Renal TNFα activates the WNK phosphorylation cascade and contributes to salt-sensitive hypertension in chronic kidney disease.

The inappropriate over-activation of the with-no-lysine kinase (WNK)-STE20/SPS1-related proline/alanine-rich kinase (SPAK)-sodium chloride cotransporter (NCC) phosphorylation cascade increases sodium reabsorption in distal kidney nephrons, resulting in salt-sensitive hypertension. Although chronic kidney disease (CKD) is a common cause of salt-sensitive hypertension, the involvement of the WNK phosphorylation cascade is unknown. Moreover, the effect of immune systems on WNK kinases has not been investigated despite the fact that immune systems are important for salt sensitivity. Here we demonstrate that the protein abundance of WNK1, but not of WNK4, was increased at the distal convoluted tubules in the aristolochic acid nephropathy mouse model of CKD. Accordingly, the phosphorylation of both SPAK and NCC was also increased. Moreover, a high-salt diet did not adequately suppress activation of the WNK1-SPAK-NCC phosphorylation cascade in this model, leading to salt-sensitive hypertension. WNK1 also was increased in adenine nephropathy, but not in subtotal nephrectomy, models of CKD. By comparing the transcripts of these three models focusing on immune systems, we hypothesized that tumor necrosis factor (TNF)-α regulates WNK1 protein expression. In fact, TNF-α increased WNK1 protein expression in cultured renal tubular cells by reducing the transcription and protein levels of NEDD4-2 E3-ligase, which degrades WNK1 protein. Furthermore, the TNF-α inhibitor etanercept reversed the reduction of NEDD4-2 expression and upregulation of the WNK1-SPAK-NCC phosphorylation cascade in distal convoluted tubules in vivo in the aristolochic acid nephropathy model. Thus, salt-sensitive hypertension is induced in CKD via activation of the renal WNK1- SPAK-NCC phosphorylation cascade by TNF-α, reflecting a link with the immune system.

Failure to sense energy depletion may be a novel therapeutic target in chronic kidney disease.

The kidneys consume a large amount of energy to regulate volume status and blood pressure and to excrete uremic toxins. The identification of factors that cause energy mismatch in the setting of chronic kidney disease (CKD) and the development of interventions aimed at improving this mismatch are key research imperatives. Although the critical cellular energy sensor 5'-adenosine monophosphate (AMP)-activated protein kinase (AMPK) is known to be inactivated in CKD, the mechanism of AMPK dysregulation is unknown. In a mouse model of CKD, metabolome analysis confirmed a decrease in AMPK activation in the kidneys despite a high AMP: ATP ratio, suggesting that AMPK did not sense energy depletion. Similar AMPK inactivation was found in heart and skeletal muscle in CKD mice. Several uremic factors were shown to inactivate AMPK in vitro and in ex vivo preparations of kidney tissue. The specific AMPK activator A-769662, which bypasses the AMP sensing mechanism, ameliorated fibrosis and improved energy status in the kidneys of CKD mice, whereas an AMP analog did not. We further demonstrated that a low-protein diet activated AMPK independent of the AMP sensing mechanism, leading to improvement in energy metabolism and kidney fibrosis. These results suggest that a failure to sense AMP is the key mechanism underlying the vicious cycle of energy depletion and CKD progression and direct AMPK activation may be a novel therapeutic approach in CKD.

Low white blood cell count is independently associated with chronic kidney disease progression in the elderly: the CKD-ROUTE study.

