Helicobacter pylori-activated gastric fibroblasts induce epithelial-mesenchymal transition of gastric epithelial cells in vitro in a TGF-β-dependent manner

The interplay between persistent pathogen infections with tumor microenvironment and immunotherapy in cancer

BACKGROUND

Chronic infections by pathogenic microorganisms play a significant role in cancer development, disrupting the body's immune system and microenvironment. This interference impairs the body's ability to eliminate these microorganisms promptly, allowing them to persist by evading immune defenses.

AIMS

This study aimed to explore how chronic pathogenic infections influence the immune microenvironment, impacting tumorigenesis, cancer progression, and treatment strategies. Additionally, it seeks to investigate the effects of these infections on specific immune checkpoints and identify potential targets for immunotherapy.

METHODS

We conducted searches, readings, and detailed analyses of key terms in databases like PubMed and Web of Science to evaluate the impact of chronic infections by pathogenic microorganisms on the immune microenvironment.

RESULTS

Our analysis demonstrates a significant association between persistent chronic infections by pathogenic microorganisms and tumorigenesis. Notable impacts on the immune microenvironment include changes in immune cell function and the regulation of immune checkpoints, offering insights into potential targets for cancer immunotherapy.

DISCUSSION

This study highlights the complex relationship between chronic infections and cancer development, presenting new opportunities for cancer immunotherapy by understanding their effects on the immune microenvironment. The influence of these infections on immune checkpoints emphasizes the crucial role of the immune system in cancer treatment.

CONCLUSION

Chronic infections by pathogenic microorganisms greatly affect the immune microenvironment, tumorigenesis, and cancer treatment. Unraveling the underlying mechanisms can unveil potential targets for immunotherapy, improving our comprehension of the immune response to cancer and potentially leading to more effective cancer treatments in the future.

GDF6 in gastric cancer upregulated by helicobacter pylori induces epithelial-mesenchymal translation via the TGF-β/SMAD3 signaling pathway

OBJECTIVE

To investigate the association between Helicobacter pylori infection and GDF6 expression in gastric cancer patients, and to determine its influence on prognosis and resistance to capecitabine.

METHODS

Tumor and adjacent non-tumor tissues were collected from 148 gastric cancer patients who underwent surgery in our department from October 2019 to June 2022. Of these patients, 78 tested positive for Helicobacter pylori and 70 tested negative. Hematoxylin-eosin (HE) and immunofluorescence staining were utilized to quantify GDF6 expression in cancerous and adjacent tissues. Patient prognosis was monitored via follow-up. Western blotting analyzed GDF6 expression in common gastric cancer cell lines. HGC27 cells exhibiting high GDF6 expression and BGC823 cells with low expression were used to create GDF6-silenced and overexpressed cell lines. The impact of GDF6 on the proliferation, migration, invasion, and cloning abilities of gastric cancer cells was evaluated using the CCK-8 assay, scratch test, Transwell assay, and plate colony formation assay. Fluorescent quantitative PCR and Western blotting assessed the effects of GDF6 levels on epithelial-mesenchymal transition (EMT) and tumor cell stemness.

RESULTS

GDF6 expression in gastric cancer tissues was significantly correlated with cancer grading and staging (P<0.05). Helicobacter pylori-positive tissues exhibited significantly higher GDF6 expression levels than negative samples (P<0.05). Kaplan-Meier survival analysis indicated that high GDF6 expression was associated with poor survival prognosis. Overexpressed GDF6 enhanced the proliferation, migration, and invasion abilities of gastric cancer cells, while silencing GDF6 yielded opposite results. Increased GDF6 expression upregulated TGF-β expression and the phosphorylation levels of SMAD3, leading to an elevation in mesenchymal cell markers N-cadherin, vimentin, and a reduction in epithelial cell markers cytokeratins, E-cadherin. Moreover, high GDF6 levels contributed to increased resistance to capecitabine and enhanced the expression of tumor stem cell markers Nanog, Sox-2, Oct-4, CD44, amplifying tumor cell stemness.

