SGLT-2 inhibitors: Their pleiotropic properties

SGLT-2 Inhibitors and the Inflammasome: What's Next in the 21st Century?

The nucleotide-binding domain-like receptor protein 3 (NLRP3) inflammasome in the kidney and the heart is increasingly being suggested to play a key role in mediating inflammation. In the kidney, NLRP3 activation was associated with the progression of diabetic kidney disease. In the heart, activation of the NLRP3 inflammasome was related to the enhanced release of interleukin-1β (IL-1β) and the subsequent induction of atherosclerosis and heart failure. Apart from their glucose-lowering effects, SGLT-2 inhibitors were documented to attenuate activation of the NLRP3, thus resulting in the constellation of an anti-inflammatory milieu. In this review, we focus on the interplay between SGLT-2 inhibitors and the inflammasome in the kidney, the heart and the neurons in the context of diabetes mellitus and its complications.

Amelioration of Murine Diabetic Nephropathy with a SGLT2 Inhibitor Is Associated with Suppressing Abnormal Expression of Hypoxia-Inducible Factors

Diabetic nephropathy (DN), once manifested, is unlikely to completely recover. Factors that influence DN progression were explored by investigating the process of glomerulosclerosis and interstitial fibrosis and chronological changes in glucose, albuminuria, hyperfiltration, and expressions of sodium-glucose cotransporter 2 (SGLT2) and hypoxia-inducible factors (HIFs) up to 50 weeks in inducible cAMP early repressor transgenic mice, a model of severe DN. Long-term intervention with the SGLT2 inhibitor canagliflozin or islet transplantation or heminephrectomy was used. Inducible cAMP early repressor transgenic mice exhibited progressive diabetic glomerulosclerosis and mild interstitial fibrosis, and expressed extensive HIF-1α and HIF-2α in glomerulus and tubules, with sustained hyperfiltration up to 50 weeks. Canagliflozin ameliorated glomerulosclerosis/interstitial fibrosis gradually and reduced HIF overexpression. Islet-transplanted mice exhibited no amelioration. None of the heminephrectomized diabetic mice survived the hyperfiltration overload, but all of the canagliflozin-treated mice survived with re-expressions of HIF-1α and HIF-2α. These results suggest that persistent glomerular hyperfiltration might initiate glomerular injury, and persistent overexpression of HIFs could promote the development of glomerulosclerosis and interstitial fibrosis. Canagliflozin attenuated both changes. Oxidative stress or hypoxia was undetectable in this model. The abnormal expression of HIF-1α and HIF-2α may be a potential therapeutic target for preventing glomerulosclerosis and interstitial fibrosis.

Sodium-Glucose Cotransporter-2 Inhibitors in Vascular Biology: Cellular and Molecular Mechanisms

Sodium-glucose cotransporter-2 (SGLT2) inhibitors are new antidiabetic drugs that reduce hyperglycemia by inhibiting the glucose reabsorption in renal proximal tubules. Clinical studies have shown that SGLT2 inhibitors not only improve glycemic control but also reduce major adverse cardiovascular events (MACE, cardiovascular and total mortality, fatal or nonfatal myocardial infarction or stroke) and hospitalization for heart failure (HF), and improve outcome in chronic kidney disease. These cardiovascular and renal benefits have now been confirmed in both diabetes and non-diabetes patients. The precise mechanism(s) responsible for the protective effects are under intensive investigation. This review examines current evidence on the cardiovascular benefits of SGLT2 inhibitors, with a special emphasis on the vascular actions and their potential mechanisms.

Effects of SGLT2 inhibitor and dietary NaCl on glomerular hemodynamics assessed by micropuncture in diabetic rats

