HMGB-1 as a Potential Target for the Treatment of Diabetic Retinopathy

BACKGROUND Diabetic retinopathy (DR) is one of the most important complications of diabetes mellitus (DM) and is the leading cause of blindness in diabetic patients. Recent studies showed that as important inflammatory mediators, high mobility group box 1 (HMGB-1) is associated with diabetic peripheral neuropathy and can participate in the occurrence and development of DR. This study explored HMGB-1 as a therapeutic target for DR treatment through observing its role in retinal ganglion cells (GRCs) in a high glucose environment. MATERIAL AND METHODS RGCs were randomly divided into 3 groups: the normal control group, the high glucose group, and the siRNA HMGB-1 group. Real-time PCR was used to detect HMGB-1 mRNA expression. ELISA was used to test HMGB-1 protein expression in the supernatant. MTT assay was performed to determine cell proliferation. Real-time PCR and Western blotting were used to analyze TLR4 and NF-κB expression. RESULTS HMGB-1 mRNA was up-regulated (P=0.015) and protein secretion increased (P=0.022) in the high glucose environment. RGCs survival decreased (P=0.026), while TLR4 and NF-κB mRNA (P=0.009 and P=0.017, respectively) and protein expression increased significantly (P=0.041 and P=0.024, respectively). SiRNA HMGB-1 transfection obviously inhibited HMGB-1 mRNA expression (P=0.032), reduced HMGB-1 secretion (P=0.012), and decreased TLR4 and NF-κB mRNA (P=0.033 and P=0.024, respectively) and protein expression (P=0.032; P=0.027, respectively). Compared with the high glucose group, the RGCs survival rate increased significantly (P=0.037). CONCLUSIONS As a therapeutic target, HMGB-1 can inhibit inflammation and promote RGCs survival to delay DR progress through the HMGB-1-TLR4-NF-κB signaling pathway.