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Immunoglobulin A nephropathy (IgAN) is the most common type of primary glomerulonephritis. Since most patients have a relatively benign renal prognosis, long-term follow-up is required. During such a long course of disease, relapse of IgAN is occasionally observed after upper respiratory tract infection or without any trigger. However, little is known about the impact of relapse on long-term renal outcomes.In this retrospective cohort study of biopsy-proven primary IgAN, we analyzed the association of 5-year therapeutic responsiveness (relapse) with the subsequent development of end-stage kidney disease (ESKD) using a 5-year landmark analysis (Cox model) and explored predictors of relapse from histological and clinical data at baseline.Among 563 patients from the exploratory cohort, most relapses (13.7%) occurred within 5 years after treatment. Using 5-year landmark analysis, among 470 patients, 79 developed ESKD during a median follow-up period of 155 months. Even after adjustment for clinicopathological relevant confounders, hazard ratios (95% confidence intervals) in the relapse and non-responder groups compared with the remission group were 2.86 (1.41-5.79) and 2.74 (1.48-5.11), respectively. Among 250 patients who achieved remission within 5 years, proteinuria, eGFR, mesangial hypercellularity, endocapillary hypercellularity, segmental sclerosis, and crescent, but not interstitial fibrosis/tubular atrophy, were independent predictors of 5-year relapse in multivariable logistic regression analysis, CONCLUSIONS: Both relapsers and non-responders had similarly strong association with ESKD in patients with IgAN. We also confirmed the predictors of relapse 5 years after renal biopsy, which may guide the treatment strategies for patients with IgAN who occasionally relapse after remission.

Dyslipidemias are common among patients with chronic kidney disease (CKD) and are a major risk factor for cardiovascular disease. This study aimed to investigate the association between early-stage CKD and new-onset dyslipidemia for each lipid profile.This nationwide longitudinal study included data from the Japan Specific Health Checkups (J-SHC) Study. New-onset dyslipidemia was indicated by hypertriglyceridemia (High-TG; ≥150 mg/dL), hyper-LDL cholesterolemia (High-LDL-C; ≥140 mg/dL), or hypo-HDL chelesterolemia (Low-HDL-C;40 mg/dL) levels according to the guideline of Japan Atherosclerosis Society, or High-TG/HDL-C ratio (≥3.5) which was a good predictor of atherosclerosis. The incidence of new-onset dyslipidemia was compared between participants with and without CKD. Survival curves were used to analyze the incidence of each dyslipidemia.Of 289,462 participants with a median follow-up period of 3 years, the incidence of High-TG, High-LDL-C, Low-HDL-C, and High-TG/HDL-C ratios were 64.4/1000 person-years, 83.1/1000 person-years, 14.5/1000 person-years, and 39.6/1000 person-years, respectively. The adjusted hazard ratios (95% confidence intervals) for High-TG, High-LDL-C, Low-HDL-C, and High-TG/HDL-C ratio were 1.09 (1.05-1.13), 0.99 (0.95-1.04), 1.12 (1.05-1.18), and 1.14 (1.09-1.18), respectively, in CKD participants as compared to non-CKD participants. Decreased eGFR and presence of proteinuria were independently associated with higher risks for new-onset of High-TG, Low-HDL-C, and High-TG/HDL-C ratios.CKD was associated with a higher risk of new-onset High-TG, Low-HDL-C, and High-TG/HDL-C ratios, but not High-LDL-C, in the general population. These CKD-specific lipid abnormalities may explain the residual risk for CKD-related cardiovascular disease.

Background A dose of 0.5–1 mg/kg/day of prednisolone (PSL) is administered for the initial treatment of minimal change disease (MCD). However, little is known about the optimal PSL dose for the initial treatment of MCD. Methods We conducted a retrospective multicenter cohort study of treatment-naive adult patients with MCD diagnosed by renal biopsy from 1981 to 2015 in whom PSL monotherapy was performed as the initial treatment. The exposure of interest was an initial median PSL dose of Results Ninety-one patients met the inclusion criteria. During a median follow-up of 2.98 years, 87 (95.6%) patients achieved complete remission, and 47.1% relapsed after remission. There was no significant difference in the remission rate between the groups at 4 weeks of follow-up (66.7 vs. 82.6%). The median time to remission in Group L was comparable to that in Group H (17.0 vs. 14.0 days). A multivariable Cox hazard model revealed that the initial PSL dose was not a significant predictor of remission. The cumulative steroid doses at 6 months, 1 year, and 2 years after treatment initiation were significantly lower in Group L than in Group H. Conclusion The initial PSL dose was not associated with time to remission, remission rate, time to relapse, or relapse rate. Therefore, a low initial steroid dose may be sufficient to achieve remission.

Association between physical activity and decline in renal function among the general population is not fully understood. This is a longitudinal study on subjects who participated in the Japanese nationwide Specific Health Checkup program between 2008 and 2014. The exposure of interest was baseline self-reported walking habit. The outcomes were annual change and incidence of 30% decline in estimated glomerular filtration rate (eGFR). Changes in eGFR were compared using a linear mixed-effects model. Cox proportional hazard models were used to examine the association between self-reported walking habit and 30% decline in eGFR. Among 332,166 subjects, 168,574 reported walking habit at baseline. The annual changes in eGFR [95% confidence interval (CI)] among subjects with and without baseline self-reported walking habit were − 0.17 (− 0.19 to − 0.16) and − 0.26 (− 0.27 to − 0.24) mL/min/1.73 m2/year, respectively (P for interaction between time and baseline self-reported walking habit

Background The relationship between kidney function at 3 months after acute kidney injury (AKI) and kidney function prognosis has not been characterized. Methods This retrospective cohort study included adults who underwent noncardiac surgery under general anesthesia. Exclusion criteria included obstetric or urological surgery, missing data and preoperative dialysis. Linear mixed-effects models were used to compare estimated glomerular filtration rate (eGFR) slopes in patients with and without AKI. Multivariable Cox proportional hazard models were used to examine the associations of AKI with incident chronic kidney disease (CKD) and decline in eGFR ≥30%. Results Among 5272 patients, 316 (6.0%) developed AKI. Among 1194 patients with follow-up creatinine values, eGFR was stable or increased in patients with and without AKI at 3 months postoperatively and declined thereafter. eGFR decline after 3 months postoperatively was faster among patients with AKI than among patients without AKI (P = .09). Among 938 patients without CKD—both at baseline and at 3 months postoperatively—226 and 161 developed incident CKD and a decline in eGFR ≥30%, respectively. Despite adjustment for eGFR at 3 months, AKI was associated with incident CKD {hazard ratio [HR] 1.73 [95% confidence interval (CI) 1.06–2.84]} and a decline in eGFR ≥30% [HR 2.41 (95% CI 1.51–3.84)]. Conclusions AKI was associated with worse kidney outcomes, regardless of eGFR at 3 months after surgery. Creatinine-based eGFR values at 3 months after AKI might be affected by acute illness-induced loss of muscle mass. Kidney function might be more accurately evaluated much later after surgery or using cystatin C values.

