Éditeur(s) : HAL CCSD
Résumé : International audience
Given the clinical success of commercial amphotericin B lipid products, investigators have begun making generic formulations of liposomal amphotericin B. Generic medicines are an attractive approach to help decrease the cost and accessibility to healthcare, provided that appropriate studies are performed to ensure bioequivalence with the parent product. This is of particular concern for liposomal drugs such as amphotericin B where liposomes are used as a carrier system to reduce the toxicity of the active agent. A favorable therapeutic profile for this form of the drug has to include the proper chemical composition along with strictly controlled manufacturing processes. Studies have shown that a comparison of liposomal amphotericin B products with different or the same chemical compositions, using different methods of production, will vary in size, and have significantly dissimilar in vitro and in vivo toxicities along with reduced efficacy. These results underscore the importance of establishing appropriate bioequivalence testing for liposome products to ensure uniformity of their therapeutic index
Medical Mycology

hal-01259233
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01259233
DOI : 10.1093/mmy/myv111
PUBMED : 26768369

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Liposomal amphotericin B (LAmb) may fail to heal Leishmania infantum visceral leishmaniasis (VL) in the immunodeficient host. There are currently no guidelines on how to treat such patients and efficacy of miltefosine monotherapy seems limited in this indication. We present 2 cases of patients with VL and AIDS for which LAmb had to be interrupted (one because of toxicity, one because of treatment failure) and who were treated effectively with pentamidine followed by miltefosine.
ISSN: 1383-5769

hal-01509592
https://hal.archives-ouvertes.fr/hal-01509592
PUBMED : 27353022

Éditeur(s) : HAL CCSD Instituto Oswaldo Cruz, Ministério da Saúde
Résumé : International audience
Leishmania are protozoan parasites that show remarkable diversity, as revealed by the various clinical forms of leishmaniasis, which can range from mild skin lesions to severe metastatic cutaneous/mucosal lesions. The exact nature and extent of Leishmania phenotypic diversity in establishing infection is not fully understood. In order to try to understand some aspects of this diversity, we subcutaneously infected BALB/c mice with first and second generation subclones of a L. amazonensis strain isolated from a patient (BA125) and examined in vivo lesion growth rate and antimony susceptibility. In vivo fast-, medium- and slow-growing subclones were obtained; moreover, fast-growing subclones could generate slow-growing subclones and inversely, revealing the continuous generation of diversity after passage into mice. No antimony-resistant subclone appeared, probably a rare occurrence. By tagging subclone cells with a L. amazonensis genomic cosmid library, we found that only a very small number of founding cells could produce lesions. Leishmania clones transfected with in vivo selected individual cosmids were also diverse in terms of lesion growth rate, revealing the cosmid-independent intrinsic characteristics of each clone. Our results suggest that only a few of the infecting parasites are able to grow and produce lesions; later, within the cell mixture of each lesion, there coexist several parasite populations with different potentialities to grow lesions during the next infection round. This may reflect a sort of programmed heterogeneity of individual parasites, favoring the survival of some individuals in various environmental conditions.
ISSN: 0074-0276

hal-01489007
https://hal-univ-perp.archives-ouvertes.fr/hal-01489007

Éditeur(s) : HAL CCSD American Society of Tropical Medicine and Hygiene
Résumé : International audience
Anti-leishmaniasis drug resistance is a common problem worldwide. The aim of this study was to inventory the general in vitro level of sensitivity of Leishmania isolates circulating in French Guiana and to highlight potential in vitro pentamidine-resistant isolates. This sensitivity study was conducted on 36 patient-promastigote isolates for seven drugs (amphotericin B, azithromycin, fluconazole, meglumine antimoniate, miltefosine, paromomycin, and pentamidine) using the Cell Counting Kit-8 viability test. The IC50 values obtained were heterogeneous. One isolate exhibited high IC50 values for almost all drugs tested. Pentamidine, which is the first-line treatment in French Guiana, showed efficacy at very low doses (mean of 0.0038 μg/mL). The concordance of the in vitro pentamidine results with the patients' clinical outcomes was 94% (K = 0.82).
ISSN: 0002-9637

inserm-01481512
http://www.hal.inserm.fr/inserm-01481512
http://www.hal.inserm.fr/inserm-01481512/document
http://www.hal.inserm.fr/inserm-01481512/file/2017%2C%20Ginouves%20-%20In%20vitro%20sensitivity%20of%20cutaneous%20leishmania.pdf
DOI : 10.4269/ajtmh.16-0373

