Adherence, internalization, and persistence of Helicobacter pylori in hepatocytes

The interplay between Helicobacter pylori infection and rs738409 PNPLA3 in metabolic dysfunction-associated steatotic liver disease

BACKGROUND

Recent studies have suggested an association between H. pylori and metabolic-disfunction associated fatty liver disease (MASLD). However, epidemiologic studies have yielded inconsistent results. We aim to evaluate the association of H. pylori and G-allele PNPLA3 in MASLD diagnosis, and markers of severity.

METHODS

A multi-center cross-sectional study was conducted. A total 224 functional dyspepsia (FD) patients cohort who underwent gastroscopy was selected. Biochemical, clinical parameters, ultrasound, FIB-4 score, LSM by VCTE, gastric biopsies, H. pylori status, and rs738409 PNPLA3 were evaluated. A second retrospective cohort of 86 patients with biopsy-proven MASLD who underwent gastroscopy with gastric biopsies was analyzed.

RESULTS

In the FD cohort MASLD was observed in 52%, and H. pylori-positive in 51%. H. pylori infection was associated with MASLD prevalence, but in multivariate analyses adjusted for G-allele PNPLA3, it became not significant. Then in MASLD-only dyspeptic cohort, H. pylori infection was significantly linked to elevated serum AST levels and increased liver stiffness measurements, suggesting a potential role in liver injury and fibrosis. Histopathological analysis in biopsy-proven MASLD patients further supported these findings, showing a significant association between H. pylori infection and increased NAS score, fibrosis stage, and prevalence of MASH. Notably, the combination of H. pylori infection and G-allele PNPLA3 appeared to exacerbate MASLD severity beyond individual effects.

CONCLUSIONS

Our results suggest that H. pylori infection may play a role in the progression of liver injury and fibrosis in patients with MASLD, especially in those with specific genetic predispositions.

Helicobacter pylori cagA/vacAs1-m1 strain is associated with high risk of fibrosis in metabolic-dysfunction-associated steatotic liver disease

INTRODUCTION AND OBJECTIVES

Recent studies have suggested an association between H. pylori and metabolic dysfunction associated steatotic liver disease (MASLD). We aim to evaluate the association of H. pylori virulence genes with non-invasive markers of liver injury and fibrosis in MASLD subjects.

PATIENTS AND METHODS

A total of 362 dyspeptic patients who underwent gastroscopy were selected. Biochemical, clinical parameters, ultrasound, FIB-4 score, liver stiffness measurement (LSM) by vibration-controlled transient elastography (VCTE), gastric biopsies, and H. pylori virulence genes (cagA, vacA) were evaluated.

RESULTS

A cohort comprised of 61 % women and 39 % men with a median age of 52 (40-60) years. MASLD was observed in 42 %, and H. pylori-positive in 45 %. No differences were observed regarding H. pylori status at co-morbid metabolic conditions. In MASLD cohort, H. pylori-positive was associated with higher AST, ALT, FIB-4 and LSM. Indeed, carriers of cagA/vacA-s1/m1-positive allelic combination were associated with higher AST, ALT, FIB-4 and LSM but not cagA/vacA-s1/m1-negative. The OR for high-risk of significant/advanced- fibrosis by VCTE (≥8 kPa) with H. pylori-positive was 2.56 (95 % CI, 1.2-5.75) and for cagA/vacA-s1/-m1-positive allelic carriers was 4.01 (95 % CI, 1.38-11.56), but non-significant association in cagA/vacA-s1/-m1-negative. After adjusting for age, gender, diabetes, BMI and hypertension the OR for VCTE ≥8 kPa with H. pylori-positive was 2.43 (95 % CI, 1.88-12.44), and cagA/vacA-s1/m1-positive allelic carriers was 4.06 (95 % CI, 1.22-14.49).

CONCLUSIONS

In our cohort of functional dyspepsia (FD) patients with MASLD, H. pylori was associated with non-invasive markers of liver injury and fibrosis. Carriers of cagA/vacA-s1/m1-positive allelic combination showed an independent risk of significant/advanced fibrosis by VCTE.

