Humoral and T-cell-mediated immunity to SARS-CoV-2 vaccination in patients with liver disease and transplant recipients.

BACKGROUND: SARS-CoV-2 vaccination induces a varied immune response among persons with chronic liver disease (CLD) and solid organ transplant recipients (SOTRs). We aimed to evaluate the humoral and T-cell-mediated immune responses to SARS-CoV-2 vaccination in these groups. METHODS: Blood samples were collected following the completion of a standard SARS-CoV-2 vaccination (2 doses of either BNT162b2 or mRNA-12732), and a subset of patients had a blood sample collected after a single mRNA booster vaccine. Three separate methods were utilized to determine immune responses, including an anti-spike protein antibody titer, neutralizing antibody capacity, and T-cell-mediated immunity. RESULTS: The cohort included 24 patients with chronic liver disease, 27 SOTRs, and 9 controls. Patients with chronic liver disease had similar immune responses to the wild-type SARS-CoV-2 compared with controls following a standard vaccine regimen and single booster vaccine. SOTRs had significantly lower anti-S1 protein antibodies (p < 0.001), neutralizing capacity (p < 0.001), and T-cell-mediated immunity response (p = 0.021) to the wild-type SARS-CoV-2 compared with controls following a standard vaccine regimen. Following a single booster vaccine, immune responses across groups were not significantly different but numerically lower in SOTRs. The neutralization capacity of the B.1.1.529 Omicron variant was not significantly different between groups after a standard vaccine regimen (p = 0.87) and was significantly lower in the SOTR group when compared with controls after a single booster vaccine (p = 0.048). CONCLUSION: The immunogenicity of the SARS-CoV-2 vaccine is complex and multifactorial. Ongoing and longitudinal evaluation of SARS-CoV-2 humoral and cellular responses is valuable and necessary to allow frequent re-evaluation of these patient populations.

The synthetic opioid fentanyl increases HIV replication and chemokine co-receptor expression in vitro.

The US is experiencing a major public health crisis that is fueled by the illicit use of synthetic opioids including fentanyl. While several drugs of abuse can enhance viral replication and/or antagonize immune responses, the impact of specific synthetic opioids on HIV pathogenesis is poorly understood. Thus, we evaluated the effects of fentanyl on HIV replication in vitro. HIV-susceptible or HIV-expressing cell lines were incubated with fentanyl. HIV p24 synthesis and chemokine receptor levels were quantified by ELISA in culture supernatants and cell lysates, respectively. Addition of fentanyl resulted in a dose-dependent increase in HIV replication. Fentanyl enhanced expression of the HIV chemokine co-receptors CXCR4 and CCR5 and caused a dose-dependent decrease in cell viability. The opioid antagonist naltrexone blocked the effect of fentanyl on HIV replication and CCR5 receptor levels but not CXCR4 receptor levels. TLR9 expression was induced by HIV; however, fentanyl inhibited TLR9 expression in a dose-dependent manner. These data demonstrate that the synthetic opioid fentanyl can promote HIV replication in vitro. As increased HIV levels are associated with accelerated disease progression and higher likelihood of transmission, additional research is required to enhance the understanding of opioid-virus interactions and to develop new and/or optimized treatment strategies for persons with HIV and opioid use disorder.

Viral hepatitis in pregnancy.

Viral hepatitis is caused by a heterogenous group of viral agents representing a wide range of phylogenetic groups. Many viruses can involve the liver and cause liver injury but only a subset are delineated as 'hepatitis viruses' based upon their primary site of replication and tropism for hepatocytes which make up the bulk of the liver cell population. Since their discovery, beginning with the agent that caused serum hepatitis in the 1960s, the alphabetic designations have been utilized. To date, we have five hepatitis viruses, A through E, though it is postulated that others may exist. This chapter will focus on those viruses. Note that hepatitis D is included as a subset of hepatitis B, as it cannot exist without concurrent hepatitis B infection. Pregnancy has the potential to affect all aspects of these viral agents due to the unique immunologic and physiologic changes that occur during and after the gestational period. In this review, we will discuss the most common viral hepatitis and their effects during pregnancy.

The synthetic opioid fentanyl enhances viral replication in vitro.

