Altered serum levels of type I collagen turnover indicators accompanied by IL-6 and IL-8 release in stable COPD

Figures & data

Table 1 Definition and severity grading of COPD according to degree of airflow obstruction

Grade	Post-bronchodilator spirometry test
Grade 1 (mild COPD)	FEV1/FVC <70%; FEV1%pred ≥80%
Grade 2 (moderate COPD)	FEV1/FVC <70%; 50% ≤FEV1%pred <80%
Grade 3 (severe COPD)	FEV1/FVC <70%; 30% ≤FEV1%pred <50%
Grade 4 (very severe COPD)	FEV1/FVC <70%; FEV1%pred <30% or FEV1%pred <50% plus chronic respiratory failure

Abbreviation: %pred, percentage of predicted.

Table 2 Baseline characteristics between control and COPD groups

Characteristics	Control	COPD	P-value
N	25	20
Male/female, n	16/9	13/7	0.956
Age (years)	73.1±2.6	78.3±1.7	0.258
Smoker/non-smoker, n	10/15	12/8	0.192
Pack-years	10.8±3.2	22.4±5.2	0.098
FEV1, post-bronchodilator, L	1.628±0.123	0.878±0.051	<0.001
FEV1 %pred, post-bronchodilator, %	74.6±5.0	45.2±2.2	<0.001
FEV1/FVC%, %	78.5±1.9	57.1±2.3	<0.001

Note: Data are expressed as mean ± SEM.

Abbreviation: %pred, percentage of predicted; SEM, standard error of the mean.

Table 3 Combined assessment of severity conditions for patients with COPD

Combined COPD assessment	GOLD grade	GOLD group
Grade 1/group A, n (%)	0 (0)	0 (0)
Grade 2/group B, n (%)	9 (45)	3 (15)
Grade 3/group C, n (%)	11 (55)	1 (5)
Grade 4/group D, n (%)	0 (0)	16 (80)

Table 4 Comparison of inflammatory biomarkers between the COPD and control groups

Inflammatory biomarker	Control	COPD	P-value
CRP (mg/L)	10.3±2.3	17.8±5.5	0.383
IL-6 (pg/mL)	11.7±4.3	30.5±9.9	0.047
IL-8 (pg/mL)	35.9±5.7	51.9±7.7	0.178
TNF-α (pg/mL)	12.8±2.9	10.1±1.7	0.708

Note: Data are expressed as mean ± SEM.

Abbreviations: CRP, C-reactive protein; TNF, tumor necrosis factor; SEM, standard error of the mean.

Figure 1 Comparison of PICP and ICTP between COPD and control groups.

Notes: (A) Serum levels of PICP. (B) Serum levels of PICP in subjects with COPD and/or smoking habits. (C) Serum levels of ICTP. Data are graphed as mean ± SD. *P<0.05. Error bars show standard error.
Abbreviations: PICP, procollagen type I C-terminal peptide; ICTP, C-terminal telopeptide of type I collagen.

Table 5 Correlation analysis between serum levels of PICP, clinical variables, and inflammatory biomarkers

Variables	Serum levels of PICP
	r	P-value
Smoking (pack-year)	0.134	0.411
FEV1 %pred (%)	−0.250	0.119
FEV1/FVC% (%)	−0.251	0.118
CRP (mg/L)	0.077	0.646
IL-6 (pg/mL)	0.483	<0.001
IL-8 (pg/mL)	0.472	0.001
TNF-α (pg/mL)	0.220	0.147

Abbreviations: PICP, procollagen type I C-terminal peptide; %pred, percentage of predicted; CRP, C-reactive protein; TNF, tumor necrosis factor.