Canagliflozin Inhibits Hedgehog Interacting Protein (Hhip) Induction of Tubulopathy in Diabetic Akita Mice

Renal hedgehog interacting protein (Hhip) activates sodium-glucose cotransporter 2 (Sglt2) expression and promotes tubular senescence in murine diabetic kidney disease (DKD), yet its underlying mechanism(s) are poorly understood. Here we study the effect of the SGLT2 inhibitor, canagliflozin on tubulopathy (fibrosis and apoptosis) in Akia/Hhip^RPTC-transgenic (Tg) mice with overexpression of Hhip in their renal proximal tubular cells (RPTCs) and its relevant mechanisms. The DKD-tubulopathy with pronounced Sglt2 expression was aggravated in the kidney of Akita/Hhip^RPTC-Tg cf. Akia/non-Tg mice. A strong association between Hhip and tubular senescence in Nephroseq from the Nakagawa chronic kidney disease study. Both in vivo and in vitro, excessive Hhip in RPTCs triggered RPTC senescence (polyploidization and cytoskeleton destabilization) and released extracellular vesicles (EVs) carrying Hhip (EVs^Hhip), most of which were apoptotic bodies (ABs^Hhip) or microvesicles (MVs^Hhip) and little exosomes (EXOs^Hhip). Further, Hhip stimulated β2 microglobulin, which further interacts with EVs^Hhip, together facilitating RPTC turn-over from cellular senescence to fibrosis and/or apoptosis, ultimately leading to advanced tubulopathy. In contrast, canagliflozin administration offset the action of Hhip in RPTCs, thereby preventing DKD progression. In conclusion, canagliflozin prevented excessive Hhip-mediated tubulopathy, possibly via the inhibition of excessive Hhip carried by extracellular vehicles in DKD.