Pathological predictors of prognosis in immunoglobulin A nephropathy: a review

Associations between Biomarkers of Complement Activation, Galactose-Deficient IgA1 Antibody and the Updated Oxford Pathology Classification of IgA Nephropathy

Our prior study indicates a close relationship between alternative complement pathway activation, galactose-deficient IgA1 (Gd-IgA1) concentration and clinical severity of IgA nephropathy (IgAN). Nonetheless, the relationship between complement factors and the updated Oxford classification of IgAN remains unclear. This study enrolled eighty-four previously untreated, biopsy-diagnosed IgAN patients. The clinical and laboratory findings were collected at the time of biopsy. Plasma levels of complement factor C5a, factor Ba and Gd-IgA1 were measured and analyzed. It was found that the levels of proteinuria positively correlated with the updated Oxford classification of mesangial hypercellularity (M), endocapillary hypercellularity (E), tubular atrophy/interstitial fibrosis (T) and crescents (C). In addition, plasma Gd-IgA1 titer was significantly elevated in IgAN patients with tubular atrophy/interstitial fibrosis (T). In separate multivariable logistic regression models, both Gd-IgA1 and factor Ba independently predict higher T scores. The results indicate that both the levels of Gd-IgA1 antibody and biomarkers of the alternative complement pathway activation reflect the Oxford classification of IgAN. Whether these biomarkers can be used to guide therapeutic decisions requires further study.

The Association of the Oxford Classification Score with Longitudinal Estimated Glomerular Filtration Rate Decline in Patients with Immunoglobulin A Nephropathy: A Mixed-Method Study

Introduction

The Oxford Classification score, which predicts renal outcomes for immunoglobulin A nephropathy (IgAN), is widely used in clinical practice. Nevertheless, the relationship between these markers and longitudinal changes in renal function are poorly understood.

Methods

This was a population-based retrospective cohort study of 280 adults with biopsy-proven primary IgAN from 2011 to 2018. We used generalized additive mixed models to control for traditional kidney disease risk factors to analyze the associations between Oxford Classification MEST-C scores (mesangial hypercellularity, M; endocapillary hypercellularity, E; segmental glomerulosclerosis, S; tubular atrophy/interstitial fibrosis, T; crescents, C) and longitudinal changes in the estimated glomerular filtration rate (eGFR) after renal biopsy.

Results

The median eGFR was 78.2 mL/min/1.73 m² at baseline, and then it decreased on average by 1.3 mL/min/1.73 m² per year in the entire cohort. In adjusted models, compared with patients without relative lesions, the presence of T > 50% (T2) (−5.7; 95% confidence interval [CI], −9.5 to −2.0 mL/min/1.73m² per year) was associated with the fastest eGFR decline. S present (S1) (−2.9; 95% CI, −4.6 to −1.1 mL/min/1.73m² per year) and C > 25% glomeruli (C2) (−3.4; 95% CI, −6.4 to −0.5 mL/min/1.73m² per year) also demonstrated steeper eGFR declines. However, we found no association between M > 0.5 (M1), E present (E1), T 26%–50% (T1), and C present ≥ 1 glomerulus (C1), and progressive eGFR decline (p > 0.05).

Conclusion

The Oxford Classification scores, S1, T2, and C2, were independently associated with the longitudinal decreases in renal function in patients with IgAN. These findings suggested therapies targeted at improving early damage to these lesions might be essential to delay renal progression.

A multicenter, prospective, observational study to determine association of mesangial C1q deposition with renal outcomes in IgA nephropathy

It was reported that histopathologic lesions are risk factors for the progression of IgA Nephropathy (IgAN). The aim of this study was to investigate the relationships between mesangial deposition of C1q and renal outcomes in IgAN. 1071 patients with primary IgAN diagnosed by renal biopsy were enrolled in multiple study centers form January 2013 to January 2017. Patients were divided into two groups: C1q-positive and C1q-negative. Using a 1: 4 propensity score matching (PSM) method identifying age, gender, and treatment modality to minimize confounding factors, 580 matched (out of 926) C1q-negative patients were compared with 145 C1q-positive patients to evaluate severity of baseline clinicopathological features and renal outcome. Kaplan-Meier and Cox proportional hazards analyses were performed to determine whether mesangial C1q deposition is associated with renal outcomes in IgAN. During the follow-up period (41.89 ± 22.85 months), 54 (9.31%) patients in the C1q negative group and 23 (15.86%) patients in C1q positive group reached the endpoint (50% decline of eGFR and/or ESRD or death) respectively (p = 0.01) in the matched cohort. Significantly more patients in C1q negative group achieved complete or partial remission during the follow up period (P = 0.003) both before and after PSM. Three, 5 and 7-year renal survival rates in C1q-positive patients were significantly lower than C1q-negative patients in either unmatched cohort or matched cohort (all p < 0.05). Furthermore, multivariate Cox regression analysis showed that independent risk factors influencing renal survival included Scr, urinary protein, T1-T2 lesion and C1q deposition. Mesangial C1q deposition is a predictor of poor renal survival in IgA nephropathy.Trial registration TCTR, TCTR20140515001. Registered May 15, 2014, http://www.clinicaltrials.in.th/index.php?tp=regtrials&menu=trialsearch&smenu=fulltext&task=search&task2=view1&id=1074 .

Is it possible to predict parameters of the Oxford classification of primary IgA Nephropathy from clinical laboratory data? Focus on the role of segmental glomerulosclerosis subtypes

INTRODUCTION

IgA nephropathy (IgAN) is the most common primary glomerulonephritis in the world and has a broad range of histological and clinical manifestations, ranging from morphologically normal to globally sclerotic glomeruli with clinical manifestations varying from isolated hematuria to end stage renal disease. This study aims to assess sensitivity, specificity and accuracy of clinical data at the time of biopsy in predicting 2017 updated Oxford classification parameters and to investigate if subtypes of segmental sclerosis (FSGS) influence clinical presentation.