Inhibitors of the main proximal tubular Na-glucose cotransporter (SGLT2) mitigate diabetic glomerular hyperfiltration and have been approved by the United States Food and Drug Administration for slowing the progression of diabetic kidney disease. It has been proposed that SGLT2 inhibitors improve hard renal outcomes by reducing glomerular capillary pressure (PGC) via a tubuloglomerular feedback (TGF) response to a decrease in proximal reabsorption (Jprox). However, the effect of SGLT2 inhibition on PGC has not been measured. Here, we studied the effects of acute SGLT2 blockade (ertugliflozin) on Jprox and glomerular hemodynamics in two-period micropuncture experiments using streptozotocin-induced diabetic rats fed high- or low-NaCl diets. PGC was measured by direct capillary puncture or computed from tubular stop-flow pressure (PSF). TGF is intact while measuring PGC directly but rendered inoperative when measuring PSF. Acute SGLT2 inhibitor reduced Jprox by ∼30%, reduced PGC by 5-8 mmHg, and reduced glomerular filtration rate (GFR) by ∼25% (all P < 0.0001) but had no effect on PSF. The decrease in PGC was larger with the low-NaCl diet (8 vs. 5 mmHg, P = 0.04) where PGC was higher to begin with (54 vs. 50 mmHg, P = 0.003). Greater decreases in PGC corresponded, unexpectedly, to lesser decreases in GFR (P = 0.04). In conclusion, these results confirm expectations that PGC would decline in response to acute SGLT2 inhibition and that a functioning TGF system is required for this. We infer a contribution of postglomerular vasorelaxation to the TGF responses where decreases in PGC were large and decreases in GFR were small.NEW & NOTEWORTHY It has been theorized that Na-glucose cotransporter (SGLT2) blockade slows progression of diabetic kidney disease by reducing physical strain on the glomerulus. This is the first direct measurement of intraglomerular pressure during SGLT2 blockade. Findings confirmed that SGLT2 blockade does reduce glomerular capillary pressure, that this is mediated through tubuloglomerular feedback, and that the tubuloglomerular feedback response to SGLT2 blockade involves preglomerular vasoconstriction and postglomerular vasorelaxation.

Insulin Therapy Is Associated With an Increased Risk of Carotid Plaque in Type 2 Diabetes: A Real-World Study

Background: Controversies concerning the association between insulin therapy and atherosclerotic lesions in type 2 diabetes mellitus (T2DM) remain to exist. The purpose of this study was to investigate whether insulin therapy in T2DM patients is linked with the increased risk of carotid atherosclerosis in real-world settings. Methods: We retrospectively enrolled 2,356 hospitalized patients with T2DM, including 1,716 subjects receiving insulin therapy and 640 subjects without receiving insulin therapy. Carotid atherosclerotic lesions including carotid intima-media thickness (CIMT), carotid plaque and carotid stenosis were assessed by Doppler ultrasonography and were compared between T2DM patients treated with and without insulin. Results: After adjusting for age and duration of diabetes, there was a significant increase in the prevalence of carotid plaque in both men (52.0 vs. 41.7%, p = 0.007) and women (49.6 vs. 39.7%, p = 0.003) receiving insulin therapy than in those without receiving insulin therapy. After further controlling for other confounding factors, compared with the patients without receiving insulin therapy, the risk of carotid plaque was still significantly increased not only in women treated with insulin (OR: 1.810; 95% CI: 1.155-2.837, p = 0.010), but also in men treated with insulin (OR: 1.867; 95% CI: 1.307-2.666; p = 0.001). Additionally, HOMA2-B% was higher in both women and men without receiving insulin therapy compared with those receiving insulin therapy (p < 0.001 in both men and women), but HOMA-IR was significantly higher in patients treated with insulin than in those without receiving insulin therapy (p < 0.001 in both men and women). Conclusions: Insulin therapy is associated with markedly increased risk of carotid atherosclerotic lesions in type 2 diabetes, which partly attribute to the more serious insulin resistance in T2DM patients receiving insulin therapy.

Dapagliflozin in a Real-World Chronic Heart Failure Population: How Many Are Actually Eligible?

BACKGROUND

In patients with heart failure (HF) and reduced ejection fraction (HFrEF) with or without type 2 diabetes mellitus, the sodium-glucose cotransporter 2 inhibitor (SGLT2i) dapagliflozin was recently shown to reduce the risk of worsening HF or death from cardiovascular causes in the dapagliflozin in patients with heart failure and reduced ejection fraction (DAPA-HF) trial. Our goal was to investigate how many patients in a real-world setting would be eligible for dapagliflozin according to the DAPA-HF enrolment criteria.

