Immunopathogenesis: role of innate and adaptive immune responses

Prevention of HBV Reactivation in Hemato-Oncologic Setting during COVID-19

Onco-hematologic patients are highly susceptible to SARS-CoV-2 infection and, once infected, frequently develop COVID-19 due to the immunosuppression caused by tumor growth, chemotherapy and immunosuppressive therapy. In addition, COVID-19 has also been recognized as a further cause of HBV reactivation, since its treatment includes the administration of corticosteroids and some immunosuppressive drugs. Consequently, onco-hematologic patients should undergo SARS-CoV-2 vaccination and comply with the rules imposed by lockdowns or other forms of social distancing. Furthermore, onco-hematologic facilities should be adapted to new needs and provided with numerically adequate health personnel vaccinated against SARS-CoV-2 infection. Onco-hematologic patients, both HBsAg-positive and HBsAg-negative/HBcAb-positive, may develop HBV reactivation, made possible by the support of the covalently closed circular DNA (cccDNA) persisting in the hepatocytic nuclei of patients with an ongoing or past HBV infection. This occurrence must be prevented by administering high genetic barrier HBV nucleo(t)side analogues before and throughout the antineoplastic treatment, and then during a long-term post-treatment follow up. The prevention of HBV reactivation during the SARS-CoV-2 pandemic is the topic of this narrative review.

Peripheral T lymphocytes predict the severity and prognosis in patients with HBV-related acute-on-chronic liver failure

BACKGROUND

Hepatitis B virus-related acute-on-chronic liver failure (HBV-ACLF) is a life-threatening syndrome with high mortality. Biomarkers are urgently needed to predict the prognosis of HBV-ACLF. Recent evidence suggests a key role for immune system in the pathology of HBV-ACLF. Here, we analyzed the correlation between peripheral blood T lymphocytes and the severity and prognosis in HBV-ACLF patients.

METHOD

Sixty-six patients with HBV-ACLF received conventional medical treatments for 4 weeks. Twenty-five healthy subjects and 20 HBV patients were enrolled for comparison. We determined white blood cell count, lymphocytes, CD3+, CD4+ and CD8+ T cells, and CD4+CD25+ Treg cells in the blood of all subjects. Their associations with laboratory parameters before or after treatments were statistically analyzed.

RESULT

The results showed that compare normal subjects and chronic hepatitis B patients, HBV-ACLF patients had significantly increased white blood count, CD4+ T cells and decreased lymphocytes, CD3+ T cells, and Treg cells. Correlation analysis showed that white blood cell, lymphocytes, and peripheral T lymphocytes were correlated with prothrombin activity (PTA) and model for end-stage liver disease (MELD) scores. After treatment, white blood cell, lymphocytes, and peripheral T lymphocytes were also correlated with PTA and MELD scores. Additionally, total bilirubin (TBIL), alanine aminotransferase (ALT), international standard ratio (INR), MELD, and white blood cell count were potential prognostic criteria for HBV-ACLF patients.

CONCLUSION

HBV-ACLF patients had depletion and dysfunction of immune system. Changes of peripheral T lymphocytes were closely related to the pathogenesis and prognosis of disease. Our results may contribute to predict the severity of HBV-ACLF, and provide a prognosis response to improve the treatment of HBV-ACLF.

The BET family in immunity and disease

Innate immunity serves as the rapid and first-line defense against invading pathogens, and this process can be regulated at various levels, including epigenetic mechanisms. The bromodomain and extraterminal domain (BET) family of proteins consists of four conserved mammalian members (BRD2, BRD3, BRD4, and BRDT) that regulate the expression of many immunity-associated genes and pathways. In particular, in response to infection and sterile inflammation, abnormally expressed or dysfunctional BETs are involved in the activation of pattern recognition receptor (e.g., TLR, NLR, and CGAS) pathways, thereby linking chromatin machinery to innate immunity under disease or pathological conditions. Mechanistically, the BET family controls the transcription of a wide range of proinflammatory and immunoregulatory genes by recognizing acetylated histones (mainly H3 and H4) and recruiting transcription factors (e.g., RELA) and transcription elongation complex (e.g., P-TEFb) to the chromatin, thereby promoting the phosphorylation of RNA polymerase II and subsequent transcription initiation and elongation. This review covers the accumulating data about the roles of the BET family in innate immunity, and discusses the attractive prospect of manipulating the BET family as a new treatment for disease.

