Helicobacter genus DNA fragments are commonly detectable in bile from patients with extrahepatic biliary diseases and associated with their pathogenesis

Helicobacter pylori and Gastrointestinal Cancers: Recent Advances and Controversies

Helicobacter pylori (H pylori), a gastric bacterium, has been extensively studied for its association with gastritis, peptic ulcers, and gastric cancer. However, recent evidence suggests its potential implications beyond the stomach, linking it to other gastrointestinal malignancies, such as esophageal cancer, liver cancer, pancreatic cancer, gallbladder cancer, and colorectal cancer. In light of the expanding research landscape and the increasing interest in exploring H pylori broader role in gastrointestinal tumorigenesis, this comprehensive review aims to elucidate the relationship between H pylori and gastrointestinal tumors. This review encompasses recent epidemiological studies, research progress, and emerging perspectives, providing a comprehensive assessment of the relationship between H pylori and gastrointestinal tumors. The findings highlight the captivating world of H pylori and its intricate involvement in gastrointestinal malignancies.

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.

Enterohepatic Helicobacter species - clinical importance, host range, and zoonotic potential

The genus Helicobacter defined just over 30 years ago, is a highly diverse and fast-growing group of bacteria that are able to persistently colonize a wide range of animals. The members of this genus are subdivided into two groups with different ecological niches, associated pathologies, and phylogenetic relationships: the gastric Helicobacter (GH) and the enterohepatic Helicobacter (EHH) species. Although GH have been mostly studied, EHH species have become increasingly important as emerging human pathogens and potential zoonotic agents in the last years. This group of bacteria has been associated with the development of several diseases in humans from acute pathologies like gastroenteritis to chronic pathologies that include inflammatory bowel disease, and liver and gallbladder diseases. However, their reservoirs, as well as their routes of transmission, have not been well established yet. Therefore, this review summarizes the current knowledge of taxonomy, epidemiology, and clinical role of the EHH group.

The Relationship between Helicobacter pylori Infection of the Gallbladder and Chronic Cholecystitis and Cholelithiasis: A Systematic Review and Meta-Analysis

Helicobacter pylori (H. pylori) is proved to be the main pathogenic agent of various diseases, including chronic gastritis, gastric ulcer, duodenal ulcer, and gastric cancer. In addition, chronic cholecystitis and cholelithiasis are common worldwide, which are supposed to increase the total mortality of patients. Epidemiologic evidence on the relationship between H. pylori infection of the gallbladder and chronic cholecystitis/cholelithiasis still remains unclear. We conducted a systematic review and meta-analysis of overall studies to investigate the relationship between H. pylori infection of the gallbladder and chronic cholecystitis/cholelithiasis. Two researchers searched PubMed, Embase, and Cochrane Library databases to obtain all related and eligible studies published before July 2020. The pooled odds ratios (ORs) and corresponding 95% confidence intervals (CIs) were calculated by the random-effects model. Subgroup analysis, heterogeneity, publication bias, and sensitivity analysis were also conducted. Twenty studies were included in the meta-analysis, involving 1735 participants and 1197 patients with chronic cholecystitis/cholelithiasis. Helicobacter species infection of the gallbladder was positively correlated with increased risk of chronic cholecystitis and cholelithiasis, especially H. pylori (OR = 3.05; 95% CI, 1.81-5.14; I 2 = 23.5%). Besides, country-based subgroup analysis also showed a positive correlation between the gallbladder H. pylori positivity and chronic cholecystitis/cholelithiasis risk. For Asian and non-Asian country studies, the ORs were 4.30 (95% CI, 1.76-10.50; I 2 = 37.4%) and 2.13 (95% CI, 1.23-3.70; I 2 = 0.0%), respectively. The association was more obvious using the bile sample and urease gene primer. In conclusion, this meta-analysis provided evidence that there is a positive correlation between H. pylori infection in the gallbladder and increased risk of chronic cholecystitis and cholelithiasis.

Association of Chronic Opisthorchis Infestation and Microbiota Alteration on Tumorigenesis in Cholangiocarcinoma

Cholangiocarcinoma (CCA) is a common hepatobiliary cancer in East and Southeast Asia. The data of microbiota contribution in CCA are still unclear. Current available reports have demonstrated that an Opisthorchis viverrini (OV) infection leads to dysbiosis in the bile duct. An increase in the commensal bacteria Helicobacter spp. in OV-infected CCA patients is associated with bile duct inflammation, severity of bile duct fibrosis, and cholangiocyte proliferation. In addition, secondary bile acids, major microbial metabolites, can mediate cholangiocyte inflammation and proliferation in the liver. A range of samples from CCA patients (stool, bile, and tumor) showed different degrees of dysbiosis. The evidence from these samples suggests that OV infection is associated with alterations in microbiota and could potentially have a role in CCA. In this comprehensive review, reports from in vitro, in vivo, and clinical studies that demonstrate possible links between OV infection, microbiota, and CCA pathogenesis are summarized and discussed. Understanding these associations may pave ways for novel potential adjunct intervention in gut microbiota in CCA patients.

