Mechanistic View on the Effects of SGLT2 Inhibitors on Lipid Metabolism in Diabetic Milieu

Sodium-glucose cotransporter 2 inhibitors and renin-angiotensin-aldosterone system, possible cellular interactions and benefits

Sodium glucose cotransporter 2 inhibitors (SGLT2is) are a newly developed class of anti-diabetics which exert potent hypoglycemic effects in the diabetic milieu. However, the evidence suggests that they also have extra-glycemic effects. The renin-angiotensin-aldosterone system (RAAS) is a hormonal system widely distributed in the body that is important for water and electrolyte homeostasis as well as renal and cardiovascular function. Therefore, modulating RAAS activity is a main goal in patients, notably diabetic patients, which are at higher risk of complications involving these organ systems. Some studies have suggested that SGLT2is have modulatory effects on RAAS activity in addition to their hypoglycemic effects and, thus, these drugs can be considered as promising therapeutic agents for renal and cardiovascular disorders. However, the exact molecular interactions between SGLT2 inhibition and RAAS activity are not clearly understood. Therefore, in the current study we surveyed the literature for possible molecular mechanisms by which SGLT2is modulate RAAS activity.

SGLT2 inhibition, blood lipids, and cardiovascular disease: A Mendelian randomization study

AIMS

We aim to investigate the causal effect of blood lipids mediating sodium-glucose cotransporter 2 (SGLT2) inhibition in cardiovascular disease (CVD) using Mendelian randomization (MR).

METHODS AND RESULTS

A two-sample two-step MR study was conducted to evaluate the association of SGLT2 inhibition with CVDs and the mediation effects of blood lipids linking SGLT2 inhibition with CVDs. Genetic instruments for SGLT2 inhibition were identified as genetic variants, which were associated with the expression of the SLC5A2 gene and glycated haemoglobin level (HbA1c). SGLT2 inhibition was associated with reduced risk of heart failure (HF) (OR 0.44 [95% CI 0.32-0.61]; P = 6.0 × 10-7), atrial fibrillation (AF) (0.47 [0.37-0.61]; P = 1.81 × 10-8), coronary artery disease (CAD) (0.47 [0.30-0.73]; P = 7.46 × 10-4), myocardial infarction (MI) (0.30 [0.15-0.61]; P = 7.44 × 10-4), any stroke (AS) (0.28 [0.18-0.42]; P = 1.14 × 10-9), and ischaemic stroke (IS) (0.27 [0.17-0.44]; P = 1.97 × 10-7). Our results indicated that the proportion mediated of the mediating effect of total cholesterol was 1.7% (OR 0.99 [95% CI 0.98, 0.99], P = 0.004), 4.7% (0.96 [0.95, 0.98], P = 0.002), and 2.7% (0.97 [0.95, 0.98], P = 0.002) in the association between SGLT2 inhibition and the risk of HF, CAD, and MI, respectively. For low-density lipoprotein cholesterol, the proportion mediated of the mediating effect was 2.2% for HF (OR 0.98 [95% CI 0.98, 0.99], P = 0.003), 8.6% for CAD (0.93 [0.91, 0.95], P = 5.74 × 10-4), and 5.0% for MI (0.95 [0.94, 0.96], P = 6.97 × 10-4). For non-high-density lipoprotein cholesterol, the proportion mediated of the mediating effect was 3.4% for HF (OR 0.98 [95% CI 0.97, 0.98], P = 4.42 × 10-6), 11.8% for CAD (0.92 [0.90, 0.93], P = 7.23 × 10-8), 5.7% for MI (0.94 [0.92, 0.95], P = 8.17 × 10-7), 1.5% for AS (0.98 [0.98, 0.99], P = 0.001), and 1.4% for IS (0.98 [0.98, 0.99], P = 0.004).

CONCLUSIONS

Our study showed the association of SGLT2 inhibition with the reduced risk of CVDs and blood lipids might mediate this association.

