Soluble inflammatory markers as predictors of virological response in patients with chronic hepatitis C virus infection treated with interferon-α plus ribavirin

The host immune response plays an important role in viral clearance in patients who are chronically infected with hepatitis C virus (HCV) and are treated with interferon and ribavirin. Activation of the immune system involves the release of pro and anti-inflammatory molecules that can be measured in plasma samples. The present study aimed to evaluate the association between pretreatment plasma levels of chemokines and soluble tumor necrosis factor receptors (sTNF-R) and the virological response in treated patients with chronic hepatitis C infection. Forty-one chronically-infected HCV patients that were being treated with interferon-α (IFN-α) plus ribavirin were included in the study. Socio-demographic, clinical and laboratory data were collected and pretreatment plasma levels of chemokine CCL2, CCL3, CCL11, CCL24, chemokine CXCL9, CXCL10, sTNF-R1 and sTNF-R2 were measured. The virological response was assessed at treatment week 12, at the end of treatment and 24 weeks after treatment. Pretreatment CXCL10 levels were significantly higher in patients without an early virological response (EVR) or sustained virological response (SVR) compared to responders [512.9 pg/mL vs. 179.1 pg/mL (p = 0.011) and 289.9 pg/mL vs. 142.7 pg/mL (p = 0.045), respectively]. The accuracy of CXCL10 as a predictor of the absence of EVR and SVR was 0.79 [confidence interval (CI) 95%: 0.59-0.99] and 0.69 (CI 95%: 0.51-0.87), respectively. Pretreatment plasma levels of the other soluble inflammatory markers evaluated were not associated with a treatment response. Pretreatment CXCL10 levels were predictive of both EVR and SVR to IFN-α and ribavirin and may be useful in the evaluation of candidates for therapy.

Dengue-2 and yellow fever 17DD viruses infect human dendritic cells, resulting in an induction of activation markers, cytokines and chemokines and secretion of different TNF-α and IFN-α profiles

Flaviviruses cause severe acute febrile and haemorrhagic infections, including dengue and yellow fever and the pathogenesis of these infections is caused by an exacerbated immune response. Dendritic cells (DCs) are targets for dengue virus (DENV) and yellow fever virus (YF) replication and are the first cell population to interact with these viruses during a natural infection, which leads to an induction of protective immunity in humans. We studied the infectivity of DENV2 (strain 16681), a YF vaccine (YF17DD) and a chimeric YF17D/DENV2 vaccine in monocyte-derived DCs in vitro with regard to cell maturation, activation and cytokine production. Higher viral antigen positive cell frequencies were observed for DENV2 when compared with both vaccine viruses. Flavivirus-infected cultures exhibited dendritic cell activation and maturation molecules. CD38 expression on DCs was enhanced for both DENV2 and YF17DD, whereas OX40L expression was decreased as compared to mock-stimulated cells, suggesting that a T helper 1 profile is favoured. Tumor necrosis factor (TNF)-α production in cell cultures was significantly higher in DENV2-infected cultures than in cultures infected with YF17DD or YF17D/DENV. In contrast, the vaccines induced higher IFN-α levels than DENV2. The differential cytokine production indicates that DENV2 results in TNF induction, which discriminates it from vaccine viruses that preferentially stimulate interferon expression. These differential response profiles may influence the pathogenic infection outcome.

Influence of GB virus C on IFN-γ and IL-2 production and CD38 expression in T lymphocytes from chronically HIV-infected and HIV-HCV-co-infected patients

This study was designed to assess the effect of GB virus (GBV)-C on the immune response to human immunodeficiency virus (HIV) in chronically HIV-infected and HIV- hepatitis C virus (HCV)-co-infected patients undergoing antiretroviral therapy. A cohort of 159 HIV-seropositive patients, of whom 52 were HCV-co-infected, was included. Epidemiological data were collected and virological and immunological markers, including the production of interferon gamma (IFN-γ) and interleukin (IL)-2 by CD4, CD8 and Tγδ cells and the expression of the activation marker, CD38, were assessed. A total of 65 patients (40.8%) presented markers of GBV-C infection. The presence of GBV-C did not influence HIV and HCV replication or TCD4 and TCD8 cell counts. Immune responses, defined by IFN-γ and IL-2 production and CD38 expression did not differ among the groups. Our results suggest that neither GBV-C viremia nor the presence of E2 antibodies influence HIV and HCV viral replication or CD4 T cell counts in chronically infected patients. Furthermore, GBV-C did not influence cytokine production or CD38-driven immune activation among these patients. Although our results do not exclude a protective effect of GBV-C in early HIV disease, they demonstrate that this effect may not be present in chronically infected patients, who represent the majority of patients in outpatient clinics.