This retrospective cohort study examined the roles of inflammation in acute kidney injury (AKI). Serum albumin and C-reactive protein (CRP) were used as markers of inflammation. Adults who underwent non–cardiac surgery from 2007 to 2011 were included. Exclusion criteria were urological surgery, obstetric surgery, missing data, and pre-operative dialysis. Subjects were followed until the end of 2015 or loss to follow-up. Associations between pre–operative albumin or CRP and post-operative AKI or association between AKI and mortality were examined by logistic or Cox regression, respectively. Mediation analyses were performed using albumin and CRP as mediators. Among 4,538 subjects, 272 developed AKI. Pre-operative albumin was independently associated with AKI (odds ratio [95% confidence interval (CI)]: 0.63 [0.48–0.83]). During a median follow-up of 4.5 years, 649 died. AKI was significantly associated with mortality (hazard ratio [HR] [95% CI]: 1.58 [1.22–2.04]). Further adjustment for pre-operative albumin and CRP attenuated the association (HR [95% CI]: 1.28 [0.99–1.67]). The proportions explained by mediating effects of lnCRP and albumin were 29.3% and 39.2% and mediation effects were statistically significant. In conclusion, inflammation is a predictor of AKI and a mediator of mortality after AKI. Interventions targeting inflammation might improve outcomes of AKI.

A-26-year-old man was admitted to our hospital with diffuse abdominal pain, nausea, and vomiting. He had a history of malignant nephrosclerosis, for which he had been receiving peritoneal dialysis (PD) for the past 14 months. His PD effluent was cloudy and turbid (white blood cell count, 10,528/μL; neutrophils 95.2%). A Gram-negative coccobacillus was isolated from peritoneal fluid culture. However, the organism could not be identified by matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS) (Vitek MS, bioMerieux), but was identified as Moraxella osloensis by the 16S rRNA gene sequencing. He was successfully treated with intraperitoneal cefazolin therapy for 3 weeks without removing the intra-abdominal catheter. A literature review revealed three previous case reports all of which were diagnosed by MALDI Biotyper (Bruker Daltonics), suggesting that the identification of M. osloensis may vary depending on the type of MALDI-TOF MS system. In conclusion, we experienced a case of M. osloensis infection in a PD patient, which was successfully treated by antibiotic treatment, without removing the PD catheter.

This longitudinal cohort study aimed to create a novel prediction model for cardiovascular death with lifestyle factors. Subjects aged 40–74 years in the Japanese nationwide Specific Health Checkup Database in 2008 were included. Subjects were randomly assigned to the derivation and validation cohorts by a 2:1 ratio. Points for the prediction model were determined using regression coefficients that were derived from the Cox proportional hazards model in the derivation cohort. Models 1 and 2 were developed using known risk factors and known factors with lifestyle factors, respectively. The models were validated by comparing Kaplan-Meier curves between the derivation and validation cohorts, and by calibration plots in the validation cohort. Among 295,297 subjects, data for 120,823 were available. There were 310 cardiovascular deaths during a mean follow-up of 3.6 years. Model 1 included known risk factors. In model 2, weight gain, exercise habit, gait speed, and drinking alcohol were additionally included as protective factors. Kaplan-Meier curves matched better between the derivation and validation cohorts in model 2, and model 2 was better calibrated. In conclusion, our prediction model with lifestyle factors improved the predictive ability for cardiovascular death.

Patients with anti-glomerular basement membrane (GBM) antibody glomerulonephritis typically exhibit rapidly progressive glomerulonephritis (RPGN). The renal outcome as well as the prognosis of this disease is worse than other forms of RPGN such as those from microscopic polyangiitis. Therefore, early therapeutic intervention is essential to improve its prognosis. One month before referral to our hospital, a 54-year-old female attended another hospital because of macrohematuria. At that time, she had proteinuria and macrohematuria with normal renal function, was negative for anti-GBM antibodies, and was diagnosed with chronic glomerulonephritis. A month later when she was admitted to our hospital, she showed renal insufficiency and was positive for anti-GBM antibodies. Immediately after recognizing the anti-GBM antibody status, plasma exchange and the first course of steroid pulse therapy was started. After 5 days of therapy, renal biopsy confirmed severe crescentic glomerulonephritis in which all the observed glomeruli were involved with cellular crescents. Despite this, she survived without end-stage renal disease after three courses of steroid pulse therapy and seven sessions of plasma exchange. This favorable outcome reflects the repeated analysis of anti-GBM antibodies within a very short period and the rapid therapeutic intervention in addition to the intensive immunosuppressive therapies.

Background The survival rate of chronic dialysis patients in Japan remains the highest worldwide, so there is value in presenting Japan’s situation internationally. We examined whether aggregate figures on dialysis patients in the National Database of Health Insurance Claims and Special Health Checkups of Japan (NDB), which contains data on insured procedures of approximately 100 million Japanese residents, complement corresponding figures in the Japanese Society for Dialysis Therapy Renal Data Registry (JRDR). Methods Subjects were patients with medical fee points for dialysis recorded in the NDB during 2014–2018. We analyzed annual numbers of dialysis cases, newly initiated dialysis cases– and deaths. Results Compared with the JRDR, the NDB had about 6–7% fewer dialysis cases but a similar number of newly initiated dialysis cases. In the NDB, the number of deaths was about 6–10% lower, and the number of hemodialysis cases was lower, while that of peritoneal dialysis cases was higher. The cumulative survival rate at dialysis initiation was approximately 6 percentage points lower in the NDB than in the JRDR, indicating that some patients die at dialysis initiation. Cumulative survival rate by age group was roughly the same between the NDB and JRDR in both sexes. Conclusion The use of the NDB enabled us to aggregate data of dialysis patients. With the definition of dialysis patients used in this study, analyses of concomitant medications, comorbidities, surgeries, and therapies will become possible, which will be useful in many future studies.

