T lymphocytes from chronic HCV-infected patients are primed for activation-induced apoptosis and express unique pro-apoptotic gene signature

Extracellular vesicle storm during the course of Ebola virus infection in primates

Introduction

Ebola virus (EBOV) is an RNA virus of the Filoviridae family that is responsible for outbreaks of hemorrhagic fevers in primates with a lethality rate as high as 90%. EBOV primarily targets host macrophages leading to cell activation and systemic cytokine storm, and fatal infection is associated with an inhibited interferon response, and lymphopenia. The EBOV surface glycoprotein (GP) has been shown to directly induce T cell depletion and can be secreted outside the virion via extracellular vesicles (EVs), though most studies are limited to epithelial cells and underlying mechanisms remain poorly elucidated.

Methods

To assess the role of GP on EBOV-induced dysregulation of host immunity, we first utilized EBOV virus-like particles (VLPs) expressing VP40 and NP either alone (Bald-VLP) or in conjunction with GP (VLP-GP) to investigate early inflammatory responses in THP-1 macrophages and in a murine model. We then sought to decipher the role of non-classical inflammatory mediators such as EVs over the course of EBOV infection in two EBOV-infected rhesus macaques by isolating and characterizing circulatory EVs throughout disease progression using size exclusion chromatography, nanoparticle tracking-analysis, and LC-MS/MS.

Results

While all VLPs could induce inflammatory mediators and recruit small peritoneal macrophages, pro-inflammatory cytokine and chemokine gene expression was exacerbated by the presence of GP. Further, quantification of EVs isolated from infected rhesus macaques revealed that the concentration of vesicles peaked in circulation at the terminal stage, at which time EBOV GP could be detected in host-derived exosomes. Moreover, comparative proteomics conducted across EV populations isolated from serum at various time points before and after infection revealed differences in host-derived protein content that were most significantly pronounced at the endpoint of infection, including significant expression of mediators of TLR4 signaling.

Discussion

These results suggest a dynamic role for EVs in the modification of disease states in the context of EBOV. Overall, our work highlights the importance of viral factors, such as the GP, and host derived EVs in the inflammatory cascade and pathogenesis of EBOV, which can be collectively further exploited for novel antiviral development.

Distribution of hepatitis C virus genotype and subtype between Mongolian and Han in Inner Mongolia

Hepatitis C is a serious infectious disease caused by the hepatitis C virus (HCV). HCV genotypes (GT) and subtypes are closely related to geographical distribution. Studies on the distribution of HCV genotypes can help to understand the regional epidemiology and genotype distribution and provide benefits in the treatment for hepatitis C. To provide information about the distribution of HCV genotypes as well as improved prevention and treatment of hepatitis C, we aimed to classify the distribution of HCV genotypes among Mongolian and Han patients with hepatitis C in Inner Mongolia over the past 5 years. Peripheral blood samples of patients with HCV were collected for gene sequencing. To analyze the HCV genotype distribution and possible influencing factors, we determined the viral load and ratios of various genotypes. We found that the most prevalent genotype in Inner Mongolia was 1b, followed by GT2a, GT3a, GT3b, and GT6a. The prevalence of HCV among Mongolian patients was significantly higher than the prevalence in their Han counterparts (χ2 = 16.64, P = .000). There was no significant difference in viral load according to sex among HCV genotypes. However, the viral load of GT 1b was significantly higher than that of GT 2a (F = 3.51, P = .008). The viral load of GT 1b among ethnic Mongolians was significantly higher than that among Han patients (t = 2.28, P = .044). The present study's findings can serve as a basis for developing a personalized treatment for hepatitis C among patients in Inner Mongolia.

Kidney transplant from hepatitis C viremic donors into aviremic recipients and risk for post-transplant BK and CMV infection

BACKGROUND

kidney transplantation from HCV-viremic donors to uninfected recipients is associated with excellent short-term outcomes. However, HCV viremia might be associated with an increased risk for post-transplant viral complications.

METHODS

We designed a retrospective study of HCV-negative kidney-only transplant recipients between 2018 and 2020. Recipients were grouped into group 1; HCV-negative donors, and group 2; HCV-viremic donors. Patients were matched 1:1 using propensity score. Primary objectives were to compare the incidence of CMV viremia ≥ 200 ml/IU, and BK viremia ≥1000 copies/ml between the groups. Secondary outcomes included group comparison of CMV disease, BK viremia ≥10,000 copies/ml, and one year patient and allograft survival.

