title: Elevated serum fibroblast growth factor 21 levels correlate with immune recovery but not mitochondrial dysfunction in HIV infection.
abstract: BACKGROUND
  Anti-retroviral treated HIV-infected patients are at risk of mitochondrial toxicity, but non-invasive markers are lacking. Serum FGF-21 (fibroblast growth factor 21) levels correlate strongly with muscle biopsy findings in inherited mitochondrial disorders. We therefore aimed to determine whether serum FGF-21 levels correlate with muscle mitochondrial dysfunction in HIV-infected patients.
  
  
  RESULTS
  We performed a cross-sectional study of anti-retroviral treated HIV-infected subjects (aged 29 - 71 years, n = 32). Serum FGF-21 levels were determined by quantitative ELISA. Cellular mitochondrial dysfunction was assessed by COX (cytochrome c oxidase) histochemistry of lower limb skeletal muscle biopsy. Serum FGF-21 levels were elevated in 66% of subjects. Levels correlated significantly with current CD4 lymphocyte count (p = 0.042) and with total CD4 count gain since initiation of anti-retroviral therapy (p = 0.016), but not with the nature or duration of past or current anti-retroviral treatment. There was no correlation between serum FGF-21 levels and severity of the muscle mitochondrial (COX) defect.
  
  
  CONCLUSIONS
  Serum FGF-21 levels are a poor predictor of muscle mitochondrial dysfunction in contemporary anti-retroviral treated patients. Serum FGF-21 levels are nevertheless commonly elevated, in association with the degree of immune recovery, suggesting a non-mitochondrial metabolic disturbance with potential implications for future comorbidity.
authors.affiliation: Institute of Genetic Medicine, Newcastle University, Central Parkway, Newcastle-upon-Tyne NE1 3BZ, UK. brendan.Payne@ncl.ac.uk.
authors.forename: Brendan Ai
authors.initials: BA
authors.lastname: Payne
authors.forename: David Ashley
authors.initials: DA
authors.lastname: Price
authors.forename: Patrick F
authors.initials: PF
authors.lastname: Chinnery