DC-derived IL-18 drives Treg differentiation, murine Helicobacter pylori-specific immune tolerance, and asthma protection

Helicobacter pylori triggers inflammation and oncogenic transformation by perturbing the immune microenvironment

The immune microenvironment plays a critical regulatory role in the pathogenesis of Helicobacter pylori (H. pylori). Understanding the mechanisms that drive the transition from chronic inflammation to cancer may provide new insights for early detection of gastric cancer. Although chronic inflammation is frequent in precancerous gastric conditions, the monitoring function of the inflammatory microenvironment in the progression from H. pylori-induced chronic inflammation to gastric cancer remains unclear. This literature review summarizes significant findings on how H. pylori triggers inflammatory responses and facilitates cancer development through the immune microenvironment. Furthermore, the implications for future research and clinical applications are also addressed. The review is divided into four main sections: inflammatory response and immune evasion mechanisms induced by H. pylori, immune dysregulation associated with gastric cancer, therapeutic implications, and future perspectives on H. pylori-induced gastric carcinogenesis with a focus on the immune microenvironment.

Trained Immunity and Trained Tolerance: The Case of Helicobacter pylori Infection

Trained immunity is a concept in immunology in which innate immune cells, such as monocytes and macrophages, exhibit enhanced responsiveness and memory-like characteristics following initial contact with a pathogenic stimulus that may promote a more effective immune defense following subsequent contact with the same pathogen. Helicobacter pylori, a bacterium that colonizes the stomach lining, is etiologically associated with various gastrointestinal diseases, including gastritis, peptic ulcer, gastric adenocarcinoma, MALT lymphoma, and extra gastric disorders. It has been demonstrated that repeated exposure to H. pylori can induce trained immunity in the innate immune cells of the gastric mucosa, which become more responsive and better able to respond to subsequent H. pylori infections. However, interactions between H. pylori and trained immunity are intricate and produce both beneficial and detrimental effects. H. pylori infection is characterized histologically as the presence of both an acute and chronic inflammatory response called acute-on-chronic inflammation, or gastritis. The clinical outcomes of ongoing inflammation include intestinal metaplasia, gastric atrophy, and dysplasia. These same mechanisms may also reduce immunotolerance and trigger autoimmune pathologies in the host. This review focuses on the relationship between trained immunity and H. pylori and underscores the dynamic interplay between the immune system and the pathogen in the context of gastric colonization and inflammation.

Helicobacter pylori infection in infant rhesus macaque monkeys is associated with an altered lung and oral microbiome

It is estimated that more than half of the world population has been infected with Helicobacter pylori. Most newly acquired H. pylori infections occur in children before 10 years of age. We hypothesized that early life H. pylori infection could influence the composition of the microbiome at mucosal sites distant to the stomach. To test this hypothesis, we utilized the infant rhesus macaque monkey as an animal model of natural H. pylori colonization to determine the impact of infection on the lung and oral microbiome during a window of postnatal development. From a cohort of 4-7 month-old monkeys, gastric biopsy cultures identified 44% of animals infected by H. pylori. 16S ribosomal RNA gene sequencing of lung washes and buccal swabs from animals showed distinct profiles for the lung and oral microbiome, independent of H. pylori infection. In order of relative abundance, the lung microbiome was dominated by the phyla Proteobacteria, Firmicutes, Bacteroidota, Fusobacteriota, Campilobacterota and Actinobacteriota while the oral microbiome was dominated by Proteobacteria, Firmicutes, Bacteroidota, and Fusobacteriota. In comparison to the oral cavity, the lung was composed of more genera and species that significantly differed by H. pylori status, with a total of 6 genera and species that were increased in H. pylori negative infant monkey lungs. Lung, but not plasma IL-8 concentration was also associated with gastric H. pylori load and lung microbial composition. We found the infant rhesus macaque monkey lung harbors a microbiome signature that is distinct from that of the oral cavity during postnatal development. Gastric H. pylori colonization and IL-8 protein were linked to the composition of microbial communities in the lung and oral cavity. Collectively, these findings provide insight into how H. pylori infection might contribute to the gut-lung axis during early childhood and modulate future respiratory health.

Adipose tissue IL-18 production is independent of caspase-1 and caspase-11

BACKGROUND

Inflammation in adipose tissue, resulting from imbalanced caloric intake and energy expenditure, contributes to the metabolic dysregulation observed in obesity. The production of inflammatory cytokines, such as IL-1β and IL-18, plays a key role in this process. While IL-1β promotes insulin resistance and diabetes, IL-18 regulates energy expenditure and food intake. Previous studies have suggested that caspase-1, activated by the Nlrp3 inflammasome in response to lipid excess, mediates IL-1β production, whereas activated by the Nlrp1b inflammasome in response to energy excess, mediates IL-18 production. However, this has not been formally tested.

METHODS

Wild-type and caspase-1-deficient Balb/c mice, carrying the Nlrp1b1 allele, were fed with regular chow or a high-fat diet for twelve weeks. Food intake and mass gain were recorded weekly. At the end of the twelve weeks, glucose tolerance and insulin resistance were evaluated. Mature IL-18 protein levels and the inflammatory process in the adipose tissue were determined. Fasting lipid and cytokine levels were quantified in the sera of the different experimental groups.

RESULTS

We found that IL-18 production in adipose tissue is independent of caspase-1 activity, regardless of the metabolic state, while Nlrp3-mediated IL-1β production remains caspase-1 dependent. Additionally, caspase-1 null Balb/c mice did not develop metabolic abnormalities in response to energy excess from the high-fat diet.

CONCLUSION

Our findings suggest that IL-18 production in the adipose tissue is independent of Nlrp3 inflammasome and caspase-1 activation, regardless of caloric food intake. In contrast, Nlrp3-mediated IL-1β production is caspase-1 dependent. These results provide new insights into the mechanisms underlying cytokine production in the adipose tissue during both homeostatic conditions and metabolic stress, highlighting the distinct roles of caspase-1 and the Nlrp inflammasomes in regulating inflammatory responses.

Deciphering the developmental trajectory of tissue-resident Foxp3+ regulatory T cells

Foxp3+ TREG cells have been at the focus of intense investigation for their recognized roles in preventing autoimmunity, facilitating tissue recuperation following injury, and orchestrating a tolerance to innocuous non-self-antigens. To perform these critical tasks, TREG cells undergo deep epigenetic, transcriptional, and post-transcriptional changes that allow them to adapt to conditions found in tissues both at steady-state and during inflammation. The path leading TREG cells to express these tissue-specialized phenotypes begins during thymic development, and is further driven by epigenetic and transcriptional modifications following TCR engagement and polarizing signals in the periphery. However, this process is highly regulated and requires TREG cells to adopt strategies to avoid losing their regulatory program altogether. Here, we review the origins of tissue-resident TREG cells, from their thymic and peripheral development to the transcriptional regulators involved in their tissue residency program. In addition, we discuss the distinct signalling pathways that engage the inflammatory adaptation of tissue-resident TREG cells, and how they relate to their ability to recognize tissue and pathogen-derived danger signals.

