Nephrotic syndrome and Giant cell arthritis concurrently occurring after percutaneous transluminal angioplasty for renal artery stenosis
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An elderly Japanese woman with bilateral renal artery occlusion who developed massive proteinuria after unilateral percutaneous transluminal renal angioplasty (PTRA) is reported. She had a history of percutaneous coronary intervention and subsequently developed refractory hypertension. She was diagnosed with renovascular hypertension caused by bilateral total occlusion of the renal arteries, and underwent PTRA for the left renal artery. Nephrotic-range proteinuria from the left kidney, confirmed by split urine collection from each kidney under cytoscopic examination, and low-grade fever with positive C-reactive protein became obvious after PTRA. Giant cell arteritis (GCA) was also diagnosed by positive findings on fluorodeoxyglucose-positron emission tomography in the common carotid arteries, subclavian arteries, and aorta, but not in the renal arteries. Administration of corticosteroid and angiotensin-converting enzyme inhibitor decreased the proteinuria (> 9 - 2 g/day). Possible mechanisms for the development of nephrotic-range proteinuria and a hypothesis that GCA became obvious after PTRA are discussed.
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Concurrent minimal change nephrotic syndrome and type 1 diabetes mellitus in an adult Japanese woman: a case report.

BACKGROUND: Concurrent type 1 diabetes mellitus (T1DM) and idiopathic nephrotic syndrome is rare, and most previously reported cases were in children. We report the case of an adult woman who developed T1DM and minimal change nephrotic syndrome (MCNS) nearly simultaneously. CASE PRESENTATION: A 24-year-old woman had first presented to another hospital with nausea, vomiting, and fatigue. She was diagnosed with diabetic ketoacidosis and T1DM on the basis of her hyperglycemia, ketoacidosis, and positive anti-glutamic acid decarboxylase antibody test result. Rapid infusion of normal saline and insulin administration alleviated hyperglycemia and ketoacidosis. Two weeks after admission, however, she developed nephrotic syndrome (NS) with rapidly decreasing urine volume. She was referred to our hospital with a diagnosis of acute kidney injury. Although she temporarily required dialysis and high doses of insulin, within 1 month NS and acute kidney injury had been alleviated by oral prednisolone and low-density lipoprotein apheresis. Renal biopsy showed minor glomerular abnormalities without diabetic nephropathy, so we diagnosed her with MCNS. Seven weeks after the discharge, NS relapsed, and cyclosporine was added to prednisolone. However, NS relapsed twice within the next 4 months, so we started her on rituximab. At 6 months after initiating rituximab therapy, she remained in complete remission. Her mother also had T1DM but not MCNS. The patient had HLA-DRB1*09:01/09:01, DQB1*03:03/03:03, and her mother had HLA-DRB1*04:05/09:01, DQB1*03:03/04:01. CONCLUSIONS: Concurrent T1DM and MCNS is rare and their coexistence might be coincidental. Alternatively, they might have been caused by an underlying, unidentified genetic predisposition. Previous reports and our patient's findings suggest that specific HLA alleles and haplotypes or a Th1/Th2 imbalance might be associated with T1DM and MCNS that occurred nearly simultaneously.

FSGS as an Adaptive Response to Growth-Induced Podocyte Stress.

Glomerular sclerotic lesions develop when the glomerular filtration surface area exceeds the availability of podocyte foot process coverage, but the mechanisms involved are incompletely characterized. We evaluated potential mechanisms using a transgenic (podocin promoter-AA-4E-BP1) rat in which podocyte capacity for hypertrophy in response to growth factor/nutrient signaling is impaired. FSGS lesions resembling human FSGS developed spontaneously by 7 months of age, and could be induced earlier by accelerating kidney hypertrophy by nephrectomy. Early segmental glomerular lesions occurred in the absence of a detectable reduction in average podocyte number per glomerulus and resulted from the loss of podocytes in individual glomerular capillary loops. Parietal epithelial cell division, accumulation on Bowman's capsule, and tuft invasion occurred at these sites. Three different interventions that prevented kidney growth and glomerular enlargement (calorie intake reduction, inhibition of mammalian target of rapamycin complex, and inhibition of angiotensin-converting enzyme) protected against FSGS lesion development, even when initiated late in the process. Ki67 nuclear staining and unbiased transcriptomic analysis identified increased glomerular (but not podocyte) cell cycling as necessary for FSGS lesion development. The rat FSGS-associated transcriptomic signature correlated with human glomerular transcriptomes associated with disease progression, compatible with similar processes occurring in man. We conclude that FSGS lesion development resulted from glomerular growth that exceeded the capacity of podocytes to adapt and adequately cover some parts of the filtration surface. Modest modulation of the growth side of this equation significantly ameliorated FSGS progression, suggesting that glomerular growth is an underappreciated therapeutic target for preservation of renal function.

