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High-salt intake leads to kidney damage and even limits the effectiveness of drugs. However, it is unclear whether excessive intake of salt affects renal tubular energy metabolism and the efficacy of dapagliflozin on renal function in diabetic kidney disease (DKD). In this study, we enrolled 350 DKD patients and examined the correlation between sodium level and renal function, and analyzed influencing factors. The results demonstrated that patients with macroalbuminuria have higher 24 h urinary sodium levels. After establishment of type 2 diabetes mellitus model, the animals received a high-salt diet or normal-salt diet. In the presence of high-salt diet, the renal fibrosis was aggravated with fatty acid metabolism dysregulation. Furthermore, Na+/K+-ATPase expression was up-regulated in the renal tubules of diabetic mice, while the fatty acid metabolism was improved by inhibiting Na+/K+-ATPase of renal tubular epithelial cells. Of note, the administration with dapagliflozin improved renal fibrosis and enhanced fatty acid metabolism. But high salt weakened the above-mentioned renal protective effects of dapagliflozin in DKD. Similar results were recapitulated in vitro after incubating proximal tubular epithelial cells in high-glucose and high-salt medium. In conclusion, our results indicate that high salt can lead to fatty acid metabolism disorders by increasing Na+/K+-ATPase expression in the renal tubules of DKD. High salt intake diminishes the reno-protective effect of dapagliflozin in DKD., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Zou, Chen, Zheng, Sheng, Jia, Wang, Ren, Yang, Li, Dong, Guan, Zhang and Xue.)

Diabetic kidney disease (DKD) has become the most common cause of chronic kidney disease. Proteinuria is generally considered one of the clinical indicators of renal damage, and it is also closely related to the progression of DKD. Accumulating evidence indicates that proteinuria induces an upregulation of the expression levels of inflammatory cytokines and fibrosis markers in renal tubular epithelial cells, but the mechanism remains unclear. Previously, we showed that early growth response 1 (Egr1) played a key role in renal tubular injury. However, the upstream mechanism of Egr1 in the development of DKD is poorly understood. In this study, we found that albumin stimulation significantly increased the expression levels of Egr1, interleukin 6 (IL-6), tumor necrosis factor-α (TNF-α), and fibronectin (FN) in HK-2 cells but decreased miR-23a-3p levels. We then identified that miR-23a-3p targeted the 3' untranslated region (UTR) of Egr1 and directly suppressed the expression of Egr1. Moreover, we found that overexpression and inhibition of miR-23a-3p in HK-2 cells attenuated and promoted the expression of IL-6, TNF-α, and FN, respectively. Additionally, Egr1 silencing reversed the inflammation and fibrosis caused by the miR-23a-3p inhibitor. Thus, we conclude that miR-23a-3p attenuates the development of DKD through Egr1, suggesting that targeting miR-23a-3p may be a novel therapeutic approach for DKD., (© 2021. The Author(s).)

Background: Cardiovascular outcomes in clinical trials with type 2 diabetes mellitus (T2DM) patients have shown that glucagon-like peptide-1 receptor agonist can have a beneficial effect on the kidney. This trial aimed to assess the effects of exenatide on renal outcomes in patients with T2DM and diabetic kidney disease (DKD)., Methods: We performed a randomized parallel study encompassing 4 general hospitals. T2DM patients with an estimated glomerular filtration rate (eGFR) ≥30 mL/min/1.73 m2 and macroalbuminuria, defined as 24-h urinary albumin excretion rate (UAER) >0.3 g/24 h were randomized 1:1 to receive exenatide twice daily plus insulin glargine (intervention group) or insulin lispro plus glargine (control group) for 24 weeks. The primary outcome was the UAER percentage change from the baseline after 24 weeks of intervention. The rates of hypoglycemia, adverse events (AEs), and change in eGFR during the follow-up were measured as safety outcomes., Results: Between March 2016 and April 2019, 92 patients were randomized and took at least 1 dose of the study drug. The mean age of the participants was 56 years. At baseline, the median UAER was 1,512.0 mg/24 h and mean eGFR was 70.4 mL/min/1.73 m2. After 24 weeks of treatment, the UAER percentage change was significantly lower in the intervention group than in the control group (p = 0.0255). Moreover, the body weight declined by 1.3 kg in the intervention group (the difference between the 2 groups was 2.7 kg, p = 0.0001). Compared to the control group, a lower frequency of hypoglycemia and more gastrointestinal AEs were observed in the intervention group., Conclusion: Exenatide plus insulin glargine treatment for 24 weeks resulted in a reduction of albuminuria in T2DM patients with DKD., (The Author(s). Published by S. Karger AG, Basel.)