Jahrestagung Deutsche Gesellschaft für Gastroenterologie, Verdauungs- und Stoffwechselkrankheiten (DGVS), Sektion Endoskopie der DGVS, Deutsche Gesellschaft für Allgemein und Viszeralchirurgie (DGAV), 2021

Carcinogenesis, 2018

Ring finger protein 43 (RNF43) is an E3 ubiquitin ligase that has been described to be frequently... more Ring finger protein 43 (RNF43) is an E3 ubiquitin ligase that has been described to be frequently mutated in gastrointestinal cancers. RNF43 downregulation was associated with distant metastasis, TNM stage and poorer survival in patients with gastric and colorectal cancers. Functional analysis has shown that overexpressed RNF43 negatively regulates Wnt signalling by ubiquitinating Frizzled receptors and targeting them for degradation and by sequestering T-cell factor 4 (TCF4) to the nuclear membrane, thereby inhibiting Wnt-mediated transcription. In the stomach, RNF43 overexpression was shown to impair stem-like properties and to be negatively correlated with expression of Wnt-target genes. In this study, we show that RNF43 knockdown enhances the tumourigenic potential of gastric and colorectal cancer cell lines in vitro and in vivo. Thus, loss of RNF43 leads to increased proliferation and anchorage-independent growth as well as increased invasive capacity. In a xenograft model, RNF43 depletion enhanced tumour growth. Furthermore, we established two mouse models in which mutations in the RING domain of RNF43 were introduced. In the intestine and colon, loss of Rnf43 did not induce changes in epithelial architecture or proliferation. In contrast, in the stomach, thickening of the mucosa, hyperplasia and cellular atypia were observed in these mice. Notably, this was independent of elevated Wnt signalling. Together, our results show that RNF43 plays a tumour suppressive role in gastric and colorectal cancer cells and that the loss of its function alters gastric tissue homeostasis in vivo.

Frontiers in cellular and infection microbiology, 2018

Eradication of has been found to be effective for gastric cancer prevention, but uncertainties re... more Eradication of has been found to be effective for gastric cancer prevention, but uncertainties remain about the possible adverse consequences such as the potential microbial dysbiosis. In our study, we investigated the association between gut microbiota and -related gastric lesions in 47 subjects by deep sequencing of microbial 16S ribosomal RNA (rRNA) gene in fecal samples. The dominant phyla in fecal samples were , and with average relative abundances of 54.77, 31.37 and 12.91%, respectively. Microbial diversity analysis showed that observed species and Shannon index were increased in subjects with past or current infection compared with negative subjects. As for the differential bacteria, the average relative abundance of was found to significantly decrease from negative (66.16%) to past infection group (33.01%, = 0.007), as well as from normal (76.49%) to gastritis (56.04%) and metaplasia subjects (46.83%, = 0.027). For and , the average relative abundances showed elevated trend...

Scientific reports, May 18, 2017

The performance of diagnostic tests in intervention trials of Helicobacter pylori (H.pylori) erad... more The performance of diagnostic tests in intervention trials of Helicobacter pylori (H.pylori) eradication is crucial, since even minor inaccuracies can have major impact. To determine the cut-off point for (13)C-urea breath test ((13)C-UBT) and to assess if it can be further optimized by serologic testing, mathematic modeling, histopathology and serologic validation were applied. A finite mixture model (FMM) was developed in 21,857 subjects, and an independent validation by modified Giemsa staining was conducted in 300 selected subjects. H.pylori status was determined using recomLine H.pylori assay in 2,113 subjects with a borderline (13)C-UBT results. The delta over baseline-value (DOB) of 3.8 was an optimal cut-off point by a FMM in modelling dataset, which was further validated as the most appropriate cut-off point by Giemsa staining (sensitivity = 94.53%, specificity = 92.93%). In the borderline population, 1,468 subjects were determined as H.pylori positive by recomLine (69.5%)....

