Effect of Low-Density Lipoprotein Apheresis on Quality of Life in Patients with Diabetes, Proteinuria, and Hypercholesterolemia.

INTRODUCTION: Treating diabetic nephropathy with low-density lipoprotein (LDL) apheresis reduces proteinuria and improves prognosis. However, its impact on patients' quality of life (QoL) is unclear. This study evaluated the effect of LDL apheresis on QoL in patients with diabetes, proteinuria, and hypercholesterolemia. METHODS: In this nationwide multicenter prospective study, we enrolled 40 patients with diabetes. Inclusion criteria were proteinuria (defined as an albumin/creatinine ratio ≥3 g/g), serum creatinine levels <2 mg/dL, and serum LDL ≥120 mg/dL despite drug treatment. LDL apheresis was performed 6-12 times within 12 weeks. The 36-item Short Form Health Survey (SF-36) was used to analyze QoL. RESULTS: The study enrolled 35 patients (27 men and 8 women; mean age 58.9 ± 11.9 years). A comparison of baseline SF-36 values with those at the end of the course of apheresis found an improvement in the mean physical component summary (37.9 ± 11.4 vs. 40.6 ± 10.5, p = 0.051) and a significant increase in the mean mental component summary (MCS) (49.4 ± 8.4 vs. 52.5 ± 10.9, p = 0.026). A multivariable linear regression analysis revealed a history of coronary heart disease negatively correlated with the MCS increase at the end of the course of apheresis (ß coefficient -6.935, 95% confidence interval, 13.313 to-0.556, p = 0.034). CONCLUSION: Our results suggest that LDL apheresis may improve the mental and physical QoL in patients with diabetes, proteinuria, and hypercholesterolemia.

Light and heavy chain deposition disease with focal amyloid deposition diagnosed with mass spectrometry: a case report.

BACKGROUND: Light and heavy chain deposition disease (LHCDD) is a rare condition characterised by the deposition of immunoglobulin components in the kidneys. Similarly, Amyloidosis is also caused by the deposition of light chain and/or heavy chain components of immunoglobulins which are folded into amyloid fibrils characterised by Congophilic deposits that exhibit apple-green birefringence under polarised light. Only a handful of reports describing LHCDD with amyloid fibril deposition have been previously published, however, none have characterized the composition of the deposited immunoglobulin components via mass spectrometry. CASE PRESENTATION: We report a case of a 79-year-old Japanese woman with nephrotic syndrome. Bone marrow aspiration revealed a slight proliferation of plasma cells (under 10%). Immunofluorescence assessment of renal biopsy showed amyloid-like deposits in the glomerulus that were positive for IgA and kappa. Further, the Congo red staining of the deposits was faintly positive, and only a slight birefringence was detected. Electron microscopy confirmed fine fibrillar structures and non-amyloid deposits. Finally, mass spectrometry revealed that the deposits were composed of abundant amounts of light chain with small amounts of heavy chain. Therefore, the patient was diagnosed with LHCDD and focal amyloid deposition. Chemotherapy was subsequently initiated, which resulted in haematological and renal response. Under polarised light, faint birefringence with Congo red staining and periodic acid-methenamine silver positivity indicated that the deposits were mostly non-amyloid fibrils with a small component of amyloid fibrils. Generally, the diagnosis of heavy- and light-chain amyloidosis is defined by greater heavy chain deposition compared to the light chain. However, in our case, contrary to the definition, the light-chain deposition was far greater than that of the heavy-chain. CONCLUSIONS: This is the first case of LHCDD with focal amyloid deposition diagnosed by analysing the glomerular deposits by mass spectrometry.

Posterior reversible encephalopathy syndrome (PRES) associated with SARS-CoV-2 infection in a patient under maintenance haemodialysis: a case report.