BACKGROUND: Elevated white blood cell (WBC) count is a well-known predictor of chronic kidney disease (CKD) progression. However, elderly patients commonly fail to develop a high WBC count in response to several diseased states and may instead present a low WBC count. Therefore, we hypothesized that low WBC count, in addition to high WBC count, is associated with CKD progression in the elderly. METHODS: We conducted a prospective cohort study using 3-year follow-up data from the CKD Research of Outcomes in Treatment and Epidemiology study. In the present study, participants aged over 60 years with pre-dialysis CKD stages G2-G5 were eligible. Patients were stratified into three groups according to WBC count using tertiles (T). The primary outcome was a composite of end-stage renal disease and a 50% reduction in estimated glomerular filtration rate. Data were analyzed using Cox proportional hazard models with adjustments for covariates. RESULTS: We enrolled 697 patients (males, 69%). The median WBC count was 6100 cells/µl (T1, <5400, n =  222; T2, 5400-6900, n =  235; T3, ≥6900, n = 240). During a median follow-up of 868 days, the primary outcome was observed in 170 patients, whereas 54 patients died. T1 and T3 had significantly higher hazard ratios (HR) than T2 (T1, HR 1.69, 95% confidence interval 1.14-2.51; T3, HR 1.63, 95% confidence interval 1.10-2.41). Moreover, T1 had a significantly higher adjusted HR (1.54, 95% confidence interval 1.00-2.37). CONCLUSION: Low WBC count is independently associated with CKD progression in the elderly.

Decreased KLHL3 expression is involved in the pathogenesis of pseudohypoaldosteronism type II caused by cullin 3 mutation in vivo.

BACKGROUND: Pseudohypoaldosteronism type II (PHAII) is a hereditary hypertensive disease caused by mutations in four genes: WNK1, WNK4, Kelch-like3 (KLHL3), and cullin3 (CUL3). Recently, it was revealed that CUL3-KLHL3 E3 ligase complex ubiquitinates WNK1 and WNK4, leading to their degradation, and that a common pathogenesis of PHAII is defective WNK degradation due to CUL3-KLHL3 E3 ligase complex impairment. PHAII-causing CUL3 mutations mediate exon9 skipping, producing a CUL3 protein with a 57-amino acid deletion (Δ403-459). However, the pathogenic effects of KLHL3, an adaptor protein that links WNKs with CUL3, in PHAII caused by CUL3 mutation remain unclear. METHODS: To clarify detailed pathophysiological mechanisms underlying PHAII caused by CUL3 mutation in vivo, we generated and analyzed knock-in mice carrying the same CUL3 exon9 deletion (CUL3WT/Δex9) as that reported in PHAII patients. RESULTS: CUL3WT/Δex9 mice exhibited a PHAII-like phenotype. Interestingly, we confirmed markedly decreased KLHL3 expression in CUL3WT/Δex9 mice by confirming the true KLHL3 band in vivo. However, the expression of other KLHL family proteins, such as KLHL2, was comparable between WT and mutant mice. CONCLUSION: KLHL3 expression was decreased in CUL3WT/Δex9 mice. However, expression levels of other KLHL family proteins were comparable between the wild-type and mutant mice. These findings indicate that the decreased abundance of KLHL3 is a specific phenomenon caused by mutant CUL3 (Δexon9). Our findings would improve our understanding of the pathogenesis of PHAII caused by CUL3 mutation in vivo.

Oral and maxillofacial surgery in patients undergoing dialysis for advanced renal disease: report of five cases.

BACKGROUND: Perioperativemanagement of hemodialysis patients involves many difficulties. High mortality rate and circulatory or respiratory complications in these patients were reported. However, in such reports, there is no concrete information of perioperative management in hemodialysis patients to prevent surgical complications and successful outcomes. CASE PRESENTATION: We retrospectively reviewed the cases of 5 hemodialysis patients who underwent oral surgery under general anesthesia between January 2005 and December 2017. Primary disease was oral squamous cell carcinoma (SCC) in 4 patients and mandibular ameloblastoma in 1 patient. Partial resection was performed in 2 cases, neck dissection in 1 case. Two cases underwent surgery including vascularized reconstruction. The patients were dialyzed the day before and after surgery for the control of fluid and electrolyte status. Patients received intraoperative and postoperative intravenous infusion of potassium-free solution at 20-40 mL/h. Erythropoiesis-stimulating agents (ESAs) were used on the day of hemodialysis during hospitalization. Nafamostat mesilate as an anticoagulant during hemodialysis were used from postoperative day (POD)1 to 7. From POD 1 to 10, cephalosporin as prophylactic antibiotics is adjusted to quarter from half the initial dose. The resuming time of oral intake was similar to that of other oral surgery patients without kidney disease. The daily intake limits of protein, salt and liquid were managed during hospitalization and no cases suffered from malnutrition. No cardiorespiratory complications occurred during the perioperative period. In a case of vascularized osteocutaneous scapular flap reconstruction, grafted scapular bone survived and scapular cutaneous flap necrotized. Necrotic tissue was debrided and split thickness skin was successfully used to cover the grafted scapular bone. CONCLUSIONS: Postoperative better result could be achieved if adequate perioperative management specific to hemodialysis patients is carried out. Vascularized flap reconstruction at oral and maxillofacial region in hemodialysis patients is beneficial treatment. Even if the first flap has wound complication secondary flap reconstruction is success and aesthetically better results could be achieved by the strict wound management and debridement.

