Integrated analysis reveals that EGR1 promotes epithelial IL33 production in T2 asthma.

Background: Airway epithelial cells constitute the first line of defense against external noxious stimuli and play crucial roles in the release of epithelial inflammatory cytokines (IL33, IL25 and TSLP), initiating airway allergic inflammatory diseases such as asthma. IL33 plays critical physiological processes in T2-endotype asthma. However, the mechanisms by which allergen exposure triggers IL33 release from airway epithelial cells remain unclear.

Methods: Integrated bioinformatic analysis and transcriptional analysis of bulk RNA-seq and single cell RNA-seq (scRNA-seq) data were used to identify core genes and determine the internal gene network associated with IL33. The expression of EGR1 was subsequently analyzed in vitro in the BEAS-2B cell line and in vivo in a house dust mite (HDM)-induced mouse asthma model. The functional experiments of EGR1 were investigated in vitro via siRNA knockdown and over-expressed plasmid. Chromatin immunoprecipitation (ChIP)-PCR and dual-luciferase reporter assay validation were subsequently performed to investigate the mechanisms by which EGR1 regulates IL33 secretion.

Results: Bulk RNA-seq and scRNA-seq data identified EGR1 as an epithelial cell-derived gene implicated in IL33 expressions in asthma. The comprehensive analysis of multiple datasets indicated that the high EGR1 expression in epithelial cells may suggest a mechanistic basis of T2-endotype childhood asthma. Moreover, we verified that the expressions of EGR1 in airway epithelial cells were elevated both in vitro and in vivo asthma models. EGR1 regulated the production of IL33. Ultimately, ChIP and luciferase reporter assays confirmed that transcription factor EGR1 directly regulate the transcription of IL33 mRNA.

Conclusions: Our integrated bioinformatic analysis elucidated that EGR1 directly regulates the production of IL33 in T2-asthma and provide insights underlying the progression of asthma.