Lasting differential gene expression of circulating CD8 T cells in chronic HCV infection with cirrhosis identifies a role for Hedgehog signaling in cellular hyperfunction.

Background: The impact of chronic hepatic infection on antigen non-specific immune cells in circulation remains poorly understood. We reported lasting global hyperfunction of peripheral CD8 T cells in HCV-infected individuals with cirrhosis. Whether gene expression patterns in bulk CD8 T cells are associated with the severity of liver fibrosis in HCV infection is not known. Methods: RNA sequencing of blood CD8 T cells from treatment naïve, HCV-infected individuals with minimal (Metavir F0-1 ≤ 7.0 kPa) or advanced fibrosis or cirrhosis (F4 ≥ 12.5 kPa), before and after direct-acting antiviral therapy, was performed. CD8 T cell function was assessed by flow cytometry. Results: In CD8 T cells from pre-DAA patients with advanced compared to minimal fibrosis, Gene Ontology analysis and Gene Set Enrichment Analysis identified differential gene expression related to cellular function and metabolism, including upregulated Hedgehog (Hh) signaling, IFN-α, -γ, TGF-ß response genes, apoptosis, apical surface pathways, phospholipase signaling, phosphatidyl-choline/inositol activity, and second-messenger-mediated signaling. In contrast, genes in pathways associated with nuclear processes, RNA transport, cytoskeletal dynamics, cMyc/E2F regulation, oxidative phosphorylation, and mTOR signaling, were reduced. Hh signaling pathway was the top featured gene set upregulated in cirrhotics, wherein hallmark genes GLI1 and PTCH1 ranked highly. Inhibition of Smo-dependent Hh signaling ablated the expression of IFN-γ and perforin in stimulated CD8 T cells from chronic HCV-infected patients with advanced compared to minimal fibrosis. CD8 T cell gene expression profiles post-DAA remained clustered with pre-DAA profiles and disparately between advanced and minimal fibrosis, suggesting a persistent perturbation of gene expression long after viral clearance. Conclusions: This analysis of bulk CD8 T cell gene expression in chronic HCV infection suggests considerable reprogramming of the CD8 T cell pool in the cirrhotic state. Increased Hh signaling in cirrhosis may contribute to generalized CD8 T cell hyperfunction observed in chronic HCV infection. Understanding the lasting nature of immune cell dysfunction may help mitigate remaining clinical challenges after HCV clearance and more generally, improve long term outcomes for individuals with severe liver disease.

Clinical and serological predictors of post COVID-19 condition-findings from a Canadian prospective cohort study.

Introduction: More than 3 years into the pandemic, there is persisting uncertainty as to the etiology, biomarkers, and risk factors of Post COVID-19 Condition (PCC). Serological research data remain a largely untapped resource. Few studies have investigated the potential relationships between post-acute serology and PCC, while accounting for clinical covariates. Methods: We compared clinical and serological predictors among COVID-19 survivors with (n = 102 cases) and without (n = 122 controls) persistent symptoms ≥12 weeks post-infection. We selected four primary serological predictors (anti-nucleocapsid (N), anti-Spike, and anti-receptor binding domain (RBD) IgG titres, and neutralization efficiency), and specified clinical covariates a priori. Results: Similar proportions of PCC-cases (66.7%, n = 68) and infected-controls (71.3%, n = 87) tested positive for anti-N IgG. More cases tested positive for anti-Spike (94.1%, n = 96) and anti-RBD (95.1%, n = 97) IgG, as compared with controls (anti-Spike: 89.3%, n = 109; anti-RBD: 84.4%, n = 103). Similar trends were observed among unvaccinated participants. Effects of IgG titres on PCC status were non-significant in univariate and multivariate analyses. Adjusting for age and sex, PCC-cases were more likely to be efficient neutralizers (OR 2.2, 95% CI 1.11-4.49), and odds was further increased among cases to report deterioration in quality of life (OR 3.4, 95% CI 1.64-7.31). Clinical covariates found to be significantly related to PCC included obesity (OR 2.3, p = 0.02), number of months post COVID-19 (OR 1.1, p < 0.01), allergies (OR 1.8, p = 0.04), and need for medical support (OR 4.1, p < 0.01). Conclusion: Despite past COVID-19 infection, approximately one third of PCC-cases and infected-controls were seronegative for anti-N IgG. Findings suggest higher neutralization efficiency among cases as compared with controls, and that this relationship is stronger among cases with more severe PCC. Cases also required more medical support for COVID-19 symptoms, and described complex, ongoing health sequelae. More data from larger cohorts are needed to substantiate results, permit subgroup analyses of IgG titres, and explore for differences between clusters of PCC symptoms. Future assessment of IgG subtypes may also elucidate new findings.