Schistosoma mansoni antigens alter the cytokine response in vitro during cutaneous leishmaniasis

Schistosoma mansoni infection or associated products are able to down-modulate the type 1 CD4+ T cell inflammatory response characteristic of autoimmune diseases. In this study, we evaluated how S. mansoni antigens altered the immune response that was induced by the soluble Leishmania antigen (SLA) from cutaneous leishmaniasis (CL) patients. Cytokines were measured from the supernatants of peripheral blood mononuclear cell cultures stimulated with SLA. This was performed using the sandwich enzyme linked immunosorbent assay technique in the presence or absence of S. mansoni recombinant antigens Sm29, SmTSP-2 and PIII. The addition of S. mansoni antigens to the cultures resulted in the reduction of interferon gamma (IFN-γ) levels in 37-50% of patients. Although to a lesser extent, the antigens were also able to decrease the production of tumour necrosis factor-alpha (TNF-α). We compared patients that either had or did not have reduction in IFN-γ and TNF-α production in cultures stimulated with SLA in the presence of S. mansoni antigens. We found that there was no significant difference in the levels of interleukin (IL)-10 and IL-5 in response to S. mansoni antigens between the groups. The antigens used in this study down-modulated the in vitro proinflammatory response induced by SLA in a group of CL patients through a currently undefined mechanism.

A single nucleotide polymorphism, rs129679860, in the IL28B locus is associated with the viral kinetics and a sustained virological response in a chronic, monoinfected hepatitis C virus genotype-1 Brazilian population treated with pegylated interferon-ribavirin

Single nucleotide polymorphisms (SNPs) in the interleukin (IL)28B locus have been associated with a sustained virological response (SVR) in interferon-ribavirin (IFN-RBV)-treated chronic hepatitis C virus (HCV)-infected patients in European and African populations. In this study, the genotype frequency of two IL28B SNPs (rs129679860 and rs8099917) in a cohort of chronic HCV-monoinfected patients in Brazil was evaluated and the SNP sufficient to predict the treatment response outcome was determined. A total of 66 naïve genotype-1 chronic HCV-infected patients were genotyped and the associated viral kinetics and SVR were assessed. The overall SVR was 38%. Both the viral kinetics and SVR were associated with rs129679860 genotypes (CC = 62% vs. CT = 33% vs. TT = 18%, p = 0.016). However, rs8099917 genotypes were only associated with SVR (TT = 53% vs. TG = 33% vs. GG = 18%; p = 0.032). In this population, the analysis of a single SNP, rs12979860, successfully predicts SVR in the IFN-RBV treatment of HCV.

Response to treatment in Brazilian patients with chronic hepatitis C is associated with a single-nucleotide polymorphism near the interleukin-28B gene

A single-nucleotide polymorphism (SNP) upstream of interleukin (IL)28B was recently identified as an important predictor of the outcome of chronic hepatitis C patients treated with pegylated interferon plus ribavirin (PEG-IFN/RBV). The aim of this study was to investigate the association between the IL28B gene polymorphism (rs12979860) and virological response in chronic hepatitis C patients. Brazilian patients (n = 263) who were infected with hepatitis C virus (HCV) genotype 1 and were receiving PEG-IFN/RBV were genotyped. Early virological response (EVR) (12 weeks), end-of-treatment response (EOTR) (48 weeks), sustained virological response (SVR) (72 weeks) and relapse were evaluated using conventional and quantitative polymerase chain reaction (PCR) assays. The frequency of the C allele in the population was 39%. Overall, 43% of patients experienced SVR. The IL28B CC genotype was significantly associated with higher treatment response rates and a lower relapse rate compared to the other genotypes [84% vs. 58% EVR, 92% vs. 63% EOTR, 76% vs. 38% SVR and 17% vs. 40% relapse rate in CC vs. other genotypes (CT and TT), respectively]. Thus, the IL28B genotype appears to be a strong predictor of SVR following PEG-IFN/RBV therapy in treatment-naïve Brazilian patients infected with HCV genotype 1. This study, together with similar research examining other SNPs, should help to define adequate protocols for the treatment of patients infected with HCV genotype 1, especially those with a poor prognosis.

