Rapid Biolayer Interferometry Measurements of Urinary CXCL9 to Detect Cellular Infiltrates Noninvasively After Kidney Transplantation

Ilaria Gandolfini, Cynthia Harris, Michael Abecassis, Lisa Anderson, Oriol Bestard, Giorgia Comai, Paolo Cravedi, Elena Cremaschi, J. Andrew Duty, Sander Florman, John Friedewald, Gaetano La Manna, Umberto Maggiore, Thomas Moran, Giovanni Piotti, Carolina Purroy, Marta Jarque, Vinay Nair, Ron Shapiro, Jessica Reid-AdamPeter S. Heeger*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

8 Scopus citations

Abstract

Introduction Measuring the chemokine CXCL9 in urine by enzyme-linked immunosorbent assay (ELISA) can diagnose acute cellular rejection (ACR) noninvasively after kidney transplantation, but the required 12- to 24-hour turnaround time is not ideal for rapid, clinical decision-making. Methods We developed a biolayer interferometry (BLI)−based assay to rapidly measure urinary CXCL9 in <1 hour. We validated this new assay versus standard ELISA in 86 urine samples from kidney transplantation recipients with various diagnoses. We then used BLI to analyze samples from 56 kidney transplantation recipients, including 46 subjects who experienced an acute rise in serum creatinine associated with biopsy-proven ACR (n = 22), subclinical rejection (n = 15), or no infiltrates (n = 9), and 10 stable kidney transplantation recipients with surveillance biopsies. To assess its usefulness in detecting adequacy of therapy we serially measured serum creatinine and urinary CXCL9 in 6 subjects after treatment for ACR, and correlated the results with histological diagnoses on follow-up biopsies. Results BLI accurately and reproducibly detected urinary CXCL9 in <1 hour. BLI-based results showed that urinary CXCL9 was >200 pg/ml in subjects with ACR and ≤100 pg/ml in subjects with stable kidney function without cellular infiltrates. In samples obtained after treatment for ACR, BLI CXCL9 measurements detected biopsy-proven intragraft infiltrates despite treatment-induced reduction in serum creatinine. Discussion Together, our proof-of-principle results demonstrate that BLI-based urinary CXCL9 detection has potential as a point-of-care noninvasive biomarker to diagnose and guide therapy for ACR in kidney transplantation recipients.

Original languageEnglish (US)
Pages (from-to)1186-1193
Number of pages8
JournalKidney International Reports
Volume2
Issue number6
DOIs
StatePublished - 2017

Keywords

  • CXCL9
  • acute rejection
  • biomarker
  • chemokines
  • kidney transplantation

ASJC Scopus subject areas

  • Ophthalmology
  • Nephrology

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