Seropositivity for Helicobacter pylori and hepatobiliary cancers in the PLCO study

Helicobacter has been suggested to play a possible role in hepatitis, gallstones, and hepatobiliary tumours. We assessed whether seropositivity to 15 H. pylori proteins was associated with subsequent incidence of 74 biliary tract and 105 liver cancer cases vs. 357 matched controls in the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial (PLCO). Odds ratios and 95% confidence intervals were computed by conditional logistic regression after adjustment for known hepatobiliary cancer risk factors. H. pylori seropositivity was not associated with either biliary tract (1.76, 0.90–3.46) or liver cancer (0.87, 0.46–1.65). CagA seropositivity was associated with both endpoints, although the latter association was not statistically significant (biliary tract: 2.16, 1.03–4.50; liver cancer: 1.96, 0.98–3.93) and neither association was statistically significant after correcting for multiple comparisons. Together, these results suggest possible associations between H. pylori and hepatobiliary cancer and suggest the value of future studies investigating the association.

Trial registration number: NCT00339495.

The Bacterial Microbiota of Gastrointestinal Cancers: Role in Cancer Pathogenesis and Therapeutic Perspectives

The microbiota has an essential role in the pathogenesis of many gastrointestinal diseases including cancer. This effect is mediated through different mechanisms such as damaging DNA, activation of oncogenic pathways, production of carcinogenic metabolites, stimulation of chronic inflammation, and inhibition of antitumor immunity. Recently, the concept of "pharmacomicrobiomics" has emerged as a new field concerned with exploring the interplay between drugs and microbes. Mounting evidence indicates that the microbiota and their metabolites have a major impact on the pharmacodynamics and therapeutic responses toward anticancer drugs including conventional chemotherapy and molecular-targeted therapeutics. In addition, microbiota appears as an attractive target for cancer prevention and treatment. In this review, we discuss the role of bacterial microbiota in the pathogenesis of different cancer types affecting the gastrointestinal tract system. We also scrutinize the evidence regarding the role of microbiota in anticancer drug responses. Further, we discuss the use of probiotics, fecal microbiota transplantation, and antibiotics, either alone or in combination with anticancer drugs for prevention and treatment of gastrointestinal tract cancers.

[Effects of magnetic laser therapy on the gastroduodenal system of patients with chronic acalculous cholecystitis]

BACKGROUND

The inflammatory process in the hepatobiliary system contributes to the development and progression of pathological changes in the adjacent digestive organs. The data available in the literature suggest that laser radiation and magnetic therapy are effective in treating hepatobiliary diseases.

AIM

To evaluate the effects of magnetic laser radiation on the status of gastroduodenal organs in patients with chronic acalculous cholecystitis.

SUBJECTS AND METHODS

Fifty patients with chronic acalculous cholecystitis, mostly women, were followed up; their mean age was 44±8 years (36 to 56 years); the disease duration was 6±1.5 years. The patients were randomized into 2 groups: 1) a comparison group (n=20) and 2) a study group (n=30). Both groups were homogeneous for sex, age, disease duration and severity. The basic treatment included the oral intake of Jermuk mineral water according to the generally accepted scheme, acupuncture, iodine-bromine baths, massage of the collar area, exercise therapy, and, if indicated, therapeutic enemas. During the basic treatment, the patients in the study group were prescribed magnetic laser radiation to the right subcostal area. Results were assessed at 20-22 days after treatment.

RESULTS

The performed treatment resulted in positive clinical changes and improvement in the indicators characterizing the status of gastroduodenal organs.

CONCLUSION

The studies have established that rehabilitation in patients with chronic acalculous cholecystitis along with laser radiation contributes to positive clinical changes and improvement in the status of the gastroduodenal system. There is a tendency to normalize acid-forming function and morphological state of the gastric and duodenal mucosa.

Helicobacter Pylori infection of the gallbladder and the risk of chronic cholecystitis and cholelithiasis: A systematic review and meta-analysis

BACKGROUND

Helicobacter pylori is coexisted with various diseases, including chronic gastritis, ulcer, and gastric cancer. Besides, chronic cholecystitis and cholelithiasis are extremely widespread over the world, which are considered as high health-care cost burdens of digestive diseases. Epidemiologic evidence on Helicobacter pylori infection in gallbladder increasing the risk of biliary diseases has been contradictory.

AIM

Conduct a meta-analysis of overall studies and investigate an association between Helicobacter pylori infection of the gallbladder with chronic cholecystitis/cholelithiasis.

METHODS

We used PubMed, EMBASE, and Cochrane library databases to identify all published studies before August 2017. Pooled odds ratios (OR) and corresponding 95% confidence intervals (CIs) were obtained using the random effects model. Heterogeneity, sensitivity, and stratified analyses were also performed.

RESULTS

Eighteen studies involving 1544 participants and 1061 biliary cases with chronic cholecystitis/cholelithiasis were included. Helicobacter pylori infection of the gallbladder was significantly associated with an increased risk of chronic cholecystitis and cholecystitis (OR = 3.022; 95% CI, 1.897-4.815; I²  = 20.1%). In addition, country-based subgroup analysis also showed a positive association between Helicobacter pylori positivity and chronic cholecystitis/cholelithiasis risk. The ORs (95% CIs) for Asian and non-Asian region studies were 3.75 (1.83-7.71) and 2.25 (1.29-3.89), respectively.