The US is in the midst of a major drug epidemic fueled in large part by the widespread recreational use of synthetic opioids such as fentanyl. Persons with opioid use disorder are at significant risk for transmission of injection-associated infections such as hepatitis B virus (HBV) and hepatitis C virus (HCV). Commonly abused substances may antagonize immune responses and promote viral replication. However, the impact of synthetic opioids on virus replication has not been well explored. Thus, we evaluated the impact of fentanyl and carfentanil using in vitro systems that replicate infectious viruses. Fentanyl was used in cell lines replicating HBV or HCV at concentrations of 1 ng, 100 ng, and 10 ug. Viral protein synthesis was quantified by ELISA, while apoptosis and cell death were measured by M30 or MTT assays, respectively. HCV replicative fitness was evaluated in a luciferase-based system. RNAseq was performed to evaluate cellular gene regulation in the presence of fentanyl. Low dose fentanyl had no impact on HCV replication in Huh7.5JFH1 hepatocytes; however, higher doses significantly enhanced HCV replication. Similarly, a dose-dependent increase in HCV replicative fitness was observed in the presence of fentanyl. In the HepG2.2.15 hepatocyte cell line, fentanyl caused a dose-dependent increase in HBV replication, although only a higher doses than for HCV. Addition of fentanyl resulted in significant apoptosis in both hepatocyte cell lines. Cell death was minimal at low drug concentrations. RNAseq identified a number of hepatocyte genes that were differentially regulated by fentanyl, including those related to apoptosis, the antiviral / interferon response, chemokine signaling, and NFκB signaling. Collectively, these data suggest that synthetic opioids promote viral replication but may have distinct effects depending on the drug dose and the viral target. As higher viral loads are associated with pathogenesis and virus transmission, additional research is essential to an enhanced understanding of opioid-virus pathogenesis and for the development of new and optimized treatment strategies.

HBV and HIV/HBV Infected Patients Have Distinct Immune Exhaustion and Apoptotic Serum Biomarker Profiles.

BACKGROUND: Hepatitis B virus (HBV) infection is a leading cause of chronic hepatitis, liver cirrhosis, and hepatocellular carcinoma worldwide. Due to their shared routes of transmission, approximately 10% of HIV-infected patients worldwide are chronically coinfected with HBV. Additionally, liver disease has become a major cause of morbidity and mortality in HBV/HIV coinfected patients due to prolonged survival with the success of antiretroviral therapy. The relationship between immune exhaustion markers (PD-1/PD-L1) and apoptotic markers such as Fas/FasL, TGFß1, TNF-α, and Th1/Th2 cytokines are not clearly delineated in HBV/HIV coinfection. METHODS: Levels of soluble Fas/FasL, TGFß1, TNF-α, and sPD-1/sPD-L1 as well as Th1 and Th2 cytokines were evaluated in the sera of HBV-monoinfected (n = 30) and HBV/HIV-coinfected (n = 15) patients and compared to levels in healthy controls (n = 20). RESULTS: HBV-monoinfected patients had significantly lower levels of the anti-inflammatory cytokine IL-4 (P < 0.05) and higher levels of apoptotic markers sFas, sFasL, and TGFß-1 (P < 0.001) compared to healthy controls. Coinfection with HIV was associated with higher levels of sFas, TNF-α, and sPD-L1 (P < 0.005), and higher levels of the pro-inflammatory cytokines IL-6, IL-8, and IL-12p70 (P < 0.05) compared to healthy controls. Patients with HBV infection had a unique biomarker clustering profile comprised of IFN-γ, IL12p70, IL-10, IL-6, and TNF-α that was distinct from the profile of the healthy controls, and the unique HIV/HBV profile comprised GM-CSF, IL-4, IL-2, IFN-γ, IL12p70, IL-7, IL-10, and IL-1ß. In HBV monoinfection a significant correlation between sFasL and PD1(r = 0.46, P = < 0.05) and between sFas and PDL1 (r = 0.48, P = <0.01) was observed. CONCLUSION: HBV-infected and HBV/HIV-coinfected patients have unique apoptosis and inflammatory biomarker profiles that distinguish them from each other and healthy controls. The utilization of those unique biomarker profiles for monitoring disease progression or identifying individuals who may benefit from novel immunotherapies such as anti-PD-L1 or anti-PD-1 checkpoint inhibitors appears promising and warrants further investigation.

Improvement in Hepatic Fibrosis Biomarkers Associated With Chemokine Receptor Inactivation Through Mutation or Therapeutic Blockade.

