A common variant of the interleukin 6 receptor (IL-6r) gene increases IL-6r and IL-6 levels, without other inflammatory effects.
Interleukin-6 (IL-6) is a key inflammatory cytokine, signalling to most tissues by binding to a soluble IL-6 receptor (sIL-6r), making a complex with gp130. We used 1273 subjects (mean age 68 years) from the InCHIANTI Italian cohort to study common variation in the IL-6r locus and associations with interleukin 6 receptor (IL-6r), IL-6, gp130 and a battery of inflammatory markers. The rs4537545 single nucleotide polymorphism (SNP) tags the functional non-synonymous Asp358Ala variant (rs8192284) in IL-6r (r(2)=0.89, n=343). Individuals homozygous for the rs4537545 SNP minor allele (frequency 40%) had a doubling of IL-6r levels (132.48 pg/ml, 95% CI 125.13-140.27) compared to the common allele homozygous group (68.31 pg/ml, 95% CI 65.35-71.41): in per allele regression models, the rs4537545 SNP accounted for 20% of the variance in sIL-6r, with P=5.1 x 10(-62). The minor allele of rs4537545 was also associated with higher circulating IL-6 levels (P=1.9 x 10(-4)). There was no association of this variant with serum levels of gp130 or with any of the studied pro- and anti-inflammatory markers. A common variant of the IL-6r gene results in major changes in IL-6r and IL-6 serum levels, but with no apparent effect on gp130 levels or on inflammatory status in the general population.
Rafiq
S
S
Peninsula Medical School, Institute of Biomedical and Clinical Science, Exeter, UK.
Frayling
T M
TM
Murray
A
A
Hurst
A
A
Stevens
K
K
Weedon
M N
MN
Henley
W
W
Ferrucci
L
L
Bandinelli
S
S
Corsi
A-M
AM
Guralnik
J M
JM
Melzer
D
D
D000368:Aged; D000483:Alleles; D050822:Cytokine Receptor gp130 / Q000097:blood; D016207:Cytokines / Q000097:blood; D005260:Female; D020022:Genetic Predisposition to Disease; D006801:Humans; D007249:Inflammation / Q000235:genetics / Q000276:immunology; D015850:Interleukin-6 / Q000097:blood / Q000235:genetics* / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D020641:Polymorphism, Single Nucleotide; D019947:Receptors, Interleukin-6 / Q000097:blood / Q000235:genetics*
D016207:Cytokines; D015850:Interleukin-6; D019947:Receptors, Interleukin-6; D050822:Cytokine Receptor gp130