Mechanism Study of Dapagliflozin Improving Diabetic Nephropathy via the Gut-Kidney Axis

Academic Background

Diabetic nephropathy (DN) is one of the most common microvascular complications of diabetes, with approximately 40% of individuals with type 1 or type 2 diabetes developing DN in the advanced stages of the disease. Although clinical management primarily focuses on controlling blood glucose and preventing associated complications, evidence suggests that solely regulating hyperglycemia may not effectively impede the progression of DN. Therefore, exploring the pathogenesis of DN and developing effective therapeutic drugs is crucial.

In recent years, the role of gut microbiota in various chronic diseases has gradually gained attention. Studies have shown that dysbiosis of gut microbiota is closely related to chronic kidney disease (CKD), especially the disruption of gut barrier function, which leads to the translocation of bacteria and their metabolites into the bloodstream, triggering inflammatory responses and exacerbating kidney damage. This interaction between the gut and kidneys is known as the “gut-kidney axis.” However, the specific mechanisms of gut microbiota and its metabolites in DN remain unclear.

Dapagliflozin, a sodium-glucose cotransporter-2 (SGLT2) inhibitor, has been proven effective in lowering blood glucose and improving DN. However, whether Dapagliflozin improves DN through mechanisms beyond glycemic control remains unclear. This study aims to explore the potential mechanisms by which Dapagliflozin improves DN by modulating gut microbiota and its metabolites.

Source of the Paper

This paper was co-authored by Yinhua Ni, Haimei Du, Lehui Ke, Liujie Zheng, Sujie Nan, Liyang Ni, Yuxiang Pan, Zhengwei Fu, Qiang He, and Juan Jin. The research team comes from the College of Biotechnology and Bioengineering at Zhejiang University of Technology, the Laboratory of Food Biochemistry at the Graduate School of Agricultural and Life Sciences of the University of Tokyo, and the Department of Nephrology at the First Affiliated Hospital of Zhejiang Chinese Medical University (Zhejiang Provincial Hospital of Chinese Medicine). The paper was published in the journal American Journal of Physiology-Cell Physiology on January 1, 2025.

Research Process

1. Animal Model Construction

The study used a DN mouse model induced by a high-fat diet (HFD) combined with streptozotocin (STZ), as well as db/db diabetic mice. Mice were divided into normal chow (NC), DN, and DN+Dapagliflozin groups. Dapagliflozin was administered at low (1 mg/kg) and high doses (10 mg/kg) for 4 weeks to observe its effects on blood glucose, renal function, and gut microbiota.

2. Antibiotic Treatment

To verify the role of gut microbiota in Dapagliflozin treatment, DN mice were treated with antibiotics (ABX) to eliminate their gut microbiome, and the therapeutic effects of Dapagliflozin were observed to see if they were diminished.

3. Metabolomics Analysis

Untargeted metabolomics analysis was conducted on mouse fecal samples to detect the impact of Dapagliflozin on gut microbiota metabolites. Special attention was given to changes in argininosuccinic acid (ASA), palmitic acid (PA), and S-allylcysteine (SAC).

4. In Vitro Experiments

The human proximal tubular cell line HK-2 was treated with ASA, PA, and SAC to observe the effects of these metabolites on cellular inflammation and fibrosis and to explore the potential protective mechanisms of Dapagliflozin.

Main Results

1. Dapagliflozin Improves Renal Function

Low-dose Dapagliflozin significantly reduced urine protein and serum creatinine levels in DN mice without affecting blood glucose levels, alleviating renal inflammation and fibrosis. Histopathological analysis showed that Dapagliflozin significantly reduced inflammatory cell infiltration and collagen deposition in the kidneys.

2. Dapagliflozin Improves Gut Barrier Function

Dapagliflozin significantly increased the number of mucus-secreting cells in the colon of DN mice, reduced plasma endotoxin (LPS) levels, and improved gut barrier function. Additionally, Dapagliflozin upregulated the expression of tight junction proteins such as Claudin-1 and Occludin.

3. Dapagliflozin Modulates Gut Microbiota

16S rRNA sequencing analysis showed that Dapagliflozin significantly altered the composition of gut microbiota in DN mice, increasing the abundance of beneficial bacteria like Akkermansia and Muribaculaceae while reducing harmful bacteria like Desulfovibrionaceae.

4. Dapagliflozin Modulates Gut Microbiota Metabolites

Metabolomics analysis indicated that Dapagliflozin significantly reduced levels of ASA and PA while increasing SAC levels. ASA and PA were found to promote inflammation and fibrosis in HK-2 cells in vitro, whereas SAC had the opposite effect.

5. Antibiotic Treatment Validates the Role of Gut Microbiota

Antibiotic treatment completely abolished the protective effects of Dapagliflozin on renal function in DN mice, further confirming the critical role of gut microbiota in Dapagliflozin treatment.

Conclusion

This study reveals a new mechanism by which Dapagliflozin improves DN by modulating gut microbiota and its metabolites. Dapagliflozin not only improves DN through its glucose-lowering effects but also exerts anti-inflammatory and antifibrotic actions by reshaping the gut microbiota composition and regulating key metabolites such as ASA, PA, and SAC. Notably, the genera Muribaculaceae and Desulfovibrionaceae play pivotal roles in Dapagliflozin treatment.

Research Highlights

1. Novel Mechanism: For the first time, it reveals the mechanism by which Dapagliflozin improves DN via the gut-kidney axis, providing new insights for DN treatment.
2. Multidimensional Analysis: Combines animal models, in vitro experiments, and metabolomics analysis to comprehensively explore the mechanisms of Dapagliflozin.
3. Clinical Application Potential: The findings provide a theoretical basis for the application of Dapagliflozin in DN treatment, especially regarding its modulation of gut microbiota.

Significance of the Study

This study not only deepens the understanding of the pathogenesis of DN but also provides important references for developing DN treatment strategies based on gut microbiota. Future research can further explore the specific mechanisms of ASA, PA, and SAC in DN and how to improve DN by modulating gut microbiota and its metabolites.