Pathogenesis of IgA nephropathy

Insights into non-coding RNAS: biogenesis, function and their potential regulatory roles in acute kidney disease and chronic kidney disease

Noncoding RNAs (ncRNAs) have emerged as pivotal regulators of gene expression, and have attracted significant attention because of their various roles in biological processes. These molecules have transcriptional activity despite their inability to encode proteins. Moreover, research has revealed that ncRNAs, especially microRNAs (miRNAs), long noncoding RNAs (lncRNAs), and circular RNAs (circRNAs), are linked to pervasive regulators of kidney disease, including anti-inflammatory, antiapoptotic, antifibrotic, and proangiogenic actions in acute and chronic kidney disease. Although the exact therapeutic mechanism of ncRNAs remains uncertain, their value in treatment has been studied in clinical trials. The numerous renal diseases and the beneficial or harmful effects of NcRNAs on the kidney will be discussed in this article. Afterward, exploring the biological characteristics of ncRNAs, as well as their purpose and potential contributions to acute and chronic renal disease, were explored. This may offer guidance for treating both acute and long-term kidney illnesses, as well as insights into the potential use of these indicators as kidney disease biomarkers.

Integrative multi-omics and network pharmacology reveal the mechanisms of Fangji Huangqi Decoction in treating IgA nephropathy

ETHNOPHARMACOLOGICAL RELEVANCE

Fangji Huangqi Decoction (FJHQD), a classical Chinese herbal formulation, has demonstrated significant clinical efficacy in the treatment of IgA nephropathy (IgAN), although its mechanisms remain poorly understood.

AIM OF THE STUDY

This study aims to investigate the renal protective mechanisms of FJHQD using an integrated approach that combines transcriptomics, proteomics, and network pharmacology.

METHODS

Renal glomerular structure changes were assessed via hematoxylin and eosin (H&E) and Masson staining. IgA expression in the glomeruli was quantified using immunofluorescence. Furthermore, the potential mechanisms underlying the effects of FJHQD were explored through a combined strategy of network pharmacology, transcriptomics, and proteomics. The expression of signaling pathway-related proteins was detected using Western blot.

RESULTS

FJHQD inhibited mesangial cell proliferation and renal interstitial fibrosis, and significantly reduced excessive IgA deposition in the glomerular mesangium. Network pharmacology identified 113 important active components and 8 common active components in FJHQD, with quercetin, isorhamnetin, jaranol, and kaempferol having the highest number of target interactions. Integration of network pharmacology with multi-omics approaches revealed that 44 active components regulated numerous immune and inflammatory signaling pathways through 17 hub targets. These pathways include the Calcium signaling pathway, cAMP signaling pathway, Ras signaling pathway, MAPK signaling pathway, and PI3K-AKT signaling pathway. Subsequent in vivo experiments demonstrated that FJHQD effectively regulates the identified pathways in IgAN mice. Ultimately, molecular docking results further validated the reliability of the network pharmacology combined with multi-omics analyses.

CONCLUSION

The findings suggest that FJHQD exerts a renal protective effect, potentially through modulation of the Calcium signaling pathway, cAMP signaling pathway, Ras signaling pathway, MAPK signaling pathway, and PI3K-AKT signaling pathway. These insights offer valuable support for the clinical use of FJHQD and open new avenues for exploring the active compounds and molecular mechanisms of Traditional Chinese Medicines (TCMs).

Post-transplant IgA nephropathy: a rapidly evolving field of kidney transplant medicine

IgA nephropathy is the commonest pattern of primary glomerular disease in the world, with high rates of progression to kidney failure. As IgA nephropathy commonly causes kidney failure at a young age, kidney transplantation is commonly used to treat kidney failure. However, high rates of recurrent disease in the allograft remain a common management challenge. The prevalence of post-transplant recurrence approaches 15% at ten years post-transplant and is associated with poor allograft function and high rates of allograft loss. Post-transplant IgA nephropathy has also been described de novo in some case series. Treatment of recurrent IgA nephropathy has been challenging but with the rapid growth of new treatments for IgA nephropathy it is likely that many of these treatments will, over time, transition to the treatment of recurrent disease. In this narrative review, our aim is to evaluate post-transplant IgA nephropathy in terms of epidemiology, risk factors, underlying pathophysiology, diagnosis and management strategies.

An inflammatory cytokine signature predicts IgA nephropathy severity and progression

IgA nephropathy (IgAN) is the most prevalent primary glomerulonephritis, resulting in end-stage renal disease and increased mortality rates. Prognostic biomarkers reflecting molecular mechanisms for effective IgAN management are urgently needed. Analysis of kidney single-cell transcriptomic sequencing data demonstrated that IgAN expressed high-expression levels of inflammatory cytokines TNFSF10, TNFSF12, CCL2, CXCL1, and CXCL12 than healthy controls (HCs). We also measured the urine proteins in 120 IgAN (57 stable and 63 progressive) and 32 HCs using the proximity extension assay (PEA), and the multivariable and least absolute shrinkage and selection operator (LASSO) logistic regression analysis both revealed that CXCL12, MCP1 were the prognostic significant variables to predict IgAN progression severity. These two proteins exhibited negative correlation with the estimated glomerular filtration rate (eGFR) and patients with higher expression levels of these two proteins had a higher probability to have poorer renal outcome. We further developed a risk index model utilizing CXCL12, MCP1, and baseline clinical indicators, which achieved an impressive area under the curve (AUC) of 0.896 for prediction of IgAN progression severity. Our study highlights the significance of the inflammatory protein biomarkers for noninvasive prediction of IgAN severity and progression, offering valuable insights for clinical management.

Relationship between serum IgA levels and low percentage forced expiratory volume in the first second in asthma

Objective: Immunoglobulin A (IgA) is suggested to have pathogenic effects in respiratory inflammatory diseases, including asthma. We aimed to analyze the relationship between serum IgA, and clinical indicators and biomarkers of asthma.Methods: This study was a post hoc analysis of the NHOM Asthma Study. In this study, serum IgA was measured using serum samples stored. We determined an association between the serum IgA level and clinical variables and biomarkers using multivariate linear regression and analyzed the differences in clinical indices between IgA high- and IgA low-asthma.Results: In this study, 572 patients with asthma were included in the final analysis. Lower percentage forced expiratory volume in the first second (%FEV1), higher serum eotaxin levels, lower serum ST2 levels, and higher serum MIP-1β levels, were independently and significantly associated with higher serum IgA levels among asthma patients by multivariate linear regression analysis (%FEV1, 95% confidence interval [CI], -8.18- -0.613, p < 0.05; eotaxin, 95% CI, 8.95-46.69, p < 0.001; ST2, 95% CI, -73.71- -7.37, p < 0.05; and MIP-1β, 95% CI, 1.47-18.71, p < 0.05). Furthermore, IgA high-asthma (serum IgA ≥ 238 mg/dL, n = 270) and IgA low-asthma (serum IgA < 238 mg/dL, n = 302) were compared separately. %FEV1 was significantly lower, the percentage of atopy was higher, and serum MIP-1β level was higher in IgA high-asthma.Conclusions: This study suggests that serum IgA may be involved in the worsening of asthma outcomes, as assessed by %FEV1 and enhanced inflammation via elevated serum MIP-1β.

Therapy of IgA nephropathy: time for a paradigm change

Immunoglobulin A nephropathy (IgAN) often has a poor outcome, with many patients reaching kidney failure within their lifetime. Therefore, the primary goal for the treatment of IgAN should be to reduce nephron loss from the moment of diagnosis. To achieve this, IgAN must be recognized and treated as both a chronic kidney disease and an immunological disease. Agents that have received US Food and Drug Administration and European Medicines Agency approval for the treatment of IgAN include modified-release/targeted-release formulation budesonide (Nefecon) and sparsentan, a selective dual endothelin-A and angiotensin II receptor type 1 antagonist. Other agents, including selective endothelin receptor antagonists, selective or combined APRIL and BAFF antagonists, and a vast array of complement inhibitors are being investigated for the treatment of IgAN. Furthermore, treatment combinations are also being studied, including sodium-glucose cotransporter-2 inhibitors with endothelin receptor antagonists. Due to the complexity of IgAN, combination treatment, rather than a single-agent approach, may provide maximum benefit. With the number of treatments for IgAN likely to increase, combinations allowing safe and effective treatment to halt progression to kidney failure seem within grasp. While trials evaluating combinations are ongoing, more are needed to pave the way for a comprehensive IgAN treatment strategy. Furthermore, an approach to IgAN treatment in which agents are combined early to achieve rapid induction of remission and prevent unnecessary and irreversible nephron loss is required. Following remission, treatments may be adjusted and stripped back as necessary in the maintenance phase with close monitoring. This review discusses the current status of IgAN treatment and explores future strategies to improve outcomes for patients with IgAN.

Uromodulin and progression of IgA nephropathy

Background

This study investigates the link between genetic variants associated with kidney function and immunoglobulin A (IgA) nephropathy (IgAN) progression.

Methods

We recruited 961 biopsy-proven IgAN patients and 651 non-IgAN end-stage renal disease (ESRD) patients from Ruijin Hospital. Clinical and renal pathological data were collected. The primary outcome was the time to ESRD. A healthy population was defined as estimated glomerular filtration rate >60 mL/min/1.73 m2 without albuminuria or hematuria. Fifteen single-nucleotide polymorphisms (SNPs) were selected from a genome-wide association study of kidney function and genotyped by the SNaPshot. Immunohistochemistry in renal tissue and ELISA in urine samples were performed to explore the potential functions of genetic variations.