An Immuno-Clinic score model for evaluating T cell immunity and predicting early antiviral therapy effectiveness in chronic hepatitis B

We generated an Immuno-Clinic score (ICS) model to evaluate T cell immunity based on the clustering of antiviral cytokines and inhibitory molecules in 229 naïve chronic hepatitis B (CHB) patients. 126 patients receiving antiviral therapy were used to validate the model for predicting antiviral therapy effectiveness. Through receiver-operator characteristic curve analysis, the area under the curve, sensitivity, and specificity of the ICS model were 0.801 (95%CI 0.703-0.900), 0.727, and 0.722, respectively. The cut-off value was 0.442. Re-evaluation of T cell immunity in different phases of CHB showed that patients in the immune tolerant phase had the lowest percentage of ICS-high (15%), while patients in the inactive carrier phase had the highest percentage of ICS-high (92%). Patients in the immune active and gray zone phases had 17% and 56% ICS-high, respectively. Elevation of ICS as early as four weeks after treatment could predict the effectiveness of hepatitis B virus (HBV) DNA loss and normalization of alanine aminotransferase, while eight weeks after treatment could predict HBV surface antigen decline. Thus, this ICS model helps clinicians choose an optimal time for initiating antiviral therapy and predicting its efficacy.

cccDNA Maintenance in Chronic Hepatitis B - Targeting the Matrix of Viral Replication

Chronic hepatitis B is a numerically important cause of cirrhosis and hepatocellular carcinoma, despite an effective prophylactic vaccine and well-tolerated and effective oral antivirals. Both the incapacity of the immune system to clear hepatitis B virus (HBV) infection and the unique replication strategies adopted by HBV are considered key determinants of HBV chronicity. In this regard, the formation of the HBV DNA minichromosome, the covalently closed circular DNA (cccDNA), in the nucleus of infected hepatocytes, is essential not only for the production of all viral proteins but also for HBV persistence even after long-term antiviral therapy. Licensed polymerase inhibitors target the HBV reverse transcriptase activity, control the disease with long-term therapy but fail to eliminate the cccDNA. Consequently, the production of viral RNAs and proteins, including the hepatitis B surface antigen (HBsAg), is not abolished. Novel therapeutic efforts that are in the pipeline for early clinical trials explore novel targets and molecules. Such therapeutic efforts focus on achieving a functional cure, which is defined by the loss of HBsAg and undetectable HBV DNA levels in serum. Since a true cure of HBV infection requires the elimination of the cccDNA from infected cells, comprehension of the mechanisms implicated in cccDNA biogenesis, regulation and stability appears necessary to achieve HBV eradication. In this review, we will summarize the state of knowledge on cccDNA metabolism, focusing on insights suggesting potential weak points of the cccDNA that may be key for the development of therapeutic approaches and design of clinical trials aiming at lowering cccDNA loads and activity.

Correlations between cytokines produced by T cells and clinical-virological characteristics in untreated chronic hepatitis B patients

Background

Hepatitis B virus (HBV) replicates non-cytopathically in the hepatocytes and HBV-related diseases are caused by immune-mediated inflammatory events. This study aimed to identify the relationship between clinical-virological characteristics and immunity in untreated chronic hepatitis B (CHB) patients.

Methods

A total of 209 CHB patients were categorized into immune tolerant (IT, n = 17), inactive carrier (IC, n = 20), immune active (IA, n = 120), and gray zone (GZ, n = 72) phases. The quantitative hepatitis B surface antigen (qHBsAg), hepatitis B e antigen (HBeAg), anti-HBeAg (HBeAb), HBV genotype, viral mutant and frequencies of interleukin (IL)-4, IL-17, IL-10 and interferon-gamma (IFN-γ) produced by CD4⁺ and CD8⁺ T cells were tested. We also correlated these cytokines with clinical-virological characteristics using a linear regression model.

Results

CD8⁺ T cells frequency were significantly decreased in IT patients. Levels of CD4⁺ T cells IL-4⁺ or IL-10⁺ were strongly negatively associated with qHBsAg titers. The frequency of IFN-γ produced by CD4⁺ and CD8⁺ T cells showed significant positive association with age and alanine aminotransferase (ALT) level, while that had negative association with qHBsAg titers. Additionally, the ratios of mutations in the HBV precore (PC) stop codon and basal core promoter (BCP) and the combined mutations were 32.5, 27.2, and 11.3%, respectively. The frequency of CD4⁺ T cells IL-17⁺ was higher in patients with a PC mutation than that in patients carrying a wild-type sequence. Finally, little associations among T cell derived IL-4, IL-10, IL-17, and IFN-γ was observed in the current untreated CHB cohort.

Conclusions

Several components of the immune system were correlated with HBV factors that influence an inflammatory process during CHB. Of particular relevance are the significant associations of between CD4⁺ T cells IL-4⁺ and qHBsAg level, and between CD4⁺ T cells IL-17⁺ and the presence of a mutation in PC.

Association Between Polymorphisms of Interleukin 1 Family Genes and Hepatocellular Carcinoma

Background

Hepatocellular carcinoma (HCC) is one of the most common malignancies occurring worldwide and is most frequent type of liver cancer. The risk for developing HCC increases with the severity of inflammation and fibrosis. The members of the interleukin-1 (IL-1) family are primarily proinflammatory cytokines due to their ability to stimulate the expression of genes associated with inflammation and autoimmune diseases. Several studies have suggested that some proinflammatory cytokines, such as the IL-1 family (IL-1α, IL-1β, and IL-1 receptor antagonist) are involved in the pathogenesis of HCC.

