Evaluation of glomerular hemodynamic changes by sodium-glucose-transporter 2 inhibition in type 2 diabetic rats using in vivo imaging.

The mechanisms responsible for glomerular hemodynamic regulation with sodium-glucose co-transporter 2 (SGLT2) inhibitors in kidney disease due to type 2 diabetes remain unclear. Therefore, we investigated changes in glomerular hemodynamic function using an animal model of type 2 diabetes, treated with an SGLT2 inhibitor alone or in combination with a renin-angiotensin-aldosterone system inhibitor using male Zucker lean (ZL) and Zucker diabetic fatty (ZDF) rats. Afferent and efferent arteriolar diameter and single-nephron glomerular filtration rate (SNGFR) were evaluated in ZDF rats measured at 0, 30, 60, 90, and 120 minutes after the administration of a SGLT2 inhibitor (luseogliflozin). Additionally, we assessed these changes under the administration of the adenosine A1 receptor (A1aR) antagonist (8-cyclopentyl-1,3-dipropylxanthine), along with coadministration of luseogliflozin and an angiotensin II receptor blocker (ARB), telmisartan. ZDF rats had significantly increased SNGFR, and afferent and efferent arteriolar diameters compared to ZL rats, indicating glomerular hyperfiltration. Administration of luseogliflozin significantly reduced afferent vasodilatation and glomerular hyperfiltration, with no impact on efferent arteriolar diameter. Urinary adenosine levels were increased significantly in the SGLT2 inhibitor group compared to the vehicle group. A1aR antagonism blocked the effect of luseogliflozin on kidney function. Co-administration of the SGLT2 inhibitor and ARB decreased the abnormal expansion of glomerular afferent arterioles, whereas the efferent arteriolar diameter was not affected. Thus, regulation of afferent arteriolar vascular tone via the A1aR pathway is associated with glomerular hyperfiltration in type 2 diabetic kidney disease.

Effects of Beraprost on Intestinal Microcirculation and Barrier Function in a Mouse Model of Renal Failure.

OBJECTIVE: Endothelial dysfunction plays an important role in the pathogenesis of chronic kidney disease. Prostacyclin (PGI2), an endothelial cell-produced endogenous prostaglandin, plays a crucial role in maintaining endothelial function. However, its effects on intestinal microcirculation and barrier function are not fully understood. We hypothesized that PGI2 improves intestinal microcirculation and barrier function via endothelial protective effects. METHODS: ICR and ICGN (a spontaneous nephrotic model) mice were used in this study. Intestinal microcirculation was visualized in vivo to investigate PGI2 effects. Beraprost served as PGI2. PGI2 administration spanned 4 weeks, following which we assessed its influence on intestinal endothelial, intestinal barrier, and renal functions. RESULTS: We visualized intestinal microcirculation and endothelial glycocalyx in the intestinal blood vessels. Beraprost administration induced a 1.2-fold dilatation of the vascular diameter of the small intestine. Intestinal blood flow in ICGN mice was significantly reduced compared that in ICR mice but improved with beraprost administration. ICGN mice exhibited reduced serum albumin levels, decreased ambulation, an imbalance in intestinal reactive oxygen species (ROS)/nitric oxide (NO), and impaired tight junctions; all were ameliorated by beraprost administration. CONCLUSIONS: Beraprost improves intestinal microcirculation and barrier function by ameliorating ROS/NO imbalances, thereby reducing physical inactivity during renal failure.

Activation of the inflammasome drives peritoneal deterioration in a mouse model of peritoneal fibrosis.

