Prevalence estimates of Helicobacter species infection in pancreatic and biliary tract cancers

A study of the association between Helicobacter pylori infection type and pancreatic cancer risk: A systematic review and meta‑analysis

Pancreatic cancer is a highly invasive malignant tumor with a complex pathogenesis that makes early diagnosis challenging. The potential association between Helicobacter pylori infection and pancreatic cancer risk has been noted; however, the available results are still highly divergent. The aim of the present study was to systematically evaluate the association between different types of H. pylori infection and pancreatic cancer risk as well as to explore the possible causes. A systematic search was conducted using the PubMed, Embase and Cochrane Library databases up to August 2023. The literature quality was evaluated using the Newcastle-Ottawa Scale. All studies that met the criteria were included in the overall meta-analysis to calculate the odds ratios (ORs) and corresponding 95% confidence intervals (CIs). In addition, subgroup analyses were performed based on factors such as diagnostic criteria for H. pylori infection, study region, type of study design and CagA status. The effect of publication bias on the quantitative synthesis results was assessed using the trim-and-fill analysis, and sensitivity analyses were used to verify the robustness of the quantitative synthesis results. A total of 17 studies involving 67,910 participants, including 64,372 controls and 3,538 patients with pancreatic cancer, were included in the present study. The overall analysis showed that no significant association was observed between H. pylori infection and pancreatic cancer risk (OR, 1.15; 95% CI, 0.93-1.41). Further subgroup analyses, which did not consider the effects of study quality, diagnostic criteria, geographical distribution and the type of study design, did not produce new findings that contradicted the results of the overall analysis. CagA+ H. pylori infection did not significantly affect the risk of pancreatic cancer (OR, 0.95; 95% CI, 0.78-1.16), whereas CagA- H. pylori infection may be a possible risk factor for pancreatic cancer (OR, 1.24; 95% CI, 1.004-1.541). The H. pylori infection did not significantly increase the risk of pancreatic cancer. However, it is noteworthy that CagA- H. pylori infection could be a potential factor that elevated the risk of pancreatic cancer.

Genome and pathogenicity analysis of Helicobacter mastomyrinus isolated from mice

The increasing attention given to the potential risk offered by enterohepatic Helicobacter species to the well-being of human beings and animals is of significant importance. Helicobacter mastomyrinus (H. mastomyrinus), a bacterium predominantly associated with rodents, has been implicated in liver and intestinal pathologies. Here, a strain of H. mastomyrinus, designated as Hm-17 (GenBank: CP145316.1), was isolated from asymptomatic C57BL/6 mice. Subsequently, an in-depth and comprehensive investigation was undertaken, which included genome sequencing analysis, micro-biochemical identification, evaluation of growth characteristic, cytotoxicity assessment, and testing of animal pathogenicity. The analysis of 16 S rRNA reveals a close phylogenetic relationship between H. mastomyrinus and H. canadensis. However, core-pan genome analysis and an evaluation of pathogenic factors indicates a more robust association between H. mastomyrinus and H. hepaticus. Cytotoxicity analysis revealed that Hm-17 exhibits robust cytolethal distending toxin (CDT) activity, inducing pronounced cellular swelling and death. Furthermore, Hm-17 infection in BALB/c mice results in rapid and characteristic focal necrotic hepatitis. Genome sequencing and pathogenicity analysis indicate that H. mastomyrinus isolates from asymptomatic mice possess significant pathogenic potential. These findings underscore the need for further investigation into the epidemiology and mechanisms of pathogenesis associated with this organism.

Effects of pomegranate exocarp extract on H. pylori-induced pancreatic EMT: Molecular mechanisms and therapeutic potential

BACKGROUND

Previous studies have linked Helicobacter pylori infection with pancreatic diseases, including cancer.

PURPOSE

To explore the influence of pomegranate exocarp extract (PEE) on epithelial-mesenchymal transition (EMT) in H. pylori-induced pancreatic rat tissue and to uncover the underlying molecular mechanisms.

STUDY DESIGN

Twenty-eight rats were divided into six groups: group 1 (negative control), group 2 (H. pylori-infected), group 3 (infected + PEE pretreatment), group 4 (infected + PEE treatment), group 5 (infected + metronidazole treatment), and group 6 (infected + metronidazole/PEE co-treatment).

