Sinomenine Hydrochloride Protects IgA Nephropathy Through Regulating Cell Growth and Apoptosis of T and B Lymphocytes

Purpose

Sinomenine hydrochloride (SH) is used to treat chronic inflammatory diseases such as rheumatoid arthritis and may also be efficacious against Immunoglobulin A nephropathy (IgAN). However, no trial has investigated the molecular mechanism of SH on IgAN. Therefore, this study aims to investigate the effect and mechanism of SH on IgAN.

Methods

The pathological changes and IgA and C3 depositions in the kidney of an IgAN rat model were detected by periodic acid-Schiff (PAS) and direct immunofluorescence staining. After extracting T and B cells using immunomagnetic beads, we assessed their purity, cell cycle phase, and apoptosis stage through flow cytometry. Furthermore, we quantified cell cycle-related and apoptosis-associated proteins by Western blotting.

Results

SH reduced IgA and C3 depositions in stage 4 IgAN, thereby decreasing inflammatory cellular infiltration and mesangial injury in an IgAN model induced using heteroproteins. Furthermore, SH arrested the cell cycle of lymphocytes T and B from the spleen of IgAN rats. Regarding the mechanism, our results demonstrated that SH regulated the Cyclin D1 and Cyclin E1 protein levels for arresting the cell cycle and it also regulated Bax and Bcl-2 protein levels, thus increasing Cleaved caspase-3 protein levels in Jurkat T and Ramos B cells.

Conclusion

SH exerts a dual regulation on the cell cycle and apoptosis of T and B cells by controlling cell cycle-related and apoptosis-associated proteins; it also reduces inflammatory cellular infiltration and mesangial proliferation. These are the major mechanisms of SH in IgAN.

Circulating soluble CD30 is associated with renal tertiary lymphoid structures and the progression of IgA nephropathy

BACKGROUND

Renal tertiary lymphoid structures (TLSs) are involved in renal pathology and prognosis of IgA nephropathy (IgAN). CD30 and its ligands participate in the formation of renal TLSs. However, the relationship between circulating CD30 and renal prognosis is unclear. The objective of this study was to evaluate the relationship between circulating CD30 and prognosis in patients with IgAN.

METHODS

We conducted a retrospective study including 351 patients with biopsy proved IgAN. We collected clinical and pathologic features at the time of biopsy and recorded renal follow-up outcomes. Circulating CD30 levels in IgAN patients at the time of biopsy were measured via enzyme-linked immunosorbent assay (ELISA). The association between elevated CD30 levels and the composite endpoint (defined as a ≥ 50 % decline in eGFR from baseline, end-stage renal disease, or death) was investigated using Cox regression analysis.

RESULTS

During a median follow-up period of 5.12 years, 44 (12.5 %) patients in the cohort reached the composite endpoint. Kaplan-Meier survival curve analysis revealed a significant association between higher circulating CD30 levels and a poorer renal prognosis (log-rank P < 0.001). Cox regression analysis showed that high CD30 was an independent factor for the composite endpoints in multivariable-adjusted models (HR 3.397, 95 % CI: 1.230-9.384, P = 0.018). These associations were also observed in a subgroup of patients with concomitant renal TLSs formation (10.443, 95 % CI: 1.680-65.545, P = 0.012), proteinuria > 1 g/d (HR 12.287, 95 % CI: 1.499-100.711, P = 0.019), and female patients (HR 22.372, 95 % CI: 1.797-278.520, P = 0.016).

CONCLUSION

Elevated level of circulating CD30 is an independent risk factor for renal disease progression in patients with IgAN.

Causal relationship between PCSK9 inhibitor and primary glomerular disease: a drug target Mendelian randomization study

Background

Successive observational studies have highlighted low-density lipoprotein cholesterol (LDL-C) as a standalone risk factor for the progression of chronic kidney disease (CKD) to end-stage renal disease. Lowering LDL-C levels significantly reduces the incidence of atherosclerotic events in patients with progressive CKD. Recent research indicates that proprotein convertase subtilisin kexin 9 (PCSK9) inhibitors not only effectively lower LDL-C levels in CKD patients but also exhibit therapeutic potential for autoimmune diseases such as systemic lupus erythematosus, rheumatoid arthritis, and ulcerative colitis. However, the role of PCSK9 inhibitors (PCSK9i) in treating CKD beyond lowering LDL-C levels remains uncertain. Therefore, this study employs drug-targeted Mendelian randomization (MR) to investigate the causal impact of PCSK9i on primary glomerular diseases such as IgA nephropathy (IgAN), membranous nephropathy (MN), and nephrotic syndrome (NS).

Methods

Single-nucleotide polymorphisms (SNPs) linked to LDL-C were sourced from the Global Lipids Genetics Consortium genome-wide association study (GWAS). Genes situated in proximity to 3-Hydroxy-3-methylglutaryl-coenzyme A reductase (HMGCR), and PCSK9 served as proxies for therapeutic inhibition of these targets. The causal link between PCSK9i and the risk of primary glomerular disorders was discovered using drug-target MR studies. The HMGCR inhibitor, a drug target of statins, was utilized for comparative analysis with PCSK9i. Primary outcomes included the risk assessment for IgAN, MN, and NS, using the risk of coronary heart disease as a positive control.

Results

The inhibition of PCSK9, as proxied genetically, was found to significantly reduce the risk of IgAN [odds ratio, OR (95% confidence interval, CI) = 0.05 (-1.82 to 1.93), p = 2.10 × 10-3]. Conversely, this inhibition was associated with an increased risk of NS [OR (95% CI) = 1.78 (1.34-2.22), p = 0.01]. Similarly, HMGCR inhibitors (HMGCRi) demonstrated a potential reduction in the risk of IgAN [OR (95%CI) = 0.0032 (-3.58 to 3.59), p = 1.60 × 10-3).

Conclusions

PCSK9i markedly decreased the risk of IgAN, suggesting a potential mechanism beyond their primary effect on LDL-C. However, these inhibitors were also associated with an increased risk of NS. On the other hand, HMGCRi appears to serve as a protective factor against IgAN. Conversely, PCSK9i may pose a risk factor for NS, suggesting the necessity for cautious application and further research into their impacts on various glomerular diseases.

Sodium-Glucose Co-Transporter 2 Inhibitors: Mechanism of Action and Efficacy in Non-Diabetic Kidney Disease from Bench to Bed-Side

Sodium-glucose cotransporter 2 inhibitors (SGLT2i) are currently available for the management of type 2 diabetes mellitus. SGLT2i acts by inhibiting renal SGLT2, thereby increasing glucosuria and lowering serum glucose. Recent trials are emerging supporting a role for SGLT2i irrespective of the diabetic status pointing towards that SGLT2i have other mechanisms of actions beyond blood sugar control. In this review, we will shed light on the role of this group of medications that act as SGLT2i in non-diabetics focusing on pre-clinical and clinical data highlighting the mechanism of renoprotection and effects of SGLT2i in the non-diabetic kidneys.

Deciphering roles of protein post-translational modifications in IgA nephropathy progression and potential therapy

Immunoglobulin A nephropathy (IgAN), one type of glomerulonephritis, displays the accumulation of glycosylated IgA in the mesangium. Studies have demonstrated that both genetics and epigenetics play a pivotal role in the occurrence and progression of IgAN. Post-translational modification (PTM) has been revealed to critically participate in IgAN development and progression because PTM dysregulation results in impaired degradation of proteins that regulate IgAN pathogenesis. A growing number of studies identify that PTMs, including sialylation, o-glycosylation, galactosylation, phosphorylation, ubiquitination and deubiquitination, modulate the initiation and progression of IgAN. Hence, in this review, we discuss the functions and mechanisms of PTMs in regulation of IgAN. Moreover, we outline numerous compounds that govern PTMs and attenuate IgAN progression. Targeting PTMs might be a useful strategy to ameliorate IgAN.

Renal outcomes in IgA nephropathy following inactivated SARS-CoV-2 vaccination

INTRODUCTION

There are increasing case reports on de novo or relapsing IgA nephropathy (IgAN) following SARS-CoV-2 vaccines, although the follow-up information on renal outcomes in IgAN patients post-SARS-CoV-2 vaccination is limited. In this study, we evaluated the renal outcomes of IgAN patients following inactivated vaccines.

METHODS

We investigated the change in eGFR, proteinuria and hematuria in 113 primary IgAN patients post-vaccination. Worsening proteinuria was defined as an increase in proteinuria by more than 0.5 times and proteinuria > 1 g/d. Univariate and multivariable logistic regression analysis were used to evaluate possible predictors of worsening proteinuria. We then compared the renal outcomes of vaccinated patients after 6 months with 101 unvaccinated patients who were followed during the same period.

RESULTS

A 2.54% (0.64, 8.61) decrease in renal function was observed in post-vaccination patients. Subgroup analysis revealed a significant decrease in eGFR in patients with 30 ≤ eGFR < 60 (mL/min/1.73 m2) post second SARS-CoV-2 dose (n = 18, p = 0.01). In addition, 10 individuals displayed worsening proteinuria post-vaccination, with the proteinuria subsequently ameliorating significantly after 6-month. Multivariate analysis showed that higher eGFR levels was an independent protective factor for worsening proteinuria. The renal outcome tended towards a decrease in eGFR in vaccinated patients after 6 months follow-up, although the difference was not significant (p = 0.06).

