TY - THES A1 - Koch, Miriam T1 - Role of Coagulation Factor XII in Atherosclerosis T1 - Rolle des Koagulationsfaktors XII in der Atherosklerose N2 - Atherosclerosis is considered a chronic inflammatory disease of the arterial vessel wall which is not only modulated by innate and adaptive immune responses but also by factors of the blood coagulation system. In general hypercoagulability seems to increase the development and progression of experimental atherosclerosis in mice on an atherogenic background. In addition, the great majority of coagulation proteins including coagulation factor XII (FXII) have been detected in early and advanced human atherosclerotic lesions supporting the cross-link between the coagulation system and atherosclerosis. Moreover, FXII has been detected in close proximity to macrophages, foam cells and smooth muscle cells in these lesions and has been demonstrated to be functionally active in human plaques. Although these data indicate that factor XII may play a role in atherogenesis a direct contribution of FXII to atherogenesis has not been addressed experimentally to date. Furthermore, clinical studies examining the function of FXII in vascular disease have yielded conflicting results. Hence, in order to investigate the function of coagulation factor XII in atherosclerosis apolipoprotein E and FXII-deficient (F12\(^{-/-}\) apoE\(^{-/-}\)) mice were employed. Compared to F12\(^{+/+}\)apoE\(^{-/-}\) controls, atherosclerotic lesion formation was reduced in F12\(^{-/-}\)apoE\(^{-/-}\) mice, associated with diminished systemic T-cell activation and Th1-cell polarization after 12 weeks of high fat diet. Moreover, a significant decrease in plasma levels of complement factor C5a was evidenced in F12\(^{-/-}\)apoE\(^{-/-}\) mice. Interestingly, C5a increased the production of interleukin-12 (IL-12) in dendritic cells (DCs) and enhanced their capacity to trigger antigen-specific interferon-gamma (IFNγ) production in OTII CD4\(^+\) T cells in vitro. Importantly, a reduction in frequencies of IL-12 expressing splenic DCs from atherosclerotic F12\(^{-/-}\)apoE\(^{-/-}\) versus F12\(^{+/+}\)apoE\(^{-/-}\) mice was observed in vivo, accompanied by a diminished splenic Il12 transcript expression and significantly reduced IL-12 serum levels. Consequently, these data reveal FXII to play an important role in atherosclerotic lesion formation and to promote DC-induced and systemic IL 12 expression as well as pro-inflammatory T-cell responses likely at least in part via the activation of the complement system. N2 - Die Arteriosklerose wird als eine chronisch entzündliche Erkrankung der arteriellen Gefäßwand angesehen, welche nicht nur durch Antworten des angeborenen und erworbenen Immunsystems, sondern auch durch Faktoren des Blutgerinnungssystems beeinflusst wird. Aus Tierstudien weiß man, dass Hyperkoagulabilität im Allgemeinen die Entwicklung und das Fortschreiten der Arteriosklerose in Mäusen mit atherogenem Hintergrund steigert. Ferner wurde die Mehrheit der Blutgerinnungsproteine inklusive des Koagulationsfaktors XII (FXII) in frühen und fortgeschrittenen arteriosklerotischen Läsionen in Menschen nachgewiesen, was eine mögliche Verbindung zwischen Koagulationssystem und Arteriosklerose untermauert. Darüber hinaus wurde der FXII in diesen Läsionen im unmittelbaren Umfeld von Makrophagen, Schaumzellen und glatten Muskelzellen nachgewiesen und dessen funktionelle Aktivität in humanen Plaques aufgezeigt. Obwohl diese Daten eine Funktion von FXII in der Arteriosklerose nahelegen, wurde eine direkte Beteiligung von FXII an der Atherogenese bislang experimentell noch nicht untersucht. Ferner erzielten klinische Studien, welche die Funktion von FXII in Gefäßerkrankungen untersuchten, widersprüchliche Resultate. Um die Funktion des Koagulationsfaktors XII in der Atherosklerose zu untersuchen, wurden daher Apolipoprotein E und FXII-defiziente (F12\(^{-/-}\)apoE\(^{-/-}\)) Mäuse eingesetzt. Die Ausbildung arteriosklerotischer Läsionen war in F12\(^{+/+}\)apoE\(^{-/-}\) Mäusen im Vergleich zu F12\(^{+/+}\)apoE\(^{-/-}\) Kontrollen reduziert. Dies ging mit einer verringerten systemischen T-Zell Aktivierung und Th1-Zell Polarisierung nach 12-wöchiger atherogener Diät einher. Ferner konnte eine signifikante Reduktion der C5a-Plasmaspiegel in F12\(^{-/-}\)apoE\(^{-/-}\) Mäusen nachgewiesen werden. Interessanterweise konnte C5a die Interleukin-12 (IL 12) Produktion in dendritischen Zellen (DCs) steigern, sowie deren Fähigkeit erhöhen, eine antigen-spezifische Interferon-gamma (IFNγ) Produktion in vitro, in OTII CD4\(^+\) T-Zellen zu induzieren. Insbesondere konnte in vivo eine Reduktion IL-12-exprimierender DCs in Milzen arteriosklerotischer F12\(^{-/-}\)apoE\(^{-/-}\) im Vergleich zu F12\(^{+/+}\)apoE\(^{-/-}\) Mäusen beobachtet werden, welche