METHODS AND RESULTS

This study aimed to assess the effectiveness of pomegranate exocarp extract (PEE) in treating Helicobacter pylori infection and its associated pancreatic tissue changes in Wistar rats. The study involved Forty-eight male rats divided into six groups: H. pylori-infected control, PEE-preventive, PEE treatment, metronidazole treatment, PEE combined with metronidazole treatment, and negative control. The results showed a significant reduction in H. pylori concentration in the antrum in the PEE-treated groups (27.08 %) compared to that in the positive control group (p < 0.05). The group receiving the combined treatment exhibited the highest reduction (55.8 %) in H. pylori concentration (p < 0.005), with no significant difference observed between the PEE-preventive and metronidazole-treated groups. The ELISA results showed that the groups treated with PEE, PEE-preventive, and PEE combined with metronidazole experienced a significant increase in pancreatic E-cadherin levels by 47.7 %, 73.8 %, and 118.06 % respectively, and a substantial decrease in vimentin levels by 16.6 %, 31.6 %, and 43.5 % respectively, compared to the positive control group (p < 0.05). The results of the RT-qPCR analysis showed that the PEE treatment group, as well as the PEE preventive and PEE combined with metronidazole treatment groups, displayed significant downregulation of vimentin, sirtuin1, and lncRNA MALAT-1, and upregulation of E-cadherin compared to the positive control group. However, there was no significant difference between the PEE-preventive and metronidazole-treated groups (p < 0.05). Histopathological analysis showed considerable improvement in pancreatic tissue morphology in the PEE-treated groups. The inflammation score was significantly lower in these groups (p < 0.05), and the combined treatment group exhibited minimal signs of metaplasia and mononuclear cell infiltration. A computational study identified 54 human target genes of bioactive compounds in PEE. These findings shed light on the crucial interactions and pathways in treating pancreatic tumors. Additionally, GO enrichment and KEGG pathway analyses revealed significant pathways, such as the MAPK signaling and RTK pathway, enriched with genes targeted by PEE. Furthermore, evaluation of drug-likeness and ADME properties indicated that ellagic acid possesses drug-like properties and has a high potential for oral absorption. In conclusion, PEE has shown significant therapeutic potential in reducing H. pylori load and improving pancreatic tissue health while influencing key molecular markers and pathways associated with pancreatic tumors.

The microbial composition of pancreatic ductal adenocarcinoma: a systematic review of 16S rRNA gene sequencing

BACKGROUND

Pancreatic cancer, specifically pancreatic ductal adenocarcinoma (PDAC), continues to pose a significant clinical and scientific challenge. The most significant finding of recent years is that PDAC tumours harbour their specific microbiome, which differs amongst tumour entities and is distinct from healthy tissue. This review aims to evaluate and summarise all PDAC studies that have used the next-generation technique, 16S rRNA gene amplicon sequencing within each bodily compartment. As well as establishing a causal relationship between PDAC and the microbiome.

MATERIALS AND METHODS

This systematic review was carried out according to the Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) guidelines. A comprehensive search strategy was designed, and 1727 studies were analysed.

RESULTS

In total, 38 studies were selected for qualitative analysis and summarised significant PDAC bacterial signatures. Despite the growing amount of data provided, we are not able to state a universal 16S rRNA gene microbial signature that can be used for PDAC screening. This is most certainly due to the heterogeneity of the presentation of results, lack of available datasets, and the intrinsic selection bias between studies.

CONCLUSION

Several key studies have begun to shed light on causality and the influence the microbiome constituents and their produced metabolites could play in tumorigenesis and influencing outcomes. The challenge in this field is to shape the available microbial data into targetable signatures. Making sequenced data readily available is critical, coupled with the coordinated standardisation of data and the need for consensus guidelines in studies investigating the microbiome in PDAC.

Use of Deep-Amplicon Sequencing (DAS), Real-Time PCR and In Situ Hybridization to Detect H. pylori and Other Pathogenic Helicobacter Species in Feces from Children

BACKGROUND

Detecting Helicobacter pylori in fecal samples is easier and more comfortable than invasive techniques, especially in children. Thus, the objective of the present work was to detect H. pylori in feces from children by molecular methods as an alternative for diagnostic and epidemiological studies.

