Ping-Ning Hsu

Hepatitis C Virus Core Protein Modulates TRAIL-Mediated Apoptosis by Enhancing Bid Cleavage and Activation of Mitochondria Apoptosis Signaling Pathway

Hepatitis C virus (HCV) is a major human pathogen causing chronic liver disease, which leads to cirrhosis of liver and hepatocellular carcinoma. The HCV core protein, a viral nucleocapsid, has been shown to affect various intracellular events, including cell proliferation and apoptosis. However, the precise mechanisms of the effects are not fully understood. In this study, we show that HCV core protein sensitizes human hepatocellular carcinoma cell line, Huh7, conferred sensitivity to TRAIL-, but not Fas ligand-mediated apoptosis. Huh7 cells are resistant to TRAIL, despite the induction of caspase-8 after TRAIL engagement. However, HCV core protein induces TRAIL apoptosis signaling via sequential induction of caspase-8, Bid cleavage, activation of mitochondrial pathway, and effector caspase-3. HCV core protein also induces activation of caspase-9 after TRAIL engagement, and the induction of TRAIL sensitivity by HCV core protein could be reversed by caspase-9 inhibitor. Therefore, the HCV core protein-induced TRAIL-mediated apoptosis is dependent upon activation of caspase-8 downstream pathway to convey the death signal to mitochondria, leading to activation of mitochondrial signaling pathway and breaking the apoptosis resistance. These results combined indicate that the HCV core protein enhances TRAIL-, but not Fas ligand-mediated apoptotic cell death in Huh7 cells via a mechanism dependent on the activation of mitochondria apoptosis signaling pathway. These results suggest that HCV core protein may have a role in immune-mediated liver cell injury by modulation of TRAIL-induced apoptosis.

Enhanced Proliferation and Increased IFN-γ Production in T Cells by Signal Transduced Through TNF-Related Apoptosis-Inducing Ligand

TNF-related apoptosis-inducing ligand (TRAIL, also called Apo2L), a novel member of TNF superfamily, induces apoptosis in transformed cell lines of diverse origin. TRAIL is expressed in most of the cells, and the expression is up-regulated in activated T cells. Four receptors for TRAIL have been identified, and there is complex interplay between TRAIL and TRAIL receptors in vivo. The actual biological function of TRAIL/TRAIL receptor is still not clear. Growing evidence has demonstrated that members of TNF superfamily transduce signals after engagement with their receptors. Cross-linking of TRAIL by plate-bound rTRAIL receptor, death receptor 4-Fc fusion protein enhanced T cell proliferation and increased IFN-γ production in conjunction with immobilized suboptimal anti-CD3 stimulation in mouse splenocytes. The increase of T cell proliferation by death receptor 4-Fc was dose dependent, and this effect could be blocked by soluble rTRAIL proteins, indicating the occurrence of reverse signaling through TRAIL on T cell. The enhanced secretion of IFN-γ mediated via TRAIL could be blocked by SB203580, a p38 mitogen-activated protein kinase-specific inhibitor. Thus, in addition to its role in inducing apoptosis by binding to the death receptors, TRAIL itself can enhance T cell proliferation after TCR engagement and signal the augmentation of IFN-γ secretion via a p38-dependent pathway. This provides another example of reverse signaling by a member of TNF superfamily. In conclusion, our data suggest that TRAIL can itself transduce a reverse signal, and this may shed light on the biological function of TRAIL.

Eradication of Helicobacter pylori prevents ulcer development in patients with ulcer-like functional dyspepsia

Although the eradication of Helicobacter pylori infection benefits patients with gastric or duodenal ulcers, the value of eradicating the infection in the patients with functional dyspepsia (FD) remains controversial.

Helicobacter pylori eradication therapy is effective in the treatment of early-stage H pylori–positive gastric diffuse large B-cell lymphomas