Empagliflozin alters lipid metabolism in the myocardium and liver in a prediabetes model with severe dyslipidemia

Background and aims

Recent studies suggest that empagliflozin reduces total and cardiovascular mortality in both diabetic and nondiabetic subjects. Although the exact mechanism is unclear, it is understood to positively affect myocardial energetics, including the metabolism of ketone bodies, lipids, and fatty acids. In this study, we compared empagliflozin effects on lipid metabolism in the heart and liver in a prediabetic rat model with severe dyslipidemia.

Materials and methods

Wistar rats served as the control group, while hereditary hypertriglyceridemic (HHTg) rats were used as a nonobese, prediabetic model. Rats were treated with or without empagliflozin at a dose of 10 mg/kg body weight (BW) for 8 weeks.

Results

In HHTg rats, empagliflozin decreased body weight and adiposity, improved glucose tolerance, and decreased serum triacylglycerols (TAGs) (p < 0.001). Empagliflozin decreased the activity and gene expression of the lipogenic enzyme SCD-1 (p < 0.001) in the myocardium, which may have led to a decrease in the ectopic accumulation of TAGs and lipotoxic diacylglycerols and lysophosphatidylcholines (p < 0.001). Changes in the myocardial phosphatidylcholine/phosphatidylethanolamine ratio (p < 0.01) and in the fatty acid profile of myocardial phospholipids may have contributed to the antifibrotic effects of empagliflozin. The anti-inflammatory effects of empagliflozin were evidenced by an increased IL-10/TNFα ratio (p < 0.001), a marked decrease in arachidonic acid metabolites (20-HETE, p < 0.001), and an increase in PUFA metabolites (14,15-EETs, p < 0.001) in the myocardium. However, empagliflozin did not significantly affect either the concentration or utilization of ketone bodies. In the liver, empagliflozin decreased lipogenesis and the accumulation of TAGs and lipotoxic intermediates. Its effect on arachidonic acid metabolites and alterations in n-3 PUFA metabolism was less pronounced than in the myocardium.

Conclusion

Our findings suggest that empagliflozin treatment in the heart and liver reduced the accumulation of neutral lipids and lipotoxic intermediates and altered the metabolism of n-3 PUFA. In the heart, empagliflozin altered arachidonic acid metabolism, which is likely associated with the anti-inflammatory and antifibrotic effects of the drug. We assume that these alterations in lipid metabolism contribute to the cardioprotective effects of empagliflozin in prediabetic states with severe dyslipidemia.

Modulating effects of crocin on lipids and lipoproteins: Mechanisms and potential benefits

Dyslipidemia poses a significant risk to cardiovascular health in both diabetic and non-diabetic individuals. Therefore, it is crucial to normalize lipid homeostasis in order to prevent or minimize complications associated with dyslipidemia. However, pharmacological interventions for controlling lipid metabolism often come with adverse effects. As an alternative, utilizing herbal-based agents, which typically have fewer side effects, holds promise. Crocin, a naturally occurring nutraceutical, has been shown to impact various intracellular pathways, reduce oxidative stress, and alleviate inflammatory processes. Recent evidence suggests that crocin may also confer lipid-related benefits and potentially contribute to the normalization of lipid homeostasis. However, the specific advantages and the cellular pathways involved are not yet well understood. In this review, we present the latest findings regarding the lipid benefits of crocin, which could be instrumental in preventing or reducing disorders associated with dyslipidemia. Additionally, we explore the potential cellular mechanisms and pathways that mediate these lipid benefits.

Comparing the effects of empagliflozin and liraglutide on lipid metabolism and intestinal microflora in diabetic mice

Background and Objectives

Recent studies have shown that the imbalance of intestinal flora is related to the occurrence and progression of diabetic nephropathy (DN) and can affect lipid metabolism. Sodium-dependent glucose transporters 2 (SGLT2) inhibitor and glucagon-like peptide-1 (GLP-1) receptor agonist are commonly used hypoglycemic drugs and have excellent renal safety. The purpose of this study was to compare the protective effects of empagliflozin and liraglutide on kidneys, lipid metabolism, and intestinal microbiota in diabetic mice.