The excretion and reabsorption of uric acid both to and from urine are tightly regulated by uric acid transporters. Metabolic syndrome conditions, such as obesity, hypercholesterolemia, and insulin resistance, are believed to regulate the expression of uric acid transporters and decrease the excretion of uric acid. However, the mechanisms driving cholesterol impacts on uric acid transporters have been unknown. Here, we show that cholesterol metabolite 27‐hydroxycholesterol (27HC) upregulates the uric acid reabsorption transporter URAT1 encoded by SLC22A12 via estrogen receptors (ER). Transcriptional motif analysis showed that the SLC22A12 gene promoter has more estrogen response elements (EREs) than other uric acid reabsorption transporters such as SLC22A11 and SLC22A13, and 27HC‐activated SLC22A12 gene promoter via ER through EREs. Furthermore, 27HC increased SLC22A12 gene expression in human kidney organoids. Our results suggest that in hypercholesterolemic conditions, elevated levels of 27HC derived from cholesterol induce URAT1/SLC22A12 expression to increase uric acid reabsorption, and thereby, could increase serum uric acid levels.

IntroductionThere are fewer reports about whether the presence of hematuria affects the progression of chronic kidney disease in patients with diabetic nephropathy. We analyzed whether microscopic hematuria in diabetic nephropathy is a risk factor for end-stage kidney disease (ESKD).Research design and methodsThe present study was a retrospective cohort study of patients with biopsy-proven diabetic nephropathy. We recruited 397 patients with diabetic nephropathy, which was confirmed by renal biopsy between June 1981 and December 2014 and followed them until October 2018 or death. Patients with microscopic hematuria before renal biopsy were defined as the hematuria group (n=91), and the remainder as the no-hematuria group (n=306). The main outcome was the occurrence of ESKD, which was defined by the requirement of permanent renal replacement therapies.ResultsThe systolic and diastolic blood pressure, serum creatinine and proteinuria were significantly higher, and the estimated glomerular filtration rate was significantly lower in the hematuria group compared with the no-hematuria group. Pathological evaluations revealed that glomerular, tubulointerstitial and vascular lesions in the hematuria group were significantly more severe. During a median of 10.1 years, 44 and 52 patients developed ESKD in the hematuria group and the no-hematuria group, respectively. Survival analyses showed that the incidence of ESKD was significantly higher in the hematuria group compared with the no-hematuria group (log-rank, pConclusionsMicroscopic hematuria is a risk factor for ESKD in diabetic nephropathy, independent of proteinuria and renal pathology.

Background and Aims Due to the interplay of chronic kidney disease and the heart, it is common for myocardial damage and strain to be present in patients with end stage kidney disease. The cardiac biomarkers Troponin I (cTnI) and the N-terminal fragment of prohormone brain natriuretic peptide (NT-proBNP) are strongly predictive of heart failure in the general population, however the value of their routine measurement for stratification of risk in hemodialysis (HD) patients is unknown. International DOPPS data indicate that these cardiac biomarkers are measured in fewer than 2% of hemodialysis patients in real-world practice. We sought to test the associations of cTNI and NT-proBNP with death in a large HD cohort. Method We analyzed data from 1169 prevalent Japanese hemodialysis patients in DOPPS phase 5 (J-DOPPS; 2012-2015) where pre-dialysis levels of cTnI and NT-proBNP at study enrollment by protocol for all participants. We used Cox regression to test the association of the cardiac biomarkers with all-cause mortality, adjusting for potential confounders. We conducted stratified analyses to assess potential effect modification of individual clinical characteristics: age, systolic blood pressure, dialysis vintage, diabetes mellitus, cardiovascular disease, and heart failure (CHF). Results Median (interquartile range) cTnI and NT-proBNP levels were 0.018 [0.005, 0.04] ng/mL and 3432 [1580, 8017] pg/mL, respectively. There was a positive direct association between cTNI and NT-proBNP (Spearman correlation coefficient=0.58). We observed 174 deaths during a median [IQR] follow-up time of 2.8 [2.3, 2.9] years. Compared to the reference group of cTNI0.04. Compared to the reference group of NT-proBNP 4000 to 8000 pg/mL; and 3.23 (1.71, 6.09) for NT-proBNP > 8000pg/mL. For both variables associations with mortality were comparable in patients with and without heart failure (p values for interaction=0.07 and 0.19, for NT-proBNP and cTNI, respectively) and according to other stratification variables (the p values for interaction were >0.15 for all other stratified models). Conclusion Routinely measured (not by indication) NT-proBNP and Troponin I are strongly associated with mortality among prevalent Japanese HD patients. Routine evaluation of these cardiac biomarkers in HD patients with or without a previous diagnosis of CHF may help identify patients at risk of death who may have undetected heart failure or cardiac strain due to fluid overload.

Introduction: Angiotensin receptor blockers (ARBs) are preferably used in hypertensive patients with CKD. Azilsartan is a strong antihypertensive ARB, but its antiproteinuric effects are not well understood. We compared the antiproteinuric effect of azilsartan and candesartan in CKD patients in an open-label, randomized, crossover trial. Methods: A total of 111 patients were treated with 20 mg of azilsartan daily for 2 months as a run-in period. After the run-in period, patients were randomized into 2 arms and received either 20 mg of azilsartan or 8 mg of candesartan daily for 3 months in a crossover trial. The primary outcome was the percent change in urinary protein-to-Cr ratio (UPCR). Results: Ninety-five patients completed the trial. The mean age was 64.3 years. The estimated glomerular filtration rate (eGFR) and UPCR were 41.5 mL/min/1.73 m2 and 1.8 g/gCr, respectively. The baseline systolic and diastolic blood pressures were 131.4 and 71.0 mm Hg, respectively. The mean percent change in the UPCR was −3.8% in the azilsartan group and 30.8% in the candesartan group at the 1st endpoint (p = 0.0004), and 6.1% in the azilsartan group and 25.8% in the candesartan group at the 2nd (final) endpoint (p = 0.029). The incidence of adverse events, including eGFR levels and serum potassium levels, was not significantly different between the groups. Conclusion: A 20 mg azilsartan dose had potent antiproteinuric effects compared with an 8 mg candesartan dose, without an increase in adverse events. Azilsartan may provide renal protection in addition to antihypertensive effects in CKD patients.