WNK4 is indispensable for the pathogenesis of pseudohypoaldosteronism type II caused by mutant KLHL3.

WNK-OSR1/SPAK-NCC signaling cascade is important for regulating salt balance and blood pressure. Activation of WNK-OSR1/SPAK-NaCl cotransporter (NCC) cascade increases sodium reabsorption in the kidney, leading to pseudohypoaldosteronism type II (PHA II) characterized by salt-sensitive hypertension and hyperkalemia. It has been previously demonstrated that the amount of phosphorylated and total NCC markedly decreased in WNK4-/- mice, indicating that WNK4 plays a major role for activation of OSR1/SPAK-NCC signaling. However, it is unclear whether absence of WNK4 can be compensated by other WNK kinases. We recently reported that KLHL3R528H/+ knock-in mice, a PHAII model, exhibited augmented activation of OSR1/SPAK-NCC signaling by increased protein levels of both WNK1 and WNK4 due to impaired protein degradation by the mutant KLHL3. In this study, we sought to determine the contribution of WNK4 to OSR1/SPAK-NCC signaling using an in vivo model which shows extremely increased WNK1 with absence of WNK4. We generated WNK4-/-KLHL3R528H/+ mice and WNK4-/-KLHL3R528H/R528H mice by crossing WNK4-/- mice with KLHL3R528H/+ mice. Thereafter, WNK-OSR1/SPAK-NCC phosphorylation signal cascade was examined in kidneys from these mice. As expected, both WNK4-/-KLHL3R528H/+ mice and WNK4-/-KLHL3R528H/R528H mice demonstrated increased WNK1 in the kidney, due to the KLHL3 mutation, and WNK4 deficiency. However, phosphorylation of SPAK and NCC at distal convoluted tubules were almost completely absent even in WNK4-/-KLHL3R528H/R528H mice. In conclusion, increased WNK1 was unable to compensate for WNK4 deficiency and phosphorylate the NCC, indicating that WNK4 is indispensable for the onset of PHAII.

Selective plasma exchange.

Selective plasma exchange (SePE) is a new modality of simple plasma exchange that uses a selective membrane plasma separator Evacure EC-4A10 (EC-4A) (Kawasumi Laboratories Inc., Tokyo, Japan). EC-4A has a relatively small pore size of 0.03µm, which is around one-tenth that of conventional plasma separators. The sieving coefficients of albumin, immunoglobulin G (IgG), factor XIII (FXIII), and fibrinogen using EC-4A have been shown to be 0.73, 0.5, 0.17, and 0, respectively. Therefore, one session of SePE can remove approximately 50% of IgG regardless of the IgG subclasses while retaining coagulation factors, such as FXIII and fibrinogen. SePE may lower the risk of bleeding when compared with other plasmapheresis modalities. SePE cannot remove large molecular substances, including IgM. When only IgG is targeted by plasmapheresis, SePE is a useful and safe option. When various immunoglobulins are targeted by plasmapheresis, PE can be combined with SePE, which results in both the unspecific removal of pathogens by PE and the retention of coagulation factors by SePE. Careful selection of the modality is important, and when necessary, appropriate plasmapheresis modalities should be combined on the basis of the characteristics and removal kinetics of the pathogenic substances.

Comprehensive genetic testing approach for major inherited kidney diseases, using next-generation sequencing with a custom panel.

