Abstract Rationale Asthma is a chronic heterogenous disease of the airways for which there is no cure. The development of biologic medications targeting type 2 (T2) inflammation have significantly reduced oral corticosteroid use and asthma exacerbations yet some studies suggest up to 50% of patients with severe asthma (SA) remain uncontrolled despite the administration of high dose inhaled corticosteroids and controller medications. Historically, asthma has been associated with airway T2 inflammation yet more recent work suggests a role for a concomitant type 1 (T1) inflammatory response in the pathogenesis of SA. In prior studies, we and others demonstrated that concomitant airway T1 inflammation, including pathogenic T1-skewed T cell subsets, are associated with SA. However, it remains unclear what adaptive immune mechanisms may be contributing to persistent airway pathobiology in patients with T2 inflammation who remain uncontrolled despite maximal medical therapy. Methods BAL fluid cells were collected from healthy controls (n = 3) or patients with mild to moderate asthma (MMA) (n = 6) or SA (n = 10). Eligible asthmatic patients were 18 to 65 with either MMA or SA and symptoms that were not well-controlled with medium-dose to high-dose inhaled glucocorticoids plus long-acting beta agonists. Asthma was deemed to be not well-controlled based on international guidelines. Cryopreserved BAL cell suspensions were thawed, subjected to CD3 immunomagnetic cell separation to enrich for T cells, and were subjected to cellular indexing of transcriptomes and epitopes by sequencing (CITE-seq) per manufacturer protocol using a custom antibody-derived tag cocktail designed to interrogate T cell surface markers of interest. Results In total, 37,436 high-confidence T cells were isolated from 19 donors in the “T enriched” population. Unsupervised (weighted nearest neighbor) clustering revealed 11 distinct T cell clusters including cells which transcriptionally (TNF and IFNG gene expression) and by surface protein expression resembled T1-skewed populations. Clusters 2 (CD8+ effector memory T cell re-expressing CD45RA) and 9 (CD8+ resident memory T cell) were more prevalent in patients with SA and differentially upregulated genes related to activation, cytotoxicity, and recent costimulation. Conclusions Subsets of patients with SA with uncontrolled disease despite maximal therapy have T1-skewed T cell populations which are more prevalent than in uncontrolled patients with MMA. Further work is needed to investigate the molecular pathways driving a T1 phenotype, investigate the contribution of quiescence or senescence, and evaluate in silico interactions with other cell types. This abstract is funded by: This work was supported by National Institutes of Health grants P01AI106684-06A1 (AR, SEW and WC), R35HL166219 (AR), K08HL164887-01A1 (MCG), a Parker B. Francis Fellowship Grant (RPR), a Competitive Medical Research Fund (RPR), and an ATS Unrestricted Grant (RPR).
Ramonell et al. (2026) studied this question.