Circulating RNA transcripts identify therapeutic response in cystic fibrosis lung disease.
BACKGROUND
Circulating leukocyte RNA transcripts are systemic markers of inflammation, which have not been studied in cystic fibrosis (CF) lung disease. Although the standard assessment of pulmonary treatment response is FEV(1), a measure of airflow limitation, the lack of systemic markers to reflect changes in lung inflammation critically limits the testing of proposed therapeutics.


OBJECTIVE
We sought to prospectively identify and validate peripheral blood leukocyte genes that could mark resolution of pulmonary infection and inflammation using a model by which RNA transcripts could increase the predictive value of spirometry.


METHODS
Peripheral blood mononuclear cells were isolated from 10 patients with CF and acute pulmonary exacerbations before and after therapy. RNA expression profiling revealed that 10 genes significantly changed with treatment when compared with matched non-CF and control subjects with stable CF to establish baseline transcript abundance. Peripheral blood mononuclear cell RNA transcripts were prospectively validated, using real-time polymerase chain reaction amplification, in an independent cohort of acutely ill patients with CF (n = 14). Patients who responded to therapy were analyzed using general estimating equations and multiple logistic regression, such that changes in FEV(1)% predicted were regressed with transcript changes.


RESULTS
Three genes, CD64, ADAM9, and CD36, were significant and independent predictors of a therapeutic response beyond that of FEV(1) alone (P < 0.05). In both cohorts, receiver operating characteristic analysis revealed greater accuracy when genes were combined with FEV(1).


CONCLUSIONS
Circulating mononuclear cell transcripts characterize a response to the treatment of pulmonary exacerbations. Even in small patient cohorts, changes in gene expression in conjunction with FEV(1) may enhance current outcomes measures for treatment response.
Saavedra
Milene T
MT
Division of Pulmonary Sciences and Critical Care Medicine, University of Colorado School of Medicine, Denver, Colorado 80262, USA. saavedram@njc.org
Hughes
Grant J
GJ
Sanders
Linda A
LA
Carr
Michelle
M
Rodman
David M
DM
Coldren
Christopher D
CD
Geraci
Mark W
MW
Sagel
Scott D
SD
Accurso
Frank J
FJ
West
James
J
Nick
Jerry A
JA
D000208:Acute Disease; D000328:Adult; D000900:Anti-Bacterial Agents / Q000627:therapeutic use*; D015415:Biomarkers / Q000097:blood; D015331:Cohort Studies; D003550:Cystic Fibrosis / Q000097:blood* / Q000188:drug therapy / Q000235:genetics; D016207:Cytokines / Q000097:blood; D005260:Female; D005541:Forced Expiratory Volume; D020869:Gene Expression Profiling / Q000379:methods; D006801:Humans; D007962:Leukocytes / Q000378:metabolism; D008297:Male; D020411:Oligonucleotide Array Sequence Analysis / Q000379:methods; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012322:RNA Precursors / Q000097:blood* / Q000235:genetics; D012372:ROC Curve; D015203:Reproducibility of Results; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D013147:Spirometry / Q000379:methods; D055815:Young Adult
D000900:Anti-Bacterial Agents; D015415:Biomarkers; D016207:Cytokines; D012322:RNA Precursors