RESULTS

The study included 634 patients in group 1, and 71 patients in group 2. 65 pairs of patients were matched. Incidence of CMV viremia (33.3% vs 40.0%, p = 0.4675), and BK viremia (15.9% vs 27.7%, P = 0.1353) did not differ significantly between groups in the matched cohort. Incidence of CMV disease (81.0% Vs 76.9%; p = 1.000), and BK viremia ≥10,000 copies/ml (9.5% vs 16.9%, p = 0.2987) were comparable between groups. There was no difference in the one-year patient or allograft survival between groups.

CONCLUSION

kidney transplant from HCV-viremic donors is not associated with increased risk for BK or CMV viremia. This article is protected by copyright. All rights reserved.

RNA-binding protein RBM47 stabilizes IFNAR1 mRNA to potentiate host antiviral activity

The type I interferon (IFN-I, IFN-α/β)-mediated immune response is the first line of host defense against invading viruses. IFN-α/β binds to IFN-α/β receptors (IFNARs) and triggers the expression of IFN-stimulated genes (ISGs). Thus, stabilization of IFNARs is important for prolonging antiviral activity. Here, we report the induction of an RNA-binding motif-containing protein, RBM47, upon viral infection or interferon stimulation. Using multiple virus infection models, we demonstrate that RBM47 has broad-spectrum antiviral activity in vitro and in vivo. RBM47 has no noticeable impact on IFN production, but significantly activates the IFN-stimulated response element (ISRE) and enhances the expression of interferon-stimulated genes (ISGs). Mechanistically, RBM47 binds to the 3'UTR of IFNAR1 mRNA, increases mRNA stability, and retards the degradation of IFNAR1. In summary, this study suggests that RBM47 is an interferon-inducible RNA-binding protein that plays an essential role in enhancing host IFN downstream signaling.

Transcriptional insights into the CD8+ T cell response in mono-HIV and HCV infection

Background

Disease progression in the absence of therapy varies significantly in mono-HIV and HCV infected individuals. Virus-specific CD8⁺ T cells play an important role in restricting lentiviral replication and determining the rate of disease progression during HIV and HCV mono- and co-infection. Thus, understanding the similarities in the characteristics of CD8⁺ T cells in mono-HIV and HCV infection at the transcriptomic level contributes to the development of antiviral therapy. In this study, a meta-analysis of CD8⁺ T cell gene expression profiles derived from mono-HIV and HCV infected individuals at different stages of disease progression, was conducted to understand the common changes experienced by CD8⁺ T cells.

Methods

Five microarray datasets, reporting CD8⁺ T cell mRNA expression of the mono-HIV and HCV infected patients, were retrieved from Gene Expression Omnibus (GEO). Differentially expressed genes (DEGs) were identified via integrative meta-analysis of expression data (INMEX) program. Network analysis methods were used to assess protein–protein interaction (PPI) networks, Gene Ontology (GO) terms and pathway enrichment for DEGs. MirDIP and miRDB online prediction tools were used to predict potential microRNAs (miRNAs) targeting hub genes.

Results

First, we identified 625 and 154 DEGs in the CD8⁺ T cells originating from mono-HIV and HCV chronic progressor patients, respectively, compared to healthy individuals. Among them, interferon-stimulated genes (ISGs) including ISG15, IFIT3, ILI44L, CXCL8, FPR1 and TLR2, were upregulated after mono-HIV and HCV infection. Pathway enrichment analysis of DEGs showed that the “cytokine–cytokine receptor interaction” and “NF-kappa B” signaling pathways were upregulated after mono-HIV and HCV infection. In addition, we identified 92 and 50 DEGs in the CD8⁺ T cells of HIV non-progressor and HCV resolver patients, respectively, compared with corresponding chronic progressors. We observed attenuated mitosis and reduced ISG expression in HIV non-progressors and HCV resolvers compared with the corresponding chronic progressors. Finally, we identified miRNA-143-3p, predicted to target both IFIT3 in HIV and STAT5A in HCV infection.