CONCLUSION

Kidney function in IgAN patients tended to worsen after SARS-CoV-2 vaccination, particularly those with initial poor kidney function. This pattern of disease flare appears to be clinically mild, and further research is needed to determine whether the impact on kidney function is long-term.

Risk for graft loss in pediatric and young adult kidney transplant recipients due to recurrent IgA nephropathy

IgA nephropathy (IgAN) is associated with a risk for posttransplant recurrence. Data are limited regarding graft loss attributable to recurrence of IgAN among pediatric and young adult kidney transplant (KT) recipients. This was a retrospective cohort study of patients aged 0 to 25 years from the Scientific Registry of Transplant Recipients who received a primary KT for IgAN. Patients with history of KT attributable to renal dysplasia were comparators. Outcomes included the incidence of graft loss attributable to IgAN recurrence, association with donor type, and posttransplant corticosteroid use. In total, 5475 transplant recipients were included, with 1915 patients with IgAN and 3560 patients with renal dysplasia. In a multivariable Cox proportional hazards model, IgAN was associated with higher risk of graft loss (adjusted hazard ratio [aHR], 1.35; 95% CI, 1.21-1.50; P < .001) compared with dysplasia. Graft loss was attributed to recurrent disease in 5.4% of patients with IgAN. In a multivariable competing risks analysis, patients with IgAN receiving a parental living-donor kidney were more likely to report graft loss from recurrent disease compared with patients with a nonparental living donor (aHR, 0.52; 95% CI, 0.31-0.91; P = .02). Posttransplant prednisone use was not associated with improved graft survival (P = .2). These data challenge existing paradigms in posttransplant management of patients with IgAN.

Efficacy of prednisone combined with mycophenolate mofetil for immunoglobulin A nephropathy with moderate-to-severe renal dysfunction

BACKGROUND

Immunoglobulin A nephropathy (IgAN) is a common form of chronic glomerulonephritis. Currently, IgAN is one of the main causes of chronic renal failure in China; its prognosis varies greatly between patients, with renal function at the time of diagnosis and prognosis being strongly correlated. Mycophenolate mofetil (MMF) is a drug with a good immunomodulatory effect and is commonly used clinically. However, its effects in IgAN have not yet been clearly demonstrated. Therefore, herein, we retrospectively compared the effectiveness and safety of prednisone alone or combined with MMF for the treatment of primary IgAN with moderate-to-severe renal impairment.

AIM

To evaluate the effectiveness and safety of prednisone and MMF in treating IgAN with moderate-to-severe renal dysfunction.

METHODS

Between January 2011 and December 2020, 200 patients with moderate-to-severe IgAN were included in this study, all of whom were admitted to Wuxi People's Hospital affiliated with Nanjing Medical University. All patients underwent a renal puncture biopsy, which revealed primary IgAN with a glomerular filtration rate (GFR) of 30-60 mL/min. The patients were divided into a glucocorticoid therapy group (GTG) and an immunosuppressive therapy group (ITG) according to the different treatment regimens, with 100 patients in each group. Based on general treatments, such as angiotensin-converting enzyme inhibitors/ angiotensin receptor blockers, patients in the GTG were administered prednisone 0.5-0.8 mg/ (kg·d-1) for 4-8 wk, which was reduced by 5 mg every two weeks until the maintenance(30 mg/d) dose was reached and maintained for 12 mo. In the ITG, MMF was administered at 1.0 g/d for 6-12 mo, followed by a maintenance dosage of 0.5 g/d for 12 mo. Age, sex, blood pressure, 24-h urinary egg white measurement, serum creatinine (Scr), blood uric acid, blood albumin, blood potassium (K), hemoglobin, GFR, alanine aminotransferase, total cholesterol (T-CHO), fasting blood glucose, and body mass index were recorded. The 24-h urinary protein, Scr, and GFR levels were recorded 3, 6, 9, and 12 mo after treatment. Follow-up data were also collected.

RESULTS

No discernible differences existed between the two groups in terms of age, sex, blood pressure, creatinine, 24-h urinary protein level, GFR, or other biochemical indicators at the time of enrollment. Both regimens significantly reduced the 24-h urinary protein quantitation and stabilized renal function. Nine months after treatment, the 24-h urinary protein and Scr of the ITG decreased more significantly than those of the GTG. By the 12th month of treatment, the 24-h urinary protein and Scr in both groups continued to decrease compared to those by the 9th month. In addition, the overall response rate in the ITG was significantly higher than that in the GTG. The occurrence of side effects did not vary significantly between the two regimens; however, endpoint events were significantly more common in the GTG than in the ITG. The follow-up time for the GTG was noticeably lower than that for the ITG.

CONCLUSION

Prednisone combined with MMF was effective for the treatment of IgAN with moderate-to-severe renal dysfunction.

Global trends and hotspots in IgA nephropathy: a bibliometric analysis and knowledge map visualization from 2012 to 2023

OBJECTIVES

This study aimed to investigate the distribution patterns and research frontiers of international literature and thus present a holistic bibliometric evaluation of the studies on IgA nephropathy.

METHODS

The Web of Science Core Collection database was searched for studies of IgA nephropathy from January 2012 to March 2023. The keywords and references are analyzed by CiteSpace, while the countries and institutions are analyzed by VOSviewer.

RESULTS

A total of 2987 publications on IgA nephropathy were included. The country with the most publications was China (n = 1299), and the institution with the most publications was Peking University (n = 139). The most frequent keywords were IgA nephropathy (n = 2013), Oxford classification (n = 482), and diseases (n = 433). The keywords that continue to burst out at high intensity are multicenter study and gut microbiota. Moreover, the top five references for burst strength were also listed.

CONCLUSIONS

IgA nephropathy has attracted widespread research interest, particularly in high-prevalence areas. From 2012 to 2023, publications on IgA nephropathy show a linear increase. China is the country with the highest number of publications and Peking University is the institution with the highest number of publications. Current research hotspots and frontiers are mainly multicenter studies related to IgA nephropathy and its exploration with gut microbiota. Overall, we have provided a comprehensive scientometric analysis of IgA nephropathy that will inform researchers and healthcare practitioners.

Colocalization of IgG and IgA Heavy Chains with Kappa and Lambda Light Chains in Glomerular Deposits of IgA Nephropathy Patients Using High-Resolution Confocal Microscopy and Correlation with Oxford MEST-C Scores

Routine immunofluorescence microscopy of glomerular immunodeposits in IgA nephropathy shows IgA, C3, and lambda light chains, and sometimes IgG, IgM, and kappa light chains. However, a previous study using high-resolution confocal microscopy showed IgG in all IgA nephropathy cases, likely representing autoantibodies specific for galactose-deficient IgA1. Here, we used high-resolution confocal microscopy to examine the composition of glomerular immunodeposits and colocalization of kappa and lambda light chains with IgA or IgG heavy chains in kidney-biopsy samples from twenty patients with IgA nephropathy, seventeen without IgG, and nine with no or trace kappa light chains by routine immunofluorescence microscopy. IgG was detected in all biopsies by high-resolution confocal microscopy. Single-optical-plane images showed similar colocalization of IgG heavy chains with kappa and lambda light chains. Colocalization of IgA heavy chains was greater with lambda light chains than with kappa light chains. Colocalization of IgG heavy chain with kappa light chains was higher than with lambda light chains in biopsies with endocapillary hypercellularity and crescents, i.e., biopsies with active lesions. We confirmed the utility of high-resolution confocal microscopy to detect components of glomerular immunodeposits not apparent on routine immunofluorescence microscopy and for colocalization of different components, potentially clarifying the pathogenesis of IgA nephropathy.

Decrypting the Pathological Pathways in IgA Nephropathy

IgAN is the most common form of glomerulonephritis affecting 2000000 people annually. The disease ultimately progresses to chronic renal failure and ESRD. In this article, we focused on a comprehensive understanding of the pathogenesis of the disease and thus identifying different target proteins that could be essential in therapeutic approaches in the management of the disease. Aberrantly glycosylated IgA1 produced by the suppression of the enzyme β-1, 3 galactosyltransferase ultimately triggered the formation of IgG autoantibodies which form complexes with Gd-IgA1. The complex gets circulated through the blood vessels through monocytes and ultimately gets deposited in the glomerular mesangial cells via CD71 receptors present locally. This complex triggers the inflammatory pathways activating the alternate complement system, various types of T Cells, toll-like receptors, cytokines, and chemokines ultimately recruiting the phagocytic cells to eliminate the Gd-IgA complex. The inflammatory proteins cause severe mesangial and podocyte damage in the kidney which ultimately initiates the repair process following chronic inflammation by an important protein named TGFβ1.TGF β1 is an important protein produced during chronic inflammation mediating the repair process via various downstream transduction proteins and ultimately producing fibrotic proteins which help in the repair process but permanently damage the glomerular cells.

