Unusual course of glyphosate-induced acute kidney injury: a case report of tubulointerstitial nephritis treated with steroids.

Glyphosate is a widely used herbicide that is generally considered safe; however, acute kidney injury (AKI) caused by glyphosate ingestion can be severe and require hemodialysis. We present a unique case of a 68-year-old Japanese man who developed AKI after accidental ingestion of glyphosate and required hemodialysis. Based on the clinical presentation and findings, the patient was diagnosed with renal AKI with severe tubulointerstitial damage. However, the precise pathogenesis of the tubulointerstitial damage remained unclear. An elevated beta-2 microglobulin level discovered by the urinalysis during admission raised the suspicion of tubulointerstitial nephritis caused by glyphosate. Gallium scintigraphy revealed accumulation in both kidneys. A renal biopsy revealed acute tubulointerstitial nephritis rather than acute tubular necrosis, which is commonly observed with glyphosate-induced renal injury. After initiating steroid therapy, his kidney function gradually improved and he was weaned from hemodialysis. This report is the first to describe glyphosate-induced acute tubulointerstitial nephritis that was successfully treated with immunosuppressive therapy. Furthermore, this report highlights the importance of steroid therapy for cases of persistent kidney injury after the discontinuation of agents associated with acute tubulointerstitial nephritis.

Development of a Kidney Prognostic Score in a Japanese Cohort of Patients With Antineutrophil Cytoplasmic Autoantibody Vasculitis.

Introduction: Glomerulonephritis is frequent in antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) and crucial to disease outcomes. We conducted a detailed assessment of renal pathology in Japanese patients with AAV, and developed a new score that would predict renal outcome. Methods: Two hundred twenty-one patients who were diagnosed with AAV and underwent a kidney biopsy were enrolled. Data on glomerular, tubular, interstitial, and vascular lesions from kidney biopsies were analyzed; the 3 established classification and prognostic scoring systems (Berden Classification, Mayo Clinic/RPS Chronicity Score [MCCS], and ANCA Renal Risk Score [ARRS]) were validated. Further, we developed a new prognostic score by including variables relevant for Japanese patients with ANCA-glomerulonephritis. Results: Median follow-up was 60 months (interquartile range: 6-60). End-stage kidney disease (ESKD) risk prediction by the MCCS and the ARRS was confirmed. Moreover, our analysis identified 4 items with significant ESKD risk prediction capacity, namely percentage of cellular, fibrocellular, and fibrous crescents; and sclerotic glomeruli. Based on our findings, we created a score evaluating the percentage of these lesions to total glomeruli, the Percentage of ANCA Crescentic Score (PACS). The area under the receiver operating characteristic (ROC) curve evaluating PACS was 0.783. The PACS had a comparable performance as the ARRS in predicting ESKD. The optimal PACS cut-off for ESKD risk over 60 months was 43%. In addition, the percentage of cellular crescents and presence of interstitial inflammation were independent predictors of kidney function recovery. Conclusion: We developed a new score predicting renal prognosis using histopathological data of Japanese patients with ANCA-glomerulonephritis. Studies are needed to validate our results in international cohorts.

Beyond 2D: A scalable and highly sensitive method for a comprehensive 3D analysis of kidney biopsy tissue.

The spatial organization of various cell populations is critical for the major physiological and pathological processes in the kidneys. Most evaluation of these processes typically comes from a conventional 2D tissue cross-section, visualizing a limited amount of cell organization. Therefore, the 2D analysis of kidney biopsy introduces selection bias. The 2D analysis potentially omits key pathological findings outside a 1- to 10-µm thin-sectioned area and lacks information on tissue organization, especially in a particular irregular structure such as crescentic glomeruli. In this study, we introduce an easy-to-use and scalable method for obtaining high-quality images of molecules of interest in a large tissue volume, enabling a comprehensive evaluation of the 3D organization and cellular composition of kidney tissue, especially the glomerular structure. We show that CUBIC and ScaleS clearing protocols could allow a 3D analysis of the kidney tissues in human and animal models of kidney disease. We also demonstrate that the paraffin-embedded human biopsy specimens previously examined via 2D evaluation could be applicable to 3D analysis, showing a potential utilization of this method in kidney biopsy tissue collected in the past. In summary, the 3D analysis of kidney biopsy provides a more comprehensive analysis and a minimized selection bias than 2D tissue analysis. Additionally, this method enables a quantitative evaluation of particular kidney structures and their surrounding tissues, with the potential utilization from basic science investigation to applied diagnostics in nephrology.

