Natural history of primary IgA nephropathy

The transcription factor HMGB2 indirectly regulates APRIL expression and Gd-IgA1 production in patients with IgA nephropathy

BACKGROUND

IgA nephropathy (IgAN) is the most common primary glomerulonephritis worldwide. Proliferation-inducing ligand (APRIL) was identified as an important cause of glycosylation deficiency of IgA1 (Gd-IgA1), which can 'trigger' IgAN. Our previous study indicated that high migration group protein B2 (HMGB2) in peripheral blood mononuclear cells from patients with IgAN was associated with disease severity, but the underlying mechanism remains unclear.

MATERIALS AND METHODS

The location of HMGB2 was identified by immunofluorescence. qRT-PCR and Western blotting were used to measure HMGB2, HMGA1, and APRIL expression. Gd-IgA1 levels were detected by enzyme-linked immunosorbent assay (ELISA). In addition, we used DNA pull-down, protein profiling, and transcription factor prediction software to identify proteins bound to the promoter region of the APRIL gene. RNA interference and coimmunoprecipitation (Co-IP) were used to verify the relationships among HMGB2, high mobility group AT-hook protein 1 (HMGA1), and APRIL.

RESULTS

HMGB2 expression was greater in IgAN patients than in HCs and was positively associated with APRIL expression in B cells. DNA pull-down and protein profiling revealed that HMGB2 and HMGA1 bound to the promoter region of the APRIL gene. The expression levels of HMGA1, APRIL, and Gd-IgA1 were downregulated after HMGB2 knockdown. Co-IP indicated that HMGB2 binds to HMGA1. The Gd-IgA1 concentration in the supernatant was reduced after HMGA1 knockdown. HMGA1 binding sites were predicted in the promoter region of the APRIL gene.

CONCLUSION

HMGB2 expression is greater in IgAN patients than in healthy controls; it promotes APRIL expression by interacting with HMGA1, thereby inducing Gd-IgA1 overexpression and leading to IgAN.

Complement system is overactivated in patients with IgA nephropathy after COVID-19

IgA nephropathy (IgAN), which has been confirmed as a complement mediated autoimmune disease, is also one form of glomerulonephritis associated with COVID-19. Here, we aim to investigate the clinical and immunological characteristics of patients with IgAN after COVID-19. The level of plasma level of C5a (p < 0.001), soluble C5b-9 (p = 0.018), FHR5 (p < 0.001) were all significantly higher in Group CoV (33 patients with renal biopsy-proven IgAN experienced COVID-19) compared with Group non-CoV (44 patients with IgAN without COVID-19), respectively. Compared with Group non-CoV, the intensity of glomerular C4d (p = 0.017) and MAC deposition (p < 0.001) and Gd-IgA1 deposition (p = 0.005) were much stronger in Group CoV. Our finding revealed that for IgAN after COVID-19, mucosal immune responses to SARS-CoV-2 infection may result in the overactivation of systemic and renal local complement system, and increased glomerular deposition of Gd-IgA1, which may lead to renal dysfunction and promote renal progression in IgAN patients.

Genome-wide analysis of long noncoding RNAs as cis-acting regulators of transcription factor-encoding genes in IgA nephropathy

BACKGROUND

IgA nephropathy (IgAN) is the most common form of primary glomerulonephritis in the world, but the disease pathogenesis noncoding is yet to be elucidated. Previous studies have revealed regulatory functions for long noncoding RNA (lncRNA) in various diseases; however, the roles of lncRNA in IgAN and regulation of transcription factors (TFs) have been scarcely investigated.

METHODS

Renal tissue samples (n = 5) from patients with IgAN and control samples (n = 4) were collected and RNA sequencing (RNA-seq) was performed. Four software programs were employed for lncRNA prediction. GO (Gene Ontology)/KEGG (Kyoto Encyclopedia of Genes and Genomes) were employed for analysis of the identified differentially expressed genes (DEGs). A regulatory network model of DE lncRNA-TF-DEG was developed, and the levels of expression of key lncRNAs, TFs, and corresponding target genes were assessed using qRT-PCR and immunofluorescence.

RESULTS

The current study identified 674 upregulated and 1,011 downregulated DE mRNAs and 260 upregulated and 232 downregulated DE lncRNAs in IgAN samples compared with control samples. The upregulated DE mRNAs showed enrichment in cell adhesion and collagen glial fiber organization pathways. The DE lncRNAs-DE mRNAs showing co-expression are associated with transmembrane transport. A novel regulatory network model of lncRNA-TF-DEG has been developed. This study identified seven TFs that are cis-regulated by 6 DE lncRNAs, and show co-expression with 132 DEGs (correlation coefficient ≥ 0.8, P ≤ 0.01), generating 158 pairs that showed co-expression. The lncRNAs NQO1-DT and RP5-1057120.6 were found to be highly expressed in IgAN samples. The TFs vitamin D Receptor (VDR) and NFAT5, along with their target genes were also aberrantly expressed.

CONCLUSION

Key lncRNAs and TFs centrally associated with IgAN have been identified in this study. A regulatory network model of lncRNA-TF-mRNA was constructed. Further studies on the genes identified herewith could provide insight into the pathogenesis of IgAN.

Clinical Presentation, Pathological Spectrum, and Outcomes of Alcoholic Cirrhosis-Related Immunoglobulin A Nephropathy

Introduction

Immunoglobulin A nephropathy (IgAN) associated with cirrhosis is frequent but often overlooked because it is largely considered silent. Until now, little has been known about their presentation and outcomes.

Methods

We conducted a retrospective multicenter study on patients with kidney biopsy-proven cirrhosis-related IgAN (cirrhosis-IgAN), diagnosed between 2009 and 2022. We mixed them up with 83 primary IgAN (pIgAN) diagnosed during the same period, using a partitioning clustering approach, to determine common clinicopathological profiles.

Results

All the 46 patients with cirrhosis-IgAN had an excessive alcoholic consumption. Clinical presentation was severe with acute kidney injury (AKI) in 79%; alternative causes of AKI was found in 62% of cases. Three clinicopathological clusters were identified as follows: the first one represented chronic involvement, the second one could be assimilated to mild disease, and the third one corresponded to a membranoproliferative glomerulonephritis (MPGN) pattern and was associated with heavy proteinuria and intrinsic AKI (without alternative causes). Whereas the first 2 clusters were equally distributed between pIgAN and cirrhosis-IgAN, the third was more frequent in patients with cirrhosis. The cumulative mortality rate in cirrhosis-IgAN was 26% and 46% at 1-year and 3-years, respectively. Steroid exposure and moderate or severe AKI were associated with higher mortality and steroid exposure was associated with the occurrence of severe infection.

Conclusion

Our results suggest that high AKI incidence is related to extrinsic causes in most cases but can also be driven by IgA-dominant MPGN in a subset of patients. Steroid use was associated with infectious disease and mortality. Further studies are needed to clarify the role of immunosuppressive treatment in cirrhosis-IgAN patients.

Drugs in Development to Treat IgA Nephropathy

IgA nephropathy is a common glomerulonephritis consequent to the autoimmune response to aberrant glycosylated immunoglobulin (Ig) A antibodies. Although it has historically been considered a benign disease, it has since become clear that a substantial percentage of patients reach end-stage kidney failure over the years. Several therapeutic attempts have been proposed, with systemic steroids being the most prevalent, albeit burdened by possible serious adverse events. Thanks to the more in-depth knowledge of the pathogenesis of IgA nephropathy, new treatment targets have been identified and new drugs developed. In this narrative review, we summarise the molecules under clinical development for the treatment of IgA nephropathy. As a search strategy, we used PubMed, Google, ClinicalTrials.gov and abstracts from recent international congresses. TRF budesonide and sparsentan are the two molecules at a more advanced stage, just entering the market. Other promising agents are undergoing phase III clinical development. These include anti-APRIL and anti-BLyS/BAFF antibodies and some complement inhibitors. Other new possible strategies include spleen tyrosine kinase inhibitors, anti-CD40 ligands and anti-CD38 antibodies. In an era increasingly characterised by 'personalised medicine' and 'precision therapy' approaches and considering that the potential therapeutic armamentarium for IgA nephropathy will be very broad in the near future, the identification of biomarkers capable of helping the nephrologist to select the right drug for the right patient should be the focus of future studies.

C3 Hypocomplementemia Predicts the Progression of CKD towards End-Stage Kidney Disease in IgA Nephropathy, Irrespective of Histological Evidence of Thrombotic Microangiopathy

Background: IgA nephropathy (IgAN) is the most common primary glomerulonephritis worldwide. IgAN causes end-stage kidney disease (ESKD) in 30-40% of all cases. The activation of the complement system by pathological circulating IgAs, which is often associated with low serum C3 levels (LowC3), seems to play a crucial role. Previous studies have shown an association between histological evidence of TMA, which is the result of alternative complement activation, and poor outcomes. However, it is not known to what extent the decrease in serum C3 levels reflects ongoing TMA injury. Our study aimed at assessing the association between LowC3 and ESKD and whether this association reflects ongoing TMA. Methods: We enrolled all patients with biopsy-proven IgAN and followed-up patients until their last visit, ESKD, or death. Results: Of the 56 patients included in the study, 12 (21%) presented low serum C3 (LowC3) at the time of renal biopsy. TMA was significantly more frequent in the LowC3 group [7/12 (58%) vs. 9/44 (20%), p = 0.02]. After adjusting for potential confounders, LowC3 was strongly associated with an increased hazard of ESKD (hazard ratio [HR]: 5.84 [95%CI: 1.69, 20.15; p = 0.005). The association was not affected by adjusting for TMA. The estimated overall proportion of the relation between C3 and ESKD mediated by TMA was low and not statistically significant. Conclusions: Our study provides evidence that C3 hypocomplementemia is associated with an increased risk of ESKD through mechanisms that are largely independent from TMA.

