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Abstract: FR-PO960

Assessment of Urinary Microparticles in Aristolochic Acid-Induced Nephropathy in Wild-Type and GPR40 Receptor Knockout Mice

Session Information

Category: Pathology and Lab Medicine

  • 1601 Pathology and Lab Medicine: Basic

Authors

  • Medeiros, Thalia, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada
  • Thibodeau, Jean-Francois, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada
  • Blais, Amélie, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada
  • Holterman, Chet E., Ottawa Hospital Research Institute, Ottawa, Ontario, Canada
  • Silva, Andréa A., Universidade Federal Fluminense, Niteroi, Rio de Janeiro, Brazil
  • Reis Almeida, Jorge, Universidade Federal Fluminense, Niteroi, Rio de Janeiro, Brazil
  • Tang, Vera A., University of Ottawa, Ottawa, Ontario, Canada
  • Langlois, Marc-Andre, University of Ottawa, Ottawa, Ontario, Canada
  • Kennedy, Chris R., Ottawa Hospital Research Institute, Ottawa, Ontario, Canada
  • Gagnon, Lyne, ProMetic BioSciences Inc., Laval, Quebec, Canada
  • Burger, Dylan, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada
Background

Urinary microparticles (MP) are novel non-invasive biomarkers of renal injury. However, the dynamics of MP release in AKI/CKD are not well understood. We questioned whether urine MPs are generated early in disease and how their levels change as disease progresses. Lastly, we determined whether urine MP levels are altered in mice with deletion of the protective, anti-fibrotic Gpr40 receptor.

Methods

8 week-old male [wild type (WT) or Gpr40-/-] mice were subjected to aristolochic acid nephropathy (AAN) via four consecutive daily injections (3.5mg/kg, ip). Renal function was assessed by plasma creatinine measured (HPLC) at days -4, 4, 11 and 28 days post-AAN. At endpoint, tubulointerstitial injury was assessed histologically. Total urine MPs were measured using nanoparticle tracking analysis (NTA) and nanoscale flow cytometry. Podocyte derived MPs (Annexin V+/Podoplanin+) were quantified by flow cytometry. Finally, mouse proximal tubule epithelial cells (PTECs) were treated with aristolochic acid (50 µM) and formation of MPs was quantified by NTA.

Results

AAN was associated with albuminuria, decline in renal function and anemia. NTA and flow cytometry revealed that both total and podocyte-derived MPs were increased at day 4 and progressively decreased until day 28. The drop in MP levels were associated with tubular interstitial fibrosis, tubular dilatation and inflammatory cell infiltration. At endpoint, plasma creatinine was significantly increased in Gpr40-/- vs. WT mice and this was associated with higher levels of total MPs (P<0.05 at day 4). Finally, PTECs treated with AA exhibited a ~3-fold increase in MP formation at 24h (P=0.01).

Conclusion

Taken together, our data suggest that the dynamics of MP release by glomerular and tubular cells changes according to the progression of kidney disease. Gpr40 deletion is associated with increased early MP levels and impaired function at endpoint. The increased early MP levels may be indicative of greater injury compared with WT leading to increased functional decline.

Funding

  • Government Support - Non-U.S.