APOPTOSIS IN HUMAN MONOCYTE-MACROPHAGES EXPOSED TO OXIDIZED LOW DENSITY LIPOPROTEIN

✍ Scribed by HARDWICK, SIMON J.; HEGYI, LASZLO; CLARE, KATHARINE; LAW, NADINE S.; CARPENTER, KERI L. H.; MITCHINSON, MALCOLM J.; SKEPPER, JEREMY N.

• Publisher: John Wiley and Sons
• Year: 1996
• Tongue: English
• Weight: 1011 KB
• Volume: 179
• Category: Article
• ISSN: 0022-3417
• DOI: 10.1002/(sici)1096-9896(199607)179:3<294::aid-path590>3.0.co;2-x

✦ Synopsis

This study has demonstrated the toxicity to human monocyte-macrophages of low-density lipoprotein (LDL) which had been artificially oxidized using copper sulphate. The assays of cell damage used were tritiated adenine release, neutral red staining, lactate dehydrogenase leakage, and MTT dye reduction. Toxicity was concentration-and time-dependent. Exposure to native LDL under the same conditions did not result in toxicity. Transmission electron microscopy of cells exposed to oxidized LDL showed characteristic changes of apoptosis, including chromatin condensation and a decrease in cell volume. There was extensive loss of cell surface protrusions and evidence of the phagocytosis of apoptotic cells by neighbouring monocyte-macrophages. Apoptotic features preceded the increased membrane permeability revealed by the release of radioactivity from cells preloaded with tritiated adenine and hy lactate dehydrogenase leakage. DNA fragmentation was indicated by nick end-labelling using the terminal transferase enzyme (TUNEL). The number of TUNEL-positive cells was markedly greater in cells exposed to oxidized LDL, compared with those incubated as no-additions controls. lnhibition of de nova protein synthesis with cycloheximide and of Ca2+fMgZ+-activated endonuclease activity with aurintricarboxylic acid or zinc ion did not inhibit the toxicity produced by oxidized LDL.