Infiltration of M1, but not M2, macrophages is impaired after unilateral ureter obstruction in Nrf2-deficient mice

Chronic inflammation can be a major driver of the failure of a variety of organs, including chronic kidney disease (CKD). The NLR family pyrin domain-containing 3 (NLRP3) inflammasome has been shown to play a pivotal role in inflammation in a mouse kidney disease model. Nuclear factor erythroid 2-related factor 2 (Nrf2), the master transcription factor for anti-oxidant responses, has also been implicated in inflammasome activation under physiological conditions. However, the mechanism underlying inflammasome activation in CKD remains elusive. Here, we show that the loss of Nrf2 suppresses fibrosis and inflammation in a unilateral ureter obstruction (UUO) model of CKD in mice. We consistently observed decreased expression of inflammation-related genes NLRP3 and IL-1β in Nrf2-deficient kidneys after UUO. Increased infiltration of M1, but not M2, macrophages appears to mediate the suppression of UUO-induced CKD symptoms. Furthermore, we found that activation of the NLRP3 inflammasome is attenuated in Nrf2-deficient bone marrow–derived macrophages. These results demonstrate that Nrf2-related inflammasome activation can promote CKD symptoms via infiltration of M1 macrophages. Thus, we have identified the Nrf2 pathway as a promising therapeutic target for CKD

マウス横紋筋融解症誘発性急性腎障害モデルにおけるNrf2活性化の意義の検討

生体は親電子性物質，活性酸素種によって生成される酸化ストレスから生体を保護する応答システムを有している．Keap1（Kelch-like ECH-associated protein 1） -Nrf2（NF-E2 related factor2）システムがこの応答機構において重要な役割を果たす．核内移行したNrf2は転写因子として，NQO1，HO-1などの抗酸化遺伝子群の発現を制御する．　横紋筋融解症による急性腎障害（AKI: Acute Kidney Injury）の機序として，酸化ストレスが尿細管障害に大きく関与する．それ故，横紋筋融解症誘発性AKI においてもNrf2活性化による腎保護効果が期待される．横紋筋融解症誘発性AKI におけるNrf2活性化の意義と治療標的としての可能性を検討した．ヒト近位尿細管上皮細胞（hPTECs）を用いhemin 刺激に対するNrf2活性化の意義を検討した．hemin 刺激によりhPTECs におけるNrf2関連抗酸化遺伝子群の上昇，細胞障害を認めた．Nrf2-siRNA によるNrf2ノックダウン（KD）を行うことでhemin 刺激に対する抗酸化遺伝子群の発現上昇は抑制され，細胞障害が有意に増悪した．野生型マウス （WT），Nrf2欠損マウス（Nrf2KO）を用い，グリセロール筋注による横紋筋融解症モデルを作成した．（１）WT/Cont，（２）WT/ 横紋筋融解症（RM），（３）Nrf2KO/Cont，（４）Nrf2KO/RM の４群で比較検討した．結果は，WT/Cont に比べWT/RM 群で腎機能障害，尿細管障害，マクロファージ浸潤を認め，Nrf2KO/RM 群で有意に増悪した．抗酸化遺伝子群の発現はNrf2KO/RM 群で低下していた．　横紋筋融解症誘発性AKI において，Nrf2活性化が腎保護効果を有する事が示された．横紋筋融解症によるAKI に対して，Nrf2活性化が新たな治療標的となり得ることが明らかとなった．Cells are equipped with cytoprotective systems against oxidative stress caused by reactive oxygen species and electrophilic stress. The Keap1-Nrf2 pathway plays a central role in such mechanisms against oxidative and xenobiotic damage. Nrf2, as a transcription factor, activates a series of genes including NQO1 and HO-1.As the mechanism of acute kidney injury (AKI) due to rhabdomyolysis, renal tubule injury due to oxidative stress is the major component of the pathology. Therefore, in rhabdomyolysisinduced AKI, reno-protective effect of Nrf2 activation is expected. In the present study, the role of Nrf2 activation in rhabdomyolysis-induced AKI was investigated. In vitro, human proximal tubular epithelial cells (hPTECs) were used to determine the significance of Nrf2 for hemin stimulation. Hemin stimulation revealed elevation of Nrf2-related antioxidant gene group and cytotoxicity. Nrf2 knockdown (KD) with Nrf2-siRNA suppressed the rise of the expression of the antioxidant genes against hemin stimulation, and the cell damage was significantly exacerbated. A model of rhabdomyolysis by glycerol intramuscular injection was also prepared in vivo using wild type mice (WT) and Nrf2-deficient mice (Nrf2 KO). These mice were of the C57BL/6J background. We divided them into four groups: (1) WT/Cont, (2) WT/rhabdomyolysis (RM), (3) Nrf2 KO/Cont, and (4) Nrf2 KO/RM. Renal dysfunction and macrophage infiltration occurred more often in the WT/RM than in the WT/Cont, and it significantly worsened in the Nrf2 KO/RM group compared to the WT/RM. The expression of the antioxidant gene group was suppressed more in the Nrf2 KO/RM group compared with the WT/RM.These results indicate that Nrf2 activation exerts reno-protective effect in rhabdomyolysisinduced AKI. Nrf2 activation may be a new therapeutic target for rhabdomyolysis-induced AKI

