Étude de la réponse immunitaire cérébrale innée dans la pathogenèse de l'encéphalite herpétique et évaluation de stratégies immunomodulatrices

La pathogenèse de l’encéphalite herpétique (HSE) n’est pas totalement connue, mais la réplication du virus engendre une encéphalite aiguë nécrosante du lobe temporal/frontal et une inflammation cérébrale menant à l’infiltration des cellules immunitaires périphériques au sein du système nerveux central. Bien que la majorité des dommages cérébraux engendrés seraient causés par la réplication virale, de plus en de plus de données indiquent une composante immunitaire dans la pathogenèse de l’HSE. La réponse immunitaire innée constitue la première ligne de défense limitant la propagation virale. Nous savons que la réponse immunitaire est engendrée à la suite de la reconnaissance du VHS-1, notamment par les « Toll-like receptors » (TLRs). De plus, la synthèse d’interféron (IFN) de type I est primordiale dans la réponse antivirale. En effet, des études montrent qu’une déficience d’un composant impliqué dans les voies de signalisation menant à la production d’IFNs de type I est délétère chez la souris et chez l’humain au cours de l’HSE. Par ailleurs, la migration des cellules immunitaires au sein du SNC prend de plus en plus d’ampleur dans l’étude de la réponse immunitaire contre cette infection. Cependant, bien que différents modèles animaux permettent l’étude de la réponse immunitaire cérébrale, la complexité de cette pathologie, du SNC et de sa réponse inflammatoire en limite encore notre compréhension. L’objectif principal de cette thèse a été de mieux comprendre la composante immunitaire de la pathogenèse de l’HSE, et plus spécifiquement, au niveau du recrutement des cellules immunitaires périphériques dans le SNC, de la participation des voies de signalisation passant par les facteurs de transcription régulateurs des IFNs (IRF) 3 et IRF7 et d’évaluer l’effet d’immunomodulateurs tels que l’artésunate et la rapamycine sur la sensibilité de différentes souches murines au cours de l’encéphalite herpétique expérimentale. Les études menées ont permis de mettre en évidence qu’une réponse immunitaire cérébrale innée efficace participe à la résistance naturelle des souris C57BL/6 en comparaison aux souris BALB/c naturellement sensibles. En effet, la charge virale dans le SNC des souris C57BL/6 infectées par le VHS-1 par voie I.N est plus faible au pic de l’infection (i. e jour 6 post-infection [p. i]) comparativement aux souris BALB/c. Ce contrôle de la charge virale est associé à une infiltration rapide (avec au jour 4 post-infection, infiltration de monocytes inflammatoires, de cellules dendritiques conventionnelles [cDCs], de cellules dendritiques plasmacytoïdes [pDCs], de cellules « natural killers » [NK], de cellules « natural killers T » [NKT]) et coordonnée (suivie d’une infiltration de lymphocyte T au jour 8 p. i). Par ailleurs, les travaux réalisés ont permis de mettre en évidence un rôle clé d’IRF3 et plus particulièrement d’IRF7 dans la réponse interféron de type I. En ce sens, les souris déficientes pour IRF3 ou IRF7 sont plus sensibles à l’infection intranasale par le VHS-1 que les souris C57BL/6 sauvages. Chez les souris déficientes pour IRF7 et dans une moindre mesure pour IRF3, la perte de contrôle de la réplication virale dans le cerveau est associée à un défaut de production d’IFN -b à un temps précoce après l’infection suivi par une surproduction des IFNs de type I. La sensibilité accrue au cours de l’HSE, aussi bien chez les souris BALB/c naturellement sensibles que chez les souris déficientes pour IRF7 ou IRF3, est combinée à une forte production de cytokines pro-inflammatoires et de chimiokines à des temps tardifs postinfection. Nous avons donc évalué l’effet de l’ajout d’immunomodulateurs au traitement antiviral : l’artésunate (ART), agissant sur les voies de signalisation passant par TLR2 et 9 et la rapamycine (RAPA), agissant sur les voies de signalisation passant par TLR3 et 9 et ainsi mis en évidence que l’ajout d’un composé immunomodulateur au traitement antiviral permettait d’améliorer la survie des souris sensibles à l’infection sans action directe sur la charge virale au niveau du cerveau, mais en diminuant significativement les taux de cytokines pro-inflammatoire et de chimiokines dans le SNC. À l’aide de ces différents modèles expérimentaux, j’ai également démontré une surexpression de cytokines pro-inflammatoires (l’IL-1 b, l’IL-6, l’IFN -g) et de chimiokine (CCL2), dont les taux