Aims Diabetic nephropathy, a pathologically diagnosed microvascular complication of diabetes, is a strong risk factor for cardiovascular events, which mainly involve arteries larger than those affected in diabetic nephropathy. However, the association between diabetic nephropathy pathological findings and cardiovascular events has not been well studied. We aimed to investigate whether the pathological findings in diabetic nephropathy are closely associated with cardiovascular event development. Methods This retrospective cohort study analysed 377 people with type 2 diabetes and biopsy-proven diabetic nephropathy, with a median follow-up of 5.9 years (interquartile range 2.0 to 13.5). We investigated how cardiovascular events were impacted by two vascular diabetic nephropathy lesions, namely arteriolar hyalinosis and arterial intimal thickening, and by glomerular and interstitial lesions. Results Of the 377 people with diabetic nephropathy, 331 (88%) and 295 (78%) had arteriolar hyalinosis and arterial intimal thickening, respectively. During the entire follow-up period, those with arteriolar hyalinosis had higher cardiovascular event rates in the crude Kaplan-Meier analysis than those without these lesions (P = 0.005, log-rank test). When fully adjusted for clinically relevant confounders, arteriolar hyalinosis independently predicted cardiovascular events [hazard ratio (HR) 1.99; 95% confidence interval (CI) 1.12, 3.86], but we did not find any relationship between arterial intimal thickening and cardiovascular events (HR 0.89; 95% CI 0.60, 1.37). Additionally, neither glomerular nor interstitial lesions were independently associated with cardiovascular events in the fully adjusted model. Conclusions Arteriolar hyalinosis, but not intimal thickening of large arteries, was strongly associated with cardiovascular events in people with diabetic nephropathy.

Background:Deposition of advanced glycation end products (AGEs) is frequently found in the peritoneum of patients on peritoneal dialysis (PD). Angiogenesis is also observed in the peritoneum. However, the clinical significance of AGEs and angiogenesis in the peritoneum is not fully understood. We evaluated the maturation of capillary vessels and investigated whether AGEs are associated with angiogenesis and peritoneal function in the peritoneal membrane.Methods:Peritoneum obtained when PD catheters were removed from 61 patients with PD was analyzed. The peritoneum was immunohistochemically stained with anti-CD34 (for endothelial cells), anti-alpha smooth muscle actin (αSMA) (for pericytes), and anti-AGE antibodies. We defined CD34-positive and αSMA-negative vessels as immature capillary vessels in peritoneal membranes using serial sections. We evaluated the associations between vessel density, peritoneal function (dialysate-to-plasma ratio for creatinine (D/P creatinine)), and the degree of AGE deposition.Results:AGE accumulation in the interstitium was positively associated with the duration of PD ( p < 0.01). AGE accumulation in the interstitium and vascular wall was positively correlated with the use of acidic solution ( p < 0.05) and the maximum value of D/P creatinine ( p < 0.05). AGE accumulation in the vascular wall was significantly associated with immature capillary density (CD34+/αSMA−) in the peritoneum ( p < 0.01). Vessel density was not significantly correlated with the last measurement of D/P creatinine ( p = 0.126, r = 0.202), However, immature capillary density was positively correlated with the last measurement of D/P creatinine ( p < 0.05, r = 0.278).Conclusions:AGE accumulation is significantly associated with immature angiogenesis and peritoneal dysfunction in patients undergoing PD.

Background Recent evidence emphasizes the critical role of inflammation in the development of diabetic nephropathy. Angiotensin-converting enzyme (ACE) plays an active role in regulating the renal inflammatory response associated with diabetes. Studies have also shown that ACE has roles in inflammation and the immune response that are independent of angiotensin II. ACE’s two catalytically independent domains, the N- and C-domains, can process a variety of substrates other than angiotensin I. Methods To examine the relative contributions of each ACE domain to the sodium retentive state, renal inflammation, and renal injury associated with diabetic kidney disease, we used streptozotocin to induce diabetes in wild-type mice and in genetic mouse models lacking either a functional ACE N-domain (NKO mice) or C-domain (CKO mice). Results In response to a saline challenge, diabetic NKO mice excreted 32% more urinary sodium compared with diabetic wild-type or CKO mice. Diabetic NKO mice also exhibited 55% less renal epithelial sodium channel cleavage (a marker of channel activity), 55% less renal IL-1 β , 53% less renal TNF- α , and 53% less albuminuria than diabetic wild-type mice. This protective phenotype was not associated with changes in renal angiotensin II levels. Further, we present evidence that the anti-inflammatory tetrapeptide N-acetyl-seryl-asparyl-lysyl-proline (AcSDKP), an ACE N-domain–specific substrate that accumulates in the urine of NKO mice, mediates the beneficial effects observed in the NKO. Conclusions These data indicate that increasing AcSDKP by blocking the ACE N-domain facilitates sodium excretion and ameliorates diabetic kidney disease independent of intrarenal angiotensin II regulation.

Diabetic nephropathy is a major cause of end-stage renal disease in developed countries. While angiotensin-converting enzyme (ACE) inhibitors are used to treat diabetic nephropathy, how intrarenal ACE contributes to diabetic renal injury is uncertain. Here, two mouse models with different patterns of renal ACE expression were studied to determine the specific contribution of tubular vs. glomerular ACE to early diabetic nephropathy: it-ACE mice, which make endothelial ACE but lack ACE expression by renal tubular epithelium, and ACE 3/9 mice, which lack endothelial ACE and only express renal ACE in tubular epithelial cells. The absence of endothelial ACE normalized the glomerular filtration rate and endothelial injury in diabetic ACE 3/9 mice. However, these mice developed tubular injury and albuminuria and displayed low renal levels of megalin that were similar to those observed in diabetic wild-type mice. In diabetic it-ACE mice, despite hyperfiltration, the absence of renal tubular ACE greatly reduced tubulointerstitial injury and albuminuria and increased renal megalin expression compared with diabetic wild-type and diabetic ACE 3/9 mice. These findings demonstrate that endothelial ACE is a central regulator of the glomerular filtration rate while tubular ACE is a key player in the development of tubular injury and albuminuria. These data suggest that tubular injury, rather than hyperfiltration, is the main cause of microalbuminuria in early diabetic nephropathy.