IgA Vasculitis as a Potential Complication of Fourth-Line Chemotherapy with Tegafur/Gimeracil/Oteracil (S-1) in Advanced Non-Small Cell Lung Cancer: A Case Report.

BACKGROUND Immunoglobulin A (IgA) vasculitis is a systemic vasculitis that involves the small vessels. It is mainly characterized by skin symptoms such as purpura, arthritis/arthralgia, abdominal symptoms, and nephropathy, which are caused by IgA adherence to the vessel walls. Herein, we report the case of an advanced non-small cell lung cancer (NSCLC) and a purpuric skin rash of the legs that developed during fourth-line chemotherapy with tegafur/gimeracil/oteracil (S-1). CASE REPORT A 68-year-old man diagnosed with NSCLC 2 years ago was undergoing S-1 as fourth-line chemotherapy when he developed purpura and edema on the lower extremities. Biopsy renal specimens were consistent with IgA vasculitis. Considering his medical history, both IgA vasculitis induced by S-1 and a paraneoplastic syndrome were considered, although the exact cause could not be identified. Subsequently, chemotherapy was discontinued because of his deteriorating general condition, and he received optimal supportive care. The purpura spontaneously disappeared; however, his ascites and renal function deteriorated. Systemic steroids improved renal function, but the ascites did not resolve. One month after being diagnosed with IgA vasculitis, the patient died due to deterioration of his general condition. CONCLUSIONS This case emphasizes the occurrence of IgA vasculitis during lung cancer treatment and its potential impact on the disease course of lung cancer. Moreover, the possible causes of IgA vasculitis in this case were paraneoplastic syndrome or S-1 adverse effects, but further case series are needed to gain a more comprehensive understanding. Refractory, steroid-unresponsive ascites may occur as an abdominal manifestation of IgA vasculitis.

Hereditary angioedema with an acute attack resolved after bone marrow transplantation for acute myeloid leukemia: a case report.

BACKGROUND: Hereditary angioedema (HAE), which is caused by C1-inhibitor (C1-INH) deficiency or dysfunction, is a rare and potentially life-threatening disease. In patients with HAE, excess production of bradykinin causes acute unpredictable recurrent attacks of angioedema in localized regions, including the larynx and intestines. Given the fact that HAE is an autosomal dominant disease, C1-INH produced in patients with HAE is 50% of that produced in healthy individuals. However, most patients with HAE present plasma C1-INH function of < 25% owing to the chronic consumption of C1-INH by kallikrein-kinin, contact, complement, coagulation, and fibrinolysis cascades. Recently, several therapeutic options have been developed for acute attacks and prophylaxis in the treatment of HAE; however, currently, there is no curative therapy for HAE. CASE PRESENTATION: Here we report the case of a 48-year-old male patient who presented with a long-standing history of HAE and underwent bone marrow transplantation (BMT) for acute myeloid leukemia (AML) at the age of 39 years and has been in complete remission of AML and HAE thereafter. Notably, after BMT, his C1-INH function gradually increased as follows: < 25%, 29%, 37%, and 45.6%. Since his 20 s, he intermittently presented with an acute attack of HAE once every 3 months from the initial attack. Further, after undergoing BMT, the number of acute attacks decreased to twice within 4 years until the age of 45 years, and subsequently, the patient has been free of acute attacks. C1-INH is mainly synthesized by hepatocytes, but it is known to be partially produced and secreted from peripheral blood monocytes, macrophages, endothelial cells, and fibroblasts. We speculate that the C1-INH function may be increased by extrahepatic production of C1-INH, possibly synthesized by differentiated cells derived from hematopoietic and mesenchymal stem cells after BMT. CONCLUSIONS: This case report supports efforts to focus on extrahepatic production of C1-INH in the next strategy of new treatment development for HAE.

Glomerular expression and urinary excretion of fatty acid-binding protein 4 in IgA nephropathy.