The two kidney to one kidney transition and transplant glomerulopathy: a podocyte perspective.

The attrition rate of functioning allografts beyond the first year has not improved despite improved immunosuppression, suggesting that nonimmune mechanisms could be involved. Notably, glomerulopathies may account for about 40% of failed kidney allografts beyond the first year of engraftment, and glomerulosclerosis and progression to ESRD are caused by podocyte depletion. Model systems demonstrate that nephrectomy can precipitate hypertrophic podocyte stress that triggers progressive podocyte depletion leading to ESRD, and that this process is accompanied by accelerated podocyte detachment that can be measured in urine. Here, we show that kidney transplantation "reverse nephrectomy" is also associated with podocyte hypertrophy and increased podocyte detachment. Patients with stable normal allograft function and no proteinuria had levels of podocyte detachment similar to levels in two-kidney controls as measured by urine podocyte assay. By contrast, patients who developed transplant glomerulopathy had 10- to 20-fold increased levels of podocyte detachment. Morphometric studies showed that a subset of these patients developed reduced glomerular podocyte density within 2 years of transplantation due to reduced podocyte number per glomerulus. A second subset developed glomerulopathy by an average of 10 years after transplantation due to reduced glomerular podocyte number and glomerular tuft enlargement. Reduced podocyte density was associated with reduced eGFR, glomerulosclerosis, and proteinuria. These data are compatible with the hypothesis that podocyte depletion contributes to allograft failure and reduced allograft half-life. Mechanisms may include immune-driven processes affecting the podocyte or other cells and/or hypertrophy-induced podocyte stress causing accelerated podocyte detachment, which would be amenable to nonimmune therapeutic targeting.

Estimating podocyte number and density using a single histologic section.

The reduction in podocyte density to levels below a threshold value drives glomerulosclerosis and progression to ESRD. However, technical demands prohibit high-throughput application of conventional morphometry for estimating podocyte density. We evaluated a method for estimating podocyte density using single paraffin-embedded formalin-fixed sections. Podocyte nuclei were imaged using indirect immunofluorescence detection of antibodies against Wilms' tumor-1 or transducin-like enhancer of split 4. To account for the large size of podocyte nuclei in relation to section thickness, we derived a correction factor given by the equation CF=1/(D/T+1), where T is the tissue section thickness and D is the mean caliper diameter of podocyte nuclei. Normal values for D were directly measured in thick tissue sections and in 3- to 5-µm sections using calibrated imaging software. D values were larger for human podocyte nuclei than for rat or mouse nuclei (P<0.01). In addition, D did not vary significantly between human kidney biopsies at the time of transplantation, 3-6 months after transplantation, or with podocyte depletion associated with transplant glomerulopathy. In rat models, D values also did not vary with podocyte depletion, but increased approximately 10% with old age and in postnephrectomy kidney hypertrophy. A spreadsheet with embedded formulas was created to facilitate individualized podocyte density estimation upon input of measured values. The correction factor method was validated by comparison with other methods, and provided data comparable with prior data for normal human kidney transplant donors. This method for estimating podocyte density is applicable to high-throughput laboratory and clinical use.

Urine podocyte mRNAs, proteinuria, and progression in human glomerular diseases.

