IL-22 negatively regulates Helicobacter pylori-induced CCL20 expression in gastric epithelial cells

CCR6+ T helper cells and regulatory T cells in the blood and gastric mucosa during Helicobacter pylori infection

BACKGROUND

Helicobacter pylori (H. pylori) can evade the host's immune response and persist for a long time on the gastric mucosa. T helper (Th) cells appear to be involved in the control of H. pylori bacteria but promote mucosal inflammation. In contrast, regulatory T cells (Tregs) may reduce inflammation but promote H. pylori persistence. CC motif chemokine receptor 6 (CCR6) is involved in the migration of various cells into inflamed gastric mucosa. In this study, we examined CCR6+ Th cells and CCR6+ Tregs during H. pylori infection in humans.

MATERIALS AND METHODS

Isolation of cells from blood and mucosal biopsies, magnetic separation of В cells, CD4+ and CD4+CCR6+CD45RO+ T cells, antigen-specific activation, B cell response in vitro, flow cytometry, determination of CD4+CD25hiFoxP3+ Tregs and various groups of Th cells.

RESULTS

CD4+CCR6+ blood lymphocytes from healthy donors included Th cells and Tregs. These CCR6+ Th cells produced proinflammatory cytokines and also stimulated plasma cell maturation and antibody production in vitro. H. pylori gastritis and peptic ulcer disease were associated with an increase in the number of circulate CD4+CCR6+CD45RO+ cells and the percentage of Th1, Th17 and Th1/17 cells in this lymphocyte subgroup. In H. pylori-positive patients, circulating CD4+CCR6+ cells contained a higher proportion of H. pylori-specific cells compared with their CD4+CCR6- counterparts. H. pylori infection strongly increased the content of CD4+ lymphocytes in the inflamed gastric mucosa, with the majority of these CD4+ lymphocytes expressing CCR6. CD4+CCR6+ lymphocytes from H. pylori-infected stomach included Tregs and in vivo activated T cells, some of which produced interferon-γ without ex vivo stimulation.

CONCLUSION

H. pylori infection causes an increase in the number of mature CD4+CCR6+ lymphocytes in the blood, with a pro-inflammatory shift in their composition and enrichment of the gastric mucosa with CD4+CCR6+ lymphocytes, including CCR6+ Th1 cells and Tregs.

Comprehensive insight into altered host cell-signaling cascades upon Helicobacter pylori and Epstein-Barr virus infections in cancer

Cancer is characterized by mutagenic events that lead to disrupted cell signaling and cellular functions. It is one of the leading causes of death worldwide. Literature suggests that pathogens, mainly Helicobacter pylori and Epstein-Barr virus (EBV), have been associated with the etiology of human cancer. Notably, their co-infection may lead to gastric cancer. Pathogen-mediated DNA damage could be the first and crucial step in the carcinogenesis process that modulates numerous cellular signaling pathways. Altogether, it dysregulates the metabolic pathways linked with cell growth, apoptosis, and DNA repair. Modulation in these pathways leads to abnormal growth and proliferation. Several signaling pathways such RTK, RAS/MAPK, PI3K/Akt, NFκB, JAK/STAT, HIF1α, and Wnt/β-catenin are known to be altered in cancer. Therefore, this review focuses on the oncogenic roles of H. pylori, EBV, and its associated signaling cascades in various cancers. Scrutinizing these signaling pathways is crucial and may provide new insights and targets for preventing and treating H. pylori and EBV-associated cancers.

