Helicobacter pylori infection in a pig model is dominated by Th1 and cytotoxic CD8+ T cell responses

Mucosal Immunity Related to CD8+ T Lymphocytes in Children with Helicobacter pylori Gastritis

Purpose

We investigated the role of CD8+T cells as host immune factors in pediatric patients with Helicobacter pylori gastritis.

Methods

Gastric mucosal tissue and blood samples were collected from 39 children, including 11 children with H. pylori infection and 28 children as controls. Anti-CD8 and anti-T-bet antibodies were used for immunohistochemistry of the gastric mucosa. For the cell surface and intracellular staining, peripheral blood mononuclear cells were stained with anti-IL7Rα, anti-CX3CR1, anti-CD8, anti-T-bet, and anti-IFN-γ antibodies. Cytokines of sera such as tumor necrosis factor alpha (TNF-α) and CX3CL1 were analyzed using enzyme- linked immunosorbent assay (ELISA).

Results

In the immunohistochemistry of gastric mucosa, the frequency of CD8+ and T-bet+ T cells cells was higher in the H. pylori-positive group than in the control group (26.9± 7.8% vs. 16.9±3.3%, p<0.001; 5.0±2.5% vs. 2.2±0.7%, p=0.001). Between the control and H. pylori-positive groups, the frequency of IL-7RαlowCX3CR1+ CD8+ and T-bet+ INF-γ+ CD8+ T cells were not significantly different between surface and intracellular staining, respectively (40.4±24.0% vs. 38.2±17.8%, p=0.914; 40.4±24.0% vs. 38.2±17.8%, p=0.914). In the ELISA, no significant differences in TNF-α and CX3CL1 concentrations were observed between the control and H. pylori-positive groups (34.3±12.1 pg/mL vs. 47.0±22.6 pg/mL, p=0.114/0.5± 0.1 pg/mL vs. 0.5±0.1 pg/mL, p=0.188).

Conclusion

CD8+ T and Th1 cells, which secrete IFN-γ, might play important roles in the mucosal immunity of the stomach in children with H. pylori infection.

Composition of mucus- and digesta-associated bacteria in growing pigs with and without diarrhea differed according to the presence of colonic inflammation

BACKGROUND

In the pig production, diarrhea can occur during different growth stages including the period 4-16 weeks post weaning, during which a diarrheal outbreak also termed as colitis-complex diarrhea (CCD) can occur and it is distinct from post-weaning diarrhea (1-2 weeks post weaning). We hypothesized that CCD in growing pigs is associated with changes in colonic microbiota composition and fermentation patterns, and the aim of the present observational study was to identify changes in digesta-associated bacteria (DAB) and mucus-associated bacteria (MAB) in the colon of growing pigs with and without diarrhea. A total number of 30 pigs (8, 11, and 12 weeks of age) were selected; 20 showed clinical signs of diarrhea and 10 appeared healthy. Based on histopathological examination of colonic tissues, 21 pigs were selected for further studies and classified as follows: without diarrhea, no colon inflammation (NoDiar; n = 5), with diarrhea, without colonic inflammation (DiarNoInfl; n = 4), and with diarrhea, with colonic inflammation (DiarInfl; n = 12). Composition (based on 16S rRNA gene amplicon sequencing) and fermentation pattern (short-chain fatty acids; SCFA profile) of the DAB and MAB communities were characterized.

RESULTS

The DAB showed higher alpha diversity compared to MAB in all pigs, and both DAB and MAB showed lowest alpha diversity in the DiarNoInfl group. Beta diversity was significantly different between DAB and MAB as well as between diarrheal groups in both DAB and MAB. Compared to NoDiar, DiarInfl showed increased abundance of various taxa, incl. certain pathogens, in both digesta and mucus, as well as decreased digesta butyrate concentration. However, DiarNoInfl showed reduced abundance of different genera (mainly Firmicutes) compared to NoDiar, but still lower butyrate concentration.