Increased infiltration of CD4+ IL-17A+ FOXP3+ T cells in Helicobacter pylori-induced gastritis

Helicobacter pylori is one of the main predisposing factors for gastric cancer, causing chronic inflammation and proper glands atrophy in the gastric mucosa. Although H. pylori-induced inflammation is a key inducer of precancerous lesions in the gastric mucosa, it remains unclear which precise immune cell subsets are responsible for the progression of H. pylori-induced gastritis. Here, we observed an abundance of CD4+ IL-17A+ FOXP3+ T cells exhibiting a Th17-like phenotype within the microenvironment of H. pylori-induced gastritis. Mechanistically, H. pylori upregulated the expression of IL-6 in Dendritic cells and macrophages, by activating NF-κB signaling through the virulence factor CagA and thus, induced IL-17A expression in FOXP3+ T cells. Moreover, CD4+ IL-17A+ FOXP3+ T cells were positively associated with advanced precancerous lesions. Therefore, these findings offer essential insights into how FOXP3+ T cells sense inflammatory signals from the environment, such as IL-6, during H. pylori infections, thereby guiding the effector immune response and aggravating the gastritis.

Strategies of Helicobacter pylori in evading host innate and adaptive immunity: insights and prospects for therapeutic targeting

Helicobacter pylori (H. pylori) is the predominant pathogen causing chronic gastric mucosal infections globally. During the period from 2011 to 2022, the global prevalence of H. pylori infection was estimated at 43.1%, while in China, it was slightly higher at approximately 44.2%. Persistent colonization by H. pylori can lead to gastritis, peptic ulcers, and malignancies such as mucosa-associated lymphoid tissue (MALT) lymphomas and gastric adenocarcinomas. Despite eliciting robust immune responses from the host, H. pylori thrives in the gastric mucosa by modulating host immunity, particularly by altering the functions of innate and adaptive immune cells, and dampening inflammatory responses adverse to its survival, posing challenges to clinical management. The interaction between H. pylori and host immune defenses is intricate, involving evasion of host recognition by modifying surface molecules, manipulating macrophage functionality, and modulating T cell responses to evade immune surveillance. This review analyzes the immunopathogenic and immune evasion mechanisms of H. pylori, underscoring the importance of identifying new therapeutic targets and developing effective treatment strategies, and discusses how the development of vaccines against H. pylori offers new hope for eradicating such infections.

Update on the association between Helicobacter pylori infection and asthma in terms of microbiota and immunity

H. pylori is a gram-negative bacterium that is usually acquired in childhood and can persistently colonize the gastric mucosa of humans, affecting approximately half of the world's population. In recent years, the prevalence of H. pylori infection has steadily reduced while the risk of allergic diseases has steadily climbed. As a result, epidemiological research indicates a strong negative association between the two. Moreover, numerous experimental studies have demonstrated that eradicating H. pylori increases the risk of allergic diseases. Hence, it is hypothesized that H. pylori infection may act as a safeguard against allergic diseases. The hygiene hypothesis, alterations in gut microbiota, the development of tolerogenic dendritic cells, and helper T cells could all be involved in H. pylori's ability to protect against asthma. Furthermore, Studies on mice models have indicated that H. pylori and its extracts are crucial in the management of asthma. We reviewed the in-depth studies on the most recent developments in the relationship between H. pylori infection and allergic diseases, and we discussed potential mechanisms of the infection's protective effect on asthma in terms of microbiota and immunity. We also investigated the prospect of the application of H. pylori and its related components in asthma, so as to provide a new perspective for the prevention or treatment of allergic diseases.

Microbes little helpers and suppliers for therapeutic asthma approaches

Bronchial asthma is a prevalent and increasingly chronic inflammatory lung disease affecting over 300 million people globally. Initially considered an allergic disorder driven by mast cells and eosinophils, asthma is now recognized as a complex syndrome with various clinical phenotypes and immunological endotypes. These encompass type 2 inflammatory endotypes characterized by interleukin (IL)-4, IL-5, and IL-13 dominance, alongside others featuring mixed or non-eosinophilic inflammation. Therapeutic success varies significantly based on asthma phenotypes, with inhaled corticosteroids and beta-2 agonists effective for milder forms, but limited in severe cases. Novel antibody-based therapies have shown promise, primarily for severe allergic and type 2-high asthma. To address this gap, novel treatment strategies are essential for better control of asthma pathology, prevention, and exacerbation reduction. One promising approach involves stimulating endogenous anti-inflammatory responses through regulatory T cells (Tregs). Tregs play a vital role in maintaining immune homeostasis, preventing autoimmunity, and mitigating excessive inflammation after pathogenic encounters. Tregs have demonstrated their ability to control both type 2-high and type 2-low inflammation in murine models and dampen human cell-dependent allergic airway inflammation. Furthermore, microbes, typically associated with disease development, have shown immune-dampening properties that could be harnessed for therapeutic benefits. Both commensal microbiota and pathogenic microbes have demonstrated potential in bacterial-host interactions for therapeutic purposes. This review explores microbe-associated approaches as potential treatments for inflammatory diseases, shedding light on current and future therapeutics.

Helicobacter pylori antigens as immunomodulators of immune system

Helicobacter pylori (H. pylori) is one of the most prevalent human pathogens and the leading cause of chronic infection in almost half of the population in the world (~59%). The bacterium is a major leading cause of chronic gastritis, gastric and duodenal ulcers, and two type of malignancies, gastric adenocarcinoma and mucosa-associated lymphoid tissue (MALT) lymphoma. Despite the immune responses mounted by the host, the bacteria are not cleared from the body resulting in a chronic infection accompanied by a chronic inflammation. Herein, a review of the literature discussing H. pylori antigens modulating the immune responses is presented. The mechanisms that are involved in the modulation of innate immune response, include modulation of recognition by pattern recognition receptors (PRRs) such as modulation of recognition by toll like receptors (TLR)4 and TLR5, modulation of phagocytic function, and modulation of phagocytic killing mediated by reactive oxygen species (ROS) and nitric oxide (NO). On the other hands, H. pylori modulates acquired immune response by the induction of tolerogenic dendritic cells (DCs), modulation of apoptosis, induction of regulatory T cells, modulation of T helper (Th)1 response, and modulation of Th17 response.

Notch Signaling Regulates the Function and Phenotype of Dendritic Cells in Helicobacter pylori Infection

Notch signaling manipulates the function and phenotype of dendritic cells (DCs), as well as the interaction between DCs and CD4+ T cells. However, the role of Notch signaling in Helicobacter pylori (H. pylori) infection remains elusive. Murine bone marrow-derived dendritic cells (BMDCs) were pretreated in the absence or presence of Notch signaling inhibitor DAPT prior to H. pylori stimulation and the levels of Notch components, cytokines and surface markers as well as the differentiation of CD4+ T cells in co-culture were measured using quantitative real-time PCR (qRT-PCR), Western blot, enzyme-linked immunosorbent assay (ELISA) and flow cytometry. Compared with the control, the mRNA expression of all Notch receptors and Notch ligands Dll4 and Jagged1 was up-regulated in H. pylori-stimulated BMDCs. The blockade of Notch signaling by DAPT influenced the production of IL-1β and IL-10 in H. pylori-pulsed BMDCs, and reduced the expression of Notch1, Notch3, Notch4, Dll1, Dll3 and Jagged2. In addition, DAPT pretreatment decreased the expression of maturation markers CD80, CD83, CD86, and major histocompatibility complex class II (MHC-II) of BMDCs, and further skewed Th17/Treg balance toward Treg. Notch signaling regulates the function and phenotype of DCs, thus mediating the differentiation of CD4+ T cells during H. pylori infection.

