SGLT2 Inhibition by Dapagliflozin Attenuates Diabetic Ketoacidosis in Mice with Type-1 Diabetes

SGLT2 inhibitors: how do they affect the cardiac cells

The first sodium-glucose cotransporter-2 inhibitor (SGLT2I), canagliflozin, was approved by the U.S. Food and Drug Administration for the treatment of type 2 diabetes in 2013. Since then, other members of this drug class (such as dapagliflozin, empagliflozin, and ertugliflozin) have become widely used. Unlike classical antidiabetic agents, these drugs do not interfere with insulin secretion or action, but instead promote renal glucose excretion. Since their approval, many preclinical and clinical studies have been conducted to investigate the diverse effects of SGLT2Is. While originally introduced as antidiabetic agents, the SGLT2Is are now recognized as pillars in the treatment of heart failure and chronic kidney disease, in patients with or without diabetes. The beneficial cardiac effects of this class have been attributed to several mechanisms. Among these, SGLT2Is inhibit fibrosis, hypertrophy, apoptosis, inflammation, and oxidative stress. They regulate mitochondrial function and ion transport, and stimulate autophagy through several underlying mechanisms. This review details the potential effects of SGLT2Is on cardiac cells.

Critical Reanalysis of the Mechanisms Underlying the Cardiorenal Benefits of SGLT2 Inhibitors and Reaffirmation of the Nutrient Deprivation Signaling/Autophagy Hypothesis

SGLT2 (sodium-glucose cotransporter 2) inhibitors produce a distinctive pattern of benefits on the evolution and progression of cardiomyopathy and nephropathy, which is characterized by a reduction in oxidative and endoplasmic reticulum stress, restoration of mitochondrial health and enhanced mitochondrial biogenesis, a decrease in proinflammatory and profibrotic pathways, and preservation of cellular and organ integrity and viability. A substantial body of evidence indicates that this characteristic pattern of responses can be explained by the action of SGLT2 inhibitors to promote cellular housekeeping by enhancing autophagic flux, an effect that may be related to the action of these drugs to produce simultaneous upregulation of nutrient deprivation signaling and downregulation of nutrient surplus signaling, as manifested by an increase in the expression and activity of AMPK (adenosine monophosphate-activated protein kinase), SIRT1 (sirtuin 1), SIRT3 (sirtuin 3), SIRT6 (sirtuin 6), and PGC1-α (peroxisome proliferator-activated receptor γ coactivator 1-α) and decreased activation of mTOR (mammalian target of rapamycin). The distinctive pattern of cardioprotective and renoprotective effects of SGLT2 inhibitors is abolished by specific inhibition or knockdown of autophagy, AMPK, and sirtuins. In the clinical setting, the pattern of differentially increased proteins identified in proteomics analyses of blood collected in randomized trials is consistent with these findings. Clinical studies have also shown that SGLT2 inhibitors promote gluconeogenesis, ketogenesis, and erythrocytosis and reduce uricemia, the hallmarks of nutrient deprivation signaling and the principal statistical mediators of the ability of SGLT2 inhibitors to reduce the risk of heart failure and serious renal events. The action of SGLT2 inhibitors to augment autophagic flux is seen in isolated cells and tissues that do not express SGLT2 and are not exposed to changes in environmental glucose or ketones and may be related to an ability of these drugs to bind directly to sirtuins or mTOR. Changes in renal or cardiovascular physiology or metabolism cannot explain the benefits of SGLT2 inhibitors either experimentally or clinically. The direct molecular effects of SGLT2 inhibitors in isolated cells are consistent with the concept that SGLT2 acts as a nutrient surplus sensor, and thus, its inhibition causes enhanced nutrient deprivation signaling and its attendant cytoprotective effects, which can be abolished by specific inhibition or knockdown of AMPK, sirtuins, and autophagic flux.

The impact of SGLT2 inhibitors on inflammation: A systematic review and meta-analysis of studies in rodents

BACKGROUND

Inhibition of sodium-glucose cotransporter-2 (SGLT2) has received remarkable attention due to the beneficial effects observed in diabetes mellitus, heart failure, and kidney disease. Several mechanisms have been proposed for these pleiotropic effects, including anti-inflammatory ones. Our systematic review and meta-analysis aimed to assess the effect of SGLT2 inhibition on inflammatory markers in experimental models.

METHODS

A literature search was conducted to detect studies examining the effect of SGLT2 inhibitors on inflammatory markers [interleukin-6 (IL-6), C reactive protein (CRP), tumor necrosis factor-α (TNF-α), and monocyte chemoattractant protein-1 (MCP-1)]. Consequently, a meta-analysis of the included studies was performed, assessing the differences in the levels of the inflammatory markers between the treatment groups as its primary outcome. Moreover, risk of bias, sensitivity analysis and publication bias were evaluated.

RESULTS

The systematic literature review yielded 30 studies whose meta-analysis suggested that treatment with an SGLT2 inhibitor resulted in decreases of IL-6 [standardized mean difference (SMD): -1.56, 95% CI -2.06 to -1.05), CRP (SMD: -2.17, 95% CI -2.80 to -1.53), TNF-α (SMD: -1.75, 95% CI -2.14 to -1.37), and MCP-1 (SMD: -2.04, 95% CI -2.91 to -1.17). The effect on CRP and TNF-α was of lesser magnitude in cases of empagliflozin use. Moderate-to-substantial heterogeneity and possible publication bias were noted. The findings remained largely unaffected after the sensitivity analyses, the exclusion of outlying studies, and trim-and-fill analyses.

CONCLUSION

The present meta-analysis suggests that SGLT2 inhibition results in reduction of inflammatory markers in animal models, further validating the suggested anti-inflammatory mechanism of action.