IL-27 and Type-2 immunity in asthma: Association with severity, CXCL9 and STAT signaling

Background—Severe asthma may involve both innate and Type-2 cytokine associated adaptive immunity. While IL-27 has been reported to potentiate Th1 responses (including the chemokine CXCL9) and suppress Th2 responses, its function in asthma is unknown. Objective—Evaluate IL-27 expression in human asthma, alone and in combination with Type-2 immunity to determine the relationship to disease severity and CXCL9 expression. Model these interactions in vitro in human bronchial epithelial cells (HBEC). Methods—Bronchoalveolar lavage (BAL) cells from 87 participants were evaluated for IL-27 mRNA and protein, alone and in association with epithelial CCL26 (a marker of Type-2 activation) in relation to asthma severity and CXCL9 mRNA. HBECs cultured in air liquid interface (ALI) and stimulated with IL-27 (1–100 ng/ml) with/without IL-13 (1 ng/ml) were evaluated for CXCL9 expression by qRT-PCR and ELISA. Phosphorylated and total STAT1/3 were detected by western blot. siRNA knockdown of STAT1 or STAT3 was performed. Results—BAL cell IL-27 mRNA and protein were increased in asthma. Patients with evidence for Type-2 pathway activation had higher IL-27 expression (p=0.02). Combined IL-27 and CCL26 expression associated with more severe asthma and higher CXCL9 expression (p=0.004, 0.007 respectively), while IL-27 alone was associated with milder disease. In vitro, IL-13 augmented IL-27 induced CXCL9 expression which appeared to be due to augmented STAT1 activation and reduced STAT3 activation. © 2014 American Academy of Allergy, Asthma amp; Immunology. All rights reserved. Corresponding Author: Sally E. Wenzel, MD, Pulmonary Allergy Critical Care Medicine Division, University of Pittsburgh Asthma Institute@UPMC/UPSOM, NW628 Montefiore Hospital, 3459 Fifth Avenue, Pittsburgh, PA 15213, USA. Phone: 412 802 6859, Fax: 412 605 1999, wenzelse@upmc.edu. Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. NIH Public Access Author Manuscript J Allergy Clin Immunol. Author manuscript; available in PMC 2016 February 01. Published in final edited form as: J Allergy Clin Immunol. 2015 February ; 135(2): 386–394.e5. doi:10.1016/j.jaci.2014.08.023. N IH -P A A uhor M anscript N IH -P A A uhor M anscript N IH -P A A uhor M anscript Conclusions—IL-27, in combination with a Type-2/CCL26 signature identifies a more severe asthma phenotype, perhaps through combined effects of IL-27 and IL-13 on STAT signaling. Understanding these interactions could lead to new targets for asthma therapy.