CONCLUSION

Diversity and composition of MAB and DAB changed in diarrheal groups depending on presence/absence of colonic inflammation. We also suggest that DiarNoInfl group was at the earlier stage of diarrhea compared with DiarInfl, with a link to dysbiosis of colonic bacterial composition as well as reduced butyrate concentration, which plays a pivotal role in gut health. This could have led to diarrhea with inflammation due to a dysbiosis, associated with an increase in e.g., Escherichia-Shigella (Proteobacteria), Helicobacter (Campylobacterota), and Bifidobacterium (Actinobacteriota), which may tolerate or utilize oxygen and cause epithelial hypoxia and inflammation. The increased consumption of oxygen in epithelial mucosal layer by infiltrated neutrophils may also have added up to this hypoxia. Overall, the results confirmed that changes in DAB and MAB were associated with CCD and reduced butyrate concentration in digesta. Moreover, DAB might suffice for future community-based studies of CCD.

CagA-specific Gastric CD8+ Tissue-Resident T Cells Control Helicobacter pylori During the Early Infection Phase

BACKGROUND & AIMS

Infection with Helicobacter pylori strongly affects global health by causing chronic gastritis, ulcer disease, and gastric cancer. Although extensive research into the strong immune response against this persistently colonizing bacterium exists, the specific role of CD8⁺ T cells remains elusive.

METHODS

We comprehensively characterize gastric H pylori-specific CD8⁺ T-cell responses in mice and humans by flow cytometry, RNA-sequencing, immunohistochemistry, and ChipCytometry, applying functional analyses including T-cell depletion, H pylori eradication, and ex vivo restimulation.

RESULTS

We define CD8⁺ T-cell populations bearing a tissue-resident memory (T_RM) phenotype, which infiltrate the gastric mucosa shortly after infection and mediate pathogen control by executing antigen-specific effector properties. These induced CD8⁺ tissue-resident memory T cells (T_RM cells) show a skewed T-cell receptor beta chain usage and are mostly specific for cytotoxin-associated gene A, the distinctive oncoprotein injected by H pylori into host cells. As the infection progresses, we observe a loss of the T_RM phenotype and replacement of CD8⁺ by CD4⁺ T cells, indicating a shift in the immune response during the chronic infection phase.

CONCLUSIONS

Our results point toward a hitherto unknown role of CD8⁺ T-cell response in this bacterial infection, which may have important clinical implications for treatment and vaccination strategies against H pylori.

Gastric immune homeostasis imbalance: An important factor in the development of gastric mucosal diseases

The gastric mucosal immune system is a unique immune organ independent of systemic immunity that not only maintains nutrient absorption but also plays a role in resisting the external environment. Gastric mucosal immune disorder leads to a series of gastric mucosal diseases, including autoimmune gastritis (AIG)-related diseases, Helicobacter pylori (H. pylori)-induced diseases, and various types of gastric cancer (GC). Therefore, understanding the role of gastric mucosal immune homeostasis in gastric mucosal protection and the relationship between mucosal immunity and gastric mucosal diseases is very important. This review focuses on the protective effect of gastric mucosal immune homeostasis on the gastric mucosa, as well as multiple gastric mucosal diseases caused by gastric immune disorders. We hope to offer new prospects for the prevention and treatment of gastric mucosal diseases.

Local and Systemic T Cell Immunity in Fighting Pig Viral and Bacterial Infections

T cells are an essential component of the adaptive immune system. Over the last 15 years, a constantly growing toolbox with which to study T cell biology in pigs has allowed detailed investigations on these cells in various viral and bacterial infections. This review provides an overview on porcine CD4, CD8, and γδ T cells and the current knowledge on the differentiation of these cells following antigen encounter. Where available, the responses of these cells to viral infections like porcine reproductive and respiratory syndrome virus, classical swine fever virus, swine influenza A virus, and African swine fever virus are outlined. In addition, knowledge on the porcine T cell response to bacterial infections like Actinobacillus pleuropneumoniae and Salmonella Typhimurium is reviewed. For CD4 T cells, the response to the outlined infections is reflected toward the Th1/Th2/Th17/Tfh/Treg paradigm for functional differentiation. Expected final online publication date for the Annual Review of Animal Biosciences, Volume 10 is February 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Swine as biomedical animal model for T-cell research-Success and potential for transmittable and non-transmittable human diseases

