Clinical usefulness of the Oxford classification in determining immunosuppressive treatment in IgA nephropathy

Systemic and targeted steroids for the treatment of IgA nephropathy

Immunoglobulin A nephropathy (IgAN) is a common glomerulonephritis partially correlated with mucosal immune system dysfunction. Progressive renal failure occurs in many patients, with about 30-50% of the patients with IgAN developing end-stage kidney disease (ESKD). Many treatments have been used for decades, despite uncertainty about their effectiveness and the ideal dose. Randomised controlled trials reported that systemic glucocorticoids can be an effective treatment for patients with persistent and significant proteinuria despite renin-angiotensin system inhibitors use possibly causing systemic side effects. The primary focus of IgAN management should be based on optimised supportive care, including renin-angiotensin system (RAS) blockade and now SGLT2 inhibitors. The novel targeted-release formulation (TRF) of budesonide has been tested to reduce the adverse events of systemic steroids by delivering the drug to the distal ileum. The local efficacy of TRF-budesonide may represent a novel and promising approach to treating IgAN. Two clinical trials showed that TRF-budesonide could significantly reduce proteinuria and haematuria and possibly preserve renal function while significantly reducing the side effects. However, the limited number of treated patients and the relatively short follow-up suggest caution before considering budesonide superior to the current six-months steroid pulses scheme. Long-term data on the efficacy and safety of TRF budesonide are awaited, together with the design of trials with a head-to-head comparison with systemic steroids before considering TRF-budesonide as the standard of care treatment for IgAN nephropathy.

Clinicopathologic Manifestations of Immunoglobulin A Nephropathy in a Northern Indian Cohort: A Mute Assassin with Delayed Diagnosis

Introduction

Immunoglobulin A nephropathy (IgAN) is the most common glomerulonephritis worldwide, but there is a marked geographic difference in its prevalence and prognosis. IgAN is known to have an aggressive course in Asians. However, its exact prevalence and clinicopathologic spectrum in North India are not well documented.

Materials and Methods

The study included all patients aged above 12 years with primary IgAN on kidney biopsy from January 2007 to December 2018. Clinical and pathological parameters were noted. Two histopathologists independently reviewed all kidney biopsies, and MEST-C score was assigned as per the Oxford classification.

Results

IgAN was diagnosed in 681 (11.85%) out of 5751 native kidney biopsies. The mean age was 32 ± 12.3 years, and the male to female ratio was 2.5:1. At presentation, 69.8% had hypertension, 68% had an estimated glomerular filtration rate (eGFR) of less than 60 ml/min, 63.2% had microscopic hematuria, and 4.6% had gross hematuria. The mean proteinuria was 3.61 ± 2.26 g/day, with 46.8% showing nephrotic range proteinuria and 15.2% showing nephrotic syndrome manifestation. Histopathologically, 34.4% of patients had diffuse global glomerulosclerosis. Oxford MEST-C scoring revealed M1 in 67%, E1 in 23.9%, S1 in 46.9%, T1/T2 in 33%, and crescents in 19.6% of biopsies. The mean serum creatinine was significantly higher in cases with E1, T1/2, and C1/2 scores (P < 0.05). Hematuria and proteinuria were significantly higher (P < 0.05) with E1 and C1/2 scores. Coexisting C3 was associated with higher serum creatinine at presentation (P < 0.05).

Conclusion

IgAN patients with late presentation and advanced disease became less amenable to immunomodulation in our cohort. The implementation of point-of-care screening strategies, early diagnosis, and retarding disease progression should be prioritized in the Indian strategy.

Structural modeling for Oxford histological classifications of immunoglobulin A nephropathy

