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

Podocytopathy Associated with IgA Nephropathy in Pregnancy: A Challenging Association

IgA nephropathy is the most common form of primary glomerulonephritis. While associations of IgA and other glomerular diseases have been described, the association of IgA nephropathy with "primary" podocytopathy is rare and has not been reported in pregnancy, due in part to the infrequent use of kidney biopsy during pregnancy, and a frequent overlap with preeclampsia. We report the case of a 33-year-old woman with normal kidney function, referred in the 14th gestational week of her second pregnancy, due to nephrotic proteinuria and macroscopic hematuria. The baby's growth was normal. The patient reported episodes of macrohematuria one year previously. A kidney biopsy performed at 18 gestational weeks confirmed IgA nephropathy, associated with extensive podocyte damage. Treatment with steroids and tacrolimus led to remission of proteinuria and a healthy baby, adequate for gestational age, was delivered at 34 gestational weeks and 6 days (premature rupture of membranes). Six months after delivery, proteinuria was about 500 mg per day, with normal blood pressure and kidney function. This case highlights the importance of timely diagnosis in pregnancy and underlines that good maternal and fetal outcomes can be achieved with appropriate treatment, even in complex or severe cases.

Predictive value of sub classification of focal segmental glomerular sclerosis in Oxford classification of IgA nephropathy

BACKGROUND

The Oxford classification of IgA nephropathy (IgAN) was revised in 2016 which lacked sufficient evidence for prognostic value of subclassification of focal segmental glomerular sclerosis (S lesion), and the proper proportion of S lesion for subclassification remains undetermined.

AIM

This study aimed to explore the predictive value of the new subclassification of S score on renal outcomes of IgAN patients.

METHODS

348 patients with IgAN-associated S lesion were enrolled. According to the optimal cut-off of 25% established by receiver operating characteristic (ROC) curves, we divided S1 patients into two groups: S1a group (S lesion < 25%) and S1b group (S lesion ≥ 25%). IgAN patients with mild lesion (M0E0S0T0C0) were set as the control group. The clinical features at renal biopsy, pathological findings, and follow-up parameters (follow-up time ranged from 1 to 5 years) were collected. We used univariate and multivariate analyses to assess whether the subclassification of S score could refine risk prediction and clinical utility.

RESULTS

We demonstrated that S lesion ≥ 25% was associated with a more rapid GFR loss and a lower rate of complete remission of proteinuria even adjusted for multiple clinic pathological variables, compared to S1a group (All p values <.05). And the ratio of glomeruli with T lesion and crescents were higher in patients with S lesion ≥ 25%. Data showed that IgAN patients with S lesion ≥ 25% were at an increased risk of poor renal outcomes even with immunosuppression.

CONCLUSION

This study might recommend new subclassification of S scores (S0 (no S lesion), S1 (S lesion <25% of glomeruli), and S2 (S lesion ≥ 25% of glomeruli)) for the Oxford classification. This model may also help to evaluate pros and cons of immunosuppressive therapy in IgAN patients with different level of S lesion.KEY MESSAGESS lesion ≥ 25% is an independent risk factor for poor renal outcome in IgAN patients.This new subclassification of S scores may help to evaluate pros and cons of immunotherapy in IgAN patients with different level of S lesion.

A cross-sectional study in patients with IgA nephropathy of correlations between clinical data and pathological findings at the time of renal biopsy: a Japanese prospective cohort study

BACKGROUND

The correlations between clinical data and pathological findings at the time of renal biopsy were investigated in IgA nephropathy patients.

METHODS

771 patients diagnosed with IgA nephropathy by renal biopsy were enrolled. The correlations between clinical variables including eGFR, daily proteinuria, mean arterial pressure (MAP), serum uric acid (UA) values, and pathological parameters were examined. These patients were further divided into three groups: children (< 19 years old), young adults (19-60 years), and elderly patients (> 60 years).

RESULTS

Daily proteinuria was moderately correlated with all pathological parameters (Rs = 0.23-0.49). The mesangial score, the percentage of glomeruli that contained endocapillary hypercellularity, cellular/fibrocellular crescents or tuft necrosis, and segmental glomerulosclerosis (GS) affected daily proteinuria most on multiple linear regression analysis (MLRA). eGFR, MAP, and serum UA levels were mainly correlated with the degree of GS and interstitial lesions. In children, the degree of cellular/fibrocellular crescents or tuft necrosis was correlated with not only daily proteinuria, but also decreased eGFR (Rs = 0.51, - 0.24). Endocapillary hypercellularity was the only independent variable related to daily proteinuria on MLRA.