Efficacy and safety of low-dose corticosteroids combined with leflunomide for progressive IgA nephropathy: a systematic review and meta-analysis

BACKGROUND AND OBJECTIVE

The effectiveness of immunosuppressive and corticosteroid treatments for Immunoglobulin A (IgA) nephropathy (IgAN) remains thoroughly evaluated. We undertook a meta-analysis to investigate the efficacy and safety of low-dose corticosteroids plus leflunomide for progressive IgA nephropathy.

METHODS

Eligible studies were obtained from PubMed, Embase, and Cochrane Library databases. We also searched the references of the included studies. Our protocol followed the preferred reporting items for systematic reviews and meta-analyses (PRISMA) checklist. Eligibility criteria were defined using a PICOS framework.

RESULTS

Our study included three articles presenting 342 patient cases. Findings revealed that low-dose corticosteroids combined with the leflunomide group were effective in relieving urine protein excretion (UPE) [mean difference (MD) = -0.35, 95% confidence interval (CI): -0.41 to -0.30, P < 0.00001] compared with the full-dose corticosteroids group. Regarding serum creatinine (SCr), estimated glomerular filtration rate (eGFR), complete remission rate, and overall response rate, there was no difference between the groups (p > 0.05). Regarding safety, low-dose corticosteroids combined with leflunomide significantly reduced the risk of serious adverse events [odds ratio (OR): 0.11, 95% CI: 0.01 to 0.91, P = 0.04]. Besides, no significant differences were observed between the two groups in the incidence of respiratory infection, abnormal liver function, diarrhea, herpes zoster, alopecia, pruritus, insomnia, pneumonia, diabetes, and urinary tract infection (P > 0.05).

CONCLUSIONS

Low-dose corticosteroids combined with leflunomide are a safe and effective treatment for progressive IgA nephropathy.

TRIAL REGISTRATION

The PROSPERO registration number is CRD42022361883.

Mortality in IgA Nephropathy: A Long-Term Follow-Up of an Eastern European Cohort

Background and Objectives: IgA nephropathy (IgAN), the most common primary glomerulonephritis, has been extensively studied for renal outcomes, with limited data on patient survival, particularly in Eastern Europe. We aimed to investigate the long-term survival rate of patients with IgAN and the associated risk factors in an Eastern European cohort. Materials and Methods: We conducted a retrospective analysis of 215 IgAN patients (median age 44, 71% male) diagnosed at a Romanian tertiary center between 2010 and 2017. We assessed clinical and pathological attributes, including the Charlson comorbidity index, the prevalence of diabetes, renal function, and treatment with renin-angiotensin-system inhibitors (RASIs). Results: Over a median 7.3-year follow-up, 20% of patients died, mostly due to cardiovascular diseases. Survival rates at 1, 5, and 10 years were 93%, 84%, and 77%, respectively. Deceased patients had higher Charlson comorbidity index scores, greater prevalence of diabetes, and poorer renal function. They were less frequently treated with RASIs and more frequently reached end-stage kidney disease (ESKD). Conclusions: We report a 20% mortality rate in our Eastern European IgAN cohort, primarily due to cardiovascular diseases. Death correlates with increased age, comorbidity burden, decreased renal function at diagnosis, and the absence of RASI use. RASI treatment may potentially improve survival, highlighting its importance in managing IgAN.

IgA Nephropathy: Beyond the Half-Century

In 1968, Jean Berger first introduced the medical world to IgA nephropathy (IgAN). Fifty-five years later, its pathogenesis is still unclear, but treatments such as renin-angiotensin-aldosterone system inhibitors (RAAS-Is), tonsillectomies, and glucocorticoids are currently used worldwide. There have been great strides in the past 20 years since the discoveries of the specific dysregulation of mucosal immunity, galactose-deficient IgA1 (Gd-IgA1), and Gd-IgA1 immune complexes in patients with IgAN. According to these findings, a multi-hit hypothesis was developed, and this multi-hit hypothesis has provided several putative therapeutic targets. A number of novel agents, including molecularly targeted drugs for targets such as APRIL, plasma cells, complement systems, and endothelin, are undergoing clinical trials. Some candidate drugs have been found to be effective, with minimal side effects. Over half a century after the discovery of IgAN, these therapies will soon be available for clinical use.

Circulating alternative pathway complement cleavage factor Bb is associated with vascular lesions and outcomes in IgA nephropathy

BACKGROUND

Complement alternative pathway (AP) activation is linked to immunoglobulin A nephropathy (IgAN) prognosis severity, but Bb fragment's role is unclear. We examined the relationship between serum Bb fragment concentration at IgAN diagnosis and disease activity and outcomes.

METHODS

This retrospective study included 125 biopsy-proven IgAN patients [age 39.9 years, 75% male, estimated glomerular filtration rate (eGFR) 82 ml/min, proteinuria 0.5 g/day] enrolled from 1984 to 2010 and followed for a minimum of 18 months. Monitoring continued until the last follow-up, end-stage kidney disease (ESKD) or death. Serum Bb fragment was measured using an enzyme-linked immunosorbent assay at diagnosis. Oxford classification and global optical score (GOS) were utilized for pathology assessment.

RESULTS

Patients were followed for a median of 16 years; 42% developed chronic kidney disease stage ≥3, 19% reached ESKD and 9% died. Serum Bb fragment concentration negatively correlated with eGFR values at the last follow-up and positively with vascular and tubular histopathological indices. In univariate Cox regression analyses, higher Bb fragment concentration was associated with ESKD alongside older age, increased body mass index, arterial hypertension, lower eGFR, higher proteinuria, E1, S1, T1-2, GOS and corticotherapy. Patients with Bb levels ≥14.3 μg/ml had shorter mean kidney survival time (19.5 versus 22.7 years, P = .07); after adjusting for progression risk factors, the association persisted [hazard ratio 4.76 (95% confidence interval 1.56-14.43)].

CONCLUSIONS

Serum Bb fragment concentration at diagnosis may predict long-term IgAN outcomes, potentially due to AP activation at the endothelial surface. Further research is needed to confirm these results and evaluate Bb fragment's role in IgAN management.

Current Understanding of Complement Proteins as Therapeutic Targets for the Treatment of Immunoglobulin A Nephropathy

Immunoglobulin A nephropathy (IgAN) is the most common primary glomerulonephritis worldwide and a frequent cause of kidney failure. Currently, the diagnosis necessitates a kidney biopsy, with routine immunofluorescence microscopy revealing IgA as the dominant or co-dominant immunoglobulin in the glomerular immuno-deposits, often with IgG and sometimes IgM or both. Complement protein C3 is observed in most cases. IgAN leads to kidney failure in 20-40% of patients within 20 years of diagnosis and reduces average life expectancy by about 10 years. There is increasing clinical, biochemical, and genetic evidence that the complement system plays a paramount role in the pathogenesis of IgAN. The presence of C3 in the kidney immuno-deposits differentiates the diagnosis of IgAN from subclinical glomerular mesangial IgA deposition. Markers of complement activation via the lectin and alternative pathways in kidney-biopsy specimens are associated with disease activity and are predictive of poor outcome. Levels of select complement proteins in the circulation have also been assessed in patients with IgAN and found to be of prognostic value. Ongoing genetic studies have identified at least 30 loci associated with IgAN. Genes within some of these loci encode complement-system regulating proteins that can interact with immune complexes. The growing appreciation for the central role of complement components in IgAN pathogenesis highlighted these pathways as potential treatment targets and sparked great interest in pharmacological agents targeting the complement cascade for the treatment of IgAN, as evidenced by the plethora of ongoing clinical trials.

