Mammalian Innate Immune Response to a Leishmania-Resident RNA Virus Increases Macrophage Survival to Promote Parasite Persistence.

Some strains of the protozoan parasite Leishmania guyanensis (L.g) harbor a viral endosymbiont called Leishmania RNA virus 1 (LRV1). LRV1 recognition by TLR-3 increases parasite burden and lesion swelling in vivo. However, the mechanisms by which anti-viral innate immune responses affect parasitic infection are largely unknown. Upon investigating the mammalian host's response to LRV1, we found that miR-155 was singularly and strongly upregulated in macrophages infected with LRV1+ L.g when compared to LRV1- L.g. LRV1-driven miR-155 expression was dependent on TLR-3/TRIF signaling. Furthermore, LRV1-induced TLR-3 activation promoted parasite persistence by enhancing macrophage survival through Akt activation in a manner partially dependent on miR-155. Pharmacological inhibition of Akt resulted in a decrease in LRV1-mediated macrophage survival and consequently decreased parasite persistence. Consistent with these data, miR-155-deficient mice showed a drastic decrease in LRV1-induced disease severity, and lesional macrophages from these mice displayed reduced levels of Akt phosphorylation

Leishmaniavirus-dependent metastatic leishmaniasis is prevented by blocking IL-17A

Cutaneous leishmaniasis has various outcomes, ranging from self-healing reddened papules to extensive open ulcerations that metastasise to secondary sites and are often resistant to standard therapies. In the case of L. guyanensis (L.g), about 5-10% of all infections result in metastatic complications. We recently showed that a cytoplasmic virus within L.g parasites (LRV1) is able to act as a potent innate immunogen, worsening disease outcome in a murine model. In this study, we investigated the immunophenotype of human patients infected by L.g and found a significant association between the inflammatory cytokine IL-17A, the presence of LRV1 and disease chronicity. Further, IL-17A was inversely correlated to the protective cytokine IFN-γ. These findings were experimentally corroborated in our murine model, where IL-17A produced in LRV1+ L.g infection contributed to parasite virulence and dissemination in the absence of IFN-γ. Additionally, IL-17A inhibition in mice using digoxin or SR1001, showed therapeutic promise in limiting parasite virulence. Thus, this murine model of LRV1-dependent infectious metastasis validated markers of disease chronicity in humans and elucidated the immunologic mechanism for the dissemination of Leishmania parasites to secondary sites. Moreover, it confirms the prognostic value of LRV1 and IL-17A detection to prevent metastatic leishmaniasis in human patients

Leishmania guyanensis parasites block the activation of the inflammasome by inhibiting maturation of IL-1β.

The various symptomatic outcomes of cutaneous leishmaniasis relates to the type and potency of its underlying inflammatory responses. Presence of the cytoplasmic javax.xml.bind.JAXBElement@52daeaa2 RNA virus-1 (LRV1) within javax.xml.bind.JAXBElement@be11ae5 , worsens lesional inflammation and parasite burden, as the viral dsRNA genome acts as a potent innate immunogen stimulating Toll-Like-Receptor-3 (TLR3). Here we investigated other innate pattern recognition receptors capable of reacting to dsRNA and potentially contributing to LRV1-mediated inflammatory pathology. We included the cytoplasmic dsRNA sensors, namely, the RIG-like receptors (RLRs) and the inflammasome-dependent and -independent Nod-like-receptors (NLRs). Our study found no role for RLRs or inflammasome-dependent NLRs in the pathology of javax.xml.bind.JAXBElement@3dfe8dc4 infection irrespective of its LRV1-status. Further, neither LRV1-bearing javax.xml.bind.JAXBElement@6e03fdb4 ( javax.xml.bind.JAXBElement@6b89952c +) nor LRV1-negative javax.xml.bind.JAXBElement@68bc8c8a ( javax.xml.bind.JAXBElement@2165acf4 ) activated the inflammasome javax.xml.bind.JAXBElement@507a0b31 . Interestingly, similarly to javax.xml.bind.JAXBElement@77fdd4e7 , javax.xml.bind.JAXBElement@7b29ce4e infection induced the up-regulation of the A20 protein, known to be involved in the evasion of inflammasome activation. Moreover, we observed that javax.xml.bind.JAXBElement@77a7dfd3 + promoted the transcription of inflammasome-independent NLRC2 (also called NOD2) and NLRC5. However, only NLRC2 showed some contribution to LRV1-dependent pathology. These data confirmed that the endosomal TLR3 pathway is the dominant route of LRV1-dependent signalling, thus excluding the cytosolic and inflammasome pathways. We postulate that avoidance of the inflammasome pathways is likely an important mechanism of virulence in javax.xml.bind.JAXBElement@77047195 infection irrespective of the LRV1-status

Exacerbated Leishmaniasis Caused by a Viral Endosymbiont can be Prevented by Immunization with Its Viral Capsid.