BACKGROUND: Endothelial dysfunction is common in patients undergoing chronic haemodialysis, and is a major cause of posterior reversible encephalopathy syndrome (PRES). Recently, Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has been shown to cause endothelial dysfunction by infecting vascular endothelial cells. Several cases of neurological complications in patients without kidney dysfunction, and only a few cases in patients with chronic kidney disease, have been reported in the literature. However, no previous report has yet described PRES associated with SARS-CoV-2 infection among patients undergoing maintenance dialysis. CASE PRESENTATION: A 54-year-old woman undergoing maintenance haemodialysis was admitted to our hospital for status epilepticus. She had developed end-stage kidney disease (ESKD) secondary to diabetic nephropathy. Seven days prior to admission, she had developed fever and was diagnosed with COVID-19. Subsequently her blood pressure increased from 160/90 mmHg to 190/100 mmHg. On admission, she presented with severe hypertension (> 220/150 mmHg), unconsciousness, and epilepticus. CT tomography revealed no signs of brain haemorrhage. Cranio-spinal fluid (CSF) examination revealed no signs of encephalitis, and CSF polymerase chain reaction (PCR) for SARS-CoV-2 was negative. MRI findings revealed focal T2/FLAIR hyperintensity in the bilateral parietooccipital regions, leading to the diagnosis of PRES. Deep sedation and strict blood pressure control resulted in a rapid improvement of her symptoms, and she was discharged without sequelae. CONCLUSIONS: We report the first case of PRES associated with SARS-CoV-2 infection in a patient undergoing maintenance haemodialysis. Patients undergoing maintenance haemodialysis are at high risk of PRES because of several risk factors. SARS-CoV-2 infection causes direct invasion of endothelial cells by binding to angiotensin-converting enzyme 2 (ACE2), initiating cytokine release, and hypercoagulation, leading to vascular endothelial cell injury and increased vascular leakage. In the present case, SARS-CoV-2 infection possibly be associated with the development of PRES.

PPAR-δ activation reduces cisplatin-induced apoptosis via inhibiting p53/Bax/caspase-3 pathway without modulating autophagy in murine renal proximal tubular cells.

BACKGROUND: Cisplatin-induced injury of renal proximal tubular cells results basically from increased apoptosis via mitochondrial damage, and is mitigated by appropriate enhancement of autophagy. Peroxisome proliferator-activated receptor-delta (PPAR-δ) reportedly protects against not only mitochondrial damages but also enhances autophagy. Thus, PPAR-δ may protect against cisplatin-induced kidney injury. METHODS: We examined the protective effects of PPAR-δ activation on cisplatin-induced cellular injury and their detailed mechanisms in a murine renal proximal tubular (mProx) cell line using GW0742, an authentic PPAR-δ activator. Cisplatin-induced cell damages were evaluated by TUNEL assay and immunoblot analyses for p53, 14-3-3, Bax, Bcl2, cytochrome C, and activated caspases. Autophagy status was examined by immunoblot analyses for p62 and LC3. RESULTS: GW0742 suppressed cisplatin-induced apoptosis of mProx cells by reducing the activation of caspase-3 via attenuating the phosphorylation of p53 and 14-3-3, mitochondrial Bax accumulation, cytochrome C release from mitochondria to the cytosol and ensuing cytosolic caspase-9 activation. In contrast, GW0742 did not diminish cisplatin-enhanced activation of caspases-8 or -12 as extrinsic or endothelium reticulum apoptotic pathways, respectively. The inhibitory effect of GW0742 on cisplatin-induced caspase-3 activation was significantly diminished by silencing of the PPAR-δ gene expression. GW0742 itself had no influence on starvation-stimulated or cisplatin-induced autophagy in mProx cells, suggesting that the protective effects were not mediated by autophagy modification. CONCLUSION: Our results indicate that GW0742 may serve as a candidate agent to mitigate cisplatin nephrotoxicity via inhibiting the mitochondrial apoptotic pathway considerably depending on PPAR-δ, without modulating autophagy.

Effects of LDL apheresis on proteinuria in patients with diabetes mellitus, severe proteinuria, and dyslipidemia.

BACKGROUND: Patients with diabetes mellitus and severe proteinuria present with poor renal prognoses, despite improvements in diabetes and kidney disease therapies. In this study, we designed a low-density lipoprotein (LDL)-cholesterol apheresis treatment for patients with diabetic nephropathy (DN)/diabetic kidney disease and severe proteinuria. This was a multicenter prospective LICENSE study to confirm the impact of LDL apheresis on proteinuria that exhibited hyporesponsiveness to treatment. In addition, we sought to determine the efficacy and safety of LDL apheresis by comparing the outcomes to those of historical controls in patients with diabetes, refractory hypercholesterolemia, and severe proteinuria. METHODS: This was a prospective, multicenter study, including 40 patients with diabetes, severe proteinuria, and dyslipidemia. LDL apheresis was performed 6-12 times over a 12-week period. The primary endpoint was the proportion of patients with a decrease in proteinuria excretion of at least 30% in the 6 months after starting therapy. The secondary endpoints included serum creatinine levels and laboratory variables, which were evaluated 4, 6, 12, 18, and 24 months after therapy initiation. RESULTS: LDL apheresis was performed on 40 registered patients with diabetes. The proportion of cases in which proteinuria decreased by 30% or more after 6 months of LDL apheresis was 25%, which was similar to that of historical controls. The overall survival and end-stage kidney disease-free survival rates were significantly higher in the LICENSE group compared to those in historical controls. CONCLUSION: Our results suggest that LDL apheresis may be effective and safe for patients with diabetes, proteinuria, and dyslipidemia. TRIAL REGISTRATION: Trial registration number: jRCTs042180076.

