Chikungunya intra-vector dynamics in Aedes albopictus from Lyon (France) upon exposure to a human viremia-like dose range reveals vector barrier’s permissiveness and supports local epidemic potential

Arbovirus emergence and epidemic potential, as approximated by the vectorial capacity formula, depends on host and vector parameters, including the vector’s intrinsic ability to replicate then transmit the pathogen known as vector competence. Vector competence is a complex, time-dependent,quantitative phenotype influenced by biotic and abiotic factors. A combination of experimental andmodelling approaches is required to assess arbovirus intra-vector dynamics and estimate epidemicpotential. In this study, we measured infection, dissemination, and transmission dynamics of chikungunya virus (CHIKV) in a field-derived Aedes albopictus population (Lyon, France) after oral exposureto a range of virus doses spanning human viraemia. Statistical modelling indicates rapid and efficientCHIKV progression in the vector mainly due to an absence of a dissemination barrier, with 100% ofthe infected mosquitoes ultimately exhibiting a disseminated infection, regardless of the virus dose.Transmission rate data revealed a time-dependent, but overall weak, transmission barrier, with individuals transmitting as soon as 2 days post-exposure (dpe) and >50% infectious mosquitoes at 6dpe for the highest dose. Based on these experimental intra-vector dynamics data, epidemiologicalsimulations conducted with an agent-based model showed that even at low mosquito biting rates,CHIKV could trigger outbreaks locally. Together, this reveals the epidemic potential of CHIKV upontransmission by Aedes albopictus in mainland Franc

Cardiovascular disease, chronic kidney disease, and diabetes mortality burden of cardiometabolic risk factors from 1980 to 2010: A comparative risk assessment

Background: High blood pressure, blood glucose, serum cholesterol, and BMI are risk factors for cardiovascular diseases and some of these factors also increase the risk of chronic kidney disease and diabetes. We estimated mortality from cardiovascular diseases, chronic kidney disease, and diabetes that was attributable to these four cardiometabolic risk factors for all countries and regions from 1980 to 2010. Methods: We used data for exposure to risk factors by country, age group, and sex from pooled analyses of population-based health surveys. We obtained relative risks for the effects of risk factors on cause-specific mortality from meta-analyses of large prospective studies. We calculated the population attributable fractions for each risk factor alone, and for the combination of all risk factors, accounting for multicausality and for mediation of the effects of BMI by the other three risks. We calculated attributable deaths by multiplying the cause-specific population attributable fractions by the number of disease-specific deaths. We obtained cause-specific mortality from the Global Burden of Diseases, Injuries, and Risk Factors 2010 Study. We propagated the uncertainties of all the inputs to the final estimates. Findings: In 2010, high blood pressure was the leading risk factor for deaths due to cardiovascular diseases, chronic kidney disease, and diabetes in every region, causing more than 40% of worldwide deaths from these diseases; high BMI and glucose were each responsible for about 15% of deaths, and high cholesterol for more than 10%. After accounting for multicausality, 63% (10·8 million deaths, 95% CI 10·1-11·5) of deaths from these diseases in 2010 were attributable to the combined effect of these four metabolic risk factors, compared with 67% (7·1 million deaths, 6·6-7·6) in 1980. The mortality burden of high BMI and glucose nearly doubled from 1980 to 2010. At the country level, age-standardised death rates from these diseases attributable to the combined effects of these four risk factors surpassed 925 deaths per 100 000 for men in Belarus, Kazakhstan, and Mongolia, but were less than 130 deaths per 100 000 for women and less than 200 for men in some high-income countries including Australia, Canada, France, Japan, the Netherlands, Singapore, South Korea, and Spain. Interpretation: The salient features of the cardiometabolic disease and risk factor epidemic at the beginning of the 21st century are high blood pressure and an increasing effect of obesity and diabetes. The mortality burden of cardiometabolic risk factors has shifted from high-income to low-income and middle-income countries. Lowering cardiometabolic risks through dietary, behavioural, and pharmacological interventions should be a part of the global response to non-communicable diseases. Funding: UK Medical Research Council, US National Institutes of Health. © 2014 Elsevier Ltd

Le rôle de p53 au cours de l'infection par le virus du chikungunya chez le mammifère et l'insecte