[Mechanisms of Helicobacter pylori Intracellular Infection and Reflections Concerning Clinical Practice]

Helicobacter pylori (H. pylori), for a long time, has generally been considered an extracellular bacterium. However, recent findings have shown that H. pylori can gain entry into host cells, evade attacks from the host immune system and the killing ability of medication, form stable intracellular ecological niche, and achieve re-release into the extracellular environment, thus causing recurrent infections. H. pylori intracellular infection causes cellular signaling and metabolic alterations, which may be closely associated with the pathogenesis and progression of tumors, thereby presenting new challenges for clinical eradicative treatment of H. pylori. Herein, examining this issue from a clinical perspective, we reviewed reported findings on the mechanisms of how H. pylori achieved intracellular infection, including the breaching of the host cell biological barrier, immune evasion, and resistance to autophagy. In addition, we discussed our reflections and the prospects of important questions concerning H. pylori, including the clinical prevention and control strategy, intracellular derivation, and the damage to host cells.

Non-alcoholic fatty liver disease is not independently associated with Helicobacter pylori in a central European screening cohort

BACKGROUND

The association between Helicobacter pylori (Hp) infection and non-alcoholic fatty liver disease (NAFLD) is subject of a contentious debate. Data mainly stem from Asian cohorts whereas European data are scarce. We, therefore, investigated an Austrian colorectal cancer screening cohort for an association between Hp and NAFLD.

METHODS

In total, 5338 consecutive participants undergoing screening colonoscopy at a single center in Austria were evaluated in this cross-sectional study. The primary risk factor was being Hp negative or positive. The primary endpoint was the presence of NAFLD defined by ultrasound (NAFLD; primary endpoint). Uni- and multivariable logistic regression models were fitted to obtain odds ratios (OR) and 95% confidence intervals (95%CI). Finally, this association was analyzed in a subgroup of 1128 patients in whom NAFLD was diagnosed by transient elastography (TE, secondary endpoint).

RESULTS

NAFLD prevalence defined by ultrasound did not differ between Hp positive (48%) and negative patients (45%, P=0.097). Accordingly, in uni- (OR 1.12 95% CI 0.98-1.29; P=0.098) and multivariable analysis adjusting for different risk factors (aOR 0.96 95%CI 0.82-1.13; P=0.601) no independent association was found. On subgroup analysis, NAFLD diagnosed by TE was more prevalent in the Hp positive compared to the Hp negative group (49% vs. 38%, P=0.004) and these patients also had higher steatosis grades. However, after adjustment for risk factors, no independent association between Hp positivity and NAFLD diagnosed by TE (aOR 1.26 95%CI 0.89-1.78; P=0.194) was confirmed.

CONCLUSIONS

In this Central European cohort, Hp-positivity was not associated with the diagnosis of NAFLD. Although Hp positive patients seem to be more likely to have a concomitant NAFLD diagnosis, this association might rather relate to a cardiometabolic risk phenotype than causality.

Unraveling the actin cytoskeleton in the malignant transformation of cholangiocyte biology

Correct actin cytoskeleton organization is vital in the liver organ homeostasis and disease control. Rearrangements of the actin cytoskeleton may play a vital role in the bile duct cells cholangiocytes. An abnormal actin network leads to aberrant cell morphology, deregulated signaling networks and ultimately triggering the development of cholangiocarcinoma (CCA) and paving the route for cancer cell dissemination (metastasis). In this review, we will outline alterations of the actin cytoskeleton and the potential role of this dynamic network in initiating CCA, as well as regulating the course of this malignancy. Actin rearrangements not only occur because of signaling pathways, but also regulate and modify cellular signaling. This emphasizes the importance of the actin cytoskeleton itself as cause for aberrant signaling and in promoting tumorigenic phenotypes. We will highlight the impact of aberrant signaling networks on the actin cytoskeleton and its rearrangement as potential cause for CCA. Often, these exact mechanisms in CCA are limited understood and still must be elucidated. Indeed, focusing future research on how actin affects and regulates other signaling pathways may provide more insights into the mechanisms of CCA development, progression, and metastasis. Moreover, manipulation of the actin cytoskeleton organization highlights the potential for a novel therapeutic area.

Association Between Acid-Suppressive Agents’ Use and Risk of Hepatocellular Carcinoma

Background:

Acid-suppressive agents (ASAs), which are mostly used in patients with upper gastrointestinal diseases (UGIDs), may influence the risk of hepatocellular carcinoma (HCC).

