Expression of TRAIL in liver tissue from patients with different outcomes of HBV infection

Circulating cytokines and alcoholic liver disease: a two-sample bidirectional Mendelian randomization study

BACKGROUND

Increased inflammation in the liver during ethanol exposure is a major feature of alcoholic liver disease (ALD). An important contributing component to the development of ALD is the inflammatory response brought on by immunological response, however the connection between individual circulating cytokines and ALD is still unclear. To ascertain the causation, we conducted a two-sample bidirectional Mendelian randomization research.

METHODS

We extracted 41 cytokines and growth factors of 8293 Europeans and ALD cases of the same ethnicity (1416 cases and 217,376 controls) from the Genome-Wide Association Studies (GWAS) database for two-sample bidirectional MR analysis.

RESULTS

Our analyses suggest that higher interleukin-7 (IL-7) levels are associated with an increased risk of ALD (p = 0.028, OR = 1.191,95% CI = 1.019-1.392), while tumor necrosis factor related apoptosis inducing ligand (TRAIL) is a protective factor for ALD (p = 0.032, OR = 0.863, 95% CI = 0.754-0.988) which can reduce the risk of disease occurrence. In addition, genetically predicted ALD does not affect the expression of circulating cytokines regulators.

CONCLUSIONS

Our study supports that cytokines play a pivotal role in the pathogenesis of ALD. To determine the mechanisms and pathways of action of these biomarkers, further basic research is required to ensure their clinical suitability for preventing and treating ALD.

Functional characterization of a putative tumor necrosis factor superfamily member 10 in blood clam (Tegillarca granosa)

Tumor necrosis factor superfamily member 10 (TNFSF10), also known as tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) or Apo-2L, is one of the important members of the TNF superfamily. It is well demonstrated that TNFSF10 preferentially induces a variety of tumor cell apoptosis, and therefore exerts an important role in tumor immune surveillance. However, the function of TNFSF10 in pathogen defense is poorly understood, especially in invertebrates. The blood clam (Tegillarca granosa), an important commercial marine bivalve, plays an important ecological role in the marine ecosystem. The identification of immune genes will provide new perspective for disease control in the blood clam (T. granosa) farming. To better understand the biological function of TNFSF10 protein, the full-length cDNA of TNFSF10 homologous gene of T. granosa (TgTNFSF10) was cloned and identified for the first time, which was found to contain 1239 base pairs and encode 254 amino acids with a molecular weight of 29.5 kDa and a conserved TNF domain in the C-terminal. Quantitative RT-PCR analysis showed that TgTNFSF10 gene was constitutively expressed in all tested tissues, with the highest expression in hemocytes. LPS, Vibrio alginolyticus and Vibrio parahaemolyticus stimulations dramatically increased the expression of TgTNFSF10 in T. granosa (11.47-fold, 3.71-fold and 8.29-fold compared with the control respectively). In vitro experiments showed that recombinant TgTNFSF10 protein strongly inhibited the proliferation of HepG2 cells. Further confocal microscopy and flow cytometry analysis showed that obvious apoptosis occurred in TgTNFSF10-treated hemocytes and HepG2 cells. To sum up, our study demonstrated that TgTNFSF10 had strong apoptosis-inducing activity, which may participate in the innate immune response of T. granosa to pathogen invasion.

TRAIL inhibits HBV replication and expression by down-regulating liver-enriched transcription factors

BACKGROUND AND STUDY AIMS

To investigate the role of low-concentration TRAIL on HBV replication and expression.

MATERIAL AND METHODS

MTT assay was performed to determine the minimum concentrations of TRAIL protein in HepG2 cell apoptosis. HepG2 cells were transfected by HBV replication plasmid pHBV4.1. After the treatment with low concentration of TRAIL, the culture supernatant was collected to detect HBsAg and HBeAg by ELISA. Proteins were extracted from the resulted cells, followed by total RNA and HBV DNA intermediate replication. Southern Blot and Northern Blot were carried out to detect HBV RNA and HBV DNA replication intermediates, respectively. RT-PCR and Western Blot were carried out to detect gene and protein expressions for HNF4α, PPARα, and RXRα, respectively.

RESULTS

50 ng/ml of TRAIL protein led to significant decline on the secretions of HBsAg and HBeAg. Expression levels of HBV RNA and HBV DNA replication intermediates were significantly decreased too. In addition, gene and protein expressions of HNF4α, PPARα and RXRα also dropped, especially for PPARα whose expressions significantly decreased.

CONCLUSION

TRAIL could inhibit HBV replication and expression by downregulating the expressions of liver-enriched transcription factors HNF4α, PPARα, and RXRα.