Helicobacter pylori infection attenuates 2,4-dinitrochlorobenzene-induced atopic dermatitis-like skin lesions in C57/BL6 mice

BACKGROUND

Although numerous studies have suggested a negative correlation between Helicobacter pylori (H. pylori) infection and allergies, there has been limited research on the relationship between H. pylori infections and atopic dermatitis (AD). The present study aimed to investigate the effects of H. pylori infection in an AD mouse model and identify potential mechanisms related to type 2 immunity, skin barrier defects, and pruritus.

METHODS

A model of AD-like symptoms was established with 2,4-dinitrochlorobenzene (DNCB) after infection of the gastric cavity with H. pylori. Analysis of the expression of key inflammatory cytokines and serum levels of immunoglobulin E (IgE) was based on enzyme-linked immunosorbent assay (ELISA). The expression of filaggrin (FLG) and loricrin (LOR) were analyzed by immunohistochemistry staining. The evaluation of STAT1, STAT3, phosphorylated STAT1 (phospho-STAT1), and phosphorylated STAT3 (phospho-STAT1) expression levels in skin lesions was performed using western blot.

RESULTS

The present study showed that the H. pylori-positive AD group (HP+AD+) exhibited milder skin lesions, including erythema, erosion, swelling, and scaling, than the H. pylori-negative AD group (HP-AD+). Additionally, HP+AD+ displayed lower levels of IgE in serum, and downregulated expression of interleukins 4 and 31 (IL-4 and IL-31) in serum. Furthermore, HP+AD+ demonstrated higher expression of filaggrin and loricrin than HP-AD+. Notably, H. pylori significantly reduced the amount of phosphorylated STAT1 and STAT3.

CONCLUSION

Helicobacter pylori infection negatively regulates the inflammatory response by affecting inflammatory factors in the immune response, and repairs the defective epidermal barrier function. In addition, H. pylori infection may reduce IL-31, thereby alleviating pruritus. These effects may be associated with the inhibition of JAK-STAT signaling activation.

Diversification and deleterious role of microbiome in gastric cancer

Gut microbiota dictates the fate of several diseases, including cancer. Most gastric cancers (GC) belong to gastric adenocarcinomas (GAC). Helicobacter pylori colonizes the gastric epithelium and is the causative agent of 75% of all stomach malignancies globally. This bacterium has several virulence factors, including cytotoxin-associated gene A (CagA), vacuolating cytotoxin (VacA), and outer membrane proteins (OMPs), all of which have been linked to the development of gastric cancer. In addition, bacteria such as Escherichia coli, Streptococcus, Clostridium, Haemophilus, Veillonella, Staphylococcus, and Lactobacillus play an important role in the development of gastric cancer. Besides, lactic acid bacteria (LAB) such as Bifidobacterium, Lactobacillus, Lactococcus, and Streptococcus were found in greater abundance in GAC patients. To identify potential diagnostic and therapeutic interventions for GC, it is essential to understand the mechanistic role of H. pylori and other bacteria that contribute to gastric carcinogenesis. Furthermore, understanding bacteria-host interactions and bacteria-induced inflammatory pathways in the host is critical for developing treatment targets for gastric cancer.

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.

Immune response modulation in inflammatory bowel diseases by Helicobacter pylori infection

Many studies point to an association between Helicobacter pylori (H. pylori) infection and inflammatory bowel diseases (IBD). Although controversial, this association indicates that the presence of the bacterium somehow affects the course of IBD. It appears that H. pylori infection influences IBD through changes in the diversity of the gut microbiota, and hence in local chemical characteristics, and alteration in the pattern of gut immune response. The gut immune response appears to be modulated by H. pylori infection towards a less aggressive inflammatory response and the establishment of a targeted response to tissue repair. Therefore, a T helper 2 (Th2)/macrophage M2 response is stimulated, while the Th1/macrophage M1 response is suppressed. The immunomodulation appears to be associated with intrinsic factors of the bacteria, such as virulence factors - such oncogenic protein cytotoxin-associated antigen A, proteins such H. pylori neutrophil-activating protein, but also with microenvironmental changes that favor permanence of H. pylori in the stomach. These changes include the increase of gastric mucosal pH by urease activity, and suppression of the stomach immune response promoted by evasion mechanisms of the bacterium. Furthermore, there is a causal relationship between H. pylori infection and components of the innate immunity such as the NLR family pyrin domain containing 3 inflammasome that directs IBD toward a better prognosis.

Helicobacter pylori Infection in Infant Rhesus Macaque Monkeys is Associated with an Altered Lung and Oral Microbiome

Background

It is estimated that more than half of the world population has been infected with Helicobacter pylori. Most newly acquired H. pylori infections occur in children before 10 years of age. We hypothesized that early life H. pylori infection could influence the composition of the microbiome at mucosal sites distant to the stomach. To test this hypothesis, we utilized the infant rhesus macaque monkey as an animal model of natural H. pylori colonization to determine the impact of infection on the lung and oral microbiome during a window of postnatal development.

Results

From a cohort of 4-7-month-old monkeys, gastric biopsy cultures identified 44% of animals infected by H. pylori. 16S ribosomal RNA gene sequencing of lung washes and buccal swabs from animals showed distinct profiles for the lung and oral microbiome, independent of H. pylori infection. In relative order of abundance, the lung microbiome was dominated by the phyla Proteobacteria, Firmicutes, Bacteroidota, Fusobacteriota, Campilobacterota and Actinobacteriota while the oral microbiome was dominated by Proteobacteria, Firmicutes, Bacteroidota, and Fusobacteriota. Relative to the oral cavity, the lung was composed of more genera and species that significantly differed by H. pylori status, with a total of 6 genera and species that were increased in H. pylori negative infant monkey lungs. Lung, but not plasma IL-8 concentration was also associated with gastric H. pylori load and lung microbial composition.

Conclusions

We found the infant rhesus macaque monkey lung harbors a microbiome signature that is distinct from that of the oral cavity during postnatal development. Gastric H. pylori colonization and IL-8 protein were linked to the composition of microbial communities in the lung and oral cavity. Collectively, these findings provide insight into how H. pylori infection might contribute to the gut-lung axis during early childhood and modulate future respiratory health.

Insights Regarding the Role of Inflammasomes in Leukemia: What Do We Know?

Inflammation is a physiological mechanism of the immune response and has an important role in maintaining the hematopoietic cell niche in the bone marrow. During this process, the participation of molecules produced by innate immunity cells in response to a variety of pathogen-associated molecular patterns and damage-associated molecular patterns is observed. However, chronic inflammation is intrinsically associated with leukemogenesis, as it induces DNA damage in hematopoietic stem cells and contributes to the creation of the preleukemic clone. Several factors influence the malignant transformation within the hematopoietic microenvironment, with inflammasomes having a crucial role in this process, in addition to acting in the regulation of hematopoiesis and its homeostasis. Inflammasomes are intracellular multimeric complexes responsible for the maturation and secretion of the proinflammatory cytokines interleukin-1β and interleukin-18 and the cell death process via pyroptosis. Therefore, dysregulation of the activation of these complexes may be a factor in triggering several diseases, including leukemias, and this has been the subject of several studies in the area. In this review, we summarized the current knowledge on the relationship between inflammation and leukemogenesis, in particular, the role of inflammasomes in different types of leukemias, and we describe the potential therapeutic targets directed at inflammasomes in the leukemic context.

