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Angiotensin receptor blockers (ARB) and sodium‑glucose co‑transporter 2 (SGLT2) inhibitors are well known to confer renal protective effects in diabetic kidney disease; however, their synergistic effects when used in combination are not well understood.
Human kidney-2 (HK‑2) cells were divided into five groups: 1) normal glucose (5.5 mM), 2) high glucose (HG, 25 mM), 3) HG + candesartan (1μM), 4) HG + SGLT2 inhibitor (dapagliflozin 10 μM), and 5) HG + candesartan + SGLT2 inhibitor combination treatment groups. The levels of inflammation and fibrosis markers were evaluated by using real time quantitative polymerase chain reaction and western blotting techniques. The changes in the high-mobility group box-1 (HMGB1), receptor for advanced glycation end products (RAGE), and nuclear factor kappa B (NF-kB) signaling pathway, known to be upregulated in HG conditions, were compared among the different groups.
HG increased mRNA and protein expression levels of factors associated with renal fibrosis and inflammatory response including transforming growth factor-β (TGF-β), α-smooth muscle actin (α-SMA), connective tissue growth factor (CTGF), collagen type I alpha 1 chain (COL1A1), fibronectin, and tumor necrosis factor-α (TNF-α). In addition, HG decreased the expression of E-cadherin. Treatment with candesartan and/or SGLT2 inhibitor effectively attenuated these changes in mRNA and protein expressions. In particular, SGLT2 inhibitor treatment on top of candesartan showed additive effect in reduction of EMT and inflammatory signals compared to candesartan monotherapy. HG group exhibited increased expressions of HMGB1, RAGE, and NF-kB, and treatment with either candesartan or SGLT2 inhibitor effectively reversed the upregulation of these molecules.
Our results suggest addition of SGLT2 inhibitor to ARB treatment is more effective than the candesartan monotherapy for preventing inflammation in HG stimulated HK-2 cells.