An explorative study evaluates the efficacy of Helicobacter pylori (HP) eradication (HPE) therapy on early-stage gastric diffuse large B-cell lymphomas (DLBCLs) without features of mucosa-associated lymphoid tissue (MALT), the pure (de novo) DLBCLs, in comparison with its efficacy on high-grade transformed gastric MALT lymphomas, the DLBCL(MALT). In total, 50 patients of stage IE/IIE1 HP-positive gastric DLBCLs with frontline HPE treatment were included. HP infection was successfully eradicated in 100% (16/16) of the pure (de novo) DLBCL patients and 94.1% (32/34) of the DLBCL(MALT) patients. In total, 68.8% (11/16) of pure (de novo) DLBCL patients and 56.3% (18/32) of DLBCL(MALT) patients achieved complete pathologic remission (pCR) after HPE therapy. The median time to pCR was 2.1 months (95% confidence interval, 0.6%-3.7%) for pure (de novo) DLBCLs and 5.0 months (95% confidence interval, 2.8%-7.5%; P = .024) for DLBCL(MALT). At a median follow-up of 7.7 years, all patients with pCR after HPE therapy were alive and free of lymphomas, except for one patient with pure (de novo) DLBCL who died of lung cancer. Similar to DLBCL(MALT), a substantial portion of early-stage HP-positive gastric pure (de novo) DLBCLs remains HP-dependent and responds to antibiotic treatment. Prospective studies to validate the findings are warranted.

Helicobacter pylori infection and the risk of gastric malignancy.

OBJECTIVE:This prospective cohort study investigated the impact of Helicobacter pylori infection on the development of various gastric malignancies.METHODS:We prospectively followed up 1,225 dyspeptic Taiwanese who had nonulcer dyspepsia, gastric ulcers, or duodenal ulcers at enrollment. Among them, 618 (50.4%) had H. pylori infection and 607 (49.6%) did not. Patients underwent endoscopy at enrollment and at 1- to 3-yr intervals thereafter.RESULTS:During a mean follow-up of 6.3 yr, gastric adenocarcinoma developed in 7 of the 618 H. pylori-infected patients, but in none of the 607 uninfected patients (1.1% vs 0.0%, P = 0.015). The incidence of gastric lymphoma was 0.2% (1/618) and 0% in H. pylori-infected and uninfected patients. Taken together, the development rate of gastric malignancy in H. pylori-infected patients was significantly higher than that in uninfected patients (1.3% vs 0%, P = 0.007). Among H. pylori-infected subjects, the incidence of gastric malignancy was similar between those receiving and not receiving eradication therapy (1.4% vs 1.2%). Multivariate analysis showed that intestinal metaplasia was the only independent factor predicting subsequent development of gastric malignancy in H. pylori-infected subjects with an odds ratio of 4.5 (95% CI 1.1–19.1).CONCLUSIONS:In this prospective cohort study, all gastric malignancies, including adenocarcinoma and lymphoma, developed in H. pylori-infected patients. The finding implies that H. pylori is a necessary cause of most gastric malignancies. Follow-up for H. pylori-infected patients who have intestinal metaplasia is indicated.

Risk factors for ulcer development in patients with non-ulcer dyspepsia: a prospective two year follow up study of 209 patients

Background and aims: A subset of non-ulcer dyspepsia (NUD) disorders can evolve into peptic ulcer disease. This prospective study attempted to determine the independent risk factors for ulcer formation in NUD patients, and compared the natural history of Helicobacter pylori positive and negative NUD subjects. Methods: From May 1997 to April 1999, consecutive NUD patients were enrolled into the study. Endoscopy was performed routinely on enrolment, at the end of the second and 12th months, and whenever there was a dyspepsia attack. Patients were prospectively followed up for two years. Results: Peptic ulcers occurred in 16 of 209 NUD patients during the two year follow up period. Multivariate analysis of 13 host and bacterial factors demonstrated that advanced age (odds ratio 2.90), H pylori infection (odds ratio 3.59), and use of non-steroidal anti-inflammatory drugs (NSAID; odds ratio 4.46) were independently significant in predicting subsequent peptic ulcer development. NUD patients with all three risk factors had a 75% (3/4) risk of developing peptic ulcer but the ulcer incidence in patients without any of the risk parameters was only 1.2% (1/84). The resolution rate of symptoms in the H pylori positive NUD patients was similar to the H pylori negative patients (57.9% v 49.1%; 95% confidence interval (CI) −5 to 22). However, rates for subsequent peptic ulcer and erosion development were significantly higher in H pylori positive patients than in H pylori negative patients (ulcer 12.6% v 3.5%, 95% CI 1–16; erosion 23.2% v 12.3%, 95% CI 1–21). Conclusion: A small but significant proportion of NUD patients develop peptic ulcer after long term follow up. H pylori infection, NSAID use, and advanced age are independent risk factors for subsequent ulcer formation. Follow up endoscopy is strongly indicated for an NUD patient with multiple risk factors for ulcer formation when symptoms recur.

