ABSTRACT
The immune response is regulated, in part, by effector cells whose activation requires multiple signals. For example, T cells require signals emanating from the T cell antigen receptor and co-stimulatory molecules for full activation. Here, we present evidence indicating that IgE-mediated hypersensitivity reactions in vivo also require cognate signals to activate mast cells. Immediate hypersensitivity reactions in the conjunctiva are ablated in mice deficient in eotaxin-1, despite normal numbers of tissue mast cells and levels of IgE. To further define the co-stimulatory signals mediated by chemokine receptor 3 (CCR3), an eotaxin-1 receptor, effects of CCR3 blockade were tested with an allergic conjunctivitis model and in ex vivo isolated connective tissue-type mast cells. Our results show that CCR3 blockade significantly suppresses allergen-mediated hypersensitivity reactions as well as IgE-mediated mast cell degranulation. We propose that a co-stimulatory axis by CCR3, mainly stimulated by eotaxin-1, is pivotal in mast cell-mediated hypersensitivity reactions.
Subject(s)
Allergens/metabolism , Chemokine CCL11/immunology , Conjunctivitis, Allergic/immunology , Conjunctivitis, Allergic/prevention & control , Glycoproteins/metabolism , Mast Cells/metabolism , Receptors, CCR3/antagonists & inhibitors , Receptors, CCR3/metabolism , Allergens/immunology , Animals , Cats , Cell Degranulation/immunology , Chemokine CCL11/metabolism , Conjunctiva/immunology , Conjunctiva/pathology , Conjunctivitis, Allergic/genetics , Glycoproteins/immunology , Immunoglobulin E/blood , Mast Cells/immunology , Mast Cells/pathology , Mice , Mice, Inbred BALB C , Mice, Knockout , Receptors, CCR3/genetics , Receptors, CCR3/immunology , Signal Transduction/genetics , Signal Transduction/immunology , Skin/immunology , Skin/pathology , VaccinationABSTRACT
PURPOSE: To characterize the transcriptome of allergic conjunctivitis mediated by eosinophil-related chemokine receptor CCR3 and to identify a candidate for possible therapeutic intervention in eosinophilic inflammation of the eye. METHODS: Mice were sensitized to ragweed pollen, and allergic conjunctivitis was induced by an allergen challenge. The induction of allergic conjunctivitis was used to determine whether an inhibition of CCR3 would suppress eosinophilic inflammation and the allergen-induced immediate hypersensitivity reaction. In addition, sensitized mice were treated with a CCR3 antagonist or an anti-CCR3 antibody before the allergen challenge. Eosinophilic inflammation was evaluated histologically at 24 hours after the allergen challenge. Transcriptional changes with or without a blockade of CCR3 were determined by microarray analyses. RESULTS: Blockade of CCR3 significantly suppressed allergen-induced clinical signs, mast cell degranulation, and eosinophilic inflammation. Clustering analysis of the transcriptome during the early phase identified clusters of genes associated with distinct biological processes. A CCR2 ligand, monocyte chemoattractant protein (MCP)-1, was identified in the cluster of genes related to mast cell activation. MCP-1, an attractant of monocytes but not eosinophils, was in the top 10 transcripts among the genome and was suppressed by CCR3 blockade. Importantly, antibody blockade of MCP-1 suppressed the eosinophilic inflammation significantly. CONCLUSIONS: CCR3 regulates not only the eosinophilic inflammation but also the clinical signs and mast cell degranulation. The CCR3-mediated transcriptome is characterized by many biological processes associated with mast cell activation. Among these CCR3-mediated processes, MCP-1 was found to be significantly involved in eosinophilic inflammation probably by an indirect pathway.
Subject(s)
Chemokine CCL2/physiology , Conjunctivitis, Allergic/genetics , Hypersensitivity, Immediate/prevention & control , Receptors, CCR3/physiology , Ambrosia , Animals , Capillary Permeability , Cell Degranulation , Cell Movement , Conjunctivitis, Allergic/immunology , Disease Models, Animal , Eosinophils/immunology , Hypersensitivity, Immediate/immunology , Immunoglobulin E/blood , Immunoglobulin G/blood , Mast Cells/immunology , Mice , Mice, Inbred Strains , Oligonucleotide Array Sequence Analysis , Piperidines/pharmacology , Pollen/immunology , Receptors, CCR3/antagonists & inhibitors , Transcription, GeneticABSTRACT
A practical asymmetric synthesis of both enantiomers of the immunosuppressive FTY720-phosphate (2) was accomplished, and the enantiomers were pharmacologically evaluated. Several lipases showed considerable activity and enantioselectivity for O-acylation of N-acetyl FTY720 (3) or N-benzyloxycarbonyl FTY720 (7) in combination with vinyl acetate or benzyl vinyl carbonate as the acyl donors. The synthesis using the lipase-catalyzed acylation as the key step produced the enantiomerically pure (>99.5% ee) enantiomers of 2 in multigram quantities. (S)-Isomer of 2 had more potent binding affinities to S1P(1,3,4,5) and inhibitory activity on lymphocyte migration toward S1P than (R)-2, suggesting that (S)-isomer of 2 is responsible for the immunosuppressive activity after administration of 1. Severe bradycardia was observed in anesthetized rats when (S)-2 was administered intravenously, while (R)-2 had no clear effect on heart rate up to 0.3 mg/kg.