sont diminués par l’ajout d’un traitement immunomodulateur à la thérapie antivirale dans un modèle murin sensible à l’HSE. Ces données apportent donc de nouvelles preuves d’une composante immunitaire dans la pathogenèse de l’encéphalite herpétique, ainsi que de nouvelles cibles thérapeutiques potentielles.Pathogenesis of herpes simplex encephalitis is not completely understood, but viral replication results in acute necrotizing encephalitis of the temporal/frontal lobes and cerebral inflammation leading to the infiltration of the peripheral immune cells to the central nervous system (CNS). Although most brain damage is caused by viral replication, a lot of data suggest that the immune response could also contribute to the pathogenesis of HSE. The innate immune response is the first line of host defense that limits viral spread. Numerous studies showed that the immune response is induced by the recognition of HSV-1, in particular by the toll-like receptors (TLRs). Likewise, type I interferon (IFN) is essential to the antiviral response. Indeed, studies showed that impairment of a component involved in signaling pathways inducing the type I IFN synthesis is deleterious in mice and humans during HSE. For several years, a series of studies have suggested that the immune response participated in this CNS pathology resulting in a fatal course and that hyperinflammatory responses initiated by early infiltrating innate cells play a key role in the development of this pathology. In addition, the complexity of the CNS inflammatory response constitutes a challenge for our understanding of the pathogenesis of herpetic encephalitis. The main objective of this thesis was to better understand the immune response as a contributor to the pathogenesis of HSE, and more specifically, the recruitment of peripheral immune cells in the CNS, the involvement of signaling pathway mediated by the interferon regulatory transcription factors (IRF) 3 and IRF7 and the evaluation of the effects of immunomodulators such as artesunate and rapamycin on the susceptibility of different murine strains during experimental HSE An effective innate cerebral immune response contributes to the natural resistance of C57BL/6 mice compared to naturally sensitive BALB/c mice. In fact, the viral load in the CNS of C57BL/6 mice infected with HSV-1 by the I.N. route is lower at the peak of infection (day 6 post-infection (p.i)) compared to BALB/c mice. This control of the viral load is associated with rapid and coordinated infiltration of cells in the CNS (infiltration of inflammatory monocytes, conventional dendritic cells (cDCs), plasmacytoid dendritic cells (pDCs), natural killer cells (NK), natural killer cells T (NKT) on day 4 p.i) followed by T lymphocyte infiltration on day 8 p.i. Moreover, the control of viral replication is orchestrated by the activation of transcription factors IRF3 and particularly IRF7. In this regard, mice deficient for IRF3 or IRF7 are more susceptible to intranasal infection by HSV-1 than wild type C57BL/6 mice. In mice deficient for IRF7 and to a lesser extent for IRF3, the loss of control of viral replication in the brain is associated with a defect in IFN-b production at an early time after infection followed by overproduction of type I IFNs. Increased susceptibility of BALB/c mice, IRF3- or IRF7-deficient mice is associated with higher levels of pro-inflammatory cytokines and chemokines levels in the CNS compared to C57BL/6 mice at later times post-infection. We therefore evaluated the effect of the addition of immunomodulators to antiviral treatment: artesunate (ART), acting on signaling pathways mediated by TLR2 and 9 and rapamycin (RAPA), acting on signaling pathways mediated by TLR3 and 9. We show that the administration of ART or RAPA to the antiviral therapy was beneficial and improve the outcome of HSE in mice, without a direct effect on the viral load. Instead they act by decreasing significantly pro-inflammatory cytokine and chemokine levels in the CNS. Using these different experimental models, we also demonstrated overexpression of pro-inflammatory cytokines (IL-1 b, IL-6, IFN -g) and chemokine (CC2) during experimental HSE. In this regard, adding of immunomodulatory compound to antiviral therapy allowed to decrease levels of these inflammatory proteins. In conclusion, these data provide new evidence for the contribution of the immune response in the pathogenesis of herpetic encephalitis, as well as the development of potential new therapeutic targets