Uric acid-based ratios for predicting renal failure in Chinese IgA nephropathy patients

Objective: The uric acid/albumin ratio (UAR), a novel, simple, and compositive laboratory biomarker, has recently attracted attention for predicting disease prediction and disease prognosis. However, whether uric acid-related biomarkers (especially UAR) could serve as prognostic indicator for IgAN is unclear. Methods: In this retrospective cohort study, biopsy-confirmed IgAN patients from 2009 to 2017 from West China Hospital were evaluated. The optimal cutoff value of UAR for renal outcome was defined using the Youden index by the area under receiver operating characteristic curve (AUC). The patients were then categorized into the high UAR group and the low UAR group. Renal endpoints were defined as progression to ESRD, eGFR decreased ≥50% of the baseline level, or initiation of renal replacement treatment. Kaplan‒Meier survival analysis and Cox regression analysis were used to identify factors influencing IgAN outcomes. Results: A total of 1143 patients with a median age of 33.0 (26.0-42.0) (44.2% men) were included in the study. The best cut-off UAR concerned with renal survival was determined to be 9.94 with a specificity of 77.5% and a sensitivity of 61.5% (J, 0.390; AUC, 0.750). Then, the patients were divided into two groups labelled as low and high UAR ratios (≥ 9.94 and <9.94, respectively). More severe clinical manifestations and pathological lesions were observed in the high UAR group. Multivariate Cox regression analysis after adjusted for important clinicopathological parameters manifested that a high UAR was an independent prognostic biomarker for IgAN. (p = 0.036, HR =2.56, 95% CI: 1.07-6.16). Conclusion: UAR might be a novel predictor for renal progression and contribute to targeted management.

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.

TFRC-RNA interactions show the regulation of gene expression and alternative splicing associated with IgAN in human renal tubule mesangial cells

Introduction: IgA nephropathy (IgAN) is the most common primary glomerular disease (PGD) which could progress to renal failure and is characterized by aberrant IgA immune complex deposition. Transferrin receptor1 (TFRC), an IgA receptor, is a potential RNA binding protein (RBP) which regulates expression of genes positively associated with the cell cycle and proliferation and is involved in IgAN. Molecular mechanisms by which TFRC affects IgAN development remain unclear. Methods: In this study, TFRC was overexpressed in human renal tubular mesangial cells (HRMCs) and RNA-sequencing (RNA-seq) and improved RNA immunoprecipitation sequencing (iRIP-seq) were performed. The aim was to identify potential RNA targets of TFRC at transcriptional and alternative splicing (AS) levels. Results: TFRC-regulated AS genes were enriched in mRNA splicing and DNA repair, consistent with global changes due to TFRC overexpression (TFRC-OE). Expression of TFRC-regulated genes potentially associated with IgAN, including CENPH, FOXM1, KIFC1, TOP2A, FABP4, ID1, KIF20A, ATF3, H19, IRF7, and H1-2, and with AS, CYGB, MCM7 and HNRNPH1, were investigated by RT-qPCR and iRIP-seq data analyzed to identify TFRC-bound RNA targets. RCC1 and RPPH1 were found to be TFRC-bound RNA targets involved in cell proliferation. Discussion: In conclusion, molecular TFRC targets were identified in HRMCs and TFRC found to regulate gene transcription and AS. TFRC is considered to have potential as a clinical therapeutic target.

APOC1 exacerbates renal fibrosis through the activation of the NF-κB signaling pathway in IgAN

Introduction: IgA nephropathy (IgAN) is the most common disease leading to end-stage renal disease, and tubular fibrosis represents an important risk factor for disease progression. However, research on early molecular diagnostic indicators of tubular fibrosis and the mechanisms underlying disease progression is still lacking. Methods: The GSE93798 dataset was downloaded from the GEO database. DEGs were screened and analyzed for GO and KEGG enrichment in IgAN. The least absolute shrinkage and selection operator (LASSO) and support vector machine recursive feature elimination (SVM-RFE) algorithms were applied to screen for hub secretory genes. The expression and diagnostic efficacy of hub genes were confirmed by the GSE35487 dataset. ELISA was applied to detect the expression of APOC1 in serum. The expression and localization of hub genes in IgAN were verified by the expression of IHC and IF in human kidney tissues, and the correlation of expression with clinical data was verified in the Nephroseq database. Finally, cellular experiments clarified the role of hub genes in the signaling pathway. Results: A total of 339 DEGs were identified in IgAN, of which 237 were upregulated and 102 downregulated. The KEGG signaling pathway is enriched in the ECM-receptor interaction and AGE-RAGE signaling pathway. APOC1, ALB, CCL8, CXCL2, SRPX2, and TGFBI identified six hub secretory genes using the LASSO and SVM-RFE algorithms. In vivo and in vitro experiments demonstrated that APOC1 expression was elevated in IgAN. The serum concentration of APOC1 was 1.232 ± 0.1812 μg/ml in IgAN patients, whereas it was 0.3956 ± 0.1233 μg/ml in healthy individuals. APOC1 exhibited high diagnostic efficacy for IgAN (AUC of 99.091%, specificity of 95.455%, and sensitivity of 99.141%) in the GSE93798 dataset. APOC1 expression negatively correlated with eGFR (R ² = 0.2285, p = 0.0385) and positively correlated with serum creatinine (R ² = 0.41, p = 0.000567) in IgAN. APOC1 exacerbated renal fibrosis, possibly in part by activating the NF-κB pathway in IgAN. Conclusion: APOC1 was identified as the core secretory gene of IgAN, which was closely associated with blood creatinine and eGFR and had significant efficacy in the diagnosis of IgAN. Mechanistic studies revealed that the knockdown of APOC1 could improve IgAN renal fibrosis by inhibiting the NF pathway, which may be a potential therapeutic target for improving renal fibrosis in 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.

Comparison between outcomes of IgA nephropathy with nephrotic-range proteinuria and nephrotic syndrome: do podocytes play a role?

Background

Nephrotic syndrome (NS) and nephrotic-range proteinuria (NRP) are uncommon in IgA nephropathy (IgAN), and their clinicopathology and prognosis have not been discussed. Podocytes may play an important role in both clinical phenotypes.

Methods

We investigated 119 biopsy-proven IgAN patients with proteinuria over 2 g/d. The patients were divided into three groups according to proteinuria level: the overt proteinuria (OP) group, NS group, and NRP group. In addition, according to the severity of foot process effacement (FPE), the patients were divided into three groups: the segmental FPE (SFPE) group, moderate FPE (MFPE) group, and diffuse FPE (DFPE) group. The outcome was survival from a combined event defined by a doubling of the baseline serum creatinine and a 50% reduction in eGFR or ESRD.

Results

Compared with the NRP group, patients in the NS group had more severe microscopic hematuria, presented with more severe endocapillary hypercellularity and had a higher percentage of DFPE. The Kaplan–Meier curve showed that MFPE patients had a better outcome in the NRP group <50% of tubular atrophy/interstitial fibrosis. In the multivariate model, the NRP group (HR = 17.098, 95% CI = 3.835–76.224) was associated with an increased risk of the combined event, while MFPE (HR = 0.260, 95% CI = 0.078–0.864; p = 0.028) was associated with a reduced risk of the combined event. After the addition of renin-angiotensin system inhibitors (RASi), the incidence of the combined event in the MFPE group (HR = 0.179, 95% CI = 0.047–0.689; p = 0.012) was further reduced.

Conclusions

NS presented more active lesions and more severe FPE in IgAN. NRP was an independent risk factor for progression to the renal endpoint, while MFPE indicated a better prognosis in NRP without obvious chronic renal lesions, which may benefit from RASi.

A systematic review assessing the effectiveness of COVID-19 mRNA vaccines in chronic kidney disease (CKD) individuals

Background: SARS-CoV-2 is a coronavirus that has rapidly spread across the world with a detrimental effect on the global population. Several reports have highlighted an increased mortality rate and a higher severity of COVID-19 infection in chronic kidney disease (CKD) individuals. Upon the development of various SARS-CoV-2 vaccines, mRNA vaccines including BNT162b2 and mRNA-1273 were deemed safe, with a high efficacy in preventing COVID-19 in the general population. This review investigates whether  SARS-CoV-2 mRNA vaccines are as effective in triggering an immune response in Dialysis Patients (DPs) and Kidney Transplant Recipients (KTRs) and if a third dose is required in this  population. Methods: A systematic search employing the PRISMA criteria was conducted in several major databases, with the data being extracted from publications for the period January 2021 to May 2022 (PROSPERO: CRD42022338514, June 15, 2022). Results: 80 studies were included in this analysis with a total cohort number of 15,059 participants. Overall, 85.29% (OR = 17.08, 95% CI = 15.84-18.42, I ² = 98%) and 41.06% (OR = 0.52, 95% CI = 0.48-0.5, I ² = 95%) of DPs and KTRs included in this review showed positive seroconversion after two doses of either mRNA vaccine, respectively. A total 76% (OR = 6.53, 95% CI = 5.63-7.5, I ² = 96%) of the cohort given a third dose of an mRNA vaccine demonstrated positive seroconversion, with 61.86% (OR = 2.31, 95% CI = 1.95-2.75 I ² = 95%) of the cohort that was assessed for a cellular response displaying a positive response. Conclusions: This data emphasises a reduced incidence of a positive immune response in DPs and KTRs compared to healthy controls, albeit a better response in DPs than when compared to KTRs alone was observed. A third dose  appears to increase the occurrence of an immune response in the overall DP/KTR cohort.