Results

The rs77924615-G was independently associated with an increased risk for ESRD in IgAN patients after adjustments for clinical and pathologic indices, and treatment (adjusted hazard ratio 2.10; 95% confidence interval 1.14-3.88). No significant differences in ESRD-free survival time were found among different genotypes in non-IgAN ESRD patients (log-rank, P = .480). Moreover, rs77924615 exhibited allele-specific enhancer activity by dual-luciferase reporter assay. Accordingly, the urinary uromodulin-creatinine ratio (uUCR) was significantly higher in healthy individuals with rs77924615 AG or GG than in individuals with AA. Furthermore, uromodulin expression in tubular epithelial cells was higher in patients with rs77924615 AG or GG. Finally, we confirmed that an increased uUCR (P = .009) was associated with faster IgAN progression.

Conclusion

The SNP rs77924615, which modulates the enhancer activity of the UMOD gene, is associated with renal function deterioration in IgAN patients by increasing uromodulin levels in both the renal tubular epithelium and urine.

Cross-species single-cell analysis uncovers the immunopathological mechanisms associated with IgA nephropathy progression

IgA nephropathy (IgAN) represents the main cause of renal failure, while the precise pathogenetic mechanisms have not been fully determined. Herein, we conducted a cross-species single-cell survey on human IgAN and mouse and rat IgAN models to explore the pathogenic programs. Cross-species single-cell RNA sequencing (scRNA-Seq) revealed that the IgAN mesangial cells (MCs) expressed high levels of inflammatory signatures CXCL12, CCL2, CSF1, and IL-34 and specifically interacted with IgAN macrophages via the CXCL12/CXCR4, CSF1/IL-34/CSF1 receptor, and integrin subunit alpha X/integrin subunit alpha M/complement C3 (C3) axes. IgAN macrophages expressed high levels of CXCR4, PDGFB, triggering receptor expressed on myeloid cells 2, TNF, and C3, and the trajectory analysis suggested that these cells derived from the differentiation of infiltrating blood monocytes. Additionally, protein profiling of 21 progression and 28 nonprogression IgAN samples revealed that proteins CXCL12, C3, mannose receptor C-type 1, and CD163 were negatively correlated with estimated glomerular filtration rate (eGFR) value and poor prognosis (30% eGFR as composite end point). Last, a functional experiment revealed that specific blockade of the Cxcl12/Cxcr4 pathway substantially attenuated the glomerulus and tubule inflammatory injury, fibrosis, and renal function decline in the mouse IgAN model. This study provides insights into IgAN progression and may aid in the refinement of IgAN diagnosis and the optimization of treatment strategies.

Infection-Associated Glomerulonephritis

The nephritic syndrome has been associated with a wide variety of infections, spanning many organisms and myriad clinical presentations. Infection-associated glomerulonephritis is challenging to diagnose given the many confounding factors linking kidney injury to infection; however, urine microscopy can assist in identifying abnormal cellular elements suggestive of glomerulonephritis. Kidney biopsy remains the gold standard for diagnosing the underlying pathologic lesion. Treatment of infection-associated glomerulonephritis centers around aggressive and complete treatment of the underlying infectious driver. It is often hard to know exactly when immunosuppression may be required in addition to treating the infection.

Network pharmacology and molecular docking to elucidate the common mechanism of hydroxychloroquine treatment in lupus nephritis and IgA nephropathy

OBJECTIVE

Hydroxychloroquine (HCQ), characterized by a broad effect on immune regulation, has been widely used in the treatment of autoimmune glomerulonephritis such as lupus nephritis (LN) and immunoglobulin A nephropathy (IgAN). The current research investigates whether HCQ plays a role in the treatment of LN and IgAN through common mechanisms since the pathogenesis of both LN and IgAN is closely related to immune complex deposition, complement activation, and ultimately inflammation.

METHODS

Seventy-two common targets were obtained related to the common mechanism of HCQ treatment of LN and IgAN. Targets associated with LN and IgAN were collected based on DisGeNET, GeneCards, and OMIM databases. Possible HCQ targets were obtained from the PubChem database and PharmMapper databases. The overlapping targets of HCQ ingredients, IgAN, and LN were discovered via the Venn 2.1.0 online platform. Through the DAVID database, the Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were conducted. Cytoscape (v3.9.1) was used to build a protein-protein interaction (PPI) network. Molecular docking was performed by using AutoDockTools 1.5.6 software and PyMol software to match the binding activity between HCQ and the 10 core targets.

RESULTS

The results showed that core targets (including MMP 2, PPARG, IL-2, MAPK14, MMP 9, and SRC), three signaling pathways (including the PI3K-Akt, AGE-RAGE, and MAPK), and cell differentiation (including Th1, Th2, and Th17) might be related to the body's immunity and inflammation. These results suggested that HCQ might act on targets and pathways involved in inflammation and immune regulation to exert a common effect on the treatment of LN and IgAN.

CONCLUSIONS

The current study provided new evidence for the protective mechanism and clinical utility of HCQ against LN and IgAN.

Synthesis and clinical application of new drugs approved by FDA in 2023

In 2023, the U.S. Food and Drug Administration (FDA) granted approval to a total of 55 new drugs, comprising 29 new chemical entities (NCEs) and 25 new biological entities (NBEs). These drugs primarily focus on oncology, the central nervous system, anti-infection, hematology, cardiovascular, ophthalmology, immunomodulatory and other therapeutic areas. Out of the 55 drugs, 33 (60 %) underwent an accelerated review process and received approval, while 25 (45 %) were specifically approved for the treatment of rare diseases. The purpose of this review is to provide an overview of the clinical uses and production techniques of 29 newly FDA-approved NCEs in 2023. Our intention is to offer a comprehensive understanding of the synthetic approaches employed in the creation of these drug molecules, with the aim of inspiring the development of novel, efficient, and applicable synthetic methodologies.

Physiologically-based pharmacokinetic model of sparsentan to evaluate drug-drug interaction potential

Sparsentan is a dual endothelin/angiotensin II receptor antagonist indicated to reduce proteinuria in patients with primary IgA nephropathy at high risk of disease progression. In vitro data indicate that sparsentan is likely to inhibit or induce various CYP enzymes at therapeutic concentrations. Sparsentan as a victim and perpetrator of CYP3A4 mediated drug-drug interactions (DDIs) has been assessed clinically. A mechanistic, bottom-up, physiologically-based pharmacokinetic (PK) model for sparsentan was developed based on in vitro data of drug solubility, formulation dissolution and particle size, drug permeability, inhibition and induction of metabolic enzymes, and P-glycoprotein (P-gp) driven efflux. The model was verified using clinical PK data from healthy adult volunteers administered single and multiple doses in the fasted and fed states for a wide range of sparsentan doses. The model was also verified by simulation of clinically observed DDIs. The verified model was then used to test various DDI simulations of sparsentan as a perpetrator and victim of CYP3A4 using an expanded set of inducers and inhibitors with varying potency. Additional perpetrator and victim DDI simulations were performed using probes for CYP2C9 and CYP2C19. Simulations were conducted to predict the effect of complete inhibition of P-gp inhibition on sparsentan absorption and clearance. The predictive simulations indicated that exposure of sparsentan could increase greater than two-fold if co-administered with a strong CYP3A4 inhibitor, such as itraconazole. Other potential DDI interactions as victim or perpetrator were all within two-fold of control. The effect of complete P-gp inhibition on sparsentan PK was negligible.

Traditional Chinese medicine for the treatment of immune-related nephropathy: A review

Immune-related nephropathy (IRN) refers to immune-response-mediated glomerulonephritis and is the main cause of end-stage renal failure. The pathogenesis of IRN is not fully understood; therefore, treatment is challenging. Traditional Chinese medicines (TCMs) have potent clinical effects in the treatment of the IRN conditions immunoglobulin A nephropathy, lupus nephropathy, and diabetic nephropathy. The underlying mechanisms mainly include its inhibition of inflammation; improvements to renal interstitial fibrosis, oxidative stress, autophagy, apoptosis; and regulation of immunity. In this review, we summarize the clinical symptoms of the three IRN subtypes and the use of TCM prescriptions, herbs, and bioactive compounds in treating IRN, as well as the potential mechanisms, intending to provide a reference for the future study of TCM as IRN treatments.

EIF2α/ATF4 pathway enhances proliferation of mesangial cell via cyclin D1 during endoplasmic reticulum stress in IgA nephropathy

IgA nephropathy (IgAN) is an essential cause of kidney failure and end-stage kidney disease worldwide. Mesangial hypercellularity is an important characteristic of IgAN, but the underlying mechanism remains unclear. Endoplasmic reticulum (ER) stress is a series of stress responses to restore the function of endoplasmic reticulum. We aimed to explore how ER stress functioned in kidneys of IgAN. We first examined ER stress in IgAN kidneys in vivo and in vitro, by testing the levels of ER stress associated proteins (BIP, p-eIF2α and ATF4). Our results showed that ER stress was activated in IgAN patients, mice and cell model. ER stress activation was related to the distribution of IgA deposition and the degree of mesangial proliferation. To determine the role of ER stress in mesangial cell (MC) proliferation of IgAN, we then tested the levels of ER stress and MC proliferation (cyclin D1, cell viability and cell cycle) through inhibiting ER stress associated proteins. After inhibiting ER stress associated proteins, ER stress was inactivated and cell proliferation was inhibited in MCs. We also explored the correlation between ER stress in the glomerulus and the clinical outcomes of IgAN patients in a prospective study. Patients with lower expression of p-eIF2α or ATF4 had higher rates of hematuria remission, proteinuria remission and clinical remission. In summary, our work outlines that in IgAN, ER stress mediated by eIF2α/ATF4 pathway promotes MC proliferation via up-regulating the expression of cyclin D1. Furthermore, p-eIF2α and ATF4 in the glomerulus negatively correlate with the clinical remission of IgAN patients.

