miR-125a-5p/miR-125b-5p contributes to pathological activation of angiotensin II-AT1R in mouse distal convoluted tubule cells by the suppression of Atrap.

The renin-angiotensin system plays a crucial role in the regulation of blood pressure. Activation of the angiotensin II (Ang II)-Ang II type 1 receptor (AT1R) signaling pathway contributes to the pathogenesis of hypertension and subsequent organ damage. AT1R-associated protein (ATRAP) has been identified as an endogenous inhibitory protein of the AT1R pathological activation. We have shown that mouse Atrap (Atrap) represses various Ang II-AT1R-mediated pathologies, including hypertension in mice. The expression of human ATRAP (ATRAP)/Atrap can be altered in various pathological states in humans and mice, such as Ang II stimulation and serum starvation. However, the regulatory mechanisms of ATRAP/Atrap are not yet fully elucidated. miRNAs are 21 to 23 nucleotides of small RNAs that post-transcriptionally repress gene expression. Single miRNA can act on hundreds of target mRNAs, and numerous miRNAs have been identified as the Ang II-AT1R signaling-associated disease phenotype modulator, but nothing is known about the regulation of ATRAP/Atrap. In the present study, we identified miR-125a-5p/miR-125b-5p as the evolutionarily conserved miRNAs that potentially act on ATRAP/Atrap mRNA. Further analysis revealed that miR-125a-5p/miR-125b-5p can directly repress both ATRAP and Atrap. In addition, the inhibition of miR-125a-5p/miR-125b-5p resulted in the suppression of the Ang II-AT1R signaling in mouse distal convoluted tubule cells. Taken together, miR-125a-5p/miR-125b-5p activates Ang II-AT1R signaling by the suppression of ATRAP/Atrap. Our results provide new insights into the potential approaches for achieving the organ-protective effects by the repression of the miR-125 family associated with the enhancement of ATRAP/Atrap expression.

Effect of tirzepatide on glycaemic control and weight loss compared with other glucagon-like peptide-1 receptor agonists in Japanese patients with type 2 diabetes mellitus.

AIM: To compare the therapeutic effects of glucose-dependent insulinotropic polypeptide (GIP)/ glucagon-like peptide-1 receptor agonists (GLP-1RAs) or GLP-1RAs in Japanese patients with type 2 diabetes (T2D). MATERIALS AND METHODS: We systematically searched PubMed, MEDLINE, EMBASE, and the Cochrane Library up to July 2023. Randomized controlled trials (RCTs) that compared GLP-1RAs or GIP/GLP-1RAs in Japanese patients with T2D were selected. A network meta-analysis was conducted to indirectly compare the treatments, focusing on efficacy in reducing glycated haemoglobin (HbA1c) levels and body weight (BW). RESULTS: A total of 18 RCTs were included in this analysis. Tirzepatide 15 mg showed the most significant reduction in HbA1c levels and BW compared with subcutaneous semaglutide 1.0 mg and oral semaglutide 14 mg (HbA1c: mean difference [95% confidence interval] -0.52 [-0.96; -0.08] and - 1.23 [-1.64; -0.81]; BW: -5.07 [-8.28; -1.86] and -6.84 [-8.97; -4.71], respectively). Subcutaneous semaglutide showed a superior reduction in HbA1c compared with oral semaglutide. Both subcutaneous and oral semaglutide were more effective than conventional GLP-1RAs, such as dulaglutide, liraglutide and lixisenatide. CONCLUSIONS: Among Japanese patients with T2D, tirzepatide showed the greatest effectiveness in reducing HbA1c levels and inducing weight loss. The study provides evidence to guide GLP-1RA treatment strategies in Japanese patients with T2D.

Abnormal lactate metabolism is linked to albuminuria and kidney injury in diabetic nephropathy.

