Increased plasma interleukin-1 receptor antagonist levels in men with visceral obesity

Figures & data

Table

AT	adipose tissue
ANOVA	analysis of variance
BMI	body mass index
CRP	C-reactive protein
HDL	high-density lipoprotein
IDF	International Diabetes Federation
IFN-β	interferon-beta
IL-1Ra	interleukin-1 receptor antagonist
IL-6	interleukin-6
NCEP	National Cholesterol Education Program
OGTT	oral glucose tolerance test
TNF-α	tumor necrosis factor-alpha
SD	Standard deviation

Table I.  Anthropometric and metabolic characteristics of the study.

Variables	Values	25th–75th percentile
n	117
Age (years)	44.9±10.1	(39–52.5)
Body mass index (kg/m^2)	28.8±4.5	(25.5–32.1)
Weight (kg)	87.5±14.7	(76.8–97.4)
Waist girth (cm)	100.6±13.2	(91.0–109.6)
Adipose tissue accumulation (cm^2):
visceral	199±95	(128–270)
subcutaneous	263±115	(180–318)
total	460±176	(325–561)
Cholesterol (mmol/L)	4.92±0.80	(4.5–5.5)
LDL cholesterol (mmol/L)	3.04±0.67	(2.6–3.5)
HDL cholesterol (mmol/L)	0.99±0.21	(0.9–1.1)
Cholesterol/HDL cholesterol	5.13±1.12	(4.5–5.8)
Triglycerides (mmol/L)	2.06 (1.40, 2.69)
Apolipoprotein B (g/L)	1.03±0.20	(0.92–1.16)
Apolipoprotein A1 (g/L)	1.15±0.15	(1.04–1.24)
Fasting insulin (pmol/L)	102 (62, 177)
Fasting glucose (mmol/L)	5.75±0.49	(5.5–6.1)
Insulin area ((pmol/L/min)×10^−3)	114 (60.8, 179)
Glucose area ((mmol/L/min)×10^−3)	1.35 (1.18, 1.48)
HOMA	26.9 (15.5, 45.8)
C-reactive protein (mg/L)	1.34 (0.66, 2.58)
Leptin (ng/mL)	7.89 (4.56, 12.21)
Adiponectin (µg/mL)	3.94 (2.99, 5.59)
Interleukin-1Ra (pg/mL)	218 (160, 299)
Interleukin-6 (pg/mL)	0.94 (0.65, 1.27)
Tumor necrosis factor-α (pg/mL)	0.99 (0.77, 1.22)

Data are presented as mean±SD, or as median (interquartile range) for skewed variables.

HDL = high-density lipoprotein; LDL = low-density lipoprotein.

HOMA = fasting insulin (mmol/L)×fasting glucose (µmol/L)/22.5.

Table II.  Spearman correlation coefficients between concentrations of IL-1Ra and indices of adiposity and cardiometabolic risk variables.

	IL-1Ra	P-value
Body mass index (kg/m^2)	0.47	≤0.0001
Weight (kg)	0.41	≤0.0001
Waist girth (cm)	0.48	≤0.0001
Adipose tissue accumulation (cm^2):
visceral	0.47	≤0.0001
subcutaneous	0.39	≤0.0001
total	0.50	≤0.0001
Cholesterol (mmol/L)	0.08
LDL cholesterol (mmol/L)	0.00
HDL cholesterol (mmol/L)	−0.42	≤0.0001
Cholesterol/HDL cholesterol	0.43	≤0.0001
Triglycerides (mmol/L)	0.46	≤0.0001
Apolipoprotein B (g/L)	0.24	<0.05
Apolipoprotein A1 (g/L)	−0.28	<0.05
Fasting insulin (pmol/L)	0.49	≤0.0001
Fasting glucose (mmol/L)	0.22	<0.05
Insulin area ((pmol/L/min)×10^−3)	0.46	≤0.0001
Glucose area ((mmol/L/min)×10^−3)	0.47	≤0.0001
C-reactive protein (mg/L)	0.40	≤0.0001
Leptin (ng/mL)	0.37	≤0.0001
Adiponectin (µg/mL)	−0.35	≤0.0001
Interleukin-6 (pg/mL)	0.34	<0.001
Tumor necrosis factor-α (pg/mL)	0.27	<0.001

HDL = high-density lipoprotein; IL-1Ra = interleukin-1 receptor antagonist; LDL = low-density lipoprotein.

Figure 1.  Respective contributions of plasma IL-1Ra levels and visceral AT to the variance in metabolic risk variables (fasting insulin (A), area under the curve (AUC) of plasma insulin (B), triglycerides (C), and cholesterol/HDL cholesterol ratio (D)) in the different subgroups (1, 2, 3, 4) classified on the basis of the 50th percentile of visceral AT and IL-1Ra. Because variables were skewed, P-values of the log-transformed values are presented in panels A, B, and C (1, 2, 3 = significantly different from the corresponding subgroups; P < 0.05). IL-1Ra = interleukin-1 receptor antagonist; AT = adipose tissue; HDL = high-density lipoprotein.

Figure 2.  Plasma IL-1Ra levels among subgroups of men classified on the basis of their number of cardiometabolic risk variables. a = significantly different from score 0: P < 0.05 on log-transformed values; b = significantly different from score 1: P < 0.05 on log-transformed values; c = significantly different from score 2: P < 0.05 on log-transformed values. HDL = high-density lipoprotein; AUC = area under the curve; IL-1Ra = interleukin-1 receptor antagonist.

Table III.  Multiple regression analyses for relative contributions of fat distribution and IL-1Ra to the variance in indices of plasma glucose-insulin homeostasis and lipids.

Dependent variable	Independent variable(s) (partial R^2)	Total R^2 (%)	P-value
Fasting insulin	Visceral AT (24.5%) Subcutaneous AT (5.3%) IL-1Ra (2.8%)	32.6	<0.05
Insulin area	Visceral AT (28.8%) IL-1Ra (5.2%) Subcutaneous AT (2.8%)	36.7	<0.05
Glucose area	Visceral AT (16.6%) IL-1Ra (5.1%)	21.6	<0.01
Triglycerides	Visceral AT (31.8%) IL-1Ra (7.9%) Subcutaneous AT (3.2%)	42.8	<0.05
HDL cholesterol	IL-1Ra (28.1%)	28.1	<0.0001
Cholestrol/HDL cholesterol	IL-1Ra (25.8%) Visceral AT (5.8%)	31.7	<0.01
Apolipoprotein B	Visceral AT (13.2%)	13.2	<0.0001
Apolipoprotein A1	IL-1Ra (9.3%)	9.3	<0.001

Visceral AT, subcutaneous AT and circulating IL-1Ra levels were the variables included in the model.

AT = adipose tissue; HDL = high-density lipoprotein; IL-1Ra = interleukin-1 receptor antagonist.