IL-18 is required for the TH1-adaptation of TREG cells and the selective suppression of TH17 responses in acute and chronic infections

Interleukin (IL)-18, a member of the IL-1 family of alarmins, is abundantly released in the lungs following influenza A (IAV) infections yet its role in orchestrating the local adaptive immune response remains ill defined. Through genetic disruption of the IL-18 receptor, we demonstrate that IL-18 not only promotes pulmonary TH1 responses but also influences regulatory T cells (TREG) function in the infected lungs. As the response unfolds, TREG cells accumulating in the lungs express Helios, T-bet, CXCR3, and IL-18R1 and produce interferon γ in the presence of IL-12. During IAV, IL-18R1 is required for TREG cells to control TH17, but not TH1, responses and promote a return to lung homeostasis, revealing a novel mechanism of selective suppression. Moreover, this observation was not limited to the lungs, as skin-localized TREG cells require an IL-18 signal to specifically suppress IL-17A production by TH17 and γδ T cells in a model of chronic cutaneous Leishmania major infection. Overall, these results uncover how IL-18 orchestrates the tissue adaptation of TREG cells to selectively favor TH1 over TH17 responses during TH1-driven immune responses and provide a novel perspective into how IL-18 dictates the immune response during viral and parasitic infections.

Helicobacter pylori in children: think before you kill the bug!

Since the discovery of Helicobacter pylori (H. pylori) as the causative organism for gastric and duodenal ulcers four decades ago and subsequent recognition as class 1 gastric carcinogen, countless numbers of studies have been conducted and papers published, on the efficacy of various management strategies to eradicate the infection. In adults, a global consensus by the experts in the field concluded that H. pylori gastritis is an infectious disease and requires treatment irrespective of the presence or absence of symptoms due to the potential for serious complication like peptic ulcer disease and gastric neoplasia. However, although more than half the world's population harbors H. pylori, these serious complications occur only in a small minority of the infected population, even less so in childhood. More importantly, there is accumulating evidence for beneficial role of H. pylori against many chronic health conditions, from several epidemiological and laboratory studies. No doubt, eradication therapy is indicated in children with H. pylori-related peptic ulcer disease. Even though the pediatric guidelines from various learned societies recommend against a "test and treat" strategy, this is not always adhered to. With the accumulating evidence of the possible beneficial role of H. pylori, it is time to pause and think, are we causing more harm than good by eradicating H. pylori in every child who has this bug?

Impact of Helicobacter pylori infection on the efficacy of immune checkpoint inhibitors for cancer treatment: a meta-analysis

Aim: The present systematic review and meta-analysis was designed to assess the impact of Helicobacter pylori infection on the efficacy of immune checkpoint inhibitors (ICIs). Materials & methods: PubMed, Scopus, Web of Science and EMBASE databases were systematically searched up to 1 February 2023. Results: Three studies comprising 263 patients treated with ICIs were included. The results of pooled analysis showed that H. pylori infection was associated with reduced overall survival and progression-free survival. Furthermore, the rate of progressive disease after administration of ICIs was higher in H. pylori-positive patients relative to H. pylori-negative patients. Conclusion: H. pylori infection status is a novel potential response biomarker for predicting the efficacy of ICIs in different cancers.

Gastric microbiota: an emerging player in gastric cancer

Gastric cancer (GC) is a common cancer worldwide with a high mortality rate. Many microbial factors influence GC, of which the most widely accepted one is Helicobacter pylori (H. pylori) infection. H. pylori causes inflammation, immune reactions and activation of multiple signaling pathways, leading to acid deficiency, epithelial atrophy, dysplasia and ultimately GC. It has been proved that complex microbial populations exist in the human stomach. H. pylori can affect the abundance and diversity of other bacteria. The interactions among gastric microbiota are collectively implicated in the onset of GC. Certain intervention strategies may regulate gastric homeostasis and mitigate gastric disorders. Probiotics, dietary fiber, and microbiota transplantation can potentially restore healthy microbiota. In this review, we elucidate the specific role of the gastric microbiota in GC and hope these data can facilitate the development of effective prevention and therapeutic approaches for GC.

Helicobacter pylori infection

Helicobacter pylori infection causes chronic gastritis, which can progress to severe gastroduodenal pathologies, including peptic ulcer, gastric cancer and gastric mucosa-associated lymphoid tissue lymphoma. H. pylori is usually transmitted in childhood and persists for life if untreated. The infection affects around half of the population in the world but prevalence varies according to location and sanitation standards. H. pylori has unique properties to colonize gastric epithelium in an acidic environment. The pathophysiology of H. pylori infection is dependent on complex bacterial virulence mechanisms and their interaction with the host immune system and environmental factors, resulting in distinct gastritis phenotypes that determine possible progression to different gastroduodenal pathologies. The causative role of H. pylori infection in gastric cancer development presents the opportunity for preventive screen-and-treat strategies. Invasive, endoscopy-based and non-invasive methods, including breath, stool and serological tests, are used in the diagnosis of H. pylori infection. Their use depends on the specific individual patient history and local availability. H. pylori treatment consists of a strong acid suppressant in various combinations with antibiotics and/or bismuth. The dramatic increase in resistance to key antibiotics used in H. pylori eradication demands antibiotic susceptibility testing, surveillance of resistance and antibiotic stewardship.

Overexpression of CASP1 triggers acute promyelocytic leukemia cell pyroptosis and differentiation

Caspase-1 (CASP1)-mediated classical pyroptosis plays a key role in cancer development and management, however, the role of CASP1 and its regulation has not yet been documented for acute promyelocytic leukemia (APL). Here, we found that CASP1/GSDMD had lower expression in patients with APL and most other subtypes of primary de novo acute myeloid leukemia (AML) and was increased in all-trans-retinoic acid (ATRA)-treated APL cells. We showed that ATRA increases and activates CASP1 to trigger the pyroptosis and differentiation of APL cells. Mechanistically, ATRA could induce CASP1 expression via the IFNγ/STAT1 pathway in APL cells. In conclusion, ATRA-induced activation of CASP1 may serve as a suppressor in APL progression, as it triggers pyroptotic cell death and differentiation.

Helicobacter pylori promotes colorectal carcinogenesis by deregulating intestinal immunity and inducing a mucus-degrading microbiota signature

OBJECTIVE

Helicobacter pylori infection is the most prevalent bacterial infection worldwide. Besides being the most important risk factor for gastric cancer development, epidemiological data show that infected individuals harbour a nearly twofold increased risk to develop colorectal cancer (CRC). However, a direct causal and functional connection between H. pylori infection and colon cancer is lacking.

DESIGN

We infected two Apc-mutant mouse models and C57BL/6 mice with H. pylori and conducted a comprehensive analysis of H. pylori-induced changes in intestinal immune responses and epithelial signatures via flow cytometry, chip cytometry, immunohistochemistry and single cell RNA sequencing. Microbial signatures were characterised and evaluated in germ-free mice and via stool transfer experiments.

RESULTS

H. pylori infection accelerated tumour development in Apc-mutant mice. We identified a unique H. pylori-driven immune alteration signature characterised by a reduction in regulatory T cells and pro-inflammatory T cells. Furthermore, in the intestinal and colonic epithelium, H. pylori induced pro-carcinogenic STAT3 signalling and a loss of goblet cells, changes that have been shown to contribute-in combination with pro-inflammatory and mucus degrading microbial signatures-to tumour development. Similar immune and epithelial alterations were found in human colon biopsies from H. pylori-infected patients. Housing of Apc-mutant mice under germ-free conditions ameliorated, and early antibiotic eradication of H. pylori infection normalised the tumour incidence to the level of uninfected controls.