Candidate gene study of TRAIL and TRAIL receptors: association with response to interferon beta therapy in multiple sclerosis patients.

TRAIL and TRAIL Receptor genes have been implicated in Multiple Sclerosis pathology as well as in the response to IFN beta therapy. The objective of our study was to evaluate the association of these genes in relation to the age at disease onset (AAO) and to the clinical response upon IFN beta treatment in Spanish MS patients. We carried out a candidate gene study of TRAIL, TRAILR-1, TRAILR-2, TRAILR-3 and TRAILR-4 genes. A total of 54 SNPs were analysed in 509 MS patients under IFN beta treatment, and an additional cohort of 226 MS patients was used to validate the results. Associations of rs1047275 in TRAILR-2 and rs7011559 in TRAILR-4 genes with AAO under an additive model did not withstand Bonferroni correction. In contrast, patients with the TRAILR-1 rs20576-CC genotype showed a better clinical response to IFN beta therapy compared with patients carrying the A-allele (recessive model: p = 8.88×10(-4), pc = 0.048, OR = 0.30). This SNP resulted in a non synonymous substitution of Glutamic acid to Alanine in position 228 (E228A), a change previously associated with susceptibility to different cancer types and risk of metastases, suggesting a lack of functionality of TRAILR-1. In order to unravel how this amino acid change in TRAILR-1 would affect to death signal, we performed a molecular modelling with both alleles. Neither TRAIL binding sites in the receptor nor the expression levels of TRAILR-1 in peripheral blood mononuclear cell subsets (monocytes, CD4+ and CD8+ T cells) were modified, suggesting that this SNP may be altering the death signal by some other mechanism. These findings show a role for TRAILR-1 gene variations in the clinical outcome of IFN beta therapy that might have relevance as a biomarker to predict the response to IFN beta in MS.

Gestation and breastfeeding in schistosomotic mothers differently modulate the immune response of adult offspring to postnatal Schistosoma mansoni infection

Schistosoma mansoni antigens in the early life alter homologous and heterologous immunity during postnatal infections. We evaluate the immunity to parasite antigens and ovalbumin (OA) in adult mice born/suckled by schistosomotic mothers. Newborns were divided into: born (BIM), suckled (SIM) or born/suckled (BSIM) in schistosomotic mothers, and animals from noninfected mothers (control). When adults, the mice were infected and compared the hepatic granuloma size and cellularity. Some animals were OA + adjuvant immunised. We evaluated hypersensitivity reactions (HR), antibodies levels (IgG1/IgG2a) anti-soluble egg antigen and anti-soluble worm antigen preparation, and anti-OA, cytokine production, and CD4+FoxP3+T-cells by splenocytes. Compared to control group, BIM mice showed a greater quantity of granulomas and collagen deposition, whereas SIM and BSIM presented smaller granulomas. BSIM group exhibited the lowest levels of anti-parasite antibodies. For anti-OA immunity, immediate HR was suppressed in all groups, with greater intensity in SIM mice accompanied of the remarkable level of basal CD4+FoxP3+T-cells. BIM and SIM groups produced less interleukin (IL)-4 and interferon (IFN)-g. In BSIM, there was higher production of IL-10 and IFN-g, but lower levels of IL-4 and CD4+FoxP3+T-cells. Thus, pregnancy in schistosomotic mothers intensified hepatic fibrosis, whereas breastfeeding diminished granulomas in descendants. Separately, pregnancy and breastfeeding could suppress heterologous immunity; however, when combined, the responses could be partially restored in infected descendants.

Genetically resistant mice lacking interleukin-12 are susceptible to infection with Leishmania major and mount a polarized Th2 cell response.