Renal fibrosis is the final common pathway of chronic kidney diseases. Lymphatic vessel (LV) proliferation is found in human renal diseases and other fibrotic diseases, suggesting that lymphangiogenesis is associated with the progression or suppression of kidney diseases. However, the purpose of LV proliferation is not completely understood. We investigated the effect of vascular endothelial growth factor (VEGF)-C on lymphangiogenesis, inflammation, and fibrosis in the mouse kidney using the unilateral ureteral obstruction (UUO) model. In UUO mice, significant proliferation of LVs was accompanied by tubulointerstitial nephritis and fibrosis. We continuously administered recombinant human VEGF-C to UUO model mice using an osmotic pump (UUO+VEGF-C group). Lymphangiogenesis was significantly induced in the UUO+VEGF-C group compared with the vehicle group, despite similar numbers of capillaries in both groups. The number of infiltrating macrophages, and levels of inflammatory cytokines and transforming growth factor-β1 were reduced in the UUO+VEGF-C group compared with the vehicle group. Renal fibrosis was consequently attenuated in the UUO+VEGF-C group. In cultured lymphatic endothelial cells, administration of VEGF-C increased the activity and proliferation of lymphatic endothelial cells (LECs) and expression of adhesion molecules such as vascular cell adhesion molecule-1. These findings suggest that induction of lymphangiogenesis ameliorates inflammation and fibrosis in the renal interstitium. Enhancement of the VEGF-C signaling pathway in LECs may be a therapeutic strategy for renal fibrosis.

Key Points Question Is the Simple Postoperative AKI Risk (SPARK) index, which was developed to predict postoperative acute kidney injury in noncardiac surgery, useful in a different population? Findings In a cohort study of 5135 adults in Japan, the incidence of postoperative acute kidney injury increased as scores on the SPARK index increased. However, the model’s discriminative and calibration powers were suboptimal owing to overestimated probability among those with especially high risk of developing acute kidney injury. Meaning These findings suggest that it is difficult to precisely predict the probability of acute kidney injury preoperatively in noncardiac surgery, which includes various surgical procedures and participants with various medical backgrounds., This cohort study externally validates the Simple Postoperative Acute Kidney Injury Risk (SPARK) index for prediction of acute kidney injury among patients undergoing noncardiac surgery., Importance The Simple Postoperative AKI Risk (SPARK) index is a prediction model for postoperative acute kidney injury (PO-AKI) in patients undergoing noncardiac surgery. External validation has not been performed. Objective To externally validate the SPARK index. Design, Setting, and Participants This single-center retrospective cohort study included adults who underwent noncardiac surgery under general anesthesia from 2007 to 2011. Those with obstetric or urological surgery, estimated glomerular filtration rate (eGFR) of less than 15 mL/min/1.73 m2, preoperative dialysis, or an expected surgical duration of less than 1 hour were excluded. The study was conducted at Nara Medical University Hospital. Data analysis was conducted from January to July 2021. Exposures Risk factors for AKI included in SPARK index. Main Outcomes And Measures PO-AKI, defined as an increase in serum creatinine of at least 0.3 mg/dL within 48 hours or 150% compared with preoperative baseline value or urine output of less than 0.5 mL/kg/h for at least 6 hours within 1 week after surgery, and critical AKI, defined as either AKI stage 2 or greater and/or any AKI connected to postoperative death or requiring kidney replacement therapy before discharge. The discrimination and calibration of the SPARK index were examined with area under the receiver operating characteristic curves (AUC) and calibration plots, respectively. Results Among 5135 participants (2410 [46.9%] men), 303 (5.9%) developed PO-AKI, and 137 (2.7%) developed critical AKI. Compared with the SPARK cohort, participants in our cohort were older (median [IQR] age, 56 [44-66] years vs 63 [50-73] years), had lower baseline eGFR (median [IQR], 82.1 [71.4-95.1] mL/min/1.73 m2 vs 78.2 [65.6-92.2] mL/min/1.73 m2), and had a higher prevalence of comorbidities (eg, diabetes: 3956 of 51 041 [7.8%] vs 802 [15.6%]). The incidence of PO-AKI and critical AKI increased as the scores on the SPARK index increased. For example, 10 of 593 participants (1.7%) in SPARK class A, indicating lowest risk, experienced PO-AKI, while 53 of 332 (16.0%) in SPARK class D, indicating highest risk, experienced PO-AKI. However, AUCs for PO-AKI and critical AKI were 0.67 (95% CI, 0.63-0.70) and 0.62 (95% CI, 0.57-0.67), respectively, and the calibration was poor (PO-AKI: y = 0.24x + 3.28; R2 = 0.86; critical AKI: y = 0.20x + 2.08; R2 = 0.51). Older age, diabetes, expected surgical duration, emergency surgery, renin-angiotensin-aldosterone system blockade use, and hyponatremia were not associated with PO-AKI in our cohort, resulting in overestimation of the predicted probability of AKI in our cohort. Conclusions and Relevance In this study, the incidence of PO-AKI increased as the scores on the SPARK index increased. However, the predicted probability might not be accurate in cohorts with older patients with more comorbidities.

