Kidney Week

Abstract: PO1740

Activation of the cGAS-STING Signaling Pathway Is Associated with Glomerular Diseases

Session Information

• Glomerular Diseases: Vasculitis and TMA
  October 22, 2020 | Location: On-Demand
  Abstract Time: 10:00 AM - 12:00 PM

Category: Glomerular Diseases

• 1202 Glomerular Diseases: Immunology and Inflammation

Authors

• Fontanella, Antonio Miguel, University of Miami School of Medicine, Miami, Florida, United States

Antonio Miguel Fontanella,

• Mallela, Shamroop Kumar, University of Miami School of Medicine, Miami, Florida, United States

Shamroop Kumar Mallela,

• Molina David, Judith T., University of Miami School of Medicine, Miami, Florida, United States

Judith T. Molina David,

• Kim, Jin Ju, University of Miami School of Medicine, Miami, Florida, United States

Jin Ju Kim,

• Burke, George William, University of Miami School of Medicine, Miami, Florida, United States

George William Burke,

• Merscher, Sandra M., University of Miami School of Medicine, Miami, Florida, United States

Sandra M. Merscher,

• Fornoni, Alessia, University of Miami School of Medicine, Miami, Florida, United States

Alessia Fornoni,

• Mitrofanova, Alla, University of Miami School of Medicine, Miami, Florida, United States

Alla Mitrofanova,

Group or Team Name

• Katz Family Division of Nephrology and Hypertension

Background

Podocytes express elements of the innate immune system which may be involved in the local immune response and contribute to chronic inflammation and glomerular damage. The cGAS-STING pathway is activated as part of the innate immune response to pathogens or host cytosolic DNA and has been shown to regulate inflammation and energy homeostasis under obesity conditions, kidney fibrosis and acute kidney injury. Whether cGAS-STING pathway contributes to development and progression of glomerular diseases remains largely unknown. This study aimed at filling this gap.

Methods

Immortalized human podocytes were cultured in RPMI medium and differentiated for 14 days. c-diAMP treatment (10 μM) was performed for 24h. Real-time PCR and Western blot analysis were used to evaluate mRNA and protein expression. Male and female, 8-week-old C57BL/6J mice were randomly divided into two groups: control (n=7) and I.P. injected with a single dose of c-diAMP, 25 mg/kg (n=9). The animals were sacrificed 72 h after injection, blood and kidneys were harvested and processed for in-depth phenotypical analysis, including urinary albumin-to-creatinine ratio, histological analysis, transmission electron microscopy analysis (foot process effacement quantification), immunohistochemistry, glomeruli isolation and serum analysis.

Results

In vitro, podocytes showed expression all of the cGAS-STING components at the mRNA and protein level under physiological conditions and treatment with c-diAMP, an antagonist of STING, lead to activation of the cGAS-STING pathway.
In vivo, treatment of mice with c-diAMP resulted in an increased expression of all components along the cGAS-STING pathway at both the mRNA and protein levels. Histology data show that c-diAMP-treated mice have a lower number of podocytes per glomerulus and a lower podocyte density, showing an increase in foot process effacement. This is further confirmed by increase in blood urine nitrogen and serum creatinine levels and in the urine albumin-to-creatinine ratio.

Conclusion

Genes of the cGAS-STING pathway are expressed in human podocytes and the pathway can be activated both in vitro and in vivo. Activation of the cGAS-STING pathway in mouse models in vivo is associated with increased podocyte injury and contributes to the glomerular diseases.

Funding

• NIDDK Support