Interleukin Variants Are Associated with the Development and Progression of IgA Nephropathy: A Candidate-Gene Association Study and Meta-Analysis

The interleukin-1 gene cluster encodes cytokines, which modulate mesangial cell proliferation and matrix expansion, both constituting central factors in the development and progression of immunoglobulin A nephropathy (IgAN). A candidate-gene study was performed to examine the association of polymorphisms of the interleukin-1 gene cluster with the risk of progressive IgAN. To gain deeper insights into the involvement of interleukin genes in IgAN, a meta-analysis of genetic association studies (GAS) that examine the association between interleukin variants and IgAN was conducted. Association study: The case-control study consisted of 121 unrelated Caucasians with sporadic, histologically diagnosed IgAN and of 246 age- and sex-matched healthy controls. Persistent proteinuria (>2 g/24 h) and/or impaired kidney function (serum creatinine > 1.5 mg/dL) defined progressive (n = 67) vs. non-progressive (n = 54) IgAN cases. Genotypes were assessed for two promoter-region single-nucleotide polymorphisms, C-899T (rs1800587) in IL1A and C-511T (rs16944) in IL1B, and for one penta-allelic variable-length tandem repeat polymorphism (VNTR 86 bp intron 2) in IL1RN. The association of these variants with the susceptibility of IgAN and the development of progressive IgAN (healthy status, IgAN, progressive IgAN) was tested using the generalized odds ratio (ORG) metric. Linkage disequilibrium and haplotype analysis were also performed. Meta-analysis: We included in the meta-analysis 15 studies investigating association between 14 interleukin variants harbored in eight different genes and IgAN. The ORG was used to evaluate the association between interleukin variants and IgAN using random effects models. The present case-control study revealed association of IL1B C-511T (rs16944) with the progression of IgAN (p = 0.041; ORG = 2.11 (1.09-4.07)). On haplotype analysis, significant results were derived for the haplotypes C-C-1 (p = 0.005; OR = 0.456 (0.261~0.797)) and C-T-2 (p = 0.003; OR = 4.208 (1.545-11.50)). Regarding association and meta-analysis results, variants in IL1B (rs1143627 and rs16944), IL1RN (rs928940, rs439154, and rs315951) and IL10 (rs1800871) were associated with IgAN based on either genotype or allele counts. Genetic variants and haplotypes in the IL1B, IL1RN, and IL10 genes might contribute to an increased risk for development and progression of IgAN.

Glomerulonephritis

Glomerulonephritis (GN) encompasses several disorders that cause glomerular inflammation and injury through an interplay of immune-mediated mechanisms, host characteristics, and environmental triggers, such as infections. GN can manifest solely in the kidney or in the setting of a systemic illness, and presentation can range from chronic and relatively asymptomatic hematuria to fulminant renal failure. Classic acute GN is characterized by hematuria, edema, and hypertension, the latter 2 of which are the consequence of sodium and water retention in the setting of renal impairment. Although presenting signs and symptoms and a compatible clinical history can suggest GN, serologic and urinary testing can further refine the differential diagnosis, and renal biopsy can be used for definitive diagnosis. Treatment of GN can include supportive care, renin-angiotensin-aldosterone system blockade, immunomodulatory therapy, and renal transplant. Prognosis is largely dependent on the underlying cause of GN and can vary from a self-limited course to chronic kidney disease. This review focuses on lupus nephritis, IgA nephropathy, IgA vasculitis, and postinfectious GN.

A bibliometric analysis of complement in IgA nephropathy from 1991 to 2022

Introduction: IgA nephropathy is a common glomerular disease on a global scale, which has resulted in significant economic burdens. The complement system plays a vital role in enhancing the efficacy of antibodies and phagocytic cells in eliminating microbes and damaged cells, and promoting inflammation. Complement activation has been found to contribute to the progression of various renal diseases, including IgA nephropathy. Methods: In this study, a thorough analysis was conducted on publications related to complement in IgAN from 1991 to 2022, retrieved from the Web of Science Core Collection and Scopus database. The analysis focused on various aspects such as annual publications, country, institution, author, journal, keywords, and co-cited references, utilizing Citespace and Vosviewer. Results: A total of 819 publications were obtained, and while there were slight fluctuations in annual publications, an overall upward trend was observed. China, Japan and the United States were the leading countries in terms of publications, with China having the highest number of publications (201). Collaborative network analysis revealed that England, University of Alabama Birmingham, and Robert J Wyatt were the most influential country, institution, and author, respectively, in this field of research. Furthermore, the analysis of references and keywords indicated that complement activation contributes to IgAN, and immunosuppression in IgAN are a hot topic of research. Discussion: This study identifies current research hotspots and advanced tendencies in the study of complement in IgAN, providing scholars with crucial directions in this research area.

Tumor Necrosis Factor-α G-308A Polymorphism and Sporadic IgA Nephropathy: A Meta-Analysis Using a Genetic Model-Free Approach

Tumor necrosis factor-α (TNF-α) is a potent pro-inflammatory cytokine, involved in the pathogenesis and progression of immunoglobulin A nephropathy (IgAN). A bi-allelic polymorphism in the promoter region, at position -308 (G/A) of the TNF-α gene (rs1800629) is associated with an increased TNF-a production. However, several previous association studies of TNF-α G-308A polymorphism and IgAN rendered contradictory findings. The objective of the present study is to shed light on these inconclusive results and clarify the role of TNF-α and any possible contribution of this factor in the development and progression of sporadic IgAN. Therefore, a meta-analysis of all available genetic association studies relating the TNF-α G-308A polymorphism to the risk for development and/or progression of IgAN was conducted. Seven studies were included in the meta-analysis. Three of them included populations of European descent (Caucasians) and four involved Asians. The generalized odds ratio (OR_G) was used to estimate the risk for the development and/or progression of the disease. Overall, the meta-analysis did not detect any significant association between the G-308A variant and both the risk of developing IgAN and the risk for progression of IgAN. In conclusion, these results suggest that TNF-α does not constitute a key component in the genetic architecture of sporadic IgAN. However, further evidence deciphering the influence of TNF-α on IgAN is still needed.

Roles of mesangial C3 and C1q deposition in the clinical manifestations and prognosis of IgAN

BACKGROUND AND AIM

Immunoglobulin A nephropathy (IgAN) is regarded as the most common type of glomerulonephritis around the world and has the potential to result in renal failure. Complement activation has been addressed by a great body of evidence in the pathogenesis of IgAN. We aimed to evaluate the predictive value of C3 and C1q deposition for disease progression in IgAN patients in this retrospective study.

METHODS

We recruited 1191 biopsy-diagnosed IgAN patients, and they were divided into different groups according to their glomerular immunofluorescence examination of renal biopsy tissues: 1) C3 deposits ≥ 2 + group (N = 518) and C3 deposits < 2 + group (N = 673). 2) C1q deposit-positive group (N = 109) and C1q deposit-negative group (N = 1082). The renal outcomes were end-stage renal disease (ESRD) and/or an estimated glomerular filtration rate (eGFR) decrease greater than 50% from the baseline value. Kaplan-Meier analyses were performed to evaluate renal survival. Univariate and multivariate Cox proportional hazard regression models were used to evaluate the effect of C3 and C1q deposition on renal outcome in IgAN patients. In addition, we compared the predictive value of mesangial C3 and C1q deposition in IgAN patients.

RESULTS

The median follow-up period was 53 months (interquartile range 36-75 months). During follow-up, 7% (84) of patients progressed to ESRD, and 9% (111) of patients had an eGFR decline ≥ 50%. IgAN patients complicated with C3 deposits ≥ 2 + were associated with more severe renal dysfunction and pathologic lesions at the time of renal biopsy. The crude incidence rates for the endpoint were 12.5% (84 out of 673) and 17.2% (89 out of 518) in the C3 < 2 + and C3 ≥ 2 + groups, respectively (P = 0.022). Of C1q deposit-positive and C1q deposit-negative patients, 22.9% (25 out of 109) and 13.7% (148 out of 1082) reached the composite endpoint, respectively (P = 0.009). Adding C3 deposition to clinical and pathologic models had better predictability of renal disease progression than C1q.

CONCLUSION

Glomerular C3 and C1q deposits affected the clinicopathologic features of IgAN patients and emerged as independent predictors and risk factors for renal outcomes. In particular, the predictive ability of C3 was slightly better than that of C1q.

Cyclic neutropenia and concomitant IgA nephropathy: a case report

BACKGROUND

IgA nephropathy (IgAN) is universally recognized as one of the most common primary glomerular diseases in all ages. Cyclic neutropenia (CN) is a rare haematologic disorder that is associated with mutations of the ELANE gene. The co-occurrence of IgAN and CN is extremely rare. This is the first case report of a patient with IgAN and genetically confirmed CN.

CASE PRESENTATION

We report a case of a 10-year-old boy who presented with recurrent viral upper respiratory tract infections accompanied by several episodes of febrile neutropenia, haematuria, proteinuria and acute kidney injury. Upon first admission, his physical examination was unremarkable. His kidney function was impaired, whereas his urine microscopy showed evidence of macroscopic haematuria and proteinuria. Further workup showed elevated IgA. The renal histology was consistent with mesangial and endocapillary hypercellularity with mild crescentic lesions, while immunofluorescence microscopy showed IgA-positive staining, which was characteristic of IgAN. Moreover, genetic testing confirmed the clinical diagnosis of CN, therefore Granulocyte colony-stimulating factor (G-CSF) was initiated to stabilize the neutrophil count. Regarding proteinuria control, the patient was initially treated with an Angiotensin-converting-enzyme inhibitor for approximately 28 months. However, due to progressive proteinuria (> 1 g/24 h), Corticosteroids (CS) were added for a period of 6 months according to the revised 2021 KDIGO guidelines with favorable outcome.

