Changes in Proximal Tubular Reabsorption Modulate Microvascular Regulation via the TGF System

Furosemide attenuates tubulointerstitial injury and allows functional testing of porcine kidneys during normothermic machine perfusion

BACKGROUND

Normothermic machine perfusion (NMP) is a promising pretransplant kidney quality assessment platform, but it remains crucial to increase its diagnostic potential while ensuring minimal additional injury to the already damaged kidney. Interventions that alter tubular transport can influence renal function and injury during perfusion. This study aimed to determine whether furosemide and desmopressin affect renal function and injury during NMP.

METHODS

Eighteen porcine kidneys (n = 6 per group) were subjected to 30 min of warm ischemia and 4 h of oxygenated hypothermic perfusion before being subjected to 6 h of NMP. Each organ was randomized to receive no drug, furosemide (750 mg), or desmopressin (16 μg) during NMP.

RESULTS

Compared with the other groups, the addition of furosemide resulted in significantly increased urine output, fractional excretion of sodium and potassium, and urea clearance during NMP. Urinary neutrophil gelatinase-associated lipocalin levels decreased significantly with furosemide supplementation compared with the other groups. The addition of desmopressin did not result in any significantly different outcome measurements compared with the control group.

CONCLUSIONS

This study showed that the addition of furosemide affected renal function while attenuating tubulointerstitial injury during NMP. Therefore, furosemide supplementation may provide renal protection and serve as a functional test for pretransplant kidney viability assessment during NMP.

Acute Kidney Injury and Electrolyte Imbalances Caused by Dapagliflozin Short-Term Use

Dapagliflozin, a sodium-glucose cotransporter 2 inhibitor (SGLT2i), has shown demonstrated benefits for renal and cardiovascular outcomes in large clinical trials. However, short-term concerns regarding its impact on renal function and electrolyte balance exist. This study aimed to evaluate the short-term effects of dapagliflozin on renal function and electrolyte balance in patients newly prescribed the medication. A retrospective analysis of 246 patients who initiated dapagliflozin therapy was conducted. Serum creatinine, sodium, and potassium levels were measured at baseline (before dapagliflozin) and 5-8 days after initiation (endpoint). A Wilcoxon signed-rank test, Pearson's chi-square test, and Fischer's exact test were used for the data analysis. Glycemia and sodium levels were significantly higher at the baseline compared to the endpoint (p < 0.001). Conversely, creatinine and potassium levels were significantly higher at the endpoint than at the baseline (p < 0.001). The prevalence of hyponatremia and hyperkalemia were increased at the endpoint (17.5% vs. 10.2% and 16.7% vs. 8.9%, respectively). Although not statistically significant, a trend towards increased hyponatremia with the co-administration of furosemide was observed (p = 0.089). No significant association was found between potassium-sparing medications (p > 0.05) and hyperkalemia, except for angiotensin receptor blockers (p = 0.017). The combination of dapagliflozin and furosemide significantly increased the risk of acute kidney injury (AKI) at the endpoint (p = 0.006). Age, gender, and chronic kidney disease status did not significantly influence the occurrence of AKI, hyponatremia, or hyperkalemia (p > 0.05). These findings emphasize the importance of the close monitoring of renal function and electrolyte balance, particularly in the early stages of dapagliflozin therapy, especially in patients receiving diuretics or renin-angiotensin-aldosterone system inhibitors.

Unlocking the potential of tumor-derived DNA in urine for cancer detection: methodological challenges and opportunities

High cancer mortality rates and the rising cancer burden worldwide drive the development of innovative methods in order to advance cancer diagnostics. Urine contains a viable source of tumor material and allows for self-collection from home. Biomarker testing in this liquid biopsy represents a novel approach that is convenient for patients and can be effective in detecting cancer at a curable stage. Here, we set out to provide a detailed overview of the rationale behind urine-based cancer detection, with a focus on non-urological cancers, and its potential for cancer diagnostics. Moreover, evolving methodological challenges and untapped opportunities for urine biomarker testing are discussed, particularly emphasizing DNA methylation of tumor-derived cell-free DNA. We also provide future recommendations for technical advancements in urine-based cancer detection and elaborate on potential mechanisms involved in the transrenal transport of cell-free DNA.

