Outcome of IgA nephropathy in adults graded by chronic histological lesions

Inhibition of RNA-binding protein HuR reduces glomerulosclerosis in experimental nephritis

Recent identification of an RNA-binding protein (HuR) that regulates mRNA turnover and translation of numerous transcripts via binding to an ARE in their 3′-UTR involved in inflammation and is abnormally elevated in varied kidney diseases offers a novel target for the treatment of renal inflammation and subsequent fibrosis. Thus, we hypothesized that treatment with a selective inhibition of HuR function with a small molecule, KH-3, would down-regulate HuR-targeted proinflammatory transcripts thereby improving glomerulosclerosis in experimental nephritis, where glomerular cellular HuR is elevated. Three experimental groups included normal and diseased rats treated with or without KH-3. Disease was induced by the monoclonal anti-Thy 1.1 antibody. KH-3 was given via daily intraperitoneal injection from day 1 after disease induction to day 5 at the dose of 50 mg/kg BW/day. At day 6, diseased animals treated with KH-3 showed significant reduction in glomerular HuR levels, proteinuria, podocyte injury determined by ameliorated podocyte loss and podocin expression, glomerular staining for periodic acid-Schiff positive extracellular matrix proteins, fibronectin and collagen IV and mRNA and protein levels of profibrotic markers, compared with untreated disease rats. KH-3 treatment also reduced disease-induced increases in renal TGFβ1 and PAI-1 transcripts. Additionally, a marked increase in renal NF-κB-p65, Nox4, and glomerular macrophage cell infiltration observed in disease control group was largely reversed by KH-3 treatment. These results strongly support our hypothesis that down-regulation of HuR function with KH-3 has therapeutic potential for reversing glomerulosclerosis by reducing abundance of pro-inflammatory transcripts and related inflammation.

Outcomes of normotensive IgA nephropathy patients with mild proteinuria who have impaired renal function

Purpose: Typically, IgA nephropathy is a slowly progressive type of glomerulonephritis. High-grade proteinuria and hypertension are predictors of reduced kidney function. However, we found some normotensive patients with mild proteinuria could exhibit impaired renal function at the time of IgAN diagnosis. We therefore conduct a study to highlight the occurrence of these cases and to define their clinical characteristics and outcomes.

Methods: The clinical, laboratory, pathological manifestations and outcomes of these IgAN patients were collected and were compared with normotensive IgA nephropathy patients with mild proteinuria and normal renal function. Patients were analyzed according to different pathological characteristics. Survival curves were constructed according to the Kaplan–Meier method.

Results: Of all normotensive IgA nephropathy patients with mild proteinuria, 108 (10.1%) patients had impaired renal function. Ischemic sclerosis (79 patients) and fibrous crescent (25 patients) were the main pathological characteristics. Macroscopic hematuria (1.3%), prodromal infection (13.9%) and high serum IgA (11.4%) were significantly lower prevalences, but only proteinuria (26.6%) was more common in ischemic sclerosis group patients. Only hematuria were not found in ischemic sclerosis group and crescent group patients. The median follow-up were about 5 years. Patients in crescent group had a poor outcome compared with patients in ischemic sclerosis group.

Conclusions: Some normotensive IgA nephropathy patients with mild proteinuria had impaired renal function at diagnosis. Ischemic sclerosis and fibrous crescent were the main pathological features in these patients. Patients in the crescent group had a worse outcome than patients in the ischemic sclerosis group.

Association between native T1 mapping of the kidney and renal fibrosis in patients with IgA nephropathy

Introduction

IgA nephropathy (IgAN) is the commonest global cause of glomerulonephritis. Extent of fibrosis, tubular atrophy and glomerulosclerosis predict renal function decline. Extent of renal fibrosis is assessed with renal biopsy which is invasive and prone to sampling error. We assessed the utility of non-contrast native T1 mapping of the kidney in patients with IgAN for assessment of renal fibrosis.

Methods

Renal native T1 mapping was undertaken in 20 patients with IgAN and 10 healthy subjects. Ten IgAN patients had a second scan to assess test-retest reproducibility of the technique. Native T1 times were compared to markers of disease severity including degree of fibrosis, eGFR, rate of eGFR decline and proteinuria.

Results

All patients tolerated the MRI scan and analysable quality T1 maps were acquired in at least one kidney in all subjects. Cortical T1 times were significantly longer in patients with IgAN than healthy subjects (1540 ms ± 110 ms versus 1446 ± 88 ms, p = 0.038). There was excellent test-retest reproducibility of the technique, with Coefficient-of-variability of axial and coronal T1 mapping analysis being 2.9 and 3.7% respectively. T1 correlated with eGFR and proteinuria (r = − 0.444, p = 0.016; r = 0.533, p = 0.003 respectively).

Patients with an eGFR decline > 2 ml/min/year had increased T1 times compared to those with a decline < 2 ml/min/year (1615 ± 135 ms versus 1516 ± 87 ms, p = 0.068), and T1 time was also higher in patients with a histological ‘T’-score of > 0, compared to those with a ‘T’-score of 0 (1575 ± 106 ms versus 1496 ± 105 ms, p = 0.131), though not to significance.

Conclusions

Cortical native T1 time is significantly increased in patients with IgAN compared to healthy subjects and correlates with markers of renal disease. Reproducibility of renal T1 mapping is excellent. This study highlights the potential utility of native T1 mapping in IgAN and other progressive nephropathies, and larger prospective studies are warranted.

Electronic supplementary material

The online version of this article (10.1186/s12882-019-1447-2) contains supplementary material, which is available to authorized users.

The Prognostic Value of Histopathologic Lesions in Native Kidney Biopsy Specimens: Results from the Boston Kidney Biopsy Cohort Study

Background Few studies have evaluated whether histopathologic lesions on kidney biopsy provide prognostic information beyond clinical and laboratory data.Methods We enrolled 676 individuals undergoing native kidney biopsy at three tertiary care hospitals into a prospective, observational cohort study. Biopsy specimens were adjudicated for semiquantitative scores in 13 categories of histopathology by two experienced renal pathologists. Proportional hazards models tested the association between histopathologic lesions and risk of kidney disease progression (≥40% eGFR decline or RRT).Results Mean baseline eGFR was 57.5±36.0 ml/min per 1.73 m² During follow-up (median, 34.3 months), 199 individuals suffered kidney disease progression. After adjustment for demographics, clinicopathologic diagnosis, and laboratory values, the following lesions (hazard ratio; 95% confidence interval) were independently associated with progression: inflammation in nonfibrosed interstitium (0.52; 0.32 to 0.83), moderate and severe versus minimal interstitial fibrosis/tubular atrophy (2.14; 1.24 to 3.69 and 3.42; 1.99 to 5.87, respectively), moderate and severe versus minimal global glomerulosclerosis (2.17; 1.36 to 3.45 and 3.31; 2.04 to 5.38, respectively), moderate and severe versus minimal arterial sclerosis (1.78; 1.15 to 2.74 and 1.64; 1.04 to 2.60, respectively), and moderate and severe versus minimal arteriolar sclerosis (1.63; 1.08 to 2.46 and 2.33; 1.42 to 3.83, respectively). An 11-point chronicity score derived from semiquantitative assessments of chronic lesions independently associated with higher risk of kidney disease progression (hazard ratio per one-point increase, 1.19; 95% confidence interval, 1.12 to 1.27).Conclusions Across a diverse group of kidney diseases, histopathologic lesions on kidney biopsy provide prognostic information, even after adjustment for proteinuria and eGFR.

