h1

TY  - THES
AU  - Krohn, Regina
TI  - Identification of novel chemokine and chemokine-like mechanisms in leukocyte adhesion and atherosclerotic lesion formation
CY  - Aachen
PB  - Publikationsserver der RWTH Aachen University
M1  - RWTH-CONV-112710
SP  - V, 100 Bl. : Ill., graph. Darst.
PY  - 2008
N1  - Zsfassung in dt. und engl. Sprache
N1  - Aachen, Techn. Hochsch., Diss., 2008
AB  - This study surveys the expression control and the down-stream effects of two mediators that have a severe impact on atherosclerosis progression. The first approach identified YB-1 as a new transcriptional regulator of the CC chemokine RANTES. RANTES is upregulated in mononuclear cells or deposited by activated platelets during inflammation and has been implicated in atherosclerosis and neointimal hyperplasia. Here, the influence of YB-1 on RANTES expression and its contribution to neointima formation after guide-wire injury has been investigated. The binding of YB-1 to position -214/-173 was confirmed by DNA binding studies. Increased expression of both YB-1 and RANTES mRNA in neointimal versus medial SMC suggested a regulatory function of YB-1 for RANTES expression and, indeed, overexpression of YB-1 in smooth muscle cells (but not macrophages) enhanced RANTES transcriptional activity in reporter assays, mRNA and protein expression, and RANTES-dependent monocyte arrest in shear flow. Furthermore, intraluminal transfection of carotid arteries of hyperlipidemic Apoe-/- mice with a lentivirus encoding YB-1 shRNA directly after wire injury led to a significant reduction in plaque area and macrophage content. YB-1 was expressed in neointimal SMC but not macrophages and colocalized with neointimal RANTES, which was downregulated by YB-1 shRNA. A further reduction of lesion formation by YB-1 knockdown was not observed in Apoe-/- mice deficient in the RANTES receptor Ccr5 or after treatment with the RANTES receptor antagonist Met-RANTES, which indicates that YB-1 effects were dependent on RANTES. Thus, local blockade of YB-1 might become a suitable strategy in preventing restenosis after balloon angioplasty. The second part of this work intended to elucidate the mechanisms of the pleiotropic functions of the CLF chemokine MIF. MIF plays a critical role in inflammatory diseases and atherogenesis and attracts immune cells to sites of inflammation. The only known cell surface receptor for MIF is CD74, which can mediate sustained activation of ERK/MAPK. Yet, no receptor had been discovered that would be able to confer MIF’s chemokine-like functions in cells devoid of CD74, as neutrophils and fibroblast, which are also affected by MIF. This thesis introduces the two chemokine receptors CXCR2 and CXCR4 as functional receptors for MIF. MIF triggered G alpha i and integrin-dependent arrest of monocytes and T cells specifically through CXCR2 and, to a lesser extent, CXCR4, inducing rapid integrin activation and calcium influx. MIF directly bound to CXCR2 as revealed by FACS analysis and coimmunoprecipitation. Monocyte arrest mediated by MIF in inflamed or atherosclerotic arteries involved CXCR2 and CD74, which occur in a receptor complex. In vivo, MIF deficiency impaired monocyte adhesion to the aortic/arterial wall in atherosclerosis-prone mice, and MIF-induced leukocyte adhesion as well as peritoneal recruitment required CXCR2, as evidenced by intravital microscopy and MIF/CXCR2 chimeric mice. Blocking MIF but not bona fide ligands of CXCR2 or CXCR4 in mice with advanced atherosclerosis reduced plaque area, monocyte and T-cell content. These data open the possibility of achieving therapeutic regression and stabilization of advanced atherosclerotic lesions by targeting MIF.
KW  - Makrophagen-Inhibitionsfaktor (SWD)
KW  - RANTES (SWD)
KW  - Zelladhäsion (SWD)
KW  - Arteriosklerose (SWD)
KW  - Plaque <Medizin> (SWD)
LB  - PUB:(DE-HGF)11
UR  - https://publications.rwth-aachen.de/record/50155
ER  -