ABSTRACT
Peroxisome proliferator-activated receptor-gamma (PPARgamma), a member of the nuclear hormone receptor superfamily originally shown to play an important role in adipocyte differentiation and glucose homeostasis, is now known to regulate inflammatory responses. Given the importance of endothelial cell (EC)-derived chemokines in regulating leukocyte function and trafficking, we studied the effects of PPARgamma ligands on the expression of chemokines induced in ECs by the Th1 cytokine IFN-gamma. Treatment of ECs with PPARgamma activators significantly inhibited IFN-gamma-induced mRNA and protein expression of the CXC chemokines IFN-inducible protein of 10 kDa (IP-10), monokine induced by IFN-gamma (Mig), and IFN-inducible T-cell alpha-chemoattractant (I-TAC), whereas expression of the CC chemokine monocyte chemoattractant protein-1 was not altered. PPARgamma activators decreased IFN-inducible protein of 10 kDa promoter activity and inhibited protein binding to the two NF-kappaB sites but not to the IFN-stimulated response element ISRE site. Furthermore, PPARgamma ligands inhibited the release of chemotactic activity for CXC chemokine receptor 3 (CXCR3)-transfected lymphocytes from IFN-gamma-stimulated ECs. These data suggest that anti-diabetic PPARgamma activators might attenuate the recruitment of activated T cells at sites of Th1-mediated inflammation.
Subject(s)
Chemokines, CXC/antagonists & inhibitors , Endothelium, Vascular/immunology , Endothelium, Vascular/metabolism , Intercellular Signaling Peptides and Proteins , Interferon-gamma/pharmacology , Receptors, Cytoplasmic and Nuclear/metabolism , T-Lymphocytes/metabolism , Transcription Factors/metabolism , Chemokine CXCL10 , Chemokine CXCL11 , Chemokine CXCL9 , Chemokines, CXC/metabolism , Chemokines, CXC/pharmacology , Chemotaxis/drug effects , Docosahexaenoic Acids/pharmacology , Dose-Response Relationship, Immunologic , Eicosapentaenoic Acid/pharmacology , Endothelium, Vascular/cytology , Endothelium, Vascular/drug effects , Humans , Interferon-gamma/antagonists & inhibitors , Microbodies/drug effects , Microbodies/metabolism , NF-kappa B/antagonists & inhibitors , NF-kappa B/metabolism , Promoter Regions, Genetic/drug effects , Promoter Regions, Genetic/immunology , Prostaglandin D2/analogs & derivatives , Prostaglandin D2/pharmacology , Pyrimidines , RNA, Messenger/antagonists & inhibitors , RNA, Messenger/biosynthesis , Receptors, CXCR3 , Receptors, Chemokine/antagonists & inhibitors , Receptors, Cytoplasmic and Nuclear/antagonists & inhibitors , Saphenous Vein , T-Lymphocytes/drug effects , Transcription Factors/antagonists & inhibitorsABSTRACT
Eotaxin is an eosinophil-selective chemokine that is constitutively expressed in a variety of organs such as the intestine. Previous studies have demonstrated that the recruitment of eosinophils during inflammation is partially dependent on eotaxin, but the function of constitutive eotaxin during homeostasis has not been examined. To elucidate the biological role of this molecule, we now examine tissue levels of eosinophils in healthy states in wild-type and eotaxin-deficient mice. The lamina propria of the jejunum of wild-type mice is demonstrated to express eotaxin mRNA, but not mRNA for the related monocyte chemoattractant proteins. Wild-type mice contained readily detectable eosinophils in the lamina propria of the jejunum. In contrast, mice genetically deficient in eotaxin had a large selective reduction in the number of eosinophils residing in the jejunum. The reduction of tissue eosinophils was not limited to the jejunum, because a loss of thymic eosinophils was also observed in eotaxin-deficient mice. These studies demonstrate that eotaxin is a fundamental regulator of the physiological trafficking of eosinophils during healthy states. Because a variety of chemokines are constitutively expressed, their involvement in the baseline trafficking of leukocytes into nonhematopoietic tissue should now be considered.
Subject(s)
Chemokines, CC , Chemotactic Factors, Eosinophil/genetics , Cytokines/deficiency , Eosinophils/cytology , Eosinophils/physiology , Animals , Blood Cell Count , Chemokine CCL11 , Cytokines/genetics , In Situ Hybridization , Jejunum/cytology , Jejunum/physiology , Mice , Mice, Knockout , RNA, Messenger/analysisABSTRACT
Eotaxin is a CC chemokine that is a specific chemoattractant for eosinophils and is implicated in the pathogenesis of eosinophilic inflammatory diseases, such as asthma. We describe the genomic organization, complete sequence, including 1354 bp 5' of the RNA initiation site, and chromosomal localization of the human eotaxin gene. Fluorescence in situ hybridization analysis localized eotaxin to human chromosome 17, in the region q21.1-q21.2, and the human gene name SCYA11 was assigned. We also present the 5' flanking sequence of the mouse eotaxin gene and have identified several regulatory elements that are conserved between the murine and the human promoters. In particular, the presence of elements such as NF-kappa B, interferon-gamma response element, and glucocorticoid response element may explain the observed regulation of the eotaxin gene by cytokines and glucocorticoids.
