IgAN Group Research Articles

IgA nephropathy recurrence after living donor kidney transplantation: a retrospective analysis of postoperative outcomes at a single high-volume transplant center

BackgroundIgA nephropathy (IgAN) is a common primary glomerulonephritis leading to end-stage renal disease. Living donor kidney transplantation (LDKT) is considered a favorable treatment option, but IgAN recurrence rates and the impact on outcome is unclear. In the present study, we retrospectively analyzed the rate of IgAN recurrence, risk factors and clinical outcomes in LDKT recipients.MethodsWe analyzed 193 adult patients who received a LDKT between 2011 and 2017 of which 32 (16.7%) had IgAN as underlying disease. Demographic data and clinical outcomes, especially regarding IgAN recurrence, were evaluated. Mean follow-up period was 102.13 months in the IgAN group vs. 97.27 months in the control group.ResultsAmong the IgAN cohort, five (15.63%) experienced IgAN recurrence. Patients with IgAN underwent LDKT at a significantly younger age (p < 0.001). No significant differences were observed in demographic factors, HLA-mismatches, or AB0-compatibility. Patients receiving an immunosuppressive regimen including Cyclosporine A (60% vs. 7.4%) instead of Tacrolimus (40% vs. 92.6%) were significantly more likely to develop IgAN recurrences (p < 0.001). Moreover, early post-surgery serum creatinine levels were higher in the recurrence group at one week (4.25 vs. 1.65 mg/dl; p < 0.001), one month (2.13 vs. 1.53 mg/dl; p = 0.027) and two years (2.65 vs. 1.34 mg/dl; p = 0.008). Although graft survival displayed a tendency towards inferior outcomes after recurrence, significance was not reached (p = 0.14, log-rank test).ConclusionLiving donor kidney transplantation continues to be recommended as the preferred treatment option for IgAN patients, despite the potential risk of recurrence and graft loss.

Clinical significance of urinary inflammatory biomarkers in patients with IgA nephropathy

BackgroundIgA nephropathy (IgAN) is the most common type of primary glomerulonephritis, although the definitive markers are unknown. We aimed to investigate the clinical significance of urinary cytokines in patients with IgAN.MethodsFrom 2009 to 2018, the patients were divided into three groups: IgAN (n = 191), disease control (n = 53), and normal control (n = 76). We used a multiplex enzyme-linked immunosorbent assay to measure 16 selected urinary inflammatory cytokines, evaluated the correlation between clinical and pathological features following regression analysis on progression.ResultsThe IgAN group exhibited significantly different levels of urinary cytokines compared to the normal control and disease control groups. Urinary levels of B-cell-activating factor, vascular endothelial growth factor receptor-2, monocyte chemoattractant protein-1, C–X–C motif chemokine 10, C–X–C motif ligand 16, epidermal growth factor (EGF), endocan, endostatin, growth/differentiation factor-15 (GDF-15), interleukin-6 (IL-6), mannose-binding lectin, transferrin receptor, and kidney injury molecule-1 were significantly correlated with both the estimated glomerular filtration rate and urine protein–creatinine ratio. In a multivariate Cox regression analysis, urinary EGF (hazard ratio [HR] 0.40, 95% confidence interval [CI] 0.17–0.95, P = 0.04), GDF-15 (HR 2.45, 95% CI 1.01–5.94, P = 0.048), and IL-6 (HR 3.02, 95% CI 1.05–8.64, P = 0.04) were associated with progression in IgAN.ConclusionsUrinary inflammatory biomarkers may serve as alternative predictive biomarkers in patients with IgAN. Further studies are needed to elucidate the physiological mechanisms and confirm the results.

A fast and efficient liquid chromatography-tandem mass spectrometry method for measuring l- and d-amino acids in the urine of patients with immunoglobulin A nephropathy.

Immunoglobulin nephropathy (IgAN) stands as the most prevalent primary glomerular nephropathy globally, typically diagnosed through an invasive renal biopsy. Emerging research suggests the significant involvement of chiral amino acids in kidney disease progression. This study introduces a nonderivative LC-tandem mass spectrometry approach, offering efficient separation outcomes within 15 min for identifying chiral amino acids in human urine samples. Subsequently, using this method, the analysis of l- and d-amino acids in the urine of both patients with IgAN and healthy individuals was conducted. Fourteen d-amino acids and 20 l-amino acids were identified in the urine samples obtained from 17 patients with IgAN and 21 healthy individuals. The results indicated notable variances in the concentrations of both l- and d-amino acids between the IgAN and healthy control groups. In contrast to the healthy group, the IgAN group exhibited higher mean urine concentrations of most l-amino acids and lower concentrations of d-amino acids. Furthermore, correlations between amino acids and clinical markers were investigated. These results propose a novel method for monitoring trace amino acids in urine samples and introduce a new concept for potential markers of IgAN.

