Phenotypic and functional translation of IL33 genetics in asthma.

Abstract

BACKGROUND:

Asthma is a complex disease with multiple phenotypes that may differ in disease pathobiology and treatment response. IL33 single nucleotide polymorphisms (SNPs) have been reproducibly associated with asthma. IL33 levels are elevated in sputum and bronchial biopsies of patients with asthma. The functional consequences of IL33 asthma SNPs remain unknown.

OBJECTIVE:

This study sought to determine whether IL33 SNPs associate with asthma-related phenotypes and with IL33 expression in lung or bronchial epithelium. This study investigated the effect of increased IL33 expression on human bronchial epithelial cell (HBEC) function.

METHODS:

Association between IL33 SNPs (Chr9: 5,815,786-6,657,983) and asthma phenotypes (Lifelines/DAG [Dutch Asthma GWAS]/GASP [Genetics of Asthma Severity & Phenotypes] cohorts) and between SNPs and expression (lung tissue, bronchial brushes, HBECs) was done using regression modeling. Lentiviral overexpression was used to study IL33 effects on HBECs.

RESULTS:

We found that 161 SNPs spanning the IL33 region associated with 1 or more asthma phenotypes after correction for multiple testing. We report a main independent signal tagged by rs992969 associating with blood eosinophil levels, asthma, and eosinophilic asthma. A second, independent signal tagged by rs4008366 presented modest association with eosinophilic asthma. Neither signal associated with FEV1, FEV1/forced vital capacity, atopy, and age of asthma onset. The 2 IL33 signals are expression quantitative loci in bronchial brushes and cultured HBECs, but not in lung tissue. IL33 overexpression in vitro resulted in reduced viability and reactive oxygen species-capturing of HBECs, without influencing epithelial cell count, metabolic activity, or barrier function.

CONCLUSIONS:

We identify IL33 as an epithelial susceptibility gene for eosinophilia and asthma, provide mechanistic insight, and implicate targeting of the IL33 pathway specifically in eosinophilic asthma.

• Authors: Maria E Ketelaar, Michael A Portelli, F Nicole Dijk, Nick Shrine, Alen Faiz, Cornelis J Vermeulen, Cheng J Xu, Jenny Hankinson, Sangita Bhaker, Amanda P Henry, Charlote K Billington, Dominick E Shaw, Simon R Johnson, Andrew V Benest, Vincent Pang, David O Bates, Z E K Pogson, Andrew Fogarty, Tricia M McKeever, Amisha Singapuri, Liam G Heaney, Adel H Mansur, Rekha Chaudhuri, Neil C Thomson, John W Holloway, Gabrielle A Lockett, Peter H Howarth, Robert Niven, Angela Simpson, Martin D Tobin, Ian P Hall, Louise V Wain, John D Blakey, Christopher E Brightling, Ma'en Obeidat, Don D Sin, David C Nickle, Yohan Bossé, Judith M Vonk, Maarten van den Berge, Gerard H Koppelman, Ian Sayers, Martijn C Nawijn
• Journal: The Journal of allergy and clinical immunology (J Allergy Clin Immunol) Vol. 147 Issue 1 Pg. 144-157 (01 2021) ISSN: 1097-6825 [Electronic] United States
• PMID: 32442646 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: Crown Copyright © 2020. Published by Elsevier Inc. All rights reserved.

Chemical References

• IL33 protein, human
• Interleukin-33

Topics

• Adult
• Asthma (genetics, immunology)
• Female
• Gene Expression Regulation (immunology)
• Genetic Predisposition to Disease
• Genome-Wide Association Study
• Humans
• Interleukin-33 (genetics, immunology)
• Male
• Middle Aged
• Polymorphism, Single Nucleotide