Pathophysiology of IgA Nephropathy

Molecular characterization of m6A RNA methylation regulators with features of immune dysregulation in IgA nephropathy

The role of RNA N6-methyladenosine (m6A) modification in immunity is being elucidated. This study aimed to explore the potential association between m6A regulators and the immune microenvironment in IgA nephropathy (IgAN). The expression profiles of 24 m6A regulators in 107 IgAN patients were obtained from the Gene Expression Omnibus (GEO) database. The least absolute shrinkage and selection operator (LASSO) regression and logistic regression analysis were utilized to construct a model for distinguishing IgAN from control samples. Based on the expression levels of m6A regulators, unsupervised clustering was used to identify m6A-induced molecular clusters in IgAN. Gene set enrichment analysis (GSEA) and immunocyte infiltration among different clusters were examined. The gene modules with the highest correlation for each of the three clusters were identified by weighted gene co-expression network analysis (WGCNA). A model containing 10 m6A regulators was developed using LASSO and logistic regression analyses. Three molecular clusters were determined using consensus clustering of 24 m6A regulators. A decrease in the expression level of YTHDF2 in IgAN samples was significantly negatively correlated with an increase in resting natural killer (NK) cell infiltration and was positively correlated with the abundance of M2 macrophage infiltration. The risk scores calculated by the nomogram were significantly higher for cluster-3, and the expression levels of m6A regulators in this cluster were generally low. Immunocyte infiltration and pathway enrichment results for cluster-3 differed significantly from those for the other two clusters. Finally, the expression of YTHDF2 was significantly decreased in IgAN based on immunohistochemical staining. This study demonstrated that m6A methylation regulators play a significant role in the regulation of the immune microenvironment in IgAN. Based on m6A regulator expression patterns, IgAN can be classified into multiple subtypes, which might provide additional insights into novel therapeutic methods for IgAN.

The Clinical and Pathological Effects of Serum C3 Level and Mesangial C3 Intensity in Patients with IgA Nephropathy

Objective

To investigate the clinical and pathological effects of serum C3 level, mesangial C3 deposition intensity and blood lipid on IgA nephropathy.

Methods

According to the deposition intensity of immunofluorescence (IF) complement C3 in mesangial region, a total of 151 patients were divided into: (1) negative group (65 cases), (2) weak positive group (51 cases), and (3) strong positive group (35 cases). According to the level of serum C3, the patients were divided into two groups: (1) 33 patients with decreased serum C3 (<85 mg/dL); (2) 118 patients with normal serum C3. The clinicopathological data of the patients were analyzed retrospectively according to the groups.

Results

(1) With the increase of C3 deposition in mesangial region, the mean value of serum C3 level decreased, and the difference was statistically significant (P=0.001). (2) Compared with the normal serum C3 group, the blood urea nitrogen (BUN), serum creatinine (Scr), and albumin (Alb) in the serum C3 decreased group were higher, and the differences were statistically significant (P < 0.05), while the fasting blood glucose (FBG), low-density lipoprotein (LDL), triglyceride and 24-hr urinary protein (24hUTP) were lower, which difference was statistically significant (P < 0.05). (3) Compared with negative group and weak positive group, BUN, uric acid (UA), and Scr were higher in the strong positive group with C3 deposition, while eGFR was lower, with statistical significance (P < 0.05). However, C3 deposition in the mesangial region was related to T and enhanced mesangial C3 deposition was associated with more severe tubular atrophy and/or interstitial fibrosis, with statistically significant differences (P=0.001).

Conclusion

Patients with strong mesangial C3 deposition and elevated lipid levels had more severe tubule atrophy and/or interstitial fibrosis, as well as more severe pathological lesions, suggesting that activation of the complement system is involved in the pathogenesis of IgA nephropathy and increases the metabolic burden of the kidney.