Identification of GMFG as a novel biomarker in IgA nephropathy based on comprehensive bioinformatics analysis

BackgroundIgA nephropathy (IgAN) stands as the most prevalent form of glomerulonephritis and ranks among the leading causes of end-stage renal disease worldwide. Regrettably, we continue to grapple with the absence of dependable diagnostic markers and specific therapeutic agents for IgAN. Therefore, this study endeavors to explore novel biomarkers and potential therapeutic targets in IgAN, while also considering their relevance in the context of tumors. MethodsWe gathered IgAN datasets from the Gene Expression Omnibus (GEO) database. Subsequently, leveraging these datasets, we conducted an array of analyses, encompassing differential gene expression, weighted gene co-expression network analysis (WGCNA), machine learning, receiver operator characteristic (ROC) curve analysis, gene expression validation, clinical correlations, and immune infiltration. Finally, we carried out pan-cancer analysis based on hub gene. ResultsWe obtained 1391 differentially expressed genes (DEGs) in GSE93798 and 783 DGEs in GSE14795, respectively. identifying 69 common genes for further investigation. Subsequently, GMFG was identified the hub gene based on machine learning. In the verification set and the training set, the GMFG was higher in the IgAN group than in the healthy group and all of the GMFG area under the curve (AUC) was more 0.8. In addition, GMFG has a close relationship with the prognosis of malignancies and a range of immune cells. ConclusionsOur study suggests that GMFG could serve as a promising novel biomarker and potential therapeutic target for both IgAN and certain types of tumors.

Prognostic factors affecting long-term outcomes in patients with concurrent IgA nephropathy and membranous nephropathy

BackgroundThe incidence of concurrent immunoglobulin A nephropathy and membranous nephropathy (cIgAN/MN) is low and rarely reported, and the prognosis of patients with cIgAN/MN remains unclear. This study was designed to compare the clinical and prognostic characteristics of cIgAN/MN with IgAN and MN and to identify crucial factors influencing the outcomes of patients with cIgAN/MN. MethodsWe included biopsy-proven cIgAN/MN patients between December 2012 and December 2020 at Xijing Hospital. In the same period, propensity score matching was employed to select an equal number of IgAN and MN patients according to the following criteria: age, sex, and follow-up time. The primary endpoint was defined as a composite of eGFR decline ≥30 %, end-stage renal disease, or death. The patient survival rate was examined using Kaplan–Meier survival curves. Univariate and multivariate Cox regression analysis models were utilized to identify the risk factors affecting renal prognosis. ResultsA total of 135 patients were finally included in this study and 35 (25.9 %) reached the primary endpoint. The median follow-up time of cIgAN/MN was 45.9 (24.0, 72.0) months. Compared to the IgAN group, the cIgAN/MN group exhibited a lower cumulative incidence rate of composite renal endpoints (P = 0.044), while no significant difference was found between MN and cIgAN/MN patients (P = 0.211). Univariate Cox analysis revealed that mean arterial pressure, serum potassium, blood urea nitrogen, serum IgA, segmental glomerulosclerosis (S1), and MN staging were associated with an increased risk of renal composite endpoints. The multivariate Cox regression analysis of clinical variables plus histological lesion scoring demonstrated that potassium (HR = 14.350, 95 % CI 2.637–78.090, P = 0.002), serum IgA (HR = 1.870, 95 % CI 1.109–3.153, P = 0.019), and S1 (HR = 11.965, 95 % CI 2.166–66.105, P = 0.004) were independent risk factors influencing renal outcomes in cIgAN/MN patients. ConclusionThe prognosis of cIgAN/MN patients may exhibit an intermediate pattern between IgAN and MN, leaning towards being more similar to MN in certain aspects. Within the cIgAN/MN cohort, potassium, and serum IgA may be more predictive of rapid progression of renal endpoints, and S1 may indicate a more aggressive disease course.

Comparative proteomic analysis of glomerular proteins in IgA nephropathy and IgA vasculitis with nephritis