The Natural Course of Biopsy-Proven Isolated Microscopic Hematuria: a Single Center Experience of 350 Patients

The increasing interest in healthcare and health screening events is revealing additional cases of asymptomatic isolated microscopic hematuria (IMH). However, a consensus of the evaluation and explanation of the IMH prognosis is controversial among physicians. Here, we present the natural course of IMH together with the pathological diagnosis and features to provide supportive data when approaching patients with IMH. We retrospectively evaluated 350 patients with IMH who underwent a renal biopsy between 2002 and 2011, and the pathological diagnosis and chronic histopathological features (glomerulosclerosis, interstitial fibrosis, and tubular atrophy) were reviewed. Deterioration of renal function was examined during follow up. The patients with IMH were evaluated for a mean of 86 months. IgA nephropathy was the most common diagnosis in 164 patients (46.9%). Chronic histopathological changes were observed in 166 (47.4%) but was not correlated with proteinuria or a decline in renal function. Ten patients developed proteinuria, and all of them had IgA nephropathy. Three patients progressed to chronic kidney disease with an estimated glomerular filtration rate < 60 mL/min/1.73 m(2) but none progressed to end stage renal disease. In conclusion, IMH had a generally benign course during 7-years of observation, although IgA nephropathy should be monitored if it progresses to proteinuria. Future prospective randomized studies may help conclude the long-term prognosis and lead to a consensus for managing IMH.

Proteinuria during Follow-Up Period and Long-Term Renal Survival of Childhood IgA Nephropathy

Background

Proteinuria is the most important risk factor for IgA nephropathy progression. The purpose of this study is to evaluate the long-term outcome and risk factors for poor prognosis in childhood IgA nephropathy.

Methods

Patients who were diagnosed with IgA nephropathy between 1972 and 1992 at the Tokyo Metropolitan Kiyose Children’s Hospital were included. We analyzed risk factors for progression to end-stage kidney disease (ESKD) and chronic renal insufficiency (CRI) using Kaplan-Meier method and multivariate analyses of Cox proportional hazard model.

Results

One hundred patients were included and the median observation period was 11.8 years. Twelve and 17 patients progressed to ESKD and CRI, respectively. The survival probabilities were 90.0% at 10 years and 79.8% at 20 years for ESKD, and 86.1% at 10 years and 72.3% at 20 years for CRI. Notably, patients with heavy proteinuria with hypoalbuminemia during follow-up period showed extremely poor prognosis. In this group, the survival rate at 10 years from ESKD and CRI was 40.6% and 20.8%, respectively. By multivariate analysis, proteinuria at diagnosis and proteinuria during follow-up period were risk factors for ESKD, whereas glomeruli showing mesangial proliferation ≥50% and proteinuria during follow-up period were risk factors for CRI. Patients without heavy proteinuria during follow-up period did not develop CRI and 63% of patients with mild proteinuria during follow-up period showed no proteinuria at the last observation.

Conclusions

The degree of proteinuria during follow-up period is the strongest risk factor for ESKD and CRI.

IgA nephropathy

Globally, IgA nephropathy (IgAN) is the most common primary glomerulonephritis that can progress to renal failure. The exact pathogenesis of IgAN is not well defined, but current biochemical and genetic data implicate overproduction of aberrantly glycosylated IgA1. These aberrant immunoglobulins are characterized by galactose deficiency of some hinge-region O-linked glycans. However, aberrant glycosylation alone is insufficient to induce renal injury: the participation of glycan-specific IgA and IgG autoantibodies that recognize the undergalactosylated IgA1 molecule is required. Glomerular deposits of immune complexes containing undergalactosylated IgA1 activate mesangial cells, leading to the local overproduction of cytokines, chemokines and complement. Emerging data indicate that mesangial-derived mediators that are released following mesangial deposition of IgA1 lead to podocyte and tubulointerstitial injury via humoral crosstalk. Patients can present with a range of signs and symptoms, from asymptomatic microscopic haematuria to macroscopic haematuria. The clinical progression varies, with 30-40% of patients reaching end-stage renal disease 20-30 years after the first clinical presentation. Currently, no IgAN-specific therapies are available and patients are managed with the aim of controlling blood pressure and maintaining renal function. However, new therapeutic approaches are being developed, building upon our ever-improving understanding of disease pathogenesis.

Endothelial cell injury in acute and chronic glomerular lesions in patients with IgA nephropathy

Endothelial cell injury may contribute to the progression of various glomerular diseases. In the present study, we examined glomerular capillary injury in acute and chronic glomerular lesions in patients with Immunoglobulin A nephropathy (IgAN). We selected renal biopsy samples of IgAN (n = 200), and glomerular capillary injury in the acute and chronic glomerular lesions was assessed using immunohistochemistry for CD34 and electron microscopy. We examined the correlations between acute and chronic glomerular lesions and proteinuria, hematuria, and the renal function. The injured glomerular capillaries in the acute glomerular lesions were characterized morphologically by the separation of CD34+ endothelial cells from the glomerular basement membrane and the loss of glomerular endothelial cells and capillaries, together with inflammatory cell infiltration, fibrin exudation, rupture of the glomerular basement membrane, and/or crescent formation. In addition, the injured capillaries in the chronic glomerular lesions were characterized by the loss of CD34+ glomerular endothelial cells and capillaries exhibiting segmental and global glomerular sclerosis with or without fibrous crescents. In the acute glomerular lesions, the presence of endocapillary hypercellularity, fibrinoid necrosis, and cellular and fibrocellular crescents correlated significantly with hematuria, with or without proteinuria. In the chronic glomerular lesions, a significant relationship was evident between segmental or global sclerosis and proteinuria and/or the serum creatinine level. In conclusion, injuries of glomerular capillaries and the loss of endothelial cells occurred in the acute and chronic glomerular lesions in IgAN and may contribute to the development of hematuria, proteinuria, and renal dysfunction.

Risk factors for persistent proteinuria after a 2-year combination therapy for severe childhood IgA nephropathy

BACKGROUND

Although a 2-year combination therapy is effective for severe childhood immunoglobulin A (IgA) nephropathy, proteinuria persists in some patients even after the treatment.

METHODS

Seventy-nine patients aged <18 years with IgA nephropathy in which >80 % of glomeruli showed mesangial proliferation were enrolled in the study. Risk factors for persistent proteinuria after combination therapy were investigated using multivariate logistic regression analysis.

RESULTS

Proteinuria (≥0.2 g/1.73 m(2)/day) persisted in 27 patients (34 %) after the combination therapy. Twenty-four-hour urinary protein excretion, rate of glomeruli with crescents, rate of glomeruli with segmental sclerosis and rate of glomeruli with global sclerosis at diagnosis were higher in patients with persistent proteinuria than those without. In the multivariate analysis, 24-h urinary protein excretion [odds ratio (OR) 6.9; 95 % confidence interval (CI) 2.1-27.8; p = 0.001] and rate of glomeruli with crescents (OR 3.8; 95 % CI 1.1-13.9; p = 0.03) were independent risk factors for persistent proteinuria. Analysis of the receiver operating characteristic curve demonstrated that the most accurate cut-off values to detect persistent proteinuria were a urinary protein excretion of 1.32 g/1.73 m(2)/day and a 14 % rate of glomeruli with crescents.