Chemokine (C-C motif) receptor 2 is associated with the pathological grade and inflammatory response in IgAN children

Background

Chemokine (C–C motif) receptor 2 (CCR2) is involved in important physiological and pathological processes, such as inflammation and autoimmune diseases. Abnormal immune and inflammatory responses play a critical role in the development and progression of IgA nephritis (IgAN). However, the role of CCR2 in IgAN is unknown.

Methods

Fifteen IgAN children who were diagnosed by kidney biopsy provided kidney biopsy tissue, blood and urine samples, and age-matched healthy control subjects (blood donators n = 12; tissue donators n = 8) were included. Immunohistochemical analysis was used to detect the expression of CCR2, MCP-1, IL-6, IL-17, and TNF-α in the kidney tissues. Relative optical density (OD) was calculated by Image J software, and the correlation between CCR2 expression and pathological grade in IgAN children was analyzed.

Results

The expression of CCR2 significantly increased in mesangial cells of children with IgAN compared to that in control group (P < 0.001), especially in IgAN patients with Lee’s grade III to IV (P < 0.001). Interestingly, CCR2 expression was positively correlated with Lee’s grade (r = 0.9152, P = 0.0001) in IgAN children. The expression levels of inflammatory factors were markedly increased in IgAN children, and importantly CCR2 expression was positively correlated with it’s expression level.

Conclusions

The results suggest that CCR2 signaling might be involved in pathological process and inflammatory responses of children IgAN, and could potentially be an intervention target in children IgAN.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12882-022-02839-y.

Contribution of functional and quantitative genetic variants of Complement Factor H and Factor H-Related (FHR) proteins on renal pathology

The complement system is a first line of defence against infectious, tumoral or autoimmune processes, and it is constitutively regulated to avoid excessive or unspecific activation. Factor H (FH), a most relevant complement regulator, controls complement activation in plasma and on the cellular surfaces of autologous tissues. FH shares evolutionary origin and structural features with a group of plasma proteins known as FH-Related Proteins (FHRs), which could act as FH functional antagonists. Studies in patient cohorts of atypical Haemolytic-Uraemic Syndrome (aHUS), C3 Glomerulopathy (C3G), and IgA nephropathy (IgAN), have identified rare genetic variants that give rise to severe FH and FHRs dysfunctions, and are major genetic predisposing factors. These patients also have a higher frequency of a few polymorphisms whose relevance as disease risk factors is incompletely understood. In the last years, the availability of specific reagents has allowed a more precise quantitation of FH and FHRs in plasma samples from patients and controls. These studies have revealed that some aHUS, C3G or IgAN risk polymorphisms determine mild changes in FH or FHRs levels that could somehow perturb complement regulation and favour disease pathogenesis.

An evaluation of the roles of hematuria and uric acid in defining the prognosis of patients with IgA nephropathy

In recent years, many significant advances have been made in determining which clinical manifestations and pathologic lesions can provide prognostic information for patients with IgA nephropathy (IgAN). However, some important questions remain, including the long-term consequences of hematuria, both macroscopic (MH) and microscopic (mH), in patients with IgAN. The importance of distinguishing patients who have a single episode of MH of long duration from those with recurrent episodes of short duration and the prognostic importance of the episodes of acute kidney injury (AKI) that sometimes accompany episodic MH will be discussed. Studies that have evaluated the mechanisms that may be responsible for recurrent MH and the toxic effects of red blood cells (RBCs), or their constituents, on kidney tubules will also be addressed. In the last section, I will review the evidence that hyperuricemia (HU) may be a significant independent risk factor for progressive kidney disease in patients with IgAN.

The Glomerulus According to the Mesangium

The glomerulus is the functional unit for filtration of blood and formation of primary urine. This intricate structure is composed of the endothelium with its glycocalyx facing the blood, the glomerular basement membrane and the podocytes facing the urinary space of Bowman's capsule. The mesangial cells are the central hub connecting and supporting all these structures. The components as a unit ensure a high permselectivity hindering large plasma proteins from passing into the urine while readily filtering water and small solutes. There has been a long-standing interest and discussion regarding the functional contribution of the different cellular components but the mesangial cells have been somewhat overlooked in this context. The mesangium is situated in close proximity to all other cellular components of the glomerulus and should be considered important in pathophysiological events leading to glomerular disease. This review will highlight the role of the mesangium in both glomerular function and intra-glomerular crosstalk. It also aims to explain the role of the mesangium as a central component involved in disease onset and progression as well as signaling to maintain the functions of other glomerular cells to uphold permselectivity and glomerular health.

Urine proteomics for prediction of disease progression in patients with IgA nephropathy

BACKGROUND

Risk of kidney function decline in immunoglobulin A (IgA) nephropathy (IgAN) is significant and may not be predicted by available clinical and histological tools. To serve this unmet need, we aimed at developing a urinary biomarker-based algorithm that predicts rapid disease progression in IgAN, thus enabling a personalized risk stratification.

METHODS

In this multicentre study, urine samples were collected in 209 patients with biopsy-proven IgAN. Progression was defined by tertiles of the annual change of estimated glomerular filtration rate (eGFR) during follow-up. Urine samples were analysed using capillary electrophoresis coupled mass spectrometry. The area under the receiver operating characteristic curve (AUC) was used to evaluate the risk prediction models.

RESULTS

Of the 209 patients, 64% were male. Mean age was 42 years, mean eGFR was 63 mL/min/1.73 m2 and median proteinuria was 1.2 g/day. We identified 237 urine peptides showing significant difference in abundance according to the tertile of eGFR change. These included fragments of apolipoprotein C-III, alpha-1 antitrypsin, different collagens, fibrinogen alpha and beta, titin, haemoglobin subunits, sodium/potassium-transporting ATPase subunit gamma, uromodulin, mucin-2, fractalkine, polymeric Ig receptor and insulin. An algorithm based on these protein fragments (IgAN237) showed a significant added value for the prediction of IgAN progression [AUC 0.89; 95% confidence interval (CI) 0.83-0.95], as compared with the clinical parameters (age, gender, proteinuria, eGFR and mean arterial pressure) alone (0.72; 95% CI 0.64-0.81).

CONCLUSIONS

A urinary peptide classifier predicts progressive loss of kidney function in patients with IgAN significantly better than clinical parameters alone.

LncRNA PTTG3P induced aberrant glycosylated IgA1 production and B cell growth in IgA nephropathy

Growing evidences suggested that lncRNAs played functional role in several cell functions such as cell growth, invasion, migration, metabolize, apoptosis, and differentiation. However, roles of lncRNA in the development and progression of IgAN remain unknown. In this reference, we indicated that PTTG3P level was overexpressed in IgAN samples compared to healthy subject. PTTG3P expression was also higher in urinary of IgAN cases than in urinary of healthy control. Furthermore, the urinary expression of PTTG3P was correlated with PTTG3P expression in intra-renal of IgAN cases. PTTG3P overexpression induced B cell growth and enhanced cyclin D1 and ki-67 expression. Overexpression of PTTG3P induced IL-1β and IL-8 production. miR-383 level was decreased in IgAN samples compared to healthy subject. In addition, miR-383 expression was also lower in urinary of IgAN cases than in urinary of healthy control. Elevated miR-383 expression decreased luciferase intensity regulated with PTTG3P, while overexpression of miR-383 had no effect on luciferase intensity of the mutant PTTG3P. PTTG3P overexpression suppressed miR-383 expression in B cells. Ectopic miR-383 expression suppressed B cell growth and IL-1β and IL-8 production. Finally, we showed that overexpression of PTTG3P promoted B cell growth and IL-1β and IL-8 production via regulating miR-383. There results proved that PTTG3P played crucial role in progression of IgAN.

