Serum and vitreous levels of visfatin in patients with diabetic retinopathy

MiR-181 enhances proliferative and migratory potentials of retinal endothelial cells in diabetic retinopathy by targeting KLF6

PURPOSE

We aimed to uncover the role of microRNA-181 (miR-181) in the disease onset of diabetic retinopathy (DR) and its underlying mechanism.

METHODS

MiR-181 levels in plasma and aqueous humor samples of non-proliferative diabetic retinopathy (NPDR), proliferative diabetic retinopathy (PDR) and healthy subjects were analyzed by microarray and quantitative real-time polymerase chain reaction (qRT-PCR). Proliferative and migrative capacities of human retinal endothelial cells (hRECs) regulated by miR-181 were assessed. The binding between miR-181 and kruppel-like factor 6 (KLF6) was verified by dual-luciferase reporter assay.

RESULTS

MiR-181 was upregulated in plasma and aqueous humor samples of NPDR and PDR patients. Overexpression of miR-181 stimulated hRECs to proliferate and migrate. KLF6 was the downstream gene binding miR-181, which was involved in the regulation of hRECs by miR-181.

CONCLUSIONS

MiR-181 is upregulated in plasma and aqueous humor of DR patients. It enhances proliferative and migratory potentials of retinal endothelial cells by targeting KLF6.

NAMPT and NAMPT-controlled NAD Metabolism in Vascular Repair

Vascular repair plays important roles in postischemic remodeling and rehabilitation in cardiovascular and cerebrovascular disease, such as stroke and myocardial infarction. Nicotinamide adenine dinucleotide (NAD), a well-known coenzyme involved in electron transport chain for generation of adenosine triphosphate, has emerged as an important controller regulating various biological signaling pathways. Nicotinamide phosphoribosyltransferase (NAMPT) is the rate-limiting enzyme for NAD biosynthesis in mammals. NAMPT may also act in a nonenzymatic manner, presumably mediated by unknown receptor(s). Rapidly accumulating data in the past decade show that NAMPT and NAMPT-controlled NAD metabolism regulate fundamental biological functions in endothelial cells, vascular smooth muscle cells, and endothelial progenitor cells. The NAD-consuming proteins, including sirtuins, poly-ADP-ribose polymerases (PARPs), and CD38, may contribute to the regulatory effects of NAMPT-NAD axis in these cells and vascular repair. This review discusses the current data regarding NAMPT and NAMPT-controlled NAD metabolism in vascular repair and the clinical potential translational application of NAMPT-related products in treatment of cardiovascular and cerebrovascular disease.

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/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.