Methods:

A population-based retrospective cohort study was conducted. Patients with UGID who used ASAs and those who did not receive ASAs were identified. Patients without UGIDs were randomly selected and matched (comparison group). All groups were followed up for 6 years. A Cox proportional hazard model was used to estimate the risk of HCC among the different groups.

Results:

Patients with UGID who used ASAs had a significantly elevated HCC risk (adjusted hazard ratio [HR] 1.53; 95% confidence interval [CI], 1.32-1.76] compared to those who did not use ASAs. Patients with UGID who used more than 540 defined daily doses of ASAs had a significantly higher risk of HCC (adjusted HR 2.04; 95% CI, 1.62-2.58). Moreover, the dose effect on HCC risk exhibited a significant increasing trend ( P < .01). Furthermore, patients with UGID who did not use ASAs had a significantly elevated HCC risk (adjusted HR 1.94; 95% CI, 1.59-2.36) compared to the comparison group.

Conclusion:

The use of ASAs increased the risk of HCC in patients with UGIDs, and the effect of ASAs was dose dependent. In addition, UGIDs alone increased the risk of HCC.

Changes of tight junction and interleukin-8 expression using a human gastroid monolayer model of Helicobacter pylori infection

BACKGROUND

Lack of a model that mirrors Helicobacter pylori-induced gastric mucosal inflammation has hampered investigation of early host-bacterial interactions. We used an ex vivo model of human stomach, gastric epithelial organoid monolayers (gastroid monolayers) to investigate interactions of H pylori infection and the apical junctional complex and interleukin-8 (IL-8) expression.

METHOD

Morphology of human antral mucosal gastroid monolayers was evaluated using histology, immunohistochemical (IHC) staining, and transmission electron microscopy (TEM). Functional and gross changes in the apical junctional complexes were assessed using transepithelial electrical resistance (TEER), cytotoxicity assays, and confocal laser scanning microscopy. IL-8 expression was evaluated by real-time quantitative PCR and ELISA.

RESULTS

When evaluated by IHC and TEM, the morphology of gastroid monolayers closely resembled in vivo human stomach. Following inoculation of H pylori, TEER transiently declined (up to 51%) in an H pylori density-dependent manner. TEER recovered by 48 hours post-infection and remained normal despite continued presence and replication of H pylori. Confocal scanning microscopy showed minimal disruption of zonula occludens-1 or E-cadherin structure. IL-8 production was unchanged by infection with either CagA-positive or CagA-negative H pylori and JNK and MEK inhibitors did not suppress IL-8 production, whereas p38 and IKK inhibitor significantly did.

CONCLUSION

Human gastroid monolayers provide a model for experimental H pylori infection more consistent with in vivo human infections than seen with typical gastric epithelial cell lines. This ex vivo system should lead to better understanding of H pylori host-pathogen interactions.

Differentiation of five enterohepatic Helicobacter species by nested PCR with high-resolution melting curve analysis

BACKGROUND

Enterohepatic Helicobacter species (EHS) are widespread in rodent species around the world. Several studies have demonstrated that infection with EHS can interfere with the outcomes of animal experiments in cancer research and significantly influence the study results. Therefore, it is essential to establish a rapid detection and identification of EHS for biomedical research using laboratory rodents. Our study aimed to develop a rapid and sensitive method to detect and distinguish five enterohepatic Helicobacter species.

MATERIALS AND METHODS

Nested PCR followed by high-resolution melting curve analysis (HRM) was developed for identification of H. bilis, H. rodentium, H. muridarum, H. typhlonius, as well as H. hepaticus. To validate the accuracy of nested PCR-HRM analysis, quantitative real-time PCR methods for five different enterohepatic Helicobacter species were developed. A total of 50 cecal samples were tested using both nested PCR-HRM analysis and qPCR method.

RESULTS

The nested PCR-HRM method could distinguish five enterohepatic Helicobacter species by different melting temperatures. The melting curve were characterized by peaks of 78.7 ± 0.12°C for H. rodentium, 80.51 ± 0.09°C for H. bilis, 81.6 ± 0.1°C for H. typhlonius, 82.11 ± 0.18°C for H. muridarum, and 82.95 ± 0.09°C for H. hepaticus.

CONCLUSIONS

The nested PCR-HRM assay is a simple, rapid, and cost-effective assay. This assay could be a useful tool for molecular epidemiology study of enterohepatic Helicobacter infection and an attractive alternative for genotyping of enterohepatic Helicobacter species.