BACKGROUND: The C-C chemokine receptor Type 5 (CCR5) is a key receptor for human immunodeficiency virus type 1 (HIV-1) entry into T-cells and a variant allele, CCR5 delta-32, is associated with decreased viral replication and disease progression. Active HIV-1 replication is highly associated with accelerated rates of hepatic fibrosis. We postulated that CCR5 plays a role in the development of hepatic fibrosis and evaluated the longitudinal effect of natural or drug-induced CCR5 mutation and blockade on biomarkers of liver fibrosis in HIV-1 patients. METHODS: To accomplish this goal, we examined 2 distinct cohorts. First, we evaluated fibrosis markers in the Multicenter Hemophilia Cohort Studies (MHCS), which included subjects with HIV and hepatitis C virus (HCV) coinfection with the CCR5 delta-32 allele. We also evaluated an HIV-1 infected cohort that was treated with a dual CCR5/CCR2 antagonist, cenicriviroc. The enhanced liver fibrosis (ELF) index was validated against liver histology obtained from HCV/HIV and HCV patients and demonstrated strong correlation with fibrosis stage. RESULTS: In both the MHCS patients and patients treated with cenicriviroc, CCR5 mutation or blockade was associated with a significant decrease in the ELF index. Among the patients with the delta-32 allele, the ELF index rate significantly decreased in sequential samples as compared to CCR5 wild-type patients (P = .043). This was not observed in control subjects treated with efavirenz nor with a lower dose of 100 mg cenicriviroc. CONCLUSION: These findings suggest that hepatic fibrosis in HIV-1 infected patients can be modulated by the mutation of CCR5 and/or use of CCR5/CCR2 blockade agents. CLINICAL TRIALS REGISTRATION: NCT01338883.

Association between IL28B rs12979860 single nucleotide polymorphism and the frequency of colonic Treg in chronically HCV-infected patients.

The IL28B gene is associated with spontaneous or treatment-induced HCV viral clearance. However, the mechanism by which the IL28B single nucleotide polymorphism (SNP) affects the extra-hepatic HCV immune responses and its relationship to HCV pathogenesis have not been thoroughly investigated. To examine the mechanism by which IL28B affects HCV clearance. Forty Egyptian patients with chronic HCV infection receiving an Interferon/ribavirin treatment regimen were enrolled into this study. There were two groups: non-responders (NR; n = 20) and sustained virologic responders (SVR; n = 20). The initial plasma HCV viral loads prior to treatment and IL28B genotypes were determined by quantitative RT-PCR and sequencing, respectively. Liver biopsies were examined to determine the inflammatory score and the stage of fibrosis. Colonic regulatory T cell (Treg) frequency was estimated by immunohistochemistry. No significant association between IL28B genotypes and response to therapy was identified, despite an odds ratio of 3.4 to have the TT genotype in NR compared to SVR (95 % confidence interval 0.3-35.3, p = 0.3). Patients with the TT-IL28Brs12979860 genotype (unfavorable genotype) have significantly higher frequencies of colonic Treg compared to the CT (p = 0.04) and CC (p = 0.03) genotypes. The frequency of colonic Treg cells in HCV-infected patients had a strong association with the IL-28B genotype and may have a significant impact on HCV clearance.

Extra-hepatic infection of hepatitis C virus in the colon tissue and its relationship with hepatitis C virus pathogenesis.

Extra-hepatic compartments might contribute to hepatitis C virus (HCV) persistence and extra-hepatic manifestations. Therefore, we investigated HCV infection in colonic tissue in patients with chronic hepatitis C (CHC) and its relationship with HCV pathogenesis. Colonic biopsies were collected from three groups with CHC infection: treatment naïve (TN; n=12), non-responders (NR; n=10) to anti-HCV therapy (pegylated interferon-α and ribavirin) and sustained virologic response (SVR; n=10) and from a fourth healthy control group (n=10). Liver biopsies were examined to assess inflammation and fibrosis. HCV infection and colonic T regulatory (Treg) frequency were detected by immunohistochemistry. HCV core and NS3 proteins were detected in B cells and macrophage/monocytes of 42 % and 25 % of TN and 50 % and 30 % of NR, respectively, but not in SVR or control group. The numbers of cells expressing HCV proteins were positively correlated with both HCV viral load and colonic Treg frequency. A significant negative correlation between HCV-expressing cells with both liver inflammation and fibrosis was identified. Our study provides evidence that HCV can infect B cells and macrophages of the colon. The correlations between HCV infection in colonic tissue and HCV viral load and liver pathology underline the significance of this extra-hepatic infection in HCV pathogenesis and response to therapy.

