Water Conservation Overrides Osmotic Diuresis During SGLT2 Inhibition in Patients With Heart Failure.

BACKGROUND: Sodium-glucose cotransporter 2 inhibitors are believed to improve cardiac outcomes due to their osmotic diuretic potential. OBJECTIVES: The goal of this study was to test the hypothesis that vasopressin-driven urine concentration overrides the osmotic diuretic effect of glucosuria induced by dapagliflozin treatment. METHODS: DAPA-Shuttle1 (Hepato-renal Regulation of Water Conservation in Heart Failure Patients With SGLT-2 Inhibitor Treatment) was a single-center, double-blind, randomized, placebo-controlled trial, in which patients with chronic heart failure NYHA functional classes I/II and reduced ejection fraction were randomly assigned to receive dapagliflozin 10 mg daily or placebo (1:1) for 4 weeks. The primary endpoint was change from baseline in urine osmolyte concentration. Secondary endpoints included changes in copeptin levels and solute free water clearance. RESULTS: Thirty-three randomized, sodium-glucose cotransporter 2 inhibitor-naïve participants completed the study, 29 of whom (placebo: n = 14; dapagliflozin: n = 15) provided accurate 24-hour urine collections (mean age 59 ± 14 years; left ventricular ejection fraction 31% ± 9%). Dapagliflozin treatment led to an isolated increase in urine glucose excretion by 3.3 mmol/kg/d (95% CI: 2.51-4.04; P < 0.0001) within 48 hours (early) which persisted after 4 weeks (late; 2.7 mmol/kg/d [95% CI: 1.98-3.51]; P < 0.0001). Dapagliflozin treatment increased serum copeptin early (5.5 pmol/L [95% CI: 0.45-10.5]; P < 0.05) and late (7.8 pmol/L [95% CI: 2.77-12.81]; P < 0.01), leading to proportional reductions in free water clearance (early: -9.1 mL/kg/d [95% CI: -14 to -4.12; P < 0.001]; late: -11.0 mL/kg/d [95% CI: -15.94 to -6.07; P < 0.0001]) and elevated urine concentrations (late: 134 mmol/L [95% CI: 39.28-229.12]; P < 0.01). Therefore, urine volume did not significantly increase with dapagliflozin (mean difference early: 2.8 mL/kg/d [95% CI: -1.97 to 7.48; P = 0.25]; mean difference late: 0.9 mL/kg/d [95% CI: -3.83 to 5.62]; P = 0.70). CONCLUSIONS: Physiological-adaptive water conservation eliminated the expected osmotic diuretic potential of dapagliflozin and thereby prevented a glucose-driven increase in urine volume of approximately 10 mL/kg/d · 75 kg = 750 mL/kg/d. (Hepato-renal Regulation of Water Conservation in Heart Failure Patients With SGLT-2 Inhibitor Treatment [DAPA-Shuttle1]; NCT04080518).

Cardiotoxicity Associated with Immune Checkpoint Inhibitors.

Immune checkpoint inhibitors (ICIs) have shown significant efficacy in various cancers, including non-small cell lung cancer, small cell lung cancer, melanoma, classical Hodgkin lymphoma, head and neck squamous cell carcinoma, urothelial cancer, and renal cell carcinoma [...].

Mfsd2a-mediated lysolipid transport is important for renal recovery after acute kidney injury.

Acute kidney injury (AKI) is a global public health concern with high mortality and morbidity. In ischemic-reperfusion injury (IRI), a main cause of AKI, the brush border membrane of S3 proximal tubules (PT) is lost to the tubular lumen. How injured tubules reconstitute lost membrane lipids during renal recovery is not known. Here, we identified Mfsd2a, a sodium-dependent lysophosphatidylcholine (LPC) transporter, to be expressed specifically in the basolateral membrane of S3 PT. Using an in vivo activity probe for Mfsd2a, transport activity was found to be specific to the S3 PT. Mice with haploinsufficiency of Mfsd2a exhibited delayed recovery of renal function after acute IRI, with depressed urine osmolality and elevated levels of histological markers of damage, fibrosis, and inflammation, findings corroborated by transcriptomic analysis. Lipidomics revealed a deficiency in docosahexaenoic acid (DHA) containing phospholipids in Mfsd2a haploinsufficiency. Treatment of Mfsd2a haploinsufficient mice with LPC-DHA improved renal function and reduced markers of injury, fibrosis, and inflammation. Additionally, LPC-DHA treatment restored S3 brush border membrane architecture and normalized DHA-containing phospholipid content. These findings indicate that Mfsd2a-mediated transport of LPC-DHA is limiting for renal recovery after AKI and suggest that LPC-DHA could be a promising dietary supplement for improving recovery following AKI.