BACKGROUND: Gene identification of hereditary kidney diseases by DNA sequencing is important for precise diagnosis, treatment, and genetic consultations. However, the conventional Sanger sequencing is now practically powerless in the face of ever increasing numbers of reported causative genes of various hereditary diseases. The advent of next-generation sequencing technology has enabled large-scale, genome-wide, simultaneous sequence analyses of multiple candidate genes. METHODS: We designed and verified a comprehensive diagnosis panel for approximately 100 major inherited kidney diseases, including 127 known genes. The panel was named Simple, sPEedy and Efficient Diagnosis of Inherited KIdney Diseases (SPEEDI-KID). We applied the panel to 73 individuals, clinically diagnosed with an inherited kidney disease, from 56 families. RESULTS: The panel efficiently covered the candidate genes and allowed a prompt and accurate genetic diagnosis. Moreover, 18 unreported mutations suspected as the disease causes were detected. All these mutations were validated by Sanger sequencing, with 100 % concordance. CONCLUSION: In conclusion, we developed a powerful diagnostic method, focusing on inherited kidney diseases, using a custom panel, SPEEDI-KID, allowing a fast, easy, and comprehensive diagnosis regardless of the disease type.

The use of vitamin D analogs is independently associated with the favorable renal prognosis in chronic kidney disease stages 4-5: the CKD-ROUTE study.

BACKGROUND: Vitamin D analogs have generally been recommended for treatment of mineral bone disease in chronic kidney disease (CKD). However, the association between this treatment and CKD progression has not yet been established. METHODS: We designed a post hoc propensity score-matched cohort analysis derived from 3-year follow-up data of a prospective cohort. Adult participants with pre-dialysis CKD stages 4-5 who had newly been prescribed active vitamin D analogs during the observation period were eligible as matched cases. Then, matched controls were extracted from participants who had never been prescribed active vitamin D analogs. The primary outcome was a composite of end-stage renal disease or a 50 % reduction in estimated glomerular filtration rate (eGFR). A Cox proportional hazards model evaluated the association between the use of vitamin D analogs and the primary outcome. RESULTS: We enrolled 240 patients (males, 65 %). The number of matched cases and controls was 30 and 210, respectively. The primary outcome was observed in 94 patients, whereas 25 patients died. The mean ± standard deviation age and eGFR were 69 ± 12 years and 17 ± 5.7 ml/min/1.73 m2, respectively. In a Cox proportional hazard model, the use of vitamin D analogs was independently associated with a lower risk of the primary outcome (crude hazard ratio 0.41; 95 % confidence interval 0.19, 0.89; adjusted hazard ratio 0.38; 95 % confidence interval 0.17, 0.88). CONCLUSION: The use of vitamin D analogs is independently associated with the preservation of renal function in patients with pre-dialysis CKD stages 4-5.

Association of serum chloride level with mortality and cardiovascular events in chronic kidney disease: the CKD-ROUTE study.

BACKGROUND: Electrolyte abnormalities, particularly dysnatremia, are independent predictors of adverse outcome in individuals with and without renal failure. However, the association of serum chloride level (Cl-) with mortality or risk of cardiovascular (CV) events in chronic kidney disease (CKD) remains unclear. METHODS: This prospective cohort study included 923 pre-dialysis CKD G2-G5 patients among the participants of the CKD Research of Outcomes in Treatment and Epidemiology (CKD-ROUTE) study, who newly visited 16 nephrology centers. The primary outcome was a composite of overall death and CV events, and the secondary outcome was overall death. Data were analyzed using the Cox hazards model with adjustment for potential confounders. RESULTS: Median Cl- was 106.0 mEq/L at enrollment [quartile (Q) 1: ≤103.9, n =  207; Q2: 104.0-105.9, n =  207; Q3: 106.0-108.0, n =  289; Q4: ≥108.1, n = 220]. During a median follow-up of 33 months, there were 98 CV events, 66 deaths, and 154 composite outcomes. The hazard ratio (HR) for the composite outcome was higher for Q1 than Q3 [HR 1.72; 95 % confidence interval (CI) 1.08-2.72; P =  0.022]. As a continuous variable in a subset of patients whose Cl- was ≤106.0 mEq/L, higher Cl- was associated with lower risk of the composite outcome (HR 0.93; 95 % CI 0.87-0.99; P = 0.023). HR for all-cause mortality was also higher for Q1 than Q3 (HR 2.48; 95 % CI 1.22-5.03; P =  0.012). CONCLUSION: Low Cl- was associated with increased mortality and risk of CV events in pre-dialysis CKD patients. Cl- may be an additional prognostic indicator in CKD.