BackgroundIgA nephropathy (IgAN) and IgA vasculitis with nephritis (IgAVN) are related glomerular diseases characterized by marked similarities in immunological and histological findings. We herein performed a comparative proteomic analysis of glomerular proteins in IgAN and IgAVN.MethodsWe used renal biopsy specimens from 6 IgAN patients without nephrotic syndrome (NS) (IgAN-I subgroup), 6 IgAN patients with NS (IgAN-II subgroup), 6 IgAVN patients with 0–8.0% of glomeruli with crescent formation (IgAVN-I subgroup), 6 IgAVN patients with 21.2–44.8% of glomeruli with crescent formation (IgAVN-II subgroup), 9 IgAVN patients without NS (IgAVN-III subgroup), 3 IgAVN patients with NS (IgAN-IV subgroup), and 5 control cases. Proteins were extracted from laser microdissected glomeruli and analyzed using mass spectrometry. The relative abundance of proteins was compared between groups. An immunohistochemical validation study was also performed.ResultsMore than 850 proteins with high confidence were identified. A principal component analysis revealed a clear separation between IgAN and IgAVN patients and control cases. In further analyses, 546 proteins that were matched with ≥ 2 peptides were selected. The levels of immunoglobulins (IgA, IgG, and IgM), complements (C3, C4A, C5, and C9), complement factor H-related proteins (CFHR) 1 and 5, vitronectin, fibrinogen chains, and transforming growth factor-β inducible gene-h3 were higher (> 2.6 fold) in the IgAN and IgAVN subgroups than in the control group, whereas hornerin levels were lower (< 0.3 fold). Furthermore, C9 and CFHR1 levels were significantly higher in the IgAN group than in the IgAVN group. The abundance of some podocyte-associated proteins and glomerular basement membrane (GBM) proteins was significantly less in the IgAN-II subgroup than in the IgAN-I subgroup as well as in the IgAVN-IV subgroup than in the IgAVN-III subgroup. Among the IgAN and IgAVN subgroups, talin 1 was not detected in the IgAN-II subgroup. This result was supported by immunohistochemical findings.ConclusionsThe present results suggest shared molecular mechanisms for glomerular injury in IgAN and IgAVN, except for enhanced glomerular complement activation in IgAN. Differences in the protein abundance of podocyte-associated and GBM proteins between IgAN and IgAVN patients with and without NS may be associated with the severity of proteinuria.

Role of abnormal glycosylated IgA1 and interstitial transformation of glomerular endothelial cells in the development and progression of IgA nephropathy

BackgroundIgA nephropathy (IgAN) is a common primary renal disease in childhood.MethodsTwenty blood samples and renal tissue from patients with IgAN, 20 blood samples from healthy children and 10 normal renal tissue were collected. Serum Gd-IgA1 and renal Gd-IgA1, CD31, α-SMA and vimentin were measured.ResultsThe serum Gd-IgA1 concentration in the IgAN group was significantly higher. Gd-IgA1 was not expressed in normal kidneys, which was positive in the IgAN group. Gd-IgA1 levels in serum and renal tissue were not related. The expression of CD31 decreased significantly in IgAN group, while the expression of α-SMA and vimentin increased significantly. There was no significant correlation between the renal concentration of Gd-IgA1 and CD31, α-SMA and vimentin.ConclusionThe increased Gd-IgA1 in the serum and kidney may promote the pathogenesis of IgAN. The serum Gd-IgA1 cannot predict the extent of its deposition in the kidney. Endothelial mesenchymal transition (EndMT) may be involved in the pathogenesis of renal fibrosis in IgAN.

Discovery of Fibrinogen γ-chain as a potential urinary biomarker for renal interstitial fibrosis in IgA nephropathy

BackgroundIgA nephropathy (IgAN) is a major cause of chronic kidney disease (CKD). Renal interstitial fibrosis is a hallmark of CKD progression. Non-invasive biomarkers are needed to dynamically evaluate renal fibrosis. Data independent acquisition (DIA)-based liquid chromatography-mass spectrometry (DIA-MS) was used to identify candidate urinary biomarkers in IgAN patients with different renal interstitial fibrosis degrees.MethodsEighteen biopsy-proven IgAN patients and six healthy controls were recruited in a discovery cohort. Interstitial fibrosis changes were evaluated according to Oxford MEST-C scores. Urinary samples were analyzed with DIA-MS to identify hub proteins. Hub proteins were then confirmed by enzyme-linked immunosorbent assay (ELISA) in a validation cohort and the associated gene mRNA expression was analyzed using public gene expression omnibus (GEO) datasets.ResultsComplement and coagulation cascades pathway was the main KEGG pathway related to the over-expressed proteins. Fibrinogen γ-Chain (FGG) was selected as the potential urinary marker for further validation. Urinary FGG to creatinine ratio (uFGG/Cr) levels were higher in both disease controls and IgAN group than in healthy controls, but were not significantly different between IgAN and disease groups. uFGG/Cr was confirmed to be increased with the extent of renal fibrosis and presented moderate correlations with T score (r = 0.614, p < 0.01) and eGFR (r = -0.682, p < 0.01), and a mild correlation with UTP (r = 0.497, p < 0.01) in IgAN group. In disease control group, uFGG/Cr was higher in patients with T1 + 2 compared to those with T0. uFGG/Cr had a good discriminatory power to distinguish different fibrosis stages in IgAN: interstitial fibrosis ≤ 5% (minimal fibrosis) vs. interstitial fibrosis (mild fibrosis) > 5%, AUC 0.743; T0 vs. T1 + 2, AUC 0.839; T0 + 1 vs. T2, AUC 0.854. In disease control group, uFGG/Cr showed better performance of AUC than UTP between minimal and mild fibrosis (p = 0.038 for Delong’s test). Moreover, GSE104954 dataset showed that FGG mRNA expression was up-regulated (fold change 1.20, p = 0.009) in tubulointerstitium of IgAN patients when compared to healthy living kidney donors.ConclusionUrinary FGG is associated with renal interstitial fibrosis and could be used as a noninvasive biomarker for renal fibrosis in IgAN.