Methods

We established a mouse model of type two diabetes by feeding rats a high-fat diet (HFD) followed by an intraperitoneal injection of STZ. The mice were randomly divided into groups: normal control (NC), diabetic model (DM), liraglutide treatment (LirT), empagliflozin treatment (EmpT), and liraglutide combined with empagliflozin treatment (Emp&LirT) groups. Blood glucose, lipids, creatinine, and uric acid, as well as urinary nitrogen and albumin levels were measured. The renal tissues were subjected to HE, PAS and Masson's staining. These parameters were used to evaluate renal function and histopathological changes in mice. Mice feces were also collected for 16sRNA sequencing to analyze the composition of the intestinal flora.

Results

All the indexes related to renal function were significantly improved after treatment with drugs. With respect to lipid metabolism, both drugs significantly decreased the serum triglyceride levels in diabetic mice, but the effect of liraglutide on reducing serum cholesterol was better than that of empagliflozin. However, empagliflozin had a better effect on the reduction of low-density lipoproteins (LDL). The two drugs had different effects on intestinal flora. At the phylum level, empagliflozin significantly reduced the ratio of Firmicutes to Bacteroidota, but no effect was seen with liraglutide. At the genus level, both of them decreased the number of Helicobacter and increased the number of Lactobacillus. Empagliflozin also significantly increased the abundance of Muribaculaceae, Muribaculum, Olsenella, and Odoribacter, while liraglutide significantly increased that of Ruminococcus.

Conclusion

Liraglutide and empagliflozin were both able to improve diabetes-related renal injury. However, the ability of empagliflozin to reduce LDL was better compared to liraglutide. In addition, their effects on the intestine bacterial flora were significantly different.

Antifibrotic effects of sodium-glucose cotransporter-2 inhibitors: A comprehensive review

BACKGROUND AND AIMS

Scar tissue accumulation in organs is the underlying cause of many fibrotic diseases. Due to the extensive array of organs affected, the long-term nature of fibrotic processes and the large number of people who suffer from the negative impact of these diseases, they constitute a serious health problem for modern medicine and a huge economic burden on society. Sodium-glucose cotransporter-2 inhibitors (SGLT2is) are a relatively new class of anti-diabetic pharmaceuticals that offer additional benefits over and above their glucose-lowering properties; these medications modulate a variety of diseases, including fibrosis. Herein, we have collated and analyzed all available research on SGLT2is and their effects on organ fibrosis, together with providing a proposed explanation as to the underlying mechanisms.

METHODS

PubMed, ScienceDirect, Google Scholar and Scopus were searched spanning the period from 2012 until April 2023 to find relevant articles describing the antifibrotic effects of SGLT2is.

RESULTS

The majority of reports have shown that SGLT2is are protective against lung, liver, heart and kidney fibrosis as well as arterial stiffness. According to the results of clinical trials and animal studies, many SGLT2 inhibitors are promising candidates for the treatment of fibrosis. Recent studies have demonstrated that SGLT2is affect an array of cellular processes, including hypoxia, inflammation, oxidative stress, the renin-angiotensin system and metabolic activities, all of which have been linked to fibrosis.

CONCLUSION

Extensive evidence indicates that SGLT2is are promising treatments for fibrosis, demonstrating protective effects in various organs and influencing key cellular processes linked to fibrosis.

The impact of sodium-glucose Cotransporter-2 inhibitors on lipid profile: A meta-analysis of 28 randomized controlled trials

AIM

The present study aimed to evaluate the impact of sodium-glucose cotransporter-2 inhibitors (SGLT2is) on blood lipid profile.

