The 9p21 locus does not affect risk of coronary artery disease through induction of type 1 interferons.
OBJECTIVE
The study objective was to determine whether the coronary artery disease (CAD)-associated genotype at chromosome 9p21 modulates basal or induced expression of type I interferons (IFN-I).


BACKGROUND
The mechanism responsible for the association between common variants in chromosome 9p21.3 and CAD remains unclear. It has been reported that the CAD risk locus is rich in enhancer-like elements and that chromosome looping can lead to its physical proximity with the IFN-I gene cluster, raising the possibility that the locus influences CAD risk by modulating expression of IFN-Is.


METHODS
We examined whether genotype at the lead CAD-associated single nucleotide polymorphism (rs1333049) in 9p21 was associated with: 1) basal levels of IFN-I in plasma from 148 healthy male subjects; 2) induction of IFN-I by Toll-like receptor stimulants in peripheral blood mononuclear cells of 60 healthy volunteers assessed by enzyme-linked immunosorbent assay, quantitative polymerase chain reaction, Western blot, and IFN-I bioassay; and 3) enhancer activity of predicted IFN regulatory factor 3/7 binding sites within the 9p21 CAD risk region in reporter assays.


RESULTS
No significant effects of 9p21 genotype were observed for plasma levels of IFN-α, IFN-α21, or CXCL10, or leukocyte induction of IFN-α, IFN-α21, IFN-β, CXCL10, or total IFN-I measured at the mRNA, protein, and biological activity levels. There was also no enhancement of reporter activity by predicted IFN regulatory factor 3/7 binding sites in the CAD risk locus of either genotype.


CONCLUSIONS
The mechanism underlying the association between common 9p21 variants and CAD does not involve differential regulation of IFN-I responses.
Department of Cardiovascular Sciences, University of Leicester, British Heart Foundation Cardiovascular Research Centre, Glenfield Hospital, Leicester, United Kingdom; National Institute for Health Research Leicester Cardiovascular Biomedical Research Unit, Glenfield Hospital, Leicester, United Kingdom. Electronic address: ce55@le.ac.uk.
Clett
C
Erridge
Jay
J
Gracey
Peter S
PS
Braund
Nilesh J
NJ
Samani
D000328:Adult; D001665:Binding Sites; D015153:Blotting, Western; D054357:Chemokine CXCL10 / Q000097:blood; D002899:Chromosomes, Human, Pair 9 / Q000235:genetics*; D003324:Coronary Artery Disease / Q000235:genetics*; D004797:Enzyme-Linked Immunosorbent Assay; D005838:Genotype; D006801:Humans; D050838:Interferon Regulatory Factor-3 / Q000235:genetics / Q000378:metabolism; D050839:Interferon Regulatory Factor-7 / Q000235:genetics / Q000378:metabolism; D007370:Interferon Type I / Q000097:blood* / Q000235:genetics; D007963:Leukocytes, Mononuclear / Q000378:metabolism; D008297:Male; D016133:Polymerase Chain Reaction; D020641:Polymorphism, Single Nucleotide; D011485:Protein Binding; D012333:RNA, Messenger / Q000378:metabolism; D055815:Young Adult
C114753:CXCL10 protein, human; D054357:Chemokine CXCL10; D050838:Interferon Regulatory Factor-3; D050839:Interferon Regulatory Factor-7; D007370:Interferon Type I; D012333:RNA, Messenger
9p21; CAD; ELISA; IFN; IFN-I; IRF; LD; ODN; PBMC; SLE; SNP; TLR; Toll-like receptor; coronary artery disease; enzyme-linked immunosorbent assay; interferon; interferon regulatory factor; linkage disequilibrium; oligodeoxynucleotide; peripheral blood mononuclear cell; single nucleotide polymorphism; systemic lupus erythematosus; type I interferon