Conclusions

We identified DEGs and transcriptional patterns in mono-HIV and HCV infected individuals at different stages of disease progression and identified miRNA-143-3p with potential to intervene disease progression, which provides a new strategy for developing targeted therapies.

Direct-Acting Antiviral Treatment of HCV Infection Does Not Resolve the Dysfunction of Circulating CD8+ T-Cells in Advanced Liver Disease

Chronic hepatitis C virus (HCV) infection disrupts immune functions, including that of cytotoxic CD8⁺ T-cells which are important mediators of immune response. While HCV cure aims to eliminate long term sequelae of infection, whether direct-acting antiviral (DAA) treatment results in immune reconstitution remains unclear. We and others have reported generalized CD8⁺ T-cell dysfunction in chronic HCV infection and our research suggests that the degree of liver damage is a factor in this process. Our recent research indicates that liver fibrosis is not readily reversed after DAA-mediated clearance of chronic HCV infection. We therefore examined the function of circulating CD8⁺ T-cell subsets in chronic HCV infection in the context of liver fibrosis severity, determined by ultrasound elastography and Metavir F-score system. We observed progressive shifts in CD8⁺ T-cell subset distribution in HCV-infected individuals with advanced liver fibrosis (F4) compared to minimal fibrosis (F0-1) or uninfected controls, and this remained unchanged after viral cure. Impaired CD8⁺ T-cell function was observed as a reduced proportion of CD107⁺ and perforin⁺ late effector memory cells in HCV⁺(F4) and HCV⁺(F0-1) individuals, respectively. In HCV⁺(F4) individuals, nearly all CD8⁺ T-cell subsets had an elevated proportion of perforin⁺ cells while naïve cells had increased proportions of IFN-γ⁺ and CD107⁺ cells. These exaggerated CD8⁺ T-cell activities were not resolved when evaluated 24 weeks after completion of DAA therapy and HCV clearance. This was further supported by sustained, high levels of cell proliferation and cytolytic activity. Furthermore, DAA therapy had no effect on elevated concentrations of systemic inflammatory cytokines and decreased levels of inhibitory TGF-β in the plasma of HCV⁺(F4) individuals, suggesting HCV infection and advanced liver disease result in a long-lasting immune activating microenvironment. These data demonstrate that in chronic HCV infection, liver fibrosis severity is associated with generalized hyperfunctional CD8⁺ T-cells, particularly with perforin production and cytotoxicity, and this persists after viral clearance. Whether DAA therapy will eliminate other related long-term sequelae in HCV⁺(F4) individuals remains an important research question.

Hepatitis C virus core protein reduces CD8+ T-cell proliferation, perforin production and degranulation but increases STAT5 activation

Clearance of hepatitis C virus (HCV) is dependent on an effective virus-specific CD8+ T-cell response, which is dysfunctional in chronic HCV infection. Dysfunction in bulk or non-HCV-specific CD8+ T-cells in HCV infection has also been observed. This may contribute to observed reductions in immunity to other diseases (e.g. cancer, viral co-infections) in HCV-infected individuals. Evidence suggests that the HCV core protein (found in blood as free protein) may contribute to this impairment. To determine if HCV core contributes to the impairment of effector functions and survival potential of CD8+ T-cells, isolated human CD8+ T-cells from healthy donors were pre-incubated with recombinant HCV core protein for 72 hr and then stimulated in vitro to evaluate proliferation, survival potential and effector functions. Pre-incubation of stimulated CD8+ T-cells with HCV core significantly reduced their proliferation. Perforin production and degranulation were also decreased, but interferon-γ production was unchanged. Additionally, when CD8+ T-cells were treated with serum from HCV+ individuals, they produced less perforin than cells treated with healthy serum. Up-regulation of anti-apoptotic Bcl-2 was slightly lower in cells treated with HCV core, but signal transducer and activator of transcription 5 (STAT5) activation was increased, suggesting dysregulation downstream of STAT activation. Our study reveals that HCV core reduces the activity and target lysis-associated functions of CD8+ T-cells. This may contribute to the generalized impairment of CD8+ T-cells observed in HCV infection. These findings provide insight for the design of novel counteractive immune-mediated strategies including the design of effective therapeutic vaccines for use in HCV+ individuals.

