Mast cell-mediated apoptosis of endothelial cells in vitro: a paracrine mechanism involving TNF-alpha-mediated down-regulation of bcl-2 expression.
Degranulated mast cells are present in the subendothelial space of eroded (de-endothelialized) coronary atheromas. Upon degranulation, mast cells secrete into the surrounding tissue an array of preformed and newly synthesized mediators, including proapoptotic molecules, such as chymase and TNF-alpha. In a co-culture system involving rat serosal mast cells and rat cardiac (microvascular) endothelial cells, we could show, by means of competitive RT-PCR, immunoblotting, immunocytochemistry, annexin staining, flow cytometry, and DNA-laddering, that stimulation of mast cells with ensuing degranulation rapidly (within 30 min) down-regulated the expression of both bcl-2 mRNA and protein, with subsequent induction of apoptosis in the endothelial cells. The major effect of bcl-2 down-regulation resided in the exocytosed granule remnants, a minor effect also being present in the granule remnant-free supernatant. No significant changes were observed in the expression levels of the pro-apoptotic protein, bax. The mast cell-mediated apoptotic effect was partially (70%) dependent on the presence of TNF-alpha and involved the translocation of cytochrome C from mitochondria into cytoplasm. These results are the first to show that one of the cell types present in the atherosclerotic plaques, namely the mast cell, by releasing both granule-remnant-bound and soluble TNF-alpha, may contribute to the erosion of atherosclerotic plaques by inducing apoptosis in adjacent endothelial cells. Published 2003 Wiley-Liss, Inc.
Lätti
Soili
S
Wihuri Research Institute, Helsinki, Finland.
Leskinen
Markus
M
Shiota
Naotaka
N
Wang
Yenfeng
Y
Kovanen
Petri T
PT
Lindstedt
Ken A
KA
D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D015550:Cell Degranulation; D002478:Cells, Cultured; D018920:Coculture Techniques; D003574:Cytochrome c Group / Q000378:metabolism; D003594:Cytoplasmic Granules / Q000378:metabolism; D015536:Down-Regulation / Q000502:physiology; D004730:Endothelium, Vascular / Q000166:cytology / Q000378:metabolism*; D008297:Male; D008407:Mast Cells / Q000187:drug effects / Q000378:metabolism*; D019899:Paracrine Communication / Q000502:physiology*; D011518:Proto-Oncogene Proteins / Q000096:biosynthesis; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis* / Q000378:metabolism; D051028:bcl-2-Associated X Protein; D003189:p-Methoxy-N-methylphenethylamine / Q000494:pharmacology
C494828:Bax protein, rat; D003574:Cytochrome c Group; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; D051028:bcl-2-Associated X Protein; D003189:p-Methoxy-N-methylphenethylamine