title: Genetically Modified Live Attenuated Leishmania donovani Parasites Induce Innate Immunity through Classical Activation of Macrophages That Direct the Th1 Response in Mice.
abstract: Visceral leishmaniasis (VL) causes significant mortality and there is no effective vaccine. Previously, we have shown that genetically modified Leishmania donovani parasites, here described as live attenuated parasites, induce a host protective adaptive immune response in various animal models. In this study, we demonstrate an innate immune response upon infection with live attenuated parasites in macrophages from BALB/c mice both in vitro and in vivo. In vitro infection of macrophages with live attenuated parasites (compared to that with wild-type [WT] L. donovani parasites) induced significantly higher production of proinflammatory cytokines (tumor necrosis factor alpha [TNF-α], interleukin-12 [IL-12], gamma interferon [IFN-γ], and IL-6), chemokines (monocyte chemoattractant protein 1/CCL-2, macrophage inflammatory protein 1α/CCL-3, and IP-10), reactive oxygen species (ROS), and nitric oxide, while concomitantly reducing anti-inflammatory cytokine IL-10 and arginase-1 activities, suggesting a dominant classically activated/M1 macrophage response. The classically activated response in turn helps in presenting antigen to T cells, as observed with robust CD4(+) T cell activation in vitro. Similarly, parasitized splenic macrophages from live attenuated parasite-infected mice also demonstrated induction of an M1 macrophage phenotype, indicated by upregulation of IL-1β, TNF-α, IL-12, and inducible nitric oxide synthase 2 and downregulation of genes associated with the M2 phenotype, i.e., the IL-10, YM1, Arg-1, and MRC-1 genes, compared to WT L. donovani-infected mice. Furthermore, an ex vivo antigen presentation assay showed macrophages from live attenuated parasite-infected mice induced higher IFN-γ and IL-2 but significantly less IL-10 production by ovalbumin-specific CD4(+) T cells, resulting in proliferation of Th1 cells. These data suggest that infection with live attenuated parasites promotes a state of classical activation (M1 dominant) in macrophages that leads to the generation of protective Th1 responses in BALB/c mice.
authors.affiliation: Division of Emerging and Transfusion Transmitted Disease, Center for Biologics Evaluation and Research, Food and Drug Administration, Silver Spring, Maryland, USA.
authors.forename: Parna
authors.initials: P
authors.lastname: Bhattacharya
authors.affiliation: Division of Emerging and Transfusion Transmitted Disease, Center for Biologics Evaluation and Research, Food and Drug Administration, Silver Spring, Maryland, USA.
authors.forename: Ranadhir
authors.initials: R
authors.lastname: Dey
authors.affiliation: Flow Cytometry Core, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland, USA.
authors.forename: Pradeep K
authors.initials: PK
authors.lastname: Dagur
authors.affiliation: Experimental Immunology Branch, National Cancer Institute, NIH, Bethesda, Maryland, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Kruhlak
authors.affiliation: Division of Emerging and Transfusion Transmitted Disease, Center for Biologics Evaluation and Research, Food and Drug Administration, Silver Spring, Maryland, USA.
authors.forename: Nevien
authors.initials: N
authors.lastname: Ismail
authors.affiliation: Division of Emerging and Transfusion Transmitted Disease, Center for Biologics Evaluation and Research, Food and Drug Administration, Silver Spring, Maryland, USA.
authors.forename: Alain
authors.initials: A
authors.lastname: Debrabant
authors.affiliation: Division of Emerging and Transfusion Transmitted Disease, Center for Biologics Evaluation and Research, Food and Drug Administration, Silver Spring, Maryland, USA.
authors.forename: Amritanshu B
authors.initials: AB
authors.lastname: Joshi
authors.affiliation: Office of Vaccines Research and Review, Center for Biologics Evaluation and Research, Food and Drug Administration, Silver Spring, Maryland, USA.
authors.forename: Adovi
authors.initials: A
authors.lastname: Akue
authors.affiliation: Office of Vaccines Research and Review, Center for Biologics Evaluation and Research, Food and Drug Administration, Silver Spring, Maryland, USA.
authors.forename: Mark
authors.initials: M
authors.lastname: Kukuruga
authors.affiliation: Office of Vaccines Research and Review, Center for Biologics Evaluation and Research, Food and Drug Administration, Silver Spring, Maryland, USA.
authors.forename: Kazuyo
authors.initials: K
authors.lastname: Takeda
authors.affiliation: Institute of Molecular Medicine, New Delhi, India.
authors.forename: Angamuthu
authors.initials: A
authors.lastname: Selvapandiyan
authors.affiliation: Flow Cytometry Core, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland, USA.
authors.forename: John Philip
authors.initials: JP
authors.lastname: McCoy
authors.affiliation: Division of Emerging and Transfusion Transmitted Disease, Center for Biologics Evaluation and Research, Food and Drug Administration, Silver Spring, Maryland, USA Hira.Nakhasi@fda.hhs.gov.
authors.forename: Hira L
authors.initials: HL
authors.lastname: Nakhasi
mesh_terms: D056704:Adaptive Immunity; D000818:Animals; D018932:Chemokine CCL2 / Q000235:genetics / Q000276:immunology; D054405:Chemokine CCL3 / Q000235:genetics / Q000276:immunology; D005260:Female; D006801:Humans; D007113:Immunity, Innate; D007371:Interferon-gamma / Q000235:genetics / Q000276:immunology; D018664:Interleukin-12 / Q000235:genetics / Q000276:immunology; D015850:Interleukin-6 / Q000235:genetics / Q000276:immunology; D007893:Leishmania donovani / Q000235:genetics* / Q000276:immunology*; D007898:Leishmaniasis, Visceral / Q000235:genetics / Q000276:immunology* / Q000469:parasitology; D008264:Macrophages / Q000276:immunology*; D051379:Mice; D008807:Mice, Inbred BALB C; D018417:Th1 Cells / Q000276:immunology*
chemical_list: D018932:Chemokine CCL2; D054405:Chemokine CCL3; D015850:Interleukin-6; D018664:Interleukin-12; D007371:Interferon-gamma