title: High vitreous concentration of IL-6 and IL-8, but not of adhesion molecules in relation to plasma concentrations in proliferative diabetic retinopathy.
abstract: OBJECTIVE
  Inflammatory markers have been observed in proliferative diabetic retinopathy (PDR). We assessed vitreous concentrations of adhesion molecules and cytokines in PDR and non-diabetic controls and plasma concentrations to differentiate local inflammation from the breakdown of the blood-retina barrier.
  
  
  METHODS
  38 patients with PDR and 16 controls with macular hole or epiretinal membrane underwent vitrectomy. Vitreous and plasma soluble adhesion molecules [sE-selectin, intercellular adhesion molecule (sICAM)-1 and -3, platelet-endothelial cell adhesion molecule (sPECAM)-1, sP-selectin, vascular cell adhesion molecule (sVCAM)-1] and cytokines [interleukin (IL)-1β, IL-2, IL-4, IL-5, IL-6, IL-8, IL-10, IL-12 (p70), tumour necrosis factor-α and -β, γ-interferon] were detected by the multiplex assay.
  
  
  RESULTS
  Levels of IL-6 and IL-8 were 26-fold (p = 0.001) and 6-fold higher (p = 0.001) in vitreous than in plasma in PDR. Vitreous IL-10 (p = 0.004), sPECAM-1, sE-selectin, sICAM-1 and sVCAM-1 were higher in PDR than controls (p = 0.001 for all). Adhesion molecule concentrations in vitreous in PDR were less than 10% of those in plasma. IL-10 was lower in vitreous than plasma (3.0 vs. 12.8 pg/ml, p = 0.007), and the vitreous IL-10/IL-8 ratio was significantly lower in PDR than in controls (0.10 vs. 0.55 pg/ml, p = 0.003).
  
  
  CONCLUSIONS
  The elevated IL-6 and IL-8 levels in vitreous, but not in plasma, are evidence favouring local over systemic inflammation in PDR. Furthermore, there was imbalance between inflammatory and anti-inflammatory cytokines in the vitreous.
authors.affiliation: Department of Ophthalmology, University of Oulu, Oulu, Finland.
authors.forename: U E
authors.initials: UE
authors.lastname: Koskela
authors.forename: S M
authors.initials: SM
authors.lastname: Kuusisto
authors.forename: A E
authors.initials: AE
authors.lastname: Nissinen
authors.forename: M J
authors.initials: MJ
authors.lastname: Savolainen
authors.forename: M J
authors.initials: MJ
authors.lastname: Liinamaa
mesh_terms: D000368:Aged; D015815:Cell Adhesion Molecules / Q000378:metabolism*; D003922:Diabetes Mellitus, Type 1 / Q000150:complications; D003924:Diabetes Mellitus, Type 2 / Q000150:complications; D003930:Diabetic Retinopathy / Q000097:blood / Q000378:metabolism* / Q000601:surgery; D005260:Female; D006801:Humans; D015850:Interleukin-6 / Q000378:metabolism*; D016209:Interleukin-8 / Q000378:metabolism*; D008269:Macular Edema / Q000378:metabolism / Q000601:surgery; D008297:Male; D008875:Middle Aged; D012167:Retinal Perforations / Q000378:metabolism / Q000601:surgery; D014821:Vitrectomy; D014822:Vitreous Body / Q000378:metabolism*
chemical_list: C508606:CXCL8 protein, human; D015815:Cell Adhesion Molecules; C508600:IL6 protein, human; D015850:Interleukin-6; D016209:Interleukin-8