Diabetic nephropathy (DN) is characterized by abnormal kidney energy metabolism, but its causes and contributions to DN pathogenesis are not clear. To examine this issue, we carried out targeted metabolomics profiling in a mouse model of DN that develops kidney disease resembling the human disorder. We found a distinct profile of increased lactate levels and impaired energy metabolism in kidneys of mice with DN, and treatment with an angiotensin-receptor blocker (ARB) reduced albuminuria, attenuated kidney pathology and corrected many metabolic abnormalities, restoring levels of lactate toward normal while increasing kidney ATP content. We also found enhanced expression of lactate dehydrogenase isoforms in DN. Expression of both the LdhA and LdhB isoforms were significantly increased in kidneys of mice, and treatment with ARB significantly reduced their expression. Single-cell sequencing studies showed specific up-regulation of LdhA in the proximal tubule, along with enhanced expression of oxidative stress pathways. There was a significant correlation between albuminuria and lactate in mice, and also in a Southeast Asian patient cohort consisting of individuals with type 2 diabetes and impaired kidney function. In the individuals with diabetes, this association was independent of ARB and angiotensin-converting enzyme inhibitor use. Furthermore, urinary lactate levels predicted the clinical outcomes of doubling of serum creatinine or development of kidney failure, and there was a significant correlation between urinary lactate levels and biomarkers of tubular injury and epithelial stress. Thus, we suggest that kidney metabolic disruptions leading to enhanced generation of lactate contribute to the pathogenesis of DN and increased urinary lactate levels may be a potential biomarker for risk of kidney disease progression.

Effects of sodium-glucose cotransporter 2 inhibitors, mineralocorticoid receptor antagonists, and their combination on albuminuria in diabetic patients.

AIMS: Diabetes mellitus (DM) is the leading cause of chronic kidney disease. Albuminuria is associated with an increased risk of cardiovascular mortality. Sodium-glucose cotransporter 2 inhibitors (SGLT2-Is) and mineralocorticoid receptor antagonists (MRAs) protect against albuminuria; however, their combined effects on albuminuria are unclear. We performed a network meta-analysis to investigate the effects of SGLT2-Is, MRAs and their combination on albuminuria in type 2 DM. METHODS: We systematically searched PubMed, Medline, EMBASE and the Cochrane Library from inception up to 20 November 2022. We selected randomized control and crossover trials that compared MRAs, SGLT2-Is, MRAs + SGLT2-Is, or a placebo in patients with type 2 DM with a urinary albumin-creatinine ratio (UACR) ≥30 mg/g creatinine. The primary outcome was the change in the UACR. RESULTS: This meta-analysis analysed 17 studies with 34 412 patients. The use of combination treatment with SGLT2-Is and MRAs was associated with lower albuminuria compared with the use of SGLT2-Is, MRAs, or the placebo alone [mean difference (95% CI): -34.19 (-27.30; -41.08), -32.25 (-24.53; -39.97) and -65.22 (-57.97; -72.47), respectively]. Treatment with SGLT2-Is or MRAs alone caused a significant reduction in UACR compared with the placebo [mean difference (95% CI): -31.03 (-28.35; -33.72) and -32.97 (-29.68; -36.27), respectively]. The effects of MRAs on the UACR are comparable with those of SGLT2-Is. Sensitivity analyses showed similar results. CONCLUSION: Combination therapy with SGLT2-Is and MRAs was associated with lower albuminuria in patients with type 2 DM compared with monotherapy with SGLT2-Is or MRAs alone.

Blunted humoral immune response to the fourth dose of BNT162b2 COVID-19 vaccine in patients undergoing hemodialysis.

BACKGROUND: We aimed to investigate the impact of a fourth dose of BNT162b2 vaccine (Comirnaty®, Pfizer-BioNTech) on anti-SARS-CoV-2 (anti-S IgG) antibody titers in patients receiving hemodialysis (HD) and healthcare workers (HCWs). METHODS: A multi-institutional retrospective study at five dialysis clinics in Japan was conducted using 238 HD patients and 58 HCW controls who received four doses of the BNT162b2 mRNA vaccine. Anti-S IgG titers were measured at 1, 3, and 6 months after the second dose, at 1 and 5/6 months after the third dose, and at 1 month after the fourth dose of vaccine. RESULTS: The log anti-S IgG titers of the HD patients after the second vaccination were significantly lower than those of the control group, but equalized 1 month after the third vaccination: 9.94 (95% CI 9.82-10.10) vs. 9.81 (95% CI 9.66-9.96), (P = 0.32). In both groups, the fold-increase in anti-S IgG titers was significantly lower after the fourth dose than after the third dose of vaccine. In addition, there was a strong negative correlation between antibody titers 1 month after the fourth vaccination and antibody titers immediately before the vaccination. In both groups, the waning rate of anti-S IgG titers from the post-vaccination peak level after the third vaccine dose was significantly slower than that after the second dose. CONCLUSIONS: These findings suggest that the humoral immune response was blunted after the fourth dose of the conventional BNT162b2 vaccine. However, multiple vaccinations could extend the window of humoral immune protection.