MATERIAL AND METHODS

Renal biopsies from 103 patients with IgAN were analyzed. Oxford classification was updated and FSGS lesions were subclassified. ROC curves, univariate and multivariate logistic regression were used.

RESULTS

In Oxford classification, the majority of patients had mesangial hypercellularity in less than a half of glomeruli (M0), did not have endocapillary hypercellularity (E0), had segmental glomerulosclerosis (S1), had interstitial fibrosis and tubular atrophy in more than a half of the sample (T2) and had no crescents (C0). Hypertension increases the chance of M1 in 2.54x (p = 0.02). For each unit of increased creatinine, 2.6x more chances of E1 (p = 0.001). S1 is predicted by proteinuria with 75% sensitivity and 90.9% specificity (p < 0.0001). For each unit of increase in GFR, there is a reduction of 6% in the chance of T2 in relation to T0 (p = 0.0001). If hypertension, there is 5x more chances of T2 than T0 (p = 0.01). For each unit of increase in creatinine, there are 2.8x more chances of crescents- C (p = 0.003). Creatinine also showed 75.8% sensitivity and 75% specificity for prediction of C (p = 0.002). Inversely, for each unit of GFR, the chance of C is reduced by 4% (p = 0.007). Other clinical data related with C are hypertension (p = 0.03) and proteinuria (p = 0.02). To determine the role of FSGS subtypes in clinical presentation, we divided patients in S0 and S1 groups. Proteinuria was the only clinical parameter with significative difference, respectively, 0.3 (0-2.1) and 1.6 (0.02-16.2) g/24 h (p < 0.0001). FSGS subtypes related to proteinuria were cellular (p = 0.03) and peri-hilar (p = 0.02). Subtypes classically related to podocytopathies showed no correlation with clinical data.

CONCLUSION

In the future, with noninvasive methods for diagnosis of IgAN, it will be essential to predict Oxford classification parameters using clinical laboratory data for establishment of prognosis and therapeutics. We showed that Oxford classification parameters correspond to some clinical laboratory data, making this approach possible. FSGS lesions not specifically related to podocytopathies may also influence clinical parameters that affect renal disease progression.

A grading system that predicts the risk of dialysis induction in IgA nephropathy patients based on the combination of the clinical and histological severity

Histological classification is essential in the clinical management of immunoglobulin A nephropathy (IgAN). However, there are limitations in predicting the prognosis of IgAN based on histological information alone, which suggests the need for better prognostic models. Therefore, we defined a prognostic model by combining the grade of clinical severity with the histological grading system by the following processes. We included 270 patients and explored the clinical variables associated with progression to end-stage renal disease (ESRD). Then, we created a predictive clinical grading system and defined the risk grades for dialysis induction by a combination of the clinical grade (CG) and the histological grade (HG). A logistic regression analysis revealed that the 24-h urinary protein excretion (UPE) and the estimated glomerular filtration rate (eGFR) were significant independent variables. We selected UPE of 0.5 g/day and eGFR of 60 ml/min/1.73 m2 as the threshold values for the classification of CG. The risk of progression to ESRD of patients with CG II and III was significantly higher than that of patients with CG I. The patients were then re-classified into nine compartments based on the combination of CG and HG. Furthermore, the nine compartments were grouped into four risk groups. The risk of ESRD in the moderate, high, and super-high-risk groups was significantly higher than that in the low-risk group. Herein, we are giving a detailed description of our grading system for IgA nephropathy that predicted the risk of dialysis based on the combination of CG and HG.

Evaluation of Clinical and Pathological Characteristics of Patients with IgA Nephropathy Based on Oxford Classification System: Should Crescents be Included?

Introduction. None of the classification systems in immunoglobulin A (IgA) nephropathy has been widely agreed or implemented by clinicians or pathologists. In order to meet this need, "Oxford Classification System", which is highly reproducible and predictive for clinical course, was developed in 2009. In the present study, we investigated clinical and pathological characteristics of patients with IgA nephropathy based on current classification and the predictivity of crescent presence on prognosis. Methods. The study comprised 40 patients with diagnosis of primary IgA nephropathy on renal biopsy. The biopsy findings and follow-up parameters of patients were retrospectively re-evaluated. Pathological findings were examined based on the Oxford classification system. The presence of crescent formation in the specimens was noted. Results. The presence of crescent formation was predictive of poor prognosis regarding the glomerular filtration rate (eGFR), the level of proteinuria, and mean arterial pressure (MAP). Conclusion: Considering the importance of crescent formation in prediction of the clinical course and need for immunosuppressive therapy, it is suggested that crescent presence can be included in this classification system.

The response of the Oxford classification to steroid in IgA nephropathy: a systematic review and meta-analysis

Background

The present review is aimed to evaluate the correlation between pathological features and the response to steroid in the patients with IgA nephropathy according to the Oxford classification, mesangial hypercellularity (M), endocapillary hypercellularity (E), segmental glomerulosclerosis (S), tubular atrophy and interstitial fibrosis (T).

Methods

We searched Chinese Biomedical Database, EMBASE, Cochrane Library, PubMed and MEDLINE with all spellings of “IgA nephropathy”, “Oxford Classification”, and “steroid”.

Results

5 studies with 637 patients were eligible for inclusion. The analysis showed that M1, S1, and T1/2 was strongly associated with the prediction to steroid resistance when compared with M0 [odds ratio (OR) 1.89, 95% confidence interval (CI) 1.01 - 3.56, P < 0.05], S0 (OR 2.24, 95% CI 0.99 - 5.08, P = 0.05) and T0 (OR 2.16, 95% CI 1.29 - 3.63, P = 0.004) respectively. There is no difference in steroid sensitivity between E0 and E1 (P = 0.55). The pooled OR of steroid resistance for E1 versus T1/2 is 0.50 (P = 0.04).

