Mechanisms of host-pathogen interaction during chronic infection, inflammation and carcinogenesis

Bild: Susanne Dürr

Our research group is working on the mechanisms of tumor development in the gastrointestinal tract, especially during chronic inflammation elicited by Helicobacter pylori infection and in the stomach, and as a result of deregulation of the Wnt signaling pathway in the intestine and colon. In parallel, we are interested in identifying targets to develop novel prophylactic approaches and therapeutic strategies for H. pylori infection and stomach cancer.

Basic Research Projects

Pathogenesis of Helicobacter pylori infection

H. pylori infection is one of the most prevalent infections worldwide. The presence of H. pylori in the gastric mucosa has been associated with duodenal and gastric ulcers as well as an increased risk of gastric cancer development. In recent years, we have focused on the interaction of H. pylori with host immune and epithelial cells, identifying virulence factors contributing to colonization, immune evasion and persistence of H. pylori in the stomach. Moreover, we have explored signaling pathways triggered upon infection and their effect on gastric pathology.

• Bacterial recognition and host-pathogen interaction

Adhesion of the bacteria to the gastric epithelium is essential for the establishment of infection, since specific bacterial adhesin-host receptor interactions allow the pathogen to tightly bind to target cells, thereby facilitating the colonization of the host tissue (Aspholm-Hurtig et al. Science 2004). Iidentification and characterization of bacterial adhesins and their corresponding receptors represents a major topic in our laboratory. Thus, we identified a novel adhesin, HopQ, which is important not only for bacterial adhesion to the gastric epithelium but also essential for translocation of the virulence factor CagA into host cells through the type IV secretion system (Javaheri et al. Nat Microbiol. 2016). HopQ binds CEACAM receptors expressed by epithelial cells in a well-defined manner (Moonens et al. EMBO J. 2018). Furthermore, we are interested in the role of this adhesin in persistence of infection and how it may eventually interfere with host-signaling cascades.

• Effect of H. pylori infection and chronic inflammation on signaling pathways associated with gastric carcinogenesis

Chronic inflammation induced by H. pylori infection is one of the first steps in the pathological cascade leading to the development of tumors. Our group is interested in deciphering the molecular mechanisms by which, on the one hand, H. pylori disrupts gastric epithelial homeostasis and, on the other hand, persists in the host, paying special attention to the bacterial virulence factors involved.

In epithelial cells, we are currently analyzing the effect of H. pylori on signal pathways related to gastric carcinogenesis such as STAT3 or NF-kB by using in vitro as well as in vivo models of infection. Thus, we found that activation of non-canonical NF-κB signaling by H. pylori through lymphotoxin receptor is an essential mechanism driving chronic gastric inflammation (Mejías-Luque et al. Gut 2017), while LIGHT, another ligand activating non-canonical NF-κB is related to gastric pathology (Mejías-Luque et al. Sci Rep. 2019). Currently, we are further investigating this signaling pathway using different cellular and animal models.

In parallel, we are studying how H. pylori manipulates the host’s immune response, particularly by analyzing the effect of H. pylori infection on dendritic as well as on T cells. We described a novel molecular mechanism by which H. pylori induces tolerance. Thus, H. pylori CagA leads to impaired maturation and function of human dendritic cells through IL-10-mediated activation of STAT3, favoring the expansion of regulatory T cells (Käbisch and Mejías-Luque et al. J Immunol. 2014).

Our findings also indicate that H. pylori γ-glutamyltranspeptidase (gGT) is an essential virulence factor driving tolerance and contributing to immune evasion. In dendritic cells, H. pylori gGT influences cytokine secretion skewing the subsequent T cell response towards a regulatory phenotype (Käbisch et al. J Immunol. 2016), while in T cells, H. pylori γ-glutamyltranspeptidase inhibits cMyc and IRF4 expression compromising metabolic adaptation (Wüstner et al. Cellular microbiology 2015). Notably, in vivo, H. pylori gGT is required for the recruitment oc CD8+ T cells to the stomach of infected mice, while in humans, gGT activity correlates with CD8 infiltration. We are further exploring the function of gGT as well as characterizing CD8 T cell responses found upon H. pylori infection.



Role of the ubiquitin ligase RNF43 in gastrointestinal cancer

The canonical Wnt signaling pathway is essential in developmental processes and plays a crucial role in the regulation of epithelial stem cell self-renewal. Deregulation of this pathway is associated with carcinogenesis, particularly in the gastrointestinal tract. We identified a target gene of the Wnt signaling pathway, RNF43, which is selectively expressed in intestinal stem cells and is overexpressed in colorectal adenomas and a subset of colorectal cancers. Overexpression of RNF43 was shown to inhibit Wnt signaling in colon cancer cells by impairing Frizzled receptor turnover. Interestingly, we found an alternative mechanism of RNF43-mediated Wnt inhibition downstream of (mutated)β-catenin. Thus, RNF43 sequesters TCF4 to the nuclear membrane, dampening the transcription of important Wnt target genes (Loregger et al., Sci Signal. 2015).