BACKGROUND: Fatty acid-binding protein 4 (FABP4) is secreted from adipocytes and macrophages in adipose tissue and acts as an adipokine. It has recently been reported that FABP4, but not liver-type FABP (L-FABP/FABP1), is also expressed in injured glomerular endothelial cells and infiltrating macrophages in the glomerulus and that urinary FABP4 (U-FABP4) is associated with proteinuria and kidney function impairment in nephrotic patients. However, the link between glomerular FABP4 and U-FABP4 has not been fully addressed in IgA nephropathy (IgAN). METHODS: We investigated the involvement of FABP4 in human and mouse IgAN. RESULTS: In patients with IgAN (n = 23), the ratio of FABP4-positive area to total area within glomeruli (G-FABP4-Area) and U-FABP4 were positively correlated with proteinuria and were negatively correlated with eGFR. In 4-28-week-old male grouped ddY mice, a spontaneous IgAN-prone mouse model, FABP4 was detected in glomerular endothelial cells and macrophages, and G-FABP4-Area was positively correlated with urinary albumin-to-creatinine ratio (r = 0.957, P < 0.001). Endoplasmic reticulum stress markers were detected in glomeruli of human and mouse IgAN. In human renal glomerular endothelial cells, FABP4 was induced by treatment with vascular endothelial growth factor and was secreted from the cells. Treatment of human renal glomerular endothelial cells or mouse podocytes with palmitate-bound recombinant FABP4 significantly increased gene expression of inflammatory cytokines and endoplasmic reticulum stress markers, and the effects of FABP4 in podocytes were attenuated in the presence of an anti-FABP4 antibody. CONCLUSION: FABP4 in the glomerulus contributes to proteinuria in IgAN, and U-FABP4 level is a useful surrogate biomarker for glomerular damage in IgAN.

Dynamin 1 is important for microtubule organization and stabilization in glomerular podocytes.

Dynamin 1 is a neuronal endocytic protein that participates in vesicle formation by scission of invaginated membranes. Dynamin 1 is also expressed in the kidney; however, its physiological significance to this organ remains unknown. Here, we show that dynamin 1 is crucial for microtubule organization and stabilization in glomerular podocytes. By immunofluorescence and immunoelectron microscopy, dynamin 1 was concentrated at microtubules at primary processes in rat podocytes. By immunofluorescence of differentiated mouse podocytes (MPCs), dynamin 1 was often colocalized with microtubule bundles, which radially arranged toward periphery of expanded podocyte. In dynamin 1-depleted MPCs by RNAi, α-tubulin showed a dispersed linear filament-like localization, and microtubule bundles were rarely observed. Furthermore, dynamin 1 depletion resulted in the formation of discontinuous, short acetylated α-tubulin fragments, and the decrease of microtubule-rich protrusions. Dynamins 1 and 2 double-knockout podocytes showed dispersed acetylated α-tubulin and rare protrusions. In vitro, dynamin 1 polymerized around microtubules and cross-linked them into bundles, and increased their resistance to the disassembly-inducing reagents Ca2+ and podophyllotoxin. In addition, overexpression and depletion of dynamin 1 in MPCs increased and decreased the nocodazole resistance of microtubules, respectively. These results suggest that dynamin 1 supports the microtubule bundle formation and participates in the stabilization of microtubules.

A rare case of nephrotic syndrome associated with Dent's disease: a case report.

Dent's disease is a rare X-linked condition caused by a mutation in CLCN5 and OCRL gene, which impair the megalin-cubilin receptor-mediated endocytosis in kidney's proximal tubules. Thus, it may manifest as nephrotic-range low-molecular-weight proteinuria (LMWP). On the other hand, glomerular proteinuria, hypoalbuminemia, and edema formation are the key features of nephrotic syndrome that rarely found in Dent's disease. Here, we reported a man in his 30 s with Dent's disease presented with leg edema for 5 days. The laboratory results revealed hypoalbuminemia and a decrease of urine ß2-microglobulin/urine protein ratio (Uß2-MG /UP), indicating that the primary origin of proteinuria shifted from LMWP to glomerular proteins. The kidney biopsy revealed glomerular abnormality and calcium deposition in the renal medulla. Electron microscopy of the kidney tissue indicated extensive foot-process effacement of the glomerular podocytes and degeneration of tubular epithelium. After a combination of treatment with prednisolone and cyclosporine (CyA), the nephrotic syndrome was remitted. Given the atypical clinical presentation and the shift of LMWP to glomerular proteinuria in this patient, glomerulopathy and the Dent's disease existed separately in this patient.

Neurofilament heavy polypeptide protects against reduction in synaptopodin expression and prevents podocyte detachment.

