Table 2.

Correlation of Epithelial Brushing RNA-Sequencing Results with Airway Physiology, Induced Sputum Markers, and Airway Wall Morphometry

Gene Symbol	Lung Function (FEV1/FVC)	Direct AHR (MCh PC20)	Indirect AHR		Induced Sputum		Airway Wall Morphometry
			Max EIB	AUC30	T2GM	Sputum EOS	Epi MCs	Subepi MCs	Epi EOS	Subepi EOS
T2 inflammation-associated genes
CLCA1	—	—	0.48	0.41	0.32	—	0.41	—	—	—
POSTN	—	—	0.48	0.35	—	—	0.72	—	—	—
SERPINB2	—	—	0.48	0.43	0.32	—	0.40	—	—	—
NOS2	—	—	0.42	0.37	—	—	0.55	—	—	—
Mast cell–related genes
CPA3	0.20	—	0.51	0.47	0.54	—	0.32	—	0.36	—
KIT	—	—	0.31	0.28	0.32	—	0.25	—	0.31	—
SIGLEC6	0.26	—	0.52	0.49	0.40	—	0.25	—	0.30	—
TPSAB1	—	—	0.44	0.38	0.58	—	—	—	0.45	—
TPSG1	0.28	—	0.24	0.22	—	—	—	0.28	0.35	—
Cytokines/inflammatory receptors
CXCR6	—	—	—	—	—	—	—	0.35	0.44	—
IFNG	—	—	—	—	—	0.24	—	0.40	0.58	—
IL18R1	—	—	0.29	0.29	—	—	—	0.25	0.29	—
IL1RL1	—	—	0.49	0.46	0.47	—	0.41	—	0.30	—
IL23R	—	—	0.46	0.44	—	—	0.43	—	—	—
P2RY10	—	—	—	—	—	—	—	0.31	0.56	—

Definition of abbreviations: AHR = airway hyperresponsiveness; AUC30 = area under the curve of FEV₁ versus time curve during exercise challenge; EIB = exercise-induced bronchoconstriction; EOS = eosinophils; Epi = the density of a specific cell population within the epithelial compartment of the airway wall (no./mm²); Max EIB = maximum percentage decline in FEV₁ from baseline after exercise challenge; MCh PC₂₀ = provocative concentration of methacholine required to reduce FEV₁ by 20%; MCs = mast cells; N/A = not applicable; Sputum EOS = the concentration of EOS identified in induced sputum (×10³ cells per milliliter); Subepi = the density of a specific cell population in the subepithelial compartment of the airway wall (no./mm²); T2 = type 2; T2GM = type-2 gene mean.

This heatmap shows P values from a simple linear regression analysis of 15 selected differentially expressed genes of interest (genes implicated in type-2 inflammation, mast cell gene expression, and inflammatory cytokines and their receptors) that had relatively increased expression in individuals who had asthma with exercise-induced bronchoconstriction versus individuals who had asthma without exercise-induced bronchoconstriction with airway physiology, induced sputum markers, and airway wall morphometry. Blue indicates a negative relationship, and red indicates a positive relationship, between gene expression and the selected parameter. Correlations highlighted in blue or red in the heatmap have a P value <0.05, and the numerical values listed within the boxes represent the coefficients of determination (r²) obtained from a simple linear regression analysis. Dashes in gray boxes indicate no significant correlation.