Mutations of RNF43 have been identified in several tumor types, suggesting an important role for RNF43 as a tumor suppressor gene. Indeed, depletion of RNF43 expression in colon and gastric cells increases their tumorigenic potential (Neumeyer et al. Carcinogenesis 2019). To further explore the function of RNF43 we have generated two mouse models expressing mutated Rnf43. Mutations in Rnf43 lead to gastric hyperproliferation (Neumeyer et al. Carcinogenesis 2019), which is exacerbated upon H. pylori infection (Neumeyer et al. Cancers 2019). We are also analyzing the mutation status of RNF43 in human gastroinstestinal tumor samples and studying them functionally in order to determine the role of RNF43 in colon and gastric cancer. In addition, we are exploring the value of RNF43 as a biomarker as well as a possible therapeutic target for gastrointestinal tumors (see also project 17 within SFB 1321


Translational Research Projects

Vaccine development against H. pylori

 Different antigens have been identified in the recent years, which may be potential vaccine candidates, however no vaccine against H. pylori is currently available. Through combination of new antigens, adjuvants and new vaccine formulations, we are working towards developing improved vaccines and establishing protocols for protective immunization in animal models. Our team aims to create a more effective novel vaccine by targeting immune modulatory factors important for the establishment and maintenance of bacterial infections.



Clinical trials

Our group is actively involved in different clinical trials aiming at understanding H. pylori infection and its prevalence in Germany, identifying biomarkers for therapy of gastric cancer patients and establishing the validity of endoscopic surveillance to prevent gastric cancer in high risk populations. Some of these clinical trials are conducted in China in close collaboration with the Peking University Cancer Hospital, under the umbrella of our TUM research presence, the Key Joint Laboratory PYLOTUM (

Microbiome sequencing facility

Within the German Center of Infection Research /DZIF), we have established a core NGS sequencing facility giving support to different research projects aiming at analyzing microbiota changes and its relation to different pathological manifestations. In addition, we are conducting different clinical studies where the analysis of intestinal and gastric microbiota is a major focus to understand disease outcome.


▪ Markus Gerhard, Prof. Dr. med. (Group leader)

▪ Raquel Mejías-Luque, PhD (Research and laboratory manager)

▪ Raphaela Semper, Dr. rer. nat.

▪ Dharmesh Singh, PhD

▪ Claudia Crowell, MD

▪ Anna Brutau Abia, PhD student

▪ Teresa Burrell, technical assistant

▪ Alisa Dietl, MD, PhD student

▪ Sonja Fuchs, PhD student

▪ Ruolan Gong, PhD student

▪ Youssef Hamway, PhD student

▪ Ursula Kälberer, study nurse

▪ Maximillian Koch, MD student

▪ Karin Mink, technical assistant

▪ Anna Ralser, MD, PhD student

▪ Martin Skerhut, laboratory assistant

▪ Karin Taxauer, PhD student

▪ Mona Wang, PhD student

▪ Andreas Wanisch, technical assistant

Selected Publications                                           

Hamway Y, Taxauer K, Moonens K, Neumeyer V, Fischer W, Schmitt V, Singer BB, Remaut H, Gerhard M, Mejías-Luque R. Cysteine Residues in Helicobacter pylori Adhesin HopQ Are Required for CEACAM-HopQ Interaction and Subsequent CagA Translocation. Microorganisms. 2020 Mar 25;8(4):465. (Full Text; Abstract)

Guo Y, Zhang Y, Gerhard M, Gao JJ, Mejias-Luque R, Zhang L, Vieth M, Ma JL, Bajbouj M, Suchanek S, Liu WD, Ulm K, Quante M, Li ZX, Zhou T, Schmid R, Classen M, Li WQ, You WC, Pan KF. Effect of Helicobacter pylori on Gastrointestinal Microbiota: A Population-Based Study in Linqu, a High-Risk Area of Gastric Cancer. Gut. 2019 Dec 19;gutjnl-2019-319696. (Full text; Abstract)

Hornburg D, Kruse T, Anderl F, Daschkin C, Semper RP, Klar K, Guenther A, Mejías-Luque R, Schneiderhan-Marra N, Mann M, Meissner F, Gerhard M. A Mass Spectrometry Guided Approach for the Identification of Novel Vaccine Candidates in Gram-Negative Pathogens. Sci Rep. 2019 Nov 22;9(1):17401. (Full Text; Abstract)

