Abstract

BACKGROUND: A variant in the IL-6 receptor (IL-6R) gene increases asthma risk and is predicted to decrease IL-6 classic signaling and increase IL-6 trans-signaling. This suggests that inhibition of IL-6 trans-signaling, but not classic signaling, might suppress allergic airway inflammation. OBJECTIVES: We sought to determine whether IL-6 signaling contributes to (1) acute experimental asthma induced by clinically relevant allergens and (2) variation in asthma clinical phenotypes in asthmatic patients. METHODS: Mice were sensitized to house dust mite (HDM) or cockroach at day 0, treated with IL-6R inhibitors at day 13, and challenged with the same allergen at days 14 to 17. End points were measured 3 hours after the final challenge. IL-6 and soluble IL-6 receptor (sIL-6R) expression in induced sputum of asthmatic patients was correlated with asthma clinical phenotypes. RESULTS: Both HDM and cockroach induced a type 2/type 17 cytokine profile and mixed granulocytic inflammation in the airways. Both allergens increased IL-6 expression in the airways, but only cockroach induced sIL-6R expression. Therefore HDM challenge promoted IL-6 classic signaling but not trans-signaling; in this model treatment with anti-IL-6R did not suppress airway inflammation. In contrast, cockroach-induced inflammation involved activation of IL-6 trans-signaling and production of IL-17A by gammadelta T cells. Anti-IL-6R, selective blockade of sIL-6R, or gammadelta T-cell deficiency significantly attenuated cockroach-induced inflammation. Asthmatic patients with high airway IL-6 and sIL-6R levels were enriched for the neutrophilic and mixed granulocytic subtypes. CONCLUSION: Experimental asthma associated with both high IL-6 and high sIL-6R levels in the airways is attenuated by treatment with IL-6R inhibitors.

Authors	Ullah, Ashik; Revez, Joana A.; Loh, Zhixuan; Simpson, Jennifer; Zhang, Vivian; Bain, L.; Varelias, Antiopi; Rose-John, Stefan; Blumenthal, Antje; Smyth, M. J.; Hill, Geoffrey R.; Sukkar, Maria B.; Ferreira, Manuel A. R.; Phipps, Simon
Journal	The Journal of allergy and clinical immunology
Pages	1065-73
Volume	136
Date	1/10/2015
Grant ID
Funding Body
URL	http://www.ncbi.nlm.nih.gov/pubmed/?term=10.1016/j.jaci.2015.02.032