Material/Methods

This study aimed to determine whether polymorphisms in the IL-1 family of genes are associated with HCC. We analyzed 178 HCC patients and 397 controls to investigate the association between polymorphisms in IL-1α, IL-1β, and IL-1 receptor antagonist (IL-1RA) genes and HCC in the Korean population. All subjects were genotyped for the selected SNPs in IL-1α, IL-1β, and IL-1RA genes by Golden-Gate SNP Genotyping Assay.

Results

Statistical analysis revealed a significant association at IL-1β between HCC and controls. Three individual polymorphisms (rs1143633, rs3917356, and rs1143627) were found to be associated with HCC. The SNPs of IL-1β gene (rs1143633A>G and rs1143627T>C) protected against HCC in the dominant model (p=0.027, OR=0.59, 95% CI=0.37–0.94; p=0.019, OR=0.56, 95% CI=0.34–0.91). The SNP of IL-1β gene (rs3917356G>A) increased the risk of HCC in the recessive model (p<0.001, OR=2.58, 95% CI=1.53–4.33), whereas other SNPs in IL-1α and IL-1RA showed no significant association between HCC patients and controls.

Conclusions

These results suggest that IL-1β in the IL-1 family contributes to HCC susceptibility.

Association of Toll-Like Receptor 3 and Toll-Like Receptor 9 Single Nucleotide Polymorphisms with Hepatitis C Virus Infection and Hepatic Fibrosis in Egyptian Patients

Toll-like receptors (TLRs) are recognized as fundamental contributors to the immune system function against infections. Hepatitis C virus (HCV) infection represents a global health problem especially in Egypt having the highest HCV prevalence worldwide where HCV infection is a continuing epidemic. The aim of the present study was to investigate the possible association between genetic variation in TLR-3 and TLR-9 and HCV infection and hepatic fibrosis in chronic HCV-positive Egyptian patients. The present study included 100 naïve chronic HCV-positive patients and 100 age- and sex-matched healthy controls. Genotyping of TLR-3 (_7 C/A [rs3775296]), TLR-3 (c.1377C/T [rs3775290]) and TLR-9 (1237T/C [rs5743836]) were done by polymerase chain reaction restriction fragment length polymorphism technique. Frequency of polymorphic genotypes in TLR-3 (_7 C/A), TLR-3 (c.1377C/T) and TLR-9 (1237T/C) were not significantly different between studied HCV-positive patients and controls with P values 0.121, 0.112, and 0.683, respectively. TLR-3 c.1377 T-allele was associated with advanced stage of hepatic fibrosis (P = 0.003).

Hepatitis B immunopathogenesis and immunotherapy

Worldwide there are over 248 million chronic carriers of HBV of whom about a third eventually develop severe HBV-related complications. Due to the major limitations of current therapeutic approaches, the development of more effective strategies to improve therapeutic outcomes in chronic hepatitis B (CHB) patients seems crucial. Immune activation plays a critical role in spontaneous viral control; therefore, new modalities based on stimulation of the innate and adaptive immune responses could result in the resolution of infection and are promising approaches. Here, we summarize the HBV immunopathogenesis, and discuss the encouraging results obtained from the promising immune-based innovations, such as therapeutic vaccination, cytokine therapy, cell-based therapies and blocking inhibitory receptors, as current and future immunotherapeutic interventions.

Association between interleukin-21 gene polymorphisms (rs12508721) and HBV-related hepatocellular carcinoma

Interleukin-21 (IL-21), as a multifunctional cytokine, plays an important role in many diseases, such as cancer, inflammatory and autoimmune diseases. We aimed to investigate the relationship between polymorphisms of IL-21 gene and susceptibility of hepatitis B virus (HBV)-related hepatocellular carcinoma (HCC) in a Chinese population. Studied subjects were divided into three groups: 100 patients with HBV-related HCC, 115 patients with chronic HBV infection and 127 healthy controls. Genomic DNA was isolated from peripheral blood, and the polymerase chain reaction-ligase detection reaction (PCR-LDR) method was used to genotype the SNPs (rs2221903, rs907715 and rs12508721) within IL-21 gene. Our results showed that IL-21 polymorphisms were associated with the risk of HCC and chronic HBV infection when compared with healthy controls. The rs2221903A/G AG genotype was associated with a higher risk of chronic HBV infection when compared with healthy controls [AG versus AA + GG, P = 0.036, OR = 1.898, 95%CI = 1.038-3.471]. The rs12508721C/T TT genotype was related with a lower risk of chronic HBV infection and HBV-related HCC than in healthy controls [TT versus CT + CC, P = 0.026, OR = 0.451, 95%CI = 0.221-0.920; P = 0.049, OR = 0.482, 95%CI = 0.231-1.005]. No significant difference in the genotype and allele distrubutions of rs907715G/A SNP was observed in the HBV-related HCC group, chronic HBV-infected group and the healthy control group when compared to each other. Our findings suggest that the rs12508721T/C and rs2221903A/G polymorphisms of IL-21 gene are associated with the susceptibility of HBV-related HCC and chronic HBV infection. The genetic variant may in fact cause protection against the HBV-related HCC. However, the function in these SNPs of IL-21 gene needs to clarify the mechanisms involved in the pathogenesis of HBV-related HCC further.

