The association of interleukin-18 genotype and serum levels with metabolic risk factors for cardiovascular disease.
OBJECTIVE
Circulating levels of interleukin (IL)-18 are associated with the metabolic syndrome and risk for the development of cardiovascular disease (CVD). This study investigated the association between the circulating IL-18 levels and the -137 G/C polymorphism within the IL-18 gene with metabolic risk factors for CVD in normal-weight and obese black South African women.


METHODS
Blood pressure (BP), body composition (dual-energy X-ray absorptiometer), visceral adiposity (computerized tomography), as well as fasting glucose, insulin, lipid profile, IL-18 levels, and IL-18 genotype were measured in 104 normal-weight (body mass index (BMI) < or = 25 kg/m2) and 124 obese (BMI > or = 30 kg/m2) black South African women.


RESULTS
Subjects with a GC genotype (23%) had a greater mean arterial pressure (MAP, 90.6+/-11.1 vs 85.5+/-10.3 mmHg, P<0.001) than the subjects with the GG genotype. Serum IL-18 levels were not associated with IL-18 genotype (P=0.985); however, they significantly correlated with percentage of body fat (r=0.25, P<0.001), visceral adiposity (r=0.32, P<0.001), MAP (r=0.22, P=0.001), HOMA-IR (r=0.33, P<0.001), fasting insulin (r=0.25, P<0.001), triglyceride (r=0.16, P<0.05), and high-density lipoprotein-cholesterol (r=-0.14, P<0.05) levels, after adjusting for age and body fatness.


CONCLUSIONS
We show for the first time that the GC genotype of the IL-18 -137 G/C polymorphism and the circulating IL-18 levels are independently associated with raised BP. Moreover, fasting IL-18 levels are associated with the other metabolic risk factors for CVD in normal-weight and obese black South African women.
Evans
Juliet
J
UCT/MRC Research Unit for Exercise Science and Sports Medicine, Department of Human Biology, Faculty of Health Sciences, University of Cape Town, PO BOX 115, Newlands, 7725 Cape Town, South Africa.
Collins
Malcolm
M
Jennings
Courtney
C
van der Merwe
Lize
L
Söderström
Ingegerd
I
Olsson
Tommy
T
Levitt
Naomi S
NS
Lambert
Estelle V
EV
Goedecke
Julia H
JH
D000293:Adolescent; D000328:Adult; D001786:Blood Glucose / Q000235:genetics / Q000378:metabolism; D001794:Blood Pressure / Q000235:genetics; D015992:Body Mass Index; D002318:Cardiovascular Diseases / Q000097:blood* / Q000209:etiology / Q000235:genetics; D005260:Female; D005838:Genotype; D006801:Humans; D007333:Insulin Resistance / Q000235:genetics; D020382:Interleukin-18 / Q000097:blood* / Q000235:genetics; D024821:Metabolic Syndrome / Q000097:blood* / Q000150:complications / Q000235:genetics; D008875:Middle Aged; D009765:Obesity / Q000097:blood / Q000150:complications / Q000235:genetics; D012307:Risk Factors
D001786:Blood Glucose; D020382:Interleukin-18