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Kidney Week

Abstract: SA-PO1013

Novel Allosteric Agonists of Integrin a3b1 as Therapeutics for FSGS

Session Information

Category: Glomerular Diseases

  • 1403 Podocyte Biology

Authors

  • Helmuth, Richard, Rush University Medical Center, Chicago, Illinois, United States
  • Balza Pineda, Santiago, 149 Bio, LLC, Miami, Florida, United States
  • Lopez-Rodriguez, Darlah M., 149 Bio, LLC, Miami, Florida, United States
  • Alzahrani, Khulood, Rush University Medical Center, Chicago, Illinois, United States
  • Gupta, Vineet, Rush University Medical Center, Chicago, Illinois, United States
Background

Podocytes form the kidney filter that allows separation of urine and waste from blood. They attach to the extracellular basement membranes via cell surface integrin a3b1. Reduced podocyte adhesion, due to injury or mutations in a3b1, associated membrane proteins (CD151), or the integrin linked cytoskeleton, results in podocyte detachment and loss that weakens the kidney filter, resulting in progressive glomerular disease. Reinforcement of podocyte adhesion, via increased integrin-mediated cell adhesion and strengthened cytoskeleton is protective in various kidney diseases.

Methods

We used a human phage display library to identify a3b1 activating antibodies. K562 cells stably expressing a3b1, differentiated podocytes, and human SKOV cells were used in in vitro assays. K562 cells were used in flow-cytometry assays to characterize a3 agonists. Podocytes were used in High-Content Screening (HCS) based assays to quantify puromycin aminonucleoside (PAN) induced cell damage and integrin agonist mediated protection. Cells were also utilized in cell adhesion and cell migration based functional assays.

Results

Measurement of F-actin fibers, focal adhesions and active integrin levels in podocytes showed a quantifiable change due to PAN injury in podocytes, and protection from PAN-injury by b1 integrin agonists 9EG7 and pyrintegrin as well as by the novel antibodies. a3b1 agonists also showed increased cell adhesion and reduced cell migration in vitro. Mapping of the antibodies using various integrin chimeras showed that they selectively bound to the a3 head-domain, away from the ligand binding pocket.

Conclusion

We previously reported that activation of podocyte-expressed integrin a3b1 increases podocyte adhesion to matrix proteins and protects cells from damage. Here, we show that novel, integrin a3b1-directed allosteric agonist antibodies can be used to reinforce podocyte adhesion to the basement membrane. Data from our currently ongoing in vivo efficacy studies will provide further evidence of the therapeutic efficacy of this approach as a novel therapeutic strategy against a variety of glomerular diseases.

Funding

  • NIDDK Support – 149 Bio, LLC