Kidney Week

Abstract: FR-PO760

Diabetes and SGLT2 Inhibitor Treatment Alter Podocyte Glycocalyx

Session Information

• Glomerular Diseases: Mechanisms and Podocyte Biology
  October 25, 2024 | Location: Exhibit Hall, Convention Center
  Abstract Time: 10:00 AM - 12:00 PM

Category: Glomerular Diseases

• 1401 Glomerular Diseases: Mechanisms, including Podocyte Biology

Authors

• Becerra Calderon, Alejandra, University of Southern California, Los Angeles, California, United States

Alejandra Becerra Calderon

• Alkoraishi, Hasen, University of Southern California, Los Angeles, California, United States

Hasen Alkoraishi

• Izuhara, Audrey, University of Southern California, Los Angeles, California, United States

Audrey Izuhara

• Deepak, Sachin K., University of Southern California, Los Angeles, California, United States

Sachin K. Deepak

• Trogen, Greta H., University of Southern California, Los Angeles, California, United States

Greta H. Trogen

• Peti-Peterdi, Janos, University of Southern California, Los Angeles, California, United States

Janos Peti-Peterdi, MD, PhD

• Gyarmati, Georgina, University of Southern California, Los Angeles, California, United States

Georgina Gyarmati, MD, MPH

Background

The glycocalyx between the podocyte foot processes and the glomerular basement membrane (GBM) has been difficult to study in vivo, therefore its function remains elusive. Recently we developed and initially characterized the Pod-Sdc1-GFP mouse model with podocyte specific genetic labeling to study the physiological role of podocyte glycocalyx. Here we aimed to visually demonstrate the alterations in podocyte glycocalyx in diabetes with and without SGLT2i treatment in vivo.

Methods

New genetic mouse models were generated by the knock-in of pCAG-Lox-STOP-Lox-EGFP-Sdc1 to generate animals with Cre-dependent expression of a syndecan-1 (Sdc1) fusion protein with N-terminal, extracellular GFP. Sdc1-GFP^flox animals were crossed with Podocin-Cre mice for the specific genetic labeling of the glycocalyx in podocytes. Intravital multiphoton microscopy (MPM) was used to measure changes in the depth of glycocalyx and corresponding changes in GFB function in vivo over time in streptozotocin induced diabetic kidney disease with or without SGLT2i empagliflozin treatment. Alexa-594 conjugated wheat germ agglutinin (WGA) lectin was used to label the glycosaminoglycan (GAG) component of the glycocalyx, and Alexa-680 conjugated albumin was used to visualize GFB permeability.

Results

Co-localization of genetic GFP and Alexa-594 WGA confirmed podocyte glycocalyx labeling. MMP9 injection significantly reduced podocyte glycocalyx thickness and resulted in glomerular albumin leakage confirming podocyte glycocalyx functionality. In vivo MPM imaging in diabetic mice revealed a significant decrease in glycocalyx thickness on both the apical and the basal surface (0.76+/-0.01 um) compared to control (1.03+/-0.02 um) and increased GFB permeability. SGLT2i treatment restored podocyte glycocalyx thickness (0.9+/-0.01 um) and reduced albumin leakage in diabetic mice but not in healthy control animals ( 1.01+/-0.01 um).

Conclusion

In conclusion, the specialized podocyte glycocalyx at the GBM may function as an important new layer of the GFB, may play an important role in the disruption of GFB functions in diabetic kidney disease, and may be involved in the pleiotropic renoprotective effects of SGLT2i treatment.

Funding

• NIDDK Support