Development of a screening protocol to identify persons who are responsive to wood smoke particle-induced airway inflammation with pilot assessment of GSTM1 genotype and asthma status as response modifiers

Figures & data

Table 1. Subject demographics.

Total Subjects	N = 52
Healthy	N = 40
Asthmatic	N = 12
Female	N = 26 (50%)
Race
Asian	N = 2
Black	N = 9
White	N = 40
Other	N = 1
BMI	25.6 + 0.7 (range 17.4–38)
Age (years)	27.4 + 0.8 (range 19.4–40.3)
GSTM1 null	N = 20
GSTM1 sufficient	N = 26
Refused GSTM1 testing	N = 6

Subject demographics.

Figure 1. Sputum inflammatory response to WSP of the entire cohort.

Sputum % PMN (Panel A), PMN/mg sputum (Panel B), IL-1β (Panel C), IL-6 (Panel D), IL-8 (Panel E) and TNFα (Panel F) at baseline, 6- and 24-hours post WSP challenge in the total unstratified cohort. Asterisk denotes mixed model analysis using a compound symmetry covariance matrix where fit used Restricted Maximum Likelihood (REML) to allow for overall and multiple comparisons and missing data.

Figure 2. Spirometric and blood pressure endpoints at baseline and immediately after WSP challenge of the entire unstratified cohort.

Spirometric and blood pressure endpoints at baseline and immediately after WSP challenge in the total unstratified cohort. Asterisk denotes paired t-test.

Table 2. Correlative analysis for inflammatory biomarkers.

	6 hours correlations			24 hours correlations
	% change in %PMN vs.			% change in %PMN vs.
	% change in inflammatory biomarkers			% change in inflammatory biomarkers
	rho	p	n	rho	p	N
IL-1β	0.06	0.70	42	0.39	0.02	36
IL-6	–0.25	0.10	43	0.36	0.04	34
IL-8	–0.08	0.60	43	0.37	0.02	37
TNFα	0.03	0.80	43	0.09	0.60	36
PMN/mg	0.35	0.02	47	0.60	<0.01	41

Correlative analysis outcomes for inflammatory biomarkers. Correlations (rho) between the % change in %PMN and the % change in inflammatory biomarkers at 6 and 24 hours post WSP exposure. Correlation (rho) values were determined by non-parametric Spearman rank correlational analysis.

Table 3. Systemic Endpoints of the Entire Cohort at 6 and 24 hours Post WSP Exposure.

Endpoint	Baseline			6hr post			24 hr post
	Mean	SE	N	Mean	SE	N	Mean	SE	N
%PMN blood	54.90	1.08	53	61.65*	0.88	52	57.21	1.09	53
PMN 10^6/uL blood	3.10	0.12	53	4.52*	0.14	52	3.50*	0.16	53
IL-8 blood	13.60	1.60	48	9.59	0.75	50	10.88	0.88	43
IL-6 blood	0.80	0.10	47	1.01	0.11	50	0.82	0.11	43
IL-1 beta blood	0.10	0.02	41	0.08	0.02	49	0.06	0.01	38
TNFalpha blood	2.36	0.21	48	2.09	0.17	50	2.15	0.15	43
CRP blood	2.60	0.40	45	2.60	0.42	44	2.67	0.46	45

Descriptive data (mean, standard error and n for available sample) for each systemic endpoint of the overall cohort at baseline, 6 and 24 hours after two-hour controlled exposure to 500ug/m³ WSP. Cytokines in blood are measured as pg/mL. Significance (p < 0.05) was obtained only for circulating PMN differential count (%PMN) and absolute PMN levels (10⁶/uL blood). Asterisk denotes mixed model analysis using a compound symmetry covariance matrix where fit used Restricted Maximum Likelihood (REML) to allow for overall and multiple comparisons and missing data.

Figure 3. Sputum Inflammatory Response to WSP of responsive volunteers as defined by %PMNs at 6 hours.

Sputum % PMN (Panel A), PMN/mg sputum (Panel B), IL-1β (Panel C), IL-6 (Panel D), IL-8 (Panel E) and TNFα (Panel F) at baseline, 6- and 24-hours post WSP challenge in the cohort of volunteers responsive to WSP based on a change from baseline of the 6-hour %PMN of at least 10% (N = 30). Asterisk denotes mixed model analysis using a compound symmetry covariance matrix where fit used Restricted Maximum Likelihood (REML) to allow for overall and multiple comparisons and missing data.

Figure 4. Spirometric (Panel A) and blood pressure (Panel B) endpoints at baseline and immediately after WSP challenge of responsive volunteers as defined by %PMNs at 6 hours.

Spirometric and blood pressure endpoints at baseline and immediately after WSP challenge in responders and non-responders defined at 6 hours. Asterisk denotes paired t-test test.

Figure 5. Sputum Inflammatory Response to WSP of responsive volunteers as defined by %PMNs at 24 hours.

Sputum % PMN (Panel A), PMN/mg sputum (Panel B), IL-1β (Panel C), IL-6 (Panel D), IL-8 (Panel E) and TNFα (Panel F) at baseline, 6- and 24-hours post WSP challenge in the cohort of volunteers responsive to WSP based on a change from baseline of the 24-hours %PMN of at least 10% (N = 28). Asterisk denotes mixed model analysis using a compound symmetry covariance matrix where fit used Restricted Maximum Likelihood (REML) to allow for overall and multiple comparisons and missing data.

Figure 6. Spirometric (Panel A) and blood pressure (Panel B) endpoints at baseline and immediately after WSP challenge of responsive volunteers as defined by %PMNs at 24 hours.

Spirometric and blood pressure endpoints at baseline and immediately after WSP challenge in responders and non-responders defined at 24 hours. Asterisk denotes paired t-test.

Data availability statement and materials

The datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request. Additionally, this study is listed in ClinicalTrials.gov (NCT02767973), and data will be posted in that database upon completion of the study. Where informed consent was given, all unused de-identified biospecimens will be stored and curated in the CEMALB Biorepository (IRB# 05-2528) for potential future use.