Overlap of Primary Membranous Nephropathy, IgA Nephropathy, and Diabetic Nephropathy: A Case Report

The coexistence of primary membranous nephropathy (PMN), immunoglobulin A nephropathy (IgAN), and diabetic nephropathy (DN) in the same patient has been a subject of clinical and pathological investigation, yielding inconclusive results. The limited availability of cases and resource materials has hindered a comprehensive understanding of this phenomenon. We present the case of a 70-year-old Saudi Arabian man diagnosed with type 2 diabetes mellitus and nephrotic syndrome. A kidney biopsy revealed the coexistence of PMN, IgAN, and DN. The patient presented with an unusual and rare combination of PMN, IgAN, and DN. To address his condition, the patient consented to rituximab therapy and planned follow-up with the kidney transplant team. However, before the first dose of rituximab could be administered, the patient experienced severe septic shock secondary to pneumonia, which tragically led to his demise. The simultaneous occurrence of PMN, IgAN, and DN represents a rare and scarcely documented condition. The purpose of this article is to report this exceptional case, emphasizing the significance of further research to deepen the understanding of the underlying pathology behind these concurrent renal disorders. This report aims to shed light on the complexities of managing such complex cases and advancing therapeutic approaches in the future.

Clinical significance of IgM and C3 deposition in children with primary immunoglobulin A nephropathy

BACKGROUND

Mesangial IgM and C3 deposition is commonly observed in patients with primary immunoglobulin A nephropathy (IgAN), but its characteristics and prognosis have rarely been reported. The aim of this study was to investigate the relationship between combined mesangial IgM and C3 deposition and disease progression in children with IgAN.

METHODS

One hundred sixteen children diagnosed with IgAN between 2016 and 2020 were selected. Renal biopsies were scored by Oxford classification including the presence of mesangial hypercellularity, endocapillary hypercellularity, segmental glomerulosclerosis, tubular atrophy/interstitial fibrosis and crescents. The primary renal outcome was an event of either ≥ 50% reduction of eGFR from the baseline value or the onset of end-stage renal disease within the follow-up period. Cox regression analysis was performed to examine the effect of the combined mesangial IgM and C3 deposition on renal outcomes.

RESULTS

Forty-seven (40.52%) patients presented combined mesangial IgM and C3 deposition. Compared with children without combined IgM and C3 deposition, children with combined IgM and C3 deposition presented higher mesangial hypercellularity, endocapillary hypercellularity and cresentic lesions in kidney biopsies, and higher prevalence of renal dysfunction (19.15% versus 2.90%; P = 0.007). Renal outcome was also significantly worse as revealed by Kaplan-Meier curves (P = 0.0034). Multivariable Cox analysis identified tubular atrophy/interstitial fibrosis lesions [hazard ratio (HR) 14.843, 95% CI, 3.497-62.997, P < 0.001] and intensity of IgM deposition (HR 2.838, 95% CI, 1.321-6.094, P = 0.007) as independent risk factors for poor renal function.

CONCLUSIONS

Combined mesangial IgM and C3 deposition was associated with unfavorable histopathological features. Mesangial IgM deposition was an independent risk factor for poor renal outcomes in children with primary IgAN.

Immune abnormalities in IgA nephropathy

Immunoglobulin A (IgA) nephropathy (IgAN) is the most common primary glomerulonephritis worldwide and it is characterized by mesangial IgA deposition. Asymptomatic hematuria with various degrees of proteinuria is the most common clinical presentation and up to 20%-40% of patients develop end-stage kidney disease within 20 years after disease onset. The pathogenesis of IgAN involves four sequential processes known as the "four-hit hypothesis" which starts with the production of a galactose-deficient IgA1 (gd-IgA1), followed by the formation of anti-gd-IgA1 IgG or IgA1 autoantibodies and immune complexes that ultimately deposit in the glomerular mesangium, leading to inflammation and injury. Although several key questions about the production of gd-IgA1 and the formation of anti-gd-IgA1 antibodies remain unanswered, a growing body of evidence is shedding light on the innate and adaptive immune mechanisms involved in this complex pathogenic process. Herein, we will focus on these mechanisms that, along with genetic and environmental factors, are thought to play a key role in disease pathogenesis.

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.

Cytoplasmic WT1 in IgA nephropathy, an indicator of poor prognosis associated with mesangial/peri-mesangial C4d

BACKGROUND

We aimed to investigate the immuno-histochemical expression of C4d, ADAM10 and WT1 in kidney biopsies of immunoglobulin A nephropathy (IgAN) patients and correlate the findings with clinical, laboratory and histopathologic features in the hope of defining new parameters to better understand the pathogenesis of the disease, and predict prognosis.

MATERIALS AND METHODS

Paraffin-embedded kidney biopsy samples of 128 IgAN patients were immuno-histochemically treated with C4d and ADAM10/WT1 dual stain. Results were evaluated according to Oxford classification parameters, epidemiologic features, laboratory findings at presentation and clinical follow-up.