Semper RP, Vieth M, Gerhard M, Mejías-Luque R. Helicobacter pylori Exploits the NLRC4 Inflammasome to Dampen Host Defenses. J Immunol. 2019 Oct 15;203(8):2183-2193. (Full Text; Abstract)

Bhattacharjee S, Mejías-Luque R, Loffredo-Verde E, Toska A, Flossdorf M, Gerhard M, Prazeres da Costa C. Concomitant Infection of S. Mansoni and H. Pylori Promotes Promiscuity of Antigen-Experienced Cells and Primes the Liver for a Lower Fibrotic Response. Cell Rep. 2019 Jul 2;28(1):231-244.e5. (Full Text; Abstract)                

Mejías-Luque R, Lozano-Pope I, Wanisch A, Heikenwälder M, Gerhard M, Obonyo M. Increased LIGHT expression and activation of non-canonical NF-κB are observed in gastric lesions of MyD88-deficient mice upon Helicobacter felis infection. Sci Rep. 2019 May 7;9(1):7030. (Full Text; Abstract)

Neumeyer V, Vieth M, Gerhard M, Mejías-Luque R. Mutated Rnf43 Aggravates Helicobacter Pylori-Induced Gastric Pathology. Cancers (Basel). 2019 Mar 16;11(3). pii: E372. (Full Text; Abstract)

Neumeyer V, Grandl M, Dietl A, Brutau-Abia A, Allgäuer M, Kalali B, Zhang Y, Pan KF, Steiger K, Vieth M, Anton M, Mejías-Luque R, Gerhard M. Loss of endogenous RNF43 function enhances proliferation and tumour growth of intestinal and gastric cells. Carcinogenesis. 2019 Jun 10;40(4):551-559. (Full Text; Abstract)

Moonens K, Hamway Y, Neddermann M, Reschke M, Tegtmeyer N, Kruse T, Kammerer R, Mejías-Luque R, Singer BB, Backert S, Gerhard M, Remaut H. Helicobacter pylori adhesin HopQ disrupts trans dimerization in human CEACAMs. EMBO J. 2018 Jul 2;37(13). (Full Text; Abstract)

Quintana I, Mejías-Luque R, Terradas M, Navarro M, Piñol V, Mur P, Belhadj S, Grau E, Darder E, Solanes A, Brunet J, Capellá G, Gerhard M, Valle L. Evidence suggests that germline RNF43 mutations are a rare cause of serrated polyposis. Gut. 2018 Jan 12. (Full Text; Abstract)

Formichella L, Romberg L, Meyer H, Bolz C, Vieth M, Geppert M, Göttner G, Nölting C, Schepp W, Schneider A, Ulm K, Wolf P, Holster IL, Kuipers EJ, Birkner B, Soutschek E, Gerhard M. Validation of a Novel Immunoline Assay for Patient Stratification according to Virulence of the Infecting Helicobacter pylori Strain and Eradication Status. J Immunol Res. 2017;2017:8394593. (Full Text; Abstract

Mejías-Luque R, Gerhard M. Immune Evasion Strategies and Persistence of Helicobacter pylori. Curr Top Microbiol Immunol. 2017;400:53-71. (Full Text; Abstract)

Javaheri A, Kruse T, Moonens K, Mejías-Luque R, Debraekeleer A, Asche CI, Tegtmeyer N, Kalali B, Bach NC, Sieber SA, Hill DJ, Königer V, Hauck CR, Moskalenko R, Haas R, Busch DH, Klaile E, Slevogt H, Schmidt A, Backert S, Remaut H, Singer BB, Gerhard M. Helicobacter pylori adhesin HopQ engages in a virulence-enhancing interaction with human CEACAMs. Nat Microbiol. 2016 Oct 17;2:16189. (Full Text; Abstract)

Mejias-Luque, R., J. Zoller, F. Anderl, E. Loew-Gil, M. Vieth, T. Adler, D.B. Engler, S. Urban, J.L. Browning, A. Muller, M. Gerhard, and M. Heikenwalder (2017). Lymphotoxin beta receptor signalling executes Helicobacter pylori-driven gastric inflammation in a T4SS-dependent manner. Gut. 66:1369-1381.(Full Text; Abstract)

Wüstner S, Anderl F, Wanisch A, Sachs C. Steiger K, Nerlich A, Vieth M, Mejías-Luque R, Gerhard M. Helicobacter pylori γ-glutamyl transferase contributes to colonization and differential recruitment of T cells during persistence Scientific Reports volume 7, Article number: 13636 (2017) (Full Text; Abstract)

