D3.130 - PGI2 Signaling Attenuates the Proliferation and Type 2 Cytokine Production of Group 2 Innate Lymphoid Cells

Group 2 innate lymphoid cells (ILC2s) are pivotal mediators in the pathogenesis of eosinophilic asthma, primarily through the robust production of type 2 cytokines such as IL-5 and IL-13. Prostacyclin (PGI₂), a potent lipid mediator, is recognized for its vasodilation and anti-inflammatory properties, largely mediated via the IP receptor. While emerging evidence suggests that PGI₂ signaling regulates innate immunity, its specific regulatory role in ILC2-mediated responses remains to be fully elucidated. This study aimed to investigate the inhibitory effects of the PGI₂ analog, iloprost, on ILC2 proliferation and effector functions, and to explore the underlying molecular mechanisms.

Primary murine lung ILC2s were sorted from IL-33-stimulated mice and expanded in vitro with IL-2 and IL-7. To evaluate the regulatory role of PGI₂ signaling, ILC2s were treated with varying concentrations of iloprost after stimulation with IL-33. Cell proliferation was assessed using Ki-67 staining or CCK-8 assays, while cytokine production (IL-5 and IL-13) was quantified by ELISA and intracellular staining. The involvement of the IP receptor was verified using the antagonist, CAY10441. Furthermore, the transcriptomic profile of iloprost-treated ILC2s was analyzed using bulk RNA sequencing and Gene Set Enrichment Analysis (GSEA).

Iloprost significantly suppressed ILC2 proliferation in a dose-dependent manner and markedly reduced the production of type 2 cytokines, particularly IL-13. Mechanistically, these inhibitory effects were partially reversed by the IP receptor antagonist CAY10441, confirming the involvement of iloprost-IP signaling axis. Notably, GSEA showed significant enrichment of gene sets associated with the negative regulation of immune response, the TGF-β signaling pathway, and the reactive oxygen species metabolism in iloprost-treated ILC2s. These transcriptomic findings suggest that iloprost exerts its regulatory influence through multiple inhibitory signaling pathways.

Our findings demonstrate that iloprost effectively inhibits the proliferation and functional activation of ILC2s in vitro. These results highlight the potential of targeting the PGI₂-IP axis as a novel pharmacological strategy to attenuate ILC2-driven airway inflammation and airway hyperresponsiveness.