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Abstract: FR-PO361

Abnormal Cytokine-Induced Responses in IgA1-Subpopulations Enhance Production of Galactose-Deficient IgA1, the Main Autoantigen in IgA Nephropathy

Session Information

  • CKD: Mechanisms - II
    November 08, 2019 | Location: Exhibit Hall, Walter E. Washington Convention Center
    Abstract Time: 10:00 AM - 12:00 PM

Category: CKD (Non-Dialysis)

  • 2103 CKD (Non-Dialysis): Mechanisms

Authors

  • Reily, Colin, University of Alabama at Birmingham, Birmingham, Alabama, United States
  • Julian, Bruce A., University of Alabama at Birmingham, Birmingham, Alabama, United States
  • Rizk, Dana, University of Alabama at Birmingham, Birmingham, Alabama, United States
  • Novak, Jan, University of Alabama at Birmingham, Birmingham, Alabama, United States
Background

IgA nephropathy (IgAN), the most common primary glomerulonephritis in the world, is characterized by glomerular IgA1 immunodeposits enriched for galactose-deficient IgA1 (Gd-IgA1). Patients with IgAN have elevated blood levels of Gd-IgA1. Gd-IgA1 blood levels also predict disease progression. IgAN patients often present with synpharyngitic hematuria, and have elevated serum levels of IL-6, indicating ongoing inflammation. Some cytokines increase Gd-IgA1 production by IgA1-secreting cells from IgAN patients. We hypothesized that Gd-IgA1 overproduction induced by a cytokine stimulation may involve only a subpopulation(s) of IgA1-producing cells and used single-cell transcriptome analysis of cells from IgAN patients and controls to test that hypothesis.

Methods

A mixture of cytokines mimicking those of T-follicular helper (Tfh) cells (IL-4, IL-6, IL-21, CD40L; 50 ng/mL) was used to activate immortalized Ig-producing cells from IgAN patients and healthy controls (HC) for 30 min before single-cell transcriptomic analysis. IgA1-secreting cells were identified using a splice-variant analysis to differentiate membrane vs. secreted isoforms. Resultant data were normalized using Seurat V2.4 and the curated data were analyzed with Alteryx. Gd-IgA1 production was assessed after cytokine stimulation for 72 h.

Results

Gd-IgA1 production increased in Ig-producing cells from IgAN patients but not HC after stimulation with Tfh cytokines. Several subpopulations of IgA1-secreting cells from IgAN patients exhibited substantial repression of genes associated with regulation of cytokine responses (e.g.,PTPN11, SOCS3, PTPN2,) due to Tfh cytokine stimulation (N=3, p <0.05). The same subpopulations also exhibited abnormal changes in glycosyltransferase genes implicated in Gd-IgA1 production.

Conclusion

We identified subpopulations of IgA1-secreting cells from IgAN patients that exhibited differential regulation of expression of glycosyltransferases due to abnormal Tfh-cytokine signaling. These data suggest that there are subpopulations of IgA1-producing cells that may be primarily responsible for Gd-IgA1 overproduction.

Funding

  • NIDDK Support