CONCLUSION

This meta-analysis suggests that infection of the gallbladder with Helicobacter pylori is closely related to an increased risk of chronic cholecystitis and cholelithiasis.

Elevated prevalence of Helicobacter species and virulence factors in opisthorchiasis and associated hepatobiliary disease

Recent reports suggest that Opisthorchis viverrini serves as a reservoir of Helicobacter and implicate Helicobacter in pathogenesis of opisthorchiasis-associated cholangiocarcinoma (CCA). Here, 553 age-sex matched cases and controls, 293 and 260 positive and negative for liver fluke O. viverrini eggs, of residents in Northeastern Thailand were investigated for associations among infection with liver fluke, Helicobacter and hepatobiliary fibrosis. The prevalence of H. pylori infection was higher in O. viverrini-infected than uninfected participants. H. pylori bacterial load correlated positively with intensity of O. viverrini infection, and participants with opisthorchiasis exhibited higher frequency of virulent cagA-positive H. pylori than those free of fluke infection. Genotyping of cagA from feces of both infected and uninfected participants revealed that the AB genotype accounted for 78% and Western type 22%. Participants infected with O. viverrini exhibited higher prevalence of typical Western type (EPIYA ABC) and variant AB'C type (EPIYT B) CagA. Multivariate analyses among H. pylori virulence genes and severity of hepatobiliary disease revealed positive correlations between biliary periductal fibrosis during opisthorchiasis and CagA and CagA with CagA multimerization (CM) sequence-positive H. pylori. These findings support the hypothesis that H. pylori contributes to the pathogenesis of chronic opisthorchiasis and specifically to opisthorchiasis-associated CCA.

Microbiota studies in the bile duct strongly suggest a role for Helicobacter pylori in extrahepatic cholangiocarcinoma

Biliary tract cancer or extrahepatic cholangiocarcinoma (ECCA) represents the sixth commonest cause of cancer in the gastrointestinal tract in western countries. We aimed to characterize the microbiota and its predicted associated functions in the biliary tract of ECCA and benign biliary pathology (BBP). Samples were taken from 100 patients with ECCA and 100 patients with BBP by endoscopic cholangio-pancreatography for DNA extraction. Ten patients with ECCA and ten with BBP were selected for microbiota studies using the V4-16S rRNA gene and sequenced in Illumina platform. Microbiota analyses included sample-to-sample distance metrics, ordination/clustering and prediction of functions. Presence of Nesterenkonia sp. and Helicobacter pylori cagA and vacA genes were tested in the 100 ECCA and 100 BBP samples. Phylum Proteobacteria dominated all samples (60.4% average). Ordination multicomponent analyses showed significant microbiota separation between ECCA and BBP (p 0.010). Analyses of 4002 operational taxonomic units with presence variation in at least one category probed a separation of ECCA from BBP. Among these, Nesterenkonia decreased, whereas Methylophilaceae, Fusobacterium, Prevotella, Actinomyces, Novosphingobium and H. pylori increased in ECCA. Predicted associated functions showed increased abundance of H. pylori virulence genes in ECCA. cagA and vacA genes were confirmed by PCR in ECCA and BBP samples. This is the first microbiota report in ECCA and BBP to show significant changes in microbial composition. Bacterial species unusual for human flora were found: Methylophilaceae and Nesterenkonia are reported in hypersaline soils, and Mesorhizobium is a nitrogen-fixing bacterium. Enrichment of virulence genes confirms previous studies suggesting that H. pylori might be associated with ECCA.

Infection with Helicobacter bilis but not Helicobacter hepaticus was Associated with Extrahepatic Cholangiocarcinoma

BACKGROUND AND AIMS

The biliary tract cancer or cholangiocarcinoma (CCA) represents the sixth leading cause of gastrointestinal tumors in the Western world, and mortality varies across the world, with regions such as Chile, Thailand, Japan, and northeastern India presenting the highest rates. CCA may develop in the bile duct, gallbladder, or ampulla of Vater; and risk factors include obesity, parity, genetic background, geographical and environmental factors. Inflammation induced by bacterial infections might play a role in the pathogenesis of CCA. In this work, we investigated whether there is an association between extrahepatic cholangiocarcinoma (ECCA) and infection with S. typhi, H. hepaticus, or H. bilis in a Mexican population.

METHODS

A total of 194 patients were included and divided into 91 patients with benign biliary pathology (controls) and 103 with ECCA (cases). Tumor samples were taken during endoscopic retrograde cholangiopancreatography by biliary brushing, followed by DNA extraction and PCR testing for infections.

RESULTS

We found that 44/103 cases were positive for H. bilis, compared with 19/91 controls (p = 0.002; OR 2.83, 95% CI 1.49-5.32), and when analyzed by sub-site, H. bilis infection was significantly more associated with cancer in the common bile duct (p = 0.0005; OR 3.56, 95% CI 1.77-7.17). In contrast, H. hepaticus infection was not different between cases (17/103) and controls (13/91) (p = 0.82; OR 1.19, 95% CI 0.54-2.60). None of the samples were positive for S. typhi infection.

CONCLUSION

In conclusion, infection with H. bilis but neither H. Hepaticus nor S. typhi was significantly associated with ECCA, particularly with tumors located in the common bile duct.