Combination of low body mass index and serum albumin level is associated with chronic kidney disease progression: the chronic kidney disease-research of outcomes in treatment and epidemiology (CKD-ROUTE) study.

BACKGROUND: The relationship between protein-energy wasting and chronic kidney disease (CKD) progression is unknown. In the present prospective cohort study, we evaluated the hypothesis that a combination of low body mass index (BMI) and serum albumin level is associated with rapid CKD progression. METHODS: The study cohort comprised 728 predialysis Japanese patients with CKD (stages 2-5) enrolled from 2010 to 2011. Patients were categorized into four groups according to their serum albumin levels and BMI: group 1, low serum albumin level (<4 g/dL) and low BMI (<23.5 kg/m2); group 2, high serum albumin level (≥4 g/dL) and low BMI; group 3, low serum albumin level and high BMI (≥23.5 kg/m2); and group 4, high serum albumin level and high BMI. The primary outcome was a 30 % decline in estimated glomerular filtration rate (eGFR) or start of dialysis within 2 years. The secondary outcome was an annual GFR decline (mL/min/1.73 m2/year). RESULTS: Logistic regression analysis adjusted for baseline characteristics (reference, group 4) showed that only group 1 was associated with a significant risk of CKD progression, with adjusted odds ratio of 3.51 [95 % confidence interval (CI) (1.63, 7.56)]. A multivariate linear regression analysis adjusted for baseline characteristics showed a significant difference in annual eGFR decline between groups 1 and 4 [coefficients ß (standard error) -2.62 (0.75), p = 0.001]. CONCLUSION: This study suggests that combined effects of low BMI (<23.5 kg/m2) and serum albumin level (<4 g/dL) are associated with CKD progression.

Anaemia management and mortality risk in newly visiting patients with chronic kidney disease in Japan: The CKD-ROUTE study.

AIM: To investigate the association between iron deficiency anaemia and mortality risk and assess the changes in anaemia and iron status after primary management by a nephrologist. METHODS: In this prospective cohort study, we stratified 951 non-dialysis chronic kidney disease (CKD) G2-G5 patients newly visiting 16 nephrology centres into four groups according to the presence of anaemia with or without iron deficiency. All-cause mortality, cardiovascular (CV)-related mortality, and a change in anaemia and iron status after specialized primary care were the endpoints evaluated. RESULTS: During a median follow-up time of 19 months, the number of all-cause deaths and CV-related deaths were 56 and 26, respectively. Compared with the control group, the groups with isolated anaemia and iron deficiency anaemia had significantly higher all-cause mortalities (isolated anaemia: hazard ratio (HR), 3.37; 95% confidence intervals (CI), 1.76-6.44; iron deficiency anaemia: HR, 3.11; 95% CI, 1.21-8.01) and CV-related mortalities (isolated anaemia: HR, 3.64; 95% CI, 1.36-9.73; iron deficiency anaemia: HR, 3.86; 95% CI, 1.11-13.41). In the isolated anaemia group, erythropoietin-stimulating agent (ESA) prescriptions significantly increased to approximately 70%. However, in patients with both anaemia and iron deficiency, iron prescriptions only increased to 48.1%. CONCLUSIONS: Iron deficiency anaemia and isolated anaemia were associated with all-cause and CV-related mortality. The absence of relative increase in iron prescriptions suggests that iron deficiency should be accurately assessed and iron supplementation should be appropriately used to manage anaemia in non-dialysis patients with CKD.

Baseline characteristics and prevalence of cardiovascular disease in newly visiting or referred chronic kidney disease patients to nephrology centers in Japan: a prospective cohort study.