Elevated levels of uric acid, a metabolite of purine in humans, is related to various diseases, such as gout, atherosclerosis and renal dysfunction. The excretion and reabsorption of uric acid to/from urine is tightly regulated by uric acid transporters. The amino acid sequences of uric acid reabsorption transporters, URAT1/SLC22A12, OAT4/SLC22A11, and OAT10/SLC22A13, share closer phylogenic relationship, whereas the gene promoter sequences are distant phylogenic relationship. Through the single-cell RNA-sequencing analysis of an adult human kidney, we found that only a small number of cells express these transporters, despite their role in the regulation of serum uric acid levels. Transcriptional motif analysis on these transporter genes, revealed that the URAT1/SLC22A12gene promoter displayed the most conserved estrogen response elements (EREs) among the three transporters. The endogenous selective estrogen receptor modulator (SERM) 27-hydroxycholesterol (27HC) had positive effects on the transcriptional activity of URAT1/SLC22A12. We also found that 27HC increased the protein and gene expression of URAT1/SLC22A12in mouse kidneys and human kidney organoids, respectively. These results strongly suggest the role of 27HC for URAT1/SLC22A12expression in renal proximal tubules and upregulation of serum uric acid levels and also show the relationship between cholesterol metabolism and serum uric acid regulation.Significance StatementThe elevated levels of serum uric acid cause various diseases, and the excretion/reabsorption of uric acid to/from urine is tightly regulated by the uric acid transporters. We found that despite the role in serum uric acid regulation, only a small number of cells express URAT1/SLC22A12. We also found that URAT1/SLC22A12gene promoter region has effective estrogen response elements, and endogenous selective estrogen receptor (ER) modulator 27-hydroxycholesterol (27HC) increased URAT1/SLC22A12expression in the mice kidneys and human kidney organoids. These suggest that 27HC increases URAT1/SLC22A12expression and upregulate serum uric acid levels. Since 27HC connects cholesterol metabolism, our study indicates the important link between cholesterol metabolism and serum uric acid regulation, and also provides a novel therapeutic approach to hyperuricemia.

Little is known about the association between intra-operative fluid balance (IFB) and post-operative acute kidney injury (AKI) in non-cardiac surgery. This is a retrospective cohort study. Adults who underwent non-cardiac surgery under general anesthesia from 2007 to 2011 at Nara Medical University Hospital were included. Those with obstetric or urological surgery, missing data, or pre-operative dialysis were excluded. Exposure of interest was IFB, defined as (amount of fluid administration − urine output − amount of bleeding)/body weight. Outcome variable was post-operative AKI within 1 week after surgery. Data were analyzed using logistic regression models and restricted cubic spline (RCS) analysis. Among 5168 subjects, AKI was observed in 309 (6.0%). Higher IFB (per 1 standard deviation) was independently associated with post-operative AKI after adjustment for potential confounders (odds ratio [95% confidence interval] of 1.18 [1.06–1.31]). The RCS curve showed an increase in expected probability of AKI associated with increase in IFB above 40 mL/kg. Subgroup analyses indicated higher IFB was especially associated with AKI among those with lower serum albumin, higher C-reactive protein, or positive proteinuria. The association was similar across intra-operative urine output or amount of bleeding (p for interaction 0.34 and 0.47, respectively), suggesting the association was not due to intra-operative oliguria or large amount of bleeding necessitating volume resuscitation. Higher IFB was independently associated with increase in post-operative AKI. Excessive fluid administration might have caused renal congestion and subsequent AKI. Avoiding fluid overload might be important in prevention of AKI.

Background Little is known about the association between pre-operative proteinuria and post-operative acute kidney injury (AKI) in noncardiac surgery. Methods This is a retrospective cohort study. Adults who underwent noncardiac surgery under general anesthesia from 2007 to 2011 at Nara Medical University Hospital were included. Those with obstetric or urological surgery, missing data for analyses or pre-operative dialysis were excluded. Exposure of interest was pre-operative proteinuria, defined as (+) or more by dipstick test. The outcome variable was post-operative AKI, defined by Kidney Disease: Improving Global Outcomes criteria, within 1 week after surgery. Multivariable logistic regression analyses were performed. Results Among 5168 subjects, 309 (6.0%) developed AKI. Pre-operative proteinuria was independently associated with post-operative AKI, with an odds ratio (OR) [95% confidence interval (CI)] of 1.80 (1.30–2.51). A sensitivity analysis restricted to elective surgery yielded a similar result. As proteinuria increased, the association with AKI became stronger [OR (95% CI) 1.14 (0.75–1.73), 1.24 (0.79–1.95), 2.75 (1.74–4.35) and 3.95 (1.62–9.62) for urinary protein (+/−), (+), (2+) and (3+), respectively]. Subgroup analyses showed proteinuria was especially associated with post-operative AKI among subjects with renin–angiotensin system inhibitors, other anti-hypertensives, hypoalbuminemia or impaired renal function (P for interaction = 0.05, 0.003, 0.09 or 0.02, respectively). Conclusions In noncardiac surgery, pre-operative proteinuria was independently associated with post-operative AKI. Subjects with proteinuria should be managed with caution to avoid AKI peri-operatively.

The cause of most hypertensive disease is unclear, but inflammation appears critical in disease progression. However, how elevated blood pressure initiates inflammation is unknown, as are the effects of high blood pressure on innate and adaptive immune responses. We now report that hypertensive mice have increased T cell responses to antigenic challenge and develop more severe T cell-mediated immunopathology. A root cause for this is hypertension-induced erythrocyte adenosine 5'-triphosphate (ATP) release, leading to an increase in plasma ATP levels, which begins soon after the onset of hypertension and stimulates P2X7 receptors on antigen-presenting cells (APCs), increasing APC expression of CD86. Hydrolyzing ATP or blocking the P2X7 receptor eliminated hypertension-induced T cell hyperactivation. In addition, pharmacologic or genetic blockade of P2X7 receptor activity suppressed the progression of hypertension. Consistent with the results in mice, we also found that untreated human hypertensive patients have significantly elevated plasma ATP levels compared with treated hypertensive patients or normotensive controls. Thus, a hypertension-induced increase in extracellular ATP triggers augmented APC and T cell function and contributes to the immune-mediated pathologic changes associated with hypertensive disease.

Lymphangiogenesis occurs in diseased native kidneys and kidney allografts, and correlates with histological injury; however, the clinical significance of lymphatic vessels in kidney allografts is unclear. This study retrospectively reviewed 63 kidney transplant patients who underwent protocol biopsies. Lymphatic vessels were identified by immunohistochemical staining for podoplanin, and were classified according to their location as perivascular or interstitial lymphatic vessels. The associations between perivascular lymphatic density and kidney allograft function and pathological findings were analyzed. There were no significant differences in perivascular lymphatic densities in kidney allograft biopsy specimens obtained at 0 h, 3 months and 12 months. The groups with higher perivascular lymphatic density showed a lower proportion of progression of interstitial fibrosis/tubular atrophy grade from 3 to 12 months (P for trend = 0.039). Perivascular lymphatic density was significantly associated with annual decline of estimated glomerular filtration rate after 12 months (r = −0.31, P = 0.017), even after adjusting for multiple confounders (standardized β = −0.30, P = 0.019). High perivascular lymphatic density is associated with favourable kidney allograft function. The perivascular lymphatic network may be involved in inhibition of allograft fibrosis and stabilization of graft function.