The Impact of Potassium Binders on Mortality in Patients with Hyperkalemia: A Single-Center Study

Hyperkalemia is associated with an increased risk of mortality and is a common complication in patients with chronic kidney disease (CKD). Despite the prevalence of hyperkalemia, current real-world data suggest that serum potassium levels are not effectively managed in clinical practice. The potential benefit of potassium binders in reducing the risk of death has not been thoroughly investigated. Therefore, this retrospective cohort study aimed to investigate the potential impact of potassium binders on mortality risk in patients with CKD by analyzing electronic medical records. The study included 1689 patients with CKD and hyperkalemia (serum potassium level > 5.0 mEq/L), who visited Kawasaki Medical School Hospital between January 2014 and December 2018. The patients were divided into two groups: those without CPS (calcium polystyrene sulphonate) treatment (CPS_OFF) and those with CPS treatment (CPS_ON). The results showed that the incidence of death was significantly higher in the CPS_OFF group than in the CPS_ON group (22.3% vs. 19.6%, p p = 0.020). These results suggest that potassium binders may reduce the risk of death in patients with CKD and hyperkalemia. We hope that the results of this cohort study will be confirmed in future RCTs

The eNOS-NO pathway attenuates kidney dysfunction via suppression of inflammasome activation in aldosterone-induced renal injury model mice.

Hypertension causes vascular complications, such as stroke, cardiovascular disease, and chronic kidney disease (CKD). The relationship between endothelial dysfunction and progression of kidney disease is well known. However, the relationship between the eNOS-NO pathway and chronic inflammation, which is a common pathway for the progression of kidney disease, remains unexplored. We performed in vivo experiments to determine the role of the eNOS-NO pathway by using eNOS-deficient mice in a hypertensive kidney disease model. All mice were unilateral nephrectomized (Nx). One week after Nx, the mice were randomly divided into two groups: the aldosterone infusion groups and the vehicle groups. All mice also received a 1% NaCl solution instead of drinking water. The aldosterone infusion groups were treated with hydralazine to correct blood pressure differences. After four weeks of drug administration, all mice were euthanized, and blood and kidney tissue samples were collected. In the results, NLRP3 inflammasome activation was elevated in the kidneys of the eNOS-deficient mice, and tubulointerstitial fibrosis was accelerated. Suppression of inflammasome activation by knocking out ASC prevented tubulointerstitial injury in the eNOS knockout mice, indicating that the eNOS-NO pathway is involved in the development of kidney dysfunction through acceleration of NLRP3 inflammasome in macrophages. We revealed that endothelial function, particularly the eNOS-NO pathway, attenuates the progression of renal tubulointerstitial injury via suppression of inflammasome activation. Clinically, patients who develop vascular endothelial dysfunction have lifestyle diseases, such as hypertension or diabetes, and are known to be at risk for CKD. Our study suggests that the eNOS-NO pathway could be a therapeutic target for the treatment of chronic kidney disease associated with endothelial dysfunction

Association of Arterial Stiffness With Kidney Function Among Adults Without Chronic Kidney Disease.

BackgroundOur aims were to assess whether arterial stiffness is associated with a higher risk for kidney dysfunction among persons without chronic kidney disease (CKD).MethodsWe analyzed data from the national health checkup system in Japan; for our analyses, we selected records of individuals who completed assessments of cardio-ankle vascular index (CAVI) and kidney function from 2005 to 2016. We excluded participants who had CKD at baseline, defined as the presence of proteinuria or estimated glomerular filtration rate (eGFR) <60 ml/min/1.73 m2. We compared 2 groups of CAVI measurements-the highest quartile (≧8.1) and the combined lower 3 quartiles (<8.1). We used Cox proportional hazards models to assess associations between these 2 groups and subsequent CKD events, proteinuria, eGFR <60 ml/min/1.73 m2, and rapid eGFR decline (greater than or equal to -3 ml/min/1.73 m2 per year).ResultsThe mean age of the 24,297 included participants was 46.2 years, and 60% were female. Over a mean follow-up of 3.1 years, 1,435 CKD events occurred. In a multivariable analysis, the hazard ratios with 95% confidence intervals (CIs) for the highest vs. combined lower quartiles of CAVI measurements were 1.3 (1.1, 1.5) for CKD events, 1.3 (0.96, 1.62) for proteinuria, 1.4 (1.1, 1.7) for eGFR <60 ml/min/1.73 m2, and the odds ratio with 95% CI was 1.3 (1.1, 1.4) for rapid eGFR decline.ConclusionsPersons with CAVI measurements ≧8.1 had a higher risk for CKD events compared with their counterparts with CAVI measurements <8.1. Greater arterial stiffness among adults without CKD may be associated with kidney dysfunction

Association of Arterial Stiffness With Kidney Function Among Adults Without Chronic Kidney Disease.