Protocol for co-producing a framework and integrated resource platform for engaging patients in laboratory-based research.

BACKGROUND: Patient engagement in research is the meaningful and collaborative interaction between patients and researchers throughout the research process. Patient engagement can help to ensure patient-oriented values and perspectives are incorporated into the development, conduct, and dissemination of research. While patient engagement is increasingly prevalent in clinical research, it remains relatively unrealized in preclinical laboratory research. This may reflect the nature of preclinical research, in which routine interactions or engagement with patients may be less common. Our team of patient partners and researchers has previously identified few published examples of patient engagement in preclinical laboratory research, as well as a paucity of guidance on this topic. Here we propose the development of a process framework to facilitate patient engagement in preclinical laboratory research. METHODS: Our team, inclusive of researchers and patient partners, will develop a comprehensive, empirically-derived, and stakeholder-informed process framework for 'patient engagement in preclinical laboratory research.' First, our team will create a 'deliberative knowledge space' to conduct semi-structured discussions that will inform a draft framework for preclinical patient engagement. Over the course of several sessions, we will identify actions, activities, barriers, and enablers (e.g. considerations and motivations for patient engagement in preclinical laboratory research, define roles of key players). The resulting draft process framework will be further populated with examples and refined through an international consensus-building Delphi survey with patients, researchers, and other collaborator organizations. We will then conduct pilot field tests to evaluate the framework with preclinical laboratory research groups paired with patient partners. These results will be used to create a refined framework enriched with real-world examples and considerations. All resources developed will be made available through an online repository. DISCUSSION: Our proposed process framework will provide guidance, best practices, and standardized procedures to promote patient engagement in preclinical laboratory research. Supporting and facilitating patient engagement in this setting presents an exciting new opportunity to help realize the important impact that patients can make.

Engaging patients as partners or collaborators in clinical research is becoming more common, but it is still new in preclinical research. Preclinical researchers work in laboratories on cell and animal experiments. They traditionally don't have frequent interactions with patients compared to their clinical research colleagues. Integrating patient engagement in preclinical laboratory research may help ensure that patient perspectives and values are considered. To help preclinical laboratory research align with patient-centred priorities we propose the development of a practical framework. This framework will facilitate patient engagement in preclinical laboratory research. To achieve this, we will first hold in-depth discussions with patient partners, researchers, and other collaborators to understand views on patient engagement in preclinical laboratory research. Together, we will identify key considerations to draft a framework, including motivations for patient engagement in preclinical laboratory research, and defining the roles of those who need to be involved. We will refine the framework through an international survey where we will collect feedback from researchers, patient partners, and other collaborators to make further improvements. The framework will then be tested and refined by preclinical laboratory teams inclusive of patient partners. The finalized framework and other resources to facilitate patient engagement in preclinical laboratory research will be hosted in a 'one-stop-shop' of online resources. Ultimately, this framework will enable partnerships between patients and researchers and provide a roadmap for patient engagement in preclinical laboratory research. This presents an exciting new opportunity for patients and researchers to collaborate and potentially improve translation of laboratory-based research.

No time for complacency: The CoVaRR-Net Biobank is an essential element of laboratory preparedness for infectious disease outbreaks.

