A multicenter application and evaluation of the oxford classification of IgA nephropathy in adult chinese patients

Advancing the application of the analytical renal pathology system in allograft IgA nephropathy patients

BACKGROUND

The analytical renal pathology system (ARPS) based on convolutional neural networks has been used successfully in native IgA nephropathy (IgAN) patients. Considering the similarity of pathologic features, we aim to evaluate the performance of the ARPS in allograft IgAN patients and broaden its implementation.

METHODS

Biopsy-proven allograft IgAN patients from two different centers were enrolled for internal and external validation. We implemented the ARPS to identify glomerular lesions and intrinsic glomerular cells, and then evaluated its performance. Consistency between the ARPS and pathologists was assessed using intraclass correlation coefficients. The association of digital pathological features with clinical and pathological data was measured. Kaplan-Meier survival curve and cox proportional hazards model were applied to investigate prognosis prediction.

RESULTS

A total of 56 biopsy-proven allograft IgAN patients from the internal center and 17 biopsy-proven allograft IgAN patients from the external center were enrolled in this study. The ARPS was successfully applied to identify the glomerular lesions (F1-score, 0.696-0.959) and quantify intrinsic glomerular cells (F1-score, 0.888-0.968) in allograft IgAN patients rapidly and precisely. Furthermore, the mesangial hypercellularity score was positively correlated with all mesangial metrics provided by ARPS [Spearman's correlation coefficient (r), 0.439-0.472, and all p values < 0.001]. Besides, a higher allograft survival was noticed among patients in the high-level groups of the maximum and ratio of endothelial cells, as well as the maximum and density of podocytes.

CONCLUSION

We propose that the ARPS could be implemented in future clinical practice with outstanding capability.

Monocytes and Macrophages in Kidney Disease and Homeostasis

The monocyte-macrophage lineage of inflammatory cells is characterized by significant morphologic and functional plasticity. Macrophages have broad M1 and M2 phenotype subgroups with distinctive functions and dual reno-toxic and reno-protective effects. Macrophages are a major contributor to injury in immune-complex-mediated, as well as pauci-immune, glomerulonephritis. Macrophages are also implicated in tubulointerstitial and vascular disease, though there have not been many human studies. Patrolling monocytes in the intravascular compartment have been reported in auto-immune injury in the renal parenchyma, manifesting as acute kidney injury. Insights into the pathogenetic roles of macrophages in renal disease suggest potentially novel therapeutic and prognostic biomarkers and targeted therapy. This review provides a concise overview of the macrophage-induced pathogenetic mechanism as a background for the latest findings about macrophages' roles in different renal compartments and common renal diseases.

To evaluate the utility of Oxford classification in predicting renal outcome in IgA nephropathy patients

BACKGROUND

Immunoglobulin A Nephropathy (IgAN) is a heterogeneous disorder. Multiple ethnicities conducted studies to assess the effectiveness of the Oxford classification of IgAN in prognostication. However, there is no study on the Pakistani population. We aim to identify its prognostic effectivity in our patients.

METHODS

We retrospectively reviewed the medical records of 93 biopsy-proven cases of primary IgAN. We collected the clinical and pathological data at baseline and on follow-ups. The median follow-up period was 12 months. We defined the renal outcome as a ≥ 50% decline in eGFR or end-stage renal disease (ESRD).

RESULTS

Of 93 cases, 67.7% were males with a median age of 29. Glomerulosclerosis was the most prevalent lesion (71%). The median MEST-C was 3. On follow-up, median serum creatinine worsened from 1.92 to 2.2 mg/dL, and median proteinuria reduced from 2.3 g/g to 1.072 g/g. The reported renal outcome was 29%. T and C scores and MEST-C scores above 2 were significantly associated with pre-biopsy eGFR. On Kaplan-Meier analysis, the T and C scores' association was significant with the renal outcome (p-value 0.000 and 0.002). In univariate and multivariate analyses, the association of T-score (p-value 0.000, HR 4.691), total MEST-C score (p-value 0.019), and baseline serum creatinine (p-value 0.036, HR 1.188) were significant with the outcome.

CONCLUSION

We validate the prognostic significance of the Oxford classification. T and C scores, baseline serum creatinine, and total MEST-C score significantly affect the renal outcome. Furthermore, we recommend the inclusion of the total MEST-C score in determining the IgAN prognosis.

Changes in spectrum of biopsy-proven kidney diseases within decade: an analysis based on 10 199 cases from South China

PURPOSE

To assess the regional epidemiological trends of kidney diseases over time in the South China using renal biopsy-proven cases.

METHODS

This retrospective observational cohort study was conducted at the Institute of Nephrology, Second Xiangya Hospital of Central South University, and encompasses all patients diagnosed with kidney disease via biopsy from 2012 to 2021.

RESULTS

The study sample consisted of 10 199 native kidneys, with a male-to-female ratio of 0.91:1 and an average age of 38.74 (±14.53) years. Primary glomerular nephropathy, systemic glomerular nephropathy (SGN), tubulointerstitial disease, and hereditary renal diseases accounted for 66.92 (6825)%, 24.49 (2498)%, 8.06 (822)%, and 0.53 (54)%, respectively. The leading pathologies of primary glomerular nephropathy remained the IgA nephropathy. The frequencies of IgA nephropathy and membranous nephropathy increased significantly, whereas the frequencies of minimal change disease and focal segmental glomerulosclerosis decreased (P < .001) between 2017 and 2021 than in the years 2012 and 2016. An earlier onset of membranous nephropathy was observed in the age group of 45-59 years compared to previous studies. The leading pathologies of SGN were found to be lupus nephritis (758 cases, 30.45%) and hypertension nephropathy (527 cases, 21.17%). The frequencies of hypertension nephropathy and diabetic nephropathy increased between 2017 and 2021 compared to 2012 and 2016 (P < .001), gradually becoming the leading pathological types of SGN. In elderly patients diagnosed with nephrotic syndrome, the frequencies of amyloidosis significantly increased (P < .01).

CONCLUSION

Our study may provide insights for kidney disease prevention and public health strategies. What is already known on this topic The pathological spectrum of kidney diseases has undergone significant transformations in the past decade, driven by the escalating incidence of chronic diseases. Although there are studies exploring the renal biopsy findings from various regions in China which present both similarities and differences in epidemiology, few large-scale reports from the South China in recent decades were published. What this study adds Our findings reveal the following key observations: (i) increased proportion of middle-aged patients leading to the increasing average age at the time of biopsy；(ii) the frequencies of IgA nephropathy and membranous nephropathy (MN) increased significantly, whereas the frequencies of minimal change disease and focal segmental glomerulosclerosis decreased (P < .001) between 2017 and 2021 than in the years 2012 and 2016; (iii) earlier onset of MN in the age group of 45-59 years old was found in our study; and (iv) a higher frequency of hypertension nephropathy and DN presented over time, and frequency of amyloidosis increased in elderly patients diagnosed with NS. How this study might affect research, practice, or policy This single-center yet a large-scale study of the kidney disease spectrum in South China may provide a reference point for the diagnosis, treatment, and prevention of chronic kidney disease.

The effect of fibrinoid necrosis on the clinical features and outcomes of primary IgA nephropathy

BACKGROUND

To explore the clinicopathologic features and outcomes of IgAN patients who presented with fibrinoid necrosis (FN) lesions or not and the effect of immunosuppressive (IS) treatment in IgAN patients with FN lesions as well.

METHODS

This was a retrospective cohort study with 665 patients diagnosed with primary IgAN from January 2010 to December 2020 in Tianjin Medical University General Hospital and having detailed baseline and follow-up characteristics. Patients were divided into two groups depending on the appearance of FN lesions. Patients with FN lesions were recruited into Group FN1, while patients who were not found FN lesions in their renal biopsy specimens were recruited into Group FN0. Compare the differences between Group FN0 and Group FN1 in baseline clinicopathologic features, treatment solutions and follow-up data as well. To evaluate the impact of different fractions of FN lesions on baseline characteristics and prognosis of IgAN, we subdivided patients in Group FN1 into 3 groups depending on the FN lesions distribution, Mild Group: 0 < FN% < 1/16; Moderate Group: 1/16 < FN% < 1/10; Severe Group: FN% > 1/10. Furthermore, we compared the differences in baseline clinicopathologic features, treatment solutions and follow-up data among these three groups. Kidney endpoint event was defined as patients went into end-stage kidney disease (ESKD), which estimated glomerular filtration rate (eGFR) < 15 ml/min/1.73 m^2, regularly chronic dialysis over 6 months or received renal transplantation surgery. The kidney composite endpoint was defined by a ≥ 30% reduction in eGFR, double Scr increase than on-set, ESKD, chronic dialysis over 6 months or renal transplantation. Compare the survival from a composite endpoint rate in different groups by Kaplan-Meier survival curve. The univariate and multivariate Cox models were used to establish the basic model for renal outcomes in patients with FN lesions.

RESULTS

(1) A total of 230 patients (34.59%) were found FN lesions in all participants. Patients with FN lesions suffered more severe hematuria than those without. On the hand of pathological characteristic, patients with FN lesions showed higher proportions of M1, E1, C1/C2 and T1/T2 lesions compared with those without FN lesions. (2) The 1-year, 3-year, and 5-year survival of the composite endpoint were lower in the FN1 group than FN0 group. (3) After adjusting for clinicopathological variables, the presence of FN lesions was a significantly independent risk factor for composite endpoint. By using multivariate Cox regression analyses, we also found when the fraction of FN lesions exceeded 10%, the risk of progression into composite endpoint increased 3.927 times.

CONCLUSION

Fibrinoid necrosis of capillary loops is an independent risk factor of poor renal outcomes. More effective treatment should be considered for those who had FN lesions.