Development of a novel combined nomogram model integrating deep learning radiomics to diagnose IgA nephropathy clinically

This study aimed to develop and validate a combined nomogram model based on superb microvascular imaging (SMI)-based deep learning (DL), radiomics characteristics, and clinical factors for noninvasive differentiation between immunoglobulin A nephropathy (IgAN) and non-IgAN.We prospectively enrolled patients with chronic kidney disease who underwent renal biopsy from May 2022 to December 2022 and performed an ultrasound and SMI the day before renal biopsy. The selected patients were randomly divided into training and testing cohorts in a 7:3 ratio. We extracted DL and radiometric features from the two-dimensional ultrasound and SMI images. A combined nomograph model was developed by combining the predictive probability of DL with clinical factors using multivariate logistic regression analysis. The proposed model's utility was evaluated using receiver operating characteristics, calibration, and decision curve analysis. In this study, 120 patients with primary glomerular disease were included, including 84 in the training and 36 in the test cohorts. In the testing cohort, the ROC of the radiomics model was 0.816 (95% CI:0.663-0.968), and the ROC of the DL model was 0.844 (95% CI:0.717-0.971). The nomogram model combined with independent clinical risk factors (IgA and hematuria) showed strong discrimination, with an ROC of 0.884 (95% CI:0.773-0.996) in the testing cohort. Decision curve analysis verified the clinical practicability of the combined nomogram. The combined nomogram model based on SMI can accurately and noninvasively distinguish IgAN from non-IgAN and help physicians make clearer patient treatment plans.

Validation of the international IgA nephropathy prediction tool in a French cohort beyond 10 years after diagnosis

INTRODUCTION

The International IgA Nephropathy Network developed a tool (IINN-PT) for predicting the risk of end-stage renal disease (ESRD) or a 50% decline in the estimated glomerular filtration rate (eGFR). We aimed to validate this tool in a French cohort with longer follow-up than previously published validation studies.

METHODS

The predicted survival of patients with biopsy-proven immunoglobulin A nephropathy (IgAN) from the Saint Etienne University Hospital cohort was computed with IINN-PT models with or without ethnicity. The primary outcome was the occurrence of either ESRD or a 50% decline in eGFR. The models' performances were evaluated through c-statistics, discrimination and calibration analysis.

RESULTS

There were 473 patients with biopsy-proven IgAN, with a median follow-up of 12.4 years. Models with and without ethnicity showed areas under the curve (95% confidence interval) of 0.817 (0.765; 0.869) and 0.833 (0.791; 0.875) and R2D of 0.28 and 0.29, respectively, and an excellent discrimination of groups of increasing predicted risk (P < .001). The calibration analysis was good for both models up to 15 years after diagnosis. The model without ethnicity exhibited a mathematical issue of survival function after 15 years.

DISCUSSION

The IINN-PT provided good performances even after 10 years post-biopsy as showed by our study based on a cohort with a longer follow-up than previous cohorts (12.4 versus <6 years). The model without ethnicity exhibited better performances up to 15 years but became aberrant beyond this point due to a mathematical issue affecting the survival function. Our study sheds light on the usefulness of integrating ethnicity as a covariable for prediction of IgAN course.

Clinicopathological Characteristics of Adult IgA Nephropathy in the United States

Introduction

IgA nephropathy (IgAN) is a progressive autoimmune kidney disease and a leading cause of glomerular disease that can result in kidney failure (KF). The median age at diagnosis is 35 to 37 years and approximately 50% of patients will progress to KF within 20 years. We aimed to enhance the understanding of renal histology and chronic kidney disease (CKD) stage at the time of IgAN diagnosis using a large real-world biopsy cohort.

Methods

This retrospective cohort study evaluated biopsy data and clinical characteristics from adult patients within the US who were diagnosed with IgAN between January 1, 2016 to May 31, 2020. Descriptive statistics were summarized and relationship(s) between each Oxford Classification (MEST-C) component score with 24-hour proteinuria or CKD stage were examined using regression analysis.

Results

A total of 4375 patients (mean age 47.7 years, 62.7% male) met eligibility criteria. Mild to moderate mesangial hypercellularity (47.3%), segmental sclerosis (65.0%), tubular atrophy ≥25% (57.4%), and crescents (18.5%) were identified; and 74.6% of patients were at CKD stage ≥3. Proteinuria ≥1 g/d was associated with higher MEST-C scores, and the odds of mesangial hypercellularity, segmental sclerosis, tubular atrophy, and crescents increased with CKD stage.

Conclusion

Most patients with IgAN in our US cohort were diagnosed at CKD stage ≥3 and had high MEST-C scores and proteinuria that are suggestive of significant disease burden at the time of kidney biopsy. Strategies are required to raise awareness and promote earlier detection of asymptomatic urinary abnormalities before extensive irreversible kidney damage has occurred.

Exploration of Artemisinin Against IgA Nephropathy via AKT/Nrf2 Pathway by Bioinformatics and Experimental Validation

Background

Artemisinin (ART) is a safe and effective antimalarial drug. In recent years, antimalarial drugs have demonstrated a good therapeutic efficacy in IgA nephropathy, suggesting that this may become a new treatment option.

Purpose

We aimed to evaluate the effect and mechanism of artemisinin in IgA nephropathy.

Methods

In this study, CMap database was used to predict the artemisinin therapeutic effect for IgA nephropathy. A network pharmacology approach was applied to explore the unknown mechanism of artemisinin in IgA nephropathy. We used molecular docking to predict the binding affinity of artemisinin with the targets. A mouse model of IgA nephropathy was established to investigate the therapeutic effect of artemisinin on IgA nephropathy. In vitro, the cell counting Kit-8 assay was used to evaluate the cytotoxicity of artemisinin. Flow cytometry and PCR assays were used to detect the effects of artemisinin on oxidative stress and fibrosis in lipopolysaccharide (LPS)-stimulated mesangial cells. Western blot and immunofluorescence were used to detect the expression of pathway proteins.

Results

CMap analysis showed artemisinin may reverse the expression levels of differentially expressed genes in IgA nephropathy. Eighty-seven potential targets of artemisinin in the treatment of IgA nephropathy were screened. Among them, 15 hub targets were identified. Enrichment analysis and GSEA analysis indicated that response to reactive oxygen species is the core biological process. AKT1 and EGFR had the highest docking affinity with artemisinin. In vivo, artemisinin could improve renal injury and fibrosis in mice. In vitro, artemisinin attenuated LPS-induced oxidative stress and fibrosis promoted AKT phosphorylation and Nrf2 nuclear translocation.

Conclusion

Artemisinin reduced the level of fibrosis and oxidative stress with IgA nephropathy through the AKT/Nrf2 pathway, which provided an alternative treatment for IgAN.

Targeting the Alternative Complement Pathway With Iptacopan to Treat IgA Nephropathy: Design and Rationale of the APPLAUSE-IgAN Study

Introduction

Targeting the alternative complement pathway (AP) is an attractive therapeutic strategy because of its role in immunoglobulin A nephropathy (IgAN) pathophysiology. Iptacopan (LNP023), a proximal complement inhibitor that specifically binds to factor B and inhibits the AP, reduced proteinuria and attenuated AP activation in a Phase 2 study of patients with IgAN, thereby supporting the rationale for its evaluation in a Phase 3 study.

Methods

APPLAUSE-IgAN (NCT04578834) is a multicenter, randomized, double-blind, placebo-controlled, parallel-group, Phase 3 study enrolling approximately 450 adult patients (aged ≥18 years) with biopsy-confirmed primary IgAN at high risk of progression to kidney failure despite optimal supportive treatment. Eligible patients receiving stable and maximally tolerated doses of angiotensin-converting enzyme inhibitors (ACEis) or angiotensin receptor blockers (ARBs) will be randomized 1:1 to either iptacopan 200 mg or placebo twice daily for a 24-month treatment period. A prespecified interim analysis (IA) will be performed when approximately 250 patients from the main study population complete the 9-month visit. The primary objective is to demonstrate superiority of iptacopan over placebo in reducing 24-hour urine protein-to-creatinine ratio (UPCR) at the IA and demonstrate the superiority of iptacopan over placebo in slowing the rate of estimated glomerular filtration rate (eGFR) decline (total eGFR slope) estimated over 24 months at study completion. The effect of iptacopan on patient-reported outcomes, safety, and tolerability will be evaluated as secondary outcomes.

Conclusions

APPLAUSE-IgAN will evaluate the benefits and safety of iptacopan, a novel targeted therapy for IgAN, in reducing complement-mediated kidney damage and thus slowing or preventing disease progression.

Clinicopathological Characteristics and Outcomes of Immunoglobulin A Nephropathy with Different Types of Dyslipidemia: A Retrospective Single-Center Study

INTRODUCTION

Immunoglobulin A nephropathy (IgAN) is one of the most common glomerulonephritic diseases in the world. Several lines of evidence have suggested that dyslipidemia is related to the disease progression and prognosis of IgAN. However, the study is scarce on the clinicopathological characteristics and outcomes of IgAN with dyslipidemia.

METHODS

This study retrospectively analyzed 234 patients with biopsy-proven idiopathic IgAN at the Department of Nephrology, Longhua Hospital, Shanghai University of Traditional Chinese Medicine, between January 2015 and June 2021. The participants were divided into dyslipidemia (n = 119) and non-dyslipidemia (n = 115), and the dyslipidemia group was also divided into the following 4 groups: hypertriglyceridemia group, hypercholesterolemia group, mixed hyperlipidemia group, and low high-density lipoprotein cholesterol group. The estimated glomerular filtration rate (eGFR) was estimated by the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation.