Evaluating the Role of Cellular Immune Responses in the Emergence of HCV NS3 Resistance Mutations During Protease Inhibitor Therapy.

The efficacy of protease inhibitor drugs in hepatitis C virus (HCV) treatment is limited by the selection and expansion of drug-resistant mutations. HCV replication is error-prone and genetic variability within the dominant epitopes ensures its persistence. The aims of this study are to evaluate the role of cellular immune response in the emergence of HCV protease resistance mutations and its effects on treatment outcome. Ten chronically HCV-infected subjects were treated with boceprevir (BOC)-based triple therapy. HCV-RNA was tested for BOC resistance-associated viral variants. HCV protease resistance mutations were investigated pretreatment and 24 weeks post-treatment. Synthetic peptides representing the wild-type and the potential nonstructural (NS)3 variants were used to evaluate T cell responses and human leukocyte antigen binding. Sustained viral response was achieved in 70% of patients, two patients were treatment nonresponders (NRs) and one was classified as a relapse. Pretreatment, the proportion of drug-resistant variants within individuals was higher in sustained viral responders (SVRs) than in NR patients. However, resistance-associated variants increased in NRs after BOC combined triple therapy. In contrast to NR patients, significant stronger cell-mediated immune responses were observed at the baseline among those who achieved sustained viral response for all T cell epitopes tested. Despite the increase in cell-mediated immune responses at week 24 in NRs, they failed to control the virus replication, leading to development of overt drug-resistant variants. Our data suggest that strong NS3-specific T cell immune responses at the baseline may predict a positive outcome of directly acting antiviral-based therapy, and the presence of pre-existent resistance mutations does not play a significant role in the outcome of anti-HCV combined therapy.

HIV-Induced Epigenetic Alterations in Host Cells.

Human immunodeficiency virus (HIV), a member of the Retroviridae family, is a positive-sense, enveloped RNA virus. HIV, the causative agent of acquired immunodeficiency syndrome (AIDS) has two major types, HIV-1 and HIV-2 In HIV-infected cells the single stranded viral RNA genome is reverse transcribed and the double-stranded viral DNA integrates into the cellular DNA, forming a provirus. The proviral HIV genome is controlled by the host epigenetic regulatory machinery. Cellular epigenetic regulators control HIV latency and reactivation by affecting the chromatin state in the vicinity of the viral promoter located to the 5' long terminal repeat (LTR) sequence. In turn, distinct HIV proteins affect the epigenotype and gene expression pattern of the host cells. HIV-1 infection of CD4(+) T cells in vitro upregulated DNMT activity and induced hypermethylation of distinct cellular promoters. In contrast, in the colon mucosa and peripheral blood mononuclear cells from HIV-infected patients demethylation of the FOXP3 promoter was observed, possibly due to the downregulation of DNA methyltransferase 1. For a curative therapy of HIV infected individuals and AIDS patients, a combination of antiretroviral drugs with epigenetic modifying compounds have been suggested for the reactivation of latent HIV-1 genomes. These epigenetic drugs include histone deacetylase inhibitors (HDACI), histone methyltransferase inhibitors (HMTI), histone demethylase inhibitors, and DNA methyltransferase inhibitors (DNMTI).

Compartmentalized accumulation of cAMP near complexes of multidrug resistance protein 4 (MRP4) and cystic fibrosis transmembrane conductance regulator (CFTR) contributes to drug-induced diarrhea.

Diarrhea is one of the most common adverse side effects observed in ∼7% of individuals consuming Food and Drug Administration (FDA)-approved drugs. The mechanism of how these drugs alter fluid secretion in the gut and induce diarrhea is not clearly understood. Several drugs are either substrates or inhibitors of multidrug resistance protein 4 (MRP4), such as the anti-colon cancer drug irinotecan and an anti-retroviral used to treat HIV infection, 3'-azido-3'-deoxythymidine (AZT). These drugs activate cystic fibrosis transmembrane conductance regulator (CFTR)-mediated fluid secretion by inhibiting MRP4-mediated cAMP efflux. Binding of drugs to MRP4 augments the formation of MRP4-CFTR-containing macromolecular complexes that is mediated via scaffolding protein PDZK1. Importantly, HIV patients on AZT treatment demonstrate augmented MRP4-CFTR complex formation in the colon, which defines a novel paradigm of drug-induced diarrhea.

