title: The identification of novel potential injury mechanisms and candidate biomarkers in renal allograft rejection by quantitative proteomics.
abstract: Early transplant dysfunction and failure because of immunological and nonimmunological factors still presents a significant clinical problem for transplant recipients. A critical unmet need is the noninvasive detection and prediction of immune injury such that acute injury can be reversed by proactive immunosuppression titration. In this study, we used iTRAQ -based proteomic discovery and targeted ELISA validation to discover and validate candidate urine protein biomarkers from 262 renal allograft recipients with biopsy-confirmed allograft injury. Urine samples were randomly split into a training set of 108 patients and an independent validation set of 154 patients, which comprised the clinical biopsy-confirmed phenotypes of acute rejection (AR) (n = 74), stable graft (STA) (n = 74), chronic allograft injury (CAI) (n = 58), BK virus nephritis (BKVN) (n = 38), nephrotic syndrome (NS) (n = 8), and healthy, normal control (HC) (n = 10). A total of 389 proteins were measured that displayed differential abundances across urine specimens of the injury types (p < 0.05) with a significant finding that SUMO2 (small ubiquitin-related modifier 2) was identified as a "hub" protein for graft injury irrespective of causation. Sixty-nine urine proteins had differences in abundance (p < 0.01) in AR compared with stable graft, of which 12 proteins were up-regulated in AR with a mean fold increase of 2.8. Nine urine proteins were highly specific for AR because of their significant differences (p < 0.01; fold increase >1.5) from all other transplant categories (HLA class II protein HLA-DRB1, KRT14, HIST1H4B, FGG, ACTB, FGB, FGA, KRT7, DPP4). Increased levels of three of these proteins, fibrinogen beta (FGB; p = 0.04), fibrinogen gamma (FGG; p = 0.03), and HLA DRB1 (p = 0.003) were validated by ELISA in AR using an independent sample set. The fibrinogen proteins further segregated AR from BK virus nephritis (FGB p = 0.03, FGG p = 0.02), a finding that supports the utility of monitoring these urinary proteins for the specific and sensitive noninvasive diagnosis of acute renal allograft rejection.
authors: California Pacific Medical Center Research Institute, 475 Brannan St., Ste 220, San Francisco, California 9410;
authors: Tara K
authors: TK
authors: Sigdel
authors: Nathan
authors: N
authors: Salomonis
authors: Carrie D
authors: CD
authors: Nicora
authors: Soyoung
authors: S
authors: Ryu
authors: Jintang
authors: J
authors: He
authors: Van
authors: V
authors: Dinh
authors: Daniel J
authors: DJ
authors: Orton
authors: Ronald J
authors: RJ
authors: Moore
authors: Szu-Chuan
authors: SC
authors: Hsieh
authors: Hong
authors: H
authors: Dai
authors: Minh
authors: M
authors: Thien-Vu
authors: Wenzhong
authors: W
authors: Xiao
authors: Richard D
authors: RD
authors: Smith
authors: Wei-Jun
authors: WJ
authors: Qian
authors: David G
authors: DG
authors: Camp
authors: Minnie M
authors: MM
authors: Sarwal
mesh_terms: D058186:Acute Kidney Injury / Q000378:metabolism / Q000652:urine*; D000293:Adolescent; D000328:Adult; D015415:Biomarkers / Q000378:metabolism / Q000652:urine*; D002648:Child; D005260:Female; D006084:Graft Rejection / Q000378:metabolism / Q000652:urine*; D006087:Graft vs Host Reaction; D006801:Humans; D016030:Kidney Transplantation / Q000009:adverse effects*; D008297:Male; D060066:Protein Interaction Maps; D040901:Proteomics / Q000379:methods*; D015398:Signal Transduction; D014184:Transplantation, Homologous; D016482:Urinalysis / Q000379:methods; D054928:Validation Studies as Topic; D055815:Young Adult
chemical_list: D015415:Biomarkers