Immune Checkpoint Inhibitors Do Not Increase Short-Term Risk of Hypertension in Cancer Patients: a Systematic Literature Review and Meta-Analysis.

BACKGROUND: Immune checkpoint inhibitors (ICIs) are becoming widely used for novel cancer treatments. Immune-related adverse events, including cardiac toxicity, are frequently observed following immune checkpoint inhibitor (ICI) use. However, little is known regarding the association between ICIs initiation and hypertension in cancer patients. METHODS: A systematic literature search was performed using PubMed, EMBASE, Cochrane Library, and Web of Science Core Collection. The risk of hypertension associated with ICI initiation in randomized controlled trials (RCTs) was evaluated. Hypertension was categorized according to the Common Terminology Criteria for Adverse Events. The odds ratios of grades I to V and grades III to V hypertension were calculated using a random-effects meta-analysis. RESULTS: Thirty-two RCTs (n=19 810 cancer patients) were included. At a median follow-up of 36 months, the median overall survival was 15 months in the ICI group. ICI initiation was not significantly associated with hypertension (grades I-V: odds ratio, 1.12 [95% CI, 0.96-1.30]; grades III-V: odds ratio, 0.95 [95% CI, 0.78-1.16]). Additionally, no significant differences in hypertension risk were evident in ICI combination therapies with various drugs, including anti-VEGF (vascular endothelial growth factor) agents. In a subgroup analysis based on clinical setting (placebo RCT versus nonplacebo RCT), there were discrepancies between the results obtained with different methodologies, with patients in the nonplacebo RCTs having higher grades I-V hypertension (I2=88.6%, P for heterogeneity=0.003). CONCLUSIONS: ICI initiation was not associated with short-term risk of hypertension in cancer patients, and the association was similar regardless of concomitant treatment with other anticancer drugs.

Adaptive physiological water conservation explains hypertension and muscle catabolism in experimental chronic renal failure.

AIM: We have reported earlier that a high salt intake triggered an aestivation-like natriuretic-ureotelic body water conservation response that lowered muscle mass and increased blood pressure. Here, we tested the hypothesis that a similar adaptive water conservation response occurs in experimental chronic renal failure. METHODS: In four subsequent experiments in Sprague Dawley rats, we used surgical 5/6 renal mass reduction (5/6 Nx) to induce chronic renal failure. We studied solute and water excretion in 24-hour metabolic cage experiments, chronic blood pressure by radiotelemetry, chronic metabolic adjustment in liver and skeletal muscle by metabolomics and selected enzyme activity measurements, body Na+ , K+ and water by dry ashing, and acute transepidermal water loss in conjunction with skin blood flow and intra-arterial blood pressure. RESULTS: 5/6 Nx rats were polyuric, because their kidneys could not sufficiently concentrate the urine. Physiological adaptation to this renal water loss included mobilization of nitrogen and energy from muscle for organic osmolyte production, elevated norepinephrine and copeptin levels with reduced skin blood flow, which by means of compensation reduced their transepidermal water loss. This complex physiologic-metabolic adjustment across multiple organs allowed the rats to stabilize their body water content despite persisting renal water loss, albeit at the expense of hypertension and catabolic mobilization of muscle protein. CONCLUSION: Physiological adaptation to body water loss, termed aestivation, is an evolutionary conserved survival strategy and an under-studied research area in medical physiology, which besides hypertension and muscle mass loss in chronic renal failure may explain many otherwise unexplainable phenomena in medicine.

Effects of Erythropoietin-Stimulating Agents on Blood Pressure in Patients with Non-Dialysis CKD and Renal Anemia.