Conclusion

IgA nephropathy patients with serious pathological changes (M1, S1, and T1/2) were more resistant to steroid than slight ones (M0, S0, and T0), and E1 is better response to steroid therapy than T1/2.

Evaluation of crescent formation as a predictive marker in immunoglobulin A nephropathy: a systematic review and meta-analysis

The 2009 Oxford Classification of immunoglobulin A (IgA) nephropathy (IgAN) identifies four histological features as predictors of renal prognosis: mesangial hypercellularity (M), endocapillary hypercellularity (E), segmental glomerulosclerosis (S), and tubular atrophy/interstitial fibrosis (T). However, the clinical and prognostic significance of crescent formation still remains controversial. Therefore, we performed a meta-analysis to evaluate the association between crescents and kidney outcome in IgAN. A total of 20 studies published from January 2009 to July 2016 involving 5,285 patients were included after systematic searches of PubMed and EMBASE databases. Pooled results showed that crescent lesions were associated with kidney failure (HR, 1.93; 95% CI, 1.49-2.50; P < 0.001). IgAN patients with crescents had lower eGFR levels (SMD, -0.21; 95% CI, -0.40--0.03; P = 0.023); higher proteinuria levels (SMD, 0.87; 95% CI, 0.11-1.63; P = 0.024); a larger number of patients with M1 (RR, 1.22; 95% CI, 1.07-1.40; P = 0.003), E1 (RR, 4.83; 95% CI, 3.04-7.66;P < 0.001), S1 (RR, 1.76; 95% CI, 1.11-2.80; P = 0.016) and T1/2 (RR, 2.74; 95% CI, 2.10-3.57; P < 0.001) lesions; and received immunosuppressive therapy more frequently (RD, 0.17; 95% CI, 0.11-0.23; P < 0.001). Our results suggest that crescent formation represents an efficient prognostic factor associated with progression to kidney failure and thus could be considered into the new Oxford Classification.

A case of synovitis, acne, pustulosis, hyperostosis, and osteitis (SAPHO) syndrome complicated by IgA nephropathy with nephrotic syndrome

A 62-year-old man visited our hospital with a mild sore throat, high-grade fever, and clavicular pain. Seven years earlier, he had been diagnosed with synovitis, acne, pustulosis, hyperostosis, and osteitis (SAPHO) syndrome. His clavicles were tender and remarkably swollen. Also noted was marked pitting edema in the lower extremities and pustulosis on the palms and soles of the feet. Laboratory studies on admission showed an elevated white cell count (23,400/μl) and serum C-reactive protein level (24.4 mg/dl). Urinalysis revealed proteinuria (2+) and occult blood (3+) with numerous dysmorphic red blood cells and hyalin casts. The patient was diagnosed with recurrence of his SAPHO syndrome and started on oral glucocorticoid therapy. By day 9 after admission, he had gained 16 kg in body weight, and his proteinuria (6.4 g/day) and serum creatinine level (2.3 mg/dl) were elevated. Renal biopsy revealed mesangial proliferative glomerulonephritis with deposition of IgA and C3 in the mesangial area and along the capillary walls. The patient was diagnosed with IgA nephropathy accompanied by nephrotic syndrome. With oral prednisolone therapy, his fever, clavicular pain, and proteinuria were gradually relieved. The clinical course in this case suggests the onset of nephrotic syndrome with IgA nephropathy was associated with the recurrence of the patient's SAPHO. To our knowledge, this is the first reported case of SAPHO-associated IgA nephropathy.

Immunoglobulin a nephropathy: Pathological markers of renal survival in paediatric patients

IgA nephropathy (IgAN) is one of the leading causes of glomerulonephritis characterized by the findings of IgA and IgG immune deposits in the mesangium of kidney biopsies from patients with persistent microscopic haematuria. IgAN is frequently detected among adolescents and young adults. IgAN presents a highly variable course that includes a spectrum from a very mild disease to end-stage renal disease (ESRD). There are several clinical and histological factors that strongly determined the final outcome of patients with IgAN. Pathological variables associated with unfavorable outcomes are mesangial hypercellularity, segmental glomerulosclerosis, endocapillary hypercellularity and interstitial fibrosis/tubular atrophy, according to the Oxford classification. Moreover, some studies also suggest a role for complement activation in the pathogenesis of IgAN. In this regard, staining for C4d may be an independent risk factor for the development of ESRD in IgAN. Despite the growing number of studies assessing IgAN risk factors, this kind of investigation in paediatric patients is still very limited. The aim of this article is to revise pathological markers related to deterioration of renal function in paediatric patients with IgAN, particularly those that can independently affect renal survival.

Nocturnal and Circadian Rhythm of Blood Pressure Is Associated with Renal Structure Damage and Function in Patients with IgAN

BACKGROUND AND AIMS

Abnormal circadian rhythm of blood pressure (BP) is closely related to target organ damage in hypertension. However, the association between abnormal circadian rhythm of BP and renal injury is not clear. We investigated whether renal injury is associated with nocturnal BP and circadian rhythm of BP in Chinese IgAN patients.

METHODS

Clinic and 24 h ambulatory BP monitoring data were obtained from 330 Chinese IgAN patients with mean 24 h BP < 130/80 and mean daytime BP < 135/85 mmHg. Renal histopathological injury was determined according to the Oxford classification of IgAN.