Dapagliflozin can alleviate renal fibrosis in rats with streptozotocin‑induced type 2 diabetes mellitus

The aim of the present study was to explore the effects of Dapagliflozin on renal fibrosis in streptozotocin (STZ)-induced type 2 diabetes mellitus (T2DM) rats, and to determine the underlying mechanism of action. A total of 24 SPF male SD rats were randomly divided into 4 groups: A normal (Control) group, model group (STZ-induced T2DM rats), Dapagliflozin group (STZ-induced T2DM rats treated with 1 mg/kg Dapagliflozin), and a metformin group (STZ-induced T2DM rats treated with 200 mg/kg metformin), with 6 rats per a group. Peripheral blood and renal tissues were collected from these rats, and the renal indices of each group were examined. The fasting blood glucose (FBG), glycosylated hemoglobin (HbA1c), blood urea nitrogen (BUN), and serum creatinine (SCr) of rats were detected. After 24 h, the urine was collected and the urine protein levels were measured. Hematoxylin and eosin staining was used to detect histological changes in the rat kidney; Masson staining was used to observe the degree of fibrosis in rat renal tissues; and western blot was performed to determine the expression levels of α-smooth muscle actin (SMA), vimentin, E-cadherin, TGF-β1, Smad7, and p-Smad3 in rat renal tissues. Dapagliflozin effectively inhibited the increase in FBG and HbA1c levels in diabetic mice, reduced renal tissue damage, reduced the renal index values, reduced collagen deposition in the glomerulus and interstitial area, and reduced the proliferation of glomerular mesangial cells. In addition, Dapagliflozin significantly lowered the levels of BUN, SCr, and 24-h urine protein, decreased the protein expression of α-SMA, vimentin, TGF-β1, and p-Smad3, and increased the protein expression levels of E-cadherin and Smad7. Together, these results showed that Dapagliflozin alleviated renal fibrosis in STZ-induced T2DM rats, and its mechanism of action may be related to the inhibition of the TGF-β1/Smad pathway.

Blinded Withdrawal of Long-Term Randomized Treatment With Empagliflozin or Placebo in Patients With Heart Failure

BACKGROUND

It is not known whether the benefits of sodium-glucose cotransporter 2 inhibitors in heart failure persist after years of therapy.

METHODS

In the EMPEROR-Reduced (Empagliflozin Outcome Trials in Chronic Heart Failure With Reduced Ejection Fraction) and EMPEROR-Preserved (Empagliflozin Outcome Trials in Chronic Heart Failure With Preserved Ejection Fraction) trials, patients with heart failure were randomly assigned (double-blind) to placebo or empagliflozin 10 mg/day for a median of 16 and 26 months, respectively. At the end of the trials, 6799 patients (placebo 3381, empagliflozin 3418) were prospectively withdrawn from treatment in a blinded manner, and, of these, 3981 patients (placebo 2020, empagliflozin 1961) underwent prespecified in-person assessments after ≈30 days off treatment.

RESULTS

From 90 days from the start of closeout to the end of double-blind treatment, the annualized risk of cardiovascular death or hospitalization for heart failure was lower in empagliflozin-treated patients than in placebo-treated patients (10.7 [95% CI, 9.0-12.6] versus 13.5 [95% CI, 11.5-15.6] events per 100 patient-years, respectively; hazard ratio 0.76 [95% CI, 0.60-0.96]). When the study drugs were withdrawn for ≈30 days, the annualized risk of cardiovascular death or hospitalization for heart failure increased in patients withdrawn from empagliflozin but not in those withdrawn from placebo (17.0 [95% CI, 12.6-22.1] versus 14.1 [95% CI, 10.1-18.8] events per 100 patient-years for empagliflozin and placebo, respectively). The hazard ratio for the change in risk in the patients withdrawn from empagliflozin was 1.75 (95% CI, 1.20-2.54), P=0.0034, whereas the change in the risk in patients withdrawn from placebo was not significant (hazard ratio 1.12 [95% CI, 0.76-1.66]); time period-by-treatment interaction, P=0.068. After withdrawal, the Kansas City Cardiomyopathy Questionnaire Clinical Summary Score declined by 1.6±0.4 in patients withdrawn from empagliflozin versus placebo (P<0.0001). Furthermore, withdrawal of empagliflozin was accompanied by increases in fasting glucose, body weight, systolic blood pressure, estimated glomerular filtration rate, N-terminal pro-hormone B-type natriuretic peptide, uric acid, and serum bicarbonate and decreases in hemoglobin and hematocrit (all P<0.01). These physiological and laboratory changes were the inverse of the effects of the drug seen at the start of the trials during the initiation of treatment (≈1-3 years earlier) in the same cohort of patients.

CONCLUSIONS

These observations demonstrate a persistent effect of empagliflozin in patients with heart failure even after years of treatment, which dissipated rapidly after withdrawal of the drug.

REGISTRATION

URL: https://www.

CLINICALTRIALS

gov; Unique identifiers: NCT03057977 and NCT03057951.