RESULTS

We observed C4d positivity in 40.6% of our patients, 25% of which was mesangial/peri-mesangial (m/pm) staining. Only m/pmC4d positivity statistically correlated with progression to end-stage renal disease (ESRD). M/pmC4d positive patients had statistically significantly higher baseline proteinuria levels, presence of crescents and > 25% segmental sclerosis of glomeruli. There was cytoplasmic staining of WT1 in 11.2% of cases. Presence of cWT1 correlated with m/pmC4d positivity and progression to ESRD. There was no glomerular ADAM10 detected and tubular expression of this protein did not relate to amount of tubular damage or other parameters.

CONCLUSION

This study is the first to show that cWT1is involved in IgAN and appears as an independent variable for worse prognosis.

An Update on the Effects of Vitamin D on the Immune System and Autoimmune Diseases

Vitamin D intervenes in calcium and phosphate metabolism and bone homeostasis. Experimental studies have shown that 1,25-dihydroxyvitamin D (calcitriol) generates immunologic activities on the innate and adaptive immune system and endothelial membrane stability. Low levels of serum 25-hydroxyvitamin D (25(OH)D) are associated with an increased risk of developing immune-related diseases such as psoriasis, type 1 diabetes, multiple sclerosis, and autoimmune diseases. Various clinical trials describe the efficacy of supplementation of vitamin D and its metabolites for treating these diseases that result in variable outcomes. Different disease outcomes are observed in treatment with vitamin D as high inter-individual difference is present with complex gene expression in human peripheral blood mononuclear cells. However, it is still not fully known what level of serum 25(OH)D is needed. The current recommendation is to increase vitamin D intake and have enough sunlight exposure to have serum 25(OH)D at a level of 30 ng/mL (75 nmol/L) and better at 40–60 ng/mL (100–150 nmol/L) to obtain the optimal health benefits of vitamin D.

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

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

Implications of Sphingolipid Metabolites in Kidney Diseases

Sphingolipids, which act as a bioactive signaling molecules, are involved in several cellular processes such as cell survival, proliferation, migration and apoptosis. An imbalance in the levels of sphingolipids can be lethal to cells. Abnormalities in the levels of sphingolipids are associated with several human diseases including kidney diseases. Several studies demonstrate that sphingolipids play an important role in maintaining proper renal function. Sphingolipids can alter the glomerular filtration barrier by affecting the functioning of podocytes, which are key cellular components of the glomerular filtration barrier. This review summarizes the studies in our understanding of the regulation of sphingolipid signaling in kidney diseases, especially in glomerular and tubulointerstitial diseases, and the potential to target sphingolipid pathways in developing therapeutics for the treatment of renal diseases.

Immunoglobulin A (IgA) Nephropathy: A Clinicopathologic Study in a Tertiary Care Center in Saudi Arabia

Background: Immunoglobulin A nephropathy (IgAN) is the most common primary aetiology of glomerulonephritis worldwide, and it is the most important type in terms of morbidity and mortality. IgAN involves the deposition of immune bodies in the mesangial cells of the kidney, which causes renal glomerular damage, haematuria, proteinuria, and various other symptoms. Previous studies have mainly focused on the East Asian population, with few studies conducted in Saudi Arabia, particularly in the western region. The diagnosis requires a biopsy, which should be examined by an expert and classified according to the Oxford classification system.

Objectives: Analyze the clinical, pathological, and laboratory features of male and female patients diagnosed with IgAN at King Abdulaziz University Hospital (KAUH).

Methods and materials: This was a retrospective record review conducted at KAUH in Jeddah, Saudi Arabia between May-June 2021. The study included 18 patients diagnosed with IgAN by biopsy, and their clinical, laboratory and pathological data were evaluated and classified according to the Oxford classification system.

Results: Demographic data revealed a male predominance of 66.7%. The most common pathological finding was mesangial proliferation, and the most common presentation was haematuria. For treatment options, corticosteroids were the most prescribed drugs. A significant relationship was found between IgAN with increased serum creatinine and male sex (P = 0.017). Additionally, a significant relationship was observed between decreased estimated glomerular filtration rate (eGFR) in IgAN and the male sex (P = 0.006).

Conclusions: We found a difference in terms of pathological, clinical and laboratory presentations of IgAN between males and females. Men generally had worse kidney function at presentation and advanced Oxford classification in their kidney biopsies compared to women.