Hepatitis B virus core antigen determines viral persistence in a C57BL/6 mouse model

We recently developed a mouse model of hepatitis B virus (HBV) persistence, in which a single i.v. hydrodynamic injection of HBV DNA to C57BL/6 mice allows HBV replication and induces a partial immune response, so that about 20–30% of the mice carry HBV for more than 6 months. The model was used to identify the viral antigen crucial for HBV persistence. We knocked out individual HBV genes by introducing a premature termination codon to the HBV core, HBeAg, HBx, and polymerase ORFs. The specific-gene-deficient HBV mutants were hydrodynamically injected into mice and the HBV profiles of the mice were monitored. About 90% of the mice that received the HBcAg-mutated HBV plasmid exhibited high levels of hepatitis B surface antigenemia and maintained HBsAg expression for more than 6 months after injection. To map the region of HBcAg essential for viral clearance, we constructed a set of serial HBcAg deletion mutants for hydrodynamic injection. We localized the essential region of HBcAg to the carboxyl terminus, specifically to the 10 terminal amino acids (HBcAg176–185). The majority of mice receiving this HBV mutant DNA did not elicit a proper HBcAg-specific IFN-γ response and expressed HBV virions for 6 months. These results indicate that the immune response triggered in mice by HBcAg during exposure to HBV is important in determining HBV persistence.

Translocation of Helicobacter pylori CagA into human B lymphocytes, the origin of mucosa-associated lymphoid tissue lymphoma

Infection by cagA-positive Helicobacter pylori (H. pylori) is strongly associated with gastric carcinomas and gastric mucosa-associated lymphoid tissue (MALT) lymphomas. H. pylori translocates the bacterial protein CagA into gastric epithelial cells, and the translocated CagA deregulates intracellular signaling pathways and thereby initiates pathogenesis. This in turn raised the possibility that H. pylori is associated with the development of MALT lymphomas during persistent infection by direct interaction with B lymphocytes. In this work, we showed that CagA can be directly translocated into human B lymphoid cells by H. pylori, and the translocated CagA undergoes tyrosine phosphorylation and binds to intracellular SH-2. Meanwhile, the translocated CagA induces activation of extracellular signal-regulated kinase and p38 mitogen-activated protein kinase in human B lymphoid cells, and upregulates the expressions of Bcl-2 and Bcl-X(L), which prevents apoptosis. These results provide the first direct evidence for the role of CagA as a bacterium-derived oncoprotein that acts in human B cells, and further implies that CagA is directly delivered into B cells by H. pylori and is associated with the development of MALT lymphomas.

Risks of interleukin-1 genetic polymorphisms and Helicobacter pylori infection in the development of gastric cancer

Background : The host genetic factors that determine the clinical outcomes of Helicobacter pylori‐infected individuals remain unclear.

α1-Antitrypsin Precursor in Gastric Juice Is a Novel Biomarker for Gastric Cancer and Ulcer

Purpose: To search for novel disease-specific markers in gastric juice by investigating the protein concentrations and components in gastric juice from patients with various gastroduodenal diseases. Experimental Design: Protein concentrations and pH values in fasting gastric juice were examined in 120 healthy subjects and 39 gastric ulcer, 38 duodenal ulcer, and 31 gastric cancer patients. The protein components in gastric juice were studied by two-dimensional PAGE and mass spectrometric analysis. Results: Protein concentrations in gastric juice of patients with gastric ulcers and gastric cancer were significantly higher than those in healthy subjects (1.06 and 2.61 mg/mL versus 0.48 mg/mL; P = 0.001 and P < 0.001, respectively), and duodenal ulcer patients had lower gastric juice protein concentrations compared with healthy subjects (0.26 versus 0.48 mg/mL; P < 0.05). Gastric hypoacidity and advanced age were independent factors affecting the protein concentrations in gastric juice with odds ratios of 32.9 (95% confidence interval, 11.8-90.9) and 3.2 (95% confidence interval, 1.3-8.3), respectively. Each electrophoresis images of gastric juice could be classified into one of three patterns: basic band, specific band, or nonspecific band. The frequencies of specific band pattern in healthy subjects, gastric ulcer, duodenal ulcer, and gastric cancer patients were 6%, 42%, 6%, and 93%, respectively. Proteomic analysis revealed that α1-antitrypsin precursor was the principal peptide in the specific band. Conclusions: α1-antitrypsin precursor in gastric juice is a novel biomarker for gastric cancer and ulcer. A noninvasive method to obtain gastric juice followed by proteomic analysis may serve as a new tool to screen for gastric malignancies.