Journal
JOURNAL OF ALLERGY AND CLINICAL IMMUNOLOGY
Volume 147, Issue 1, Pages 144-157Publisher
MOSBY-ELSEVIER
DOI: 10.1016/j.jaci.2020.04.051
Keywords
asthma phenotypes; IL33 SNPs; eQTL; bronchial epithelium; functional translation
Categories
Funding
- Lung Foundation Netherlands grants [AF 95.05, AF 98.48, AF3.2.09.081JU]
- University Medical Center Groningen
- Dutch TerMeulen Fund
- Ubbo Emmius Foundation
- GlaxoSmithKline
- Dutch Ministry of Health, Welfare and Sport
- Dutch Ministry of Economic Affairs
- University Groningen
- Northern Provinces of the Netherlands - Asthma UK grant [AUK-PG-2013-188]
- Asthma UK [AUK-PG-2013-188]
- Rosetrees Trust
- AirPROM
- Medical Research Council [G1100163]
- GSK/British Lung Foundation Chair in Respiratory Research
- National Institute for Health Research Leicester Respiratory Biomedical Centre
- MRC [G1100163, MC_PC_12010] Funding Source: UKRI
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The study found that IL33 SNPs are associated with asthma-related phenotypes, with rs992969 being linked to blood eosinophil levels, asthma, and eosinophilic asthma. Additionally, IL33 overexpression experiments revealed potential effects on bronchial epithelial cell function.
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: 5,815,7866,657,983) 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.
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