mit einer verminderten Expression an Il12 Transkripten in der Milz und signifikant reduzierten IL-12 Serumspiegeln einherging. Zusammenfassend zeigen diese Daten, dass FXII eine wichtige Rolle in der Bildung arteriosklerotischer Läsionen spielt und die DC-vermittelte und systemische IL-12 Expression, sowie pro-inflammatorische T-Zell Antworten, vermutlich teilweise über eine Aktivierung des Komplementsystems, fördert. KW - Gerinnungsfaktor XII KW - Arteriosklerose KW - coagulation factor XII KW - atherosclerosis KW - T cells KW - dendritic cells Y1 - 2014 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-97850 ER - TY - JOUR A1 - Cochain, Clement A1 - Chaudhari, Sweena M. A1 - Koch, Miriam A1 - Wiendl, Heinz A1 - Eckstein, Hans-Henning A1 - Zernecke, Alma T1 - Programmed Cell Death-1 Deficiency Exacerbates T Cell Activation and Atherogenesis despite Expansion of Regulatory T Cells in Atherosclerosis-Prone Mice JF - PLoS ONE N2 - T cell activation represents a double-edged sword in atherogenesis, as it promotes both pro-inflammatory T cell activation and atheroprotective Foxp3(+) regulatory T cell (Treg) responses. Here, we investigated the role of the co-inhibitory receptor programmed cell death-1 (PD-1) in T cell activation and CD4(+) T cell polarization towards pro-atherogenic or atheroprotective responses in mice. Mice deficient for both low density lipoprotein receptor and PD-1 (Ldlr(-/-)Pd1(-/-)) displayed striking increases in systemic CD4(+) and CD8(+) T cell activation after 9 weeks of high fat diet feeding, associated with an expansion of both pro-atherogenic IFNγ-secreting T helper 1 cells and atheroprotective Foxp3+ Tregs. Importantly, PD-1 deficiency did not affect Treg suppressive function in vitro. Notably, PD-1 deficiency exacerbated atherosclerotic lesion growth and entailed a massive infiltration of T cells in atherosclerotic lesions. In addition, aggravated hypercholesterolemia was observed in Ldlr(-/-)Pd1(-/-) mice. In conclusion, we here demonstrate that although disruption of PD-1 signaling enhances both pro- and anti-atherogenic T cell responses in Ldlr(-/-) mice, pro-inflammatory T cell activation prevails and enhances dyslipidemia, vascular inflammation and atherosclerosis. KW - nutritional deficiencies KW - atherosclerosis KW - spleen KW - aorta KW - diet KW - cytotoxic T cells KW - regulatory T cells KW - T cells Y1 - 2014 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-119823 SN - 1932-6203 VL - 9 IS - 4 ER - TY - JOUR A1 - Busch, Martin A1 - Westhofen, Thilo C. A1 - Koch, Miriam A1 - Lutz, Manfred B. A1 - Zernecke, Alma T1 - Dendritic Cell Subset Distributions in the Aorta in Healthy and Atherosclerotic Mice JF - PLoS ONE N2 - Dendritic cells (DCs) can be sub-divided into various subsets that play specialized roles in priming of adaptive immune responses. Atherosclerosis is regarded as a chronic inflammatory disease of the vessel wall and DCs can be found in non-inflamed and diseased arteries. We here performed a systematic analyses of DCs subsets during atherogenesis. Our data indicate that distinct DC subsets can be localized in the vessel wall. In C57BL/6 and low density lipoprotein receptor-deficient (Ldlr−/−) mice, CD11c+ MHCII+ DCs could be discriminated into CD103− CD11b+F4/80+, CD11b+F4/80− and CD11b−F4/80− DCs and CD103+ CD11b−F4/80− DCs. Except for CD103− CD11b− F4/80− DCs, these subsets expanded in high fat diet-fed Ldlr−/− mice. Signal-regulatory protein (Sirp)-α was detected on aortic macrophages, CD11b+ DCs, and partially on CD103− CD11b− F4/80− but not on CD103+ DCs. Notably, in FMS-like tyrosine kinase 3-ligand-deficient (Flt3l−/−) mice, a specific loss of CD103+ DCs but also CD103− CD11b+ F4/80− DCs was evidenced. Aortic CD103+ and CD11b+ F4/80− CD103− DCs may thus belong to conventional rather than monocyte-derived DCs, given their dependence on Flt3L-signalling. CD64, postulated to distinguish macrophages from DCs, could not be detected on DC subsets under physiological conditions, but appeared in a fraction of CD103− CD11b+ F4/80− and CD11b+ F4/80+ cells in atherosclerotic Ldlr−/− mice. The emergence of CD64 expression in atherosclerosis may indicate that CD11b+ F4/80− DCs similar to CD11b+ F4/80+ DCs are at least in part derived from immigrated monocytes during atherosclerotic lesion formation. Our data advance our knowledge about the presence of distinct DC subsets and their accumulation characteristics in atherosclerosis, and may help to assist in future studies aiming at specific DC-based therapeutic strategies for the treatment of chronic vascular inflammation. KW - flow cytometry KW - monocytes KW - diet KW - cell staining KW - DAPI staining KW - aorta KW - macrophages Y1 - 2014 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-119907 SN - 1932-6203 VL - 9 IS - 2 ER -