CONCLUSIONS

Our studies provide evidence that H. pylori infection is a strong causal promoter of colorectal carcinogenesis. Therefore, implementation of H. pylori status into preventive measures of CRC should be considered.

The innate immune brakes of the lung

Respiratory mucosal surfaces are continuously exposed to not only innocuous non-self antigens but also pathogen-associated molecular patterns (PAMPs) originating from environmental or symbiotic microbes. According to either "self/non-self" or "danger" models, this should systematically result in homeostasis breakdown and the development of immune responses directed to inhaled harmless antigens, such as T helper type (Th)2-mediated asthmatic reactions, which is fortunately not the case in most people. This discrepancy implies the existence, in the lung, of regulatory mechanisms that tightly control immune homeostasis. Although such mechanisms have been poorly investigated in comparison to the ones that trigger immune responses, a better understanding of them could be useful in the development of new therapeutic strategies against lung diseases (e.g., asthma). Here, we review current knowledge on innate immune cells that prevent the development of aberrant immune responses in the lung, thereby contributing to mucosal homeostasis.

Helicobacter pylori Chronic-Stage Inflammation Undergoes Fluctuations That Are Altered in tlpA Mutants

Helicobacter pylori colonizes half of the world's population and is responsible for a significant disease burden by causing gastritis, peptic ulcers, and gastric cancer. The development of host inflammation drives these diseases, but there are still open questions in the field about how H. pylori controls this process. We characterized H. pylori inflammation using an 8-month mouse infection time course and comparison of the wild type (WT) and a previously identified mutant lacking the TlpA chemoreceptor that causes elevated inflammation. Our work shows that H. pylori chronic-stage corpus inflammation undergoes surprising fluctuations, with changes in Th17 and eosinophil numbers. The H. pylori tlpA mutant changed the inflammation temporal characteristics, resulting in different inflammation from the wild type at some time points. tlpA mutants have equivalent total and gland colonization in late-stage infections. During early infection, in contrast, they show elevated gland and total colonization compared to those by WT. Our results suggest the chronic inflammation setting is dynamic and may be influenced by colonization properties of early infection.

Treatment with Helicobacter pylori-derived VacA attenuates allergic airway disease

Background

Asthma is an incurable heterogeneous disease with variations in clinical and underlying immunological phenotype. New approaches could help to support existing therapy concepts. Neonatal infection of mice with Helicobacter pylori or administration of H. pylori-derived extracts or molecules after birth have been shown to prevent the development of allergic airway disease later in life. This study evaluated the potential therapeutic efficacy of H. pylori vacuolating cytotoxin A (VacA) in allergic airway inflammation and investigated the underlying immunological mechanisms for its actions.

Methods

Murine models of allergic airway diseases, and murine and human in vitro models were used.

Results

In both an acute model and a therapeutic house dust mite model of allergic airway disease, treatment with H. pylori-derived VacA reduced several asthma hallmarks, including airway hyperresponsiveness, inflammation and goblet cell metaplasia. Flow cytometry and ELISA analyses revealed induction of tolerogenic dendritic cells (DC) and FoxP3 positive regulatory T cells (Tregs), and a shift in the composition of allergen-specific immunoglobulins. Depletion of Tregs during treatment with VacA reversed treatment-mediated suppression of allergic airway disease. Human monocyte derived DCs (moDC) that were exposed to VacA induced Tregs in co-cultured naïve autologous T cells, replicating key observations made in vivo.

Conclusion

H. pylori-derived VacA suppressed allergic airway inflammation via induction of Tregs in both allergic airway disease models. These data suggest that the immunomodulatory activity of VacA could potentially be exploited for the prevention and treatment of allergic airway disease.

Immune Biology and Persistence of Helicobacter pylori in Gastric Diseases

Helicobacter pylori is a prevalent pathogen, which affects more than 40% of the global population. It colonizes the human stomach and persists in its host for several decades or even a lifetime, if left untreated. The persistent infection has been linked to various gastric diseases, including gastritis, peptic ulcers, and an increased risk for gastric cancer. H. pylori infection triggers a strong immune response directed against the bacterium associated with the infiltration of innate phagocytotic immune cells and the induction of a Th1/Th17 response. Even though certain immune cells seem to be capable of controlling the infection, the host is unable to eliminate the bacteria as H. pylori has developed remarkable immune evasion strategies. The bacterium avoids its killing through innate recognition mechanisms and manipulates gastric epithelial cells and immune cells to support its persistence. This chapter focuses on the innate and adaptive immune response induced by H. pylori infection, and immune evasion strategies employed by the bacterium to enable persistent infection.

Helicobacter pylori Immune Response in Children Versus Adults

H. pylori is perhaps the most prevalent human pathogen worldwide and infects almost half of the world's population. Despite the decreasing prevalence of infection overall, it is significant in developing countries. Most infections are acquired in childhood and persist for a lifetime unless treated. Children are often asymptomatic and often develop a tolerogenic immune response that includes T regulatory cells and their products, immunosuppressive cytokines, such as interleukin (IL)-10, and transforming growth factor-β (TGF-β). This contrasts to the gastric immune response seen in H. pylori-infected adults, where the response is mainly inflammatory, with predominant Th1 and Th17 cells, as well as, inflammatory cytokines, such as TNF-α, IFN-γ, IL-1, IL-6, IL-8, and IL-17. Therefore, compared to adults, infected children generally have limited gastric inflammation and peptic ulcer disease. H. pylori surreptitiously subverts immune defenses to persist in the human gastric mucosa for decades. The chronic infection might result in clinically significant diseases in adults, such as peptic ulcer disease, gastric adenocarcinoma, and mucosa-associated lymphoid tissue lymphoma. This review compares the infection in children and adults and highlights the H. pylori virulence mechanisms responsible for the pathogenesis and immune evasion.

Intrapericardial Exosome Therapy Dampens Cardiac Injury via Activating Foxo3

BACKGROUND

Mesenchymal stem cell (MSC)-derived exosomes are well recognized immunomodulating agents for cardiac repair, while the detailed mechanisms remain elusive. The Pericardial drainage pathway provides the heart with immunosurveillance and establishes a simplified model for studying the mechanisms underlying the immunomodulating effects of therapeutic exosomes.

METHODS

Myocardial infarction (MI) models with and without pericardiectomy (corresponding to Tomy MI and NonTomy MI) were established to study the functions of pericardial drainage pathway in immune activation of cardiac-draining mediastinal lymph node (MLN). Using the NonTomy MI model, MSC exosomes or vehicle PBS was intrapericardially injected for MI treatment. Via cell sorting and RNA-seq (RNA-sequencing) analysis, the differentially expressed genes were acquired for integrated pathway analysis to identify responsible mechanisms. Further, through functional knockdown/inhibition studies, application of cytokines and neutralizing antibodies, western blot, flow cytometry, and cytokine array, the molecular mechanisms were studied. In addition, the therapeutic efficacy of intrapericardially injected exosomes for MI treatment was evaluated through functional and histological analyses.

