scholarly journals Macromolecular IgA1 taken from patients with familial IgA Nephropathy or their asymptomatic relatives have higher reactivity to mesangial cells in vitro

2009 ◽  
Vol 75 (12) ◽  
pp. 1330-1339 ◽  
Author(s):  
Ka Ying Tam ◽  
Joseph C.K. Leung ◽  
Loretta Y.Y. Chan ◽  
Man Fai Lam ◽  
Sydney C.W. Tang ◽  
...  
Keyword(s):  
Iga Nephropathy ◽  
Mesangial Cells

Mass spectrometry-based circulating IgA1 complexes screening driven identification of IgA-alpha-1-microglobulin complex in IgA nephropathy

2020 ◽  
Author(s):  
Boyang Xu ◽  
Li Zhu ◽  
Qingsong Wang ◽  
Yanfeng Zhao ◽  
Meng Jia ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Iga Nephropathy ◽  
Cell Injury ◽  
Mesangial Cell ◽  
Mesangial Cells ◽  
Independent Population ◽  
Tubulointerstitial Lesions ◽  
Noninvasive Biomarker

Abstract Background IgA nephropathy (IgAN) is characterized by predominant IgA deposition in the glomerular mesangium. Previous studies proved that renal-deposited IgA in IgAN came from circulating IgA1-containing complexes (CICs). Methods To explore the composition of CICs in IgAN, we isolated CICs from IgAN patients and healthy controls, and then quantitatively analyzed them by mass spectrometry. Meanwhile, the isolated CICs were used to treat human mesangial cells to monitor mesangial cell injury. Taken together the proteins content and injury effects, the key constituent in CICs was identified. Then, the circulating levels of identified key constituent-IgA complex were detected in an independent population by an in-house-developed ELISA. Results By comparing the proteins of CICs between IgAN patients and controls, we found that 14 proteins showed significantly different levels. Among them, alpha-1-microglobulin content in CICs was associated with not only in vitro mesangial cell proliferation and MCP-1 secretion but also in vivo eGFR levels and tubulointerstitial lesions in IgAN patients. Moreover, we found alpha-1-microglobulin was prone to bind aberrant glycosylated IgA1. Additionally, an elevated circulating IgA-alpha-1-microglobulin complex levels were detected in an independent IgAN population, and IgA-alpha-1-microglobulin complex levels were correlated with hypertension, eGFR levels and Oxford-T scores in these IgAN patients. Conclusions Our results suggest that the IgA-alpha-1-microglobulin complex is an important constituent in CICs, and that circulating IgA-alpha-1-microglobulin complex detection might serve as a potential noninvasive biomarker detection method for IgAN.

scholarly journals Sialylation of IgG inhibits the formation of galactose-deficient IgA1-containing immune complexes and protects mesangial cells from injury in IgA nephropathy

2022 ◽  
Vol 23 (1) ◽  
Author(s):  
Youxia Liu ◽  
Hongfen Li ◽  
Huyan Yu ◽  
Fanghao Wang ◽  
Junya Jia ◽  
...  
Keyword(s):  
Iga Nephropathy ◽  
B Lymphocytes ◽  
Immune Complexes ◽  
Mononuclear Cells ◽  
Mesangial Cells ◽  
Healthy Controls ◽  
Peripheral Blood Mononuclear ◽  
Tnf Α ◽  
Inflammatory State

