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ABSTRACT: In mammals, the T-cell receptor (TCR) complex expressed on mature T-cells consists of α/β or γ/δ clonotypic heterodimers non-covalently associated with four invariant chains forming the CD3 complex (CD3γ, CD3δ, CD3ε and CD3ζ). The TCR is the unit implicated in the antigenic peptide recognition whereas the CD3 subunits present as three different dimers (δ-ε, γ-ε and ζ-ζ) in the receptor complex participate to the signal transduction and are indispensable for the expression of the TCR at the cell surface. We report the cloning, characterization and expression analysis of CD3γ/δ and CD3ε genes in an amphibian urodele, the Mexican axolotl. Amino acid comparisons show that important motifs and residues were preserved between the axolotl CD3 chains and various vertebrate CD3ε, CD3γ, CD3δ and CD3γ/δ chains. During ontogeny, CD3ε transcripts are first detected in the dorsal region of tail-bud embryos before thymus organogenesis. CD3γ/δ transcripts are first detected in the head of 4-week-old larvae. A cross-reactive polyclonal anti-CD3ε antibody was used for the co-immunoprecipitation of the two CD3 proteins of 25 and 29 kDa, respectively, associated with the 90-kDa αβ TCR heterodimer.
Immunogenetics 07/2011; 63(12):847-53. · 2.93 Impact Factor
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ABSTRACT: Replacement therapy with exogenous factor VIII (FVIII) to treat haemorrhages or used in prophylaxis induces inhibitory anti-FVIII immunoglobulin G (IgG) in some patients with haemophilia A. Therapeutic strategies to prevent the onset of the deleterious anti-FVIII immune response are still lacking. Maternal IgG is transferred to the offspring during fetal and neonatal life. While protecting the offspring from bacterial and viral infections, maternal IgG may alter the repertoires of T and B lymphocytes, and may impair vaccination in early infancy. Using haemophilic mice, we demonstrate that the transfer of maternal anti-FVIII IgG modulates the onset of anti-FVIII inhibitory IgG in early adulthood. The protective effect is reproduced upon reconstitution of naive mice with anti-FVIII IgG, suggesting that the reduced ability to mount an anti-FVIII immune response is the result of an interference between circulating anti-FVIII IgG and the administered FVIII rather than to a profound remodelling of lymphocyte repertoires occurring during the ontogeny of the immune system.
Immunology 12/2010; 131(4):549-55. · 3.32 Impact Factor
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ABSTRACT: The immunogenicity of therapeutic factor VIII (FVIII) in patients with haemophilia A remains a critical issue in patient management. This review describes the immunological processes involved in the activation of the immune system against FVIII, with a particular focus on the role of endocytic receptors for the recognition of FVIII by antigen-presenting cells.
Thrombosis and Haemostasis 09/2010; 104(6):1093-8. · 5.04 Impact Factor
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Arthritis & Rheumatism 09/2009; 60(9):2848-9; author reply 2849-51. · 7.87 Impact Factor
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ABSTRACT: CD4+CD25+ regulatory T cells (Tregs) play a critical role in preventing immune aggression. One way in which Tregs exert immune surveillance activities is by modifying the function of antigen presenting cells (APCs) such as dendritic cells, macrophages, and B cells. Tregs can induce apoptosis of APCs or inhibit their activation and function, thereby regulating subsequent innate and adaptive immune responses. These actions of Tregs are mediated by both soluble factors (interleukin [IL]-10, transforming growth factor-beta, perforins, granzymes) and cell-associated molecules (cytotoxic T lymphocyte antigen 4, lymphocyte activation gene-3, CD18, neuropilin-1, LFA-1/CD11a, CD39), of which cytotoxic T lymphocyte antigen 4 has a key role. However, in autoimmunity, chronically activated APCs under the influence of intracellular signaling pathways, such as phosphatidyl inositol 3 kinase, JAK-STAT, MAPK, and nuclear factor-kappaB pathways, can escape surveillance by Tregs, leading to the activation of T cells that are refractory to suppression by Tregs. Moreover, APCs and APC-derived inflammatory cytokines such as tumor necrosis factor, IL-6, IL-1beta, and IL-23 can render Tregs defective and can also reciprocally enhance the activity of the IL-17-producing pathogenic Th17 T cell subset. Emerging knowledge of the importance of APC-Treg interactions in maintaining immune tolerance and aberrations in this cross talk in autoimmune diseases provides a rationale for therapeutic approaches specifically targeting this axis of the immune system.
