Background: This study investigated the significance of galactose-deficient immunoglobulin A1 staining in kidney diseases with IgA deposition.
Methods: A total of 120 patients with IgA-dominant deposition in kidney tissues were enrolled and divided into four groups: primary IgA nephropathy (PIgAN), secondary IgA nephropathy (SIgAN), monotypic IgA nephropathy (MIgAN), and IgA variant monoclonal gammopathy of renal significance (IgA-MGRS). KM55 (the antibody of galactose-deficient immunoglobulin A1), IgA subtypes, and complement pathway factors (properdin, C4d, and C1q) were detected through immunofluorescence or immunohistochemistry analysis.
Results: KM55 and IgA double staining showed colocalization within glomeruli in all cases except for IgA-MGRS, which showed negative or weak staining of KM55 but strong staining of IgA. The PIgAN group showed the highest intensity of KM55 and KM55/IgA ratio, while these values in the IgA-MGRS group were the lowest (P < 0.01). A KM55/IgA quantified ratio of 0.78 was the optimal cut-off value to distinguish PIgAN from SIgAN, whereas a cut-off value of 0.21 was optimal to distinguish between MIgAN and IgA-MGRS. The clinicopathological characteristics showed significant differences as the groups were divided by diseases with optimal cut-off values, and these differences corresponded to the pathogenesis of each disease entity.
Conclusions: PIgAN, SIgAN, and MIgAN are caused by the deposition of abnormally glycosylated IgA1 whereas IgA-MGRS is not. The KM55/IgA quantified ratio is valuable in distinguishing PIgAN from SIgAN, as well as MIgAN from IgA-MGRS.
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http://dx.doi.org/10.1007/s11255-023-03512-5 | DOI Listing |
CEN Case Rep
December 2024
Division of Nephrology and Hypertension, Department of Internal Medicine, The Jikei University School of Medicine, Minato-Ku, Tokyo, 105-8461, Japan.
Immunoglobulin A nephropathy (IgAN) is the most common primary glomerulonephritis worldwide with heterogeneous histopathological phenotypes. Although IgAN with membranoproliferative glomerulonephritis (MPGN)-like features has been reported in children and adults, treatment strategies for this rare IgAN subtype have not been established. Here, we present the case of a 56-year-old man with no history of kidney disease who initially presented with nephrotic syndrome.
View Article and Find Full Text PDFClin Chim Acta
January 2025
Department of Molecular Biochemistry and Clinical Investigation, Graduate School of Medicine, Osaka University, 1-7 Yamada-oka, Suita, Osaka 565-0871, Japan. Electronic address:
Galactose-deficient (agalactosyl) IgG is significantly increased in the serum of patients with rheumatoid arthritis, and autoantibodies against it are used in clinical tests. Subsequent studies also show increased agalactosyl IgG in many chronic inflammatory diseases. In this study, we generated antibody 42B1 recognizing agalactosyl IgG and developed a new method to evaluate chronic inflammatory diseases with it.
View Article and Find Full Text PDFInt J Mol Sci
October 2024
Department of Nephrology, Juntendo University Faculty of Medicine, Tokyo 113-8421, Japan.
IgA nephropathy (IgAN) is the most common type of primary glomerulonephritis worldwide; however, the underlying mechanisms of this disease are not fully understood. This review explores several animal models that provide insights into IgAN pathogenesis, emphasizing the roles of aberrant IgA1 glycosylation and immune complex formation. It discusses spontaneous, immunization, and transgenic models illustrating unique aspects of IgAN development and progression.
View Article and Find Full Text PDFFront Pediatr
October 2024
Department of Pediatrics, Sendai City Hospital, Sendai, Japan.
Clin Transl Sci
November 2024
Alpine Immune Sciences, a Vertex Company, Seattle, Washington, USA.
Therapeutic agents targeting the tumor necrosis factor (TNF) superfamily cytokines B-cell activating factor (BAFF, BLyS) and/or A PRoliferation Inducing Ligand (APRIL) have demonstrated clinical effectiveness in multiple autoimmune diseases, such as systemic lupus erythematosus, lupus nephritis, and immunoglobulin A nephropathy (IgAN). However, their clinical utility can often be limited by incomplete and/or prolonged times to clinical response and inconvenient dosing regimens, which may be improved by more potent dual inhibition of both cytokines. Povetacicept (ALPN-303; TACI vTD-Fc) is a crystallizable fragment (Fc) fusion protein of an engineered transmembrane activator and CAML interactor (TACI) domain which mediates more potent inhibitory activity than wild-type TACI-Fc or BAFF- or APRIL-specific antibodies and demonstrates superior pharmacokinetic and pharmacodynamic activity in multiple preclinical disease models.
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