METHODS

Forty-five fecal samples were taken from pediatric patients who presented symptoms compatible with H. pylori infection. HpSA test, culture, real-time quantitative PCR (qPCR), fluorescence in situ hybridization (FISH), direct viable count associated with FISH (DVC-FISH), and Illumina-based deep-amplicon sequencing (DAS) were applied.

RESULTS

No H. pylori colonies were isolated from the samples. qPCR analysis detected H. pylori in the feces of 24.4% of the patients. In comparison, DVC-FISH analysis showed the presence of viable H. pylori cells in 53.3% of the samples, 37% of which carried 23S rRNA mutations that confer resistance to clarithromycin. After DAS, H. pylori-specific 16S rDNA sequences were detected in 26 samples. In addition, DNA from H. hepaticus was identified in 10 samples, and H. pullorum DNA was detected in one sample.

CONCLUSION

The results of this study show the presence of H. pylori, H. hepaticus, and H. pullorum in children's stools, demonstrating the coexistence of more than one Helicobacter species in the same patient. The DVC-FISH method showed the presence of viable, potentially infective H. pylori cells in a high percentage of the children's stools. These results support the idea that fecal-oral transmission is probably a common route for H. pylori and suggest possible fecal-oral transmission of other pathogenic Helicobacter species.

Helicobacter hepaticus and Helicobacter bilis in liver and biliary cancers from ATBC and PLCO

BACKGROUND

Helicobacter species (spp.) have been detected in human bile and hepatobiliary tissue Helicobacter spp. promote gallstone formation and hepatobiliary tumors in laboratory studies, though it remains unclear whether Helicobacter spp. contribute to these cancers in humans. We used a multiplex panel to assess whether seropositivity to Helicobacter (H.) hepaticus or H. bilis proteins was associated with the development of hepatobiliary cancers in the Finnish Alpha-Tocopherol, Beta-Carotene Cancer Prevention (ATBC) Study, and US-based Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial (PLCO).

METHODS

We included 62 biliary and 121 liver cancers, and 190 age-matched controls from ATBC and 74 biliary and 105 liver cancers, and 364 age- and sex-matched controls from PLCO. Seropositivity to 14 H. hepaticus and H. bilis antigens was measured using a multiplex assay. Odds ratios (ORs) and 95% confidence intervals (CIs) were adjusted for major hepatobiliary cancer risk factors and Helicobacter pylori serostatus.

RESULTS

Seropositivity to the H. bilis antigen, P167D, was associated with more than a twofold higher risk of liver cancer (OR: 2.38; 95% CI: 1.06, 5.36) and seropositivity to the H. hepaticus antigens HH0407 or HH1201, or H. bilis antigen, HRAG 01470 were associated with higher risk of biliary cancer (OR: 5.01; 95% CI: 1.53, 16.40; OR: 2.40; 95% CI: 1.00, 5.76; OR: 3.27; 95% CI: 1.14, 9.34, respectively) within PLCO. No associations for any of the H. hepaticus or H. bilis antigens were noted for liver or biliary cancers within ATBC.

CONCLUSIONS

Further investigations in cohort studies should examine the role of Helicobacter spp. in the etiology of liver and biliary cancers.

Helicobacter pylori extract induces purified neutrophils to produce reactive oxygen species only in the presence of plasma

H. pylori is a bacterial pathogen infecting over half of the world's population and induces several gastric and extra-gastric diseases through its various virulence factors, especially cagA. These factors may be released from the bacteria during interactions with host immune cells. Neutrophils play key roles in innate immunity, and their activity is regulated by plasma factors, which can alter how these cells may interact with pathogens. The aim of the present study was to determine whether purified neutrophils could produce reactive oxygen species (ROS), one of the key functions of their anti-microbial functions, in response to extracts of cagA+ and cagA- H. pylori. Extracts from either cagA+ or cagA- H. pylori were co-cultured with human neutrophils in the presence or absence of plasma, and the neutrophil ROS production was measured. In the absence of plasma, extracts from cagA+ and cagA- H. pylori did not induce neutrophil ROS production, whereas in the presence of plasma, extracts from both cagA+ and cagA- H. pylori-induced ROS production. Furthermore, when peripheral blood mononuclear cells (PBMCs) were added to the purified neutrophils in the absence of plasma, there was no neutrophil ROS production after challenging with extracts from either cagA+ or cagA- H. pylori. Thus, it is suggested that plasma contains immunological components that change the responsiveness of neutrophils, such that when neutrophils encounter the bacterial antigens in H. pylori extracts, they become activated and produce ROS. This study also revealed a potential novel immunopathogenic pathway by which cagA activation of neutrophils contributed to inflammatory damage.

