Cytotoxin-associated gene A (CagA) promotes aortic endothelial inflammation and accelerates atherosclerosis through the NLRP3/caspase-1/IL-1β axis

Beyond the gut: a comprehensive meta-analysis on Helicobacter pylori infection and cardiovascular complications

BACKGROUND

Helicobacter pylori (H. pylori) is known to induce chronic inflammatory conditions, and interactions between the host immune system and pathogen have diverted attention toward investigating its correlation with extra-gastrointestinal disorders.

OBJECTIVE

The present study aimed to assess the rate of H. pylori infection in cardiovascular disease (CVD) through a systematic review and meta-analysis.

METHODS

We conducted a large-scale meta-analysis to determine the prevalence rates of H. pylori infection in vascular diseases. Articles from PubMed/Medline, Web of Science, and Embase databases published between 2000 and 2023 were included for analysis. We used multiple independent observers to extract data, calculated the pooled frequency of H. pylori in vascular diseases using a random effect model, and reported the results as a weighted average based on the study population. The main outcome measures were presented with 95% confidence intervals (CI).

RESULTS

In 87 included studies, the prevalence of H. pylori infection in vascular diseases was 56.7% worldwide. 14.25% of H. pylori isolates harbored the cagA gene. The predominant vascular complication was coronary artery disease (CAD) (31.07%), primarily documented in Europe. This meta-analysis revealed a declining emphasis on studying the association of H. pylori infection with vascular disease in recent times.

CONCLUSION

According to this meta-analysis, H. pylori infection has a high frequency in CVD and may increase the risk of vascular diseases. However, further research is required, particularly in nations with limited data.

Helicobacter pylori, Atherosclerosis, and Coronary Artery Disease: A Narrative Review

Coronary artery disease (CAD) is one of the leading causes of death worldwide, significantly contributing to mortality in both developed and developing nations. CAD arises from a combination of risk factors, including atherosclerosis, dyslipidemia, hypertension, diabetes, and smoking. In recent years, growing evidence has suggested a potential link between infectious agents and cardiovascular diseases. Among these, Helicobacter pylori (H. pylori) infection has been hypothesized for over a decade to play a role in the pathogenesis of CAD. This hypothesis is based on the bacterium's ability to trigger host inflammatory or autoimmune responses, potentially contributing to the progression of atherosclerotic plaques and coronary events. The association between H. pylori infection and CAD is of considerable interest as it opens new avenues for prevention and management strategies in cardiovascular health. Understanding this relationship could lead to innovative approaches to reducing the burden of CAD, particularly in populations with a high prevalence of H. pylori. In this review, we aim to provide a comprehensive overview of the most recent evidence on the involvement of H. pylori in the development and prognosis of CAD. By analyzing and synthesizing current findings, we seek to shed light on unresolved questions and clarify the ambiguous aspects of this potential connection. Our goal is to contribute to a deeper understanding of how H. pylori, may influence cardiovascular disease and to inspire further research in this critical area.

Clinical significance of serum Helicobacter pylori antibody cytotoxin-associated gene A levels in patients with unstable angina

OBJECTIVES

We investigated the clinical significance of serum Helicobacter pylori cytotoxin-associated gene A (CagA) antibody levels in 768 patients with unstable angina (UA).

METHODS

Serum CagA levels were measured using ELISA. Demographic data, serum biomarkers, and SYNTAX scores were collected. Patients were followed up for 1 year for major adverse cardiac events (MACE).

RESULTS

CagA-positive UA patients had higher total cholesterol and hsCRP levels, and SYNTAX scores. CagA levels correlated positively with TC, hsCRP, and SYNTAX scores. Kaplan-Meier analysis showed shorter MACE-free survival in CagA-positive UA patients. CagA levels predicted MACE occurrence within 1 year, along with SYNTAX scores.

CONCLUSIONS

Serum H. pylori CagA antibody positivity is associated with worse prognosis in UA patients. CagA levels correlate with lipid metabolism and inflammatory markers.

