Hepatitis C virus（HCV）-specific CD8^＋ T cells play an important role in the resolution of HCV infection. Nevertheless, during chronic hepatitis C these cells lack their effector functions and fail to control the vi...Hepatitis C virus（HCV）-specific CD8^＋ T cells play an important role in the resolution of HCV infection. Nevertheless, during chronic hepatitis C these cells lack their effector functions and fail to control the virus. HCV has developed several mechanisms to escape immune control. One of these strategies is the upregulation of negative co-stimulatory molecules such us programmed death-1 （PD-1）. This molecule is upregulated on intrahepatic and peripheral HCV-specific cytotoxic T cells during acute and chronic phases of the disease, whereas PD-1 expression is low in resolved infection. PD-1 expressing HCV-specific CD8^＋ T cells are exhausted with impairment of several effector mechanisms, such as： type-1 cytokine production, expansion ability after antigen encounter and cytotoxic ability. However, PD-1 associated exhaustion can be restored by blocking the interaction between PD-1 and its ligand （PD-L1）. After this blockade, HCV-specific CD8^＋ T cells reacquire their functionality. Nevertheless, functional restoration depends on PD-1 expression level. High PD-l-expressing intrahepatic HCV-specific CD8^＋ T cells do not restore their effector abilities after PD-1/ PD-L1 blockade. The mechanisms by which HCV is able to induce PD-1 up-regulation to escape immune control are unknown. Persistent TCR stimulation by a high level of HCV antigens could favour early PD-1 induction, but the interaction between HCV core protein and gClq receptor could also participate in this process. The PD-1/PD-L1 pathway modulation could be a therapeutic strategy, in conjunction with the regulation of others co-stimulatory pathways, in order to restore immune response aclainst HCV to succeed in clearing the infection.展开更多
Chronic hepatitis B(CHB) remains a challenging global health problem, with nearly one million related deaths per year. Nucleos(t)ide analogue(NA) treatment suppresses viral replication but does not provide complete cu...Chronic hepatitis B(CHB) remains a challenging global health problem, with nearly one million related deaths per year. Nucleos(t)ide analogue(NA) treatment suppresses viral replication but does not provide complete cure of the hepatitis B virus(HBV) infection. The accepted endpoint for therapy is the loss of hepatitis B surface antigen(HBs Ag), but this is hardly ever achieved. Therefore, indefinite treatment is usually required. Many different studies have evaluated NA therapy discontinuation after several years of NA treatment and before HBs Ag loss. The results have indicated that the majority of patients can remain off therapy, with some even reaching HBs Ag seroconversion. Fortunately, this strategy has proved to be safe, but it is essential to consider the risk of liver damage and other comorbidities and to ensure aclose follow-up of the candidates before considering this strategy. Unanswered questions remain, namely in which patients could this strategy be effective and what is the optimal time point at which to perform it. To solve this enigma, we should keep in mind that the outcome will ultimately depend on the equilibrium between HBV and the host's immune system. Viral parameters that have been described as good predictors of response in HBe Ag(+) cases, have proven useless in HBe Ag(-) ones. Since antiviral immunity plays an essential role in the control of HBV infection, we sought to review and explain potential immunological biomarkers to predict safe NA discontinuation in both groups.展开更多
Virus-specific T cells play an important role in the resolution of hepatic infection. However, during chronic hepatitis infection these cells lack their effector functions and fail to control the virus. Hepatitis B vi...Virus-specific T cells play an important role in the resolution of hepatic infection. However, during chronic hepatitis infection these cells lack their effector functions and fail to control the virus. Hepatitis B virus and hepatitis C virus have developed several mechanisms to generate immune tolerance. One of these strategies is the depletion of virus-specific T cells by apoptosis. The immunotolerogenic liver has unique property to retain and activate na ve T cell to avoid the over reactivation of immune response against antigens which is exploited by hepatotropic viruses to persist. The deletion of the virus-specific T cells occurs by intrinsic (passive) apoptotic mechanism. The pro-apoptotic molecule Bcl-2 interacting mediator (Bim) has attracted increasing attention as a pivotal involvement in apoptosis, as a regulator of tissue homeostasis and an enhancer for the viral persistence. Here, we reviewed our current knowledge on the evidence showing critical role of Bim in viral-specific T cell death by apoptotic pathways and helps in the immune tolerance.展开更多
