Mitochondrial DNA depletion and morphologic changes in adipocytes associated with nucleoside reverse transcriptase inhibitor therapy.
BACKGROUND
Nucleoside analogue reverse transcriptase inhibitor (NRTI) therapy provides sufficient conditions for progressive subcutaneous fat wasting in HIV-infected patients. As NRTI-induced host toxicity is proposed to involve cellular mitochondrial DNA (mtDNA) depletion, determinants of cellular mtDNA copy number and mitochondrial mass in adipocyte samples from NRTI-treated HIV-infected patients and antiretroviral-naive controls were investigated. Adipose tissue morphology was also assessed.


METHODS
Subcutaneous fat samples were obtained from NRTI-treated, HIV-infected patients (n = 21), antiretroviral therapy-naive HIV-infected controls (n = 11), and HIV-seronegative controls (n = 6). Non-adipocytes were removed by collagenase digestion. Adipocyte mtDNA copies/cell was measured using a real time PCR-based assay, and adipocyte mitochondrial protein content was also measured. Light and electron microscopy were performed on tissue samples.


RESULTS
Adipocyte mtDNA copies/cell values were similar (P = 0.56) in HIV seronegative and HIV-infected control groups. NRTI treatment was associated with reduced adipocyte mtDNA copies/cell, representing mean mtDNA depletion in NRTI-treated individuals of 77.7% compared with the mean value for the HIV-infected control group (P < 0001). Additionally, significant differences were found in adipocyte mtDNA copies/cell between patients receiving stavudine (n = 12, mean mtDNA depletion 87.1%) and zidovudine (n = 9, mean mtDNA depletion 52.1%) (P < 0.001). Adipocyte mitochondrial mass was increased in the stavudine group only (mean increase 289%, P < 0.01).


CONCLUSIONS
NRTI therapy is associated with mtDNA depletion and mitochondrial proliferation in adipocytes, consistent with the hypothesis that NRTI-induced mtDNA depletion contributes to the pathogenesis of subcutaneous fat wasting. Morphologic assessment also supports a role for NRTI therapy in inducing adipocyte metabolic dysfunction and cell death.
Nolan
David
D
Centre for Clinical Immunology and Biomedical Statistics, Royal Perth Hospital and Murdoch University, Western Australia, Australia.
Hammond
Emma
E
Martin
Annalise
A
Taylor
Louise
L
Herrmann
Susan
S
McKinnon
Elizabeth
E
Metcalf
Cecily
C
Latham
Bruce
B
Mallal
Simon
S
D017667:Adipocytes / Q000648:ultrastructure*; D000704:Analysis of Variance; D023241:Antiretroviral Therapy, Highly Active; D016022:Case-Control Studies; D016923:Cell Death; D003430:Cross-Sectional Studies; D004272:DNA, Mitochondrial / Q000187:drug effects* / Q000648:ultrastructure; D015658:HIV Infections / Q000188:drug therapy / Q000473:pathology; D039682:HIV-Associated Lipodystrophy Syndrome / Q000139:chemically induced* / Q000473:pathology; D006801:Humans; D008854:Microscopy, Electron; D018894:Reverse Transcriptase Inhibitors / Q000627:therapeutic use*; D020133:Reverse Transcriptase Polymerase Chain Reaction
D004272:DNA, Mitochondrial; D018894:Reverse Transcriptase Inhibitors