A Validation Study Comparing Risk Prediction Models of IgA Nephropathy.

We aimed to validate three IgAN risk models proposed by an international collaborative study and another CKD risk model generated by an extended CKD cohort with our multicenter Chinese IgAN cohort. Biopsy-proven IgAN patients with an eGFR ≥15 ml/min/1.73 m2 at baseline and a minimum follow-up of 6 months were enrolled. The primary outcomes were a composite outcome (50% decline in eGFR or ESRD) and ESRD. The performance of those models was assessed using discrimination, calibration, and reclassification. A total of 2,300 eligible cases were enrolled. Of them, 288 (12.5%) patients reached composite outcome and 214 (9.3%) patients reached ESRD during a median follow-up period of 30 months. Using the composite outcome for analysis, the Clinical, Limited, Full, and CKD models had relatively good performance with similar C statistics (0.81, 0.81, 0.82, and 0.82, respectively). While using ESRD as the end point, the four prediction models had better performance (all C statistics > 0.9). Furthermore, subgroup analysis showed that the models containing clinical and pathological variables (Full model and Limited model) had better discriminatory abilities than the models including only clinical indicators (Clinical model and CKD model) in low-risk patients characterized by higher baseline eGFR (≥60 ml/min/1.73 m2). In conclusion, we validated recently reported IgAN and CKD risk models in our Chinese IgAN cohort. Compared to pure clinical models, adding pathological variables will increase performance in predicting ESRD in low-risk IgAN patients with baseline eGFR ≥60 ml/min/1.73 m2.

Development of anti-glomerular basement membrane glomerulonephritis during the course of IgA nephropathy: a case report.

BACKGROUND: Anti-glomerular basement membrane (GBM) glomerulonephritis does not usually coexist with another glomerulonephritis such as IgA nephropathy. We present a rare case having a combination of these two diseases, and furthermore, histological evaluation could be performed before and after the development of anti-GBM glomerulonephritis over a period of only10 months. CASE PRESENTATION: A 66-year-old woman was admitted with complaints of microscopic hematuria and mild proteinuria for the past 3 years. Serum creatinine level was normal at that time. The first renal biopsy was performed. Light microscopy revealed mesangial proliferative glomerulonephritis with fibro-cellular crescents in one out of 18 glomeruli, excluding one global sclerotic glomerulus. Immunofluorescence (IF) showed IgA and C3 deposition in the mesangium. Therefore, the diagnosis was IgA nephropathy. Eight months later, the patient's serum creatinine suddenly rose to 4.53 mg/dL and urinalysis showed 100 red blood cells per high power field with nephrotic range proteinuria (12.3 g/gCr). The serological tests revealed the presence of anti-GBM antibody at the titer of 116 IU/mL. Treatments were begun after admission, consisting of hemodialysis, plasma exchange, and intravenous methylprednisolone pulse therapy. At 4 weeks after admission, the second renal biopsy was performed. Light microscopy revealed crescents in 18 of 25 glomeruli, excluding six global sclerotic glomeruli. IF showed linear IgG deposition along the GBM in addition to granular IgA and C3 deposition. Based on these findings, the diagnosis of anti-GBM glomerulonephritis and IgA nephropathy was confirmed. Renal function was not restored despite treatment, but alveolar hemorrhage was prevented. CONCLUSIONS: We report a patient with a diagnosis of anti-GBM disease during the course of IgA nephropathy. This case strongly suggests that the presence of autoantibodies should be checked to rule out overlapping autoimmune conditions even in patient who have previously been diagnosed with chronic glomerulonephritis, such as IgA nephropathy, who present an unusually rapid clinical course.

The impact of IgM deposits on the outcome of Nephrotic syndrome in children.

BACKGROUND: The significance of IgM deposits in glomerular mesangium has been controversial since they were first described due to the variations in the both the definitions used and described impact on clinical outcome. The aim of our study was to evaluate the significance of the IgM deposits in the glomerular mesangium for outcomes of nephrotic syndrome (NS) in children. METHODS: Forty-five children with NS who underwent renal biopsy at tertiary pediatric hospital from January 1st, 2000 to December 31st, 2015 and the pathology diagnosis of minimal change disease, focal segmental glomerulosclerosis and mesangial hypercellularity (MH) were retrospectively analyzed. IgM positivity was defined as ≥1+ imunofluorescence with predominantly mesangial distribution. The patients were stratified into IgM-positive (n = 18) and IgM-negative (n = 27). RESULTS: At the end of the median follow-up 4.5 years (range 0.17-13.14), the IgM-positive group was represented by 11 patients (61.1%) in remission, 3 patients (16.7%) with active disease and normal kidney function, 2 (11.1%) patients with active disease and impaired kidney function, 2 (11.1%) patients on renal replacement therapy. Accordingly, the IgM-negative group included 13 patients (48.1%) in remission, 12 (44.4%) with active disease and normal kidney function, 1 (3.7%) with active disease and impaired kidney function, 1 (3.7%) on renal replacement therapy, with no statistical significance between groups (p = 0.186). CONCLUSIONS: This study did not reveal significant differences of the disease outcomes between IgM-positive and IgM-negative groups.