Hypertriglyceridemia Is Associated with More Severe Histological Glomerulosclerosis in IgA Nephropathy

IgA nephropathy (IgAN) is a globally well-known primary glomerular nephropathy. Hypertriglyceridemia (HTG) is one factor contributing to atherosclerosis and is a common complication of renal failure. HTG is a significant risk factor for decreased renal function in patients with IgAN. We evaluated the association of HTG with the histopathological features of IgAN patients. A total of 480 patients diagnosed with IgAN via kidney biopsy from eight university hospitals affiliated with the College of Medicine of the Catholic University of Korea were included in the final cohort. Pathological features were evaluated by eight expert pathologists with hospital consensus. HTG was defined as a serum triglyceride (TG) level of ≥150 mg/dL. In the study population analysis, the HTG group was older, with more males; higher body mass index (BMI), low-density lipoprotein cholesterol (LDL-C) and spot urine protein ratio; and lower estimated glomerular filtration rate (eGFR). In the lipid profile analysis, eGFR was negatively correlated with TGs/ high-density lipoprotein cholesterol (HDL) and triglyceride-glucose index (TyG). Proteinuria positively correlated with TGs/HDL, non-HDL/HDL, LDL/HDL, TyG, TGs and LDL. The percentages of global sclerosis (GS), segmental sclerosis (SS) and capsular adhesion (CA), and the scores for mesangial matrix expansion (MME) and mesangial cell proliferation (MCP), were more elevated in the HTG group compared to the normal TG group. Multivariable linear regression analysis showed that the percentages of global sclerosis, segmental sclerosis and capsular adhesion, as well as the scores for mesangial matrix expansion and mesangial cell proliferation, were positively associated with TG level. In binary logistic regression, the HTG group showed a higher risk for global sclerosis and segmental sclerosis. In conclusion, HTG is a significant risk factor for glomerulosclerosis in IgAN.

Association between urinary VEGFA and renal pathology of IgA nephropathy patients

BACKGROUND

Renal biopsy remains the golden standard for diagnosing and monitoring IgA nephropathy (IgAN). Vascular endothelial growth factor A (VEGFA) was crucial for the survival of glomerular cells. Our aim was to screen the expression pattern of urinary, circulating and renal VEGFA in IgAN patients to reveal their relationship with renal pathology and outcomes.

METHODS

Baseline VEGFA levels were determined with ELISA, real-time PCR and immunohistochemistry. Associations between VEGFA expression and clinical-pathological parameters, and renal outcomes were evaluated.

RESULTS

Compared with healthy controls, urinary VEGFA level was obviously elevated in IgAN patients (76.19 ± 63.67 pg/mg Cr vs 146.67 ± 232.71 pg/mg Cr, p = 0.0291) and not correlated with serum VEGFA level. Baseline urinary VEGFA was significantly associated with gender and tubular atrophy/interstitial fibrosis by stepwise multivariate regression analysis. Urinary VEGFA was higher in male patients accompanied with higher serum creatinine, larger proportion of hypertension and recurrent hematuria than in female patients. In the kidney of IgAN patients, VEGFA were robustly expressed in the parietal epithelial cells, podocytes, mesangial cells and tubular epithelial cells. After a follow-up duration of 38.53 ± 27.14 months, IgAN patients with higher urinary VEGFA level were found to have a poorer renal outcome of renal replacement therapy (HR = 1.027, p = 0.037) or composite outcome (HR = 1.023, p = 0.039) after adjusting for confounders.

CONCLUSIONS

Increased urinary VEGFA might reflect certain renal pathology and, although not fully specific, still could be served as a valuable noninvasive indicator in predicting renal progression of IgAN.

Contribution of functional and quantitative genetic variants of Complement Factor H and Factor H-Related (FHR) proteins on renal pathology

The complement system is a first line of defence against infectious, tumoral or autoimmune processes, and it is constitutively regulated to avoid excessive or unspecific activation. Factor H (FH), a most relevant complement regulator, controls complement activation in plasma and on the cellular surfaces of autologous tissues. FH shares evolutionary origin and structural features with a group of plasma proteins known as FH-Related Proteins (FHRs), which could act as FH functional antagonists. Studies in patient cohorts of atypical Haemolytic-Uraemic Syndrome (aHUS), C3 Glomerulopathy (C3G), and IgA nephropathy (IgAN), have identified rare genetic variants that give rise to severe FH and FHRs dysfunctions, and are major genetic predisposing factors. These patients also have a higher frequency of a few polymorphisms whose relevance as disease risk factors is incompletely understood. In the last years, the availability of specific reagents has allowed a more precise quantitation of FH and FHRs in plasma samples from patients and controls. These studies have revealed that some aHUS, C3G or IgAN risk polymorphisms determine mild changes in FH or FHRs levels that could somehow perturb complement regulation and favour disease pathogenesis.

MIR17HG genetic variations affect the susceptibility of IgA nephropathy in Chinese Han people

BACKGROUND

Immunoglobulin A nephropathy (IgAN) is the most common primary glomerular disease worldwide. It accounts for approximately 30 ~ 40% of glomerular diseases in China. However, the exact pathogenesis of IgAN is not well established. This study aimed to explore the association between MIR17HG polymorphisms and IgAN susceptibility.

METHODS

Six single nucleotide polymorphisms (SNPs) of MIR17HG were genotyped in 417 patients with IgAN and 424 healthy controls. The association analysis was conducted by logistic regression adjusted for age and gender in multiple genetic models and different subgroups.

RESULTS

Our results revealed that rs72640334 and rs1428 increased the susceptibility to IgAN in total populations (p < 0.05). The stratification analysis by age indicated that rs72640334 enhanced the risk of IgAN people older than 35 years, while rs7318578 played a protective role in the development of IgAN patients aged >35 years (p < 0.05). In addition, MIR17HG-rs72640334 could facilitate the occurrence of IgAN in females (p < 0.05). In Lee's grade III-Vsubgroup, rs72640334 and rs7336610 have an increasing effect on IgAN risk, while rs7318578 has a decreasing effect on IgAN susceptibility (p < 0.05).

CONCLUSIONS

Our findings suggested that MIR17HG genetic polymorphisms were correlated with IgAN susceptibility. It provided new evidence for the potential molecular mechanism of IgAN and may serve as a new biomarker for the treatment and early diagnosis of IgAN.

The Role of Renal Macrophage, AIM, and TGF-β1 Expression in Renal Fibrosis Progression in IgAN Patients

Objective

To analyze the expression of macrophages, AIM, TGF-β1 in the kidney of IgAN patients, and to explore the role of macrophages, AIM, TGF-β1 in the progression of renal fibrosis in IgAN patients.

Methods

The paraffin specimens of renal tissue from 40 IgAN patients were selected as the observation group. At the same time, paraffin specimens of normal renal tissue from 11 patients treated by nephrectomy were selected as the normal control group. We observed the distribution of macrophages, the expression of AIM and TGF-β1 by immunohistochemical staining and/or immunofluorescence.

Result

The number of M0, M1, M2 macrophages could be found increased in IgAN patients. M0 macrophages are mainly polarized towards M2 macrophages. The expression of AIM and TGF-β1 were significantly higher in IgAN patients than in NC. M2 macrophage, AIM and TGF-β1 were positively correlated with serum creatinine and 24-hour proteinuria, but negatively correlated with eGFR. M2 macrophages, AIM, TGF-β1 were positively correlated with fibrotic area.

Conclusion

M2 macrophages, AIM and TGF-β1 play important roles in the process of IgAN fibrosis, and the three influence each other.

Clinicopathological significance of glomerular capillary IgA deposition in childhood IgA nephropathy

BACKGROUND

IgA nephropathy (IgAN) is characterized by predominant mesangial IgA deposition. Some patients with IgAN demonstrate IgA deposition in glomerular peripheral capillaries (cap-IgA). The clinicopathological significance of cap-IgA remains incompletely investigated in children.

METHODS

We retrospectively analyzed 503 consecutive cases of biopsy-proven childhood IgAN between July 1976 and June 2013 to compare clinical and pathological features between IgAN patients with and without cap-IgA.

RESULTS

Among the 503 patients, 30 (6.0%) had cap-IgA. We found significant differences in proteinuria (2.0 vs. 0.5 g/day/m², p < 0.0001), time from onset to kidney biopsy (2.2 vs. 8.3 months, p < 0.0001), and rate of proteinuria remission after treatment (23.3% vs. 48.0%, p = 0.007) between both groups. Pathological analysis revealed significant differences in M1 (83.3% vs. 56.0%, p = 0.002), ratio of subendothelial electron dense deposits (EDDs, 58.6% vs. 16.5%, p < 0.0001) and subepithelial EDDs (48.3% vs. 16.5%, p = 0.0001), and glomerular basement membrane (GBM) lysis (58.6% vs. 27.1%, p = 0.0006) between both groups. More than half of cap-IgA patients (17/30, 56.7%), whereas only 26.2% of non-cap-IgA patients (124/473), were treated with immunosuppressive treatments. Six of 30 cases (20%) with cap-IgA reached glomerular filtration rate (GFR) categories G3a-G5 (estimated GFR < 60 ml/min/1.73 m²) at most recent observation (mean observation period: 7.0 ± 4.0 years). According to Kaplan-Meier analysis, patients with cap-IgA had significantly lower kidney survival curves than non-cap-IgA patients (72.8% vs. 97.2% at 10 years, p < 0.0001).

CONCLUSIONS

Cap-IgA is associated with acute inflammation with GBM changes, resulting in refractory heavier proteinuria. Cap-IgA may represent a poor prognostic factor.

Hematuria was a high risk for renal progression and ESRD in immunoglobulin a nephropathy: a systematic review and meta-analysis

Background: The relationship between hematuria, a typical presentation of immunoglobulin A nephropathy (IgAN), and long-term adverse prognosis of these patients is still controversial. This meta-analysis aims to clarify the effect of hematuria on renal outcomes in IgAN.