INTRODUCTION: Erythropoietin-stimulating agents (ESAs) are used to treat renal anemia in patients with non-dialysis CKD, but this can lead to increases in blood pressure (BP). OBJECTIVE: We investigated the effects of continuous erythropoietin receptor activator (CERA) and darbepoetin alfa (DA) on office/ambulatory BP in 36 patients with non-dialysis CKD and renal anemia who did not receive ESA treatment. METHODS: Participants were randomly assigned to CERA or DA, and received ESA treatment for 24 weeks. ESA doses were adjusted to maintain hemoglobin (Hb) at 10-12 g/dL. Primary outcomes were office/ambulatory BP after 24 weeks of ESA treatment. Hb levels were within the target range at 24 weeks. RESULTS: Office/ambulatory BP, renal function, and other parameters were not significantly different between groups. However, we could not exclude the possibility that differences may exist because our sample size was small. Therefore, we also performed analysis of all of the data that were compiled from the groups of per-protocol population. Although office/ambulatory BP profiles had not worsened after 24 weeks of ESA treatment, more than half of the patients required an increase in the antihypertensive agent dose. CONCLUSIONS: CERA and DA may have similar effects on BP profiles in patients with non-dialysis CKD and renal anemia. ESA treatment often requires increases in the doses of antihypertensive agents.

Regulators of Epithelial Sodium Channels in Aldosterone-Sensitive Distal Nephrons (ASDN): Critical Roles of Nedd4L/Nedd4-2 and Salt-Sensitive Hypertension.

Ubiquitination is a representative, reversible biological process of the post-translational modification of various proteins with multiple catalytic reaction sequences, including ubiquitin itself, in addition to E1 ubiquitin activating enzymes, E2 ubiquitin conjugating enzymes, E3 ubiquitin ligase, deubiquitinating enzymes, and proteasome degradation. The ubiquitin-proteasome system is known to play a pivotal role in various molecular life phenomena, including the cell cycle, protein quality, and cell surface expressions of ion-transporters. As such, the failure of this system can lead to cancer, neurodegenerative diseases, cardiovascular diseases, and hypertension. This review article discusses Nedd4-2/NEDD4L, an E3-ubiquitin ligase involved in salt-sensitive hypertension, drawing from detailed genetic dissection analysis and the development of genetically engineered mice model. Based on our analyses, targeting therapeutic regulations of ubiquitination in the fields of cardio-vascular medicine might be a promising strategy in future. Although the clinical applications of this strategy are limited, compared to those of kinase systems, many compounds with a high pharmacological activity were identified at the basic research level. Therefore, future development could be expected.

Sodium Handling and Interaction in Numerous Organs.

Salt (NaCl) is a prerequisite for life. Excessive intake of salt, however, is said to increase disease risk, including hypertension, arteriosclerosis, heart failure, renal disease, stroke, and cancer. Therefore, considerable research has been expended on the mechanism of sodium handling based on the current concepts of sodium balance. The studies have necessarily relied on relatively short-term experiments and focused on extremes of salt intake in humans. Ultra-long-term salt balance has received far less attention. We performed long-term salt balance studies at intakes of 6, 9, and 12 g/day and found that although the kidney remains the long-term excretory gate, tissue and plasma sodium concentrations are not necessarily the same and that urinary salt excretion does not necessarily reflect total-body salt content. We found that to excrete salt, the body makes a great effort to conserve water, resulting in a natriuretic-ureotelic principle of salt excretion. Of note, renal sodium handling is characterized by osmolyte excretion with anti-parallel water reabsorption, a state-of-affairs that is achieved through the interaction of multiple organs. In this review, we discuss novel sodium and water balance concepts in reference to our ultra-long-term study. An important key to understanding body sodium metabolism is to focus on water conservation, a biological principle to protect from dehydration, since excess dietary salt excretion into the urine predisposes to renal water loss because of natriuresis. We believe that our research direction is relevant not only to salt balance but also to cardiovascular regulatory mechanisms.

Effects of Rikkunshito treatment on renal fibrosis/inflammation and body weight reduction in a unilateral ureteral obstruction model in mice.