Evaluation of the C-Terminal Fragment of Entamoeba histolytica Gal/GalNAc Lectin Intermediate Subunit as a Vaccine Candidate against Amebic Liver Abscess

Background

Entamoeba histolytica is an intestinal protozoan parasite that causes amoebiasis, including amebic dysentery and liver abscesses. E. histolytica invades host tissues by adhering onto cells and phagocytosing them depending on the adaptation and expression of pathogenic factors, including Gal/GalNAc lectin. We have previously reported that E. histolytica possesses multiple CXXC sequence motifs, with the intermediate subunit of Gal/GalNAc lectin (i.e., Igl) as a key factor affecting the amoeba's pathogenicity. The present work showed the effect of immunization with recombinant Igl on amebic liver abscess formation and the corresponding immunological properties.

Methodology/Principal Findings

A prokaryotic expression system was used to prepare the full-length Igl and the N-terminal, middle, and C-terminal fragments (C-Igl) of Igl. Vaccine efficacy was assessed by challenging hamsters with an intrahepatic injection of E. histolytica trophozoites. Hamsters intramuscularly immunized with full-length Igl and C-Igl were found to be 92% and 96% immune to liver abscess formation, respectively. Immune-response evaluation revealed that C-Igl can generate significant humoral immune responses, with high levels of antibodies in sera from immunized hamsters inhibiting 80% of trophozoites adherence to mammalian cells and inducing 80% more complement-mediated lysis of trophozoites compared with the control. C-Igl was further assessed for its cellular response by cytokine-gene qPCR analysis. The productions of IL-4 (8.4-fold) and IL-10 (2-fold) in the spleen cells of immunized hamsters were enhanced after in vitro stimulation. IL-4 expression was also supported by increased programmed cell death 1 ligand 1 gene.

Conclusions/Significance

Immunobiochemical characterization strongly suggests the potential of recombinant Igl, especially the C-terminal fragment, as a vaccine candidate against amoebiasis. Moreover, protection through Th2-cell participation enabled effective humoral immunity against amebic liver abscesses.

Amebiasis, a neglected tropical disease caused by the protozoan parasite Entamoeba histolytica, is the second leading cause of death from protozoan diseases. Vaccination is considered as an effective strategy against amebiasis; however, clinical vaccines have yet to be developed. We previously reported that the intermediate subunit of Gal/GalNAc lectin (Igl) of E. histolytica is a key factor related to the adherence and cytotoxicity of this parasite to host cells. This study focused on the immune efficacy and immunological characterization of recombinant Igl and its fragments. Highly effective protection was observed in the hamsters immunized intramuscularly with the C-terminal fragment of Igl (C-Igl). C-Igl was further assessed to determine the immunological basis of protection. The immunized hamsters generated high levels of specific antibodies; these hamsters also showed an enhanced complementary-mediated lysis. The spleen cells from the immunized hamsters produced the cytokines IL-4, IL-10, and programmed cell death 1 ligand 1 after these cells were stimulated by C-Igl in vitro. These results demonstrate that recombinant Igl, particularly the C-terminal fragment, is a candidate vaccine for amebiasis. Nevertheless, further studies on Igl should be conducted to explore the preliminary steps of the development of vaccines for human amebiasis.

Expression of microRNA-155 correlates positively with the expression of Toll-like receptor 7 and modulates hepatitis B virus via C/EBP-β in hepatocytes

Effective recognition of viral infection and successive activation of antiviral innate immune responses are vital for host antiviral defence, which largely depends on multiple regulators, including Toll-like receptors (TLRs) and microRNAs. Several early reports suggest that specific TLR-mediated immune responses can control hepatitis B virus (HBV) replication and express differentially with disease outcome. Considering the versatile function of miR-155 in the TLR-mediated innate immune response, we aimed to study the association between miR-155 and TLRs and their subsequent impact on HBV replication using both a HBV-replicating stable cell line (HepG2.2.15) and HBV-infected liver biopsy and serum samples. Our results showed that miR-155 was suppressed during HBV infection and a subsequent positive correlation of miR-155 with TLR7 activation was noted. Further, ectopic expression of miR-155 in vitro reduced HBV load as evidenced from reduced viral DNA, mRNA and subsequently reduced level of secreted viral antigens (HBsAg and HBeAg). Our results further suggested that CCAAT/enhancer-binding protein-β (C/EBP-β), a positive regulator of HBV transcription, was inhibited by miR-155. Taken together, our study established a correlation between miR-155 and TLR7 during HBV infection and also demonstrated in vitro that increased miR-155 level could help to reduce HBV viral load by targeting C/EBP-β.