Abstract Background The addition of sialic acid alters IgG from a pro-inflammatory state to an anti-inflammatory state. However, there is a lack of research on the changes of IgG sialylation in IgA nephropathy (IgAN). Methods This study included a total of 184 IgAN patients. The sialylated IgG (SA-IgG), IgG-galactose-deficient IgA1 complex (IgG-Gd-IgA1-IC), IL-6, TNF-α, and TGF-β were detected using commercial ELISA kits. SA-IgG, non-sialylated IgG (NSA-IgG), sialylated IgG-IgA1 complex (SA-IgG-IgA1), and non-sialylated IgG-IgA1 complex (NSA-IgG-IgA1) were purified from IgAN patients and healthy controls (HCs). Results The mean SA-IgG levels in plasma and B lymphocytes in IgAN patients were significantly higher than those of healthy controls. A positive correlation was found between SA-IgG levels in plasma and B lymphocytes. In vitro, the results showed that the release of IgG-Gd-IgA1-IC was significantly decreased in peripheral blood mononuclear cells (PBMCs) cultured with SA-IgG from both IgAN patients and healthy controls. The proliferation ability and the release of IL-6, TNF-α, and TGF-β in human mesangial cells (HMCs) were measured after stimulating with SA-IgG-IgA1-IC and NSA-IgG-IgA1-IC. The mesangial cell proliferation levels induced by NSA-IgG-IgA1-IC derived from IgAN patients were significantly higher than those caused by SA-IgG-IgA1-IC derived from IgAN patients and healthy controls. Compared with NSA-IgG-IgA1 from healthy controls, IgAN-NSA-IgG-IgA1 could significantly upregulate the expression of IL-6 and TNF-α in mesangial cells. The data showed that there weren’t any significant differences in the levels of IL-6, TNF-α, and TGF-β when treated with IgAN-SA-IgG-IgA1 and HC-NSA-IgG-IgA1. Conclusions The present study demonstrated that the sialylation of IgG increased in patients with IgA nephropathy. It exerted an inhibitory effect on the formation of Gd-IgA1-containing immune complexes in PBMCs and the proliferation and inflammation activation in mesangial cells.

scholarly journals The TLR4-MyD88-NF-κB pathway is involved in sIgA-mediated IgA nephropathy

2020 ◽  
Vol 33 (6) ◽  
pp. 1251-1261 ◽  
Author(s):  
Junjun Zhang ◽  
Yiming Mi ◽  
Ruwen Zhou ◽  
Zhangsuo Liu ◽  
Bo Huang ◽  
...  
Keyword(s):  
Iga Nephropathy ◽  
Mesangial Cells ◽  
Immunofluorescence Assay ◽  
Kidney Damage ◽  
Secretory Iga ◽  
Tnf Α ◽  
Mesangial Area ◽  
Enhanced Expression ◽  
Better Than

AbstractPrevious studies have shown that secretory IgA (sIgA) was critically involved in IgA nephropathy (IgAN) immune responses. Toll-like receptors (TLRs), especially TLR4 which participates in mucosal immunity, may be involved in the pathogenesis of IgAN. The purpose of this study was to investigate whether sIgA and TLR4 interact to mediate kidney damage in IgAN patients. IgAN patients with positive sIgA deposition in renal tissues were screened by immunofluorescence assay. Patient salivary sIgA (P-sIgA) was collected and purified by jacalin affinity chromatography. Salivary sIgA from healthy volunteers was used as a control (N-sIgA). Expression of TLR4, MyD88, NF-κB, TNF-α, IL-6, and MCP-1 were detected in the mesangial area of IgAN patients by immunohistochemistry, the expression levels in patients with positive sIgA deposition were higher than that with negative sIgA deposition. Human renal mesangial cells (HRMCs) were cultured in vitro, flow cytometry showed that P-sIgA bound HRMCs significantly better than N-sIgA. HRMCs were cultured in the presence of sIgA (400 μg/mL) for 24 h, compared with cells cultured with N-sIgA, HRMCs cultured in vitro with P-sIgA showed enhanced expression of TLR4, increased secretion of TNF-α, IL-6, and MCP-1, and increased expression of MyD88/NF-κB. TLR4 shRNA silencing and NF-κB inhibition both reduced the ability of HRMCs to synthesize TNF-α, IL-6, and MCP-1. Our results indicate that sIgA may induce high expression of TLR4 in HRMCs and further activate downstream signalling pathways, prompting HRMCs to secrete multiple cytokines and thereby mediating kidney damage in IgAN patients.

Collectin11 and Complement Activation in IgA Nephropathy

2021 ◽  
pp. CJN.04300321
Author(s):  
Min Wei ◽  
Wei-yi Guo ◽  
Bo-yang Xu ◽  
Su-fang Shi ◽  
Li-jun Liu ◽  
...  
Keyword(s):  
Iga Nephropathy ◽  
Complement Activation ◽  
Immune Complexes ◽  
Mesangial Cells ◽  
Kidney Injury ◽  
Lectin Pathway ◽  
Independent Manner ◽  
Proximity Ligation ◽  
Injury Model

