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Study links inflammatory factors with diabetic macular edema
Ophthalmology. 2009;116(1):73-79.
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High vitreous levels of four inflammatory factors and low levels of one anti-inflammatory factor may play key roles in the development of diabetic macular edema.
The retrospective case-control study included 53 patients with DME, 15 patients with non-diabetic ocular disease and eight diabetic patients without retinopathy. Investigators took vitreous fluid samples and measured four inflammatory factors: vascular endothelial growth factor (VEGF), intercellular adhesion molecule-1 (ICAM-1), interleukin-6 (IL-6) and monocyte chemotactic protein-1 (MCP-1). They also measured levels of pigment epithelium-derived factor (PEDF), an anti-inflammatory factor.
Up-regulation of the inflammatory factors and down-regulation of PEDF, combined with an increase in leukocyte-endothelial interaction, contributed to the breakdown of the blood-retinal barrier, a cause of DME, the authors said.
Levels of VEGF, ICAM-1, IL-6 and MCP-1 were significantly higher in patients with DME than in non-diabetic patients or diabetic patients without retinopathy (both P < .05). VEGF and ICAM-1 levels correlated more strongly with DME severity than other factors, the authors said.
"These results may be useful for investigating the mechanism of [blood-retinal barrier] breakdown in patients with DME and for developing new treatments," they said. Intravitreal injection of triamcinolone, a steroid, may treat DME more effectively than bevacizumab, an anti-VEGF, but more study is warranted.
This study nicely adds to the growing body of evidence that various inflammatory cytokines are up-regulated and anti-inflammatory cytokines are down-regulated in eyes with diabetic macular edema (DME). The study found that multiple inflammatory factors are involved in eyes with active DME and the breakdown of blood-retinal barrier, although VEGF and ICAM-1 seemed to be most important. Therefore, therapy for DME may need to target more broadly than VEGF alone.
– Judy E. Kim, MD
OSN Retina/Vitreous Board Member