Landscape of intestinal microbiota in patients with IgA nephropathy, IgA vasculitis and Kawasaki disease.

To explore the common differential flora of IgAN, Kawasaki disease and IgA vasculitis by screening and analyzing the differential intestinal flora between the three disease groups of IgAN, Kawasaki disease and IgA vasculitis and their healthy controls. Papers on 16srRNA sequencing-related intestinal flora of IgAN, Kawasaki disease and IgA vasculitis were searched in databases, the literature was systematically collated and analysed, the original data was download from the relevant databases, and then the operational taxonomic unit and species classification analysis were performed. Besides, Alpha diversity analysis and Beta diversity analysis were performed to screen for IgAN, Kawasaki disease and I1gA vasculitis groups and finally compare the common intestinal differential flora among the three groups. Among the common differential flora screened, Lachnospiracea_incertae_sedis was lower in both the IgAN and Kawasaki disease groups than in the respective healthy controls; Coprococcus was low in the IgAN group but high in the IgA vasculitis group. Fusicatenibacter was lower in both the Kawasaki disease and IgA vasculitis groups than in their respective healthy controls, and Intestinibacter was low in the Kawasaki disease group, but its expression was high in the IgA vasculitis group. The dysbiosis of the intestinal flora in the three groups of patients with IgAN, Kawasaki disease and IgA vasculitis, its effect on the immunity of the organism and its role in the development of each disease group remain unclear, and the presence of their common differential flora may further provide new ideas for the association of the pathogenesis of the three diseases.

The Ratio of CD226 and TIGIT Expression in Tfh and PD-1+ICOS+Tfh Cells Are Potential Biomarkers for Chronic Antibody-Mediated Rejection in Kidney Transplantation.

Kidney transplantation is the ideal treatment for end-stage renal disease (ESRD). Chronic antibody-mediated rejection (CAMR) is the main cause of graft failure. Tfh and B cells are key immune cells that play important roles in CAMR. In this study, the populations of different Tfh cell phenotypes and B cell subsets in CAMR were investigated in a total of 36 patients. Based on Banff-2019, 15 patients were diagnosed with CAMR (CAMR group), 11 recipients were diagnosed with recurrent or de novo IgA nephropathy (IgAN group), and 10 patients displayed stable renal function (stable group). The Tfh and B cell subsets were analyzed by flow cytometry. The percentage and absolute number of PD-1+ICOS+Tfh cells were significantly higher in CAMR (p < 0.05), as was the ratio of CD226+Tfh cells to TIGIT+Tfh cells (p < 0.05). Compared with stable recipients, CAMR patients had lower naïve B cells and higher unswitched memory B cells, which were also significantly related to renal function (p < 0.05). Using the logistic regression model, we concluded that the estimated glomerular filtration rate (eGFR), absolute number of PD-1+ICOS+Tfh cells, and ratio of CD226+Tfh cells to TIGIT+Tfh cells were independent risk factors for CAMR. The combination of eGFR, PD-1+ICOS+Tfh cells, and the ratio of CD226+Tfh cells to TIGIT+Tfh cells showed better diagnostic efficacy for CAMR than each single parameter. The collective findings show that monitoring different Tfh phenotypes and B cell subsets is beneficial to kidney transplant recipients and implicate the combination of eGFR, number of PD-1+ICOS+Tfh cells, and ratio of CD226+Tfh cells to TIGIT+Tfh cells as a biomarker for diagnosing CAMR. The findings may also inform new strategies to identify and treat CAMR.

Efficacy of combination therapy for childhood complicated focal IgA nephropathy.