Background and objectives: IgA nephropathy is the most common primary glomerulonephritis worldwide. Previous research demonstrated that collectin11, an initiator of complement lectin pathway, was involved in both acute kidney injury and chronic tubulointerstitial fibrosis. Here, we investigated the potential role of collectin11 in the pathogenesis of IgA nephropathy. Design, setting, participants, and measurements: The deposition of collectin11 and other complement proteins was detected in glomeruli of 60 participants with IgA nephropathy by immunofluorescence. In vitro, human mesangial cells were treated with IgA1-containing immune complexes derived from participants with IgA nephropathy. Then, the expression of collectin11 in mesangial cells was examined by RT-qPCR and immunofluorescence. The codeposition of collctin11 with IgA1 or C3 on mesangial cells was detected by immunofluorescence and proximity ligation assays. Results: 37% participants with IgA nephropathy (22/60) showed codeposition of collectin11 with IgA in the glomerular mesangium. Using an injury model of mesangial cells, we demonstrated that IgA1-immune complexes derived from participants with IgA nephropathy increased the secretion of collectin11 in mesangial cells with the subsequent deposition of collectin11 on the cell surface via the interaction with deposited IgA1-immune complexes. In vitro, we found that collectin11 bound to IgA1-immune complexes in a dose-dependent but calcium-independent manner. Furthermore, deposited collectin11 initiated the activation of complement and accelerated the deposition of C3 on mesangial cells. Conclusions: In situ-produced collectin11 by mesangial cells might play an essential role in kidney injury in a subset of patients with IgA nephropathy through the induction of complement activation.

scholarly journals Circulating serum lectins of patients with IgA nephropathy stimulate IL-6 release from mesangial cells.

1997 ◽  
Vol 8 (2) ◽  
pp. 208-213
Author(s):  
C Libetta ◽  
T Rampino ◽  
G Palumbo ◽  
C Esposito ◽  
A Dal Canton
Keyword(s):  
Affinity Chromatography ◽  
Iga Nephropathy ◽  
Mesangial Cells ◽  
Lectin Binding ◽  
Normal Serum ◽  
In Vitro Studies ◽  
Human Mesangial Cells ◽  
Serum Activity ◽  
Peripheral Leukocytes

Previously, the authors reported that the serum of patients with immunoglobulin (Ig) A nephropathy stimulated peripheral leukocytes, and this effect was inhibited by nominal haptens for lectins. In vitro studies have shown that lectins can bind to rat mesangial cells and cause their activation. This study was performed to investigate whether the serum of IgA nephropathy patients contains lectins that activate mesangial cells, i.e., induce release of interleukin (IL)-6, a nephritogenic cytokine. The serum of patients was adsorbed by affinity chromatography on resins loaded with lectin-binding sugars. After adsorption, serum supernatant was collected and the resins were then eluted. Human mesangial cells were conditioned with native serum, post-adsorption supernatant, and eluate (all three at 10%) for 24 h, and the release of IL-6 was determined by ELISA. Normal serum was used as control. Incubation of mesangial cells with IgA nephropathy patients serum raised average IL-6 release from 8.5 pg/mL to 274.1 pg/mL. Adsorption in beta-D-glucose and N-acetyl-D-glucosamine caused a fall in the activity of patients' serum, to 17.0 and 63.7 pg/mL, respectively, and the activity lost was recovered in the eluate (185.2 and 142.7 pg/mL, respectively). Neither adsorption on N-acetyl-D-galactosamine nor on fucosylamine was associated with any effect on serum activity; accordingly, no activity was found in the eluates. Serum of patients with non-IgA mesangiocapillary nephritis did not stimulate mesangial cells. These results show that the serum of IgA nephropathy patients contains specific lectins that stimulate IL-6 nephropathy by mesangial cells and are, therefore, potential nephritogenic.

Activation of podocytes by mesangial-derived TNF-α: glomerulo-podocytic communication in IgA nephropathy

2008 ◽  
Vol 294 (4) ◽  
pp. F945-F955 ◽  
Author(s):  
Kar Neng Lai ◽  
Joseph C. K. Leung ◽  
Loretta Y. Y. Chan ◽  
Moin A. Saleem ◽  
Peter W. Mathieson ◽  
...  
Keyword(s):  
Iga Nephropathy ◽  
Mesangial Cell ◽  
Mesangial Cells ◽  
Neutralizing Antibody ◽  
Important Mediator ◽  
Tnf Α ◽  
Strategic Position ◽  
Inflammatory Changes