American Journal Of Pathology 05/2009; 174(5):1575-87. · 4.89 Impact Factor
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ABSTRACT: Procoagulant factor VIII (FVIII) is either produced endogenously under physiologic conditions, or administered exogenously as a therapeutic hemostatic drug in patients with hemophilia A. In the circulation, FVIII interacts with a multitude of glycoproteins, and may be used for coagulation at the sites of bleeding, eliminated by scavenger cells, or processed by the immune system, either as a self-constituent or as a foreign antigen. The fate of FVIII is dictated by the immune status of the individual, the location of FVIII in the body at a given time point, and the inflammatory microenvironment. It also depends on the local concentration of FVIII and of each interacting partner, and on the affinity of the respective interactions. FVIII, by virtue of its promiscuity, thus constitutes the core of a dynamic network that links the coagulation cascade, cells of the immune system, and, presumably, the inflammatory compartment. We describe the different interactions that FVIII is prone to establish during its life cycle, with a special focus on players of the innate and adaptive immune response. Lessons can be learned from understanding the dynamics of FVIII interactions--lessons that should pave the way to the conception of long-lasting hemostatic drugs devoid of iatrogenic immunogenicity.
Blood 08/2008; 112(2):240-9. · 9.90 Impact Factor
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ABSTRACT: Von Willebrand factor (VWF) has been proposed to reduce the immunogenicity of therapeutic factor VIII (FVIII) in patients with hemophilia A. Using FVIII-deficient mice, we compared the immunogenicity of different preparations of plasma-derived (pd) and recombinant (r) FVIII. Treatment of mice with pdFVIII induced significantly lower titers of FVIII inhibitors, as measured by ELISA and in vitro coagulation assays, compared with rFVIII. Furthermore, pre-incubation of rFVIII with excess VWF significantly reduced rFVIII immunogenicity. Our data confirm that pdFVIII induces lower levels of inhibitors than rFVIII, and that VWF is an immuno-chaperone molecule for FVIII.
Haematologica 11/2007; 92(10):1423-6. · 6.42 Impact Factor
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ABSTRACT: Gammadelta T cells localize at mammalian epithelial surfaces to exert both protective and regulatory roles in response to infections. We have previously characterized the Mexican axolotl (Ambystoma mexicanum) T cell receptor delta (TRD) chain. In this study, TRD repertoires in spleen, liver, intestine and skin from larvae, pre-adult and adult axolotls were examined and compared to the thymic TRD repertoire. A TRDV transcript without N/D diversity, TRDV1S1-TRDJ1, dominates the TRD repertoires until sexual maturation. In adult tissues, this canonical transcript is replaced by another dominant TRDV1S1-TRDJ1 transcript. In the thymus, these two transcripts are detected early in development. Our results suggest that gammadelta T cells that express the canonical TRDV1S1-TRDJ1 transcript emerge from the thymus and colonize the peripheral tissues, where they are selectively expanded by recurrent ligands. This particular situation is probably related to the neotenic state and the slow development of the axolotl. In thymectomized axolotls, TRD repertoires appear different from those of normal axolotls, suggesting that extrathymic gammadelta T cell differentiation could occur. Gene expression analysis showed the importance of the gut in T cell development.
