High vitreous concentration of IL-6 and IL-8, but not of adhesion molecules in relation to plasma concentrations in proliferative diabetic retinopathy

Ophthalmic Res. 2013;49(2):108-14. doi: 10.1159/000342977. Epub 2012 Dec 18.


Background/aim: 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).

Conclusion: 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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Cell Adhesion Molecules / metabolism*
  • Diabetes Mellitus, Type 1 / complications
  • Diabetes Mellitus, Type 2 / complications
  • Diabetic Retinopathy / blood
  • Diabetic Retinopathy / metabolism*
  • Diabetic Retinopathy / surgery
  • Female
  • Humans
  • Interleukin-6 / metabolism*
  • Interleukin-8 / metabolism*
  • Macular Edema / metabolism
  • Macular Edema / surgery
  • Male
  • Middle Aged
  • Retinal Perforations / metabolism
  • Retinal Perforations / surgery
  • Vitrectomy
  • Vitreous Body / metabolism*


  • CXCL8 protein, human
  • Cell Adhesion Molecules
  • IL6 protein, human
  • Interleukin-6
  • Interleukin-8