Chronic Lymphocytic Leukemia Causing Gastric Ulcer Perforation: A Case Presentation and Literature Review

Chronic lymphocytic leukemia (CLL) is a malignancy characterized by the progressive accumulation of lymphocytes in the bone marrow and lymphoid organs. Gastrointestinal manifestations are rare in all types of leukemia. Generally, this occurs during relapsing disease or in acute leukemias; however, recent advancements in treatment have reduced these complications. Most commonly, lesions in the stomach are hemorrhagic, and lesions in the lower gastrointestinal tract present as peritonitis or colitis. Our patient was unique because she had a perforated, rather than bleeding, peptic ulcer caused by infiltrative chronic lymphocytic leukemia after starting ibrutinib. Although this medication can impair wound healing and/or cause bleeding, there are no reports of perforation of existing ulcers. Additionally, chronic lymphocytic leukemia causing perforated peptic ulcer disease (PUD) is rare, and this is, to our knowledge, the first case of this phenomenon.

Ginger Extract Modulates the Production of Chemokines CCL17, CCL20, CCL22, and CXCL10 and the Gene Expression of Their Receptors in Peripheral Blood Mononuclear Cells from Peptic Ulcer Patients Infected with Helicobacter pylori

Background: The imbalanced expression of chemokines plays critical role in the development of Helicobacter pylori-mediated complications. Objectives: Our aim was to determine ginger extract (GE) effects on the expression of chemokines CCL17, CCL20, CCL22, and CXCL10, as well as CCR4, CCR6, and CXCR3 receptors by peripheral blood mononuclear cells (PBMCs) from H. pylori -infected patients with peptic ulcer (PU). Methods: Peripheral blood mononuclear cells were obtained from 20 patients with H. pylori-associated PU, 20 H. pylori-infected asymptomatic subjects (HAS), and 20 non-infected healthy subjects (NHS). The PBMCs were stimulated by 10 µg/mL of H. pylori-derived crude extract (HPCE) in the presence of 0, 10, 20, and 30 µg/mL of GE. After 36 hours, the supernatant and the RNA extracted from the cells were tested for chemokine concentration and chemokine receptor expression using ELISA and real-time PCR techniques, respectively. Results: In PU patients, treating HPCE-stimulated PBMCs with 10, 20, or 30 µg/mL GE reduced the production of CXCL10 (1.47, 1.5, and 1.53 folds, respectively, P < 0.001 for all), CCL20 (1.44, 1.62, and 1.65 folds, respectively, P < 0.003), and treatment with 30 µg/mL GE increased CCL17 (1.28-fold, P < 0.001) and CCL22 (1.59-fold, P < 0.001) production compared with untreated HPCE-stimulated PBMCs. In PU patients, the HPCE-stimulated PBMCs treated with 10, 20, or 30 µg/mL GE expressed lower levels of CXCR3 (1.9, 3, and 3.5 folds, respectively, P < 0.001) and CCR6 (2.3, 2.7, and 2.8 folds, respectively, P < 0.002) while treating with 10 µg/mL GE upregulated CCR4 (1.7 fold, P = 0.003) compared with untreated HPCE-stimulated PBMCs. Conclusions: Ginger extract modulated the expression of chemokines and their receptors in the PBMCs derived from H. pylori-infected PU patients. The therapeutic potentials of ginger for treating HP-related complications need to be further explored.

T Cell Cytokines Impact Epithelial Cell Responses during Helicobacter pylori Infection

The goal of this Brief Review is to highlight literature that demonstrates how cytokines made by T lymphocytes impact the gastric epithelium, especially during Helicobacter pylori infection. These cytokines effect many of the diverse functions of the epithelium and the epithelium's interactions with H. pylori The focal point of this Brief Review will be on how T cell cytokines impact antimicrobial function and barrier function and how T cell cytokines influence the development and progression of cancer. Furthermore, the modulation of epithelial-derived chemokines by H. pylori infection will be discussed.