RESULTS

Among the 330 IgAN subjects, 35.8% suffered from nocturnal hypertension, 61.5% had abnormal circadian BP, and 27% had nocturnal hypertension with a nondipping pattern. Compared with nocturnal normotensive patients, patients with nocturnal hypertension had significantly higher levels of blood cystatin C, blood uric acid, and lower estimated glomerular filtration rate (eGFR), and significantly a higher mean renal tissue injury score. The nondipping hypertensive group had significantly higher nocturnal diastolic and systolic BP, blood uric acid, and glomerulosclerosis rates, whereas eGFR was lower. In nondipping hypertensive patients, urinary sodium excretion and renal tissue injury scores were significantly higher than dipping patients. Nocturnal hypertension and abnormal circadian BP correlated with renal tissue injury, renal interstitial fibrosis, and aortic arch atherosclerosis.

CONCLUSION

Abnormal circadian rhythm of BP and nocturnal hypertension are common clinical manifestations in Chinese IgAN patients with normal mean 24 h BP. Abnormal circadian BP and nocturnal hypertension may accelerate IgAN progression by inducing renal dysfunction and histopathological damage.

CD147 renal expression as a biomarker for progressive IgAN

BACKGROUND/AIMS

Recent studies have demonstrated that tubulointerstitial injury can predict renal outcomes better than the other histological parameters in patients with IgA nephropathy (IgAN). CD147 is a key regulator of renal tubulointerstitial fibrosis in cellular and animal models. However, it is not clear whether the expression of CD147 correlates with tubulointerstitial injury in IgAN patients.

METHODS

We analyzed the degree of CD147 expression and localization in renal biopsy tissues from IgAN patients and correlated their immunostaining scores with clinical and histological parameters.

RESULTS

Elevated CD147 expression was found in the basolateral membrane of renal tubules in IgAN patients; however, in normal kidney samples, positive staining for CD147 was not found in the tubular epithelial cells (P = 0.000). CD147 protein expression in the renal tubules showed a negative correlation with estimated glomerular filtration rate (eGFR; r = -0.600, P = 0.000) and a positive correlation with serum creatinine (Scr; r = 0.322, P = 0.002) and tubulointerstitial lesions (r = 0.525, P = 0.000). Moreover, a high level of CD147 correlated with the activation of Slug expression and E-cadherin repression in patients with IgAN. Kaplan-Meier survival curves showed that elevated CD147 expression was associated with decreased renal survival. Multivariate analyses further demonstrated that a high CD147 immunostaining score was an independent predictor of renal outcome in patients with IgAN (HR = 8.731, P = 0.041).

CONCLUSION

CD147 expression is associated with tubulointerstitial injury and predicts renal prognosis in IgA nephropathy. CD147 may be an early marker for tubulointerstitial injury IgA nephropathy.

ELISA analysis of urinary nephrin and podocalyxin standardized by aquaporin-2 in adult patients with nephrotic syndrome

OBJECTIVE

To investigate urinary nephrin and podocalyxin standardized by aquaporin (AQP)-2 using the enzyme-linked immunosorbent assay (ELISA) method in adult nephrotic syndrome (NS) patients.

METHODS

In 107 adult NS patients (27 proliferative nephritis, 77 non-proliferative, and 3 amyloidosis) undergoing renal biopsy, urinary nephrin, podocalyxin and AQP2 were measured by ELISA. Urinary nephrin and podocalyxin were standardized by AQP2 (neph/AQP and PCX/AQP) and values were compared with 11 healthy controls.

RESULTS

Urinary neph/AQP correlated positively to PCX/AQP (r = 0.51, p < 0.001). Urinary neph/AQP and PCX/AQP were lower in controls than NS patients. Both proliferative and non-proliferative NS patients excreted high urinary neph/AQP and PCX/AQP without a significant difference between them (p > 0.05). Patients with focal segmental glomerular sclerosis (FSGS) excreted higher urinary neph/AQP (p = 0.09) and PCX/AQP (p < 0.05) compared to the other patients. Urinary neph/AQP and PCX/AQP were increased in the immunoglobulin M nephropathy patients. Amyloidosis patients excreted lower neph/AQP and PCX/AQP. The sensitivity was 0.87 and specificity 0.37 when the neph/AQP borderline value of 0.16 was adopted [area under the curve (AUC) = 0.61]. The sensitivity was 0.74 and specificity 0.61 when the PCX/AQP borderline value was 3.06 (AUC = 0.69).

CONCLUSIONS

Urinary neph/AQP and PCX/AQP are increased in NS patients, with FSGS patients showing the highest levels. To distinguish FSGS from other NS forms, the measurement of urinary PCX/AQP may be a practical method, and superior to neph/AQP.

Increased number of Th22 cells and correlation with Th17 cells in peripheral blood of patients with IgA nephropathy

T-helper (Th) 22 and Th17 cells are involved in the pathogenesis of autoimmune diseases. However, the role of Th22 and correlation with Th17 cells in the pathophysiology of IgA nephropathy (IgAN) remain unknown. In our study, Th22 and Th17 cells in peripheral blood of IgAN patients, non-IgA mesangial proliferative glomerulonephritis (non-IgA MsPGN) patients, and healthy controls were measured by flow cytometry. The concentration of plasma interleukin-22 (IL-22) was examined by enzyme linked immunosorbent assay (ELISA). The results showed that Th22 cells, Th17 cells, and plasma IL-22 were significantly elevated in IgAN patients compared with non-IgA MsPGN patients and healthy controls. Th22 cells showed a positive correlation with the levels of plasma IL-22 in IgAN patients. Moreover, a significantly positive correlation between Th22 cells and Th17 in IgAN patients was observed. Furthermore, IgAN patients with proteinuria showed a higher percentage of Th22 cells than IgAN patients without proteinuria. Our data demonstrated that IgAN had increased frequencies of peripheral Th22, Th17 cells and plasma IL-22, indicating that Th22 along with Th17 cells are involved in the immune responses of IgAN.