Expression of PBMC apoptosis-related factors in patients with chronic hepatitis B and their relationships with clinical prognosis

The present study was conducted to investigate the expression of apoptosis-related factors in peripheral blood mononuclear cells (PBMC) of patients with chronic hepatitis B and their correlation to clinical prognosis. Sixty-two patients that were diagnosed with chronic hepatitis B were admitted to Xuzhou Hospital from March 2015 to February 2016 and were enrolled as the observation group, while 60 healthy subjects who were examined in the health examination center were selected as the control group. The PBMC of patients were collected, and mRNA expression levels of the apoptotic molecules (FAS, CASP3, CASP8 and CASP9) were measured using real-time fluorescence quantitative PCR. The protein expression levels of apoptosis-related genes in the plasma were detected using enzyme-linked immunosorbent assay (ELISA) and the serum HBV-DNA was quantitatively measured using real-time fluorescence quantitative PCR. The mRNA and protein expression levels of FAS, CASP3, CASP8 and CASP9 in the observation group were significantly higher than those in the control group (P<0.05). The positive rate and log value of the copy amount of HBV DNA in the observation group were significantly higher than those in the control group (P<0.05). The Pearson correlation coefficient analysis showed that FAS, CASP3, CASP8 and CASP9 were positively correlated with HBV DNA (P<0.05). The mRNA expression levels of FAS, CASP3, CASP8 and CASP9 in patients with negative HBV-DNA were significantly lower than those with positive HBV-DNA (P<0.05). Apoptosis of PBMCs play an important role in the occurrence and development of chronic hepatitis B, and is closely correlated to the level of serum virus replication and prognosis.

Unexpected evolutionarily conserved rapid effects of viral infection on oxytocin receptor and TGF-β/pSmad3

Background

shRNA lentiviral vectors are extensively used for gene knockdowns in mammalian cells, and non-target shRNAs typically are considered the proper experimental control for general changes caused by RNAi. However, the effects of non-target lentivirus controls on the modulation of cell signaling pathways remain largely unknown. In this study, we evaluated the effect of control lentiviral transduction on oxytocin receptor (OXTR) expression through the ERK/MAPK pathway in mouse and human skeletal muscle cells, on myogenic activity, and in vivo on mouse muscle regeneration. Furthermore, we mined published data for the influence of viral infections on OXTR levels in human populations and found that unrelated viral pathologies have a common consequence: diminished levels of OXTR.

Methods

We examined the change in OXTR mRNA expression upon transduction with control and Smad3-targeting viral vectors through real time RT-PCR and Western blotting, and confirmed with immunofluorescence. Changes in Smad3 and OXTR expression were examined both in vitro with mouse and human myoblasts and in vivo in mouse satellite cells. The general effects of viral infections on OXTR downregulation in humans were also examined by analyzing published Gene Expression Omnibus (GEO) datasets. The change in myoblast myogenic activity caused by the viral transduction (the percent of Pax7 + Ki67+ cells) was examined by immunofluorescence.

Results

Results shown in this work establish that lentiviral control vectors significantly downregulate OXTR expression at mRNA and protein levels and diminish key downstream effectors of OXTR, ERK signaling, reducing the myogenic proliferation of infected cells. This effect is evolutionarily conserved between mouse and human myogenic cells, and it manifests in satellite cells after control lentiviral transduction of mice in vivo. Furthermore, an examination of published datasets uncovered similar OXTR downregulation in humans that are afflicted with different viral infections. Additionally, cells transduced with Smad3-targeting shRNA downregulate OXTR even more than cells transduced with control viruses.

Conclusions

Our work suggests that experimental cohorts transduced with control viruses may not behave the same as un-transduced cells and animals, specifically that control viral vectors significantly change the intensity of key cell-signaling pathways, such as OXTR/ERK. Our results further demonstrate that lentiviral transduction significantly decreases myogenic proliferation and suggest that viral infections in general may play a role in decreasing muscle health and regeneration, a decline in metabolic health, and a lower sense of well-being, as these rely on effective OXTR signaling. Additionally, our data suggest pathway crosstalk between TGF-β/pSmad3 and OXTR, implying that sustained attenuation of the TGF-β/pSmad3 pathway will reduce pro-regenerative OXTR/pERK signaling.