METHODS

We searched the PubMed, Cochrane Library, Medline, and EMBASE databases from the inception to July 2023 for randomized controlled trials (RCTs) comparing SGLT2i with placebo regarding lipid profile changes. The "Meta" package of R software was applied for data synthesis.

RESULTS

A total of 28 RCTs were included and 5192 patients participated in the present study, including 2686 patients who received SGLT2is intervention and 2506 patients who were in the control group. SGLT2is significantly increased blood low density lipoprotein cholesterol (LDL-C) levels [mean difference (MD): 0.09 mmol/L, 95% confidence interval (CI) (0.03, 0.16), 95% prediction interval (PI) (-0.06, 0.24), P = 0.0046] and high density lipoprotein cholesterol (HDL-C) levels [MD: 0.08 mmol/L, 95% CI (0.06, 0.11), 95% PI (-0.00, 0.17), P < 0.0001]. However, we observed neutral effect of SGLT2is on total cholesterol (TC) [MD: 0.08 mmol/L, 95% CI (-0.08, 0.24), 95% PI (-0.24, 0.40), P = 0.3150] and triglyceride (TG) [MD: -0.03 mmol/L, 95% CI (-0.23, 0.16), 95% PI (-0.70, 0.63), P = 0.7382].

CONCLUSION

Our study determined that SGLT2is increase both LDL-C and HDL-C levels, but exerts not significant effect on TC and TG levels.

SGLT2 inhibition, circulating metabolites, and atrial fibrillation: a Mendelian randomization study

BACKGROUND

Sodium-glucose cotransporter 2 (SGLT2) inhibitors have shown promise in reducing the risk of atrial fibrillation (AF). However, the results are controversial and the underlying metabolic mechanism remains unclear. Emerging evidence implied that SGLT2 inhibitors have extra beneficial metabolic effects on circulating metabolites beyond glucose control, which might play a role in reducing the risk of AF. Hence, our study aimed to investigate the effect of circulating metabolites mediating SGLT2 inhibition in AF by Mendelian randomization (MR).

METHODS

A two-sample and two-step MR study was conducted to evaluate the association of SGLT2 inhibition with AF and the mediation effects of circulating metabolites linking SGLT2 inhibition with AF. Genetic instruments for SGLT2 inhibition were identified as genetic variants, which were both associated with the expression of SLC5A2 gene and glycated hemoglobin level (HbA1c). Positive control analysis on type 2 diabetes mellitus (T2DM) was conducted to validate the selection of genetic instruments.

RESULTS

Genetically predicted SGLT2 inhibition (per 1 SD decrement in HbA1c) was associated with reduced risk of T2DM (odds ratio [OR] = 0.63 [95% CI 0.45, 0.88], P = 0.006) and AF (0.51 [0.27, 0.97], P = 0.039). Among 168 circulating metabolites, two metabolites were both associated with SGLT2 inhibition and AF. The effect of SGLT2 inhibition on AF through the total concentration of lipoprotein particles (0.88 [0.81, 0.96], P = 0.004) and the concentration of HDL particles (0.89 [0.82, 0.97], P = 0.005), with a mediated proportion of 8.03% (95% CI [1.20%, 14.34%], P = 0.010) and 7.59% ([1.09%, 13.34%], P = 0.011) of the total effect, respectively.

CONCLUSIONS

This study supported the association of SGLT2 inhibition with a reduced risk of AF. The total concentration of lipoprotein particles and particularly the concentration of HDL particles might mediate this association. Further mechanistic and clinical studies research are needed to understand the mediation effects of circulating metabolites especially blood lipids in the association between SGLT2 inhibition and AF.

Nanoparticles with SGLT2 inhibitory activity: Possible benefits and future

AIM

Nano-drug delivery is a rapidly growing approach in medicine that helps design and develop newer forms of drugs with more efficacy and lower adverse effects. Sodium-glucose cotransporter-2 inhibitors are an emerging class of antidiabetic agents that reduce the blood glucose levels by damping glucose reabsorption in renal proximal tubules.

