Fluid homeostasis induced by sodium-glucose cotransporter 2 inhibitors: novel insight for better cardio-renal outcomes in chronic kidney disease

Water and sodium conservation response induced by SGLT2 inhibitor ipragliflozin in Dahl salt-sensitive hypertensive rats

Sodium-glucose cotransporter 2 (SGLT2) inhibitors increase urine volume with glucosuria and natriuresis. We recently reported that osmotic diuresis by the SGLT2 inhibitor ipragliflozin induces fluid homeostatic action via the stimulation of fluid intake and vasopressin-induced water reabsorption in euvolemic rats. However, the effects of SGLT2 inhibitors on these parameters in hypervolemic animals remain unclear. In this study, Dahl salt-sensitive hypertensive rats, a hypervolemic rat model, were fed a low-salt (0.3%) or high-salt (8%) diet for 14 days, then divided into vehicle or ipragliflozin (0.01%) groups. During 7 days of treatment, the high-salt diet groups significantly increased fluid intake and urine volume. In the ipragliflozin groups, fluid intake and urine volume increased by 63% and 235%, respectively, in rats fed a normal-salt diet and by 46% and 72%, respectively, in rats fed a high-salt diet. Ipragliflozin increased urinary vasopressin by 200% and solute-free water reabsorption by 196% in the normal-salt group but by only 44% and 38%, respectively, in the high-salt group. A high-salt diet significantly increased fluid balance (fluid intake - urine volume) and Na+ balance (Na+ intake - urinary Na+), but ipragliflozin did not change fluid and Na+ balance in normal- or high-salt groups. A high-salt diet significantly increased systolic blood pressure, but ipragliflozin did not significantly change systolic blood pressure in normal- or high-salt groups. In conclusion, SGLT2 inhibitor ipragliflozin did not change fluid and Na+ balance regardless of basal fluid retention, suggesting the potential of SGLT2 inhibitors to maintain body water and Na+.

Changes in 24-hour blood pressure profile after 12 weeks of dapagliflozin treatment in patients with diabetic kidney disease: an Italian multicenter prospective study

Background

Sodium-glucose cotransporter 2 inhibitors (SGLT2i) lower ambulatory blood pressure (ABP) in patients with type 2 diabetes mellitus; whether the same holds true in diabetic kidney disease (DKD) is unknown. This information is critical to the knowledge of mechanisms of nephroprotection and safety of this therapy.

Methods

This multicenter prospective study evaluates the changes in ABP after 12 weeks of dapagliflozin 10 mg/day in a cohort of patients with type 2 DKD and glomerular filtration rate (GFR) >25 mL/min/1.73 m2. Primary endpoint was the change of nighttime systolic blood pressure (SBP). Changes of daytime SBP, prevalence of normal dipping (day/night SBP ratio <0.9) and changes in ABP patterns, that is, sustained uncontrolled hypertension (SUCH), white coat uncontrolled hypertension (WUCH), masked uncontrolled hypertension (MUCH) and controlled hypertension (CH) were secondary endpoints.

Results

Eighty-three of 96 patients completed the study [age 68.7 ± 8.9 years, 73.5% males, GFR 49 ± 17 mL/min/1.73 m2, median albuminuria: 0.18 (interquartile range 0.10-0.38) g/24 h]. After 12 weeks of dapagliflozin, nighttime SBP declined by -3.0 mmHg (95% confidence interval -5.2/-0.8 mmHg; P = .010) with an improvement of nighttime SBP goal (<110 mmHg) from 18.0% to 27.0% (P < .001). Similarly, the prevalence of normal dipping increased (from 31.3% to 50.6%, P = .005). A decrease in daytime (-2.4 mmHg; P = .046) and office (-7.9 mmHg; P = .009) SBP was also found. The decline of ambulatory and office SBP was associated with increased prevalence of CH (from 6.0% to 18.0%) and significant improvement of SUCH, WUCH and MUCH (P = .009). Albuminuria decreased (P < .001), whereas eGFR did not change (P = .297). Urinary tract infection (4.2%) and acute kidney injury (3.6%) were the main causes of drop-out. Only one patient showed a drop of nighttime SBP below 90 mmHg.

