SGLT2 Inhibitors and the Diabetic Kidney

Diabetic nephropathy (DN) is the most common cause of end-stage renal disease worldwide. Blood glucose and blood pressure control reduce the risk of developing this complication; however, once DN is established, it is only possible to slow progression. Sodium-glucose cotransporter 2 (SGLT2) inhibitors, the most recent glucose-lowering oral agents, may have the potential to exert nephroprotection not only through improving glycemic control but also through glucose-independent effects, such as blood pressure-lowering and direct renal effects. It is important to consider, however, that in patients with impaired renal function, given their mode of action, SGLT2 inhibitors are less effective in lowering blood glucose. In patients with high cardiovascular risk, the SGLT2 inhibitor empagliflozin lowered the rate of cardiovascular events, especially cardiovascular death, and substantially reduced important renal outcomes. Such benefits on DN could derive from effects beyond glycemia. Glomerular hyperfiltration is a potential risk factor for DN. In addition to the activation of the renin-angiotensin-aldosterone system, renal tubular factors, including SGLT2, contribute to glomerular hyperfiltration in diabetes. SGLT2 inhibitors reduce sodium reabsorption in the proximal tubule, causing, through tubuloglomerular feedback, afferent arteriole vasoconstriction and reduction in hyperfiltration. Experimental studies showed that SGLT2 inhibitors reduced hyperfiltration and decreased inflammatory and fibrotic responses of proximal tubular cells. SGLT2 inhibitors reduced glomerular hyperfiltration in patients with type 1 diabetes, and in patients with type 2 diabetes, they caused transient acute reductions in glomerular filtration rate, followed by a progressive recovery and stabilization of renal function. Interestingly, recent studies consistently demonstrated a reduction in albuminuria. Although these data are promising, only dedicated renal outcome trials will clarify whether SGLT2 inhibitors, in addition to their glycemic and blood pressure benefits, may provide nephroprotective effects

Insulin-dependent diabetic sibling pairs are concordant for sodium-hydrogen antiport activity11See Editorial by Giancarlo Viberti, p. 2526.

Insulin-dependent diabetic sibling pairs are concordant for sodium-hydrogen antiport activity.BackgroundRecent findings of enhanced Na+/H+ antiport activity in cultured fibroblasts and immortalized lymphoblasts from type 1 diabetic patients with nephropathy support the view that a phenotypic or genotypic factor(s) underlies nephropathy risk. This study evaluated the kinetic properties of Na+/H+ antiporter in cultured fibroblasts from families with two siblings affected by type 1 (insulin-dependent) diabetes.MethodsSeventeen diabetic sibling pairs were studied. The age was 38 ± 10years (mean ± sd) in probands, the first to develop diabetes, and 39 ± 7 in siblings; the duration of diabetes was, by definition, longer in probands (24 ± 12 vs. 17 ± 8years in siblings). Na+/H+ antiport activity was determined using a microfluorometric technique with the pH sensitive dye 2′,7′-bis(2-carboxyethyl)-5(6)-carboxyfluorescein in skin fibroblasts cultured for at least six passages.ResultsThere were no significant differences between probands and siblings for the following parameters: glycated hemoglobin, 8.3 ± 0.8% in probands and 8.6 ± 1.4% in siblings; creatinine clearance, 103 ± 24 ml/min/1.73m2 in probands and 103 ± 25 in siblings; albumin excretion rate, 6.8 (1 to 860) μg/min (median and range) in probands and 4.9 (2 to 1334) in siblings. Intracellular pH and buffering capacity were superimposable in the sibling pairs. The Vmax for the antiport was 39.2 ± 14.7mmol/liter cell/min in probands and 40.3 ± 17.6 in siblings. The internal pH for half-maximal activation (Km) and Hill coefficient was also similar in probands and siblings. There were correlations between probands and siblings in values for intracellular pH (r = 0.51, P < 0.04), Vmax (r = 0.84, P < 0.0001), and buffering capacity (r = 0.53, P < 0.03). Glycated hemoglobin values over five years were not significantly correlated in the sibling pairs (r = 0.3, P > 0.1). Vmax was related with the albumin excretion rate (r = +0.49, P = 0.005) and glycated hemoglobin (r = +0.41, P = 0.017) in the total cohort of sibling pairs. However, multiple regression analysis, using Vmax as the dependent variable, found no correlations between any of the subjects’ clinical and demographic variables.ConclusionsFamilial concordance for Na+/H+ antiport activity in long-term cultured skin fibroblasts from type 1 diabetic siblings suggests that at least some of the in vitro phenotypical characteristics of these cells are likely to be genetically determined and to be, at least in part, independent of in vivo metabolic control