Extracellular vesicles and endothelial dysfunction in infectious diseases

Cardiovascular diseases (CVDs) remain the leading cause of mortality and morbidity globally. Studies have shown that infections especially bacteraemia and sepsis are associated with increased risks for endothelial dysfunction and related CVDs including atherosclerosis. Extracellular vesicles (EVs) are small, sealed membrane-derived structures that are released into body fluids and blood from cells and/or microbes and are critically involved in a variety of important cell functions and disease development, including intercellular communications, immune responses and inflammation. It is known that EVs-mediated mechanism(s) is important in the development of endothelial dysfunction in infections with a diverse spectrum of microorganisms including Escherichia coli, Candida albicans, SARS-CoV-2 (the virus for COVID-19) and Helicobacter pylori. H. pylori infection is one of the most common infections globally. During H. pylori infection, EVs can carry H. pylori components, such as lipopolysaccharide, cytotoxin-associated gene A, or vacuolating cytotoxin A, and transfer these substances into endothelial cells, triggering inflammatory responses and endothelial dysfunction. This review is to illustrate the important role of EVs in the pathogenesis of infectious diseases, and the development of endothelial dysfunction in infectious diseases especially H. pylori infection, and to discuss the potential mechanisms and clinical implications.

The Interplay between Helicobacter pylori and Gut Microbiota in Non-Gastrointestinal Disorders: A Special Focus on Atherosclerosis

The discovery of Helicobacter pylori (H. pylori) in the early 1980s by Nobel Prize winners in medicine Robin Warren and Barry Marshall led to a revolution in physiopathology and consequently in the treatment of peptic ulcer disease. Subsequently, H. pylori has also been linked to non-gastrointestinal diseases, such as autoimmune thrombocytopenia, acne rosacea, and Raynaud's syndrome. In addition, several studies have shown an association with cardiovascular disease and atherosclerosis. Our narrative review aims to investigate the connection between H. pylori infection, gut microbiota, and extra-gastric diseases, with a particular emphasis on atherosclerosis. We conducted an extensive search on PubMed, Google Scholar, and Scopus, using the keywords "H. pylori", "dysbiosis", "microbiota", "atherosclerosis", "cardiovascular disease" in the last ten years. Atherosclerosis is a complex condition in which the arteries thicken or harden due to plaque deposits in the inner lining of an artery and is associated with several cardiovascular diseases. Recent research has highlighted the role of the microbiota in the pathogenesis of this group of diseases. H. pylori is able to both directly influence the onset of atherosclerosis and negatively modulate the microbiota. H. pylori is an important factor in promoting atherosclerosis. Progress is being made in understanding the underlying mechanisms, which could open the way to interesting new therapeutic perspectives.

Non-Canonical Inflammasome Pathway: The Role of Cell Death and Inflammation in Ehrlichiosis

Activating inflammatory caspases and releasing pro-inflammatory mediators are two essential functions of inflammasomes which are triggered in response to pathogen-associated molecular patterns (PAMPs) or danger-associated molecular patterns (DAMPs). The canonical inflammasome pathway involves the activation of inflammasome and its downstream pathway via the adaptor ASC protein, which causes caspase 1 activation and, eventually, the cleavage of pro-IL-1b and pro-IL-18. The non-canonical inflammasome pathway is induced upon detecting cytosolic lipopolysaccharide (LPS) by NLRP3 inflammasome in Gram-negative bacteria. The activation of NLRP3 triggers the cleavage of murine caspase 11 (human caspase 4 or caspase 5), which results in the formation of pores (via gasdermin) to cause pyroptosis. Ehrlichia is an obligately intracellular bacterium which is responsible for causing human monocytic ehrlichiosis (HME), a potentially lethal disease similar to toxic shock syndrome and septic shock syndrome. Several studies have indicated that canonical and non-canonical inflammasome activation is a crucial pathogenic mechanism that induces dysregulated inflammation and host cellular death in the pathophysiology of HME. Mechanistically, the activation of canonical and non-canonical inflammasome pathways affected by virulent Ehrlichia infection is due to a block in autophagy. This review aims to explore the significance of non-canonical inflammasomes in ehrlichiosis, and how the pathways involving caspases (with the exception of caspase 1) contribute to the pathophysiology of severe and fatal ehrlichiosis. Improving our understanding of the non-canonical inflammatory pathway that cause cell death and inflammation in ehrlichiosis will help the advancement of innovative therapeutic, preventative, and diagnostic approaches to the treatment of ehrlichiosis.

Helicobacter pylori infection and risk of cardiovascular disease

BACKGROUND

Whether Helicobacter pylori (H. pylori) infection is associated with an increased risk of cardiovascular disease (CVD) remains controversial. This study aimed to investigate the association between H. pylori infection and the risk of CVD.

METHODS

Potentially related studies were searched in the electronic databases, including PubMed, EMBASE and Cochrane Library, from inception to 31 August 2022. Observational cohort studies that reported the multivariable-adjusted relative risks (RRs) for composite CVD, CHD, stroke, or all-cause mortality associated with H. pylori infection were included in the meta-analysis, using random-effects models.