CONCLUSIONS

Patients with CN are more susceptible to recurrent viral infections, which can trigger IgAN attacks. In our case CS induced remarkable proteinuria remission. The use of G-CSF contributed to the resolution of severe neutropenic episodes, viral infections and concomitant AKI episodes, contributing to better prognosis of IgAN. Further studies are mandatory to determine whether there is a genetical predisposition for IgAN in children with CN.

Identifying potential biomarkers for the diagnosis and treatment of IgA nephropathy based on bioinformatics analysis

BACKGROUND

IgA nephropathy (IgAN) has become the leading cause of end-stage renal disease in young adults. Nevertheless, the current diagnosis exclusively relies on invasive renal biopsy, and specific treatment is deficient. Thus, our study aims to identify potential crucial genes, thereby providing novel biomarkers for the diagnosis and therapy of IgAN.

METHODS

Three microarray datasets were downloaded from GEO official website. Differentially expressed genes (DEGs) were identified by limma package. GO and KEGG analysis were conducted. Tissue/organ-specific DEGs were distinguished via BioGPS. GSEA was utilized to elucidate the predominant enrichment pathways. The PPI network of DEGs was established, and hub genes were mined through Cytoscape. The CTD database was employed to determine the association between hub genes and IgAN. Infiltrating immune cells and their relationship to hub genes were evaluated based on CIBERSORT. Furthermore, the diagnostic effectiveness of hub markers was subsequently predicted using the ROC curves. The CMap database was applied to investigate potential therapeutic drugs. The expression level and diagnostic accuracy of TYROBP was validated in the cell model of IgAN and different renal pathologies.

RESULTS

A total of 113 DEGs were screened, which were mostly enriched in peptidase regulator activity, regulation of cytokine production, and collagen-containing extracellular matrix. Among these DEGs, 67 genes manifested pronounced tissue and organ specificity. GSEA analysis revealed that the most significant enriched gene sets were involved in proteasome pathway. Ten hub genes (KNG1, FN1, ALB, PLG, IGF1, EGF, HRG, TYROBP, CSF1R, and ITGB2) were recognized. CTD showed a close connection between ALB, IGF, FN1 and IgAN. Immune infiltration analysis elucidated that IGF1, EGF, HRG, FN1, ITGB2, and TYROBP were closely associated with infiltrating immune cells. ROC curves reflected that all hub genes, especially TYROBP, exhibited a good diagnostic value for IgAN. Verteporfin, moxonidine, and procaine were the most significant three therapeutic drugs. Further exploration proved that TYROBP was not only highly expressed in IgAN, but exhibited high specificity for the diagnosis of IgAN.

CONCLUSIONS

This study may offer novel insights into the mechanisms involved in IgAN occurrence and progression and the selection of diagnostic markers and therapeutic targets for IgAN.

Identification of key genes for IgA nephropathy based on machine learning algorithm and correlation analysis of immune cells

INTRODUCTION

The pathogenesis and progression mechanism of Immunoglobulin A nephropathy (IgAN) is not fully understood. There is a lack of panoramic analysis of IgAN immune cell infiltration and algorithms that are more efficient and accurate for screening key pathogenic genes.

METHODS

RNA sequencing (RNA-seq) data sets on IgAN were downloaded from the Gene Expression Omnibus (GEO) database, including GSE93798, GSE35489, and GSE115857. The RNA-seq data set of kidney tissue as control samples were downloaded from the Genotype-Tissue Expression (GTEx) database. Three machine learning algorithms-weighted gene co-expression network analysis (WGCNA), least absolute shrinkage and selection operator (LASSO), and support vector machine-were used to identify the key pathogenic gene sets of the IgAN disease. The ssGSEA method was applied to calculate the immune cell infiltration (ICI) of IgAN samples, whereas the Spearman test was used for correlation analysis. The receiver operator characteristic curve (ROC) was used to evaluate the diagnostic efficacy of key genes. The correlation between the key genes and ICI was analyzed using the Spearman test.

RESULTS

A total of 177 genes were screened out as differentially expressed genes (DEGs) for IgAN, including 135 up-regulated genes and 42 down-regulated genes. The DEGs were significantly enriched in the inflammatory- or immune-related pathways (gene sets). Activating transcription factor 3 (AFT3), C-X-C Motif Chemokine Ligand 6 (CXCL6), and v-fos FBJ murine osteosarcoma viral oncogene homolog B (FOSB) were identified using WGCNA, support vector machine, and LASSO algorithms. These three genes revealed good diagnostic efficacy in the training and test cohorts. The CXCL6 expression positively correlated with activated B cells and memory B cells.

CONCLUSION

ATF3, FOSB, and CXCL6 genes were identified as potential biomarkers of IgAN. These three genes exhibited good diagnostic efficacy for IgAN. We described the landscape of immune cell infiltration for IgAN. Activated B cells and memory B cells were more highly expressed in the IgAN samples than in the control samples. CXCL6 seems crucial to the pathogenesis of IgAN and may induce IgAN by enriching immune cells. Our study may contribute to developing CXCL6 inhibitors that target B cells for IgAN therapy.

Proteomic profiling of IgA nephropathy reveals distinct molecular prognostic subtypes

IgA nephropathy (IgAN) is a heterogeneous disease, which poses a series of challenges to accurate diagnosis and personalized therapy. Herein, we constructed a systematic quantitative proteome atlas from 59 IgAN and 19 normal control donors. Consensus sub-clustering of proteomic profiles divided IgAN into three subtypes (IgAN-C1, C2, and C3). IgAN-C2 had similar proteome expression patterns with normal control, while IgAN-C1/C3 exhibited higher level of complement activation, more severe mitochondrial injury, and significant extracellular matrix accumulation. Interestingly, the complement mitochondrial extracellular matrix (CME) pathway enrichment score achieved a high diagnostic power to distinguish IgAN-C2 from IgAN-C1/C3 (AUC>0.9). In addition, the proteins related to mesangial cells, endothelial cells, and tubular interstitial fibrosis were highly expressed in IgAN-C1/C3. Most critically, IgAN-C1/C3 had a worse prognosis compared to IgAN-C2 (30% eGFR decline, p = 0.02). Altogether, we proposed a molecular subtyping and prognostic system which could help to understand IgAN heterogeneity and improve the treatment in the clinic.

Long-term outcomes of add-on direct renin inhibition in igA nephropathy: a propensity score-matched cohort study

INTRODUCTION

The long-term clinical outcomes in biopsy proven IgAN patients treated with aliskiren on top of a maximally tolerated dose of ACEi/ARB remain unknown.

METHODS

Patients with IgAN treated with a direct renin inhibitor and ACEi/ARB for at least 6 months were compared with a 1:1 propensityscore-matched cohort (including MEST-C score and the 12-months pre-exposure slope of eGFR matching) who received ACEi/ARB without aliskiren exposure to compute the hazard ratio of reaching the primary endpoint of a composite of 40% reduction in eGFR, initiation of KRT and all-cause mortality. Secondary outcome measures included changes in mean UPCR, blood pressure, eGFR, incidence of hyperkalemia and other adverse events during follow-up.

RESULTS

After a median follow-up of 2.5 years, 8/36 (22.2%) aliskiren-treated patients and 6/36 (16.7%) control patients reached the primary composite outcome (HR = 1.60; 95% CI 0.52-4.88; P = 0.412). Aliskiren treatment increased the risk of ≥ 40% eGFR decline (HR = 1.60; 95% CI 0.52-4.88; P = 0.412), and hyperkalemia (HR = 8.60; 95% CI 0.99-73.64; P = 0.050). At 10.8 years, renal composite outcome was reached in 69.4% vs 58.3% (HR = 2.16; 95% CI 1.18-3.98; P = 0.013) of patients in the aliskiren and control groups, respectively. The mean UPCR reduction between treatment and control was not statistically different (52.7% vs 42.5%; 95% CI 0.63-2.35; P = 0.556). The mean intergroup difference in eGFR decline over 60 months was 7.75 ± 3.95 ml/min/1.73 m² greater in the aliskiren group (12.83 vs 5.08; 95% CI - 0.17 to 15.66; P = 0.055).

CONCLUSION

Among patients with IgAN, add-on aliskiren was associated with less favorable long-term kidney outcomes despite an initial anti-proteinuric effect.

Long noncoding RNA FGD5-AS1 alleviates childhood IgA nephropathy by targeting PTEN-mediated JNK/c-Jun signaling pathway via miR-196b-5p

This paper studied lncRNA FGD5 antisense RNA 1 (FGD5-AS1)-associated mechanisms in immunoglobulin A nephropathy (IgAN). FGD5-AS1, miR-196b-5p, and PTEN in the serum of children with IgAN were assessed. MES-13 cells were stimulated by p-IgA1 to construct an in vitro model of IgAN. After plasmid intervention, cell proliferation, cell cycle, apoptosis, and inflammatory response were correspondingly evaluated. An IgAN mouse model was established to define FGD5-AS1/miR-196b-5p/PTEN axis-mediated alternations of 24-h proteinuria, blood urea nitrogen, serum creatinine, glomerular IgA deposition, renal fibrosis, and glycogen content in renal tissue. The changes in JNK/c-Jun pathway activation in the cell model were also tested. Our results discovered that FGD5-AS1 and PTEN were down-regulated and miR-196b-5p was up-regulated in children with IgAN. Overexpression of FGD5-AS1 or silencing of miR-196b-5p impeded the proliferation and inflammatory response and induced apoptosis of p-IgA1-stimulated MES-13 cells, and improved pathological conditions in IgAN mice. Inhibition of PTEN rescued the therapeutic effects of overexpression of FGD5-AS1 or inhibition of miR-196b-5p on IgAN. FGD5-AS1/miR-196b-5p/PTEN axis inhibited the activation of the JNK/c-Jun pathway. Taken together, FGD5-AS1 attenuates IgAN by targeting PTEN-mediated JNK/c-Jun signaling via miR-196b-5p. Therefore, FGD5-AS1 may be a new therapeutic target for IgAN.