CONCLUSIONS

In our cohort, urinary protein excretion and rate of glomeruli with crescents at diagnosis were independent risk factors for persistent proteinuria after the combination therapy.

Pathology of IgA nephropathy

IgA nephropathy is defined by the presence of IgA-dominant or co-dominant immune deposits within glomeruli. Biopsy specimens meeting these diagnostic criteria have a range of histological changes that are reflected in the variable clinical course of IgA nephropathy. The impact of histology on outcomes in IgA nephropathy has been clarified in a number of large retrospective clinicopathological studies. These studies have consistently demonstrated that the stage of disease at presentation, as indicated by the extent of interstitial fibrosis and tubular atrophy in the biopsy, is the strongest histological predictor of renal survival. The effect of active proliferative lesions on the disease course is less clear cut, owing in part to considerable treatment bias in most published retrospective studies. There is evidence that endocapillary hypercellularity and cellular crescents are responsive to immunosuppressive therapy, but this observation requires confirmation in prospective randomized controlled trials. Future challenges include improving the reproducibility of histological scoring, particularly for the presence and extent of endocapillary lesions, and to improve prognostic modelling by combining histological data with clinical variables and biomarker data.

Association of URG11 and Twist with clinical pathological characteristics and prognosis in patients with IgA nephropathy

BACKGROUND

Our previous studies demonstrated that URG11 is involved in hypoxia-induced tubular epithelial-mesenchymal transition and the development of kidney fibrosis in cellular and animal models. The objective of this study was to determine the expression levels of URG11 in kidneys with IgA nephropathy (IgAN), and the association of URG11 with various clinical parameters.

METHODS

We analysed the degree of expression and localization of URG11 in biopsies from kidneys with IgAN, and correlated their immunostaining levels with various clinical and histological parameters. We also analysed the correlation between the expression of URG11 and Twist in the renal interstitium with renal survival.

RESULTS

URG11 was strongly expressed in the cytoplasm of tubular epithelial cells obtained from kidneys of patients with IgAN. However, there was little positive staining for URG11 in the renal tubules of normal kidneys (P = 0.024). URG11 protein levels in the tubulointerstitium were inversely correlated with estimated glomerular filtration rates (eGFRs) (r = -0.305, P = 0.038) and the percentage of tubulointerstitial fibrosis (r = 0.350, P = 0.023). Moreover, a high level of URG11 correlated with the activation of Twist expression and E-cadherin repression in patients with IgAN (P = 0.000 and 0.041, respectively). Multivariate analyses indicated that a combination of high URG11 and Twist expression was an independent prognostic factor [relative ratio, RR 4.738 (95% CI: 1.040, 21.591), P = 0.044] of IgAN.

CONCLUSIONS

Our findings suggest that URG11 staining in renal biopsy specimens might be a novel histological marker for progression in IgAN patients.

The safety and short-term efficacy of aliskiren in the treatment of immunoglobulin a nephropathy--a randomized cross-over study

Background

Laboratory research and previous study suggest that aliskiren, a direct renin inhibitor, has anti-proteinuric effects. We conducted a randomized crossover study to evaluate the anti-proteinuric effect of aliskiren in patients with immunoglobulin A (IgA) nephropathy.

Methods

We studied 22 patients with biopsy-proven IgA nephropathy and persistent proteinuria despite angiotensin converting enzyme (ACE) inhibitor or angiotensin receptor blocker (ARB). Patients were randomized to either oral aliskiren 300 mg/day or placebo for 16 weeks and then crossed over to the other treatment arm after a washout period. Proteinuria, estimated glomerular filtration rate (eGFR), blood pressure, and serum potassium were monitored.

Results

After aliskiren treatment, there was a significant reduction in proteinuria in 4 weeks (1.76±0.95 to 1.03±0.69 g:g-Cr, p<0.0001), which remained at a low level throughout the treatment period. There was a significant difference in proteinuria between the aliskiren and placebo groups from 4 to 16 weeks after treatment (p<0.01 for all comparisons). After aliskiren treatment, there were modest but statistically significant reductions in eGFR (57.2±29.1 to 54.8±29.3 ml/min/1.73 m², p = 0.013) and diastolic blood pressure (72.6±12.3 to 66.2±11.2 mmHg, p<0.0001). None of the patient developed severe hyperkalemia (serum potassium ≥6.0 mmol/l) during the study period.

Conclusions

Aliskiren has anti-proteinuric effect in patients with IgA nephropathy and persistent proteinuria despite ACE inhibitor or ARB. Further studies are needed to confirm the renal protecting effect of direct renin inhibition in chronic proteinuric kidney diseases.

Trial Registration

ClinicalTrials.gov NCT00870493

Treatment of early immunoglobulin A nephropathy by angiotensin-converting enzyme inhibitor

BACKGROUND

The treatment of immunoglobulin A (IgA) nephropathy with normal renal function and minimal proteinuria is unknown.

METHODS

We randomly assigned 60 patients with IgA nephropathy, proteinuria <0.5 g/day, normal blood pressure and renal function to ramipril 2.5 mg daily or no treatment. Patients were followed for 5 years for the development of hypertension, proteinuria, or impaired renal function.

RESULTS

The blood pressure of the treatment group was marginally lower than the control group throughout the study period. At 60 months, the event-free survival was marginally higher for the treatment group as compared with the control group (81.1% vs 70.5%, P=.27). The proteinuria-free survival was similar at 82.9% and 79.3% for the treatment and control groups, respectively (P=.6); hypertension-free survival was 86.4% and 79.3% (P=.2). After 60 months of follow-up, the estimated glomerular filtration rate (GFR) was 108.1±29.0 mL/min/1.73 m(2) for the treatment group and 105.7±17.7 mL/min/1.73 m(2) for the control group (P=.7), but the difference was not statistically significant. None of the patients developed impaired renal function. The rate of GFR decline was similar between the treatment and control groups (-0.39±2.57 vs -0.59±1.63 mL/min/1.73 m(2) per year, respectively, P=.7). In general, the study medication was well tolerated. Two patients needed to stop prematurely because of cough and dizziness.

CONCLUSION

For early IgA nephropathy patients with minimal proteinuria, normal blood pressure, and normal renal function, treatment with 2.5 mg/daily of ramipril for 5 years does not offer any benefit.

Role of myofibroblasts and collagen type IV in patients of IgA nephropathy as markers of renal dysfunction

The aim was to evaluate the role of a-smooth muscle actin (SMA) and collagen type IV as markers of chronicity in renal biopsies of IgA nephropathy patients and to correlate the degree of their interstitial expression with renal function as judged by serum creatinine. Renal biopsies from 29 clinically, histologically and immunologically confirmed cases of IgA nephropathy were reviewed to assess activity and chronicity indices. Immunohistochemical stains for α-SMA and collagen type IV was performed on 23 patients with adequate tissue available in the block. The interstitial expression of α-SMA and collagen type IV was then correlated with chronicity and activity indices, serum creatinine and 24 hours urinary protein. Pearson's coefficient of correlation, unpaired-t test were used for statistical analysis. α-SMA and collagen type IV were shown to be expressed in the interstitium in all 22 cases showing interstitital fibrosis. Both showed a similar distribution pattern with predominant periglomerular and peritubular positivity. The cases were divided into two groups (low and high grade) depending on the percentage of interstitial area showing positivity for these two antibodies. On statistical analysis, the expression of both a-smooth muscle actin and collagen type IV showed a striking correlation with the histological chronicity index (P<0.01). A positive correlation was also noted with the serum creatinine at the time of diagnosis. It is seen that an immunohistochemical approach to grading interstitial fibrosis as in this study is far simpler than the histological grading systems prevalent and is an important baseline prognostic indicator.