In vitro immunomodulatory activity of interferon alpha on toll-like receptor 9 signaling pathway in chronic hepatitis B

Interferon alpha (IFN-α) is registered for chronic hepatitis B (CHB) treatment. However, the antiviral mechanism of IFN-α and the biological function of many IFN-α responsive genes have not been fully elucidated. We investigated to determine the regulative effect of IFN-α on toll-like receptor (TLR) 9 signaling in peripheral blood mononuclear cells (PBMCs) from CHB patients in vitro. We examined the changes of expression and function of TLR9 signaling pathway in the PBMCs with different treatment methods and investigated the synergism of IFN-α and TLR9 ligand on antiviral cytokine secretions in vitro. The data showed that, for the TLR9 signaling pathway, IFN-α not only augmented the expressions of TLR9 signal transduction molecules but also activated the TLR9 signal function. This study has clearly demonstrated that the TLR9 ligand could stimulate PBMCs that have been pretreated with IFN-α. Furthermore, the quantity of antiviral cytokines secreted by the pretreated PBMCs was greater than those without pretreatment. The interaction between IFN-α and TLR9 ligand appears to be synergistic. Data revealed IFN-α could influence TLR9 signaling transduction and synergistically improve the immune efficacy of TLR9 ligand against CHB. The present study suggests a potential novel mechanism for the antiviral activity against hepatitis B virus and a new individualized antiviral strategy.

Coffee, alcohol and other beverages in relation to cirrhosis mortality: the Singapore Chinese Health Study

Limited experimental and epidemiologic data suggest that coffee may reduce hepatic damage in chronic liver disease. The association between consumption of coffee and other beverages and risk of cirrhosis mortality was evaluated in the Singapore Chinese Health Study. This is a prospective population-based cohort of 63,275 middle-aged and older Chinese subjects who provided data on diet, lifestyle, and medical histories through in-person interviews using a structured questionnaire at enrollment between 1993 and 1998. Mortality from cirrhosis in the cohort was ascertained through linkage analysis with nationwide death registry. After a mean follow-up of 14.7 years, 114 subjects died from cirrhosis; 33 of them from viral hepatitis B (29%), two from hepatitis C (2%), and 14 from alcohol-related cirrhosis (12%). Compared to nondrinkers, daily alcohol drinkers had a strong dose-dependent positive association between amount of alcohol and risk of cirrhosis mortality. Conversely, there was a strong dose-dependent inverse association between coffee intake and risk of nonviral hepatitis-related cirrhosis mortality (P for trend = 0.014). Compared to non-daily coffee drinkers, those who drank two or more cups per day had a 66% reduction in mortality risk (hazard ratio [HR] = 0.34, 95% confidence interval [CI] = 0.14-0.81). However, coffee intake was not associated with hepatitis B-related cirrhosis mortality. The inverse relationship between caffeine intake and nonviral hepatitis-related cirrhosis mortality became null after adjustment for coffee drinking. The consumption of black tea, green tea, fruit juices, or soft drinks was not associated with risk of cirrhosis death.

CONCLUSION

This study demonstrates the protective effect of coffee on nonviral hepatitis-related cirrhosis mortality, and provides further impetus to evaluate coffee as a potential therapeutic agent in patients with cirrhosis.

Correlation of AIM2 expression in peripheral blood mononuclear cells from humans with acute and chronic hepatitis B

The AIM2 (absent in melanoma 2) protein promotes host defenses against invading viruses and pathogenic bacteria through corresponding adapter molecules leading to the initiation of innate immune responses. We investigated the expression of AIM2 in peripheral blood mononuclear cells (PBMCs) from patients with acute hepatitis B (AHB) and chronic hepatitis B (CHB) during different clinical phases, and analyzed the correlation between AIM2 and clinical profiles in these groups. This study indicated that there is higher expression of AIM2, IL-1β, and IL-18 in AHB compared with expression in CHB. The expression of AIM2 mRNA was significantly negatively correlated with serum hepatitis B virus (HBV) load, HBeAg, and significantly positively correlated with IL-1β and IL-18 in AHB patients and CHB patients with immune clearance, which suggests that AIM2 expression is correlated with the immune clearance of HBV in the host. We summarized that there is a higher immune status in AHB, and a lower immune response in CHB. This suggests that the down-regulation of AIM2 may be associated with the chronic development of HB.

Pathology of chronic hepatitis B and chronic hepatitis C

Histologic evaluation of the liver is a major component in the medical management and treatment algorithm of patients with chronic hepatitis B (HBV) and chronic hepatitis C (HCV). Liver biopsy in these patients remains the gold standard, and decisions on treatment are often predicated on the degree of damage and stage of fibrosis. This article outlines the clinical course and serologic diagnosis of HBV and HCV for the clinician and the pathologist, who together have a close working relationship in managing patients with acute and chronic liver disease. The salient histologic features are elucidated in an attempt to provide the clinician with an understanding of the basic histopathology underlying chronic HCV and HBV.