Mice with homologous disruption of the gene coding for either the p35 subunit or the p40 subunit of interleukin-12 (IL-12) and derived from a strain genetically resistant to infection with Leishmania major have been used to study further the role of this cytokine in resistance to infection and the differentiation of functional CD4+ T cell subsets in vivo. Wild-type 129/Sv/Ev mice are resistant to infection with L. major showing only small lesions which resolve spontaneously within a few weeks and develop a type 1 CD4+ T cell response. In contrast, mice lacking bioactive IL-12 (IL-12p35-/- and IL-12p40-/-) developed large, progressing lesions. Whereas resistant mice were able to mount a delayed-type hypersensitivity (DTH) response to Leishmania antigen, susceptible BALB/c mice as well as IL-12-deficient 129/Sv/Ev mice did not show any DTH reaction. To characterize the functional phenotype of CD4+ T cells triggered in infected wild-type mice and IL-12-deficient mice, the expression of mRNA for interferon-gamma (IFN-gamma) and interleukin-4 (IL-4) in purified CD4+ lymph node cells was analyzed. Wild-type 129/Sv/Ev mice showed high levels of mRNA for IFN-gamma and low levels of mRNA for IL-4 which is indicative of a Th1 response. In contrast, IL-12- deficient mice and susceptible BALB/c mice developed a strong Th2 response with high levels of IL-4 mRNA and low levels of IFN-gamma mRNA in CD4+ T cells. Similarly, lymph node cells from infected wild-type 129 mice produced predominantly IFN-gamma in response to stimulation with Leishmania antigen in vitro whereas lymph node cells from IL-12-deficient mice and susceptible BALB/c mice produced preferentially IL-4. Taken together, these results confirm in vivo the importance of IL-12 in induction of Th1 responses and protective immunity against L. major.

The role of Toll-like Receptor (TLR) 9 in the development of a T-helper (Th)1/Th2 response in the murine model of infection with " Leishmania major "