Role of incretin based therapies in the treatment of diabetic kidney disease

Diabetic kidney disease (DKD), a serious microvascular complication of diabetes mellitus is a leading cause of end-stage renal disease and is associated with an increased risk of cardiovascular morbidity and mortality. Despite advancements in blood glucose and blood pressure (BP) control, ~20% to 40% of patients with diabetes mellitus develop DKD. Intensive glycaemic and BP control positively influence decline in estimated glomerular filtration rate and albuminuria, thereby delaying the onset and progression of diabetic nephropathy. Incretin based therapies namely glucagon-like peptide-1 receptor agonists (GLP-1 RAs) and dipeptidyl peptidase-4 (DPP-4) inhibitors are widely used glucose lowering agents and have shown favorable renal outcomes in DKD. This article discusses the extra-glycaemic properties of incretin based therapies and their renoprotective effects on components of the metabolic syndrome, including obesity, hypertension and dyslipidaemia; reduction in oxidative stress and inflammation; and increase in natriuresis

Hyperspectral analysis applied to micro-Brillouin maps of amyloid-beta plaques in Alzheimer’s disease brains

A recent investigation on the architecture and chemical composition of amyloid-β (Aβ) plaques in ex vivo histological sections of an Aβ-overexpressing transgenic mouse hippocampus has shed light on the infrared light signature of cell-activation related biomarkers of Alzheimer’s disease. A correlation was highlighted between the biomechanical properties detected by Brillouin microscopy and the molecular make-up of Aβ plaques provided by FTIR spectroscopic imaging and Raman microscopy (with correlative immunofluorescence imaging) in this animal model of the disease. In the Brillouin spectra of heterogeneous materials such as biomedical samples, peaks are likely the result of multiple contributions, more or less overlaid on a spatial and spectral scale. The ability to disentangle these contributions is very important as it may give access to discrete components that would otherwise be buried within the Brillouin peak envelope. Here, we applied an unsupervised non-negative matrix factorization method to analyse the spontaneous Brillouin microscopy maps of Aβ plaques in transgenic mouse hippocampal sections. The method has already been proven successful in decomposing chemical images and is applied here for the first time to acoustic maps acquired with a Fabry–Perot Brillouin microscope. We extracted and visualised a decrease in tissue rigidity from the core through to the periphery of the plaque, with spatially distinct components that we assigned to specific entities. This work demonstrates that it is possible to reveal the structure and mechanical properties of Aβ plaques, with details visualized by the projection of the mechanical contrast into a few relevant channels

Impact of Age and Estimated Glomerular Filtration Rate on the Glycemic Efficacy and Safety of Canagliflozin: A Pooled Analysis of Clinical Studies.