Methods: Observational cohort studies reporting associations between various forms of hematuria and renal outcomes among IgAN patients were identified from the PubMed and Embase databases. The pooled adjusted risk ratios (RRs) were computed with random effects models.

Results: Thirteen studies encompassing 5660 patients with IgAN were included. Patients with initial hematuria did not have a significantly increased risk of developing end-stage renal disease (ESRD) compared with those without hematuria (RR, 1.32; 95% CI, 0.87–2.00; p = .19). However, initial microscopic hematuria was associated with an 87% increase in the risk of ESRD (RR, 1.87; 95% CI, 1.40–2.50; p < .001), while macroscopic hematuria was associated with a 32% decrease in the risk of ESRD (RR, 0.68; 95% CI, 0.58–0.79; p < .001). Additionally, persistent hematuria might be an independent risk factor for ESRD or a 50% decline in eGFR.

Conclusions: Among IgAN patients, hematuria, including initial microscopic hematuria and even persistent hematuria, was possibly associated with renal progression and ESRD. However, independent of other classical predictors, initial macroscopic hematuria might be a protective factor for IgAN.

Differential expression of microRNA miR-150-5p in IgA nephropathy as a potential mediator and marker of disease progression

Understanding why certain patients with IgA nephropathy progress to kidney failure while others maintain normal kidney function remains a major unanswered question. To help answer this, we performed miRNome profiling by next generation sequencing of kidney biopsies in order to identify microRNAs specifically associated with the risk of IgA nephropathy progression. Following sequencing and validation in independent cohorts, four microRNAs (-150-5p, -155-5p, -146b-5p, -135a-5p) were found to be differentially expressed in IgA nephropathy progressors compared to non-progressors, and patients with thin membrane nephropathy, lupus nephritis and membranous nephropathy, and correlated with estimated glomerular filtration rate, proteinuria, and the Oxford MEST-C scores (five histological features that are independent predictors of clinical outcome). Each individual microRNA increased the discrimination score of the International IgAN Prediction Tool, although due to the small number of samples the results did not reach statistical significance. miR-150-5p exhibited the largest amplitude of expression between cohorts and displayed the best discrimination between IgA nephropathy progressors and non-progressors by receiver operating curve analysis (AUC: 0.8). However, expression was similarly upregulated in kidneys with established fibrosis and low estimated glomerular filtration rates at the time of biopsy. Consistent with a more generic role in kidney fibrosis, in situ hybridization revealed that miR-150-5p was found in lymphoid infiltrates, and areas of proliferation and fibrosis consistent with the known drivers of progression. Thus, miR-150-5p may be a potential functional mediator of kidney fibrosis that may add value in predicting risk of progression in IgA nephropathy and other kidney diseases.

Glomerular C4d in Post-Transplant IgA Nephropathy is associated with decreased allograft survival

Background

Glomerulonephritis (GN), including post-transplant IgAN (post-Tx IgAN) is an important contributor to decreased long-term allograft survival. The immunopathological detection of the complement degradation product C4d in glomeruli (C4dG) has been recently described as a risk factor in native kidney IgAN, however little is known about C4dG deposition in post-Tx IgAN. We hypothesized that glomerular C4d may indicate a more aggressive disease course and worse allograft survival in patients with post-Tx IgAN.

Methods

In this retrospective study we assessed the presence and clinical relevance of C4dG in patients with post-transplant IgAN. We analyzed 885 renal allograft recipients, including 84 patients with post-transplant GN. All patients were transplanted between January 1999 and April 2006 and underwent at least one biopsy for differnt causes. The primary endpoint was death-censored graft survival, with a median follow-up of 9.6 (IQR 3.8–13.2) years.

Results

The prevalence of post-Tx GN was 9.5%. Twenty-seven patients with post-Tx IgAN were included. C4dG positive patients (N = 18, 66.7%) had significantly worse allograft survival compared to C4dG negative post-Tx IgAN patients and patients without post-Tx IgAN [C4dG positive: 27.8% vs. 55.6% and 66.0%; log-rank: p = 0.01]. C4dG remained a significant risk factor (HR 2.22, 95% CI 1.27–3.87) for allograft loss even after adjustment for T cell mediated rejection (TCMR) and antibody mediated rejection.

Conclusion

Glomerular C4d deposition is an independent risk factor for worse graft-survival in patients with post-Tx IgAN, even after adjusting for other risk factors such as antibody mediated rejection.  Assessment of glomerular C4d deposition may provide a valuable prognostic risk assessment tool to identify high risk patients in post-Tx IgAN.

Graphic abstract

Electronic supplementary material

The online version of this article (10.1007/s40620-020-00914-x) contains supplementary material, which is available to authorized users.

Emerging Modes of Treatment of IgA Nephropathy

IgA nephropathy is the most common primary glomerulonephritis with potentially serious outcome leading to end stage renal disease in 30 to 50% of patients within 20 to 30 years. Renal biopsy, which might be associated with risks of complications (bleeding and others), still remains the only reliable diagnostic tool for IgA nephropathy. Therefore, the search for non-invasive diagnostic and prognostic markers for detection of subclinical types of IgA nephropathy, evaluation of disease activity, and assessment of treatment effectiveness, is of utmost importance. In this review, we summarize treatment options for patients with IgA nephropathy including the drugs currently under evaluation in randomized control trials. An early initiation of immunosupressive regimens in patients with IgA nephropathy at risk of progression should result in the slowing down of the progression of renal function to end stage renal disease.

Glomerular Complement Factor H-Related Protein 5 is Associated with Histologic Injury in Immunoglobulin A Nephropathy

Introduction

Immunoglobulin A nephrology (IgAN), characterized by co-deposition of IgA and complement components, is an activation of complement system involved disease. Factor H-related protein 5 (FHR-5) antagonized the ability of factor H to negatively regulate C3 activation, which leads to overactivation of the alternative pathway. Here we explore the relationship of intensity of glomerular FHR-5 deposition and severity of IgAN.

Methods

Renal staining of FHR-5 was detected by immunofluorescence, and plasma FHR-5 was detected by enzyme-linked immunosorbent assay in 56 patients with IgAN. The relationship of intensity of glomerular FHR-5 and clinical and pathologic features of these patients were further analyzed.

Results

Glomerular staining for FHR-5 was observed in a predominantly mesangial pattern in 32 biopsy specimens (57.1%). FHR-5 co-deposited with IgA and C3c in glomerular mesangial and capillary area in patients with IgAN. Patients with IgAN with Oxford endocapillary hypercellularity (P = 0.007) and segmental glomerulosclerosis (P = 0.049) presented with greater intensity of FHR-5 deposition. There were more cases with 2+ and 3+ FHR-5 staining in cohorts of 2+ and 3-4+ mesangial C3 deposition (P = 0.034) and IgA deposition (P = 0.019). Interestingly, the glomerular FHR-5 depositions were more abundant in male versus female in patients with IgAN (P = 0.002). Besides, circulating FHR-5 levels were elevated in patients with IgAN compared with healthy control subjects. Plasma FHR-5 levels were significantly higher in patients with mesangial hypercellularity at diagnosis than those with nonmesangial hypercellularity.

Conclusions

We found that glomerular intensity of FHR-5 deposition could indicate the severity of histologic lesions of IgAN.

[Study on molecular target of Taohong Siwu Decoction in delaying growth of fibroblasts based on network pharmacology]

As a prescription for promoting blood circulation and removing blood stasis, Taohong Siwu Decoction(THSWD) has certain effects in delaying the progression of renal fibrosis. However, as a traditional Chinese medicine compound containing many monomer components, it has been a research hotspot in the field of exploring the research methods and targets for the complex pathological process. The method of activating blood circulation and removing blood stasis has certain clinical effect in retarding the process of IgA nephropathy(IgAN) fibrosis, but the mechanism of action is still unclear. In this study, the network pharmacology method was used to investigate the active ingredients, targets and molecular mechanisms of THSWD in the intervention of IgAN fibrosis. On this basis, in vitro experiments were conducted to verify the effect of THSWD on the expression of ERK factor in BALB/c 3 T3 cells. The active ingredients and targets in THSWD were collected through the TCMSP. Sixty-one active ingredients and 240 targets including luteolin and quercetin were screened, and 185 targets were obtained by intersecting with CTD database to search IgAN related targets. Cytoscape software and STRING database were used to construct &quot;THSWD-active ingredients-targets&quot; network and protein-protein interaction network, and 69 core targets were screened. In DAVID's GO enrichment analysis and KEGG pathway analysis of the core targets and cell experiments, the results showed that ERK was an important factor for THSWD to interfere with IgAN fibrosis, and THSWD intervention could significantly decrease cell activity, ERK1/2 mRNA expression, and p-ERK1/2 protein expression. This study preliminarily revealed that THSWD may delay the growth of fibroblasts by affecting ERK factor and its phosphorylation level.