Validating the association of Oxford classification and renal function deterioration among Taiwanese individuals with Immunoglobulin A nephropathy

Validation of the Oxford classification (MEST and MEST-C) for Immunoglobulin A nephropathy (IgAN) in the Taiwanese population is lacking. Our study aimed to validate this classification and assess individual lesion impact. We conducted a retrospective cohort study at Taichung Veterans General Hospital, Taiwan (Jan 2011-Jul 2023). Composite renal outcomes were evaluated using clinical conditions and estimated glomerular filtration rate (eGFR). We used Kaplan-Meier, univariable/multivariable logistic regression and ROC curves. Subgroup analysis considered eGFR < or ≥ 30.0 ml/min/1.73 m2. In 366 renal biopsies, serum creatinine was 1.34 mg/dl, eGFR 53.8 ml/min/1.73 m2, urine protein-creatinine ratio 1159 mg/g. T1/T2 lesions had lowest baseline eGFR (39.6/11.5 ml/min/1.73 m2), correlating with poorest renal survival (median survival 54.7/34.4 months). Univariable analysis linked all individual variables to worse renal outcomes. Multivariable analysis (MEST/MEST-C) showed only T1/T2 linked to worse outcomes. T score had highest predictive power (AUC 0.728, sensitivity 60.2%, specificity 83.6%), with MEST having high AUC (0.758). No extra predictive power was seen transitioning MEST to MEST-C. Subgroup analysis (eGFR < 30.0 ml/min/1.73 m2) associated C1 with improved renal outcomes (odds ratio 0.14, 95% CI 0.03-0.65). T lesion correlated with worse outcomes across subgroups. The T lesion consistently correlated with worse renal outcomes across all groups and baseline statuses. Integrating the C lesion into the transition from MEST to MEST-C did not enhance predictive power. Importantly, the C1 lesion was linked to improved renal outcomes in the eGFR < 30.0 ml/min/1.73 m2 subgroup, likely due to treatment effects.

Ethnicity and IgA nephropathy: worldwide differences in epidemiology, timing of diagnosis, clinical manifestations, management and prognosis

Immunoglobulin A nephropathy (IgAN), the most common primary glomerulonephritis, is one of the major causes of end-stage renal disease. Significant variances in epidemiology, clinical manifestation, timing of diagnosis, management and renal prognosis of IgAN have been reported worldwide. The incidence of IgAN is the most frequent in Asia, followed by Europe, and lower in Africa. Moreover, Asian patients show more frequent acute lesions in renal histology and present poorer renal outcomes compared with Caucasians. The comorbidities also show the difference between Asians and Caucasians. Although the frequency of gross hematuria with upper respiratory tract infection is not different, comorbidities with gastrointestinal diseases are reported to be higher in Europe. Recently, genetic studies for variant ethnic patients revealed widely ranging genetic risks in each ethnicity. A genetic risk score is most elevated in Asians, intermediate in Europeans and lowest in Africans, consistent with the disease prevalence of IgAN globally. Ethnic variance might be highly affected by the difference in genetic background. However, it is also essential to mention that the different timing of diagnosis due to variant urinary screening systems and the indication for renal biopsy in different countries may also contribute to these variances. The management of IgAN also varies internationally. Currently, several novel therapies based on the pathogenesis of IgAN are being assessed and are expected to become available soon. Further understanding the ethnic variance of IgAN might help establish individualized care for this disease. Here, we review the issues of ethnic heterogeneities of IgAN.

Comparative analysis between the safety and efficacy of oral corticosteroids versus corticosteroids pulse therapies in IgA nephropathy

OBJECTIVE

This study retrospectively compared the safety and efficacy of oral corticosteroid therapy (OCT) and corticosteroid pulse therapy (CPT) in the treatment of IgA nephropathy.

METHODS

One ninety-two patients were diagnosed with IgA nephropathy and had an estimated glomerular filtration rate > 15mL/min/1.73m2 and 24-h urine protein level of 0.75-3.5g. Patients were divided into CPT and OCT groups according to the treatment protocol. The differences in the efficacy and safety between the two groups were assessed by logistic regression analysis and propensity score matching.

RESULTS

Significant differences at baseline, including 24-h urine protein level and eGFR, were observed between the two groups. Logistic regression analysis indicated that the remission rate increased significantly, while the incidences of total adverse events and infections decreased in CPT group compared with the OCT group after adjusting the potential confounding factors. Forty-seven pairs of subjects are matched by using propensity score matching with similar baseline data. The results indicate that the total remission rate and complete remission rate were significantly higher, while the incidences of total adverse events were lower (p = 0.008) in the CPT group than in the OCT group. The subgroup analysis showed that CPT group was more likely to achieve remission in patients with initial 24-h urine protein levels falling into the range of 2-3.5 g and Oxford Classification of S1 or C1/2 (p < 0.05).

CONCLUSION

Among patients with IgA nephropathy and 24-h urine protein levels of 0.75-3.5g, CPT may be more effective than OCT in reducing urinary protein levels and improving renal function with a lower incidence of adverse events.

Noninvasive Assessment of the Renal Function, Oxford Classification and Prognostic Risk Stratification of IgAN by Using Intravoxel Incoherent Motion Diffusion-Weighted Imaging and Blood Oxygenation Level-Dependent MRI

BACKGROUND

Immunoglobulin A nephropathy (IgAN) is the most common primary glomerulonephritis worldwide. Oxford classification including mesangial hypercellularity (M), endothelial hypercellularity (E), segmental sclerosis (S), interstitial fibrosis/tubular atrophy (T), and crescent (C) were recommended to predict the prognosis of IgAN.

PURPOSE

To explore whether multiparametric magnetic resonance imaging (MRI) can be applied to assess the renal function, Oxford classification, and risk of progression to end-stage kidney disease within 5 years of IgAN.

STUDY TYPE

Prospective.

POPULATION

A total of 46 patients with pathologically confirmed IgAN and 20 healthy volunteers.

FIELD STRENGTH/SEQUENCE

A 3-T, blood oxygenation level-dependent (BOLD)-MRI, intravoxel incoherent motion diffusion-weighted imaging (IVIM-DWI).

ASSESSMENT

Two radiologists measured the cortex and medulla T2*, apparent diffusion coefficient (ADC), true diffusion (Dt), pseudo-diffusion (Dp), perfusion fraction (fp). All participants were divided into three groups: group 1, healthy volunteers; group 2, patients with estimated glomerular filtration rate (eGFR) ≥60 mL/min/1.73 m2 ; group 3, patients with eGFR <60 mL/min/1.73 m2 . Or two groups: group A, 5-year risk scores ≤10% and group B, 5-year risk scores >10%.

STATISTICAL TESTS

Intraclass correlation coefficient, one-way analysis of variance, least-significant difference, Student's t-test, Pearson product-moment correlation, Spearman's rank correlation, and receiver operating characteristics (ROC) with the area under the curve (AUC). A P value <0.05 was considered statistically significant.

RESULTS

Except for cortical Dp, all other MRI parameters showed significant differences between group 1 and group 2. None of the MRI parameters showed a significant correlation with M, E, or C scores. Cortical T2*, Dt, fp, and medullary Dt and fp showed low-to-moderate significant correlations with S scores. Except for cortical and medullary Dp, all other MRI parameters were significantly correlated with T scores. Cortical Dt showed the largest AUC for differentiating group A from group B (AUC = 0.927) and T0 from T1/T2 (AUC = 0.963).

DATA CONCLUSION

Imaging by IVIM-DWI and BOLD-MRI could facilitate noninvasive assessment of the renal function, Oxford classification, and prognostic risk of IgAN patients.

EVIDENCE LEVEL

2.

TECHNICAL EFFICACY

Stage 3.

Comparative study on clinicopathological features and prognosis of IgA vasculitis nephritis and IgA nephropathy in children

BACKGROUND

IgA vasculitis nephritis (IgAVN) and IgA nephropathy (IgAN) share several clinical and pathological characteristics, though distinctions also exist. Their interrelation, however, remains undefined. This study investigates the clinicopathological divergences and prognostic disparities in pediatric patients with IgAVN and IgAN.

METHODS

Our study encompasses 809 pediatric patients with IgAVN and 236 with IgAN, all of whom underwent kidney biopsy. We utilized the Semiquantitative Classification (SQC) scoring system to juxtapose the pathologies of the two conditions, and performed a COX regression analysis to examine factors influencing their prognoses.

RESULTS

Both patient groups demonstrated a predominance of males. A seasonality was observed, with a higher incidence of IgAN in the summer, and IgAVN in the fall (P < 0.0001). Patients with IgAN exhibited more severe tubulointerstitial injury, higher chronicity index, and total biopsy scores compared to those with IgAVN (P < 0.0001). Mesangial deposition intensity of complement C3, and the rate of pure IgA deposition, were found to be greater in patients with IgAVN compared to those with IgAN (P < 0.0001). The intensity of IgA deposition was also significantly higher in IgAVN patients (P = 0.003). IgAVN demonstrated a superior prognosis, with a higher rate of kidney remission (P < 0.0001). COX regression analysis indicated that interstitial fibrosis, as identified in the SQC pathology system, was associated with the prognosis of both conditions. Furthermore, the findings suggest that IgA deposition levels (IgA +  + and IgA +  + +) could potentially influence the prognosis of IgAVN.

CONCLUSIONS

Compared to IgAVN, IgAN manifests more severely with regard to renal impairment, interstitial damage, and prognosis. The disparities in immune complex deposition levels and locations within the kidneys support the hypothesis of IgAVN and IgAN as distinct diseases. Interstitial fibrosis may serve as a key pathological indicator within the SQC system associated with kidney prognosis in children with IgAVN and IgAN. The degree of IgA deposition could also be linked with the prognosis of IgAVN.

Systematic Review of the Oxford Classification of IgA Nephropathy: Reproducibility and Prognostic Value

Key Points

The Oxford classification of IgA nephropathy defined five features scored subjectively in renal biopsies, identified by the initials MESTC. Two large studies with independent observers showed reproducibility was moderate for T, moderate or poor for M and S, and poor for E and C. In multivariate analyses including clinical features, T was related to 58% of outcomes, with no correlation of MESTC with 24% of outcomes.

Background

The Oxford classification of IgA nephropathy defined five prognostic features scored subjectively in renal biopsies: mesangial cellularity (M), endocapillary hypercellularity (E), segmental sclerosis (S), interstitial fibrosis/tubular atrophy (T), and (fibro)cellular crescents (C). Pathological scoring systems should be reproducible and have prognostic value independently of clinical features. Reproducibility of the classification was not previously investigated in a systematic review, and the most recent systematic reviews of prognostic value were in 2017.