RESULTS

We show that the pericardial draining pathway promoted immune activation in the MLN following MI. Intrapericardially injected exosomes accumulated in the MLN and induced regulatory T cell differentiation to promote cardiac repair. Mechanistically, uptake of exosomes by major histocompatibility complex (MHC)-II+ antigen-presenting cells (APCs) induced Foxo3 activation via the protein phosphatase (PP)-2A/p-Akt/forkhead box O3 (Foxo3) pathway. Foxo3 dominated APC cytokines (IL-10, IL-33, and IL-34) expression and built up a regulatory T cell (Treg)-inducing niche in the MLN. The differentiation of Tregs as well as their cardiac deployment were elevated, which contributed to cardiac inflammation resolution and cardiac repair.

CONCLUSIONS

This study reveals a novel mechanism underlying the immunomodulation effects of MSC exosomes and provides a promising candidate (PP2A/p-Akt/Foxo3 signaling pathway) with a favorable delivery route (intrapericardial injection) for cardiac repair.

Pathogenic roles and diagnostic utility of interleukin-18 in autoinflammatory diseases

Interleukin (IL)-18 is a pleiotropic, pro-inflammatory cytokine involved in the regulation of innate and adaptive immune responses. IL-18 has attracted increasing attention as a key mediator in autoinflammatory diseases associated with the development of macrophage activation syndrome (MAS) including systemic juvenile idiopathic arthritis and adult-onset Still’s disease. In these diseases, dysregulation of inflammasome activity and overproduction of IL-18 might be associated with the development of MAS by inducing natural killer cell dysfunction. Serum IL-18 levels are high in patients with these diseases and therefore are useful for the diagnosis and monitoring of disease activity. In contrast, a recent study revealed the overproduction of IL-18 was present in cases of autoinflammation without susceptibility to MAS such as pyogenic sterile arthritis, pyoderma gangrenosum, and acne (PAPA) syndrome. The pathogenic and causative roles of IL-18 remain unclear in these autoinflammatory diseases. Further investigations are necessary to clarify the role of IL-18 and its importance as a therapeutic target in the pathogenesis of autoinflammatory diseases.

The Efficacy of Cancer Immunotherapies Is Compromised by Helicobacter pylori Infection

Helicobacter pylori infects the gastric mucosa of a large number of humans. Although asymptomatic in the vast majority of cases, H pylori infection can lead to the development of peptic ulcers gastric adenocarcinoma and mucosa-associated lymphoid tissue (MALT) lymphoma. Using a variety of mechanisms, H pylori locally suppresses the function of the host immune system to establish chronic infection. Systemic immunomodulation has been observed in both clinical and pre-clinical studies, which have demonstrated that H pylori infection is associated with reduced incidence of inflammatory diseases, such as asthma and Crohn’s disease. The introduction of immunotherapies in the arsenal of anti-cancer drugs has revealed a new facet of H pylori-induced immune suppression. In this review, we will describe the intimate interactions between H pylori and its host, and formulate hypothtyeses describing the detrimental impact of H pylori infection on the efficacy of cancer immunotherapies.

Helicobacter pylori and the Role of Lipopolysaccharide Variation in Innate Immune Evasion

Helicobacter pylori is an important human pathogen that infects half the human population and can lead to significant clinical outcomes such as acute and chronic gastritis, duodenal ulcer, and gastric adenocarcinoma. To establish infection, H. pylori employs several mechanisms to overcome the innate and adaptive immune systems. H. pylori can modulate interleukin (IL) secretion and innate immune cell function by the action of several virulence factors such as VacA, CagA and the type IV secretion system. Additionally, H. pylori can modulate local dendritic cells (DC) negatively impacting the function of these cells, reducing the secretion of immune signaling molecules, and influencing the differentiation of CD4⁺ T helper cells causing a bias to Th1 type cells. Furthermore, the lipopolysaccharide (LPS) of H. pylori displays a high degree of phase variation and contains human blood group carbohydrate determinants such as the Lewis system antigens, which are proposed to be involved in molecular mimicry of the host. Lastly, the H. pylori group of outer membrane proteins such as BabA play an important role in attachment and interaction with host Lewis and other carbohydrate antigens. This review examines the various mechanisms that H. pylori utilises to evade the innate immune system as well as discussing how the structure of the H. pylori LPS plays a role in immune evasion.

Your Regulatory T Cells Are What You Eat: How Diet and Gut Microbiota Affect Regulatory T Cell Development

Modern industrial practices have transformed the human diet over the last century, increasing the consumption of processed foods. Dietary imbalance of macro- and micro-nutrients and excessive caloric intake represent significant risk factors for various inflammatory disorders. Increased ingestion of food additives, residual contaminants from agricultural practices, food processing, and packaging can also contribute deleteriously to disease development. One common hallmark of inflammatory disorders, such as autoimmunity and allergies, is the defect in anti-inflammatory regulatory T cell (Treg) development and/or function. Treg represent a highly heterogeneous population of immunosuppressive immune cells contributing to peripheral tolerance. Tregs either develop in the thymus from autoreactive thymocytes, or in the periphery, from naïve CD4⁺ T cells, in response to environmental antigens and cues. Accumulating evidence demonstrates that various dietary factors can directly regulate Treg development. These dietary factors can also indirectly modulate Treg differentiation by altering the gut microbiota composition and thus the production of bacterial metabolites. This review provides an overview of Treg ontogeny, both thymic and peripherally differentiated, and highlights how diet and gut microbiota can regulate Treg development and function.

Helicobacter pylori infection has a detrimental impact on the efficacy of cancer immunotherapies

OBJECTIVE

In this study, we determined whether Helicobacter pylori (H. pylori) infection dampens the efficacy of cancer immunotherapies.

DESIGN

Using mouse models, we evaluated whether immune checkpoint inhibitors or vaccine-based immunotherapies are effective in reducing tumour volumes of H. pylori-infected mice. In humans, we evaluated the correlation between H. pylori seropositivity and the efficacy of the programmed cell death protein 1 (PD-1) blockade therapy in patients with non-small-cell lung cancer (NSCLC).

RESULTS

In mice engrafted with MC38 colon adenocarcinoma or B16-OVA melanoma cells, the tumour volumes of non-infected mice undergoing anticytotoxic T-lymphocyte-associated protein 4 and/or programmed death ligand 1 or anti-cancer vaccine treatments were significantly smaller than those of infected mice. We observed a decreased number and activation status of tumour-specific CD8⁺ T cells in the tumours of infected mice treated with cancer immunotherapies independent of the gut microbiome composition. Additionally, by performing an in vitro co-culture assay, we observed that dendritic cells of infected mice promote lower tumour-specific CD8⁺ T cell proliferation. We performed retrospective human clinical studies in two independent cohorts. In the Dijon cohort, H. pylori seropositivity was found to be associated with a decreased NSCLC patient survival on anti-PD-1 therapy. The survival median for H. pylori seropositive patients was 6.7 months compared with 15.4 months for seronegative patients (p=0.001). Additionally, in the Montreal cohort, H. pylori seropositivity was found to be associated with an apparent decrease of NSCLC patient progression-free survival on anti-PD-1 therapy.

CONCLUSION

Our study unveils for the first time that the stomach microbiota affects the response to cancer immunotherapies and that H. pylori serology would be a powerful tool to personalize cancer immunotherapy treatment.