Éditeur(s) : HAL CCSD American Society for Microbiology
Résumé : International audience
Human leishmaniasis are widely spread diseases with different clinical forms caused by about 20 species within the Leishmania genus. Leishmania species identification is relevant for therapeutic management and prognosis, especially for cutaneous and muco-cutaneous forms. Several methods are available to identify Leishmania species from culture, but they have not been standardized for the majority of the currently described species, with the exception of MultiLocus Enzyme Electrophoresis. Moreover, these techniques are expensive, time-consuming and not available in all laboratories. Within the last decade, mass spectrometry (MS) has been adapted for microorganism identification, including Leishmania However, no commercial reference mass spectral database is available. In this study, a reference mass spectral library (MSL) for Leishmania isolates, accessible through a free web-based application (mass spectral identification, MSI), was constructed and tested. It includes mass spectral data for 33 different Leishmania species, including species that infect humans, animals and phlebotomine vectors. Four laboratories on two continents evaluated MSI performance using 268 samples of which 231 were Leishmania strains. All Leishmania strains, but one, were correctly identified at least at the complex level. A risk of species misidentification within the L. donovani, L. guyanensis and L. braziliensis complexes was observed, as already reported with other techniques. The tested application was reliable, with identification results comparable to those obtained with reference methods, but with a more favorable cost-efficiency ratio. This free online identification system relies on a scalable database and can be implemented directly in the user's computers.
ISSN: 0095-1137

hal-01571305
https://hal.archives-ouvertes.fr/hal-01571305
DOI : 10.1128/JCM.00845-17
PUBMED : 28724559

Résumé : Les études écologiques sont maintenant considérées comme prometteuses en raison de leur capacité à intégrer dans un même modèle autant des facteurs individuels que populationnels. Le mouvement récent de l’open data pourrait jouer un rôle important dans la pérennisation des démarches multidisciplinaires. Cette thèse montre que l’association des méthodes écologiques aux données publiques permet d’éclairer sous un angle nouveau des problématiques des maladies infectieuses.En Guyane Française, des méthodes écologiques dites de séries temporelles couplées aux données climatiques libres ont contribué à une meilleure compréhension du rôle du climat sur la dynamique de la transmission du paludisme, de la leishmaniose cutanée ainsi que de l’histoplasmose disséminée. L’utilisation de méthodes écologiques sur des données libres de la littérature scientifique concernant la séroprévalence toxoplasmose dans les populations humaines a permis d’identifier les principaux facteurs influençant le niveau de séroprévalence globale et indirectement du risque de toxoplasmose congénital associé. L’association de données onusiennes à des méthodes écologiques a permis de montrer qu’une prévalence importante d’ascaridiose est associée à une réduction par 10 de l’incidence du paludisme et l’impact significatif de la corruption sur la mortalité juvéno-infantile et sur les résistances aux anti-tuberculeux. Ces études montrent que l’association des méthodes écologiques aux données publiques permet d’éclairer sous un angle nouveau des problématiques des maladies infectieuses. Ce type d‘étude fournit la flexibilité nécessaire à l’étude des interactions complexes des nombreux déterminants de la santé.
Ecological studies are now considered promising because of their ability to integrate as well as individual factors than populational ones in the same model. The recent open data movement could play an important role in the sustainability of multidisciplinary approaches. The studies developed in this thesis show that the combination of ecological methods with open data could give original results in the issues of infectious diseases.In French Guiana, ecological methods called time series, coupled with open climate data, have contributed to a better understanding of the role of climate on the dynamics of malaria, cutaneous leishmaniasis and disseminated histoplasmosis. The use of ecological methods with open data from the scientific literature concerning toxoplasmosis seroprevalence in human populations has permitted to identify the main factors influencing the level of overall seroprevalence and indirectly to estimate the associated risk of congenital toxoplasmosis.The combination of UN data to ecological methods has shown that a high prevalence of ascariasis is associated with a reduction from 10 in the incidence of malaria and that corruption has a significant impact on child mortality and resistance to TB.The various studies developed in this thesis show that the combination of ecological methods to public data sheds a new light on the issues of infectious diseases. This type of study provides the flexibility to study the complex interactions of many determinants of health.