AbstractObjectiveReduced efficacy has been reported in the elderly; it may be a consequence of an age-dependent decline in estimated glomerular filtration rate (eGFR) rather than ageing per se. We sought to determine the impact of these 2 parameters, as well as sex and baseline body mass index (BMI), on the efficacy and safety of canagliflozin, a sodium glucose co-transporter 2 inhibitor, in people with type 2 diabetes.MethodsData were pooled from 6 randomized, double-blind, placebo-controlled studies (18 or 26 weeks; N=4053). Changes in glycated hemoglobin (A1C) and systolic blood pressure (BP) from baseline with canagliflozin 100 mg and 300 mg and placebo were evaluated in subgroups by sex, baseline BMI, baseline age and baseline eGFR. Safety was assessed by reports of adverse events.ResultsPlacebo-subtracted reductions in A1C with canagliflozin 100 mg and 300 mg were similar in men and women. A1C reductions with canagliflozin were seen across BMI subgroups and in participants aged <65 years and ≥65 years. Significantly greater placebo-subtracted reductions in A1C were seen with both canagliflozin doses in participants with higher baseline eGFR (≥90 mL/min/1.73 m2). Reductions in systolic BP were seen with canagliflozin across subgroups of sex, BMI, age and eGFR. A1C reductions with canagliflozin were similar for participants aged <65 or ≥65 years who had baseline eGFR ≥60 mL/min/1.73 m2 and were smaller in older than in younger participants with baseline eGFR 45 to <60 mL/min/1.73 m2. The overall incidence of adverse events was similar across treatment groups regardless of sex, baseline BMI, baseline age or baseline eGFR.ConclusionsCanagliflozin improved glycemic control, reduced BP and was generally well tolerated in people with type 2 diabetes across a range of ages, BMIs and renal functions

Resistant Hypertension, Time-Updated Blood Pressure Values and Renal Outcome in Type 2 Diabetes Mellitus

BACKGROUND: Apparent treatment resistant hypertension (aTRH) is highly prevalent in patients with type 2 diabetes mellitus (T2D) and entails worse cardiovascular prognosis. The impact of aTRH and long-term achievement of recommended blood pressure (BP) values on renal outcome remains largely unknown. We assessed the role of aTRH and BP on the development of chronic kidney disease in patients with T2D and hypertension in real-life clinical practice.METHODS AND RESULTS: Clinical records from a total of 29&nbsp;923 patients with T2D and hypertension, with normal baseline estimated glomerular filtration rate and regular visits during a 4-year follow-up, were retrieved and analyzed. The association between time-updated BP control (ie, 75% of visits with BP &lt;140/90&nbsp;mm&nbsp;Hg) and the occurrence of estimated glomerular filtration rate &lt;60 and/or a reduction 6530% from baseline was assessed. At baseline, 17% of patients had aTRH. Over the 4-year follow-up, 19% developed low estimated glomerular filtration rate and 12% an estimated glomerular filtration rate reduction 6530% from baseline. Patients with aTRH showed an increased risk of developing both renal outcomes (adjusted odds ratio, 1.31 and 1.43; P&lt;0.001 respectively), as compared with those with non-aTRH. No association was found between BP control and renal outcomes in non-aTRH, whereas in aTRH, BP control was associated with a 30% (P=0.036) greater risk of developing the renal end points.CONCLUSIONS: ATRH entails a worse renal prognosis in T2D with hypertension. BP control is not associated with a more-favorable renal outcome in aTRH. The relationship between time-updated BP and renal function seems to be J-shaped, with optimal systolic BP values between 120 and 140&nbsp;mm&nbsp;Hg

Apparent Treatment Resistant Hypertension, Blood Pressure Control and the Progression of Chronic Kidney Disease in Patients with Type 2 Diabetes

Background/Aims: Apparent treatment resistant hypertension (aTRH) is highly prevalent in patients with type 2 diabetes (T2D) and chronic kidney disease (CKD). The impact of aTRH and achievement of recommended blood pressure (BP) values on the rate of glomerular filtration rate (eGFR) loss in CKD patients is poorly known. To assess the role of aTRH and time-updated BP control (BPC) on the progression of CKD in patients with T2D and hypertension (HT) in real life clinical practice. Methods: Clinical records from a total of 2,778 diabetic patients with HT and stage 3 CKD (i.e. baseline eGFR values between 30 and 60 ml/min) and regular visits during a four-year follow-up were analyzed. The association between BPC (i.e. 75% of visits with BP &lt;140/90 mmHg) and eGFR loss (i.e. a &gt;30% reduction from baseline) or worsening of albuminuria status over time was assessed. Results: At baseline 33% of patients had aTRH. Over the 4-year follow-up, 20% had a &gt;30% eGFR reduction. Patients with aTRH had an increased risk of eGFR loss &gt;30% (OR 1.31; P&lt;0.007). In patients with aTRH, BPC was associated with a 79% (P=0.029) greater risk of eGFR reduction despite a 58% (P=0.001) lower risk of albuminuria status worsening. In non-aTRH, no association was found between BPC and renal outcome. Conclusion: In patients with stage 3 CKD the presence of aTRH entails a faster loss of eGFR. More effective prevention of aTRH should be implemented as this condition is associated with a burden of risk not modifiable by tight BP reduction

Vascular endothelial growth factor (VEGF) and VEGF receptors in diabetic nephropathy: expression studies in biopsies of type 2 diabetic patients.