Patients with immunoglobulin A nephropathy who present with focal mesangial proliferation (focal IgAN) can have a relatively good prognosis, and renin-angiotensin system inhibitor (RAS-i) is commonly used as the initial treatment. However, there are some complicated focal IgAN cases with resistance to RAS-i treatment or nephrotic-range proteinuria. Thus, combination therapy including corticosteroids is often used. This study aimed to evaluate the efficacy of combination therapy for complicated focal IgAN cases by comparing to diffuse mesangial proliferation (diffuse IgAN). We conducted a multicenter retrospective study on 88 children who received 2-year combination therapy. The participants were classified based on pathological severity: focal IgAN (n = 26) and diffuse IgAN (n = 62). In total, 26 patients with focal IgAN and 52 with diffuse IgAN achieved proteinuria disappearance within 2years (100 vs. 83.9%, P = 0.03). Moreover, the time to proteinuria disappearance was significantly shorter in the focal IgAN group than in the diffuse IgAN group (2.9 vs. 4.2months, P < 0.01) and all patients with focal IgAN achieved proteinuria disappearance within 8months. At the last observation (8.6 vs. 10.4years, P = 0.13), only patients with diffuse IgAN (n = 12) had greater than stage 2 chronic kidney disease. In terms of irreversible adverse events, one patient exhibited cataracts. Combination therapy was significantly effective in patients with complicated focal IgAN. Moreover, the long-term prognosis was good, and the duration of combination therapy for complicated focal IgAN can be decreased to reduce adverse events.

The Gut and Blood Microbiome in IgA Nephropathy and Healthy Controls.

IgA nephropathy (IgAN) has been associated with gut dysbiosis, intestinal membrane disruption, and translocation of bacteria into blood. Our study aimed to understand the association of gut and blood microbiomes in patients with IgAN in relation to healthy controls. We conducted a case-control study with 20 patients with progressive IgAN, matched with 20 healthy controls, and analyzed bacterial DNA quantitatively in blood using 16S PCR and qualitatively in blood and stool using 16S metagenomic sequencing. We conducted between-group comparisons as well as comparisons between the blood and gut microbiomes. Higher median 16S bacterial DNA in blood was found in the IgAN group compared with the healthy controls group (7410 versus 6030 16S rDNA copies/μl blood, P=0.04). α- and β-Diversity in both blood and stool was largely similar between the IgAN and healthy groups. In patients with IgAN, in comparison with healthy controls, we observed higher proportions of the class Coriobacteriia and species of the genera Legionella, Enhydrobacter, and Parabacteroides in blood, and species of the genera Bacteroides, Escherichia-Shigella, and some Ruminococcus in stool. Taxa distribution were markedly different between the blood and stool samples of each subject in both IgAN and healthy groups, without any significant correlation between corresponding gut and blood phyla. Important bacterial taxonomic differences, quantitatively in blood and qualitatively in both blood and stool samples, that were detected between IgAN and healthy groups warrant further investigation into their roles in the pathogenesis of IgAN. Although gut bacterial translocation into blood may be one of the potential sources of the blood microbiome, marked taxonomic differences between gut and blood samples in each subject in both groups confirms that the blood microbiome does not directly reflect the gut microbiome. Further research is needed into other possible sites of origin and internal regulation of the blood microbiome.

Reduced fecal short-chain fatty acids levels and the relationship with gut microbiota in IgA nephropathy

BackgroundIgA nephropathy(IgAN)) is the common pathological type of glomerular diseases. The role of gut microbiota in mediating “gut-IgA nephropathy” has not received sufficient attention in the previous studies. The purpose of this study was to investigate the changes of fecal short-chain fatty acids(SCFAs), a metabolite of the intestinal microbiota, in patients with IgAN and its correlation with intestinal flora and clinical indicators, and to further investigate the role of the gut-renal axis in IgAN.MethodsThere were 29 patients with IgAN and 29 normal control subjects recruited from January 2018 to May 2018. The fresh feces were collected. The fecal SCFAs were measured by gas chromatography/mass spectrometry and gut microbiota was analysed by16S rDNA sequences, followed by estimation of α- and β-diversity. Correlation analysis was performed using the spearman’s correlation test between SCFAs and gut microbiota.ResultsThe levels of acetic acid, propionic acid, butyric acid, isobutyric acid and caproic acid in the IgAN patients were significantly reduced compared with control group(P < 0.05). Butyric acid(r=-0.336, P = 0.010) and isobutyric acid(r=-0.298, P = 0.022) were negatively correlated with urea acid; butyric acid(r=-0.316, P = 0.016) was negatively correlated with urea nitrogen; caproic acid(r=-0.415,P = 0.025) showed negative correlation with 24-h urine protein level.Exemplified by the results of α-diversity and β-diversity, the intestinal flora of IgAN patients was significantly different from that of the control group. Acetic acid was positively associated with c_Clostridia(r = 0.357, P = 0.008), o_Clostridiales(r = 0.357, P = 0.008) and g_Eubacterium_coprostanoligenes_group(r = 0.283, P = 0.036). Butyric acid was positively associated with g_Alistipes (r = 0.278, P = 0.040). The relative abundance of those were significantly decreased in IgAN group compared to control group.ConclusionsThe levels of fecal SCFAs in the IgAN patients were reduced, and correlated with clinical parameters and gut microbiota, which may be involved in the pathogenesis of IgAN, and this finding may provide a new therapeutic approach.