Chronic hypoxia exacerbates diabetic glomerulosclerosis through mesangiolysis and podocyte injury in db/db mice.

BACKGROUND: Chronic hypoxia may play a pivotal role in the development of diabetic nephropathy (DN). However, the precise mechanisms underlying progressive hypoxia-induced glomerular injury remain unclear. METHODS: We housed db/db mice in a hypoxia chamber (12% O2) for up to 16 weeks beginning at 8 weeks of age. Various urine, serum and kidney abnormalities and glomerular messenger RNA (mRNA) expression were compared with those in age-matched db/db mice housed under normoxia. RESULTS: Levels of urinary albumin and podocalyxin (PCX) were significantly higher in hypoxic mice early during hypoxia. Ultracentrifugation of urine samples revealed that podocytes in the hypoxic mice shed PCX-positive microparticles into the urine. After 16 weeks of hypoxia, the mice also had higher hematocrits with lower serum glucose and various degrees of mesangiolytic glomerulosclerosis with microaneurysms and the infrequent occurrence of nodular lesions. Immunohistologically, hypoxic mice showed significantly decreased endothelial cell densities early during hypoxia and decreased podocyte densities later. In both hypoxic and normoxic mice, glomerular macrophage and transforming growth factor-ß1 (TGF-ß1) staining significantly increased with aging, without changes in vascular endothelial growth factor or endothelial nitric oxide synthase (eNOS). Glomerular mRNA expression of monocyte chemoattractant protein-1, eNOS and TGF-ß1 was significantly enhanced in the hypoxic mice. CONCLUSIONS: These results indicate that chronic hypoxia induces advanced glomerulosclerosis with accelerated albuminuria triggered by mesangiolysis and podocyte injury in a murine model of DN.

Rationale and study design of a clinical trial to assess the effects of LDL apheresis on proteinuria in diabetic patients with severe proteinuria and dyslipidemia.

BACKGROUND: Diabetic nephropathy is a leading cause of end-stage kidney disease in the world. Although various types of treatment for diabetes, hypertension and dyslipidemia have improved prognosis and quality of life in patients with diabetic nephropathy, there still exist some diabetic patients with severe proteinuria showing poor prognosis. This clinical trial, LICENSE, aims to confirm the impact of LDL apheresis on proteinuria exhibiting hyporesponsiveness to treatment. METHODS: This ongoing trial is a multicenter, prospective study of diabetic patients with severe proteinuria. The objective is to examine the impact of LDL apheresis on proteinuria in patients with diabetic nephropathy. The other subject is to investigate safety of LDL apheresis in these patients. RESULTS: The subjects consist of diabetic patients with serum creatinine (Cr) levels below 2 mg/dL who present severe proteinuria above 3 g/g Cr or 3 g/day and LDL cholesterol above 120 mg/dL. The target number of registered patients will be 35 patients. Urinary protein excretion and renal function will be observed for 24 weeks after the treatment of LDL apheresis. CONCLUSION: This study will determine the effectiveness and safety of LDL apheresis for diabetic nephropathy patients with severe proteinuria and dyslipidemia.

Tubulointerstitial Nephritis with IgM-Positive Plasma Cells.