N-acetylgalactosamine exposure of serum IgA1 was associated with glomerulosclerosis and tubular atrophy/interstitial fibrosis of IgA nephropathy patients

AIM

Immunoglobulin A nephropathy (IgAN) is the most common glomerulonephritis with various histological and clinical phenotypes. N-acetylgalactosamine (GalNAc) exposure plays a pivotal role in the pathogenesis of IgAN. The aim of the current study is to investigate whether GalNAc exposure of serum IgA1 was associated with clinical and pathological manifestation of IgAN.

METHODS

Sera from 199 patients with biopsy proved IgAN were collected. Clinical and pathological manifestations were collected. Biotinylated Helix aspersa were used in ELISA to examine GalNAc exposure on IgA1 molecules. Patients were divided into two groups according to the GalNAc exposure rate less or more than 0.4.

RESULTS

Age, gender, and serum creatinine were comparable between the two groups. Univariate analysis showed that significantly higher urinary protein excretion rate but less severe glomerular sclerosis and tubularinterstitial fibrosis were observed in the lower GalNAc exposure group. Multivariate regression analysis demonstrated that adjusted by age and gender, the GalNAc exposure rate more than 0.4 was a risk factor of glomerular sclerosis and tubularinterstitial fibrosis, OR*(95% CI) were 2.76 (1.19-6.37) and 2.49 (1.18-5.25), respectively.

CONCLUSION

Immunoglobulin A nephropathy patients with lower proteinuria had higher GalNAc exposure rates. The GalNAc exposure rate more than 0.4 was a risk factor of severe chronic renal tissue change.

Evaluation of the Oxford Classification of IgA nephropathy: a systematic review and meta-analysis

BACKGROUND

The Oxford Classification of the pathology of immunoglobulin A (IgA) nephropathy, developed in 2009, is highly predictive of renal prognosis. It has been validated in different populations, but the results remain inconsistent.

STUDY DESIGN

Systematic review and meta-analysis.

SETTING & POPULATION

Patients with biopsy-proven primary IgA nephropathy.

SELECTION CRITERIA FOR STUDIES

Studies assessing the Oxford Classification of IgA nephropathy published between January 2009 and December 2012 were included following systematic searching of the MEDLINE and EMBASE databases.

PREDICTOR

4 pathologic lesions of the Oxford Classification: mesangial hypercellularity (M), endocapillary hypercellularity (E), segmental glomerulosclerosis (S), and tubular atrophy/interstitial fibrosis (T).

OUTCOME

Kidney failure defined as doubled serum creatinine level, 50% decline in estimated glomerular filtration rate, or end-stage kidney disease.

RESULTS

16 retrospective cohort studies with 3,893 patients and 570 kidney failure events were included. In a multivariate model, HRs for kidney failure were 0.6 (95% CI, 0.5-0.8; P < 0.001), 1.8 (95% CI, 1.4-2.4; P < 0.001), and 3.2 (95% CI, 1.8-5.6; P < 0.001) for scores of M0 (mesangial hypercellularity score ≤0.5), S1 (presence of segmental glomerulosclerosis), and T1/2 (>25% tubular atrophy/interstitial fibrosis), respectively, without evidence of heterogeneity. Pooled results showed that E lesions were not associated with kidney failure (HR, 1.4; 95% CI, 0.9-2.0; P = 0.1), with evidence of heterogeneity (I(2) = 54.1%; P = 0.01). Crescent (C) lesions were associated with kidney failure (HR, 2.3; 95% CI, 1.6-3.4; P < 0.001), with no evidence of heterogeneity (I(2) = 14.7%; P = 0.3).

LIMITATIONS

All studies were retrospective. This was not an individual-patient-data meta-analysis.

CONCLUSIONS

This study suggests that M, S, T, and C lesions, but not E lesions, are associated strongly with progression to kidney failure and thus should be included in the Oxford Classification system.

Decreased circulating C3 levels and mesangial C3 deposition predict renal outcome in patients with IgA nephropathy

BACKGROUND AND AIMS

Mesangial C3 deposition is frequently observed in patients with IgA nephropathy (IgAN). However, the role of complement in the pathogenesis or progression of IgAN is uncertain. In this observational cohort study, we aimed to identify the clinical implications of circulating C3 levels and mesangial C3 deposition and to investigate their utility as predictors of renal outcomes in patients with IgAN.

METHODS

A total of 343 patients with biopsy-proven IgAN were enrolled between January 2000 and December 2008. Decreased serum C3 level (hypoC3) was defined as C3 <90 mg/dl. The study endpoint was end-stage renal disease (ESRD) and a doubling of the baseline serum creatinine (D-SCr).

RESULTS

Of the patients, there were 66 patients (19.2%) with hypoC3. During a mean follow-up of 53.7 months, ESRD occurred in 5 patients (7.6%) with hypoC3 compared with 9 patients (3.2%) with normal C3 levels (P = 0.11). However, 12 patients (18.2%) with hypoC3 reached D-SCr compared with 17 patients (6.1%) with normal C3 levels [Hazard ratio (HR), 3.59; 95% confidence interval (CI), 1.33-10.36; P = 0.018]. In a multivariable model in which serum C3 levels were treated as a continuous variable, hypoC3 significantly predicted renal outcome of D-SCr (per 1 mg/dl increase of C3; HR, 0.95; 95% CI, 0.92-0.99; P = 0.011). The risk of reaching renal outcome was significantly higher in patients with mesangial C3 deposition 2+ to 3+ than in patients without deposition (HR 9.37; 95% CI, 1.10-80.26; P = 0.04).