Recent studies have shown that a cytoplasmic virus called Leishmaniavirus (LRV) is present in some Leishmania species and acts as a potent innate immunogen, aggravating lesional inflammation and development in mice. In humans, the presence of LRV in Leishmania guyanensis and in L. braziliensis was significantly correlated with poor treatment response and symptomatic relapse. So far, no clinical effort has used LRV for prophylactic purposes. In this context, we designed an original vaccine strategy that targeted LRV nested in Leishmania parasites to prevent virus-related complications. To this end, C57BL/6 mice were immunized with a recombinant LRV1 Leishmania guyanensis viral capsid polypeptide formulated with a T helper 1-polarizing adjuvant. LRV1-vaccinated mice had significant reduction in lesion size and parasite load when subsequently challenged with LRV1+ Leishmania guyanensis parasites. The protection conferred by this immunization could be reproduced in naïve mice via T-cell transfer from vaccinated mice but not by serum transfer. The induction of LRV1 specific T cells secreting IFN-γ was confirmed in vaccinated mice and provided strong evidence that LRV1-specific protection arose via a cell mediated immune response against the LRV1 capsid. Our studies suggest that immunization with LRV1 capsid could be of a preventive benefit in mitigating the elevated pathology associated with LRV1 bearing Leishmania infections and possibly avoiding symptomatic relapses after an initial treatment. This novel anti-endosymbiotic vaccine strategy could be exploited to control other infectious diseases, as similar viral infections are largely prevalent across pathogenic pathogens and could consequently open new vaccine opportunities

Recherche de thérapies innovantes dans un modèle murin de myopathies inflammatoires

Inflammatory myopathies are acquired diseases characterized by motor deficit involving an autoimmune myopathy.They are responsible for impairing disability and may be associated with life-threatening complications.Treatment, when they exist, based on the use of corticosteroids in high doses and for long periods.However, 60 % of patients relapse and 20-30 % are readily corticosteroid.Other immunosuppressive treatments are then required (methotrexate , azathioprime , cyclosporine).The side effects of these treatments are inevitable and sometimes severe, which is why the development of new approaches treatment is essential. To test these new approaches, the laboratory developed a mouse model of Experimental Autoimmune Myositis with same Clinical and histological characteristics to polymyositis.In this model we tested the effect of a sub-population of T lymphocyte, nammed regulatory T cells, plays a crucial role in peripheral tolerance self-antigens. In order to control autoimmune manifestations that can replicate the mechanisms of action of Tregs , we sought to amplify in vivo, pharmacologically.At first, we observed the beneficial effect of rapamycin on our model, notably with increase of Tregs.In a second step, we have shown the beneficial role IVIg in the same model in curative.Finally, we investigated the effect of arsenic trioxide ( Trisenox ) in this animal model.Thus, all these data provide insight into the pathophysiology of myositis and to develop a clinical trial with rapamycin .Les myopathies inflammatoires sont des maladies acquises caractérisées par un déficit moteur impliquant une atteinte musculaire auto-immune. Elles sont responsables d'un handicap invalidant et peuvent s'accompagner de complications engageant le pronostic vital. Les traitements, quand ils existent, reposent sur l'utilisation de corticoïdes à fortes doses et au long cours. Cependant, 60% des patients rechutent et 20 à 30 % sont d'emblée corticorésistants. D'autres traitements immunosuppresseurs sont alors nécessaires. Les effets secondaires de ces traitements sont inévitables et parfois sévères. Afin de tester des nouvelles approches, le laboratoire a développé un modèle de Myosite Auto-immune Expérimentale dont les caractéristiques sont similaires à celles de la polymyosite. Dans ce modèle nous avons testé l'effet d'une sous population lymphocytaire T, appelée les lymphocytes T régulateurs, joue un rôle déterminant dans la tolérance périphérique aux antigènes du soi. Afin de contrôler les manifestations auto-immunes, nous avons cherché à les amplifier les Tregs in vivo, pharmacologiquement. D'abord, nous avons observé l'effet bénéfique de la rapamycine sur la sévérité de notre modèle en permettant en particulier d'augmenter le pourcentage de Tregs. Dans un second temps, nous avons montré le rôle bénéfique des immunoglobulines en intraveineux dans ce même modèle en traitement curatif. Enfin, nous nous sommes intéressés à l'effet de l'arsenic trioxyde (Trisenox) dans ce modèle animal.Ainsi, l'ensemble ces données permettent de mieux comprendre la physiopathologie des myosites et de mettre au point un essai clinique avec la rapamycine

