Gene expression profiling reveals a downregulation in immune-associated genes in patients with AS.
OBJECTIVE
To identify differentially expressed genes in peripheral blood mononuclear cells (PBMCs) from patients with ankylosing spondylitis (AS) compared with healthy individuals.


METHODS
RNA was extracted from PBMCs collected from 18 patients with active disease and 18 gender-matched and age-matched controls. Expression profiles of these cells were determined using microarray. Candidate genes with differential expressions were confirmed in the same samples using quantitative reverse transcription-PCR (qRT-PCR). These genes were then validated in a different sample cohort of 35 patients with AS and 18 controls by qRT-PCR.


RESULTS
Microarray analysis identified 452 genes detected with 485 probes which were differentially expressed between patients with AS and controls. Underexpression of NR4A2, tumour necrosis factor AIP3 (TNFAIP3) and CD69 was confirmed. These genes were further validated in a different sample group in which the patients with AS had a wider range of disease activity. Predictive algorithms were also developed from the expression data using receiver-operating characteristic curves, which demonstrated that the three candidate genes have approximately 80% power to predict AS according to their expression levels.


CONCLUSIONS
The findings show differences in global gene expression patterns between patients with AS and controls, suggesting an immunosuppressive phenotype in the patients. Furthermore, downregulated expression of three immune-related genes was confirmed. These candidate genes were also shown to be strong predictive markers for AS.
Duan
Ran
R
Diamantina Institute for Cancer, Immunology & Metabolic Medicine, Princess Alexandra Hospital, Ipswich Road, Woolloongabba, QLD 4102, Australia.
Leo
Paul
P
Bradbury
Linda
L
Brown
Matthew A
MA
Thomas
Gethin
G
D000293:Adolescent; D000328:Adult; D000368:Aged; D001798:Blood Proteins / Q000096:biosynthesis / Q000235:genetics; D016022:Case-Control Studies; D016000:Cluster Analysis; D015536:Down-Regulation; D005260:Female; D020869:Gene Expression Profiling / Q000379:methods; D006801:Humans; D007963:Leukocytes, Mononuclear / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D020411:Oligonucleotide Array Sequence Analysis / Q000379:methods; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D013167:Spondylitis, Ankylosing / Q000235:genetics* / Q000276:immunology
D001798:Blood Proteins