The Human Virome and Its Crosslink with Glomerulonephritis and IgA Nephropathy

The prokaryotic, viral, fungal, and parasitic microbiome exists in a highly intricate connection with the human host. In addition to eukaryotic viruses, due to the existence of various host bacteria, phages are widely spread throughout the human body. However, it is now evident that some viral community states, as opposed to others, are indicative of health and might be linked to undesirable outcomes for the human host. Members of the virome may collaborate with the human host to retain mutualistic functions in preserving human health. Evolutionary theories contend that a particular microbe's ubiquitous existence may signify a successful partnership with the host. In this Review, we present a survey of the field's work on the human virome and highlight the role of viruses in health and disease and the relationship of the virobiota with immune system control. Moreover, we will analyze virus involvement in glomerulonephritis and in IgA nephropathy, theorizing the molecular mechanisms that may be responsible for the crosslink with these renal diseases.

New-onset IgA nephropathy following COVID-19 vaccination

Coronavirus disease 2019 (COVID-19) pandemic, caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has caused significant economic and health damage worldwide. Rapid vaccination is one of the key strategies to curb severe illness and death due to SARS-CoV-2 infection. Hundreds of millions of people worldwide have received various COVID-19 vaccines, including mRNA vaccines, inactivated vaccines and adenovirus-vectored vaccines, but the side effects and efficacy of most vaccines have not been extensively studied. Recently, there have been increasing reports of immunoglobulin A nephropathy (IgAN) after COVID-19 vaccination, however, whether their relationship is causal or coincidental remains to be verified. Here, we summarize the latest clinical evidence of IgAN diagnosed by renal biopsy associated with the COVID-19 vaccine published by 10 July 2022 with the largest sample size, and propose a hypothesis for the pathogenesis between them. At the same time, the new opportunity presented by COVID-19 vaccine allows us to explore the mechanism of IgAN recurrence for the first time. Indeed, we recognize that large-scale COVID-19 vaccination has enormous benefits in preventing COVID-19 morbidity and mortality. The purpose of this review is to help guide the clinical assessment and management of IgA nephropathy post-COVID-19 vaccination and to enrich the 'multi-hit' theory of IgA nephropathy.

IgA nephropathy pathogenesis and therapy: Review & updates

BACKGROUND

IgA nephropathy (IgAN) is the most frequent type of primary glomerulonephritis since the first type was described more than four decades ago. It is the prevalent cause of primary glomerular disease that causes end-stage renal disease. In most patients with IgAN, hematuria is the most common reported symptom, particularly in those with a preceding upper respiratory tract infection. Although the pathogenesis of IgAN is usually multifactorial, autoimmune complex formation and inflammatory processes are the most widely recognized pathogenic mechanisms. Multiple approaches have been trialed as a therapy for IgAN, including tonsillectomy, steroids, other immune-suppressive therapy in different regimens, and kidney transplantation.

AIM AND METHOD

PubMed, Google, Google Scholar, Scopus, and EMBASE were searched by the authors using different texts, keywords, and phrases. A non-systemic clinical review is intended to review the available data and clinical updates about the possible mechanism(s) of IgAN pathogenesis and treatments.

CONCLUSION

IgAN has a heterogeneous pattern worldwide, making it difficult to understand its pathogenesis and treatment. Proteinuria is the best guide to follow up on the IgAN progression and treatment response. Steroids are the cornerstone of IgAN therapy; however, other immune-suppressive and immune-modulative agents are used with a variable response rate. Kidney transplantation is highly advisable for IgAN patients, although the recurrence rate is high. Finally, IgAN management requires collaborative work between patients and their treating physicians for safe long-term outcomes.

Increased Urinary IgA in Paediatric IgA Vasculitis Nephritis

IgA vasculitis (IgAV) is the most common form of paediatric vasculitis, with up to 50% of patients experiencing kidney inflammation. Much remains unknown about IgAV, but it is believed to arise due to galactose-deficient IgA1 promoting an auto-inflammatory response. This study assesses whether urinary IgA can be detected in children with IgAV to allow further evaluation of IgA1 and whether it has any relationship with nephritis. Urinary and serum IgA concentrations were measured using commercially available ELISA kits. Patients were grouped into IgAV nephritis (IgAVN) or IgAV without nephritis (IgAVwoN). Fifty-nine children were included: IgAVN n = 12, IgAVwoN n = 35, and healthy controls (HC) n = 12, with a mean age of 8.2 ± 4.1 years. Urinary IgA concentrations were statistically significantly higher in patients with IgAV (107.1 ± 136.3 μg/mmol) compared to HC (50.6 ± 26.3 μg/mmol; p = 0.027) and IgAVN (229.8 ± 226.3 μg/mmol) compared to both IgAVwoN (65.0 ± 37.8 μg/mmol; p = 0.002) and HC (p < 0.001). Urinary IgA concentrations were able to distinguish between renal status (AUC 0.838, 95%CI [0.704−0.973], p < 0.001) and did not correlate with proteinuria (r = 0.124; p = 0.407). Urinary IgA concentrations are increased in children with IgAVN, and it has the potential to act as a non-invasive biofluid to further evaluate nephritis in this disease.

Mesangial Cell–Derived Exosomal miR-4455 Induces Podocyte Injury in IgA Nephropathy by Targeting ULK2

Growing evidence suggests that mesangial cells (MCs) play a crucial role in the pathogenesis of IgA nephropathy (IgAN) by secreting aIgA1. However, the mechanism by which MCs regulate podocyte injury remains unknown. This study demonstrated that MC-derived exosomes treated with aIgA1 induced podocyte injury in IgA nephropathy. miR-4455, which was significantly upregulated in aIgA1 treatment MC-derived exosomes, can be transferred from MCs to podocytes via exosomes. MC-derived exosomal miR-4455 induced podocyte injury. Mechanistically, exosomal miR-4455 directly targeted ULK2 to regulate LC3II/I and P62 levels, which mediates autophagy homeostasis. This study revealed that MC-derived exosomal miR-4455 is a key factor affecting podocyte injury and provides a series of potential therapeutic targets for treating IgA nephropathy.

Increased retinal drusen in IgA glomerulonephritis are further evidence for complement activation in disease pathogenesis

Drusen are retinal deposits comprising cell debris, immune material and complement that are characteristic of macular degeneration but also found in glomerulonephritis. This was a pilot cross-sectional study to determine how often drusen occurred in IgA glomerulonephritis and their clinical significance. Study participants underwent non-mydriatic retinal photography, and their deidentified retinal images were examined for drusen by two trained graders, who compared central drusen counts, counts ≥ 10 and drusen size with those of matched controls. The cohort comprised 122 individuals with IgA glomerulonephritis including 89 males (73%), 49 individuals (40%) of East Asian or Southern European ancestry, with an overall median age of 54 years (34-64), and median disease duration of 9 years (4-17). Thirty-nine (33%) had an eGFR < 60 ml/min/1.73 m² and 72 had previously reached kidney failure (61%). Overall mean drusen counts were higher in IgA glomerulonephritis (9 ± 27) than controls (2 ± 7, p < 0.001). Central counts ≥ 10 were also more common (OR = 3.31 (1.42-7.73, p = 0.006), and were associated with longer disease duration (p = 0.03) but not kidney failure (p = 0.31). Larger drusen were associated with more mesangial IgA staining (p = 0.004). Increased drusen counts were also present in IgA glomerulonephritis secondary to Crohn's disease but not with Henoch-Schonlein purpura. The finding of retinal drusen in IgA glomerulonephritis is consistent with complement activation and represents a model for better understanding glomerular immune deposition and a supporting argument for treatment with anti-complement therapies.

Renal Side Effects of COVID-19 Vaccination

Background: The COVID-19 pandemic has imposed a challenge on global healthcare and has tremendously impacted everyone's lives. Vaccination is one of the most effective and vital strategies to halt the pandemic. However, new-onset and relapsed kidney diseases have been reported after COVID-19 vaccination. This narrative review was conducted to collect published data and generalize some hypotheses for the pathogenesis of renal side effects of COVID-19 vaccines. Methods: A systematic literature search of articles reporting renal adverse reactions, including in adults and children, in the PubMed and Web of Science databases until August 2022 was performed. Results: A total of 130 cases reporting a renal adverse reaction following COVID-19 vaccination from 90 articles were included in this review, of which 90 (69%) were new-onset kidney diseases, while 40 (31%) were relapsed kidney diseases. The most frequent renal side effects of COVID-19 vaccination were minimal change disease (52 cases), IgA nephropathy (48 cases), antineutrophil cytoplasmic autoantibody vasculitis (16 cases), and acute interstitial nephritis (12 cases). Other renal side effects occurred at a much lower frequency. Follow-up data were available for 105 patients, and 100 patients (95%) responded to the treatments. Conclusions: The number of reported cases is far less than the hundreds of millions of vaccinations, and the benefit of COVID-19 vaccination far outweighs its risks. This review will assist healthcare professionals, particularly nephrologists, who should be aware of these side effects and recognize them early and treat them efficiently.

Guben Tongluo Formula Protects LPS-induced Damage in Lamina Propria B Lymphocytes Through TLR4/MyD88/NF-κB Pathway

OBJECTIVE

The main pathological feature of immunoglobulin A nephropathy (IgAN), an autoimmune kidney disease, is the deposition of IgA immune complexes, accompanied by mesangial cell proliferation and elevated urine protein. The Guben Tongluo formula (GTF) is a traditional Chinese medicine prescription, which has predominant protective effects on IgAN. However, the therapeutic mechanism of the GTF in IgAN remains elusive. The present study aimed to determine the effects of GTF in treating IgAN via regulating the TLR4/MyD88/NF-κB pathway.