The SARS-CoV-2 pandemic highlighted the need for rapid, collaborative, and population-centric research to define health impact, develop health care policies and establish reliable diagnostic and surveillance tests. Critical for these objectives were in-depth clinical data collected in standardized fashion and large numbers of various types of human samples prior and post-viral encounter. As the pandemic evolved with the emergence of new variants of concern (VOCs), access to samples and data from infected and vaccinated individuals were needed to monitor immune durability, the possibility of increased transmissibility and virulence, and vaccine protection against new and emerging VOCs. Therefore, essential to the pandemic response is a strong laboratory and data research component, supported by effective biobanking and data sharing. Critically important to the speed of the research response is the rapid access to biobanked samples. To address critical challenges brought to light by the pandemic, the Coronavirus Variants Rapid Response Network (CoVaRR-Net), funded by the Canadian Institutes of Health Research, was established to coordinate research efforts to provide rapid evidence-based responses to emerging VOCs. The purpose of this paper is to introduce the CoVaRR-Net Biobank and define its contribution to pandemic preparedness.

La pandémie de SRAS-CoV-2 a fait ressortir la nécessité de réaliser des recherches rapides, coopératives et populationnelles pour en définir les effets sur la santé, promulguer des politiques sanitaires et établir des tests diagnostiques et des tests de surveillance fiables. Pour réaliser ces objectifs, il était essentiel de colliger des données cliniques approfondies d'une manière standardisée et d'amasser un grand nombre de divers types d'échantillons humains avant et après le contact viral. Lorsque la pandémie a évolué par l'émergence de nouveaux variants préoccupants (VOC), il est devenu nécessaire d'accéder à des échantillons et à des données de personnes infectées et vaccinées pour surveiller la durabilité de l'immunité, la possibilité d'une transmissibilité et d'une virulence accrues et la protection conférée par les vaccins contre les VOC nouveaux et émergents. Ainsi, il est essentiel de disposer d'un vigoureux volet de recherches de laboratoire et de recherches à partir de données pour répondre à la pandémie, soutenu par une mise en biobanque et un partage des données efficaces. Pour assurer une réponse rapide par la recherche, il est tout aussi important d'accéder rapidement aux échantillons mis en biobanque. Afin de relever les défis cruciaux soulevés par la pandémie, le Coronavirus Variants Rapid Response Network (réseau de réponse rapide aux variants du coronavirus; CoVaRR-Net), financé par les Instituts de recherche en santé du Canada, a été créé pour coordonner les efforts de recherche afin de fournir des réponses rapides fondées sur des données probantes aux VOC en émergence. Le présent article vise à présenter la Biobanque CoVaRR-Net et à en définir la contribution à la préparation aux pandémies.

SARS-CoV-2 Vaccine-Induced T-Cell Response after Three Doses in People Living with HIV on Antiretroviral Therapy Compared to Seronegative Controls (CTN 328 COVAXHIV Study).

People living with HIV (PLWH) may be at risk for poor immunogenicity to certain vaccines, including the ability to develop immunological memory. Here, we assessed T-cell immunogenicity following three SARS-CoV-2 vaccine doses in PLWH versus uninfected controls. Blood was collected from 38 PLWH on antiretroviral therapy and 24 age-matched HIV-negative controls, pre-vaccination and after 1st/2nd/3rd dose of SARS-CoV-2 vaccines, without prior SARS-CoV-2 infection. Flow cytometry was used to assess ex vivo T-cell immunophenotypes and intracellular Tumor necrosis factor (TNF)-α/interferon(IFN)-γ/interleukin(IL)-2 following SARS-CoV-2-Spike-peptide stimulation. Comparisons were made using Wilcoxon signed-rank test for paired variables and Mann-Whitney for unpaired. In PLWH, Spike-specific CD4 T-cell frequencies plateaued post-2nd dose, with no significant differences in polyfunctional SARS-CoV-2-specific T-cell proportions between PLWH and uninfected controls post-3rd dose. PLWH had higher frequencies of TNFα+CD4 T-cells and lower frequencies of IFNγ+CD8 T-cells than seronegative participants post-3rd dose. Regardless of HIV status, an increase in naive, regulatory, and PD1+ T-cell frequencies was observed post-3rd dose. In summary, two doses of SARS-CoV-2 vaccine induced a robust T-cell immune response in PLWH, which was maintained after the 3rd dose, with no significant differences in polyfunctional SARS-CoV-2-specific T-cell proportions between PLWH and uninfected controls post-3rd dose.

