Increased Expression of Interleukin-18 and its Receptor in Peripheral Blood of Patients with Chronic Obstructive Pulmonary Disease

Figures & data

Table 1.  Clinical characteristics of subjects in this study

	Nonsmoker	Smoker	COPD
Subjects	32	30	58
Age yrs	57.8±1.7	58.5±1.4	63.4±1.0
Male	32(100%)	30(100%)	58(100%)
Smoking status
Current smoker	0	30(100%)	37(64%)
Ex-smoker n (yrs since quitting)	0	0	21(7.3±1.2)
Smoking index, p.y	0	41.9±2.6	44.2±2.5
GOLD stage
I	0	0	14
II	0	0	15
III	0	0	16
IV	0	0	13
BMI kg/m2	22.1±0.3	22.2±0.4	21.4±0.4
FEV1 L	3.11±0.11	2.91±0.07	1.47±0.09*
FVC L	3.69±0.11	3.56±0.09	2.97±0.10*
FEV1/FVC%	83.9±0.8	82.2±1.1	47.6±1.8*
FEV1% pred	105.1±2.1	102.9±2.3	55.6±3.3*
Medications
No medication	32(100%)	30(100%)	42(72%)
Bronchodilators	0	0	16(28%)
Inhaled corticosteroids	0	0	9(16%)
Systemic steroids	0	0	0

Values are numbers (%) or mean±SEM; COPD: Chronic Obstructive Pulmonary Disease; p.y: pack-yrs; GOLD: Global initiative for Obstructive Lung Disease; BMI: body mass index; FVC: forced vital capacity; FEV1: forced expiratory volume in one second;% pred:% predicted. *: p<0.05 versus nonsmoker and smoker.

Table 2.  Serum levels of interleukin (IL)-18, interferon (IFN)-γ and high sensitivity C-reactive protein (hsCRP) in subjects

	Nonsmoker	Smoker	COPD
Subjects n	32	30	58
Serum IL-18 pg/ml	162.8±12.6	255.5±13.6*	323.6±9.4*†
Serum IFN-γ pg/ml	1.2±0.4	1.2±0.5	1.4±0.4
Serum hsCRP mg/L	1.5±0.4	2.7±1.2	5.3±1.5 *†

Values are numbers or mean±SEM; COPD: Chronic Obstructive Pulmonary Disease; *: p<0.05 versus nonsmoker; †: p<0.05 versus smoker.

Figure 1.  Serum IL-18 levels in nonsmokers (N) (n = 32), current smokers (S) (n = 30) and stable chronic obstructive pulmonary disease (COPD) patients classified according to Global Initiative for Chronic Obstructive Lung Disease (GOLD) stage I (n = 14), II (n = 15), III (n = 16) and IV (n = 13). *: p<0.05 versus nonsmokers; **: p<0.05 versus current smokers, stable patients with GOLD stage I and II COPD.

Figure 2.  Correlation between serum IL-18 levels and forced expiratory volume in one second (FEV1)% predicted in stable chronic obstructive pulmonary disease patients (n = 58). The gradient and intercept of the best-fit line are -0.1799 and 113.8, respectively (r = 0.5108 and p<0.001).

Figure 3.  A representative three-color flow cytometric analysis of IL-18Rα expression on CD3+ cells (T lymphocytes) and CD3+CD8+ cells (CD8+ T lymphocytes) in a nonsmoker. The number in each panel indicates a percentage of IL-18Rα-positive cells gated in CD3+ cells or CD3+CD8+ cells.

Figure 4.  A representative three-color flow cytometric analysis of IL-18Rα expression on CD3+ cells (T lymphocytes) and CD3+CD8+ cells (CD8+ T lymphocytes) in a current smoker. The number in each panel indicates a percentage of IL-18Rα-positive cells gated in CD3+ cells or CD3+CD8+ cells.

Figure 5.  A representative three-color flow cytometric analysis of IL-18Rα expression on CD3+ cells (T lymphocytes) and CD3+CD8+ cells (CD8+ T lymphocytes) in a stable chronic obstructive pulmonary disease patient (COPD). The number in each panel indicates a percentage of IL-18Rα-positive cells gated in CD3+ cells or CD3+CD8+ cells.

Figure 6.  Expression of IL-18Rα on peripheral CD3+ lymphocytes (T lymphocytes). Percentages of IL-18Rα-positive T lymphocytes in flow cytometric analysis are indicated in nonsmokers (N), current smokers (S) and stable chronic obstructive pulmonary disease patients (C). *: p<0.05 versus nonsmokers and current smokers.

Figure 7.  Expression of IL-18Rα on peripheral CD3+CD8+ lymphocytes (CD8+ T lymphocytes). Percentages of IL-18Rα-positive CD8+ T lymphocytes in flow cytometric analysis are indicated in nonsmokers (N), current smokers (S) and stable chronic obstructive pulmonary disease patients (C). *: p<0.05 versus nonsmokers and current smokers.

Table 3.  The proportion of interleukin (IL)-18R-expressing T lymphocytes and CD8+ T lymphocytes in subjects

	Nonsmoker	Smoker	COPD
Subjects n	32	30	58
T lymphocyte%	49.6±1.6	54.3±1.9	60.5±1.6*
CD8+ T lymphocyte%	51.4±2.1	51.6±2.3	59.3±1.8*

Values are numbers or mean±SEM; COPD: Chronic Obstructive Pulmonary Disease; *: p<0.05 versus nonsmoker and smoker.