In immunoglobulin A nephropathy (IgAN), Cox regression analysis can select independent prognostic variables for renal functional decline (RFD). However, the correlation of the selected histological variables with clinical and/or treatment variables is unknown, thereby making histology-based treatment decisions unreliable. We prospectively followed 946 Japanese patients with IgAN for a median of 66 mo. and applied structural equation modeling (SEM) to identify direct and indirect effects of histological variables on RFD as a regression line of estimated glomerular filtration rate (eGFR) via clinical variables including amount of proteinuria, eGFR, mean arterial pressure (MAP) at biopsy, and treatment variables such as steroid therapy with/without tonsillectomy (ST) and renin–angiotensin system blocker (RASB). Multi-layered correlations between the variables and RFD were identified by multivariate linear regression analysis and the model’s goodness of fit was confirmed. Only tubular atrophy/interstitial fibrosis (T) had an accelerative direct effect on RFD, while endocapillary hypercellularity and active crescent (C) had an attenuating indirect effect via ST. Segmental sclerosis (S) had an attenuating indirect effect via eGFR and mesangial hypercellularity (M) had accelerative indirect effect for RFD via proteinuria. Moreover, M and C had accelerative indirect effect via proteinuria, which can be controlled by ST. However, both T and S had additional indirect accelerative effects via eGFR or MAP at biopsy, which cannot be controlled by ST. SEM identified a systemic path links between histological variables and RFD via dependent clinical and/or treatment variables. These findings lead to clinically applicable novel methodologies that can contribute to predict treatment outcomes using the Oxford classifications.

A Novel Scoring System Based on Oxford Classification Indicating Steroid Therapy Use for IgA Nephropathy

Introduction

The usefulness of the Oxford classification (MEST-C score) for deciding the management approach for IgA nephropathy (IgAN) remains unclear.

Methods

Effects of steroid therapy on the long-term prognosis for all 858 patients with IgAN and patients classified according to each MEST-C score were evaluated using Kaplan-Meier and Cox regression analyses. Steroid responder score (SRS) and steroid nonresponder score (SNRS) were determined using individual pathology scores when steroids were found to be independently associated, or not, with clinical benefits. In addition, the effects of steroid therapy according to the total SRS/SNRS were analyzed.

Results

Steroid therapy improved the 20-year renal survival rates of patients with IgAN after matching (steroids[+] vs. steroids[−]; estimated glomerular filtration rate [eGFR] [ml/min per 1.73 m²]: 79.4 vs. 77.0, not significant; proteinuria [g/d]: 0.80 vs. 0.62, not significant; renal survival rate: 75.5% vs. 61.7%; P = 0.025) and of patients with M1, E1, S1, C1+2, and T0 scores. Therefore, we considered the total of the M1, E1, S1, and C1+2 scores (point 0: low, 1–2: medium, and 3–4: high) as the SRS and the total of the T1+2 scores (0: low and 1: high) as the SNRS. Multivariate Cox regression analyses revealed that steroid therapy improved the renal prognosis of patients with IgAN with high SRS and any SNRS, unlike patients with IgAN with medium SRS and any SNRS.

Conclusion

Patients with M1, E1, S1, and C1+2 scores responded to steroid therapy; however, those with T1+2 scores did not. Although a high SRS was a useful indicator for steroid therapy, SNRS indicated resistance to steroid therapy.

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.

CD71 mesangial IgA1 receptor and the progression of IgA nephropathy

The transferrin receptor (CD71) is known as a receptor for IgA1 on mesangial cells, but the role of CD71 in IgA nephropathy (IgAN) is unknown. We studied clinical implication of mesangial CD71 in 282 patients with biopsy-proven IgAN (2005-2018). The transcript and protein expression of glomerular CD71 was determined by real-time polymerase chain reaction and immunohistochemistry. Ten subjects with microscopic hematuria only and no evidence of histologic abnormalities on kidney biopsy were considered as controls. Human mesangial cells (HMCs) were treated with sera from IgAN patients and expression levels of CD71 and inflammatory cytokine markers were compared according to disease status. Disease progression was defined as a ≥30% decline in estimated glomerular filtration rate from the baseline value. During a mean follow up of 53.5 (18.3-75.9) months, 80 (28.4%) patients developed disease progression. The mRNA expression of CD71 was significantly higher in progressors than in nonprogressors (P = 0.001). Among the Oxford classification scores, patients with M1 had significantly higher CD71 expression levels than those with M0. In a multivariable Cox model, elevated transcript levels of CD71 were significantly associated with 4.32-fold higher risk of disease progression (P = 0.009). Furthermore, CD71 expression levels independently predicted the increase in proteinuria of ≥50% from the baseline (P = 0.03). Finally, HMCs treated with sera from IgAN patients with the higher Oxford score (M1E1S1T0) more increased the mRNA expression of CD71 and inflammatory markers than those with sera from negative score (M0E0S0T0). However, silencing CD71 significantly reduced expression levels of the inflammatory cytokine genes. Our results show that mesangial CD71 is significantly associated with disease progression and may play a biologic role in IgAN.