We have previously documented that human mesangial cell (HMC)-derived TNF-α is an important mediator involved in the glomerulo-tubular communication in the development of interstitial damage in IgA nephropathy (IgAN). With the strategic position of podocytes, we further examined the role of mesangial cells in the activation of podocytes in IgAN. There was no binding of IgA from patients with IgAN to podocytes. Podocytes cultured with IgA from patients with IgAN did not induce the release of growth factors or cytokines. Furthermore, podocytes did not express mRNA of known IgA receptors. In contrast, IgA-conditioned medium (IgA-HMC medium) prepared by culturing HMC with IgA from patients with IgAN for 48 h significantly increased the gene expression and protein synthesis of TNF-α by podocytes with a 17-fold concentration above that of IgA-HMC medium. The upregulation of TNF-α expression by podocyte was only abolished by a neutralizing antibody against TNF-α but not by other antibodies. Exogenous TNF-α upregulated the synthesis of TNF-α by podocytes in an autocrine fashion. IgA-HMC medium prepared with IgA from patients with IgAN also significantly upregulated the expression of both TNF-α receptor 1 and 2 in podocytes. Our in vitro finding suggests podocytes may play a contributory role in the development of interstitial damage in IgAN by amplifying the activation of tubular epithelial cells with enhanced TNF-α synthesis after inflammatory changes of HMC.

scholarly journals Glycosylation of Circulating IgA in Patients with IgA Nephropathy Modulates Proliferation and Apoptosis of Mesangial Cells

2001 ◽  
Vol 12 (9) ◽  
pp. 1862-1871 ◽  
Author(s):  
ALESSANDRO AMORE ◽  
PAOLA CIRINA ◽  
GIOVANNI CONTI ◽  
PAOLA BRUSA ◽  
LICIA PERUZZI ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Iga Nephropathy ◽  
Mesangial Cells ◽  
Enzyme Linked Immunosorbent Assay ◽  
Nitric Oxide Synthesis ◽  
Lectin Affinity Chromatography ◽  
Serum Iga ◽  
Proliferation And Apoptosis ◽  
Biologic Effects

Abstract. Abnormalities in circulating IgA1 have been demonstrated in patients with IgA nephropathy (IgAN). This study addresses the question of the functional significance of this alteration in creating mesangial injury. Biologic effects of selected IgA glycoforms isolated from serum of IgAN patients and controls and in vitro deglycosylated normal IgA were tested on cultured human mesangial cells (MC). IgA glycoforms, ranging from 250 to 500 kD molecular weight, were isolated by lectin affinity chromatography followed by HPLC. IgA and IgG content was measured by enzyme-linked immunosorbent assay. HPLC fractions were incubated with MC to evaluate proliferation and apoptosis rates and nitric oxide synthesis. Moreover, MC were conditioned with in vitro desialylated and degalactosylated normal IgA. Patients with IgAN displayed increased levels of IgA glycoforms exposing sialic acid in α2,6 linkage with N-acetylgalactosamine (Neu5Acα2,6GalNAc) (P < 0.02) and GalNAc (P < 0.05), indicating truncation of O-linked glycans of IgA1. Moreover, IgA glycoforms with increased exposure of mannose were observed (P < 0.03), suggesting a defective N-linked glycosylation. No modification in IgG glycosylation was detected. When incubated with MC, the IgA glycoforms isolated from patients with increased exposure of GalNAc, Neu5Acα2,6GalNAc, or mannose, significantly depressed the proliferation and increased the apoptotic rate and nitric oxide synthesis activity of cultured MC, in comparison with fractions isolated from controls. Similarly, in vitro desialylated and degalactosylated IgAs significantly depressed the proliferation and enhanced the apoptosis rates of MC. In conclusion, a significant modulation of several human MC functions exerted by serum IgA with increased exposure of GalNAc, Neu5Acα2,6GalNAc, and mannose residues isolated from IgAN patients is reported for the first time.

scholarly journals Immune Characteristics of IgA Nephropathy With Minimal Change Disease

2021 ◽  
Vol 12 ◽  
Author(s):  
Huixian Li ◽  
Wanhong Lu ◽  
Haiyun Li ◽  
Xiaoling Liu ◽  
Xue Zhang ◽  
...  
Keyword(s):  
Iga Nephropathy ◽  
Minimal Change Disease ◽  
Estimated Glomerular Filtration Rate ◽  
Mesangial Cells ◽  
Minimal Change ◽  
Substantial Evidence ◽  
Pathological Characteristics ◽  
High Degree ◽  
Degree Of Heterogeneity

