Immunophysiology and Intracellular Parasitism  

  HEADDr. MILON Geneviève /
  MEMBERSBRULE Chantal / DE LA LLAVE Emilie / Dr. LANG Thierry / LECOEUR Hervé / Dr. OSORIO y FORTEA José / Dr. PRINA Eric

  Annual Report

In the entity “Immunophysiology and Intracellular Parasitism”, there is a continuous focus on the Leishmania life traits in their mammal hosts. We attempt to extend our understanding of the stepwise processes that assess the long-term interactions Leishmania establish and renew with i) the mammal phagocytic leukocytes left unexposed to any exogenous signal, ii) the phagocytic leukocytes exposed to a balanced combination of counter- and pro-inflammatory signals i.e. with leukocytes hosting persisting Leishmania amastigotes. High throughput screening readout assays have been selected to assist in designing novel interventions aimed to target both the cell-cycling and the persisting amastigote populations. This integrative approach - initiated since years - is expected to provide novel data on the dynamic features of both 1) the amastigotes and 2) the mammal host niche(s) where these amastigotes either cycle or persist.

Designing reliable in vitro model systems for deciphering the stepwise developmental programs of Leishmania in the mammal phagocytic leukocyte lineages.

Though we are aware that each discrete phase, in the Leishmania-loaded dermis, assesses the otherwise versatile activities of many different leukocyte lineages [macrophages, macrophage related dendritic cells/ DCs neutrophils], we decided to first focus on the phagocytes the Leishmania amastigotes subvert as bona fide host cells. Affymetrix GeneChip oligonucleotide array technology was applied to total RNA carefully extracted from L. amazonensis–loaded bone marrow derived (a) macrophages and (b) DCs. Many robust signatures of the silent entry/establishment of the Leishmania amastigotes have been documented for both the macrophages and the DCs ; one carefully selected software application allowed extracting many biologically relevant transcriptional signatures of L. amazonensis–loaded phagocytic leukocytes.

Designing reliable mouse models for deciphering the stepwise developmental programs of Leishmania in mammal host tissues they rely on for their perpetuation.

The C57BL/6 that have received, intradermally in the ear, transgenic bioluminescent L.major metacyclic promastigotes offer the relevant experimental conditions for exploring in real time simultaneously i) the parasite load fluctuations, ii) the ear features, iii) transcriptional immune signatures captured with quantitative real time PCR. In this context, while longitudinally probing transcriptional signatures in both tissues we are indeed decoding (a) when the Leishmania amastigote-hosting phagocytic leukocytes are becoming sources of signals to CD3 T lymphocytes that are retained in the draining lymph node and (b) when these activated CD3 lymphocytes are recruited in the Leishmania–loaded ears. Additional studies are in progress to highlight (a) how dermis-protective regulatory T lymphocytes are subverted to help amastigotes-loaded macrophages to consolidate their functions as bona fide host cells of cell-cycling amastigotes, (b) when and how a balanced activation of both parasite-clearing CD3 lymphocytes and dermis-protective regulatory T lymphocytes is triggered, (c) the subsequent unique immune and dynamic signatures of the skin where persist the amastigotes that are transmissible to the sand flies.

Keywords: Parasitism / Tissue remodeling / Tissue microbiology / Parasite developmental biology / Leishmania / Phagocytic leukocytes


1. Lang T., Goyard S., Lebastard M., Saklani H. & Milon G. 2005. on line 1-Nov-2004) Bioluminescent Leishmaniaexpressing luciferase for rapid an high throughput screening of drugs acting on amastigote-harbouring macrophages and for quantitative real-time monitoring ofparasitism features in living mice. Cell. Microbiol. 7: 383-392 (PMID 15679841).

2. Buffet PA, MilonG, Brousse V, Correas JM, Dousset B, Couvelard A, Kianmanesh R, Farges O, Sauvanet A, Paye F, Ungeheuer MN, Ottone C, Khun H, Fiette L, Guigon G, Huerre M, Mercereau-Puijalon O, David PH.2006(Epub 2005 Dec 29) Ex vivoperfusion of human spleens maintains clearing and processing functions. Blood107 : 3745-3752 (PMID 16384927).

3. Osorio y Fortea J., Prina, E., de La Llave E., Lecoeur, H., Lang T., Milon G. 2007. Unveiling pathways used by Leishmania amazonensis amastigotes to subvert macrophage function. Immunol. Rev. 219:66-74 (PMID 17850482).

4. Prina, E., E. Roux, D. Mattei, and G. Milon. 2007. Leishmania DNA is rapidly degraded following parasite death : an analysis by microscopy and real-time PCR. 9: 1307-1315 (PMID 17890124).

5. Lecoeur, H., P. A. Buffet, G. Morizot, S. Goyard, G. Guigon, G. Milon, and T. Lang.2007. Optimization of topical therapy for Leishmania major localized cutaneous leishmaniasis using a reliable C57Bl/6 model. Plos.Neglected Trop.Dis1:1-10 (PMID 18060082).

Activity Reports 2007 - Institut Pasteur
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