Combining clinical features and MEST-C score in IgA nephropathy may be a better determinant of kidney survival

Introduction. IgA nephropathy (IgAN) is a heterogeneous disease with highly variable clinical and histopathological features. We investigated the effects of Oxford classification and clinical features on renal survival in patients with IgAN.Methods. This retrospective observational study conducted from 2013 to 2017. Ninety-seven patients who were followed up more than six months were examined.Results. A total of 97 patients (68% male and median age 40 years) were enrolled in this study. 13% of patients developed end stage renal disease (ESRD) within the median of 37 months of follow-up. Need for renal replacement therapy at the time of diagnosis, serum creatinine level of higher than 1.97 mg/dl, serum albumin level less than 3.5 gr/dl, 24-hour urine protein level of higher than > 3.5 g/day, the percentage of glomerulosclerosis higher than 53%, T2 score and total MEST-C score higher than two were found to be significant predictors of development of ESRD. None of the clinical or histopathological features were found to be significant predictor of steroid treatment sensitivity except T1-2 scores.Conclusion. We think that IgA nephropathy is a heterogeneous disease that requires clinical and histopathological features to be evaluated together, but not individually, to determine renal survival.What is new. Iga nephropathy is a heterogeneous disease and modern pathologic classification systems is not enough to predict to prognosis. Histopathological features to be evaluated with clinical features, but not individually, to determine renal survival. Also glucocorticoid treatment response seems to be independent from clinical and histopathological features except T1-2 score.

Relationship between complement deposition and the Oxford classification score and their combined effects on renal outcome in immunoglobulin A nephropathy

Background

Complement activation has been highlighted in immunoglobulin (Ig) A nephropathy pathogenesis. However, whether the complement system can affect the downstream phenotype of IgA nephropathy remains unknown. Herein, we investigated the association of mesangial C3 deposition with the Oxford classification and their joint effects on worsening kidney function.

Methods

We investigated 453 patients with biopsy-proven IgA nephropathy. C3 deposition was defined as an immunofluorescence intensity of C3 ≥2+ within the mesangium. The subjects were classified according to the combination of C3 deposition and Oxford classification lesions. The primary endpoint was a composite of ≥30% decline in the estimated glomerular filtration rate or an increase in proteinuria ≥3.5 g/g during follow-up.

Results

Among the Oxford classification lesions, mesangial hypercellularity (M1), segmental glomerulosclerosis (S1) and tubulointerstitial fibrosis (T1–2) and crescentic lesion significantly correlated with C3 deposition. During a median follow-up of 33.0 months, the primary endpoint occurred more in patients with M1, S1, T1–2 and mesangial C3 deposition than in those without. In individual multivariable-adjusted Cox analyses, the presence of M1, S1, T1–2 and C3 deposition was significantly associated with higher risk of reaching primary endpoint. In the combined analyses of C3 deposition and the Oxford classification lesions, the hazard ratios for the composite outcome were significantly higher in the presence of C3/M1, C3/S1 and C3/crescent than in the presence of each lesion alone.

Conclusions

Complement deposition can strengthen the significance of the Oxford classification, and the presence of both components portends a poorer prognosis in IgA nephropathy.

Is immunoglobulin A nephropathy different in different ethnic populations?

Immunoglobulin A nephropathy (IgAN) is one of the commonest global patterns of primary glomerulonephritis and remains a leading cause of chronic kidney disease and end-stage renal disease. The sole diagnostic criterion of IgAN remains the presence of dominant mesangial immunoglobulin A deposits on kidney biopsy. Beyond this defining feature, there is significant heterogeneity in the epidemiology, clinical presentation, renal progression and long-term outcomes of IgAN in different ethnic populations. Mirroring this heterogeneity in clinical phenotypes, there is also marked ethnic variation in the extent of histopathological lesions observed on kidney biopsy, which may partly explain the well-documented differences in response to immunomodulatory agents reported in different regions of the world. In parallel, disparities have been identified in genetic association studies and key pathogenic pathways in different ethnic populations. Understanding the basis for these differences in IgAN has important implications for both clinical care and future research. In this review, we will examine the impact of ethnicity on the epidemiology, clinical presentation and outcomes, pathogenesis and genetic associations in IgAN.