MicroRNA-27a-3p directly targets FosB to regulate cell proliferation, apoptosis, and inflammation responses in immunoglobulin a nephropathy

Immunoglobulin A nephropathy (IgAN) constitutes the most common primary glomerulonephritis worldwide; however, the exact pathogenesis of IgAN is unknown. Previous genome-wide analysis of microRNA (miRNA) expression in the kidney has confirmed that miRNAs are closely related to the pathological changes of IgAN. Accordingly, in this study we found that miR-27a-3p is upregulated in IgAN kidney tissues in addition to human podocytes and tubule epithelial HK2 but not mesangial cells. Methylthiazolyldiphenyl-tetrazolium bromide (MTT), flow cytometry, real-time polymerase chain reaction, western blot, and enzyme-linked immunosorbent assays were used to verify the regulatory effects of miR-27a-3p and its inhibition on cell proliferation, apoptosis, and release of inflammatory factors in podocytes and HK2 cells. The target genes of miR-27a-3p were predicted using bioinformatics software; the identity of FosB as a target gene of miR-27a-3p was confirmed by luciferase report assay and western blot. Overall, our findings demonstrated that miR-27a-3p regulates cell apoptosis, cell proliferation, and the release of inflammatory cytokines of human podocytes and HK2 cells by directly targeting FosB. Our results therefore suggested that miR-27a-3p might be associated with the pathophysiology of IgAN and may represent a potential target for further studies related to IgAN mechanism or therapeutics.

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.

After ten years of follow-up, no difference between supportive care plus immunosuppression and supportive care alone in IgA nephropathy

The randomized, controlled STOP-IgAN trial in patients with IgA nephropathy (IgAN) and substantial proteinuria showed no benefit of immunosuppression added on top of supportive care on renal function over three years. As a follow-up we evaluated renal outcomes in patients over a follow-up of up to ten years in terms of serum creatinine, proteinuria, end-stage kidney disease (ESKD), and death. The adapted primary endpoint was the time to first occurrence of a composite of death, ESKD, or a decline of over 40% in the estimated glomerular filtration rate (eGFR) compared to baseline at randomization into STOP-IgAN. Data were analyzed by Cox-regression models. Follow-up data were available for 149 participants, representing 92% of the patients originally randomized. Median follow-up was 7.4 years (inter quartile range 5.7 to 8.3 years). The primary endpoint was reached in 36 of 72 patients randomized to supportive care and 35 of 77 patients randomized to additional immunosuppression (hazard ratio 1.20; 95% confidence interval 0.75 to 1.92). ESKD occurred in 17 of the patients with supportive care and in 20 of the patients with additional immunosuppression. Additionally, the rates of eGFR loss over 40% and annual eGFR loss did not differ between groups. Two patients died with supportive care and three with additional immunosuppression. Thus, within the limitations of a retrospective study, over a follow-up of up to ten years, and using an adapted primary endpoint, we failed to detect differences in key clinical outcomes in IgAN patients randomized to receive added immunosuppression on top of supportive care versus supportive care alone.

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.

Co-delivery of p38α MAPK and p65 siRNA by novel liposomal glomerulus-targeting nano carriers for effective immunoglobulin a nephropathy treatment

Glomerulonephritis related renal failure is a frequent cause of end-stage renal disease, and immunoglobulin A nephropathy (IgAN) is the most frequent type of primary glomerulonephritis. As damage induced by IgAN mostly attributes to inflammation responses, inhibiting inflammation in glomerulus can protect normal renal function and delay the onset of renal failure. Hence, reducing levels of p38 MAPK and p65 which are essential regulators in p38 MAPK and NF-κB related inflammation responses could be effective against IgAN. Here, we rationally designed and constructed size- and surface charge- dependent glomerulus-targeting liposomal nanoparticles which are loaded with both p38α MAPK and p65 siRNA. Experiments show that our nanoparticles successfully crossed fenestrated endothelium, accumulated in mesangial cells and endothelial cells, efficiently silenced p38α MAPK and p65 genes, and eventually alleviated proteinuria, inflammation and excessive extracellular matrix deposition in mouse IgAN models. This siRNA co-delivery system thus represents a promising treatment option for IgAN and offers a versatile platform for other glomerular problems. Our work also highlights a novel strategy of glomerulus-targeting and an encouraging therapeutic route for other inflammatory diseases.

Association between VDR gene FokI polymorphism and renal function in patients with IgA nephropathy

Background

Studies have shown that the occurrence and development of IgA nephropathy (IgAN) are genetically susceptible, but the relationship between vitamin D receptor (VDR) gene polymorphisms and renal function in IgAN patients is unclear.

Methods

We investigated the relationship between VDR FokI (rs2228570) single nucleotide polymorphism (SNP) and renal function and related clinicopathologic parameters in IgAN patients. Clinical and pathological data of 282 IgAN patients treated at the First Affiliated Hospital of Guangxi Medical University were collected, and FokI genotypes were determined by PCR and direct sequencing. Patients were divided into the renal dysfunction group and normal renal function (control) group by estimated glomerular filtration rate (eGFR) and serum creatinine level.

Results

Frequencies of TT genotype and T allele in the renal dysfunction group were higher than those of the control group. Blood urea nitrogen, serum phosphorus (P), proportions of mesangial cell proliferation, interstitial fibrosis/tubular atrophy and crescents in T allele carriers were higher than those in non-T allele carriers, while eGFR and 25-Hydroxyvitamin D3 were lower in T allele carriers than non-T allele carriers. Multiple linear regression analysis showed that eGFR was affected by FokI genotypes in IgAN patients. Logistics regression analysis showed that middle and elderly age, elevated P, intact parathyroid hormone and TT genotype were independent risk factors for renal dysfunction in IgAN patients; the odds ratio of carrying the TT genotype was as high as 84.77 (P < 0.05 for all).

Conclusions

IgA nephropathy patients carrying the VDR FokI TT genotype have an increased risk of renal dysfunction. VDR FokI SNP is closely related to renal function, calcium-phosphate metabolism, and related pathological damage in IgAN patients.

Role of Mesangial-Podocytic-Tubular Cross-Talk in IgA Nephropathy

IgA nephropathy (IgAN), a common primary glomerulonephritis worldwide, is associated with a substantial risk of progression to end-stage renal failure. The disease runs a highly variable clinical course with frequent involvement of tubulointerstitial damage. A subgroup of IgAN with proximal tubular epithelial cells (PTECs) and tubulointerstitial damage often is associated with rapid progression to end-stage renal failure. Human mesangial cell-derived mediators lead to podocyte and tubulointerstitial injury via mesangial-podocytic-tubular cross-talk. Although mesangial-podocytic communication plays a pathogenic role in podocytic injury, the implication of a podocyte-PTEC cross-talk pathway in the progression of tubulointerstitial injury in IgAN should not be underscored. We review the role of mesangial-podocytic-tubular cross-talk in the progression of IgAN. We discuss how podocytopathy in IgAN promotes subsequent PTEC dysfunction and whether tubulointerstitial injury affects the propagation of podocytic injury in IgAN. A thorough understanding of the cross-talk mechanisms among mesangial cells, podocytes, and PTECs may lead to better design of potential therapeutic options for IgAN.

The Emerging Role of Complement Proteins as a Target for Therapy of IgA Nephropathy

IgA nephropathy (IgAN) is the most common form of primary glomerulonephritis worldwide and a common cause of end-stage renal disease. Evaluation of a kidney biopsy is necessary for diagnosis, with routine immunofluorescence microscopy revealing dominant or co-dominant IgA immunodeposits usually with complement C3 and sometimes IgG and/or IgM. IgA nephropathy reduces life expectancy by more than 10 years and leads to kidney failure in 20–40% of patients within 20 years of diagnosis. There is accumulating clinical, genetic, and biochemical evidence that complement plays an important role in the pathogenesis of IgA nephropathy. The presence of C3 differentiates the diagnosis of IgA nephropathy from the subclinical deposition of glomerular IgA. Markers for the activation of the alternative and mannan-binding lectin (MBL) pathways in renal-biopsy specimens are associated with disease activity and portend a worse renal outcome. Complement proteins in the circulation have also been evaluated in IgA nephropathy and found to be of prognostic value. Recently, genetic studies have identified IgA nephropathy-associated loci. Within these loci are genes encoding products involved in complement regulation and interaction with immune complexes. Put together, these data identify the complement cascade as a rational treatment target for this chronic kidney disease. Recent case reports on the successful use of humanized anti-C5 monoclonal antibody eculizumab are consistent with this hypothesis, but a better understanding of the role of complement in IgA nephropathy is needed to guide future therapeutic interventions.

Renal outcomes of STOP-IgAN trial patients in relation to baseline histology (MEST-C scores)

Background

The Oxford classification of IgA nephropathy (IgAN) defines histologic criteria (MEST-C) that provide prognostic information based on the kidney biopsy. There are few data on the predictive impact of this classification in randomized clinical trial settings.

Methods

We performed an exploratory analysis of MEST-C scores in 70 available renal biopsies from 162 randomized STOP-IgAN trial participants and correlated the results with clinical outcomes. Analyses were performed by researchers blinded to the clinical outcome of the patients. Biopsies had been obtained 6.5 to 95 (median 9.4) months prior to randomization.