Effects of a High-Protein Diet on Kidney Injury under Conditions of Non-CKD or CKD in Mice.

Considering the prevalence of obesity and global aging, the consumption of a high-protein diet (HPD) may be advantageous. However, an HPD aggravates kidney dysfunction in patients with chronic kidney disease (CKD). Moreover, the effects of an HPD on kidney function in healthy individuals are controversial. In this study, we employed a remnant kidney mouse model as a CKD model and aimed to evaluate the effects of an HPD on kidney injury under conditions of non-CKD and CKD. Mice were divided into four groups: a sham surgery (sham) + normal diet (ND) group, a sham + HPD group, a 5/6 nephrectomy (Nx) + ND group and a 5/6 Nx + HPD group. Blood pressure, kidney function and kidney tissue injury were compared after 12 weeks of diet loading among the four groups. The 5/6 Nx groups displayed blood pressure elevation, kidney function decline, glomerular injury and tubular injury compared with the sham groups. Furthermore, an HPD exacerbated glomerular injury only in the 5/6 Nx group; however, an HPD did not cause kidney injury in the sham group. Clinical application of these results suggests that patients with CKD should follow a protein-restricted diet to prevent the exacerbation of kidney injury, while healthy individuals can maintain an HPD without worrying about the adverse effects.

Deficiency of the kidney tubular angiotensin II type1 receptor-associated protein ATRAP exacerbates streptozotocin-induced diabetic glomerular injury via reducing protective macrophage polarization.

Although activation of the renin-angiotensin system and of its glomerular components is implicated in the pathogenesis of diabetic nephropathy, the functional roles of the tubular renin-angiotensin system with AT1 receptor signaling in diabetic nephropathy are unclear. Tissue hyperactivity of the renin-angiotensin system is inhibited by the angiotensin II type 1 receptor-associated protein ATRAP, which negatively regulates receptor signaling. The highest expression of endogenous ATRAP occurs in the kidney, where it is mainly expressed by tubules but rarely in glomeruli. Here, we found that hyperactivation of angiotensin II type 1 receptor signaling in kidney tubules exacerbated diabetic glomerular injury in a mouse model of streptozotocin-induced diabetic nephropathy. These phenomena were accompanied by decreased expression of CD206, a marker of alternatively activated and tissue-reparative M2 macrophages, in the kidney tubulointerstitium. Additionally, adoptive transfer of M2- polarized macrophages into diabetic ATRAP-knockout mice ameliorated the glomerular injury. As a possible mechanism, the glomerular mRNA levels of tumor necrosis factor-α and oxidative stress components were increased in diabetic knockout mice compared to non-diabetic knockout mice, but these increases were ameliorated by adoptive transfer. Furthermore, proximal tubule-specific ATRAP downregulation reduced tubulointerstitial expression of CD206, the marker of M2 macrophages in diabetic mice. Thus, our findings indicate that tubular ATRAP-mediated functional modulation of angiotensin II type 1 receptor signaling modulates the accumulation of tubulointerstitial M2 macrophages, thus affecting glomerular manifestations of diabetic nephropathy via tubule-glomerular crosstalk.

SARS-CoV-2 spike protein antibody titers 6 months after SARS-CoV-2 mRNA vaccination among patients undergoing hemodialysis in Japan.