Microbiota-Dependent Effects of IL-22

Cytokines are important contributors to immune responses against microbial and environmental threats and are of particular importance at epithelial barriers. These interfaces are continuously exposed to external factors and thus require immune components to both protect the host from pathogen invasion and to regulate overt inflammation. Recently, substantial efforts have been devoted to understanding how cytokines act on certain cells at barrier sites, and why the dysregulation of immune responses may lead to pathogenesis. In particular, the cytokine IL-22 is involved in preserving an intact epithelium, maintaining a balanced microbiota and a functioning defense system against external threats. However, a tight regulation of IL-22 is generally needed, since uncontrolled IL-22 production can lead to the progression of autoimmunity and cancer. Our aim in this review is to summarize novel findings on IL-22 and its interactions with specific microbial stimuli, and subsequently, to understand their contributions to the function of IL-22 and the clinical outcome. We particularly focus on understanding the detrimental effects of dysregulated control of IL-22 in certain disease contexts.

Keratinocyte transglutaminase 2 promotes CCR6+ γδT-cell recruitment by upregulating CCL20 in psoriatic inflammation

Keratinocyte-derived cytokines and chemokines amplify psoriatic inflammation by recruiting IL-17-producing CCR6⁺ γδT-cells and neutrophils. The expression of these cytokines and chemokines mainly depends on NF-κB activity; however, the pathway that activates NF-κB in response to triggering factors is poorly defined. Here, we show that transglutaminase 2 (TG2), previously reported to elicit a T_H17 response by increasing IL-6 expression in a mouse model of lung fibrosis, mediates the upregulation of cytokines and chemokines by activating NF-κB in imiquimod (IMQ)-treated keratinocytes. TG2-deficient mice exhibited reduced psoriatic inflammation in skin treated with IMQ but showed systemic immune responses similar to wild-type mice. Experiments in bone marrow (BM) chimeric mice revealed that TG2 is responsible for promoting psoriatic inflammation in non-BM-derived cells. In keratinocytes, IMQ treatment activated TG2, which in turn activated NF-κB signaling, leading to the upregulation of IL-6, CCL20, and CXCL8 and increased leukocyte migration, in vitro. Consequently, TG2-deficient mice showed markedly decreased CCR6⁺ γδT-cell and neutrophil infiltration in IMQ-treated skin. Moreover, TG2 levels were higher in psoriatic skin than in normal skin and correlated with IL-6, CXCL8, and CCL20 levels. Therefore, these results indicate that keratinocyte TG2 acts as a critical mediator in the amplification of psoriatic inflammation.

PUMA-mediated epithelial cell apoptosis promotes Helicobacter pylori infection-mediated gastritis

The molecular mechanism responsible for Helicobacter pylori infection-mediated gastritis and carcinogenesis is not yet clear. Increased evidence suggests that chronic gastritis and elevated gastric epithelial cell (GEC) apoptosis are crucial events during stomach carcinoma transformation. PUMA is a potent proapoptotic Bcl-2 protein and mediates acute tissue injury. In this study, we aimed to investigate the role of PUMA in GEC apoptosis and inflammation induced by H. pylori infection. As a result, we found that PUMA expression was elevated in gastritis tissues compared with uninvolved tissues, and it was correlated with the severity of apoptosis and gastritis. In mice, PUMA mRNA and protein were markedly induced in GECs upon induction of gastritis by H. pylori. PUMA-deficient mice were highly resistant to apoptosis and gastritis induced by H. pylori. Furthermore, the transcription factor NF-κB p65 binds to PUMA promoter to activate PUMA transcription after H. pylori infection. In addition, NF-κB inhibitor could rescue H. pylori-induced apoptosis and gastritis. Finally, H. pylori-induced activation of p-p65 and PUMA was mediated via Toll-like receptor 2 (TLR2) and blocked in TLR2 knockout mice. Taken together, these results verified the pro-inflammatory effect of PUMA in H. pylori-infected gastric tissue. Moreover, TLR2/NF-κB-mediated transcriptional regulation of PUMA contributes to the pathogenesis of H. pylori-infected gastritis.