During peritoneal dialysis (PD), the peritoneum is exposed to a bioincompatible dialysate, deteriorating the tissue and limiting the long-term effectiveness of PD. Peritoneal fibrosis is triggered by chronic inflammation induced by a variety of stimuli, including peritonitis. Exposure to PD fluid alters peritoneal macrophages phenotype. Inflammasome activation triggers chronic inflammation. First, it was determined whether inflammasome activation causes peritoneal deterioration. In the in vivo experiments, the increased expression of the inflammasome components, caspase-1 activity, and concomitant overproduction of IL-1ß and IL-18 were observed in a mouse model of peritoneal fibrosis. ASC-positive and F4/80-positive cells colocalized in the subperitoneal mesothelial cell layer. These macrophages expressed high CD44 levels indicating that the CD44-positive macrophages contribute to developing peritoneal deterioration. Furthermore, intravital imaging of the peritoneal microvasculature demonstrated that the circulating CD44-positive leukocytes may contribute to peritoneal fibrosis. Bone marrow transplantation in ASC-deficient mice suppressed inflammasome activation, thereby attenuating peritoneal fibrosis in a high glucose-based PD solution-injected mouse model. Our results suggest inflammasome activation in CD44-positive macrophages may be involved in developing peritoneal fibrosis. The inflammasome-derived pro-inflammatory cytokines might therefore serve as new biomarkers for developing encapsulating peritoneal sclerosis.

Factors affecting the sodium-glucose cotransporter 2 inhibitors-related initial decline in glomerular filtration rate and its possible effect on kidney outcome in chronic kidney disease with type 2 diabetes: The Japan Chronic Kidney Disease Database.

AIM: Sodium-glucose cotransporter 2 (SGLT2) inhibitors often cause a transient decrease in glomerular filtration rate (GFR) shortly after the initiation, referred to as the 'initial drop'. However, the clinical significance of this initial drop in real-world practice remains unclear. MATERIALS AND METHODS: Using the nationwide Japan Chronic Kidney Disease Database, we examined factors that affected the initial drop, in patients with chronic kidney disease (CKD) and type 2 diabetes mellitus (T2DM). We also evaluated the effects of the initial drop on a composite kidney outcome (a decline in GFR of ≥50% or progression to end-stage kidney disease). RESULTS: Data from 2053 patients with CKD and T2DM newly prescribed an SGLT2 inhibitor were analysed. The follow-up period after SGLT2 inhibitor administration was 1015 days (interquartile range: 532, 1678). Multivariate linear regression models revealed that the concomitant use of the renin-angiotensin system inhibitors and diuretics, urinary protein levels ≥2+, and changes in GFR before the initiation of the SGLT2 inhibitor were associated with a larger initial GFR decline (ß = -0.609, p = .039; ß = -2.298, p < .001; ß = -0.936, p = .048; ß = -0.079, p < .001, respectively). Patients in the quartile with the largest initial GFR decline experienced a higher incidence of the subsequent composite kidney outcome than those in the other quartiles (p < .001). CONCLUSIONS: The concomitant use of renin-angiotensin system inhibitors and diuretics, higher urine protein levels and pre-treatment GFR changes were associated with a larger initial GFR decline. Of these factors, the use of a diuretic had the largest effect. Furthermore, patients with CKD and T2DM experiencing an excessive initial GFR drop might be at a higher risk of adverse kidney outcomes.

A case series of Fabry diseases with CKD in Japan.

BACKGROUND: It is well known that kidney injury is vital organ damage in Fabry disease (FD). Renin-angiotensin system (RAS) inhibitors are known to reduce proteinuria in patients with chronic kidney disease (CKD) by dilating the glomerular export arteries and reducing intraglomerular pressure. This improvement in intraglomerular pressure, although lowering the glomerular filtration rate, is thought to prevent renal damage and be renoprotective in the long term. RAS inhibitors may be effective in FD patients with proteinuria to prevent the progression of kidney disease, however, the degree to which they are used in clinical practice is unknown. METHODS: The J-CKD-DB-Ex is a comprehensive multicenter database that automatically extracts medical data on CKD patients. J-CKD-DB-Ex contains data on 187,398 patients in five medical centers. FD patients were identified by ICD-10. Clinical data and prescriptions of FD patients between January 1 of 2014, and December 31 of 2020 were used for the analysis. RESULTS: We identified 39 patients with FD from the J-CKD-DB-Ex including those with suspected FD. We confirmed 22 patients as FD. Half of the patients received RAS inhibitors. RAS inhibitors tended to be used in CKD patients with more severe renal impairment. CONCLUSIONS: This case series revealed the actual clinical practice of FD patients with CKD. In particular, we found cases in which patients had proteinuria, but were not treated with RAS inhibitors. The database was shown to be useful in assessing the clinical patterns of patients with rare diseases.

