Three non-invasive protein biomarkers for solid-organ transplant rejection found through integrative genomics

We integrated three transplant rejection microarray studies examining gene expression in samples from pediatric renal, adult renal, and adult heart transplants. We performed one study ourselves and retrieved two others from the NCBI Gene Expression Omnibus (GEO)(GSE4470 and GSE1563). We identified 45 genes that were upregulated in common in acute rejection. Half were involved in one immune-related pathway. Among ten proteins we tested by serum ELISA, three successfully distinguished acute rejection from stable transplants. These were CXCL9, PECAM1, and CD44, with areas under the receiver operating characteristic curves of 0.844, 0.802, and 0.738, respectively. Immunohistochemistry showed that the PECAM1 protein was increased in acute rejection in renal, liver and heart transplants versus normal tissues. Our results show that integrating publicly-available gene expression data sets is a fast, powerful, and cost-effective way to identify serum-detectable diagnostic biomarkers.

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Ling XB, Sigdel TK, Lau K, Ying L, Lau I, Schilling J, Sarwal MM