Chronic kidney disease (CKD) progresses to end-stage renal failure via renal tubulointerstitial fibrosis. Malnutrition, inflammation, and arteriosclerosis interact to exacerbate the poor prognosis of CKD, and their effective management is thus essential. The traditional Japanese medicine Rikkunshito (RKT) exerts appetite-stimulating effects via ghrelin, which attenuates inflammation and fibrosis. We evaluated the therapeutic effect of RKT in unilateral ureter obstruction (UUO)-induced renal fibrosis/inflammation and body weight loss in mice. UUO and sham-operated mice were fed a standard diet or diet containing 3.0% RKT. Renal fibrosis was investigated by histopathology and macrophage infiltration was determined by immunohistochemistry. Expression levels of genes associated with fibrosis, inflammation, ghrelin, and mitochondrial function were determined by quantitative reverse transcription-polymerase chain reaction and western blot analyses. RKT treatment partially prevented UUO-induced weight loss but failed to attenuate renal fibrosis and inflammation. Renal expression of sirtuin 1, a ghrelin-downstream signalling molecule, and gene expression of peroxisome proliferator-activated receptor-γ coactivator 1α and Bcl-2/adenovirus E1B interacting protein 3 were unaffected by RKT. These results indicate that RKT inhibits weight loss but does not improve renal fibrosis or inflammation in a rapidly progressive renal fibrosis mouse model. RKT may have a protective effect on weight loss associated with CKD.

Native T1 time and extracellular volume fraction in differentiation of normal myocardium from non-ischemic dilated and hypertrophic cardiomyopathy myocardium: A systematic review and meta-analysis.

BACKGROUND: Both native T1 time and extracellular volume (ECV) fraction have been shown to be important measures for the detection of myocardial fibrosis. However, ECV determination requires the administration of an intravenous contrast agent, whereas native T1 mapping can be performed without a contrast agent. METHODS: Here, we conducted a meta-analysis of myocardial native T1 data obtained for non-ischemic cardiomyopathy (NIC) patients and controls. A literature review included studies that applied T1 mapping using modified Look-Locker inversion recovery to measure myocardial fibrosis, and the results were validated by comparing datasets for dilated cardiomyopathy (DCM) or hypertrophic cardiomyopathy (HCM) patients and healthy controls (HCs). RESULTS: We identified 16 eligible studies. Pooled mean differences (MDs) and 95% confidence intervals (CIs) were estimated as follows. Native T1 at 1.5-T, DCM vs. HC: MD = 45.26 (95% CI: 30.92-59.59); HCM vs. HC: MD = 47.09 (95% CI: 32.42-61.76). Native T1 at 3.0-T, DCM vs. HC: MD = 82.52 (95% CI: 47.60-117.44); HCM vs. HC: MD = 115.87 (95% CI: 50.71-181.04). ECV at 1.5-T, DCM vs. HC: MD = 4.26 (95% CI: 3.06-5.46); HCM vs. HC: MD = 1.49 (95% CI: -1.45-4.43). ECV at 3.0-T, DCM vs. HC: MD = 8.40 (95% CI: 2.94-13.86); HCM vs. HC: MD = 8.02 (95% CI: 5.45-1-0.59). CONCLUSION: In conclusion, native T1 values were significantly different between NIC patients and controls. Native T1 mapping may be a useful noninvasive method to detect diffuse myocardial fibrosis in NIC patients.

Lubiprostone as a potential therapeutic agent to improve intestinal permeability and prevent the development of atherosclerosis in apolipoprotein E-deficient mice.

The interaction between atherosclerosis and commensal microbes through leaky gut syndrome (LGS), which is characterized by impaired intestinal permeability and the introduction of undesired pathogens into the body, has not been fully elucidated. Our aim was to investigate the potential role of a ClC-2 chloride channel activator, lubiprostone, which is reported to have beneficial effects on LGS, in the development of atherosclerosis in apolipoprotein E-deficient (ApoE-/-) mice. After a 15-week feeding period of a Western diet (WD), ApoE-/- mice were treated with a Western-type diet (WD) alone or WD with oral supplementation of lubiprostone for 10 weeks. This feeding protocol was followed by experimental evaluation of LGS and atherosclerotic lesions in the aorta. In mice with lubiprostone, in vivo translocation of orally administered 4-kDa FITC-dextran was significantly improved, and RNA expression of the epithelial tight junction proteins, Zo-1 and occludin, was significantly up-regulated in the ileum, compared to the WD alone group, suggesting a possible reversal of WD-induced intestinal barrier dysfunction. As a result, WD-induced exacerbation of atherosclerotic lesion formation was reduced by 69% in longitudinally opened aortas and 26% in aortic root regions. In addition, there was a significant decrease in circulating immunoglobulin level, followed by an attenuation of inflammatory responses in the perivascular adipose tissue, as evidenced by reduced expression of pro-inflammatory cytokines and chemokines. Lubiprostone attenuates atherosclerosis by ameliorating LGS-induced inflammation through the restoration of the intestinal barrier. These findings raise the possibility of targeting LGS for the treatment of atherosclerosis.