1.1 SUMMARY The role of the non-specific innate immune system is as important as the elaboration of the adaptive immune system in the initiation of an immune response to pathogens. The role of the Toll-like receptors (TLRs) in the innate immune response to virus and bacterial pathogens is widely recognised, however, little is known about the role of TLRs in host defence against eukaryotic pathogens. Immunologic investigations on the marine model of infection with Leishmania major (L. major) have correlated the outcome of the disease with expansion of different subsets of CD4+ cells, designated Th1 and Th2. The resistance of C57BL/6, CBA and C3H/He mice is linked with an IL-12 driven Th1 response. In BALB/c mice the susceptibility correlates with an IL-4 driven Th2 response. The initial event promoting the development of a Th1 or Th2 response still remains elusive. Recently, the contribution of the TLR signalling pathway in the innate and acquired immune response to infection with the intracellular protozoan parasite L. major has been demonstrated. Thus, the purpose of this study is to determine whether TLRs may play a role in influencing the outcome of the infection by directing the development of a Th1 or a Th2 response during infection with L, major parasites, in resistant C57BL/6 and susceptible BALB/c mice, respectively. We demonstrated that MyD88, the major TLR adaptor molecule is necessary for C57BL/6 to develop a resistant Th1 response following L. major infection. Our data show the essential role of MyD88 in the establishment of a protective Th1 response. We subsequently aimed to determine which TLRs may be involved in the protective response. Since TLR2 and TLR4 have shown to have a potential role for Leishmania recognition, we analysed the course of infection in TLR2 and TLR4 deficient mice on a C57BL/6 resistant background following L. major infection. Our results clearly demonstrate that TLR2 or TLR4 aze dispensable to control the outcome of the disease as the TLR2 and TLR4 knockout mice developed a protective Th1 response. With the aim of determining a potential TLR candidate important in the initiation of the Thl response, we assessed the mRNA expression of different TLRs (TLR1 to TLR9) using quantitative real-time RT-PCR at different time points during the first week of infection. The results clearly showed an upregulation of TLR7 and TLR9 mRNA expression during the early phase of infection in resistant C57BL/6 mice but not in susceptible BALB/c mice. To provide in vivo evidence for the role for, these TLRs in the outcome of cutaneous leishmaniasis, studies using TLR7 and TLR9 deficient mice on a resistant C57BL/6 background were performed. The TLR7 deficient mice developed a resistance phenotype that was comparable with C57BL/6 wild type mice. Thus, the presence of TLR7 is not indispensable for the development of a Th1 response and resistance to infection. On the contrary, TLR9 deficient mice on the C57BL/6 resistant background showed high variability in the outcome of the disease. Although some mice behave as resistant C57BL/6 mice, half of them developed high lesion following infection and showed a decrease in IFN-γ production and an increase in IL-4 as compared to wild type mice. These results suggest that TLR9 may be involved in the control of infection. To test the hypothesis that regulatory T cells (Treg) are playing a role in the high variability in the disease outcome in TLR9 deficient mice, depletion of CD4+CD25+ T cells with a specific antibody three days before infection with L. major were performed Interestingly, these treated mice developed large lesions, low IL-4 and decreased IFN-γ producion when compared to untreated mice. A better understanding of the mechanism by which Treg cells influence the outcome of the disease in TLR9 deficient mice following L. major infection is currently under investigation. Altogether, this study demonstrates the importance of TLR9 in the induction of a protective T'h1 response, a process that is involved in the resolution of the lesion induced by L. major infection. 1.2 RÉSUMÉ Le rôle de la réponse immunitaire innée a longtemps été négligé quant à l'impact qu'elle pourrait avoir dans l'initiation d'une réponse immune adaptative efficace dirigée contre un pathogène. Si l'importance des récepteurs Toll-like (TLR) du système inné dans la reconnaissance des virus et bactéries a été démontrée, son rôle dans la défense contre les pathogènes eucaryotes reste encore très élusif. Récemment, il a été montré que les voies de signalisation provenant de l'activation des TLRs pouvaient initier la réponse immunitaire innée et adaptative après une infection avec le parasite protozoaire Leishmania major (L. major). Dans un modèle marin d'infection avec L. major alors que la plupart des souches de souris telles que C57BL/6 sont résistantes à l'infection et développent une réponse immunitaire de type T helper 1 (Th1) induite par IL-12, peu de souches dont les BALB/c sont sensibles et développent une réponse Th2 induite par IL-4. La différentiation Th1/Th2 est un événement qui prend place de manière définitive lors de la première semaine après infection. Les événements précoces promouvant le développement d'une réponse Th1 ou Th2 n'étant pas connus, l'objectif de ce travail a été de démontrer un rôle des TLRs dans l'initiation d'une réponse immune innée et adaptative suite à l'infection par L. major. Nous avons démontré que MyD88, une molécule importante dans le processus de signalisation des TLRs, est nécessaire pour que les souris résistantes C57BL/6 développent une réponse Th1 protectrice. L'importance du rôle de TLR2 et TLR4 dans la reconnaissance du parasite Leishmania ayant été démontrée, nous avons privilégié l'analyse de la réponse immunitaire suite à une infection in vivo de souris déficiente en TLR2 ou TLR4 sur un fond génétique résistant. Les résultats obtenus montrent que la présence de ces récepteurs n'est pas indispensable pour le contrôle de l'infection et la polarisation d'une réponse Th1 caractéristique de la résistance à L. major. Cependant d'autres TLRs peuvent aussi activer la