TRAIL in oncology: From recombinant TRAIL to nano- and self-targeted TRAIL-based therapies

TNF-related apoptosis-inducing ligand (TRAIL) selectively induces the apoptosis pathway in tumor cells leading to tumor cell death. Because TRAIL induction can kill tumor cells, cancer researchers have developed many agents to target TRAIL and some of these agents have entered clinical trials in oncology. Unfortunately, these trials have failed for many reasons, including drug resistance, off-target toxicities, short half-life, and specifically in gene therapy due to the limited uptake of TRAIL genes by cancer cells. To address these drawbacks, translational researchers have utilized drug delivery platforms. Although, these platforms can improve TRAIL-based therapies, they are unable to sufficiently translate the full potential of TRAIL-targeting to clinically viable products. Herein, we first summarize the complex biology of TRAIL signaling, including TRAILs cross-talk with other signaling pathways and immune cells. Next, we focus on known resistant mechanisms to TRAIL-based therapies. Then, we discuss how nano-formulation has the potential to enhance the therapeutic efficacy of TRAIL protein. Finally, we specify strategies with the potential to overcome the challenges that cannot be addressed via nanotechnology alone, including the alternative methods of TRAIL-expressing circulating cells, tumor-targeting bacteria, viruses, and exosomes.

Insight into the role of TRAIL in liver diseases

TNF-related apoptosis inducing ligand (TRAIL) is a potential antitumor protein known for its ability to selectively eliminate various types of tumor cells without exerting toxic effects in normal cells and tissues. TRAIL has recently been suggested as a potential therapeutic target in hepatocellular carcinoma (HCC) because it promotes apoptosis in cancer cells. Furthermore, studies on the role of TRAIL in liver injury have reported that TRAIL plays an essential role in viral hepatitis, fatty liver diseases, etc. However, several contradictory and confounding effects of TRAIL in these liver diseases have not been fully elucidated or placed into perspective. Hence, this review summarizes recent progress in studies on TRAIL, including its role in apoptotic signaling, potential therapeutic applications of TRAIL in HCC, hepatitis virus infection, and liver fibrosis and cirrhosis.

Interference of Apoptosis by Hepatitis B Virus

Hepatitis B virus (HBV) causes liver diseases that have been a consistent problem for human health, leading to more than one million deaths every year worldwide. A large proportion of hepatocellular carcinoma (HCC) cases across the world are closely associated with chronic HBV infection. Apoptosis is a programmed cell death and is frequently altered in cancer development. HBV infection interferes with the apoptosis signaling to promote HCC progression and viral proliferation. The HBV-mediated alteration of apoptosis is achieved via interference with cellular signaling pathways and regulation of epigenetics. HBV X protein (HBX) plays a major role in the interference of apoptosis. There are conflicting reports on the HBV interference of apoptosis with the majority showing inhibition of and the rest reporting induction of apoptosis. In this review, we described recent studies on the mechanisms of the HBV interference with the apoptosis signaling during the virus infection and provided perspective.

Distinct roles of TNF-related apoptosis-inducing ligand (TRAIL) in viral and bacterial infections: from pathogenesis to pathogen clearance

INTRODUCTION

Apoptotic death of different cells observed during infection is thought to limit overwhelming inflammation in response to microbial challenge. However, the underlying apoptotic death mechanisms have not been well defined. Tumor necrosis factor (TNF) related apoptosis-inducing ligand (TRAIL) is a type II transmembrane protein belonging to the TNF superfamily, which is involved not only in tumor growth suppression but in infection control and also in the regulation of both innate and adaptive immune responses.

FINDINGS

In this review, we have summarized data of recent studies on the influence of the TRAIL/TRAIL receptor (TRAIL-R) system on the development of viral and bacterial infections. TRAIL may have a dual function in the immune system being able to kill infected cells and also to participate in the pathogenesis of multiple infections. Moreover, many pathogens have evolved mechanisms to manipulate TRAIL signaling thus increasing pathogen replication.

CONCLUSION

Present data highlight an essential role for the TRAIL/TRAIL-R system in the regulation and modulation of apoptosis and show that TRAIL has distinct roles in pathogenesis and pathogen elimination. Knowledge of the factors that determine whether TRAIL is helpful or harmful supposes its potential therapeutic implications that are only beginning to be explored.