CONCLUSION

Helicobacter pylori infection is associated with increased GDF6 expression in gastric cancer tissue, correlating with poor survival prognosis. Elevated GDF6 expression promotes the proliferation, migration, and invasion abilities of gastric cancer cells, facilitates EMT via the TGF-β/SMAD3 pathway, and intensifies cell stemness and capecitabine resistance. Consequently, GDF6 presents itself as a potential new target for gastric cancer treatment.

DATA AVAILABILITY STATEMENT

The data that support the findings of this study are available from the corresponding author upon reasonable request.

Tumor cell stemness in gastrointestinal cancer: regulation and targeted therapy

The cancer stem cells are a rare group of self-renewable cancer cells capable of the initiation, progression, metastasis and recurrence of tumors, and also a key contributor to the therapeutic resistance. Thus, understanding the molecular mechanism of tumor stemness regulation, especially in the gastrointestinal (GI) cancers, is of great importance for targeting CSC and designing novel therapeutic strategies. This review aims to elucidate current advancements in the understanding of CSC regulation, including CSC biomarkers, signaling pathways, and non-coding RNAs. We will also provide a comprehensive view on how the tumor microenvironment (TME) display an overall tumor-promoting effect, including the recruitment and impact of cancer-associated fibroblasts (CAFs), the establishment of an immunosuppressive milieu, and the induction of angiogenesis and hypoxia. Lastly, this review consolidates mainstream novel therapeutic interventions targeting CSC stemness regulation.

Helicobacter pylori promotes gastric fibroblast proliferation and migration by expulsing exosomal miR-124-3p

Gastric fibroblasts (GFs) are direct targets of Helicobacter pylori (H. pylori). GFs infected with H. pylori exhibit marked changes in their morphology and biological behavior. However, the molecular mechanisms by which H. pylori regulates GFs remain unknown. In this study, we cocultured GFs with H. pylori for 48 h. As a result, GFs exhibited an elongated and spindle-shaped morphology. Further, cancer-associated fibroblast (CAF) biomarkers were increased, and related behaviors were significantly enhanced in H. pylori-activated GFs. The number of extracellular vesicles (EVs) secreted by H. pylori-activated GFs remarkably increased. The miR-124-3p level was increased in secreted EVs but decreased in the cytoplasm of H. pylori-activated GFs. Overexpression of miRNA-124-3p in the original GFs significantly suppressed their proliferation and migration. In addition, the migration-promoting effects of H. pylori-activated GFs were suppressed by miR-124-3p and GW4869, which blocked EV generation. Finally, pull-down and luciferase assays revealed that SNAI2 is a target of miR-124-3p. The migration-inhibitory effects of GFs treated with miR-124-3p were eliminated by the overexpression of SNAI2, and the upregulation of SNAI2 in H. pylori-activated GFs was partially alleviated by miR-124-3p or GW4869. Overall, H. pylori infection promotes the proliferation and migration of GFs by accelerating the expulsion of EVs carrying miRNA-124-3p, a SNAI2 inhibitor.

Helicobacter pylori-induced fibroblast-derived Serpin E1 promotes gastric cancer growth and peritoneal dissemination through p38 MAPK/VEGFA-mediated angiogenesis

BACKGROUND

Fibroblasts, especially cancer-associated fibroblasts (CAFs), represent the predominant stromal cell population in the tumor microenvironment and have an important function in tumorigenesis by interacting with tumor cells. However, their interaction remains elusive in an inflammatory tumor microenvironment induced by Helicobacter pylori (H. pylori).

METHODS

The expression of Serpin family E member 1 (Serpin E1) was measured in fibroblasts with or without H. pylori infection, and primary gastric cancer (GC) cells. Serpin E1 knockdown and overexpression fibroblasts were generated using Serpin E1 siRNA or lentivirus carrying Serpin E1. Co-culture models of fibroblasts and GC cells or human umbilical vein endothelial cells (HUVECs) were established with direct contact or the Transwell system. In vitro functional experiments and in vivo tumorigenesis assay were employed to study the malignant behaviors of GC cells interacting with fibroblasts. ELISA was used for quantifying the levels of Serpin E1 and VEGFA in the culture supernatant. The tube formation capacity of HUVECs was assessed using a tube formation assay. Recombinant human Serpin E1 (recSerpin E1), anti-Serpin E1 antibody, and a MAPK pathway inhibitor were utilized to treat HUVECs for elucidating the underlying molecular mechanisms.