The Helicobacter pylori L-form: formation and isolation in the human bile cultures in vitro and in the gallbladders of patients with biliary diseases

BACKGROUND

The Helicobacter pylori is considered the important causative agent causing biliary diseases, but the H. pylori can be isolated from very few gallbladder specimens with diseases. We studied the formation of H. pylori L-forms in bile in vitro and isolated the H. pylori L-forms from gallbladder of patients with biliary diseases.

METHODS

We inoculated the H. pylori into the human bile to induce the L-form in vitro. The gallbladder specimens were collected from patients with biliary diseases to isolate the bacterial L-forms by the nonhigh osmotic isolation technique, and the H. pylori L-forms in the L-form isolates were identified by the gene assay for the H. pylori-specific genes 16S rRNA and UreA.

RESULTS

The H. Pylori cannot be isolated from the bile-induced cultures, but the H. pylori L-form can be isolated from the H. pylori-negative bile-induced cultures. The L-form isolates of bile-induced cultures showed a positive reaction of the H. pylori-specific genes by PCR, and the coincidence ratio of the nucleotide sequences between the L-forms and the H. pylori is 99%. The isolation rate of bacteria L-form is 93.2% in the gallbladder specimens with bacteria-negative isolation culture by the nonhigh osmotic isolation technique, and the positive rate of the H. pylori-specific genes in the L-form isolates is 7.1% in the bacterial L-form-positive isolation cultures by the PCR.

CONCLUSIONS

H. pylori can be rapidly induced into the L-form in the human bile; the L-form, as the latent bacteria, can live in the host gallbladder for a long times, and they made the host became a latent carrier of the H. pylori L-form. The H. pylori L-form can be isolated by the nonhigh osmotic isolation technique, and the variant can be identified by the gene assay for the H. pylori-specific genes 16S rRNA and reA.

Association between Helicobacter spp. infections and hepatobiliary malignancies: a review

Hepatobiliary cancers are highly lethal cancers that comprise a spectrum of invasive carcinomas originating in the liver hepatocellular carcinoma, the bile ducts intrahepatic cholangiocarcinoma and extrahepatic cholangiocarcinoma, the gallbladder and the ampulla of Vater (collectively known as biliary tract cancers). These tumors account for approximately 13% of all annual cancer-related deaths worldwide and for 10%-20% of deaths from hepatobiliary malignancies. Cholangiocarcinoma (CCA) is a devastating disease that displays a poor survival rate for which few therapeutic options are available. Population genetics, geographical and environmental factors, cholelithiasis, obesity, parity, and endemic infection with liver flukes have been identified as risk factors that influence the development of biliary tract tumors. Other important factors affecting the carcinogenesis of these tumors include chronic inflammation, obstruction of the bile ducts, and impaired bile flow. It has been suggested that CCA is caused by infection with Helicobacter species, such as Helicobacter bilis and Helicobacter hepaticus, in a manner that is similar to the reported role of Helicobacter pylori in distal gastric cancer. Due to the difficulty in culturing these Helicobacter species, molecular methods, such as polymerase chain reaction and sequencing, or immunologic assays have become the methods of choice for diagnosis. However, clinical studies of benign or malignant biliary tract diseases revealed remarkable variability in the methods and the findings, and the use of uniform and validated techniques is needed.

Helicobacter hepaticus cholesterol-α-glucosyltransferase is essential for establishing colonization in male A/JCr mice

BACKGROUND

Helicobacter pylori cholesterol-α-glucosyltransferase (cgt) is essential for survival of H. pylori in mice. Enterohepatic H. hepaticus, the cause of colonic and hepatocellular carcinoma in susceptible mouse strains, contains an ortholog of the H. pylori cgt. However, the role of cgt in the pathogenesis of H. hepaticus has not been investigated.

MATERIALS AND METHODS

Two cgt-deficient isogenic mutants of wild-type H. hepaticus (WT) 3B1 were generated and used to inoculate male A/JCr mice. Cecal and hepatic colonization levels of the mutants and WT 3B1 as well as select inflammation-associated cytokines were measured by qPCR at 4 months postinoculation.

RESULTS

Both mutants were undetectable in the cecum of any inoculated mice (10 per mutant) but were detected in two livers (one for each mutant); by contrast, 9 and 7 of 10 mice inoculated with WT 3B1 were qPCR positive in the ceca and livers, respectively. The mice inoculated with the mutants developed significantly less severe hepatic inflammation (p < .05) and also produced significantly lower hepatic mRNA levels of proinflammatory cytokines Ifn-γ (p < .01) and Tnf-α (p ≤ .02) as well as anti-inflammatory factors Il10 and Foxp3 compared with the WT 3B1-inoculated mice. Additionally, the WT 3B1-inoculated mice developed significantly higher Th1-associated IgG2a (p < .0001) and Th2-associated IgG1 responses (p < .0001) to H. hepaticus infection than mice dosed with isogenic cgt mutants.

CONCLUSION

Our data indicate that the cholesterol-α-glucosyltransferase is required for establishing colonization of the intestine and liver and therefore plays a critical role in the pathogenesis of H. hepaticus.