BACKGROUND: About 39,000 patients were newly prescribed renal replacement therapy in Japan in 2011, resulting in a total of more than 300,000 patients being treated with dialysis. This high prevalence of treated end stage kidney disease (ESKD) patients is an emergent problem that requires immediate attention. We launched a prospective cohort study to evaluate population specific characteristics of the progression of chronic kidney disease (CKD). In this report, we describe the baseline characteristics and risk factors for cardiovascular disease (CVD) prevalence among this cohort. METHODS: New patients from 16 nephrology centers who were older than 20 years of age and who visited or were referred for the treatment of CKD stage 2-5, but were not on dialysis therapy, were recruited in this study. At enrollment, medical history, lifestyle behaviors, functional status and current medications were recorded, and blood and urine samples were collected. Estimated glomerular filtration rate (eGFR) was calculated by a modified three-variable equation. RESULTS: We enrolled 1138 patients, 69.6% of whom were male, with a mean age of 68 years. Compared with Western cohorts, patients in this study had a lower body mass index (BMI) and higher proteinuria. The prevalence of CVD was 26.8%, which was lower than that in Western cohorts but higher than that in the general Japanese population. Multivariate analysis demonstrated the following association with CVD prevalence: hypertension (adjusted odds ratio (aOR) 3.57; 95% confidence interval (CI) 1.82-7.02); diabetes (aOR 2.45; 95% CI 1.86-3.23); hemoglobin level less than 11 g/dl (aOR 1.61; 95% CI 1.21-2.15); receiving anti-hypertensive agents (aOR 3.54; 95% CI 2.27-5.53); and statin therapy (aOR 2.73; 95% CI 2.04-3.66). The combination of decreased eGFR and increased proteinuria was also associated with a higher prevalence of CVD. CONCLUSIONS: The participants in this cohort had a lower BMI, higher proteinuria and lower prevalence of CVD compared with Western cohorts. Lower eGFR and high proteinuria were associated with CVD prevalence. Prospective follow up of these study patients will contribute to establishment of individual population-based treatment of CKD.

Severe hyperparathyroidism in a pre-dialysis chronic kidney disease patient treated with a very low protein diet.

The present report describes a case of a 64-year-old pre-dialysis woman with chronic kidney disease (CKD) stage 5, who developed severe hyperparathyroidism. This patient had been on a very low protein diet (VLPD) to delay the progression of CKD and the need for renal replacement therapy (RRT). Her serum calcium levels were high-normal to slightly high during this time. However, her serum intact parathyroid hormone (PTH) levels increased from 400 to 1160 pg/ml rapidly over a period of 3 months. Serum 1,25-(OH)2D levels were low, and ultrasound of the neck showed three markedly enlarged parathyroid glands exceeding 2 cm. Parathyroidectomy was performed, and all glands showed nodular hyperplasia, which indicated severe secondary hyperparathyroidism leading to tertiary. Severe secondary hyperparathyroidism requiring surgical intervention is usually observed in patients with long-term RRT and is relatively rare in the pre-dialysis patient. In this case, extension of the pre-dialysis period by VLPD may have predisposed this patient to develop severe secondary hyperparathyroidism. Thus, careful monitoring of calcium, phosphorus, and PTH may be necessary in patients treated with VLPD even before renal replacement therapy. Furthermore, initiation of dialysis should not be excessively delayed by strict protein restriction dietary therapy.

Effects of sevelamer hydrochloride on mortality, lipid abnormality and arterial stiffness in hemodialyzed patients: a propensity-matched observational study.

