B Willems

Centre hospitalier de l'Université de Montréal (CHUM), Montréal, Quebec, Canada

Are you B Willems?

Claim your profile

Publications (53)315.23 Total impact

  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Although studies have addressed the exhaustion of the host's immune response to HCV and its role in treatment, there is little information about the possible contribution of innate immunity to treatment-induced clearance. We hypothesized that because intact myeloid dendritic cell (MDC) pathogen sensing functions are associated with improved HCV-specific CD8+ T cell functionality in some chronically infected patients, it might enhance HCV clearance rate under standard interferon therapy. To investigate this hypothesis, TLR-induced MDC activation and HCV-specific CD8+ T cell response quality were monitored longitudinally at the single-cell level using polychromatic flow cytometry in chronically infected patients undergoing interferon therapy. We correlated the immunological, biochemical and virological data with response to treatment. We demonstrate that the clinical efficacy of interferon-induced viral clearance is influenced by the extent to which HCV inhibits MDC functions before treatment, rather than solely on a breakdown of the extrinsic T cell immunosuppressive environment. Thus, viral inhibition of MDC functions before treatment emerges as a co-determining factor in the clinical efficacy of interferon therapy during chronic HCV infection.
    PLoS ONE 01/2014; 9(7):e102605. · 3.53 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Single nucleotide polymorphisms (SNPs) in the proximity of the interleukin-28B (IL28B) gene can predict spontaneous resolution of hepatitis C virus (HCV) infection and response to interferon therapy. Screening for this polymorphism has become part of the standard criteria for the management of HCV-infected patients, hence the need for a rapid, cost-effective screening method. Here, we describe a rapid PCR-based test to screen for two IL28B SNPs (rs12979860 and rs8099917). We used this test to investigate IL28B polymorphism and prevalence in a cohort of French Canadian injection drug users who are part of a unique population known to have a strong genetic founder effect. This population had lower linkage disequilibrium between the two tested SNPs as compared to other cohorts (|d'| = 0.68, r = 0.59). The special genetic makeup should be considered in the management of HCV-infected patients within that population.
    Immunogenetics 03/2013; · 2.89 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Interferon alpha (IFNα) therapy, despite good efficacy in curing HCV infection, leads to major side effects, in particular inducement of a strong peripheral T-cell lymphocytopenia. We here analyze the early consequences of IFNα therapy on both thymic function and peripheral T-cell homeostasis in patients in the acute or chronic phase of HCV-infection as well as in HIV/HCV co-infected patients. The evolution of T-cell subsets and T-cell homeostasis were estimated by flow cytometry while thymic function was measured through quantification of T-cell receptor excision circles (TREC) and estimation of intrathymic precursor T-cell proliferation during the first four months following the initiation of IFNα therapy. Beginning with the first month of therapy, a profound lymphocytopenia was observed for all T-cell subsets, including naïve T-cells and recent thymic emigrants (RTE), associated with inhibition of intrathymic precursor T-cell proliferation. Interleukin (IL)-7 plasma concentration rapidly dropped while lymphocytopenia progressed. This was neither a consequence of higher consumption of the cytokine nor due to its neutralization by soluble CD127. Decrease in IL-7 plasma concentration under IFNα therapy correlated with the decline in HCV viral load, thymic activity and RTE concentration in blood. These data demonstrate that IFNα-based therapy rapidly impacts on thymopoiesis and, consequently, perturbs T-cell homeostasis. Such a side effect might be detrimental for the continuation of IFNα therapy and may lead to an increased level of infectious risk, in particular in HIV/HCV co-infected patients. Altogether, this study suggests the therapeutic potential of IL-7 in the maintenance of peripheral T-cell homeostasis in IFNα-treated patients.