Swine is biologically one of the most relevant large animal models for biomedical research. With its use as food animal that can be exploited as a free cell and tissue source for research and its high susceptibility to human diseases, swine additionally represent an excellent option for both the 3R principle and One Health research. One of the previously most limiting factors of the pig model was its arguably limited immunological toolbox. Yet, in the last decade, this toolbox has vastly improved including the ability to study porcine T-cells. This review summarizes the swine model for biomedical research with focus on T cells. It first contrasts the swine model to the more commonly used mouse and non-human primate model before describing the current capabilities to characterize and extend our knowledge on porcine T cells. Thereafter, it not only reflects on previous biomedical T-cell research but also extends into areas in which more in-depth T-cell analyses could strongly benefit biomedical research. While the former should inform on the successes of biomedical T-cell research in swine, the latter shall inspire swine T-cell researchers to find collaborations with researchers working in other areas - such as nutrition, allergy, cancer, transplantation, infectious diseases, or vaccine development.

The effect of Helicobacter pylori infection and different H. pylori components on the proliferation and apoptosis of gastric epithelial cells and fibroblasts

Background

Helicobacter pylori colonizes the human gastric mucosa, causing chronic inflammation, peptic ulcers and gastric cancer. A cascade of harmful processes results from the interaction of these bacteria with the gastric epithelium.

Aim

To investigate these processes in terms of upregulation of oxidative stress and cell apoptosis and downregulation of the pro-regenerative activity of cells.

Methods

We employed an in vivo guinea pig model at 7 or 28 days postinoculation with H. pylori, corresponding to an acute or chronic stage of infection, respectively, and an in vitro model of guinea pig primary gastric epithelial cells and fibroblasts treated with bacterial components: glycine acid extract (GE), urease subunit A (UreA), cytotoxin-associated gene A protein (CagA) and lipopolysaccharide (LPS). Cells were evaluated for metabolic activity (MTT reduction), myeloperoxidase (MPO) and metalloproteinase (MMP-9) secretion, lipid peroxidation (4-hydroxynonenal (4HNE)), migration (wound healing), proliferation (Ki-67 antigen) and cell apoptosis (TUNEL assay; Bcl-xL, Bax, Bcl-2 expression; caspase 3 cleavage).

Results

Significant infiltration of the gastric mucosa by inflammatory cells in vivo in response to H. pylori was accompanied by oxidative stress and cell apoptosis, which were more intense 7 than 28 days after inoculation. The increase in cell proliferation was more intense in chronic than acute infection. H. pylori components GE, CagA, UreA, and LPS upregulated oxidative stress and apoptosis. Only H. pylori LPS inhibited cell migration and proliferation, which was accompanied by the upregulation of MMP-9.

Conclusions

H. pylori infection induces cell apoptosis in conjunction with increased oxidative stress. Elevated apoptosis protects against deleterious inflammation and neoplasia; however, it reduces cell integrity. Upregulation of cell migration and proliferation in response to injury in the milieu of GE, CagA or UreA facilitates tissue regeneration but increases the risk of neoplasia. By comparison, downregulation of cell regeneration by H. pylori LPS may promote chronic inflammation.

Dietary lysozyme supplementation contributes to enhanced intestinal functions and gut microflora of piglets

Lysozyme plays a significant role in defense against bacterial pathogens and in regulating the interactions between gut microbiota and host immune systems. Here, the effects of dietary lysozyme on the intestinal development, immunity, and colonic microbiota of piglets were comprehensively evaluated. Twenty-four seven-day-old piglets from Landrace × Yorkshire sows (n = 8 per group) received no supplementation (group A, the control), 0.5 g kg-1 lysozyme (group B), or 1.0 g kg-1 lysozyme (group C). After the 14-day treatment, piglets supplemented with 1.0 g kg-1 lysozyme had higher average weaning weight, jejunal villus height (VH), and ileal lymphocyte counts than those in the control groups (P < 0.005). Serum total protein and albumin were significantly up-regulated (P < 0.005) and immunoglobulin G tended to increase in the 0.5 g kg-1 lysozyme group (P = 0.065). Bacteroidetes, Proteobacteria, and Fibrobacteres all showed a significant increase in relative abundance after lysozyme treatment at the highest dosage (P < 0.005). At the genus level, the relative abundance of Lactobacillus, Treponema_2, and Prevotellaceae_NK3B31_group was significantly increased in the lysozyme-treated groups. Furthermore, microbial genes related to glycerolipid, propanoate, and pyruvate metabolism showed much more abundance in the 1.0 g kg-1 lysozyme group. Interleukin-4 in the colonic mucosa was significantly up-regulated, while transforming growth factor-β1 showed significant reduction in the lysozyme-treated group. Moreover, mucosal catalase and malondialdehyde in colon samples increased significantly. These results demonstrate that dietary lysozyme efficaciously improves the development of intestinal structure and functions and promotes the enrichment of beneficial microbes in the gut microbiota in terms of both composition and metabolic functions.