Helicobacter hepaticus promotes liver fibrosis through oxidative stress induced by hydrogenase in BALB/c mice

BACKGROUND

It has been documented that Helicobacter hepaticus produces a nickel-containing hydrogen-oxidizing hydrogenase enzyme, which is necessary for hydrogen-supported amino acid uptake. Although H. hepaticus infection has been shown to promote liver inflammation and fibrosis in BALB/c mice, the impact of hydrogenase on the progression of liver fibrosis induced by H. hepaticus has not been explored.

MATERIALS AND METHODS

BALB/c mice were inoculated with hydrogenase mutant (ΔHyaB) or wild type (WT) H. hepaticus 3B1 for 12 and 24 weeks. H. hepaticus colonization, hepatic histopathology, serum biochemistry, expression of inflammatory cytokines, and oxidative stress signaling pathways were detected.

RESULTS

We found that ΔHyaB had no influence on the colonization of H. hepaticus in the liver of mice at 12 and 24 weeks post infection (WPI). However, mice infected by ΔHyaB strains developed significantly alleviated liver inflammation and fibrosis compared with WT infection. Moreover, ΔHyaB infection remarkably increased the expression of hepatic GSH, SOD, and GSH-Px, and decreased the liver levels of MDA, ALT, and AST compared to WT H. hepaticus infected group from 12 to 24 WPI. Furthermore, mRNA levels of Il-6, Tnf-α, iNos, Hmox-1, and α-SMA were significantly decreased with an increase of Nfe2l2 in the liver of mice infected by ΔHyaB strains. In addition, ΔHyaB H. hepaticus restored the activation of the Nrf2/HO-1 signaling pathway, which is inhibited by H. hepaticus infection.

CONCLUSIONS

These data demonstrated that H. hepaticus hydrogenase promoted liver inflammation and fibrosis development mediated by oxidative stress in male BALB/c mice.

Helicobacter Species and Hepato-Biliary Tract Malignancies: A Systematic Review and Meta-Analysis

Helicobacter species may cause chronic inflammation of the biliary tract, but its relationship with cancer is controversial. We performed a systematic review and meta-analysis to evaluate the association between Helicobacter species and hepatobiliary tract malignancies. Twenty-six studies (4083 patients) were included in qualitative synthesis, and 18 studies (n = 1895 qualified for meta-analysis. All studies were at high-intermediate risk of bias. Most studies combined several direct microbiological methods, mostly PCR (23 studies), culture (8 studies), and/or CLOtest (5 studies). Different specimens alone or in combination were investigated, most frequently bile (16 studies), serum (7 studies), liver/biliary tissue (8 studies), and gastric tissue (3 studies). Patients with Helicobacter species infection had an increased risk of hepatobiliary tract malignancies (OR = 3.61 [95% CI 2.18-6.00]; p < 0.0001), with high heterogeneity in the analysis (I2 = 61%; p = 0.0003). This effect was consistent when Helicobacter was assessed in bile (OR = 3.57 [95% CI 1.73-7.39]; p = 0.0006), gastric tissue (OR = 42.63 [95% CI 5.25-346.24]; p = 0.0004), liver/biliary tissue (OR = 4.92 [95% CI 1.90-12.76]; p = 0.001) and serum (OR = 1.38 [95% CI 1.00-1.90]; p = 0.05). Heterogeneity was reduced in these sub-analyses (I2 = 0-27%; p = ns), except for liver/biliary tissue (I2 = 57%; p = 0.02). In conclusion, based on low-certainty data, Helicobacter species chronic infection is associated with a tripled risk of hepatobiliary tract malignancy. Prospective studies are required to delineate public health interventions.