BACKGROUND: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccination is shown to prevent severe illness and death in hemodialysis (HD) patients, but the immune response to vaccines is reduced in this population. This study compared SARS-CoV-2 spike protein antibody titers between HD patients and healthy controls in Japan for up to 6 months following vaccination. METHODS: A multi-institutional retrospective study at five clinics in Japan was conducted using 412 HD patients and 156 healthy controls who received two doses of the BNT162b2 (Pfizer-BioNTech) mRNA vaccine. Anti-SARS-CoV-2 spike protein S1 IgG antibody titers were measured at 1, 3, and 6 months after the second dose. The attenuation speed was calculated as slope (i.e., -ß) using a linear mixed-effects model toward the log-transformed antibody titers. RESULTS: The HD group had significantly lower month 1 antibody titers (Ab-titer-1) than the controls, and these remained lower through month 6 (95% CI: 2617.1 (1296.7, 5240.8) vs. 7285.4 (4403.9, 11,000.0) AU/mL at Ab-titer-1, and 353.4 (178.4, 656.3) vs. 812.0 (498.3, 1342.7) AU/mL at Ab-titer-6 (p < 0.001, respectively)). Lower log Ab-titer-1 levels in the HD group were significantly associated with a lower log Ab-titer-6 (0.90 [0.83, 0.97], p < 0.001). The -ß values in the HD patients and healthy controls were -4.7 ± 1.1 and -4.7 ± 1.4 (year-1), respectively. CONCLUSION: SARS-CoV-2 spike protein antibody titers were significantly lower in HD patients than in healthy controls at 1 (peak) and 6 months after the second vaccination. Low peak antibody titers contributed to low 6-month antibody titers.

Cardiovascular and renal outcomes with SGLT-2 inhibitors versus GLP-1 receptor agonists in patients with type 2 diabetes mellitus and chronic kidney disease: a systematic review and network meta-analysis.

BACKGROUND: Emerging evidence suggests that sodium-glucose cotransporter-2 (SGLT-2) inhibitors and glucagon-like peptide-1 receptor agonists (GLP-1 RAs) are associated with decreased risk of cardiovascular and renal events in type 2 diabetes mellitus (DM) patients. However, no study to date has compared the effect of SGLT-2 inhibitors with that of GLP-1 RAs in type 2 DM patients with chronic kidney disease (CKD). We herein investigated the benefits of SGLT-2 inhibitors and GLP-1 RAs in CKD patients. METHODS: We performed a systematic literature search through November 2020. We selected randomized control trials that compared the risk of major adverse cardiovascular events (MACE) and a composite of renal outcomes. We performed a network meta-analysis to compare SGLT-2 inhibitors with GLP-1 RAs indirectly. Risk ratios (RRs) with corresponding 95% confidence intervals (CI) were synthesized. RESULTS: Thirteen studies were selected with a total of 32,949 patients. SGLT-2 inhibitors led to a risk reduction in MACE and renal events (RR [95% CI]; 0.85 [0.75-0.96] and 0.68 [0.59-0.78], respectively). However, GLP-1 RAs did not reduce the risk of cardiovascular or renal adverse events (RR 0.91 [0.80-1.04] and 0.86 [0.72-1.03], respectively). Compared to GLP-1 RAs, SGLT-2 inhibitors did not demonstrate a significant difference in MACE (RR 0.94 [0.78-1.12]), while SGLT-2 inhibitors were associated with a lower risk of renal events compared to GLP-1 RAs (RR 0.79 [0.63-0.99]). A sensitivity analysis revealed that GLP-1 analogues significantly decreased MACE when compared to placebo treatment (RR 0.81 [0.69-0.95]), while exendin-4 analogues did not (RR 1.03 [0.88-1.20]). CONCLUSIONS: In patients with type 2 DM and CKD, SGLT-2 inhibitors were associated with a decreased risk of cardiovascular and renal events, but GLP-1 RAs were not. SGLT-2 inhibitors significantly decreased the risk of renal events compared to GLP-1 RAs. Among GLP-1 RAs, GLP-1 analogues showed a positive impact on cardiovascular and renal outcomes, while exendin-4 analogues did not.

Potential effective treatment of shortening continuous erythropoietin receptor activator treatment interval combined with iron supplementation in hemodialysis patients.

Our previous randomized controlled trial comparing the total dose of weekly versus biweekly continuous erythropoietin receptor activator (CERA) therapy to maintain optimal hemoglobin (Hb) levels showed no significant differences between the two therapies. This post-hoc analysis assessed whether the total dose of weekly versus biweekly CERA therapy to maintain Hb levels among HD patients differed among groups with or without iron supplementation. Of 107 patients, 40 received intravenous iron supplementation due to iron deficiency (iron group) and 67 did not (non-iron group). In the iron group, the weekly therapy tended to require a lower total CERA dose compared with the biweekly therapy (274 ± 274 vs 381 ± 223 µg/12 weeks, P = 0.051). Changes in circulating hepcidin levels, a negative regulator of intestinal iron uptake, after 2 weeks of CERA treatment were significantly lower in the weekly therapy compared with the biweekly therapy (-4.2 ± 6.3 vs 11.1 ± 7.3 ng/mL, P = 0.015). In the non-iron group, there were no significant differences in total CERA dose or changes in hepcidin levels between the two therapies. Shortening the CERA treatment interval combined with iron supplementation may lead to the more efficient treatment of HD patients with iron deficiency.