RESULTS

Forty-one cohort studies with 230,288 participants were included. After a median follow-up duration of 6.3 years, H. pylori infection was associated with a mildly increased risk of composite CVD (RR 1.10, 95% CI 1.03, 1.18) and coronary heart disease (RR 1.10, 95% CI 1.02, 1.18) compared with those without H. pylori infection. No significant association was observed between H. pylori infection and risk of stroke (RR 1.08, 95% CI 0.94, 1.23) or all-cause mortality (RR 1.02, 95% CI 0.90, 1.16). Compared with cytotoxin-associated gene-A (CagA) negative H. pylori infection, the risk of CVD was significantly increased in patients with CagA positive H. pylori infection (RR 1.58, 95% CI 1.03, 2.41).

CONCLUSIONS

Helicobacter pylori infection is associated with a mildly increased risk of CVD. It may be of great public health and clinical significance to screen H. pylori infection in patients with a high risk of CVD.

Characteristics of different types of Helicobacter pylori: New evidence from non-amplified white light endoscopy

BACKGROUND

Different types of Helicobacter pylori (H. pylori) were analyzed to determine their infection characteristics using serology, pathology, and non-magnification white light endoscopy combined with the Kimura-Takemoto classification, and the regular arrangement of collecting venules (RAC) as well.

MATERIALS AND METHODS

A retrospective analysis of 685 inpatients who have completed the 14C-urea breath test, the H. pylori antibody typing classification, the serum gastric function tests (PGI/PGII/G-17), the endoscope detection, and the pathological examinations.

RESULTS

The levels of PGI, PGII, and G-17 were in descending order from the type I H. pylori infection group to the type II H. pylori infection group than the control group (F = 14.31; 26.23; 9.12, P < 0.01). Using the Kimura-Takemoto classification, there were significant differences among the three groups of different degrees of atrophy (χ 2 =29.81; 482.78; 292.5, P< 0.01). Based on the characteristics of RAC, the H. pylori infection rates were in descending order from the type I H. pylori infection group to the type II H. pylori infection group than the control group (χ 2 = 200.39; 174.72; 143.51, P < 0.01). The type I H. pylori infection group had higher grades than those of the type II H. pylori infection group in the OLGA and OLGIM staging systems, while the differences are statistically significant only in the OLGA staging system (χ 2 =10.63, P < 0.05).

CONCLUSION

With the aid of non-amplified white light endoscopy, we found new evidence of type I H. pylori infection accelerating the progression of gastric mucosal atrophy through the degree of atrophy and the range of infection, whereas type II H. pylori infection has a low ability of migration and atrophy progression. Individual virulence factor-based eradication therapy may be a better choice in future.

Interactions between PCSK9 and NLRP3 inflammasome signaling in atherosclerosis

Atherosclerosis is an early pathological basis of numerous cardiovascular events that result in death or disability. Recent studies have described PCSK9 as a novel target for the treatment of atherosclerosis; PCSK9 is capable of degrading LDLR on the surface of hepatocytes through the regulation of lipid metabolism, and it can function as a novel inflammatory modulator in atherosclerosis. Inflammasomes are important intracellular multiprotein complexes that promote the inflammatory response in atherosclerosis. Among inflammasomes, the NLRP3 inflammasome is particularly notable because of its important role in the development of atherosclerotic disease. After activation, NLRP3 forms a complex with ASC and pro-caspase-1, converting pro-caspase-1 into activated caspase-1, which may trigger the release of IL-1β and IL-18 and contribute to the inflammatory response. Several recent studies have indicated that there may be interactions between PCSK9 and the NLRP3 inflammasome, which may contribute to the inflammatory response that drives atherosclerosis development and progression. On the one hand, the NLRP3 inflammasome plays an important role via IL-1β in regulating PCSK9 secretion. On the other hand, PCSK9 regulates caspase-1-dependent pyroptosis by initiating mtDNA damage and activating NLRP3 inflammasome signaling. This paper reviews the mechanisms underlying PCSK9 and NLRP3 inflammasome activation in the context of atherosclerosis. Furthermore, we describe the current understanding of the specific molecular mechanism underlying the interactions between PCSK9 and NLRP3 inflammasome signaling as well as the drug repositioning events that influence vascular cells and exert beneficial antiatherosclerotic effects. This review may provide a new therapeutic direction for the effective prevention and treatment of atherosclerosis in the clinic.