Is Helicobacter pylori infection associated with pancreatic cancer? A systematic review and meta-analysis of observational studies

Background and Objectives

Recent observational studies have investigated the association between Helicobacter pylori (H. pylori) infection and pancreatic cancer with conflicting data. Therefore, we conducted a systematic review and meta-analysis to assess the potential association.

Design

This is a systematic review and meta-analysis.

Methods

We searched three databases (PubMed, Embase, and Web of Science) from inception to 30 August 2022. The summary results as odds ratio (OR) or hazard ratio (HR) with 95% confidence interval (CI) were pooled by generic inverse variance method based on random-effects model.

Results

A total of 20 observational studies involving 67,718 participants were included in the meta-analysis. Meta-analysis of data from 12 case-control studies and 5 nested case-control studies showed that there was no significant association between H. pylori infection and the risk of pancreatic cancer (OR = 1.20, 95% CI = 0.95-1.51, p = 0.13). Similarly, we also did not find significant association between cytotoxin-associated gene A (CagA) positive strains, CagA negative strains, vacuolating cytotoxin gene A (VacA) positive strains H. pylori infection, and the risk of pancreatic cancer. Meta-analysis of data from three cohort studies showed that H. pylori infection was not significantly associated with an increased risk of incident pancreatic cancer (HR = 1.26, 95% CI = 0.65-2.42, p = 0.50).

Conclusion

We found insufficient evidence to support the proposed association between H. pylori infection and increased risk of pancreatic cancer. To better understand any association, future evidence from large, well-designed, high-quality prospective cohort studies that accounts for diverse ethnic populations, certain H. pylori strains, and confounding factors would be useful to settle this controversy.

Associations between cigarette smoking and biliary tract cancer by anatomic subsite and sex: a prospective cohort study in Japan

PURPOSE

Biliary tract cancer (BTC) has not been considered a tobacco-related cancer, largely because of inconclusive results from epidemiological studies. We herein evaluate the association between cigarette smoking and risk of death from BTC by anatomic subsite and sex using data from a large, prospective cohort study in Japan.

METHODS

The present study included 97,030 Japanese individuals who were enrolled in 1988-1990 and followed until 31 December 2009. Cox proportional hazards regression models were used to estimate relative risks (RRs) and 95% confidence intervals (CIs) for the association of BTC with cigarette smoking, including smoking status, number of cigarettes smoked per day, and pack-years of smoking.

RESULTS

During a mean follow-up of 16.2 years, we documented 484 deaths (187 from gallbladder cancers and 297 from cancers of other and unspecified biliary tract parts). After adjustment for sex, age, body mass index, alcohol consumption, and history of gallstones, current smokers had a higher risk of death due to BTC (RR = 1.35, 95% CI = 1.01-1.79) than never smokers. In the analyses by anatomic subsite, current smoking was associated with an increased risk of death from gallbladder cancer (RR = 1.89 95% CI = 1.19-3.02), whereas no evidence of an association was noted for cancers of other and unspecified biliary tract parts (RR = 1.10, 95% CI = 0.77-1.58). Moreover, mortality risk increased with an increasing number of cigarettes smoked per day and pack-years of smoking, particularly for gallbladder cancer in men.

CONCLUSION

Cigarette smoking is associated with an increased risk of death from BTC, particularly gallbladder cancer, in Japanese men.

Helicobacter bilis Contributes to the Occurrence of Inflammatory Bowel Disease by Inducing Host Immune Disorders

Gut microbiota coevolve with humans to achieve a symbiotic relationship, which ultimately leads to physiological homeostasis. A variety of diseases can occur once this balance is disrupted. Helicobacter bilis (H. bilis) is an opportunistic pathogen in humans, triggering multiple diseases, including inflammatory bowel disease (IBD). IBD is a chronic immunologically mediated inflammation of the human gastrointestinal tract, and its occurrence is closely related to the gut microbiota. Several studies have demonstrated that H. bilis colonization is associated with IBD, and its mechanism is related to host immunity. However, few studies have investigated these mechanisms of action. Therefore, this article is aimed at reviewing these studies and summarizing the mechanisms of H. bilis-induced IBD from two perspectives: adaptive immunity and innate immunity. Furthermore, this study provides a preliminary discussion on treating H. bilis-related IBD. In addition, we also demonstrated that H. bilis played an important role in promoting the carcinogenesis of IBD and discussed its mechanism.