Hepatocyte-derived DPP4 regulates portal GLP-1 bioactivity, modulates glucose production, and when absent influences NAFLD progression.

Elevated circulating dipeptidyl peptidase-4 (DPP4) is a biomarker for liver disease, but its involvement in gluconeogenesis and metabolic associated fatty liver disease progression remains unclear. Here, we identified that DPP4 in hepatocytes but not TEK receptor tyrosine kinase-positive endothelial cells regulates the local bioactivity of incretin hormones and gluconeogenesis. However, the complete absence of DPP4 (Dpp4-/-) in aged mice with metabolic syndrome accelerates liver fibrosis without altering dyslipidemia and steatosis. Analysis of transcripts from the livers of Dpp4-/- mice displayed enrichment for inflammasome, p53, and senescence programs compared with littermate controls. High-fat, high-cholesterol feeding decreased Dpp4 expression in F4/80+ cells, with only minor changes in immune signaling. Moreover, in a lean mouse model of severe nonalcoholic fatty liver disease, phosphatidylethanolamine N-methyltransferase mice, we observed a 4-fold increase in circulating DPP4, in contrast with previous findings connecting DPP4 release and obesity. Last, we evaluated DPP4 levels in patients with hepatitis C infection with dysglycemia (Homeostatic Model Assessment of Insulin Resistance > 2) who underwent direct antiviral treatment (with/without ribavirin). DPP4 protein levels decreased with viral clearance; DPP4 activity levels were reduced at long-term follow-up in ribavirin-treated patients; but metabolic factors did not improve. These data suggest elevations in DPP4 during hepatitis C infection are not primarily regulated by metabolic disturbances.

Ribavirin Does Not Enhance Hepatitis B Virus Nucleotide Antiviral Activity: A Pilot Study.

PURPOSE: There is a need for effective and affordable treatments that achieve hepatitis B virus (HBV) functional cure and prevent long-term complications. The use of immune-modulators combined with HBV antivirals is a promising therapeutic strategy to achieve these goals. Based on ribavirin (RBV) monotherapy data, we hypothesized that RBV could improve virological responses when used in combination with tenofovir.  Methods: In this randomized, open label, controlled pilot trial, we evaluated RBV (n=4) dosed for the initial 24 weeks of treatment versus no RBV (n=4) in tenofovir recipients dosed over 48 weeks.  Results: Although well tolerated and safe in combination with tenofovir, RBV demonstrated no beneficial effects on virologic, biochemical or immunological markers of chronic HBV infection over 48 weeks of serial evaluation.  Conclusions: Our data does not suggest a HBV-specific immunomodulatory effect or an impact of RBV on HBV virological and antigen suppression.

Longitudinal profiles of plasma gelsolin, cytokines and antibody expression predict COVID-19 severity and hospitalization outcomes.

Background: Prognostic markers for COVID-19 disease outcome are currently lacking. Plasma gelsolin (pGSN) is an actin-binding protein and an innate immune marker involved in disease pathogenesis and viral infections. Here, we demonstrate the utility of pGSN as a prognostic marker for COVID-19 disease outcome; a test performance that is significantly improved when combined with cytokines and antibodies compared to other conventional markers such as CRP and ferritin. Methods: Blood samples were longitudinally collected from hospitalized COVID-19 patients as well as COVID-19 negative controls and the levels of pGSN in µg/mL, cytokines and anti- SARS-CoV-2 spike protein antibodies assayed. Mean ± SEM values were correlated with clinical parameters to develop a prognostic platform. Results: pGSN levels were significantly reduced in COVID-19 patients compared to healthy individuals. Additionally, pGSN levels combined with plasma IL-6, IP-10 and M-CSF significantly distinguished COVID-19 patients from healthy individuals. While pGSN and anti-spike IgG titers together strongly predict COVID-19 severity and death, the combination of pGSN and IL-6 was a significant predictor of milder disease and favorable outcomes. Conclusion: Taken together, these findings suggest that multi-parameter analysis of pGSN, cytokines and antibodies could predict COVID-19 hospitalization outcomes with greater certainty compared with conventional clinical laboratory markers such as CRP and ferritin. This research will inform and improve clinical management and health system interventions in response to SARS-CoV-2 infection.