Nature microbiology, Jan 17, 2016

Helicobacter pylori specifically colonizes the human gastric epithelium and is the major causativ... more Helicobacter pylori specifically colonizes the human gastric epithelium and is the major causative agent for ulcer disease and gastric cancer development. Here, we identify members of the carcinoembryonic antigen-related cell adhesion molecule (CEACAM) family as receptors of H. pylori and show that HopQ is the surface-exposed adhesin that specifically binds human CEACAM1, CEACAM3, CEACAM5 and CEACAM6. HopQ-CEACAM binding is glycan-independent and targeted to the N-domain. H. pylori binding induces CEACAM1-mediated signalling, and the HopQ-CEACAM1 interaction enables translocation of the virulence factor CagA into host cells and enhances the release of pro-inflammatory mediators such as interleukin-8. Based on the crystal structure of HopQ, we found that a β-hairpin insertion (HopQ-ID) in HopQ's extracellular 3+4 helix bundle domain is important for CEACAM binding. A peptide derived from this domain competitively inhibits HopQ-mediated activation of the Cag virulence pathway, as ...

PLOS ONE, 2016

The Dsb protein family is responsible for introducing disulfide bonds into nascent proteins in pr... more The Dsb protein family is responsible for introducing disulfide bonds into nascent proteins in prokaryotes, stabilizing the structure of many proteins. Helicobacter pylori HP0231 is a Dsb-like protein, shown to catalyze disulfide bond formation and to participate in redox homeostasis. Notably, many H. pylori virulence factors are stabilized by the formation of disulfide bonds. By employing H. pylori HP0231 deficient strains we analyzed the effect of lack of this bacterial protein on the functionality of virulence factors containing putative disulfide bonds. The lack of H. pylori HP0231 impaired CagA translocation into gastric epithelial cells and reduced VacA-induced cellular vacuolation. Moreover, H. pylori HP0231 deficient bacteria were not able to colonize the gastric mucosa of mice, probably due to compromised motility. Together, our data demonstrate an essential function for H. pylori HP0231 in gastric colonization and proper function of bacterial virulence factors related to gastric pathology.

Jundishapur Journal of Microbiology, 2015

Background: Helicobacter pylori infection and related diseases outcome are mediated by a complex ... more Background: Helicobacter pylori infection and related diseases outcome are mediated by a complex interplay between bacterial, host and environmental factors. Several distinct virulence factors of H. pylori have been shown to be associated with different clinical outcomes. Here we focused on vacA and cagA genotypes of H. pylori strains isolated from patients with gastric disorder. Objectives: The aim of this study was to determine the frequency of two toxins and genotypes of VacA toxin in patients referred to a central hospital in the west of Iran (Imam Reza hospital, Kermanshah) during 2011-2012. Patients and Methods: Samples were collected from patients infected with H. pylori. Gastric biopsy specimens from the stomach antrum and corpus were cultured. PCR analysis was performed for genotyping H. pylori vacA and cagA genes. Results: Helicobacter pylori was isolated from 48% (96/200) of patients with gastroduodenal disorders. In 81/96 (84%) cases, the cagA gene was present. Among different genotypes of vacA, two s1m2 and s2m2 genotypes were dominant with frequency of 39.5% and 50%, respectively. The frequency of the s1m1 genotype was 7.2% (7/96), which is much lower than elsewhere. H. pylori isolates with positive results for cagA gene and vacA s1m2 genotypes showed statistically significant correlation with peptic ulcer (s1m2 13/34 [38.2%] P = 0.003). However, isolates of H. pylori infection with cagA gene and vacA s2m2 genotypes were significantly associated with development of gastritis (s2m2 41/42 [97.6%] P = 0.000). Conclusions: About 90% of H. pylori strains potentially contained vacA s2m2 and s1m2 genotypes. Infection with H. pylori strain containing the cagA gene or the vacA s1m1 and s1m2 genotypes was associated with increased incidence of peptic ulcer disease (PUD).

