Discovery and Validation of a Urinary Exosome mRNA Signature for the Diagnosis of Human Kidney Transplant Rejection |
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Authors: | Rania El Fekih James Hurley Vasisht Tadigotla Areej Alghamdi Anand Srivastava Christine Coticchia John Choi Hazim Allos Karim Yatim Juliano Alhaddad Siawosh Eskandari Philip Chu Albana B Mihali Isadora T Lape Mauricio P Lima Filho Bruno T Aoyama Anil Chandraker Kassem Safa James F Markmann Leonardo V Riella Richard N Formica Johan Skog Jamil R Azzi |
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Institution: | 1.Renal Division, Transplantation Research Center, Brigham and Women’s Hospital and Children’s Hospital, Harvard Medical School, Boston, Massachusetts;2.Exosome Diagnostics, a Bio-Techne brand, Waltham, Massachusetts;3.Transplant Center, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts;4.Section of Nephrology, Yale School of Medicine, New Haven, Connecticut |
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Abstract: | BackgroundDeveloping a noninvasive clinical test to accurately diagnose kidney allograft rejection is critical to improve allograft outcomes. Urinary exosomes, tiny vesicles released into the urine that carry parent cells’ proteins and nucleic acids, reflect the biologic function of the parent cells within the kidney, including immune cells. Their stability in urine makes them a potentially powerful tool for liquid biopsy and a noninvasive diagnostic biomarker for kidney-transplant rejection.MethodsUsing 192 of 220 urine samples with matched biopsy samples from 175 patients who underwent a clinically indicated kidney-transplant biopsy, we isolated urinary exosomal mRNAs and developed rejection signatures on the basis of differential gene expression. We used crossvalidation to assess the performance of the signatures on multiple data subsets.ResultsAn exosomal mRNA signature discriminated between biopsy samples from patients with all-cause rejection and those with no rejection, yielding an area under the curve (AUC) of 0.93 (95% CI, 0.87 to 0.98), which is significantly better than the current standard of care (increase in eGFR AUC of 0.57; 95% CI, 0.49 to 0.65). The exosome-based signature’s negative predictive value was 93.3% and its positive predictive value was 86.2%. Using the same approach, we identified an additional gene signature that discriminated patients with T cell–mediated rejection from those with antibody-mediated rejection (with an AUC of 0.87; 95% CI, 0.76 to 0.97). This signature’s negative predictive value was 90.6% and its positive predictive value was 77.8%.ConclusionsOur findings show that mRNA signatures derived from urinary exosomes represent a powerful and noninvasive tool to screen for kidney allograft rejection. This finding has the potential to assist clinicians in therapeutic decision making. |
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Keywords: | kidney transplantation urine exosome mRNA biomarker rejection |
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