Long-term study of mycophenolate mofetil treatment in IgA nephropathy

Since the efficacy of mycophenolate mofetil (MMF) to treat immunoglobulin A (IgA) nephropathy is controversial, we extended our original study by following 40 Chinese patients with established IgA nephropathy for 6 years. All patients were maintained on their angiotensin blockade medication and half were randomized to receive MMF for 6 months. After 6 years, 11 patients required dialysis (2 from the MMF and 9 from the control group). Significantly, only 3 treated (as compared to 10 control) patients reached the composite end point of serum creatinine doubling or end-stage renal disease. Linear regression showed the annualized decline in the estimated glomerular filtration rate was significantly less in the MMF-treated group. Urinary protein excretion and the albumin-to-creatinine ratio were lower with MMF treatment during the first 24 months, beyond which there was no difference between groups. Multivariable Cox regression analysis showed that the baseline estimated glomerular filtration rate and proteinuria, and change in the urine albumin-to-creatinine ratio at 1 year to be important predictors of progression to end-stage renal disease. We found that among Chinese patients with IgA nephropathy who had mild histologic lesions and persistent proteinuria despite maximal angiotensin blockade, MMF treatment may result in transient and partial remission of proteinuria in the short-term and renoprotection in the long-term.

The Oxford classification of IgA nephropathy: pathology definitions, correlations, and reproducibility

Pathological classifications in current use for the assessment of glomerular disease have been typically opinion-based and built on the expert assumptions of renal pathologists about lesions historically thought to be relevant to prognosis. Here we develop a unique approach for the pathological classification of a glomerular disease, IgA nephropathy, in which renal pathologists first undertook extensive iterative work to define pathologic variables with acceptable inter-observer reproducibility. Where groups of such features closely correlated, variables were further selected on the basis of least susceptibility to sampling error and ease of scoring in routine practice. This process identified six pathologic variables that could then be used to interrogate prognostic significance independent of the clinical data in IgA nephropathy (described in the accompanying article). These variables were (1) mesangial cellularity score; percentage of glomeruli showing (2) segmental sclerosis, (3) endocapillary hypercellularity, or (4) cellular/fibrocellular crescents; (5) percentage of interstitial fibrosis/tubular atrophy; and finally (6) arteriosclerosis score. Results for interobserver reproducibility of individual pathological features are likely applicable to other glomerulonephritides, but it is not known if the correlations between variables depend on the specific type of glomerular pathobiology. Variables identified in this study withstood rigorous pathology review and statistical testing and we recommend that they become a necessary part of pathology reports for IgA nephropathy. Our methodology, translating a strong evidence-based dataset into a working format, is a model for developing classifications of other types of renal disease.

Pathological predictors of prognosis in immunoglobulin A nephropathy: a review

PURPOSE OF REVIEW

To provide a review and discussion of histological prognostic indicators in immunoglobulin A (IgA) nephropathy (IgAN).

RECENT FINDINGS

A variety of histological parameters and classifications have been used to attempt to predict prognosis in patients with IgAN. Grading systems used thus far do not consistently provide a useful adjunct to clinical prognostic parameters. This may be due to the variety of grading systems used, to inconsistent patient recruitment processes, and to the use of actuarial renal survival as an end point. This has led to the development of a new IgAN classification proposal by the International IgA Nephropathy Network in conjunction with the Renal Pathological Society. Additional potential markers of disease progression currently under investigation include glomerular parameters such as number and size, markers of podocyte function and of complement activation, inflammatory infiltrates and mediators of tubulointerstitial fibrosis.

SUMMARY

There is a need for an internationally accepted, reproducible and clinically meaningful pathological classification of IgAN. Such a classification is currently being developed. By using only reproducible, single parameters and validating them on a large group of cases from all over the world, it is hoped that a useful clinically predictive tool will be developed.

Concise semiquantitative histological scoring system for immunoglobulin A nephropathy

AIM

Immunoglobulin A nephropathy (IgAN) is a common and progressive glomerulonephritis. Histological lesions of IgAN are variable and considered as a risk factor for renal outcome. Establishing a relatively concise histological semiquantitative scoring system would be valuable in clinical practice.

METHODS

Renal biopsy sections of 293 patients with primary IgAN from two centres in China were reviewed. A histological scoring system was established based on multivariate survival analysis of semiquantitative histological indices, using end-stage renal disease (ESRD) as the end-point event.

RESULTS

Four indices--extracapillary glomerular activity index (exGAI), mesangial proliferation index (MsI), glomerular chronicity index (GCI) and tubulointerstitial chronicity index (TCI)--independently correlated with ESRD (relative risk (RR) = 1.16, 2.27, 1.29 and 1.80, respectively). The four indices and the sum of their scores (Total I) constituted the scoring system. Patients with exGAI of 4 or more, GCI of 4 or more, MsI of 2 or more and TCI of 2 or more were considered as having a higher risk for progression (P < 0.05). A score of 4 or more on the exGAI index could identify the patients who should be treated with immunosuppressive drugs, which showed a lower incidence of ESRD than that without (24.3% vs 52.4%, P = 0.031).

CONCLUSION

It suggested that the present concise scoring system could serve as prognostic and therapeutic indications.

Continental variations in IgA nephropathy among Asians

BACKGROUND/AIMS

Local variations in patient demographics and medical practice can contribute to differences in renal outcomes in patients with IgA nephropathy. We report the experiences of two groups of Asians with IgA nephropathy across continents.

MATERIALS AND METHODS

We retrospectively examined two cohorts of Asian patients with IgA nephropathy from The King Chulalongkorn Memorial Hospital registry, Thailand (1994 - 2005), and The Metropolitan Toronto Glomerulonephritis registry, Canada (1975 - 2006), and compared their baseline characteristics. Slope of estimated glomerular filtration rate (eGFR) in each group was approximated using separate repeated measures regression models for each country.

RESULTS

There were 152 Canadian and 76 Thai patients. At the time of first presentation, Thai patients were more likely to be female (63.2 vs. 44.1%, p = 0.01), have less baseline proteinuria (1.2 vs. 1.7 g/d, p = 0.08) and more likely to receive angiotensin-converting enzyme inhibitors (ACE-I) or angiotensin receptor blockers (ARB) (64.0 vs. 15.2%, p < 0.01), or prednisone (41.3 vs. 4.6%, p < 0.01). The annual change in estimated glomerular filtration rate (eGFR) for the Thai and Canadian groups were -0.82 ml/min/1.73 m2/year and -3.35 ml/min/1.73 m2/year, respectively, after adjustment for age, sex, mean arterial pressure (MAP), proteinuria, body mass index, Haas histological grade, chronicity scores and baseline medications.

CONCLUSIONS

Although disease severity was similar among IgA nephropathy patients in Canada and Thailand, more Thai patients were on ACE-I/ARB or prednisone therapy at baseline. Further prospective research is needed to explore international differences in demographic and environmental factors, health resources, and disease management to determine how they may impact long-term outcomes in Asians with IgA nephropathy.

