Article

Dendritic cells in Leishmania major infections: mechanisms of parasite uptake, cell activation and evidence for physiological relevance.

Department of Dermatology, University Medicine, Johannes Gutenberg-University Mainz, Langenbeckstrasse 1, 55131, Mainz, Germany.
Medical Microbiology and Immunology (Impact Factor: 3.55). 09/2012; 201(4):581-92. DOI: 10.1007/s00430-012-0261-2
Source: PubMed

ABSTRACT Leishmaniasis is one of the most important infectious diseases worldwide; a vaccine is still not available. Infected dendritic cells (DC) are critical for the initiation of protective Th1 immunity against Leishmania major. Phagocytosis of L. major by DC leads to cell activation, IL-12 release and (cross-) presentation of Leishmania antigens by DC. Here, we review the role of Fcγ receptor- and B cell-mediated processes for parasite internalization by DC. In addition, the early events after parasite inoculation that consist of mast cell activation, parasite uptake by skin-resident macrophages (MΦ), followed by neutrophil and monocyte immigration and DC activation are described. All these events contribute significantly to antigen processing in infected DC and influence resulting T cell priming in vivo. A detailed understanding of the role of DC for the development of efficient anti-Leishmania immunity will aid the development of potent anti-parasite drugs and/or vaccines.

0 Bookmarks
 · 
116 Views
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: BACKGROUND: To date, no universally effective and safe vaccine has been developed for general human use. Leishmania donovani Peroxidoxin-1 (LdPxn-1) is a member of the antioxidant family of proteins and is predominantly expressed in the amastigote stage of the parasite. The aim of this study was to evaluate the immunogenicity and protective efficacy of LdPxn-1 in BALB/c mice in heterologous DNA-Protein immunization regimen in the presence of fusion murine granulocyte-macrophage colony-stimulating factor (mGMCSF) DNA adjuvant. METHODOLOGY AND PRINCIPAL FINDINGS: A fusion DNA of LdPxn1 and mGMCSF was cloned into a modified pcDNA vector. To confirm the expression in mammalian system, Chinese hamster ovary cells were transfected with the plasmid vector containing LdPxn1 gene. BALB/c mice were immunized twice with pcDNA-mGMCSF-LdPxn-1 or pcDNA-LdPxn1 DNA and boosted once with recombinant LdPxn-1 protein. Three weeks after the last immunization, mice were infected with Leishmania major promastigotes. The result showed that immunization with pcDNA-mGMCSF-LdPxn1 elicited a mixed Th-1/Th-2 immune response with significantly higher production of IFN-γ than controls. Intracellular cytokine staining of antigen-stimulated spleen cells showed that immunization with this antigen elicited significantly higher proportion of CD4+ T cells that express IFN-γ, TNF-α, or IL-2. The antigen also induced significantly higher proportion of multipotent CD4+ cells that simultaneously express the three Th-1 cytokines. Moreover, a significant reduction in the footpad swelling was seen in mice immunized with pcDNA-mGMCSF-LdPxn1 antigen. Expression study in CHO cells demonstrated that pcDNA-mGMCSF-LdPxn-1 was expressed in mammalian system. CONCLUSION: The result demonstrates that immunization of BALB/c mice with a plasmid expressing LdPxn1 in the presence of mGMCSF adjuvant elicits a strong specific immune response with high level induction of multipotent CD4+ cells that mediate protection of the mice from Leishmania major infection. To our knowledge, this is the first study showing the vaccine potential of Leishmania peroxidoxin -1.
    PLoS Neglected Tropical Diseases 12/2014; 8(12):e3391. · 4.49 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: To date, no universally effective and safe vaccine has been developed for general human use. Leishmania donovani Peroxidoxin-1 (LdPxn-1) is a member of the antioxidant family of proteins and is predominantly expressed in the amastigote stage of the parasite. The aim of this study was to evaluate the immunogenicity and protective efficacy of LdPxn-1 in BALB/c mice in heterologous DNA-Protein immunization regimen in the presence of fusion murine granulocyte-macrophage colony-stimulating factor (mGMCSF) DNA adjuvant. A fusion DNA of LdPxn1 and mGMCSF was cloned into a modified pcDNA vector. To confirm the expression in mammalian system, Chinese hamster ovary cells were transfected with the plasmid vector containing LdPxn1 gene. BALB/c mice were immunized twice with pcDNA-mGMCSF-LdPxn-1 or pcDNA-LdPxn1 DNA and boosted once with recombinant LdPxn-1 protein. Three weeks after the last immunization, mice were infected with Leishmania major promastigotes. The result showed that immunization with pcDNA-mGMCSF-LdPxn1 elicited a mixed Th-1/Th-2 immune response with significantly higher production of IFN-γ than controls. Intracellular cytokine staining of antigen-stimulated spleen cells showed that immunization with this antigen elicited significantly higher proportion of CD4+ T cells that express IFN-γ, TNF-α, or IL-2. The antigen also induced significantly higher proportion of multipotent CD4+ cells that simultaneously express the three Th-1 cytokines. Moreover, a significant reduction in the footpad swelling was seen in mice immunized with pcDNA-mGMCSF-LdPxn1 antigen. Expression study in CHO cells demonstrated that pcDNA-mGMCSF-LdPxn-1 was expressed in mammalian system. The result demonstrates that immunization of BALB/c mice with a plasmid expressing LdPxn1 in the presence of mGMCSF adjuvant elicits a strong specific immune response with high level induction of multipotent CD4+ cells that mediate protection of the mice from Leishmania major infection. To our knowledge, this is the first study showing the vaccine potential of Leishmania peroxidoxin -1.
    PLoS neglected tropical diseases. 12/2014; 8(12):e3391.
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The role of different dendritic cell (DC) subsets in priming and maintenance of immunity against Leishmania major (L. major) infection is debated. The transcription factor Batf3 is essential for the development of mouse CD103+ DCs and some functions of CD8α+ DCs. We found that CD103+ DCs were significantly reduced in the dermis of Batf3-deficient C57BL/6 mice. Batf3-/- mice developed exacerbated and unresolved cutaneous pathology following a low dose of i.d. L. major infection in the ear pinnae. Parasite load was increased 1000-fold locally and expanded systemically. Batf3 deficiency did not affect L. major antigen presentation to T cells, which was directly exerted by CD8α- conventional DCs (cDCs) in the skin draining LN. However, CD4+ T-cell differentiation in the LN and skin was skewed to non-protective Treg- and Th2-cell subtypes. CD103+ DCs are major IL-12 producers during L. major infection. Local Th1 immunity was severely hindered, correlating with impaired IL-12 production and reduction in CD103+ DC numbers. Adoptive transfer of WT but not IL12p40-/- Batf3-dependent DCs significantly improved anti-L. major response in infected Batf3-/- mice. Our results suggest that IL-12 production by Batf3-dependent CD103+ DCs is crucial for maintenance of local Th1 immunity against L. major infection.This article is protected by copyright. All rights reserved
    European Journal of Immunology 10/2014; 45(1). · 4.52 Impact Factor