Persistent advanced periductal fibrosis is associated with cagA-positive Helicobacter pylori infection in post-praziquantel treatment of opisthorchiasis

BACKGROUND

Liver fluke infection caused by Opisthorchis viverrini is associated with several hepatobiliary diseases including advanced periductal fibrosis (APF) and cholangiocarcinoma. Recently, we demonstrated a persistent APF in over one-third of opisthorchiasis patients after worm removal by praziquantel (PZQ) treatment. However, the underlying mechanism(s) of this phenomena is unclear. Given a co-infection with Helicobacter pylori (H. pylori) especially cagA-positive strain enhances APF, we hypothesized that H. pylori with CagA virulent factor contributes to persistent APF.

MATERIALS AND METHODS

Seventy-five opisthorchiasis patients who underwent ultrasonography and treatment with PZQ were recruited in the 2-year follow-up study. Helicobacter and its cagA in the feces were examined by conventional and qPCR. Correlations between prevalence or bacterial loads of Helicobacter spp., H. pylori, and cagA-positive H. pylori before and after PZQ treatment were analyzed among resolved, slowly resolved, relapsed, and persistent APF groups.

RESULTS

Overall, prevalence of Helicobacter spp., H. pylori, and cagA-positive H. pylori declined after PZQ treatment. However, only the prevalence and bacterial loads of cagA-positive H. pylori detected at 2-year post-treatment were significantly lower than those before treatment (p < .05). In addition, both prevalence and bacterial loads of cagA-positive H. pylori were significantly lower in the resolved APF group after PZQ treatment, while there were no significant changes in the slowly resolved, relapsed, and persistent APF groups. Among the APF subgroups, cagA-positive H. pylori prevalence in both relapsed and persistent APF groups were significantly higher than the resolved APF group.

CONCLUSION

The results support our hypothesis that H. pylori, especially cagA-positive strain, contributes to the relapsed and persistent APF. A supplementary antibiotic treatment for H. pylori to reduce persistent APF and eventually CCA is warranted.

Helicobacter bilis infection induces oxidative stress in and enhances the proliferation of human cholangiocytes

BACKGROUND

Helicobacter bilis, an enterohepatic Helicobacter species, represents a carcinogenic risk factor for cholangiocytes owing to the prevalence of infections in patients with biliary tract cancer, cholecystitis, and pancreaticobiliary maljunction. However, the effect of H. bilis infection on cholangiocytes and the process and mechanism of carcinogenesis are not known. We aimed to determine the effects of H. bilis on cholangiocytes, focusing on inflammation and oxidative stress.

MATERIALS AND METHODS

Helicobacter bilis and MMNK-1 cells were cocultured for 24 h and inflammatory cytokine secretion was evaluated. Furthermore, MMNK-1 cell proliferation, intracellular reactive oxidant species (ROS) production, and DNA damage caused by ROS were investigated. All factors were compared with and without H. bilis infection.

RESULTS

Interleukin (IL)-6 and IL-8 secretion were significantly increased in MMNK-1 cocultures with H. bilis (IL-6, 24.3 ± 12.2 vs. 271.1 ± 286.4 pg/ml; IL-8, 167.6 ± 78.7 vs. 1085.1 ± 1047.1 pg/ml, p < .05). MMNK-1 proliferation was also significantly higher in H. bilis cocultures (1.05 ± 0.02 vs. 1.00-fold, respectively; p < .05). Coculturing enhanced the production of ROS in MMNK-1 cells depending on the cell concentration of H. bilis (1.0 vs. 1.17 ± 0.06, p < .05); however, DNA injury was not observed in cocultures with H. bilis (5.35 ± 0.87 vs. 6.08 ± 0.55 pg/μl, p = .06).

CONCLUSIONS

Helicobacter bilis infection induced ROS production in and enhanced the proliferation of cholangiocytes.