Kidney allocation to liver transplant candidates with renal failure of undetermined etiology: role of percutaneous renal biopsy

The feasibility, value and risk of percutaneous renal biopsy (PRB) in liver transplant candidates with renal failure are unknown. PRB was performed on 44 liver transplant candidates with renal failure of undetermined etiology and glomerular filtration rate (GFR) <40 mL/min/1.73 m(2) (n = 37) or on renal replacement therapy (RRT) (n = 7). Patients with >or=30% interstitial fibrosis (IF), >or=40% global glomerulosclerosis (gGS) and/or diffuse glomerulonephritis were approved for simultaneous-liver-kidney (SLK) transplantation. Prebiopsy GFR, urinary sodium indices, dependency on RRT and kidney size were comparable between 27 liver-transplant-alone (LTA) and 17 SLK candidates and did not relate to the biopsy diagnosis. The interobserver agreement for the degree of IF or gGS was moderate-to-excellent. After a mean of 78 +/- 67 days, 16 and 8 patients received LTA and SLK transplants. All five LTA recipients on RRT recovered kidney function after transplantation and serum creatinine was comparable between LTA and SLK recipients at last follow-up. Biopsy complications developed in 13, of these, five required intervention. PRB is feasible in liver transplant candidates with renal failure and provides reproducible histological information that does not relate to the pretransplant clinical data. Randomized studies are needed to determine if PRB can direct kidney allocation in this challenging group of liver transplant candidates.

Focal segmental glomerulosclerosis in mild IgA nephropathy: a clinical-pathologic study

BACKGROUND

The significance of focal segmental glomerulosclerosis (FSGS) in mild IgA nephropathy is uncertain.

METHODS

All consecutive renal biopsies performed between 1996 and 2005 in adults with a diagnosis of mild IgA nephropathy (Lee Grade 1 or 2) at St Paul's Hospital, Vancouver, Canada, were reviewed.

RESULTS

Seventy-five patients were included, 26 (35%) with IgA nephropathy and FSGS (FSGS+ group) and 49 (65%) with IgA nephropathy without FSGS (FSGS- group). The mean follow-up was 3 years. At the time of renal biopsy the FSGS+ group had a lower eGFR (60 versus 73 mL/min, P = 0.02), lower serum albumin (38 versus 41 g/L, P = 0.02), higher mean arterial pressure (103 versus 97 mmHg, P = 0.03) and greater protein excretion (3.0 versus 1.3 g/day, P < 0.01) than the FSGS- group. On histology, the FSGS+ group had a higher percentage of obsolete glomeruli (23.4% versus 12.7%, P < 0.01), and 31% of FSGS+ biopsies had >or=25% tubular atrophy/interstitial fibrosis while this was not observed in the FSGS- group (P < 0.01). The primary outcome measure, DeltaGFR, was -2.56 mL/ min/year in the FSGS+ group and +1.14 mL/min/year in the FSGS- group, difference: 3.70 mL/min/year (P = 0.03) (univariate). In the multivariate model, the FSGS+ group declined at 0.19 mL/min/year (-14.16, 13.78) and the FSGS- group improved at 2.85 mL/min/year (-11.64, 17.34), difference 3.04 mL/min/year, P = 0.18.

CONCLUSIONS

Our study suggests that the focal segmental glomerulosclerosis lesion and associated clinical and pathologic findings in patients with mild IgA nephropathy are associated with a worse renal outcome.

Malignant hypertension in IgA nephropathy was not associated with background pathological phenotypes of glomerular lesions

BACKGROUND

It was reported that IgA nephropathy (IgAN) was the major cause of secondary malignant hypertension (MHT). However, the pathogenesis of MHT secondary to IgAN (IgAN-MHT) is unknown and its association with glomerular pathological phenotypes remains inconclusive. The present study aimed to investigate whether glomerular pathological phenotypes and anti-endothelial cell antibodies (AECA) were associated with the occurrence of IgAN-MHT.

METHODS

The glomerular pathological phenotypes of 45 patients with IgAN-MHT were analysed using Haas' histologic grading system of IgAN. Sera were collected from 34 of the 45 patients with IgAN-MHT, 19 patients with primary MHT, 41 patients with non-MHT IgAN and 10 healthy volunteers. AECA of both IgG and IgA isotypes were detected by western blot analysis using human umbilical vein endothelial cell lysate as antigen.

RESULTS

In the 45 patients with IgAN-MHT, 7 (15.56%), 5 (11.11%), 13 (28.89%), 9 (20%) and 11 (24.44%) patients were graded as Hass I, II, III, IV and V, respectively. Although the severity of non-ischaemic sclerosis, crescents and mesangial proliferation were significantly different between patients with different grades, the levels of blood pressure, SCr and proteinuria at presentation were comparable. Eleven and four protein bands of endothelial proteins could be blotted by AECA-IgG and AECA-IgA in sera from patients with IgAN-MHT. The prevalences of anti-121 kD AECA-IgG (15/34) and anti-92 kD AECA-IgA (10/34) in IgAN-MHT were significantly higher than that of primary MHT, non-MHT IgAN and normal controls, respectively. Patients with anti-92 kD AECA-IgA had more severe glomerular ischaemic sclerosis (6.25-92.86%, median 39.61%) than those without (0-91.67%, median 18.18%, P = 0.035). There was no significant difference in the prevalence of AECA between IgAN-MHT patients with different background glomerular lesions. Only one IgAN patient with MHT was found with both anti-121 kD AECA-IgG and anti-92 kD AECA-IgA. No particular manifestations were found.

CONCLUSIONS

The occurrence of IgAN-MHT was not associated with the background glomerular pathological phenotypes of IgAN. AECA might play a role in the pathogenesis of IgAN-MHT.

Prevalence and Implications of Isolated Microscopic Hematuria in Asymptomatic Chinese Pregnant Women

BACKGROUND

IgA nephropathy (IgAN) is the most common primary glomerulonephritis worldwide. However, the actual prevalence of microscopic hematuria and IgAN is unknown in the Chinese population.

METHODS

We screened 7,828 consecutive pregnant women for microscopic hematuria in the antenatal clinic of a tertiary referral center. Persistent microscopic hematuria was defined as urine Hemastix (Bayer Diagnostics, Hong Kong) of 1+ for red cells in two clinic visits. Subjects were referred to the renal clinic for specialist evaluation, including measurement of blood pressure, serum creatinine, urine bacterial culture, and quantification of proteinuria.

RESULT

There were 207 women (2.64%) with microscopic hematuria. Mean age was 31.8 +/- 5.0 years. In 101 patients (48.8%), there was proteinuria >0.1 g/day by quantitative assay. Hematuria was found to resolve before or shortly after delivery in 126 (60.9%) and 68 women (32.9%), respectively. Five patients (2.4%) had urinary tract infection proved by repeated urine culture, 1 had papillary necrosis, and 1 had duplex collecting system. Three patients were confirmed to have IgAN by renal biopsy; all had normal blood pressure and serum creatinine, but dysmorphic red cells in urine microscopy, and proteinuria of over 0.5 g/day that persisted after delivery. Renal biopsy on another woman showed no specific pathology. Two women were lost to follow-up, both with normal renal function and no detectable proteinuria. The overall prevalence of IgAN was 38 cases per 100,000 population (95% confidence interval: 8-112 cases).

CONCLUSION

Microscopic hematuria is not uncommon in pregnant women, and IgAN is present in a small proportion of these patients. Further study is needed to determine whether screening for microscopic hematuria would allow early diagnosis and improve the prognosis of these patients.