Canal de Provence

Presented at the 2002 USCID/EWRI conference, Energy, climate, environment and water - issues and opportunities for irrigation and drainage on July 9-12 in San Luis Obispo, California.Includes bibliographical references.Measurement network on hydraulic system includes many sensors subject to failure or deviation, and spread over a huge area. In addition discharge and volume measurements in open channel hydraulic networks are characterized by large uncertainties. To overcome this kind of problem, in process control industrial applications, data reconciliation is more and more used. The objective of the data reconciliation is to take advantage of information redundancy on a system to make a cross-checking of real-time measurements. Using this information redundancy, a data reconciliation module allows to detect inconsistent measurements, measurement deviations and provides corrected values whether the initial measurements are valid, biased or invalid. A derived consequence is to better schedule the maintenance of sensors. A data reconciliation module, based on the measurements from the hydraulic network, has been recently developed and implemented in the SCP's supervisory system. The software has initially been used on a daily basis to check the measured flow on the main canal. It has then been adapted in order to run every 15 minutes on a distribution network including pipes, canals, and tanks. The paper presents first the theory of the Canal de Provence data reconciliation application. The basic model is an hydraulic network with a series of nodes corresponding to balance equations (inflows, outflows, and storage). Constrained data reconciliation is used in order to satisfy the non-negativity of the hydraulic variables and the mass balance relations. The results are corrected values for measured variables and proposed values for non-measured quantities. A statistical analysis of the results is performed. This analysis allows to evaluate the uncertainties attached to the estimated flows and volume values. It allows also to detect invalid measurements, drift of sensors and to decide which maintenance operations to perform. Secondly, field examples are presented: measured and re-estimated flow values with their standard deviations, detection of invalid sensors, performed maintenance operation. The data reconciliation is situated just after the measurement process and takes place in the decision process for diagnosis, identification and control

Using Passive Samplers to Track per and Polyfluoroalkyl Substances (PFAS) Emissions From the Paper Industry: Laboratory Calibration and Field Verification

Per and polyfluoroalkyl substances (PFAS) are becoming more stringently regulated and as such, a more diverse suite of environmental monitoring methods is needed. In this work a polar organic chemical integrative sampler (POCIS) with a nylon membrane and a combination of Oasis WAX and Fluoroflash® sorbents was calibrated in the laboratory and deployed in the field. A static renewal system was used to determine sampling rates for 12 PFAS which ranged between 0.69 ± 0.27 to 5.68 ± 1.80 L/day. POCIS devices were deployed for 10 days in lake Tyrifjorden, Norway which is known to be contaminated by a closed down factory producing paper products, in order to track the evolution of the PFAS contamination in a river system draining into the lake. Th sampling campaign enabled the stretch of the river which was responsible for the emissions of PFAS to lake Tyrifjorden to be identified. Freely dissolved concentrations determined with the POCIS were lowest at the site considered to reflect a diffuse PFAS contamination and highest at the site located downstream the factory. Perfluorooctanesulfonic acid (PFOS), perfluorohexanoic acid (PFHxA) and perfluorooctane sulfonamidoacetic acid (EtFOSAA) dominated the concentration profile at this site. Emissions of PFAS to lake Tyrifjorden were estimated to be 3.96 g/day for the sum of the 12 investigated PFAS.publishedVersio

Can high psychological job demands, low decision latitude, and high job strain predict disability pensions? A 12-year follow-up of middle-aged Swedish workers.