CONCLUSIONS

This study showed that hypoC3 and mesangial C3 deposition were independent risk factors for progression, suggesting that complement activation may play a pathogenic role in patients with IgAN.

Risk stratification of patients with IgA nephropathy

In this review, we summarize recent advances in the risk stratification of patients with immunoglobulin A (IgA) nephropathy. Several clinical variables have consistent and independent associations with worse kidney prognosis, including blood pressure, proteinuria, and baseline kidney function. Although one-time cross-sectional assessments of blood pressure and proteinuria are important, a more thorough understanding of risk can be achieved when these variables are considered over a follow-up period. IgA nephropathy is unique compared with other glomerular diseases in that a much lower threshold of proteinuria (protein excretion, 1 g/d) is associated with glomerular filtration rate (GFR) loss. Controlling proteinuria and blood pressure over time is important to reduce the risk of future loss of kidney function. The recently described Oxford classification has helped standardize the pathologic characterization of IgA nephropathy using a scoring system that is readily reproducible and associated with increased risk of GFR loss independent of clinical variables. We suggest an approach to risk stratification in IgA nephropathy when considering potential treatment with immunosuppression. Despite our current understanding of risk stratification in IgA nephropathy, the ability to accurately predict individual patient-level risk currently is limited, and further research into additional biomarkers or risk prediction tools is needed to improve the care of patients with IgA nephropathy.

Pathogenesis of IgA nephropathy

Since its first description in 1968, IgA nephropathy has remained the most common form of idiopathic glomerulonephritis leading to chronic kidney disease in developed countries. The exact pathogenesis of IgA nephropathy is still not well defined. Current data implicate an important genetic factor, especially in promoting the overproduction of an aberrant form of IgA1. The immunochemical aberrancy of IgA nephropathy is characterized by the undergalactosylation of O-glycans in the hinge region of IgA1. However, such aberrant glycosylation alone does not cause renal injury. The next stage of disease development requires the formation of glycan-specific IgG and IgA antibodies that recognize the undergalactosylated IgA1 molecule. These antibodies often have reactivity against antigens from extrinsic microorganisms and might arise from recurrent mucosal infection. B cells that respond to mucosal infections, particularly tonsillitis, might produce the nephritogenic IgA1 molecule. With increased immune-complex formation and decreased clearance owing to reduced uptake by the liver, IgA1 binds to the glomerular mesangium via an as yet unidentified receptor. Glomerular IgA1 deposits trigger the local production of cytokines and growth factors, leading to the activation of mesangial cells and the complement system. Emerging data suggest that mesangial-derived mediators following glomerular deposition of IgA1 lead to podocyte and tubulointerstitial injury via mesangio-podocytic-tubular crosstalk. This Review summarizes the latest findings in the pathogenesis of IgA nephropathy.

Overweight and obesity accelerate the progression of IgA nephropathy: prognostic utility of a combination of BMI and histopathological parameters

BACKGROUND

Although more than 40 years have passed since IgA nephropathy (IgAN) was first reported, predicting the renal outcome of individual IgAN patients remains difficult. Emerging epidemiologic evidence indicates that overweight and obesity are risk factors for end-stage renal disease. We aimed to elucidate the outcome of overweight IgAN patients and improve our ability to predict the progression of IgAN based on a combination of body mass index (BMI) and histopathological parameters, including maximal glomerular area (Max GA).

METHODS

Forty-three adult IgAN patients whose estimated glomerular filtration rate was ≥50 ml/min/1.73 m(2) were enrolled in this study. Renal biopsy specimens were evaluated according to the Oxford classification of IgAN. A Kaplan-Meier analysis and the multivariate Cox proportional hazards method were used to evaluate 10-year kidney survival and the impact of covariates. The ability of factors to predict the progression of IgAN was evaluated by their diagnostic odds ratio (DOR).

RESULTS

A BMI ≥25 kg/m(2) was found to be an independent predictor of a ≥1.5-fold increase in serum creatinine value (DOR 7.4). The combination of BMI ≥25 kg/m(2), Max GA ≥42,900 μm(2), and presence of mesangial hypercellularity (Oxford M1) optimally raised predictive power for disease progression of IgAN (DOR 26.0).

CONCLUSION

A combination of BMI ≥25 kg/m(2), the Oxford classification M1, and a Max GA ≥42,900 μm(2) can serve as a predictor of long-term renal outcome of IgAN.

Long-term renal survival and related risk factors in patients with IgA nephropathy: results from a cohort of 1155 cases in a Chinese adult population

BACKGROUND

We sought to identify the long-term renal survival rate and related risk factors of progression to renal failure in Chinese adult patients with IgA nephropathy (IgAN) and to quantify the effects of proteinuria during the follow-up on outcome in patients with IgAN.

METHODS

Patients with biopsy-proven primary IgAN in the Nanjing Glomerulonephritis Registry were studied. Renal survival and the relationships between clinical parameters and renal outcomes were assessed.

RESULTS

One thousand one hundred and fifty-five patients were enrolled in this study. The 10-, 15- and 20-year cumulative renal survival rates, calculated by Kaplan-Meier method, were 83, 74 and 64%, respectively. At the time of biopsy, proteinuria>1.0 g/day [hazard ratio (HR) 3.2, P<0.001], estimated glomerular filtration rate (eGFR)<60 mL/min/1.73 m2 (HR 2.6, P<0.001), hypertension (HR 1.9, P<0.001), hypoproteinemia (HR 2.0, P<0.001) and hyperuricemia (HR 2.1, P<0.001) were the independent risk factors. Multivariate Cox analysis showed the time-average proteinuria (TA-P) during follow-up was the most important risk factor of renal failure. Patients with TA-P>1.0 g/day were associated with a 9.4-fold risk than patients with TA-P<1.0 g/day (P<0.001) and 46.5-fold risk than those with TA-P<0.5 g/day (P<0.001). Moreover, patients who achieved TA-P<0.5 g/day benefit much more than those with TA-P between 0.5 and 1.0 g/day (HR 13.1, P<0.001).