The chikungunya virus (CHIKV) belongs to Alphavirus genus which can be found in an ecological but not taxonomic group named arboviruses (for arthropod-borne viruses) indicating viruses transmitted by an arthropod vector hematophagous to a vertebrate host, during a blood meal. Alphaviruses are transmitted by bloodsucking arthropods, mainly mosquitoes, to humans and animals causing debilitating disease. While in human CHIKV disease is characterized by fever, headache, and a typical acute infection, sometimes followed by persistent arthralgia or myalgia, in mosquito the infection does not seem to cause significant pathology. Since the re-emergency of CHIKV at La Réunion in 2005-2006 Alphavirus-host or vector interactions are more and more studied at the cellular and molecular level. Indeed, the identification of cellular and viral factors involved in the human pathology and mosquito chronicity could allow to develop antiviral treatments. The regulated apoptotic cell death and interferon Type-I immune response are strong antiviral defence participating in rapid viral elimination. Moreover, it has been demonstrated that p53 plays a central role in the regulation of cell death and Type-I interferon signalling pathway during different viral infections. Finally, quite recently it has been suggested that in Dengue virus-infected insect, p53-induced cell death was associated to the permissiveness and resistance of vector. In this way my work was to study the potential role of p53 and p53 isoforms on cellular outcome and viral infection in mammal and insect infected with Alphavirus, mainly chikungunya virus and to a lesser extent Sindbis virus. First, in order to investigate a potential function of p53 on viral infection in mammal and insect, infected with chikungunya virus and Sindbis virus, we have generated p53 knockout human skeletal muscle cell line. In addition, thanks to a collaboration, we obtained Drosophila melanogaster p53-/- mutant strain. We observed an opposite effect of p53 knockout on chikungunya virus infection in in vitro human cells and in vivo in Drosophila melanogaster. Indeed, we have demonstrated an increase in CHIKV infection in p53 knockout human cells and a decrease in CHIKV and Sindbis virus replication in the whole flies p53-/- mutants. Several analyses on CHIKV-infected p53 knockout human cell line have demonstrated an immune antiviral effect of p53 through Type-I interferon production and signalling pathway and a negative impact on neighbouring cells protection. Moreover, it seems that infected-p53 knockout cells are not able to enhance IFN production and signalling. Further experiments are required to decipher the activity of p53 on immune signalling. In parallel, we have shown that CHIKV-induced cell death was p53-independent as no p53 family target genes were regulated and the knockout of p53 did not decreased or delayed the virus-induced cell death. Secondly, we have investigated a possible function of ∆40p53 and ∆133p53 isoforms on CHIKV infection. We have set up and carried out (i) human muscle cell line overexpressing endogenous ∆40p53 using CRISPR/Cas9 technology and (ii) an inducible-system overexpressing ∆40p53 or ∆133p53 protein isoforms. We observed that endogenous overexpression of ∆40p53 isoform led to a decrease in CHIKV infection, but the mechanism remains unclearLe virus du chikungunya (CHIKV) appartient au genre des Alphavirus qui peuvent faire partis d’un groupe écologique mais pas taxonomique, nommée les Arboviruses (pour « Arthropod-borne viruses ») signifiant des virus transmis par des arthropodes vecteur hématophages à des hôtes vertébrés, au cours d’un repas sanguin. Les alphavirus sont transmis, principalement par des moustiques, à l’Homme et aux animaux causant des maladies invalidantes. Tandis que le CHIKV induit chez l’Homme une maladie caractérisée par de la fièvre, des maux de tête et une infection aigue typique, elle peut s’accompagner de douleurs articulaires et musculaires persistantes ; alors que chez le moustique l’infection ne semble pas causer de pathologie. A la suite de la réémergence du CHIKV au cours de l’épidémie de 2005-2006 à La Réunion, les interactions entre les alphavirus et leur hôte ou vecteur sont de plus en plus étudiées au niveau cellulaire et moléculaire. En effet, l’identification de facteurs cellulaires et viraux impliqués dans la pathologie de l’Homme et la chronicité du vecteur moustique permettrait de développer des traitements antiviraux. La mort cellulaire programmée (apoptose) et la réponse immunitaire de Type-I assurent une réponse antivirale rapide, participant à l’élimination du virus. De plus, il a été démontré que la protéine p53 joue un rôle central dans la régulation de l’apoptose et dans la voie de signalisation de la réponse interféron de Type-I. Pour finir, il a été suggéré récemment que l’infection d’un insecte par le virus de la Dengue, la morte cellulaire induite par p53 était associée à la permissivité et à la résistance du vecteur. L’objectif de mon travail était d’étudier le rôle possible de la protéine p53 et des isoformes p53 sur la réponse cellulaire et l’infection virale chez le mammifère et l’insecte infectés par des alphavirus, en prenant le virus du chikungunya comme modèle principal et dans une moindre mesure le virus Sindbis. Dans un premier temps, nous avons généré une lignée cellulaire de muscle squelettique humaine délété de la protéine p53 et grâce à une collaboration, nous avons obtenu des souches Drosophila melanogaster p53-/- mutantes. Nous avons observé un effet opposé de la délétion de p53 sur l’infection du chikungunya entre la lignée cellulaire humaine et la drosophile. En effet, nous avons démontré que la délétion de p53 induisait une augmentation de l’infection du CHIKV dans les cellules humaines et une diminution de la réplication virale du CHIKV et du virus Sindbis chez les drosophiles. Plusieurs analyses ont montré que la protéine p53 était impliquée dans la réponse interféron de Type-I, indépendamment de son implication dans la régulation de la mort cellulaire au cours de l’infection du CHIKV dans les cellules humaines. En effet, la délétion de p53 ne permet pas la production d’interféron Bêta et par conséquence la production des gènes cibles de la voie de signalisation. L’activité de p53 sur la réponse immune va être étudiée plus en détails dans des expériences futures. En parallèle, nous avons également montré que la mort cellulaire induite par le virus CHIKV était indépendante de p53 car aucuns des gènes cibles de p53 étudiés n’était régulés et la délétion de p53 n’a pas diminué ou retardé l’induction de la mort cellulaire à la suite de l’infection virale. Dans un deuxième temps, nous avons étudié le rôle possible des isoformes ∆133p53 et ∆40p53 sur l’infection du CHIKV. Pour cela nous avons mis au point (i) des cellules humaines de muscle qui présente une surexpression endogène de l’isoforme ∆40p53, générée par la technologie CRISPR/Cas9 et (ii) un système inductible pour surexprimer transitoirement les protéines des deux isoformes. Nous avons observé que la surexpression endogène de l’isoforme ∆40p53 conduisait à une diminution de l’infection, cependant le mécanisme est inconn