Electronic supplementary material

The online version of this article (doi:10.1186/s13395-017-0125-y) contains supplementary material, which is available to authorized users.

Hepatitis C virus strategies to evade the specific-T cell response: a possible mission favoring its persistence

Hepatitis C virus (HCV) is a small, enveloped RNA virus. The number of HCV-infected individuals worldwide is estimated to be approximately 200 million. The vast majority of HCV infections persist, with up to 80% of all cases leading to chronic hepatitis associated with liver fibrosis, cirrhosis, and hepatocellular carcinoma. The interaction between HCV and the host have a pivotal role in viral fitness, persistence, pathogenicity, and disease progression. The control of HCV infection requires both effective innate and adaptive immune responses. The HCV clearance during acute infection is associated with an early induction of the innate and a delayed initiation of the adaptive immune responses. However, in the vast majority of acute HCV infections, these responses are overcome and the virus persistence almost inexorably occurs. Recently, several host- and virus-related mechanisms responsible for the failure of both the innate and the adaptive immune responses have been recognized. Among the latter, the wide range of escape mutations to evade the specific-T-and B-cell responses as well as the T cell anergy and the CD8+ T cell exhaustion together with the interference with its function after prolonged virus exposure hold a pivotal role. Other HCV strategies include the modification or manipulation of molecules playing key roles in the induction of the interferon response and its induced effector proteins. In this review, we attempt to gain insights on the main T cell immune evasion strategies used by the virus in order to favor its persistence.

Generalized Liver- and Blood-Derived CD8+ T-Cell Impairment in Response to Cytokines in Chronic Hepatitis C Virus Infection

Generalized CD8⁺ T-cell impairment in chronic hepatitis C virus (HCV) infection and the contribution of liver-infiltrating CD8⁺ T-cells to the immunopathogenesis of this infection remain poorly understood. It is hypothesized that this impairment is partially due to reduced CD8⁺ T-cell activity in response to cytokines such as IL-7, particularly within the liver. To investigate this, the phenotype and cytokine responsiveness of blood- and liver-derived CD8⁺ T-cells from healthy controls and individuals with HCV infection were compared. In blood, IL-7 receptor α (CD127) expression on bulk CD8⁺ T-cells in HCV infection was no different than controls yet was lower on central memory T-cells, and there were fewer naïve cells. IL-7-induced signalling through phosphorylated STAT5 was lower in HCV infection than in controls, and differed between CD8⁺ T-cell subsets. Production of Bcl-2 following IL-7 stimulation was also lower in HCV infection and inversely related to the degree of liver fibrosis. In liver-derived CD8⁺ T-cells, STAT5 activation could not be increased with cytokine stimulation and basal Bcl-2 levels of liver-derived CD8⁺ T-cells were lower than blood-derived counterparts in HCV infection. Therefore, generalized CD8⁺ T-cell impairment in HCV infection is characterized, in part, by impaired IL-7-mediated signalling and survival, independent of CD127 expression. This impairment is more pronounced in the liver and may be associated with an increased potential for apoptosis. This generalized CD8⁺ T-cell impairment represents an important immune dysfunction in chronic HCV infection that may alter patient health.

Genome-wide analysis of the transcriptional response to porcine reproductive and respiratory syndrome virus infection at the maternal/fetal interface and in the fetus

Background

Porcine Reproductive and Respiratory Syndrome Virus (PRRSV) infection of pregnant pigs can result in congenital infection and ultimately fetal death. Little is known about immune responses to infection at the maternal-fetal interface and in the fetus itself, or the molecular events behind virus transmission and disease progression in the fetus. To investigate these processes, RNA-sequencing of two sites, uterine endothelium with adherent placental tissue and fetal thymus, was performed 21 days post-challenge on four groups of fetuses selected from a large PRRSV challenge experiment of pregnant gilts: control (CON), uninfected (UNINF), infected (INF), and meconium-stained (MEC) (n = 12/group). Transcriptional analyses consisted of multiple contrasts between groups using two approaches: differential gene expression analysis and weighted gene co-expression network analysis (WGCNA). Biological functions, pathways, and regulators enriched for differentially expressed genes or module members were identified through functional annotation analyses. Expression data were validated by reverse transcription quantitative polymerase chain reaction (RTqPCR) carried out for 16 genes of interest.