    PLoS ONE 01/2012; 7(4):e34326. · 3.53 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Early alpha interferon (IFN-alpha) therapy against hepatitis C virus (HCV) rescues polyfunctional, virus-specific memory CD8(+) T cells, but whether immune restoration is possible during late therapy remains controversial. We compared immune restoration of HCV-specific memory T cells in patients who cleared HCV infection spontaneously and following early or late IFN therapy. Multifunctional CD4(+) and CD8(+) memory T cells were detected in spontaneous resolvers and in individuals treated early following an acute infection. In contrast, limited responses were detected in patients treated during chronic infection, and the phenotype of HCV-specific cells was influenced by autologous viral sequences. Our data suggest that irreversible damage to the HCV-specific memory T-cell response is associated with chronic HCV infection.
    Journal of Virology 10/2010; 84(19):10429-35. · 5.08 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Although chronic viral infections have evolved mechanisms to interfere with aspects of pathogen recognition by dendritic cells (DCs), the role that these APCs play in virus-specific T cell exhaustion is unclear. Herein we report that NS3-dependent suppression of Toll/IL-1 domain-containing adapter-inducing IFN-beta- and IFN-beta promoter stimulator-1- but not MyD88-coupled pathogen-recognition receptor-induced synthesis of proinflammatory cytokines (IL-12 and TNF-alpha) from DCs by hepatitis C virus (HCV) is a distinctive feature of a subgroup of chronically infected patients. The result is decreased CD8(+) T cell polyfunctional capacities (production of IFN-gamma, IL-2, TNF-alpha, and CD107a mobilization) that is confined to HCV specificities and that relates to the extent to which HCV inhibits DC responses in infected subjects, despite comparable plasma viral load, helper T cell environments, and inhibitory programmed death 1 receptor/ligand signals. Thus, subjects in whom pathogen-recognition receptor signaling in DCs was intact exhibited enhanced polyfunctionality (i.e., IL-2-secretion and CD107a). In addition, differences between HCV-infected patients in the ability of CD8(+) T cells to activate multiple functions in response to HCV did not apply to CD8(+) T cells specific for other immune-controlled viruses (CMV, EBV, and influenza). Our findings identify reversible virus evasion of DC-mediated innate immunity as an additional important factor that impacts the severity of polyfunctional CD8(+) T cell exhaustion during a chronic viral infection.
    The Journal of Immunology 02/2010; 184(6):3134-44. · 5.52 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Since the discovery of hepatitis C virus (HCV), researchers have encountered difficulties with in vitro models. The aim of this study was to determine whether HCV-infected human primary hepatocytes, isolated from cirrhotic livers at liver transplantation, can be used as a model to study HCV infection. Hepatocytes were isolated with collagenase and cultured over a 20-day period on different matrices. Viral kinetics was monitored with/without treatment by real-time polymerase chain reaction. Cell yield and viability were higher with uninfected/non-cirrhotic livers (77.2+/-1.8%) in comparison with HCV-infected cirrhotic livers (68.8+/-12%). HCV-infected hepatocytes behaved similar to non-infected cells and expressed albumin and cytochrome P4502E1. HCV-positive strand was identified in supernatants and cell lysates. HCV-negative strand was only found inside cells and correlated with viral RNA recovery in the medium. Improvement in the degree of hepatocyte differentiation was associated with better HCV recovery. Antiviral treatment with interferon-alpha, EX4 and cyclosporine A induced significant reductions in HCV RNA. Primary cultures of HCV-infected human hepatocytes from end-stage cirrhotic livers is feasible, represents an excellent model to study specific virus-host interactions and can be used to assess viral replication.