CAPIH: a Web interface for comparative analyses and visualization of host-HIV protein-protein interactions

Background

The Human Immunodeficiency Virus type one (HIV-1) is the major causing pathogen of the Acquired Immune Deficiency Syndrome (AIDS). A large number of HIV-1-related studies are based on three non-human model animals: chimpanzee, rhesus macaque, and mouse. However, the differences in host-HIV-1 interactions between human and these model organisms have remained unexplored.

Description

Here we present CAPIH (Comparative Analysis of Protein Interactions for HIV-1), the first web-based interface to provide comparative information between human and the three model organisms in the context of host-HIV-1 protein interactions. CAPIH identifies genetic changes that occur in HIV-1-interacting host proteins. In a total of 1,370 orthologous protein sets, CAPIH identifies ~86,000 amino acid substitutions, ~21,000 insertions/deletions, and ~33,000 potential post-translational modifications that occur only in one of the four compared species. CAPIH also provides an interactive interface to display the host-HIV-1 protein interaction networks, the presence/absence of orthologous proteins in the model organisms in the networks, the genetic changes that occur in the protein nodes, and the functional domains and potential protein interaction hot sites that may be affected by the genetic changes. The CAPIH interface is freely accessible at http://bioinfo-dbb.nhri.org.tw/capih.

Conclusion

CAPIH exemplifies that large divergences exist in disease-associated proteins between human and the model animals. Since all of the newly developed medications must be tested in model animals before entering clinical trials, it is advisable that comparative analyses be performed to ensure proper translations of animal-based studies. In the case of AIDS, the host-HIV-1 protein interactions apparently have differed to a great extent among the compared species. An integrated protein network comparison among the four species will probably shed new lights on AIDS studies.

[Natural history and clinical manifestations of chronic hepatitis B virus]

Hepatitis B virus (HBV) infection is a serious public health problem worldwide. In the last few decades, major advances have been achieved that have contributed to greater understanding of the natural history and clinical manifestations of this infection. The fluctuation between viral replication and the host's immune response has implications in the pathogenesis and progression of the hepatic lesion. In immunocompetent adults, most HBV infections resolve spontaneously in contrast with progression to chronic infection in most infants. Patients with chronic hepatitis due to HBV or chronic hepatitis B can present at four phases: 1) the immune tolerance phase, 2) HBeAg-positive chronic hepatitis B, 3) inactive HBsAg carrier state, and 4) HBeAg-negative chronic hepatitis. HBeAg-positive or -negative chronic hepatitis can progress to cirrhosis, liver failure and hepatocellular carcinoma. Progression to these complications is more frequent in HBeAg-negative forms, associated with mutations that affect the pre-core region and maintain active viral replication. Risk factors are HBV-DNA positive serum levels, an increase in serum transaminase levels and some genotypes. These factors highlight the need to evaluate and monitor all HBV carriers to identify those who could benefit from early antiviral treatment, thus avoiding progression to more advanced forms of liver disease. These measures could improve prevention and treatment of hepatitis B.

Expression of toll-like receptor 9 in peripheral blood mononuclear cells from patients with different hepatitis B and C viral loads

The aim of the present study was to investigate the expression of toll-like receptors (TLR) 9 in peripheral blood mononuclear cells (PBMC) of patients with chronic hepatitis B and C with different virus copies. The study group included 90 patients (60 with chronic hepatitis B, and 30 with chronic hepatitis C), and 20 healthy people served as control group. The protein and mRNA levels of TLR9 were detected by using flow cytometry and real-time PCR. The serum viral copies of HBV and HCV were measured in all patients, and the correlation between HBV-DNA copies or HCV-RNA copies and the TLR9 expression was analyzed. Our results demonstrated that HBV or HCV infection led to a decreased expression of TLR9 mRNA and protein compared to the control group (P<0.05). The TLR9 protein and mRNA levels were negatively correlated with serum viral copies of HBV and HCV (r=-0.632, r=-0.909, P<0.01). It was concluded that TLR9 mRNA and protein are down-regulated in PBMC of HBV-infected or HCV-infected patients, and they are negatively correlated with serum viral copies and play an important role in detecting viral replication of HBV and HCV.

Genetic polymorphisms in the cytokine genes and risk of hepatocellular carcinoma in low-risk non-Asians of USA