Impact factors that modulate gastric cancer risk in Helicobacter pylori-infected rodent models

Gastric cancer causes a large social and economic burden to humans. Helicobacter pylori (H pylori) infection is a major risk factor for distal gastric cancer. Detailed elucidation of H pylori pathogenesis is significant for the prevention and treatment of gastric cancer. Animal models of H pylori-induced gastric cancer have provided an invaluable resource to help elucidate the mechanisms of H pylori-induced carcinogenesis as well as the interaction between host and the bacterium. Rodent models are commonly used to study H pylori infection because H pylori-induced pathological processes in the stomachs of rodents are similar to those in the stomachs of humans. The risk of gastric cancer in H pylori-infected animal models is greatly dependent on host factors, bacterial determinants, environmental factors, and microbiota. However, the related mechanisms and the effects of the interactions among these impact factors on gastric carcinogenesis remain unclear. In this review, we summarize the impact factors mediating gastric cancer risk when establishing H pylori-infected animal models. Clarifying these factors and their potential interactions will provide insights to construct animal models of gastric cancer and investigate the in-depth mechanisms of H pylori pathogenesis, which might contribute to the management of H pylori-associated gastric diseases.

Pathogenicity of Helicobacter pylori in cancer development and impacts of vaccination

Helicobacter pylori affect around 50% of the population worldwide. More importantly, the gastric infection induced by this bacterium is deemed to be associated with the progression of distal gastric carcinoma and gastric mucosal lymphoma in the human. H. pylori infection and its prevalent genotype significantly differ across various geographical regions. Based on numerous virulence factors, H. pylori can target different cellular proteins to modulate the variety of inflammatory responses and initiate numerous "hits" on the gastric mucosa. Such reactions lead to serious complications, including gastritis and peptic ulceration, gastric cancer and gastric mucosa-associated lymphoid structure lymphoma. Therefore, H. pylori have been considered as the type I carcinogen by the Global Firm for Research on Cancer. During the two past decades, different reports revealed that H. pylori possess oncogenic potentials in the gastric mucosa through a complicated interplay between the bacterial factors, various facets, and the environmental factors. Accordingly, numerous signaling pathways could be triggered in the development of gastrointestinal diseases (e.g., gastric cancer). Therefore, the main strategy for the treatment of gastric cancer is controlling the disease far before its onset using preventive/curative vaccination. Increasing the efficiency of vaccines may be achieved by new trials of vaccine modalities, which is used to optimize the cellular immunity. Taken all, H. pylori infection may impose severe complications, for resolving of which extensive researches are essential in terms of immune responses to H. pylori. We envision that H. pylori-mediated diseases can be controlled by advanced vaccines and immunotherapies.

Helicobacter pylori-induced gastric pathology: insights from in vivo and ex vivo models

Gastric colonization with Helicobacter pylori induces diverse human pathological conditions, including superficial gastritis, peptic ulcer disease, mucosa-associated lymphoid tissue (MALT) lymphoma, and gastric adenocarcinoma and its precursors. The treatment of these conditions often relies on the eradication of H. pylori, an intervention that is increasingly difficult to achieve and that does not prevent disease progression in some contexts. There is, therefore, a pressing need to develop new experimental models of H. pylori-associated gastric pathology to support novel drug development in this field. Here, we review the current status of in vivo and ex vivo models of gastric H. pylori colonization, and of Helicobacter-induced gastric pathology, focusing on models of gastric pathology induced by H. pylori, Helicobacter felis and Helicobacter suis in rodents and large animals. We also discuss the more recent development of gastric organoid cultures from murine and human gastric tissue, as well as from human pluripotent stem cells, and the outcomes of H. pylori infection in these systems.

