IdeNtifying reSponse defIninG mecHanisms for biological TherapieS in SevereAsthma (INSIGHTS ); assessing the role of CD4-CTLs

PROJECT SUMMARY Severe asthma, characterized by persistent airway inflammation and corticosteroid resistance, afflicts millions of Americans with limited therapeutic options. Clinicians currently rely on Type 2 immune biomarkers for patient classification (T2HIGH vs. T2LOW) and treatment decisions. However, real-world studies revealed the over- representation of the T2HIGH endotype in severe asthma and those treated with anti-T2 biologic therapies exhibit contrasting responses, challenging the efficacy of this T2 dichotomy and highlighting the need to explore alternative pathophysiological drivers. Our single-cell transcriptome analysis of T cells from inflamed airways in severe asthmatics identified a novel subset of pathogenic airway tissue resident cytotoxic CD4+ T cells (CD4-CTLs). Despite biologic treatment, CD4- CTLs remained activated, producing inflammatory molecules. Cell proportions analysis linked CD4-CTLs to asthma severity and lung function impairment, particularly in males with late-onset asthma. The study strongly supports CD4-CTLs' significant contribution to airway inflammation, potentially hindering T2-biologic response. Led by a multidisciplinary team of experts in clinical asthma, and immuno-genomics, Drs. Kurukulaaratchy and Seumois, our INSIGHTS study aims to assess the impact of CD4-CTLs on severe asthma pathogenesis and T2- biologics response at a larger scale. AIM 1: We will analyze airway CD4-CTLs from blood and sputum samples collected from 160 severe asthmatic patients before, and 12- and 24- months after initiating T2-biologic therapy. We will evaluate the impact of CD4- CTLs on T2-biologics response through extensive clinical analysis. Samples will be collected by three clinical centers [University of Southampton, UK; University of Michigan, Ann Arbor, US, and University of California, San Diego, US] establishing the clinical significance of CD4-CTL as a new player in asthma pathogenesis. AIM 2: With the planned collection of samples, we will generate up to 1 million single-CD4-CTL cell transcriptomes allowing us to comprehensively decipher the pathogenic cellular and molecular features of CD4- CTLs in asthma severity and response to T2-biologics, as well as investigate their function through TCR- reactivity and interactions with structural cells analysis. In summary, this unique translational proposal aims to unveil mechanisms causing a lack or loss of response to T2-biologics in severe asthma, focusing on CD4-CTLs. Findings could establish CD4-CTLs as a better predictor for patient stratification, leading to novel therapies for unmet patient needs.