Accumulation of worn-out GBM material substantially contributes to mesangial matrix expansion in diabetic nephropathy.

Thickening of the glomerular basement membrane (GBM) and expansion of the mesangial matrix are hallmarks of diabetic nephropathy (DN), generally considered to emerge from different sites of overproduction: GBM components from podocytes and mesangial matrix from mesangial cells. Reevaluation of 918 biopsies with DN revealed strong evidence that these mechanisms are connected to each other, wherein excess GBM components fail to undergo degradation and are deposited in the mesangium. These data do not exclude that mesangial cells also synthesize components that contribute to the accumulation of matrix in the mesangium. Light, electron microscopic, immunofluorescence, and in situ hybridization studies clearly show that the thickening of the GBM is due not only to overproduction of components of the mature GBM (α3 and α5 chains of collagen IV and agrin) by podocytes but also to resumed increased synthesis of the α1 chain of collagen IV and of perlecan by endothelial cells usually seen during embryonic development. We hypothesize that these abnormal production mechanisms are caused by different processes: overproduction of mature GBM-components by the diabetic milieu and regression of endothelial cells to an embryonic production mode by decreased availability of mediators from podocytes.

[Pathology and differential diagnosis of immunotactoid glomerulopathy].

Objective: To study the morphologic changes of immunotactoid glomerulopathy and to investigate the clinical pathological features and differential diagnosis. Methods: Renal biopsy was observed under the light microscope, immunofluorescence and electron microscopy in a case of newly diagnosed immunotactoid glomerulopathy. Results: This patient clinically presented with nephrotic syndrome and hypertension, without family history of renal diseases. Light microscopy showed that diffusely massive and specific protein deposition in the glomerulus in Masson staining. Immunofluorescence revealed IgG, C3 and κ were deposited along the capillary walls and mesangial regions. Electron microscopic examination showed that a large amount of microtubule like substances and a small amount of long bar-shaped and dense crystal-like substances were deposited in the subendothelial spaces and mesangial areas. Conclusions: Light microscopy and immunofluorescence of immunotactoid glomerulopathy show no specifically pathological changes. Under electron microscope, a large amount of microtubule like substances is deposited in the glomerulus, which is the key point to distinguish this disease from other glomerular diseases. Except for the microtubule-like substances, the present case is accompanied by the deposition of long bar-shaped and dense crystal-like substance, which has not been reported in previous studies.

An animal model of glomerular light-chain-associated amyloidogenesis depicts the crucial role of lysosomes.

In vitro and ex vivo studies have elucidated the step-by-step process whereby some physicochemically abnormal light chains are processed by mesangial cells to form amyloid fibrils. Although crucial steps in the cascade of events have been determined, these findings have not been reproduced in vivo. This has led to some doubts as to the significance and clinical application of the information that has been deciphered. Here, we developed an animal model which uses mice injected with amyloidogenic light chains purified from the urine of patients with biopsy-proven, light-chain-associated glomerular amyloidosis which validated in vitro/ex vivo findings. This animal model showed internalization of the light chains utilizing caveolae followed by trafficking to the mature lysosomal compartment where fibrils were formed. This model permits evaluation of mesangial amyloidogenesis for prolonged periods of time, is potentially useful to test maneuvers to modulate events that take place, and can be used to design novel therapeutic interventions.

Protective effect of statin therapy on connective tissue growth factor induction by diabetes in vivo and high glucose in vitro.

Transcriptional activity of connective tissue growth factor (CTGF) promoter in transfected HEK293 cells was determined by luciferase assays. Secreted CTGF in cultured human mesangial cells was measured by enzyme-linked immunosorbent assay (ELISA). CTGF in urine and plasma was also measured in 405 subjects with/without type 2 diabetes. Our results showed that high glucose significantly increased transcription of the promoter in the transfected cells by more than 2.5-folds (p < 0.0005). CTGF secretion was induced by high glucose in the cells (p < 0.0005). These increases were inhibited by simvastatin. Urine CTGF was positively associated with plasma CTGF in both type 2 diabetes (p = 0.0005) and controls (p = 0.01). Urine CTGF levels in patients with macroalbuminuria were significantly higher than patients without macroalbuminuria (p < 0.05). In conclusion, our in vitro study suggests that statin may have a renal-protective effect through the inhibition of CTGF expression. Urine CTGF may be a good marker for the prediction of diabetic nephropathy.

