D106-20 Subset-specific Dendritic Cell Activation Reveals a Pathogenic Role for Cd301b+ Cdc2s in Pulmonary Hypertension

Abstract Rationale Pulmonary hypertension (PH) is a progressive vascular disease in which inflammation plays a central pathogenic role. Dendritic cells (DCs), potent antigen-presenting cells resident in the lung, have been implicated in vascular remodeling, but their specific contribution to hypoxia-induced PH remains undefined. We investigated how hypoxia reprograms lung classical DC subsets—cDC1s and cDC2s—and how these subsets drive PH pathogenesis. Methods We performed single-cell RNA sequencing (scRNA-seq) of lung DCs from Zbtb46GFP mice exposed to normoxia (NMX) or hypoxia (HYX, 10% O2, 7 days). Differentially expressed genes were analyzed within cDC1 and cDC2 subsets, identifying IFN-responsive, migratory, tolerogenic, monocyte-like, proliferative, and homeostatic populations. Functional relevance was assessed in CD301b-DTR mice (depletion of CD301b+ cDC2s) and Batf3−/− mice (lacking cDC1s) subjected to hypoxia. In vitro hypoxia assays with isolated lung cDCs evaluated cell-intrinsic activation. Results scRNA-seq revealed that hypoxia induces robust activation of cDC2 subsets, whereas cDC1s remain largely regulatory. • cDC2 activation: Monocyte-like cDC2s upregulated Il1b, Tnf, Ccl3/4, and Ptgs2, indicating strong NF-κB-driven inflammation. Migratory cDC2s increased Cd83, Cd40, Ccr7, and AP-1 components (Fos, Junb), consistent with T cell priming and lymph node trafficking. Proliferative cDC2s enriched for mitotic genes (Mki67, Cdk1), suggesting hypoxia-driven expansion. • cDC1 response: IFN-responsive cDC1s upregulated Ifit3, Irf7, and Stat1, whereas tolerogenic cDC1s expressed Il10ra, Pdcd1lg2, and Socs2, reflecting limited activation. Functionally, depletion of CD301b+ cDC2s protected mice from hypoxia-induced PH, whereas Batf3−/− mice developed disease similar to wild-type controls. Isolated lung cDCs cultured under hypoxia in vitro showed minimal activation, suggesting that extrinsic lung cues are required for cDC reprogramming in vivo. Conclusions Our findings identify CD301b+ cDC2s as key immunologic effectors that mediate hypoxia-induced pulmonary hypertension through subset-specific inflammatory and migratory programs, whereas Batf3-dependent cDC1s are dispensable. These results uncover a previously unrecognized DC-driven mechanism of vascular remodeling and position CD301b+ cDC2s as potential therapeutic targets in hypoxia-associated PH. This abstract is funded by: NHLBI