Model systems demonstrate that progression to ESRD is driven by progressive podocyte depletion (the podocyte depletion hypothesis) and can be noninvasively monitored through measurement of urine pellet podocyte mRNAs. To test these concepts in humans, we analyzed urine pellet mRNAs from 358 adult and pediatric kidney clinic patients and 291 controls (n=1143 samples). Compared with controls, urine podocyte mRNAs increased 79-fold (P<0.001) in patients with biopsy-proven glomerular disease and a 50% decrease in kidney function or progression to ESRD. An independent cohort of patients with Alport syndrome had a 23-fold increase in urinary podocyte mRNAs (P<0.001 compared with controls). Urinary podocyte mRNAs increased during active disease but returned to baseline on disease remission. Furthermore, urine podocyte mRNAs increased in all categories of glomerular disease evaluated, but levels ranged from high to normal, consistent with individual patient variability in the risk for progression. In contrast, urine podocyte mRNAs did not increase in polycystic kidney disease. The association between proteinuria and podocyturia varied markedly by glomerular disease type: a high correlation in minimal-change disease and a low correlation in membranous nephropathy. These data support the podocyte depletion hypothesis as the mechanism driving progression in all human glomerular diseases, suggest that urine pellet podocyte mRNAs could be useful for monitoring risk for progression and response to treatment, and provide novel insights into glomerular disease pathophysiology.

Growth-dependent podocyte failure causes glomerulosclerosis.

Podocyte depletion leads to glomerulosclerosis, but whether an impaired capacity of podocytes to respond to hypertrophic stress also causes glomerulosclerosis is unknown. We generated transgenic Fischer 344 rats that express a dominant negative AA-4E-BP1 transgene driven by the podocin promoter; a member of the mammalian target of rapamycin complex 1 (mTORC1) pathway, 4E-BP1 modulates cap-dependent translation, which is a key determinant of a cell's hypertrophic response to nutrients and growth factors. AA-4E-BP1 rat podocytes expressed the transgene and had normal kidney histology and protein excretion at 100 g of body weight but developed ESRD by 12 months. Proteinuria and glomerulosclerosis were linearly related to both increasing body weight and transgene dose. Uni-nephrectomy reduced the body weight at which proteinuria first developed by 40%-50%. The initial histologic manifestation of disease was the appearance of bare areas of glomerular basement membrane from the pulling apart of podocyte foot processes, followed by adhesions to the Bowman capsule. Morphometric analysis confirmed the mismatch between glomerular tuft volume and total podocyte volume (number × size) per tuft in relation to weight gain and nephrectomy. Proteinuria and glomerulosclerosis did not develop if dietary calorie restriction prevented weight gain and glomerular enlargement. In summary, failure of podocytes to match glomerular tuft growth in response to growth signaling through the mTORC1 pathway can trigger proteinuria, glomerulosclerosis, and progression to ESRD. Reducing body weight and glomerular growth may be useful adjunctive therapies to slow or prevent progression to ESRD.

Case Report: A Case of Encephalopathy Presenting the Lentiform Fork Sign on MRI in a Diabetic Dialysis Patient.

Basal ganglia lesions showing an expansile high signal intensity on T2-weighted MRI are termed the lentiform fork sign. This specific finding is mainly observed in diabetic patients with uremic encephalopathy with metabolic acidosis, although there are also reports in patients with ketoacidosis, dialysis disequilibrium syndrome, intoxication, and following drug treatment (e.g., metformin). A 57-year-old Japanese man on chronic hemodialysis for 4 years because of diabetic nephropathy was admitted to our hospital for relatively rapid-onset gait disturbance, severe dysarthria, and consciousness disturbance. Brain T2-weighted MRI showed the lentiform fork sign. Hemodialysis was performed the day before admission, and laboratory tests showed mild metabolic (lactic) acidosis, but no uremia. Surprisingly, metformin, which is contraindicated for patients with end-stage kidney disease, had been prescribed for 6 months in his medication record, and his sluggish speaking and dysarthria appeared gradually after metformin treatment was started. Thus, the encephalopathy was considered to be related to metformin treatment. He received hemodialysis treatment for 6 consecutive days, and his consciousness disturbance and dysarthria improved in 1 week. At the 8-month follow-up, the size of the hyperintensity area on MRI had decreased, while the mild gait disturbance remained. Considering the rapid onset of gait and consciousness disturbance immediately before admission, diabetic uremic syndrome may also have occurred with metformin-related encephalopathy, and resulted in the lentiform fork sign, despite the patient showing no evidence of severe uremia on laboratory data.

