Characterizing Non-T2 Asthma: Key Pathways and Molecular Implications Indicative of Attenuated Th2 Response

Non-Type 2 (non-T2) asthma is characterized by a lack of allergic sensitization and normal to low total IgE levels. We aimed to explore molecular mechanisms and pathways differentiating non-T2 from T2-high pediatric asthma. We analyzed peripheral blood RNA samples from 11 non-T2 and 17 T2-high pediatric asthma patients using bulk RNA sequencing. Differentially expressed genes (DEGs) were identified, followed by Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses, and Protein-Protein Interaction (PPI) network construction. Gene Set Enrichment Analysis (GSEA) and Ingenuity Pathway Analysis (IPA) were employed to explore significance of these DEGs. We utilized independent public datasets GSE145505 to validate our findings. We investigated Th cytokine profiles in an independent cohort of pediatric patients with non-T2 asthma (n = 38) and T2-high asthma (n = 64). We demonstrated that the total serum IgE levels of children with non-T2 asthma (128.4 ± 159.5 IU/mL) was significantly lower than that of those with T2-high asthma (405.8 ± 252.1 IU/mL). Our analysis revealed 136 DEGs distinguishing non-T2 from T2-high asthma. IPA identified predicted inhibition of IgE-FcεRI signaling pathways in non-T2 asthma. Our DEG data showed the expression of IGHV4-39, IGLV1-40, IGLV1-47, IGLV1-44, IGHV1-69, IGLV6-57, IGLV3-19, IGLV3-1, and IGLC7 were downregulated in our non-T2 asthma patient. The non-T2 group exhibited significantly higher concentrations of IL-2, IFN-γ, IL-6, and IL-17A compared to the T2-high group. Our integrated analysis differentiated non-T2 from T2-high asthma by revealing downregulation of specific immunoglobulin genes influencing FcεRI signaling, elevated Th1 cytokines and Th17 cytokines might affect IgE associated sensitization and alter Th2 allergic response.