Methods

This systematic review followed PRISMA 2020 guidelines. MEDLINE, PUBMED, and EMBASE databases were searched using the terms “IgA nephropathy” and “Oxford.” Eligible papers applied the classification and mentioned statistical analysis of interobserver reproducibility and/or included multivariate analysis of outcomes related to individual Oxford scores and clinical features, including treatment with corticosteroids or other immunosuppressive drugs.

Results

There were 99 suitable papers before September 23, 2022. Of 12 papers that mentioned reproducibility, only six reported statistics for MEST/MESTC scoring. Four of these were small studies and/or had observers at the same institution. These were considered less representative of application of the classification than two large studies with independent observers, in which agreement was moderate for T, either moderate or poor for M and S, and poor for E and C. In 92 papers with 125 multivariate analyses of various outcomes, the commonest Oxford element associated with outcomes was T (73 of 125, 58%), with no correlation of any element with outcomes in 30 analyses (24%). Treatment with immunosuppression was often related to scores, particularly C and E, without consistent relations between Oxford scores and outcomes in immunosuppressed patients.

Conclusions

This systematic review showed limitations of the Oxford classification in practice, particularly the moderate or poor reproducibility of scores. T was the Oxford score most often related to clinical outcomes, but even this was not consistently reliable as a prognostic indicator.

Prognostic significance of the extent of tubulointerstitial lesions in patients with IgA nephropathy

PURPOSE

IgA nephropathy (IgAN) is the most common type of primary glomerulonephritis worldwide. However, the effect of the degree of tubulointerstitial lesions (TIL) on the renal prognosis of these patients is uncertain.

METHODS

All biopsy-proven primary IgAN patients from a single center (≥ 14 years old) were retrospectively examined from January 2006 to December 2011. According to the Oxford classification for tubulointerstitial lesions in IgAN, eligible patients were assigned to T0 or T1/2 groups. The clinicopathological features of these groups were compared and multivariate models were used to identify the effect of tubulointerstitial lesions on renal prognosis. The composite endpoint was end-stage renal disease or doubling of serum creatinine.

RESULTS

We initially identified 1570 patients with IgAN and examined 988 patients who completed follow-up examinations (mean: 49 months). There were 506 patients in the T0 group (51.2%) and 482 in the T1/2 group (48.8%). The 1-year, 3-year, and 5-year incidences of the composite endpoint were 0.2%, 1.5%, 7.7% in the T0 group, and 1.9%, 9.9%, 18.1% in the T1/2 group. An adjusted multivariate model indicated the hazard ratio for reaching the composite endpoint was 9.3 for patients with T1/2 rather than T0 (reference group). A multivariate logistic analysis of the T1/2 group indicated the independent risk factors for reaching the composite endpoint were decreased eGFR, hypertension, hyperlipidemia, proteinuria, global glomerulosclerosis, and segmental glomerulosclerosis.

CONCLUSION

More severe tubulointerstitial lesions (> 25%, T1/2) were an independent predictor of poor renal prognosis in patients with IgAN.

Divergent manifestations and outcomes of diffuse crescentic immunoglobulin A nephropathy and pauci-immune crescentic glomerulonephritis on long-term

BACKGROUND

Diffuse crescentic IgAN (CIgAN) is an uncommon phenotype of IgAN, which presents as rapidly progressive renal failure, similar to patients with pauci-immune crescentic glomerulonephritis(PCGN). There are limited data on outcomes comparisons between the two.

METHODS

In this single-center, retrospective cohort study, we compared the clinical features, pathological presentation, and renal outcomes of 52 patients with CIgAN and 42 patients with renal-limited PCGN from January 2007 to December 2019.

RESULTS

The CIgAN patients were younger (30.5 ± 13.8 years) than PCGN patients (46.1 ± 11.8 years) (P = 0.001). The CIgAN patients had a higher prevalence of hypertension (86.5% Vs. 41.3%, P = 0.001); and degree of proteinuria (4.2 ± 2.7 g/24 h Vs. 2.3 ± 1.16 g/24 h; P = 0.001) than PCGN patients. The chronicity in terms of global glomerulosclerosis, interstitial fibrosis, and tubular atrophy was higher in the CIgAN group than in the PCGN group. The remission rate with immunosuppression was significantly higher in the PCGN group than in the CIgAN group (P = 0.016). The end-stage renal disease (ESRD) or death within 1 year of diagnosis was significantly more in the CIgAN group (62.3% Vs. 39.1%) than PCGNgroup. For patients who were dialysis-dependent at presentation, the primary outcome of ESRD or death within one year was seen in 90.9% of patients of CIgAN and 44.1% in the PCGN group (P = 0.001). The long-term death non-censored renal survival is poor in the CIgAN group than in PCGN patients. However, patient survival is poor in PCGN patients.

CONCLUSION

CIgAN is a different form of RPGN compared to PCGN and carries a poor prognosis despite similar immunosuppressive therapy in the long term.

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.

Podocytes are likely the therapeutic target of IgA nephropathy with isolated hematuria: Evidence from repeat renal biopsy

Background: The present study aimed to prove the progression of immunoglobulin A nephropathy (IgAN) patients with isolated hematuria based on repeat renal biopsy data for the first time. Methods: 29 IgAN patients with isolated hematuria who received repeat renal biopsies were analyzed retrospectively, while 29 non-isolated hematuria IgAN patients with similar age and background were randomly selected as the control group. Clinical parameters were collected at the time of biopsy. The treatment strategies (conservative treatment with RASS blocker or immunosuppressive treatment) were choosen according to the pathological results at the first renal biopsy. The activity and chronicity indexes of renal lesions were evaluated. Markers of cell inflammation and proliferation were tseted by immunochemistry. The ultrastructure of podocytes was observed by transmission electron microscopy (TEM). Podocyte and oxidative stress marker (NPHS2 and 4-HNE) were detected by immunofluorescence. Results: The IgAN patients with isolated hematuria had better clinical indicators than those with no-isolated hematuria, such as better renal function, higher albumin and lower uric acid. The interval between two biopsies in IgAN patients with isolated hematuria was 630 (interquartile range, 409.5-1,171) days. The hematuria of the patients decreased significantly from 30 (IQR, 4.00-35.00) RBC/ul in the first biopsy to 11 (IQR, 2.50-30.00) RBC/ul in the repeated biopsy (p < 0.05). The level of triglyceride decreased significantly (p < 0.05). The other clinical indicators were not statistically significant (p > 0.05). Deposits of IgA and C3 in the glomerulus were persistent. The activity index decreased, especially cellular crescent formation, while the chronicity index increased. The ultrastructure of podocytes was improved after treatment. The oxidative stress products of podocytes reduced after treatment. Conclusion: Although the clinical indicators of the IgAN patients with isolated hematuria were in the normal range, various acute and chronic pathological changes have occurred, and irreversible chronic changes have been progressing. Cell inflammation and proliferation persisted. Oxidative stress of podocytes was likely to be the therapeutic target. This study provided a strong basis for the progress of IgAN with isolated hematuria through pathological changes before and after treatment. This study will help clinicians recognize the harm of hematuria, change the traditional treatment concept, and help such patients get early treatment.

The Significance of Crescents on the Clinical Features and Outcomes of Primary Immunoglobin A Nephropathy

Background

It is still controversial whether the proportion of crescents below 50% can be an independent predictive risk factor for poor prognosis in IgAN patients. We reported the significance of different proportions of crescents on the clinical features and the cut-off value of crescents in predicting the occurrence of end-stage kidney disease (ESKD) in patients with IgAN.

Methods

We retrospectively analyzed biopsy-proven primary IgAN patients in Sichuan Provincial People’s Hospital from 2007 to 2019. The patients were divided into 5 groups on the basis of crescent proportion as follows: 0 (n = 647), < 10% (n = 221), 10 to 24% (n = 272), 25 to 49% (n = 80), and ≥50% (n = 22). The primary endpoint was defined as ESKD, and the secondary endpoint was the combined renal endpoint (≥50% reduction in eGFR or ESKD). A validation cohort of 346 patients were enrolled from Affiliated Hospital of Southwest Medical University. Cox regression model and Kaplan-Meier survival analysis were performed.

Results

A total of 1242 eligible patients with biopsy-proven IgAN were recorded in the database, compared with the non-crescent group, patients in the crescent group had lower levels of hemoglobin (Hb) and albumin (Alb), higher levels of blood urea nitrogen (BUN), 24h urinary protein and hematuria, a higher proportion of mesangial hypercellularity (M1), endocapillary hypercellularity (E1), segmental glomerulosclerosis (S1), and tubular atrophy/interstitial fibrosis (T1/T2) (p < 0.05). A higher crescent proportion was associated with lower levels of Hb, ALB, eGFR and serum IgG (p < 0.05), higher levels of SCr, BUN, increasing amounts of 24 h urinary protein, increasing proportion of M1 and E1, and increasing severity of interstitial inflammatory infiltration. During the median follow-up of 43 months (range 6-151), 63 individuals (7.0%) reached the primary outcome of ESKD and 99 patients (11.1%) reached the combined renal endpoint. 34(7.5%), 21 (13.3%), 24(12.2%), 14(21.5%) and 6(31.6%) patients reached the combined renal endpoint in the above five groups in crescents 0, <10%, 10∼24%, 25∼49% and ≥50%, respectively. A total of 274(62.6%) cases in the crescent group and 254 (55.7%) cases in the non-crescent group received immunosuppressive therapy. Multivariate Cox regression showed that crescents ≥50% was an independent risk factor for the progression of ESKD (p = 0.003) and crescents ≥25% was an independent risk factor for the combined renal endpoint(p < 0.001). The receiver operating characteristic curve showed that IgAN patients with crescents ≥43.7% had a higher risk of ESKD, even with immunosuppressants (Sensitivity = 75.7%,specificity = 89.6%,p < 0.001). This discovery cohort and the validation cohort further confirmed that patients with crescents <43.7% had better renal prognosis than those with crescents ≥43.7% in the whole group and those with immunosuppressants (p < 0.001).

Conclusion

IgAN patients with crescents had more severe clinicopathological features and poorer prognosis. Crescents ≥50% was an independent risk factor for the progression of ESKD and crescents ≥25% was an independent risk factor for ≥50% reduction in eGFR or ESKD in treated and untreated IgAN patients. Crescents ≥43.7% was an independent risk factor for ESKD in those with immunosuppressants.