Adhesion and Invasion of Gastric Mucosa Epithelial Cells by Helicobacter pylori

Helicobacter pylori is the main pathogenic bacterium involved in chronic gastritis and peptic ulcer and a class 1 carcinogen in gastric cancer. Current research focuses on the pathogenicity of H. pylori and the mechanism by which it colonizes the gastric mucosa. An increasing number of in vivo and in vitro studies demonstrate that H. pylori can invade and proliferate in epithelial cells, suggesting that this process might play an important role in disease induction, immune escape and chronic infection. Therefore, to explore the process and mechanism of adhesion and invasion of gastric mucosa epithelial cells by H. pylori is particularly important. This review examines the relevant studies and describes evidence regarding the adhesion to and invasion of gastric mucosa epithelial cells by H. pylori.

Extragastric manifestations of Helicobacter pylori infection: Possible role of bacterium in liver and pancreas diseases

Helicobacter pylori (H. pylori) is an ancient microorganism that has co-evolved with humans for over 60000 years. This bacterium typically colonizes the human stomach and it is currently recognized as the most common infectious pathogen of the gastroduodenal tract. Although its chronic infection is associated with gastritis, peptic ulcer, dysplasia, neoplasia, MALT lymphoma and gastric adenocarcinoma, it has been suggested the possible association of H. pylori infection with several extragastric effects including hepatobiliary and pancreatic diseases. Since a microorganism resembling H. pylori was detected in samples from patients with hepatobiliary disorders, several reports have been discussed the possible role of bacteria in hepatic diseases as hepatocellular carcinoma, cirrhosis and hepatic encephalopathy, nonalcoholic fatty liver disease and fibrosis. Additionally, studies have reported the possible association between H. pylori infection and pancreatic diseases, especially because it has been suggested that this infection could change the pancreatic physiology. Some of them have related a possible association between the microorganism and pancreatic cancer. H. pylori infection has also been suggested to play a role in the acute and chronic pancreatitis pathogenesis, autoimmune pancreatitis, diabetes mellitus and metabolic syndrome. Considering that association of H. pylori to liver and pancreas diseases needs further clarification, our work offers a review about the results of some investigations related to the potential pathogenicity of H. pylori in these extragastric diseases.

Impact of Helicobacter pylori on the growth of hepatic orthotopic graft tumors in mice

Helicobacter pylori is a well-known causative organism of chronic gastric diseases and has been found in many hepatic carcinoma samples. To explore the expression of apoptosis-related proteins and carcinoma development in H. pylori-infected livers, we utilized BALB/cAnSlac mice to establish an H. pylori-infected model by oral inoculation and orthotopic grafts of hepatic tumors by H22 cells, respectively. We found that H. pylori colonies could not be cultured from all liver and tumor samples. However, its 16S rRNA was detectable in 85.3% of livers and 66.7% of tumors in the infected mice. Inflammatory cells were observed and thinly distributed in the lobule portions of the liver, and H. pylori mainly existed in the infected hepatic sinusoids and the necrotic areas of the infected tumors. No significant difference was found in liver to body weight ratio between the infected and uninfected. Moreover, the pathological tumor difference was unremarkable between the two. The proliferating cell nuclear antigen (PCNA) and Bcl-2-associated X protein (Bax) expression in the infected tumors was significantly higher and lower, respectively, than those of the uninfected tumors. However, no significant difference in Bcl-2 (B-cell lymphoma 2) expression existed. The results indicate that H. pylori found in the livers which were infected by H. pylori oral inoculation could contribute to the infiltration of inflammatory cells in livers. Although H. pylori has no significant impact on the liver to body weight ratio or tumor Bcl-2 expression, it may upregulate PCNA expression and downregulate Bax expression, respectively. All our findings show that H. pylori may promote proliferation and inhibit apoptosis of tumor cells.

