Reno- and cardioprotective molecular mechanisms of SGLT2 inhibitors beyond glycemic control: from bedside to bench

Large placebo-controlled clinical trials have shown that sodium-glucose cotransporter-2 inhibitors (SGLT2i) delay the deterioration of renal function and reduce cardiovascular events in a glucose-independent manner, thereby ultimately reducing mortality in patients with chronic kidney disease (CKD) and/or heart failure. These existing clinical data stimulated preclinical studies aiming to understand the observed clinical effects. In animal models, it was shown that the beneficial effect of SGLT2i on the tubuloglomerular feedback (TGF) improves glomerular pressure and reduces tubular workload by improving renal hemodynamics, which appears to be dependent on salt intake. High salt intake might blunt the SGLT2i effects on the TGF. Beyond the salt-dependent effects of SGLT2i on renal hemodynamics, SGLT2i inhibited several key aspects of macrophage-mediated renal inflammation and fibrosis, including inhibiting the differentiation of monocytes to macrophages, promoting the polarization of macrophages from a proinflammatory M1 phenotype to an anti-inflammatory M2 phenotype, and suppressing the activation of inflammasomes and major proinflammatory factors. As macrophages are also important cells mediating atherosclerosis and myocardial remodeling after injury, the inhibitory effects of SGLT2i on macrophage differentiation and inflammatory responses may also play a role in stabilizing atherosclerotic plaques and ameliorating myocardial inflammation and fibrosis. Recent studies suggest that SGLT2i may also act directly on the Na+/H+ exchanger and Late-INa in cardiomyocytes thus reducing Na+ and Ca2+ overload-mediated myocardial damage. In addition, the renal-cardioprotective mechanisms of SGLT2i include systemic effects on the sympathetic nervous system, blood volume, salt excretion, and energy metabolism.

Dapagliflozin in focal segmental glomerulosclerosis: a combined human-rodent pilot study

Focal segmental glomerulosclerosis (FSGS) is an important cause of nondiabetic chronic kidney disease (CKD). Sodium-glucose cotransporter 2 inhibition (SGLT2i) therapy attenuates the progression of diabetic nephropathy, but it remains unclear whether SGLT2i provides renoprotection in nondiabetic CKD such as FSGS. The primary aim of this pilot study was to determine the effect of 8 wk of dapagliflozin on glomerular filtration rate (GFR) in humans and in experimental FSGS. Secondary end points were related to changes in renal hemodynamic function, proteinuria, and blood pressure (BP). GFR (inulin) and renal plasma flow (para-aminohippurate), proteinuria, and BP were measured in patients with FSGS ( n = 10), and similar parameters were measured in subtotally nephrectomized (SNx) rats. In response to dapagliflozin, changes in GFR, renal plasma flow, and 24-h urine protein excretion were not statistically significant in humans or rats. Systolic BP (SBP) decreased in SNx rats (196 ± 26 vs. 165 ± 33 mmHg; P < 0.001), whereas changes were not statistically significant in humans (SBP 112.7 ± 8.5 to 112.8 ± 11.2 mmHg, diastolic BP 71.8 ± 6.5 to 69.6 ± 8.4 mmHg; P = not significant), although hematocrit increased (0.40 ± 0.05 to 0.42 ± 0.05%; P = 0.03). In archival kidney tissue from a separate patient cohort, renal parenchymal SGLT2 mRNA expression was decreased in individuals with FSGS compared with controls. Short-term treatment with the SGLT2i dapagliflozin did not modify renal hemodynamic function or attenuate proteinuria in humans or in experimental FSGS. This may be related to downregulation of renal SGLT2 expression. Studies examining the impact of SGLT2i on markers of kidney disease in patients with other causes of nondiabetic CKD are needed.

Effectiveness of Multifaceted Care Approach on Adverse Clinical Outcomes in Nondiabetic CKD: A Systematic Review and Meta-analysis

Introduction

The risk of major adverse events associated with chronic kidney disease (CKD) could potentially be reduced with effective medical interventions. The impact of multifaceted interventions as compared with usual care in patients with nondiabetic CKD is unclear. We performed a systematic review to analyze the impact of multifaceted interventions on reducing the risk of major adverse events in this population.

Methods

Systematic review and meta-analysis. We searched MEDLINE, EMBASE, CINAHL and the Cochrane Library databases for medical literature published up to November 2016. Published original studies and abstracts were reviewed that reported on adult patients in a community or specialty care setting, with 2 or more CKD risk factors, treated with a combination of more than 2 interventions. We included randomized controlled trials, observational studies, and systematic reviews. Studies focused on diabetic patients were excluded. The intervention was defined as a treatment with a combination of 2 or more interventions compared with the usual care. The outcomes were defined as a reduction in the risk of adverse clinical outcomes (renal replacement therapy, all-cause hospitalizations, all-cause and cardiovascular mortality, cardiovascular events) as primary outcomes. Secondary outcomes were optimal risk factor control (attaining guideline concordant blood pressure, reduction of proteinuria, smoking cessation).

Results

Five of the 5846 unique citations from our initial literature search met our study criteria. All identified studies reported on patients with CKD and their management. In comparison with usual care, multifaceted interventions tended to reduce all-cause mortality (risk ratio: 0.81, 95% confidence interval: 0.63–1.03) and were associated with a lower risk of progression to kidney failure requiring dialysis (risk ratio: 0.57, 95% confidence interval: 0.35–0.94). Multifaceted interventions were not associated with reducing risk of all-cause hospitalizations (risk ratio: 0.93, 95% confidence interval: 0.71–1.23) or improved blood pressure control (mean difference: −0.48, range: −2.5 to 1.55 mm Hg).

Discussion

Multifaceted interventions targeting multiple risk factors tended to reduce the risk of all-cause mortality and reduced the risk to progress to end-stage kidney failure in patients with CKD. There is a need for high-quality studies that can rigorously evaluate a set of interventions targeting multiple domains of CKD management in the population with nondiabetic CKD due to paucity of data in the current published literature.