Helicobacter species infection may be associated with cholangiocarcinoma: a meta-analysis

OBJECTIVE

Since the discovery of Helicobacter species in human biliary system, the association between Helicobacter species infection and cholangiocarcinoma is under debate. This meta-analysis aims to explore this issue.

METHODS

Literature search was carried out to identify all eligible articles. We performed overall meta-analysis of all included studies and subgroup analysis based on regional distribution. Subgroup analysis in the light of detection methods and specimens was also conducted.

RESULTS

Ten case-control studies were included. Overall meta-analysis favoured a significant association between Helicobacter species infection and cholangiocarcinoma (cumulative OR 8.88, 95% CI 3.67-21.49). Subgroup analysis based on geographic distribution indicated that Helicobacter species infection may serve as a risk factor not only in a region with high cholangiocarcinoma incidence (Asia, OR 6.68, 95% CI 2.29-19.49) but also in low incidence region (Europe, OR 14.90, 95% CI 4.79-46.35). The other subgroup analysis showed that PCR was the most effective and efficient method to detect Helicobacter species in surgically resected tissue and bile. There was significant heterogeneity among studies and obvious publication bias.

CONCLUSION

Our meta-analysis supports the possible association between Helicobacter species infection and cholangiocarcinoma. Further investigations are required to clarify the role of Helicobacter species in this malignancy.

Hepatitis B and C virus infection is a risk factor for the development of cholangiocarcinoma

OBJECTIVE

Chronic hepatitis B virus (HBV) and hepatitis C virus (HCV) infection may be involved in the development of cholangiocarcinoma. The prevalence of HBV and HCV infection was examined in patients with intrahepatic cholangiocarcinoma (ICC) and extrahepatic cholangiocarcinoma (ECC).

METHODS

The levels of HBV surface antigens (HBsAg), antibodies against HBV core antigens (HBcAb) and hepatitis C virus antibodies (HCV-Ab) were determined in sera obtained from 145 consecutive patients (50 patients with ICC, 95 patients with ECC).

RESULTS

The seroprevalence of HBsAg was 10% in the ICC patients and 4.2% in the ECC patients. The prevalence of HCV-Ab was 20% in the ICC patients and 7.4% in the ECC patients.

CONCLUSION

The prevalence of HBsAg and HCV-Ab is 0.8-2.2% and 1-2%, respectively, in the Japanese population living in the Tottori area. Furthermore, HBV and HCV infection is a possible risk factor for the development of cholangiocarcinoma. Therefore, the surveillance of ICC and ECC is needed in HBV and HCV carriers.

Infections of Helicobacter spp. in the biliary system are associated with biliary tract cancer: a meta-analysis

OBJECTIVE

As Helicobacter spp. have been successfully isolated from the biliary system, a hypothetical question was raised about the role of these organisms in the development of biliary tract cancer. This meta-analysis has been carried out to explore the association between Helicobacter spp. infection and biliary tract cancer.

METHODS

A systematic literature search was carried out to identify all eligible articles. Meta-analysis used odds ratio and a random-effect model, and 95% confidence intervals for odds ratios were calculated. Heterogeneity was quantitatively assessed using the χ-test, with significance set at a P-value of 0.01, and was measured using the I-statistic.

RESULTS

Ten studies published between 2002 and 2011 were finally included for meta-analysis. Helicobacter pylori, Helicobacter bilis, Helicobacter hepaticus, and Helicobacter ganmani were studied. With heterogeneity (I=0%, P=0.685), a significantly higher pooled infection rate of Helicobacter spp. was observed in the biliary tract cancer group compared with the normal group (P=0.0001) and the benign biliary disease group, respectively (P=0.0001). Studies from East Asia and South Asia showed a higher prevalence of Helicobacter spp. in the malignant group. Evidence supporting the higher presence of Helicobacter spp. in the cancer group was obtained using PCR and immunohistochemical analysis of specimens from bile and biliary tissues.

CONCLUSION

Our meta-analysis suggests a trend of a higher presence of Helicobacter spp. in patients with biliary tract cancers compared with normal controls or those with benign biliary diseases.

Risk factors for gallbladder cancer and cholangiocarcinoma: similarities, differences and updates

INTRODUCTION

Far-ranging variation in the incidence of gallbladder cancer (GBC) and cholangiocarcinoma (CCA) in different geographic regions on the globe may reflect the risk factor distribution for these tumors

METHODS

The authors give a comprehensive review on the known risk factors for GBC and CCA, and analyze both similarities and differences between the risk factors for the two main types of biliary cancer

DISCUSSION AND CONCLUSION

Leading risk factors for GBC include gallstones, female gender, and advancing age. Primary sclerosing cholangitis, nitrosamine exposure, choledochal cysts, Clonorchis sinensis and Opisthorchis viverrini represent important risk factors for CCA, although a specific risk factor cannot be identified for many patients. While both cancers affect mostly individuals in their sixth decade or older, CCA has a male predominance and GBC--a predilection for females. Although the current level of understanding of the molecular pathogenesis of GBC and CCA at the interface with specific risk factors is significantly lower than for other gastrointestinal malignancies, it continues to evolve and may soon open new avenues for the therapy of biliary cancers.