Low expression of estrogen receptor β in renal tubular epithelial cells may cause hyperuricemia in premenopausal patients with systemic lupus erythematosus.

We investigated the impact of estrogen receptor (ER) expression in renal tubular epithelial cells on serum uric acid (UA) levels in premenopausal patients with systemic lupus erythematosus (SLE). Thirty patients underwent renal biopsy: 18 with SLE (LN group) and 12 with IgA nephritis (IgAN group). ERs (ERα and ERβ) in renal tubular epithelial cells were measured using immunohistochemistry. The ER expression levels of the two groups were compared, and the relationship between the expression of ERs and serum UA levels was analyzed. Mean serum UA levels in the LN group were significantly higher than those of the IgA nephropathy group, while the mean creatinine levels and GFRs of the two groups were similar. Pathological changes in the LN group were significantly more severe than those in the IgAN group. ERβ was expressed in renal tubular epithelial cells in both groups, but not in the glomeruli. ERβ expression in the LN group was significantly lower than that in the IgAN group. ERβ expression scores significantly negatively correlated with serum UA levels. These findings suggest that the expression of ERβ in premenopausal female SLE patients may cause hyperuricemia, and may subsequently promote glomerular damage, suggesting that ERβ may be involved in UA excretion.

Bioinformatics analysis reveals novel hub gene pathways associated with IgA nephropathy

BackgroundImmunoglobulin A nephropathy (IgAN) is the most common primary glomerulopathy worldwide. However, the molecular events underlying IgAN remain to be fully elucidated. This study aimed to identify novel biomarkers of IgAN through bioinformatics analysis and elucidate the possible molecular mechanism.MethodsBased on the microarray datasets GSE93798 and GSE37460 downloaded from the Gene Expression Omnibus database, the differentially expressed genes (DEGs) between IgAN samples and normal controls were identified. Using the DEGs, we further performed a series of functional enrichment analyses. Protein–protein interaction (PPI) networks of the DEGs were constructed using the STRING online search tool and were visualized using Cytoscape. Next, hub genes were identified and the most important module among the DEGs, Biological Networks Gene Ontology tool (BiNGO), was used to elucidate the molecular mechanism of IgAN.ResultsIn total, 148 DEGs were identified, comprising 53 upregulated genes and 95 downregulated genes. Gene Ontology (GO) analysis indicated that the DEGs for IgAN were mainly enriched in extracellular exosome, region and space, fibroblast growth factor stimulus, inflammatory response, and innate immunity. Module analysis showed that genes in the top 1 significant module of the PPI network were mainly associated with innate immune response, integrin-mediated signaling pathway and inflammatory response. The top 10 hub genes were constructed in the PPI network, which could well distinguish the IgAN and control group in monocyte and tissue samples. We finally identified the integrin subunit beta 2 (ITGB2) and Fc fragment of IgE receptor Ig (FCER1G) genes that may play important roles in the development of IgAN.ConclusionsWe identified key genes along with the pathways that were most closely related to IgAN initiation and progression. Our results provide a more detailed molecular mechanism for the development of IgAN and novel candidate gene targets of IgAN.