CONCLUSIONS

Thirty-six percent of Chinese adult patients with IgAN progress to end stage renal disease within 20 years. Five clinical features-higher proteinuria, hypertension, impaired renal function, hypoproteinemia and hyperuricemia-are independent predictors of an unfavorable renal outcome. The basic goal of anti-proteinuric therapy for Chinese patients is to lower proteinuria<1.0 g/day and the optimal goal is to lower proteinuria to <0.5 g/day.

Pathologic predictors of renal outcome and therapeutic efficacy in IgA nephropathy: validation of the oxford classification

BACKGROUND AND OBJECTIVES

The Oxford classification of IgA nephropathy (IgAN) may aid in predicting prognosis and providing therapeutic strategy but must be validated in different ancestry.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

A total of 410 patients with IgAN, enrolled from one of the largest renal centers in China, were evaluated for the predictive value of the Oxford classification to prognosis defined as end stage renal disease. A total of 294 of these patients were prospectively treated with renin-angiotensin system blockade and immunosuppressants sequentially and were evaluated separately to assess the predictive value to therapeutic efficacy (defined as time-averaged proteinuria <1 g/d). Three pathologists reviewed specimens independently according to the Oxford classification and were blinded to clinical data.

RESULTS

Segmental glomerulosclerosis and tubular atrophy and interstitial fibrosis were independent predictive factors of end stage renal disease. Patients who had >25% of glomeruli with endocapillary hypercellularity showed higher proteinuria, lower estimated GFR, and higher mean BP than patients with less endocapillary hypercellularity. Immunosuppressive therapy showed a protective effect to prognosis of endocapillary hypercellularity in patients with endoncapillary hypercellularity could benefit from immunosuppressive therapy. Mesangial hypercellularity and tubular atrophy and interstitial fibrosis were independent factors of inefficiency of renin-angiotensin system blockade alone. Crescents were not significant in predicting prognosis or in therapeutic efficacy.

CONCLUSIONS

The Oxford classification may aid in predicting prognosis and providing a therapeutic strategy in Chinese patients with IgAN.

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.

The Oxford classification as a predictor of prognosis in patients with IgA nephropathy

BACKGROUND

In 2009, the Oxford classification was developed as a pathological classification system for immunoglobulin A nephropathy (IgAN) to predict the risk of disease progression. The aim of this retrospective study was to evaluate the clinical and pathologic relevance of the Oxford classification in Korean patients with a pathologic diagnosis of IgAN.

PATIENTS AND METHODS

We reviewed the renal pathology archives from January 2000 to December 2006 at Seoul St Mary's Hospital in Korea and identified 273 patients, who were diagnosed as having IgAN. We enrolled 197 patients who were available for further clinicopathologic analysis. All cases of IgAN were categorized according to the WHO classification, the semiquantitative classification and the Oxford classification. These pathologic classifications were compared. The clinical and laboratory findings at the time of biopsy were compared with those at the end of the follow-up according to the Oxford classification.

RESULTS

When three pathologic classifications were compared, M1, S1, E1, T1 or T2 were associated with a higher score in the activity index. S1, T1 or T2 were associated with a higher score in the chronicity index and a higher grade in the WHO classification. The clinical and laboratory findings were compared according to the Oxford classification. At the time of biopsy, the proteinuria in patients with M1 was more than that of M0 (P = 0.035). At the end of follow-up, the number of antihypertensive drugs taken among patients with M1 was greater than that of patients with M0 (P = 0.001). At the time of biopsy, the proteinuria of patients with S1 was greater than that of S0 patients (P = 0.009). At the end of follow-up, the number of patients who received immunosuppressants was increased as the grade of T increased (P = 0.000). At the end point of the follow-up, the estimated glomerular filtration rate (eGFR) decreased as the grade of T increased (P = 0.008). The time-average proteinuria after adjusting the initial proteinuria increased significantly with increasing degree of T (P = 0.000). Levels of tubular atrophy/interstitial fibrosis were predictive for survival from end-stage renal disease or of having a 50% reduction of eGFR.

CONCLUSION

The pathologic variables of the Oxford classification correlated significantly with other classifications (the WHO classification and the semiquantitative classification). The Oxford classification is a simple method for predicting renal outcome and differentiating between active and chronic lesions. We suggest that the Oxford classification offers an advantage for determining treatment policy for patients with IgAN.

Maximal glomerular diameter as a 10-year prognostic indicator for IgA nephropathy

BACKGROUND

Although there have been many reports on clinicopathological studies of immunoglobulin A nephropathy (IgAN), reliable outcome predictors are still lacking. We therefore assessed maximal glomerular diameter (Max GD), an indicator of glomerular size, as a predictor of the long-term evolution of renal histopathology.

METHODS

Forty-three adult patients, diagnosed with IgAN, who had estimated glomerular filtration rate (eGFR) ≥50 mL/min/1.73 m(2), were enrolled in this study. Prognostic variables for renal survival were examined by using the multivariate Cox proportional hazards method. The optimal cut-off value of Max GD was 242.3 μm (AUC = 0.78, sensitivity = 62.5%, specificity = 81.5%) by using receiver operating characteristics analysis. In order to assess the characteristics of glomerular hypertrophy, we divided the cases into two groups according to the Max GD value (Group A, ≥242 μm; Group B, <242 μm). Renal survival was also assessed by Kaplan-Meier curves with the log-rank test.