Podocytes are highly specialized cells that line the glomerulus of the kidney and play a role in filtration. Podocyte injury plays a critical role in the development of many kidney diseases, but the underlying mechanisms remain unclear. In this study, we identified that neurofilament heavy polypeptide (NEFH), an intermediate filament component, protects podocyte from injury. We observed that NEFH was upregulated after ADRIAMYCIN(ADR)-induced podocyte injury in both mice and cultured murine podocytes. Immunofluorescence and co-immunoprecipitation analyses revealed that NEFH was colocalized with synaptopodin, a podocyte-specific marker. High NEFH expression in podocytes prevented the Adriamycin-induced reduction in synaptopodin expression. The siRNA-mediated knockdown of NEFH in podocytes reduced the number of vinculin-containing focal contacts, thereby reducing adhesion to the extracellular matrix and increasing podocyte detachment. In addition, NEFH expression was significantly increased in renal biopsy specimens from patients with focal segmental glomerulosclerosis and membranous nephropathy, but in those with minimal change disease. These findings indicate that NEFH is expressed in podocytes during the disease course and that it prevents the reduction in synaptopodin expression and detachment of podocytes.

Expression of Cathepsin L and Its Intrinsic Inhibitors in Glomeruli of Rats With Puromycin Aminonucleoside Nephrosis.

Cathepsin L, a lysosomal cysteine proteinase, may have a key role in various biological and disease processes by intracellular and extracellular degradation of proteins. We examined the levels of cathepsin L and its intrinsic inhibitors in glomeruli of rats with puromycin aminonucleoside (PAN) nephrosis. In contrast to the weak levels of cathepsin L in normal glomeruli, on days 4 and 8, strong immunostaining was detected in almost all podocytes when proteinuria and pathological changes of the podocytes developed. Cathepsin L was reduced after day 28, but remained in a focal and segmental manner. Cystatin ß, an intracellular inhibitor, was not detected in podocytes. However, cystatin C, an extracellular inhibitor, was detected in podocytes after day 4, coincident with cathepsin L. Cystatin C levels were gradually reduced but sustained in many podocytes on day 28, while cystatin C was not detected in podocytes sustained cathepsin L. These results demonstrated that cathepsin L levels are not always accompanied by the levels of its inhibitors in podocytes of PAN nephrosis, suggesting a potential role of cathepsin L in podocyte injury, which is a critical process for the development and progression of tuft adhesion and sclerosis.

Rac1 in podocytes promotes glomerular repair and limits the formation of sclerosis.

Rac1, a Rho family member, is ubiquitously expressed and participates in various biological processes. Rac1 expression is induced early in podocyte injury, but its role in repair is unclear. To investigate the role of Rac1 expression in podocytes under pathological conditions, we used podocyte-specific Rac1 conditional knock-out (cKO) mice administered adriamycin (ADR), which causes nephrosis and glomerulosclerosis. Larger areas of detached podocytes, more adhesion of the GBM to Bowman's capsule, and a higher ratio of sclerotic glomeruli were observed in Rac1 cKO mice than in control mice, whereas no differences were observed in glomerular podocyte numbers in both groups after ADR treatment. The mammalian target of rapamycin (mTOR) pathway, which regulates the cell size, was more strongly suppressed in the podocytes of Rac1 cKO mice than in those of control mice under pathological conditions. In accordance with this result, the volumes of podocytes in Rac1 cKO mice were significantly reduced compared with those of control mice. Experiments using in vitro ADR-administered Rac1 knockdown podocytes also supported that a reduction in Rac1 suppressed mTOR activity in injured podocytes. Taken together, these data indicate that Rac1-associated mTOR activation in podocytes plays an important role in preventing the kidneys from developing glomerulosclerosis.

AGEs-RAGE overexpression in a patient with smoking-related idiopathic nodular glomerulosclerosis.

We report a case of smoking-related idiopathic nodular glomerulosclerosis (ING) with overexpression of glomerular advanced glycation end products (AGEs) and their receptor (RAGE). A 59-year-old Japanese man with nephrotic syndrome, who had a smoking history of one pack of cigarettes per day for approximately 40 years, presented with a 3-year history of urinalysis abnormalities without clinical evidence of diabetic mellitus. The patient's leg edema progressively worsened over the previous 2 years, and he was admitted to our hospital. Renal biopsy showed mesangial expansion with diabetic Kimmelstiel-Wilson-like nodular lesions, glomerular basement thickening, and arteriosclerosis. No electron-dense deposits, fibrils, or microtubule deposits were seen in the glomeruli on electron microscopy. Skin AGE level measured using AGE reader was higher in this case than the average level in age-matched Caucasians. In addition, immunohistochemical analysis revealed that N-carboxymethyl lysine, one of the major AGEs, and RAGE were overexpressed and podocin expression was decreased in the peripheral area of the glomerular nodular lesions. These observations suggest that AGEs-RAGE system may be activated in smoking-related ING, possibly leading to the progression of renal dysfunction.