Results

Mesangial hypercellularity (M1) associated with higher annual eGFR-loss during the 3-year trial (M1: − 5.06 ± 5.17 ml/min/1.73 m², M0: − 0.79 ± 4.50 ml/min/1.73 m², p = 0.002). An M0-score additionally showed a weak association with full clinical remission, whereas the percentage of patients losing ≥15 ml/min/1.73 m² over the 3-year trial phase was higher among those scored as M1. Among patients with additional immunosuppression, ESRD occurred more frequently in patients when tubulointerstitial fibrosis (T1/2) was present (T1/2 = 33%, T0 = 0%, p = 0.008). In patients receiving supportive care only, ESRD frequencies were similar (T1/2 = 18%, T0 = 7%, p = 0.603). At randomization, eGFR was significantly lower when tubulointerstitial fibrosis was present (T1/2: 45.2 ± 15.7 ml/min/1.73 m², T0: 74.6 ± 28.2 ml/min/1.73 m², p < 0.0001). Endocapillary hypercellularity (E), and glomerular segmental sclerosis (S) were not associated with any clinical outcome parameter. In the analyzed cohort, patients with glomerular crescents (C1/2 scores) in their biopsies were more likely to develop ESRD during the 3-year trial phase, but this trend was only significant in patients under supportive care.

Conclusions

This secondary analysis of STOP-IgAN biopsies indicates that M1, T1/2 and C1/2 scores associate with worse renal outcomes.

Complement C3 Produced by Macrophages Promotes Renal Fibrosis via IL-17A Secretion

Complement synthesis in cells of origin is strongly linked to the pathogenesis and progression of renal disease. Multiple studies have examined local C3 synthesis in renal disease and elucidated the contribution of local cellular sources, but the contribution of infiltrating inflammatory cells remains unclear. We investigate the relationships among C3, macrophages and Th17 cells, which are involved in interstitial fibrosis. Here, we report that increased local C3 expression, mainly by monocyte/macrophages, was detected in renal biopsy specimens and was correlated with the severity of renal fibrosis (RF) and indexes of renal function. In mouse models of UUO (unilateral ureteral obstruction), we found that local C3 was constitutively expressed throughout the kidney in the interstitium, from which it was released by F4/80⁺macrophages. After the depletion of macrophages using clodronate, mice lacking macrophages exhibited reductions in C3 expression and renal tubulointerstitial fibrosis. Blocking C3 expression with a C3 and C3aR inhibitor provided similar protection against renal tubulointerstitial fibrosis. These protective effects were associated with reduced pro-inflammatory cytokines, renal recruitment of inflammatory cells, and the Th17 response. in vitro, recombinant C3a significantly enhanced T cell proliferation and IL-17A expression, which was mediated through phosphorylation of ERK, STAT3, and STAT5 and activation of NF-kB in T cells. More importantly, blockade of C3a by a C3aR inhibitor drastically suppressed IL-17A expression in C3a-stimulated T cells. We propose that local C3 secretion by macrophages leads to IL-17A-mediated inflammatory cell infiltration into the kidney, which further drives fibrogenic responses. Our findings suggest that inhibition of the C3a/C3aR pathway is a novel therapeutic approach for obstructive nephropathy.

Serum GDIgA1 levels in children with IgA nephropathy and Henoch-Schönlein nephritis

Introduction

GDIgA1 (galactose deficient IgA1) plays a significant role in the pathogenesis of IgA nephropathy (IgAN) and Henoch-Schönlein nephritis (HSN).

Aim of the study

The aim of this study was to assess the relevance of serum GDIgA1 level as a prognostic marker in children with IgAN and HSN.

Material and methods

41 children were included to the study group (15 IgAN, 26 HSN) and 22 to the control group. The following parameters were evaluated at baseline and endpoint: proteinuria, erythrocyturia, serum creatinine, serum IgA, GFR. A kidney biopsy was performed in all patients and evaluated according to the Oxford Classification (1 – present, 0 – absent: M – mesangial hypercellularity; E– endocapillary hypercellularity; S – segmental sclerosis/adhesion; T – tubular atrophy/interstitial fibrosis), and was calculated as the total score (sum of M, E, S, T). At the end of follow-up, the serum GDIgA1 concentration was measured.

Results

The serum GDIgA1 concentration in patients with IgAN and HSN was significantly higher than in the control group. No significant differences in mean proteinuria, erythrocyturia, GFR, MEST score, or GDIgA1 in serum, as well as the duration of follow-up between IgAN and HSN were observed. Baseline serum IgA concentration and time to kidney biopsy were significantly higher in children with IgAN than in children with HSN. We observed a positive correlation between GDIgA1 and IgA levels (r = 0.53), and GDIgA1 and serum creatinine levels (r = 0.5), as well as negative correlation between GDIgA1 and GFR (r = –0.37).

Conclusions

Serum GDIgA1 level may have a prognostic value in children with IgAN and HSN; however, to fully elucidate its clinical potential further studies performed in larger patient cohorts are required.

Patterns of renal disease in South Korea: a 20-year review of a single-center renal biopsy database

Background: Several registries and centers have reported the results of renal biopsies from different parts of the world. As there are few data regarding the epidemiology of glomerulonephritis (GN) in South Korea, we conducted this study on renal biopsy findings during the last 20 years from a single center.

Methods: Data for 818 patients who underwent renal biopsy at our center between 1992 and 2011 were collected retrospectively. All kidney specimens were examined with light microscopy (LM) and immunofluorescent microscopy (IF).

Results: There were 818 cases of native kidney biopsies. In cases of primary GN, the most frequent type of renal pathology in adults (18–59 years) was mesangial proliferative GN (MsPGN, 34.5%) followed by IgA nephropathy (IgAN, 33.3%) and membranous GN (MGN, 8.8%). Indications in adults (18–59 years) were asymptomatic urinary abnormalities (75.3%) followed by nephrotic syndrome (19.8%) and acute kidney injury (AKI, 3.4%).

Conclusions: Among 818 renal biopsy specimens, MsPGN and IgAN were the most frequent biopsy-proven renal diseases. MGN was the third most common cause of primary GN and lupus nephritis (LN) was the most common secondary glomerular disease. Our data contribute to the epidemiology of renal disease in South Korea.

A unique evolution of the kidney phenotype in a patient with autosomal recessive Alport syndrome

Alport syndrome is due to mutations in one of the genes encoding (α3,4,5) type IV collagen resulting in defective type IV collagen, a key component of the glomerular basement membrane (GBM). The GBM is initially thin and, with ongoing remodeling, develops a thickened basket-woven appearance. We report a unique case of a 9-year-old boy who underwent biopsy for hematuria and proteinuria, diagnosed as IgA nephropathy, with normal GBM appearance and thickness. Because of a family history of hematuria and chronic kidney disease, he subsequently underwent genetic evaluation, and a mutation of α3 type IV collagen (COL4A3) was detected. Additional studies of the initial biopsy demonstrated abnormal type IV collagen immunostaining. A repeat biopsy 4 years later showed characteristic glomerular basement membrane morphology of Alport syndrome and scarring consistent with sequelae of IgA nephropathy. This is the first description of this unusual transition from an initial normal appearance of the glomerular basement membrane to the classic Alport phenotype.

CTLA-4 Polymorphisms in Patients with IgA Nephropathy Correlate with Proteinuria

BACKGROUND/AIMS

IgA nephropathy (IgAN) is the most common form of primary glomerulonephritis and still constitutes one of the most important causes of end-stage renal disease. Abnormal T cell responses may play a role in IgAN pathogenesis. Co-stimulatory molecules such as cytotoxic T lymphocyte-associated antigen 4 (CTLA-4) are important for naive T cells to initiate and terminate immune responses. Single nucleotide polymorphisms (SNPs) in the CTLA4 gene locus are associated with several autoimmune diseases.

METHODS

We aimed to investigate the occurrence of the SNPs -318C/T, +49A/G and CT60 G/A within the CTLA4 locus in healthy blood donors (n=455) and IgAN patients (n=252) recruited from the recently published STOP-IgAN trial. The presence of these SNPs was then associated with baseline proteinuria in IgAN patients.

RESULTS

We observed a significantly increased frequency of the CTLA4 -318C/T genotype in IgAN patients as compared to controls (CC vs. CT+TT: OR 1.65, 95%-CI 1.03-2.65, p=0.035). No significant associations, neither with the +49A/G nor for the CT60 G/A SNP, were detected. However, when we stratified for proteinuria at time of inclusion into the STOP-IgAN trial (<1 g/day vs. >1 g/day), we observed significant differences in the frequencies of the CT60 G/A genotype, i.e. a significantly increased risk for higher proteinuria in patients carrying the G allele (OR 2.81, 95%-CI 1.03-7.64, p=0.042).

CONCLUSION

The CTLA4 -318/C/T SNP was associated with an increased risk to develop IgAN, while the CT60 G/A genotype significantly associated with the risk for higher proteinuria suggesting a possible role for CTLA-4 in IgAN.