A critical role for c-Myc in group 2 innate lymphoid cell activation.

Background: Asthma is a complicated chronic inflammatory disorder characterized by airway inflammation and bronchial hyperresponsiveness. Group 2 innate lymphoid cells (ILC2) are tissue-resident innate effector cells that can mediate airway inflammation and hyperresponsiveness through production of IL-5, IL-13 and VEGFA. ILC2 in asthma patients exhibit an activated phenotype. However, molecular pathways that control ILC2 activation are not well understood.

Methods: MYC expression was examined in ILC2 sorted from peripheral blood of healthy controls and asthma patients or cultured with or without activating cytokines. CRISPR knockout technique was used to delete c-Myc in primary murine lung ILC2 or an ILC2 cell line. Cell proliferation was examined, gene expression pattern was profiled by genome-wide microarray analysis, and direct gene targets were identified by Chromatin immunoprecipitation (ChIP). ILC2 responses, airway inflammation and airway hyperresponsiveness were examined in Balb/c mice challenged with Alternaria extracts, with or without treatment with JQ1.

Results: ILC2 from asthma patients expressed increased amounts of MYC. Deletion of c-Myc in ILC2 results in reduced proliferation, decreased cytokine production, and reduced expression of many lymphocyte activation genes. ChIP identified Stat6 as a direct gene target of c-Myc in ILC2. In vivo inhibition of c-Myc by JQ1 treatment repressed ILC2 activity and suppressed Alternaria-induced airway inflammation and AHR.

Conclusion: c-Myc expression is upregulated during ILC2 activation. c-Myc is essential for ILC2 activation and their in vivo pathogenic effects. These findings suggest that targeting c-Myc may unlock novel strategies to combat asthma or asthma exacerbation.