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Abstract: TH-PO954

RNA Seq Interrogation of a Clinical Kidney Biopsy Biobank Identifies Axl Kinase as an Anti-Fibrotic Target

Session Information

Category: Pathology and Lab Medicine

  • 1501 Pathology and Lab Medicine: Basic

Authors

  • Tolosa, Monica F., St. Michael's Hospital, Toronto, Ontario, Canada
  • Caldwell, Lauren V., Lunenfeld Tanenbaum Research Institute, Ajax, Ontario, Canada
  • Zhang, Yanling, St. Michael's Hospital, Toronto, Ontario, Canada
  • Thai, Kerri, St. Michael's Hospital, Toronto, Ontario, Canada
  • Kirpalani, Anish, St. Michael's Hospital, Toronto, Ontario, Canada
  • Krizova, Adriana, St. Michael's Hospital, Toronto, Ontario, Canada
  • Gilbert, Richard E., St. Michael's Hospital, Toronto, Ontario, Canada
  • Yuen, Darren A., St. Michael's Hospital, Toronto, Ontario, Canada
Background

Fibrosis is a key manifestation and driver of chronic kidney injury. No safe and effective renal anti-fibrotic agents exist, in part because of the lack of human kidney tissue for study. Well annotated human kidney tissue biobanks are rare given their maintenance costs and the resources required to collect follow-up data. The few biobanks that exist have been primarily interrogated using microarrays, which while enabling multi-gene assessment, is limited to the probes on the array, and usually requires an extra, specially stored biopsy core. Here we describe the interrogation of archived remnants of clinical kidney biopsy tissue using a comprehensive RNA seq-based platform, enabling the study of clinical samples and linking to routinely obtained follow-up data.

Methods

RNA extracted from remnants of 14 frozen clinically indicated kidney transplant biopsies at St. Michael’s Hospital (SMH) was subjected to RNA sequencing. Clinical data (age, gender, Banff histologic scores, eGFR values) was collected from the SMH Kidney Transplant Database. Preliminary findings were confirmed in the murine unilateral ureteral obstruction (UUO) model of kidney fibrosis.

Results

The mean slope of eGFR change post-biopsy was -4.8 +/- 8.6 mL/min/yr. 7 biopsies were scored as ci 1 (5 – 25% fibrosis), 6 biopsies as ci 2 (25 – 50% fibrosis), and 1 biopsy as ci 3 (> 50% fibrosis). In addition to known fibrosis-associated transcripts (collagens, TGF-beta, CTGF), we found that mRNA levels of the tyrosine kinase Axl were positively associated with fibrosis score (rho = 0.48, p = 0.03) and negatively with slope of eGFR change post-biopsy (rho = -0.52, p = 0.02). We found a similar increase in Axl mRNA levels in fibrotic UUO kidneys. As Axl mRNA expression was localized primarily to fibroblasts, we next treated NRK49F fibroblasts with an Axl inhibitor (BGB324), finding that Axl inhibition blocked TGF-beta-induced collagen production.

Conclusion

We describe a novel RNA seq-based platform that can interrogate routinely stored remnants of clinically obtained kidney biopsy tissue, enabling the use of archived clinical samples and their associated follow-up data. Our initial studies identified known fibrosis-associated transcripts, and also potential druggable targets that may lead to new anti-fibrotic strategies.

Funding

  • Private Foundation Support