BACKGROUND: Cause-and-effect associations between sevelamer hydrochloride (HCl) and mortality have yet to be clarified. The effects of sevelamer HCl on mortality, lipid abnormality and arterial stiffness were examined in patients with chronic kidney disease stage 5D. METHODS: The effects of sevelamer HCl were studied by a single-center cohort study that was conducted from January 1, 2005 to December 31, 2008 (n = 483). By the end of the study, 172 patients (Sevelamer group) had succeeded in continuing sevelamer HCl for >6 months (median 37 months), and 300 patients (Control group) had received calcium carbonate (n = 264) or no phosphate binder (n = 36). The mortality and other outcomes were compared between these two groups after matching by a propensity score calculated using age, gender, diabetes prevalence, and dialysis vintage. RESULTS: All-cause [hazard ratio (HR) 0.4, P = 0.02] and cardiovascular (CV)-cause [HR 0.29, P = 0.03] cumulative mortality were significantly lower in the matched Sevelamer group than in the matched Control group. The matched Sevelamer group showed increased high-density lipoprotein cholesterol (P = 0.003) and no change in pulse wave velocity (PWV) and ankle-brachial index (ABI), whereas the matched Control group showed increased serum low-density lipoprotein (LDL) cholesterol (P = 0.003), increased PWV (P = 0.03), and decreased ABI (P = 0.0009). Change in serum LDL cholesterol level correlated inversely with sevelamer HCl dosage (P = 0.02). CONCLUSIONS: Reduced mortality in patients with sevelamer HCl may, at least in part, be explained by an improvement in dyslipidemia and arterial stiffness by sevelamer HCl.

Generation and analyses of R8L barttin knockin mouse.

Barttin, a gene product of BSND, is one of four genes responsible for Bartter syndrome. Coexpression of barttin with ClC-K chloride channels dramatically induces the expression of ClC-K current via insertion of ClC-K-barttin complexes into plasma membranes. We previously showed that stably expressed R8L barttin, a disease-causing missense mutant, is retained in the endoplasmic reticulum (ER) of Madin-Darby canine kidney (MDCK) cells, with the barttin ß-subunit remaining bound to ClC-K α-subunits (Hayama A, Rai T, Sasaki S, Uchida S. Histochem Cell Biol 119: 485-493, 2003). However, transient expression of R8L barttin in MDCK cells was reported to impair ClC-K channel function without affecting its subcellular localization. To investigate the pathogenesis in vivo, we generated a knockin mouse model of Bartter syndrome that carries the R8L mutation. These mice display disease-like phenotypes (hypokalemia, metabolic alkalosis, and decreased NaCl reabsorption in distal tubules) under a low-salt diet. Immunofluorescence and immunoelectron microscopy revealed that the plasma membrane localization of both R8L barttin and the ClC-K channel was impaired in these mice, and transepithelial chloride transport in the thin ascending limb of Henle's loop (tAL) as well as thiazide-sensitive chloride clearance were significantly reduced. This reduction in transepithelial chloride transport in tAL, which is totally dependent on ClC-K1/barttin, correlated well with the reduction in the amount of R8L barttin localized to plasma membranes. These results suggest that the major cause of Bartter syndrome type IV caused by R8L barttin mutation is its aberrant intracellular localization.

Nationwide in-hospital mortality following major fractures among hemodialysis patients and the general population: An observational cohort study.

BACKGROUNDS: End-stage kidney disease (ESKD) is associated with increased risk of fracture and subsequent morbidity and mortality. However, fracture site-specific mortality in ESKD patients have yet to be elucidated in comparison with the general population. METHODS: In this population-based cohort derived from the Diagnosis Procedure Combination database of Japan from 2012 to 2014, we included 9320 ESKD patients undergoing hemodialysis and 547,726 patients without ESKD who were hospitalized for five major fractures, including hip (proximal femur), spine, forearm, upper arm, and leg (distal femur and proximal tibia). Overall and site-specific risks of in-hospital death were determined by logistic regression models. RESULTS: The age- and sex-adjusted mortality rates were 4.91% (95% confidence interval [CI], 4.46-5.37) and 1.02% (95% CI, 0.99-1.06) in the hemodialysis and general population groups, respectively. The multivariate odds ratio (OR) of death in hemodialysis patients versus the general population was 2.48 (95% CI, 2.25-2.74) for overall fractures, and was particularly high for a subgroup of upper arm fracture (OR 4.82, 95% CI, 3.19-7.28). The site-specific odds of death (95% CI) among hip, spine, forearm, upper arm, and leg (reference) fractures were 1.77 (0.98-3.18), 1.48 (0.79-2.75), 0.19 (0.04-0.86), and 2.01 (1.01-4.01) in hemodialysis patients, and 1.28 (1.13-1.45), 1.00 (0.88-1.14), 0.13 (0.10-0.17), and 0.83 (0.70-0.97) in the general population, respectively. CONCLUSION: Hemodialysis patients experienced a 4.8-fold higher mortality rate after fractures than the general population. Mortality after upper arm fracture was specifically high in patients on hemodialysis, likely due to the involvement of vascular access located on the fractured arm.