CONCLUSION

In all age cohorts of IgA nephropathy patients, daily proteinuria was correlated with all histological parameters, including both acute and chronic glomerular lesions, and the mesangial score. Independent variables for daily proteinuria were the meangial score, acute histological lesions, and segmental GS on MLRA, whereas the remaining independent variable in the pediatric group was endocapillary hypercellurality. The clinical pathological correlation at the time of biopsy varied depending on the age group.

A proposed Oxford classification-based clinicopathological nomogram for predicting short-term renal outcomes in IgA nephropathy after acute kidney injury

BACKGROUND

This study aimed to investigate the effect of acute kidney injury (AKI) on the progression of renal disease and to develop a clinico-pathological nomogram to predict the renal outcome of IgA nephropathy (IgAN) patients, based on Oxford classification score.

METHODS

This is a retrospective observational study. A total of 988 IgAN patients treated at our hospital between 2006 and 2011 were included and divided into AKI (n = 82) and non-AKI group (n = 906). The primary outcome measure was the composite renal endpoint. The secondary outcome measure was all-cause mortality. Clinical and pathologic features were assessed with multivariable Cox regression to predict the outcome in IgAN patients. A nomogram was developed to predict the renal outcome.

RESULTS

The median follow-up time was 48.6 months (range: 34.4 to 62.7). The incidence of AKI was 8.30%. The AKI group had more severe pathological characteristics and a significantly poor survival outcome than the non-AKI group. The multivariate Cox regression analysis showed that the AKI group had a 2.84 times higher risk of the composite renal endpoint as compared with the non-AKI group (P < 0.001). A clinico-pathological nomogram was developed using the seven predictors for the primary renal composite endpoint. The AUC for the nomogram model was 0.81 (sensitivity = 0.78, specificity = 0.85), and the C-index was 0.91 (95% CI = 0.85-0.97).

CONCLUSIONS

For IgAN patients, AKI is an independent risk factor for the progression of renal disease. Our nomogram model has good prediction power for the renal outcome of IgAN patients.

Aberrant Blood Vessel Formation Connecting the Glomerular Capillary Tuft and the Interstitium Is a Characteristic Feature of Focal Segmental Glomerulosclerosis-like IgA Nephropathy

Background:

Segmental glomerulosclerosis without significant mesangial or endocapillary proliferation is rarely seen in IgA nephropathy (IgAN), which simulates idiopathic focal segmental glomerulosclerosis (FSGS). We recently recognized aberrant blood vessels running through the adhesion sites of sclerosed tufts and Bowman’s capsule in IgAN cases with mild glomerular histologic change.

Methods:

To characterize aberrant blood vessels in relation to segmental sclerosis, we retrospectively reviewed the clinical and histologic features of 51 cases of FSGS-like IgAN and compared them with 51 age and gender-matched idiopathic FSGS cases.

Results:

In FSGS-like IgAN, aberrant blood vessel formation was observed in 15.7% of cases, 1.0% of the total glomeruli, and 7.3% of the segmentally sclerosed glomeruli, significantly more frequently than in the idiopathic FSGS cases (p = .009). Aberrant blood vessels occasionally accompanied mild cellular proliferation surrounding penetrating neovessels. Clinically, all FSGS-like IgAN cases had hematuria; however, nephrotic range proteinuria was significantly less frequent than idiopathic FSGS.

Conclusions:

Aberrant blood vessels in IgAN are related to glomerular capillary injury and may indicate abnormal repair processes in IgAN.

Soluble Urokinase Receptor Levels Are Correlated with Focal Segmental Glomerulosclerosis Lesions in IgA Nephropathy: A Cohort Study from China

Background

Soluble urokinase receptor (suPAR) may be involved in the pathological mechanisms of focal segmental glomerulosclerosis (FSGS) changes. However, it remains unclear whether suPAR is correlated with the FSGS-like lesions in IgA nephropathy (IgAN).

Methods

We measured the plasma suPAR levels in 138 patients with IgAN, and then their clinical and pathological relationships were analyzed.