Analysis of the relationship between invasive capability of Helicobacter pylori and gastroduodenal diseases

Helicobacter pylori (H. pylori) may enter into host cells, maybe as a facultative intracellular pathogen. This study aims to reveal the roles of internalized H. pylori in the bacterial pathopoiesis. Transmission electron microscopy was used to observe the invasion of H. pylori. Invasion rates of H. pylori (two standard strains and 43 clinical strains) were examined by gentamicin invasion assay. The cagA, cagE and vacA genes of H. pylori were detected by PCR. The cagA 3'region (cagA-EPIYA) of each strain was sequenced. The secretion of IL-8 from AGS cells and activity of NF-κB induced by intracellular H. pylori were tested by ELISA and the dual-luciferase reporter assay system, respectively. It was found that H. pylori could adhere to and invade AGS cells, then continue to survive and multiply in the cytoplasm. The average invasion rate of H. pylori gastric cancer plants and that of ulcer plants were both higher than that of gastritis plants (P ≈ 0.0001). In the clinical strains, cagA, vacA and cagE were all positive; cagA-EPIYA genotypes included ABD 90.7% (39/43) and ABBD 9.3% (4/43), all without comparability. Notably, the average invasion rate of H. pylori vacA s1c-i1-m1b plants was higher than that of vacA s1c-i1-m2 plants (P=0.0445). In addition, the intracellular H. pylori all could induce IL-8 secretion, which was decreased after cells were pretreated with anti-β1-integrin antibody or SN-50 (an NF-κB inhibitor). The intracellular H. pylori all activated NF-κB, which would be inhibited after cells were pretreated with anti-β1-integrin antibody. These results demonstrate that H. pylori invasive ability and disease severity have a positive correlation, and this intension of invasive ability is associated with the vacA mid-region, not with cagA, cagA-EPIYA or cagE. It is possible that cagA and cagE are essential for the bacterial invasion. Internalized H. pylori can activate NF-κB signal pathway and induce IL-8 secretion, which suggests that H. pylori invasion may be an important strategy to play a role in the development of H. pylori associated diseases.

Autoimmune disease triggered by infection with alphaproteobacteria

Despite having long been postulated, compelling evidence for the theory that microbial triggers drive autoimmunity has only recently been reported. A specific association between Novosphingobium aromaticivorans, an ubiquitous alphaproteobacterium, and primary biliary cirrhosis (PBC) has been uncovered in patients with PBC. Notably, the association between Novosphingobium infection and PBC has been confirmed in a mouse model in which infection leads to the development of liver lesions resembling PBC concomitant with the production of anti-PDC-E2 antibodies that cross-react with conserved PDC-E2 epitopes shared by Novosphingobium. The discovery of infectious triggers of autoimmunity is likely to change our current concepts about the etiology of various autoimmune syndromes and may suggest new and simpler ways to diagnose and treat these debilitating diseases.

Helicobacter pylori cag pathogenicity island (cagPAI) involved in bacterial internalization and IL-8 induced responses via NOD1- and MyD88-dependent mechanisms in human biliary epithelial cells

Helicobacter pylori infection has been proposed to be associated with various diseases of the hepatobiliary tract, including cancer of the bile duct epithelial cells (cholangiocarcinoma, CCA). The ability of H. pylori bacteria to cause pathogenic effects in these cells has, however, yet to be investigated. Given that the cag pathogenicity island (cagPAI) is required for H. pylori pathogenesis in gastric epithelial cells, we investigated wild-type and cag mutant strains for their ability to adhere, be internalized and induce pro-inflammatory responses in two bile duct epithelial cell lines derived from cases of CCA. The findings from these experiments were compared to results obtained with the well-characterized AGS gastric cancer cell line. We showed that the cagPAI encodes factors involved in H. pylori internalization in CCA cells, but not for adhesion to these cells. Consistent with previous studies in hepatocytes, actin polymerization and α5β1 integrin may be involved in H. pylori internalization in CCA cells. As for AGS cells, we observed significantly reduced levels of NF-κB activation and IL-8 production in CCA cells stimulated with either cagA, cagL or cagPAI bacteria, when compared with wild-type bacteria. Importantly, these IL-8 responses could be inhibited via either pre-treatment of cells with antibodies to α5β1 integrins, or via siRNA-mediated knockdown of the innate immune signaling molecules, nucleotide oligomerization domain 1 (NOD1) and myeloid differentiation response gene 88 (MyD88). Taken together, the data demonstrate that the cagPAI is critical for H. pylori pathogenesis in bile duct cells, thus providing a potential causal link for H. pylori in biliary tract disease.