The important role played by chemokines influence the clinical outcome of Helicobacter pylori infection

The extended infection with Helicobacter pylori (H. pylori), one of the most frequent infectious agents in humans, may cause gastritis, peptic ulcers, gastric mucosa-associated lymphoid tissue (MALT) lymphoma, and gastric cancer. During H. pylori infection, different kinds of inflammatory cells such as dendritic cells, macrophages, neutrophils, mast cells, eosinophils, T cells and B cells are accumulated into the stomach. The interactions between chemokines and their respective receptors recruit particular types of the leukocytes that ultimately determine the nature of immune response and therefore, have a main influence on the consequence of infection. The suitable production of chemokines especially in the early stages of H. pylori infection shapes appropriate immune responses that contribute to the H. pylori elimination. The unbalanced expression of the chemokines can contribute in the induction of inappropriate responses that result in the tissue damage or malignancy. Thus, chemokines and their receptors may be promising potential targets for designing the therapeutic strategies against various types H. pylori-related gastrointestinal disorders. In this review, a comprehensive explanation regarding the roles played by chemokines in H. pylori-mediated peptic ulcer, gastritis and gastric malignancies was provided while presenting the potential utilization of these chemoattractants as therapeutic elements.

Circulating inflammation-related markers and advanced gastric premalignant lesions

BACKGROUND AND AIM

Chronic Helicobacter pylori infection causes gastric mucosal inflammation as an important antecedent of gastric cancer. We aimed to evaluate associations of blood markers of inflammation with gastric intestinal metaplasia and dysplasia in H. pylori-infected individuals.

METHODS

We compared pre-treatment serum levels of immune-related and inflammation-related markers between 99 individuals with intestinal metaplasia or dysplasia and 75 control individuals with non-atrophic gastritis within an H. pylori eradication trial in Mexico. Serum levels of 28 markers measured with Luminex bead-based assays were categorized in tertiles as low (T1), middle (T2), and high (T3). Logistic regression models were used to calculate age-adjusted and sex-adjusted odds ratios and 95% confidence intervals. All statistical tests were two-sided, and significance values were adjusted for multiple comparisons using false discovery rate methods.

RESULTS

Five markers were nominally associated (P_trend  < 0.05) with the presence of advanced premalignant gastric lesions. Adjusted odds ratios (95% confidence interval) of T2 and T3 versus T1 were 4.09 (1.65-10.17) and 3.08 (1.23-7.68) for CCL3/MIP1A, 3.21 (1.33-7.75) and 2.69 (1.10-6.57) for CCL20/MIP3A levels, 1.79 (0.77-4.18) and 2.39 (1.02-5.60) for IL-1β, 1.34 (0.56-3.19) and 3.02 (1.29-7.12) for IL-4, and 1.07 (0.44-2.59) and 3.07 (1.32-7.14) for IL-5, respectively. Two (IL-4 and IL-5) of the five markers had false discovery rate adjusted P_trend  < 0.2.

CONCLUSIONS

Our results suggest that certain Th2 and other cytokines may have a role in promoting carcinogenesis in the setting of H. pylori infection. Additional research is needed to replicate these findings, extend to pre-diagnostic samples, and elucidate the underlying mechanisms.

Novel Insights of Lymphomagenesis of Helicobacter pylori-Dependent Gastric Mucosa-Associated Lymphoid Tissue Lymphoma