RESULTS

Serpin E1 was predominantly expressed in gastric CAFs. H. pylori infection significantly enhanced the expression and secretion of Serpin E1 by CAFs. Both fibroblast-derived Serpin E1 and recSerpin E1 enhanced the growth, invasion, and migration of GC cells, along with increased VEGFA expression and tube formation in HUVECs. Furthermore, the co-inoculation of GC cells and fibroblasts overexpressing Serpin E1 triggered the expression of Serpin E1 in cancer cells, which facilitated together xenograft tumor growth and peritoneal dissemination of GC cells in nude mice, with an increased expression of Ki67, Serpin E1, CD31 and/or VEGFA. These processes may be mediated by Serpin E1-induced migration and p38 MAPK/VEGFA-mediated angiogenesis of HUVECs.

CONCLUSION

H. pylori infection induces Serpin E1 expression in fibroblasts, subsequently triggering its expression in GC cells through their interaction. Serpin E1 derived from these cells promotes the migration and p38 MAPK/VEGFA-mediated angiogenesis of HUVECs, thereby facilitating GC growth and peritoneal metastasis. Targeting Serpin E1 signaling is a potential therapy strategy for H. pylori-induced GC.

Helicobacter pylori-activated fibroblasts as a silent partner in gastric cancer development

The discovery of Helicobacter pylori (Hp) infection of gastric mucosa leading to active chronic gastritis, gastroduodenal ulcers, and MALT lymphoma laid the groundwork for understanding of the general relationship between chronic infection, inflammation, and cancer. Nevertheless, this sequence of events is still far from full understanding with new players and mediators being constantly identified. Originally, the Hp virulence factors affecting mainly gastric epithelium were proposed to contribute considerably to gastric inflammation, ulceration, and cancer. Furthermore, it has been shown that Hp possesses the ability to penetrate the mucus layer and directly interact with stroma components including fibroblasts and myofibroblasts. These cells, which are the source of biophysical and biochemical signals providing the proper balance between cell proliferation and differentiation within gastric epithelial stem cell compartment, when exposed to Hp, can convert into cancer-associated fibroblast (CAF) phenotype. The crosstalk between fibroblasts and myofibroblasts with gastric epithelial cells including stem/progenitor cell niche involves several pathways mediated by non-coding RNAs, Wnt, BMP, TGF-β, and Notch signaling ligands. The current review concentrates on the consequences of Hp-induced increase in gastric fibroblast and myofibroblast number, and their activation towards CAFs with the emphasis to the altered communication between mesenchymal and epithelial cell compartment, which may lead to inflammation, epithelial stem cell overproliferation, disturbed differentiation, and gradual gastric cancer development. Thus, Hp-activated fibroblasts may constitute the target for anti-cancer treatment and, importantly, for the pharmacotherapies diminishing their activation particularly at the early stages of Hp infection.

Masking of typical TLR4 and TLR5 ligands modulates inflammation and resolution by Helicobacter pylori

Helicobacter pylori is a paradigm of chronic bacterial infection and is associated with peptic ulceration and malignancies. H. pylori uses specific masking mechanisms to avoid canonical ligands from activating Toll-like receptors (TLRs), such as lipopolysaccharide (LPS) modification and specific flagellin sequences that are not detected by TLR4 and TLR5, respectively. Thus, it was believed for a long time that H. pylori evades TLR recognition as a crucial strategy for immune escape and bacterial persistence. However, recent data indicate that multiple TLRs are activated by H. pylori and play a role in the pathology. Remarkably, H. pylori LPS, modified through changes in acylation and phosphorylation, is mainly sensed by other TLRs (TLR2 and TLR10) and induces both pro- and anti-inflammatory responses. In addition, two structural components of the cag pathogenicity island-encoded type IV secretion system (T4SS), CagL and CagY, were shown to contain TLR5-activating domains. These domains stimulate TLR5 and enhance immunity, while LPS-driven TLR10 signaling predominantly activates anti-inflammatory reactions. Here, we discuss the specific roles of these TLRs and masking mechanisms during infection. Masking of typical TLR ligands combined with evolutionary shifting to other TLRs is unique for H. pylori and has not yet been described for any other species in the bacterial kingdom. Finally, we highlight the unmasked T4SS-driven activation of TLR9 by H. pylori, which mainly triggers anti-inflammatory responses.