Are Helicobacter pylori and other Helicobacter species infection associated with human biliary lithiasis? A meta-analysis

Background

Since the isolation of Helicobacter species in biliary system, a hypothetical question was raised about the role of these agents in the development of cholelithiasis. This meta-analysis is to explore the association between the Helicobacter infection and biliary lithiasis.

Methodology/Principal Findings

A systematic literature search was performed to identify all eligible articles. Meta-analysis which was carried out using odds ratio and random effect model, 95% confidence intervals for odds ratio was calculated. Quantitative assessment of heterogeneity was explored by chi-square test with significance set at P value 0.10 and was measured using I² statistic. Eighteen studies published between 1998 and 2011 were finally eligible for meta-analysis. H. Pylori, H. Bilis, H. Hepaticus, H. Pullorum and H. Ganmani were studied. With heterogeneity (I² = 69.5%, P<0.0001), significantly higher pooled infection rates of H. Pylori (OR: 2.59, 35.82% versus 26.75%, P = 0.01) and H. Hepaticus (OR: 3.13, 31.30% versus 12.12%, P = 0.02) were observed in lithiasis group. Higher prevalence of H. Pylori in cholelithiasis patients were reported by studies from East Asia, South Asia and South America. Evidences supporting the higher presence of H. Pylori in cholelithiasis patients could be found by PCR for detecting 16s rRNA in bile, 26kDa protein gene in biliary tissue and immunohistochemistry. Using multiple detection tests could increase the detection rate of H. Pylori.

Conclusions/Significances

Our meta-analysis suggests a trend of higher presence of H. Pylori in cholelithiasis patients than control group and this trend was significant in the regions with higher prevalence of this agent. Evidences supporting the association between Helicobacter and cholelithiasis could be found by using different tests but the gold standard for the identification of these bacteria in biliary system has yet to be established. Considering obvious heterogeneity, a large multi-center study will facilitate us to further clarify the association between the Helicobacter infection and cholelithiasis.

Helicobacter pylori and pathogenesis of gallbladder cancer

BACKGROUND AND AIM

Gallbladder cancer (GBC) is a rare but leading cause of cancer-related deaths worldwide. The incidence of GBC is increasing at an alarming rate in the Varanasi region, and its etiology remains obscure.

METHODS

A total of 108 patients, 54 with GBC and 54 with gallstone diseases (GSD), were examined for Helicobacter pylori (H. pylori) in gallbladder specimens by rapid urease test, biochemical test, histology, culture, serology, polymerase chain reaction (PCR), and partial DNA sequencing. PCR was done using heat shock protein-60 (Hsp60) gene-nested primers.

RESULT

Forty (74%) patients with GBC had gallstones. Upon culture, H. pylori colonies were identified in 24 (44%) GBC and 18 (33%) GSD specimens. H. pylori was detected in 20 (37%) GBC and 15 (28%) GSD samples upon histology. Serology was positive in 17 (32%) GBC and 15 (28%) GSD patients. The DNA isolated from GBC and GSD specimens was amplified by PCR with Hsp60-nested primers in 18 (33%) patients with GBC and 15 (28%) with GSD (P > 0.05). These sequences had 98% similarity with the presubmitted Hsp60 sequences of H. pylori in the National Centre for Biotechnology Information's GenBank.

CONCLUSION

The results revealed that H. pylori was present in a large population, including both GBC and GSD patients, which indicates its endemic presence in the Varanasi region. Thus, it appears H. pylori might not have a significant role in the etiopathogenesis of GBC in our region.

Role of bacteria in oncogenesis

Although scientific knowledge in viral oncology has exploded in the 20th century, the role of bacteria as mediators of oncogenesis has been less well elucidated. Understanding bacterial carcinogenesis has become increasingly important as a possible means of cancer prevention. This review summarizes clinical, epidemiological, and experimental evidence as well as possible mechanisms of bacterial induction of or protection from malignancy.

Serological analysis of Helicobacter hepaticus infection in patients with biliary and pancreatic diseases

BACKGROUND AND AIMS

Infection with Helicobacter hepaticus has been associated with development of hepatocellular carcinoma and gallstones in animal models. In humans, however, the association of H. hepaticus infection with biliary and pancreatic diseases has not been elucidated. The aim of this study was to serologically examine the prevalence of H. hepaticus infection in patients with biliary and pancreatic diseases.

METHODS

Serum samples obtained from 55 patients with cholelithiasis, 18 with bile duct or gallbladder cancer and 19 with pancreatic cancer were studied. Sera were obtained from 34 control subjects who underwent endoscopy and were diagnosed as not having peptic ulcers or cancers. Seropositivity of H. hepaticus was examined by western blot analysis using a H. hepaticus-specific antigen. To validate the specificity, positive sera were also tested after absorption with H. hepaticus whole-cell sonicate. Serum samples were also tested for the presence of anti-Helicobacter pylori antibody.

RESULTS

Prevalence of antibody to H. hepaticus-specific antigen in patients with bile tract cancer was 38.8% and was significantly higher than in control subjects (13.1%, P < 0.05). Prevalence of antibody to H. hepaticus-specific antigen was 18.2% and 10.5% in patients with cholelithiasis and pancreatic cancer, respectively. Seropositivity for H. pylori was similar in all groups. Detection of the H. hepaticus-specific band was significantly decreased after the sera were absorbed with H. hepaticus whole-cell sonicate.