A case of idiopathic nodular glomerulosclerosis with fibrin caps.

We report a case of idiopathic nodular glomerulosclerosis (ING) mimicking diabetic Kimmelstiel-Wilson glomerulopathy. A 72-year-old man suffering from nephritic syndrome and renal dysfunction had no prior history of diabetes mellitus, but had impaired glucose tolerance and a history of hypertension and smoking. A kidney biopsy showed increased mesangial matrix with Kimmelstiel-Wilson-like nodules, glomerular basement membrane thickening and capillary microaneurysms. Additionally, a large amount of fibrin caps detectable as electron-dense subendothelial material by electron microscopy were observed. Although ING with fibrin caps has been rarely reported, the large number of fibrin caps seen in this case may be due to the advanced clinical stage.

Circulating levels of chromatin fragments are inversely correlated with anti-dsDNA antibody levels in human and murine systemic lupus erythematosus.

Anti-dsDNA antibodies represent a central pathogenic factor in Lupus nephritis. Together with nucleosomes they deposit as immune complexes in the mesangial matrix and along basement membranes within the glomeruli. The origin of the nucleosomes and when they appear e.g. in circulation is not known. Serum samples from autoimmune (NZBxNZW)F1 mice, healthy BALB/c mice, patients with SLE, RA and normal healthy individuals were analyzed for presence and amount of circulating anti-dsDNA antibodies and nucleosomal DNA. Here we use a quantitative PCR to measure circulating DNA in sera. We demonstrate an inverse correlation between anti-dsDNA antibodies and the DNA concentration in the circulation in both murine and human serum samples. High titer of anti-DNA antibodies in human sera correlated with reduced levels of circulating chromatin, and in lupus prone mice with deposition within glomeruli. The inverse correlation between DNA concentration and anti-dsDNA antibodies may reflect antibody-dependent deposition of immune complexes during the development of lupus nephritis in autoimmune lupus prone mice. The measurement of circulating DNA in SLE sera by using qPCR may indicate and detect the development of lupus nephritis at an early stage.

Increased class A scavenger receptor and glomerular lipid precede mesangial matrix expansion in the bGH mouse model.

OBJECTIVE: Elevated neutral lipid content and mRNA expression of class A scavenger receptor (SRA) have been found in the renal cortex of the bovine growth hormone (bGH) mouse model of progressive glomerulosclerosis (GS). We hypothesize that the increased expression of SRA precedes glomerular scarring in this model. DESIGN: Real time RT-PCR and immunofluorescence were employed to measure SRA and collagen types I and IV in the bGH transgenic and control mice at 5 and 12 weeks (wk) of age to determine the chronology of change in SRA expression in relation to glomerular scarring. Alternative mechanisms for increasing glomerular lipid were assessed by measuring mRNA expression levels of low-density lipoprotein receptor (LDL-r), 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGR), and ATP-binding cassette transporter A1 (ABCA1). In addition, the involvement of macrophages in early GS was assessed by CD68 mRNA expression in kidney cortex. RESULTS: Both mRNA and protein levels of SRA were significantly increased in 5-wk bGH compared with control mice, whereas the expression of collagen I and IV was unaltered. Unchanged levels of LDL-r and HMGR mRNA indicate that neither regulated cholesterol uptake via LDL-r nor the cholesterol synthetic pathway played a role in the early lipid increase. The finding of increased ABCA1 expression was an indicator of excess intracellular lipid in the renal cortex of bGH mice at 5 wk. CD68 expression in bGH did not differ significantly from that of controls at 5 wk suggesting that cortical macrophage infiltration was not increased in bGH mice at this time point. CONCLUSION: An early increase in SRA mRNA and protein expression in the bGH kidney precedes glomerular scarring and is independent of macrophage influx.

Changes in glomerular mesangium in kidneys with congenital nephrotic syndrome of the Finnish type.