METHODS

In the present study, lamina propria B lymphocytes were treated with different concentrations of lipopolysaccharide (LPS) (0, 1, 5, 10 and 20 ng/mL). Flow cytometry was used to define positive CD86+CD19+ cells. CCK-8 assay was used to examine cell proliferation. RNAi was used to induce TLR4 silencing. qRT-PCR and Western blotting were used to determine gene expression.

RESULTS

It was found that the LPS dose-dependently increased the content of IgA and galactose-deficient IgA1 (Gd-IgA), the levels of TLR4, Cosmc, MyD88 and phosphorylated (p)-NF-κB, and the ratio of CD86+CD19+ and IgA-producing B cells. However, the TLR4 knockdown reversed the role of LPS. This suggests that TLR4 mediates the effects of LPS on lamina propria B lymphocytes. Furthermore, the GTF could dose-dependently counteract the effects of LPS and TLR4 overexpression on lamina propria B lymphocytes through the TLR4/MyD88/NF-κB pathway.

CONCLUSION

Collectively, these results demonstrate that the GTF can regulate the TLR4/MyD88/NF-κB pathway to treat IgAN model lamina propria B lymphocytes stimulated by LPS.

Intrinsic Kidney Pathology in Children and Adolescents Following COVID-19 Vaccination: A Systematic Review

Global COVID-19 vaccination programs for children and adolescents have been developed with international clinical trial data confirming COVID-19 mRNA vaccine safety and efficacy for the pediatric population. The impact of COVID-19 vaccination in the kidneys is thought to be explained by a complex immune-mediated relationship between the two, although the pathophysiological mechanisms of how COVID-19 vaccination potentially induces kidney pathology are not presently well known. Whilst intrinsic kidney pathologies following COVID-19 vaccination have been reported in adults, such cases are only being recently reported with greater frequency in children and adolescents. Conforming to the PRISMA checklist, we conducted a systematic review of the current literature to provide an overview on the range of intrinsic kidney pathologies that have been reported following COVID-19 vaccination in children and adolescents. All English language research articles published on or before 30 June 2022 reporting new-onset or relapsed intrinsic kidney pathology in children or adolescents (≤18 years) following COVID-19 vaccination were selected for qualitative analysis. Out of 18 cases from the 13 published articles selected, there were 10 cases of IgA nephropathy (1 case of rapidly progressive glomerulonephritis requiring acute hemodialysis), 5 cases of minimal change disease (MCD), 1 case of concurrent MCD/tubulointerstitial nephritis (TIN) and 2 cases of TIN. There is no indication currently to avoid vaccination, unless specific circumstances exist, as the benefits of COVID-19 vaccination far outweigh its risks. Concluding the findings from our systematic review based on preliminary evidence, potential adverse effects to the kidney from COVID-19 vaccination affects a small number of children and adolescents among the many who have been vaccinated. There remains good reason at present to support vaccination of children and adolescents with a greater morbidity status, such as those living with preexisting chronic kidney disease. Close observation of all children and adolescents receiving COVID-19 vaccination is recommended, particularly in those with preceding intrinsic kidney pathology to identify risks of relapsed disease.

Metagenomics-based systematic analysis reveals that gut microbiota Gd-IgA1-associated enzymes may play a key role in IgA nephropathy

Background: IgA nephropathy (IgAN) is the most common type of glomerulonephritis in Asia. Its pathogenesis involves higher expression of galactose-deficient IgA1 (Gd-IgA1) and dysregulated intestinal mucosal immunity. The objective of this study was to explore whether specific gut microbiota and associated enzymes affect Gd-IgA1 in IgAN.

Methods: This study carried out shotgun metagenomic sequencing with Illumina on fecal samples collected from 20 IgAN patients (IgAN group) and 20 healthy controls (HCs group) who were recruited from January 2016 to December 2018 at the Second Clinical College of Guangzhou University of Chinese Medicine. Differences analysis in gut microbiota was performed to determine the overall microbiota composition, the representative enterotypes, and the microbiota abundance. Correlations between gut microbiota and clinical indicators were assessed by Spearman’s analysis. Moreover, the functional prediction of microbial communities and the quantitative calculation of enzymes encoded by microbiome were performed using the MetaCyc pathway and the bioBakery three platform, respectively.

Results:Bacteroides plebeius and Bacteroides vulgatus levels were higher, while Prevotella copri and Alistipes putredinis levels were lower in the IgAN group compared to HCs group. Enterotype I characterized by Bacteroides was closely related to the IgAN patients. Moreover, Bacteroides fragilis, Flavonifractor plautii and Ruminococcus gnavus were characteristic bacteria enriched in IgAN patients. Spearman’s correlation analysis found that Eggerthella lenta and Ruminococcus bromii were positively correlated with urine protein-creatinine ratio, while Ruminococcus gnavus showed a direct association with red blood cells in urine, and Bacteroides vulgatus and Ruminococcus gnavus were positively correlated with eGFR. These results indicated that intestinal dysbacteriosis occurred in IgAN patients and was associated with clinical and biochemical features. In addition, MetaCyc pathway analysis predicted microbiota-related metabolic pathways, including the biosynthesis of amino acids and glycans, were associated with the IgAN group. Microbial enzymes analysis highlighted that Gd-IgA1-associated α-galactosidase and α-N-acetyl-galactosaminidase secreted by Flavonifractor plautii were enriched in IgAN patients.

Conclusion: These findings suggested that α-galactosidase and α-N-acetyl-galactosaminidase secreted by Flavonifractor plautii might be related to the production of Gd-IgA1, indicating that enzymes originated from abnormal intestinal microbiota may contribute to the production of Gd-IgA1 and play an important role in the pathogenesis of IgAN.

Increased proportion of follicular helper T cells is associated with B cell activation and disease severity in IgA nephropathy

IgA nephropathy (IgAN) is the most common primary glomerulonephritis, characterized by glomerular deposition of IgA immune complexes, mainly produced by B cells under the regulation of CD4⁺T cells. However, the alterations of specific CD4⁺T cell subsets and the mechanism of B cells activation in IgAN remain unclear. Therefore, we aimed to investigate the landscape characteristics and role of CD4⁺T cells in the progression of IgAN. We identified that the proportion of Th2, Th17 and Tfh (follicular helper T) cells in patients with IgAN was significantly higher than that of healthy controls (P < 0.05). Single-cell RNA sequencing of peripheral blood mononuclear cells (PBMCs) showed that Th cells and B cells in patients with IgAN were more activated. Correspondingly, multiplex immunohistochemistry staining of renal biopsy showed increased infiltration of CD4⁺T and B cells in the kidneys of patients with IgAN. The degree of infiltration was positively correlated with the degree of renal damage. Interestingly, the proportion of Tfh cells in peripheral blood was positively correlated with the severity of proteinuria. Moreover, the proximity position of Tfh cells and B cells suggested that cell-cell interactions between Tfh and B cells were happening in situ. Intercellular communication analysis also showed enhanced interaction between Tfh cells and B cells in IgAN. Our findings suggested that Tfh cells of patients possibly contributed to the progression of IgAN by activating B cells via cell-cell interactions and TNFSF14-TNFRSF14 may be an underlying signaling pathway.

Gross hematuria can be an impact of severe acute respiratory syndrome coronavirus 2 vaccination on immunoglobulin A nephropathy: a case report

BACKGROUND

Immunoglobulin A nephropathy is typically accelerated by upper respiratory tract infections and can relapse following vaccination. There have been reports of patients who presented with immunoglobulin A nephropathy flares with or without gross hematuria following coronavirus disease 2019 vaccination. However, this relationship remains to be elucidated.

CASE PRESENTATION

Herein, we present the case of a patient with newly diagnosed immunoglobulin A nephropathy who presented with gross hematuria following the second dose of coronavirus disease 2019 vaccine. A 21-year-old Japanese woman presented with fever and new-onset gross hematuria 1 day after receiving the second dose of the coronavirus disease 2019 vaccine (Pfizer). She had microhematuria without proteinuria for 2 years at the time of her medical check-up. Gross hematuria resolved 6 days after the second dose of the coronavirus disease 2019 vaccine; however, microhematuria (> 100 per high-power field) and mild proteinuria were observed. She was admitted to our hospital 4 weeks after the second vaccination because of persistent urinary abnormalities. She was well before the vaccination and did not have any pulmonary involvement on chest radiography or any symptoms suggestive of coronavirus disease 2019. Renal biopsy revealed an immunoglobulin A nephropathy. The Oxford MEST-C score was M0E0S0T0C0. Our patient's urinary abnormalities implied exacerbation of immunoglobulin A nephropathy after coronavirus disease 2019 vaccination.

CONCLUSIONS

In our case, gross hematuria served as a trigger for immunoglobulin A nephropathy diagnosis, suggesting that nephrologists should pay close attention to gross hematuria and urinalysis after coronavirus disease 2019 vaccination.