voie de signalisation MyD88 dépendante. L'expression de l'ARNm des différents TLRs dans les ganglions drainant de souris sensibles et résistantes pendant la première semaine d'infection a été déterminée par PCR quantitative en temps réel. Les résultats obtenus montrent que l'ARNm de TLR7 et TLR9 était régulé positivement suite à l'infection par L. major chez les souris résistantes C57BL/6 alors qu'aucune modulation n'était détectable chez les souris sensibles BALB/c. Le rôle des récepteurs TLR7 et TLR9 a donc été évalué par l'infection par L. major des souris déficientes en TLR7 et TLR9 sur fond génétique C57BL/6. Nos résultats ont clairement démontré que les souris déficientes en TLR7 montrent une réponse immunitaire identique à celle des souris résistantes C57BL/6, signifiant que TLR7 n'est pas indispensable au développement d'une Th1 ainsi qu'au contrôle de la parasitémie. Paz contre, les souris déficientes en TLR9 sur un fond génétique résistant ont montré une grande variabilité dans la réponse à l'infection. En effet, la moitié des souris deviennent sensibles à l'infection, ceci étant associé à une diminution dans la production d'IFN-γ et à une augmentation de la production d'IL-4. Ces résultats suggèrent que TLR9 est impliqué dans le contrôle de la lésion et de la réponse immunitaire suite à l'infection avec L. major. Cependant les résultats avec les souris déficientes en TLR9 montrant une grande hétérogénéité et une balance Th1/Th2 instable, nous avons émis l'hypothèse que les cellules T régulatrices pouvaient être impliquées dans ce phénomène. Nous avons effectivement constaté qu'après déplétion des cellules CD4+CD25+, les souris déficientes en TLR9 développent des lésions aussi grandes que les souris BALB/c après infection par L. major. Cependant le nombre de parasites reste le même que chez les souris C57BL/6. De plus la production d'IL-4 ainsi que celle d'IFN-γ reste extrêment bas. Les mécanismes régulateurs impliqués dans ce processus sont en cours d'analyse. Ce travail met en évidence l'importance du TLR9 dans le développement d'une réponse Th1 lors d'une infection avec L. major, un processus nécessaire pour la résistance à l'infection. 1.3 RESUME POUR UN LARGE PUBLIC La leishmaniose est une maladie parasitaire répandue dans le monde entier et touchant plus de 88 pays. L'incidence mondiale de la leishmaniose cutanée et de 1 à 1,5 million de nouveaux cas par année. Plus de 12 millions de personnes sont affectées par la maladie et 350 millions de personnes sont une population à risque. Un modèle marin d'infection avec Leishmania major (L. major) a été établi qui reproduit plusieurs tableaux cliniques observés dans le cas de la leishmaniose cutanée chez l'homme. L'analyse de la réponse immunitaire dans les souris infectées par L. major a permis de distinguer deux groupes : les souris de la plupart des souches telles que C57BL/6 sont résistantes à l'infection et développent une réponse immunitaire de type T helper 1 (Th1), alors que quelques souches dont les BALB/c sont sensibles et développent une réponse de type Th2. La réponse immune adaptative dans le modèle d'infection avec L. major à été largement étudiée. Cependant, les événements précoces déterminants pour le développement d'une réponse Th1 ou Th2 restent encore très flous. Récemment, plusieurs publications ont montré que les récepteurs Toll-like (TLR) peuvent contribuer à l'initiation de la réponse immunitaire lors d'une infection avec le parasite intracellulaire L. major. Dans ce travail de thèse, nous avons étudié le rôle de MyD88, une molécule importante dans le processus de signalisation des TLRs, dans la réponse immune suite à une infection avec L. major. En l'absence de MyD88, les souris normalement résistantes à l'infection avec L. major deviennent sensibles et développent des lésions importantes. Ces souris ne sont plus capables de développer une réponse Thl, normalement caractéristique de leur phénotype résistant. Nous avons ensuite tenté de comprendre quels TLRs, plus précisément, pouvait être impliqué dans ce processus. Malgré quelques évidences démontrant que TLR2 et TLR4 pouvaient avoir un rôle important dans l'initiation d'une réponse immunitaire adaptative à Leishmania, nous avons montré que, in vivo après infection avec L. major, la déficience d'un de ces récepteurs n'était pas suffisante à faire basculer la réponse immunitaire. Les souris C57BL/6 déficient en TLR2 ou TLR4 peuvent parfaitement contrôler l'évolution de la maladie. De plus, ces souris, malgré l'absence de TLR2 ou TLR4, sont capables de monter une parfaite réponse Thl. Etant donné que TLR2 et TLR4 n'étaient pas essentiels pour la résistance à la maladie, nous avons analysé les TLRs, parmi les 12 décrits qui pouvaient être indispensables au développement d'une réponse de type Th1 associée à la résistance à l'infection par Leishmania. Nos expériences ont montré que l'expression de l'ARN messager (ARNm) de TLR7 et TLR9 était modulée suite à l'infection par L. major chez la souris résistante C57BL/6 alors qu'aucune modulation n'était visible chez les souris sensible BALB/c. Pensant que ces TLRs pourraient jouer un rôle dans la réponse immunitaire au parasite, nous avons étudié l'évolution de l'infection dans les souris déficientes en TLR7 et TLR9. Nos résultats ont clairement démontré que TLR7 n'était pas indispensable à la résistance au parasite alors que l'absence de TLR9 avait des conséquences radicales sur le contrôle de la lésion et de la réponse immunitaire suite à l'infection avec L. major. Ce travail révèle ainsi l'importance du TLR9 dans le développement d'une réponse Th1 lors d'une infection avec L. major, un processus nécessaire pour la résistance à l'infection. Il est a noté que nos résultats sont en accord avec le fait que les motifs CpG, qui sont des immunostimulateurs interagissant avec le TLR9, ont une activité adjuvante importante dans la préparation de vaccins contre la leishmaniose. Une meilleure compréhension des mécanismes immunologiques impliquant le TLR9 dans la reconnaissance du parasite est alors indispensable pour le développement de vaccins thérapeutiques efficaces.