Blood Pressure Elevation of Tubular Specific (P)RR Transgenic Mice and Lethal Tubular Degeneration due to Possible Intracellular Interactions between (P)RR and Alternative Renin Products.

The prorenin/renin receptor ((P)RR) is a multifunctional protein that is widely distributed in various organs. Despite intensive research for more than 20 years, this receptor has not been fully characterized. In this study, we generated mice overexpressing the tubular epithelial (P)RR gene ((P)RR-TG mice) to test the previously reported functional role of (P)RR by Ramkumar et al. in 2015 using tubular specific (P)RR KO mice. (P)RR-TG mice were maintained and analyzed in individual metabolic cages and were administered angiotensin II blocker (ARB), direct renin inhibitor (DRI), and bafilomycin, that is, vacuolar ATPase (V-ATPase) antagonist. (P)RR-TG mice were hypertensive and had alkalized urine with lower osmolality and Na+ excretion. ARB and DRI, but not bafilomycin, concurrently decreased blood pressure. Bafilomycin acidized urine of (P)RR-TG mice, or equivalently this phenomenon restored the effect of overexpressed transgene, suggesting that (P)RR functioned as a V-ATPase in renal tubules. Afterall, (P)RR-TG mice were mated with alternative renin transgenic mice (ARen2-TG), which we identified as intracellular renin previously, to generate double transgenic mice (DT-TG). Lethal renal tubular damage was observed in DT-TG mice, suggesting that intracellular renin may be a ligand for (P)RR in tubules. In summary, (P)RR did not substantially affect the tissue renin-angiotensin system (RAS) in our model of tubular specific (P)RR gene over-expression, but alternative intracellular renin may be involved in (P)RR signaling in addition to conventional V-ATPase function. Further investigations are warranted.

Aristolochic Acid Induces Renal Fibrosis and Senescence in Mice.

The kidney is one of the most susceptible organs to age-related impairments. Generally, renal aging is accompanied by renal fibrosis, which is the final common pathway of chronic kidney diseases. Aristolochic acid (AA), a nephrotoxic agent, causes AA nephropathy (AAN), which is characterized by progressive renal fibrosis and functional decline. Although renal fibrosis is associated with renal aging, whether AA induces renal aging remains unclear. The aim of the present study is to investigate the potential use of AAN as a model of renal aging. Here, we examined senescence-related factors in AAN models by chronically administering AA to C57BL/6 mice. Compared with controls, the AA group demonstrated aging kidney phenotypes, such as renal atrophy, renal functional decline, and tubulointerstitial fibrosis. Additionally, AA promoted cellular senescence specifically in the kidneys, and increased renal p16 mRNA expression and senescence-associated ß-galactosidase activity. Furthermore, AA-treated mice exhibited proximal tubular mitochondrial abnormalities, as well as reactive oxygen species accumulation. Klotho, an antiaging gene, was also significantly decreased in the kidneys of AA-treated mice. Collectively, the results of the present study indicate that AA alters senescence-related factors, and that renal fibrosis is closely related to renal aging.

Recent Research Advances in Renin-Angiotensin-Aldosterone System Receptors.

PURPOSE OF REVIEW: The renin-angiotensin-aldosterone system (RAAS) plays important roles in regulating blood pressure and body fluid, which contributes to the pathophysiology of hypertension and cardiovascular/renal diseases. However, accumulating evidence has further revealed the complexity of this signal transduction system, including direct interactions with other receptors and proteins. This review focuses on recent research advances in RAAS with an emphasis on its receptors. RECENT FINDINGS: Both systemically and locally produced angiotensin II (Ang II) bind to Ang II type 1 receptor (AT1R) and elicit strong biological functions. Recent studies have shown that Ang II-induced activation of Ang II type 2 receptor (AT2R) elicits the opposite functions to those of AT1R. However, accumulating evidence has now expanded the components of RAAS, including (pro)renin receptor, angiotensin-converting enzyme 2, angiotensin 1-7, and Mas receptor. In addition, the signal transductions of AT1R and AT2R are regulated by not only Ang II but also its receptor-associated proteins such as AT1R-associated protein and AT2R-interacting protein. Recent studies have indicated that inappropriate activation of local mineralocorticoid receptor contributes to cardiovascular and renal tissue injuries through aldosterone-dependent and -independent mechanisms. Since the mechanisms of RAAS signal transduction still remain to be elucidated, further investigations are necessary to explore novel molecular mechanisms of the RAAS, which will provide alternative therapeutic agents other than existing RAAS blockers.