Results

We found that the plasma suPAR levels were significantly correlated with age and renal function by both univariate and multivariate analysis in our IgAN patient cohort. Female had higher plasma suPAR levels and no significant correlation was observed between plasma suPAR levels and 24-h urine protein and highly sensitive C-reaction protein with multivariate analysis. In our cohort, sixty of these IgAN patients could be diagnosed with a type of FSGS lesions. The plasma suPAR levels were higher in the IgAN patients with FSGS lesions than in the IgAN patients without FSGS lesions by univariate (P < 0.0001) and multivariate (P < 0.001) analysis adjusting for other predictor variables, which might be helpful to differentiate the pathological changes with and without FSGS lesions. And the optimal cutoff value was 1806 pg/ml in this study. The plasma suPAR concentrations were also associated with the degree of tubular atrophy/interstitial fibrosis in both univariate and multivariate analysis. In multivariate analysis, the plasma suPAR levels were correlated with the percentage of crescents, not global sclerosis and arterial lesions.

Conclusions

Our study suggested that the plasma suPAR levels were associated with age, gender, renal function, the degree of tubular atrophy/interstitial fibrosis and the percentage of crescent formation. The plasma suPAR might be a potential predictor for the presence of FSGS pathological lesions in Chinese patients with IgAN.

Plasma Soluble Urokinase Receptor Level Is Correlated with Podocytes Damage in Patients with IgA Nephropathy

Background

Focal segmental glomerulosclerosis (FSGS) lesions are similar in characteristics to S lesions of the Oxford classification of IgA nephropathy (IgAN) and may predict poor prognosis. In the present study, we aimed to explore the association between plasma soluble urokinase receptor (suPAR) levels and S lesions and podocytes damage in IgAN patients.

Methods

We enrolled 569 IgAN patients with follow-up data and detected plasma suPAR levels at renal biopsy by enzyme-linked immunosorbent assay.

Results

Plasma suPAR levels in IgAN patients with or without S lesions did not differ significantly (P = 0.411). However, suPAR levels were positively correlated with proteinuria (r = 0.202, P < 0.001), and negatively correlated with estimated glomerular filtration rate (eGFR, r = –0.236, P < 0.001). In the partial correlation to adjust for eGFR, plasma suPAR levels remained positively correlated with proteinuria (r = 0.112, P = 0.023). In a Cox proportional hazards model, higher levels of plasma suPAR were not associated with poor renal outcome. Plasma suPAR levels of IgAN and primary FSGS patients with nephrotic syndrome were not significantly different (P = 0.306). Plasma suPAR levels in patients with extensive effacement of the epithelial cell foot processes of glomerular podocytes were significantly higher than those with segmental effacement on the basis of comparable eGFR (P = 0.036).

Conclusions

In IgAN patients, plasma suPAR levels were not associated with S lesions. However, they were positively associated with proteinuria and negatively associated with eGFR. In addition, plasma suPAR levels were positively associated with the effacement degree of the foot processes, which might partially contribute to the development of proteinuria in patients with IgAN.

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.

Development and validation of a prediction rule using the Oxford classification in IgA nephropathy

BACKGROUND AND OBJECTIVES

The risk assessment for developing ESRD remains limited in patients with IgA nephropathy (IgAN). The aim of this study was to develop and validate a prediction rule for estimating the individual risk of ESRD in patients with IgAN.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

A total of 698 patients with IgAN diagnosed by renal biopsy at Kyushu University Hospital (derivation cohort) between 1982 and 2010 were retrospectively followed. The Oxford classification was used to evaluate the pathologic lesions. The risk factors for developing ESRD were evaluated using a Cox proportional hazard model with a stepwise backward elimination method. The prediction rule was verified using data from 702 patients diagnosed at Japanese Red Cross Fukuoka Hospital (validation cohort) between 1979 and 2002.

RESULTS

In the derivation cohort, 73 patients developed ESRD during the median 4.7-year follow-up. The final prediction model included proteinuria (hazard ratio [HR], 1.30; 95% confidence interval [95% CI], 1.16 to 1.45, every 1 g/24 hours), estimated GFR (HR, 0.84; 95% CI, 0.74 to 0.96, every 10 ml/min per 1.73 m(2)), mesangial proliferation (HR, 1.85; 95% CI, 1.10 to 3.11), segmental sclerosis (HR, 3.21; 95% CI, 1.37 to 7.51), and interstitial fibrosis/tubular atrophy (T1: HR, 5.30; 95% CI, 2.63 to 10.7; T2: HR, 20.5; 95% CI, 9.05 to 46.5) as independent risk factors for developing ESRD. To create a prediction rule, the score for each variable was weighted by the regression coefficients calculated using the relevant Cox model. The incidence of ESRD increased linearly with increases in the total risk scores (P for trend <0.001). Furthermore, the prediction rule demonstrated good discrimination (c-statistic=0.89) and calibration (Hosmer-Lemeshow test, P=0.78) in the validation cohort.