European Journal of Immunology 07/2007; 37(6):1621-33. · 5.10 Impact Factor
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Suryasarathi Dasgupta,
Ana-Maria Navarrete,
Jagadeesh Bayry,
Sandrine Delignat,
Bharath Wootla, Sébastien André,
Olivier Christophe,
Michelina Nascimbeni,
Marc Jacquemin,
Luisa Martinez-Pomares,
Teunis B H Geijtenbeek,
Arnaud Moris,
Jean-Marie Saint-Remy,
Michel D Kazatchkine,
Srinivas V Kaveri,
Sébastien Lacroix-Desmazes
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ABSTRACT: Several therapeutic self-proteins elicit immune responses when administered to patients. Such adverse immune responses reduce drug efficacy. To induce an immune response, a protein must interact with different immune cells, including antigen-presenting cells, T cells, and B cells. Each cell type recognizes distinct immunogenic patterns on antigens. Mannose-terminating glycans have been identified as pathogen-associated molecular patterns that are essential for internalization of microbes by antigen-presenting cells, leading to presentation. Here, we have investigated the importance of exposed mannosylation on an immunogenic therapeutic self-protein, procoagulant human factor VIII (FVIII). Administration of therapeutic FVIII to hemophilia A patients induces inhibitory anti-FVIII antibodies in up to 30% of the cases. We demonstrate that entry of FVIII into human dendritic cells (DC) leading to T cell activation, is mediated by mannose-terminating glycans on FVIII. Further, we identified macrophage mannose receptor (CD206) as a candidate endocytic receptor for FVIII on DC. Saturation of mannose receptors on DC with mannan, and enzymatic removal of mannosylated glycans from FVIII lead to reduced T cell activation. The interaction between FVIII and CD206 was blocked by VWF, suggesting that, under physiological conditions, the intrinsic mannose-dependent immunogenicity of FVIII is quenched by endogenous immunochaperones. These data provide a link between the mannosylation of therapeutic self-proteins and their iatrogenic immunogenicity. Such a link would be of special relevance in the context of replacement therapy where mechanisms of central and peripheral tolerance have not been established during ontogeny because of the absence of the antigen.
Proceedings of the National Academy of Sciences 06/2007; 104(21):8965-70. · 9.68 Impact Factor
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ABSTRACT: Nontemplate (N)-nucleotide addition by the terminal dideoxynucleotidyl transferase (TdT) at the junctions of rearranging V( D) J gene segments greatly contribute to antigen-receptor diversity. TdT has been identified in several vertebrate species, where it is highly conserved. We report here the isolation of two forms of TdT mRNA in an amphibian, the Mexican axolotl. The isoform TdT1 shares all of the conserved structural motifs required for TdT activity and displays an average of 50-58% similarity at the amino acid level with TdT of other species. The second axolotl TdT variant ( TdT2) differs from TdT1 by a 57-amino acid deletion located between amino acids 165-222 of TdT1, including the first helix-hairpin-helix DNA-binding motif. During ontogeny, TdT products are first detected in the head of 6-week-old larvae and further in the head and trunk of 8-month-old larvae. These developmental stages correspond to the first detection of RAG1 and antigen-receptor (TCRbeta and IgHmicro) products in axolotl larvae. Our results suggest that in contrast to mammalian development, N diversity occurs early in axolotl development to diversify the primary repertoire. Phylogenetic analyses reveal that TdT and DNA polymerase mu(Pol mu) genes are closely related, and that both enzymes were already present in the common ancestor of jawed vertebrates.
Immunogenetics 07/2004; 56(3):204-13. · 2.93 Impact Factor
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ABSTRACT: Nontemplate (N)-nucleotide addition by the terminal dideoxynucleotidyl transferase (TdT) at the junctions of rearranging V(D)J gene segments greatly contribute to antigen-receptor diversity. TdT has been identified in several vertebrate species, where it is highly conserved. We report here the isolation of two forms of TdT mRNA in an amphibian, the Mexican axolotl. The isoform TdT1 shares all of the conserved structural motifs required for TdT activity and displays an average of 50–58% similarity at the amino acid level with TdT of other species. The second axolotl TdT variant (TdT2) differs from TdT1 by a 57-amino acid deletion located between amino acids 165–222 of TdT1, including the first helix–hairpin–helix DNA-binding motif. During ontogeny, TdT products are first detected in the head of 6-week-old larvae and further in the head and trunk of 8-month-old larvae. These developmental stages correspond to the first detection of RAG1 and antigen-receptor (TCR and IgH) products in axolotl larvae. Our results suggest that in contrast to mammalian development, N diversity occurs early in axolotl development to diversify the primary repertoire. Phylogenetic analyses reveal that TdT and DNA polymerase (Pol ) genes are closely related, and that both enzymes were already present in the common ancestor of jawed vertebrates.