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

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

Efficacy and safety of immunosuppressive therapies in the treatment of high-risk IgA nephropathy: A network meta-analysis

BACKGROUND

IgA nephropathy (IgAN) is one of the significant contributing factors of end-stage renal disease (ESRD). It is reported that over half of patients with IgAN accompany multiple high-risk factors, which increase the risk of ESRD progression. Studies have shown that immunosuppressive agents were beneficial in high-risk IgAN, but the efficacy and safety have not been fully demonstrated yet. The present study aims to elucidate the efficacy of commonly used immunosuppressants in high-risk IgAN and their relative safety profiles via a network meta-analysis strategy.

METHODS

Randomized controlled trials (RCTs) eligible for this network meta-analysis were included to evaluate the efficacy and safety of different immunosuppressants for high-risk IgAN. Main outcomes and measures include incidence of renal composite end point, the rate of total remission, adverse events, and proteinuria. Besides, subgroup analysis and cluster analysis were carried out.

RESULTS

This network meta-analysis of 37 RCTs involving 3012 participants found that Mycophenolate mofetil (MMF) combined with corticosteroids (CS) was superior to other interventions in end point events and proteinuria. Cyclosporine A (CsA) plus CS was the best option for clinical remission rate, and supportive care (SC) was the safest treatment. Cluster analysis showed that MMF+CS and Leflunomide (LEF)+CS were best protocols in efficacy and safety. Subgroup analysis indicated the best benefits of MMF were presented among the Asian population, and the benefits increased with the increase of follow-up duration. The effect of Cyclophosphamide (CTX) +CS on crescent IgAN was better than that of other risk factors. Moreover, the increasing follow-up duration was negatively associated with the effect.

CONCLUSIONS

MMF+CS and LEF+CS appear to serve as the best choice for treating high-risk IgAN than other immunosuppressive therapies.

Immunofluorescence deposits in the mesangial area and glomerular capillary loops did not affect the prognosis of immunoglobulin a nephropathy except C1q:a single-center retrospective study

Background

Immunoglobulin A nephropathy (IgAN) is identified as mesangial IgA deposition and is usually accompanied by other immunofluorescence deposits. The impact of immunofluorescent features in IgAN patients, however, remains unclear.

Methods

Baseline clinicopathologic parameters and renal outcomes of 337 patients diagnosed with IgAN between January 2009 and December 2015 were analyzed. We then categorized these patients into four groups: without immunofluorescence deposits, mesangial-only, mesangial and glomerular capillary loops (GCLs), and GCLs-only. The study endpoint was end-stage kidney disease (ESKD) or a ≥ 50% decline in the estimated glomerular filtration rate (eGFR). Kaplan–Meier and Cox regression analyses were performed to calculate renal survival.

Results

Of the 337 IgAN patients, women comprised 57.0%. Compared to patients with IgA deposition in the mesangial-only group, patients with IgA deposition in the mesangial +GCLs group were much heavier, and exhibited higher systolic blood pressure, lower serum IgG levels, and heavier proteinuria (all P < 0.05). Patients with IgG deposition in the mesangial +GCLs group presented with higher levels of cholesterol, heavier proteinuria than IgG deposition in the mesangial-only group (both P < 0.05). Compared with the mesangial-only group exhibiting C3 deposits, patients in the mesangial +GCLs group with C3 deposition had a higher systolic blood pressure (P = 0.028). A total of 38 patients (11.3%) continued to the study endpoint after a median follow-up time of 63.5 months (range,49.8–81.4). Kaplan–Meier analysis and Cox regression analysis showed that C1q deposition in the mesangial +GCLs group predicted a poor renal prognosis.

Conclusions

IgA and IgG deposits in the mesangial region and GCLs were associated with more unfavorable clinical and histopathologic findings in IgAN patients. C1q deposition in the mesangial region and GCLs predicted a poor renal prognosis. However, the impact of the pattern of immunofluorescence deposits on renal outcomes remains to be proven by further investigation.

microRNA-630 Regulates Underglycosylated IgA1 Production in the Tonsils by Targeting TLR4 in IgA Nephropathy