P0347COMPLEMENT FACTOR BB AND FACTOR C4D IN IGA NEPHROPATHY AND IGA VASCULITIS

Abstract Background and Aims IgA nephropathy (IgAN) is the most common glomerulonephritis worldwide. IgAN and IgA Vasculitis with nephritis (IgAVN) are thought to have related pathogenesis characterized by IgA-containing renal immune complexes contributing to chronic kidney disease (CKD) and renal failure. In both diseases, IgA1 immune complexes and complement factors have been shown to be involved, indicating complement activation. However, the individual contribution of the alternative and lectin pathway has of yet not been fully elucidated. Plasma Bb is a marker of the alternative pathway activity and plasma C4d of the mannan-binding lectin pathway. We aimed to investigate the association between circulating plasma Bb and C4d at diagnosis and potential correlates with clinical features, renal histopathology and renal outcome in patients with IgAN and IgAVN. Method A prospective study of 98 patients undergoing renal biopsy was performed. Median age was 43 years, 52% males, 88% were caucasians, Sixty-six patients were diagnosed with IgAN, 15 IgAVN and 17 controls with “non-immunocomplex driven disease including Thin membrane disease, Diabetic Nephropathy, Minimal change disease or renal failure due to hyperfiltration. Blood samples were analyzed for complement factors C4d and Bb (both ELISA, Termo Fisher ScientificTM). Oxford classification of the renal biopsy was done at baseline and creatinine, estimated glomerular filtration rate (eGFR-CKD-EPI formula) were measured annually. Continuous data are expressed as median (25th to 75th percentile) and nominal or ordinal data as percentage. Comparisons between groups were assessed with the non-parametric Wilcoxon test/ Kruskal-Wallis ANOVA-test for continuous variables and Chi-square test for nominal variables. Results Patients with IgAN and IgAVN were significantly younger than the control group. There were no significant differences between the three groups for gender distribution and eGFR. Complement factor Bb for patients with IgAN and IgAVN was significantly increased (figure 1) as compared to the control group, whereas there was was no statistical difference for complement factorsC4d between groups. Estimated GFR decreased significantly only in patients with IgAN after 24 months of follow-up (56.6 ± 3.8 ml/min/1,73m2 as compared to IgAVN 83.8 ± 8.5 and controls 90.2 ± 8.9). Patients with IgAN had more severe histopathological changes in T-score (T-score 0, 1, 2 in IgAN 51 %, 37 % and 12 % respectively) compared to IgAVN. In the IgAN group a more severe T-score was significantly associated with increased levels of complement factor Bb (p=0.005) but did not reach significance for complement factor C4d (p=0.097). No other difference or correlations were found with regards to M, E, S and C % scores. Conclusion Patients with IgAN were younger and had increased levels of complement factor Bb and after 24 months follow-up significantly reduced eGFR. The increase in factor Bb was also associated with more severe histopathological changes in T-score. These findings suggest that the alternative complement pathway contributes to the pathogenesis in IgAN and chronic kidney damage. Our findings should motivate studies in a larger population to further clarify the role of complement activity in IgAN and IgAVN.

P0408KIDNEY TRANSPLANTATION OUTCOMES IN PATIENTS WITH IGA NEPHROPATHY IN THE MODERN ERA OF IMMUNOSUPPRESSION: A CASE CONTROL STUDY

Abstract Background and Aims Advances in immunosuppressants, used for kidney transplantation (KTx) have significantly improved outcomes in this field. We aimed to compare the long-term results of KTx in recipients with IgAN, as cause of end stage kidney disease (ESKD), with those of patients, with non-glomerular causes of renal failure, during the modern era of immunosuppression for KTx. Method This is a retrospective, case control study, in which were included patients who received a KTx after 2000. Patients were eligible to be included, if they had IgAN in a native kidney biopsy specimen and follow up longer than 1 year after KTx. IgAN patients were compared to a control-group of patients with non-glomerular primary causes of ESKD matched for age, gender, date of KTx and donor source. Graft biopsies were performed by clinical indication. Patients with ABO incompatible KTx, preemptive KTx, re-KTx, PRA&amp;gt;50%, major surgical complications during the 1st post-KTx month or non-compliance were excluded from the analysis of outcome. Primary outcomes of interest included graft function, patient and graft survival at end of follow up. The rate of IgAN recurrence in the graft and its impact in renal function and survival were also recorded. Computed GFR was calculated using the Modification of Diet in Renal Disease formula. Results A total of 102 KTx recipients with biopsy-proven IgAN, were compared to 204 controls with non-glomerular causes of ESKD. The mean age of patients with IgAN was 43.2(±10.15) years and 68(66.7%) were men. The mean time in dialysis was 50.2(±48.7) months and 59(57.8%) of them received a graft from a living donor. The mean cold ischemia time was 17.5(±6.7) hours, while 22(21.6%) of patients experienced delayed graft function. 97.05% of patients received induction therapy with an anti-CD25 inhibitor and 99.3% were maintained with a triple immunosuppressive regimen consisted of a mycophenolate mofetil formulation, a calcineurin inhibitor and glucocorticoids. The mean serum creatinine and eGFR at end of follow up were significantly lower for the IgAN group (p=0.001 and p=0.02 respectfully) with no difference in the frequency of acute rejection. However, graft and patient survival were not different even after controlling for follow up longer than one decade. During a mean follow up time of 120.8(±49.1) months, IgAN recurrence in the graft was documented in 23(22.5%) patients. The mean time to recurrence was 47.8(41.8) months, with a mean serum creatinine 1.83(±0.52) mg/dl and eGFR of 43.45(±18.4) ml/min/1.73m2 at the end of follow up. Within the IgAN group, although graft function was significantly lower in patients with disease recurrence, compared with that of patients without recurrence (p=0.003), graft loss remained not different between these two subgroups (p=0.49). Conclusion In the newer era of immunosuppression, long-term outcomes of KTx in patients with IgAN, as primary disease, appear significantly improved, and although graft function was significantly lower in patients with IgAN at the end of follow up, graft and patient survival was not different, compared to patients with non-glomerular causes of ESKD. Recurrence of IgAN in the graft was documented in 22.5% of patients and was associated with significantly lower eGFR at end of follow up compared to patients without recurrence but it did not impact graft survival in this time period.