Direct tool for quantitative analysis of cell/object dynamic behavior - metastasis and far beyond

INTRODUCTION

The dynamics and depth of invasion as well as the ability of cancer cells to penetrate the walls of  lymphatic or blood vessels represent critical survival-influencing factors in cancer patients. Depending on the cell type and tissue environment, cancer cell invasion differ in terms of motility mechanism and migration modes. Thus, there is the need of effective models allowing not only for single cell invasion potential assessment but also for collective migration and expansive growth evaluation in 3D microenvironment e.g. basement membranes. To meet this task, the specimens should be compared and analyzed in terms of the dynamics of movement and the evolution of the shape.

OBJECTIVES

Our main objective was development of the mathematical method that enables fast and credible calculation of parameters of shape and position, namely standard deviations (σ_X, σ_Y), centroid position (μ_X, μ_Y) and correlation coefficient ρ, based only on the contour of the aggregate.

METHODS

In order to accomplish this goal we measured geometrical properties of aggregates of RGM1 cells seeded in 3D Geltrex basement membrane. Referential microscopic images were taken 24 and 48 h after seeding and cell group dynamics was registered over 8 h periods using time lapse microscopy.

RESULTS

Based on gathered data, we managed to develop and fully test universal numerical tool allowing for estimation of statistical parameters of cell groups and aggregates which then allows for the precise evaluation of their behavior within microenvironment with time.

CONCLUSION

We conclude, that our tool is suitable for any research on the metastatic potential and motility of cancer cells in a given microenvironment, regardless of the migration mechanism, which together with the advanced analysis like cell single-cell transcriptomic, proteomic, and chromatin accessibility data may allow to identify precise targets for anti-cancer therapies, to predict the degree of malignancy of neoplastic lesions as well as it can be useful during architecting therapeutic strategies. Moreover, the developed tool seems to be broadly applicable for assessment of behavioural dynamics of any population.

The interaction of Helicobacter pylori with cancer immunomodulatory stromal cells: New insight into gastric cancer pathogenesis

Gastric cancer is the fourth most common cause of cancer-linked deaths in the world. Gastric tumor cells have biological characteristics such as rapid proliferation, high invasiveness, and drug resistance, which result in recurrence and poor survival. Helicobacter pylori (H. pylori) has been proposed as a first-class carcinogen for gastric cancer according to the 1994 world health organization (WHO) classification. One of the important mechanisms by which H. pylori affects the gastric environment and promotes carcinogenesis is triggering inflammation. H. pylori induces an inflammatory response and a plethora of different signal transduction processes, leading to gastric mucosal disturbance, chronic gastritis, and a multi-step complex pathway that initiates carcinogenesis. It seems undeniable that the interaction between various cell types, including immune cells, gastric epithelium, glands, and stem cells, is vital for the progression and development of carcinogenesis concerning H. pylori. The interactions of H. pylori with surrounding cells play a key role in cancer progression. In this review, we discuss the interplay between H. pylori and tumor-supportive cells, including mesenchymal stem cells (MSCs), cancer-associated fibroblasts (CAFs), tumor-associated macrophages (TAMs), and myeloid derived-suppressor cells (MDSCs) in gastric cancer. It is hoped that clarifying the specific mechanisms for 'cross-talk' between H. pylori and these cells will provide promising strategies for developing new treatments.

Effects of helicobacter pylori on tumor microenvironment and immunotherapy responses

Helicobacter pylori is closely associated with gastric cancer. During persistent infection, Helicobacter pylori can form a microenvironment in gastric mucosa which facilitates the survival and colony formation of Helicobacter pylori. Tumor stromal cells are involved in this process, including tumor-associated macrophages, mesenchymal stem cells, cancer-associated fibroblasts, and myeloid-derived suppressor cells, and so on. The immune checkpoints are also regulated by Helicobacter pylori infection. Helicobacter pylori virulence factors can also act as immunogens or adjuvants to elicit or enhance immune responses, indicating their potential applications in vaccine development and tumor immunotherapy. This review highlights the effects of Helicobacter pylori on the immune microenvironment and its potential roles in tumor immunotherapy responses.

