title: Elevated intravitreal interleukin-6 levels in patients with proliferative diabetic retinopathy.
abstract: BACKGROUND
  We conducted this study to elucidate the possible role of interleukin-6 (IL-6) in the pathogenesis of proliferative diabetic retinopathy (PDR).
  
  
  METHODS
  Together with pertinent clinical and laboratory data, intravitreal and serum concentrations of IL-6 were determined in 8 patients with PDR by means of enzyme-linked immunosorbent assay (ELISA). The results were compared with data from 8 nondiabetic control subjects undergoing vitrectomy.
  
  
  RESULTS
  Significantly higher intravitreal IL-6 concentrations were found in patients with PDR (mean [SD], 755 [177] pg/mL) compared with control subjects (93 [151] pg/mL) (p = 0.001). The serum IL-6 levels in the PDR group were lower than the measurable threshold of the ELISA kit (<0.16 pg/mL). Diabetic patients with macular edema had a higher mean (SD) level of intravitreal IL-6 (896 [73] pg/mL) compared with patients without macular edema (613 [119] pg/mL) (Mann-Whitney U test, p = 0.03). Correlation analysis did not reveal any significant association between intravitreal IL-6 levels and patient age, duration of either diabetes mellitus or vitreous hemorrhage, panretinal photocoagulation, type of current medical therapy, hyperglycemia, or the biochemical indicators of renal function.
  
  
  CONCLUSIONS
  IL-6, a proinflammatory cytokine, may have a role in PDR. Intraocular production of IL-6 appears to be responsible for the elevated intravitreal levels observed.
authors.affiliation: Department of Opthalmology, Hacettepe University School of Medicine, Ankara, Turkey.
authors.forename: Mehmet C
authors.initials: MC
authors.lastname: Mocan
authors.forename: Sibel
authors.initials: S
authors.lastname: Kadayifcilar
authors.forename: Bora
authors.initials: B
authors.lastname: Eldem
mesh_terms: D000368:Aged; D015415:Biomarkers / Q000378:metabolism; D003930:Diabetic Retinopathy / Q000175:diagnosis / Q000378:metabolism*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D015850:Interleukin-6 / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D009887:Ophthalmoscopy; D011379:Prognosis; D012720:Severity of Illness Index; D018630:Vitreoretinopathy, Proliferative / Q000175:diagnosis / Q000378:metabolism*; D014822:Vitreous Body / Q000378:metabolism*
chemical_list: D015415:Biomarkers; D015850:Interleukin-6