Association of serum magnesium levels with renal prognosis in patients with chronic kidney disease.

BACKGROUND: Magnesium deficiency is associated with various health conditions, but its impact on the progression of chronic kidney disease (CKD) remains unclear. This study aimed to investigate the association between serum magnesium levels and prognosis of renal function in CKD patients. METHODS: This is an analysis of the Japan Chronic Kidney Disease Database Ex　(J-CKD-DB-Ex), which is a multicenter prospective cohort including CKD patients enrolled from January 1, 2014 to December 31, 2020. We included adult outpatients with CKD stage G3 and G4 at the time of initial magnesium measurement. Patients were classified by magnesium levels as low (<1.7 mg/dl), normal (1.7-2.6 mg/dl), or high (>2.6 mg/dl). The primary outcomes were the composite of an eGFR < 15 ml/min/1.73 m2 or a ≥30% reduction in eGFR from the initial measurement, which was defined as CKD progression. We applied the Kaplan-Meier analysis and Cox regression hazard model to examine the association between magnesium levels and CKD progression. RESULTS: The analysis included 9868 outpatients during the follow-up period. The low magnesium group was significantly more likely to reach CKD progression. Cox regression, adjusting for covariates and using the normal magnesium group as the reference, showed that the hazard ratio for the low magnesium group was 1.20 (1.08-1.34). High magnesium was not significantly associated with poor renal outcomes compared with normal magnesium. CONCLUSION: Based on large real-world data, this study demonstrated that low magnesium levels are associated with poorer renal outcomes.

Kidney outcomes associated with haematuria and proteinuria trajectories among patients with IgA nephropathy in real-world clinical practice: The Japan Chronic Kidney Disease Database.

AIM: Among patients with Immunoglobulin A (IgA) nephropathy, we aimed to identify trajectory patterns stratified by the magnitude of haematuria and proteinuria using repeated urine dipstick tests, and assess whether the trajectories were associated with kidney events. METHODS: Using a nationwide multicentre chronic kidney disease (CKD) registry, we analysed data from 889 patients with IgA nephropathy (mean age 49.3 years). The primary outcome was a sustained reduction in eGFR of 50% or more from the index date and thereafter. During follow-up (median 49.0 months), we identified four trajectories (low-stable, moderate-decreasing, moderate-stable, and high-stable) in both urine dipstick haematuria and proteinuria measurements, respectively. RESULTS: In haematuria trajectory analyses, compared to the low-stable group, the adjusted hazard ratios (HRs) (95% confidence interval [CI]) for kidney events were 2.59 (95% CI, 1.48-4.51) for the high-stable, 2.31 (95% CI, 1.19-4.50) for the moderate-stable, and 1.43 (95% CI, (0.72-2.82) for the moderate-decreasing groups, respectively. When each proteinuria trajectory group was subcategorized according to haematuria trajectories, the proteinuria group with high-stable and with modest-stable haematuria trajectories had approximately 2-times higher risk for eGFR reduction ≥50% compared to that with low-stable haematuria trajectory. CONCLUSION: Assessments of both haematuria and proteinuria trajectories using urine dipstick could identify high-risk IgA nephropathy patients.

Genome-wide association study of the risk of chronic kidney disease and kidney-related traits in the Japanese population: J-Kidney-Biobank.

