Der interzelluläre Transport Lipid-geladener Lysosomen aus Makrophagen in glatte Gefäßmuskelzellen führt zur phänotypischen Veränderung der Gefäßmuskelzellen in einen schaumzellartigen Phänotyp

• Main Author: Weinert, Sönke
• Other Authors: Technische Universität Dresden, Fakultät Mathematik und Naturwissenschaften
• Format: Doctoral Thesis
• Language: deu
• Published: Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden 2015
• Subjects: Gefäßmuskelzellen; Makrophagen; Low Density Lipoprotein; LDL; Cholesterol; Smooth muscle cells; Macrophages; Low-density lipoprotein (LDL); ddc:540; rvk:WD 5400
• Online Access: http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-150397; http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-150397; http://www.qucosa.de/fileadmin/data/qucosa/documents/15039/Dissertation_S_Weinert_PDF_A1b_ohne_Animation.pdf

AIMS: Macrophages (MPs) and vascular smooth muscle cells (VSMCs) closely interact within the growing atherosclerotic plaque. An in vitro co-culture model was established to study how MPs modulate VSMC behaviour. METHODS AND RESULTS: MPs were exposed to fluorescence-labelled-acetylated LDL (FL-acLDL) prior to co-culture with VSMCs. Fluorescence microscopy visualized first transport of FL-acLDL within 6 h after co-culture implementation. When MPs had been fed with FL-acLDL in complex with fluorescence-labelled cholesterol (FL-Chol), these complexes were also transferred during co-culture and resulted in cholesterol positive lipid droplet formation in VSMCs. When infected with a virus coding for a fusion protein of Rab5a and fluorescent protein reporter (FP) to mark early endosomes, no co-localization between Rab5a-FP and the transported FL-acLDL within VSMCs was detected implying a mechanism independent of phagocytosis. Next, expression of lysosome-associated membrane glycoprotein 1 (LAMP1)-FP, marking all lysosomes in VSMCs, revealed that the FL-acLDL was located in non-acidic lysosomes. MPs infected with virus encoding for LAMP1-FP prior to co-culture demonstrated that intact fluorescence-marked lysosomes were transported into the VSMC, instead. Xenogenic cell composition (rat VSMC, human MP) and subsequent quantitative RT-PCR with rat-specific primers rendered induction of genes typical for MPs and down-regulation of the cholesterol sensitive HMG-CoA reductase. CONCLUSION: Our results demonstrate that acLDL/cholesterol-loaded lysosomes are transported from MPs into VSMCs in vitro. Lysosomal transfer results in a phenotypic alteration of the VSMC towards a foam cell-like cell. This way VSMCs may lose their plaque stabilizing properties and rather contribute to plaque destabilization and rupture.