Association of the Tight Junction Protein Claudin-4 with Lung Function and Exacerbations in Chronic Obstructive Pulmonary Disease

Figures & data

Table 1 Clinical Characteristics of the Healthy Control Subjects and the COPD Patients

Clinical Variables	Control Subjects (N = 25)	COPD Patients (N = 30)		P-value
		Stable State	Exacerbated State
Age (years)	69.31 ± 6.63	67.61 ± 6.18		0.295
Sex (male/female)	2/23	30/0		<0.001
BMI (kg/m^2)	24.84 ± 2.61	21.38 ± 2.24		<0.001
Smoking status (NS/ES/CS)	25/0/0	1/18/11		NA
Cigarettes smoked (pack-year)	NA	38.17 ± 24.50		<0.001
Baseline lung function at enrollment
FVC (%pred)	96.56 ± 14.51	66.90 ± 23.59		<0.001
FEV1 (%pred)	115.36 ± 16.59	44.43 ± 13.89		<0.001
FEV1/FVC	84.24 ± 6.05	47.10 ± 12.17		<0.001
Lung function at stable and exacerbated state		(N = 19)	(N = 24)
FVC (%pred)	NA	69.32 ± 17.25	56.00 ± 14.65	0.002
FEV1 (%pred)	NA	47.53 ± 13.14	35.67 ± 12.37	0.001
FEV1/FVC	NA	49.79 ± 11.21	43.75 ± 9.04	0.082
Total IgE (kU)	30.42 ± 106.68	333.24 ± 719.69		<0.001
Blood WBC (/μL)	5587.20 ± 1268.00	7699.44 ± 2202.82	11,341.74 ± 3804.23	0.001*, 0.012^†
Blood neutrophils (%)	56.25 ± 10.00	58.96 ± 8.88	74.24 ± 10.74	<0.001^†
Blood eosinophils (%)	2.73 ± 2.26	3.98 ± 4.61	2.02 ± 2.41	0.019^†

Notes: Data are presented as mean ± standard deviation. *P<0.05 compared with control subjects; ^†P<0.05 compared with stable COPD.

Abbreviations: COPD, chronic obstructive pulmonary disease; BMI, body mass index; NS, non-smokers; ES, ex-smokers; CS, current smokers; FVC, forced vital capacity; FEV₁, forced expiratory volume in one second; %pred, percentage of predicted value; IgE, immunoglobulin E; WBC, white blood cells; NA, not applicable.

Figure 1 The plasma claudin-4 (CLDN4) levels of the subjects. The plasma CLDN4 levels of healthy control subjects were compared to those of patients with stable (ST) or exacerbated (EXA) chronic obstructive pulmonary disease (COPD). *P<0.05, control vs COPD-ST; ^†P<0.05, COPD-ST vs COPD-EXA.

Figure 2 Association of plasma claudin-4 (CLDN4) levels and lung function of chronic obstructive pulmonary disease (COPD) patients. (A) Forced vital capacity (FVC), and (B) forced expiratory volume in one second (FEV1) of COPD-stable (ST) was correlated with plasma CLDN5 levels.

Abbreviation: EXA, exacerbated.