HIV-associated lipodystrophy (HIVLD) syndrome is a condition comprising abnormalities in distribution of body fat and metabolism of lipids and glucose that arises in HIV-infected patients on long-term antiretroviral therapy. This thesis describes clinical research into aspects of the natural history and treatment of HIVLD, as well as molecular research into its pathogenesis centred on subcutaneous adipose tissue. Results demonstrate HIVLD to be a treatment-induced syndrome characterised by initial gains in body fat followed by selective, progressive loss of limb fat. Exposure to thymidineanalogue nucleoside reverse transcriptase inhibitors (tNRTI) induces lipoatrophy through mitochondrial dysfunction of which inhibition of mitochondrial RNA expression, rather than mitochondrial DNA depletion, is an early feature. Mitochondrial dysfunction is associated with decreases in expression of peroxisome proliferatoractivated receptor gamma (PPAR??), an adipocyte transcription factor, which helps explain how tNRTI exposure leads to the loss of adipocyte function. Once established, lipoatrophy is characterised by mitochondrial DNA depletion, although this depletion occurs throughout the mitochondrial genome, suggesting an underlying cause other than inhibition of DNA polymerase gamma. HIVLD is a difficult syndrome to treat. Lipoatrophy is resistant to treatment with rosiglitazone, an agonist of PPAR??, which is ineffective in the setting of ongoing tNRTI therapy and mitochondrial dysfunction. Dyslipidaemia is also difficult to treat as use of pravastatin in the setting of ongoing exposure to protease inhibitors results in only modest declines in fasting cholesterol concentrations. Gains in central fat, such as that seen in patients with buffalo hump, are associated with insulin resistance and diabetes, but only occur in a relatively small percentage of treated patients, suggesting a role for genetic factors in its development. Use of strategies such as avoidance of tNRTI in firstline ART, genetic screening to identify those at risk of toxicities and targeted selection of interventions in subgroups of affected patients, may help prevent this syndrome occurring and better treat those patients in which it has already occurred.
| Identifer | oai:union.ndltd.org:ADTP/257646 |
| Date | January 2006 |
| Creators | Mallon, Patrick William Gerard, School of Medicine, UNSW |
| Publisher | Awarded by:University of New South Wales. School of Medicine |
| Source Sets | Australiasian Digital Theses Program |
| Language | English |
| Detected Language | English |
| Rights | Copyright Patrick William Gerard Mallon, http://unsworks.unsw.edu.au/copyright |
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