Polymorphisms in cytokine genes responsible for inflammatory and immune responses are associated with risk of hepatocellular carcinoma (HCC) in high-risk Chinese population. Similar data in low-risk populations are lacking. A population-based case-control study of HCC was conducted including 120 HCC patients and 230 matched control subjects of non-Asian residents in Los Angeles County, California. Genetic variants in the interferon gamma (IFNgamma), tumor necrosis factor-alpha (TNFalpha), interleukin-2 (IL-2), IL-4, IL-6, IL-10, IL-12 and IL-18 genes were determined by Taqman assays. The logistic regression method was used to analyze the data. For T helper (Th) 1 genes (IFNgamma, IL-6 and IL-12), relative to the putative high-activity genotypes, individual low-activity genotypes were associated with statistically non-significant increases in HCC risk. The odds ratio (OR) was 1.53 [95% confidence interval (CI) = 0.53-4.39] for three versus zero low-activity genotypes. For Th2 cytokines (IL-4 and IL-10), low- versus high-activity genotypes were associated with statistically non-significant decreases in HCC risk. The OR was 0.64 (95% CI = 0.27-1.55) for two versus zero low-activity genotypes. When the Th1 and Th2 genotypes were examined simultaneously, the highest level of risk was observed in individuals jointly possessing the highest number of low-activity Th1 genotypes and the lowest number of low-activity Th2 genotypes. There was a roughly doubling of risk between these two extreme genetic profiles, which did not reach statistical significance (OR = 1.98, 95% CI = 0.50-7.84, P = 0.08). In contrast to high-risk Chinese, Th1 and Th2 genotypes did not impact in a major way on risk of HCC in USA non-Asians.

Hepatitis B virus infection

Since the introduction of the hepatitis B vaccine and other preventive measures, the worldwide prevalence of hepatitis B infection has fallen. However, chronic infection remains a challenging global health problem, with more than 350 million people chronically infected and at risk of hepatic decompensation, cirrhosis, and hepatocellular carcinoma. An improved understanding of hepatitis B virology, immunology, and the natural course of chronic infection, has identified hepatitis B virus replication as the key driver of immune-mediated liver injury and disease progression. The approval of potent oral antiviral agents has revolutionised hepatitis B treatment since 1998. Conventional and pegylated interferon alfa and nucleoside and nucleotide analogues are widely authorised treatments, and monotherapy with these drugs greatly suppresses virus replication, reduces hepatitis activity, and halts disease progression. However, hepatitis B virus is rarely eliminated, and drug resistance is a major drawback during long term therapy. The development of new drugs and strategies is needed to improve treatment outcomes.

Mouse hepatitis virus liver pathology is dependent on ADP-ribose-1''-phosphatase, a viral function conserved in the alpha-like supergroup

Viral infection of the liver can lead to severe tissue damage when high levels of viral replication and spread in the organ are coupled with strong induction of inflammatory responses. Here we report an unexpected correlation between the expression of a functional X domain encoded by the hepatotropic mouse hepatitis virus strain A59 (MHV-A59), the high-level production of inflammatory cytokines, and the induction of acute viral hepatitis in mice. X-domain (also called macro domain) proteins possess poly-ADP-ribose binding and/or ADP-ribose-1''-phosphatase (ADRP) activity. They are conserved in coronaviruses and in members of the "alpha-like supergroup" of phylogenetically related positive-strand RNA viruses that includes viruses of medical importance, such as rubella virus and hepatitis E virus. By using reverse genetics, we constructed a recombinant murine coronavirus MHV-A59 mutant encoding a single-amino-acid substitution of a strictly conserved residue that is essential for coronaviral ADRP activity. We found that the mutant virus replicated to slightly reduced titers in livers but, strikingly, did not induce liver disease. In vitro, the mutant virus induced only low levels of the inflammatory cytokines tumor necrosis factor alpha and interleukin-6 (IL-6). In vivo, we found that IL-6 production, in particular, was reduced in the spleens and livers of mutant virus-infected mice. Collectively, our data demonstrate that the MHV X domain exacerbates MHV-induced liver pathology, most likely through the induction of excessive inflammatory cytokine expression.

Implication of cytokines: Roles of tumor necrosis factor-alpha in liver injury

Acute liver failure caused by viruses, drugs, or liver resection, is marked by a massive degree of hepatocyte apoptosis and impaired hepatocyte proliferation, the mechanisms of which, however, still remain to be understood. The choice between life and death is associated with events in regulation of the immune system. The liver is continuously exposed to a large antigenic load that includes pathogens, toxins and dietary antigens. Bacterial toxins, including endotoxin and staphylococcal enterotoxin, have been implicated in the pathogenesis of multi-organ failure associated with liver damage through production of cytokines and chemokines. Inflammation involves the sequential activation of signaling pathways leading to the production of both pro- and anti-inflammatory mediators. Among pro-inflammatory mediators, tumor necrosis factor-alpha (TNF-alpha)/TNF receptor (TNFR) systems play central roles in the physiological regulation of apoptosis as well as inflammation and immunity. These pleiotropic biological effects of TNF-alpha result from its ability to initiate different intracellular signaling pathways, which induce both pro-apoptotic and anti-apoptotic molecules. Hepatocytes appear to be poorly responsive to pro-apoptotic stimuli by TNF-alpha. Tumor necrosis factor-alpha, however, induces excessive hepatocyte apoptosis, once cells are sensitized by D-galactosamine or actinomycin D, suggesting that TNF-alpha itself also induces molecules that protect cells from apoptosis by TNF-alpha. Besides the apoptosis-inducing signal, the binding of TNF-alpha to TNFR1 triggers a series of intracellular events that result in the activation of nuclear factor-kappaB (NF-kappaB), phosphatidylinositol 3-kinase (PI3K)/Akt, and c-Jun NH(2)-terminal kinase (JNK). Inhibition of NF-kappaB may be a two-edged sword against liver injury, which inhibits pro-inflammatory gene expression in leukocytes and causes the sensitization of hepatocytes to TNF-alpha-induced apoptosis. A variety of mechanisms exist to modulate the activity of intracellular molecules and thereby affect the ultimate outcome of a liver cell's fate.