Infiltration by IgG-positive plasma cells is a common finding in tubulointerstitial nephritis. Indeed, it has been thought that CD138-positive mature plasma cells secrete mainly IgG, and the occurrence of tubulointerstitial nephritis with CD138-positive plasma cells secreting IgM has rarely been reported. Routine immunofluorescence of fresh frozen sections is considered the gold standard for detection of immune deposits. However, the immunoenzyme method with formalin-fixed, paraffin-embedded sections is superior for detecting IgM- or IgG-positive cells within the renal interstitium, thus histologic variants may often go undetected. We recently discovered a case of tubulointerstitial nephritis showing IgM-positive plasma cell accumulation within the interstitium. To further explore the morphologic and clinical features of such cases, we performed a nationwide search for patients with biopsy-proven tubulointerstitial nephritis and high serum IgM levels. We identified 13 patients with tubulointerstitial nephritis and IgM-positive plasma cell infiltration confirmed with the immunoenzyme method. The clinical findings for these patients included a high prevalence of distal renal tubular acidosis (100%), Fanconi syndrome (92%), and anti-mitochondrial antibodies (82%). The pathologic findings were interstitial nephritis with diffusely distributed CD3-positive T lymphocytes and colocalized IgM-positive plasma cells, as well as tubulitis with CD3-positive T lymphocytes in the proximal tubules and collecting ducts. Additionally, levels of H+-ATPase, H+, K+-ATPase, and the HCO3--Cl- anion exchanger were markedly decreased in the collecting ducts. We propose to designate this group of cases, which have a common histologic and clinical form, as IgM-positive plasma cell-tubulointerstitial nephritis.

Short-chain fatty acids, GPR41 and GPR43 ligands, inhibit TNF-α-induced MCP-1 expression by modulating p38 and JNK signaling pathways in human renal cortical epithelial cells.

Short-chain fatty acids (SCFAs), such as acetate, propionate, and butyrate, are produced predominantly by gut microbiota fermentation of dietary fiber. SCFAs are newly identified as endogenous ligands of two orphan G protein-coupled receptors, GPR41 and GPR43, which have the potential to modulate inflammation. Therefore, GPR41 and GPR43 may mediate the link between the gut microbiome status and various disease conditions including renal inflammation. This study aimed at investigating whether SCFAs activate GPR41 and GPR43, and thereby exert anti-inflammatory effects in human renal cortical epithelial cells (HRCEs) as a main component of kidney tissue. Immunohistochemical analyses of human renal biopsy specimens revealed the expression of GPR41 and GPR43 protein in the distal renal tubules and collecting tubules. TNF-α increased the expression of monocyte chemoattractant protein-1 (MCP-1), a potential fibrotic inducer, at least partly via enhancing phosphorylation of p38 and JNK in HRCEs. SCFAs, especially propionate, attenuated TNF-α- stimulated MCP-1 expression by inhibiting the phosphorylation of p38 and JNK. This inhibitory effect was considerably attenuated by an inactivator of the Gi/o-type G protein and a Gßγ (i/o) blocker, but not by a Gα (i/o) blocker. Furthermore, SCFA-mediated inhibition of MCP-1 expression was significantly blocked by siRNA-induced gene silencing of GPR41 and GPR43. In conclusion, SCFAs lowered TNF-α-induced MCP-1 expression by reducing phosphorylation of p38 and JNK in a GPR41/43-dependent manner in HRCEs, suggesting that SCFA modification may be a new therapeutic tool for preventing progression of renal inflammation and fibrosis.

A heterozygous female with Fabry disease due to a novel α-galactosidase A mutation exhibits a unique synaptopodin distribution in vacuolated podocytes.

We report the case of a 42-yearold woman diagnosed with heterozygous Fabry disease (FD) due to a novel α-galactosidase A Pro210Ser mutation and exhibiting a unique distribution of synaptopodin within podocytes. The patient was referred to our hospital with moderate proteinuria, and a renal biopsy was performed. Light microscopic examination of the specimen revealed diffuse global enlargement of podocytes, which also showed foamy changes. Electron microscopy revealed abundant myeloid bodies in podocytes and focal mitochondrial abnormalities within the tubules. The patient exhibited none of the characteristic symptoms of FD except hypohidrosis and had no obvious family history. Genetic analysis revealed a novel missense mutation (Pro210Ser) in the α-galactosidase A gene. She was ultimately diagnosed with FD based on immunohistochemical staining indicating large amounts of accumulated globotriaosylceramide in her podocytes, detection of urinary globotriaosylceramide secretion using high-performance thin-layer chromatography/ immunostaining, and structural modeling of the mutated α-galactosidase A (Pro210Ser). Immunostaining of the swollen and foamy podocytes using podocyte-associated antibodies (against podocalyxin, Wilms tumor-1, vimentin, and synaptopodin) revealed a unique distribution of synaptopodin surrounding globotriaosylceramide. To our knowledge, this is the first report of immunohistologically detected synaptopodin upregulation in foamy podocytes in a patient with FD.