Epithelial Pyroptosis in Host Defense

Pyroptosis is a lytic form of cell death that is executed by a family of pore-forming proteins called gasdermins (GSDMs). GSDMs are activated upon proteolysis by host proteases including the proinflammatory caspases downstream of inflammasome activation. In myeloid cells, GSDM pore formation serves two primary functions in host defense: the selective release of processed cytokines to initiate inflammatory responses, and cell death, which eliminates a replicative niche of the pathogen. Barrier epithelia also undergo pyroptosis. However, unique mechanisms are required for the removal of pyroptotic epithelial cells to maintain epithelial barrier integrity. In the following review, we discuss the role of epithelial inflammasomes and pyroptosis in host defense against pathogens. We use the well-established role of inflammasomes in intestinal epithelia to highlight principles of epithelial pyroptosis in host defense of barrier tissues, and discuss how these principles might be shared or distinctive across other epithelial sites.

Association of gastric lymphofollicular hyperplasia with Helicobacter-like organisms in dogs

Background

The relationships among gastric lymphoid follicular hyperplasia (GLFH), Helicobacter‐like organisms (HLOs), and clinical signs have not been established in dogs.

Objectives

To evaluate the epidemiologic, clinical, endoscopic, and histopathologic findings associated with GLFH in dogs, and determine the association of GLFH with HLOs and the French Bulldog (FB) breed.

Animals

Two hundred eighty‐eight dogs that underwent gastroscopy between 2013 and 2016.

Methods

Retrospective, cross‐sectional study. Gastric biopsy samples were reviewed and scored for inflammation and HLOs. Dogs were divided into 3 groups: group 1 (63 FBs), group 2 (45 non‐FB brachycephalic dogs), and group 3 (180 nonbrachycephalic dogs). Variables were evaluated for their association with GLFH.

Results

Univariate analysis determined that intact males, young age, vomiting, gastroscopic findings (discoloration, hemorrhage, and ulcers), and histopathologic findings (gastric lamina propria lymphocytic infiltration and HLO score) were associated with GLFH (P ≤ .03). In the multivariate analysis, GLFH was associated with the HLO score (odds ratio [OR] > 5 for HLO scores 1‐2 and >15 for HLO score of 3; P < .001), with vomiting (OR > 4; P = .01) but not with FB breed (P = .76) and age (P = .1). The HLO score was associated with younger age (P < .001).

Conclusion and Clinical Importance

The HLO score was associated with a high GLFH score. Vomiting was associated with GLFH. Helicobacter‐like organisms are highly prevalent in young dogs and GLFH is indirectly associated with this factor. Clinical relevance of the identification of GLFH and HLO remains to be determined.

Circulating LIGHT (TNFSF14) and Interleukin-18 Levels in Sepsis-Induced Multi-Organ Injuries

The novel therapeutic target cytokine LIGHT (TNFSF14) was recently shown to play a major role in COVID-19-induced acute respiratory distress syndrome (ARDS). This study aims to investigate the associations of plasma LIGHT and another potentially targetable cytokine, interleukin-18 (IL-18), with ARDS, acute hypoxic respiratory failure (AHRF), or acute kidney injury (AKI), caused by non-COVID-19 viral or bacterial sepsis. A total of 280 subjects diagnosed with sepsis, including 91 cases with sepsis triggered by viral infections, were investigated in this cohort study. Day 0 plasma LIGHT and IL-18, as well as 59 other biomarkers (cytokines, chemokines, and acute-phase reactants) were measured by sensitive bead immunoassay and associated with symptom severity. We observed significantly increased LIGHT level in both bacterial sepsis patients (p = 1.80 × 10⁻⁵) and patients with sepsis from viral infections (p = 1.78 × 10⁻³). In bacterial sepsis, increased LIGHT level was associated with ARDS, AKI, and higher Apache III scores, findings also supported by correlations of LIGHT with other biomarkers of organ failure. IL-18 levels were highly variable across individuals and consistently correlated with Apache III scores, mortality, and AKI in both bacterial and viral sepsis. There was no correlation between LIGHT and IL-18. For the first time, we demonstrate independent effects of LIGHT and IL-18 in septic organ failure. The association of plasma LIGHT with AHRF suggests that targeting the pathway warrants exploration, and ongoing trials may soon elucidate whether this is beneficial. Given the large variance of plasma IL-18 among septic subjects, targeting this pathway requires precise application.

The interplay between Helicobacter pylori and gastrointestinal microbiota

The complex population of microbes in the human gastrointestinal (GI) tract interacts with itself and with the host, exerting a deep influence on health and disease development. The development of modern sequencing technology has enabled us to gain insight into GI microbes. Helicobacter pylori colonization significantly affects the gastric microenvironment, which in turn affects gastric microbiota and may be correlated with colonic microbiota changes. Crosstalk between H. pylori and GI commensal flora may play a role in H. pylori-related carcinogenicity and extragastric manifestations. We review current knowledge on how H. pylori shapes GI microbiota with a specific focus on its impact on the stomach and colon. We also review current evidence on colonic microbiota changes attributed to eradication therapy based on the clinical studies performed to date.

Immunological Perspective: Helicobacter pylori Infection and Gastritis

Helicobacter pylori is a spiral-shaped gram-negative bacterium. Its infection is mainly transmitted via oral-oral and fecal-oral routes usually during early childhood. It can achieve persistent colonization by manipulating the host immune responses, which also causes mucosal damage and inflammation. H. pylori gastritis is an infectious disease and results in chronic gastritis of different severity in near all patients with infection. It may develop from acute/chronic inflammation, chronic atrophic gastritis, intestinal metaplasia, dysplasia, and intraepithelial neoplasia, eventually to gastric cancer. This review attempts to cover recent studies which provide important insights into how H. pylori causes chronic inflammation and what the characteristic is, which will immunologically explain H. pylori gastritis.

Helicobacter pylori and its association with autoimmune diseases: systemic lupus erythematosus, rheumatoid arthritis and Sjögren syndrome

Helicobacter pylori (H. pylori) is a gram-negative bacterium that adapts to the gastric mucosa and provokes symptoms associated with gastritis. Chronic H. pylori infection in patients with a genetic predisposition can trigger autoimmune diseases due to the immune interaction of cellular and humoral responses. Infections are a triggering factor for systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), and Sjögren syndrome (SS), although the association between H. pylori and these diseases is unclear. Therefore, we reviewed this interaction and its clinical importance.

Immunogenetic, Molecular and Microbiotic Determinants of Eosinophilic Esophagitis and Clinical Practice-A New Perspective of an Old Disease

Eosinophilic oesophagitis (EoE) is a chronic, allergic disease associated with a T-lymphocyte response inducing esophageal eosinophilic infiltration in the esophagus. Inflammation and tissue fibrosis are responsible for the main clinical symptoms such as food impaction and dysphagia. The etiopathogenesis is multifactorial in which genetic and environmental factors coexist. The most common trigger is a non-IgE-mediated food allergy to milk, wheat, egg, soybean, nuts, fish, and seafood. The second factor we focus on is the contribution of genetic variation to the risk of EoE, describing the expression profile of selected genes associated with eosinophilic oesophagitis. We raise the topic of treatment, aiming to eliminate inflammation through an elimination diet and/or use of pharmacologic therapy with the use of proton pump inhibitors or steroids and endoscopic procedures to dilate the esophagus. We demonstrate that early diagnosis and effective treatment prevent the development of food impaction and decreased quality of life. The increasing presence of EoE requires bigger awareness among medical specialists concerning clinical features, the course of EoE, diagnostic tools, and management strategies.