Immunogenetics 01/2004; 56(3):204-213. · 2.93 Impact Factor
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ABSTRACT: Mammals and birds have two major populations of T cells, based on the molecular composition and biological properties of their antigen receptors (TCR). alpha beta T cells recognize antigenic peptides linked to major histocompatibility complex (MHC) molecules, and gamma delta T cells recognize native peptide or non-peptide antigens independently of MHC. Very little is known about gamma delta T cells in ectothermic vertebrates. We have cloned and characterized the TCRdelta chains of an urodele amphibian, the Mexican axolotl (Ambystoma mexicanum). The Cdelta domain is structurally similar to its mammalian homologues and the transmembrane domain is very well conserved. Four of the six Valpha regions that can associate with Calpha (Valpha2, Valpha3, Valpha5 and Valpha6) can also associate with Cdelta, but no specific Vdelta regions were found. This suggests that the axolotl TRD locus is nested within the TRA locus, as in mammals, and that this organization has been present in all tetrapod vertebrates and in the common ancestor of Lissamphibians and mammals, for over 400 million years. Two Jdelta regions were identified, but no Ddelta segments were clearly recognized at the Vdelta-Jdelta junctions. This results in shorter and less variable CDR3 loops than in other vertebrates and the size range of the Vdelta-Jdelta junctions is similar to that of mammalian immunoglobulin light chains. Equivalent quantities of TRD mRNA were found in the lymphoid organs, and in the skin and the intestines of normal and thymectomized axolotls. The analysis of several Valpha/delta6-Cdelta and Vbeta7-Cbeta junctions showed that both the TCRdelta and the TCRbeta chains were limited in diversity in thymectomized axolotls.
European Journal of Immunology 06/2002; 32(5):1349-58. · 5.10 Impact Factor
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ABSTRACT: Mammals and birds have two major populations of T cells, based on the molecular composition and biological properties of their antigen receptors (TCR). α β T cells recognize antigenic peptides linked to major histocompatibility complex (MHC) molecules, and γ δ T cells recognize native peptide or non-peptide antigens independently of MHC. Very little is known about γ δ T cells in ectothermic vertebrates. We have cloned and characterized the TCRδ chains of an urodele amphibian, the Mexican axolotl (Ambystoma mexicanum). The Cδ domain is structurally similar to its mammalian homologues and the transmembrane domain is very well conserved. Four of the six Vα regions that can associate with Cα (Vα2, Vα3, Vα5 and Vα6) can also associate with Cδ, but no specific Vδ regions were found. This suggests that the axolotl TRD locus is nested within the TRA locus, as in mammals, and that this organization has beenpresent in all tetrapod vertebrates and in the common ancestor of Lissamphibians and mammals, for over 400 million years. Two Jδ regions were identified, but no Dδ segments were clearly recognized at the Vδ-Jδ junctions. This results in shorter and less variable CDR3 loops than in other vertebrates and the size range of the Vδ-Jδ junctions is similar to that of mammalian immunoglobulin light chains. Equivalent quantities of TRD mRNA were found in the lymphoid organs, and in the skin and the intestines of normal and thymectomized axolotls. The analysis of several Vα/δ6-Cδ and Vβ7-Cβ junctions showed that both the TCRδ and the TCRβ chains were limited in diversity in thymectomized axolotls.
European Journal of Immunology 04/2002; 32(5):1349 - 1358. · 5.10 Impact Factor