Helicobacter pylori infection in a pig model is dominated by Th1 and cytotoxic CD8+ T cell responses

Helicobacter pylori infection is the leading cause for peptic ulcer disease and gastric adenocarcinoma. Mucosal T cell responses play an important role in mediating H. pylori-related gastric immunopathology. While induced regulatory T (iTreg) cells are required for chronic colonization without disease, T helper 1 (Th1) effector responses are associated with lower bacterial loads at the expense of gastric pathology. Pigs were inoculated with either H. pylori strain SS1 or J99. Phenotypic and functional changes in peripheral blood mononuclear cell (PBMC) populations were monitored weekly, and mucosal immune responses and bacterial loads were assessed up to 2 months postinfection. Both H. pylori strains elicited a Th1 response characterized by increased percentages of CD4(+)Tbet(+) cells and elevated gamma interferon (IFN-γ) mRNA in PBMCs. A subset of CD8(+) T cells expressing Tbet and CD16 increased following infection. Moreover, a significant increase in perforin and granzyme mRNA expression was observed in PBMCs of infected pigs, indicating a predominant cytotoxic immune response. Infiltration of B cells, myeloid cells, T cells expressing Treg- and Th17-associated transcription factors, and cytotoxic T cells was found in the gastric lamina propria of both infected groups. Interestingly, based on bacterial reisolation data, strain SS1 showed greater capacity to colonize and/or persist in the gastric mucosa than did strain J99. This novel pig model of infection closely mimics human gastric pathology and presents a suitable avenue for studying effector and regulatory responses toward H. pylori described in humans.

Colonization of frog Rana temporaria L. urinary bladder by Gram-negative bacteria leads to decreased effect of arginine-vasotocin on water reabsorption from the urinary bladder

In frogs and toads the urinary bladder is very important for the maintenance of water balance due to its ability to store water which can be reabsorbed under the action of arginine-vasotocin (AVT). The usage of isolated bladders as a model for studying the osmotic water permeability (OWP) regulation has a disadvantage which relates to high variability of AVT effect among individuals, some showing insensitivity to the hormone. We hypothesized that the response of the bladder to AVT could depend on the colonization of the mucosal epithelium by Gram-negative bacteria. To test this, paired hemibladders of the frog Rana temporaria were used for measurement of OWP and for analysis of Gram-negative bacteria in the bladder tissue or isolated epithelial cells. Among the 206 frogs studied, 41% were infected by different Enterobacteriaceae, with prevalence of Hafnia alvei and Escherichia coli. In infected bladders the basal level of OWP was unchanged, whereas OWP stimulated by AVT was reduced (non-infected: 2.53 ± 0.13, n = 59, infected: 1.21 ± 0.17 µL min(-1)  cm(-2), n = 38, for the 15 min of AVT action, P < 0.001). In the sample, 100% of hemibladders that responded to AVT very weakly (OWP <0.5 µL min(-1)  cm(-2)) had a bacterial infection. Overnight treatment of hemibladders with mucosal lipopolysaccharide E. coli decreased OWP induced by AVT, forskolin, or IBMX lowering basal and stimulated level of cAMP. The data obtained indicate that the frog bladder epithelium could be colonized by Gram-negative bacteria, probably of cloacal origin, leading to reduction of sensitivity to AVT and to impairment of the urinary bladder to provide osmoregulation.

Cell-cell contact-mediated hepatitis C virus (HCV) transfer, productive infection, and replication and their requirement for HCV receptors

Hepatitis C virus (HCV) infection is believed to begin with interactions between cell-free HCV and cell receptors that include CD81, scavenger receptor B1 (SR-B1), claudin-1 (CLDN1), and occludin (OCLN). In this study, we have demonstrated that HCV spreading from infected hepatocytes to uninfected hepatocytes leads to the transfer of HCV and the formation of infection foci and is cell density dependent. This cell-cell contact-mediated (CCCM) HCV transfer occurs readily and requires all these known HCV receptors and an intact actin cytoskeleton. With a fluorescently labeled replication-competent HCV system, the CCCM transfer process was further dissected by live-cell imaging into four steps: donor cell-target cell contact, formation of viral puncta-target cell conjugation, transfer of viral puncta, and posttransfer. Importantly, the CCCM HCV transfer leads to productive infection of target cells. Taken together, these results show that CCCM HCV transfer constitutes an important and effective route for HCV infection and dissemination. These findings will aid in the development of new and novel strategies for preventing and treating HCV infection.