Loregger A, Grandl M, Mejías-Luque R, Allgäuer M, Degenhart K, Haselmann V, Oikonomou C, Pantelis Hatzis, Janssen KP, Nitsche U, Gradl D, van den Broek O, Destree O, Neumaier M, Kalali B, Jung A, Varela I, Schmid RM, Rad R, Busch DH and Gerhard M. The stem-cell E3 ligase RNF43 displays a novel mode of Wnt inhibition downstream of (mutated) β-catenin, which is disrupted in tumors bearing RNF43 mutations. Science Signaling 2015 Sep 8;8(393):ra90. (Full Text; Abstract)

Wüstner S, Mejías-Luque R, Koch M, Rath E, Vieth M, Sieber SA, Haller D, Gerhard M. H. pylori γ-glutamyltranspeptidase impairs T lymphocyte function by compromising metabolic adaption through inhibition of cMyc and IRF4 expression. Cellular microbiology 2015; 17: 51-61. (Full Text; Abstract)

Anderl F, Gerhard M. Helicobacter pylori vaccination: Is there a path to protection? World J Gastroenterol. 2014 Sep 14;20(34):11939-11949.(Full Text; Abstract)

Semper RP, Mejías-Luque R, Groß C, Anderl F, Oertli M, Engler D, Müller A, Vieth M, Busch DH, Prazeres da Costa C, Ruland J, Groß O and Gerhard M. Helicobacter pylori-induced IL-1β secretion in innate immune cells is regulated by the NLRP3 inflammasome and requires the Cag Pathogenicity Island. J Immunol., 2014 Oct 1;193(7):3566-76. (Full Text; Abstract)

Käbisch R, Mejías-Luque R, Gerhard M and Prinz C. Involvement of Toll-like Receptors on Helicobacter pylori-induced immunity. PLos One, 2014 Aug 25;9(8):e104804. (Full Text; Abstract)

Kalali B, Mejías-Luque R, Javaheri A, Gerhard M. H. pylori virulence factors: influence on immune system and pathology. Mediators Inflamm. 2014;2014:426309. (Full Text; Abstract)

Hütz K, Mejías-Luque R, Farsakova K, Ogris M, Krebs S, Anton M, Vieth M, Schüller U, Scheneider RM, Blum H, Wagner E, Jung A, Gerhard M. The stem cell factor Sox2 regulates the tumorigenic potential in human gastric cancer cells. Carcinogenesis. 2014 Apr;35(4):942-50. (Full Text; Abstract)

Käbisch R, Mejías-Luque R, Prinz C, Gerhard M. Helicobacter pylori CagA impairs dendritic cell maturation and function through IL-10-mediated activation of STAT3. J Immunol. 2014 Jan 1;192(1):316-23 (Full Text; Abstract)

Pan KF, Formichella L, Zhang L, Zhang Y, Ma JL, Li ZX, Liu C, Wang YM, Goettner G, Ulm K, Classen M, You WC, Gerhard M. Helicobacter pylori antibody responses and evolution of precancerous gastric lesions in a chinese population. Int J Cancer. 2014 May 1;134(9):2118-25. (Full Text; Abstract)

Khalifeh Gholi M, Kalali B, Formichella L, Göttner G, Shamsipour F, Zarnani AH, Hosseini M, Busch DH, Shirazi MH, Gerhard M. Helicobacter pylori FliD protein is a highly sensitive and specific marker for serologic diagnosis of H. pylori infection. Int J Med Microbiol. 2013 Dec;303(8):618-23. (Full Text; Abstract)

Javed S, Mejías-Luque R, Kalali B, Bolz C, Gerhard M. Helicobacter bilis Gamma-Glutamyltranspeptidase Enhances Inflammatory Stress Response via Oxidative Stress in Colon Epithelial Cells. PLoS One. 2013 Aug 23;8(8):e73160. (Full Text; Abstract)

Formichella L, Romberg L, Bolz C, Vieth M, Geppert M, Göttner G, Nölting C, Walter D, Schepp W, Schneider A, Ulm K, Wolf P, Busch DH, Soutschek E, Gerhard M. A novel immuno-line assay based on recombinant virulence factors enables highly specific and sensitive serological diagnosis of H. pylori infection. Clin Vaccine Immunol. 2013 Nov;20(11):1703-10. (Full Text; Abstract)

Schmees C, Prinz C, Treptau T, Rad R, Hengst L, Voland P, Bauer S, Brenner L, Schmid RM, Gerhard M. Inhibition of T cell proliferation by Helicobacter pylori γ-glutamyl transpeptidase. Gastroenterology 2007 May;132(5):1820-33. (Full Text; Abstract)                                                    

Gerhard M, Schmees C, Voland P,  Endres N, Sander M, Reindl W, Rad R, Oelsner M, Decker T, Mempel M, Hengst L, Prinz C. A secreted low molecular weight protein from Helicobacter pylori induces cell cycle arrest of T-cells. Gastroenterology 2005;128(5):1327-39. (Full Text; Abstract)