RESULTS

The prevalence of dyslipidemia in IgAN patients in our center was 50.9% (119/234). The patients with dyslipidemia presented with higher systolic blood pressure (BP), diastolic BP, serum creatinine, uric acid, hemoglobin, proteinuria, and eGFR (p < 0.05). Proportions of males, hypertension, and chronic kidney disease stage 2∼5 were also higher in the dyslipidemia group (p < 0.05). Similarly, the pathological characteristics performed were worse in the dyslipidemia group. Most dyslipidemia patients had a higher percentage of mesangial hypercellularity (M1) and tubular atrophy/interstitial fibrosis (T1∼2) in the Oxford Classification's scoring system (p < 0.05). Multivariate logistic regression analysis revealed that male gender (odds ratio [OR] = 2.397, 95% confidence interval [CI]: 1.051-5.469, p = 0.038) and proteinuria (OR = 1.000, 95% CI: 1.000-1.001, p = 0.035) were possible risk factors for dyslipidemia. A total of 13 patients (13.8%) in the dyslipidemia group had an endpoint event, of which 6 patients (6.4%) had a ≥50% decrease in eGFR from baseline and 7 patients (7.4%) reached the end-stage renal disease stage. Kaplan-Meier survival curve analysis showed that patients in the dyslipidemia group had a worse outcome than those in the non-dyslipidemia group (log-rank test, p = 0.048).

CONCLUSIONS

IgAN patients with dyslipidemia presented more severe clinicopathological characteristics. Male gender and proteinuria are significantly associated with the occurrence of dyslipidemia in IgAN patients. Patients in the dyslipidemia group had a worse prognosis than those in the non-dyslipidemia group, which may be essential for the disease management of IgAN and help identify the high-risk patients.

Corticosteroid Therapy in Immunoglobulin A Nephropathy: A Friend or Foe?

BACKGROUND

The administration of corticosteroids in addition to supportive care to delay progressive immunoglobulin A nephropathy (IgAN), the most common primary glomerulonephritis worldwide, remains controversial. This is partly due to the paucity of well-designed randomized controlled trials and well-known corticosteroid-related side effects. As a result, clinical equipoise in corticosteroid therapy exists depending on geographical regions and the clinician's preference.

SUMMARY

Better understanding around the pathogenesis of IgAN has prompted several clinical trials exploring the effects of immunosuppressive agents including corticosteroids. Earlier studies of corticosteroids were limited by suboptimal study designs, inadequate implementation of standard of care, and inconsistent adverse event data collection. Two well-designed, adequately powered, multi-centre randomized controlled trials, the STOP-IgAN and TESTING studies, have reported contrasting kidney outcomes that have further fuelled the clinical conundrum regarding the efficacy of corticosteroids. Both studies independently reported greater adverse events with corticosteroids. A novel targeted release formulation of budesonide, which has been hypothesized to reduce the adverse events associated with systemic corticosteroids, has shown promising results in the Phase 3 NefigaRD trial. Studies of treatments targeting B cells and the complement cascade are currently underway, and early data appear encouraging. This review provides an overview of the current literature around the understanding of the pathomechanisms and benefits and harm of corticosteroid use in IgAN.

KEY MESSAGES

Recent evidence suggests the use of corticosteroids in a selected cohort of people with IgAN at high risk of disease progression can improve kidney outcomes but comes with an associated risk of treatment-related adverse events, particularly with higher doses. Management decisions should therefore follow an informed patient-clinician discussion.

Characterization of patients with IgA nephropathy with and without associated minimal change disease

Introduction

Immunoglobulin A nephropathy (IgAN) presents various clinical manifestations and pathological phenotypes. Approximately 5% of patients with IgAN present with early onset nephrotic syndrome, mild mesangial lesions, and diffuse foot process effacement of podocytes, which resemble minimal change disease (MCD). These patients are defined as MCD-IgAN. Whether MCD-IgAN is a special type of IgAN or simply MCD accompanied by IgA deposition remains controversial.

Methods

A total of 51 patients diagnosed with MCD-IgAN at Beijing Anzhen Hospital from January 2010 to September 2022 were recruited. The clinical and pathological characteristics of IgA-MCD were analyzed. Patients with IgAN but without MCD (non-MCD-IgAN) and healthy participants were enrolled as controls. Galactose-deficient immunoglobulin A1 (Gd-IgA1) and complement C3 were detected both in the circulation and in renal tissues.

Results

We found that the levels of serum Gd-IgA1 were lower in participants with MCD-IgAN than in those with non-MCD-IgAN, but higher than in healthy participants. Gd-IgA1 was rarely deposited in the glomeruli of participants with MCD-IgAN, with a positive rate of only 13.7% (7/51); in contrast, the positive rate in participants with non-MCD-IgAN was 82.4% (42/51). Among renal Gd-IgA1-positive patients, Gd-IgA1 and immunoglobulin A (IgA) colocalized along the glomerular mesangial and capillary areas. Interestingly, we found that the circulating levels of complement C3 were significantly higher in participants with MCD-IgAN than in participants with non-MCD-IgAN. In addition, the intensity of C3c in glomeruli in participants with MCD-IgAN was significantly weaker than in participants with non-MCD-IgAN.

Conclusions

Our study suggests that, in MCD-IgAN, most of the IgA that is deposited on glomeruli is not the same pathogenic Gd-IgA1 as found in general IgAN. Complement activation both in the circulation and in the renal locality was much weaker in MCD-IgAN than in non-MCD-IgAN. Our study suggests that IgAN with MCD might be MCD with coincidental IgA deposition.

Glomerular Galactose-Deficient IgA1(KM55) Positive May Predict Poorer Prognosis in Coexisting Primary Membranous Nephropathy and IgA Nephropathy Patients

Primary membrane nephropathy (PMN) and IgA nephropathy (IgAN) are the most common glomerular diseases in China. Because of different pathogenesis, prognosis is significantly different. When the two diseases coexist (PMN/IgAN), the clinicopathological manifestations and prognosis remain unclear. In the present study, we analyzed the clinicopathological characteristics of PMN/IgAN patients, with only IgA deposition (PMN/IgA deposition) patients as controls. Galactose-deficient IgA1(KM55) and M-type Phospholipase A2 Receptor(PLA2R), both in circulation and renal tissues, were detected. Furthermore, prognosis of PMN/IgAN was explored. We found that PMN/IgAN also had some clinical features of IgAN in addition to PMN, such as higher serum albumin, along with a similar heavy proteinuria and lower titers of serum anti-PLA2R antibody. The positive rate of glomerular KM55 in PMN/IgAN was 23.5% (20/85), and 0% (0/29) in PMN/IgA deposition. Among those glomerular KM55 positive patients, KM55 and IgA colocalized mainly along the glomerular mesangial and capillary areas. Unfortunately, there was no significant difference in serum level of Gd-IgA1 between KM55+ and KM55- subgroups in PMN/IgAN patients, similar to the PMN/IgA deposition group. Notably, glomerular KM55 positive may predict a poorer prognosis in PMN/IgAN patients. In conclusion, our study suggested that, when glomerular KM55 staining was positive, this special coexisting PMN/IgAN disorder was prone to have more characteristics of IgAN besides PMN, and may predict poorer prognosis, while the mechanism requires further investigation.

Particulate matter of air pollution may increase risk of kidney failure in IgA nephropathy

IgA nephropathy (IgAN) is characterized by deposition of galactose-deficient IgA1 (Gd-IgA1) in glomerular mesangium associated with mucosal immune disorders. Since environmental pollution has been associated with the progression of chronic kidney disease in the general population, we specifically investigated the influence of exposure to fine particulate matter less than 2.5 μm in diameter (PM2.5) on IgAN progression. Patients with biopsy-proven primary IgAN were recruited from seven Chinese kidney centers. PM2.5 exposure from 1998 to 2016 was derived from satellite aerosol optical depth data and a total of 1,979 patients with IgAN, including 994 males were enrolled. The PM2.5 exposure levels for patients from different provinces varied but, in general, the PM2.5 exposure levels among patients from the north were higher than those among patients from the south. The severity of PM2.5 exposure in different regions was correlated with regional kidney failure burden. In addition, each 10 μg/m³ increase in annual average concentration of PM2.5 exposure before study entry (Hazard Ratio, 1.14; 95% confidence interval, 1.06-1.22) or time-varying PM2.5 exposure after study entry (1.10; 1.01-1.18) were associated with increased kidney failure risk after adjustment for age, gender, estimated glomerular filtration rate, urine protein, uric acid, hemoglobin, mean arterial pressure, Oxford classification, glucocorticoid and renin-angiotensin system blocker therapy. The associations were robust when the time period, risk factors of cardiovascular diseases or city size were further adjusted on the basis of the above model. Thus, our results suggest that PM2.5 is an independent risk factor for kidney failure in patients with IgAN, but these findings will require validation in more diverse populations and other geographic regions.

Rapidly progressive IgA nephropathy: clinicopathological characteristics and outcomes assessed according to the revised definition of the KDIGO 2021 Guideline

BACKGROUND

Rapidly progressive immunoglobulin A nephropathy (RPIgAN) is a severe clinical phenotype of IgAN associated with a poor outcome. The recently published Kidney Disease: Improving Global Outcomes (KDIGO) 2021 Guideline for the Management of Glomerular Diseases has proposed a new definition for RPIgAN that is based simply on a ≥50% decline in the estimated glomerular filtration rate (eGFR) over ≤3 months.