Gender- and disease-specific urinary thioredoxin in chronic kidney disease patients with or without type 2 diabetic nephropathy.

AIM: The role of urinary (U-) thioredoxin (Trx), a class of small redox proteins, in physiological and pathological conditions, in addition to its gender specificity, has been insufficiently determined in chronic kidney disease (CKD) patients, especially in diabetes mellitus (DM) nephropathy. METHODS: U-Trx was measured cross-sectionally in 110 CKD outpatients with estimated glomerular filtration rate (eGFR) of >15 mL/min per 1.73 m(2) , namely, in 57 type 2 DM patients (male: n = 41, female: n = 16) and 53 non-DM patients (M: n = 33, F: n = 20), as well as 30 healthy controls (M: n = 11, F: n = 19). Comparisons were made among controls, DM and non-DM, and between M and F, with clinical parameters compared in each group. In addition, a comparison between average U-Trx level and the changes of renal function during a one-year period was performed. RESULTS: U-Trx was significantly higher in females than in males in controls (P < 0.05) and in non-DM patients (P < 0.05). Multiple regression analysis revealed that urinary protein (UP)/creatinine (Cr) ratio, female sex and HbA1c were independent factors affecting U-Trx among all subjects (adjusted R(2) = 0.468). In DM patients, U-Trx was negatively correlated with eGFR, especially in males, and positively correlated with UP/Cr and NAG in both sexes (all P < 0.01), as well as with systolic blood pressure in all (P < 0.05). Average U-Trx was positively correlated with the rate of annual eGFR decline of male (P < 0.01) but not female DM patients. CONCLUSION: U-Trx might have a gender-specific physiological and pathological role and be a potent marker of renal damage in DM nephropathy.

Renal redox dysregulation in AKI: application for oxidative stress marker of AKI.

Oxidative stress is a major determinant of acute kidney injury (AKI); however, the effects of an AKI on renal redox system are unclear, and few existing AKI markers are suitable for evaluating oxidative stress. We measured urinary levels of the redox-regulatory protein thioredoxin 1 (TRX1) in patients with various kinds of kidney disease and in mice with renal ischemia-reperfusion injury. Urinary TRX1 levels were markedly higher in patients with AKI than in those with chronic kidney disease or in healthy subjects. In a receiver operating characteristic curve analysis to differentiate between AKI and other renal diseases, the area under the curve for urinary TRX1 was 0.94 (95% confidence interval, 0.90-0.98), and the sensitivity and specificity were 0.88 and 0.88, respectively, at the optimal cutoff value of 43.0 µg/g creatinine. Immunostaining revealed TRX1 to be diffusely distributed in the tubules of normal kidneys, but to be shifted to the brush borders or urinary lumen in injured tubules in both mice and humans with AKI. Urinary TRX1 in AKI was predominantly in the oxidized form. In cultured human proximal tubular epithelial cells, hydrogen peroxide specifically and dose dependently increased TRX1 levels in the culture supernatant, while reducing intracellular levels. These findings suggest that urinary TRX1 is an oxidative stress-specific biomarker useful for distinguishing AKI from chronic kidney disease and healthy kidneys.

Telmisartan, a possible PPAR-δ agonist, reduces TNF-α-stimulated VEGF-C production by inhibiting the p38MAPK/HSP27 pathway in human proximal renal tubular cells.

Vascular endothelial growth factor-C (VEGF-C) is a main inducer of inflammation-associated lymphangiogenesis in various inflammatory disorders including chronic progressive kidney diseases, for which angiotensin II receptor type 1 blockers (ARBs) are widely used as the main treatment. Although proximal renal tubular cells may affect the formation of lymphatic vessels in the interstitial area by producing VEGF-C, the molecular mechanisms of VEGF-C production and its manipulation by ARB have not yet been examined in human proximal renal tubular epithelial cells (HPTECs). In the present study, TNF-α dose-dependently induced the production of VEGF-C in HPTECs. The TNF-α-induced production of VEGF-C was mediated by the phosphorylation of p38MAPK and HSP27, but not by that of ERK or NFkB. Telmisartan, an ARB that can activate the peroxisome proliferator-activated receptor (PPAR), served as a PPAR-δ activator and reduced the TNF-α-stimulated production of VEGF-C. This reduction was partially attributed to a PPAR-δ-dependent decrease in p38MAPK phosphorylation. Our results indicate that TNF-α induced the production of VEGF-C in HPTECs by activating p38MAPK/HSP27, and this was partially inhibited by telmisartan in a PPAR-δ dependent manner. These results provide a novel insight into inflammation-associated lymphangiogenesis.