Helicobacter species DNA in liver and gastric tissues in children and adolescents with chronic liver disease

OBJECTIVE

Enterohepatic Helicobacter species (EHS) have previously been found in adults with hepatobiliary diseases. Here, we report the prevalence of Helicobacter pylori and EHS in liver and gastric tissue in children and adolescents with chronic liver disease (CLD).

MATERIAL AND METHODS

Seventy-seven consecutive children and adolescents with CLD with or without ulcerative colitis or Crohn's disease (UC/CD) were investigated. Tissue samples were analysed using a Helicobacter genus-specific 16S rDNA polymerase chain reaction (PCR) assay and DNA-sequence analysis. Sera from 61 subjects were also analysed using enzyme immunoassay and immunoblotting.

RESULTS

The Helicobacter PCR was positive in 3/23 (13%) livers from patients with primary sclerosing cholangitis and UC, and in 1/2 livers from patients with autoimmune hepatitis (AIH) and UC. Sequenced PCR products matched the 16S rDNA of H. hepaticus, H. muridarum, H. canis, and H. pylori, respectively. H. ganmani and H. bilis were detected in gastric tissues from two AIH patients. H. hepaticus and H. pullorum were found in livers from two patients with acute liver failure and intrahepatic cholestasis. Antibody reactivity to Helicobacter cell-surface proteins was negative.

CONCLUSIONS

H. pylori and EHS can be detected in the livers of some patients with UC and concomitant liver disease, as well as in other children with liver diseases. Multicentre studies from different locations are needed to find out whether these bacteria play a pathogenetic role or whether their presence is an epiphenomenon.

Hypothesis: Targeted Ikkβ deletion upregulates MIF signaling responsiveness and MHC class II expression in mouse hepatocytes

Macrophage migration inhibitory factor (MIF) is causally related to the pathogenesis of chronic liver disease but its hepatocellular mechanisms of action are largely unknown. Scattered reports in the literature hint at functional connections between the expression of MIF and major histocompatibility complex (MHC) Class II molecules. Not surprisingly, these relationships have not yet been explored in hepatocytes because MIF and MHC Class II cell surface receptors are commonly expressed by other cell types including various antigen presenting cells of the immune system. On the other hand, mounting evidence suggests that heteromeric MIF receptors share a common molecule with intracellular MHC Class II complexes, viz., CD74, which also serves as the MHC Class II chaperone; and, while it is unclear what cancer-related role(s) MHC Class II receptors might play, increasing evidence suggests that MIF and CD74 are also implicated in the biology of hepatocellular carcinoma. These reports are provocative for two reasons: firstly, Ikkβ^Δhep mice carrying hepatocyte-targeted deletions of Ikkβ, an IκB kinase complex subunit required for the activation of the transcription factor NF-κB (nuclear factor-κB), have been shown to display heightened susceptibilities to hepatotoxins and chemical hepatocarcinogens; secondly, microarray profiling observations indicate that Ikkβ^Δhep hepatocytes constitutively and “ectopically” overexpress genes, particularly CD74, CD44 (a MIF-receptor subunit) and MHC Class II I-A/E β and I-A α chains, and gene families that regulate host immune process and immune defense responses. These findings together suggest that Ikkβ^Δhep mice might express functional MIF and MHC Class II receptors, leading to increased hepatocellular sensitivity to MIF signaling as well as to the unusual property of antigen presentation; both functions might contribute to the heightened liver disease phenotypes of Ikkβ^Δhep mice. The findings raise questions about the potential existence of cohorts of human patients with genetic abnormalities of Ikkβ that might confer heightened susceptibility to liver disease including hepatocellular carcinoma.

Hepatocellular carcinoma: prevalence and molecular pathogenesis of Helicobacter spp

Helicobacter pylori infection is one of the most common chronic bacterial infections in humans. The association of other Helicobacter spp. with extragastric diseases in animals is well established, and a role of these bacteria in human liver disease is becoming clearer. Several case-control studies have reported possible associations of Helicobacter spp. with various liver diseases, including hepatocellular carcinoma, which is the fifth most common type of carcinoma among men worldwide, and the eighth most common among women. Thus, it is important to understand molecular mechanisms that may lead to hepatotoxicity or hepatocellular dysfunction in which Helicobacter spp. may play a role in inducing malignant transformation of liver cells.