Re-expression of Sall1 in podocytes protects against adriamycin-induced nephrosis.

The highly conserved spalt (sal) gene family members encode proteins characterized by multiple double zinc finger motifs of the C2H2 type. Humans and mice each have four known Sal-like genes (SALL1-4 in humans and Sall1-4 in mice). Sall1 is known to have a crucial role in kidney development. To explore the significance of Sall1 in differentiated podocytes, we investigated podocyte-specific Sall1-deficient mice (Sall1 KOp°d°/p°d°) using a podocin-Cre/loxP system and siRNA Sall1 knockdown (Sall1 KD) podocytes. Under physiological conditions, Sall1 KOp°d°/p°d° mice exhibited no proteinuria during their lifetime, but foot-process effacement was detected in some of the podocytes. To elucidate the role of Sall1 in injured podocytes, we used an adriamycin (ADR)-induced model of nephrosis and glomerulosclerosis. Surprisingly, the expression of Sall1 was elevated in control mice on day 14 after ADR injection. On day 28 after ADR injection, Sall1 KOp°d°/p°d° mice exhibited significantly higher levels of proteinuria and higher numbers of sclerotic glomeruli. Differentiated Sall1 KD podocytes showed a loss of synaptopodin, suppressed stress fiber formation, and, ultimately, impaired directed cell migration. In addition, the loss of Sall1 increased the number of apoptotic podocytes following ADR treatment. These results indicated that Sall1 has a protective role in podocytes; thus, we investigated the endoplasmic reticulum stress marker GRP78. GRP78 expression was higher in ADR-treated Sall1 KOp°d°/p°d° mice than in control mice. Sall1 appeared to influence the expression of GRP78 in injured podocytes. These results suggest that Sall1 is associated with actin reorganization, endoplasmic reticulum stress, and apoptosis in injured podocytes. These protective aspects of Sall1 re-expression in injured podocytes may have the potential to reduce apoptosis and possibly glomerulosclerosis.

Sorting Nexin 9 facilitates podocin endocytosis in the injured podocyte.

The irreversibility of glomerulosclerotic changes depends on the degree of podocyte injury. We have previously demonstrated the endocytic translocation of podocin to the subcellular area in severely injured podocytes and found that this process is the primary disease trigger. Here we identified the protein sorting nexin 9 (SNX9) as a novel facilitator of podocin endocytosis in a yeast two-hybrid analysis. SNX9 is involved in clathrin-mediated endocytosis, actin rearrangement and vesicle transport regulation. Our results revealed and confirmed that SNX9 interacts with podocin exclusively through the Bin-Amphiphysin-Rvs (BAR) domain of SNX9. Immunofluorescence staining revealed the expression of SNX9 in response to podocyte adriamycin-induced injury both in vitro and in vivo. Finally, an analysis of human glomerular disease biopsy samples demonstrated strong SNX9 expression and co-localization with podocin in samples representative of severe podocyte injury, such as IgA nephropathy with poor prognosis, membranous nephropathy and focal segmental glomerulosclerosis. In conclusion, we identified SNX9 as a facilitator of podocin endocytosis in severe podocyte injury and demonstrated the expression of SNX9 in the podocytes of both nephropathy model mice and human patients with irreversible glomerular disease.

Glycolysis, but not Mitochondria, responsible for intracellular ATP distribution in cortical area of podocytes.