Techniques for thoracic duct cannulation without thoracotomy in piglets

Background

Pigs are the natural hosts of many zoonotic pathogens such as influenza viruses and Staphylococcus aureus and thus have advantages over non-natural hosts when studying these zoonotic diseases. In addition, pulmonary infections are a key issue in the pig industry, for example: porcine reproductive and respiratory syndrome virus infection. Exploration of the pathogenesis of swine pulmonary infections, in particular at the onset of disease, will provide valuable information for the development of vaccines against these diseases. Therefore, there is need to develop a methodology that allows for in vivo sampling of efferent pulmonary lymph with minimum damage to the target tissues for studying the pathogenesis of swine pulmonary infections.

Results

We introduce the surgical procedures for cannulating the thoracic duct at its point of entry into the external jugular vein cranial to the first rib on the left in pigs. Using this methodology, we monitored the amounts of triglyceride and cholesterol in the lymph collected from the thoracic duct following 30 h fasting and at multiple time points after meals. It was found that the levels of triglyceride rather than cholesterol corresponded to the milky appearance of the lymph samples.

Conclusions

Our techniques provide a strategy for collecting lymph including pulmonary lymph from the thoracic duct without thoracotomy. A pig model for collecting in vivo, in situ efferent lymph draining the lower respiratory tract and its local lymph nodes in real-time with minimal tissue damage to the target tissues opens a new door for studying disease processes in pulmonary infections. Techniques described here are the key to this door.

Electronic supplementary material

The online version of this article (doi:10.1186/s12917-016-0808-3) contains supplementary material, which is available to authorized users.

Modeling-Enabled Systems Nutritional Immunology

This review highlights the fundamental role of nutrition in the maintenance of health, the immune response, and disease prevention. Emerging global mechanistic insights in the field of nutritional immunology cannot be gained through reductionist methods alone or by analyzing a single nutrient at a time. We propose to investigate nutritional immunology as a massively interacting system of interconnected multistage and multiscale networks that encompass hidden mechanisms by which nutrition, microbiome, metabolism, genetic predisposition, and the immune system interact to delineate health and disease. The review sets an unconventional path to apply complex science methodologies to nutritional immunology research, discovery, and development through “use cases” centered around the impact of nutrition on the gut microbiome and immune responses. Our systems nutritional immunology analyses, which include modeling and informatics methodologies in combination with pre-clinical and clinical studies, have the potential to discover emerging systems-wide properties at the interface of the immune system, nutrition, microbiome, and metabolism.

Unraveling the swine genome: implications for human health

The pig was first used in biomedical research in ancient Greece and over the past few decades has quickly grown into an important biomedical research tool. Pigs have genetic and physiological traits similar to humans, which make them one of the most useful and versatile animal models. Owing to these similarities, data generated from porcine models are more likely to lead to viable human treatments than those from murine work. In addition, the similarity in size and physiology to humans allows pigs to be used for many experimental approaches not feasible in mice. Research areas that employ pigs range from neonatal development to translational models for cancer therapy. Increasing numbers of porcine models are being developed since the release of the swine genome sequence, and the development of additional porcine genomic and epigenetic resources will further their use in biomedical research.

Systems-wide analyses of mucosal immune responses to Helicobacter pylori at the interface between pathogenicity and symbiosis

Helicobacter pylori is the dominant member of the gastric microbiota in over half of the human population of which 5-15% develop gastritis or gastric malignancies. Immune responses to H. pylori are characterized by mixed T helper cell, cytotoxic T cell and NK cell responses. The presence of Tregs is essential for the control of gastritis and together with regulatory CX3CR1+ mononuclear phagocytes and immune-evasion strategies they enable life-long persistence of H. pylori. This H. pylori-induced regulatory environment might contribute to its cross-protective effect in inflammatory bowel disease and obesity. Here we review host-microbe interactions, the development of pro- and anti-inflammatory immune responses and how the latter contribute to H. pylori's role as beneficial member of the gut microbiota. Furthermore, we present the integration of existing and new data into a computational/mathematical model and its use for the investigation of immunological mechanisms underlying initiation, progression and outcomes of H. pylori infection.