Association of colonic regulatory T cells with hepatitis C virus pathogenesis and liver pathology.

BACKGROUND AND AIM: Forkhead box protein P3 (FoxP3)(+) regulatory T (Treg ) cells play a fundamental role in maintaining the balance between the tissue-damaging and protective immune response to chronic hepatitis C (CHC) infection. Herein, we investigated the frequency of Treg cells in the colon and their potential relationship to the various CHC outcomes and hepatic histopathology. METHODS: Colonic biopsies were collected from three groups with CHC: treatment naïve (TN; n = 20), non-responders (NR; n = 20), sustained virologic response (SVR; n = 20), and a fourth healthy control group (n = 10). The plasma viral loads and cytokines levels were determined by quantitative real-time polymerase chain reaction, and ELISA, respectively. Liver biopsies were examined to assess inflammatory score and fibrosis stage. Colonic Treg frequency was estimated by immunohistochemistry using confocal microscopy. RESULTS: A significant increase in the frequency of colonic Treg was found in TN, and NR groups compared with the control and SVR group. The frequency of colonic Treg , plasma interleukin (IL)-10 and IL-4 levels were significantly positively correlated with viral load and negatively correlated with METAVIR inflammatory score, and fibrosis stages. CONCLUSION: Colonic Treg cells are negatively correlated with liver inflammation and hepatitis C virus (HCV) viral load, which suggests a strong linkage between gut-derived Treg cell populations and HCV infection.

Modulation of HCV replication after combination antiretroviral therapy in HCV/HIV co-infected patients.

The hepatitis C virus (HCV) is an important contributor to morbidity and mortality in patients co-infected with HIV. Co-infection results in increased HCV replication and more rapid rates of liver disease progression. The effect of HIV combination antiretroviral therapy (cART) on HCV replication has not been studied in depth. To address this issue, we enrolled a small cohort of HCV/HIV co-infected patients into a cART initiation trial and used dynamic modeling combined with evaluation of immune responses and microarray profiles to determine how effective treatment of HIV affects HCV. Treatment with cART resulted in increased HCV replication and increased alanine aminotransferase (ALT) in a subset of patients. Subjects with evidence of hepatic injury (increased ALT) were more likely to have HCV-specific immune responses directed against HCV epitopes. Over time, HCV viral loads declined. Reproducible and biologically important gene expression changes occurred in co-infected patients who underwent successful cART. The effective suppression of HIV by cART initiated a cascade of early and late events in treated patients. Early events involving down-regulation of interferon-stimulated genes may have led to transiently increased viral replication and hepatic injury. At later time points, HCV viral load declined to levels comparable to those seen in the setting of HCV monoinfection. These findings support early antiretroviral therapy in those with HCV/HIV co-infection.

The protective effect of Physalis peruviana L. against cadmium-induced neurotoxicity in rats.

The present study was carried out to investigate the protective effect of Physalis peruviana L. (family Solanaceae) against cadmium-induced neurotoxicity in rats. Adult male Wistar rats were randomly divided into four groups. Group 1 was used as control. Group 2 was intraperitoneally injected with 6.5 mg/kg bwt of cadmium chloride for 5 days. Group 3 was treated with 200 mg/kg bwt of methanolic extract of Physalis (MEPh). Group 4 was pretreated with MEPh 1 h before cadmium for 5 days. Cadmium treatment induced marked disturbances in neurochemical parameters as indicating by significant (p < 0.05) reduction in dopamine (DA), serotonin (5-HT), and 5-hydroxyindoleacetic acid (5-HIAA) in cerebellum, hippocampus, and cerebral cortex and enhanced significantly (p < 0.05) the levels of lipid peroxidation and nitric oxide in the brain. Cadmium treatment also decreased the amount of nonenzymatic and enzymatic antioxidants significantly (p < 0.05). Pretreatment with MEPh resulted in significant (p < 0.05) decreases in lipid peroxidation and nitric oxide levels and restored the amount of glutathione successfully. Although, preadministration of MEPh also brought the activities of cellular antioxidant enzymes, namely superoxide dismutase, catalase, glutathione peroxidase, and glutathione reductase significantly (p < 0.05) to the control levels, as well as the levels of Ca(2+), Cl(-), DA, 5-HT, and serotonin metabolite, 5-HIAA. These data indicated that Physalis has a beneficial effect in ameliorating the cadmium-induced oxidative neurotoxicity in the brain of rats.

