Molecular Mechanisms Linking Empagliflozin to Renal Protection in the LLC-PK1 Model of Diabetic Nephropathy

Abstract

Aims: Chronic diabetes complications, including diabetic nephropathy (DN), frequently result in end-stage renal failure. This study investigated empagliflozin (SGLT2i) effects on collagen synthesis, oxidative stress, cell survival, and protein expression in an LLC-PK1 model of DN. Methods: Combinations of high glucose (HG) and increasing empagliflozin concentrations (100 nM and 500 nM), as well as combinations of HG, H2O2, and empagliflozin, were used for cell culture treatment. The cell viability, glutathione (tGSH), ECM expression, and TGF-β1 concentration were measured. In addition, the protein expression of Akt, pAkt, GSK3, pGSK3, pSTAT3, and SMAD7 was determined. Results: The addition of both concentrations of empagliflozin to cells previously exposed to glucose and oxidative stress generally improved cell viability and increased GSH levels (p < 0.001, p < 0.05). In HG30/H2O2/Empa500-treated cells, significant increase in pSTAT3, pGSK3β, GSK3β, SMAD7, and pAKT levels (p < 0.001, p < 0.001, p < 0.05) was observed except for AKT. Lower drug concentrations did not affect the protein expression levels. Furthermore, empagliflozin treatment (100 nM and 500 nM) of HG30/H2O2-injured cells led to a decrease in TGF-β1 levels (p < 0.001). In cells exposed to oxidative stress and hyperglycemia, collagen production remained unchanged. Conclusion: Renoprotective effects of empagliflozin, in this LLC-PK1 cell model of DN, are mediated via activation of the Akt/GSK-3 signalling pathway, thus reducing oxidative stress-induced damage, as well as enhanced SMAD7 expression leading to downregulation of TGF-β1, one of the key mediators of inflammation and fibrosis.

GSK3β: A ray of hope for the treatment of diabetic kidney disease

“…Empagliflozin can reduce oxidative stress and the inflammatory response in DKD by activating the AKT/GSK3β pathway. 118 Similarly, in the comparison of improving renal insulin signaling, oxidative stress, and renal function in diabetic rats, dapagliflozin is superior to metformin with dapagliflozin downregulating GSK3β, while metformin cannot, and whether this is the reason for the difference between them has not been explained in depth by the authors. 119 Furthermore, Yi Song et al found that the hsa_circRNA_012448-hsa-miR-29b-2-5p-GSK3β pathway, which is involved in the oxidative stress response, was an important pathway mediating the action of dapagliflozin against DKD.…”

“…Of note, evidence implies that the nephroprotective effect of these hypoglycemic drugs may be related to GSK3β. Empagliflozin can reduce oxidative stress and the inflammatory response in DKD by activating the AKT/GSK3β pathway 118 . Similarly, in the comparison of improving renal insulin signaling, oxidative stress, and renal function in diabetic rats, dapagliflozin is superior to metformin with dapagliflozin downregulating GSK3β, while metformin cannot, and whether this is the reason for the difference between them has not been explained in depth by the authors 119 .…”

The intellectual base and global trends in inflammation of diabetic kidney disease: a bibliometric analysis

“…The modulation of IGF1R expression presents a potentially innovative strategy for treating DKD [ 56 ]. Furthermore, it has been observed that empagliflozin exhibits a mitigating effect on harm caused by oxidative stress through the activation of the Akt/GSK-3 signaling pathway [ 57 ] and the PPAR gamma/CD36 pathway [ 58 ]. Dapagliflozin enhances the inflammatory response in DKD by augmentation of AMPK activity and suppressing the inflammatory response mediated by the NF-κB pathway, thereby ameliorating the long-term prognosis of individuals with DKD [ 59 ].…”