RESULTS

The Max GD was significantly correlated with age, body mass index and serum triglyceride levels at the time of renal biopsy. During the 10-year follow-up period, the Max GD was significantly correlated with eGFR decline per year, and proteinuria, but not with hematuria. A multiple regression analysis by the Cox method adjusted for age, sex and eGFR showed that the Max GD values were significantly associated with a 1.5-fold increase in serum creatinine (Cr) values (hazard ratio = 1.04, P = 0.03). Renal function in 66.7% of the patients whose Max GD was ≥242 μm had at least a 1.5-fold increase in their serum Cr value at the 10-year follow-up examination (log-rank, P = 0.003).

CONCLUSIONS

The results of this study suggest that Max GD is a simple quantitative prognostic indicator of the disease progression in IgAN patients.

Clinical and histopathological spectrum of IgA nephropathy in Kuwait

BACKGROUND

Little is known about the nature and the course of IgA nephropathy (IgAN) in Arab countries. The aim of this work was to study the spectrum of clinical presentation and histopathological findings at our institution.

DESIGN AND SETTING

Retrospective review, all renal biopsies at the Mubarak Al Kabeer Hospital between January 2000 and December 2004.

METHODS

Cases of IgA nephropathy were selected, and their medical records and biopsy findings were reviewed.

RESULTS

Eighty patients (9.2% of all native kidney biopsies) were diagnosed to have IgAN nephropathy. Sixty-nine biopsies were included in the study;11 were excluded. Forty-three (62.3%) patients were male and 26 (37.7) patients were female. Fifty (72.5%) patients were below the age of 40 years. Mean (SD) duration of follow-up was 3.6 (1.3) years. The first presentation included nephritic-range proteinuria (49.3%) and renal impairment (50.7%). During the follow-up period, 56 (81.2%) patients were stable or improved. Hass classification of biopsies showed 36.2% had class I, 27.5% had class II, 13.0% had class III, 5.8% had class IV, and 17.4% had class V IgAN. Females had milder forms of the disease than males. Macroscopic hematuria and renal impairment at presentation were seen more in patients with class IV and V IgAN. The presenting serum creatinine and uric acid values were higher in those with Hass classes III to V. Deterioration of renal function during the follow-up period was more significant in the presence of hypertension, renal impairment, or macroscopic hematuria at the time of biopsy .

CONCLUSION

The prevalence of IgAN in Kuwait is about 9.2%. Renal impairment or macroscopic hematuria at presentation was seen in patients with more aggressive renal lesions and contributed to poor outcome.

Association between ACE polymorphism and risk of IgA nephropathy: a meta-analysis

BACKGROUND

and objective: The effect of angiotensin-converting enzyme (ACE) gene insertion/deletion (I/D) polymorphism on risk or progression of immunoglobulin A nephropathy (IgAN) is still debated.Therefore, a meta-analysis was performed to evaluate the association of ACE gene polymorphism with IgAN in different ethnic groups.

METHOD

A predefined search strategy was performed to collect data from electronic databases.

RESULTS

Twenty articles were identified for the analysis of the relationship between ACE polymorphism and IgAN risk, including 11 in Asians and nine in Caucasians. There was a markedly positive association between the D allele or DD genotype and IgAN risk in Asians (OR = 1.27, p = 0.006; OR = 1.83, p < 0.0001). However, a link between D allele or DD genotype and IgAN risk was not found in Caucasians (OR = 1.04, p = 0.46; OR = 1.13, p = 0.12). Ten investigations were included for analysis of the association of ACE polymorphism with IgAN progression, including six in Asians and four in Caucasians. These data did not support a link between the ACE D allele or DD genotype and IgAN progression in Asians and Caucasians (Asians: D: OR = 1.03, p = 0.80; DD: OR = 1.43, p = 0.16; Caucasians: D: OR = 1.29, p = 0.22; DD: OR = 1.31, p = 0.17).

CONCLUSIONS

The D allele or DD genotype is associated with IgAN risk in Asian, but not in Caucasian populations; there was no significant association between the D allele or DD gene and IgAN progression for Asians and Caucasians.

Additive effect of PPAR-γ agonist and ARB in treatment of experimental IgA nephropathy

Our recent in vitro study demonstrated peroxisome proliferator-activated receptor-γ (PPAR-γ) agonist potentiated the anti-inflammatory effect of angiotensin receptor blocker (ARB) in tubular epithelial cell under milieu mimicking IgA nephropathy (IgAN). Here we studied the therapeutic effect of combining a PPAR-γ agonist, rosiglitazone (Ros), with an ARB, losartan (Los), in experimental IgAN induced in Lewis rats by oral and intravenous immunization with bovine gamma-globulin (BGG). The rats were randomly divided into six groups: control, IgAN, IgAN with unilateral nephrectomy (IgAN/1K), and IgAN/1K receiving Ros, Los, or Ros + Los. Medication was given 1 week after nephrectomy until killing. Rats developing IgAN had hematuria, mesangial hypercellularity with IgA deposition, glomerular damage, and tubulointerstitial infiltration of CD25+ leukocytes accompanied by increased renal expression of TGF-β, AngII receptor subtype-1 (ATR1) and ICAM-1. The renal histopathology, albuminuria, and renal expression of TGF-β, ATR1 and ICAM-1 worsened with unilateral nephrectomy. Ros or Los reduced the renal expression of PCNA, TGF-β, ATR1, and ICAM-1 in IgAN rats with nephrectomy. Despite no difference between rats treated with monotherapy, combined therapy offered additive effect with decreased renal expression of TGF-β, ATR1 and ICAM-1 and attenuation of renal injury. Our animal study suggests combined PPAR-γ agonist and ARB holds promise for future therapy for IgAN.