Effects of ATRAP in Renal Proximal Tubules on Angiotensin-Dependent Hypertension.

Background We have previously shown that ATRAP (angiotensin II receptor-associated protein; Agtrap) interacts with AT1R (angiotensin II type 1 receptor) and promotes constitutive internalization of AT 1R so as to inhibit hyperactivation of its downstream signaling. In response to angiotensin II , systemic ATRAP deficiency exacerbates angiotensin II -mediated hypertension via hyperactivation of renal tubular AT 1R. Although ATRAP expression is abundant in renal proximal tubules, little is known about the actual function of renal proximal tubule ATRAP in angiotensin-mediated hypertension. Methods and Results In this study, we examined the in vivo functional role of renal proximal tubule ATRAP in angiotensin-dependent hypertension. We succeeded in generating proximal tubule-specific ATRAP knockout ( PT - KO ) mice for the first time using the Cre/loxP system with Pepck-Cre. Detailed analysis of renal ATRAP expression in PT - KO mice estimated by immunohistochemical and laser-capture microdissection analysis revealed that ATRAP mRNA expression decreased by ≈80% in proximal regions of the nephron in PT - KO mice compared with wild-type ( WT ) mice. We compared blood pressure of PT - KO and WT mice using both tail-cuff and radiotelemetric methods. Blood pressure of PT - KO mice was comparable with that of WT mice at baseline. Moreover, no significant differences were noted in pressor response to angiotensin II (600 ng/kg per min or 1000 ng/kg per minute) infusion between PT - KO and WT mice. In addition, angiotensin II -mediated cardiac hypertrophy was identical between PT - KO and WT mice. Conclusions ATRAP deficiency in proximal tubules did not exacerbate angiotensin-dependent hypertension in vivo. The results indicate that renal proximal tubule ATRAP has a minor role in angiotensin-dependent hypertension in vivo.

Effects of rikkunshito on renal fibrosis and inflammation in angiotensin II-infused mice.

The underlying pathogenesis of chronic kidney disease involves an activated renin-angiotensin system and systemic inflammation which ultimately develop renal injury. Rikkunshito (RKT) has been reported to exert anti-fibrotic and anti-inflammatory effects through enhancement of ghrelin signaling pathway. In this study, we investigated the effects of RKT on renal fibrosis and inflammation in angiotensin II (Ang II)-induced renal injury model. Ang II-infused mice exhibited hypertension, cardiac hypertrophy, increases in blood urea nitrogen and serum creatinine, moderate albuminuria and renal pathological changes such as mild urinary cast, interstitial macrophage infiltration and modest interstitial fibrosis. RKT had no evident effects on the Ang II-induced renal functional insufficiency and fibrosis, but attenuated renal interstitial macrophage infiltration. In addition, RKT significantly restored the Ang II-induced alteration in the expression of renal fibrosis- and inflammation-related genes such as type 3 collagen, transforming growth factor-ß, monocyte chemoattractant protein-1 and interleukin-6. Furthermore, although RKT did not affect the expression of renal ghrelin receptor, an Ang II-induced decrease in renal sirtuin 1 expression, a critical down-stream pathway of the ghrelin receptor, was restored by RKT. These findings suggest that RKT potentially has a renal anti-inflammatory effect in the development of renal injury, and this effect could be mediated by the ghrelin signaling pathway.

Early Enhanced Leucine-Rich α-2-Glycoprotein-1 Expression in Glomerular Endothelial Cells of Type 2 Diabetic Nephropathy Model Mice.

