Abstract
Purpose:
T cells that are driven by local inflammation play a pivotal role as conductor in acute and chronic immune responses, and have been shown to infiltrate the vitreous in patients with proliferative diabetic retinopathy (PDR). It has been known that IL-6 is elevated in the vitreous fluid of PDR patients. In this study, we examined whether vitreous level of IL-6 are associated with pathogenic factors of PDR.
Methods:
The study group consisted of 60 eyes of 54 type 2 diabetic patients (60 eyes) with PDR in which vitrectomy was performed and vitreous level of IL-6 could be measured between July 1, 2010 and February 28, 2014 in National Defense Medical College. The vitreous level of IL-6 was measured by Bio-Plex kit®, and the mean ± SD was 781.3±778.1 pg/ml. The age (mean ± SD) was 54.8 ± 10.6 years, the duration of diabetes (mean ± SD) was 6.9 ± 8.6 years, and the preoperative HbA1c (mean ± SD) was 7.3 ±1.9％. Vitreous hemorrhage (VH) in 63.3%, macular edema (ME) in 65.0%, and tractional retinal detachment (TRD) in 56.7% were observed. The study was approved by the institutional review board of National Defense Medical College.
Results:
The vitreous level of IL-6 was significantly associated with preoperative HbA1c (r=0.31、P=0.02), and there was significant difference between PDR with TRD (882.5±813.2 pg/ml)and those without TRD (649.0±723.8 pg/ml). Vitreous IL-6 level in the fourth, fifth, and sixth decade were 1167.1 ± 1010.5, 509.04±454.0, and 767.2±782.5 pg/ml, respectively, in which that of the fourth decade was significantly higher than others. On the other hand, there was no significant difference between vitreous IL-6 level and the duration of diabetes, or the grades of retinal photocoagulation. In addition, vitreous level of IL-6 was higher in PDR without VH (951.9±1053.6 pg/ml) or ME (1041.5±1082.5 pg/ml) than in those with VH (682.5±555.0 opg/ml) or ME (641.2±515.5 pg/ml), however there was no statistical difference between them.
Conclusions:
In PDR, vitreous level of IL-6 which is one of inflammatory cytokines was correlated with preoperative HbA1c, and was higher in eyes developing TRD or in the younger patients, suggesting that vitreous IL-6 might be a factor exhibiting progression of diabetic retinopathy.