title: Mitochondrial DNA depletion and morphologic changes in adipocytes associated with nucleoside reverse transcriptase inhibitor therapy.
abstract: 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.
authors.affiliation: Centre for Clinical Immunology and Biomedical Statistics, Royal Perth Hospital and Murdoch University, Western Australia, Australia.
authors.forename: David
authors.initials: D
authors.lastname: Nolan
authors.forename: Emma
authors.initials: E
authors.lastname: Hammond
authors.forename: Annalise
authors.initials: A
authors.lastname: Martin
authors.forename: Louise
authors.initials: L
authors.lastname: Taylor
authors.forename: Susan
authors.initials: S
authors.lastname: Herrmann
authors.forename: Elizabeth
authors.initials: E
authors.lastname: McKinnon
authors.forename: Cecily
authors.initials: C
authors.lastname: Metcalf
authors.forename: Bruce
authors.initials: B
authors.lastname: Latham
authors.forename: Simon
authors.initials: S
authors.lastname: Mallal
mesh_terms: 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
chemical_list: D004272:DNA, Mitochondrial; D018894:Reverse Transcriptase Inhibitors