Effect of renin-angiotensin system blockers on contrast-induced acute kidney injury in patients with normal or mild-to-moderate reduced kidney function undergoing coronary angiography: A systematic review and meta-analysis.

INTRODUCTION: Contrast-induced acute kidney injury (CI-AKI) is a major complication after coronary angiography (CAG) or percutaneous coronary intervention (PCI) and is associated with increased morbidity and mortality. It remains controversial whether renin-angiotensin system (RAS) blockers increase or decrease CI-AKI. In this meta-analysis, we investigated the association between RAS blockers and CI-AKI in patients with normal kidney function or mild-to-moderate chronic kidney disease (CKD). MATERIALS AND METHODS: We performed a systematic search of PubMed, EMBASE, clinicaltrials.gov, and the Cochrane Library up to December 2019 for studies that assessed the association between RAS blockers and CI-AKI events after CAG/PCI. The primary outcome was the development of CI-AKI. Odds ratios (ORs) with corresponding 95% confidence interval (CI) were synthesized. RESULTS: Five randomized controlled trials (RCTs) and five observational studies were included, accounting for a total of 7,420 patients. Unstratified, RAS blocker administration was significantly associated with an increased risk of CI-AKI (pooled OR = 1.63, 95% CI 1.19 - 2.25, p = 0.003). However, the effect was not observed in RCTs (pooled OR = 1.22, 95% CI 0.54 - 2.74, p = 0.63). Sensitivity analysis in observational studies showed significant association (pooled OR = 1.77, 95% CI 1.22 - 2.55, p = 0.003) with high heterogeneity and evidence of publication bias. CONCLUSION: In patients with relatively-preserved renal function, the association of RAS blockers with an increased risk of CI-AKI after contrast media exposure was inconclusive, as sensitivity analysis showed conflicting results and bias. Although this study did not demonstrate significant evidence, it indicated that clinicians need to be vigilant in assessing the potential risk for RAS blockers to cause CI-AKI in low-risk patients.

Improved home BP profile with dapagliflozin is associated with amelioration of albuminuria in Japanese patients with diabetic nephropathy: the Yokohama add-on inhibitory efficacy of dapagliflozin on albuminuria in Japanese patients with type 2 diabetes study (Y-AIDA study).

BACKGROUND: The Y-AIDA study was designed to investigate the renal- and home blood pressure (BP)-modulating effects of add-on dapagliflozin treatment in Japanese individuals with type 2 diabetes mellitus (T2DM) and albuminuria. METHODS: We conducted a prospective, multicenter, single-arm study. Eighty-six patients with T2DM, HbA1c 7.0-10.0%, estimated glomerular filtration rate (eGFR) ≥ 45 mL/min/1.73 m2, and urine albumin-to-creatinine ratio (UACR) ≥ 30 mg/g creatinine (gCr) were enrolled, and 85 of these patients were administered add-on dapagliflozin for 24 weeks. The primary and key secondary endpoints were change from baseline in the natural logarithm of UACR over 24 weeks and change in home BP profile at week 24. RESULTS: Baseline median UACR was 181.5 mg/gCr (interquartile range 47.85, 638.0). Baseline morning, evening, and nocturnal home systolic/diastolic BP was 137.6/82.7 mmHg, 136.1/79.3 mmHg, and 125.4/74.1 mmHg, respectively. After 24 weeks, the logarithm of UACR decreased by 0.37 ± 0.73 (P < 0.001). In addition, changes in morning, evening, and nocturnal home BP from baseline were as follows: morning systolic/diastolic BP - 8.32 ± 11.42/- 4.18 ± 5.91 mmHg (both P < 0.001), evening systolic/diastolic BP - 9.57 ± 12.08/- 4.48 ± 6.45 mmHg (both P < 0.001), and nocturnal systolic/diastolic BP - 2.38 ± 7.82/- 1.17 ± 5.39 mmHg (P = 0.0079 for systolic BP, P = 0.0415 for diastolic BP). Furthermore, the reduction in UACR after 24 weeks significantly correlated with an improvement in home BP profile, but not with changes in other variables, including office BP. Multivariate linear regression analysis also revealed that the change in morning home systolic BP was a significant contributor to the change in log-UACR. CONCLUSIONS: In Japanese patients with T2DM and diabetic nephropathy, dapagliflozin significantly improved albuminuria levels and the home BP profile. Improved morning home systolic BP was associated with albuminuria reduction. Trial registration The study is registered at the UMIN Clinical Trials Registry (UMIN000018930; http://www.umin.ac.jp/ctr/index-j.htm ). The study was conducted from July 1, 2015 to August 1, 2018.