Crescents and IgA Nephropathy: A Delicate Marriage

IgA nephropathy (IgAN) is a progressive disease with great variability in the clinical course. Among the clinical and pathologic features contributing to variable outcomes, the presence of crescents has attracted particular interest as a distinct pathological feature associated with severity. Several uncontrolled observations have led to the general thought that the presence and extent of crescents was a prognostic indicator associated with poor outcomes. However, KDIGO 2021 guidelines concluded that either the presence or the relative number of crescents should not be used to determine the progression of IgAN nor should they suggest the choice of immunosuppression. Our aim is to report and discuss recent data on the debated issue of the value of active (cellular and fibrocellular) crescents in the pathogenesis and clinical progression of IgAN, their predictive value, and the impact of immunosuppression on renal function. We conclude that the value of crescents should not be disregarded, although this feature does not have an independent predictive value for progression in IgAN, particularly when considering immunosuppressed patients. An integrated overall evaluation of crescents with other active MEST scores, clinical data, and novel biomarkers must be considered in achieving a personalized therapeutic approach to IgAN patients.

The Role of Complement in Microangiopathic Lesions of IgA Nephropathy

Introduction

Methods

Results

Conclusion

Mesangial Cell-Derived Tenascin-C Contributes to Mesangial Cell Proliferation and Matrix Protein Production in IgA Nephropathy

AIM

Tenascin-C (TNC), a non-structural extracellular matrix glycoprotein, is transiently expressed during development or after injury, playing an important role in injury and repair process. The potential role of TNC in the pathogenesis of IgA nephropathy (IgAN) remains to be clarified.

METHODS

Immunohistochemistry staining for TNC was conducted on paraffin-embedded slices from renal biopsies of 107 IgAN patients, and correlation analysis was made between mesangial TNC expression and clinic-pathological parameters. In situ hybridization for TNC mRNA was further performed to figure out the cells that express TNC within glomeruli. In vitro experiments were also carried out on mouse mesangial cells (SV40 MES13) to elucidate the effect of TNC on mesangial cells.

RESULTS

TNC was expressed in the mesangial area of IgAN, as well as in fibrotic regions. Correlation analysis showed that higher mesangial TNC was associated with higher level of proteinuria, lower eGFR and more serious pathological lesions (MEST score). In situ hybridization revealed that abundant TNC mRNA expression was observed in the affected glomeruli of IgAN, but not in minimal change disease (MCD). Moreover, TNC mRNA co-localized with PDGFRβ mRNA, but not with PODXL mRNA, suggesting that TNC mRNA was expressed in the mesangial cells within glomeruli in IgAN. In vitro experiments showed that exogenous TNC promoted matrix protein production and mesangial cell proliferation, which was attenuated by an EGFR inhibitor.

CONCLUSION

Taken together, these results suggest that mesangial cell-derived TNC contributes to mesangial matrix expansion and mesangial cell proliferation, which is a potential therapeutic target in IgAN.

Incidence, demographic, biochemical, and clinicopathological profile of primary IgAN in a tertiary care center from Northern India

Background

Primary IgA nephropathy (IgAN) has variable distribution and clinicopathological spectrum throughout the world. We report the incidence, demographic, and clinicopathological profile of primary IgAN from a tertiary care center in Northern India.

Methods

This is a single-center, prospective, observational study conducted at Sheri- Kashmir Institute of Medical Sciences, J&K, India, from January 2015 to December 2018. The study was approved by the hospital ethical committee.

Results

A total of 106 patients were included in this study, accounting for 19% (106/558) of all native kidney biopsies done during the period from January 2015 till December 2018. Males and females accounted for 60.4% (64/106) and 39.6% (42/106), respectively, with a ratio of 1.5:1. The mean age was 31.37±11.60 years. Edema and hypertension were the most common presenting symptoms and signs, seen in 69 (65.1%) and 72 (67.9%) patients, respectively. The baseline 24-h urine protein excretion was 2.32 ±1.34 g, Nephrotic range proteinuria (≥3.5g/day) was seen in 23/106 (21.7%). Average serum creatinine was 1.6±0.80 mg/dl and estimated glomerular filtration rate using CKD-EPI was <60 ml/min/1.73 m2 in 48.1% of patients (51/106). In patients with < 1 g proteinuria, 36.8% had E1, 78.9% had S1, 36.8% had T1, and 42.1% had T2 lesions.

Conclusions

IgAN is common in North India and has a more severe histopathological presentation, characterized by extensive sclerosis and tubulointerstitial fibrosis. Renal dysfunction and nephrotic range proteinuria are common. Hypertension, low eGFR, and proteinuria correlate with the presence of segmental scarring, endocapillary hypercellularity, and IFTA. Screening of asymptomatic individuals might help in early diagnosis and long-term preservation of renal function.

Utilizing the MEST score for prognostic staging in IgA nephropathy

Background

The Oxford classification/MEST score is an established histopathologic scoring system for patients with IgA nephropathy (IgAN). The objective of this study was to derive a prognostic model for IgAN based on the MEST score and histopathologic features.

Methods

A total of 306 patients with biopsy-proven primary IgAN were included. Histopathologic samples were retrieved from the Norwegian Kidney Biopsy Registry and reclassified according to the Oxford classification. The study endpoint was end-stage renal disease (ESRD). Patients were subclassified into three risk models based on histologic features (Model A), a composite score calculated from the adjusted hazard ratio values (Model B), and on quartiles (Model C).

Results

The mean follow-up time was 16.5 years (range 0.2–28.1). In total, 61 (20%) patients reached ESRD during the study period. Univariate analysis of M, E, S, T and C lesions demonstrated that all types were associated with an increased risk of ESRD; however, a multivariate analysis revealed that only S, T and C lesions were associated with poor outcomes. Statistical analysis of 15-year data demonstrated that Models A and B were as predictive as the MEST score, with an area-under-the-curve at 0.85. The Harrel c index values were 0.81 and 0.80 for the MEST score and Models A and B, respectively. In the present cohort, adding C lesions to the MEST score did not improve the models prognostic value.

Conclusions

Patients can be divided into risk classes based on their MEST scores. Histopathologic data provide valuable prognostic information at the time of diagnosis. Model B was the most suitable for clinical practice because it was the most user-friendly.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12882-021-02653-y.

A mixed-method evaluation of the relationship between Oxford classification scores and longitudinal changes in proteinuria in patients with immunoglobulin A nephropathy

INTRODUCTION

This study aimed to investigate the relationship between Oxford Classification scores and longitudinal changes in proteinuria in patients with immunoglobulin A nephropathy (IgAN).

METHODS

The study was a single-center retrospective cohort study involving 358 patients with primary IgAN who were treated at the Shenzhen Second People's Hospital, China, between January 2011 and May 2021. Multivariate linear regression and generalized additive mixed models (GAMMs), adjusted for traditional risk confounders, were used to evaluate the correlation between scores for mesangial hypercellularity (M), endocapillary hypercellularity (E), segmental glomerulosclerosis (S), tubular atrophy/interstitial fibrosis (T), and crescents (C) (known as the Oxford Classification MEST-C score system), with proteinuria/creatinine ratio (PCR) at the time of renal biopsy and longitudinal changes in PCR, respectively.

RESULTS

The median PCR was 1061 mg/g, and it increased on average by 68.82 mg/g per year in these patients. Among patients with renal insufficiency, compared with patients without relative lesions, those with E present (E1) (1153.44; 95% confidence interval [CI], 188.99-2117.89 mg/g) and C > 0 (C1/2) (1063.58; 95% CI, 185.25-1941.90 mg/g) were associated with increased PCR levels at the time of renal biopsy. What's more, S present (S1) (194.96; 95% CI, 54.50-335.43 mg/g per year) was associated with the fastest PCR increase; C > 0 (C1/2) (147.59; 95% CI, 8.32-286.86 mg/g per year) and T >25% (T1/2) (77.04; 95% CI, 7.18-146.89 mg/g per year), were also correlated with a faster PCR increase. In patients with normal kidney function, associations between S1 (55.46; 95% CI, 8.93-101.99 mg/g per year) and E1 (94.02; 95% CI, 21.47-166.58 mg/g per year) and PCR change could be observed. Additionally, in patients with overweight/obesity, S1 (156.09; 95% CI, 52.41-259.77 mg/g per year), E1 (143.34; 95% CI, 35.30-251.38 mg/g per year), T1/2 (116.04; 95% CI, 22.58-209.51 mg/g per year), as well as C1/2 (134.03; 95% CI, 41.73-226.32 mg/g per year) were associated with noticeably quicker PCR increase.

CONCLUSIONS

Overall, E1 and C1/2 were independently associated with raised proteinuria levels at the time of renal biopsy, and S1, E1, T1/2, C1/2 were independently associated with a longitudinal increase in proteinuria in the patients with IgAN, especially in those with renal insufficiency or overweight/obesity, suggesting that currently available treatments might not be satisfactory, and weight control might be beneficial. Individual therapy development might benefit from the use of the Oxford Classification system.

Randomized clinical study to evaluate the effect of personalized therapy on patients with immunoglobulin a nephropathy

Background

Randomized controlled trials (RCTs) have been conducted, stratifying idiopathic immunoglobulin A nephropathy (IgAN) patients based on the laboratory findings [serum creatinine, estimated glomerular filtration rate (eGFR) and daily proteinuria]. In contrast, data from kidney biopsy have been used only for clinical diagnosis. Therefore, IgAN patients with active or chronic renal lesions have been receiving the same therapy in experimental and control arms of randomized clinical trials (RCTs).

Methods

Our clinical study of IgAN (CLIgAN) is a multicentre, prospective, controlled and open-label RCT based on patients’ stratification at the time of their kidney biopsy. We will consider, first, the type of renal lesions, followed by serum creatinine values, eGFR and proteinuria. Primary and secondary endpoints will be monitored. Then, we will determine whether personalized therapy can slow the decline of renal function and delay end-stage kidney disease.