Characterisation of N-terminal pro-brain natriuretic peptide in dialysis patients and its reduced prognostic significance in the elderly.

Characterisation of N-terminal pro-brain natriuretic peptide (NT-proBNP) in chronic haemodialysis patients and its prognostic significance in age stratification have not been addressed. A prospective cohort study with cross-sectional analyses at baseline was performed. Outcomes were all-cause mortality, non-malignancy-related mortality, and cardiovascular disease (CVD)-related mortality. NT-proBNP was significantly higher in elderly, female, and low dry weight patients. Study patients were divided into two groups: Group-O (≥75 years) and Group-Y (<75 years). The 7-year follow-up receiver operating curve analysis showed that NT-proBNP significantly predicted all outcomes. All-cause mortality cut-off points were significantly different among the groups (total cohort, 5375 pg/mL; Group-Y, 3682 pg/mL; Group-O, 11750 pg/mL). Cox regression analysis showed risks for all outcomes by tertile NT-proBNP significantly higher in the total cohort and Group-Y as adjusted by potential confounders. For all-cause mortality, hazard ratios and 95% confidence intervals (CI) were T2 1.70 (0.89 to 3.25), p = 0.11, T3 2.95 (1.54 to 5.67), p < 0.01 in Group-Y; and T2 1.00 (0.64 to 1.58), p = 1.00; T3 1.50 (0.94 to 2.40), p = 0.09 in Group-O. In conclusion, NT-proBNP was significantly higher in elderly, female, and low dry weight chronic dialysis patients. NT-proBNP was significantly associated with all outcomes. However, this association was reduced in elderly patients.

Diminishing dry weight is strongly associated with all-cause mortality among long-term maintenance prevalent dialysis patients.

OBJECTIVES: To investigate the relationship between dry weight (DW) change and survival in long-term maintenance prevalent dialysis patients. METHODS: We conducted a prospective data collection study with retrospective analysis of the registered data. Patients were followed up for 5 years (1-year observation of DW changes and subsequent 4-year follow-up). The outcome was all-cause mortality. The predictors were 1-year DW change rates. The hazard ratios (HRs) for all-cause mortality were calculated using multivariable Cox regression analysis, fully adjusted for age, sex, basal kidney disease, dialysis vintage, current smoking, past cardiovascular events, serum albumin, DW at enrollment, serum creatinine, mean predialysis systolic blood pressure, and cardiothoracic ratio or 1-year cardiothoracic ratio change rate. Propensity score (PS) analysis was also conducted using the same covariates of Cox regression analysis. RESULTS: In total, 899 dialysis patients (mean dialysis vintage: 101.2 months) were followed up, and 180 deaths were recorded, of which 90 were of cardiovascular origin. Each 2% decrement of DW showed adjusted HR, and the 95% confidence interval was 1.24 [1.16-1.33]. According to the 1-year DW change rate, participants were divided into five groups (group A, ≥+3%; group B, +1 to +2.9%; group C, -0.9 to +0.9%; group D, -2.9 to -1.0%; and group E, ≤-3%). For survival curves based on grouping, group B had the best and group E had the worst survival rate (p<0.01, log-rank test). Therefore, we set group B as a reference; adjusted risks for death of groups D and E were 2.16 [1.23-3.79] and 2.66 [1.54-4.58], respectively. However, this relation was blunted in patients of heavier DW. The PS-matched cohort showed a poorer prognosis in patients with diminishing DW divided by DW change rate at -0.635% (mean value of DW change rate). CONCLUSION: In the long-term maintenance hemodialysis cohort, 1-year DW decrement, especially ≤-3.0%, was significantly associated with all-cause mortality, and cardiovascular disease-related death was prominent in these patients.