Diseases, 2015

Since the first evidence demonstrating the dramatically high incidence of H. pylori infection and... more Since the first evidence demonstrating the dramatically high incidence of H. pylori infection and the subsequent medical challenges it incurs, health management of H. pylori infection has been a high priority for health authorities worldwide. Despite a decreasing rate of infection in western countries, prevalence of H. pylori infection in developing and in some industrial countries is still very high. Whereas treatment and vaccination against H. pylori is a contemporary issue in medical communities, selective treatment and prior high-throughput screening of the subject population is a major concern of health organizations. So far, diagnostic tests are either elaborative and require relatively advanced medical care infrastructure or they do not fulfill the criteria recommended by the Maastricht IV/Florence consensus report. In this review, in light of recent scientific studies, we highlight current and possible future approaches for the diagnosis of H. pylori. We point out that novel non-invasive tests may not only cover the requirements of gold standard methods in H. pylori detection but also offer the potential for risk stratification of infection in a high throughput manner.

Journal of immunology (Baltimore, Md. : 1950), 2014

Infection with the gram-negative bacterium Helicobacter pylori is the most prevalent chronic bact... more Infection with the gram-negative bacterium Helicobacter pylori is the most prevalent chronic bacterial infection, affecting ∼50% of the world's population, and is the main risk factor of gastric cancer. The proinflammatory cytokine IL-1β plays a crucial role in the development of gastric tumors and polymorphisms in the IL-1 gene cluster leading to increased IL-1β production have been associated with increased risk for gastric cancer. To be active, pro-IL-1β must be cleaved by the inflammasome, an intracellular multiprotein complex implicated in physiological and pathological inflammation. Recently, H. pylori was postulated to activate the inflammasome in murine bone marrow-derived dendritic cells; however, the molecular mechanisms as well as the bacterial virulence factor acting as signal 2 activating the inflammasome remain elusive. In this study, we analyzed the inflammasome complex regulating IL-1β upon H. pylori infection as well as the molecular mechanisms involved. Our res...

Cancer research, 2001

Helicobacter pylori has been assigned as a class I carcinogen because of its relation to gastric ... more Helicobacter pylori has been assigned as a class I carcinogen because of its relation to gastric adenocarcinoma. Chronic H. pylori infection may lead to severe gastritis, glandular atrophy (AT), and intestinal metaplasia (IM). Strains secreting the vacuolating toxin VacA and producing the cytotoxin-associated antigen CagA (type 1 strains), as well as the blood group antigen binding adhesin (BabA) targeting Lewis(b) antigens, have been associated previously with distal gastric adenocarcinoma (M. Gerhard et al., Proc. Natl. Acad. Sci. USA, 96: 12778-12783, 1999) and may therefore also be related to lesions preceding gastric cancer. Antral and corpus biopsies were collected from 451 patients; 151 were H. pylori positive, as determined by PCR. Gastric biopsies were histologically evaluated for activity of gastritis (G0-G3, granulocyte infiltration), chronicity of gastritis (L1-L3, lymphocyte infiltration), and the presence of IM and/or AT according to the Sydney classification. Simultan...

American Journal of Physiology-Gastrointestinal and Liver Physiology, 2002

Gastric Helicobacter pylori infection may lead to multifocal atrophic corpus gastritis associated... more Gastric Helicobacter pylori infection may lead to multifocal atrophic corpus gastritis associated with loss of epithelial cells as well as glandular structures. The current work investigated H. pylori effects on cell death of isolated, nontransformed rat parietal cells (PC). Highly enriched rat PC (>97%) were isolated from gastric mucosa and cultured in serum-free medium over 24 h. The cells were cocultured over 8 h with cytotoxin-associated immunodominant protein (cagA)+/vacuolating toxin (vacA)+or with cagA−/vacA−H. pylori laboratory strains and also with H. pylori mutants deleted in several genes of the cag pathogenicity island. Staphylococcus aureus or Campylobacter jejuni were used as controls. Apoptosis was determined by terminal deoxynucleotidyl transferase dUTP nick-end labeling staining and electron microscopy. Interleukin (IL)-8 and cytokine-induced neutrophil chemoattractant (CINC)-1 secretion was measured by ELISA. Activation of nuclear factor-κB (NF-κB) was studied i...