METHODS AND RESULTS

This mechanism might be followed by some adverse effects that could be prevented by nano-drug delivery. Although we have still limited evidence about nanoforms of sodium-glucose cotransporter-2 inhibitors, current knowledge strongly suggests that nanotechnology can help us design more effective drugs with lower side effects. In recent years, several studies have explored the possible benefits of nanoforms of sodium-glucose cotransporter-2 inhibitors. However, clinical trials are yet to be conducted.

CONCLUSION

In the current review, we present the latest findings on the development and benefits of nanoforms of sodium-glucose cotransporter-2 inhibitors.

Novel Antidiabetic Agents and Their Effects on Lipid Profile: A Single Shot for Several Cardiovascular Targets

Type-2 diabetes mellitus (DM) represents one of the most important risk factors for cardiovascular diseases (CVD). Hyperglycemia and glycemic variability are not the only determinant of the increased cardiovascular (CV) risk in diabetic patients, as a frequent metabolic disorder associated with DM is dyslipidemia, characterized by hypertriglyceridemia, decreased high-density lipoprotein (HDL) cholesterol levels and a shift towards small dense low-density lipoprotein (LDL) cholesterol. This pathological alteration, also called diabetic dyslipidemia, represents a relevant factor which could promotes atherosclerosis and subsequently an increased CV morbidity and mortality. Recently, the introduction of novel antidiabetic agents, such as sodium glucose transporter-2 inhibitors (SGLT2i), dipeptidyl peptidase-4 inhibitors (DPP4i) and glucagon-like peptide-1 (GLP-1) receptor agonists (GLP-1 RAs), has been associated with a significant improvement in CV outcomes. Beyond their known action on glycemia, their positive effects on the CV system also seems to be related to an ameliorated lipidic profile. In this context, this narrative review summarizes the current knowledge regarding these novel anti-diabetic drugs and their effects on diabetic dyslipidemia, which could explain the provided global benefit to the cardiovascular system.

The role of atherogenic lipoproteins in diabetes: Molecular aspects and clinical significance

Dyslipidaemia plays a prominent role in the genesis of atherosclerotic plaque and the increased cardiovascular risk in diabetes. Macrophages readily take up atherogenic lipoproteins, transforming into foam cells and amplifying vascular damage in the presence of endothelial dysfunction. We discuss the importance of distinct lipoprotein subclasses in atherogenic diabetic dyslipidaemia as well as the effects of novel anti-diabetic agents on lipoprotein fractions and ultimately on cardiovascular risk prevention. In patients with diabetes, lipid abnormalities should be aggressively identified and treated in conjunction with therapeutical agents used to prevent cardiovascular disease. The use of drugs that improve diabetic dyslipidaemia plays a prominent role in conferring cardiovascular benefit in individuals with diabetes.

Hepatic benefits of sodium-glucose cotransporter 2 inhibitors in liver disorders

Diabetic patients are at higher risk of liver dysfunction compared with the normal population. Thus, using hypoglycemic agents to improve liver efficiency is important in these patients. Sodium-glucose cotransporters-2 inhibitors (SGLT2i) are newly developed antidiabetic drugs with potent glucose-lowering effects. However, recent limited evidence suggests that they have extra-glycemic benefits and may be able to exert protective effects on the liver. Hence, these drugs could serve as promising pharmacological agents with multiple benefits against different hepatic disorders. In this review, the current knowledge about the possible effects of SGLT2 inhibitors on different forms of liver complications and possible underlying mechanisms are discussed.

Empagliflozin ameliorates atherosclerosis via regulating the intestinal flora

BACKGROUND AND AIMS

Sodium-glucose cotransporter 2 inhibitor (SGLT2i) has been reported to attenuate atherosclerosis. Further, it has been suggested that intestinal flora influences atherosclerosis progression. Herein we aimed to investigate whether SGLT2i can alleviate atherosclerosis through intestinal flora.