IgA nephropathy (IgAN) is the most common primary glomerular disease. The characteristic pathology involves immune complexes formed by the deposition of IgA1 and underglycosylated IgA1 aggregates in the mesangial area, which may be accompanied by the deposition of IgG and/or IgM and complement components. However, the molecular mechanisms of IgAN remain unclear. In the present study, microarray analysis showed that the expression of microRNA-630 (miR-630) was significantly reduced in palatal tonsils from IgAN patients compared with chronic tonsillitis. Additionally, bioinformatic analysis showed that Toll-like receptor 4 (TLR4) was the predicted target gene of miR-630 and was regulated by miR-630. When miR-630 was overexpressed in palatal tonsil mononuclear cells from IgAN patients, the expression of TLR4 was reduced and the content of IgA1 in the cell culture supernatant was decreased, and the level of galactosylation in the IgA1 hinge region was increased. Moreover, immunohistochemical analysis showed that the expression of TLR4 in IgAN patients was significantly increased. After knocking down the expression of TLR4, both the concentration of IgA1 and the binding force of IgA1 with broad bean lectin were significantly reduced in IgAN. Furthermore, the mechanism study demonstrated that TLR4 might regulate the expression of IL-1β and IL-8 through NF-κB signaling pathway to modulate the concentration of IgA1 and the glycosylation level of IgA1. This interesting finding may offer new insight into the molecular mechanism of IgAN.

Emerging role of vitamin D in autoimmune diseases: An update on evidence and therapeutic implications

Vitamin D plays a key role in in calcium homeostasis and, thus, provides an important support in bone growth by aiding in the mineralization of the collagen matrix. However, vitamin D performs various immunomodulatory, anti-inflammatory, antioxidant and anti-fibrotic actions. Autoimmune diseases result from an aberrant activation of the immune system, whereby the immune response is directed against harmless self-antigens. Does vitamin D play a role in the pathophysiology of autoimmune diseases? And, if so, what is its role? In the last decade, researchers' interest in vitamin D and its correlations with autoimmune diseases has considerably increased. We conducted a literature review, covering the period January 1, 2009 through March 30, 2019, in PubMed. We analyzed more than 130 studies in order to find a correlation between vitamin D levels and its effect upon several autoimmune diseases. The analysis demonstrated an inverse association between vitamin D and the development of several autoimmune diseases, such as SLE, thyrotoxicosis, type 1 DM, MS, iridocyclitis, Crohn's disease, ulcerative colitis, psoriasis vulgaris, seropositive RA, polymyalgia rheumatica. International multicenter study could allow us to confirm the data already present in the literature in the single clinical studies and to evaluate when to effectively supplement vitamin D in patients who do not take corticosteroids.

Analysis of the relationship between Oxford classification, IgM deposition and multiple indexes and the adverse prognosis of patients with primary IgA nephropathy and related risk factors

The risk and influencing factors of prognosis in patients with primary IgA nephropathy (IgAN) were explored. One hundred and twenty-four patients who were diagnosed with IgA nephropathy in West China Hospital of Sichuan University were selected as the study subjects. The baseline data were recorded. All patients were followed up for 3 years. Patients with poor prognosis were defined as poor prognosis group, and the patient with no adverse prognosis was defined as a good prognosis group during the follow-up period. The risk factors that may affect the prognosis of patients with IgAN were analyzed by single factor analysis. The influence of all factors that were statistically significant on the prognosis of the patients was further evaluated by multifactor Cox regression. The single factor analysis and multivariate Cox proportional hazard model showed that patients with 24 h urinary protein, pathological type, Oxford classification (T1+T2), Lee (grade IV) and mesangial IgM deposition were independent factors of patients, and the difference was statistically significant, their P-values were 0.041, 0.046, 0.037, 0.043, and 0.028, respectively. Patients with 24 h urinary protein, pathological type, Oxford classification (T1+T2), Lee (grade IV) and mesangial IgM deposition can be used as independent factors affecting poor prognosis in primary IgAN patients. It provides evidence for early detection of high-risk IgA nephropathy.

Efficacy and safety of mycophenolate mofetil for IgA nephropathy: An updated meta-analysis of randomized controlled trials

