Abstract
Purpose: This study aimed to examine the effects of Empagliflozin on the mice model of HFD/STZ-induced T2DM and liver fibrosis, and the correlations with gut microbiota.
Methods: The HFD/STZ-induced T2DM and liver fibrosis mice were treated with Empagliflozin for 6 weeks. After the intervention, OGTT and IPGTT were performed to assess glucose tolerance and insulin resistance in mice. The histological chemistry and indicators of liver pathology and liver fibrosis were assessed. Moreover, 16S rRNA amplicon sequencing for gut microbiota was performed to explore the changes of gut bacterial composition. And we analyzed the correlation between alterations in intestinal microbial composition and liver fibrosis score or glucose metabolic indicators.
Results: 6-week Empagliflozin intervention improved glucose metabolism, and attenuated liver fibrosis in HFD/STZ-induced mice, which might be related to the alterations of gut microbiota. Furthermore, the abundance of Lactobacillus was increased, whileRuminococcus and Adlercreutzia were reduced in Empagliflozin-treated mice, which were positively associated with liver fibrosis and glucose metabolism in correlation analysis.
Conclusion: Empagliflozin ameliorated glucose metabolic dysfunction and liver fibrosis in HFD/STZ-induced mice, whose effects might be due to the beneficial balance of gut microbiota composition. Our study provided evidence and highlighted improvement of gut-liver axis by inhibition of SGLT2 in T2DM and liver fibrosis.
Key Words: SGLT2 inhibitors, Liver fibrosis, T2DM, Gut microbiota, Gut-liver axis
INTRODUCTION
Liver fibrosis is the end-stage outcome of chronic liver injury induced by various factors such as non-alcoholic fatty liver disease (NAFLD), alcohol abuse, and chronic viral infections1. NAFLD has been identified as a major inducer of liver fibrosis, and diabetes mellitus (DM) has been reported to accelerate the progression of NAFLD to liver fibrosis, cirrhosis, and hepatocellular carcinoma (HCC)2,3. Insulin resistance and intestinal flora are potential mechanisms contributing to the development of liver fibrosis in the context of the complex interaction between DM and NAFLD4. However, the available interventions for liver fibrosis are currently limited5. Further research is needed to explore potential pharmacotherapy targeting the underlying common pathological mechanisms of NAFLD and DM to alleviate liver fibrosis.
Sodium-glucose cotransporter 2 (SGLT2) inhibitors (including Dapagliflozin, Canagliflozin and Empagliflozin) are novel hypoglycemic agents that lower blood glucose mainly by inhibiting glucose reabsorption from the proximal tubules of the kidney and increasing urinary glucose excretion6. In recent years, several studies have shown that SGLT2 inhibitors may improve liver fibrosis in addition to significant hypoglycemic effects7,8. A multicenter, randomized controlled trial (RCT) revealed that long-term ipragliflozin treatment ameliorates liver fibrosis in patients with NAFLD and T2DM9. Another study based on real-world data also showed that SGLT2 inhibitors not only lowered blood glucose but also improved liver fatty infiltration and fibrosis in patients with NAFLD and T2DM, suggesting that SGLT2 inhibitors may be potential drugs for anti-liver fibrosis10. Interestingly, another study also discovered that Empagliflozin improves liver fibrosis in patients with NAFLD without T2DM, indicating that SGLT2 inhibitors may ameliorate liver fibrosis through non-hypoglycemic effects11. However, the anti-fibrotic effect of SGLT2 inhibitors still needs to be further confirmed, and it remains unclear whether SGLT2 inhibitors can alleviate liver fibrosis through other mechanisms rather than glycemic control or weight reduction. Since it remains uncertain whether SGLT2 is expressed in the liver, the anti-fibrotic effect of SGLT2 inhibitors may be indirectly through the improvement of insulin resistance or gut microbiota4.
In recent years, a number of studies have found that SGLT2 inhibitors seem to be able to regulate intestinal flora and play a protective role in many diseases12,13. Hao et al. found that Empagliflozin can mitigate atherosclerosis partly by regulating intestinal microbiota14. Similarly, Deng et al. also reported that Empagliflozin can ameliorate type 2 diabetes mellitus-related diabetic nephropathy via altering the gut microbiota15. These evidences indicate that SGLT2 inhibitors can regulate gut microbiota and play a significant role in improving diseases. Notably, dysbiosis of the gut microbiota has been observed in patients with T2DM and NAFLD, highlighting its association with these conditions16,17. Therefore, it is plausible that SGLT2 inhibitors attenuate liver fibrosis by modulating the gut microbiota. However, the interactions among SGLT2 inhibitors, gut microbiota, and liver fibrosis remain unclear and necessitate further investigation. Consequently, the aim of the present study is to provide additional evidence regarding the therapeutic effects of SGLT2 inhibitors on liver fibrosis using a high-fat diet/streptozotocin (HFD/STZ)-induced T2DM and liver fibrosis mouse model and explore the potential relationship between the observed anti-fibrotic effects and modulation of the gut microbiota.
RESULTS
2.1 Empagliflozin had no significant effect on body weight and food intake inHFD/STZ-induced T2DM mice
To observe the effects of SGLT2 inhibitors on liver fibrosis, HFD/STZ-induced liver fibrosis with type 2 diabetes mellitus models were treated with Empagliflozin (Figure 1A). Compared to the Chow diet group, the body weight of mice in HFD group increased significantly (P < 0.05), while mice showed a significant decrease in body weight (P < 0.05) and a significant increase in blood glucose (P < 0.05) after intraperitoneal injection of STZ at week 8 (Supplementary Figure 1 and 2). After 6 weeks of Empagliflozin administration, no significant changes were observed both in body weight (Figure 1B) and food intake (Supplementary Figure 3).