A Genetic Validation Study Reveals a Role of Vitamin D Metabolism in the Response to Interferon-Alfa-Based Therapy of Chronic Hepatitis C.

BACKGROUND: To perform a comprehensive study on the relationship between vitamin D metabolism and the response to interferon-α-based therapy of chronic hepatitis C. METHODOLOGY/PRINCIPAL FINDINGS: Associations between a functionally relevant polymorphism in the gene encoding the vitamin D 1α-hydroxylase (CYP27B1-1260 rs10877012) and the response to treatment with pegylated interferon-α (PEG-IFN-α) and ribavirin were determined in 701 patients with chronic hepatitis C. In addition, associations between serum concentrations of 25-hydroxyvitamin D(3) (25[OH]D(3)) and treatment outcome were analysed. CYP27B1-1260 rs10877012 was found to be an independent predictor of sustained virologic response (SVR) in patients with poor-response IL28B genotypes (15% difference in SVR for rs10877012 genotype AA vs. CC, p = 0.02, OR = 1.52, 95% CI = 1.061-2.188), but not in patients with favourable IL28B genotype. Patients with chronic hepatitis C showed a high prevalence of vitamin D insufficiency (25[OH]D(3)<20 ng/mL) during all seasons, but 25(OH)D(3) serum levels were not associated with treatment outcome. CONCLUSIONS/SIGNIFICANCE: Our study suggests a role of bioactive vitamin D (1,25[OH](2)D(3), calcitriol) in the response to treatment of chronic hepatitis C. However, serum concentration of the calcitriol precursor 25(OH)D(3) is not a suitable predictor of treatment outcome.

The impact of fibrosis and steatosis on early viral kinetics in HCV genotype 1-infected patients treated with Peg-IFN-alfa-2a and ribavirin.

Summary.  Hepatitis C viral (HCV) kinetics after initiation of interferon-based therapy provide valuable insights for understanding virus pathogenesis, evaluating treatment antiviral effectiveness and predicting treatment outcome. Adverse effects of liver fibrosis and steatosis on sustained virological response have been frequently reported, yet their impacts on the early viral kinetics remain unclear. In this study, associations between histology status and early viral kinetics were assessed in 149 HCV genotype 1-infected patients treated with pegylated interferon alfa-2a and ribavirin (DITTO trial). In multivariate analyses adjusted for critical factors such as IL28B genotype and baseline viral load, presence of significant fibrosis (Ishak stage > 2) was found to independently reduce the odds of achieving an initial reduction (calculated from day 0 to day 4) in HCV RNA of ≥2 logIU/mL (adjusted OR 0.03, P = 0.004) but was not associated with the second-phase slope of viral decline (calculated from day 8 to day 29). On the contrary, presence of liver steatosis was an independent risk factor for not having a rapid second-phase slope, that is, ≥0.3 logIU/mL/week (adjusted OR 0.22, P = 0.012) but was not associated with the first-phase decline. Viral kinetic modelling theory suggests that significant fibrosis primarily impairs the treatment antiviral effectiveness in blocking viral production by infected cells, whereas the presence of steatosis is associated with a lower net loss of infected cells. Further studies will be necessary to identify the biological mechanisms underlain by these findings.

Impairment of JCV-specific T-cell response by corticotherapy: Effect on PML-IRIS management?