Conclusions

Dapagliflozin is associated with improvement in circadian blood pressure rhythm with no major safety signal related to excessive blood pressure decrease.

Glomerular pressure and tubular oxygen supply: a critical dual target for renal protection

The primary treatment goal of chronic kidney disease (CKD) is preserving renal function and preventing its progression to end-stage renal disease. Glomerular hypertension and tubular hypoxia are critical risk factors in CKD progression. However, the renal hemodynamics make it difficult to avoid both factors due to the existence of peritubular capillaries that supply oxygen to the renal tubules downstream from the glomerulus through the efferent arteriole. In the treatment strategies for balancing glomerular pressure and tubular oxygen supply, afferent and efferent arterioles of the glomerulus determine glomerular filtration rate and blood flow to the peritubular capillaries. Therefore, sodium-glucose cotransporter 2 inhibitors and angiotensin receptor-neprilysin inhibitors as well as classical renin-angiotensin system inhibitors, which can change the diameter of afferent and/or efferent arterioles, are promising options for balancing this dual target and achieving renal protection. This review focuses on the clinical importance of glomerular pressure and tubular oxygen supply and proposes an effective treatment modality for this dual target.

Sodium-Glucose Cotransporter 2 Inhibitor Combined with Conventional Diuretics Ameliorate Body Fluid Retention without Excessive Plasma Volume Reduction

We previously reported that sodium-glucose cotransporter 2 (SGLT2) inhibitors exert sustained fluid homeostatic actions through compensatory increases in osmotic diuresis-induced vasopressin secretion and fluid intake. However, SGLT2 inhibitors alone do not produce durable amelioration of fluid retention. In this study, we examined the comparative effects of the SGLT2 inhibitor dapagliflozin (SGLT2i group, n = 53) and the combined use of dapagliflozin and conventional diuretics, including loop diuretics and/or thiazides (SGLT2i + diuretic group, n = 23), on serum copeptin, a stable, sensitive, and simple surrogate marker of vasopressin release and body fluid status. After six months of treatment, the change in copeptin was significantly lower in the SGLT2i + diuretic group than in the SGLT2i group (-1.4 ± 31.5% vs. 31.5 ± 56.3%, p = 0.0153). The change in the estimated plasma volume calculated using the Strauss formula was not significantly different between the two groups. Contrastingly, changes in interstitial fluid, extracellular water, intracellular water, and total body water were significantly lower in the SGLT2i + diuretic group than in the SGLT2i group. Changes in renin, aldosterone, and absolute epinephrine levels were not significantly different between the two groups. In conclusion, the combined use of the SGLT2 inhibitor dapagliflozin and conventional diuretics inhibited the increase in copeptin levels and remarkably ameliorated fluid retention without excessively reducing plasma volume and activating the renin-angiotensin-aldosterone and sympathetic nervous systems.

Pretreatment body mass index affects achievement of target blood pressure with sodium-glucose cotransporter 2 inhibitors in patients with type 2 diabetes mellitus and chronic kidney disease