Subject(s)
Chemokines, CC , Chemotactic Factors, Eosinophil/genetics , Chromosomes, Human, Pair 17/genetics , Cytokines/genetics , Amino Acid Sequence , Animals , Base Sequence , Binding Sites/genetics , Chemokine CCL11 , Chromosome Mapping , Conserved Sequence , DNA/genetics , DNA/metabolism , Gene Expression Regulation , Humans , In Situ Hybridization, Fluorescence , Mice , Molecular Sequence Data , Promoter Regions, Genetic , Sequence Homology, Nucleic Acid , Transcription Factors/metabolismABSTRACT
The chemokines are a large family of cytokines that control the recruitment of leukocytes in immune and inflammatory responses. We describe the isolation of a novel murine CC chemokine that, based on its biological and structural features, we have named monocyte chemoattractant protein (MCP)-5. MCP-5 mapped to the CC chemokine cluster on mouse chromosome 11 and was most closely related to human MCP-1 in structure (66% amino acid identity). Purified recombinant MCP-5 protein was a potent chemoattractant for peripheral blood monocytes, was only weakly active on eosinophils at high doses, and was inactive on neutrophils. MCP-5 induced a calcium flux in peripheral blood mononuclear cells, but not in purified murine eosinophils or neutrophils. Consistent with these results, MCP-5 induced a calcium flux in human embryonic kidney (HEK)-293 cells transfected with human and murine CCR2, a CC chemokine receptor expressed on monocytes. MCP-5 did not induce a calcium flux in HEK-293 cells transfected with CCR1, CCR3, or CCR5. Constitutive expression of MCP-5 mRNA was detected predominantly in lymph nodes, and its expression was markedly induced in macrophages activated in vitro and in vivo. Moreover, MCP-5 expression was up-regulated in the lungs of mice following aerosolized antigen challenge of sensitized mice, and during the host response to infection with Nippostrongylus brasiliensis. These data indicate that MCP-5 is a novel and potent monocyte active chemokine that is involved in allergic inflammation and the host response to pathogens.
Subject(s)
Chemokine CCL2/chemistry , Chromosome Mapping , Monocyte Chemoattractant Proteins/chemistry , Monocyte Chemoattractant Proteins/genetics , Amino Acid Sequence , Animals , Base Sequence , Calcium/metabolism , Cell Line , DNA Primers , DNA, Complementary , Humans , Kidney , Leukocytes/drug effects , Leukocytes/physiology , Mice , Molecular Sequence Data , Monocyte Chemoattractant Proteins/pharmacology , Multigene Family , Polymerase Chain Reaction , RNA, Messenger/biosynthesis , Receptors, Cytokine/biosynthesis , Receptors, Cytokine/physiology , Recombinant Proteins/biosynthesis , Recombinant Proteins/chemistry , Recombinant Proteins/pharmacology , Transcription, Genetic , TransfectionABSTRACT
The chemokines are a large family of cytokines that regulate the complex and precise recruitment of immune cells into inflammatory foci. To fully appreciate their role in the pathogenesis of human diseases, the entire spectrum of chemokines, their receptors, their cellular targets, and mechanisms of regulation need to be delineated. Using eotaxin as a probe, we isolated a cDNA for a novel human beta (or CC) chemokine that, based on its biological and structural features, we have named monocyte chemoattractant protein (MCP)-4. Purified recombinant MCP-4 protein was a potent chemoattractant for monocytes and eosinophils and stimulated histamine release from basophils. MCP-4 induced a calcium flux in HEK-293 cells transfected with the monocyte selective MCP-1 receptor (CCR-2B) and the eosinophil selective eotaxin receptor (CCR-3), but not in the more widely expressed CCR-1 or CCR-5. This novel chemokine is expressed in TNF-alpha and IL-1 activated epithelial and endothelial cells in vitro, and in the epithelial mucosa of patients with both Th2-type allergic and Th1-type nonallergic sinusitis. Furthermore, both IFN-gamma and IL-4, products of Th1 and Th2 cells, respectively, synergized with TNF-alpha and IL-1 in inducing MCP-4 mRNA accumulation. These properties of MCP-4 offer a molecular explanation for the observed accumulation of monocytes, eosinophils and basophils in both Th1- and Th2-type immune responses.