BATL: Bayesian annotations for targeted lipidomics.

MOTIVATION: Bioinformatic tools capable of annotating, rapidly and reproducibly, large, targeted lipidomic datasets are limited. Specifically, few programs enable high-throughput peak assessment of liquid chromatography-electrospray ionization tandem mass spectrometry data acquired in either selected or multiple reaction monitoring modes. RESULTS: We present here Bayesian Annotations for Targeted Lipidomics, a Gaussian naïve Bayes classifier for targeted lipidomics that annotates peak identities according to eight features related to retention time, intensity, and peak shape. Lipid identification is achieved by modeling distributions of these eight input features across biological conditions and maximizing the joint posterior probabilities of all peak identities at a given transition. When applied to sphingolipid and glycerophosphocholine selected reaction monitoring datasets, we demonstrate over 95% of all peaks are rapidly and correctly identified. AVAILABILITY AND IMPLEMENTATION: BATL software is freely accessible online at https://complimet.ca/batl/ and is compatible with Safari, Firefox, Chrome and Edge. SUPPLEMENTARY INFORMATION: Supplementary data are available at Bioinformatics online.

Cohort profile: Stop the Spread Ottawa (SSO)-a community-based prospective cohort study on antibody responses, antibody neutralisation efficiency and cellular immunity to SARS-CoV-2 infection and vaccination.

PURPOSE: To investigate the robustness and longevity of SARS-CoV-2 immune responses conferred by natural infection and vaccination among priority populations such as immunocompromised individuals and people with post-acute sequelae of COVID-19 in a prospective cohort study (Stop the Spread Ottawa-SSO) in adults living in the Ottawa region. In this paper, we describe the study design, ongoing data collection and baseline characteristics of participants. PARTICIPANTS: Since October 2020, participants who tested positive for COVID-19 (convalescents) or at high risk of exposure to the virus (under surveillance) have provided monthly blood and saliva samples over a 10-month period. As of 2 November 2021, 1026 adults had completed the baseline survey and 976 had attended baseline bloodwork. 300 participants will continue to provide bimonthly blood samples for 24 additional months (ie, total follow-up of 34 months). FINDINGS TO DATE: The median age of the baseline sample was 44 (IQR 23, range: 18-79) and just over two-thirds (n=688; 67.1%) were female. 255 participants (24.9%) had a history of COVID-19 infection confirmed by PCR and/or serology. Over 600 participants (60.0%) work in high-risk occupations (eg, healthcare, teaching and transportation). 108 participants (10.5%) reported immunocompromising conditions or treatments at baseline (eg, cancer, HIV, other immune deficiency, and/or use of immunosuppressants). FUTURE PLANS: SSO continues to yield rich research potential, given the collection of pre-vaccine baseline data and samples from the majority of participants, recruitment of diverse subgroups of interest, and a high level of participant retention and compliance with monthly sampling. The 24-month study extension will maximise opportunities to track SARS-CoV-2 immunity and vaccine efficacy, detect and characterise emerging variants, and compare subgroup humoral and cellular response robustness and persistence.

Relative Ratios of Human Seasonal Coronavirus Antibodies Predict the Efficiency of Cross-Neutralization of SARS-CoV-2 Spike Binding to ACE2.