New Treatment Strategies for IgA Nephropathy: Targeting Plasma Cells as the Main Source of Pathogenic Antibodies

Immunoglobulin A nephropathy (IgAN) is a rare autoimmune disorder and the leading cause of biopsy-reported glomerulonephritis (GN) worldwide. Disease progression is driven by the formation and deposition of immune complexes composed of galactose-deficient IgA1 (Gd-IgA1) and Gd-IgA1 autoantibodies (anti-Gd-IgA1 antibodies) in the glomeruli, where they trigger complement-mediated inflammation that can result in loss of kidney function and end-stage kidney disease (ESKD). With the risk of progression and limited treatment options, there is an unmet need for therapies that address the formation of pathogenic Gd-IgA1 antibody and anti-Gd-IgA1 antibody-containing immune complexes. New therapeutic approaches target immunological aspects of IgAN, including complement-mediated inflammation and pathogenic antibody production by inhibiting activation or promoting depletion of B cells and CD38-positive plasma cells. This article will review therapies, both approved and in development, that support the depletion of Gd-IgA1-producing cells in IgAN and have the potential to modify the course of this disease. Ultimately, we propose here a novel therapeutic approach by depleting CD38-positive plasma cells, as the source of the autoimmunity, to treat patients with IgAN.

Efficacy of Glucocorticoids and Glucocorticoid-Induced Hyperglycaemia in Renal Disease: A Meta-Analysis of Randomized Controlled Trials

Background

Glucocorticoids are the most effective anti-inflammatory and immunosuppressive drugs used to treat patients with renal disease. This study pooled the current evidence of the efficacy of Glucocorticoids and Glucocorticoid-induced hyperglycaemia in renal disease.

Methods

We conducted a systematic literature search on PubMed, Cochrane Central, and Web of Science for relevant randomized controlled trials (RCTs) up to September 1, 2021. The meta-analysis, sensitivity analysis and bias analysis were performed using Review Manager 5. 3.

Results

In this study, seven RCTs with 797 patients were included in our analysis. The analysis revealed that glucocorticoids had a certain alleviating effect on the reduction of renal function. (risk ratio [RR] 0.49 95% confidence interval [Cl] 0. 28 to 0.85, p =0.01) and reduction of proteinuria (weight mean difference [WMD] -0.43; 95% CI -0.57 to-0.28) when compared with the control group. Patients receiving glucocorticoids therapy did not have an increased risk of developing new-onset diabetes mellitus or impaired glucose tolerance. (RR 3.76 95% CI 0.54 to 26.10, p =0.18). For other safety outcomes, glucocorticoids therapy did not increase risk of respiratory infections (RR 1.63, 95% CI 0. 69to3. 89, p =0.27) and Gastrointestinal SAEs is relatively controversial (RR 1.10, 95% CI 0.32 to 3.79, p =0.88). Discussion. In conclusion, current clinical evidence indicates that glucocorticoids is efficacious and safe to renal disease compared with control. Further research comparing long-term glucocorticoids use is needed.

Efficacy and safety of angiotensin-converting enzyme inhibitors or angiotensin receptor blockers for IgA nephropathy in children

BACKGROUND

IgA nephropathy (IgAN) is one of the most prevalent primary glomerulopathies in children. There are various studies investigating the efficacy of angiotensin-converting enzyme inhibitors (ACEI) and angiotensin II receptor blockers (ARB) in adults with IgAN. However, only few studies evaluated the efficacy of these medications in pediatric patients.

OBJECTIVE

To evaluate the efficacy and safety of ACEI/ARB in children with IgAN.

DATA SOURCES

Databases including PubMed, Web of Science, Cochrane, Scopus, and Google Scholar were searched between the 1st of April and 20th of July of 2021 using the keywords "IgA Nephropathy," "Berger's Disease," "Angiotensin-Converting Enzyme Inhibitors," "Angiotensin Receptor Antagonists," "Angiotensin II Type 1 Receptor Blockers," and similar entry terms collected from the Medical Subject Headings (MeSH).

STUDY ELIGIBILITY CRITERIA

Observational studies (case series, case-control, cohort, and cross-sectional) and clinical trials with descriptions of pediatric patients (under 19 years old) with histopathological diagnosis of IgA nephropathy and who received ACEI and/or ARB.

PARTICIPANTS AND INTERVENTIONS

Pediatric patients (under 19 years old) with histopathological diagnosis of IgA nephropathy and who received ACEI and/or ARB.

STUDY APPRAISAL

For quality assessment, the Risk of Bias 2 tool (RoB 2), the Risk Of Bias In Non-randomized Studies of Interventions tool (ROBINS-I), the National Institutes of Health (NIH) quality assessment tool, and the Newcastle-Ottawa Scale (NOS) were used.

RESULTS

After recovering 1,471 studies, only eight, published between 2003 and 2019, met the eligibility criteria and were included in this systematic review. Of the 737 included children in the studies, 202 (25.8%) used ACEI/ARB and were compared with placebo and other therapy regimens. Of the seven studies that evaluated proteinuria, six reported an efficacy of ACEI/ARB in reducing this marker. ACEI/ARB also showed a possible effect in reducing hematuria and oxidative stress. The most common side effect was dizziness.

LIMITATIONS

The number of studies about the treatment with ACEI/ARB in children with IgAN is scarce. In addition, the studies are very heterogeneous. There are few studies that compared ACEI/ARB with placebo.

CONCLUSIONS AND IMPLICATIONS OF KEY FINDINGS

The use of ACEI and/or ARB appears to be safe and to reduce proteinuria in pediatric patients with IgAN. Nonetheless, further randomized controlled trials, with greater methodological rigor and longer follow-up time, are required to establish the efficacy and safety of this therapy in this population.

SYSTEMATIC REVIEW REGISTRATION NUMBER

The protocol of this systematic literature review was registered in PROSPERO under the number CRD42021245375, and in the OSF registries ( https://osf.io/qft4z/ ) with the registration https://doi.org/10.17605/OSF.IO/VADYR . A higher resolution version of the Graphical abstract is available as Supplementary information.

New-Onset Kidney Diseases after COVID-19 Vaccination: A Case Series

Various vaccines against COVID-19 have been developed and proven to be effective, but their side effects, especially on kidney function, are not yet known in detail. In this study, we report the clinical courses and histopathologic findings of new-onset kidney diseases after COVID-19 vaccination as confirmed via kidney biopsy. Five patients aged 42 to 77 years were included in this study, and baseline kidney function was normal in all patients. The biopsy-proven diagnosis indicated newly developed kidney diseases: (1) IgA nephropathy presenting with painless gross hematuria, (2) minimal change disease presenting with nephrotic syndrome, (3) thrombotic microangiopathy, and (4) two cases of acute tubulointerstitial nephritis presenting with acute kidney injury. Individualized treatment was applied as per disease severity and underlying pathology, and the treatment outcomes of all patients were improved. Since this is not a controlled study, the specific pathophysiologic link and causality between the incidence of kidney diseases and COVID-19 vaccination are difficult to confirm. However, clinicians need to consider the possibility that kidney diseases may be provoked by vaccines in patients who have renal symptoms.

New-Onset and Relapsed Kidney Histopathology Following COVID-19 Vaccination: A Systematic Review

INTRODUCTION

The introduction of COVID-19 vaccination programs has become an integral part of the major strategy to reduce COVID-19 numbers worldwide. New-onset and relapsed kidney histopathology have been reported following COVID-19 vaccination, sparking debate on whether there are causal associations. How these vaccines achieve an immune response to COVID-19 and the mechanism that this triggers kidney pathology remains unestablished. We describe the results of a systematic review for new-onset and relapsed kidney histopathology following COVID-19 vaccination.

METHODS

A systematic literature search of published data up until 31 August 2021 was completed through the Preferred Reporting Items for Systematic Reviews and Meta Analyses (PRISMA) guideline. Research articles reporting new onset or relapsed kidney histopathology in adult patients (>18 years) following COVID-19 vaccination were included for qualitative review. Only full-text articles published in the English language were selected for review.

RESULTS

Forty-eight cases from thirty-six articles were included in the qualitative synthesis of this systematic review. Minimal change disease (19 cases) was the most frequent pathology observed, followed by IgA nephropathy (14 cases) and vasculitis (10 cases). Other cases include relapse of membranous nephropathy, acute rejection of kidney transplant, relapse of IgG4 nephritis, new-onset renal thrombotic microangiopathy, and scleroderma renal crisis following COVID-19 vaccination. There was no mortality reported in any of the included cases. Patients in all but one case largely recovered and did not require long-term renal replacement therapy.

CONCLUSION

This systematic review provides insight into the relationship between various kidney pathologies that may have followed COVID-19 vaccination. Despite these reported cases, the protective benefits offered by COVID-19 vaccination far outweigh its risks. It would be recommended to consider early biopsy to identify histopathology amongst patients presenting with symptoms relating to new-onset kidney disease following vaccination and to monitor symptoms for those with potential relapsed disease.

The Advances of Single-Cell RNA-Seq in Kidney Immunology

Kidney diseases are highly prevalent and treatment is costly. Immune cells play important roles in kidney diseases; however, it has been challenging to investigate the contribution of each cell type in kidney pathophysiology. Recently, the development of single-cell sequencing technology has allowed the extensive study of immune cells in blood, secondary lymphoid tissues, kidney biopsy and urine samples, helping researchers generate a comprehensive immune cell atlas for various kidney diseases. Here, we discuss several recent studies using scRNA-seq technology to explore the immune-related kidney diseases, including lupus nephritis, diabetic kidney disease, IgA nephropathy, and anti-neutrophil cytoplasmic antibody-associated glomerulonephritis. Application of scRNA-seq successfully defined the transcriptome profiles of resident and infiltrating immune cells, as well as the intracellular communication networks between immune and adjacent cells. In addition, the discovery of similar immune cells in blood and urine suggests the possibility of examining kidney immunity without biopsy. In conclusion, these immune cell atlases will increase our understanding of kidney immunology and contribute to novel therapeutics for patients with kidney diseases.