An angiotensin II type 1 receptor binding molecule has a critical role in hypertension in a chronic kidney disease model.

Angiotensin II type 1 receptor-associated protein (ATRAP) promotes AT1R internalization along with suppression of hyperactivation of tissue AT1R signaling. Here, we provide evidence that renal ATRAP plays a critical role in suppressing hypertension in a mouse remnant kidney model of chronic kidney disease. The effect of 5/6 nephrectomy on endogenous ATRAP expression was examined in the kidney of C57BL/6 and 129/Sv mice. While 129/Sv mice with a remnant kidney showed decreased renal ATRAP expression and developed hypertension, C57BL/6 mice exhibited increased renal ATRAP expression and resistance to progressive hypertension. Consequently, we hypothesized that downregulation of renal ATRAP expression is involved in pathogenesis of hypertension in the remnant kidney model of chronic kidney disease. Interestingly, 5/6 nephrectomy in ATRAP-knockout mice on the hypertension-resistant C57BL/6 background caused hypertension with increased plasma volume. Moreover, in knockout compared to wild-type C57BL/6 mice after 5/6 nephrectomy, renal expression of the epithelial sodium channel α-subunit and tumor necrosis factor-α was significantly enhanced, concomitant with increased plasma membrane angiotensin II type 1 receptor in the kidneys. Thus, renal ATRAP downregulation is involved in the onset and progression of blood pressure elevation caused by renal mass reduction, and implicates ATRAP as a therapeutic target for hypertension in chronic kidney disease.

Within-visit blood pressure variability and cardiovascular risk factors in hypertensive patients with non-dialysis chronic kidney disease.

As there may be an association between within-visit blood pressure (BP) variability and cardiovascular disease (CVD), we investigated the clinical significance of this BP variability in non-dialysis chronic kidney disease (CKD) patients. MATERIALS AND METHODS: According to the median of coefficient of variation (CV) of three systolic BP (SBP) readings within a single visit, we divided hypertensive patients with stage G1-4 CKD already treated with antihypertensive therapy into the high SBP-CV group and the low SBP-CV group. Univariate and multivariate linear regression analyses were also performed to explore the contributing factors to within-visit BP variability. RESULTS: In the high SBP-CV group, the clinic BP, total cholesterol level, dyslipidemia, and past history of CVD were significantly greater, while α1-blockers and renin-angiotensin system (RAS) inhibitors usage were significantly reduced compared with the lower SBP-CV group. Within-visit BP variability was significantly and positively correlated with total cholesterol (R = 0.392, P < 0.001) and low-density lipoprotein cholesterol (R = 0.284, P = 0.013). Total cholesterol (ß = 0.269, P = 0.024), α1-blockers usage (ß = -0.260, P = 0.015), and RAS inhibitors usage (ß = -0.266, P = 0.017) were shown to independently contribute to the within-visit BP variability after adjustment for age, sex, presence of diabetes, CVD history, statins usage, and clinic SBP. CONCLUSIONS: We show that within-visit BP variability may be a clinically relevant factor of CVD risk, and lipid lowering and/or anti-hypertensive therapies using RAS inhibitors and α1-blockers may be associated with the improved within-visit BP variability observed in non-dialysis CKD patients.

Eplerenone-Resistant Salt-Sensitive Hypertension in Nedd4-2 C2 KO Mice.

