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Molecular Medicine |
From the Lowance Center for Human Immunology and Rheumatology, Emory University School of Medicine, 101 Woodruff Circle, Atlanta, GA 30322.
Correspondence to Cornelia M. Weyand, MD, PhD, Lowance Center for Human Immunology, WMRB #1003, 101 Woodruff Circle, Atlanta, GA 30322. E-mail cweyand{at}emory.edu
Large vessel vasculitides, such as Takayasu arteritis and giant cell arteritis, affect vital arteries and cause clinical complications by either luminal occlusion or vessel wall destruction. Inflammatory infiltrates, often with granulomatous arrangements, are distributed as a panarteritis throughout all of the arterys wall layers or cluster in the adventitia as a perivasculitis. Factors determining the architecture and compartmentalization of vasculitis are unknown. Human macrovessels are populated by indigenous dendritic cells (DCs) positioned in the adventitia. Herein, we report that these vascular DCs sense bacterial pathogens and regulate the patterning of the emerging arteritis. In human temporal artery–SCID chimeras, lipopolysaccharides stimulating Toll-like receptor (TLR)4 and flagellin stimulating TLR5 trigger vascular DCs and induce T-cell recruitment and activation. However, the architecture of the evolving inflammation is ligand-specific; TLR4 ligands cause transmural panarteritis and TLR5 ligands promote adventitial perivasculitis. Underlying mechanisms involve selective recruitment of functional T cell subsets. Specifically, TLR4-mediated DC stimulation markedly enhances production of the chemokine CCL20, biasing recruitment toward CCL20-responsive CCR6+ T cells. In adoptive transfer experiments, CCR6+ T cells produce an arteritis pattern with media-invasive T cells damaging vascular smooth muscle cells. Also, CCR6+ T cells dominate the vasculitic infiltrates in patients with panarteritic giant cell arteritis. Thus, depending on the original danger signal, vascular DCs edit the emerging immune response by differentially recruiting specialized T effector cells and direct the disease process toward distinct types of vasculitis.
Key Words: T cell Toll-like receptor inflammation vascular inflammation
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Circ. Res. 2009 104: 425-427.
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A. Yilmaz and M. Arditi Giant Cell Arteritis: Dendritic Cells Take Two T's to Tango Circ. Res., February 27, 2009; 104(4): 425 - 427. [Full Text] [PDF] |
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