The influences of α-hemolytic Streptococcus on class switching and complement activation of human tonsillar cells in IgA nephropathy

While β-hemolytic streptococcus (β-HS) infections are known to predispose patients to acute poststreptococcal glomerulonephritis, there is evidence that implicates α-hemolytic streptococcus (α-HS) in IgA nephropathy (IgAN). The alternative pathway of the complement system has also been implicated in IgAN. We aimed to explore the association between α-HS and complement activation in human tonsillar mononuclear cells (TMCs) in IgAN. In our study, α-HS induced higher IgA levels than IgG levels, while β-HS increased higher IgG levels than IgA levels with more activation-induced cytidine deaminase, in TMCs in the IgAN group. Aberrant IgA1 O-glycosylation levels were higher in IgAN patients with α-HS. C3 and C3b expression was decreased in IgAN patients, but in chronic tonsillitis control patients, the expression decreased only after stimulation with β-HS. Complement factor B and H (CFH) mRNA increased, but the CFH concentration in culture supernatants decreased with α-HS. The percentage of CD19 + CD35 + cells/complement receptor 1 (CR1) decreased with α-HS more than with β-HS, while CD19 + CD21 + cells/complement receptor 2 (CR2) increased more with β-HS than with α-HS. The component nephritis-associated plasmin receptor (NAPlr) of α-HS was not detected on tonsillar or kidney tissues in IgAN patients and was positive on cultured TMCs and mesangial cells. We concluded that α-HS induced the secretion of aberrantly O-glycosylated IgA while decreasing the levels of the inhibitory factor CFH in culture supernatants and CR1 + B cells. These findings provide testable mechanisms that relate α-HS infection to abnormal mucosal responses involving the alternative complement pathway in IgAN.

Cosmc deficiency causes spontaneous autoimmunity by breaking B cell tolerance

Factors regulating the induction and development of B cell–mediated autoimmunity are not well understood. Here, we report that targeted deletion in murine B cells of X-linked Cosmc, encoding the chaperone required for expression of core 1 O-glycans, causes the spontaneous development of autoimmune pathologies due to a breakdown of B cell tolerance. BC-CosmcKO mice display multiple phenotypic abnormalities, including severe weight loss, ocular manifestations, lymphadenopathy, and increased female-associated mortality. Disruption of B cell tolerance in BC-CosmcKO mice is manifested as elevated self-reactive IgM and IgG autoantibodies. Cosmc-deficient B cells exhibit enhanced basal activation and responsiveness to stimuli. There is also an elevated frequency of spontaneous germinal center B cells in BC-CosmcKO mice. Mechanistically, loss of Cosmc confers enhanced B cell receptor (BCR) signaling through diminished BCR internalization. The results demonstrate that Cosmc, through control of core 1 O-glycans, is a previously unidentified immune checkpoint gene in maintaining B cell tolerance.

The increased miRNA-150-5p expression of the tonsil tissue in patients with IgA nephropathy may be related to the pathogenesis of disease

BACKGROUND

The microRNA (miRNA) expression of the tonsil tissues in patients with immunoglobulin A (IgA) nephropathy (IgAN) has not been reported in the literature.

METHODS

In this study, the expression of nine miRNAs was measured in the tonsil tissues of patients with IgAN, including miRNA-21-5p, miRNA-29a-3p, miRNA-34a-5p, miRNA-146a-5p, miRNA-146b-5p, miRNA-148b-3p, miRNA-150-5p, miRNA-155-5p, and miRNA-181a-5p. Forty patients with proved primary IgA nephropathy were enrolled in our study, 20 IgAN patients with gross hematuria, which induced by tonsillitis (GH-IgAN group) and 20 IgAN patients without gross hematuria in the history (non-GH-IgAN group). Another 20 patients recruited as the control group (CT group) were chronic tonsillitis without kidney disease.

RESULTS

Compared to the CT group, the expression level of miRNA-150-5p in the tonsils was significantly upregulated in the GH-IgAN group, but not in the non-GH-IgAN group (P = 0.031 and P = 0.122, respectively). A correlation analysis was performed between the expression of miRNAs in the tonsils and the clinical data of IgAN patients. The results showed that in the GH-IgAN group, the miRNA-150 expression was positively correlated with systolic blood pressure (β = 2.36, 95% CI 1.11-3.61, P = 0.0016), diastolic blood pressure (β = 1.02, 95% CI 0.22-1.82, P = 0.0224), uric acid (β = 7.43, 95% CI 1.81-13.04, P = 0.0184), leukocyte count (β = 0.22, 95% CI 0.09-0.35, P = 0039), neutrophil count (β = 0.19, 95% CI 0.06-0.32, P = 0.0096), cholesterol (β = 0.09, 95% CI 0.02-0.16, P = 0.0207) and triglyceride level (β = 0.16, 95% CI 0.10-0.22, P < 0.000). Besides, it was negatively correlated with the estimated glomerular filtration rate (eGFR) (β = -2.06, 95% CI: -3.90 - -0.21, P = 0.0421) in the GH-IgAN group; however, no significant correlation was found in the non-GH-IgAN group.

CONCLUSION

The present findings suggest that miRNA-150-5p may be important in the pathogenesis of IgAN, especially in mucosal immunity against the disease.

IgA Nephropathy in a Patient Treated with Adalimumab

Immunoglobulin A (IgA) nephropathy (IgAN) is the most common glomerulonephritis worldwide, characterized by IgA deposits in the glomerular mesangium. It has a progressive nature and can eventually lead to end-stage kidney failure. It can occur as a potential side effect of treatment with tumor necrosis factor alpha antagonist that has been used for numerous chronic inflammatory conditions, such as Crohn's disease. In this study, the case of a 33-year-old man with renal dysfunction, nephrotic proteinuria, and erythrocyturia is described. He had had a history of Crohn's disease for 8 years and had been treated with adalimumab for the past 7 years. The diagnosis of IgAN was confirmed by kidney biopsy. After discontinuance of adalimumab and the induction of corticosteroid therapy, he made a remarkable recovery. Four years after the first presentation of IgAN and discontinuation of adalimumab, his renal function was normal with no proteinuria and only mild erythrocyturia.

IgA Nephropathy After SARS-CoV-2 Vaccination

Here we present the first case of newly diagnosed IgA nephropathy (IgAN) after a SARS-CoV-2 vaccination. A 30-year-old man with no known past medical history presented with gross hematuria and subnephrotic proteinuria 24 hours after the second dose of the mRNA-1273 SARS-CoV-2 vaccine. A kidney biopsy showed IgAN. He was started on an angiotensin receptor blocker, resulting in proteinuria reduction. Similar to natural infection of SARS-CoV-2, persons who receive 2 mRNA-based vaccines demonstrate robust antibodies against the receptor-binding domain (RBD) of the S1 protein. Given the uniqueness of glycosylation of RBD and potent stimulation of immune response from mRNA-based vaccine compared to other vaccines, we hypothesize that our patient developed de novo antibodies, leading to IgA-containing immune-complex deposits. This case highlights the urgency of understanding the immunological responses to novel mRNA-based SARS-CoV-2 vaccines in more diverse populations. Despite the lack of clear causality, nephrologists should be alerted if any new-onset hematuria or proteinuria is observed.

Aberrantly Glycosylated IgA1 in IgA Nephropathy: What We Know and What We Don't Know

IgA nephropathy (IgAN), the most common primary glomerular disease worldwide, is characterized by glomerular deposition of IgA1-containing immune complexes. The IgA1 hinge region (HR) has up to six clustered O-glycans consisting of Ser/Thr-linked N-acetylgalactosamine usually with β1,3-linked galactose and variable sialylation. Circulating levels of IgA1 with abnormally O-glycosylated HR, termed galactose-deficient IgA1 (Gd-IgA1), are increased in patients with IgAN. Current evidence suggests that IgAN is induced by multiple sequential pathogenic steps, and production of aberrantly glycosylated IgA1 is considered the initial step. Thus, the mechanisms of biosynthesis of aberrantly glycosylated IgA1 and the involvement of aberrant glycoforms of IgA1 in disease development have been studied. Furthermore, Gd-IgA1 represents an attractive biomarker for IgAN, and its clinical significance is still being evaluated. To elucidate the pathogenesis of IgAN, it is important to deconvolute the biosynthetic origins of Gd-IgA1 and characterize the pathogenic IgA1 HR O-glycoform(s), including the glycan structures and their sites of attachment. These efforts will likely lead to development of new biomarkers. Here, we review the IgA1 HR O-glycosylation in general and the role of aberrantly glycosylated IgA1 in the pathogenesis of IgAN in particular.

Downregulation of miR‑214-3p attenuates mesangial hypercellularity by targeting PTEN‑mediated JNK/c-Jun signaling in IgA nephropathy

Mesangial cell (MC) proliferation and matrix expansion are basic pathological characteristics of IgA nephropathy (IgAN). However, the stepwise mechanism of MC proliferation and the exact set of related signaling molecules remain largely unclear. In this study, we found a significant upregulation of miR-214-3p in the renal cortex of IgAN mice by miRNA sequencing. In situ hybridization analysis showed that miR-214-3p expression was obviously elevated in MCs in the renal cortex in IgAN. Functionally, knockdown of miR-214-3p alleviated mesangial hypercellularity and renal lesions in IgAN mice. In vitro, the inhibition of miR-214-3p suppressed MC proliferation and arrested G1-S cell cycle pSrogression in IgAN. Mechanistically, a luciferase reporter assay verified PTEN as a direct target of miR-214-3p. Downregulation of miR-214-3p increased PTEN expression and reduced p-JNK and p-c-Jun levels, thereby inhibiting MC proliferation and ameliorating renal lesions in IgAN. Moreover, these changes could be attenuated by co-transfection with PTEN siRNA. Collectively, these results illustrated that miR-214-3p accelerated MC proliferation in IgAN by directly targeting PTEN to modulate JNK/c-Jun signaling. Therefore, miR-214-3p may represent a novel therapeutic target for IgAN.