Differentiated podocytes, a type of renal glomerular cells, require substantial levels of energy to maintain glomerular physiology. Mitochondria and glycolysis are two major producers of ATP, but the precise roles of each in podocytes remain unknown. This study evaluated the roles of mitochondria and glycolysis in differentiated and differentiating podocytes. Mitochondria in differentiated podocytes are located in the central part of cell body while blocking mitochondria had minor effects on cell shape and migratory ability. In contrast, blocking glycolysis significantly reduced the formation of lamellipodia, a cortical area of these cells, decreased the cell migratory ability and induced the apoptosis. Consistently, the local ATP production in lamellipodia was predominantly regulated by glycolysis. In turn, synaptopodin expression was ameliorated by blocking either mitochondrial respiration or glycolysis. Similar to differentiated podocytes, the differentiating podocytes utilized the glycolysis for regulating apoptosis and lamellipodia formation while synaptopodin expression was likely involved in both mitochondrial OXPHOS and glycolysis. Finally, adult mouse podocytes have most of mitochondria predominantly in the center of the cytosol whereas phosphofructokinase, a rate limiting enzyme for glycolysis, was expressed in foot processes. These data suggest that mitochondria and glycolysis play parallel but distinct roles in differentiated and differentiating podocytes.

ENOS deficiency causes podocyte injury with mitochondrial abnormality.

The contribution of endothelial nitric oxide synthase (eNOS) to podocyte integrity remains unclear. This study therefore examined podocytes and mitochondrial abnormalities in eNOS deficient mice. Absence of eNOS caused glomerular hypertrophy, along with occasional glomerular sclerosis and mesangiolysis. While many glomeruli did not have such advanced lesions, ultrastructural analysis showed cellular hypertrophy, vacuolization, lysosomal enlargement, and microvillus formation in podocytes of eNOS knockout (KO) mice. Increased oxidative stress was associated with mitochondrial abnormalities, including an increase in number, coupled with a reduction in size, of mitochondria in podocytes of eNOS-KO mice. While the levels of expression of several mitochondrial proteins were not altered, the d-17 mutation in mitochondrial DNA was significantly associated with the eNOS deficiency. Renal ATP level in the renal cortex and mitochondrial respiration in the primary podocytes were significantly lower in eNOS-KO mice, suggesting that renal mitochondria may be functionally impaired. Podocytes cultured with endothelial conditioned medium lacking NO consistently showed a greater degree of mitochondrial fragmentation and an increase in mitochondrial oxidative stress, with these mitochondrial alterations rescued by an NO donor. In conclusion, eNOS may be necessary to maintain podocyte integrity, especially mitochondrial function.

Podocin is translocated to cytoplasm in puromycin aminonucleoside nephrosis rats and in poor-prognosis patients with IgA nephropathy.

Podocytes serve as the final barrier to urinary protein loss through a highly specialized structure called a slit membrane and maintain foot process and glomerular basement membranes. Podocyte injury results in progressive glomerular damage and accelerates sclerotic changes, although the exact mechanism of podocyte injury is still obscure. We focus on the staining gap (podocin gap) defined as the staining difference between podocin and synaptopodin, which are normally located in the foot process. In puromycin aminonucleoside nephrosis rats, the podocin gap is significantly increased (p < 0.05) and podocin is translocated to the cytoplasm on days 7 and 14 but not on day 28. Surprisingly, the gap is also significantly increased (p < 0.05) in human kidney biopsy specimens of poor-prognosis IgA nephropathy patients. This suggests that the podocin gap could be a useful marker for classifying the prognosis of IgA nephropathy and indicating the translocation of podocin to the cytoplasm. Next, we find more evidence of podocin trafficking in podocytes where podocin merges with Rab5 in puromycin aminonucleoside nephrosis rats at day 14. In immunoelectron microscopy, the podocin positive area was significantly translocated from the foot process areas to the cytoplasm (p< 0.05) on days 7 and 14 in puromycin aminonucleoside nephrosis rats. Interestingly, podocin is also translocated to the cytoplasm in poor-prognosis human IgA nephropathy. In this paper, we demonstrate that the translocation of podocin by endocytosis could be a key traffic event of critical podocyte injury and that the podocin gap could indicate the prognosis of IgA nephropathy.

Combination therapy with telmisartan and oxacalcitriol suppresses the progression of murine adriamycin nephropathy.