Sodium-glucose cotransporter 2 inhibitor (SGLT2-I) shows excellent antihypertensive effects in addition to its hypoglycemic effects. However, whether body mass index (BMI) affects the antihypertensive effect of SGLT2-I remains unknown. We investigated the impact of baseline BMI on the achievement of target blood pressure (BP) with SGLT2-I treatment in Japanese patients with type 2 diabetes mellitus (T2DM) and chronic kidney disease (CKD). We retrospectively evaluated 447 Japanese patients with T2DM and CKD treated with SGLT2-I for at least 1 year. The primary outcome was achieving the target BP (<130/80 mmHg) after SGLT2-I treatment. Patients were divided into two groups according to a baseline BMI of 29.1 determined by receiver operating characteristic analysis and analyzed in a cohort model with propensity score matching. In each group, 130 patients were compared by propensity score matching. The target BP achievement rate was significantly higher in the BMI < 29.1 group than in the BMI ≥ 29.1 group (34% and 21%, respectively, p = 0.03). The odds ratio for achieving the target BP in the BMI ≥ 29.1 group was 0.50 (95% confidence interval, 0.28-0.90, p = 0.02). The BMI < 29.1 group had significantly lower systolic and diastolic BPs after SGLT2-I treatment than the BMI ≥ 29.1 group. Only the BMI < 29.1 group was showed a significant decrease in the logarithmic albumin-to-creatinine ratio from baseline after SGLT2-I treatment. In patients with T2DM and CKD, baseline BMI was associated with the antihypertensive effects of SGLT2-I. Patients in the lower baseline BMI group were more likely to achieve the target BP after SGLT2-I treatment. Pretreatment BMI affects the antihypertensice effect of SGLT2 inhibirors in patients with T2DM and CKD.

Sodium glucose cotransporter 2 inhibitor suppresses renal injury in rats with renal congestion

Renal congestion is an issue of cardiorenal syndrome in patients with heart failure. Recent clinical and basic studies suggest a renoprotective potential of sodium-glucose cotransporter (SGLT) 2 inhibitors. However, the effect on renal congestion and its mechanism is not fully understood. Thus, we aimed to clarify the effect of SGLT inhibition in a renal congestion model. Renal congestion was induced in the left kidney of male Sprague-Dawley rats by ligation of the inferior vena cava between the renal veins. The SGLT2 inhibitor tofogliflozin or vehicle was orally administered daily from the day before IVC ligation until two days after surgery. On the third postoperative day, both the right control kidney and the left congested kidney were harvested and analyzed. Kidney weight and water content was increased, and renal injury and fibrosis were observed in the left congested kidney. Kidney weight gain and hydration were improved with tofogliflozin treatment. Additionally, this treatment effectively reduced renal injury and fibrosis, particularly in the renal cortex. SGLT2 expression was observed in the congested kidney, but suppressed in the damaged tubular cells. Molecules associated with inflammation were increased in the congested kidney and reversed by tofogliflozin treatment. Mitochondrial dysfunction provoked by renal congestion was also improved by tofogliflozin treatment. Tofogliflozin protects against renal damage induced by renal congestion. SGLT2 inhibitors could be a candidate strategy for renal impairment associated with heart failure.

2023 update and perspectives

Total 276 manuscripts were published in Hypertension Research in 2022. Here our editorial members picked up the excellent papers, summarized the current topics from the published papers and discussed future perspectives in the sixteen fields. We hope you enjoy our special feature, 2023 update and perspectives in Hypertension Research.

Fluid homeostatic action of dapagliflozin in patients with chronic kidney disease: the DAPA-BODY Trial

