title: Leishmania donovani chaperonin 10 regulates parasite internalization and intracellular survival in human macrophages.
abstract: Protozoa of the genus Leishmania infect macrophages in their mammalian hosts causing a spectrum of diseases known as the leishmaniases. The search for leishmania effectors that support macrophage infection is a focus of significant interest. One such candidate is leishmania chaperonin 10 (CPN10) which is secreted in exosomes and may have immunosuppressive properties. Here, we report for the first time that leishmania CPN10 localizes to the cytosol of infected macrophages. Next, we generated two genetically modified strains of Leishmania donovani (Ld): one strain overexpressing CPN10 (CPN10+++) and the second, a CPN10 single allele knockdown (CPN10+/-), as the null mutant was lethal. When compared with the wild-type (WT) parental strain, CPN10+/- Ld showed higher infection rates and parasite loads in human macrophages after 24 h of infection. Conversely, CPN10+++ Ld was associated with lower initial infection rates. This unexpected apparent gain-of-function for the knockdown could have been explained either by enhanced parasite internalization or by enhanced intracellular survival. Paradoxically, we found that CPN10+/- leishmania were more readily internalized than WT Ld, but also displayed significantly impaired intracellular survival. This suggests that leishmania CPN10 negatively regulates the rate of parasite uptake by macrophages while being required for intracellular survival. Finally, quantitative proteomics identified an array of leishmania proteins whose expression was positively regulated by CPN10. In contrast, many macrophage proteins involved in innate immunity were negatively regulated by CPN10. Taken together, these findings identify leishmania CPN10 as a novel effector with broad based effects on macrophage cell regulation and parasite survival.
authors.affiliation: Department of Medicine, University of British Columbia, Vancouver, BC, Canada.
authors.forename: Lucie
authors.initials: L
authors.lastname: Colineau
authors.affiliation: Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany.
authors.forename: Joachim
authors.initials: J
authors.lastname: Clos
authors.affiliation: Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC, Canada.
authors.forename: Kyung-Mee
authors.initials: KM
authors.lastname: Moon
authors.affiliation: Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC, Canada.
authors.forename: Leonard J
authors.initials: LJ
authors.lastname: Foster
authors.affiliation: Department of Medicine, University of British Columbia, Vancouver, BC, Canada. nreiner@mail.ubc.ca.
authors.forename: Neil E
authors.initials: NE
authors.lastname: Reiner
mesh_terms: D002470:Cell Survival; D002478:Cells, Cultured; D018835:Chaperonin 10 / Q000235:genetics / Q000378:metabolism*; D004705:Endocytosis; D015870:Gene Expression; D055785:Gene Knockdown Techniques; D054884:Host-Pathogen Interactions; D006801:Humans; D007893:Leishmania donovani / Q000235:genetics / Q000472:pathogenicity / Q000502:physiology*; D008264:Macrophages / Q000469:parasitology*; D040901:Proteomics; D015800:Protozoan Proteins / Q000032:analysis; D037521:Virulence Factors / Q000235:genetics / Q000378:metabolism*
chemical_list: D018835:Chaperonin 10; D015800:Protozoan Proteins; D037521:Virulence Factors
keywords: Chaperonin; Heat shock protein; Host–pathogen interaction; Leishmania donovani; Parasitic infection; Virulence factor