Anti-Clogging Effect of Continuous Hemodiafiltration With Blood Recirculation.

Pediatric dialysis requires low flow from the body, but greater flow is needed to prevent clogging. As a solution, we developed a new continuous hemodiafiltration system with blood recirculation (CHDF-R), which enables separate settings for blood flow from the body and to the hemofilter. We compared CHDF-R with conventional continuous hemodiafiltration (CHDF) of bovine plasma and blood by monitoring the transmembrane pressure (TMP) and observing the hemofilter membrane surface. When using bovine plasma, the postdialysis TMP with CHDF-R was significantly lower than with CHDF (median CHDF, 23.7; median CHDF-R, 18.1; p = 0.029). Likewise, when using bovine blood, the postdialysis TMP was also significantly lower with CHDF-R than with CHDF (median CHDF, 150; median CHDF-R, 100; p = 0.029). Moreover, the area of clogged membrane was significantly smaller with CHDF-R than with CHDF, and the inner membrane surface showed less material deposition with CHDF-R than CHDF. CHDF-R thus appears to suppress accumulation of clogging substances by producing higher shear stress within hollow fiber membranes.

Renoprotective effects of extracellular fibroblast specific protein 1 via nuclear factor erythroid 2-related factor-mediated antioxidant activity.

Podocyte expression of fibroblast specific protein 1 (FSP1) is observed in various types of human glomerulonephritis. Considering that FSP1 is secreted extracellularly and has been shown to have multiple biological effects on distant cells, we postulated that secreted FSP1 from podocytes might impact renal tubules. Our RNA microarray analysis in a tubular epithelial cell line (mProx) revealed that FSP1 induced the expression of heme oxygenase 1, sequestosome 1, solute carrier family 7, member 11, and cystathionine gamma-lyase, all of which are associated with nuclear factor erythroid 2-related factor (Nrf2) activation. Therefore, FSP1 is likely to exert cytoprotective effects through Nrf2-induced antioxidant activity. Moreover, in mProx, FSP1 facilitated Nrf2 translocation to the nucleus, increased levels of reduced glutathione, inhibited the production of reactive oxygen species (ROS), and reduced cisplatin-induced cell death. FSP1 also ameliorated acute tubular injury in mice with cisplatin nephrotoxicity, which is a representative model of ROS-mediated tissue injury. Similarly, in transgenic mice that express FSP1 specifically in podocytes, tubular injury associated with cisplatin nephrotoxicity was also mitigated. Extracellular FSP1 secreted from podocytes acts on downstream tubular cells, exerting renoprotective effects through Nrf2-mediated antioxidant activity. Consequently, podocytes and tubular epithelial cells have a remote communication network to limit injury.

Fanconi syndrome in an elderly patient with membranous nephropathy during treatment with the immunosuppressant mizoribine.

We report on an 80-year-old man diagnosed with Fanconi syndrome induced by mizoribine after 4 weeks of administration to treat membranous nephropathy. Mizoribine is an oral immunosuppressant that inhibits inosine monophosphate dehydrogenase and is widely used in Japan for the treatment of autoimmune diseases and nephrotic syndrome, as well as after renal transplantation. Acquired Fanconi syndrome is often caused by drugs (antibacterial, antiviral, anticancer, and anticonvulsant drugs) and is sometimes caused by autoimmune diseases, monoclonal light chain-associated diseases, or heavy metal poisoning. In our patient, hypokalemia, hypophosphatemia, glucosuria, hypouricemia, and severe proteinuria resolved gradually after discontinuation of mizoribine administration, despite oral administration of prednisolone followed by a single intravenous injection of rituximab. The patient was ultimately diagnosed with Fanconi syndrome induced by mizoribine based on his clinical course and his typical laboratory data with the absence of proximal tubular acidosis. To our knowledge, this is the first report of Fanconi syndrome possibly induced by mizoribine. Although the precise mechanism by which mizoribine induces proximal tubular dysfunction is unknown, we suggest that nephrologists should be aware of the onset of Fanconi syndrome, a rare complication during mizoribine treatment.

Feasibility of Renal Blood Flow Measurement Using 64Cu-ATSM PET/MRI: A Quantitative PET and MRI Study.

