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Abstract: PO0831

Serum Induces Major Transcriptional and Epigenetic Changes at COVID-19-Associated Gene Loci in Primary Renal Epithelial Cells

Session Information

Category: Coronavirus (COVID-19)

  • 000 Coronavirus (COVID-19)

Authors

  • Lidberg, Kevin, University of Washington, Seattle, Washington, United States
  • Muthusamy, Selvaraj, University of Washington, Seattle, Washington, United States
  • Adil, Mohamed, University of Washington, Seattle, Washington, United States
  • Reichel, Jonathan, University of Washington, Seattle, Washington, United States
  • Himmelfarb, Jonathan, University of Washington, Seattle, Washington, United States
  • Kelly, Edward J., University of Washington, Seattle, Washington, United States
  • Akilesh, Shreeram, University of Washington, Seattle, Washington, United States
Background

Tubular epithelial cells express high levels of COVID-19 entry receptors ACE2 and the accessory protease TMPRSS2. High systemic levels of IL-6 and IL-8 may contribute to the “cytokine storm” associated with poor outcome with COVID-19 infection. We sought to understand the regulation of these key genes in a 3D microphysiological system (MPS) containing primary human tubular epithelial cells treated with human serum, a surrogate for a disease-state ultrafiltrate.

Methods

Primary human tubular epithelial cells cultured in the 3D MPS were exposed to 0.5 and 2% serum for 48 hours and their transcriptional responses were evaluated by RNA-seq. Observed changes in transcription of secreted proteins were validated by ELISA on MPS effluents. We also orthogonally validated our MPS findings against gene expression and chromatin accessibility (ATAC-seq) data generated from intact human renal cortex and primary tubular epithelial cells cultured in 2D in the presence of 10% serum.

Results

Serum exposure of tubular MPS elicited 535 up and 285 downregulated genes with upregulation of pro-inflammatory and chemotactic cytokines IL6 and IL8 consistently seen across multiple donors. This was associated with increased IL6 and HAVCR1 (KIM-1) protein secretion in MPS effluents. Tubular epithelial cells cultured in 2D with 10% serum expressed higher levels of HAVCR1 (up 4.5x), LCN2 (NGAL, up 6x), IL6 (up 11.2x) and CXCL8 (IL8, up 7.6x) compared to renal cortex. In contrast, ACE2 (down 8.6x) and TMPRSS2 (down 4.4x) were significantly downregulated. Analysis of open chromatin regions revealed a stress response signature at these gene loci, indicating active regulation in response to injury.

Conclusion

Proteinuria is common in COVID-19 infected patients and we studied serum-exposure, as a model of glomerular dysfunction and subsequent proximal tubule responses in our kidney MPS. Serum induces the expression and secretion of IL6 and IL8, suggesting a localized, pro-inflammatory tubule response. Our epigenetic analysis revealed that COVID-19 associated genes have a stress response signature with implications for inter-individual variability in expression. Our kidney MPS model and data represent a powerful system for studying the complex effects that COVID-19 infection exerts on the kidney.

Funding

  • Other NIH Support