Gastric mucosa-associated lymphoid tissue (MALT) lymphoma is the most common subtype of gastric lymphoma. Most gastric MALT lymphomas are characterized by their association with the Helicobacter pylori (HP) infection and are cured by first-line HP eradication therapy (HPE). Several studies have been conducted to investigate why most gastric MALT lymphomas remain localized, are dependent on HP infection, and show HP-specific intratumoral T-cells (e.g., CD40-mediated signaling, T-helper-2 (Th2)-type cytokines, chemokines, costimulatory molecules, and FOXP3+ regulatory T-cells) and their communication with B-cells. Furthermore, the reason why the antigen stimuli of these intratumoral T-cells with tonic B-cell receptor signaling promote lymphomagenesis of gastric MALT lymphoma has also been investigated. In addition to the aforementioned mechanisms, it has been demonstrated that the translocated HP cytotoxin-associated gene A (CagA) can promote B-cell proliferation through the activation of Src homology-2 domain-containing phosphatase (SHP-2) phosphorylation-dependent signaling, extracellular-signal-regulated kinase (ERK), p38 mitogen-activated protein kinase (MAPK), B-cell lymphoma (Bcl)-2, and Bcl-xL. Furthermore, the expression of CagA and these CagA-signaling molecules is closely associated with the HP-dependence of gastric MALT lymphomas (completely respond to first-line HPE). In this article, we summarize evidence of the classical theory of HP-reactive T-cells and the new paradigm of direct interaction between HP and B-cells that contributes to the HP-dependent lymphomagenesis of gastric MALT lymphomas. Although the role of first-line HPE in the treatment of HP-negative gastric MALT lymphoma remains uncertain, several case series suggest that a proportion of HP-negative gastric MALT lymphomas remains antibiotic-responsive and is cured by HPE. Considering the complicated interaction between microbiomes and the genome/epigenome, further studies on the precise mechanisms of HP- and other bacteria-directed lymphomagenesis in antibiotic-responsive gastric MALT lymphomas are warranted.

Oral Administration of Lactobacillus rhamnosus GG Ameliorates Salmonella Infantis-Induced Inflammation in a Pig Model via Activation of the IL-22BP/IL-22/STAT3 Pathway

The high rate of Salmonella enterica serovar Infantis (S. Infantis) infection poses significant risk for the development of non-typhoidal Salmonella gastroenteritis. However, efficient strategies to prevent or treat the infection remain elusive. Here, we explored the effect of the probiotic Lactobacillus rhamnosus GG (LGG) administration in preventing S. Infantis infection in a pig model. Probiotic LGG (1.0 × 1010 CFU/day) was orally administered to newly weaned piglets for 1 week before S. Infantis challenge. LGG pretreatment reduced the severity of diarrhea and alleviated intestinal inflammation caused by S. Infantis. Pre-administration of LGG excluded Salmonella from colonization of the jejunal mucosa but increased the abundance of Bifidobacterium in the feces. LGG promoted the expansion of CD4+ T-bet+ IFNγ+ T cells but attenuated S. Infantis-induced increases in the percentage of CD4+ IFNγ+ T cells and serum interleukin (IL)-22 levels in peripheral blood after S. Infantis challenge. In the small intestine, LGG pretreatment upregulated expression of the transcription factor T-bet but downregulated the S. Infantis-induced increase of CD4+ IFNγ+ T cells in Peyer's patches and IL-7Rα expression in the jejunum. Notably, LGG-treated pigs had enhanced expression of IL-22 and activated STAT3 in the ileum in response to S. Infantis infection. Pretreatment of pigs with LGG also elevated intestinal IL-22-binding protein production in response to S. Infantis challenge. In contrast, LGG consumption reduced the S. Infantis-induced increase in the number of CCL20-expressing cells in the jejunum. Our results suggest that the mechanism by which LGG ameliorates the intestinal inflammation caused by S. Infantis involves the upregulation of T-bet, activation of STAT3, and downregulation of CCL20.