CONCLUSION

Infection with H. hepaticus might be associated with bile duct cancer. Results obtained from absorbed sera suggested high specificity of the western blot analysis.

Detection of Helicobacter hepaticus in human bile samples of patients with biliary disease

BACKGROUND

Since the discovery of Helicobacter pylori, various enterohepatic Helicobacter spices have been detected in the guts of humans and animals. Some enterohepatic Helicobacters have been associated with inflammatory bowel disease or liver disease in mice. However the association of these bacteria with human diseases remains unknown.

MATERIALS AND METHODS

We collected 126 bile samples from patients with cholelithiasis, cholecystitis, gallbladder polyp, and other nonbiliary diseases. Samples were screened for the presence of enterohepatic Helicobacter spp. using cultures, nested PCR, or in situ hybridization. We tested for antibodies to H. pylori and H. hepaticus by Western blot analysis.

RESULTS

Attempts at cultivation were unsuccessful. However, H. hepaticus was detected in bile samples with nested PCR whereas H. bilis was not. Helicobacter hepaticus in the bile was confirmed by in situ hybridization, but H. hepaticus from bile samples was coccoid in appearance. We detected immunoglobulin G antibodies to H. hepaticus in bile samples by Western blotting. Helicobacter hepaticus was detected in 40 (32%) of total 126 samples as H. hepaticus positive if at least one of the three methods with nested PCR, in situ, or Western blotting. Patients with cholelithiasis (41%) and cholecystitis with gastric cancer (36%) had significantly higher (p = .029) prevalence of H. hepaticus infection than samples from patients with other diseases.

CONCLUSION

Helicobacter hepaticus may closely associate with diseases of the liver and biliary tract in humans.

Helicobacter species in cancers of the gallbladder and extrahepatic biliary tract

Helicobacter species have been found in human bile and biliary tract (BT) tissue and are suspected to cause BT diseases, including gallbladder and extrahepatic cancers, collectively referred to in this work as BT cancers. We conducted a literature review of the epidemiological evidence linking the presence of Helicobacter species in bile or BT biopsies to BT cancers and benign diseases. Reports showed great variability with respect to study methods. Nine studies of BT cancers were identified, all with 30 or fewer BT cancers; eight included cancer-free control subjects and used polymerase chain reaction (PCR) as a means of Helicobacter species detection. In four of these studies, Helicobacter species were detected in patients with BT cancer significantly more frequently than in controls, at least when controls without BT diseases were used. In two studies, no Helicobacter species were detected in either cases or controls. Helicobacter species were also often detected in benign BT diseases such as gallstone disease or chronic cholecystitis. As our current knowledge relies on a few small studies that showed substantial differences, larger studies and more standardised protocols for detecting DNA and antibodies against Helicobacter species are needed to investigate a potential association with BT cancer.

Cross-reactivity between immune responses to Helicobacter bilis and Helicobacter pylori in a population in Thailand at high risk of developing cholangiocarcinoma

Helicobacter bilis DNA has been detected in human tissue and is a candidate for etiologic investigations on the causes of hepatic and biliary tract diseases, but reliable serologic tests need to be developed in order to pursue such investigations. The scope of this study was to assess the specificity of two assays for H. bilis immune response allowing for H. pylori, and their cross-reactivity in a population in Thailand at high risk for cholangiocarcinoma. Plasma samples from 92 Thai volunteers were independently tested in two laboratories (Massachusetts Institute of Technology [MIT] and Lund). MIT performed three analyses of H. pylori and H. bilis based either on (i) outer membrane protein (OMP) with no preabsorption or on antigens derived from whole-cell sonicate before (ii) or after (iii) preabsorption with H. pylori sonicate protein. Lund used cell surface proteins from H. pylori and H. bilis as antigens. Testing for H. bilis was preabsorbed with a whole-cell lysate of H. pylori. More than 80% of the samples were positive for H. pylori in both laboratories. As tested by MIT, 58.7% (95% confidence interval, 47.9 to 68.9%) were positive for H. bilis by OMP and 44.5% (34.1 to 55.3%) were positive for H. bilis sonicate protein, but only 15.2% (8.6 to 24.2%) remained positive after preabsorption with H. pylori sonicate protein. Lund found 34.5% of the samples positive for H. bilis (22.0 to 41.0%), which was statistically compatible with all three MIT results. Serologic responses to OMPs of the two bacteria coincided in 66 and 45% of the samples in the MIT and Lund assays, respectively. We found high cross-reactivity between the immune responses to H. pylori and H. bilis antigens. More-specific H. bilis antigens need to be isolated to develop serologic tests suitable for epidemiological studies.