Aldosterone-stimulated SGK1 activity mediates profibrotic signaling in the mesangium.

Several recent reports support the hypothesis that aldosterone contributes to the progression of renal injury. Mineralocorticoids increase the expression of serum- and glucocorticoid-inducible protein kinase 1 (SGK1), which is upregulated in several fibrotic diseases. It was hypothesized that SGK1 may mediate the effects of aldosterone on glomerular fibrosis and inflammation. In primary cultures of rat mesangial cells, aldosterone stimulated the expression, phosphorylation, and kinase activity of SGK1, as well as SGK1-dependent NF-kappaB activity. Furthermore, aldosterone augmented the promoter activity and protein expression of intercellular adhesion molecule-1 (ICAM-1), which modulates the inflammatory response, and the profibrotic cytokine connective tissue growth factor (CTGF) in an SGK1- and NF-kappaB-dependent manner. Similar to the in vitro results, uninephrectomized rats that were treated with aldosterone demonstrated increased glomerular expression of SGK1, ICAM-1, and CTGF proteins than untreated rats; these changes were accompanied by hypertension, glomerulosclerosis, and inflammation. In conclusion, these findings suggest that aldosterone stimulates ICAM-1 and CTGF transcription via the activation of SGK1 and NF-kappaB, effects that may contribute to the progression of aldosterone-induced mesangial fibrosis and inflammation.

Removal Characteristics of Immunoadsorption with the Tryptophan-Immobilized Column Using Conventional and Selective Plasma Separators in the Treatment of Myasthenia Gravis.

Autoimmune neurological diseases are often treated by immunoadsorption using a conventional plasma separator and tryptophan-immobilized column (IA). However, there is only one case report on treatment with immunoadsorption using a selective plasma separator and tryptophan-immobilized column (SeIA) in clinical practice. This study aimed to investigate the removal characteristics of antibodies against acetylcholine receptors (AChRAb), immunoglobulin G, fibrinogen, and factor XIII (FXIII) in IA and SeIA in four patients with myasthenia gravis. A total of 19 sessions of immunoadsorption were performed (five sessions of IA and 14 sessions of SeIA) when the processed plasma volume was 2 L. The corresponding reductions were 52.5% ± 6.2% for AChRAb, 58.8% ± 4.2% for fibrinogen, and 36.9% ± 5.5% for FXIII after one session of IA. The corresponding reductions were 45.2% ± 9.9% for AChRAb, 3.5% ± 6.9% for fibrinogen, and -4.6% ± 11.1% for FXIII after one session of SeIA. The removal rates for AChRAb, fibrinogen, and FXIII in IA were significantly higher than those in SeIA. IA could effectively remove AChRAb, and SeIA could retain fibrinogen and FXIII. IA can be combined with SeIA, resulting in both IgG autoantibodies removal by IA and retention of coagulation factors by SeIA.

Encephalopathy Induced by High Plasma and Cerebrospinal Fluid Ceftriaxone Concentrations in a Hemodialysis Patient.

Encephalopathy is a rare side effect of cephalosporin treatment. We herein present a case of encephalopathy induced by ceftriaxone, a third-generation cephalosporin, in a patient with renal failure. An 86-year-old woman on maintenance hemodialysis received ceftriaxone for Helicobacter cinaedi bacteremia. Her mental status deteriorated during antibiotic treatment, and an electroencephalogram revealed triphasic waves predominantly in the frontal area. Her consciousness improved after the discontinuation of the antibiotic due to the suspicion of ceftriaxone-induced encephalopathy. This is the first reported case of encephalopathy associated with high plasma and cerebrospinal fluid ceftriaxone concentrations, and provides significant evidence for a causal relationship between the administration of ceftriaxone and the onset of encephalopathy.