CONCLUSIONS

This study developed and validated a new prediction rule using clinical measures and the Oxford classification for developing ESRD in patients with IgAN.

Renal biopsy findings of patients presenting with isolated hematuria: disease associations

BACKGROUND

Most nephrologists have believed that patients with isolated hematuria (IH) generally do not require treatment and have a good prognosis. The aim of this study was to analyze the pathological characteristics and emphasize the importance of renal biopsy for patients with IH.

METHODS

The pathological characteristics of 90 patients with IgA nephropathy confirmed by renal biopsy and presenting with IH were reviewed. We analyzed their pathological features according to the Oxford classification by using light and immunofluorescence.

RESULTS

Total samples included 68 females and 22 males. The age of onset with IH focuses on 20-30 years. At presentation, the focal and/or segmental glomerulosclerosis (FSGS) was the most frequent diagnosis (52.22%). The distribution of hematuria focused on 20-40 thousand. 46.67% of cases had global glomerulosclerosis which excluded the physical glomerular sclerosis, and the incidence of crescent formation was 24.44%. However, the proportion of glomerular sclerosis was mainly concentrated in less than 10%. Direct immunofluorescence showed simple IgA deposition was the most common (43.33%). 46.67% of patients had accompanying complement deposition, and 92.89% had complement 3 deposition. According to the Oxford classification, M(1)S(0)E(0)T(0) accounted for 53.33%. The incidence of M, S, E, and T was 100, 30, 14.44, and 22.22% respectively. 46.67% of patients included two or more pathological lesions.

CONCLUSIONS

FSGS played an important role in patients with IgA nephropathy who presented with IH. For those patients, renal biopsy was a valuable diagnostic tool and should be offered in clinical settings to provide them with maximal potential benefits.

Oxford-MEST classification in IgA nephropathy patients: A report from Iran

BACKGROUND

There is a limited knowledge about the morphological features of IgA nephropathy (IgAN)in the middle east region.

OBJECTIVES

The objective of this study was to evaluate the spectrum of histopathological findings in IgAN patients at our laboratory.

PATIENTS AND METHODS

At this work, an observational study reported which was conducted on IgAN patients using the Oxford-MEST classification system.

RESULTS

In this survey, of 102 patients 71.6 % were male. The mean age of the patients was 37.7 ± 13.6 years. Morphologic variables of MEST classification was as follows; M1: 90.2 %, E: 32 %, S: 67 % also,T in grads I and II were in 30% and 19% respectively, while 51% were in grade zero. A significant difference was observed in segmental glomerulosclerosis (P=0.003) and interstitial fibrosis/tubular atrophy frequency distribution (P= 0.045), between males and females . Furthermore, it was found that mesangial hypercellularity was more prevalent in yonger patients. Moreover, there was a significant correlation between serum creatinine and crescents (P<0.001). There was also significant correlation of serum creatinine with segmental glomerulosclerosis (P<0.001).

CONCLUSIONS

Higher prevalence of segmental glomerulosclerosis and interstitial fibrosis/ tubular atrophy, as the two of, four variables of Oxford-MEST classification of IgAN in male patients further attests that male gender is a risk factor in this disease.In this study the significant correlation between serum creatinine and crescent was in an agreement with previous studies and suggests for the probable accomodation of extracapillary proliferation as a new variable in MEST system.

A case of minimal change nephrotic syndrome with immunoglobulin A nephropathy transitioned to focal segmental glomerulosclerosis