BACKGROUND: Antibodies raised against human seasonal coronaviruses (sCoVs), which are responsible for the common cold, are known to cross-react with SARS-CoV-2 antigens. This prompts questions about their protective role against SARS-CoV-2 infections and COVID-19 severity. However, the relationship between sCoVs exposure and SARS-CoV-2 correlates of protection are not clearly identified. METHODS: We performed a cross-sectional analysis of cross-reactivity and cross-neutralization to SARS-CoV-2 antigens (S-RBD, S-trimer, N) using pre-pandemic sera from four different groups: pediatrics and adolescents, individuals 21 to 70 years of age, older than 70 years of age, and individuals living with HCV or HIV. Data was then further analysed using machine learning to identify predictive patterns of neutralization based on sCoVs serology. FINDINGS: Antibody cross-reactivity to SARS-CoV-2 antigens varied between 1.6% and 15.3% depending on the cohort and the isotype-antigen pair analyzed. We also show a range of neutralizing activity (0-45%) with median inhibition ranging from 17.6 % to 23.3 % in serum that interferes with SARS-CoV-2 spike attachment to ACE2 independently of age group. While the abundance of sCoV antibodies did not directly correlate with neutralization, we show that neutralizing activity is rather dependent on relative ratios of IgGs in sera directed to all four sCoV spike proteins. More specifically, we identified antibodies to NL63 and OC43 as being the most important predictors of neutralization. INTERPRETATION: Our data support the concept that exposure to sCoVs triggers antibody responses that influence the efficiency of SARS-CoV-2 spike binding to ACE2, which may potentially impact COVID-19 disease severity through other latent variables. FUNDING: This study was supported by a grant by the CIHR (VR2 -172722) and by a grant supplement by the CITF, and by a NRC Collaborative R&D Initiative Grant (PR031-1).

TLR-4 Agonist Induces IFN-γ Production Selectively in Proinflammatory Human M1 Macrophages through the PI3K-mTOR- and JNK-MAPK-Activated p70S6K Pathway.

IFN-γ, a proinflammatory cytokine produced primarily by T cells and NK cells, activates macrophages and engages mechanisms to control pathogens. Although there is evidence of IFN-γ production by murine macrophages, IFN-γ production by normal human macrophages and their subsets remains unknown. Herein, we show that human M1 macrophages generated by IFN-γ and IL-12- and IL-18-stimulated monocyte-derived macrophages (M0) produce significant levels of IFN-γ. Further stimulation of IL-12/IL-18-primed macrophages or M1 macrophages with agonists for TLR-2, TLR-3, or TLR-4 significantly enhanced IFN-γ production in contrast to the similarly stimulated M0, M2a, M2b, and M2c macrophages. Similarly, M1 macrophages generated from COVID-19-infected patients' macrophages produced IFN-γ that was enhanced following LPS stimulation. The inhibition of M1 differentiation by Jak inhibitors reversed LPS-induced IFN-γ production, suggesting that differentiation with IFN-γ plays a key role in IFN-γ induction. We subsequently investigated the signaling pathway(s) responsible for TLR-4-induced IFN-γ production in M1 macrophages. Our results show that TLR-4-induced IFN-γ production is regulated by the ribosomal protein S6 kinase (p70S6K) through the activation of PI3K, the mammalian target of rapamycin complex 1/2 (mTORC1/2), and the JNK MAPK pathways. These results suggest that M1-derived IFN-γ may play a key role in inflammation that may be augmented following bacterial/viral infections. Moreover, blocking the mTORC1/2, PI3K, and JNK MAPKs in macrophages may be of potential translational significance in preventing macrophage-mediated inflammatory diseases.

Selective killing of human M1 macrophages by Smac mimetics alone and M2 macrophages by Smac mimetics and caspase inhibition.

The inflammatory and anti-inflammatory Mϕs have been implicated in many diseases including rheumatoid arthritis, multiple sclerosis, and leprosy. Recent studies suggest targeting Mϕ function and activation may represent a potential target to treat these diseases. Herein, we investigated the effect of second mitochondria-derived activator of caspases (SMAC) mimetics (SMs), the inhibitors of apoptosis (IAPs) proteins, on the killing of human pro- and anti-inflammatory Mϕ subsets. We have shown previously that human monocytes are highly susceptible whereas differentiated Mϕs (M0) are highly resistant to the cytocidal abilities of SMs. To determine whether human Mϕ subsets are resistant to the cytotoxic effects of SMs, we show that M1 Mϕs are highly susceptible to SM-induced cell death whereas M2a, M2b, and M2c differentiated subsets are resistant, with M2c being the most resistant. SM-induced cell death in M1 Mϕs was mediated by apoptosis as well as necroptosis, activated both extrinsic and intrinsic pathways of apoptosis, and was attributed to the IFN-γ-mediated differentiation. In contrast, M2c and M0 Mϕs experienced cell death through necroptosis following simultaneous blockage of the IAPs and the caspase pathways. Overall, the results suggest that survival of human Mϕs is critically linked to the activation of the IAPs pathways. Moreover, agents blocking the cellular IAP1/2 and/or caspases can be exploited therapeutically to address inflammation-related diseases.