    Liver international: official journal of the International Association for the Study of the Liver 04/2009; 29(6):942-9. · 3.87 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The majority of acute hepatitis C virus (HCV) infections progress to chronicity and progressive liver damage. Alpha interferon (IFN-alpha) antiviral therapy achieves the highest rate of success when IFN-alpha is administered early during the acute phase, but the underlying mechanisms are unknown. We used a panel of major histocompatibility complex class I tetramers to monitor the phenotypic and functional signatures of HCV-specific T cells during acute HCV infection with different infection outcomes and during early IFN therapy. We demonstrate that spontaneous resolution correlates with the early development of polyfunctional (IFN-gamma- and IL-2-producing and CD107a(+)) virus-specific CD8(+) T cells. These polyfunctional T cells are distinguished by the expression of CD127 and Bcl-2 and represent a transitional memory T-cell subset that exhibits the phenotypic and functional signatures of both central and effector memory T cells. In contrast, HCV-specific CD8(+) T cells in acute infections evolving to chronicity expressed low levels of CD127 and Bcl-2, exhibited diminished proliferation and cytokine production, and eventually disappeared from the periphery. Early therapeutic intervention with pegylated IFN-alpha rescued polyfunctional memory T cells expressing high levels of CD127 and Bcl-2. These cells were detectable for up to 1 year following discontinuation of therapy. Our results suggest that the polyfunctionality of HCV-specific T cells can be predictive of the outcome of acute HCV infection and that early therapeutic intervention can reconstitute the pool of long-lived polyfunctional memory T cells.
    Journal of Virology 08/2008; 82(20):10017-31. · 5.08 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Hepatitis C virus (HCV) rates have decreased steadily in first-time donors in Canada since testing was implemented but reasons are unclear. A description of factors that may have played a role in this decline is reported. Descriptive analysis of first-time blood donors by HCV positivity status and year (1993--2006), sex, and age was carried out. HCV-positive first-time donors and matched controls participated in a confidential scripted telephone interview about risk factors in 1993 through 1994 and in 2005 through 2006, and risk factors independently predicting HCV positivity were determined with multiple logistic regression. HCV-positive donations occurred most frequently in donors born between 1945 and 1964 and decreased in this birth cohort over time (p < 0.01). At present, most first-time donors (74%) are born after 1964. History of intravenous drug use, sex with an intravenous drug user, blood transfusion, and tattoo independently predicted (p < 0.01) HCV positivity in both periods (1993--1994 and 2005--2006). Most HCV-positive donors were born between 1945 and 1964, and the decline in HCV rates is associated primarily with this birth cohort. The key risk factors predicting HCV positivity did not change over the 13 years of the study. With approximately two-thirds of HCV-positive Canadians in the general population having been tested for HCV, potential donors may be aware of their HCV status and be likely to self-defer. This, and an increasing proportion of first-time donors born after 1964, may contribute to declining HCV rates in first-time donors.
    Transfusion 06/2008; 48(5):902-9. · 3.53 Impact Factor
  • Journal of Hepatology - J HEPATOL. 01/2008; 48.
  • Hawley Rigsby, Bernard Willems, Daniel Lamarre
    Cytokine 01/2008; 43(3):274-274. · 2.52 Impact Factor
  • Cytokine 01/2008; 43(3):306-307. · 2.52 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Concomitant HIV and hepatitis C virus (HCV) is a common yet complex coinfection. The present document is a practical guide for treating HCV infection in people coinfected with HIV. Effective antiretroviral therapies have prolonged survival rates for HIV-infected people over the past decade, which have made latent complications of HCV major causes of morbidity and mortality in these patients. Advances in the treatment of HCV (eg, combined pegylated interferon and ribavirin) offer the possibility of eradicating HCV infection in coinfected persons. The treatment of HCV must be considered in all cases. Intensive management of the adverse effects of HCV treatment is one of the factors for the success of these therapies. HCV eradication is predicted to decrease the mortality associated with coinfection and reduce the toxicity of HIV treatment.
