Researchers at the Tokyo Women's Medical University have verified the link between four inflammatory factors and diabetic macular edema (DME). Although this study suggests that intravitreal injection of steroids such as triamcinolone acetonide may be useful in treating DME, further clinical trials are required to confirm this finding.
The group measured levels of four inflammatory factors and one anti-inflammatory factor in the vitreous gel of 53 patients with DME, 15 patients with nondiabetic ocular disease, and eight diabetic patients without retinopathy. Vascular endothelial growth factor (VEGF), intercellular adhesion molecule (ICAM)-1, interleukin (IL)-6, monocyte chemotactic protein (MCP)-1, and the antiinflammatory pigment epithelium-derived factor (PEDF) were selected because earlier research had linked them to the development or exacerbation of DME.
All four inflammatory factors were significantly higher, and PEDF was significantly lower in the vitreous of patients with DME compared with the two other patient groups, according to the scientists. They also found that VEGF and ICAM-1 had a stronger influence on the severity of DME than the other factors.
VEGF is a strong vascular permeability factor that is overproduced in response to reduced oxygen levels in the retinas of people with retinopathy, and this research thus suggests that VEFG is the key to the inflammatory response in DME, the team explains. Building on earlier, similar findings, the study also indicates that PEDF may block the expression and actions of the key inflammatory factors.
The findings also point to Triamcinolone acetonide as a treatment option. “Triamcinolone acetonide downregulates VEGF and ICAM-1, inhibits inflammatory cells, stabilizes cell membranes, and increases PEDF levels,” says Hideharu Funatsu, M.D. “It appears to control more of the cytokine messengers that contribute to abnormal blood-vessel permeability.” Results of this study appear in this month’s Ophthalmology.