METHODS

In 1677 IgAN patients followed at a single centre in China, we evaluated the utility of this new definition to identify the highest-risk IgAN patients who might be suitable for combination immunosuppressive therapy.

RESULTS

The proportion of a ≥50% decline in eGFR over ≤3 months was 5.2%. The majority of these patients had reversible causes, with only 2.3% (39/1677) meeting the KDIGO 2021 criteria for RPIgAN. These patients had a significantly higher risk for end-stage kidney disease (ESKD) than non-RPIgAN patients (logrank P < 0.001). RPIgAN was an independent risk factor for ESKD [hazard ratio 3.99 (95% confidence interval 2.25-7.09); P <0.001]. A minority of the RPIgAN patients (25.6%) had ≥50% crescents. There was no significant difference in the risk for ESKD between patients in the RPIgAN group with ≥50% crescents and ˂50% crescents (logrank P = 0.27). Patients with RPIgAN and ≥50% crescents had a higher risk for ESKD than patients with non-RPIgAN and ≥50% crescents (logrank P = 0.04).

CONCLUSIONS

These data support the validity of the KDIGO 2021 definition but require independent validation in other non-Chinese cohorts.

High value of early secretory antigenic target-6 and culture filtrate protein-10 in diagnosis of IgA nephropathy with renal tuberculosis: a retrospective study

BACKGROUND

This retrospective study aimed to evaluate the diagnostic value of early secretory antigenic target-6 (ESAT-6) and culture filtrate protein-10 (CFP-10) in immunoglobulin A nephropathy (IgAN) associated with renal tuberculosis (RT).

METHODS

Forty patients with IgAN (IgAN group), 32 patients with RT (RT group), and 52 patients with IgAN associated with RT (IgAN + RT group) were retrospectively selected for this study. A tuberculin skin test (TST) was conducted, and Mycobacterium tuberculosis (MTB) antibody levels were measured. Immunohistochemistry and western blotting were used to determine the expression of ESAT-6 and CFP-10 proteins in renal tissues.

RESULTS

The positive results of TST and levels of serum and urinary MTB antibodies were higher in the RT group than in the IgAN + RT group. The expression levels of ESAT-6 and CFP-10 proteins were the highest in the IgAN + RT group and lowest in the IgAN group. The receiver operating characteristic curves indicated that the area under curve (AUC) value of the ESAT-6 protein for the diagnosis of IgAN associated with RT was 0.907 and the cut-off value of the integral optical density (IOD) was 26.72. Diagnosis based on ESAT-6 protein levels showed 75% sensitivity and 94.2% specificity. The AUC value of the CFP-10 protein for the diagnosis of IgAN associated with RT was 0.8 and the cut-off value of IOD was 25.67. Detection based on CFP-10 protein levels showed 63.9% sensitivity and 84.6% specificity.

CONCLUSIONS

Our study provides evidence for the potential of ESAT-6 and CFP-10 proteins as candidate markers in the diagnosis of IgAN associated with RT.

Remission of Proteinuria in a Patient Affected by Crescentic IgA Nephropathy with Rapidly Progressive Glomerulonephritis Treated by Sodium-Glucose Cotransporter-2 Inhibitors: Casual or Causal Relationship?

Crescentic IgA nephropathy (IgAN) with rapidly progressive glomerulonephritis (RPGN) is often associated with rapidly declining kidney function. Up to this date, specific therapy for crescentic IgAN is still unknown. Accumulating evidence suggests that sodium-glucose co-transporter-2 inhibitors (SGLT-2i) may have a role in standard therapy of glomerular diseases. However, it is unclear at what point in the natural history of specific glomerular diseases SGLT-2i can be beneficial. We report the clinical and histological features of a patient with crescentic IgAN that presented as an RPGN, who received intensive immunosuppression and renal replacement therapeutic (RRT). At the third month, the patient presented with significant improvement in his kidney function. At that point, we decided to start dapagliflozin in addition to his renin-angiotensin system (RAS) blocker, basing our decision on its proven renal benefits such as slowing the rate of decline in kidney function and reducing albuminuria. At the eighth month, the patient’s renal function gradually improved from serum Cr of 6.07 to 2.1 mg/dL; and urine albumin to creatinine ratio (UACR) declined from 5655 mg/g to 200 mg/g. The use of SGLT-2i in primary and secondary nondiabetic glomerular disease appears promising. It is crucial and necessary to accumulate more evidence for a more complete understanding of the mechanisms of the actions of SGLT-2i in non-diabetic glomerular disease.

Prognostic value of chronicity grading on renal outcomes in patients with IgA nephropathy

Many studies have shown that chronic changes are strong predictors of renal outcomes in various kidney diseases, including IgA nephropathy. The Mayo Clinic/Renal Pathology Society suggested a glomerulonephritis reporting system with a proposal for standardized grading of chronic changes. The purpose of this study was to predict renal outcomes in patients with IgA nephropathy using chronicity grading in comparison to the Oxford classification which did not include global sclerosis. A total of 4,151 patients with IgA nephropathy were enrolled from the Korean GlomeruloNephritis Study Group registry. Chronicity grading was categorized into minimal, mild, moderate, and severe according to the extent of chronic changes. The Oxford T and S scores were considered as chronic lesions. Three prediction models were constructed: the Oxford classification model (Oxford S plus T), chronicity grading model A (chronicity grading), and chronicity grading model B (chronicity grading plus Oxford S). Using these three prediction models, the primary renal outcome (end-stage renal disease) was evaluated using Cox regression analysis and prediction performance. During the median follow-up of 6.1 (2.7–9.9) years, 304 (7.3%) patients progressed to end-stage renal disease with a cumulative incidence rate of 1.02 events per 100 person-years. In a fully adjusted multivariable model, chronicity grading was independently associated with the primary renal outcome in both models A and B. Compared to the Oxford model, both models A and B showed improvements in model fit, but not in discrimination (ΔC 0.001; 95% CI, −0.010 to 0.013 and ΔC 0.002; 95% CI, −0.005 to 0.008, respectively). Model B demonstrated improvements in integrated discrimination improvement (0.01; 95% CI, 0–0.03) and continuous net reclassification improvement (0.49; 95% CI, 0.02–0.72). The severity of chronicity grading is closely related to adverse renal outcomes in patients with IgA nephropathy, and chronicity grading could provide additional information in clinical practice alongside the Oxford classification.

Overactivation of the complement system may be involved in intrarenal arteriolar lesions in IgA nephropathy

Introduction

IgA nephropathy (IgAN) encompasses a wide range of clinical and histology features. Some patients present without hematuria, with or without hypertension, still rapidly progress in renal function. Renal pathology of this part of patients were predominant intrarenal arteriolar lesions, rarely presented glomerular proliferative lesions. We aim to investigate the clinical and pathological characteristics and prognosis of these IgAN patients and initially explore whether the abnormal activation of complement is involved in the intrarenal arteriolar lesions of IgAN.

Methods

A total of 866 patients with renal biopsy-proven IgAN diagnosed at Beijing Anzhen Hospital were recruited. IgAN patients without intrarenal arteriolar lesions and proliferative lesions were excluded (n = 115), the rest were divided into arteriolar lesions group (n = 202) and proliferative lesions group (n = 549). Among them, 255 patients were regularly followed up for at least 1 year. Renal biopsy tissues of 104 IgAN patients were stained for complement components by immunohistochemistry and immunofluorescence.

Results

Compared with proliferative lesions group, the arteriolar lesions group experienced high percentage of hypertension (p = 0.004), low percentage of gross hematuria (p = 0.001), microscopic hematuria (p < 0.001) and less initial proteinuria (p = 0.033). Renal survival between the two groups was not significantly different (p = 0.133). MBL, C4d, FH and FHR5, C3c, and MAC deposited on intrarenal arteriole in arteriolar lesions group. Compare with the proliferative lesion group, the arteriolar lesions group exhibited a higher intensity of C3c deposition on the intrarenal arterioles (p = 0.048). C3c and CD31 co-deposited on intrarenal arterioles area in patients with intrarenal arteriolar lesions.

Conclusion

Renal survival of the IgAN patients in arteriolar lesions group was not better than those in proliferative lesions group. Abnormal activation of complement may be involved in the pathogenesis of arteriolar damage through the injury of endothelial cells in this clinical phenotype of IgAN.

How to take advantage of easily available biomarkers in patients with IgA nephropathy: IgA and C3 in serum and kidney biopsies

IgA nephropathy (IgAN) is the most common glomerulonephritis worldwide. It is diagnosed based on clinical and histological features including predominant IgA deposits in kidney biopsy. The multi-hit theory, based on the production of GDIgA1 and anti-GDIgA1 antibodies, and complement activation via alternative and lectin pathways and also a genetic tendency are crucial in the pathogenesis of IgAN. The aim of the present review is to summarize the utility of routine diagnostic tests in IgA nephropathy, such as IgA and C3 in serum and kidney biopsy specimens, for predicting the disease progression. The paper also contains data on new markers used in the diagnosis and prognosis of IgA nephropathy.