Chronic kidney disease (CKD) is a syndrome characterized by a gradual loss of kidney function with decreased estimated glomerular filtration rate (eGFR), which may be accompanied by an increase in the urine albumin-to-creatinine ratio (UACR). Although trans-ethnic genome-wide association studies (GWASs) have been conducted for kidney-related traits, there have been few analyses in the Japanese population, especially for the UACR trait. In this study, we conducted a GWAS to identify loci related to multiple kidney-related traits in Japanese individuals. First, to detect loci associated with CKD, eGFR, and UACR, we performed separate GWASs with the following two datasets: 475 cases of CKD diagnosed at seven university hospitals and 3471 healthy subjects (dataset 1) and 3664 cases of CKD-suspected individuals with eGFR <60 ml/min/1.73 m2 or urinary protein ≥ 1+ and 5952 healthy subjects (dataset 2). Second, we performed a meta-analysis between these two datasets and detected the following associated loci: 10 loci for CKD, 9 loci for eGFR, and 22 loci for UACR. Among the loci detected, 22 have never been reported previously. Half of the significant loci for CKD were shared with those for eGFR, whereas most of the loci associated with UACR were different from those associated with CKD or eGFR. The GWAS of the Japanese population identified novel genetic components that were not previously detected. The results also suggest that the group primarily characterized by increased UACR possessed genetically different features from the group characterized by decreased eGFR.

eGFR slope as a surrogate endpoint for clinical study in early stage of chronic kidney disease: from The Japan Chronic Kidney Disease Database.

BACKGROUND: In clinical trials targeting early chronic kidney disease (CKD), eGFR slope has been proposed as a surrogate endpoint for predicting end-stage kidney disease (ESKD). However, it is unclear whether the eGFR slope serves as a surrogate endpoint for predicting long-term prognosis in Japanese early CKD populations. METHODS: The data source was the J-CKD-Database, which contains real-world data on patients with CKD in Japan. eGFR slope was calculated from the eGFR of each period, 1-year (1-year slope), 2-year (2-year slope), and 3-year (3-year slope), for participants with a baseline eGFR ≥ 30 ml/min/1.73 m2. The outcome was ESKD (defined as dialysis initiation or incidence of CKD stage G5). The relationship between eGFR slope and the sub-distribution hazard ratio (SHR) of ESKD with death as a competing event was investigated using a Fine-Gray proportional hazard regression model. RESULTS: The number of participants and mean observation periods were 7768/877 ± 491 days for 1-year slope, 6778/706 ± 346 days for 2-year slope, and 5219/495 ± 215 days for 3-year slope. As the eGFR slope decreased, a tendency toward a lower risk of ESKD was observed. Compared with the 1-year slope, there was a smaller variation in the slope values for the 2-year or 3-year slope and a greater decrease in the SHR; therefore, a calculation period of 2 or 3 years for the eGFR slope was considered appropriate. CONCLUSION: Even in Japanese patients with early stage CKD, a slower eGFR slope calculated from eGFR values over 2-3 years was associated with a decreased risk of ESKD.

SH3BP2 Deficiency Ameliorates Murine Systemic Lupus Erythematosus.

BACKGROUND: The adaptor protein Src homology 3 domain-binding protein 2 (SH3BP2) is widely expressed in immune cells. It controls intracellular signaling pathways. The present study was undertaken to investigate the role of SH3BP2 in a murine systemic lupus erythematosus model. METHODS: For the lupus model, we used Faslpr/lpr mice. Clinical and immunological phenotypes were compared between Faslpr/lpr and SH3BP2-deficient Faslpr/lpr mice. Splenomegaly and renal involvement were assessed. Lymphocyte subsets in the spleen were analyzed by flow cytometry. To examine the role of SH3BP2 in specific cells, B cell-specific SH3BP2-deficient lupus mice were analyzed; T cells and bone marrow-derived dendritic cells and macrophages were analyzed in vitro. RESULTS: SH3BP2 deficiency significantly reduced lupus-like phenotypes, presented as splenomegaly, renal involvement, elevated serum anti-dsDNA antibody, and increased splenic B220+CD4-CD8- T cells. Notably, SH3BP2 deficiency in B cells did not rescue the lupus-like phenotypes. Furthermore, SH3BP2 deficiency did not substantially affect the characteristics of T cells and macrophages in vitro. Interestingly, SH3BP2 deficiency suppressed the differentiation of dendritic cells in vitro and reduced the number of dendritic cells in the spleen of the lupus-prone mice. CONCLUSIONS: SH3BP2 deficiency ameliorated lupus-like manifestations. Modulating SH3BP2 expression could thus provide a novel therapeutic approach to autoimmune diseases.