Sodium glucose cotransporter 2 (SGLT2) inhibitors have both glucose-lowering and diuretic effects. We recently reported that the SGLT2 inhibitor dapagliflozin exerts short-term fluid homeostatic action in patients with chronic kidney disease (CKD). However, the long-term effects of SGLT2 inhibitors on body fluid status in patients with CKD remain unclear. This was a prospective, non-randomized, open-label study that included a dapagliflozin treatment group (n = 73) and a control group (n = 24) who were followed for 6 months. Body fluid volume was measured using a bioimpedance analysis device. The extracellular water-to-total body water ratio (ECW/TBW), a predictor of renal outcomes, was used as a parameter for body fluid status (fluid retention, 0.400 ≤ ECW/TBW). Six-month treatment with dapagliflozin significantly decreased ECW/TBW compared with the control group (-0.65% ± 2.03% vs. 0.97% ± 2.49%, p = 0.0018). Furthermore, dapagliflozin decreased the ECW/TBW in patients with baseline fluid retention, but not in patients without baseline fluid retention (-1.47% ± 1.93% vs. -0.01% ± 1.88%, p = 0.0017). Vasopressin surrogate marker copeptin levels were similar between the control and dapagliflozin groups at 6 months (32.3 ± 33.4 vs. 30.6 ± 30.1 pmol/L, p = 0.8227). However, dapagliflozin significantly increased the change in copeptin levels at 1 week (39.0% ± 41.6%, p = 0.0010), suggesting a compensatory increase in vasopressin secretion to prevent hypovolemia. Renin and aldosterone levels were similar between the control and dapagliflozin groups at 6 months, while epinephrine and norepinephrine (markers of sympathetic nervous system activity) were significantly lower in the dapagliflozin group than in the control group. In conclusion, the SGLT2 inhibitor dapagliflozin ameliorated fluid retention and maintained euvolemic fluid status in patients with CKD, suggesting that SGLT2 inhibitors exert sustained fluid homeostatic actions in patients with various fluid backgrounds. Clinical trial registration: https://www.umin.ac.jp/ctr/, identifier [UMIN000048568].

Long-term observation of estimated fluid volume reduction after the initiation of ipragliflozin in patients with type 2 diabetes mellitus: a sub-analysis from a randomized controlled trial (PROTECT)

BACKGROUNDS/AIM

Recent studies have shown that the addition of sodium-glucose co-transporter 2 (SGLT2) inhibitors gradually reduces the estimated fluid volume parameters in a broad range of patient populations, suggesting that this mediates the clinical benefits of SGLT2 inhibitors in preventing heart failure. Here, we sought to examine the long-term (24 months) effect of the SGLT2 inhibitor ipragliflozin on the estimated fluid volume parameters in patients with type 2 diabetes mellitus (T2DM).

METHODS

In this prespecified sub-analysis of the PROTECT (Prevention of Atherosclerosis by SGLT2 Inhibitor: Multicenter, Randomized Controlled Study) trial, which was an investigator-initiated, multicenter, prospective, randomized, open-label, clinical trial primarily designed to evaluate the effect of ipragliflozin treatment administered for 24 months on carotid atherosclerosis in patients with T2DM, we evaluated serial changes in estimated plasma volume (ePV, %) calculated using the Straus formula and estimated extracellular volume (eEV, mL) calculated by the body surface area by 24 months following the initiation of 50-mg ipragliflozin once daily and compared them with those following standard care for T2DM (non-SGLT2 inhibitor use).

RESULTS

This sub-analysis included 464 patients (ipragliflozin, n = 232; control, n = 232), a full analysis set of the PROTECT trial. In an analysis using mixed-effects models for repeated measures, relative to the control group, ipragliflozin significantly reduced ePV by - 10.29% (95% confidence interval [CI]  - 12.47% to - 8.11%; P < 0.001) at 12 months and - 10.76% (95% CI - 12.86% to - 8.67%; P < 0.001) at 24 months. Additionally, ipragliflozin significantly reduced eEV by - 190.44 mL (95% CI - 249.09 to - 131.79 mL; P < 0.001) at 12 months and - 176.90 mL (95% CI  - 233.36 to - 120.44 mL; P < 0.001) at 24 months. The effects of ipragliflozin on these parameters over 24 months were mostly consistent across various patient clinical characteristics.

CONCLUSIONS

This prespecified sub-analysis from the PROTECT trial demonstrated that ipragliflozin treatment, compared with the standard care for T2DM, reduced two types of estimated fluid volume parameters in patients with T2DM, and the effect was maintained for 24 months. Our findings suggest that SGLT2 inhibitor treatment regulates clinical parameters incorporated into the calculating formulas analyzed and consequently fluid volume status for the long-term, and this may be at least partly associated with clinical benefits from chronic use of SGLT2 inhibitors. Trial registration Japan Registry of Clinical Trials, ID jRCT1071220089.