Diabetic Nephropathy: Update on Pillars of Therapy Slowing Progression

Management of diabetic kidney disease (DKD) has evolved in parallel with our growing understanding of the multiple interrelated pathophysiological mechanisms that involve hemodynamic, metabolic, and inflammatory pathways. These pathways and others play a vital role in the initiation and progression of DKD. Since its initial discovery, the blockade of the renin-angiotensin system has remained a cornerstone of DKD management, leaving a large component of residual risk to be dealt with. The advent of sodium-glucose cotransporter 2 inhibitors followed by nonsteroidal mineralocorticoid receptor antagonists and, to some extent, glucagon-like peptide 1 receptor agonists (GLP-1 RAs) has ushered in a resounding paradigm shift that supports a pillared approach in maximizing treatment to reduce outcomes. This pillared approach is like that derived from the approach to heart failure treatment. The approach mandates that all agents that have been shown in clinical trials to reduce cardiovascular outcomes and/or mortality to a greater extent than a single drug class alone should be used in combination. In this way, each drug class focuses on a specific aspect of the disease's pathophysiology. Thus, in heart failure, β-blockers, sacubitril/valsartan, a mineralocorticoid receptor antagonist, and a diuretic are used together. In this article, we review the evolution of the pillar concept of therapy as it applies to DKD and discuss how it should be used based on the outcome evidence. We also discuss the exciting possibility that GLP-1 RAs may be an additional pillar in the quest to further slow kidney disease progression in diabetes.

Intrarenal Mechanisms of Sodium-Glucose Cotransporter-2 Inhibitors on Tubuloglomerular Feedback and Natriuresis

When sodium-glucose cotransporter-2 (SGLT2) inhibitors were first introduced a decade ago, no one expected them to have substantial effects beyond their known glucose-lowering effects, until the emergence of evidence of their robust renal and cardiovascular benefits showing that they could attenuate progression of kidney disease, irrespective of diabetes, as well as prevent the development of acute kidney injury. Still, the precise and elaborate mechanisms underlying the major organ protection of SGLT2 inhibitors remain unclear. SGLT2 inhibitors inhibit the reabsorption of sodium and glucose in the proximal tubule of the kidney and then recovers tubuloglomerular feedback, whereby SGLT2 inhibitors reduce glomerular hyperfiltration. This simple demonstration of their beneficial effects has perplexed experts in seeking more plausible and as yet undisclosed explanations for the whole effects of SGLT2 inhibitors, including metabolism reprogramming and the modulation of hypoxia, inflammation, and oxidative stress. Given that the renal benefits of SGLT2 inhibitors in patients with kidney disease but without diabetes were comparable to those seen in patients with diabetes, it may be reasonable to keep the emphasis on their hemodynamic actions. In this context, the aim of the present review is to provide a comprehensive overview of renal hemodynamics in individuals with diabetes who are treated with SGLT2 inhibitors, with a focus on natriuresis associated with the regulation of tubuloglomerular feedback and potential aquaresis. Throughout the discussion of alterations in renal sodium and water transports, particular attention will be given to the potential enhancement of adenosine and its receptors following SGLT2 inhibition.

Inhibition of SGLT2 co-transporter by dapagliflozin ameliorates tubular proteinuria and tubule-interstitial injury at the early stage of diabetic kidney disease

Diabetic kidney disease (DKD) is characterized by progressive impairment of kidney function. It has been postulated that tubule-interstitial injury, associated with tubular albuminuria, precedes glomerular damage in the early stage of DKD. Here, we wanted to determine if the development of tubule-interstitial injury at the early stage of DKD implies modulation of megalin-mediated protein reabsorption in proximal tubule epithelial cells (PTECs) by SGLT2-dependent high glucose influx. Rats with streptozotocin (STZ)-induced diabetes were treated or not with dapagliflozin (DAPA) for 8 weeks. Four experimental groups were generated: (1) CONT, control; (2) DAPA, rats treated with DAPA; (3) STZ, diabetic rats; (4) STZ + DAPA, diabetic rats treated with DAPA. No changes in glomerular structure and function were observed. The STZ group presented proteinuria and albuminuria associated with an increase in the fractional excretion of proteins. A positive correlation between glycemia and proteinuria was found. These phenomena were linked to a decrease in luminal and total megalin expression and, consequently, in albumin reabsorption in PTECs. We also observed tubule-interstitial injury characterized by an increase in urinary tubular injury biomarkers and changes in tubular histomorphometry parameters. In addition, inverse correlations were found between cortical albumin uptake and tubule-interstitial injury or glycemia. All these modifications were attenuated in the STZ + DAPA group. These results suggest that SGLT2-dependent high glucose influx into PTECs promotes a harmful effect on the PTECs, leading to the development of tubular albuminuria and tubule-interstitial injury preceding glomerular damage. These results expand current knowledge on the renoprotective effects of gliflozins.