Hepatitis B and C virus infection and the risk of biliary tract cancer: a population-based study in China

Emerging data suggest that chronic hepatitis B virus (HBV) and hepatitis C virus (HCV) infections may also play a role in extrahepatic bile duct cancers. To test the HBV hypothesis, we examined the relationship of HBV/HCV infection with risks of biliary tract cancer and biliary stones in a population-based case-control study conducted in Shanghai, China. Standard assays were used to detect HBV surface antigen (HBsAg) and antibodies against HBV core antigen (anti-HBc) and hepatitis C virus (anti-HCV) in sera from 417 patients with biliary tract cancers, 517 with biliary stones, and 762 healthy controls randomly selected from the population. Unconditional logistic regression was used to calculate the odds ratios (ORs) and 95% confidence intervals (CIs) for each disease type. HBsAg seroprevalence was 7.3% among population controls and 14.2% among patients with extrahepatic bile duct cancer, resulting in a 2.4-fold risk of extrahepatic bile duct cancer (95% CI 1.2-4.5). No association was found for cancers of the gallbladder (prevalence 8.2%) or the ampulla of Vater (6.1%), or for stones in the gallbladder (10.1%) or bile duct (9.3%). Further adjustment for education, smoking, body mass index, diabetes and gallstones did not materially change the results. Prevalence of HCV infection in this population was low (2%), limiting our ability to detect an association with biliary diseases. In Shanghai, an HBV endemic area, chronic HBV infection was associated with a 2.4-fold risk of extrahepatic bile duct cancer. These results should be confirmed in other populations with varying risks of HBV and HCV infection.

Helicobacter pylori in areas of gastric metaplasia in the gallbladder and isolation of H. pylori DNA from gallstones

AIMS

To assess if the areas of gastric metaplasia in the gallbladder are colonised by Helicobacter pylori and to conduct a molecular study of gallstones for presence of H. pylori DNA.

METHODS

Sections from 111 gallbladders with evidence of gastric metaplasia on H&E and Alcian blue-periodic acid-Schiff (pH 2.5) stain were stained with Loeffler's methylene blue and Warthin Starry stain for demonstration of H. pylori. Presence of H. pylori was confirmed by immunohistochemistry. Formalin fixed mucosal tissues and gallstones from 11 cases showing heavy colonisation were subjected to molecular analysis.

RESULTS

Helicobacter pylori was present in 50 of 111 (45%) sections with gastric metaplasia. Areas adjacent to gastric metaplasia in gallbladder showed acute inflammation (6%) and lymphoid follicle formation in 58% of cases with H. pylori that were significantly higher than those seen in sections without H. pylori. In molecular study, 8 of 11 gallstones showed 16S rDNA. Amplification of material from one stone showed positivity for atpA, efp, mutY, ppa, trpC, UreI and vacA genes. Phylogenetic affiliation study of the isolates indicated that H. pylori sequence from the gallstones clustered with Indian strains of H. pylori. No considerable difference was observed in phylogenetic affiliations of eight stones studied.

CONCLUSION

H. pylori colonises areas of gastric metaplasia in gallbladder producing histological changes similar to those seen in gastric mucosa. Isolation of H. pylori DNA from gallstones further support its presence in the gallbladder.

Low prevalence of Helicobacteraceae in gall-stone disease and gall-bladder carcinoma in the German population

Colonisation of the hepatobiliary system with bile-resistant Helicobacter spp. has been proposed as a novel risk-factor in the pathogenesis of gall-bladder carcinoma (GBC). There are reports that biliary Helicobacter colonisation is frequent in countries with a high incidence of gall-bladder carcinoma. However, the prevalence of Helicobacteraceae in the gall-bladders of patients with GBC in Germany, a region with a low incidence of GBC, is unknown. Therefore, gall-bladder tissue from 99 patients who had undergone cholecystectomy was tested, including 57 cases of gall-stone disease (GSD), 20 cases of GBC, and 22 control patients. The presence of Helicobacter spp. was investigated by culture, immunohistochemistry and a group-specific PCR targeting the 16S rRNA gene of all currently known Helicobacteraceae. Of the 99 cases investigated, only one patient with GSD was PCR-positive for Helicobacteraceae. For this individual, sequence analysis of the 16S rRNA gene showed that it had homology closest to the 16S rRNA sequence of Helicobacter ganmani. Helicobacteraceae were not detected by culture or immunohistochemistry. The low prevalence of Helicobacteraceae in the gall-bladders investigated suggests that Helicobacteraceae do not play a predominant role in the pathogenesis of GSD and GBC in the German population. The low prevalence could be a possible explanation for a relatively low incidence of GBC in the German population, despite the fact that GSD, the major risk-factor for GBC, is highly prevalent.

Helicobacter bilis sp. nov., a novel Helicobacter species isolated from bile, livers, and intestines of aged, inbred mice

A fusiform bacterium with 3 to 14 multiple bipolar sheathed flagella and periplasmic fibers wrapped around the cell was isolated from the liver, bile, and lower intestine of aged, inbred mice. The bacteria grew at 37 and 42 degrees C under microaerophilic conditions, rapidly hydrolyzed urea, were catalase and oxidase positive, reduced nitrate to nitrite, did not hydrolyze indoxyl acetate or hippurate, and were resistant to both cephalothin and nalidixic acid but sensitive to metronidazole. On the basis of 16S rRNA gene sequence analysis, the organism was classified as a novel helicobacter, Helicobacter bilis. This new helicobacter, like Helicobacter hepaticus, colonizes the bile, liver, and intestine of mice. Although the organism is associated with multifocal chronic hepatitis, further studies are required to ascertain whether H. bilis is responsible for causing chronic hepatitis and/or hepatocellular tumors in mice.