Results

We will enrol 132 IgAN patients with active renal lesions (66 patients per arm) in the first RCT (ACIgAN). They will receive corticosteroids combined with renin–angiotensin system blockers (RASBs) or only RASBs. A total of 294 IgAN patients with chronic or moderate renal lesions at high or very high risk of chronic kidney disease (147 patients per arm) will be enrolled in the second RCT (CHRONIgAN), in which they will receive dapagliflozin, a sodium–glucose cotransporter 2 inhibitor, combined with RASBs, or RASBs alone.

Conclusion

Using this approach, we hypothesize that patients could receive personalized therapy based on renal lesions to ensure that the right drug gets to the right patient at the right time.

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.

Oxidative stress and macrophage infiltration in IgA nephropathy

BACKGROUND

The aim of this study was to evaluate the interactions among serum levels of galactose-deficient IgA1 (Gd-IgA1), oxidative stress and macrophage infiltration and their clinical correlates in patients with IgA Nephropathy (IgAN).

METHODS

A total of 47 patients with biopsy-proven primary IgAN, aged between 16 and 79 years, with a follow-up period ≥ 1 year or who showed progression to end stage kidney disease (ESKD) regardless the duration of follow-up were included. Study endpoint was the progression to ESKD. Serum Gd-IgA1 and advanced oxidation protein product (AOPP) levels were measured using ELISA assays. Kidney biopsies were evaluated according to the Oxford MEST-C scoring, with C4d and CD68 staining.

RESULTS

Seventeen patients (36%) experienced ESKD during a median follow-up time of 6 years (IQR 3.7-7.5). Serum AOPP levels were correlated with the intensity of glomerular C3 deposition (r = 0.325, p = 0.026), glomerular (r = 0.423, p = 0.003) and interstitial CD68 + cell count (r = 0.298, p = 0.042) and Gd-IgA1 levels (r = 0.289, p = 0.049). Serum Gd-IgA1 levels were correlated with the intensity of C3 deposition (r = 0.447, p = 0.002). eGFR at biopsy (adjusted HR (aHR) 0.979 p = 0.011), and E score (aHR, 8.305, p = 0.001) were associated with progression to ESKD in multivariate analysis. 5-year ESKD-free survival rate was significantly lower in patients with higher E score compared to patients with E score 0 [p = 0.021].

CONCLUSIONS

An increased number of macrophages in the glomerular and tubulointerstitial area may play a role in oxidative stress and complement system activation. Endocapillary hypercellularity is a predictive factor for poor prognosis in IgAN.

The effect of immunosuppressive therapy in patients with fibrinoid necrosis lesions in a large cohort of patients with IgA nephropathy

BACKGROUND

Fibrinoid necrosis is considered one of the active pathological lesions in IgA nephropathy. Whether patients with IgA nephropathy with fibrinoid necrosis lesions benefit from immunosuppressive therapy in terms of long-term outcomes remains uncertain. This study aimed to evaluate the response to immunosuppressive therapy in patients with fibrinoid necrosis lesions in a large cohort of patients with IgA nephropathy.

METHODS

A total of 1325 patients with kidney biopsy-proven IgA nephropathy from 1994 to 2016 were recruited from the Peking University First Hospital IgA Nephropathy Database. The clinicopathological characteristics of patients with fibrinoid necrosis lesions and the effect of immunosuppressive therapy on patients with fibrinoid necrosis lesions alone or in those with fibrinoid necrosis together with crescents or endocapillary hypercellularity lesions were analyzed.

RESULTS

In total, 107/1325 (8.1%) patients showed fibrinoid necrosis lesions, and 92/107 (86.0%) of these patients showed fibrinoid necrosis associated either with cellular/fibrocellular crescents or endocapillary hypercellularity lesions. The presence of fibrinoid necrosis together with crescents or endocapillary hypercellularity was an independent risk factor for the kidney composite endpoint (HR, 2.11; 95% CI, 1.16-3.84; P = 0.02) in patients without immunosuppression, while for those receiving immunosuppressive therapy, kidney outcome was improved (HR, 0.80; 95% CI, 0.46-1.39; P = 0.42). However, the predictive value of fibrinoid necrosis lesions alone did not change significantly between patients with and without immunosuppressive therapy.

CONCLUSIONS

The presence of fibrinoid necrosis with crescents or endocapillary hypercellularity lesions together, but not fibrinoid necrosis lesions alone, was a pathological indicator of patients who may benefit from immunosuppressive therapy.

IgA Nephropathy: A Chinese Perspective

Background

IgA nephropathy (IgAN) is the most common primary glomerular disease worldwide and remains a leading cause of chronic kidney disease and end-stage renal disease. The disease prevalence, clinical and pathological phenotypes, the underlying pathogenic molecular mechanisms, and the response to treatments are highly heterogeneous in different ethnic populations, which raise the concern that IgAN may differ across different parts of the world.

Summary

From a Chinese perspective, we stated the disease burden of IgAN, summarized genome-wide association studies and research into pathological molecules, and compared them with findings based on other populations. The emerging biomarkers, indigenous clinical trials, and major challenges for Chinese researchers and nephrologists in studying IgAN are also discussed.

Key Messages

In this review, we described a higher risk of major susceptible loci in mucosal immunity, IgA production, and complement activation pathways in Chinese patients with IgAN. With our understanding of the pathogenesis of IgAN, novel biomarkers are emerging. Although there are challenges for conducting high-quality clinical trials in China, it is still feasible to conduct innovative and well-designed studies of IgAN. In the future, international collaborations on research infrastructure would be helpful to advance clinical and basic research in China.

Is IgA nephropathy the same disease in different parts of the world?

Since it was first described in 1968, immunoglobulin A nephropathy (IgAN) is understood to be the most common form of glomerulonephritis worldwide. The diagnosis of IgAN depends on the presence of dominant mesangial IgA1 deposition by renal biopsy. To date, a wide spectrum of clinical and pathologic features of IgAN have been observed, implying that IgAN might not be the same disease across the world. Here, we review the characteristics of IgAN from perspectives of epidemiology, clinical-pathological patterns, disease pathogenesis, and treatment response across different ethnic populations. Overall, IgAN is most prevalent in Asians, followed by Caucasians, and relatively rare in Africans. More severe clinical presentation and higher risk of disease progression have been reported in Asians than Europeans. Moreover, active lesions, such as endocapillary hypercellularity and crescents, are more commonly reported in Asians than Europeans. Response to corticosteroid/immunosuppression therapy is variably reported, with greater apparent efficacy reported in Asian than European studies. Although a multi-hit hypothesis has been suggested for IgAN, the relative importance of each "hit" may vary in different ethnic populations and this variation underlies the differences in presentation of IgAN. In the future, a better understanding of pathogenic pathways operating in different ethnic populations may help provide better biomarkers of disease and more precise targeting of treatment strategies for IgAN.

The predictive value of Oxford MEST-C classification to immunosuppressive therapy of IgA nephropathy

PURPOSE

To analyze the efficacy of immunosuppressive therapy in IgA nephropathy and investigate the value of all clinicopathologic indicators.

METHOD

One hundred and one eligible IgA nephropathy patients were retrospectively studied. All the patients received immunosuppressive treatment and were then grouped according to the treatment outcome. The endpoint was a composite outcome (halving eGFR, end-stage renal disease (ESRD) or death due to kidney disease). The outcomes of immunosuppressive therapy were evaluated, and the factors influencing the outcomes of immunosuppressive therapy were analyzed by logistics regression. The independent significance of clinicopathologic indicators on renal outcome was then analyzed by multivariable Cox regression.

RESULTS

Multivariate logistic regression analysis showed that S1 and M1 were the risk factors for the immunosuppressive treatment effect in IgAN patients, and eGFR was the protective factor for the immunosuppressive treatment effect in IgAN patients. Kaplan-Meier analysis revealed that outcomes of immunosuppressive therapy were significantly associated with poor renal outcomes. Multiple Cox regression analysis further confirmed that M1, T2, and the initial level of eGFR were independent predictive factors for poor renal outcomes.

CONCLUSIONS

M, S scores and initial eGFR are independent predictors of outcomes of immunosuppressive therapy. Only M, T scores can effectively predict poor renal outcomes after immunosuppressive therapy. Nonetheless, stable eGFR and low proteinuria can protect renal outcomes.

The association of microhematuria with mesangial hypercellularity, endocapillary hypercellularity, crescent score and renal outcomes in immunoglobulin A nephropathy

BACKGROUND

Microhematuria is common in immunoglobulin A nephropathy (IgAN). However, current prognostication is based on proteinuria and mesangial hypercellularity, endocapillary hypercellularity, segmental sclerosis, tubulointerstitial fibrosis and crescent (MEST-C) scores.

METHODS

In this retrospective study, we evaluated whether MEST-C score components are associated with the presence of microhematuria at biopsy and whether the degree of microhematuria during follow-up is associated with change in estimated glomerular filtration rate (eGFR), after adjusting for clinical and histological parameters. We identified 125 patients with biopsy-proven IgAN and MEST-C scoring who were not on immunosuppressive therapy at biopsy. Microhematuria was defined as ≥3 red blood cells (RBCs)/high-power field (hpf).

RESULTS

Of the 125 patients, 97 had microhematuria at baseline and were more likely to have M1, E1 and C ≥ 1 lesions (P < 0.05 for all) compared with patients without microhematuria. Of the 125 patients, 72 had follow-up data available. An increase in the degree of microhematuria was significantly associated with an eGFR decline of -0.81 mL/min/1.73 m2 [95% confidence interval (CI) -1.44 to -0.19, P = 0.01], after adjusting for follow-up time, proteinuria and T score. Severe microhematuria (≥21 RBCs/hpf) was associated with an even larger decline in eGFR (-3.99 mL/min/1.73 m2; 95% CI -6.9411 to -1.0552, P = 0.008), after similar adjustments.

CONCLUSION

Degree of microhematuria during follow-up is an independent predictor of eGFR decline after adjusting for clinical and histological parameters. Therefore, monitoring the degree of microhematuria as well as proteinuria is important when evaluating patients with IgAN. Additional studies using improvement in microhematuria as a primary surrogate outcome are needed.