Δ40p53 isoform up-regulates netrin-1/UNC5B expression and potentiates netrin-1 pro-oncogenic activity

International audienceNetrin-1, a secreted protein recently characterized as a relevant cancer therapeutic target, is the antiapoptotic ligand of the dependence receptors deleted in colorectal carcinoma and members of the UNC5H family. Netrin-1 is overexpressed in several aggressive cancers where it promotes cancer progression by inhibiting cell death induced by its receptors. Interference of its binding to its receptors has been shown, through the development of a monoclonal neutralizing antinetrin-1 antibody (currently in phase II of clinical trial), to actively induce apoptosis and tumor growth inhibition. The transcription factor p53 was shown to positively regulate netrin-1 gene expression. We show here that netrin-1 could be a target gene of the N-terminal p53 isoform Δ40p53, independent of full-length p53 activity. Using stable cell lines, harboring wild-type or null-p53, in which Δ40p53 expression could be finely tuned, we prove that Δ40p53 binds to and activates the netrin-1 promoter. In addition, we show that forcing immortalized human skeletal myoblasts to produce the Δ40p53 isoform, instead of full-length p53, leads to the up-regulation of netrin-1 and its receptor UNC5B and promotes cell survival. Indeed, we demonstrate that netrin-1 interference, in the presence of Δ40p53, triggers apoptosis in cancer and primary cells, leading to tumor growth inhibition in preclinical in vivo models. Finally, we show a positive correlation between netrin-1 and Δ40p53 gene expression in human melanoma and colorectal cancer biopsies. Hence, we propose that inhibition of netrin-1 binding to its receptors should be a promising therapeutic strategy in human tumors expressing high levels of Δ40p53

Chikungunya intra-vector dynamics in Aedes albopictus from Lyon (France) upon exposure to a human viremia-like dose range reveals vector barrier’s permissiveness and supports local epidemic potential

International audienceArbovirus emergence and epidemic potential, as approximated by the vectorial capacity formula, depends on host and vector parameters, including the vector’s intrinsic ability to replicate then transmit the pathogen known as vector competence. Vector competence is a complex, time dependent, quantitative phenotype influenced by biotic and abiotic factors. A combination of experimental and modelling approaches is required to assess arbovirus intra-vector dynamics and estimate epidemic potential. In this study, we measured infection, dissemination, and transmission dynamics of chikungunya virus (CHIKV) in a field-derived Aedes albopictus population (Lyon, France) after oral exposure to a range of virus doses spanning human viraemia. Statistical modelling indicates rapid and efficient CHIKV progression in the vector mainly due to an absence of a dissemination barrier, with 100% of the infected mosquitoes ultimately exhibiting a disseminated infection, regardless of the virus dose. Transmission rate data revealed a time-dependent, but overall weak, transmission barrier, with individuals transmitting as soon as 2 days post-exposure (dpe) and =50% infectious mosquitoes at 6 dpe for the highest dose. Based on these experimental intra-vector dynamics data, epidemiological simulations conducted with an agent-based model showed that even at low mosquito biting rates, CHIKV could trigger outbreaks locally. Together, this reveals the epidemic potential of CHIKV upon transmission by Aedes albopictus in mainland France

The Global Cardiovascular Risk Transition Associations of Four Metabolic Risk Factors with National Income, Urbanization, and Western Diet in 1980 and 2008

Background-It is commonly assumed that cardiovascular disease risk factors are associated with affluence and Westernization. We investigated the associations of body mass index (BMI), fasting plasma glucose, systolic blood pressure, and serum total cholesterol with national income, Western diet, and, for BMI, urbanization in 1980 and 2008