ASN's Mission

ASN leads the fight to prevent, treat, and cure kidney diseases throughout the world by educating health professionals and scientists, advancing research and innovation, communicating new knowledge, and advocating for the highest quality care for patients.

learn more

Contact ASN

1401 H St, NW, Ste 900, Washington, DC 20005

email@asn-online.org

202-640-4660

The Latest on Twitter

Kidney Week

Abstract: PO1832

Single-Cell Transcriptomic Profiling Reveals Aberrant Signaling Responses to Tfh Cytokines in IgA1-Secreting Cells from IgA Nephropathy Patients

Session Information

Category: Glomerular Diseases

  • 1202 Glomerular Diseases: Immunology and Inflammation

Authors

  • Reily, Colin, University of Alabama at Birmingham, Departments of Medicine, Microbiology and Genetics, Birmingham, Alabama, United States
  • Nakazawa, Shigeaki, Osaka University Graduate School of Medicine, Department of Urology, Osaka, Japan
  • Kamata, Masakazu, University of Alabama at Birmingham, Departments of Medicine, Microbiology and Genetics, Birmingham, Alabama, United States
  • Crossman, David K., University of Alabama at Birmingham, Departments of Medicine, Microbiology and Genetics, Birmingham, Alabama, United States
  • Rizk, Dana, University of Alabama at Birmingham, Departments of Medicine, Microbiology and Genetics, Birmingham, Alabama, United States
  • Julian, Bruce A., University of Alabama at Birmingham, Departments of Medicine, Microbiology and Genetics, Birmingham, Alabama, United States
  • Novak, Jan, University of Alabama at Birmingham, Departments of Medicine, Microbiology and Genetics, Birmingham, Alabama, United States
Background

IgA nephropathy (IgAN), a common primary glomerulonephritis, is characterized by glomerular IgA1 immunodeposits enriched for galactose-deficient IgA1 (Gd-IgA1). These immunodeposits are likely derived from Gd-IgA1-containing immune complexes that are elevated in the circulation of IgAN patients. Gd-IgA1 is produced by IgA1-secreting cells due to abnormal expression of several glycosyltransferases in IgAN. Furthermore,some cytokines can enhance production of Gd-IgA1 by IgA1-secreting cells from IgAN patients but not those from healthy controls. We hypothesize that pro-inflammatory factors, such as those identified by GWAS or produced during episodes of synpharyngitic hematuria in IgAN patients, may further dysregulate IgA1-secreting cells and lead to enhanced Gd-IgA1 production.

Methods

As an experimental model, we used T-follicular helper (Tfh) cell-derived cytokines (IL-4, IL-6, IL-21, CD40L) to stimulate for 30 min immortalized Ig-producing cells derived from peripheral blood of IgAN patients and healthy controls. Then, single-cell transcriptomic analysis was performed. IgA1 splice variants were integrated into the hg38 reference genome to identify IgA1-secreting cells and the data analyzed using Seurat and Alteryx workflow. siRNA knock-down (k/d) was used to confirm involvement of candidate regulatory elements in cytokine-mediated overproduction of Gd-IgA1. Production of Gd-IgA1 was assessed after 72 h.

Results

Single-cell transcriptomics identified discrete populations of IgA1-secreting cells with differentialC1GALT1expression after Tfh-cytokine stimulation. Furthermore, these subpopulations exhibited reduced expression of cytokine-signaling regulatory elements, SOCS3,SOCS1, PTPN2, and PTPN11(p = 0.07, 0.04, 0.02, 0.07), indicating dysregulation of cytokine-signaling JAK/STAT pathways in IgAN-derived cells. Involvement of SOCS3 in Gd-IgA1 production was further supported by the observation that SOCS3siRNA k/d increased Gd-IgA1 production in healthy-control cells (p = 0.01).

Conclusion

Single-cell transcriptomics with stratification of IgA1-secreting cells based on C1GALT1expression and siRNA k/d experiments revealed that aberrant regulation of Tfh cytokine signaling was associated with enhanced Gd-IgA1 production in IgAN.

Funding

  • NIDDK Support