APOE gene polymorphism linked to CRP, IL-6 levels
MedWire News: Study findings suggest that carriers of the ε4 allele of the apolipoprotein E gene (APOE) are less likely to have elevated levels of several markers of inflammation than noncarriers.
Indeed, "ε4 carriers have significantly lower C-reactive protein (CRP) levels and marginally significantly lower interleukin-6 (IL-6) levels," remark the researchers.
The team also confirmed previous findings of a protective effect of APOE on blood lipids by showing that carriage of the APOE ε2 allele was significantly associated with lower levels of total cholesterol and higher levels of high-density lipoprotein (HDL) cholesterol.
Sarinnapha Vasunilashorn (Princeton University, New Jersey, USA) and colleagues assessed the relationship between individual APOE genotypes and mortality, as well as a set of biomarkers related to cardiovascular and immune function, in over 1000 Taiwanese individuals who participated in the Social Environment and Biomarkers of Aging Study (SEBAS). All participants were older than 54 years at baseline (2000).
The frequencies of the ε2, ε3, and ε4 APOE alleles were 8.0%, 84.7%, and 7.3%, respectively.
As reported in the journal Atherosclerosis, ε4 carriers were 38% less likely to have elevated CRP levels (≥3 mg/l) than noncarriers. They were also 38% less likely to have at-risk levels of IL-6 (≥4.64 pg/ml), but this finding did not reach statistical significance.
Compared with ε2 noncarriers, ε2 carriers were 55% less likely to have high levels of total cholesterol (≥240 mg/dl [6.22 mmol/l]) and 55% less likely to have low levels of HDL cholesterol (<40 mg/dl [1.04 mmol/l] in men or <50 mg/dl [1.30 mmol/l] in women).
"Numerous studies have linked APOE to health outcomes including cardiovascular disease and mortality, but far fewer studies have examined the relationship of APOE to other biological markers of health," write Vasunilashorn and co-authors.
"Our findings highlight a less frequently noted relationship between APOE ε4 and lower CRP levels and suggest a potential relationship between APOE and IL-6," they say.
Of note, in the present study, APOE carrier status had no significant effect on 6-year changes in levels of any of the biomarkers examined. Furthermore, APOE genotype was not associated with mortality after 8 years of follow-up.
"Further investigations regarding the mechanism underlying the relationship between APOE polymorphisms and inflammatory markers will contribute to our understanding of the effects of the APOE gene on health and survival," conclude the researchers.
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By Nikki Withers