BACKGROUND Antiviral treatment of patients with chronic hepatitis B(CHB)in the grey zone of treatment comands risk management in order to optimize the health outcome.In this sense,the identification of HBV mutants rel...BACKGROUND Antiviral treatment of patients with chronic hepatitis B(CHB)in the grey zone of treatment comands risk management in order to optimize the health outcome.In this sense,the identification of HBV mutants related with an increased risk of hepatocellular carcinoma(HCC)could be useful to identify subpopulations with potential indication of antiviral treatment.AIM To analyze the prevalence/persistence of hepatitis B virus(HBV)preS and basal core promoter(BCP)/precore/core variants associated to HCC development in CHB patients in the grey zone.METHODS Work was designed as a longitudinal retrospective study,including 106 plasma samples from 31 patients with CHB in the grey zone of treatment:Hepatitis B e antigen negative,HBV-DNA levels between 12-20000 IU/mL,normal or discordant transaminase levels during follow up and mild/moderate necroinflammatory activity in liver biopsy or Fibroscan(up to 9.5 kPa).Serum HBVDNA was tested using the Abbott Real Time HBV Assay and the BCP/precore/core and the hepatitis B surface antigen(HBsAg)coding regions were analyzed in positive samples by PCR/bulk-sequencing to identify the HCCrelated HBV mutants.RESULTS High-risk HCC related mutants were detected in 24(77%)patients:19(61%)in the BCP/precore/core,and 7(23%)in the HBsAg coding region(2 preS1 and 5 preS2 deletions).The prevalence of preS deletions was genotype-dependent:3/5(60%)patients with preS2 deletions and 1/2 with preS1 deletions were infected with the HBV-E genotype.Since HBV-E was the most prevalent in sub-Saharan patients,a correlation between preS deletions and ethnicity was also found:6/8(75%)sub-Saharan vs 1/19(5%)Caucasian patients had preS deletions(P=0.00016).Remarkably,this correlation was maintained in those patients infected with HBV-A,a minor genotype in sub-Saharan patients:2/2 patients infected with HBV-A from West Africa vs 0/6 of Caucasian origin had preS deletions.The HCC related variants were the major strains and persisted over time(up to 48 mo).Patients with preS deletions had a significant higher prevalence of F2 fibrosis stage than the negatives(57%vs 10%,P=0.0078).CONCLUSION HBV genetic analysis of selected populations,like sub-Saharans infected with HBV-E/A genotypes,will allow identification of subpopulations with risk of HCC development due to accumulation of high-risk HBV variants,thus commanding their increased clinical surveillance.展开更多
Hepatitis C virus(HCV)infection is an excellent immunological model for understanding the mechanisms developed by non-cytopathic viruses and tumors to evade the adaptative immune response.The antigen-specific cytotoxi...Hepatitis C virus(HCV)infection is an excellent immunological model for understanding the mechanisms developed by non-cytopathic viruses and tumors to evade the adaptative immune response.The antigen-specific cytotoxic T cell response is essential for keeping HCV under control,but during persistent infection,these cells become exhausted or even deleted.The exhaustion process is progressive and depends on the infection duration and level of antigenemia.During high antigenic load and long duration of infection,T cells become extremely exhausted and ultimately disappear due to apoptosis.The development of exhaustion involves the impairment of positive co-stimulation induced by regulatory cytokines,such as transforming growth factor beta 1.This cytokine downregulates tumor necrosis factor receptor(TNFR)-associated factor 1(TRAF1),the signal transducer of the T cell co-stimulatory molecule TNFR superfamily member 9(known as 4-1BB).This impairment correlates with the low reactivity of T cells and an exhaustion phenotype.Treatment with interleukin-7 in vitro restores TRAF1 expression and rescues T cell effector function.The process of TRAF1 loss and its in vitro recovery is hierarchical,and more affected by severe disease progression.In conclusion,TRAF1 dynamics on T cells define a new pathogenic model that describes some aspects of the natural history of HCV,and sheds light on novel immunotherapy strategies for chronic viral infections and cancer.展开更多
基金Supported by Grants from "Fiscam" J.C.C.M (Ayuda para proyectos de investigación en salud PI-2007/32)+5 种基金"Fundación de Investigación Médica Mutua Madrileń a" (Beca Ayudas a la Investigación FMMM 2548/2008) from SpainBenito-Martínez S was supported by a research grant from "Fiscam" J.C.C.M ("Perfeccionamiento y movilidad de investigadores" MOV-2007_JI/18), SpainCalvino M was supported by a research grant from "Instituto de Salud Carlos III" (Contrato de apoyo a la investigación en el SNS’’ CA07/00157), Spain