Vascular endothelial growth factor (VEGF) is involved in the pathogenesis of diabetic retinopathy but its role in diabetic nephropathy is only speculative so far. It has been shown that in renal cortex of normal kidneys, glomerular and tubular epithelial cells express VEGF and that VEGF 165 is the predominant isoform. Two VEGF receptors, KDR (kinase domain region) and Flt-1 (fms-like tyrosine kinase) are co-expressed by glomerular and peritubular capillary endothelial cells. However, VEGF and VEGF receptors are predominantly expressed at glomerular level. We recently demonstrated that in type 2 diabetic patients glomerular qualitative and quantitative changes of VEGF mRNA expression are associated with functional and structural renal changes. In the present work we focused on the tubulo-interstitial compartment; by reverse transcription/polymerase chain reaction (RT/PCR) we evaluated the expression of VEGF, KDR, Flt-1 and the relationship between the two main type of VEGF isoforms, VEGF121 and VEGF165 in the tubulo-interstitium of type 2 diabetic patients. Patients were divided in three category on the basis of renal structure pattern: CI, with normal or near normal renal structure; CII, with glomerular and tubulo-interstitial lesions occurring in parallel (typical diabetic nephropathology); CIII, with atypical pattern of renal injury, i.e., more severe tubulo-interstitial and vascular than glomerular changes. Comparison between the two cortical compartments revealed that, both in glomeruli and in tubulo-interstitium. VEGF121 isoform exceed VEGF165 while Flt-1 was significantly lower in glomeruli. CIII patients had the lowest tubulo-interstitial level of VEGF and Flt-1 mRNAs. These results suggest that the transcriptional shifting from VEGF165 to VEGF121 isoform and the unbalanced FIt-1 expression between tubulo-interstitium and glomeruli could be involved in the pathogenesis of diabetic nephropathy. Furthermore, at least in CIII patients, down-regulation of the VEGF-Flt-1 system could be involved in the mechanisms leading to tubulointerstitial diabetic lesions

Sodium-glucose co-transporter-2 inhibitors in patients with type 2 diabetes : Barriers and solutions for improving uptake in routine clinical practice

Recent advances in type 2 diabetes (T2D) research have highlighted the benefits of sodium-glucose co-transporter-2 (SGLT-2) inhibitors, including cardiovascular and renal protection. However, uptake rates of these drugs remain low in patients with T2D, particularly in subpopulations most likely to benefit from them. This review considers the potential barriers to prescribing SGLT-2 inhibitors in T2D in clinical practice and outlines potential multidisciplinary recommendations to overcome these barriers. Safety concerns and a lack of clarity in and divergence of guidelines around the introduction of SGLT-2 inhibitors into treatment regimens may represent a barrier to uptake from the clinicians' perspective, including a general lack of understanding of the benefits associated with SGLT-2 inhibitors. Patient characteristics, such as socioeconomic status, may influence uptake because of the cost of SGLT-2 inhibitors, especially in the United States, where health insurance coverage could be a concern. SGLT-2 inhibitor prescription rates vary between clinical specialty (endocrinology, primary care, cardiology, and nephrology) and country, with cardiologists the lowest prescribers, and endocrinologists the highest. Primary care practitioners may experience more challenges in following SGLT-2 inhibitor-related guidelines than diabetes specialists as there may be fewer opportunities for education on how this drug class improves cardiovascular and renal outcomes in patients with T2D. Uptake rates appear to vary between countries because of differences in guidelines and health insurance systems. The amendment of SGLT-2 inhibitor-related guidelines for more multidisciplinary use and the implementation of patient and clinician education may encourage uptake of these drugs, potentially improving long-term health outcomes among patients with T2D