BackgroundOur aims were to assess whether arterial stiffness is associated with a higher risk for kidney dysfunction among persons without chronic kidney disease (CKD).MethodsWe analyzed data from the national health checkup system in Japan; for our analyses, we selected records of individuals who completed assessments of cardio-ankle vascular index (CAVI) and kidney function from 2005 to 2016. We excluded participants who had CKD at baseline, defined as the presence of proteinuria or estimated glomerular filtration rate (eGFR) <60 ml/min/1.73 m2. We compared 2 groups of CAVI measurements-the highest quartile (≧8.1) and the combined lower 3 quartiles (<8.1). We used Cox proportional hazards models to assess associations between these 2 groups and subsequent CKD events, proteinuria, eGFR <60 ml/min/1.73 m2, and rapid eGFR decline (greater than or equal to -3 ml/min/1.73 m2 per year).ResultsThe mean age of the 24,297 included participants was 46.2 years, and 60% were female. Over a mean follow-up of 3.1 years, 1,435 CKD events occurred. In a multivariable analysis, the hazard ratios with 95% confidence intervals (CIs) for the highest vs. combined lower quartiles of CAVI measurements were 1.3 (1.1, 1.5) for CKD events, 1.3 (0.96, 1.62) for proteinuria, 1.4 (1.1, 1.7) for eGFR <60 ml/min/1.73 m2, and the odds ratio with 95% CI was 1.3 (1.1, 1.4) for rapid eGFR decline.ConclusionsPersons with CAVI measurements ≧8.1 had a higher risk for CKD events compared with their counterparts with CAVI measurements <8.1. Greater arterial stiffness among adults without CKD may be associated with kidney dysfunction

Distinct characteristics and outcomes in elderly-onset IgA vasculitis (Henoch-Schönlein purpura) with nephritis: Nationwide cohort study of data from the Japan Renal Biopsy Registry (J-RBR)

<div><p>Background</p><p>The clinical presentation and prognosis of adult and elderly patients with IgA vasculitis (Henoch-Schönlein purpura) accompanied by nephritis (IgAV-N) have not been investigated in detail. We therefore surveyed the features and outcomes of IgAV-N based on nationwide data derived from the Japan Renal Biopsy Registry (J-RBR).</p><p>Methods</p><p>This multi-center cohort study compared the clinicopathological parameters at diagnosis, initial therapies and outcomes between 106 adult (age 19–64 years) and 46 elderly (≥65 years) patients with IgAV-N who were registered in the J-RBR between 2007 and 2012. The primary end-points comprised a 50% increase in serum creatinine (sCr) values or end-stage kidney disease. Factors affecting a decrease in renal function were assessed using Cox proportional hazards models.</p><p>Results</p><p>Rates of hypertension, impaired renal function, hypoalbuminemia and crescentic glomerulonephritis were significantly higher among the elderly, than the adult patients. About 80% and 60% of the patients in both groups were respectively treated with corticosteroid and a renin-angiotensin system (RAS) blockade. Both groups had favorable renal survival rates for nine years (93.6% and 91.4% of the adult and elderly patients, respectively). Significantly more elderly than adult patients developed a 50% increase in sCr during a mean observation period of 3.9 years (21.7% vs. 4.7%, p = 0.012), and significantly fewer elderly, than adult patients achieved clinical remission (23.9% vs. 46.2%, p = 0.016). Multivariate analysis selected advanced age (≥65 years) and lower serum albumin values as independent prognostic factors for a decline in renal function, whereas steroid pulse therapy helped to preserve renal function.</p><p>Conclusions</p><p>The renal prognosis of adult and elderly patients with IgAV-N was favorable when treated aggressively with corticosteroid and RAS blockade. However, the course of renal function should be carefully monitored in patients aged over 65 years and those with hypoalbuminemia.</p></div

Comparison of clinicopathological findings at diagnosis and initial treatment between adult and elderly patients with IgAV-N (n = 152).

<p>Comparison of clinicopathological findings at diagnosis and initial treatment between adult and elderly patients with IgAV-N (n = 152).</p