A Novel Urinary Proteomics Classifier for Non-Invasive Evaluation of Interstitial Fibrosis and Tubular Atrophy in Chronic Kidney Disease

Non-invasive urinary peptide biomarkers are able to detect and predict chronic kidney disease (CKD). Moreover, specific urinary peptides enable discrimination of different CKD etiologies and offer an interesting alternative to invasive kidney biopsy, which cannot always be performed. The aim of this study was to define a urinary peptide classifier using mass spectrometry technology to predict the degree of renal interstitial fibrosis and tubular atrophy (IFTA) in CKD patients. The urinary peptide profiles of 435 patients enrolled in this study were analyzed using capillary electrophoresis coupled with mass spectrometry (CE-MS). Urine samples were collected on the day of the diagnostic kidney biopsy. The proteomics data were divided into a training (n = 200) and a test (n = 235) cohort. The fibrosis group was defined as IFTA ≥ 15% and no fibrosis as IFTA < 10%. Statistical comparison of the mass spectrometry data enabled identification of 29 urinary peptides with differential occurrence in samples with and without fibrosis. Several collagen fragments and peptide fragments of fetuin-A and others were combined into a peptidomic classifier. The classifier separated fibrosis from non-fibrosis patients in an independent test set (n = 186) with area under the curve (AUC) of 0.84 (95% CI: 0.779 to 0.889). A significant correlation of IFTA and FPP_BH29 scores could be observed Rho = 0.5, p < 0.0001. We identified a peptidomic classifier for renal fibrosis containing 29 peptide fragments corresponding to 13 different proteins. Urinary proteomics analysis can serve as a non-invasive tool to evaluate the degree of renal fibrosis, in contrast to kidney biopsy, which allows repeated measurements during the disease course.

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.

Volume of Crescents Affects Prognosis of IgA Nephropathy in Patients without Obvious Chronic Renal Pathology

INTRODUCTION

A working group on the Oxford classification of IgA nephropathy (IgAN) recently reported that crescents detected in the kidney tissue predicted a worse renal outcome. However, the effect of C1 lesion (crescents in <1/4th of all glomeruli) and their volume on the prognosis of IgAN is still unclear. We explored the association of C1 lesion with the renal prognosis in IgAN patients without obvious chronic renal lesions (glomerulosclerosis <25%, T score <2).

METHODS

We investigated 305 biopsy-proven IgAN patients without obvious chronic renal lesions. Clinicopathologic features and treatment modalities were recorded. The patients were divided into several groups according to the presence or absence of a global crescent: no crescent (NC) group, only segmental crescent (SC) group, and global crescent (GC) group. The outcome was the survival from a combined event defined by a ≥15% decline in the estimated glomerular filtration rate (eGFR) after 1 year or ≥30% decline in the eGFR after 2 years.

RESULTS

Among all patients, 75.7% were in the NC group, 14.8% were in the SC group, and 9.5% were in the GC group. Compared with the NC group, patients in the SC group and the GC group had more urine protein, lower eGFR, and presented with more severe pathological change. During a median follow-up of 34.8 (26.16-57.95) months, the combined event occurred in 34 individuals (11.1%). In a multivariate model, the GC group (HR = 2.756, 95% CI = 1.068-7.109) was associated with an increased risk of the combined event.

CONCLUSIONS

In IgAN patients without obvious chronic renal lesions, the GC group had more severe clinical and pathological manifestations than in the NC group. GC is an independent risk factor for the progression of IgAN renal function.

The Serum Uric Acid Level Is Related to the More Severe Renal Histopathology of Female IgA Nephropathy Patients

Hyperuricemia is a significant risk factor for cardiovascular morbidity and chronic kidney disease progression. IgA nephropathy (IgAN) is a well-known primary glomerular nephropathy. Hyperuricemia is associated with a poor prognosis in IgAN patients. We evaluated the association of hyperuricemia with the histopathological severity of IgAN in male and female patients; 658 patients diagnosed with IgAN via kidney biopsy were initially included. Baseline patient data were collected by eight university hospitals affiliated with the College of Medicine of the Catholic University of Korea. Pathological features were independently evaluated by eight expert pathologists working in the hospitals, and the consensus was reached. Of the initial 658 patients, 517 were finally included (253 males and 264 females). Hyperuricemia was defined as a serum uric acid (UA) level >7.0 mg/dL for males and >5.6 mg/dL for females; 108 (42.7%) males and 95 (35.9%) females exhibited hyperuricemia. Compared to the patients with normal UA levels, the global glomerulosclerosis, segmental sclerosis, mesangial matrix expansion (MME), endocapillary proliferation (ECP), interstitial fibrosis (IF), and tubular atrophy (TA) scores were higher in hyperuricemic males and females. In multivariable linear regression, the serum UA level correlated significantly with the MME, ECP, IF, and TA scores of female IgAN patients only.

Role of Human Mesangial-Tubular Crosstalk in Secretory IgA-Induced IgA Nephropathy

BACKGROUND

IgA nephropathy (IgAN) is characterized by the mesangial deposition of pathogenic IgA. We previously detected the deposition of pathogenic secretory IgA (SIgA) in the mesangium of about one-third of IgAN patients. Tubulointerstitial injury has an important role in the development of IgAN. However, the relationship between SIgA and tubulointerstitial damage is currently unclear. In this work, the role of the mesangial-tubular crosstalk was explored in the tubulointerstitial damage in SIgA-induced IgAN.

METHODS

SIgA deposition in renal tissues of IgAN patients was detected by immunofluorescence. Flow cytometry was used to assess the binding of SIgA to human renal mesangial cells (HRMC) and human proximal tubule epithelial (HK-2) cells. HK-2 was co-cultured with HRMC added with SIgA isolated from patients or normal volunteers. Protein synthesis and gene expressions of TNF-α, TGF-β1, and MCP-1 were determined by ELISA and PCR, respectively. The expressions of the above cytokines in renal tissues of patients and normal controls were detected by immunohistochemistry.

RESULTS

Twenty-nine of 96 patients had SIgA deposition in the mesangium, but SIgA was rarely detected in the tubulointerstitium. The binding rate of SIgA to HK-2 (2.79%) was significantly lower than that of HRMC (81.6%) (p < 0.001). The expressions of TNF-α, TGF-β1, and MCP-1 in HRMC were significantly higher than in SIgA-stimulated HK-2 (p < 0.05), and their expressions were significantly higher in the SIgA-stimulated co-culture group compared with SIgA-stimulated HRMC (p < 0.05). The expressions of the above cytokines were mainly detected in tubulointerstitium of IgAN patients with positive and negative SIgA deposition, without significant difference between the 2 groups, but to a significantly higher level than that in normal controls, and their expressions positively correlated with tubulointerstitial injury.

CONCLUSION

Inflammatory factors released from the mesangium after SIgA deposition might mediate tubulointerstitial damage via mesangial-tubular crosstalk in IgAN.

Epidemiology, baseline characteristics and risk of progression in the first South-Asian prospective longitudinal observational IgA nephropathy cohort

INTRODUCTION

Glomerular Research And Clinical Experiments-IgA Nephropathy in Indians (GRACE-IgANI) is the first prospective South Asian IgAN cohort with protocolized follow-up and extensive biosample collection. Here we report the baseline clinical, biochemical, and histopathologic characteristics of GRACE IgANI and calculate baseline risk of progression for the cohort.

METHODS

201 incident adults with kidney biopsy-proven primary IgAN were recruited into GRACE-IgANI between March 2015 and September 2017. As of April 30, 2020, the cohort had completed a median follow-up of 30 months (interquartile range [IQR] 16-39).

RESULTS

The commonest clinical presentation in GRACE IgANI was hypertension, with or without proteinuria, and nephrotic-range proteinuria was present in 34%, despite <10 months of lead time to kidney biopsy. The GRACE-IgANI kidney biopsy data demonstrated a disproportionate absence of active glomerular lesions and overrepresentation of segmental sclerosing lesions and tubulointerstitial fibrosis at presentation, often coexistent with relatively well-preserved estimated glomerular filtration rate (eGFR) and low levels of proteinuria, especially in males. Baseline risk of progression was calculated for each evaluable patient using 2 different risk prediction tools. The median 5-year absolute risk of end-stage kidney disease (ESKD) was 19.8% (IQR 2.7-57.4) and median 5-year risk of progression to the combined endpoint of 50% decline in eGFR or ESKD was 35.5% using the 2 tools.

CONCLUSIONS

The predicted risk of progression in this cohort was considerable. Over the next 5 years, we will dissect the pathogenic pathways that underlie this severe South Asian IgAN phenotype.

Quantifying Duration of Proteinuria Remission and Association with Clinical Outcome in IgA Nephropathy

BACKGROUND

On the basis of findings of observational studies and a meta-analysis, proteinuria reduction has been proposed as a surrogate outcome in IgA nephropathy. How long a reduction in proteinuria needs to be maintained to mitigate the long-term risk of disease progression is unknown.

METHODS

In this retrospective multiethnic cohort of adult patients with IgA nephropathy, we defined proteinuria remission as a ≥25% reduction in proteinuria from the peak value after biopsy, and an absolute reduction in proteinuria to <1 g/d. The exposure of interest was the total duration of first remission, treated as a time-varying covariate using longitudinal proteinuria measurements. We used time-dependent Cox proportional hazards regression models to quantify the association between the duration of remission and the primary outcome (ESKD or a 50% reduction in eGFR).

RESULTS

During a median follow-up of 3.9 years, 274 of 1864 patients (14.7%) experienced the primary outcome. The relationship between duration of proteinuria remission and outcome was nonlinear. Each 3 months in sustained remission up to approximately 4 years was associated with an additional 9% reduction in the risk of disease progression (hazard ratio [HR], 0.91; 95% confidence interval [95% CI], 0.89 to 0.93). Thereafter, each additional 3 months in remission was associated with a smaller, nonsignificant risk reduction (HR, 0.99; 95% CI, 0.96 to 1.03). These findings were robust to multivariable adjustment and consistent across clinical and histologic subgroups.

CONCLUSIONS

Our findings support the use of proteinuria as a surrogate outcome in IgA nephropathy, but additionally demonstrate the value of quantifying the duration of proteinuria remission when estimating the risk of hard clinical endpoints.