This study aimed to evaluate the renal blood flow (RBF) in patients with chronic kidney disease (CKD) using 64Cu(II)-diacetyl-bis(4-methylthiosemicarbazonate) (64Cu-ATSM) for positron emission tomography (PET)/magnetic resonance imaging (MRI). We included five healthy controls (HCs) and ten patients with CKD. The estimated glomerular filtration rate (eGFR) was calculated from the serum creatinine (cr) and cystatin C (cys) levels. The estimated RBF (eRBF) was calculated using the eGFR, hematocrit, and filtration fraction. A single dose of 64Cu-ATSM (300-400 MBq) was administered for RBF evaluation, and a 40 min dynamic PET scan was performed with simultaneous arterial spin labeling (ASL) imaging. PET-RBF images were obtained from the dynamic PET images at 3 min after injection using the image-derived input function method. The mean eRBF values calculated from various eGFR values differed significantly between the patients and HCs; both groups also differed significantly in terms of the RBF values (mL/min/100 g) measured using PET (151 ± 20 vs. 124 ± 22, p < 0.05) and ASL-MRI (172 ± 38 vs. 125 ± 30, p < 0.001). The ASL-MRI-RBF was positively correlated with the eRBFcr-cys (r = 0.858, p < 0.001). The PET-RBF was positively correlated with the eRBFcr-cys (r = 0.893, p < 0.001). The ASL-RBF was positively correlated with the PET-RBF (r = 0.849, p < 0.001). 64Cu-ATSM PET/MRI demonstrated the reliability of PET-RBF and ASL-RBF by comparing them with eRBF. This is the first study to demonstrate that 64Cu-ATSM-PET is useful for assessing the RBF and is well correlated with ASL-MRI.

Severe intraglomerular detachment of podocytes in a Gitelman syndrome patient.

We report the case of a 38-year-old woman diagnosed with Gitelman syndrome. A kidney biopsy showed abundant floating cells in the Bowman's space of the mildly cystic glomeruli, moderate tubulointerstitial changes and apparent intimal thickening of small arteries. These floating cells were immunohistologically identified as podocytes, by the expression of podocalyxin, vimentin, Wilms' tumor 1, synaptopodin and nephrin with positivities of 100%, 88.4%, 80.4%, 74.7% and 22.6%, respectively. In these phenotypes, nephrin expression was notably decreased in both detached and capillary-attached podocytes in comparison with normal control podocytes. Immunostaining of both detached and capillary-attached podocytes for Bax, Bcl-2, desmin, fibroblast-specific protein-1, α-smooth muscle actin and Ki-67 was negative, as were TUNEL assays. These results suggest that apoptosis and epithelial-mesenchymal transition were not the main cause of podocyte detachment in this patient. In addition, levels of urinary podocalyxin were not elevated, suggesting the detached podocytes were not excreted in the urine. To the best of our knowledge, this is the first report of severe intraglomerular non-apoptotic detachment of podocytes in Gitelman syndrome. This podocyte detachment may be associated with nephron obstruction and reduced nephrin expression.

SIRT1 deacetylates APE1 and regulates cellular base excision repair.

Apurinic/apyrimidinic endonuclease-1 (APE1) is an essential enzyme in the base excision repair (BER) pathway. Here, we show that APE1 is a target of the SIRTUIN1 (SIRT1) protein deacetylase. SIRT1 associates with APE1, and this association is increased with genotoxic stress. SIRT1 deacetylates APE1 in vitro and in vivo targeting lysines 6 and 7. Genotoxic insults stimulate lysine acetylation of APE1 which is antagonized by transcriptional upregulation of SIRT1. Knockdown of SIRT1 increases cellular abasic DNA content, sensitizing cells to death induced by genotoxic stress, and this vulnerability is rescued by overexpression of APE1. Activation of SIRT1 with resveratrol promotes binding of APE1 to the BER protein X-ray cross-complementing-1 (XRCC1), while inhibition of SIRT1 with nicotinamide (NAM) decreases this interaction. Genotoxic insult also increases binding of APE1 to XRCC1, and this increase is suppressed by NAM or knockdown of SIRT1. Finally, resveratrol increases APE activity in XRCC1-associated protein complexes, while NAM or knockdown of SIRT1 suppresses this DNA repair activity. These findings identify APE1 as a novel protein target of SIRT1, and suggest that SIRT1 plays a vital role in maintaining genomic integrity through regulation of the BER pathway.