”Just invest in ecotourism” : livelihood and poverty in a Cambodian fishing village

FN:s första hållbarhetsmål är att avskaffa all form av fattigdom, överallt. Invånarna i fiskebyar i Kambodja lever ofta i fattigdom och deras liv påverkas av åtskilliga faktorer. Syftet med denna uppsats är att ta reda på hur byborna i en fiskeby försörjer sig och vilka utmaningar som finns mot att ta sig ur fattigdomen. Familjerna försörjer sig till stor del av fisket, men de har även en diversifierad inkomst från kompletterande källor. Det finns en vilja att diversifiera mer än vad de gör i dagsläget men många hindras av sin ekonomiska situation. Många fiskare har skuld till mellanhänder som är svåra att betala av eftersom fisken i sjön samtidigt minskar. De som har möjlighet flyttar när naturresurserna förstörs, men de som inte har råd blir kvar. I Kambodja finns det en utbredd syn om att det är de fattigas ansvar att själva ta sig ur fattigdomen istället för att man ska jämna ut de stora klyftorna i landet

Développement de biosenseurs fluorescents et d’inhibiteurs pour suivre et cibler CDK4/cycline D dans le mélanome

CDK/cyclins play a central role in coordinating cell cycle progression, and in sustaining proliferation of cancer cells, thereby constituting established cancer biomarkers and attractive pharmacological targets. In particular, CDK4/cyclin D, which is responsible for coordinating cell cycle progression through G1 into S phase, is a relevant target in several cancers including melanoma, associated with mutation of CDK4, cyclin D, p16INK4a and pRb.As there are no sensitive and direct approaches to probe CDK4/cyclin D activity in physiological and pathological conditions, the first goal of my thesis has consisted in engineering a fluorescent biosensor to probe this kinase in vitro and in cellulo. Once characterized and validated in vitro, the biosensor was applied to detect CDK4/cyclin D alterations in biopsies from human skin and melanoma xenografts in fluorescence-based activity assays, and in living cancer cells by fluorescence microscopy and timelapse imaging.Moreover, only few inhibitors are currently available to target CDK4/cyclin D and most of them bind the ATP pocket. As such, the second major goal of my thesis project has consisted in identifying non-ATP competitive inhibitors, either through rational design of peptides or by screening small molecule libraries. To this aim, two fluorescent biosensors were engineered which discriminate compounds that target the interface between CDK4 and cyclin D, or that perturb the conformational dynamics of CDK4, respectively, from ATP-pocket binding compounds. Fluorescence-based screening assays performed with these biosensors lead to identification of hits, which were validated and characterized in vitro and in cell proliferation assays, and which constitute promising candidates for selective chemotherapy in melanoma.Les CDK/cyclines jouent un rôle majeur dans la progression du cycle cellulaire et dans le maintien de la prolifération des cellules cancéreuses, constituant ainsi des biomarqueurs clés et des cibles pharmacologiques attractives. Plus particulièrement, l’activité de CDK4/cycline D, kinase responsable de la progression de la phase G1 et de la transition G1/S, est dérégulée dans de nombreux cancers dont le mélanome. Cette hyperactivation est associée à des mutations, à l’amplification ou à la surexpression de CDK4, cycline D, p16INK4a ou encore pRb.Comme aucune approche sensible et directe n’existe pour évaluer l’activité de CDK4/cycline D dans des conditions physiologiques et pathologiques, le premier objectif de ma thèse a consisté à développer un biosenseur fluorescent permettant d’étudier cette kinase in vitro et in cellulo. Une fois caractérisé et validé in vitro, le biosenseur a été appliqué à la détection d’altérations de CDK4/cycline D dans des biopsies de peau humaine et de xénogreffes de mélanome dans des essais fluorescents d’activité kinase, ainsi que dans des cellules cancéreuses vivantes par microscopie de fluorescence et vidéo microscopie.Par ailleurs, peu d’inhibiteurs sont actuellement disponibles pour inhiber CDK4/cycline D et la plupart d’entre eux ciblent la poche de fixation de l’ATP. C’est pourquoi le second objectif de ma thèse a consisté à identifier des inhibiteurs non compétitifs de l’ATP, soit par élaboration rationnelle de peptides, soit par criblage de petites molécules. A cette fin, deux biosenseurs fluorescents ont été développés qui permettent d’identifier respectivement des composés ciblant l’interface entre CDK4 et cycline D ou des inhibiteurs allostériques capables de perturber la dynamique conformationnelle de CDK4. Des essais de criblage par fluorescence réalisés avec ces biosenseurs ont conduit à l’identification de touches qui ont été validées et caractérisées in vitro et dans des essais de prolifération cellulaire, et qui constituent des candidats prometteurs pour une chimiothérapie sélective du mélanome