Clinical and histopathological analyses of kidney biopsies in a single center for 7 years

Kidney biopsy is the most important tool for diagnosing kidney disease and can be helpful in determining treatment and prognosis. Pathological spectra vary by country, region, race, sex, and age. We are the first to investigate the pathological spectrum of biopsy-proven kidney disease in Gyeongnam province of South Korea. We retrospectively analyzed 631 patients who underwent a kidney biopsy between 2013 and 2019 at Gyeongsang National University Hospital. The mean age of the 631 patients was 51.5 ± 18.1 years, and 361 patients (57.2%) were male. The mean estimated glomerular filtration rate by serum creatinine (Chronic Kidney Disease Epidemiology Collaboration [CKD-EPI]) was 68.0 ± 45.7 mL/min/1.73 m2. The mean systolic blood pressure was higher in 2017, 2018, and 2019 than in 2013 (P = .002). Hypertension (47.4%) was the most common comorbid disease, followed by diabetes (18.2%) and dyslipidemia (10.9%). Common clinical syndromes at the time of biopsy were renal insufficiency (42.0%) and nephrotic syndrome (33.9%). The prevalence of primary and secondary glomerular disease and tubulointerstitial disease were 71.4%, 16.9%, and 5.4%, respectively. Immunoglobulin A nephropathy was the most common primary glomerular disease (34.9%). Diabetic nephropathy was the most common secondary glomerular disease, followed by lupus nephritis. Tubulointerstitial disease was underestimated, as in other reports. Our data can be a useful reference for diagnosing kidney disease and understanding the patients in our province.

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

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

Cytokines and Production of Aberrantly O-Glycosylated IgA1, the Main Autoantigen in IgA Nephropathy

Immunoglobulin A (IgA) nephropathy is the most common primary glomerulonephritis worldwide, with no disease-specific treatment and up to 40% of patients progressing to kidney failure. IgA nephropathy (IgAN), characterized by IgA1-containing immunodeposits in the glomeruli, is considered to be an autoimmune disease in which the kidneys are injured as innocent bystanders. Glomerular immunodeposits are thought to originate from the circulating immune complexes that contain aberrantly O-glycosylated IgA1, the main autoantigen in IgAN, bound by IgG autoantibodies. A common clinical manifestation associated with IgAN includes synpharyngitic hematuria at disease onset or during disease activity. This observation suggests a connection of disease pathogenesis with an activated mucosal immune system of the upper-respiratory and/or gastrointestinal tract and IgA1 glycosylation. In fact, some cytokines can enhance production of aberrantly O-glycosylated IgA1. This process involves abnormal cytokine signaling in IgA1-producing cells from patients with IgAN. In this article, we present our view of pathogenesis of IgAN and review how some cytokines can contribute to the disease process by enhancing production of aberrantly glycosylated IgA1. We also review current clinical trials of IgAN based on cytokine-targeting therapeutic approaches.

ICAM-1 related long noncoding RNA is associated with progression of IgA nephropathy and fibrotic changes in proximal tubular cells

Intercellular adhesion molecule 1 (ICAM-1) related long noncoding RNA (ICR) is on the antisense strand of ICAM-1 and regulates ICAM-1 expression. ICAM-1 is involved in renal tubulointerstitial injury; however, the expression and clinical implication of ICR are not determined in IgA nephropathy (IgAN). We compared renal ICR levels in 337 IgAN patients with those of 89 biopsy controls, and a markedly increased ICR level was observed in IgAN patients. By Cox proportional hazards models, higher levels of renal ICR were independently associated with disease progression event defined as end-stage renal disease or ≥ 40% decline in estimated glomerular filtration rate. Patients in the highest tertile of renal ICR had a 3.5-fold higher risk for disease progression compared with those in the lowest tertile. The addition of renal ICR to a model with traditional risk factors improved risk prediction of disease progression (net reclassification index: 0.31 [95% CI 0.01–0.50]; integrated discrimination index: 0.10 [95% CI 0.04–0.16]). Inhibition of ICR by transfection with plasmids containing ICR shRNA significantly reduced expression of collagen I and α-SMA, and phosphorylation of Akt and mTOR in TGF-β1- treated HK-2 cells. Our findings suggest that renal ICR might be an independent predictor of IgAN progression and contribute to renal fibrosis.

Renal Megalin mRNA Downregulation Is Associated with CKD Progression in IgA Nephropathy

INTRODUCTION

Megalin plays an important role in proximal tubule uptake of filtered proteins. Downregulation and dysfunction of megalin were previously demonstrated in IgA nephropathy (IgAN); however, its relationship to IgAN progression remains unclear.

METHODS

We measured renal megalin mRNA and miR-148b, previously identified as a regulator of megalin, in a retrospective cohort of 417 IgAN patients at the time of biopsy, and evaluated their associations with chronic kidney disease (CKD) progression event, defined as end-stage renal disease or ≥40% decline in estimated glomerular filtration rate, using Cox proportional hazard models. Risk classification statistics were calculated for CKD progression.

RESULTS

During a median follow-up of 43 months, 121 (29.0%) patients reached the CKD progression event. Patients in the highest tertile of renal megalin mRNA had a lower risk for CKD progression than in the lowest tertile (hazard ratio (HR): 0.407, 95% confidence interval (CI) 0.231-0.719; p = 0.002). Log megalin mRNA was independent and negatively associated with CKD progression in IgAN (HR: 0.529, 95% CI 0.377-0.742; p < 0.001). The addition of renal megalin mRNA to a model with traditional risk factors improved risk prediction of disease progression (C statistic from 0.76 to 0.80; integrated discrimination index: 0.04 [95% CI: 0.02-0.07]). Moreover, patients in the highest tertile of renal miR-148b had a 2.3-fold higher risk for CKD progression compared with those in the lowest tertile.

CONCLUSIONS

Lower renal megalin mRNA levels were associated with a greater risk of CKD progression in IgAN independent of clinical and pathological characteristics, suggesting that renal megalin could be an important prognostic factor for IgAN.

A noninvasive artificial neural network model to predict IgA nephropathy risk in Chinese population

Renal biopsy is the gold standard for Immunoglobulin A nephropathy (IgAN) but poses several problems. Thus, we aimed to establish a noninvasive model for predicting the risk probability of IgAN by analyzing routine and serological parameters. A total of 519 biopsy-diagnosed IgAN and 211 non-IgAN patients were recruited retrospectively. Artificial neural networks and logistic modeling were used. The receiver operating characteristic (ROC) curve and performance characteristics were determined to compare the diagnostic value between the two models. The training and validation sets did not differ significantly in terms of any variables. There were 19 significantly different parameters between the IgAN and non-IgAN groups. After multivariable logistic regression analysis, age, serum albumin, serum IgA, serum immunoglobulin G, estimated glomerular filtration rate, serum IgA/C3 ratio, and hematuria were found to be independently associated with the presence of IgAN. A backpropagation network model based on the above parameters was constructed and applied to the validation cohorts, revealing a sensitivity of 82.68% and a specificity of 84.78%. The area under the ROC curve for this model was higher than that for logistic regression model (0.881 vs. 0.839). The artificial neural network model based on routine markers can be a valuable noninvasive tool for predicting IgAN in screening practice.

External validation of the International Prediction Tool in Korean patients with immunoglobulin A nephropathy

Background

The International IgA Nephropathy Prediction Tool (International IgA Nephropathy Prediction Tool) has been recently developed to estimate the progression risk of immunoglobulin A nephropathy (IgAN). This study aimed to evaluate the clinical performance of this prediction tool in a large IgAN cohort in Korea.

Methods

The study cohort was comprised of 2,064 patients with biopsy-proven IgAN from four medical centers between March 2012 and September 2021. We calculated the predicted risk for each patient. The primary outcome was occurrence of a 50% decline in estimated glomerular filtration rate (eGFR) from the time of biopsy or end-stage kidney disease. The model performance was evaluated for discrimination, calibration, and reclassification. We also constructed and tested an additional model with a new coefficient for the Korean race.

Results

During a median follow-up period of 3.8 years (interquartile range, 1.8–6.6 years), 363 patients developed the primary outcome. The two prediction models exhibited good discrimination power, with a C-statistic of 0.81. The two models generally underestimated the risk of the primary outcome, with lesser underestimation for the model with race. The model with race showed better performance in reclassification compared to the model without race (net reclassification index, 0.13). The updated model with the Korean coefficient showed good agreement between predicted risk and observed outcome.

Conclusion

In Korean IgAN patients, International IgA Nephropathy Prediction Tool had good discrimination power but underestimated the risk of progression. The updated model with the Korean coefficient showed acceptable calibration and warrants external validation.

The Role of Complement in Microangiopathic Lesions of IgA Nephropathy

Introduction

Methods

Results

Conclusion

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.

Noninvasive assessment of clinical and pathological characteristics of patients with IgA nephropathy by diffusion kurtosis imaging

Objectives

To explore the diagnostic performance of diffusion kurtosis imaging (DKI) in evaluating the clinical and pathological characteristics of patients with immunoglobulin A nephropathy (IgAN) compared with conventional DWI.