Novel Helicobacter pylori therapeutic targets: the unusual suspects

Understanding the current status of the discovery and development of anti-Helicobacter therapies requires an overview of the searches for therapeutic targets performed to date. A summary is given of the very substantial body of work conducted in the quest to find Helicobacter pylori genes that could be suitable candidates for therapeutic intervention. The products of most of these genes perform metabolic functions, and others have roles in growth, cell motility and colonization. The genes identified as potential targets have been organized into three categories according to their degree of characterization. A short description and evaluation is provided of the main candidates in each category. Investigations of potential therapeutic targets have generated a wealth of information about the physiology and genetics of H. pylori, and its interactions with the host, but have yielded little by way of new therapies.

Helicobacters and extragastric diseases

For two decades, Helicobacter pylori has been considered as the culprit in many extragastric manifestations. However, for several of these supposed associations the hypothesis of an etiological role has not yet been fully investigated. This may be due to a series of factors linked to the epidemiological features of the studies and to the diseases investigated. This review attempts to highlight the main reported associations of H. pylori with extragastric manifestations during the last year. The most convincing data arise in the field of idiopathic thrombocytopenic purpura (ITP) and sideropenic anemia. Long-term follow-up studies have shown that 50% of subjects with ITP maintain a hematological response after H. pylori eradication. There is also growing evidence of the role of H. pylori in other diseases, including ischemic heart disease even though results are not conclusive.

NF-kappaB signaling, liver disease and hepatoprotective agents

The NF-kappaB signaling pathway has particular relevance to several liver diseases including hepatitis (liver infection by Helicobacter, viral hepatitis induced by HBV and HCV), liver fibrosis and cirrhosis and hepatocellular carcinoma. Furthermore, the NF-kappaB signaling pathway is a potential target for development of hepatoprotective agents. Several types of drugs including: selective estrogen receptor modulators (SERMs), antioxidants, proteasome inhibitors, IKK inhibitors and nucleic acid-based decoys have been shown to interfere with NF-kappaB activity at different levels and may be useful for the treatment of liver diseases. However, NF-kappaB also plays an important hepatoprotective function that needs to be taken into consideration during development of new therapeutic regimens.

Extragastric manifestations of Helicobacter pylori infection: other Helicobacters

The finding that Helicobacter pylori is the main cause of gastritis and peptic ulcer disease has opened a new era in the gastrointestinal world. Today there is evidence that H. pylori may also play a role in different nongastric diseases, opening the new "extragastric manifestations of H. pylori infection" field. Concerning this, several studies have been published in the last year. The most convincing data arise from those investigating idiopathic thrombocytopenic purpura and sideropenic anemia, while there is also an increasing evidence for a possible association with atherosclerotic disease. Furthermore, the discovery of a number of other novel Helicobacter species has stimulated the research in different extragastric diseases, in which an infectious hypothesis is plausible. In particular, several species have been studied for a potential role in different liver and intestinal diseases with interesting findings.

Disturbance of apoptosis and DNA synthesis by Helicobacter pylori infection of hepatocytes

We evaluated the effects of infection of hepatocytes with the well-characterized Helicobacter species, H. pylori. Cell number doubled during each 24 h period in mock cultures or following infection with H. pylori 401C (CagA-, VacA-, BabA-, OipA-) (P < 0.05). In contrast, infection with the more virulent H. pylori NCTC11637 (CagA+, VacA+, BabA+, OipA+) resulted in cell arrest (P < 0.05). Furthermore, NCTC11637 activated caspase-3 and increased DNA fragmentation 6.1 +/- 1.2 fold (P < 0.01) and the number of apoptotic bodies 9.4 +/- 3.5 fold (P < 0.01) compared to controls. The effect was greater than with the less virulent strain 401C (3.8 +/- 0.6 fold and 3.9 +/- 1.7, respectively, P < 0.05). Strain NCTC11637 at low concentrations increased cellular DNA synthesis 139 +/- 6% (P < 0.05) but decreased it to 16 +/- 7% (P < 0.01) at high concentrations. In contrast, strain 401C increased DNA synthesis 155 +/- 14% of controls (P < 0.05) at high concentrations. The presence of intracellular NCTC11637 within hepatocytes increased DNA fragmentation 3.0 +/- 0.4 fold (P < 0.01) greater than in controls. H. pylori infection resulted in strain-species-dependent effects on hepatocytes, and virulent strain caused cell arrest and apoptosis of infected hepatocytes.