Helicobacter pylori infection induces stem cell-like properties in Correa cascade of gastric cancer

Gastric cancer (GC) is the fourth leading cause of cancer-related death. Its poor prognosis is attributed to unclear pathogenesis. Currently, the most widely accepted model for elucidating the mechanism of GC is the Correa cascade, which covers several histological lesions of the gastric mucosa. GC stem cells (CSCs) are crucial for oncogenesis in the Correa cascade and GC progression. As Helicobacter pylori (H. pylori) is the etiological factor in the Correa cascade, growing evidence suggests that enhancement of gastric stem cell-like properties and increase in CSCs correlate with H. pylori infection. In this paper, we review recent studies that present pathogenic mechanisms by which H. pylori induces gastric stem cell-like properties and CSCs, which may supplement the existing Correa model of GC. First, the dysfunction of developmental signaling pathways associated with H. pylori infection leads to the enhancement of gastric stemness. Second, H. pylori infection promotes alteration of the gastric mucosal microenvironment. In addition, epithelial-mesenchymal transition (EMT) may contribute to H. pylori-induced gastric stemness. Taken together, understanding these pathogeneses will provide potential therapeutic targets for the treatment of CSCs and malignant GC in H. pylori induced-Correa cascade of GC.

Knockdown of circHECTD1 inhibits oxygen-glucose deprivation and reperfusion induced endothelial-mesenchymal transition

Ischemic stroke (IS) has become a cerebrovascular disease which seriously threatens the elderly people. It has been reported that circRNAs participate in multiple diseases, including IS. However, the role of circHECTD1 in IS remains largely unknown. To mimic IS in vitro, human cerebral microvascular endothelial cells (HCMECs) were treated with oxygen glucose deprivation/reperfusion (OGD/R). Meanwhile, MCAO mouse model was established to detect the expression of circHECTD1 in IS. qRT-PCR and western blot were used to test gene and protein expressions, respectively. CCK-8 assay was used to investigate the cell viability. Moreover, cell migration and tube formation were assessed by transwell and tube formation assays. In addition, RIP and luciferase assay were performed to explore the association among circHECTD1, miR-335 and NOTCH2. CircHECTD1 was significantly upregulated in IS. OGD/R significantly induced EndoMT in HCMECs, while knockdown of circHECTD1 notably reversed this phenomenon. In addition, silencing of circHECTD1 remarkably reversed OGD/R-induced promotion of HCMEC tube formation and migration. Meanwhile, circHECTD1 upregulated the level of NOTCH2 through binding with miR-335. Furthermore, miR-335 inhibited the process of EndoMT in IS via targeting NOTCH2. In summary, circHECTD1 knockdown significantly alleviated EndoMT process in HCMECs via mediation of miR-335/NOTCH2 axis. Thus, circHECTD1 might act as a potential target against IS.

Treponema denticola Promotes OSCC Development via the TGF-β Signaling Pathway

Numerous studies have demonstrated an association between periodontitis and oral squamous cell carcinoma (OSCC), and periodontal pathogens such as Treponema denticola are implicated in the pathogenesis of OSCC. Previous studies have mainly focused on T. denticola surface proteins—for example, chymotrypsin-like proteinase, which was detected in the majority of orodigestive tumor tissues. T. denticola may influence the development of OSCC. Nevertheless, the potential direct regulatory mechanism of T. denticola in OSCC is still unclear. Therefore, this study aimed to explore the direct effect of T. denticola on OSCC cell proliferation and elucidate potential mechanisms of T. denticola in contributing to cell proliferation. A series of in vitro experiments (e.g., CCK-8, EdU, flow cytometry) were performed to explore the effect of T. denticola on cell proliferation, cell cycle, and apoptosis. Mice experiments were performed to explore the effect of T. denticola on tumor growth. Whole mRNA transcriptome sequencing and quantitative real-time polymerase chain reaction were performed to explore the intracellular signaling pathway. Our study found that T. denticola could invade Cal-27 cells and directly promote cell proliferation, regulate the cell cycle, and inhibit apoptosis. T. denticola could also promote the growth of OSCC tumors in mice, and it upregulated Ki67 expression. Regarding the mechanism, T. denticola could promote the development of OSCC by activating the TGF-β pathway. In conclusion, T. denticola could promote OSCC cell proliferation directly, and the mechanism was associated with intracellular TGF-β pathway activation.

