钠葡萄糖共转运体抑制剂抑制有氧糖酵解治疗多囊肾病的分子机制研究

Autosomal dominant polycystic kidney disease (ADPKD) is the most common inherited kidney disease. However, the molecular mechanism of the pathogenesis of ADPKD is still unclear and specific drug therapy is lacking. Recently, there is a novel finding that the aerobic glycolysis plays an important role in the pathogenesis of ADPKD, which might be due to the inhibition of LKB1-AMPK axis by over activated pERK1/2 (Nature Med. 2013, 19(4):488-493). Inhibition of the aerobic glycolysis might be a new therapeutic strategy for treating ADPKD. Sodium glucose cotrasnporter (SGLT) plays an important role in modulating the glucose metabolism. We recently reported that SGLTs are over-expressed in kidney tissues of ADPKD, and SGLT inhibitor could inhibit the proliferation of tubular and cystic epithelial cells, retard the progression of renal cysts, lower the 2-kidneys/body weight ratio, and improve renal function (Kidney Int. 2013, 84(5):962-968). We also showed that SGLT inhibitor could decrease the lactate concentration in cyst and down-regulate the level of pERK1/2 both in vivo and in vitro, which strongly suggesting the therapeutic effect of SGLT inhibitor on ADPKD might be due to its inhibition of the aerobic glycolysis. Therefore, in the present study, we will clarify whether SGLT inhibitor retarded the progression of ADPKD through inhibition of aerobic glycolysis and decipher its molecular mechanism. This study will provide experimental and theoretical rationale for using SGLT inhibitor as therapeutic agent for the treatment of ADPKD in the future.

常染色体显性多囊肾病（ADPKD）是最常见的遗传性肾病，至今分子机制尚未阐明，无特效治疗手段。ADPKD囊肿上皮细胞中有氧糖酵解(aerobic glycolysis, AG)增加促进细胞过度增殖是其最新病理生理机制，抑制AG对Pkd1-/-小鼠有治疗作用。pERK1/2上调进而抑制LKB1-AMPK通路在AG中发挥重要作用。前期研究中我们发现SGLT在ADPKD大鼠肾组织高表达，新型降糖药物SGLT抑制剂能抑制囊肿上皮细胞增殖、延缓囊肿增长，改善肾功能(Kidney Int 2013;84:962-8)。此外，我们还发现SGLT抑制剂能降低囊液中乳酸浓度、下调pERK1/2表达，提示SGLT抑制剂对ADPKD的治疗作用很可能与其抑制AG有关。因此，本项目拟运用多种技术，在体内/外模型中阐明SGLT抑制剂通过抑制AG治疗ADPKD的分子机制，为应用SGLT抑制剂治疗ADPKD提供实验依据。

寻找多囊肾病新的治疗靶点是近年来多囊肾病治疗领域的研究热点。课题组前期研究中发现 非选择性SGLT抑制剂Phlorizin对多囊肾病大鼠肾功能有保护作用。肾脏表达两类SGLT：SGLT1和SGLT2。因此，有必要先明确究竟是SGLT1还是SGLT2的作用更重要，为后续研究选择合适的选择性SGLT抑制剂。结果发现选择性SGLT2抑制剂DAPA尽管可改善Han:SPRD大鼠肾功能，但增加了肾重，对囊肿指数、肾小管上皮细胞增殖、炎症细胞侵润和间质纤维化无明显影响，提示其对抑制囊肿进展没有作用。由于Han:SPRD大鼠的囊肿主要起源于肾脏近曲小管，课题组另外选择了远曲小管和集合管起源的大鼠囊肿模型PCK大鼠来观察DAPA对其影响。结果显示DAPA处理对PCK大鼠肾功能无影响，且增加了肾重和囊肿指数，对肾小管上皮细胞增殖无明显作用，提示SGLT2抑制剂加重了远曲小管和集合管来源的囊肿生成。上述结果表明选择性SGLT2抑制剂对多囊肾病大鼠的肾脏保护作用不如非选择性SGLT抑制剂，提示SGLT1通路可能起更重要作用，但SGLT1抑制剂因副作用大，临床应用价值有限。由于本研究最终目标是“阐明SGLT抑制剂治疗多囊肾病的分子机制，为运用SGLT抑制剂治疗多囊肾病提供实验依据”，而依据前述研究结果，课题组判断SGLT通路可能不是一个好的多囊肾病治疗靶点，按照原计划继续进行SGLT抑制剂作用机制的研究已无意义。鉴于意外结果的出现，课题组另外开展了PKD1对肾脏上皮细胞氧化磷酸化和糖酵解代谢的影响及可能机制研究。结果发现，与正常人肾脏上皮细胞系UCL-93相比，多囊肾病患者肾脏上皮细胞系OX161氧化磷酸化水平降低、糖酵解水平增加。后续正在利用PKD1 siRNA瞬染及PKD1 shRNA lenti-virus转染，观察敲低PKD1对氧化磷酸化和糖酵解代谢的影响，并研究其可能机制。