Intervention with Cilostazol Attenuates Retinal Inflammation in a Streptozotocin-Induced Diabetic Animal Model
Date Issued
2010
Date
2010
Author(s)
Huang, Yu-Hsun
Abstract
1.Background:
Among working adults in developed countries, diabetic retinopathy (DR) remains the leading cause of blindness and visual impairment. New evidence indicates that DR shares similarities with chronic inflammatory disease, and inflammation may play a central role in the development of DR. In diabetes, leukocytes become less deformable and retinal leukostasis increases, corresponding to the fact that the expression of cellular adhesion molecules such as intercellular adhesion molecule-1 (ICAM-1) are increased in retinal vasculature, which affects retinal endothe¬lial function, retinal perfusion, angiogen¬esis and vascular permeability. The inflamed retina tissues release increased levels of adhesion molecules, cytokines and chemokines for leukocyte recruitment. The concentrations of inflammatory mediators such as monocyte chemoattractant protein-1 (MCP-1) and fracktalkine (FKN) are reported to be increased in the vitreous of patients with proliferative diabetic retinopathy.
It has been suggested that increased oxidative stress, which generates excess reactive oxygen species (ROS), is a key point in the pathogenesis of DR. The use of appropriate antioxidants may have potential to inhibit the inflammatory changes in the development of DR in animals, including activation of NF-κB, leukostasis, and formation of ROS with the ability of scavenging free radicals, or increasing the antioxidants defense enzyme capabilities.
Cilostazol, is a phosphodiesterase 3 (PDE3) inhibitor which results in inhibition of platelet aggregation and vasodilation leading to reduction in arterial pressure. Among recent studies, potent anti-inflammatory and anti-oxidative effects of cilostazol were shown through the suppression of cytokines, adhesion molecules, and other inflammatory mediators leading to leukocyte-endothelial cell interactions and platelet-mediated tissue damage after transient retina ischemia. Besides, it has been reported that cilostazol could reduce inflammatory burden and oxidative stress in hypertensive type 2 diabetes mellitus patients.
We hypothesized that cilostazol inhibits the expression of various inflammatory mediators and adhesion molecules such as MCP-1, FKN and ICAM-1 by blocking NF-κB activation in the development of DR. Treatment with cilostazol could also increase the activity of antioxidants defense enzymes and reduce levels of oxidatively modified DNA (8-hydroxy-2''-deoxyguanosine), oxidatively protein (nitrotyrosine) and oxidative lipids (acrolein) in the diabetic retina. We will assess retinal expression of these inflammatory mediators and oxidative stress biomarkers in streptozotocin (STZ) induced diabetic rat model and set up cilostazol treatment model to define the possible anti-inflammatory and anti-oxidative effect of cilostazol in DR.
2.Material and methods:
Thirty 6 weeks old female Wistar rats with the body weight about 200-250g were divided into a normal control group (n=10) and a STZ-induce diabetic group (n=20). Twenty rats were intraperitoneally injected with STZ to induce diabetes. Eight weeks later, the eyeball of each rat was taken out to obtain fresh retina tissues. We performed polymerase chain reaction (PCR), western blot analysis, hematoxylin and Eosin (H&E) and immunohistochemical staining to assess ICAM-1, MCP-1 and FKN in the retina of rats. The concentrations of ICAM-1, MCP-1 and FKN in the aqueous humor and vitreous cavity were examined by enzyme-linked immunosorbent assay (ELISA). The nuclear factor (NF)-κB activity was assessed by IHC and electrophoresis mobility shift assay (EMSA). Besides, the contents of 8-OHdG, nitrotyrosine and acrolein in the retina were measured by IHC in order to evaluate the change of oxidative stress in the diabetic retina.
3.Results and discussions:
The administration of cilostazol for eight weeks in diabetic rats did not alter the blood glucose levels compared with untreated diabetic rats. Cilostazol inhibits the increase of ICAM-1, MCP-1 and FKN mRNA and protein expression in the retina, as well as the increase of ICAM-1, MCP-1 and FKN contents in the aqueous humor and vitreous cavity. Consistent with these findings, cilostazol attenuated the enhanced activation of NF-κB in diabetic rats by IHC and EMSA findings. The levels of oxidatively modified DNA (8-OHdG), nitrotyrosine and oxidative lipids (acrolein) were also diminished in the cilostazol-treated diabetic group.
4.Conclusions:
Cilostazol reduces inflammatory reactions and oxidative stress in the development of DR. The anti-inflammatory effects of cilostazol is supposed to be mediated by the inhibition of NF-κB activity, and the subsequent decrease in inflammatory mediators such as ICAM-1, MCP-1 and FKN expression in the retina. The effects of cilostazol had been widely studied in the treatment of diabetic vasculopathy, neuropathy, nephropathy and retinopathy of the animal model. In the future, cilostazol may be clinically applied in the treatment of diabetic patients to avoid progressive visual loss.
Subjects
Cilostazol
Diabetic retinopathy
Oxidative stress
ROS (reactive oxygen species)
Angiogenesis
SDGs
Type
thesis
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