Elevation of IL-6 in the allergic asthmatic airway is independent of inflammation but associates with loss of central airway function.
BACKGROUND
Asthma is a chronic inflammatory disease of the airway that is characterized by a Th2-type of immune response with increasing evidence for involvement of Th17 cells. The role of IL-6 in promoting effector T cell subsets suggest that IL-6 may play a functional role in asthma. Classically IL-6 has been viewed as an inflammatory marker, along with TNFalpha and IL-1beta, rather than as regulatory cytokine.


OBJECTIVE
To investigate the potential relationship between IL-6 and other proinflammatory cytokines, Th2/Th17 cytokines and lung function in allergic asthma, and thus evaluate the potential role of IL-6 in this disease.


METHODS
Cytokine levels in induced sputum and lung function were measured in 16 healthy control and 18 mild-moderate allergic asthmatic subjects.


RESULTS
The levels of the proinflammatory biomarkers TNFalpha and IL-1beta were not different between the control and asthmatic group. In contrast, IL-6 levels were specifically elevated in asthmatic subjects compared with healthy controls (p < 0.01). Hierarchical regression analysis in the total study cohort indicates that the relationship between asthma and lung function could be mediated by IL-6. Among Th2 cytokines only IL-13 (p < 0.05) was also elevated in the asthmatic group, and positively correlated with IL-6 levels (rS = 0.53, p < 0.05).


CONCLUSIONS
In mild-moderate asthma, IL-6 dissociates from other proinflammatory biomarkers, but correlates with IL-13 levels. Furthermore, IL-6 may contribute to impaired lung function in allergic asthma.
Neveu
Wendy A
WA
Department of Medicine, Division of Immunobiology, University of Vermont, Burlington, Vermont 05405, USA.
Allard
Jenna L
JL
Raymond
Danielle M
DM
Bourassa
Lorraine M
LM
Burns
Stephanie M
SM
Bunn
Janice Y
JY
Irvin
Charles G
CG
Kaminsky
David A
DA
Rincon
Mercedes
M
D000328:Adult; D001249:Asthma / Q000276:immunology*; D016207:Cytokines / Q000276:immunology*; D005260:Female; D006801:Humans; D015850:Interleukin-6 / Q000276:immunology*; D008168:Lung / Q000276:immunology*; D008297:Male; D011014:Pneumonia / Q000150:complications / Q000276:immunology*; D012130:Respiratory Hypersensitivity / Q000276:immunology*
D016207:Cytokines; C508600:IL6 protein, human; D015850:Interleukin-6