Association between Helicobacter pylori infection and mortality risk in prostate cancer patients receiving androgen deprivation therapy: A real-world evidence study

Purpose

Helicobacter pylori (H. pylori) is a major risk factor for gastric cancer and may affect androgen activity in men. The association between H. pylori and androgen deprivation therapy (ADT) in patients with prostate cancer (PCa) remains unclear.

Methods

This retrospective cohort study linked National Health Insurance (NHI) data to Taiwan Cancer Registry (TCR) and Taiwan Death Registry (TDR) between 1995 and 2016. PCa patients who received ADT were classified into H. pylori infection and non‐H. pylori infection groups. The outcomes were overall mortality, prostate cancer‐specific mortality, and castration‐resistant prostate cancer (CRPC). Propensity score matching was adopted for the primary analysis and inverse probability of treatment weighting (IPTW) was used for the sensitivity analysis.

Results

Of the 62,014 selected PCa patients, 23,701 received ADT, of whom 3516 had H. pylori infections and 20,185 did not. After matching, there were 3022 patients in the H. pylori infection group and 6044 patients in the non‐H. pylori infection group. The mean follow‐up period for the matched cohort was 4.8 years. Compared to the non‐H. pylori group, the H. pylori group was significantly associated with decreased risks of all‐cause mortality (hazard ratio [HR] 0.90; 95% confidence interval [CI] 0.84–0.96) and prostate cancer‐specific mortality (HR 0.88; 95% CI 0.81–0.95) in the matched analysis.

Conclusions

H. pylori infection was associated with a reduced risk of mortality in PCa patients receiving ADT.

Obesity-related IL-18 Impairs Treg Function and Promotes Lung Ischemia-reperfusion Injury

RATIONALE

Primary graft dysfunction (PGD) is a severe form of acute lung injury, leading to increased early morbidity and mortality after lung transplantation. Obesity is a major health problem, and recipient obesity is one of the most significant risk factors for developing PGD.

OBJECTIVES

We hypothesized that T-regulatory (Treg) cells are able to dampen early ischemia/reperfusion events and thereby decrease risk of PGD, whereas that action is impaired in obese recipients.

METHODS

We evaluated Treg, T cells and inflammatory markers, plus clinical data, in 79 lung and 41 liver or kidney transplant recipients and studied two groups of mice on high fat diet (HFD), who developed ("inflammatory" HFD) or not ("healthy" HFD) low-grade inflammation with decreased Treg function.

RESULTS

We identified increased levels of IL-18 as a previously unrecognized mechanism that impairs Treg suppressive function in obese individuals. IL-18 decreases levels of FOXP3, the key Treg transcription factor, decreases FOXP3 di- and oligomerization and increases the ubiquitination and proteasomal degradation of FOXP3. IL-18-treated Tregs or Treg from obese mice fail to control PGD, while IL-18 inhibition ameliorates lung inflammation. The IL-18 driven impairment in Treg suppressive function pre-transplant was associated with increased risk and severity of PGD in clinical lung transplant recipients.

CONCLUSION

Obesity-related IL-18 induces Treg dysfunction that may contribute to the pathogenesis of PGD. Evaluation of Treg suppressive function along with IL-18 levels may serve as screening tools to identify pre-transplant obese recipients with increased risk of PGD.

Helicobacter pylori induces gastric cancer via down-regulating miR-375 to inhibit dendritic cell maturation

BACKGROUND

Recent studies and clinical samples have demonstrated that Helicobacter pylori could induce the downregulation of miR-375 in the stomach and promote gastric carcinogenesis. However, whether the immune cells are affected by Helicobacter pylori due to the downregulation of miR-375 is unclear.

MATERIALS AND METHODS

In this study, we constructed an overexpression and knockdown of miR-375 and Helicobacter pylori infection cell models in vitro. In addition, the maturity of dendritic cells (DCs) and the expression of IL-6, IL-10, and VEGF at the transcriptional and translational levels were analyzed. Changes in the JAK2-STAT3 signaling pathway were detected. In vivo, the number changes in CD4+ T and CD8+ T cells and the size changes of tumors via models of transplantable subcutaneous tumors were also analyzed.

RESULTS

A cell model of Helicobacter pylori and gastric cancer was used to identify the expression of miR-375 and the maturity of dendritic cells. This study found that Helicobacter pylori could downregulate miR-375, which regulates the expression of cytokines IL-6, IL-10, and VEGF in the stomach. MiR-375 regulated the expression of cytokines IL-6, IL-10, and VEGF through the JAK2-STAT3 signaling pathway in vitro. In addition, we found that Helicobacter pylori regulates the maturation of dendritic cells through miR-375. These results were further verified in vivo, and miR-375 diminishes tumor size was also demonstrated. This study showed that immature DCs caused a decrease in the number of CD4+ and CD8+ T cells.

CONCLUSIONS

This study demonstrated that Helicobacter pylori can inhibit miRNA-375 expression in the stomach. Downregulated miR-375 activates the JAK2-STAT3 pathway. Activating the JAK2-STAT3 signaling pathway promotes the secretion of IL-6, IL-10, and VEGF, leading to immature differentiation of DCs and induction of gastric cancer.

AIM2 regulates anti-tumor immunity and is a viable therapeutic target for melanoma

The STING and absent in melanoma 2 (AIM2) pathways are activated by the presence of cytosolic DNA, and STING agonists enhance immunotherapeutic responses. Here, we show that dendritic cell (DC) expression of AIM2 within human melanoma correlates with poor prognosis and, in contrast to STING, AIM2 exerts an immunosuppressive effect within the melanoma microenvironment. Vaccination with AIM2-deficient DCs improves the efficacy of both adoptive T cell therapy and anti–PD-1 immunotherapy for “cold tumors,” which exhibit poor therapeutic responses. This effect did not depend on prolonged survival of vaccinated DCs, but on tumor-derived DNA that activates STING-dependent type I IFN secretion and subsequent production of CXCL10 to recruit CD8⁺ T cells. Additionally, loss of AIM2-dependent IL-1β and IL-18 processing enhanced the treatment response further by limiting the recruitment of regulatory T cells. Finally, AIM2 siRNA-treated mouse DCs in vivo and human DCs in vitro enhanced similar anti-tumor immune responses. Thus, targeting AIM2 in tumor-infiltrating DCs is a promising new treatment strategy for melanoma.

Spatial and temporal key steps in early-life intestinal immune system development and education

Education of our intestinal immune system early in life strongly influences adult health. This education strongly relies on series of events that must occur in well-defined time windows. From initial colonization by maternal-derived microbiota during delivery to dietary changes from mother's milk to solid foods at weaning, these early-life events have indeed long-standing consequences on our immunity, facilitating tolerance to environmental exposures or, on the contrary, increasing the risk of developing noncommunicable diseases such as allergies, asthma, obesity, and inflammatory bowel diseases. In this review, we provide an outline of the recent advances in our understanding of these events and how they are mechanistically related to intestinal immunity development and education. First, we review the susceptibility of neonates to infections and inflammatory diseases, related to their immune system and microbiota changes. Then, we highlight the maternal factors involved in protection and education of the mucosal immune system of the offspring, the role of the microbiota, and the nature of neonatal immune system until weaning. We also present how the development of some immune responses is intertwined in temporal and spatial windows of opportunity. Finally, we discuss pending questions regarding the neonate particular immune status and the activation of the intestinal immune system at weaning.