PLoS One, 2010

Amongst the most severe clinical outcomes of lifelong infections with Helicobacter pylori is the ... more Amongst the most severe clinical outcomes of lifelong infections with Helicobacter pylori is the development of peptic ulcers and gastric adenocarcinoma-diseases often associated with an increase of regulatory T cells. Understanding H. pylori-driven regulation of T cells is therefore of crucial clinical importance. Several studies have defined mammalian microRNAs as key regulators of the immune system and of carcinogenic processes. Hence, we aimed here to identify H. pylori-regulated miRNAs, mainly in human T cells. MicroRNA profiling of non-infected and infected human T cells revealed H. pylori infection triggers miR-155 expression in vitro and in vivo. By using single and double H. pylori mutants and the corresponding purified enzymes, the bacterial vacuolating toxin A (VacA) and c-glutamyl transpeptidase (GGT) plus lipopolysaccharide (LPS) tested positive for their ability to regulate miR-155 and Foxp3 expression in human lymphocytes; the latter being considered as the master regulator and marker of regulatory T cells. RNAi-mediated knockdown (KD) of the Foxp3 transcription factor in T cells abolished miR-155 expression. Using adenylate cyclase inhibitors, the miR-155 induction cascade was shown to be dependent on the second messenger cyclic adenosine monophosphate (cAMP). Furthermore, we found that miR-155 directly targets the protein kinase A inhibitor a (PKIa) mRNA in its 39UTR, indicative of a positive feedback mechanism on the cAMP pathway. Taken together, our study describes, in the context of an H. pylori infection, a direct link between Foxp3 and miR-155 in human T cells and highlights the significance of cAMP in this miR-155 induction cascade.

PLoS ONE, 2013

Helicobacter bilis (H. bilis) infection is associated with cases of inflammatory bowel Disease, t... more Helicobacter bilis (H. bilis) infection is associated with cases of inflammatory bowel Disease, thyphlocolitis, hepatitis and cholecystitis. However, little is known about the bacterial virulence determinants or the molecular mechanisms involved. Recently, H. bilis γ-glutamyltranspeptidase (HBgGT) was shown to be a virulence factor decreasing host cell viability. Bacterial gGTs play a key role in synthesis and degradation of glutathione and enables the bacteria to utilize extracellular glutamine and glutathione as sources of glutamate. gGT-mediated loss of cell viability has so far been linked to DNA damage via oxidative stress, but the signaling cascades involved herein have not been described. In this study, we identified enhanced ROS production induced by HBgGT as a central factor involved in the activation of the oxidative stress response cascades, which finally activate CREB, AP-1 and NF-κB in H. bilis infected colon cancer cells. IL-8, an important pro-inflammatory chemokine that is a common downstream target of these transcription factors, was up-regulated upon H. bilis infection in an HBgGT dependent manner. Moreover, the induction of these signaling responses and inflammatory cytokine production in host cells could be linked to HBgGTmediated glutamine deprivation. This study implicates for the first time HBgGT as an important regulator of signaling cascades regulating inflammation in H. bilis infected host epithelial cells that could be responsible for induction of inflammatory disorders by the bacterium.

Zeitschrift für Gastroenterologie, 2009

Helicobacter pylori (H.p.) is the most widespread bacterial infection, affecting half of the worl... more Helicobacter pylori (H.p.) is the most widespread bacterial infection, affecting half of the world population and causing peptic ulcers and gastric cancer. Although big efforts have been initiated to develop a vaccine against this pathogen none of these experimental approaches led to successful results in human studies and thus failed to generate an approved vaccine in humans. It is unclear if this is due to the antigens used, the vaccine formulations tested to induce protective immunity or the laboratory infection models applied. Our group described a virulence factor of H. pylori, the H.p. gamma-glutmyltranspeptidase (HPgGT) that inhibits the proliferation of T-cells and thus prevents the generation of an effective immune response. We used HPgGT in an experimental mouse infection model for a novel vaccination approach. Immunization with this antigen induces strong antibody responses, which blocks its enzymatic activity, thereby counteracting the immunosuppressive activity of HPgGT. Different formulations and routes of application were tested, revealing a need for mucosal immunization. As HPgGT is a secreted protein, HPgGT specific T-cells can hardly target the pathogen. Therefore we combine this protein with outer membrane proteins to induce protective T-cell responses. In infection experiments this vaccination lead to a substantial decrease of bacterial colonization in the stomach, making this new approach of a “liberating vaccine“ a promising candidate for a new immunization strategy.