OBJECTIVES: The aim of this study was to investigate whether job strain, psychological demands, and decision latitude are independent determinants of disability pension rates over a 12-year follow-up period. METHODS: We studied 3,181 men and 3,359 women, all middle-aged and working at least 30 h per week, recruited from the general population of Malmö, Sweden, in 1992. The participation rate was 41 %. Baseline data include sociodemographics, the Job Content Questionnaire, lifestyle, and health-related variables. Disability pension information was obtained through record linkage from the National Health Insurance Register. RESULTS: Nearly 20 % of the women and 15 % of the men were granted a disability pension during the follow-up period. The highest quartile of psychological job demands and the lowest quartile of decision latitude were associated with disability pensions when controlling for age, socioeconomic position, and health risk behaviours. In the final model, with adjustment also for health indicators and stress from outside the workplace, the hazard ratios for high strain jobs (i.e. high psychological demands in combination with low decision latitude) were 1.5 in men (95 % CI, 1.04-2.0) and 1.7 in women (95 % CI, 1.3-2.2). Stratifying for health at baseline showed that high strain tended to affect healthy but not unhealthy men, while this pattern was reversed in women. CONCLUSIONS: High psychological demands, low decision latitude, and job strain were all confirmed as independent risk factors for subsequent disability pensions. In order to increase chances of individuals remaining in the work force, interventions against these adverse psychosocial factors appear worthwhile

Insomnia Symptoms, Sleep Duration, and Disability Pensions: a Prospective Study of Swedish Workers.

BACKGROUND: Previous studies have found insomnia and long sleep duration to be independently associated with subsequent disability pension (DP). However, the issue of a possible gender-based pattern in this context has received little attention. PURPOSE: This study aims to assess the impact of insomnia symptoms and sleep duration on the DP rates among Swedish women and men during a 12-year follow-up period. METHOD: The participants, from the general population of Malmö, Sweden, were enrolled from 1992 to 1994 (n = 4,319; participation rate 41 %), aged 45-64, healthy, and employed ≥30 h per week. Baseline inquiry data concerning psychosocial circumstances and self-reported sleep habits were compared with official register-based DP rates. RESULTS: Five hundred and nine persons were granted a DP. Insomnia symptoms, affirmed by 33 % of the men and 41 % of the women, were associated with receiving a DP; the hazard ratios in the fully adjusted model were 1.4 for both men [95 % confidence interval (CI) 1.1, 1.9] and women (95 % CI 1.1, 1.7). The fully adjusted hazard ratio for women sleeping ≥9 h was 7.8 (95 % CI 3.7, 16.6) for DP due to a mental disorder. In the age-adjusted analyses, the sub-domain "difficulties falling asleep" was related to DP due to mental disorders in men and DP due to cardiovascular diseases in women. CONCLUSION: The findings suggest that preventing and treating insomnia symptoms could reduce DP and that disease mechanisms linking sleep disturbances to DP may differ by gender

Icodextrin-induced peritonitis: Study of five cases and comparison with bacterial peritonitis

Icodextrin-induced peritonitis: Study of five cases and comparison with bacterial peritonitis.BackgroundAn epidemic of aseptic peritonitis related to the presence of peptidoglycan contaminant in some batches of icodextrin solution (Extraneal®, Baxter Healthcare Corporation) occurred in Europe in the first six months of 2002.MethodsBy case-control study we examined the clinical and biologic features of 5 patients with icodextrin-induced peritonitis (group AP) and compared them with 7 patients with bacterial peritonitis (group BP) recruited in our clinical center between January and June 2002.ResultsDiagnosis of icodextrin-induced peritonitis was confirmed in all cases by a positive reintroduction test with contaminated batches of icodextrin. No recurrence was observed on re-exposure to icodextrin free of peptidoglycan. Skin tests were positive with contaminated icodextrin in 2 of 5 patients, while they were negative with icodextrin solution free of peptidoglycan (<0.6ng/mL). During peritonitis, serum level of C-reactive protein (CRP) was lower in group AP (42.4 ± 34mg/L) than in group BP (135 ± 59mg/L) (P = 0.01). Leukocyte number in peritoneal dialysis effluent was lower in group AP (284 ± 101/mm3), with a lower neutrophil/monocyte ratio (N/M = 0.67) than in group BP (1410 ± 973/mm3; N/M = 4) (P < 0.05). A low number of peritoneal fluid eosinophilia (11 ± 8%) was detected in group AP.ConclusionIcodextrin-induced peritonitis was associated with a burst of intraperitoneal cytokines. The phenotype of peritoneal neutrophils was different between aseptic and bacterial peritonitis, indicating that inflammatory stimuli that activate neutrophils in both types of peritonitis are clearly distinct. Finally, peritoneal injury measured by weight gain, peritoneal permeability, and CA125 concentration seemed to be less severe during icodextrin-induced peritonitis than during bacterial peritonitis