Immune activation in HIV/HCV-infected patients is associated with low-level expression of liver expressed antimicrobial peptide-2 (LEAP-2).

BACKGROUND: Immune activation is one of the main features of HIV/Hepatitis C virus (HCV) infections and has been linked to the disturbance of the gut-associated lymphoid tissue (GALT). In chronic HIV infection, loss of GALT integrity results in translocation of microbial products and chronic immune activation. We explored the relationship between bacterial translocation and specific colonic proteins, including liver expressed antimicrobial peptide (LEAP 2) which may play a role in modulating the bacterial translocation process. METHODS: A total of 40 subjects (10 HIV/HCV, 10 HIV, 10 HCV-infected patients and 10 controls) were enrolled and underwent serum and colonic tissue sampling. The levels of immune activation were evaluated by measuring plasma sCD27, and the levels of selected proinflammatory, Th2 and regulatory cytokines in both the plasma and supernatant of CD3-stimulated intraepithelial lymphocytes. We also evaluated LEAP-2 expression in the colon biopsies using Affymetrix Human Gene 1.0 ST (HuGene) and fluorescent immunohistochemistry. RESULTS: Increased levels of sCD27 were observed in HIV/HCV coinfected (p=0.03) and HIV monoinfected (p=0.04) patients compared with controls consistent with the presence of immune activation. The chip array identified LEAP-2 expression as a key marker associated with immune activation. LEAP-2 expression in HIV, HCV and HIV/HCV-infected patients was significantly lower compared with controls, and was significantly negatively correlated (p=0.03, r=-0.44) with sCD27. CONCLUSIONS: Our data suggests that HCV and HIV infections are associated with decreased expression of LEAP-2 in colonic tissue. This may represent a key mechanism for enhanced microbial translocation and immune activation in HIV/HCV-infected patients.

Hepatitis C virus-specific cell-mediated immune responses in children born to mothers infected with hepatitis C virus.

OBJECTIVE: To investigate the association between hepatitis C virus (HCV)-specific cell-mediated immunity (CMI) responses and viral clearance in children born to mothers infected with HCV. STUDY DESIGN: A cross-sectional study of children from a mother-infant cohort in Egypt were enrolled to detect CMI responses to recombinant core and nonstructural HCV antigens (nonstructural segments NS3, NS4a/b, and NS5 of the HCV genome) using an interferon-gamma enzyme-linked immunospot assay. Children born to mothers with chronic HCV were enrolled into 3 groups: transiently viremic (n = 5), aviremic (n = 36), and positive control (n = 6), which consisted of 1 child with chronic HCV from this cohort and another 5 children with chronic HCV from a companion study. Children without HCV born to mothers without HCV (n = 27) served as a negative control group. Wilcoxon rank sum test was used to compare the magnitude of CMI responses between groups. RESULTS: None of the 6 control children who were positive for HCV responded to any HCV antigen, and 4 (80%) of 5 children with transient viremia responded to at least one HCV antigen, compared with 5 (14%) of 36 and 3 (11%) of 27 children in the aviremic and negative control groups, respectively. Children with transient viremia elicited stronger responses than did negative controls (P = .005), positive controls (P = .011), or children without HCV viremia (P = .012), particularly to nonstructural antigens. CONCLUSIONS: HCV-specific CMI responses were significantly higher in magnitude and frequency among transiently infected children compared with those persistently infected. This suggests CMI responses may be associated with past viral clearance and can identify children at high risk of infection, who can be targeted for health education, screening, and follow-up.

Th17 cells: interactions with predisposing factors in the immunopathogenesis of inflammatory bowel disease.

Inflammatory bowel disease (IBD) is a chronic inflammatory state of the GI tract of unknown etiology. Classically, tissue injury in IBD is thought to be primarily mediated by Th1 cells in Crohn's disease or Th2 cells in ulcerative colitis. The discoveries of new subsets of T-helper cells, especially Th17 cells, have revolutionized our understanding of the disease immunopathology. Th17 cells seem to affect both innate and adaptive immune responses by the release of regulatory cytokines. Understanding the role of Th17 cells in IBD pathogenesis and targeting their regulatory cytokines may provide potential therapeutic approaches for the treatment of IBD in the future.

