D3.140 - Transcriptomic profiling reveals distinct gene signatures and immune pathways in inhaled corticosteroid (ICS)-sensitive and resistant House Dust Mite (HDM)-induced asthma mouse models

Asthma is a chronic, heterogeneous inflammatory airway disease affecting 300 million people worldwide, characterised by distinct phenotypes broadly classified as Type 2 (T2) high and T2 low.

Well-characterizing preclinical models that mimic the mechanisms of the disease are crucial to understand the complex processes driving the disorder and provide translational models to evaluate new therapeutic strategies.

RNA-seq provides a comprehensive overview of inflammation-associated transcriptional changes, shedding light on molecular mechanisms driving asthma.

This study aimed to detect transcriptional alterations in two HDM-induced mouse models reproducing different asthma phenotypes to investigate molecular mechanisms and discover new potential targets.

The two HDM-induced models were established using Alum or Complete Freund’s Adjuvant (CFA) to reproduce, ICS-sensitive T2-high and ICS-resistant mixed T2/non-T2 phenotype, respectively. Budesonide was used as reference compound. Inflammatory cell count was evaluated on BALF. RNA-Seq was performed in lung tissue and pathway analysis was conducted on differentially expressed genes (FDR<0.05 and |log2FC|>1).

In the HDM/Alum model, HDM exposure markedly increased BALF inflammatory cell recruitment, with eosinophils representing the dominant population (p<0.001 saline vs HDM), while the HDM/CFA model showed elevated neutrophils alongside eosinophils (p<0.05 at least saline vs HDM). As expected, treatment with budesonide significantly reduced eosinophil counts in the ICS-sensitive model (p<0.001). Budesonide did not impact inflammatory cell levels in HDM/CFA treated mice, confirming the reduced responsiveness to ICS.

RNA-Seq analysis highlighted transcriptional differences between the two preclinical models. HDM/Alum mice showed enrichment of immune-related pathways associated with eosinophil recruitment, T2 responses, airway remodelling and hyperresponsiveness (i.e. Il4, Il5, Ccr3, Mmp12, Arg1, Chil3), many of which are reversed by budesonide. HDM/CFA model shared some of these T2 genes, but they were not affected by steroid treatment. Moreover, HDM/CFA mice displayed T1/T17 activation and neutrophilic signatures (i.e. Il1β, Il17f, Ifnγ, Oas3, S100a9, Csf3), and also these genes remained unaffected by ICS.

Our data confirmed that the two models can mimic different asthma phenotypes, providing valid tools to study disease mechanisms and to support the identification of new strategies to treat T2-high and non-T2 asthma.