MicroRNA-370-3p shuttled by breast cancer cell-derived extracellular vesicles induces fibroblast activation through the CYLD/Nf-κB axis to promote breast cancer progression

Breast cancer is a malignancy arising in the mammary epithelial tissues. Recent studies have indicated the abundance of microRNAs (miRNAs) in extracellular vesicles (EVs), and their interactions have been illustrated to exert crucial roles in the cell-to-cell communication. The present study focused on investigating whether EV-delivered miR-370-3p affects breast cancer. Initially, the miR-370-3p expression pattern was examined in the cancer-associated fibroblasts (CAFs), normal fibroblasts (NFs), and cancerous cells-derived EVs. The relation of miR-370-3p to CYLD was assessed using luciferase activity assay. Afterwards, based on ectopic expression and depletion experiments in the MCF-7 breast cancer cells, we evaluated stemness, migration, invasion, and sphere formation ability, and EMT, accompanied with measurement on the expression patterns of pro-inflammatory factors and nuclear factor-kappa B (NF-κB) signaling-related genes. Finally, tumorigenesis and proliferation were analyzed in vivo using a nude mouse xenograft model. The in vitro experiments revealed that breast cancer cell-derived EVs promoted NF activation, while activated fibroblasts contributed to enhanced stemness, migration, invasion, as well as EMT of cancerous cells. In addition, EVs could transfer miR-370-3p from breast cancer cells to NFs, and EV-encapsulated miR-370-3p was also found to facilitate fibroblast activation. Mechanistically, EV-encapsulated miR-370-3p downregulated the expression of CYLD through binding to its 3'UTR and activated the NF-κB signaling pathway, thereby promoting the cellular functions in vitro and in vivo in breast cancer. Taken together, EVs secreted by breast cancer cells could carry miR-370-3p to aggravate breast cancer through downregulating CYLD expression and activating the NF-κB signaling pathway.

Gastric Cancer: Advances in Carcinogenesis Research and New Therapeutic Strategies

Gastric cancer’s bad incidence, prognosis, cellular and molecular heterogeneity amongst others make this disease a major health issue worldwide. Understanding this affliction is a priority for proper patients’ management and for the development of efficient therapeutical strategies. This review gives an overview of major scientific advances, made during the past 5-years, to improve the comprehension of gastric adenocarcinoma. A focus was made on the different actors of gastric carcinogenesis, including, Helicobacter pylori cancer stem cells, tumour microenvironment and microbiota. New and recent potential biomarkers were assessed as well as emerging therapeutical strategies involving cancer stem cells targeting as well as immunotherapy. Finally, recent experimental models to study this highly complex disease were discussed, highlighting the importance of gastric cancer understanding in the hard-fought struggle against cancer relapse, metastasis and bad prognosis.

Organic carbon monoxide prodrug, BW-CO-111, in protection against chemically-induced gastric mucosal damage

Metal-based carbon monoxide (CO)-releasing molecules have been shown to exert anti-inflammatory and anti-oxidative properties maintaining gastric mucosal integrity. We are interested in further development of metal-free CO-based therapeutics for oral administration. Thus, we examine the protective effect of representative CO prodrug, BW-CO-111, in rat models of gastric damage induced by necrotic ethanol or aspirin, a representative non-steroidal anti-inflammatory drug. Treatment effectiveness was assessed by measuring the microscopic/macroscopic gastric damage area and gastric blood flow by laser flowmetry. Gastric mucosal mRNA and/or protein expressions of HMOX1, HMOX2, nuclear factor erythroid 2-related factor 2, COX1, COX2, iNos, Anxa1 and serum contents of TGFB1, TGFB2, IL1B, IL2, IL4, IL5, IL6, IL10, IL12, tumor necrosis factor α, interferon γ, and GM-CSF were determined. CO content in gastric mucosa was assessed by gas chromatography. Pretreatment with BW-CO-111 (0.1 mg/kg, i.g.) increased gastric mucosal content of CO and reduced gastric lesions area in both models followed by increased GBF. These protective effects of the CO prodrug were supported by changes in expressions of molecular biomarkers. However, because the pathomechanisms of gastric damage differ between topical administration of ethanol and aspirin, the possible protective and anti-inflammatory mechanisms of BW-CO-111 may be somewhat different in these models.