NF-κB Signaling in Gastric Cancer

Gastric cancer is a leading cause of cancer death worldwide. Diet, obesity, smoking and chronic infections, especially with Helicobacter pylori, contribute to stomach cancer development. H. pylori possesses a variety of virulence factors including encoded factors from the cytotoxin-associated gene pathogenicity island (cagPAI) or vacuolating cytotoxin A (VacA). Most of the cagPAI-encoded products form a type 4 secretion system (T4SS), a pilus-like macromolecular transporter, which translocates CagA into the cytoplasm of the host cell. Only H. pylori strains carrying the cagPAI induce the transcription factor NF-κB, but CagA and VacA are dispensable for direct NF-κB activation. NF-κB-driven gene products include cytokines/chemokines, growth factors, anti-apoptotic factors, angiogenesis regulators and metalloproteinases. Many of the genes transcribed by NF-κB promote gastric carcinogenesis. Since it has been shown that chemotherapy-caused cellular stress could elicit activation of the survival factor NF-κB, which leads to acquisition of chemoresistance, the NF-κB system is recommended for therapeutic targeting. Research is motivated for further search of predisposing conditions, diagnostic markers and efficient drugs to improve significantly the overall survival of patients. In this review, we provide an overview about mechanisms and consequences of NF-κB activation in gastric mucosa in order to understand the role of NF-κB in gastric carcinogenesis.

IL-17a and IL-22 Induce Expression of Antimicrobials in Gastrointestinal Epithelial Cells and May Contribute to Epithelial Cell Defense against Helicobacter pylori

Helicobacter pylori colonization of the human stomach can lead to adverse clinical outcomes including gastritis, peptic ulcers, or gastric cancer. Current data suggest that in addition to bacterial virulence factors, the magnitude and types of immune responses influence the outcome of colonization. Specifically, CD4+ T cell responses impact the pathology elicited in response to H. pylori. Because gastritis is believed to be the initiating host response to more detrimental pathological outcomes, there has been a significant interest in pro-inflammatory T cell cytokines, including the cytokines produced by T helper 17 cells. Th17 cells produce IL-17A, IL-17F, IL-21 and IL-22. While these cytokines have been linked to inflammation, IL-17A and IL-22 are also associated with anti-microbial responses and control of bacterial colonization. The goal of this research was to determine the role of IL-22 in activation of antimicrobial responses in models of H. pylori infection using human gastric epithelial cell lines and the mouse model of H. pylori infection. Our data indicate that IL-17A and IL-22 work synergistically to induce antimicrobials and chemokines such as IL-8, components of calprotectin (CP), lipocalin (LCN) and some β-defensins in both human and primary mouse gastric epithelial cells (GEC) and gastroids. Moreover, IL-22 and IL-17A-activated GECs were capable of inhibiting growth of H. pylori in vitro. While antimicrobials were activated by IL-17A and IL-22 in vitro, using a mouse model of H. pylori infection, the data herein indicate that IL-22 deficiency alone does not render mice more susceptible to infection, change their antimicrobial gene transcription, or significantly change their inflammatory response.

Helicobacter pylori cytotoxin-associated gene A activates tumor necrosis factor-α and interleukin-6 in gastric epithelial cells through P300/CBP-associated factor-mediated nuclear factor-κB p65 acetylation

Helicobacter pylori‑initiated chronic gastritis is characterized by the cytotoxin‑associated gene (Cag) pathogenicity island‑dependent upregulation of pro‑inflammatory cytokines in gastric epithelial cells, which is largely mediated by the activation of nuclear factor (NF)‑κB as a transcription factor. However, the precise regulation of NF‑κB activation, particularly post‑translational modifications in the CagA‑induced inflammatory response, has remained elusive. The present study showed that Helicobacter pylori CagA, an important virulence factor, induced the expression of P300/CBP‑associated factor (PCAF) in gastric epithelial cells. Further study revealed that PCAF was able to physically associate with the NF‑κB p65 sub‑unit and enhance its acetylation. More importantly, PCAF‑induced p65 acetylation was shown to contribute to p65 phosphorylation and further upregulation of tumor necrosis factor (TNF)‑α and interleukin (IL)‑6 in gastric adenocarcinoma cells. In conclusion, the results of the present study indicated that Helicobacter pylori CagA enhanced TNF‑α and IL‑6 in gastric adenocarcinoma cells through PCAF‑mediated NF‑κB p65 sub‑unit acetylation.