Antimicrobial Peptides SLPI and Beta Defensin-1 in Sputum are Negatively Correlated with FEV₁

Figures & data

Table 1 Patient Characteristics of Participants with Available Sputum

	Healthy	Asthma	COPD	p-value
Number of participants	9	21	14
Age (years) ^‡	36 (23–66)	55 (34–74)	65 (50–82)	0.001***
Sex (% male)	33.3	33.3	42.9	0.378
FEV1 (L) ^†	2.92 (0.84)	2.69 (0.84)	1.80 (0.88)	0.001***
FEV1% Predicted^†	90.4 (11.4)	86.9 (19.30)	56.7 (19.1)	<0.0001****
FEV1/FVC ratio^†	0.80 (0.07)	0.69 (0.10)	0.53 (0.15)	<0.0001****
Smoker (% Current/Ex/Non)	0/14/86	10/33/57	36/64/0	<0.001***
Pack years (years) ^‡	1.4 (0–13)	4.6 (0–33.75)	52.8 (9.75–200)	<0.0001****
Proportion on ICS (%)	0	85.6	71.5	<0.0001****
Total sputum cell count (x10^6/g) ^§	0.33 (0.19–0.83)	0.76 (0.45–1.30)	0.94 (0.50–1.75)	0. 137
Sputum neutrophils %^§	28.92 (12.56–66.58)	52.97 (32.48–86.37)	69.11 (59.93–79.71)	0.079
Proportion with neutrophilic inflammation (defined >70%, %)	14.3	42.9	35.7	0.323
Sputum eosinophils %^§	0.2 (0.2–0.75)	0.2 (0–1.2)	1 (0.7–10.5)	0.051
Proportion with eosinophilic inflammation (defined >3%, %)	14.3	14.3	28.6	0.325
Total CFU (x10^6) ^§	1.17 (0.82–1.68)	1.18 (0.82–1.68)	0.64 (0.30–1.36)	0.169
NTHi (log gene copies/g sputum plug) ^†	4.968 (2.125)	4.228 (3.123)	4.832 (5.288)	0.854
Sputum SLPI (ng/mL) ^§	728.8 (449.4–1182)	231.8 (153.9–349.2)	1076.0 (813.4–1423)	<0.001****
Sputum Osteopontin (pg/mL) ^§	278.2 (125.6–1066)	166.1 (101.1–272.9)	260.5 (5.8–704.3)	0.707
Sputum Beta defensin-1 (ng/mL) ^§	17.31 (11.38–26.32)	4.86 (2.79–8.45)	15.69 (10.29–23.59)	0.008**
Sputum Elafin (ng/mL) ^§	21.65 (11.93–39.27)	19.9 (13.72–28.95)	19.26 (15.49–25.15)	0.897

Notes: Data are presented as ^†= Mean (SD), ^‡= Mean (Range), ^§=Geometric mean (95% CI). Significant difference between the three groups where **p<0.01, ***p<0.001, ****p<0.0001.

Abbreviations: FEV1, forced expiratory volume in 1 second; FVC, forced vital capacity; ICS, inhaled corticosteroids; CFU, colony forming units; NTHi, non typeable Haemophilus influenzae; SLPI, secretory leucocyte protease inhibitor.

Table 2 Correlation Analysis of Participant Characteristics and Sputum AMP Concentrations in All Participants. Significant Correlation Where *p<0.5, **p<0.01, ***p<0.001

	SLPI	Osteopontin	Elafin	Beta Defensin-1
Age (years)	p=0.060, r=0.286	p=0.940, r=−0.012	p=0.764, r=−0.048	p=0.024*, r=0.341
FEV1 (L)	P<0.001***, r=−0.610	p=0.408, r=−0.144	p=0.454, r=0.137	p<0.001***, r=−0.594
FEV1% Predicted	P<0.001***, r=−0.583	p=0.560, r=−0.105	p=0.341, r=0.180	p=0.159, r=−0.221
FEV1/FVC ratio	p=0.001**, r=−0.528	p=0.369, r=−0.157	p=0.276, r=0.199	p=0.369, r=−0.157
Pack years (years)	p=0.082, r=0.269	p=0.382, r=0.137	p=0.501, r=−0.110	p=0.382, r=0.137

Figure 1 Comparison of peptide levels in sputum from healthy donors (n=9), asthmatics (n=21) and patients with COPD (n=14) tested in duplicate. (A) SLPI, (B) osteopontin, (C) elafin and (D) beta defensin-1. Data shown as geometric mean and 95% confidence intervals. Significant differences represented as *p<0.05, **p<0.01, ****p<0.0001.

Figure 2 Peptide levels in sputum from asthmatics and COPD patients grouped into sputum neutrophil high and low groups are similar. (A) SLPI, (B) osteopontin, (C) elafin and (D) beta defensin-1. Graph showing asthmatic patients (n=21) (o) and COPD patients (n=14) (●), tested in duplicate. Data shown as geometric mean and 95% confidence intervals.

Figure 3 Correlation of NTHi presence in the airway and peptide levels in healthy donors (n=7, white dots), patients with COPD (n=9, grey dots) and asthma (n=2, black dots), tested in duplicate. (A) SLPI, (B) osteopontin, (C) elafin and (D) beta defensin-1.

Figure 4 (A) Beta defensin-1 release from HBECs when untreated and infected with NTHi. (B) Elafin release from HBECs when untreated and infected with NTHi. Results are shown as a mean percentage change from untreated cell release. Tests were run in duplicate per experiment, from three separate experiments for each donor. Donors: health (n=3, white bars) and COPD (n=3, grey bars). Significant changes form basal release shown as * p<0.05 and ** p<0.01.

Figure 5 (A) Beta defensin-1 release from HBECs treated with high steroid concentrations. (B) Elafin release from HBECs treated with high steroid concentrations. Results are shown as a mean percentage change from untreated cell release. Tests were run in duplicate per experiment, from three separate experiments for each donor. High Budesonide (Bud): 16nM, High Fluticasone propionate (FP): 10nM. Donors: health (n=3, white bars), COPD (n=3, grey bars).