Prostaglandin D₂ receptor 2 downstream signaling and modulation of type 2 innate lymphoid cells from patients with asthma

by Christina Gress, Maximilian Fuchs, Saskia Carstensen-Aurèche, Meike Müller, Jens M. Hohlfeld

Increased production of Prostaglandin D₂ (PGD₂) is linked to development and progression of asthma and allergy. PGD₂ is rapidly degraded to its metabolites, which initiate type 2 innate lymphoid cells (ILC2) migration and IL-5/IL-13 cytokine secretion in a PGD₂ receptor 2 (DP₂)-dependent manner. Blockade of DP₂ has shown therapeutic benefit in subsets of asthma patients. Cellular mechanisms of ILC2 activity in response to PGD₂ and its metabolites are still unclear. We hypothesized that ILC2 respond non-uniformly to PGD₂ metabolites. ILC2s were isolated from peripheral blood of patients with atopic asthma. ILC2s were stimulated with PGD₂ and four PGD₂ metabolites (Δ¹²-PGJ₂, Δ¹²-PGD₂, 15-deoxyΔ^12,14-PGD₂, 9α,11β-PGF₂) with or without the selective DP₂ antagonist fevipiprant. Total RNA was sequenced, and differentially expressed genes (DEG) were identified by DeSeq2. Differential gene expression analysis revealed an upregulation of pro-inflammatory DEGs in ILC2s stimulated with PGD₂ (14 DEGs), Δ¹²-PGD₂ (27 DEGs), 15-deoxyΔ^12,14-PGD₂ (56 DEGs) and Δ¹²-PGJ₂ (136 DEGs), but not with 9α,11β-PGF₂. Common upregulated DEGs were i.e. ARG2, SLC43A2, LAYN, IGFLR1, or EPHX2. Inhibition of DP₂ via fevipiprant mainly resulted in downregulation of pro-inflammatory genes such as DUSP4, SPRED2, DUSP6, ETV1, ASB2, CD38, ADGRG1, DDIT4, TRPM2, or CD69. DEGs were related to migration and various immune response-relevant pathways such as “chemokine (C-C motif) ligand 4 production”, “cell migration”, “interleukin-13 production”, “regulation of receptor signaling pathway via JAK-STAT”, or “lymphocyte apoptotic process”, underlining the pro-inflammatory effects of PGD₂ metabolite-induced immune responses in ILC2s as well as the anti-inflammatory effects of DP₂ inhibition via fevipiprant. Furthermore, PGD₂ and metabolites showed distinct profiles in ILC2 activation. Overall, these results expand our understanding of DP₂ initiated ILC2 activity.