文摘Hepatitis C virus（HCV）-specific CD8^＋ T cells play an important role in the resolution of HCV infection. Nevertheless, during chronic hepatitis C these cells lack their effector functions and fail to control the virus. HCV has developed several mechanisms to escape immune control. One of these strategies is the upregulation of negative co-stimulatory molecules such us programmed death-1 （PD-1）. This molecule is upregulated on intrahepatic and peripheral HCV-specific cytotoxic T cells during acute and chronic phases of the disease, whereas PD-1 expression is low in resolved infection. PD-1 expressing HCV-specific CD8^＋ T cells are exhausted with impairment of several effector mechanisms, such as： type-1 cytokine production, expansion ability after antigen encounter and cytotoxic ability. However, PD-1 associated exhaustion can be restored by blocking the interaction between PD-1 and its ligand （PD-L1）. After this blockade, HCV-specific CD8^＋ T cells reacquire their functionality. Nevertheless, functional restoration depends on PD-1 expression level. High PD-l-expressing intrahepatic HCV-specific CD8^＋ T cells do not restore their effector abilities after PD-1/ PD-L1 blockade. The mechanisms by which HCV is able to induce PD-1 up-regulation to escape immune control are unknown. Persistent TCR stimulation by a high level of HCV antigens could favour early PD-1 induction, but the interaction between HCV core protein and gClq receptor could also participate in this process. The PD-1/PD-L1 pathway modulation could be a therapeutic strategy, in conjunction with the regulation of others co-stimulatory pathways, in order to restore immune response aclainst HCV to succeed in clearing the infection.
基金Supported by grants from the “Instituto de Salud Carlos Ⅲ”,Spain and the “European Regional Development Fund(ERDF),a way of making Europe”,No.PI12/00130 and No.PI15/00074the “Gilead Spain & Instituto de Salud Carlos Ⅲ”,No.GLD14_00217 and No.GLD16_00014
文摘Chronic hepatitis B(CHB) remains a challenging global health problem, with nearly one million related deaths per year. Nucleos(t)ide analogue(NA) treatment suppresses viral replication but does not provide complete cure of the hepatitis B virus(HBV) infection. The accepted endpoint for therapy is the loss of hepatitis B surface antigen(HBs Ag), but this is hardly ever achieved. Therefore, indefinite treatment is usually required. Many different studies have evaluated NA therapy discontinuation after several years of NA treatment and before HBs Ag loss. The results have indicated that the majority of patients can remain off therapy, with some even reaching HBs Ag seroconversion. Fortunately, this strategy has proved to be safe, but it is essential to consider the risk of liver damage and other comorbidities and to ensure aclose follow-up of the candidates before considering this strategy. Unanswered questions remain, namely in which patients could this strategy be effective and what is the optimal time point at which to perform it. To solve this enigma, we should keep in mind that the outcome will ultimately depend on the equilibrium between HBV and the host's immune system. Viral parameters that have been described as good predictors of response in HBe Ag(+) cases, have proven useless in HBe Ag(-) ones. Since antiviral immunity plays an essential role in the control of HBV infection, we sought to review and explain potential immunological biomarkers to predict safe NA discontinuation in both groups.
基金Supported by Grants from "Fiscam" JCCM, Ayuda para proyectos de investigación en salud, PI-2010/022"Fundación de Investigación Médica Mutua Madrilea", Beca Ayudas a la Investigación FMMM, 8922/2011A research grant from "Asociación de Hepatología Translacional", No. AHT 2010-01, to Lokhande MU
文摘Virus-specific T cells play an important role in the resolution of hepatic infection. However, during chronic hepatitis infection these cells lack their effector functions and fail to control the virus. Hepatitis B virus and hepatitis C virus have developed several mechanisms to generate immune tolerance. One of these strategies is the depletion of virus-specific T cells by apoptosis. The immunotolerogenic liver has unique property to retain and activate na ve T cell to avoid the over reactivation of immune response against antigens which is exploited by hepatotropic viruses to persist. The deletion of the virus-specific T cells occurs by intrinsic (passive) apoptotic mechanism. The pro-apoptotic molecule Bcl-2 interacting mediator (Bim) has attracted increasing attention as a pivotal involvement in apoptosis, as a regulator of tissue homeostasis and an enhancer for the viral persistence. Here, we reviewed our current knowledge on the evidence showing critical role of Bim in viral-specific T cell death by apoptotic pathways and helps in the immune tolerance.