A 50-year-old woman with a 1-month history of lower extremity edema and a 5 kg weight increase was admitted to our hospital with suspected nephrotic syndrome in October 1999. Urine protein level was 3.5 g per day, 10-15 erythrocytes in urine per high-power field, and serum albumin level 2.5 g/dl. Furthermore, an accumulation of pleural effusion was confirmed by chest X-ray. The results of a renal biopsy indicated slight mesangial proliferation in the glomeruli by light microscopy, and an immunofluorescence study confirmed the deposition of immunoglobulin (Ig) A and C3 in the mesangial area. Diffuse attenuation of foot processes and dense deposits in the mesangial area were observed by electron microscopy. Treatment with 40 mg/day of prednisolone was effective, and proteinuria was negative 1 month later. Because of this course, we diagnosed minimal change nephrotic syndrome complicated by mild-proliferative IgA nephropathy. In November 2000, there was a relapse of nephrotic syndrome, which was believed to be induced by an influenza vaccination, but response to increased steroid treatment was favorable, and proteinuria disappeared on day 13 of steroid increase. A second relapse in May 2001, showed steroid resistance with renal insufficiency, and an increase in the selectivity index to 0.195. Light microscopy revealed focal sclerotic lesions of the glomeruli, and an immunofluorescence study revealed attenuation of mesangial IgA and C3 deposition. These findings led to the diagnosis that minimal change nephrotic syndrome had transitioned to focal segmental glomerulosclerosis, whereby mesangial IgA deposition was reduced by immunosuppressive treatment. Subsequently, her renal function gradually worsened to the point of end-stage renal failure by 27 months after the second relapse of nephrotic syndrome.

Focal segmental glomerulosclerosis plays a major role in the progression of IgA nephropathy. II. Light microscopic and clinical studies

It is well known that lesions morphologically identical with focal segmental glomerulosclerosis (FSGS) may appear in IgA nephropathy (IgAN). Capsular adhesions without underlying abnormalities in the tuft, often the first sign of FSGS, are frequent in IgAN. In this retrospective study, a new cohort of 128 adult patients with IgAN was used to validate the new Oxford classification system of IgAN, and shown to have highly significant associations with clinical and outcome parameters. We then used these patients to determine the extent to which IgAN could be accounted for in terms of FSGS. Some form of lesion consistent with FSGS, notably hyalinosis and collapsing glomerulopathy, was found in 101 of these patients. No glomerular lesions were found in 16 patients, and 11 had mild lesions not definable as FSGS. Those with FSGS had significantly worse renal survival at 80 months than those without. Comparison of pure forms of FSGS (excluding collapsing glomerulopathy) with cases of FSGS having other glomerular lesions (mesangial hyperplasia, endocapillary hypercellularity, glomerular necroses, extracapillary proliferation) revealed that those with FSGS and other superimposed lesions did significantly worse than cases of pure FSGS at 80 months following diagnosis. Importantly, patients with pure FSGS had relatively poor survival even without other superimposed glomerular abnormalities. Thus, the majority of cases of IgAN can be interpreted as representing one or another variant of FSGS. Hence, interpreting IgAN in terms of FSGS emphasizes the role that podocyte lesions may play in the pathogenesis and progression of this disease.

Focal segmental glomerulosclerosis plays a major role in the progression of IgA nephropathy. I. Immunohistochemical studies

IgA nephropathy (IgAN) often shows lesions morphologically identical with those of focal segmental glomerulosclerosis (FSGS). In order to determine the possible role of FSGS in IgAN lesions, we measured glomerular capsular adhesions, often the first step toward FSGS, in biopsies from 127 patients with IgAN, 100 with lupus nephritis, and 26 with primary FSGS. Capsular adhesions with no lesions in the underlying tuft, consistent with podocyte abnormality or loss, were found regularly in FSGS and IgAN, but infrequently in lupus. Fifteen biopsies of patients with IgAN were studied immunohistochemically using markers for podocytes, Bowman's parietal epithelial cells, proliferating cells, and macrophages. Cytokeratins CK-8 and C2562 differentiated normal podocytes (negative) from parietal epithelial cells (variably positive). There was focal loss of the podocyte markers synaptopodin, glomerular epithelial protein 1 (GLEPP-1), nephrin, and vascular endothelial growth factor (VEGF), particularly at sites of capsular adhesions in otherwise histologically normal glomeruli. Cells displaying the parietal epithelial cell markers PAX2 (paired box gene 2) and the cytokeratins were also positive for the proliferating cell marker, proliferating cell nuclear antigen. These cells gathered at sites of adhesion, and in response to active lesions in the tuft, grew inward along the adhesion onto the tuft, forming a monolayer positive for parietal markers and the podocyte marker Wilms tumor protein-1 (WT-1). These cells deposited a layer of collagen over the sclerosing tuft. Thus, all biopsies of patients with IgAN had changes basically identical to those classically described in FSGS. Hence, our study strongly suggests that podocytopathy of a type similar to that in primary FSGS occurs frequently in IgAN.

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.