http://www.theses.fr/2011AGUY0482/document

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
The parasitic life cycle of Leishmania includes an extracellular promastigote stage that occurs in the gut of the insect vector. During that period, the sucrose metabolism and more specifically the first glycosidase of this pathway are essential for growth and survival of the parasite. We investigated the expression of the invertase BfrA in the promastigote and amastigote stages of three parasite species representative of the three various clinical forms and of various geographical areas, namely Leishmania major, L. donovani and L. braziliensis. Thereafter, we cloned, overexpressed and biochemically characterized this invertase BfrA from L. major, heterologously expressed in both Escherichia coli and L. tarentolae. For all species, expression levels of BfrA mRNA were correlated to the time of the culture and the parasitic stage (promastigotes > amastigotes). BfrA exhibited no activity when expressed as a glycoprotein in L. tarentolae but proved to be an invertase when not glycosylated, yet owing low sequence homology with other invertases from the same family. Our data suggest that BfrA is an original invertase that is located inside the parasite. It is expressed in both parasitic stages, though to a higher extent in promastigotes. This work provides new insight into the parasite sucrose metabolism
ISSN: 0008-6215

hal-01187142
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01187142
DOI : 10.1016/j.carres.2015.07.001
PUBMED : 26279524

Éditeur(s) : HAL CCSD
Résumé : After a review of knowledge, attitudes and practices related to leishmaniasis in Amazonia, this work focused on the vegetal species used for its cure. Utilization of geographic and cultural diffusion index allowed to characterize Pan-Amazonian antileishmanial taxa and to investigate the mechanisms allowing for their diffusion. Consistency between traditional use and laboratory results were looked for. Two " knowledge, attitudes and practices " surveys were conducted amongst the Chayahuita (Peru) and along the upper and middle Oyapock river (French Guiana, Teko and Wayãpi groups). These allowed us to refine the knowledge and perception of the disease in these cultural groups, to define patterns in the therapeutic itinerary, and to make an inventory of antileishmanial plant species. Thirty one species used by the Chayahuita were collected and submitted to in vitro assays on axenic amastigotes of Leishmania amazonensis. Pseudoelephantopus spicatus (Asteraceae) is one of the most active and most frequently used plant. From this species, piptocarphol derivatives, very active against Leishmania in vitro, were isolated along with ursolic acid. Presence of these molecules justifies the use of this species as traditional antileishmanial remedy by the Chayahuita.
Après avoir dressé un inventaire des connaissances, attitudes et pratiques concernant les leishmanioses en Amazonie d'après la littérature, le présent travail s'est focalisé sur les espèces végétales connues et utilisées dans le traitement de ces maladies. L'utilisation d'indices de diffusion (géographique, culturelle) a permis de caractériser des taxons antileishmaniens panamazoniens et de définir certains mécanismes impliqués dans leur diffusion. Des cohérences entre usages traditionnels et résultats de laboratoire ont été recherchés. Deux enquêtes de type " connaissance, attitudes et pratiques " effectuées au sein du groupe chayahuita (Pérou), et sur le haut et moyen cours du fleuve Oyapock (Guyane, communautés teko et wayãpi) ont permis d'affiner les connaissances sur la perception de cette maladie dans ces différents groupes culturels, de comprendre les recours aux différentes thérapeutiques et de dresser un inventaire des espèces médicinales utilisées. Trente et une espèces collectées chez les Chayahuita ont été soumises à des essais in vitro sur amastigotes axéniques de Leishmania amazonensis. Pseudoelephantopus spicatus (Asteraceae) compte parmi les espèces les plus actives et les plus fréquemment utilisées, et des dérivés du piptocarphol très actifs sur les parasites in vitro ont été isolés conjointement à l'acide ursolique. La présence de ces molécules permet de justifier en partie l'usage de cette espèce comme antileishmanien traditionnel par les Chayahuita.
https://tel.archives-ouvertes.fr/tel-00590977

tel-00590977
https://tel.archives-ouvertes.fr/tel-00590977
https://tel.archives-ouvertes.fr/tel-00590977/document
https://tel.archives-ouvertes.fr/tel-00590977/file/ThA_se_Odonne_light.pdf