Hepatitis B Virus X Protein Sensitizes TRAIL-Induced Hepatocyte Apoptosis by Inhibiting the E3 Ubiquitin Ligase A20

Hepatitis B virus (HBV) infection causes hepatocyte death and liver damage, which may eventually lead to cirrhosis and liver cancer. Hepatitis B virus X protein (HBx) is a key antigen that is critically involved in HBV-associated liver diseases. However, the molecular basis for its pathogenesis, particularly in liver damage, has not been well defined. Herein, we report that HBx was able to enhance the susceptibility of hepatocytes to TNF-related apoptosis-inducing ligand (TRAIL)-induced apoptosis. Increased sensitivity to TRAIL was associated with HBx-induced upregulation of miR-125a, which, in turn, suppressed the expression of its putative target gene, A20 E3 ligase. Importantly, we demonstrate that the defective expression of A20 impaired the K63-linked polyubiquitination of caspase-8, which reciprocally enhanced the activation of caspase-8, the recruitment of Fas-associated death domain (FADD), and the formation of death-inducing signaling complex (DISC), thereby promoting HBx-mediated apoptotic signaling. Accordingly, antagonizing miR-125a or ectopically expressing A20 in hepatocytes abolished the pro-apoptotic effect of HBx. Conversely, the overexpression of miR-125a or knockdown of A20 mimicked HBx to enhance TRAIL susceptibility in hepatocytes. Thus, we establish, for the first time, a miR-125a/A20-initiated and caspase-8-targeted mechanism by which HBx modulates apoptotic signaling and increases hepatic susceptibility to the damaging agent, which might provide novel insight into HBV-related liver pathology.

Correlation between the suppressor of cytokine signaling-1 and 3 and hepatitis B virus: possible roles in the resistance to interferon treatment

BACKGROUND

The suppressor of cytokine signaling family (SOCS) is an important negative regulator in the JAK-STAT signaling pathway. This study was designed to explore the correlation between SOCS-1, 2 and 3, Hepatitis B Virus (HBV) and interferon (IFN), and the relationship between SOCS and IFN therapeutic efficacy.

METHODS

Four types of mouse models were established. Mice were administered with HBV replicative plasmid pHBV4.1 and IFN inducer Poly IC (Group A), pHBV4.1 (Group B), Poly IC (Group C) and saline (Group D), respectively. Liver tissues were harvested from the mice and SOCS expression was determined. Meanwhile, patients with chronic hepatitis B (CHB) were treated with pegylated interferon α-2b for 24-48 weeks. Liver biopsy was collected and the baseline SOCS expression was determined. Serum assay was performed for efficacy evaluation and correlation analysis.

RESULTS

In animal studies, the expression level of SOCS-1 and 3 was found in the descending order of B, A, C and D. The difference between Group B and D suggested that HBV could induce SOCS. The difference between Group A and C suggested that HBV could still induce SOCS with up-regulated endogenous IFN. The difference between Group C and D suggested that ploy IC could induce SOCS, while the difference between Group B and A suggested that Poly IC might have a stronger inhibition effect for SOCS. There was no difference in SOCS-2 expression. In clinical studies, eight of twenty-four enrolled patients achieved either complete or partial therapeutic response. The expression of both SOCS-1 and 3 was higher in CHB patients than in normal controls. The baseline HBV-DNA level was positively correlated with SOCS-1 and 3. The age, viral genotype, HBVDNA, SOCS-1 and SOCS-3 were found to be related to IFN efficacy.

CONCLUSION

HBV could induce both SOCS-1 and 3 expression regardless of endogenous IFN level. Elevated IFN could directly up-regulate SOCS-1 and 3 expression, but it could also indirectly down-regulate SOCS-1 and 3 expression by inhibiting HBV replication. HBV might play a more important role in the SOCS up-regulation than IFN, a possible reason why patients with high HBV viral load encounter poor efficacy of IFN treatment.

HIV and co-infections

Despite significant reductions in morbidity and mortality secondary to availability of effective combination anti-retroviral therapy (cART), human immunodeficiency virus (HIV) infection still accounts for 1.5 million deaths annually. The majority of deaths occur in sub-Saharan Africa where rates of opportunistic co-infections are disproportionately high. In this review, we discuss the immunopathogenesis of five common infections that cause significant morbidity in HIV-infected patients globally. These include co-infection with Mycobacterium tuberculosis, Cryptococcus neoformans, hepatitis B virus, hepatitis C virus, and Plasmodium falciparum. Specifically, we review the natural history of each co-infection in the setting of HIV, the specific immune defects induced by HIV, the effects of cART on the immune response to the co-infection, the pathogenesis of immune restoration disease (IRD) associated with each infection, and advances in the areas of prevention of each co-infection via vaccination. Finally, we discuss the opportunities and gaps in knowledge for future research.