Tubular decoy receptor 2 as a predictor of prognosis in patients with immunoglobulin A nephropathy

Background

Accelerated senescence of renal tubular epithelial cells (RTECs) might contribute to immunoglobulin A nephropathy (IgAN) progression. This study aimed to determine whether the RTEC senescence marker, decoy receptor 2 (DcR2), could predict prognosis in IgAN.

Methods

We included a retrospective cohort of 105 patients with biopsy-proven IgAN. Tubular DcR2 expression was assessed at renal biopsy and the Oxford histological MEST-C score [mesangial hypercellularity (M), endocapillary proliferation (E), segmental sclerosis (S), interstitial fibrosis/tubular atrophy (T) and crescents (C)] defined disease severity. IgAN progression was defined as a composite of end-stage renal disease or a 30% decline in the estimated glomerular filtration rate (eGFR), analyzed using Kaplan–Meier and Cox regression analyses.

Results

Tubular DcR2 was overexpressed in IgAN. Numbers of DcR2 and p16 double-positive RTECs increased with increasing severity of tubular atrophy/interstitial fibrosis (T lesion). Patients with ≥25% tubular DcR2 expression experienced worse proteinuria, T lesions and a lower eGFR. Cumulative renal survival was significantly lower in patients with ≥25% DcR2 positivity. Multivariate regression analyses showed that ≥25% tubular DcR2 expression was significantly associated with worse eGFR slopes (the rate of renal function decline; P = 0.003) and the incidence of the composite outcome (P = 0.001) in IgAN. The addition of tubular DcR2 to a model with clinical data at biopsy (mean arterial pressure, proteinuria and eGFR) or MEST-C score significantly improved the 5-year risk prediction of IgAN progression, as confirmed by receiver operating characteristic curve analyses.

Conclusions

Tubular DcR2 expression detected at biopsy was a strong independent predictor for IgAN progression and might have prognostic value in addition to established risk markers.

Spectrums and Prognosis of Kidney Disease in Patients with Ankylosing Spondylitis

Background/Aims

Renal involvement was a common extra-articular manifestation of ankylosing spondylitis (AS). Few reports have investigated the pathological characteristics and renal outcomes of AS patients with kidney disease. The aim of this study was to investigate the pathological spectrums and the renal prognosis of AS patients with kidney disease.

Methods

This retrospective and observational study was conducted working on 62 patients (47 males and 15 females) with a diagnosis of AS (ACR, 1984) and renal biopsies between 2008 and 2017. The histopathological findings and associated clinical manifestations were collected, and the renal prognoses of patients with kidney disease were evaluated too. Multivariate binary logistic regression analysis was performed to identify risk factors for the occurrence of IgA nephropathy (IgAN).

Results

Renal biopsy revealed that IgAN accounted for a majority (74.2%) of the kidney disease with AS, while membranous nephropathies, minimal change disease, focal segmental glomerulosclerosis, and other lesions accounted for a small minority. Multivariate analysis revealed that serum immunoglobulin A >3.45 g/L and immunoglobulin G >9.06 g/L were risk factors for the occurrence of IgAN. With a median follow-up time of 24.3 months, 28 patients (50.9%) reached complete remission, 9 patients (16.4%) had partial remission, and 1 patient had an eGFR decline >30%. No difference was found in prognosis between IgAN and non-IgAN.

Conclusion

IgAN occurred in 76.4% of the kidney disease with AS, and higher serum immunoglobulin A and G increased the risk for the occurrence of IgAN. The renal prognosis of kidney disease in AS was good.

Identification of glomerular lesions and intrinsic glomerular cell types in kidney diseases via deep learning

Identification of glomerular lesions and structures is a key point for pathological diagnosis, treatment instructions, and prognosis evaluation in kidney diseases. These time‐consuming tasks require a more accurate and reproducible quantitative analysis method. We established derivation and validation cohorts composed of 400 Chinese patients with immunoglobulin A nephropathy (IgAN) retrospectively. Deep convolutional neural networks and biomedical image processing algorithms were implemented to locate glomeruli, identify glomerular lesions (global and segmental glomerular sclerosis, crescent, and none of the above), identify and quantify different intrinsic glomerular cells, and assess a network‐based mesangial hypercellularity score in periodic acid–Schiff (PAS)‐stained slides. Our framework achieved 93.1% average precision and 94.9% average recall for location of glomeruli, and a total Cohen's kappa of 0.912 [95% confidence interval (CI), 0.892–0.932] for glomerular lesion classification. The evaluation of global, segmental glomerular sclerosis, and crescents achieved Cohen's kappa values of 1.0, 0.776, 0.861, and 95% CI of (1.0, 1.0), (0.727, 0.825), (0.824, 0.898), respectively. The well‐designed neural network can identify three kinds of intrinsic glomerular cells with 92.2% accuracy, surpassing the about 5–11% average accuracy of junior pathologists. Statistical interpretation shows that there was a significant difference (P value < 0.0001) between this analytic renal pathology system (ARPS) and four junior pathologists for identifying mesangial and endothelial cells, while that for podocytes was similar, with P value = 0.0602. In addition, this study indicated that the ratio of mesangial cells, endothelial cells, and podocytes within glomeruli from IgAN was 0.41:0.36:0.23, and the performance of mesangial score assessment reached a Cohen's kappa of 0.42 and 95% CI (0.18, 0.69). The proposed computer‐aided diagnosis system has feasibility for quantitative analysis and auxiliary recognition of glomerular pathological features. © 2020 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.

Validation of the revised Oxford classification for IgA nephropathy considering treatment with corticosteroids/immunosuppressors

The Oxford classification for IgA nephropathy (IgAN) was updated in 2017. We have validated the revised Oxford classification considering treatment with corticosteroids/immunosuppressors. In this retrospective analysis, 871 IgAN patients were enrolled. Patients were divided into two groups, those treated with or without corticosteroids/immunosuppressors. The 20-year renal prognosis up to end-stage renal disease was assessed using the Oxford classification. In all patients, the renal survival rate was 87.5% at 10 years and 72.6% at 20 years. The T score alone was significantly related to renal prognosis in the Kaplan–Meier analysis and multivariate Cox regression analysis. In the non-treatment group (n = 445), E, S, T, and C scores were significantly related to renal survival rates, however, in the treatment group (n = 426), T score alone was significantly related to renal prognosis on Kaplan–Meier analysis, indicating that corticosteroids/immunosuppressors improved renal prognosis in E1, S1, and C1. In patients with E1, S1, or C1, the treatment group showed significantly better renal prognosis than the non-treatment group in univariate and multivariate analysis. The Oxford classification and T score were used to determine renal prognosis in IgAN patients. Corticosteroids/immunosuppressors improved renal prognosis, especially E1, S1, and C1 scores.

The correlation analysis between the Oxford classification of Chinese IgA nephropathy children and renal outcome - a retrospective cohort study

BACKGROUND

The 2016 Oxford Classification's MEST-C scoring system predicts outcomes in adults with IgA nephropathy (IgAN), but it lacks tremendous cohort validation in children with IgAN in China. We sought to verify whether the Oxford classification could be used to predict the renal outcome of children with IgAN.

METHODS

In this retrospective cohort study, 1243 Chinese IgAN children who underwent renal biopsy in Jinling Hospital were enregistered from 2000 to 2017. The combined endpoint was defined as either a ≥ 50% reduction in estimated glomerular filtration rate (eGFR) or end-stage renal disease (ESRD). We probed into the relevance betwixt the Oxford classification and renal prognosis.

RESULTS

There were 29% of children with mesangial proliferation(M1), 35% with endocapillary proliferation (E1), 37% with segmental sclerosis/adhesion lesion (S1), 23% with moderate tubular atrophy/interstitial fibrosis (T1 25-50% of cortical area involved), 4.3% with severe tubular atrophy/interstitial fibrosis (T2 > 50% of cortical area involved), 44% with crescent in< 25% of glomeruli(C1), and 4.6% with crescent in> 25% of glomeruli (C2). All children were followed for a medial of 7.2 (4.6-11.7) years, 171 children (14%) arrived at the combined endpoint. The multivariate COX regression model revealed that the presence of lesions S (HR2.7,95%CI 1.8 ~ 4.2, P<0.001) and T (HR6.6,95%CI 3.9 ~ 11.3, P<0.001) may be the reason for poorer prognosis in the whole cohort. In contrast, C lesion showed a significant association with the outcome only in children received no immunosuppressive treatment.

CONCLUSIONS

This study revealed that S and T lesions were useful as the long-term renal prognostic factors among Chinese IgAN children.

Renal survival and risk factors in IgA nephropathy with crescents

PURPOSE

The association between crescents and renal outcomes was inconsistent in a Chinese IgA nephropathy (IgAN) cohort, and limited research has investigated the prognosis of IgAN patients with crescents.

METHODS

Between January 2008 and January 2013, 169 consecutive IgAN patients with crescents in the Xijing Hospital, who were matched to IgAN patients without crescents at a 1:1 ratio by sex, age, eGFR, and proteinuria were reviewed. Combined events were defined by either a ≥ 50% reduction in eGFR or ESRD.

RESULTS

All patients were followed for a mean of 49.9 ± 26.0 months, and 41 (12.1%) patients had developed combined events. Five multivariate Cox regression models were created, and crescents was an independent risk factor for combined events. In model 5, crescents (HR = 2.216, 95% CI 1.040-4.345, P = 0.039) were notably associated with the risk of combined events after adjusting for age, sex, smoking, TA-P, persistent hematuria, and TA-MAP. Of the IgAN patients with crescents, 17.2% had developed combined events. In the baseline variables model, age, proteinuria, eGFR, E1, T1-T2, and RAAS had statistically significant associations with combined events in the multivariate Cox regression analyses. In the time varying variables model, TA-P, persistent hematuria, and TA-MAP were independent risk factors for combined events.

CONCLUSION

We validated that the presence of crescents was an independent predictor of combined events in Chinese IgAN patients. Age, proteinuria, eGFR, E1, T1-T2, RAAS, TA-P, persistent hematuria, and TA-MAP were independent risk factors for combined events in IgAN patients with crescents.

