Sodium/glucose cotransporter 2 (SGLT2) inhibitors are oral hypoglycemic agents 
used to treat patients with diabetes mellitus. SGLT2 inhibitors block 
reabsorption of filtered glucose by inhibiting SGLT2, the primary glucose 
transporter in the proximal tubular cell (PTC), leading to glycosuria and 
lowering of serum glucose. We examined the renoprotective effects of the SGLT2 
inhibitor empagliflozin to determine whether blocking glucose entry into the 
kidney PTCs reduced the inflammatory and fibrotic responses of the cell to high 
glucose. We used an in vitro model of human PTCs. HK2 cells (human kidney PTC 
line) were exposed to control 5 mM, high glucose (HG) 30 mM or the profibrotic 
cytokine transforming growth factor beta (TGFβ1; 0.5 ng/ml) in the presence and 
absence of empagliflozin for up to 72 h. SGLT1 and 2 expression and various 
inflammatory/fibrotic markers were assessed. A chromatin immunoprecipitation 
assay was used to determine the binding of phosphorylated smad3 to the promoter 
region of the SGLT2 gene. Our data showed that TGFβ1 but not HG increased SGLT2 
expression and this occurred via phosphorylated smad3. HG induced expression of 
Toll-like receptor-4, increased nuclear deoxyribonucleic acid binding for 
nuclear factor kappa B (NF-κB) and activator protein 1, induced collagen IV 
expression as well as interleukin-6 secretion all of which were attenuated with 
empagliflozin. Empagliflozin did not reduce high mobility group box protein 1 
induced NF-κB suggesting that its effect is specifically related to a reduction 
in glycotoxicity. SGLT1 and GLUT2 expression was not significantly altered with 
HG or empagliflozin. In conclusion, empagliflozin reduces HG induced 
inflammatory and fibrotic markers by blocking glucose transport and did not 
induce a compensatory increase in SGLT1/GLUT2 expression. Although HG itself 
does not regulate SGLT2 expression in our model, TGFβ increases SGLT2 expression 
through phosphorylated smad3.