Vascular calcification (VC) is a critical complication in patients with chronic kidney disease (CKD). The effects of spironolactone (SPL), a mineralocorticoid receptor (MR) antagonist, on VC have not been fully investigated in CKD. The present in vivo study determined the protective effects of SPL on VC in CKD rats. Rats were divided into a control group and four groups of rats with adenine-induced CKD. Three groups were treated with 0, 50, and 100 mg·kg−1·day−1 SPL for 8 wk, and one group was treated with 100 mg·kg−1·day−1 SPL for the last 2 wk of the 8-wk treatment period. After 8 wk, CKD rats developed azotemia and hyperphosphatemia, with increases in the expression of serum and glucocorticoid-regulated kinase-1 and sodium-phosphate cotransporter, in inflammation and oxidative stress level, in osteogenic signaling and apoptosis, and in aortic calcification, compared with control rats. SPL dose dependently decreased these changes in the aortas, concomitant with improvements in renal inflammation, tubulointerstitial nephritis, and kidney function. SPL neither lowered blood pressure level nor induced hyperkalemia. Treatment of CKD rats for the last 2 wk with 100 mg·kg−1·day−1 SPL attenuated VC compared with CKD rats with the same degree of kidney function and hyperphosphatemia. In conclusion, SPL dose dependently inhibits the progression of VC by suppressing MR signaling, local inflammation, osteogenic transition, and apoptosis in the aortas of CKD rats.

Angiotensin-converting enzyme (ACE) plays a key role in renal inflammation and sodium retention associated with diabetic nephropathy. Although most effects of ACE have been classically related to angiotensin (Ang) II synthesis, studies highlight an Ang II-independent role of ACE in inflammation. Indeed, ACE has two catalytic domains, the N- and C-domains, that can process a wide diversity of substrates besides Ang I. Here, we study the relative contributions of ACE domains to renal inflammation and sodium retention during diabetic nephropathy. Diabetes was induced with streptozotocin in wild-type (WT) mice and mice lacking either a functional ACE N-domain (NKO) or C-domain (CKO) (n=5-8). After 6 months of diabetes, we evaluated the natriuretic response to volume expansion. For this, mice were injected with 0.9% NaCl equivalent to 10% of their body weight. After 5 hours, diabetic NKO mice excreted 30% more urinary sodium in response to the saline challenge compared to diabetic WT or CKO mice ( P P P P P P P =NS). We next evaluated whether the anti-inflammatory tetrapeptide N-acetyl-seryl-asparyl-lysyl-proline (AcSDKP), an ACE N-domain specific substrate, mediates the protective phenotype of NKO. For this, diabetic mice were treated with the prolyl oligopeptidase inhibitor, S17092 (10 mg/kg, IP), that prevents the synthesis of AcSDKP. In diabetic NKO mice receiving S17092, sodium excretion in response to a saline challenge, ENaC α and γ subunit cleavage, renal inflammation and renal injury were indistinguishable from equally treated diabetic WT mice. In summary, these data indicate that increasing AcSDKP by blocking the ACE N-domain improves sodium handling and ameliorates diabetic kidney disease independently of intrarenal Ang II regulation.

Purpose of review The purpose of this study is to review current perspectives regarding the pathogenesis of cardiorenal syndrome (CRS) in chronic kidney disease (CKD), and current treatment guidelines for this condition. Recent findings The pathophysiological mechanisms underlying the development of CRS in CKD include neurohumoral, haemodynamic and CKD-related mechanisms. Recent evidence suggests that sympathetic nerve activity plays a role in CRS, but the SYMPLICITY HTN-3 trial failed to show a reduction of blood pressure after catheter-based renal denervation in patients with resistant hypertension. Kidney injury in patients with heart failure was previously considered to result from arterial underfilling due to low cardiac output, but the role of renal venous hypertension in this process has also recently been investigated. It would be useful to develop a reliable treatment option for CRS due to haemodynamic mechanism other than volume control using diuretics. Fibroblast growth factor 23 (FGF23) is a phosphaturic hormone that has recently been identified as a CKD-related factor affecting CRS. FGF23 treatment has both advantages and disadvantages in terms of CRS progression. Summary Multiple disorders underlie the development of CRS. Current treatment options include renin-angiotensin system blockade and volume control, but remain limited. A multidisciplinary approach is required to prevent CRS, including renal sympathetic denervation, treatment of renal venous hypertension and FGF23 treatment.

We elucidate the underlying mechanisms of bidirectional cardiorenal interaction, focusing on the sympathetic nerve driving disruption of the local renin–angiotensin system (RAS). A rat model of N ω -nitro-L-arginine methyl ester (L-NAME; a nitric oxide synthase inhibitor) administration was used to induce damage in the heart and kidney, similar to cardiorenal syndrome. L-NAME induced sympathetic nerve–RAS overactivity and cardiorenal injury accompanied by local RAS elevations. These were suppressed by bilateral renal denervation, but not by hydralazine treatment, despite the blood pressure being kept the same between the two groups. Although L-NAME induced angiotensinogen (AGT) protein augmentation in both organs, AGT mRNA decreased in the kidney and increased in the heart in a contradictory manner. Immunostaining for AGT suggested that renal denervation suppressed AGT onsite generation from activated resident macrophages of the heart and circulating AGT excretion from glomeruli of the kidney. We also examined rats treated with L-NAME plus unilateral denervation to confirm direct sympathetic regulation of intrarenal RAS. The levels of urinary AGT and renal angiotensin II content and the degrees of renal injury from denervated kidneys were less than those from contralateral innervated kidneys within the same rats. Thus, renal denervation has blood pressure–independent beneficial effects associated with local RAS inhibition.