Long-term renal survival and undetected risk factors of IgA nephropathy in Chinese children-a retrospective 1243 cases analysis from single centre experience

BACKGROUND

The long-term renal outcome for IgA nephropathy (IgAN) in large cohorts of children remains unclear. IgAN is a progressive disease, to explore novel biomarkers is necessary for predicting the disease activity and progression of IgAN. In addition, there is a hot debate on when to treat with immunosuppression in children. We aimed to confirm the long-term renal survival, find some undetected risk factors and investigate when to treat with immunosuppression can benefit for renal outcome in Chinese children.

METHODS

1243 Children with IgAN were enrolled and a follow-up of at least 1 year after a biopsy from 2000 to 2017. Long-term renal survival, undetected risk factors and the renal survival of immunosuppressive and non-immunosuppressive therapy were evaluated. The primary endpoint of the study was a combined outcome of either ≥50% reduction in estimated glomerular filtration rate (eGFR) or end-stage renal disease (ESRD) or death.

RESULTS

The median follow-up time were 86.8 months (interquartile range 54.7-140.2 months). The 5-, 10- and 15-year renal survival rates were 95.3%, 90.3% and 84%, respectively. Cox multivariate regression and Kaplan-Meier analysis showed that hypertension, hyperuricemia, high 24 h urine protein (24 h-UP) levels, lower initial eGFR, high urine C3 levels, high retinol-binding protein (RBP) levels, segmental glomerulosclerosis (S) and tubular atrophy and interstitial fibrosis (T) were associated with renal outcome. The statistically significant predictive perfect power for renal outcome was RBP ≥ 0.7µg/ml (AUC = 0.899, sensitivity = 84.00%, specificity = 86.00%), 24 h-UP ≥ 1 g/24 h (AUC = 0.722, sensitivity = 84.20%, specificity = 52.70%), eGFR < 60 ml/min/1.73 m² (AUC = 0.718, sensitivity = 81.30%, specificity = 39.20%) and S1 lesion (AUC = 0.703, sensitivity = 75.50%, specificity = 65.10%).Children with urinary RBP ≥ 0.7µg/ml were associated with a 2.513-fold risk than patients with urinary RBP < 0.7µg/ml (P = 0.003). Our study suggested that immunosuppressive therapy may reduce the risk of progression in IgAN children had both eGFR > 50 ml/min/1.73 m² and proteinuria of at least 1 g/day.

CONCLUSIONS

This is the first report that the 15-year renal survival rate of children with IgAN in China was 84%. At the same time, this is the first study to reveal that urinary RBP ≥ 0.7µg/ml may indicate a poor renal outcome. In addition, this study supports immunosuppressive therapy for IgAN children had both proteinuria ≥1 g/day and initial eGFR > 50 ml/min/1.73m².

Plasma fractalkine levels are associated with renal inflammation and outcomes in immunoglobulin A nephropathy

BACKGROUND

A recognized noninvasive biomarker to improve risk stratification of immunoglobulin A nephropathy (IgAN) patients is scarce. Fractalkine has been shown to play a key role in glomerular disease as chemoattractant, adhesion and even fibrosis factor. The current study assessed the possibility of plasma fractalkine as a novel biomarker in IgAN patients.

METHODS

Plasma fractalkine was measured in 229 patients with renal biopsy consistent IgAN from 2012 to 2014, and clinical, pathological and prognostic relationships were analyzed.

RESULTS

The plasma fractalkine levels in IgAN patients were significantly correlated with the creatinine level and 24-h urine protein by both univariate and multivariate analysis. Mesangial hypercellularity was still significantly correlated with the plasma fractalkine levels even after adjustment for other potential predictor variables by multivariate analysis. In addition, the counts of CD20+ B cells or CD68+ macrophage in renal biopsies of IgAN patients were significantly correlated with the plasma fractalkine levels, but not CD4+ and CD8+ T cells. Finally, we concluded that patients with higher plasma fractalkine levels had higher risk of poor renal outcome compared with those with lower plasma fractalkine levels. No association was observed between the CX3CR1 polymorphisms and clinical parameters including plasma fractalkine levels and prognosis. Recombinant fractalkine induced mesangial cells extracellular matrix synthesis and promoted the migration of microphage cells RAW264.7.

CONCLUSIONS

Plasma fractalkine levels were associated with creatinine level, 24-h urine protein, mesangial hypercellularity pathological damage, the CD68+ macrophage and CD20+ B cell infiltration in renal tissue and renal outcome in IgAN patients. Plasma fractalkine might be a potential prognosis novel predictor in Chinese patients with IgAN.

B4GALT1-congenital disorders of glycosylation: Expansion of the phenotypic and molecular spectrum and review of the literature

A congenital disorder of glycosylation due to biallelic mutations in B4GALT1 has been previously reported in only three patients with two different mutations. Through homozygosity mapping followed by segregation analysis in an extended pedigree, we identified three additional patients homozygous for a novel mutation in B4GALT1, expanding the phenotypic spectrum of the disease. The patients showed a uniform clinical presentation with intellectual disability, marked pancytopenia requiring chronic management, and novel features including pulmonary hypertension and nephrotic syndrome. Notably, affected individuals exhibited a moderate elevation of Man3GlcNAc4Fuc1 on serum N-glycan analysis, yet two of the patients had a normal pattern of transferrin glycosylation in repeated analysis. The novel mutation is the third disease-causing variant described in B4GALT1, and the first one within its transmembrane domain.

Identification and external validation of IgA nephropathy patients benefiting from immunosuppression therapy

BACKGROUND

Although IgA nephropathy (IgAN), an immune-mediated disease with heterogeneous clinical and pathological phenotypes, is the most common glomerulonephritis worldwide, it remains unclear which IgAN patients benefit from immunosuppression (IS) therapy.

METHODS

Clinical and pathological data from 4047 biopsy-proven IgAN patients from 24 renal centres in China were included. The derivation and validation cohorts were composed of 2058 and 1989 patients, respectively. Model-based recursive partitioning, a machine learning approach, was performed to partition patients in the derivation cohort into subgroups with different IS long-term benefits, associated with time to end-stage kidney disease, measured by adjusted Kaplan-Meier estimator and adjusted hazard ratio (HR) using Cox regression.

FINDINGS

Three identified subgroups obtained a significant IS benefits with HRs ≤ 1. In patients with serum creatinine ≤ 1·437 mg/dl, the benefits of IS were observed in those with proteinuria > 1·525 g/24h (node 6; HR = 0·50; 95% CI, 0·29 to 0·89; P = 0·02), especially in those with proteinuria > 2·480 g/24h (node 8; HR =  0·23; 95% CI, 0·11 to 0·50; P <0·001). In patients with serum creatinine > 1·437 mg/dl, those with high proteinuria and crescents benefitted from IS (node 12; HR = 0·29; 95% CI, 0·09 to 0·94; P = 0·04). The treatment benefits were externally validated in the validation cohort.

INTERPRETATION

Machine learning could be employed to identify subgroups with different IS benefits. These efforts promote decision-making, assist targeted clinical trial design, and shed light on individualised treatment in IgAN patients.

FUNDING

National Key Research and Development Program of China (2016YFC0904103), National Key Technology R&D Program (2015BAI12B02).

Prognostic value of the Oxford classification and the Oxford score in IgA nephropathy: A Tunisian study

Immunoglobulin A nephropathy is the most common primary glomerular disease. The main challenge in this disease is the evaluation of prognostic factors for end-stage renal disease. The aim of our study was to describe the characteristics of immunoglobulin A nephropathy, to evaluate the histological data according to Oxford classification, and to identify factors associated with renal survival. This was a retrospective study, including adults with primary immunoglobulin A nephropathy. The study was conducted over a period of 10 years. Renal biopsies were scored according to Oxford classification. Oxford score, based on the sum of the different histological lesions of Oxford classification, was calculated for each patient. We included 50 patients with a gender ratio (male:female) of 2.8. The average age was 35.6 ± 10.6 years. Fifty-eight percent of the patients had hypertension (HTN). The median proteinuria was 1.9 g/day. The median of the glomerular filtration rate was 47.6 mL/min/1.73 m². According to Oxford classification, mesangial proliferation, endocapillary proliferation, glomerulosclerosis, interstitial fibrosis, and/or tubular atrophy and crescents were present in 40%, 38%, 88%, 36%, and 22% of the cases, respectively. The median Oxford score was 2. The median follow-up duration was 30 months. Ten patients (20%) reached end-stage renal disease. At univariate analysis, HTN, glomerular filtration rate, proteinuria, tubular involvement, and Oxford score >3 were associated with progression to end-stage renal disease (ESRD). Tubular involvement was an independent risk factor for ESRD. Our study confirms the prognostic value of the Oxford classification in immunoglobulin A nephropathy.

Extracapillary proliferation scoring correlates with renal outcome and contributes to stratification in adult patients with immunoglobulin A nephropathy

Background

The revised Oxford classification of diagnostic renal biopsies has been proposed to aid in the prediction of renal outcome. We aimed to validate the histological crescents and interstitial fibrosis and tubular atrophy (IFTA) subgrouping, and to investigate the additional value of the proportion of crescents (CatPE) in the prediction of renal outcome.

Methods

Data were retrospectively collected over 10 years, from the time of diagnosis, by systematic review of medical records from 90 patients with renal biopsies recruited to cohorts from two hospitals in Spain. Patients were classified into three groups for the analysis: CatPE >25% (C2), CatPE <25% (C1) and without this type of lesion (C0). The end point was renal survival defined by either >50% reduction in glomerular filtrate rate or end-stage renal disease.

Results

Renal survival at 5 years was 90% in group C0, 81% in group C1 and 31% in group C2 (P = 0.013). The presence of >25% crescents in the sample was associated with more severe disease when compared with <25%, as demonstrated by more interstitial fibrotic change and by lower estimated glomerular filtration rate at diagnosis, as well as worse renal function at 2 and 5 years. At the time of diagnosis and at 24 months, the group with IFTA >50% had poorer renal function compared with the other groups.

Conclusions

We have confirmed the predictive value for renal survival of the revised Oxford classification in a two-centre study. We found worse renal outcome in patients with severe tubulointerstitial fibrosis and atrophy. Patients with extracapillary lesions >25% and IFTA >50% had a worse renal prognosis due to more severe kidney injury. These results contribute to patient stratification in immunoglobulin A nephropathy for therapeutic, epidemiological and basic research.