OBJECTIVE: To investigate the impact of corticosteroids (CS) on the viral-specific T-cell response, in particular the JC virus (JCV)-specific one, in an attempt to determine the optimal timing of CS in the management of progressive multifocal leukoencephalopathy-immune reconstitution inflammatory syndrome (PML-IRIS). METHODS: A blood draw was performed before and 7 days after the administration of IV CS to 24 patients with relapsing multiple sclerosis (MS). The phenotypic pattern of T cells was determined by CCR7 and CD45RA. To assess the impact of CS treatment on proliferative response of JCV-, influenza-, and Epstein-Barr virus (EBV)-specific T cells, a thymidine incorporation proliferation assay was performed. An intracellular cytokine staining assay was performed to determine the effect of CS treatment on the production of cytokine by virus-specific T cells. JCV T-cell assays were performed only in JCV-infected patients with MS as detected by serologies (Stratify) or detection of JCV DNA in the urine by PCR. RESULTS: CS led T cells, CD4+ and CD8+, toward a less differentiated phenotype. There was a significant decrease of EBV-, influenza-, and JCV-specific T-cell proliferative response upon CS treatment. There was a significant decrease in the frequency of interferon (IFN) γ- and tumor necrosis factor (TNF) α-producing JCV-specific CD8+ T cells, but not EBV- or influenza-specific CD4+ or CD8+ T cells. CONCLUSIONS: CS have a profound impact on the virus-specific T-cell response, especially on JCV, suggesting that when CS are considered, they should not be given before the onset of clinical or radiologic signs of IRIS. Studies addressing directly patients with MS with natalizumab-caused PML are warranted. CLASSIFICATION OF EVIDENCE: This study provides Class III evidence that methylprednisolone treatment decreases the frequency of JCV-specific CD8+ T cells producing IFN-γ and TNFα, impairing control of JCV, suggesting this should be used to treat but not to prevent PML-IRIS. No clinical outcomes were measured.

Should we await IFN-free regimens to treat HCV genotype 1 treatment-naive patients? A cost-effectiveness analysis (ANRS 95141).

BACKGROUND & AIMS: In treatment-naive patients mono-infected with genotype 1 chronic HCV, treatments with telaprevir/boceprevir (TVR/BOC)-based triple therapy are standard-of-care. However, more efficacious direct-acting antivirals (IFN-based new DAAs) are available and interferon-free (IFN-free) regimens are imminent (2015). METHODS: A mathematical model estimated quality-adjusted life years, cost and incremental cost-effectiveness ratios of (i) IFN-based new DAAs vs. TVR/BOC-based triple therapy; and (ii) IFN-based new DAAs initiation strategies, given that IFN-free regimens are imminent. The sustained virological response in F3-4/F0-2 was 71/89% with IFN-based new DAAs, 85/95% with IFN-free regimens, vs. 64/80% with TVR/BOC-based triple therapy. Serious adverse events leading to discontinuation were taken as: 0-0.6% with IFN-based new DAAs, 0% with IFN-free regimens, vs. 1-10% with TVR/BOC-based triple therapy. Costs were euro60,000 for 12weeks of IFN-based new DAAs and two times higher for IFN-free regimens. RESULTS: Treatment with IFN-based new DAAs when fibrosis stage ⩾F2 is cost-effective compared to TVR/BOC-based triple therapy (euro37,900/QALY gained), but not at F0-1 (euro103,500/QALY gained). Awaiting the IFN-free regimens is more effective, except in F4 patients, but not cost-effective compared to IFN-based new DAAs. If we decrease the cost of IFN-free regimens close to that of IFN-based new DAAs, then awaiting the IFN-free regimen becomes cost-effective. CONCLUSIONS: Treatment with IFN-based new DAAs at stage ⩾F2 is both effective and cost-effective compared to TVR/BOC triple therapy. Awaiting IFN-free regimens and then treating regardless of fibrosis is more efficacious, except in F4 patients; however, the cost-effectiveness of this strategy is highly dependent on its cost.

Reduced IFNλ4 activity is associated with improved HCV clearance and reduced expression of interferon-stimulated genes

Hepatitis C virus (HCV) infections are the major cause of chronic liver disease, cirrhosis and hepatocellular carcinoma worldwide. Both spontaneous and treatment-induced clearance of HCV depend on genetic variation within the interferon-lambda locus, but until now no clear causal relationship has been established. Here we demonstrate that an amino-acid substitution in the IFNλ4 protein changing a proline at position 70 to a serine (P70S) substantially alters its antiviral activity. Patients harbouring the impaired IFNλ4-S70 variant display lower interferon-stimulated gene (ISG) expression levels, better treatment response rates and better spontaneous clearance rates, compared with patients coding for the fully active IFNλ4-P70 variant. Altogether, these data provide evidence supporting a role for the active IFNλ4 protein as the driver of high hepatic ISG expression as well as the cause of poor HCV clearance.