Integrated pyroptosis measurement and metabolomics to elucidate the effect and mechanism of tangzhiqing on atherosclerosis

Tangzhiqing formula (TZQ) is a traditional Chinese medicine prescribed to treat glucose and lipid metabolism disorders. A significant effect of TZQ on diabetes and hyperlipidemia has been demonstrated, but its effect on atherosclerosis (AS) remains unknown. This study combines pyroptosis with metabolomics to elucidate the effect and mechanism of TZQ on AS. A model of AS was developed using ApoE^−/− mice fed a high-fat diet for 8 weeks. After 6 weeks of atorvastatin (Ator) or TZQ treatment, aortic lumen diameter, aortic lesion size, serum lipid profile, cytokines, and Nod-like receptor protein 3 (NLRP3) inflammasome-mediated pyroptosis were analyzed. Serum metabolomics profiles were obtained to examine the effect of TZQ on AS and the correlation between pyroptosis and metabolites was further analyzed. As a result, TZQ significantly reduced the diameter of the common carotid artery during diastole and the blood flow velocity in the aorta during systole; reduced blood lipid levels, arterial vascular plaques, and the release of inflammatory cytokines; and inhibited the NLRP3 inflammasome-mediated pyroptosis. According to metabolomics profiling, TZQ is engaged in the treatment of AS via altering arachidonic acid metabolism, glycerophospholipid metabolism, steroid hormone production, and unsaturated fatty acid biosynthesis. The cytochrome P450 enzyme family and cyclooxygenase 2 (COX-2) are two major metabolic enzymes associated with pyroptosis.

Helicobacter pylori Infection—A Risk Factor for Irritable Bowel Syndrome? An Updated Systematic Review and Meta-Analysis

Nowadays, the relationship between Helicobacter pylori infection (HPI) and irritable bowel syndrome (IBS) remains controversial. Objective: The aim of this study is to investigate the relationship between HPI and IBS through a systematic review and meta-analysis based on the current evidence. Methods: We performed a systematic literature search in electronic databases (PubMed, EMBASE, and the Cochrane library) by computer to identify all reports published before 8 August 2021. The odds ratio (OR) and confidence interval (CI) were calculated to evaluate the association between HPI and IBS. Subgroup analyses were conducted for further assessment and exploration of heterogeneity sources. In addition, we assessed publication bias through funnel plots, Egger’s test, and Begg’s test. Finally, we conducted a sensitivity analysis to evaluate the robustness of the results. Results: Thirteen studies with 13,173 participants were included in the meta-analysis. The pooled OR of the association between HPI and IBS was 1.03 (95% CI [0.80,1.31]; p = 0.84). The adjusted OR of the association between HPI and IBS after excluding the studies with confounding factors defined by our team was 1.29 (95% CI [1.03,1.62]; p = 0.03). We found a positive association between HPI and IBS-D (diarrhea subtype) (OR: 1.54; 95% CI [1.22,1.95]; p = 0.0003). The OR of the relationship between cytotoxin-associated gene A (Cag A) positive HPI and IBS was 4.3 (95% CI [0.51,36.17]; p = 0.18). Conclusions: The likelihood of HPI in IBS patients is relatively higher than that of non-IBS participants but not statistically significant, implying that HPI is not significantly associated with IBS, albeit we may underestimate this association. Moreover, we found a positive association between HPI and IBS-D. We also observed an increased likelihood of Cag-A positive HPI in IBS patients than that of non-IBS participants but not statistically significant.

Transgenically expressed Helicobacter pylori CagA in vascular endothelial cells accelerates arteriosclerosis in mice

Arteriosclerosis is intimately associated with cardiovascular diseases. Recently, evidence accumulated that infection with Helicobacter pylori cagA-positive strains, which causes gastritis, peptic ulceration, and gastric cancer, is also involved in the development of arteriosclerosis. The cagA-encoded CagA protein is injected into the attached gastric epithelial cells via the type IV secretion system. We previously showed that CagA-containing exosomes are secreted from CagA-injected gastric epithelial cells and enter the systemic blood circulation, delivering CagA into endothelial cells. In the present study, transgenic mice were established in which CagA was selectively expressed in endothelial cells by Cre-loxP system. Treatment of the mice with a high-fat diet revealed that atherogenic lesions were induced in mice expressing CagA in vascular endothelial cells but not in CagA-nonexpressing mice. To investigate the effects of CagA on endothelial cells, we also established conditional CagA-expressing human vascular endothelial cells using the Tet-on system. Upon induction of CagA, a dramatic change in cell morphology was observed that was concomitantly associated with the loss of the endothelial cells to form tube-like structures. Induction of CagA also activated the pro-inflammatory transcription factor STAT3. Thus, exosome-delivered CagA deregulates signals that activates STAT3 in endothelial cells, which accelerates inflammation that promotes arteriosclerosis/atherosclerosis.