Zeitschrift für Gastroenterologie, 2009

The Journal of Infectious Diseases, 2005

Background. Infection of the gastric mucosa with Helicobacter pylori leads to increased apoptosis... more Background. Infection of the gastric mucosa with Helicobacter pylori leads to increased apoptosis. Cytokines and receptors of the tumor necrosis factor (TNF) family are known to be involved in this process. The role that the death-inducing TNF-a-related apoptosis-inducing ligand (TRAIL) and its receptors play, in the context of H. pylori infection, is unknown. Methods. In 74 H. pylori-infected and 51 H. pylori-uninfected gastric antral biopsy specimens, levels of TRAIL mRNA and TRAIL receptor mRNA were determined quantitatively by TaqMan reverse-transcriptase polymerase chain reaction. Recombinant TRAIL-induced apoptosis was measured in human and rat gastric epithelial cells by end-labeling of DNA with fluorescein-dTUP and by fluorescence-activated cell sorter analysis. Results. In patients infected with cagA + /vacAs1 + H. pylori strains, expression of TRAIL and the proapoptotic receptors TRAIL-R1 and-R2 was down-regulated, whereas expression of the antiapoptotic receptors TRAIL-R3 and-R4 was up-regulated. Furthermore, expression of TRAIL and TRAIL-R1 and-R2 correlated inversely with the severity of gastric inflammation. Significant apoptosis of isolated human gastric epithelial cells and highly enriched rat parietal and chief cells was induced by 100 ng/mL TRAIL. Conclusions. Down-regulation of the TRAIL system, in the context of H. pylori infection, may limit exaggerated apoptosis of gastric epithelial cells and destruction of tissue and, therefore, may enable H. pylori to maintain its niche.

Journal of Allergy and Clinical Immunology, 2009

Journal of Allergy and Clinical Immunology, 2011

Based on a recent positional cloning approach, it was claimed that the collagen 29A1 gene (COL29A... more Based on a recent positional cloning approach, it was claimed that the collagen 29A1 gene (COL29A1), which encodes an epidermal collagen, represents a major risk gene for eczema underlying a previously reported linkage to chromosome 3q21. However, thus far, not a single replication attempt has been published, and no definitive functional data have been provided. We aimed to determine whether COL29A1 polymorphisms contribute to eczema susceptibility and whether COL29A1 expression is altered in eczema. We investigated the reported association of COL29A1 variants with eczema, subtypes of eczema, and eczema-related traits in 5 independent and large study populations comprehensively phenotyped for allergic diseases: a set of 1687 German patients with eczema and 2387 population control subjects, a collection of 274 German families with eczema-diseases children, a cross-sectional population of German children (n = 3099), the Swedish population-based birth cohort Children Allergy and Milieu in Stockholm, an Epidemiologic Study (BAMSE) (n = 2033), and the European cross-sectional Prevention of Allergy-Risk Factors for Sensitization Related to Farming and Anthroposophic Lifestyle (PARSIFAL) study (n = 3113). An additional set of 19 COL29A1 coding single nucleotide polymorphisms was analyzed in BAMSE and PARSIFAL. COL29A1 expression was investigated by using in situ hybridization. We found no evidence for a relationship between COL29A1 polymorphisms and eczema. The equivalence test rejected the hypothesis of association even excluding small effects. In situ hybridization carried out on biopsy specimens from lesional and nonlesional skin of patients with eczema and from healthy control subjects did not show any differences in the cellular distribution pattern of COL29A1 expression at the mRNA level. Our results suggest that COL29A1 is unlikely to contain genetic variants that have a major effect on eczema or atopy susceptibility.