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R. Farjo, D. J. Nuno, A. B. Quiambao, A. E. Stanley, R. A. Wassel, J.-X. Ma, P. Margaron; CLT-005 Reduces Retinal Vascular Leakage and Expression of Angiogenic and Inflammatory Factors in Diabetic Rats. Invest. Ophthalmol. Vis. Sci. 2009;50(13):4975.
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© ARVO (1962-2015); The Authors (2016-present)
To determine the effect of CLT-005, a novel small molecule inhibitor of Stat3, on reduction of retinal vascular leakage following intravitreal administration.
Human vascular endothelial cells (HUVEC) were stimulated with Leptin to induce Stat3 activation and treated with 2, 4, or 8 µM of CLT-005. Immunofluorescence was performed with antibodies specific to Stat3 and phosphorylated Stat3 in order to gauge nuclear translocation of Stat3. The effect of CLT-005 on reduction of retinal vascular permeability and pro-angiogenic factors in a streptozotocin-diabetic (STZ) rats was also examined. CLT-005 was administered at doses of 1, 5, 10, or 25 µg to STZ-rats by means of an intravitreal injection. For all experiments, the contralateral eye served as a control and received an equal volume of the vehicle. At 7 days post-injection, retinal vascular permeability was measured by the Evans blue extravasation assay. At 14 days post-injection, immunoblot analyses were performed to determine the expression levels of vascular endothelial growth factor (VEGF), monocyte chemoattractant protein 1 (MCP-1), and other pro-angiogenic and pro-inflammatory proteins.
At all doses tested, CLT-005 demonstrated robust inhibition of Stat3 nuclear translocation in HUVEC cells. Intravitreal administration of CLT-005 was well tolerated and all doses tested conferred a large decrease in retinal vascular permeability. At 14-days post-injection, the expression level of VEGF was nearly undetectable in eyes receiving CLT-005, compared to fellow eyes where significant levels of expression were observed. Similarly, the expression of MCP-1 was greatly reduced in eyes receiving intravitreal administration of CLT-005.
These studies demonstrate that CLT-005 is potent inhibitor of Stat3 and inhibition of this pathway in the diabetic eye causes a significant reduction in retinal vascular leakage. In addition, the in-vivo administration of CLT-005 was sufficient to reduce the expression of pro-angiogenic and pro-inflammatory genes that are regulated by Stat3. These results demonstrate the preclinical therapeutic efficacy of CLT-005 as an effective treatment for Diabetic Macular Edema, and possibly other ocular indications where neovascularization and inflammation are pathogenic features.
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