BACKGROUND: Blockade of the renin-angiotensin system plays a key role in suppressing the progression of renal diseases. It has not been well established whether this therapy provides additional effects when combined with vitamin D or its analog in a model of adriamycin (ADR)-induced nephropathy. METHODS: We evaluated the effect of an angiotensin II subtype 1 receptor blocker (telmisartan) combined with a vitamin D analog (oxacalcitriol) on mice ADR-induced nephropathy (9.5 mg/kg single intravenous injection). We also tested immortalized murine podocytes to examine the effects on podocyte apoptosis. RESULTS: Mice with ADR-induced nephropathy developed progressive albuminuria and glomerulosclerosis within 30 days accompanied by decreased expression of slit diaphragm (SD)-associated proteins (nephrin and podocin), reduced numbers of podocytes, and increased systolic blood pressure. Treatment with telmisartan or oxacalcitriol alone moderately ameliorated kidney injury. The combined treatment most effectively reduced the albuminuria and glomerulosclerosis. These effects were accompanied by the restoration of SD-associated proteins, reduction of podocyte apoptosis, and prevention of podocyte depletion in the glomeruli. Treatment with telmisartan, oxacalcitriol, and the combination therapy resulted in similar reductions in systolic blood pressure. In cultured murine podocytes, ADR stimulated the expression of Bax/Bcl-2 and apoptosis as determined by Hoechst 33342 staining. These changes were effectively inhibited by telmisartan or oxacalcitriol, but the combination treatment most effectively reduced these effects. CONCLUSIONS: These data demonstrated that application of a renin-angiotensin system blocker plus a vitamin D analog effectively prevented renal injury in ADR-induced nephropathy. The observed amelioration of renal injury may be partly attributable to antiapoptotic effects in podocytes.

Significance of urinary full-length megalin in patients with IgA nephropathy.

BACKGROUND AND OBJECTIVES: Megalin is highly expressed at the apical membranes of proximal tubular epithelial cells. A urinary full-length megalin (C-megalin) assay is linked to the severity of diabetic nephropathy in type 2 diabetes. This study examined the relationship between levels of urinary C-megalin and histological findings in adult patients with IgA nephropathy (IgAN). DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: Urine samples voided in the morning on the day of renal biopsy were obtained from 73 patients with IgAN (29 men and 44 women; mean age, 33 years) and 5 patients with membranous nephropathy (MN). Renal pathologic variables were analyzed using the Oxford classification of IgAN, the Shigematsu classification and the Clinical Guidelines of IgAN in Japan. The levels of urinary C-megalin were measured by sandwich ELISA. RESULTS: Histological analysis based on the Oxford classification revealed that the levels of urinary C-megalin were correlated with mesangial hypercellularity in IgAN patients (OR = 1.76, 95% CI: 1.04-3.27, P<0.05). There was a significant correlation between the levels of urinary C-megalin and the severity of chronic extracapillary abnormalities according to the Shigematsu classification in IgAN patients (ß = 0.33, P = 0.008). The levels of urinary C-megalin were significantly higher in all risk levels of IgAN patients requiring dialysis using the Clinical Guidelines of IgAN in Japan than in the control group. The levels of urinary C-megalin were significantly higher in the high risk and very high risk grades than in the low risk grade (P<0.05). The levels of urinary C-megalin were significantly higher in MN patients compared to the control group. CONCLUSIONS: The levels of urinary C-megalin are associated with histological abnormalities in adult IgAN patients. There is a possibility that urinary C-megalin is an independent predictor of disease progression of IgAN. In addition, our results suggest that urinary C-megalin is a marker of glomerular abnormalities in various glomerular diseases as well as IgAN.

Transient increase in proteinuria, poly-ubiquitylated proteins and ER stress markers in podocyte-specific autophagy-deficient mice following unilateral nephrectomy.

Previous studies have revealed that podocytes normally can be associated with a very high degree of autophagic activity, and that a lack of autophagic activity in podocytes is associated with susceptibility to disease and to late-onset glomerulosclerosis. In the present study, we conducted unilateral nephrectomy as a surgical model for acute nephron reduction. First, using GFP-LC3 transgenic mice to monitor autophagy, we found that glomerular autophagy could be transiently suppressed by surgery, but that it was restored quickly. To further explore the significance of podocyte autophagy after unilateral nephrectomy, we investigated podocyte-specific Atg7-deficient mice. The knockout mice exhibited no pathological phenotype compared with wild-type mice before nephrectomy. However, 1 day after nephrectomy, significantly higher levels of proteinuria and ultrastructural changes that included foot process effacement and a significant reduction in podocyte number were detected in mice harboring Atg7-deficient podocytes. Moreover, biochemical and immunohistochemical analyses showed a robust increase in polyubiquitin levels and ER stress markers in the glomeruli of the mice with autophagy-deficient podocytes. These results show the importance of the autophagic process in podocytes for maintaining a normal degree of filtration function during the adaptation to compensatory kidney hypertrophy following unilateral nephrectomy.