METHODS

This is a single-center retrospective study enrolling consecutive, unselected patients followed up in an HF clinic from 2013 to 2019. Key DAPA-HF inclusion criteria (i.e., left ventricular ejection fraction [LVEF] ≤40% and NT-proBNP ≥600 pg/mL [or ≥900 pg/mL if atrial fibrillation]) and exclusion criteria (estimated glomerular filtration rate [eGFR] <30 mL/kg/1.73 m2 and systolic blood pressure [SBP] <95 mm Hg) were considered.

RESULTS

Overall, 479 patients (age 76 ± 13 years; 50.5% male; 78.9% hypertensive; 45.1% with an eGFR <60 mL/min/1.73 m2; 36.5% with TD2M; and 33.5% with ischaemic HF) were assessed. The median SBP was 128.5 (112.0-146.0) mm Hg, mean eGFR was 50.8 ± 23.7 mL/min/1.73 m2, and median NT-proBNP was 2,183 (IQR 1,010-5,310) pg/mL. Overall, 155 (32.4%) patients had LVEF ≤40%. According to the DAPA-HF trial key criteria, 90 patients (18.8%) would be eligible for dapagliflozin. The remainder would be excluded due to LVEF >40% (67.6%), eGFR <30 mL/min/1.73 m2 (19.4%), NT-proBNP below the cutoff (16.7%), and/or SBP <95 mm Hg (6.5%). If we center the analysis to those with LVEF ≤40%, 58.1% would be eligible for dapagliflozin. The remainder would be excluded due to an eGFR <30 mL/min/1.73 m2 (20%), NT-proBNP below the cutoff (16.1%), and/or SBP <95 mm Hg (8.4%).

CONCLUSION

Roughly half of our real-world HFrEF cohort would be eligible for dapagliflozin according to the key criteria of the DAPA-HF trial. The main reason for non-eligibility was an eGFR <30 mL/min/1.73 m2. However, two-thirds of patients had LVEF >40%. These findings show that dapagliflozin is a promising complementary new drug in the therapeutic armamentarium of most patients with HFrEF, while highlighting the urgent need for disease-modifying drugs in mid-range and preserved LVEF and the need to assess the efficacy and safety of SLGT2i in advanced kidney disease patients. The results of ongoing SGLT2i trials in these LVEF subgroups are eagerly awaited.

Canagliflozin impedes ischemic hind-limb recovery in the setting of diabetes

There is a reported increased incidence of lower extremity amputations in individuals with diabetes who are treated with canagliflozin (an SGLT2 receptor inhibitor). It is unclear whether this is an unintended consequence of therapy, or whether canagliflozin can affect peripheral limb perfusion in the setting of underling arterial malperfusion. To evaluate this we explored the effect of canagliflozin on tissue recovery following unilateral hind-limb ischemia (HLI). Adult wildtype (+/+) and diabetic (db/db) mice were maintained on 8 weeks of a regular chow diet, or a chow diet containing canagliflozin (200 mg/kg). Following HLI, hind-limb appearance, function, and Doppler perfusion were serially evaluated. Gastrocnemius muscle fiber size and microvessel density were also evaluated 21 days following HLI. We observed that db/db that received a diet containing canagliflozin had significantly worse hind-limb function and appearance scores compared to both db/db mice that received a regular diet and +/+ mice that received a canagliflozin diet. At post-HLI day 21, db/db mice that received a canagliflozin diet also had decreased Doppler perfusion, gastrocnemius muscle fiber size, and microvessel density compared to +/+ mice that received a canagliflozin diet. These findings indicate that canagliflozin appears to impede ischemic peripheral tissue recovery and warrant further clinical investigation in individuals with diabetes and a history of peripheral artery disease.

Pharmacotherapy of obesity: Available medications and drugs under investigation

Obesity is a chronic disease with a continuously rising prevalence that currently affects more than half a billion people worldwide. Energy balance and appetite are highly regulated via central and peripheral mechanisms, and weight loss triggers a homeostatic response leading to weight regain. Lifestyle and behavioral modifications are the cornerstones of obesity management; however, they often fail to achieve or sustain long-term weight loss. Pharmacotherapy added onto lifestyle modifications results in an additional, albeit limited, weight reduction. Regardless, this weight reduction of 5-10% conveys multiple cardiovascular and metabolic benefits. In this review, evidence on the food and drug administration (FDA)-approved medications, i.e., orlistat, lorcaserin, phentermine/topiramate, liraglutide and naltrexone/bupropion, is summarized. Furthermore, anti-obesity agents in the pipeline for potential future therapeutic use are presented.