Congenital nephrotic syndrome of the Finnish type (NPHS1, CNF) is an autosomal recessive disease caused by mutations in a major podocyte protein, nephrin. NPHS1 is associated with heavy proteinuria and the development of glomerular scarring. We studied the cellular and molecular changes affecting the glomerular mesangium in NPHS1 kidneys. Marked hyperplasia of mesangial cells (MC) was mainly responsible for the early mesangial expansion in NPHS1 glomeruli. The levels of the proliferation marker, mindbomb homolog 1 and the major MC mitogen, platelet-derived growth factor, and its receptors, however, were quite normal. Only a small number of cells were positive for CD68 (marker for phagocytic cells) and CD34 (marker for mesenchymal precursor cells) in the NPHS1 mesangium. MCs strongly expressed alpha-smooth muscle actin, indicating myofibloblast transformation. The expression levels of the profibrotic mediators osteopontin and transforming growth factor beta were up-regulated in NPHS1 glomeruli by 3.2 and 1.6-fold, respectively, compared to the controls. The synthesis by MCs of the typical fibroblast products collagen I, fibronectin, and tenascin, however, was low, and the extracellular matrix increase was caused by the accumulation of a normal MC product, collagen IV. The results indicate that severe glomerular sclerosis can develop without major qualitative cellular or molecular changes in the mesangium.

Glomeruli of Dense Deposit Disease contain components of the alternative and terminal complement pathway.

Dense Deposit Disease (DDD), or membranoproliferative glomerulonephritis type II, is a rare renal disease characterized by dense deposits in the mesangium and along the glomerular basement membranes that can be seen by electron microscopy. Although these deposits contain complement factor C3, as determined by immunofluorescence microscopy, their precise composition remains unknown. To address this question, we used mass spectrometry to identify the proteins in laser microdissected glomeruli isolated from paraffin-embedded tissue of eight confirmed cases of DDD. Compared to glomeruli from five control patients, we found that all of the glomeruli from patients with DDD contain components of the alternative pathway and terminal complement complex. Factor C9 was uniformly present as well as the two fluid-phase regulators of terminal complement complex clusterin and vitronectin. In contrast, in nine patients with immune complex-mediated membranoproliferative glomerulonephritis, glomerular samples contained mainly immunoglobulins and complement factors C3 and C4. Our study shows that in addition to fluid-phase dysregulation of the alternative pathway, soluble components of the terminal complement complex contribute to glomerular lesions found in DDD.

[Glomerular deposition disease, regarding a case of fibrillary glomerulonephritis]. / Enfermedad de depósito glomerular: a propósito de un caso de glomerulonefritis fibrilar.

In routine diagnosis for renal biopsy, glomerular diseases are encountered that, viewed by electron microscopy, reveal deposits with a fibrillary structure in the extracellular matrix of the glomeruli. Amyloidosis is the most common glomerulopathy that shows deposits with an ultrastructural fibrillary structure. However, other glomerulopathies have deposits with an ultrastructural fibrillary structure and which are negative for Congo-red stain, but positive for immunoglobulins. Fibrillary glomerulonephritis is a well-characterized disease, and clearly identified in approximately 0.5% to 1% of biopsies of native kidneys. These cases usually manifest themselves as severe renal insufficiencies with nephrotic-range proteinuria. No treatment regimes have been clearly established and the prognosis is poor. Herein, the clinical and histological characteristics are described for the first case of idiopathic fibrillary glomerulonephritis reported in Colombia.

Efficacy and safety of lisinopril for mild childhood IgA nephropathy: a pilot study.

Even in children with mild immunoglobulin (Ig)A nephropathy (IgA-N) showing minimal/focal mesangial proliferation, persistent proteinuria seems to be a risk factor for progression of the disease, indicating the need for an effective and safe treatment even in such cases. Studies carried out to date have indicated that angiotensin-converting enzyme inhibitors (ACEIs) reduce urinary protein excretion and preserve renal function in adult IgA-N. However, no prospective study of ACEI only for childhood IgA-N has yet been carried out. In this prospective single-arm pilot trial, we administered lisinopril (0.4 mg/kg per day) as therapeutic treatment to 40 children with mild IgA-N with proteinuria [morning urinary protein/creatinine ratio (uP/Cr) >or= 0.2 g/g]. Thirty-three patients reached the primary endpoint (uP/Cr < 0.2) during the 2-year treatment period. The cumulative disappearance rate of proteinuria determined by the Kaplan-Meier method was 80.9%. Mean uP excretion was reduced from 0.40 to 0.18 g/m(2)/day (p < 0.0001). Of the 40 patients treated, five (12.5%) showed dizziness, and four of these five needed the lisinopril dose reduced. However, lisinopril therapy was continued in all patients during the 2-year treatment period. No other side effect, such as cough, was observed. We conclude that the efficacy and safety of lisinopril is seemingly acceptable for the treatment of children with mild IgA-N.

What is the significance of CD34 immunostaining in the extraglomerular and intraglomerular mesangium?