Materials and methods

A total of 28 IgAN patients and 14 healthy volunteers prospectively underwent MRI examinations including coronal T2WI, axial T1WI, T2WI, and DWI sequences from September 2020 to August 2021. We measured mean kurtosis (MK), mean diffusivity (MD), and apparent diffusion coefficient (ADC) by using MR Body Diffusion Toolbox v1.4.0 (Siemens Healthcare). Patients were divided into three groups according to their estimated glomerular filtration rate (eGFR) (Group1, healthy volunteers without kidney disease or other diseases that affect renal function; Group2, IgAN patients with eGFR > 60 mL/min/1.73 m²; Group3, IgAN patients with eGFR < 60 mL/min/1.73 m²). One-way analysis of variance, Pearson or Spearman correlation, and receiver operating characteristic curves were applied in our statistical analysis.

Results

MK_Cortex and ADC_Cortex showed significant differences between the Group1 and Group2. MK_Cortex, MD_Cortex, ADC_Cortex, MK_Medulla, and ADC_Medulla showed significant differences between Group2 and Group3. MK_Cortex had the highest correlation with CKD stages (r = 0.749, p < 0.001), and tubulointerstitial lesion score (r = 0.656, p < 0.001). MD_Cortex had the highest correlation with glomerular lesion score (r = − 0.475, p = 0.011). MK_Cortex had the highest AUC (AUC = 0.923) for differentiating Group1 from Group2, and MD_Cortex had the highest AUC (AUC = 0.924) for differentiating Group2 from Group3, followed by MK_Medulla (AUC = 0.923).

Conclusions

DKI is a feasible and reliable technique that can assess the clinical and pathological characteristics of IgAN patients and can provide more valuable information than conventional DWI, especially MK_Cortex.

A Validation Study Comparing Risk Prediction Models of IgA Nephropathy

We aimed to validate three IgAN risk models proposed by an international collaborative study and another CKD risk model generated by an extended CKD cohort with our multicenter Chinese IgAN cohort. Biopsy-proven IgAN patients with an eGFR ≥15 ml/min/1.73 m² at baseline and a minimum follow-up of 6 months were enrolled. The primary outcomes were a composite outcome (50% decline in eGFR or ESRD) and ESRD. The performance of those models was assessed using discrimination, calibration, and reclassification. A total of 2,300 eligible cases were enrolled. Of them, 288 (12.5%) patients reached composite outcome and 214 (9.3%) patients reached ESRD during a median follow-up period of 30 months. Using the composite outcome for analysis, the Clinical, Limited, Full, and CKD models had relatively good performance with similar C statistics (0.81, 0.81, 0.82, and 0.82, respectively). While using ESRD as the end point, the four prediction models had better performance (all C statistics > 0.9). Furthermore, subgroup analysis showed that the models containing clinical and pathological variables (Full model and Limited model) had better discriminatory abilities than the models including only clinical indicators (Clinical model and CKD model) in low-risk patients characterized by higher baseline eGFR (≥60 ml/min/1.73 m²). In conclusion, we validated recently reported IgAN and CKD risk models in our Chinese IgAN cohort. Compared to pure clinical models, adding pathological variables will increase performance in predicting ESRD in low-risk IgAN patients with baseline eGFR ≥60 ml/min/1.73 m².

O- and N-Glycosylation of Serum Immunoglobulin A is Associated with IgA Nephropathy and Glomerular Function

BACKGROUND

IgA nephropathy (IgAN) is the most common primary glomerular disease worldwide and is a leading cause of renal failure. The disease mechanisms are not completely understood, but a higher abundance of galactose-deficient IgA is recognized to play a crucial role in IgAN pathogenesis. Although both types of human IgA (IgA1 and IgA2) have several N-glycans as post-translational modification, only IgA1 features extensive hinge-region O-glycosylation. IgA1 galactose deficiency on the O-glycans is commonly detected by a lectin-based method. To date, limited detail is known about IgA O- and N-glycosylation in IgAN.

METHODS

To gain insights into the complex O- and N-glycosylation of serum IgA1 and IgA2 in IgAN, we used liquid chromatography-mass spectrometry (LC-MS) for the analysis of tryptic glycopeptides of serum IgA from 83 patients with IgAN and 244 age- and sex-matched healthy controls.

RESULTS

Multiple structural features of N-glycosylation of IgA1 and IgA2 were associated with IgAN and glomerular function in our cross-sectional study. These features included differences in galactosylation, sialylation, bisection, fucosylation, and N-glycan complexity. Moreover, IgA1 O-glycan sialylation was associated with both the disease and glomerular function. Finally, glycopeptides were a better predictor of IgAN and glomerular function than galactose-deficient IgA1 levels measured by lectin-based ELISA.

CONCLUSIONS

Our high-resolution data suggest that IgA O- and N-glycopeptides are promising targets for future investigations on the pathophysiology of IgAN and as potential noninvasive biomarkers for disease prediction and deteriorating kidney function.

The Role of Complement Component C3 Activation in the Clinical Presentation and Prognosis of IgA Nephropathy-A National Study in Children

The aim of the study was to evaluate the influence of the intensity of mesangial C3 deposits in kidney biopsy and the serum C3 level on the clinical course and outcomes of IgAN in children. The study included 148 children from the Polish Pediatric IgAN Registry, diagnosed based on kidney biopsy. Proteinuria, creatinine, IgA, C3 were evaluated twice in the study group, at baseline and the end of follow-up. Kidney biopsy was categorized using the Oxford classification, with a calculation of the MEST-C score. The intensity of IgA and C3 deposits were rated from 0 to +4 in immunofluorescence microscopy. The intensity of mesangial C3 > +1 deposits in kidney biopsy has an effect on renal survival with normal GFR in children with IgAN. A reduced serum C3 level has not been a prognostic factor in children but perhaps this finding should be confirmed in a larger group of children.

A Systematic Literature Review of the Epidemiology, Health-Related Quality of Life Impact, and Economic Burden of Immunoglobulin A Nephropathy

Introduction: This systematic literature review analyzed published evidence on IgA nephropathy (IgAN), focusing on US epidemiology, health-related quality of life (HRQoL), and economic burden of illness. Methods: Using Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, Embase®, MEDLINE®, Cochrane, and Econlit (January 2010 to June 2020) were searched, along with relevant congresses (2017-2020). Results: Of 123 epidemiologic studies selected for data extraction, 24 reported IgAN diagnosis rates ranging from 6.3% to 29.7% among adult and pediatric patients undergoing renal biopsy, with all reported US rates <15%. No US studies reported IgAN prevalence. A meta-analysis of US studies calculated an annual incidence of 1.29/100 000 people, translating to an annual US incidence of 4236 adults and children. Relative to Europe, the United States had more patients diagnosed with IgAN in later chronic kidney disease stages. US rates of transition to end-stage renal disease (ESRD) ranged from 12.5% to 23% during 3-3.9 years of observation, rising to 53% during 19 years of observation. Across 8 studies reporting HRQoL, pain and fatigue were the most reported symptoms, and patients consistently ranked kidney function and mortality as the most important treatment outcomes. Patients with glomerulopathy reported worse mental health than healthy controls or hemodialysis patients; proteinuria was significantly associated with poorer HRQoL and depression. Conclusion: While economic evidence in IgAN remains sparse, management of ESRD is a major cost driver. IgAN is a rare disease where disease progression causes increasing patient burden, underscoring the need for therapies that prevent kidney function decline and HRQoL deterioration while reducing mortality.

Leflunomide plus low-dose prednisone in patients with progressive IgA nephropathy: a multicenter, prospective, randomized, open-labeled, and controlled trial

Background

Immunoglobulin A nephropathy (IgAN) is the most common cause of glomerulonephritis worldwide, and the optimal approach to its treatment remains a significant challenge.

Methods

We did a prospective, randomized, open-labeled, multicenter, controlled trial, comprised of 3-month run-in, 12-month treatment, and 12-month follow-up phases. After 3-month run-in phase, patients with biopsy-confirmed IgAN at risk of progression were randomly allocated to LEF plus low-dose prednisone (LEF + prednisone group) or conventionally accepted-dose prednisone [prednisone(alone) group] Our primary outcome was 24-h urine protein excretion (UPE) and secondary outcomes were serum albumin (sALB), serum creatinine (Scr), and eGFR. Safety was evaluated in all patients who received the trial medications.

Results

One hundred and eight patients [59 in LEF + prednisone group, 49 in prednisone (alone) group]were enrolled and finished their treatment and follow-up periods. There is no significant difference in the baseline level between the two groups. Compared with baseline, both groups showed a significant decrease in 24-h UPE (p < 0.01) and increase in sALB (p < 0.01), with stable Scr and eGFR throughout the 12-month treatment period. What’s more, these effects were sustained through the 12-month follow-up period. However, there was no difference in 24-h UPE, sALB, Scr, and eGFR between the two groups (p > 0.05). At 12 months, a difference in overall response rate, relapsing rate, and incidence of adverse events between the two groups was not significant.

