KLF2 AGONISTS AS A NOVEL THERAPY FOR DIABETIC DISEASE

Glomerular endothelial cell (GEC) dysfunction is a key event mediating the progression of diabetic kidney disease (DKD). Krüppel-like Factor-2 (KLF2) is induced by flow-mediated shear stress and has endo-protection via its anti-inflammatory, anti-thrombotic activation, and anti-angiogenesis effects. Over the last several years, we have generated interesting data to support a critical role of KLF2 in protecting GEC injury induced by glomerular hyperfiltration, which is known to induce shear stress, in DKD. We found : 1) In humans with established DKD, reduction of KLF2 expression is associated with the progression of DKD. 2) In cultured GECs, we find that KLF2 has anti-inflammatory effects and is a key and direct regulator of eNOS expression. 3) After induction of diabetes or unilateral nephrectomy to induce glomerular hyperfiltration, mice with endothelial cell-specific KLF2 deficiency develop more severe GEC injury and kidney disease as compared to wild type mice. Here, we liked to test whether KLF2 could be a potential drug target to treat GEC injury induced by glomerular hyperfiltration in DKD.

We generated an inducible endothelial cell-specific KLF2 overexpression mouse model to test whether overexpression of KLF2 protects GEC injury in DKD mice. We used Limited Rational Design (LRD) approach to design and synthesize KLF2 agonists. We screened KLF2 agonists in cultured GECs by using qPCR assay for eNOS and confirmed by western blot analysis. We utilized the drug affinity responsive target stability (DARTS) method to confirm the interaction of KLF2 agonists with KLF2. We treated db/db mice and BTBR ob/ob mice with KLF2 agonists.

Induction of KLF2 expression in endothelial cells in diabetic mice ameliorated albuminuria and glomerular injury with increased glomerular eNOS expression. We designed and synthesized multiple KLF2 agonists by using LRD approach. Screening of these compounds identified that compound 6 (C-6) had the strongest stimulation on eNOS expression based on qPCR analysis and a dose-dependent stimulatory effect was also confirmed by western blot analysis. By DARTS approach, we confirmed that C-6 had direct interaction with KLF2 without regulation of its mRNA or protein expression, suggesting that C-6 increases the transcription of eNOS via enhancing the binding of KLF2 at eNOS promoter. To test whether C-6 has effects in vivo, we fed both db/db mice and BTBR-ob/ob mice with C-6 at 2.5mg/kg by daily gavage for 8 weeks and found a significant reduction of albuminuria and improvement of glomerular injury in these mice with no obvious toxicity.  eNOS expression was also restored in the glomeruli of these diabetic mice by treatment of C-6.

KLF2 has a major protective role against GEC injury in DKD and KLF2 agonists could be developed as potential drugs for treatment of DKD.