Dendritic cell-derived TGF-β mediates the induction of mucosal regulatory T-cell response to Helicobacter infection essential for maintenance of immune tolerance in mice

BACKGROUND

Helicobacter pylori infection leads to regulatory T-cell (Treg) induction in infected mice, which contributes to H. pylori immune escape. However, the mechanisms responsible for H. pylori induction of Treg and immune tolerance remain unclear. We hypothesized DC-produced TGF-β may be responsible for Treg induction and immune tolerance.

MATERIALS AND METHODS

To test this hypothesis, we generated TGF-β^∆DC mice (CD11c⁺ DC-specific TGF-β deletion) and assessed the impact of DC-specific TGF-β deletion on DC function during Helicobacter infection in vitro and in vivo. To examine the T cell-independent DC function, we crossed TGF-β^∆DC mice onto Rag1KO background to generate TGF-β^∆DC xRag1KO mice.

RESULTS

When stimulated with H. pylori, TGF-β^∆DC BMDC/splenocyte cocultures showed increased levels of proinflammatory cytokines and decreased levels of anti-inflammatory cytokines compared to control, indicating a proinflammatory DC phenotype. Following 6 months of H. felis infection, TGF-β^∆DC mice developed more severe gastritis and a trend toward more metaplasia compared to TGF-β^fl/fl with increased levels of inflammatory Th1 cytokine mRNA and lower gastric H. felis colonization compared to infected TGF-β^fl/fl mice. In a T cell-deficient background using TGF-β^∆DC xRag1KO mice, H. felis colonization was significantly lower when DC-derived TGF-β was absent, revealing a direct, innate function of DC in controlling H. felis infection independent of Treg induction.

CONCLUSIONS

Our findings indicate that DC-derived TGF-β mediates Helicobacter-induced Treg response and attenuates the inflammatory Th1 response. We also demonstrated a previously unrecognized innate role of DC controlling Helicobacter colonization via a Treg-independent mechanism. DC TGF-β signaling may represent an important target in the management of H. pylori.

Long-Term Helicobacter pylori Infection Switches Gastric Epithelium Reprogramming Towards Cancer Stem Cell-Related Differentiation Program in Hp-Activated Gastric Fibroblast-TGFβ Dependent Manner

Helicobacter pylori (Hp)-induced inflammatory reaction leads to a persistent disturbance of gastric mucosa and chronic gastritis evidenced by deregulation of tissue self-renewal and local fibrosis with the crucial role of epithelial–mesenchymal transition (EMT) in this process. As we reported before, Hp activated gastric fibroblasts into cells possessing cancer-associated fibroblast properties (CAFs), which secreted factors responsible for EMT process initiation in normal gastric epithelial RGM1 cells. Here, we showed that the long-term incubation of RGM1 cells in the presence of Hp-activated gastric fibroblast (Hp-AGF) secretome induced their shift towards plastic LGR5⁺/Oct4^high/Sox-2^high/c-Myc^high/Klf4^low phenotype (l.t.EMT⁺RGM1 cells), while Hp-non-infected gastric fibroblast (GF) secretome prompted a permanent epithelial–myofibroblast transition (EMyoT) of RGM1 cells favoring LGR⁻/Oct4^high/Sox2^low/c-Myc^low/Klf4^high phenotype (l.t.EMT⁻RGM1 cells). TGFβ1 rich secretome from Hp-reprogrammed fibroblasts prompted phenotypic plasticity and EMT of gastric epithelium, inducing pro-neoplastic expansion of post-EMT cells in the presence of low TGFβR1 and TGFβR2 activity. In turn, TGFβR1 activity along with GF-induced TGFβR2 activation in l.t.EMT⁻RGM1 cells prompted their stromal phenotype. Collectively, our data show that infected and non-infected gastric fibroblast secretome induces alternative differentiation programs in gastric epithelium at least partially dependent on TGFβ signaling. Hp infection-activated fibroblasts can switch gastric epithelium microevolution towards cancer stem cell-related differentiation program that can potentially initiate gastric neoplasm.