Genetic polymorphism of vascular endothelial growth factor: impact on progression of IgA nephropathy

BACKGROUND

Vascular endothelial growth factor (VEGF) plays a pivotal role in the capillary endothelial cell growth and proliferation and has known effects on glomerular microvascular permeability. Because certain VEGF polymorphisms are correlated with alterations in VEGF expression, we hypothesized that VEGF genetic polymorphisms may affect the renal survival and progression of primary IgA nephropathy.

METHODS

The study population consisted of 195 biopsy-proven IgA nephropathy patients at our center between 1984 and 2004. VEGF genotype polymorphism at -2578 positions was determined from peripheral blood leukocytes DNA using polymerase chain reaction methodologies. The primary end point was kidney survival as measured by the time interval from renal biopsy to end-stage renal disease or the requirement of renal replacement therapy.

RESULTS

In total, we studied 119 women (61%) and 76 men (39%), with a mean age of 35 +/- 10 yr at the time of renal biopsy. Observed genotype frequency was 55.6%, 38.8%, and 5.1% for CC, CA, and AA genotypes respectively. Baseline characteristics did not differ significantly between three genotype groups for patient age, sex, prevalence of hypertension, degree of proteinuria, initial serum creatinine concentration, and the histological grading. After a median follow-up period of 11 yr, doubling of the baseline serum creatinine occurred in 107 of them; 99 patients reached end-stage renal disease requiring renal replacement therapy with a median renal survival of 88 months. The kidney survival in the CC genotype subgroup was similar to that of the CA/AA genotype subgroup during the first 2 yr but became worse than the latter thereafter (log-rank test P = 0.023). The kidney survival rates at the end of 6 yr were 76.8% in the CA genotype, 67.0% in the CC, and 50.0% in the AA genotype groups. Unadjusted hazard ratio of developing end-stage renal disease was 2.65 (95% CI, 1.16 to 6.06) for the CC group as compared to the CA/AA group. The influence of VEGF genotype upon renal survival, however, was not significant after multivariate Cox regression analysis.

CONCLUSION

Our preliminary results raise the concern that the CC genotype of the VEGF promoter at -2578 position might be associated with increased risk of renal progression in patients with IgA nephropathy.

Fibroblast-specific protein 1 is a specific prognostic marker for renal survival in patients with IgAN

BACKGROUND

There is little direct evidence that fibroblasts are involved in the progression of the renal interstitial fibrosis in human glomerulonephritis. With the availability of a new specific marker for fibroblasts, we determined the presence of fibroblasts in kidneys with IgA nephropathy (IgAN) and correlated their numbers with various clinical parameters. In particular, we also prospectively asked if the number of fibroblasts in the renal interstitium correlates with prognosis.

METHODS

Cells positive for fibroblast-specific protein 1 (FSP1) were localized in renal biopsy specimens using immunohistochemistry with anti-FSP1 antibody. Clinical features were analyzed by one-way analysis of variance (ANOVA) with the Bonferroni correction. To assess the prognostic impact of the number of FSP1+ fibroblasts on renal survival in 142 patients with normal serum creatinine, the relationship between covariates to renal survival were evaluated univariately using the log-rank test and multivariately using Cox proportional hazards.

RESULTS

Fibroblasts identified by their expression of FSP1 accumulate in areas showing severe interstitial fibrosis. Some tubular epithelial cells undergoing epithelial-mesenchymal transition (EMT) in fibrotic areas also express FSP1. Numbers of FSP1+ fibroblasts directly correlate with serum creatinine (r = 0.74, P < 0.0001) and inversely correlate with estimated creatinine clearance (r = -0.54, P < 0.0001), and by multivariate analysis, the clinical factors influencing renal survival are urinary protein excretion [> or = 1.0 g/day, relative risk (RR) = 4.20, P= 0.032], hypertension (RR 5.85, P = 0.0027), and > or = 20 FSP1+ fibroblasts per high power field (HPF) (RR 7.39, P = 0.0015). Staining for FSP1+ fibroblasts is largely nonoverlapping with alpha-smooth muscle actin+ (alpha-SMA) cells in the interstitium.

CONCLUSION

The target protein FSP1 identifies human fibroblasts and tubular epithelium undergoing EMT, and distinguishes them from the diaspora of alpha-SMA+ vascular smooth muscle cells. FSP1+ fibroblasts are critically related to the progression of IgAN; consequently, staining FSP1 in renal biopsy specimens provides a valuable histologic index of progression.

Mycophenolate mofetil alleviates persistent proteinuria in IgA nephropathy

BACKGROUND

Mycophenolate mofetil (MMF) is increasingly used to treat primary glomerulopathies. Its effectiveness in IgA nephropathy (IgAN) remains unclear.

METHODS

Forty IgAN patients with persistent proteinuria (>1 g/24 hours) despite conventional treatment with blockers of the renin-angiotensin system were randomized to receive MMF for 24 weeks (group 1) or continue conventional therapy (group 2), and followed for 72 weeks. The primary end point was reduction of proteinuria by 50% or more over entry level.

RESULTS

Sixteen patients (80%) in group 1 versus six patients (30%) in group 2 reached the primary end point (P= 0.0019). Time-averaged change in proteinuria showed a significant decline in group 1, while control subjects displayed a modest rise (P= 0.003). By 72 weeks, the mean proteinuria was 62.0 +/- 7.7% (P= 0.003) and 120.5 +/- 14.1% (P= 0.351) that of the corresponding baseline value in group 1 and group 2, respectively. There was concomitant increase in serum albumin and decrease in serum IgA levels in group 1 but not group 2 patients. Baseline histologic grades, blood pressure control, and the rates of change in serum creatinine and creatinine clearance were not different between the two groups. Normalization in binding of polymeric IgA to cultured mesangial cells and serum interleukin-6 (IL-6) levels, which sustained to study end, was observed in group 1 but not group 2 subjects.

CONCLUSION

In selected patients with IgAN, MMF is effective in lowering proteinuria and ameliorating some of the putative pathogenetic abnormalities.

Histological grading of IgA nephropathy predicting renal outcome: revisiting H. S. Lee's glomerular grading system

BACKGROUND

The glomerular grading system is useful to compare biopsy specimens and to predict the natural course of disease in IgA nephropathy (IgAN), although no grading system can be perfect.

METHODS

H. S. Lee's grading system for IgAN was refined as follows: grade I, normal or focal mesangial cell proliferation; grade II, diffuse mesangial cell proliferation, or <25% of glomeruli with crescent (Cr)/segmental sclerosis (SS)/global sclerosis (GS); grade III, 25-49% of glomeruli with Cr/SS/GS; grade IV, 50-75% of glomeruli with Cr/SS/GS; grade V, >75% of glomeruli with Cr/SS/GS. This refined H. S. Lee grading system was then tested for clinical relevance on 187 patients with IgAN followed up for an average of 6.5 years (minimum, 3 years). In the survival analysis, a modified primary end-point (progressive renal disease) was used.

RESULTS

The glomerular grades were significantly related to hypertension, serum creatinine levels and the amounts of proteinuria at time of biopsy. By univariate analysis, glomerular grades, hypertension, renal insufficiency and significant proteinuria (> or =1 g/day) were significantly associated with progressive renal disease. By multivariate analysis using the Cox regression model, glomerular grades, renal insufficiency and significant proteinuria were independent prognostic factors for progressive renal disease. At the end of follow-up, glomerular grades were significantly related to serum creatinine levels, amounts of proteinuria, hypertension and progressive renal disease.