Background How residual kidney function (RKF) functions in the prevention of anemia in peritoneal dialysis (PD) patients is unclear. In this study, we investigated the association between RKF and hemoglobin (Hb) level. Methods We performed a cross-sectional analysis of the association between RKF, defined as the mean renal creatinine and urea clearance (rCUC), and the Hb level in 50 PD patients registered retrospectively. The independent variable was mean rCUC as continuous or categorical variable by tertile, and the dependent variable was Hb level as continuous or dichotomous variable using Hb cutoff of 10 g/dL. We conducted a multivariable regression analysis and calculated the c-statistic for Hb level

Research studies demonstrated that interleukin (IL)-1β contributes to the development of diabetic nephropathy and hypertension. However, the origin and regulation of IL-1β synthesis during diabetic kidney injury are still unknown. Here, we hypothesize that renal epithelial cells produce IL-1β in response to a high glucose stress and that angiotensin converting enzyme (ACE) plays a key role in this process. To study this, we isolated proximal tubular (PT) epithelial cells from wild-type (WT) and mice lacking either the ACE N-domain (NKO) or the C-domain (CKO) catalytic activity. These cells were exposed to normal (5 mM) or high (30 mM) glucose for 24 hours. IL-1β produced by PT cells were assessed by ELISA and RT-PCR. High glucose induced WT PT cells to release significant amounts of IL-1β (from 5±1 to 70±6 pg/ml, p

Angiotensin-converting enzyme (ACE) inhibitors are widely used to reduce blood pressure. Here, we examined if an ACE is important for the antibacterial effectiveness of neutrophils. ACE knockout mice or mice treated with an ACE inhibitor were more susceptible to bacterial infection by methicillin-resistant Staphylococcus aureus (MRSA). In contrast, mice overexpressing ACE in neutrophils (NeuACE mice) have increased resistance to MRSA and better in vitro killing of MRSA, Pseudomonas aeruginosa, and Klebsiella pneumoniae ACE overexpression increased neutrophil production of reactive oxygen species (ROS) following MRSA challenge, an effect independent of the angiotensin II AT1 receptor. Specifically, as compared with wild-type (WT) mice, there was a marked increase of superoxide generation (>twofold, P < .0005) in NeuACE neutrophils following infection, whereas ACE knockout neutrophils decreased superoxide production. Analysis of membrane p47-phox and p67-phox indicates that ACE increases reduced NAD phosphate oxidase activity but does not increase expression of these subunits. Increased ROS generation mediates the enhanced bacterial resistance of NeuACE mice because the enhanced resistance is lost with DPI (an inhibitor of ROS production by flavoenzymes) inhibition. NeuACE granulocytes also have increased neutrophil extracellular trap formation and interleukin-1β release in response to MRSA. In a mouse model of chemotherapy-induced neutrophil depletion, transfusion of ACE-overexpressing neutrophils was superior to WT neutrophils in treating MRSA infection. These data indicate a previously unknown function of ACE in neutrophil antibacterial defenses and suggest caution in the treatment of certain individuals with ACE inhibitors. ACE overexpression in neutrophils may be useful in boosting the immune response to antibiotic-resistant bacterial infection.

Fibroblast growth factor (FGF) 23 plays an important role in regulation of renal phosphate excretion in patients with chronic kidney disease. However, it remains undetermined whether FGF23 is closely linked to renal phosphate handling in patients with low glomerular filtration rate (GFR). The present cross-sectional study included 52 outpatients undergoing peritoneal dialysis with urine volume ≥ 100 mL/day. The primary outcome was level of urinary phosphate excretion, and the secondary outcomes were tubular maximal reabsorption of phosphate normalized to GFR (TmP/GFR), an index of the renal threshold for phosphate excretion, and level of peritoneal phosphate excretion. Variates of interest were serum FGF23 and parathyroid hormone (PTH) levels. The median and interquartile range of serum FGF23 level, TmP/GFR, and total urinary and peritoneal phosphate excretion were 5610 (1493–11 430) ng/mL, 1.30 (0.44–1.86) mg/dL, 117 (40–234) mg/day, and 208 (156–250) mg/day, respectively. Multivariate linear regression analysis revealed that serum FGF23 level was significantly (P

Fibroblast growth factor 23 (FGF23) levels in dialysis patients are influenced by various factors, including phosphorus load. However, the clinical parameters that determine serum FGF23 levels in patients on peritoneal dialysis (PD) remain unclear. The aim of the present study was to examine the effects of clinical factors, on serum FGF23 levels, with an emphasis on residual renal function (RRF). This cross-sectional study included 56 outpatients undergoing PD therapy. Urine volume ≥ 100 mL/day or renal creatinine (Cr) clearance was used as a surrogate marker for RRF. Clinical characteristics were compared between patients with and without RRF. Linear regression analysis was conducted with serum FGF23 level as the dependent variable and renal Cr clearance as the main independent variable. The median and interquartile range of serum FGF23 levels were 5970 (1451-11,688) pg/mL. Patients with RRF showed higher urinary and total phosphate eliminations, and lower serum FGF23 and phosphate levels than patients without RRF. Multivariate linear regression analysis showed that the renal Cr clearance and serum phosphate and dialysis history were negatively associated with serum FGF23 levels, even after adjusting for potential confounders including peritoneal Cr clearance. Further, the predictabilities of serum FGF23 were comparable among renal Cr clearance, Kt/V for urea, and renal phosphate clearance. RRF determined by renal Cr clearance or residual urine volume is an independent negative determinant of serum FGF23 levels in PD patients.

Renal parenchymal injury predisposes to salt-sensitive hypertension, but how this occurs is not known. Here we tested whether renal tubular angiotensin converting enzyme (ACE), the main site of kidney ACE expression, is central to the development of salt sensitivity in this setting. Two mouse models were used: it-ACE mice in which ACE expression is selectively eliminated from renal tubular epithelial cells; and ACE 3/9 mice, a compound heterozygous mouse model that makes ACE only in renal tubular epithelium from the ACE 9 allele, and in liver hepatocytes from the ACE 3 allele. Salt sensitivity was induced using a post L-NAME salt challenge. While both wild-type and ACE 3/9 mice developed arterial hypertension following three weeks of high salt administration, it-ACE mice remained normotensive with low levels of renal angiotensin II. These mice displayed increased sodium excretion, lower sodium accumulation, and an exaggerated reduction in distal sodium transporters. Thus, in mice with renal injury induced by L-NAME pretreatment, renal tubular epithelial ACE, and not ACE expression by renal endothelium, lung, brain, or plasma, is essential for renal angiotensin II accumulation and salt-sensitive hypertension.