Absence of Na‐Glucose Cotransporter SGLT2 Does Not Protect the Kidney in a Murine Model of Renal Ischemia‐Reperfusion Injury

Abstract

The renal Na‐glucose cotransporter SGLT2 reabsorbs most of the filtered glucose in the early proximal tubule. Inhibitors of SGLT2 are glucosuric and form a new class of anti‐hyperglycemic drugs that have been proposed to reduce the risk of acute kidney injury (AKI). Here we tested whether genetic deletion of SGLT2 (KO) alters the initial kidney injury or the subsequent recovery following renal ischemia‐reperfusion (IR).Male KO and wild‐type (WT) mice (C57BL/6J) underwent sham surgery (Sham) or IR (25 min of bilateral renal artery clamping) under ketamine/xylazine anesthesia, while body temperature was maintained at 36–37°C (n=7–15/group). Urine and blood were collected at several time points. GFR was measured 14 days after IR by plasma elimination kinetics of FITC‐sinistrin in conscious mice. Kidneys were harvested 23 days after IR for renal gene expression analysis by RT‐qPCR, blinded histological analysis, and KIM‐1 and CD31 immunostaining.Plasma creatinine increased to similar levels on day 1 after IR in KO‐IR and WT‐IR (2.0±0.2 vs 1.9±0.3 mg/dL, NS) vs Sham groups (0.14±0.01 vs 0.11±0.01 mg/dL, NS). This was associated with a similar increase in urinary KIM‐1 to creatinine ratio, a marker of proximal tubule injury, and similarly reduced urine osmolality and increased plasma osmolality in KO‐IR and WT‐IR, potentially indicating impaired urine concentration. Fractional urinary glucose excretion increased from 27 to 62% in KO‐IR and from 0.1 to 20% in WT‐IR, indicating impaired tubular glucose reabsorption via SGLT1 in KO‐IR. Overall, the data indicated similar initial kidney impairment in response to IR between genotypes. In the recovery phase, GFR remained reduced on day 14 in both KO‐IR and WT‐IR (2.4±0.2 vs 2.8±0.3 μL/min/g BW, NS) vs Sham groups (12±1 vs 12±1 μL/min/g BW, NS). On day 23, plasma creatinine (0.28±0.03 vs 0.32±0.03 mg/dL, NS) was partially and similarly restored in KO‐IR and WT‐IR. Urine osmolality and renal mRNA expression of Na‐2Cl‐K cotransporter NKCC2 and renin were similarly reduced vs Sham groups, suggesting sustained impairment of thick ascending limb function. Renal mRNA expression of markers of injury, inflammation, oxidative stress, and fibrosis, (KIM‐1, NGAL, MCP‐1, NOX2, type 1 collagen, TGFB1) was similarly increased in KO‐IR and WT‐IR vs Sham groups. This was associated with similar localization and enhanced abundance of KIM‐1‐positive cells and an increased histological damage score in kidneys of IR groups. Renal CD31‐positive area and Vegfa mRNA expression were similarly reduced in KO‐IR and WT‐IR vs Sham groups suggesting similar degree of capillaries loss.The data indicate that genetic deletion of SGLT2 did not protect the kidneys in the initial injury phase or the subsequent recovery phase in a mouse model of ischemia‐reperfusion‐induced acute kidney injury, including effects on glomerular and tubular function as well as markers of inflammation, fibrosis and endothelial integrity.Support or Funding InformationNIH R01DK106102, R01DK112042, P30DK079337, and the Department of Veterans Affairs