Gene signature profiles in lung tissues of wild type mice or Has2 heterozygous deficient mice stimulated chronically with ovalbumin

Background: HAS2 is a member of the gene family encoding hyaluronan synthase 2 (HAS2), which can generate high-molecular-weight hyaluronan (HMW-HA). Our previous study identified HAS2 as a candidate gene for susceptibility to adult asthma. However, little is known if HAS2 dysfunction affects airway remodeling and steroid insensivity. In this study, we clarified the dysfunction of Has2 triggering severe airway remodeling and steroid insensitivity in a murine model of asthma. Methods: Ovalbumin (OVA) was used to induce eosinophilic airway inflammation and airway remodeling in Has2 heterozygous deficient (Has2+/-) mice and their wild-type (WT) littermates. Lung tissue histology, bronchoalveolar lavage fluid cell counting, quantitative PCR, HA size analysis, multiplex cytokines and chemokines analysis, RNA sequencing, anti IL-17 neutralization experiment were performed. Results: After chronic OVA stimulation, Has2+/- (Has2+/--OVA) mice showed significant decrease of Has2 mRNA expression levels, HMW-HA, HA-binding protein, and TGF-ß. Has2+/--OVA mice demonstrated increased eosinophilic airway inflammation, goblet cell hyperplasia, and IL-17 levels. RNA sequencing demonstrated downregulation of EIF2 signaling pathways, TGF-ß signaling pathways, and heat shock proteins with Th17 bias in Has2+/--OVA mice. Combined treatment with anti IL-17 antibody and dexamethasone reduce steroid insensitivity in Has2+/--OVA mice Conclusions: Has2 attenuation worsen eosinophilic airway inflammation, airway remodeling, and steroid insensitivity. This severe intractable phenotype might be induced by impairment of TGF-ß signaling and ER stress response related signaling. These data highlight that HAS2 and HMW-HA are important for controlling intractable eosinophilic airway inflammation and remodeling, and could potentially be exploited for therapeutic benefit to asthma patients. Overall design: 19 strand-specific RNA libraries for high-throughput sequencing were prepared (5 from the lungs of the wild type mice treated with saline, 4 from the lungs of the Has2+/- mice treated with saline, 5 from the lungs of the wild type mice sensitized and interanasaly stimulated with ovalbumin, and 5 from the lungs of the Has2+/- mice stimulated with ovalbumin using the Illumina Stranded mRNA Sample Preparation Kit with 500ng of total RNA according to manufacturer's instructions.