The efficacy and safety of mycophenolate mofetil (MMF) for immunoglobulin A nephropathy (IgAN) remains debatable. Therefore, the present meta-analysis was conducted with randomized controlled trials (RCTs). PubMed/MEDLINE, EMBASE and the Cochrane Central Register of Controlled Trials were analyzed to identify eligible trials. The pooled risk ratio (RR) with 95% confidence interval (CI) was estimated for all the dichotomous outcome measures. A total of eight RCTs with nine publications (n=510 patients) were included. No significant difference was noted between therapeutic regimens with and without MMF for renal remission and end stage renal disease (ESRD) of patients with IgAN (seven trials; RR, 1.250; 95% CI, 0.993–1.574; P=0.057; and four trials; RR, 0.728; 95% CI, 0.164–3.236; P=0.676). To further define the effects of MMF for renal remission, subgroup analysis was performed, demonstrating that MMF was significantly more effective compared with the placebo (three trials; RR, 2.152; 95% CI, 1.198–3.867; P=0.010), although the immunosuppressive regimens with MMF had no significantly different effects compared with those without MMF (four trials; RR, 1.140; 95% CI, 0.955–1.361; P=0.146), indicating that MMF was superior to placebo and had a similar efficacy to other immunosuppressants for renal remission. In addition, subgroup analysis for ESRD revealed no significant differences between MMF and placebo and between the immunosuppressive regimens with and without MMF (three trials; RR, 0.957; 95% CI, 0.160–5.726; P=0.962; and one trial; RR, 0.205; 95% CI, 0.010–4.200; P=0.303). Furthermore, there were no significant differences between the therapeutic regimens with and without MMF in terms of the risk of adverse events. The present meta-analysis demonstrated that MMF was more effective compared with the placebo, may have similar efficacy to other immunosuppressants in terms of inducing renal remission of IgAN and may not increase the risk of adverse events. The long-term effects of MMF on the prognosis of patients with IgAN require verification in further studies.

A pilot and comparative study between pathological and serological levels of immunoglobulin and complement among three kinds of primary glomerulonephritis

Background

Immunoglobulin A nephropathy (IgAN), membranous nephropathy (MN) and minimal-change disease (MCD) are three common types of glomerulonephritis in China. Pathological diagnosis based on renal biopsy is the criterion and the golden standard for diagnosing the sub-types of primary or secondary glomerulonephritis. Immunoglobulin and complements might be used in the differential diagnosis of glomerulonephritis without renal biopsies. However, the relationship between IF intensities of immune proteins and the corresponding serum levels remained unclear, and seldom studies combine histopathological examination results and blood tests together for a predictive purpose. This study was considered as a pilot study for integrating histopathological indicators into serum parameters for exploring the relationship of IF intensity and serum values of immunoglobulin and complement, and for screening and investigating effective indicators inIgAN, MN and MCD.

Methods

Renal tissue immunofluorescence (IF) intensity grades and serum levels of immunoglobulin and complements (IgG, IgA, IgM, C3 and C4) were retrospectively analyzed in 236 cases with IgAN, MN or MCD. IF grades were grouped as negative (−), positive (+) or strong positive (++) with both high and low magnification of microscope. Other serum indicators such as urea nitrogen (BUN), creatinine (Crea) and estimated glomerular filtration rate (eGFR) were also evaluated among the groups.

Results

There were difference in IgA, IgG and C3 IF intensity grades among IgAN, MN and MCD groups (p = 9.82E-43, 4.60E-39, 7.45E-15, respectively). Serum values of BUN, Crea, eGFR, IgG, IgA, IgM and C4 showed difference in three groups (BUN: p = 0.045, Crea: p = 3.45E-5, eGFR: p = 0.005, IgG: p = 1.68E-14, IgA: p = 9.14E-9, IgM: p = 0.014, C4: p = 0.026). eGFR had the trend to decrease with enhanced IgA IF positive grades (p = 8.99E-4); Crea had trends to decrease with both enhanced IgA and IgG IF intensity grades (p = 2.06E-6, 2.94E-5, respectively). In all subjects, serum IgA levels was inversely correlated with eGFR(r = − 0.216, p = 0.001) and correlated with Crea levels(r = 0.189, p = 0.004); serum IgG and Crea showed no correlation which were discordance with inverse correlation of IgG IF grade and Crea(r = 0.058,p = 0.379). IgG serum level was inverse correlated with its IF grades (p = 3.54E-5, p = 7.08E-6, respectively); C3 serum levels had significantly difference between Neg and positive (+) group (p = 0.0003). IgA serum level was positive correlated with its IF grades (Neg-(+): p = 0.0001; (+)-(++): p = 0.022; Neg-(++): p = 2.01E-10). After matching comparison among C3 groups, C3 Neg. group and C3 ++ group had difference (*p = 0.017). C4 had all negative IF expression in all pathological groups. In IgAN subjects, there were statistical differences of serum C3 levels between its pathological Neg and positive (+) group(p = 0.026), and serum IgA levels showed difference between IgA pathological positive(+) and (++)(p = 0.007). In MN subjects, sIgG levels showed difference between IgG pathological IF grade positive (+) and (++)(p = 0.044); serum C3 levels showed difference between C3 pathological IF grade Neg and positive(+)(p = 0.005); and serum IgA levels showed difference between Neg and positive(+)(p = 0.040). In IgAN, eGFR showed serum IgA levels had significant differences among groups (p = 0.007) and had increasing trend with enhanced its IF grades(P_trend = 0.016). There were also difference between IgG group Neg and positive (+) (p = 0.005, P_trend = 0.007) in IgAN. In MN, serum IgG levels had significant differences among IF groups (p = 0.034) and had decreasing trend with its enhanced IF grades (P_trend = 0.014). Serum C3 concentrations also were found distinctive among IF groups (p = 0.016) and had in inverse correlation with its enhanced IF grades (P_trend = 0.004).

