肝损伤改变血-视网膜屏障上BCRP和P-GP等ABC转运体功能与表达及对视网膜内药物处置影响

肝损伤病人常伴有肝性视网膜病，这与血视网膜屏障(BRB)功能损伤引起视网膜内环境紊乱和功能异常有关。鉴于BCRP、P-GP和MRP1等ABC转运体参与BRB功能维持，基于前期工作，提出“肝损伤显著改变BRB上BCRP、P-GP和MRP1功能与表达，改变视网膜内药物处置和毒性；另一方面引起视网膜内脱氢表雄酮硫酸酯等内源性物质转运改变和水平紊乱，参与肝性视网膜病病理过程”的推论。用胆管结扎和硫代乙酰胺诱导肝损伤大鼠，用特异底物和分子生物学技术研究BRB上BCRP、P-GP和MRP1功能与表达改变及机制；其改变与视网膜内脱氢表雄酮硫酸酯等水平紊乱，环孢素A等药物在视网膜中处置和毒性改变关系。用BRB细胞和视网膜组织块研究引起这些转运体功能与表达改变因素及机制，内源性物质和药物转运及毒性。用基因沉默验证。其成果有助于阐明BCRP等ABC转运体功能与表达改变在肝性视网膜病中作用及视网膜药物不良反应。

Hepatic retinopathy is an ophthalmic complication of both acute and chronic liver failure, which results from retinal dysfunction partly due to impairment of blood-retinal barrier(BRB) and retinal dyshomeostasis. Accumulating evidences have demonstrated that ABC transporters such as breast cancer resistance protein(BCRP), P-glycoprotein(P-GP) and multidrug resistance-associated protein 1(MRP1) play important roles in BRB function. Our previous study showed that liver injury induced by thioacetamide impaired BCRP and P-GP function and expression at BRB of rats. Liver failure induced by bile duct ligation impaired BCRP function and expression, but enhanced function of P-GP and expression of membrane P-GP protein at BRB of rats. Based on previous evidences, a hypotheses was proposed. i.e liver failure altered function and expression of ABC transporters such as BCRP, P-GP and MRP1 at BRB, impaired BRB intact and retinal homeostasis, participating in hepatic retinopathy and altering retinal disposition of drugs as well as their toxicities. Here, we investigated: 1)whether liver injury induced by thioacetamide and bile duct ligation altered function and expression of BCRP, P-GP and MRP1 at BRB of rats as well as real mechanism, using their specific probes, Western blot and QT-PCR; 2)effects of the altered function and expression of these ABC transporters on accumulations of endogenous compounds (such as dehydroepiandrosterone sulfate), disposition and toxicity of cyclosporin A, zidovudine and ciprofloxacin in retina of rats with liver injury. Human retinal pigment epithelial cells, human retinal vascular endothelial cells and retinal explant were used as in vitro BRB models. Effect of serum derived from rats with liver injury, ammonia and bilirubin as well as their combination on expression and function of the ABC transporters in the in vitro BRB models. The signaling proteins involved in the regulation of ABC transporters were also documented. Transport characters of dehydroepiandrosterone sulfate, cyclosporin A, zidovudine and ciprofloxacin in the in vitro BRB models were investigated. Above results were further confirmed using both in vivo and in vitro gene silence. Toxicities of endogenous compounds and the tested drugs on retina from normal rats and rats with liver failure were also documented in vivo and in vitro. The results may highlight the roles of retinal ABC transporter alteration by liver failure in development of hepatic retinopathy and prediction of drug adverse effects at retina in patents with liver injury.