Modeling the Regulatory Mechanisms by Which NLRX1 Modulates Innate Immune Responses to Helicobacter pylori Infection

Helicobacter pylori colonizes half of the world’s population as the dominant member of the gastric microbiota resulting in a lifelong chronic infection. Host responses toward the bacterium can result in asymptomatic, pathogenic or even favorable health outcomes; however, mechanisms underlying the dual role of H. pylori as a commensal versus pathogenic organism are not well characterized. Recent evidence suggests mononuclear phagocytes are largely involved in shaping dominant immunity during infection mediating the balance between host tolerance and succumbing to overt disease. We combined computational modeling, bioinformatics and experimental validation in order to investigate interactions between macrophages and intracellular H. pylori. Global transcriptomic analysis on bone marrow-derived macrophages (BMDM) in a gentamycin protection assay at six time points unveiled the presence of three sequential host response waves: an early transient regulatory gene module followed by sustained and late effector responses. Kinetic behaviors of pattern recognition receptors (PRRs) are linked to differential expression of spatiotemporal response waves and function to induce effector immunity through extracellular and intracellular detection of H. pylori. We report that bacterial interaction with the host intracellular environment caused significant suppression of regulatory NLRC3 and NLRX1 in a pattern inverse to early regulatory responses. To further delineate complex immune responses and pathway crosstalk between effector and regulatory PRRs, we built a computational model calibrated using time-series RNAseq data. Our validated computational hypotheses are that: 1) NLRX1 expression regulates bacterial burden in macrophages; and 2) early host response cytokines down-regulate NLRX1 expression through a negative feedback circuit. This paper applies modeling approaches to characterize the regulatory role of NLRX1 in mechanisms of host tolerance employed by macrophages to respond to and/or to co-exist with intracellular H. pylori.

Epinecidin-1 antimicrobial activity: In vitro membrane lysis and In vivo efficacy against Helicobacter pylori infection in a mouse model

Helicobacter pylori (H. pylori) infection is highly prevalent, and has a strong association with various gastric diseases, including gastritis, digestive ulcers, and cancer. H. pylori strains with resistance to existing antibiotics have emerged in the past two decades. Currently, treatment of H. pylori infection (involving the use of proton pump inhibitors, followed by triple therapy with broad-spectrum antibiotics) is suboptimal, with high failure rates. As such, there is a clear need for new approaches against H. pylori. Here, we report that Epinecidin-1 (Epi-1) shows effective bactericidal activity against H. Pylori in vitro, and modulates H. Pylori-induced host immune responses in a mouse model. Epi-1 exhibited a low minimum inhibitory concentration (MIC) against antibiotic-sensitive and clinical antibiotic-resistant strains. Moreover, Epi-1 treatment caused 1-N-phenylnaphthylamine (NPN)-fluorescent probe uptake, suggesting it induced membrane lysis; transmission electron micrographs revealed that membranes were destabilized by the generation of saddle-splay membrane curvature. Oral administration of Epi-1 (quaque die dose) in a mouse infection model had strong efficacy (p < 0.00152) against H. pylori, as compared with conventional proton pump inhibitor (PPI)-triple therapeutic antibiotics. Epi-1 inhibited infection through in vivo depletion of CD4+-FOXP3+ T Regulatory and Th17 subset populations, and aided in clearance of persistent H. pylori colonization. Flow cytometry and gene expression analysis of mouse splenic and gastric tissue indicated that Epi-1 inhibits IL-10, and thereby affects FOXP3 expression levels and reduces pro-inflammatory cytokine responses. Crucially, high doses of Epi-1 did not exert toxic effects in oral, dermal, and eye irritation models. Collectively, our results suggest that Epi-1 may be a promising, effective, and safe monotherapeutic agent for the treatment of multi-drug resistant H. pylori infection.