CONCLUSIONS

These findings indicate that the refined H. S. Lee grading system for IgAN is useful in assessing the patients' clinical outcome and is sufficiently simple and easy to reproduce as to be universally applicable in prognostic work.

Early prediction of IgA nephropathy progression: Proteinuria and AOPP are strong prognostic markers

BACKGROUND

Inflammation and oxidative stress have been incriminated in the pathogenesis of IgA nephropathy (IgAN). The aim of the present study was to assess whether markers reflecting these pathophysiologic processes, namely C-reactive protein (CRP) and advanced oxidation protein products (AOPP), would allow-in conjunction with clinical and histopathologic parameters-to predict disease progression.

METHODS

Between 1994 and 1997, 120 adult patients with biopsy-proven IgAN were included in a prospective cohort study, and followed until the end of 2002 or start of dialysis. In every patient, we determined plasma levels of CRP and AOPP. These parameters were included, together with clinical data, in a multivariate Cox proportional hazard regression analysis, with halving of baseline creatinine clearance as the primary renal end point.

RESULTS

A total of 51 patients reached the renal end point, including 30 who had to start dialysis. With multivariate analysis, the most potent independent risk factors of poor renal outcome were proteinuria > or =1 g/day [proportional hazard risk (HR) = 23.7, P= 0.0001], hypertension (HR = 8.13, P= 0.008), and AOPP plasma level (HR = 1.09 per 10 micromol/L, P= 0.042), whereas angiotensin II inhibitors were protective (HR = 0.19, P= 0.001).

CONCLUSION

Our data support the role of oxidative stress in the pathogenesis of IgAN and suggest that patients with proteinuria > or =1 g/day should be eligible for early implemented antioxidant and/or anti-inflammatory therapeutic strategies, with AOPP plasma level as a surrogate marker to evaluate their effects.

Role of differential and cell type-specific expression of cell cycle regulatory proteins in mediating progressive glomerular injury in human IgA nephropathy

The activities of cell cycle regulatory proteins have been reported to be associated with the development of pathological lesions in glomerulonephritis. To assess the cellular mechanisms underlying the mesangial cell proliferation and glomerulosclerosis in progressive human IgA nephropathy (IgAN), we examined the expression of E2F1, Rb, c-Myc, proliferating cell nuclear antigen (PCNA), cyclins (D1, E and A), cyclin-dependent kinase 2 (CDK2) and CDK inhibitors (p21(waf1), p27(kip1), 57(kip2) and p16(ink4a)) by immunohistochemistry in renal biopsy specimens. Terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) was also performed to detect the presence of apoptosis. In total, 51 cases of IgAN were categorized into four subgroups according to histological severity. A dramatic upregulation of E2F1 expression in mesangial cells was identified in proliferating glomeruli, which correlated well with the proliferation index. High endogenous expression of p27(kip1) and p57(kip2) by podocytes in normal glomeruli and glomeruli with minor lesions was observed to decrease in proliferating and sclerosing glomeruli; this pattern displayed a strong inverse correlation with the mean glomerulosclerosis score and the index of glomerular lesion. Increased apoptotic activity was identified in progressive glomerular lesions of advanced IgAN, which correlated with the proliferative activity in these lesions as assessed by total expression levels of PCNA and CDK2 in glomeruli, E2F1 expression levels in the mesangium, cyclin D1 expression levels in endothelium and the c-Myc glomerular staining score. Our results suggest that the onset and magnitude of mesangial cell proliferation and glomerulosclerosis is associated with the upregulation of E2F1 by mesangial cells and the downregulation of p27(kip1) and p57(kip2) by glomerular epithelial cells. The cell type-specific and coordinated regulation of proliferative and proapoptotic activities of cell cycle regulatory proteins may play an important role in mediating progressive glomerular injury in human IgAN.

Clinical significance of costimulatory molecules CD80/CD86 expression in IgA nephropathy

BACKGROUND

IgA nephropathy (IgAN) is the most common form of human glomerulonephritis. Tubulointerstitial inflammation with infiltration of mononuclear cells plays an important role in the progression of IgAN. Activation of T cells requires costimulatory signals through binding of CD28 receptor with cognate ligands (CD80/CD86) located on antigen-presenting cells (APC). To assess the clinical significance of this regulatory pathway participation in the pathogenesis of IgAN, a comprehensive immunohistologic evaluation was conducted on renal tissue of IgAN in different phases of progressive injury.

METHODS

Thirty-three cases of IgAN and ten cases of non-IgA mesangial proliferative glomerulonephritis (PGN) with minor tissue damage as controls were investigated. Monoclonal antibodies were used to assess the expression of CD80, CD86, CD68, CD14, CD45RO, human leukocyte antigen-DR (HLA-DR), and intercellular adhesion molecule-1 (ICAM-1) in renal tissues. Clinical and expression data were compared at the time of renal biopsy.

RESULTS

CD80+ and CD86+ cells were observed more in IgAN patients with progressive renal injury than in mild cases and controls. CD80 was limited to tubular epithelial cells and was complemented by HLA-DR expression. CD86 was expressed in the glomerulus, periglomerular area, and peritubular interstitium. Activated T cells (CD45RO+), monocytes (CD14+), macrophages (CD68+), and CD86 showed similar distributions. Positive correlations were found between CD86+ cells and CD45RO, CD14, and CD68 positive cells and between CD80+ tubuli and peritubular interstitial CD45RO+ cells. The number of interstitial CD86 positive cells and the percentage of CD80+ tubuli were correlated with renal function. Most CD86+ cells were monocyte/macrophages.

CONCLUSION

This study suggested that CD80 and CD86 activate T cells in IgAN, CD80/CD86 expressions correlated with renal function at the time of renal biopsy, and monocyte/macrophages and tubular epithelial cells act as APC.

Onset of Berger disease after Staphylococcus aureus infection: septic arthritis after anterior cruciate ligament reconstruction

Septic arthritis is rare in patients undergoing knee arthroscopic surgery. If the infection is due to Staphylococcus aureus, patients might experience fever, severe clinical syndromes, and extra-articular manifestations, including vasculitis and glomerulonephritis. We describe a case of onset of immunoglobulin A nephropathy (Berger disease) after S aureus septic arthritis complicating an anterior cruciate ligament surgical reconstruction. The patient had no previous history of renal disease, and renal function returned to normal after resolution of the knee infection. S aureus infection has been associated with several glomerular diseases, but this is the first report of the infection causing immunoglobulin A nephropathy. In addition, this is the first description of Berger disease after arthroscopic treatment, providing evidence that this disease might complicate the clinical course of orthopedic surgery.

Primary IgA nephropathy with low histologic grade and disease progression: is there a "point of no return"?

Histologic low-grade chronic renal lesions in 144 adults with primary immunoglobulin A (IgA) nephropathy were correlated with clinical parameters of disease progression over a median follow-up of 93 months. Using chronicity-based histologic grading, 50, 59, and 35 patients were glomerular grade (GG) 1a, GG1b, and GG2; 83 and 61 patients were tubulointerstitial grade (TIG) 1 and TIG2; and 25 patients had hyaline arteriolosclerosis. On follow-up, GG and TIG were predictive of disease progression by impairment of renal function, development of hypertension, and significant proteinuria (>1 g/d). Hyaline arteriolosclerosis correlated only with the development of hypertension. Histologic lesions GG1a or TIG1 predicted a significant low risk for disease progression compared with other renal lesions, regardless of the renal manifestation at the time of biopsy. Combined GG1a, TIG1, and isolated hematuria at the time of biopsy enhanced the sensitivity to determine early IgA nephropathy and to define a nonearly cohort with a higher risk of disease progression appropriate for recruitment into clinical therapeutic trials within realistic time frames. The significant risk of progression in other low-grade lesions, such as GG1b or TIG2, suggests that the point of no return in IgA nephropathy may occur much earlier than perceived and that delayed biopsy in these patients no longer may be justified.