Abnormal angiogenesis plays a major role in the development of early stage diabetic nephropathy. Vascular endothelial growth factor (VEGF) is a classical proangiogenic factor that regulates abnormal glomerular angiogenesis linked to glomerular hypertrophy in the early stage of diabetic nephropathy. Leucine-rich α-2-glycoprotein-1 (LRG1) was recently reported as a novel proangiogenic factor that is expressed in endothelial cells and promotes angiogenesis by modulating the transforming growth factor-ß signaling pathway. However, the pathophysiology of LRG1 in diabetic nephropathy remains largely unknown. In the present study, we investigated intrarenal expression of the novel proangiogenic factor LRG1 in diabetic db/db mice by immunohistochemistry and a laser capture microdissection method during the development of diabetic nephropathy. We hypothesized that glomerular LRG1 expression is increased earlier than VEGF expression under conditions of pathological angiogenesis in the early stage of diabetic nephropathy. Thus, we compared glomerular expression of VEGF and LRG1 in diabetic db/db mice at 16 and 24 weeks of age. At 16 weeks, diabetic db/db mice exhibited glomerular hypertrophy with abnormal angiogenesis characterized by endothelial cell proliferation, which was concomitant with an increase in LRG1 expression of glomerular endothelial cells. However, glomerular VEGF expression was not increased at this early stage. At 24 weeks, the features of early diabetic nephropathy in db/db mice had developed further, along with further enhanced glomerular LRG1 expression. At this late stage, glomerular VEGF and fibrosis-related-gene expression was also significantly increased compared with nondiabetic db/m mice. These results suggest that LRG1 plays a pivotal role in the initial development of diabetic nephropathy by promoting abnormal angiogenesis, thereby suggesting that LRG1 is a potential preemptive therapeutic target of diabetic nephropathy.

New non-invasive indexes of arterial stiffness are significantly correlated with severity and complexity of coronary atherosclerosis.

BACKGROUND: Endothelial dysfunction and increased arterial stiffness gradually develop before the manifestation of catastrophic cardiovascular events. Therefore, detection and assessment of vascular function are required to address pre-existing pathological conditions. However, the currently available diagnostic devices and methods are insufficient due to variability among investigators and the time-consuming nature of manual procedures. METHODS: Recently, novel devices were developed for the detection of both arterial stiffness and endothelial dysfunction in a single blood pressure measurement using a cuff-oscillometric technique (AVE-1500, Shisei Datum, Japan). API (arterial pressure volume index) is defined as the reciprocal of the slope of the tangent of the brachial artery pressure-volume curve, and AVI (arterial velocity pulse index) is defined as the ratio of the difference between the ejection and reflection waves. In the present study, we performed retrospective, cross-sectional analyses of subjects (n = 102; mean age = 70.5 ± 10.4 years) with detailed coronary angiographic examinations and clinical background parameters. RESULTS: After adjusting for various variables using multiple linear regression analyses, we found that API, but not AVI, was significantly correlated with coronary artery severity and complexity scores. CONCLUSIONS: We propose that API may be a new vascular index useful for monitoring and assessing the severity and complexity of atherosclerosis in subjects with coronary artery disease and for evaluating atherosclerotic diseases.

Angiotensin II Type 1 Receptor-associated Protein Inhibits Angiotensin II-induced Insulin Resistance with Suppression of Oxidative Stress in Skeletal Muscle Tissue.

Enhancement of AT1 receptor-associated protein (ATRAP) in adipose tissue improves high fat diet (HFD)-induced visceral obesity and insulin resistance, and suppresses adipose oxidative stress. However, HFD loading is not a direct stimulatory factor for AT1 receptor. In the present study, we investigated the effect of chronic, low-dose angiotensin II (Ang II) stimulation on glucose and lipid metabolism in mice and functional role of ATRAP. ATRAP expression was higher in adipose tissue (5-10-fold) and skeletal muscle tissue (approximately 1.6-fold) in ATRAP transgenic (TG) mice compared with wild-type (WT) mice. After Ang II infusion, insulin sensitivity was impaired in WT mice, but this response was suppressed in TG mice. Unexpectedly, Ang II infusion did not affect the adipose tissue profile in WT or TG mice. However, in skeletal muscle tissue, Ang II stimulus caused an increase in oxidative stress and activation of p38 MAPK, resulting in a decrease in glucose transporter type 4 expression in WT mice. These responses were suppressed in TG mice. Our study suggests that Ang II-induced insulin resistance is suppressed by increased ATRAP expression in skeletal muscle tissue. Hyperactivity of AT1 receptor could be related to formation of insulin resistance related to metabolic syndrome.