CXCR6 as a novel therapeutic target in allergic asthma.

BACKGROUND

C-X-C motif chemokine receptor 6 (CXCR6) has emerged as a key marker selectively expressed on pathogenic CD4+ T cells involved in various inflammatory and immune-mediated disorders. However, its expression and functional significance in CD4+ T lymphocytes-known to play a pivotal role in the pathogenesis of allergic asthma-remain poorly understood. To address this gap, we investigated the potential role of CXCR6 as a novel therapeutic target in allergic asthma.

METHODS

An ovalbumin (OVA)-induced allergic asthma mouse model was established, along with in vitro differentiation of T-helper cell subsets. Multiparametric flow cytometry, RT-qPCR, and Western blotting were employed to characterize CXCR6 expression across specific cell types and tissues. CXCR6+CD4+ and CXCR6-CD4+ T cells infiltrating the lung were isolated and subjected to RNA sequencing for differential gene expression analysis. Additionally, an anti-CXCR6 monoclonal antibody was administered to selectively deplete CXCR6+ cells and assess the functional consequences of CXCR6 inhibition in allergic asthma. Key differentially expressed genes (DEGs) were further validated by RT-qPCR in lung tissue.

RESULTS

CXCR6+CD4+ T cells were significantly enriched in the lungs of OVA-induced asthmatic mice and exhibited heightened secretion of intracellular cytokines IL-17 and IFN-γ, alongside increased CXCR6 and CXCL16 protein expression. In vitro polarization studies demonstrated that CXCR6 expression was selectively elevated in Th1 and Th17 cells, but not in Th2 or regulatory T (Treg) cells. RNA sequencing identified 1574 DEGs between CXCR6+ and CXCR6- CD4+ T cells, with enrichment in pathways related to chemokine signaling, Th17 cell differentiation, Th1/Th2 polarization, and asthma pathogenesis. Treatment with the anti-CXCR6 antibody effectively depleted CXCR6+CD4+ T cells and significantly downregulated CXCR6 and CXCL16 protein levels in the lungs of asthmatic mice. Notably, this intervention markedly attenuated airway inflammation, mucus hypersecretion, serum anti-OVA IgE levels, and concentrations of IL-17 A, IFN-γ, and inflammatory infiltrates in lung tissue. Furthermore, key signature genes associated with pathogenic Th17 (Il17a, Il17f, Il22, Il23), Th1 (Il1b), and Th2 (Il4, Il13) responses were substantially reduced following CXCR6 antibody treatment.

CONCLUSION

Our findings demonstrate that CXCR6+CD4+ T cells are highly enriched in the lungs of OVA-induced allergic asthmatic mice and are strongly associated with pulmonary inflammation. Targeting CXCR6 represents a promising immunotherapeutic strategy for mitigating allergic asthma.