Helicobacter pylori Outer Membrane Protein 18 (Hp1125) Is Involved in Persistent Colonization by Evading Interferon- γ Signaling

Outer membrane proteins (OMPs) can induce an immune response. Omp18 (HP1125) of H. pylori is a powerful antigen that can induce significant interferon-γ (IFN-γ) levels. Previous studies have suggested that IFN-γ plays an important role in H. pylori clearance. However, H. pylori has multiple mechanisms to avoid host immune surveillance for persistent colonization. We generated an omp18 mutant (H. pylori 26695 and H. pylori SS1) strain to examine whether Omp18 interacts with IFN-γ and is involved in H. pylori colonization. qRT-PCR revealed that IFN-γ induced Omp18 expression. qRT-PCR and western blot analysis revealed reduced expressions of virulence factors CagA and NapA in H. pylori 26695 with IFN-γ treatment, but they were induced in the Δomp18 strain. In C57BL/6 mice infected with H. pylori SS1 and the Δomp18 strain, the Δomp18 strain conferred defective colonization and activated a stronger inflammatory response. Signal transducer phosphorylation and transcription 1 (STAT1) activator was downregulated by the wild-type strain but not the Δomp18 strain in IFN-γ-treated macrophages. Furthermore, Δomp18 strain survival rates were poor in macrophages compared to the wild-type strain. We concluded that H. pylori Omp18 has an important function influencing IFN-γ-mediated immune response to participate in persistent colonization.

Phenotypic and functional differentiation of porcine αβ T cells: current knowledge and available tools

Domestic pigs are considered as a valuable large animal model because of their close relation to humans in regard to anatomy, genetics and physiology. This includes their potential use as organ donors in xenotransplantation but also studies on various zoonotic infections affecting pigs and humans. Such work also requires a thorough understanding of the porcine immune system which was partially hampered in the past by restrictions on available immunological tools compared to rodent models. However, progress has been made during recent years in the study of both, the innate and the adaptive immune system of pigs. In this review we will summarize the current knowledge on porcine αβ T cells, which comprise two major lymphocyte subsets of the adaptive immune system: CD4(+) T cells with important immunoregulatory functions and CD8(+) T cells, also designated as cytolytic T cells. Aspects on their functional and phenotypic differentiation are presented. In addition, we summarize currently available tools to study these subsets which may support a more widespread use of swine as a large animal model.

Novel insights on the role of CD8+ T cells and cytotoxic responses during Helicobacter pylori infection

Helicobacter pylori chronically persists in 50% of the human population and causes serious gastric and duodenal pathologies in 15% of infected people. Research on the immune response to the infection has mainly focused on the induction of CD4+ T cell responses. Human studies emphasize the potential clinical relevance of CD8+ cytotoxic T lymphocytes, however this cell type has barely been reported in studies employing mouse or gerbil models. Traditionally characterized as an extracellular bacterium, H. pylori has been identified inside epithelial and immune cells. Similarly to other intracellular bacteria, H. pylori infection of macrophages can alter autophagy and phagosome processing. A novel animal model of H. pylori infection demonstrates for the first time the induction of cytotoxic CD8+ T cell responses in pigs and localization of intracellular H. pylori within lymphoid aggregates. Here, we discuss novel mechanisms of host-H. pylori interactions that could lead to the induction of cytotoxic responses.

Exploratory study of oral mucosal colonization of human gastric Helicobacter pylori in mice

In this study, human gastric Helicobacter pylori (Hp) was closely attached to the pre-treated mouse buccal mucosa by using artificial oral film to induce the growth and colonization of Hp on the buccal mucosa in mice. Sixty BALB/c mice were divided into three groups, in which Hp biofilm colonization was detected in three mice in Hp film group (Hp mesh biofilm accumulation under an optical microscope; Hp accumulated colonization under an electron microscope). There were no Hp biofilms detected in Hp smear group or the control group with black film. In this study, human gastric Hp was first used to artificially induce the growth and colonization of Hp on the buccal mucosa in mice. The mouse model of oral infection with Hp was initially established, providing animal experimental evidences for oral conditions of growth and colonization of Hp on the buccal mucosa in mice, and providing a workable animal modeling method for further research of joint infection of Hp on the mouth and stomach, as well as the relationship between oral Hp and gastric Hp.