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Abstract: FR-OR33

New Insights on the Role of C3a/C3aR1 Signaling in Membranous Nephropathy

Session Information

Category: Glomerular Diseases

  • 1202 Glomerular Diseases: Immunology and Inflammation

Authors

  • Da Sacco, Stefano, Children's Hospital of Los Angeles, Los Angeles, California, United States
  • Zhang, Qi, Children's Hospital of Los Angeles, Los Angeles, California, United States
  • Budge, Kelly L., Icahn School of Medicine at Mount Sinai, New York, New York, United States
  • Petrosyan, Astgik, Children's Hospital of Los Angeles, Los Angeles, California, United States
  • Villani, Valentina, Children's Hospital of Los Angeles, Los Angeles, California, United States
  • De Filippo, Roger E., Children's Hospital of Los Angeles, Los Angeles, California, United States
  • Perin, Laura, Children's Hospital of Los Angeles, Los Angeles, California, United States
  • Cravedi, Paolo, Icahn School of Medicine at Mount Sinai, New York, New York, United States
Background

Primary membranous nephropathy (MN) is a leading cause of nephrotic syndrome in adults worldwide. MN is characterized by the deposition of anti-podocyte-antibodies within the glomerular subepithelial space. While complement deposition and formation of membrane-attack-complex (MAC) are thought to play a crucial pathogenic role, the exact mechanism of injury in MN is still unclear. We have developed a novel glomerulus-on-a-chip system (GOAC) using human primary podocytes and glomerular endothelial cells (GEC) to study MN and assessed functional response to human MN serum, role of MAC formation and C3a/C3aR1 signaling in MN pathogenesis in addition to in vivo studies.

Methods

GOACs were cultured with serum containing either anti-PLA2R+ or THSD7A+ MN patients and from healthy individuals ( as control). Functional response was assessed by albumin permeability assay. The mechanistic role of MAC and C3a/C3aR1 signaling pathway was assessed by immunofluorescence, functional analysis, PCR arrays and Western Blotting. Results were further confirmed in GOAC using podocytesC3aR1-/- and in vivo using THSD7A induced MN in balb/c mice.

Results

Following exposure to sera from MN patients, we have confirmed deposition of human lgG on podocytes and formation of MAC complex, accompanied by albumin leakage. MAC inhibition did not prevent albumin leakage while GOAC supplemented with C3aR1 antagonists as well as GOAC using podocytesC3aR1-/- were able to prevent glomerular filtration damage and albumin leakage. Efficacy of C3aR1 antagonists in preventing proteinuria was confirmed in mice injected with serum from patients with anti-thrombospondin Ab, substantiating our findings.

Conclusion

Using our microfluidic GOAC system in combination with in vivo animal models, we have found evidence that C3a/C3aR1 plays a dominant role in complement-mediated MN pathogenesis. Our results not only shed some light on the injury mechanisms in complement-mediated damage but could provide new avenues for the development of glomerulus-specific treatments.

Funding

  • NIDDK Support