Differentially Expressed RNA from Public Microarray Data Identifies Serum Protein Biomarkers for Cross-Organ Transplant Rejection and Other Conditions
Figure 2
Identification of cross-organ AR protein biomarkers through integration of gene expression data.
We integrated three microarray studies examining gene expression after rejection in the biopsy samples from pediatric renal, adult renal, and adult heart transplants (the latter two were retrieved from GEO). We identified 45 genes that were upregulated in common in acute rejection compared to stable graft function. Among ten proteins we tested by ELISA, the concentrations of three were higher in serum samples from AR patients. The concentrations of the same three proteins were also higher in AR samples from cardiac transplantation. Immunohistochemistry showed that PECAM1 was increased in AR vs. stable biopsies in renal, hepatic and cardiac transplantation. All three biomarkers were from our identified AR pathway, and two of them showed detectable protein abundance in the biofluid proteome database we constructed before. CXCL9 was not listed in our biofluid proteome database, but is known to have detectable protein abundance [24].