Discussion

Our research cross contrasts several immunoprotein IF intensities and relevant serum levels in three kinds of primary glomerular nephritis, and finally acquired helpful results for understanding the relationships between pathological presentation and serological presentation of immunoproteins in kidney diseases. Furthermore, this pilot study is offering a possible method for the analysis of combination of pathology and serology.

Conclusion

Different pathological types of nephritis presented different expression patterns of immunoglobulin and complement, especially IgA and IgG, which suggested different pathogenesis involved in the development of IgAN and MN. Furthermore, either in tissue or in serum, increased IgA level was closely related with renal function in all of the patients.

Electronic supplementary material

The online version of this article (10.1186/s12865-018-0254-z) contains supplementary material, which is available to authorized users.

Efficacy and safety of tacrolimus combined with glucocorticoid treatment for IgA nephropathy: a meta-analysis

Objective

As a classical immunosuppressant, tacrolimus (TAC) has been widely used in organ transplantation therapy, but the general benefits of TAC for the treatment of IgA nephropathy (IgAN) remain uncertain. We conducted a meta-analysis to examine the effects of TAC combined with glucocorticoid on IgAN.

Methods

We searched the information databases PubMed/Medline, Embase, Science Citation Index, Chinese Biomedical Literature and the Chinese databases VIP, CNKI and Wan Fang for randomized controlled trials of TAC combined with glucocorticoid as a therapy for IgAN.

Results

Ten relevant studies involving 472 patients were included in a meta-analysis. Overall, the TAC group showed a significant decrease in proteinuria compared with the control group (MD: −0.18 g/d, 95% CI: −0.32 to −0.04). No increased risk of adverse events was observed (OR: 0.93, 95% CI: 0.65 to 1.33). In general, the TAC group showed good tolerance.

Conclusion

Evidence to date clearly indicates that TAC combined with glucocorticoid is quite effective in reducing proteinuria and albuminuria in patients with IgAN. Moreover, we found that patients receiving TAC therapy did not show an increased risk of side effects compared with control group patients. TAC combined with glucocorticoid is a promising medication and merits further research.

Identification of novel molecular signatures of IgA nephropathy through an integrative -omics analysis

IgA nephropathy (IgAN) is the most prevalent among primary glomerular diseases worldwide. Although our understanding of IgAN has advanced significantly, its underlying biology and potential drug targets are still unexplored. We investigated a combinatorial approach for the analysis of IgAN-relevant -omics data, aiming at identification of novel molecular signatures of the disease. Nine published urinary proteomics datasets were collected and the reported differentially expressed proteins in IgAN vs. healthy controls were integrated into known biological pathways. Proteins participating in these pathways were subjected to multi-step assessment, including investigation of IgAN transcriptomics datasets (Nephroseq database), their reported protein-protein interactions (STRING database), kidney tissue expression (Human Protein Atlas) and literature mining. Through this process, from an initial dataset of 232 proteins significantly associated with IgAN, 20 pathways were predicted, yielding 657 proteins for further analysis. Step-wise evaluation highlighted 20 proteins of possibly high relevance to IgAN and/or kidney disease. Experimental validation of 3 predicted relevant proteins, adenylyl cyclase-associated protein 1 (CAP1), SHC-transforming protein 1 (SHC1) and prolylcarboxypeptidase (PRCP) was performed by immunostaining of human kidney sections. Collectively, this study presents an integrative procedure for -omics data exploitation, giving rise to biologically relevant results.