The 9th Canadian Symposium on Hepatitis C Virus: Advances in HCV research and treatment towards elimination.

Hepatitis C virus (HCV) elimination has evolved into a coordinated global effort. Canada, with more than 250,000 chronically infected individuals, is among the countries leading this effort. The 9th Canadian Symposium on HCV, held in February 2020, thus established and addressed its theme, 'advances in HCV research and treatment towards elimination', by gathering together basic scientists, clinicians, epidemiologists, social scientists, and community members interested in HCV research in Canada. Plenary sessions showcased topical research from prominent international and national researchers, complemented by select abstract presentations. This event was hosted by the Canadian Network on Hepatitis C (CanHepC), with support from the Public Health Agency of Canada and the Canadian Institutes of Health Research and in partnership with the Canadian Liver Meeting. CanHepC has an established record in HCV research by its members and in its advocacy activities to address the care, treatment, diagnosis, and immediate and long-term needs of those affected by HCV infection. Many challenges remain in tackling chronic HCV infection, such as the need for a vaccine; difficult-to-treat populations and unknown aspects of patient subgroups, including pregnant women and children; vulnerable people; and issues distinct to Indigenous peoples. There is also increasing concern about long-term clinical outcomes after successful treatment, with the rise in comorbidities such as diabetes, cardiovascular disease, and fatty liver disease and the remaining risk for hepatocellular carcinoma in cirrhotic individuals. The symposium addressed these topics in highlighting research advances that will collectively play an important role in eliminating HCV and minimizing subsequent health challenges.

Expression of Inhibitory Receptors on T and NK Cells Defines Immunological Phenotypes of HCV Patients with Advanced Liver Fibrosis.

Chronic HCV can result in advanced liver disease, including cirrhosis. Patients with advanced fibrosis experience poor clinical outcomes and increased risk for hepatocellular carcinoma (HCC). These outcomes are, in part, a consequence of immune dysfunction. Increased inhibitory receptor and Galectin-9 (GAL-9) expression is a possible mechanism promoting lymphocyte dysfunction. In this study, we measured the expression of inhibitory receptors and GAL-9 on T/NK cells of patients with chronic HCV with no to moderate fibrosis (F0-F2) and advanced fibrosis (F3-F4). To analyze their co-expression, we employed t-SNE analysis. Notably, we found that F3-F4 patients had higher frequencies of >3 inhibitory receptor co-expression on NK cells. Moreover, F3-F4 patients manifest a higher frequency of NK cells co-expressing TIGIT and TIM-3, and CD4/NK cells co-expressing LAG-3 and GAL-9. In conclusion, we identified phenotypes of immune dysregulation that could explain the increased susceptibility to infection and HCC in patients with chronic HCV with advanced fibrosis.

IL-7 induces sCD127 release and mCD127 downregulation in human CD8+ T cells by distinct yet overlapping mechanisms, both of which are impaired in HIV infection.

The IL-7 receptor specific α chain, CD127, can be expressed both as a membrane-associated (mCD127) and a soluble form (sCD127), however, the mechanisms involved in their regulation remain to be defined. We first demonstrated in primary human CD8+ T cells that IL-7-induced downregulation of mCD127 expression is dependent on JAK and PI3K signaling, whereas IL-7-induced sCD127 release is also mediated by STAT5. Following stimulation with IL-7, expression of alternatively spliced variants of the CD127 gene, sCD127 mRNA, is reduced, but to a lesser degree than the full-length gene. Evaluation of the role of proteases revealed that MMP-9 was involved in sCD127 release, without affecting the expression of mCD127, suggesting it does not induce direct shedding from the cell surface. Since defects in the IL-7/CD127 pathway occur in various diseases, including HIV, we evaluated CD8+ T cells derived from HAART-treated HIV-infected individuals and found that IL-7-induced (1) downregulation of mCD127, (2) release of sCD127, and (3) expression of the sCD127 mRNA were all impaired. Expression of mCD127 and sCD127 is, therefore, regulated by distinct, but overlapping, mechanisms and their impairment in HIV infection contributes to our understanding of the CD8+ T cell dysfunction that persists despite effective antiretroviral therapy.