基金Supported by Análisis genético y epigenético del VHB en pacientes portadores asintomáticos.Implicaciones en la decisión terapéutica funded in the 1~(st) Edition of the Gilead Fellowship Program,No.GLD13/00046 and Modificaciones de los niveles de expresión génica mediada por mutantes naturales de la región PreS del virus de la hepatitis B,y asociación con genes implicados en el desarrollo de hepatocarcinoma Efecto del tratamiento antiviral
文摘BACKGROUND Antiviral treatment of patients with chronic hepatitis B(CHB)in the grey zone of treatment comands risk management in order to optimize the health outcome.In this sense,the identification of HBV mutants related with an increased risk of hepatocellular carcinoma(HCC)could be useful to identify subpopulations with potential indication of antiviral treatment.AIM To analyze the prevalence/persistence of hepatitis B virus(HBV)preS and basal core promoter(BCP)/precore/core variants associated to HCC development in CHB patients in the grey zone.METHODS Work was designed as a longitudinal retrospective study,including 106 plasma samples from 31 patients with CHB in the grey zone of treatment:Hepatitis B e antigen negative,HBV-DNA levels between 12-20000 IU/mL,normal or discordant transaminase levels during follow up and mild/moderate necroinflammatory activity in liver biopsy or Fibroscan(up to 9.5 kPa).Serum HBVDNA was tested using the Abbott Real Time HBV Assay and the BCP/precore/core and the hepatitis B surface antigen(HBsAg)coding regions were analyzed in positive samples by PCR/bulk-sequencing to identify the HCCrelated HBV mutants.RESULTS High-risk HCC related mutants were detected in 24(77%)patients:19(61%)in the BCP/precore/core,and 7(23%)in the HBsAg coding region(2 preS1 and 5 preS2 deletions).The prevalence of preS deletions was genotype-dependent:3/5(60%)patients with preS2 deletions and 1/2 with preS1 deletions were infected with the HBV-E genotype.Since HBV-E was the most prevalent in sub-Saharan patients,a correlation between preS deletions and ethnicity was also found:6/8(75%)sub-Saharan vs 1/19(5%)Caucasian patients had preS deletions(P=0.00016).Remarkably,this correlation was maintained in those patients infected with HBV-A,a minor genotype in sub-Saharan patients:2/2 patients infected with HBV-A from West Africa vs 0/6 of Caucasian origin had preS deletions.The HCC related variants were the major strains and persisted over time(up to 48 mo).Patients with preS deletions had a significant higher prevalence of F2 fibrosis stage than the negatives(57%vs 10%,P=0.0078).CONCLUSION HBV genetic analysis of selected populations,like sub-Saharans infected with HBV-E/A genotypes,will allow identification of subpopulations with risk of HCC development due to accumulation of high-risk HBV variants,thus commanding their increased clinical surveillance.
基金Supported by Instituto de Salud Carlos III and European Structural Funds in SpainEuropean Regional Development Fund,No.PI19/00206.
文摘Hepatitis C virus(HCV)infection is an excellent immunological model for understanding the mechanisms developed by non-cytopathic viruses and tumors to evade the adaptative immune response.The antigen-specific cytotoxic T cell response is essential for keeping HCV under control,but during persistent infection,these cells become exhausted or even deleted.The exhaustion process is progressive and depends on the infection duration and level of antigenemia.During high antigenic load and long duration of infection,T cells become extremely exhausted and ultimately disappear due to apoptosis.The development of exhaustion involves the impairment of positive co-stimulation induced by regulatory cytokines,such as transforming growth factor beta 1.This cytokine downregulates tumor necrosis factor receptor(TNFR)-associated factor 1(TRAF1),the signal transducer of the T cell co-stimulatory molecule TNFR superfamily member 9(known as 4-1BB).This impairment correlates with the low reactivity of T cells and an exhaustion phenotype.Treatment with interleukin-7 in vitro restores TRAF1 expression and rescues T cell effector function.The process of TRAF1 loss and its in vitro recovery is hierarchical,and more affected by severe disease progression.In conclusion,TRAF1 dynamics on T cells define a new pathogenic model that describes some aspects of the natural history of HCV,and sheds light on novel immunotherapy strategies for chronic viral infections and cancer.