The epithelial sodium channel (ENaC) plays critical roles in maintaining fluid and electrolyte homeostasis and is located in the aldosterone-sensitive distal nephron (ASDN). We previously found that Nedd4-2 C2 knockout (KO) mice showed salt-sensitive hypertension with paradoxically enhanced ENaC gene expression in ASDN under high oral salt intake. Eplerenone (EPL), a selective aldosterone blocker, is a promising therapeutic option for resistant or/and salt-sensitive hypertension. We examined the effect of EPL on Nedd4-2 C2 KO mice with respect to blood pressure, metabolic parameters, and molecular level changes in ASDN under high oral salt intake. We found that EPL failed to reduce blood pressure in KO mice with high oral salt intake and upregulated ENaC expression in ASDN. Thus, salt-sensitive hypertension in Nedd4-2 C2 KO was EPL-resistant. Gene expression analyses of laser-captured specimens in ASDN suggested the presence of non-aldosterone-dependent activation of ENaC transcription in ASDN of Nedd4-2 C2 KO mice, which was abolished by amiloride treatment. Our results from Nedd4-2 C2 KO mice suggest that enhanced ENaC gene expression is critically involved in salt-sensitive hypertension under certain conditions of specific enzyme isoforms for their ubiquitination.

An Isoform of Nedd4-2 Plays a Pivotal Role in Electrophysiological Cardiac Abnormalities.

We have previously shown that neural precursor cell-expressed developmentally downregulated gene 4-2 (Nedd4-2) isoforms with a C2 domain are closely related to ubiquitination of epithelial sodium channel (ENaC), resulting in salt-sensitive hypertension by Nedd4-2 C2 targeting in mice. The sodium voltage-gated channel alpha subunit 5 (SCN5A) gene encodes the α subunit of the human cardiac voltage-gated sodium channel (I Na), and the potassium voltage-gated channel subfamily H member 2 (KCNH2) gene encodes rapidly activating delayed rectifier K channels (I Kr). Both ion channels have also been shown to bind to Nedd4-2 via a conserved Proline-Tyrosine (PY) motif in C-terminal with subsequent ubiquitination and degradation by proteasome. Therefore, loss of Nedd4-2 C2 isoform might be involved in electrophysiological impairment under various conditions. We demonstrate here that Nedd4-2 C2 isoform causes cardiac conduction change in resting condition as well as proarrhythmic change after acute myocardial infarction (MI). The Nedd4-2 C2 knockout (KO) mice showed bradycardia, prolonged QRS, QT intervals, and suppressed PR interval in resting condition. In addition, enhancement of T peak/T end interval was found in mice with surgical ligation of the distal left coronary artery. Morphological analyses based on both ultrasonography of the living heart, as well as histopathological findings revealed that Nedd4-2 C2 KO mice show no significant structural changes from wild-type littermates under resting conditions. These results suggested that Nedd4-2 with C2 domain might play an important role in cardio-renal syndrome through post-transcriptional modification of both ENaC and cardiac ion channels, which are critical for kidney and heart functions.

ATRAP Expression in Brown Adipose Tissue Does Not Influence the Development of Diet-Induced Metabolic Disorders in Mice.

Activation of tissue renin-angiotensin system (RAS), mainly mediated by an angiotensin II (Ang II) type 1 receptor (AT1R), plays an important role in the development of obesity-related metabolic disorders. We have shown that AT1R-associated protein (ATRAP), a specific binding protein of AT1R, functions as an endogenous inhibitor to prevent excessive activation of tissue RAS. In the present study, we newly generated ATRAP/Agtrap-floxed (ATRAPfl/fl) mice and adipose tissue-specific ATRAP downregulated (ATRAPadipoq) mice by the Cre/loxP system using Adipoq-Cre. Using these mice, we examined the functional role of adipose ATRAP in the pathogenesis of obesity-related metabolic disorders. Compared with ATRAPfl/fl mice, ATRAPadipoq mice exhibited a decreased ATRAP expression in visceral white adipose tissue (WAT) and brown adipose tissue (BAT) by approximately 30% and 85%, respectively. When mice were fed a high-fat diet, ATRAPfl/fl mice showed decreased endogenous ATRAP expression in WAT that was equivalent to ATRAPadipoq mice, and there was no difference in the exacerbation of dietary obesity and glucose and lipid metabolism. These results indicate that ATRAP in BAT does not influence the pathogenesis of dietary obesity or metabolic disorders. Future studies that modulate ATRAP in WAT are necessary to assess its in vivo functions in the development of obesity-related metabolic disorders.