Decreased expression of TIPE2 in the eye under high-glucose conditions tested in vivo and in vitro.

AIMS: Inflammation is important in the development of angiogenesis diabetic retinopathy (DR). Anti-inflammation is promising strategy in early DR management. This study aimed to evaluate the level of tumour necrosis factor (TNF)-α-induced protein-8 like-2 (TIPE2), a formerly anti-inflammatory factor, under high-glucose conditions. METHODS: TIPE2 was detected in the ① retina from db/db and streptozotocin-induced diabetic mice; ② vitreous fluid of patients with proliferative diabetic retinopathy (PDR) and ③ mouse retinal microendothelial cells (RMEC) cultured in glucose of varying concentrations. In situ expression was evaluated by immunohistochemistry and immunofluorescence assay. The expression of protein was analysed by Western blot or ELISA and mRNA by qRT-PCR. RESULTS: TIPE2 was down-regulated in the retina of the mice with diabetes. TIPE2 was present in the cytoplasm of RMEC and down-regulated in high-glucose conditions in line with concentration and time. The expression of TIPE2 in the vitreous fluid of patients with PDR was significantly lower than that without diabetes. Silencing TIPE2 by an siRNA resulted in increased expression of vascular endothelial growth factor (a vital factor in the development of DR), TNF-α and IL-1ß. CONCLUSIONS: TIPE2 down-expressed and exerted anti-VEGF and anti-inflammatory function in the high-glucose environment. TIPE2 was verified to be involved in the process of DR and might be a potential regulator for DR development.