Detection of cardiac allograft rejection and response to immunosuppressive therapy with peripheral blood gene expression.
BACKGROUND
Assessment of gene expression in peripheral blood may provide a noninvasive screening test for allograft rejection. We hypothesized that changes in peripheral blood expression profiles would correlate with biopsy-proven rejection and would resolve after treatment of rejection episodes.


RESULTS
We performed a case-control study nested within a cohort of 189 cardiac transplant patients who had blood samples obtained during endomyocardial biopsy (EMB). Using Affymetrix HU133A microarrays, we analyzed whole-blood expression profiles from 3 groups: (1) control samples with negative EMB (n=7); (2) samples obtained during rejection (at least International Society for Heart and Lung Transplantation grade 3A; n=7); and (3) samples obtained after rejection, after treatment and normalization of the EMB (n=7). We identified 91 transcripts differentially expressed in rejection compared with control (false discovery rate <0.10). In postrejection samples, 98% of transcripts returned toward control levels, displaying an intermediate expression profile for patients with treated rejection (P<0.0001). Cluster analysis of the 40 transcripts with >25% change in expression levels during rejection demonstrated good discrimination between control and rejection samples and verified the intermediate expression profile of postrejection samples. Quantitative real-time polymerase chain reaction confirmed significant differential expression for the predictive markers CFLAR and SOD2 (UniGene ID No. 355724 and No. 384944).


CONCLUSIONS
These data demonstrate that peripheral blood expression profiles correlate with biopsy-proven allograft rejection. Intermediate expression profiles of treated rejection suggest persistent immune activation despite normalization of the EMB. If validated in larger studies, expression profiling may prove to be a more sensitive screening test for allograft rejection than EMB.
Horwitz
Phillip A
PA
Department of Internal Medicine, Division of Cardiovascular Diseases, University of Iowa-Roy J. and Lucille A. Carver College of Medicine, Iowa City, Iowa, USA.
Tsai
Emily J
EJ
Putt
Mary E
ME
Gilmore
Joan M
JM
Lepore
John J
JJ
Parmacek
Michael S
MS
Kao
Andrew C
AC
Desai
Shashank S
SS
Goldberg
Lee R
LR
Brozena
Susan C
SC
Jessup
Mariell L
ML
Epstein
Jonathan A
JA
Cappola
Thomas P
TP
D000328:Adult; D000368:Aged; D015415:Biomarkers; D001706:Biopsy; D016022:Case-Control Studies; D016000:Cluster Analysis; D015331:Cohort Studies; D004699:Endocardium / Q000473:pathology; D020869:Gene Expression Profiling; D006084:Graft Rejection / Q000097:blood* / Q000175:diagnosis / Q000188:drug therapy / Q000235:genetics / Q000473:pathology; D016027:Heart Transplantation / Q000009:adverse effects* / Q000276:immunology; D006801:Humans; D007166:Immunosuppressive Agents / Q000627:therapeutic use*; D008875:Middle Aged; D020411:Oligonucleotide Array Sequence Analysis; D011446:Prospective Studies; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014184:Transplantation, Homologous / Q000009:adverse effects* / Q000276:immunology
D015415:Biomarkers; D007166:Immunosuppressive Agents