This project is concerned with the lysosomal accumulation of lipid in the developing macrophage foam cell as occurs in the atherosclerotic lesion. Lysosomal lipid accumulation in atherosclerosis is a feature of advanced atherosclerotic lesions, but an under explored area of research. In this dissertation I explored the potential mechanisms behind the lysosomal accumulation of lipid. We found that, upon incubation of macrophages with physiological lipid particles, there was an increase in lysosome pH over time such that the number of lysosomes having an active pH decreased. This could be duplicated by pharmacologically sequestering free cholesterol within the lysosome. To analyze for the potential mechanism behind lysosomal inactivation a procedure for isolating lysosomes and monitoring their activation in vitro was established. The studies presented here are the first to monitoring how cholesterol affects the activation of the human macrophage vacuolar-ATPase, which is responsible for maintaining the acidic nature of the lysosome. These experiments determined that exogenously increasing the lysosomal membrane cholesterol inhibited the vacuolar-ATPase. Furthermore, data indicate that the entire vacuolar-ATPase complex is inhibited and not just the pumping of hydrogen ions into the lysosomal lumen. This inhibition of the vacuolar-ATPase does appear to be a reversible process if the membrane cholesterol levels are returned to normal. These data suggest that, if the cholesterol could be removed from the lesion, the lysosomes could potentially recover their v-ATPase activity and become reactivated. These studies should aid in the understanding of lysosome biology and provide a more comprehensive understanding of macrophage foam cell metabolism in the atherosclerotic lesion.
| Identifer | oai:union.ndltd.org:VANDERBILT/oai:VANDERBILTETD:etd-09192007-151424 |
| Date | 20 September 2007 |
| Creators | Cox, Brian Elbert |
| Contributors | Larry Swift, Richard Hoover, Sergio Fazio, Jason Morrow, Anne Kenworthy |
| Publisher | VANDERBILT |
| Source Sets | Vanderbilt University Theses |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.library.vanderbilt.edu/available/etd-09192007-151424/ |
| Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to Vanderbilt University or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
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