Conclusions

The efficacy and safety of LEF plus low-dose prednisone and conventionally accepted-dose prednisone in the treatment of progressive IgAN are comparable.

Relationship between Gd-IgA1 and TNFR1 in IgA nephropathy and IgA vasculitis nephritis in children - multicenter study

AIM OF THE STUDY

To evaluate the relationship between serum Gd-IgA1 (sGd-IgA1) and serum and urine TNFR1 (sTNFR1, uTNFR1) levels as possible prognostic factors in IgA nephropathy (IgAN) and IgA vasculitis nephritis (IgAVN).

MATERIAL AND METHODS

From 299 patients from the Polish Registry of Pediatric IgAN and IgAVN, 60 children (24 IgAN and 36 IgAVN) were included in the study. The control group consisted of 20 healthy children. Proteinuria, haematuria, serum creatinine as well as IgA and C3 levels were measured and glomerular filtration rate (GFR) was calculated at onset and at the end of the follow-up. Kidney biopsy findings were evaluated using the Oxford classification. Serum Gd-IgA1 and serum and urine TNFR1 levels were measured at the end of follow-up.

RESULTS

Serum Gd-IgA1 level was significantly higher in IgAN and IgAVN patients in comparison to the control group. Urine TNFR1 was significantly higher in IgAN than in IgAVN and the control group. We did not observe any differences in sTNFR1 level between IgAN, IgAVN and control groups. We found a positive correlation between Gd-IgA1 and creatinine (r = 0.34), and negative between Gd-IgA1 and GFR (r = -0.35) at the end of follow-up. We observed a negative correlation between uTNFR1/creatinine log and albumin level and protein/creatinine ratio. We did not find any correlations between Gd-IgA1 and TNFR1.

CONCLUSIONS

The prognostic value of sGd-IgA1 in children with IgAN and IgAVN has been confirmed. TNFR1 is not associated with Gd-IgA1 and is not a useful prognostic marker in children with IgAN/IgAVN and normal kidney function.

Deletion of the miR-25/93/106b cluster induces glomerular deposition of immune complexes and renal fibrosis in mice

IgA nephropathy (IgAN), the most common form of primary glomerulonephritis, is caused by immune system dysfunction and affects only the kidneys. miRNA was involved in IgAN, in which their roles are still unknown. Herein, we found increased glomerular medulla size, proteinuria, kidney artery resistance, kidney fibrosis and immune complex deposition in 5‐month miR‐25/93/106b cluster knockout (miR‐TKO) mice. In vitro, the inhibition of miR‐25 cluster could promote cell proliferation and increase fibrosis‐related protein and transferrin receptor (TFRC) expression in human renal glomerular mesangial cell (HRMC). Luciferase assay revealed that inhibition of miR‐93/106b cluster could upregulate Ccnd1 expression through direct binding with the 3’UTR of Ccnd1. Conversely, inhibition of Ccnd1 expression prevented miR‐93/106b‐induced effect in HRMC. These findings suggested that miR‐25 cluster played an important role in the progression of IgAN, which provided new insights into the pathogenesis and treatment of IgAN.

Alternative Complement Pathway Is Activated and Associated with Galactose-Deficient IgA1 Antibody in IgA Nephropathy Patients

Background

Galactose-deficient IgA₁ (Gd-IgA₁) and alternative complement pathway activation are considered to be involved in the pathogenesis of IgA nephropathy (IgAN). Nevertheless, the relationships between alternative pathway activation and disease activity or Gd-IgA₁ level remains unclear.

Methods

Ninety-eight biopsy-diagnosed IgAN, twenty-five primary focal segmental sclerosis (FSGS) patients and forty-two healthy individuals were recruited in this study. Among them, fifty IgAN patients received immunosuppression. Follow-up blood samples at 1 and 3~6 months after immunosuppression were collected. Plasma levels of complement C5a, factor Ba and Gd-IgA₁ were measured and analyzed. Immunostaining for complement was performed in twenty-five IgAN and FSGS patients.

Results

At baseline, IgAN patients had higher levels of plasma C5a, factor Ba and Gd-IgA₁ than control subjects. Gd-IgA₁ levels positively correlated with plasma C5a and factor Ba. In addition, levels of factor Ba and Gd-IgA₁ were positively associated with proteinuria and negatively associated with renal function. Immunostaining revealed positive staining for factor Bb and C3c in glomeruli in IgAN patients, but not in FSGS patients. At baseline, patients receiving immunosuppression had more severe proteinuria and higher factor Ba. After 6 months, eGFR declined and proteinuria persisted in patients without immunosuppression. In contrast, patients who received immunosuppression exhibited decreased plasma levels of C5a, factor Ba, and Gd-IgA₁ as early as 1 month after treatment. Proteinuria decreased and renal function also remained stable 6 months after immunosuppression.

Conclusions

Our results indicate a close relationship between alternative complement pathway activation, Gd-IgA₁ concentration and clinical severity of IgAN. Level of complement factor B may be a potential marker for disease activity and therapeutic target in IgAN patients.

Measurement of galactosyl-deficient IgA1 by the monoclonal antibody KM55 contributes to predicting patients with IgA nephropathy with high risk of long-term progression

BACKGROUND AND OBJECTIVE

About 25% of patients with IgA nephropathy (IgAN) progress to stage 5 chronic kidney disease (CKD) after years of evolution. Various tools have been developed in recent years designed to predict which of the patients will had poorer outcomes. The value of circulating galactosyl-deficient IgA1 (Gd-IgA1) has been related to a worse evolution of IgAN in several studies. There are also some publications that relate higher APRIL values with a worse evolution. Recently, a new method has been developed that allows measuring the value of circulating Gd-IgA1 in a simpler way than those previously available. The objective of this study is to analyze the influence of circulating Gd-IgA1, measured by this method, on the progression of IgAN.

MATERIALS AND METHODS

Forty-nine patients with a diagnosis of IgAN demonstrated by renal biopsy were selected in our center, without having received prior immunosuppressive treatment, for whom frozen serum was available. The median follow-up was 4 years. Gd-IgA1 was measured by lectin-independent ELISA with the monoclonal antibody KM55 (IgA1 kit Cat. No. 30111694. IBL Int., Hamburg, Germany). Likewise, APRIL levels were also measured in these patients.

RESULTS

19 (38.8%) patients reached stage 5 CKD. The fourth quartile of circulating Gd-IgA1 was related to a higher cumulative risk of reaching stage 5 CKD in the Kaplan-Meier analysis (risk at the 5th year 39.4% vs. 24.3%, log rank p=0.019). The Gd-IgA1 value was related to an increased risk of CKD stage 5 (HR 1.147, 95% CI 1.035-1.270, p=0.009), regardless of glomerular filtration rate, proteinuria, the percentage of sclerosed glomeruli and the value of segmental sclerosis. We did not find significant differences in the APRIL values.

CONCLUSIONS

The value of circulating Gd-IgA1 measured by the monoclonal antibody KM55 is related to a worse evolution of patients with IgAN independently of other variables, so it could be included in the study of patients to improve the prediction of the risk of disease progression.

[Measurement of galactosyl-deficient IgA1 by the monoclonal antibody KM55 contributes to predicting patients with IgA nephropathy with high risk of long-term progression]

BACKGROUND AND OBJECTIVE

About 25% of patients with IgA nephropathy (IgAN) progress to stage 5 chronic kidney disease (CKD) after years of evolution. Various tools have been developed in recent years designed to predict which of the patients will had poorer outcomes. The value of circulating galactosyl-deficient IgA1 (Gd-IgA1) has been related to a worse evolution of IgAN in several studies. There are also some publications that relate higher APRIL values with a worse evolution. Recently, a new method has been developed that allows measuring the value of circulating Gd-IgA1 in a simpler way than those previously available. The objective of this study is to analyze the influence of circulating Gd-IgA1, measured by this method, on the progression of IgAN.

MATERIALS AND METHODS

Forty-nine patients with a diagnosis of IgAN demonstrated by renal biopsy were selected in our center, without having received prior immunosuppressive treatment, for whom frozen serum was available. The median follow-up was 4 years. Gd-IgA1 was measured by lectin-independent ELISA with the monoclonal antibody KM55 (IgA1 kit Cat. No. 30111694. IBL Int., Hamburg, Germany). Likewise, APRIL levels were also measured in these patients.

RESULTS

19 (38.8%) patients reached stage 5 CKD. The fourth quartile of circulating Gd-IgA1 was related to a higher cumulative risk of reaching stage 5 CKD in the Kaplan-Meier analysis (risk at the 5th year 39.4% vs. 24.3%, log rank p=0.019). The Gd-IgA1 value was related to an increased risk of CKD stage 5 (HR 1.147, 95% CI 1.035-1.270, p=0.009), regardless of glomerular filtration rate, proteinuria, the percentage of sclerosed glomeruli and the value of segmental sclerosis. We did not find significant differences in the APRIL values.

CONCLUSIONS

The value of circulating Gd-IgA1 measured by the monoclonal antibody KM55 is related to a worse evolution of patients with IgAN independently of other variables, so it could be included in the study of patients to improve the prediction of the risk of disease progression.

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.