Shotgun proteomics identifies proteins specific for acute renal transplant rejection.
OBJECTIVE
Acute rejection (AR) remains the primary risk factor for renal transplant outcome; development of non-invasive diagnostic biomarkers for AR is an unmet need.


METHODS
We used shotgun proteomics applying LC-MS/MS and ELISA to analyze a set of 92 urine samples, from patients with AR, stable grafts (STA), proteinuria (NS), and healthy controls.


RESULTS
A total of 1446 urinary proteins (UP) were identified along with a number of nonspecific proteinuria-specific, renal transplantation specific and AR-specific proteins. Relative abundance of identified UP was measured by protein-level spectral counts adopting a weighted fold-change statistic, assigning increased weight for more frequently observed proteins. We have identified alterations in a number of specific UP in AR, primarily relating to MHC antigens, the complement cascade and extra-cellular matrix proteins. A subset of proteins (uromodulin, SERPINF1 and CD44), have been further cross-validated by ELISA in an independent set of urine samples, for significant differences in the abundance of these UP in AR.


CONCLUSIONS
This label-free, semi-quantitative approach for sampling the urinary proteome in normal and disease states provides a robust and sensitive method for detection of UP for serial, non-invasive clinical monitoring for graft rejection after kidney transplantation.
Sigdel
Tara K
TK
Department of Pediatrics, Stanford University School of Medicine, CA 94304, USA.
Kaushal
Amit
A
Gritsenko
Marina
M
Norbeck
Angela D
AD
Qian
Wei-Jun
WJ
Xiao
Wenzhong
W
Camp
David G
DG
Smith
Richard D
RD
Sarwal
Minnie M
MM
D000208:Acute Disease; D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D030562:Databases, Protein; D004797:Enzyme-Linked Immunosorbent Assay; D005786:Gene Expression Regulation; D006084:Graft Rejection / Q000175:diagnosis* / Q000652:urine*; D006801:Humans; D016030:Kidney Transplantation / Q000009:adverse effects*; D013058:Mass Spectrometry; D040901:Proteomics / Q000191:economics / Q000379:methods*; D012680:Sensitivity and Specificity; D013997:Time Factors; D014556:Urine / Q000737:chemistry; D055815:Young Adult