P0354MATRIX ASSISTED LASER DESORPTION/IONIZATION MASS SPECTROMETRY IN PROTEIN ALTERATIONS ASSOCIATED WITH THE PROGRESSION OF IGA NEPHROPATHY DISCOVERY

Abstract Background and Aims IgA nephropathy (IgAN) is one of the most diffuse glomerulonephrites worldwide, but there are still many issues regarding its prognosis and pathogenesis understanding. Although the diagnosis is established by renal biopsy examination, there are still remaining pitfalls in primary origin discrimination, and therefore for prognosis and outcome for the patient. Method In this pilot study we performed matrix-assisted laser desorption/ionization (MALDI) mass spectrometry imaging (MSI) with a high spatial resolution (raster sampling of 20 μm) on formalin fixed paraffin embedded renal biopsies obtained from patients with IgAN (n=11) and other mesangioproliferative glomerulonephrites (MesPGN, n=6) attempting to enlighten proteomic alterations that may be associated with the progression of IgAN. The patients in both disease groups were separated according to their CKD stage (CKDI, CKDII, CKDIII and more). After MALDI-MSI analysis, all biopsies were stained with hematoxylin and eosin, scanned and overlaid with molecular image in order to verify the signals’ spatial distribution. Results Using MALDI-MSI we detected clear differences in the proteomic profiles of IgAN and other MesPGN tissues. Fourteen signals (AUC ≥ 0.8) were observed to have an altered intensity among the different CKD stages within the IgAN group. In particular, large increases in the intensity of these signals could be observed at CKD stages II and above. Putatively identified, these signals primarily corresponded to proteins involved in inflammatory and healing pathways and their increased intensity was localised within regions of tissue with large amounts of inflammatory cells or sclerosis (Figure 1), verified by immunohistochemical staining (Figure 2). Conclusion The capability of MALDI-MSI to provide highly spatially resolved proteomics analysis of complex renal tissue demonstrates it a useful additional diagnostic and prognostic tool and a promising approach in the search for prognostic or predictive markers in glomerular diseases.

C1GALT1 expression is associated with galactosylation of IgA1 in peripheral B lymphocyte in immunoglobulin a nephropathy

BackgroundMore and more studies demonstrated that genetic variation at C1GALT1 influences Gd-IgA1 level in IgAN. However, whether the expression of β1, 3-galactosyltransferase (β1, 3Gal-T) was influenced may provide insights into how Gd-IgA1 levels are controlled in IgAN.MethodsThirty IgAN patients diagnosed in Tianjin Medical University General Hospital from April to September 2018 and 30 healthy volunteers whose age and gender matched with patients were enrolled in this study. Total Gd-IgA1 levels in plasma were determined by ELISA and C1GALT1 levels were determined by RT-PCR. Four databases (PubMed, EMBASE, CNKI, WanFang Medical Network) were searched to identify eligible studies that evaluated a difference in the expression of C1GALT1 in IgAN patients compared with total controls (non-IgAN and health controls). The C1GALT1C1 expression levels, which was indispensable to β1, 3Gal-T of IgA1, was also been compared.ResultsGd-IgA1 levels were remarkable higher in IgAN patients compared with healthy control. The expression levels of C1GALT1 gene were remarkably down-regulated in IgAN patients compared with healthy control. And the mRNA level of C1GALT1 was inversely correlated to Gd-IgA1 levels. In meta-analysis, six articles including 316 participants that analyzed the expression of β1, 3Gal-T were met inclusion criteria. There was no significant difference in the expression of C1GALT1 between IgAN patients compared with controls. And we found patients with IgAN had lower levels of C1GALT1 gene expression in the B cells compared to controls. The C1GALT1C1 levels in the IgAN patients were not different from the levels in the control group, which were unchanged no matter according to different ethnic population, different control group and different cell source. Two studies including 46 persons compared enzymatic activity of β1, 3Gal-T in B cells, and the result showed the β1, 3Gal-T activity was decreased in B cells.ConclusionsWe found expression levels of C1GALT1 were remarkably downregulated in IgAN patients and negatively correlated with higher levels of Gd-IgA1. Subsequent meta-analysis validated the low expression and activity of β1, 3Gal-T in B cells in patients with IgAN. However, there was no apparent disparity in the aspect of C1GALT1C1 expression between IgAN and control groups.

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

BackgroundImmunoglobulin 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.MethodsRenal 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.ResultsThere 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(Ptrend = 0.016). There were also difference between IgG group Neg and positive (+) (p = 0.005, Ptrend = 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 (Ptrend = 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 (Ptrend = 0.004).DiscussionOur 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.ConclusionDifferent 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.