Evidence for protection against chronic hepatitis C virus infection in chimpanzees by immunization with replicating recombinant vaccinia virus.

Given the failures of nonreplicating vaccines against chronic hepatitis C virus (HCV) infection, we hypothesized that a replicating viral vector may provide protective immunity. Four chimpanzees were immunized transdermally twice with recombinant vaccinia viruses (rVV) expressing HCV genes. After challenge with 24 50% chimpanzee infective doses of homologous HCV, the two control animals that had received only the parental VV developed chronic HCV infection. All four immunized animals resolved HCV infection. The difference in the rate of chronicity between the immunized and the control animals was close to statistical significance (P = 0.067). Immunized animals developed vigorous gamma interferon enzyme-linked immunospot responses and moderate proliferative responses. To investigate cross-genotype protection, the immunized recovered chimpanzees were challenged with a pool of six major HCV genotypes. During the acute phase after the multigenotype challenge, all animals had high-titer viremia in which genotype 4 dominated (87%), followed by genotype 5 (13%). However, after fluctuating low-level viremia, the viremia finally turned negative or persisted at very low levels. This study suggests the potential efficacy of replicating recombinant vaccinia virus-based immunization against chronic HCV infection.

Attempted therapeutic immunization in a chimpanzee chronic HBV carrier with a high viral load.

BACKGROUND: We previously reported successful therapeutic immunization in a chimpanzee having a relatively low viral load, which was immunized with recombinant plasmid hepatitis B surface antigen (HBsAg) DNA and boosted with recombinant HBsAg encoding canarypox virus. In the present study, we attempted to confirm these findings in an animal with a high virus load. METHODS AND RESULTS: We tested three immunization strategies successively over a 3-year period. In the first of these, we administered four monthly injections of DNA encoding HBsAg + PreS2 + hepatitis B core antigen (HBcAg) + DNA encoding interleukin (IL)-12, (given 3 days later), and boosted with canarypox expressing all of the above HBV genes 6 months after initial immunization. No reduction in viral load was observed. In the second trial, we administered lamivudine for 8 weeks, and then began monthly DNA-based immunization with plasmids expressing the above viral genes; however, viral loads rebounded 1 week after termination of lamivudine therapy. In a third trial, we continued lamivudine therapy for 30 weeks and immunized with vaccinia virus expressing the above viral genes 18 and 23 weeks after the start of lamivudine therapy. Again viral loads rebounded shortly after cessation of lamivudine treatment. Analysis of cell-mediated immune responses, and their avidity, revealed that DNA-based immunization produced the strongest enhancement of high avidity T-cell responses, while recombinant vaccinia immunization during lamivudine therapy enhanced low avidity responses only. The strongest low and high avidity responses were directed to the middle surface antigen. CONCLUSIONS: Three strategies for therapeutic immunization failed to control HBV viremia in a chronically infected chimpanzee with a high viral load.

gC1qR expression in chimpanzees with resolved and chronic infection: potential role of HCV core/gC1qR-mediated T cell suppression in the outcome of HCV infection.

Chimpanzee is a unique animal model for HCV infection, in which about 50% of infections resolve spontaneously. It has been reported that the magnitude of T cell responses to HCV core in recovered chimpanzees is greater than that in chronically infected ones. However, the mechanism(s) by which the chimpanzees with resolved infection overcome core-mediated immunosuppression remains unknown. In this study, we examined the effect of HCV core on T cell responsiveness in chimpanzees with resolved and chronic HCV infection. We found that core protein strongly inhibited T cell activation and proliferation in chimpanzees with chronic infection, while this inhibition was limited in chimpanzees with resolved infection. Notably, the level of gC1qR, as well as the binding of core protein, on the surface of T cells was lower in recovered chimpanzees when compared to chimpanzees with chronic HCV infection. Intriguingly, the observed differences in gC1qR expression levels and susceptibility to core-induced suppression amongst HCV-chronically infected and recovered chimpanzees were observed prior to HCV challenge, suggesting a possible genetic determination of the outcome of infection. These findings suggest that gC1qR expression on the surface of T cells is crucial for HCV core-mediated T cell suppression and viral clearance, and that represents a novel mechanism by which a virus usurps host machinery for persistence.