Background: IgA nephropathy (IgAN) has a high degree of heterogeneity in clinical and pathological features. Among all subsets of IgAN, the pathogenesis of IgAN with minimal change disease (MCD-IgAN) remained controversial.Methods: We analyzed the clinical and pathological characteristics of MCD-IgAN patients in a retrospective cohort. Patients diagnosed with IgAN, excluding MCD-IgAN, were randomly selected as controls. Levels of plasma galactose-deficient IgA1 (GdIgA1), IgG autoantibodies against GdIgA1, GdIgA1 deposition in the glomerulus, and inflammatory reactivity of circulating poly-IgA1 complexes to cultured mesangial cells were evaluated.Results: Patients with MCD-IgAN had significantly higher levels of proteinuria and estimated glomerular filtration rate (eGFR), lower levels of albumin and urine blood cells, and milder histological lesions by a light microscope compared to IgAN patients, which bears a resemblance to MCD. Lower levels of GdIgA1 (3.41 ± 1.68 vs. 4.92 ± 2.30 μg/ml, p = 0.009) and IgG antiglycan autoantibodies (23.25 ± 22.59 vs. 76.58 ± 71.22 IU/ml, p &lt; 0.001) were found in MCD-IgAN patients than those in IgAN controls. Meanwhile, weaker fluorescence intensities of both IgA and GdIgA1 were observed in the glomerulus of MCD-IgAN patients compared to those in IgAN patients. Furthermore, poly-IgA1 complexes from MCD-IgAN patients induced weaker inflammatory effects on cultured mesangial cells than those from IgAN patients in vitro.Conclusion: The results demonstrated that MCD-IgAN cases represent a dual glomerulopathy, namely, mild IgAN with superimposed MCD, which furthermore provides substantial evidence for the corticosteroids therapy in MCD-IgAN patients as the guidelines recommended.

RNA-Seq profiling of microdissected glomeruli identifies potential biomarkers for human IgA nephropathy

2020 ◽  
Vol 319 (5) ◽  
pp. F809-F821
Author(s):  
Sehoon Park ◽  
Seung Hee Yang ◽  
Chang Wook Jeong ◽  
Kyung Chul Moon ◽  
Dong Ki Kim ◽  
...  
Keyword(s):  
Gene Ontology ◽  
Iga Nephropathy ◽  
Differentially Expressed Genes ◽  
Mesangial Cells ◽  
Principal Component ◽  
Differentially Expressed ◽  
Rna Seq ◽  
Ontology Term ◽  
Transcriptomic Profiling

Few studies have examined gene expression changes occurring in the glomeruli of IgA nephropathy (IgAN) using a sensitive transcriptomic profiling method such as RNA sequencing (RNA-Seq). We collected glomeruli from biopsy specimens from patients with IgAN with relatively preserved kidney function (estimated glomerular filtration rate ≥ 60 mL·min−1·1.73 m−2 and urine protein-to-creatinine ratio < 3 g/g) and from normal kidney cortexes by hand microdissection and performed RNA-Seq. Differentially expressed genes were identified, and gene ontology term annotation and pathway analysis were performed. Immunohistochemical labeling and primary mesangial cell cultures were performed to confirm the findings of RNA-Seq analysis. Fourteen patients with IgAN and ten controls were included in this study. Glomerulus-specific genes were highly abundant. Principal component analysis showed clear separation between the IgAN and control groups. There were 2,497 differentially expressed genes, of which 1,380 were upregulated and 1,117 were downregulated (false discovery rate < 0.01). The enriched gene ontology terms included motility/migration, protein/vesicle transport, and immune system, and kinase binding was the molecular function overrepresented in IgAN. B cell signaling, chemokine signal transduction, and Fcγ receptor-mediated phagocytosis were the canonical pathways overrepresented. In vitro experiments confirmed that spleen tyrosine kinase (SYK), reported as upregulated in the IgAN transcriptome, was also upregulated in glomeruli from an independent set of patients with IgAN and that treatment with patient-derived IgA1 increased the expression of SYK in mesangial cells. In conclusion, transcriptomic profiling of the IgAN glomerulus provides insights in the intraglomerular pathophysiology of IgAN before it reaches profound kidney dysfunction. SYK may have a pathogenetic role in IgAN.

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