CD34, traditionally a marker of hematopoietic stem cells (HSCs), was found on endothelial cells and fibroblasts as well. At the level of the extraglomerular or intraglomerular mesangium, CD34 may signal either the presence of HSCs or, conversely, may be a marker of transdifferentiation. CD34-positive cells of the extraglomerular mesangium could migrate into the intraglomerular mesangium and participate in reparative processes at this level. The aim of our study was to analyze the presence of CD34 at the level of the extraglomerular and intraglomerular mesangium and its relationship with histological markers of activity and chronicity, as well as with other immunohistochemical markers in glomerulonephritis (GN). A cross-sectional study of 36 patients with GN was conducted. Conventional stains: hematoxylin-eosin, periodic acid Schiff, and Trichrome Gömöri, as well as immunohistochemistry: CD34, alpha smooth muscle actin (alpha SMA), vimentin, and proliferating cell nuclear antigen (PCNA) were employed. Activity and chronicity of GN were evaluated according to a scoring system initially used for lupus nephritis and antineutrophil-cytoplasmic-antibody-associated vasculitis. Immunohistochemistry was assessed using a semiquantitative score. The mean age was 46.44 +/- 12.97 years; 22 were male and 14 were female. The extraglomerular mesangium was visible on specimens in 30 patients. CD34 was present in the extraglomerular mesangium in 15 patients: 11 of these patients showed concomitant intraglomerular and extraglomerular mesangial CD34 immunostaining, while four showed only extraglomerular mesangial immunostaining. In three patients, CD34 immunostaining was present only in the intraglomerular mesangium. Twelve patients showed negative immunostaining in both the extraglomerular and the intraglomerular mesangium. Overall, there was a fair degree of relationship, which did not reach statistical significance between CD34 in the extraglomerular mesangium and CD34 in the intraglomerular mesangium across the 36 patients. In the intraglomerular mesangium, CD34 did not significantly correlate with mesangial alpha SMA, vimentin, PCNA, and activity or chronicity index. In the extraglomerular mesangium, CD34 did not show a significant correlation with alpha SMA, vimentin, or PCNA. The activity index and the chronicity index showed a good correlation with serum creatinine. Mesangial cell proliferation correlated well with the mesangial matrix increase, while interstitial vimentin showed a good correlation with interstitial alpha SMA. We demonstrated the presence of CD34 in the extraglomerular mesangium, which could be related to transdifferentiated mesangial cells or to HSCs in the absence of blood vessels at this level. Our study shows the value of histological indices for evaluating GN but cannot assign significance to CD34 immunolabeling for the assessment of GN.

Overexpression of connective tissue growth factor in podocytes worsens diabetic nephropathy in mice.

Connective tissue growth factor (CTGF) is a potent inducer of extracellular matrix accumulation. In diabetic nephropathy, CTGF expression is markedly upregulated both in podocytes and mesangial cells, and this may play an important role in its pathogenesis. We established podocyte-specific CTGF-transgenic mice, which were indistinguishable at baseline from their wild-type littermates. Twelve weeks after streptozotocin-induced diabetes, these transgenic mice showed a more severe proteinuria, mesangial expansion, and a decrease in matrix metalloproteinase-2 activity compared to diabetic wild-type mice. Furthermore, diabetic transgenic mice exhibited less podocin expression and a decreased number of diffusely vacuolated podocytes compared to diabetic wild-type mice. Importantly, induction of diabetes in CTGF-transgenic mice resulted in a further elevation of endogenous CTGF mRNA expression and protein in the glomerular mesangium. Our findings suggest that overexpression of CTGF in podocytes is sufficient to exacerbate proteinuria and mesangial expansion through a functional impairment and loss of podocytes.

A pediatric occurrence of crescentic glomerulonephritis associated with antineutrophil cytoplasmic antibodies and mesangial IgA deposits.

Antineutrophil cytoplasmic antibody-(ANCA) associated glomerulonephritis usually shows histopathologic features of pauciimmune crescentic glomerulonephritis and occurs late in life. We report a 14-year-old Japanese girl presenting with proteinuria, hematuria and mildly elevated serum creatinine. A renal biopsy specimen demonstrated crescentic glomerulonephritis, immunofluorescence showed mesangial IgA staining. Electron microscopic examination disclosed paramesangial deposits. Serum ANCA against myeloperoxidase (MPO) were detected at high titers. Myeloperoxidase-ANCA-related nephritis accompanied by IgA nephropathy is considered rare in childhood and teen years. Yet, if ANCA assays and detailed electron microscopic examination of renal specimens were performed routinely in patients with rapidly progressive glomerulonephritis, the diagnosis might be more frequent in young patients.