Gerhardinger Chiara, Dagher Zeina, Sebastiani Paola, Park Yong Seek, Lorenzi Mara
Schepens Eye Research Institute and Department of Ophthalmology, Harvard Medical School, Boston, MA, USA.
Diabetes. 2009 Jul;58(7):1659-67. doi: 10.2337/db08-1008. Epub 2009 Apr 28.
Prevention of diabetic retinopathy would benefit from availability of drugs that preempt the effects of hyperglycemia on retinal vessels. We aimed to identify candidate drug targets by investigating the molecular effects of drugs that prevent retinal capillary demise in the diabetic rat.
We examined the gene expression profile of retinal vessels isolated from rats with 6 months of streptozotocin-induced diabetes and compared it with that of control rats. We then tested whether the aldose reductase inhibitor sorbinil and aspirin, which have different mechanisms of action, prevented common molecular abnormalities induced by diabetes. The Affymetrix GeneChip Rat Genome 230 2.0 array was complemented by real-time RT-PCR, immunoblotting, and immunohistochemistry.
The retinal vessels of diabetic rats showed differential expression of 20 genes of the transforming growth factor (TGF)-beta pathway, in addition to genes involved in oxidative stress, inflammation, vascular remodeling, and apoptosis. The complete loop of TGF-beta signaling, including Smad2 phosphorylation, was enhanced in the retinal vessels, but not in the neural retina. Sorbinil normalized the expression of 71% of the genes related to oxidative stress and 62% of those related to inflammation. Aspirin had minimal or no effect on these two categories. The two drugs were instead concordant in reducing the upregulation of genes of the TGF-beta pathway (55% for sorbinil and 40% for aspirin) and apoptosis (74 and 42%, respectively).
Oxidative and inflammatory stress is the distinct signature that the polyol pathway leaves on retinal vessels. TGF-beta and apoptosis are, however, the ultimate targets to prevent the capillary demise in diabetic retinopathy.
若能获得可预先阻止高血糖对视网膜血管产生影响的药物，将有助于预防糖尿病视网膜病变。我们旨在通过研究可预防糖尿病大鼠视网膜毛细血管病变的药物的分子效应，来确定候选药物靶点。
我们检测了链脲佐菌素诱导糖尿病6个月的大鼠视网膜血管的基因表达谱，并将其与对照大鼠的进行比较。然后我们测试了作用机制不同的醛糖还原酶抑制剂索比尼尔和阿司匹林是否能预防糖尿病诱导的常见分子异常。采用实时逆转录聚合酶链反应、免疫印迹和免疫组织化学对Affymetrix GeneChip大鼠基因组230 2.0芯片进行补充研究。
除了参与氧化应激、炎症、血管重塑和细胞凋亡的基因外，糖尿病大鼠的视网膜血管还显示出转化生长因子（TGF）-β通路的20个基因的差异表达。TGF-β信号的完整环路，包括Smad2磷酸化，在视网膜血管中增强，但在神经视网膜中未增强。索比尼尔使71%与氧化应激相关的基因和62%与炎症相关的基因的表达恢复正常。阿司匹林对这两类基因的影响极小或无影响。相反，这两种药物在降低TGF-β通路基因的上调（索比尼尔为55%，阿司匹林为40%）和细胞凋亡（分别为74%和42%）方面是一致的。
氧化应激和炎症应激是多元醇通路在视网膜血管上留下的独特印记。然而，TGF-β和细胞凋亡是预防糖尿病视网膜病变中毛细血管病变的最终靶点。