CD44 expression in IgA nephropathy

Immunoglobulin A (IgA) nephropathy is a frequent, chronic renal disease characterized by a broad spectrum of clinical presentations and pathologic findings. CD44, a family of type I transmembrane glycoproteins involved in cell-cell and cell-matrix interactions, may orchestrate partially the cascade of inflammation, accumulation of myofibroblasts, and fibrosis leading to end-stage renal disease. To clarify the possible role of CD44 in the progression of IgA nephropathy, the expression of CD44 in glomeruli and the tubulointerstitial compartment was analyzed in 25 renal biopsy specimens of patients with IgA nephropathy and was correlated to histopathologic, serologic, and urinary parameters. The expression of CD44 correlated significantly with the degree of glomerular and interstitial damage, even better than the accumulation of alpha-smooth muscle actin-positive myofibroblasts, which is recognized as a reliable marker for the progression of IgA nephropathy. A positive correlation also was found between proteinuria and the expression of CD44 in the tubulointerstitial compartment. The glomerular and tubulointerstitial expression of CD44 correlated with the degree of renal damage in IgA nephropathy and could be a reliable marker of the progression of IgA nephropathy. CD44 may have a pivotal role in the cascade of renal inflammation and fibrosis.

Predicting progression in IgA nephropathy

Immunoglobulin A (IgA) nephropathy is one of the most common primary types of glomerulonephritis to progress to end-stage renal disease. Its variable and often long natural history makes it difficult to predict outcome. We investigated the association of the rate of renal function decline based on the slope of creatinine clearance over time with demographic, clinical, laboratory, and histological data from 298 patients with biopsy-proven IgA nephropathy with a mean follow-up of 70 months. Using univariate analysis, urinary protein excretion at baseline and Lee pathological grading, as well as mean arterial pressure (MAP) and urinary protein excretion during follow-up, were associated with the rate of deterioration in renal function. Of these, only MAP and urinary protein excretion during follow-up were identified as independent factors by multiple linear regression analysis. The combination of best accuracy of prediction and shortest observation time using these two parameters was reached between the second and third years of follow-up. A semiquantitative method of estimating the rate of progression by using these factors was developed. These results indicate that MAP and severity of proteinuria over time are the most important prognostic indicators of IgA nephropathy. The potential relevance of the algorithm in patient management is shown.

Grading of acute and chronic renal lesions in Henoch-Schönlein purpura

The renal outcome of 34 patients with Henoch-Schönlein purpura nephritis was assessed clinically and by grading acute and chronic renal lesions using a system we applied to primary IgA nephropathy. On a median follow-up period of 65 months, hypertension and the serum levels of creatinine and proteinuria at the time of renal biopsy were correlated with renal survival. Acute glomerular lesions including mesangial hypercellularity, endocapillary proliferation, necrosis, cellular crescents, and leukocytes infiltration were observed, respectively, in 41%, 12%, 50%, 29%, and 32% of the cases. Of these, only glomerular necrotizing lesion and cellular crescent were correlated with the renal survival. Chronic renal lesions based on a grading system applied to primary IgA nephropathy and assessing the extent of glomerular sclerosis (glomerular grading), of tubular loss and interstitial fibrosis (tubulointerstitial grading), and of hyaline arteriolosclerosis demonstrated correlation between these lesions, as well as with renal survival. On follow-up, these chronic renal lesions were predictors of subsequent clinical events associated with disease progression, such as impaired renal function, significant proteinuria, and development of hypertension. Despite some limitations related to the relatively small size, this series indicates that distinction of acute and chronic lesions of Henoch-Schonlein purpura nephritis is important for both the prognosis and management of patients.

The natural history of immunoglobulin a nephropathy among patients with hematuria and minimal proteinuria

PURPOSE

To determine the natural history of immunoglobulin (Ig) A nephropathy among patients who presented with hematuria and minimal proteinuria, and factors associated with the development of adverse clinical events, such as proteinuria.

SUBJECTS AND METHODS

In Hong Kong, all patients who present with isolated hematuria are referred for renal biopsy after urologic diseases are ruled out. We reviewed the clinical course of 72 consecutive patients with histologically confirmed IgA nephropathy who presented with hematuria and minimal proteinuria (0.4 g/day or less). All patients were normotensive and had normal renal function at presentation. Adverse events were defined as proteinuria greater than 1 g per day, hypertension, or impaired renal function (serum creatinine level 120 micromol/L or estimated creatinine clearance < 70 mL per minute).

RESULTS

The mean (+/- SD) age at presentation was 27 +/- 8 years; 56 (78%) were female. Nine patients (13%) had grade 2 histologic lesions. During a median follow-up of 7 years, 32 patients (44%) developed adverse events: 24 (33%) developed proteinuria of 1 g per day or more, 19 (26%) became hypertensive, and 5 (7%) developed impaired renal function. Another 30 patients (42%) had persistently abnormal urinalysis examinations. Only 10 patients (14%) had complete resolution of hematuria. The median time for progression from proteinuria (> l g/day) to renal impairment was 84 months (range 56 to 132). In a multivariate analysis, age at presentation (relative risk [RR] per 10 years of age = 2.0; 95% confidence interval [CI], 1.2 to 3.4) and histologic grade (grade 2 versus grade 1, RR = 4.5; 95% CI, 1.7 to 12) were independent predictors of developing an adverse event.

CONCLUSIONS

IgA nephropathy that presents with hematuria and minimal proteinuria is usually a progressive disease. Life-long follow-up with regular monitoring of blood pressure and proteinuria is recommended.

Characterization of early IgA nephropathy

Histological grading of 45 patients with clinical early immunoglobulin A (IgA) nephropathy was correlated with disease progression over a median follow-up of 123 months. Clinical early IgA nephropathy was defined as a serum creatinine level of 1.3 mg/dL or less, proteinuria of 0.4 g/d or less of protein, and the absence of hypertension at the time of renal biopsy. Disease progression was related to the occurrence of impaired renal function, increased proteinuria, and hypertension. We applied a previously described chronicity-based histological grading to the renal biopsy specimen and also assessed acute glomerular lesions. Disease progression was observed in 44.4% of these patients. Forty patients (89%) showed glomerular grade 1 (GG1) and 5 patients (11%) showed GG2, but this grading did not correlate with disease progression. However, when GG1 was subdivided into GG1a (mean sclerosis per glomerulus <10%) and GG1b (mean sclerosis per glomerulus 10% to <25%), GG1a correlated with nonprogressive disease. Tubulointerstitial grade also correlated with disease progression but was associated with a low sensitivity for predicting nonprogressive disease. Hyaline arteriolosclerosis and acute glomerular lesions did not correlate with disease progression. The chronicity-based histological grading is not only applicable to clinical early IgA nephropathy, but also more importantly, it characterizes GG1a in a subset of patients with a very low risk for disease progression, which can be regarded as genuine early IgA nephropathy.