First malaria infections in a cohort of infants in Benin: biological, environmental and genetic determinants. Description of the study site, population methods and preliminary results

Objectives: Malaria infection of the placenta during pregnancy was found to be associated with infant susceptibility to malaria. Other factors such as the intensity of malaria transmission and the nutritional status of the child might also play a role, which has not been adequately taken into account in previous studies. The aim of this study was to assess precisely the parts played by environmental, nutritional and biological determinants in first malaria infections, with a special interest in the role of placental infection. The objective of this paper is not to present final results but to outline the rationale of the study, to describe the methods used and to report baseline data. Design: A cohort of infants followed with a parasitological (symptomatic and asymptomatic parasitaemia) and nutritional follow-up from birth to 18 months. Ecological, entomological and behavioural data were collected along the duration of the study. Setting: A rural area in Benin with two seasonal peaks in malaria transmission. Participants: 656 infants of women willing to participate in the study, giving birth in one of the three maternity clinics and living in one of the nine villages of the study area. Primary Outcome Measures: The time and frequency of first malaria parasitaemias in infants, according to Plasmodium falciparum infection of the placenta. Results: 11% of mothers had a malaria-infected placenta at delivery. Mosquito catches made every 6 weeks in the area showed an average annual P falciparum entomological inoculation rate of 15.5, with important time and space variations depending on villages. Similarly, the distribution of rainfalls, maximal during the two rainy seasons, was heterogeneous over the area. Conclusions: Considering the multidisciplinary approach of all factors potentially influencing the malaria status of newborn babies, this study should bring evidence on the implication of placental malaria in the occurrence of first malaria infections in infants

Trends in obesity and diabetes across Africa from 1980 to 2014: an analysis of pooled population-based studies

Background: The 2016 Dar Es Salaam Call to Action on Diabetes and Other non-communicable diseases (NCDs) advocates national multi-sectoral NCD strategies and action plans based on available data and information from countries of sub-Saharan Africa and beyond. We estimated trends from 1980 to 2014 in age-standardized mean body mass index (BMI) and diabetes prevalence in these countries, in order to assess the co-progression and assist policy formulation. Methods: We pooled data from African and worldwide population-based studies which measured height, weight and biomarkers to assess diabetes status in adults aged ≥ 18 years. A Bayesian hierarchical model was used to estimate trends by sex for 200 countries and territories including 53 countries across five African regions (central, eastern, northern, southern and western), in mean BMI and diabetes prevalence (defined as either fasting plasma glucose of ≥ 7.0 mmol/l, history of diabetes diagnosis, or use of insulin or oral glucose control agents). Results: African data came from 245 population-based surveys (1.2 million participants) for BMI and 76 surveys (182 000 participants) for diabetes prevalence estimates. Countries with the highest number of data sources for BMI were South Africa (n = 17), Nigeria (n = 15) and Egypt (n = 13); and for diabetes estimates, Tanzania (n = 8), Tunisia (n = 7), and Cameroon, Egypt and South Africa (all n = 6). The age-standardized mean BMI increased from 21.0 kg/m2 (95% credible interval: 20.3–21.7) to 23.0 kg/m2 (22.7–23.3) in men, and from 21.9 kg/m2 (21.3–22.5) to 24.9 kg/m2 (24.6–25.1) in women. The age-standardized prevalence of diabetes increased from 3.4% (1.5–6.3) to 8.5% (6.5–10.8) in men, and from 4.1% (2.0–7.5) to 8.9% (6.9–11.2) in women. Estimates in northern and southern regions were mostly higher than the global average; those in central, eastern and western regions were lower than global averages. A positive association (correlation coefficient ≃ 0.9) was observed between mean BMI and diabetes prevalence in both sexes in 1980 and 2014. Conclusions: These estimates, based on limited data sources, confirm the rapidly increasing burden of diabetes in Africa. This rise is being driven, at least in part, by increasing adiposity, with regional variations in observed trends. African countries’ efforts to prevent and control diabetes and obesity should integrate the setting up of reliable monitoring systems, consistent with the World Health Organization’s Global Monitoring System Framework