Results

The immune response to infection in endometrium was mainly adaptive in nature, with the most upregulated genes functioning in either humoral or cell-mediated immunity. In contrast, the expression profile of infected fetal thymus revealed a predominantly innate immune response to infection, featuring the upregulation of genes regulated by type I interferon and pro-inflammatory cytokines. Fetal infection was associated with an increase in viral load coupled with a reduction in T cell signaling in the endometrium that could be due to PRRSV-controlled apoptosis of uninfected bystander cells. There was also evidence for a reduction in TWIST1 activity, a transcription factor involved in placental implantation and maturation, which could facilitate virus transmission or fetal pathology through dysregulation of placental function. Finally, results suggested that events within the fetus could also drive fetal pathology. Thymus samples of meconium-stained fetuses exhibited an increase in the expression of pro-inflammatory cytokine and granulocyte genes previously implicated in swine infectious disease pathology.

Conclusions

This study identified major differences in the response to PRRSV infection in the uterine endometrium and fetus at the gene expression level, and provides insight into the molecular basis of virus transmission and disease progression.

Electronic supplementary material

The online version of this article (doi:10.1186/s12864-016-2720-4) contains supplementary material, which is available to authorized users.

Regulation of T cell proliferation by JMJD6 and PDGF-BB during chronic hepatitis B infection

T cell functional exhaustion during chronic hepatitis B virus (HBV) infection may contribute to the failed viral clearance; however, the underlying molecular mechanisms remain largely unknown. Here we demonstrate that jumonji domain-containing protein 6 (JMJD6) is a potential regulator of T cell proliferation during chronic HBV infection. The expression of JMJD6 was reduced in T lymphocytes in chronic hepatitis B (CHB) patients, and this reduction in JMJD6 expression was associated with impaired T cell proliferation. Moreover, silencing JMJD6 expression in primary human T cells impaired T cell proliferation. We found that JMJD6 promotes T cell proliferation by suppressing the mRNA expression of CDKN3. Furthermore, we have identified platelet derived growth factor-BB (PDGF-BB) as a regulator of JMJD6 expression. PDGF-BB downregulates JMJD6 expression and inhibits the proliferation of human primary T cells. Importantly, the expression levels of JMJD6 and PDGF-BB in lymphocytes from CHB patients were correlated with the degree of liver damage and the outcome of chronic HBV infection treatment. Our results demonstrate that PDGF-BB and JMJD6 regulate T cell function during chronic HBV infection and may provide insights for the treatment strategies for CHB patients.

CD4+ primary T cells expressing HCV-core protein upregulate Foxp3 and IL-10, suppressing CD4 and CD8 T cells

Adaptive T cell responses are critical for controlling HCV infection. While there is clinical evidence of a relevant role for regulatory T cells in chronic HCV-infected patients, based on their increased number and function; mechanisms underlying such a phenomena are still poorly understood. Accumulating evidence suggests that proteins from Hepatitis C virus can suppress host immune responses. We and others have shown that HCV is present in CD4+ lymphocytes from chronically infected patients and that HCV-core protein induces a state of unresponsiveness in the CD4+ tumor cell line Jurkat. Here we show that CD4+ primary T cells lentivirally transduced with HCV-core, not only acquire an anergic phenotype but also inhibit IL-2 production and proliferation of bystander CD4+ or CD8+ T cells in response to anti-CD3 plus anti-CD28 stimulation. Core-transduced CD4+ T cells show a phenotype characterized by an increased basal secretion of the regulatory cytokine IL-10, a decreased IFN-γ production upon stimulation, as well as expression of regulatory T cell markers, CTLA-4, and Foxp3. A significant induction of CD4+CD25+CD127(low)PD-1(high)TIM-3(high) regulatory T cells with an exhausted phenotype was also observed. Moreover, CCR7 expression decreased in HCV-core expressing CD4+ T cells explaining their sequestration in inflamed tissues such as the infected liver. This work provides a new perspective on de novo generation of regulatory CD4+ T cells in the periphery, induced by the expression of a single viral protein.