    The Canadian journal of infectious diseases & medical microbiology = Journal canadien des maladies infectieuses et de la microbiologie medicale / AMMI Canada 10/2007; 18(5):293-303. · 1.02 Impact Factor
  • 14th International Symposium on Hepatitis C Virus and Related Viruses; 09/2007
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The role of peripheral dendritic cells (DCs) in hepatitis C virus (HCV) infection is unclear. To determine if persistent infection exerts an inhibitory pressure on HCV-specific innate responses, we analyzed DC function in blood through quantification of cell-associated HCV RNA levels in conjunction with multiparametric flow cytometry analysis of pathogen recognition receptor-induced cytokine expression. Independently of the serum viral load, fluorescence-activated cell sorter-purified total DCs had a wide range of cell-associated HCV genomic RNA copy numbers (mean log(10), 5.0 per 10(6) cells; range, 4.3 to 5.8). Here we report that for viremic patients with high viral loads in their total DCs, the myeloid DC (MDC) subset displayed impaired expression of interleukin-12 (IL-12) and tumor necrosis factor alpha (TNF-alpha) but normal IL-6 or chemokine CCL3 expression in response to poly(I:C) and lipopolysaccharide (LPS). IL-6-expressing cells from this subgroup of viremic patients demonstrated a significant increase (sixfold more) in TNF-alpha(-) IL-12(-) cell frequency compared to healthy donors (mean, 38.8% versus 6.5%; P < 0.0001), indicating a functional defect in a subpopulation of cytokine-producing MDCs ( approximately 6% of MDCs). Attenuation of poly(I:C) and LPS innate sensing was HCV RNA density dependent and did not correlate with viremia or deficits in circulating MDC frequencies in HCV-infected patients. Monocytes from these patients were functionally intact, responding normally on a per-cell basis following stimulation, independent of cell-associated HCV RNA levels. Taken together, these data indicate that detection of HCV genomic RNA in DCs and loss of function in the danger signal responsiveness of a small proportion of DCs in vivo are interrelated rather than independent phenomena.
    Journal of Virology 07/2007; 81(11):5537-46. · 5.08 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Plant-virus-based vaccines have emerged as a promising avenue in vaccine development. This report describes the engineering of an innovative vaccine platform using the papaya mosaic virus (PapMV) capsid protein (CP) as a carrier protein and a C-terminal fused hepatitis C virus (HCV) E2 epitope as the immunogenic target. Two antigen organizations of the PapMV-based vaccines were tested: a virus-like-particle (VLP; PapMVCP-E2) and a monomeric form (PapMVCP(27-215)-E2). While the two forms of the vaccine were both shown to be actively internalized in vitro in bone-marrow-derived antigen presenting cells (APCs), immunogenicity was demonstrated to be strongly dependent on antigen organization. Indeed, C3H/HeJ mice injected twice with the multimeric VLP vaccine showed a long-lasting humoral response (more than 120 days) against both the CP and the fused HCV E2 epitope. The antibody profile (production of IgG1, IgG2a, IgG2b, IgG3) suggests a Th1/Th2 response. Immunogenicity of the PapMV vaccine platform was not observed when the monomer PapMVCP-E2 was injected. These results demonstrate for the first time the potential of the PapMV vaccine platform and the critical function of multimerization in its immunogenicity.
    Virology 07/2007; 363(1):59-68. · 3.37 Impact Factor
  • Journal of Hepatology - J HEPATOL. 01/2007; 46.
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Approximately one third of hepatitis C virus (HCV) genotype 1 patients achieved a sustained virological response (SVR) after 24 weeks of treatment with peginterferon alpha-2a (40 kd) plus ribavirin in a randomized, multinational trial. We aimed to identify factors associated with a rapid virological response (RVR) at week 4 (HCV RNA <50 IU/mL) and a SVR (HCV RNA <50 IU/mL at the end of follow-up) in these patients. Stepwise multiple logistic regression analysis was used to explore the prognostic factors for a RVR and SVR in genotype 1 patients treated for 24 weeks. Fifty-one of 216 (24%) genotype 1 patients in the 24-week treatment groups had a RVR. SVR rates were considerably higher in patients with than without [corrected] a RVR (89% vs. 19%, respectively). Patients with a baseline HCV RNA of less than 