Immune response modulation in inflammatory bowel diseases by Helicobacter pylori infection

Navigating new horizons in inflammatory bowel disease: Integrative approaches and innovations

This editorial offers an updated synthesis of the major advancements in the management and treatment of inflammatory bowel disease (IBD), as documented in the World Journal of Gastroenterology between 2023 and early 2024. This editorial explores substantial developments across key research areas, such as intestinal microecology, computational drug discovery, dual biologic therapy, telemedicine, and the integration of lifestyle changes into patient care. Furthermore, the discussion of emerging topics, including bowel preparation in colonoscopy, the impact of the coronavirus disease 2019 pandemic, and the intersection between IBD and mental health, reflects a shift toward a more holistic approach to IBD research. By integrating these diverse areas of research, this editorial seeks to promote a holistic and multidisciplinary approach to IBD treatment, combining emerging technologies, personalized medicine, and conventional therapies to improve patient outcomes.

Helicobacter pylori infection and inflammatory bowel disease: a 2-sample Mendelian randomization study

Introduction

Observational studies have discovered a contradictory phenomenon between Helicobacter pylori (H. pylori) infection and inflammatory bowel disease (IBD). The study aimed to confirm the causal association between H. pylori and IBD, including ulcerative colitis (UC) and Crohn's disease (CD).

Methods

We conducted a Mendelian randomization (MR) study with two sample Genome-Wide Association Studies (GWAS) to determine whether there is a causal relationship between H. pylori infection and IBD, as well as the possible pathogenic factors that may be involved. The reliability of the main MR assumptions was examined through a series of sensitivity analyses.

Results

Two genetic variants (SNPs) previously identified were employed as instrumental variables (IVs) for H. pylori infection. GWAS data for IBD, UC, and CD were obtained from the recent DF10 release10 of the FinnGen study. Our findings indicated a significant association between H. pylori seropositivity and an increased risk of IBD and UC (IBD: OR: 1.16, 95% CI, 1.03-1.31, P < 0.05; UC: OR: 1.22, 95% CI, 1.08-1.37, P < 0.001) while no causal relationship with CD (P > 0.05). Analysis of the main virulence pathogenic factors revealed a causal relationship between cytotoxin-associated protein A (CagA) and IBD and UC (IBD: OR: 1. 06, 95% CI, 1.001-1.11, P < 0.05; UC: OR: 1.07, 95% CI, 1.004-1.14, P < 0.05), while no correlation was found for vacuolar cytotoxin A (VacA) (P > 0.05). After applying the False Discovery Rate (FDR) correction, the causal relationship between CagA and the risk of IBD or UC was no longer statistically significant.

Conclusion

This study suggests a potential causal relationship between H. pylori infection and IBD, particularly UC. The effect may be more pronounced in individuals with previous H. pylori infections.

Helicobacter pylori in Inflammatory Bowel Diseases: Active Protagonist or Innocent Bystander?

Helicobacter pylori (H. pylori) infection is a prominent entity within human infectious diseases which cause chronic gastritis, peptic ulcers, gastric malignancies, and extragastric disorders. Its persistent colonization can lead to a systemic inflammatory cascade, potentially instigating autoimmune responses and contributing to the pathogenesis of autoimmune diseases. While the specific etiopathogenesis of inflammatory bowel diseases (IBDs) is still unknown, it is widely recognized that immunological, genetic, and environmental factors are implicated. Various bacterial and viral pathogens have been implicated in the pathogenesis of IBDs. Numerous studies suggest a correlation between H. pylori infection and IBDs. While subject to debate, this link suggests that the bacterium's presence somehow impacts the progression of IBDs by modifying the diversity of the gut microbiota, consequently altering local chemical profiles and disrupting the pattern of gut immune response. However, epidemiological evidence indicates a protective role of H. pylori infection against the onset of autoimmune diseases. Additionally, laboratory findings demonstrate H. pylori's capacity to promote immune tolerance and restrict inflammatory reactions. The aim of this review is to elucidate the proposed mechanisms and confounding factors that underlie the potential association between H. pylori infection and IBDs.

When inflammatory stressors dramatically change, disease phenotypes may transform between autoimmune hematopoietic failure and myeloid neoplasms

Aplastic anemia (AA) and hypoplastic myelodysplastic syndrome are paradigms of autoimmune hematopoietic failure (AHF). Myelodysplastic syndrome and acute myeloid leukemia are unequivocal myeloid neoplasms (MNs). Currently, AA is also known to be a clonal hematological disease. Genetic aberrations typically observed in MNs are detected in approximately one-third of AA patients. In AA patients harboring MN-related genetic aberrations, a poor response to immunosuppressive therapy (IST) and an increased risk of transformation to MNs occurring either naturally or after IST are predicted. Approximately 10%-15% of patients with severe AA transform the disease phenotype to MNs following IST, and in some patients, leukemic transformation emerges during or shortly after IST. Phenotypic transformations between AHF and MNs can occur reciprocally. A fraction of advanced MN patients experience an aplastic crisis during which leukemic blasts are repressed. The switch that shapes the disease phenotype is a change in the strength of extramedullary inflammation. Both AHF and MNs have an immune-active bone marrow (BM) environment (BME). In AHF patients, an inflamed BME can be evoked by infiltrated immune cells targeting neoplastic molecules, which contributes to the BM-specific autoimmune impairment. Autoimmune responses in AHF may represent an antileukemic mechanism, and inflammatory stressors strengthen antileukemic immunity, at least in a significant proportion of patients who have MN-related genetic aberrations. During active inflammatory episodes, normal and leukemic hematopoieses are suppressed, which leads to the occurrence of aplastic cytopenia and leukemic cell regression. The successful treatment of underlying infections mitigates inflammatory stress-related antileukemic activities and promotes the penetration of leukemic hematopoiesis. The effect of IST is similar to that of treating underlying infections. Investigating inflammatory stress-powered antileukemic immunity is highly important in theoretical studies and clinical practice, especially given the wide application of immune-activating agents and immune checkpoint inhibitors in the treatment of hematological neoplasms.

Effects of Helicobacter pylori infection on intestinal microbiota, immunity and colorectal cancer risk

Infecting about half of the world´s population, Helicobacter pylori is one of the most prevalent bacterial infections worldwide and the strongest known risk factor for gastric cancer. Although H. pylori colonizes exclusively the gastric epithelium, the infection has also been associated with various extragastric diseases, including colorectal cancer (CRC). Epidemiological studies reported an almost two-fold increased risk for infected individuals to develop CRC, but only recently, direct causal and functional links between the chronic infection and CRC have been revealed. Besides modulating the host intestinal immune response, H. pylori is thought to increase CRC risk by inducing gut microbiota alterations. It is known that H. pylori infection not only impacts the gastric microbiota at the site of infection but also leads to changes in bacterial colonization in the distal large intestine. Considering that the gut microbiome plays a driving role in CRC, H. pylori infection emerges as a key factor responsible for promoting changes in microbiome signatures that could contribute to tumor development. Within this review, we want to focus on the interplay between H. pylori infection, changes in the intestinal microbiota, and intestinal immunity. In addition, the effects of H. pylori antibiotic eradication therapy will be discussed.