Heplisav™: a new hepatitis B vaccine

Heplisav™ is a vaccine comprising recombinant hepatitis B surface antigen mixed with a synthetic oligonucleotide containing CpG motifs, which stimulates innate immunity. A clinical study demonstrated that Heplisav was significantly more immunogenic compared with Engerix-B in terms of an earlier seroprotection (78.9 vs 11.8%) 4 weeks after the first dose, and 100 versus only 64% seroprotection 4 weeks after the second dose. Geometric mean concentrations also peaked earlier in the Heplisav group. A similar finding was confirmed in a Phase III study in an older (aged >40 years) vaccine-naive population, with 100 versus 73.1% seroprotection in Heplisav versus Engerix-B recipients, respectively, 4 weeks after the third injection. The main adverse events were injection-site reactions, but these were usually mild and self-limiting. In conclusion, Heplisav, a vaccine containing a CpG adjuvant mixed with hepatitis B surface antigen, was more immunogenic and produced earlier seroprotection compared with an existing vaccine, Engerix-B.

Toll-like receptor 7 and 9 expression in peripheral blood mononuclear cells from patients with chronic hepatitis B and related hepatocellular carcinoma

AIM

The aim of the present study was to investigate the expression of Toll-like receptors (TLR) 7 and 9 in peripheral blood mononuclear cells (PBMC) of patients with chronic hepatitis B virus (HBV) infection and related hepatocellular carcinoma.

METHODS

The study group was comprised of 52 patients: 41 with chronic hepatitis B and 11 healthy controls. The protein and mRNA levels of TLR7 and TLR9 were evaluated using real-time PCR, Western blot analysis, and flow cytometry. We also detected the serum viral load of HBV in the patients and analyzed the correlation between HBV-DNA copies and the TLR expression.

RESULTS

Our results demonstrated a lower TLR7 expression in all HBV infection groups compared to the controls. We found that HBV infection led to a decreased expression of TLR9 mRNA, but an increased expression of the TLR9 protein compared to the healthy group. The TLR protein levels are related to serum HBV-DNA (P<0.01).

CONCLUSION

There are downregulations of TLR7 expression and TLR9 mRNA in PBMC of HBV-infected patients, but an increased TLR9 expression at the protein level.

Prostacyclin in liver disease: a potential therapeutic option

Complex molecular and cellular mechanisms are involved in the initiation and progression of hepatic fibrosis. Recent studies have shown that hepatic stellate cells, endothelin, cytokines and prostacyclin play crucial roles in this pathology. Prostacyclin exerts vasorelaxant, antioxidant and antifibrotic properties that prevent the development of fibrosis and cirrhosis in liver diseases. In this editorial, the authors discuss some of the molecular and cellular mechanisms involved in the initiation and progression of liver fibrosis and the role played by prostacyclin in counteracting it. At the moment, however, only limited information is available from clinical studies demonstrating the effectiveness of prostacyclin in liver diseases and this makes it difficult to draw any conclusions; further efforts are necessary to verify whether prostacyclin, alone or in combination with other drugs, may be a valid therapeutic option in liver diseases.

Hepatitis B virus-induced oncogenesis

Hepatocellular carcinoma (HCC) is one of the most common cancers in the world with an annual incidence of more than 500 000 in the year 2000. Its incidence is rising in many countries. Recently, it has been estimated that about 53% of HCC cases in the world are related to hepatitis B virus (HBV). The epidemiological association of HBV with HCC is well established. In recent studies, it was revealed that HBsAg carriers have a 25-37 times increased risk of developing HCC as compared to non-infected people. At present, HBV-associated carcinogenesis can be seen as a multi-factorial process that includes both direct and indirect mechanisms that might act synergistically. The integration of HBV DNA into the host genome occurs at early steps of clonal tumor expansion. The integration has been shown in a number of cases to affect a variety of cancer-related genes and to exert insertional mutagenesis. The permanent liver inflammation, induced by the immune response, resulting in a degeneration and regeneration process confers to the accumulation of critical mutations in the host genome. In addition to this, the regulatory proteins HBx and the PreS2 activators that can be encoded by the integrate exert a tumor promoter-like function resulting in positive selection of cells producing a functional regulatory protein. Gene expression profiling and proteomic techniques may help to characterize the molecular mechanisms driving HBV-associated carcinogenesis, and thus potentially identify new strategies in diagnosis and therapy.