200,000 IU/mL (OR 9.7, 95% CI 4.2-22.5; P < .0001) or 200,000-600,000 IU/mL (OR 5.6, 95% CI 1.5-9.1; P = .0057) were more likely to achieve a RVR than those with HCV RNA greater than 600,000 IU/mL. HCV subtype (1b vs. 1a) was also independently associated with RVR (OR 1.8, 95% CI 0.9-3.7; P = .0954). RVR (OR 23.7 vs. no RVR, 95% CI 9.1-61.7) and baseline HCV RNA less than 200,000 IU/mL (OR 2.7 vs. > 600,000 IU/mL, 95% CI 1.1-6.3; P < .026) were significant and independent predictors of SVR in patients treated for 24 weeks. In conclusion, patients infected with HCV genotype 1 and treated with peginterferon alpha-2a/ribavirin sustained a RVR 24% of the time. This portends an 89% probability of a SVR after 24 weeks of treatment.
    Hepatology 05/2006; 43(5):954-60. · 12.00 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The aim of this study was to assess the impact of fatigue on the quality of life of patients with chronic hepatitis C (CHC) and to examine its relationship with various parameters of the disease, including viral load. The Fatigue Impact Scale (FIS), a self-report questionnaire, was applied to 92 patients with CHC, and the results were compared to those of an age-matched cohort of 213 healthy blood donors. Fatigue was frequent and disabling, being present in 67% of CHC patients, and the FIS was significantly increased in CHC patients compared to the healthy controls. Fatigue severity was not correlated with the activity of the disease or with the level of viremia. The FIS proved to be a valuable tool to assess this symptom. It should be of help for better evaluation of the clinical spectrum of the disease and should be included in trials assessing the efficacy of therapeutic interventions.
    Digestive Diseases and Sciences 01/2003; 47(12):2674-81. · 2.26 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The transjugular intrahepatic portosystemic shunt (TIPS) is a new therapeutic modality for variceal bleeding. In this study we compared the two year survival and rebleeding rates in cirrhotic patients treated by either variceal band ligation or TIPS for variceal bleeding. Eighty cirrhotic patients (Pugh score 7-12) with variceal bleeding were randomly allocated to TIPS (n=41) or ligation (n=39), 24 hours after control of bleeding. Mean follow up was 581 days in the ligation group and 678 days in the TIPS group. The two year survival rate was 57% in the TIPS group and 56% in the ligation group (NS); the incidence of variceal rebleeding after two years was 18% in the TIPS group and 66% in the ligation group (p<0.001). Uncontrolled rebleeding occurred in 11 patients in the ligation group (eight were rescued by emergency TIPS) but in none of the TIPS group. The incidence of encephalopathy at two years was 47% in the TIPS group and 44% in the ligation group (NS). TIPS did not increase the two year survival rate compared with variceal band ligation after variceal bleeding in cirrhotic patients with moderate or severe liver failure. It significantly reduced the incidence of variceal rebleeding without increasing the rate of encephalopathy.
    Gut 03/2001; 48(3):390-6. · 10.73 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: A patient who underwent orthotopic liver transplantation for giant cell hepatitis with cirrhosis and in whom giant cell hepatitis recurred twice after orthotopic liver transplantation is reported. He was treated with ribavirin with an excellent result. The literature on this subject is reviewed. This observation clearly confirms the efficacy of ribavirin for the treatment of giant cell hepatitis, thus providing evidence for its viral origin.
    Canadian journal of gastroenterology = Journal canadien de gastroenterologie 10/2000; 14(8):729-31. · 1.53 Impact Factor

Publication Stats

2k Citations
315.23 Total Impact Points

Institutions

  • 1988–2014
    • Centre hospitalier de l'Université de Montréal (CHUM)
      Montréal, Quebec, Canada
    • Centre Hospitalier Saint Joseph Saint Luc
      Lyons, Rhône-Alpes, France
  • 1997–2013
    • Université de Montréal
      • Department of Microbiology and Immunology
      Montréal, Quebec, Canada
  • 2010
    • University of Toronto
      Toronto, Ontario, Canada
  • 2008
    • Assiut University
      • Faculty of Science
      Asyūţ, Muhafazat Asyut, Egypt
  • 2006
    • University of Chicago
      Chicago, Illinois, United States