METHODS

Six-week-old male ApoE^-/- mice fed a high-fat diet were gavaged either empagliflozin (SGLT2i group, n = 9) or saline (Ctrl group, n = 6) for 12 weeks. Feces were collected from both groups at the end of the experiment for fecal microbiota transplantation (FMT). Another 12 six-week-old male ApoE^-/- mice were fed a high-fat diet and received FMT with feces either from SGLT2i (FMT-SGLT2i group, n = 6) or from Ctrl (FMT-Ctrl group, n = 6) groups. Blood, tissue, and fecal samples were collected for subsequent analyses.

RESULTS

In comparison with Ctrl group, atherosclerosis was less severe in the SGLT2i group (p < 0.0001), and the richness of probiotic, such as f_Coriobacteriaceae, f_S24-7, f_Lachnospiraceae, and f_Adlercreutzia, was higher in feces. Besides, empagliflozin resulted in a significant reduction in the inflammatory response and altered intestinal flora metabolism. Interestingly, compared with FMT-Ctrl, FMT-SGLT2i also showed a reduction in atherosclerosis and systemic inflammatory response, as well as changes in the component of intestinal flora and pertinent metabolites similar to SGLT2i group.

CONCLUSIONS

Empagliflozin seems to mitigate atherosclerosis partly by regulating intestinal microbiota, and this anti-atherosclerotic effect can be transferred through intestinal flora transplantation.

Neutral effect of SGLT2 inhibitors on lipoprotein metabolism: From clinical evidence to molecular mechanisms

Sodium-glucose cotransporter-2 inhibitors (SGLT2i) are effective, well-tolerated, and safe glucose-lowering compounds for patients with type 2 diabetes mellitus (T2DM). SGLT2i benefit encompasses protection from heart and kidney failure, independently of the presence of diabetes. In addition, SGLT2i consistently reduce the risk of hospitalization for heart failure and, although with some heterogeneity between specific members of the class, favourably affect the risk of cardiovascular outcomes. The molecular mechanisms underlying the cardiovascular favourable effect are not fully clarified. Studies testing the efficacy of SGLT2i in human cohorts and experimental models of atherosclerotic cardiovascular disease (ASCVD) have reported significant differences in circulating levels and composition of lipoprotein classes. In randomized clinical trials, small but significant increases in low-density lipoprotein cholesterol (LDL-C) levels have been observed, with a still undefined clinical significance; on the other hand, favourable (although modest) effects on high-density lipoprotein cholesterol (HDL-C) and triglycerides have been reported. At the molecular level, glycosuria may promote a starving-like state that ultimately leads to a metabolic improvement through the mobilization of fatty acids from the adipose tissue and their oxidation for the production of ketone bodies. This, however, may also fuel hepatic cholesterol synthesis, thus inhibiting atherogenic lipoprotein uptake from the liver. Long-term studies collecting detailed information on lipid-lowering therapies at baseline and during the trials with SGLT2i, as well as regularly monitoring lipid profiles are warranted to disentangle the potential implications of SGLT2i in modulating lipoprotein-mediated atherosclerotic cardiovascular risk.

Sodium-glucose cotransporter 2 inhibitors and mitochondrial functions: state of the art

Sodium-glucose cotransporter 2 inhibitors (SGLT2is) are a class of newly introduced antidiabetic drugs with potent hypoglycemic effects. Recent evidence suggests that these drugs have extraglycemic impacts and are therefore able to provide additional benefits beyond glucose lowering. Mitochondrial dysfunction is a central facet of many disorders that negatively impacts many tissues and organs, especially in the setting of diabetes. Therefore, it would be hugely beneficial if an antidiabetic drug could also provide mitochondrial benefits to improve cellular function and reduce the risk of diabetic complications. In this review, we have surveyed the literature for possible mitochondrial benefits of SGLT2is and we discuss the possible mechanisms involved.