Efficacy and safety of sodium-glucose cotransporter 2 inhibitor ipragliflozin on glycemic control and cardiovascular parameters in Japanese patients with type 2 diabetes mellitus; Fukuoka Study of Ipragliflozin (FUSION)

Sodium-glucose co-transporter-2 inhibitors are newly established anti-diabetic agents with a unique glucose-lowering mechanism. In the present study, we investigated the efficacy and safety of the sodium-glucose co-transporter-2 inhibitor ipragliflozin (Ipra) for metabolic markers and cardiovascular parameters in Japanese patients with type 2 diabetes mellitus (T2DM). This study was an investigator-initiated, open-label, single-arm, multicenter prospective study. Patients with T2DM were treated with 50 mg Ipra for 24 and 52 weeks. The primary outcome investigated was the reduction of glycated hemoglobin (HbA1c) level. The secondary outcome was the change in other metabolic and cardiovascular parameters by 24 weeks. Before and after 52 weeks of treatment, carotid intima-media thickening (IMT) was measured by echography. A total of 134 patients were recruited in the study. A 24-week treatment with 50 mg Ipra daily significantly reduced HbA1c level (-0.6%, p < 0.01). Body mass index (BMI), blood pressure and serum C-peptide were reduced significantly (p < 0.05), while serum glucagon level was unchanged. Interestingly, the serum adiponectin and high-density lipoprotein (HDL) cholesterol levels were significantly increased by Ipra. However, 52 weeks of Ipra treatment did not change carotid IMT. Multiple regression analysis revealed that the only significant contributing factor for HbA1c reduction by Ipra was baseline HbA1c level. These data suggest that Ipra decreased not only glucose level but also BMI, blood pressure and serum C-peptide, and the contributing factor for HbA1c reduction by Ipra was baseline HbA1c level. Further, Ipra improved serum adiponectin and HDL cholesterol levels.

SGLT2 Protein Expression Is Increased in Human Diabetic Nephropathy: SGLT2 PROTEIN INHIBITION DECREASES RENAL LIPID ACCUMULATION, INFLAMMATION, AND THE DEVELOPMENT OF NEPHROPATHY IN DIABETIC MICE

There is very limited human renal sodium gradient-dependent glucose transporter protein (SGLT2) mRNA and protein expression data reported in the literature. The first aim of this study was to determine SGLT2 mRNA and protein levels in human and animal models of diabetic nephropathy. We have found that the expression of SGLT2 mRNA and protein is increased in renal biopsies from human subjects with diabetic nephropathy. This is in contrast to db-db mice that had no changes in renal SGLT2 protein expression. Furthermore, the effect of SGLT2 inhibition on renal lipid content and inflammation is not known. The second aim of this study was to determine the potential mechanisms of beneficial effects of SGLT2 inhibition in the progression of diabetic renal disease. We treated db/db mice with a selective SGLT2 inhibitor JNJ 39933673. We found that SGLT2 inhibition caused marked decreases in systolic blood pressure, kidney weight/body weight ratio, urinary albumin, and urinary thiobarbituric acid-reacting substances. SGLT2 inhibition prevented renal lipid accumulation via inhibition of carbohydrate-responsive element-binding protein-β, pyruvate kinase L, SCD-1, and DGAT1, key transcriptional factors and enzymes that mediate fatty acid and triglyceride synthesis. SGLT2 inhibition also prevented inflammation via inhibition of CD68 macrophage accumulation and expression of p65, TLR4, MCP-1, and osteopontin. These effects were associated with reduced mesangial expansion, accumulation of the extracellular matrix proteins fibronectin and type IV collagen, and loss of podocyte markers WT1 and synaptopodin, as determined by immunofluorescence microscopy. In summary, our study showed that SGLT2 inhibition modulates renal lipid metabolism and inflammation and prevents the development of nephropathy in db/db mice.