In Vitro Hepatitis C Virus Infection and Hepatic Choline Metabolism.

Choline is an essential nutrient required for normal neuronal and muscular development, as well as homeostatic regulation of hepatic metabolism. In the liver, choline is incorporated into the main eukaryotic phospholipid, phosphatidylcholine (PC), and can enter one-carbon metabolism via mitochondrial oxidation. Hepatitis C virus (HCV) is a hepatotropic positive-strand RNA virus that similar to other positive-strand RNA viruses and can impact phospholipid metabolism. In the current study we sought to interrogate if HCV modulates markers of choline metabolism following in vitro infection, while subsequently assessing if the inhibition of choline uptake and metabolism upon concurrent HCV infection alters viral replication and infectivity. Additionally, we assessed whether these parameters were consistent between cells cultured in fetal bovine serum (FBS) or human serum (HS), conditions known to differentially affect in vitro HCV infection. We observed that choline transport in FBS- and HS-cultured Huh7.5 cells is facilitated by the intermediate affinity transporter, choline transporter-like family (CTL). HCV infection in FBS, but not HS-cultured cells diminished CTL1 transcript and protein expression at 24 h post-infection, which was associated with lower choline uptake and lower incorporation of choline into PC. No changes in other transporters were observed and at 96 h post-infection, all differences were normalized. Reciprocally, limiting the availability of choline for PC synthesis by use of a choline uptake inhibitor resulted in increased HCV replication at this early stage (24 h post-infection) in both FBS- and HS-cultured cells. Finally, in chronic infection (96 h post-infection), inhibiting choline uptake and metabolism significantly impaired the production of infectious virions. These results suggest that in addition to a known role of choline kinase, the transport of choline, potentially via CTL1, might also represent an important and regulated process during HCV infection.

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-ß 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.

Evaluation of Safety and Effectiveness of Elvitegravir/Cobicistat/Emtricitabine/Tenofovir Alafenamide Switch Followed by Ledipasvir/Sofosbuvir HCV Therapy in HIV-HCV Coinfection.

BACKGROUND: We conducted a pilot study assessing the feasibility, efficacy, and safety of a simplified combination HIV antiretroviral and hepatitis C virus (HCV) antiviral regimen in HIV-HCV coinfection. METHODS: Participants on suppressive antiretrovirals and HCV genotype 1 infection were switched to single-tablet daily-dosed elvitegravir/cobicistat/emtricitabine/tenofovir alafenamide (E/C/F/TAF) and 1 month later initiated single-tablet-regimen daily-dosed ledipasvir-sofosbuvir for 12 weeks. E/C/F/TAF was continued during HCV treatment and for 12 weeks after. RESULTS: Twenty-six individuals were screened, 25 enrolled, and 23 completed all HIV and HCV treatment. Participants were predominantly male, with a mean age (SD) of 55 (7.5) years. The median transient elastography score (interquartile range [IQR]) was 5.9 (5.3 to 7.6) kPa, and the mean CD4 count (SD) was 579 (223) cells/µL. The median adherence to HCV medications, assessed by pill count, was 100% (95% confidence interval [CI], 100%-100%), and HIV ranged from 99% to 100% (100%; 95% CI, 90%-100%) over the 7-month study duration. HIV undetectability was maintained in all but 1 participant enrolled with unsuspected multiclass resistance. Treatment was well tolerated, with no study medication modification due to adverse events and no serious adverse event related to the study drug. All participants achieved sustained virological response. The mean CD4 count (SD) increased to 673 (361) cells/µL, and the fibrosis score (IQR) declined to 5.2 (4.4 to 7.4) kPa by week 12 after HCV treatment. There was no treatment effect on glucose metabolism. Cholesterol increased during and after treatment. CONCLUSIONS: Provision of this 2-tablet daily HIV-HCV regimen is feasible, well tolerated, and safe, avoids drug-drug interactions between HIV and HCV medications, maintains HIV suppression in the absence of drug resistance, and is highly curative of HCV.