What is the clinical evidence from this study?

Study design: Other. Population: Pulmonary arterial hypertension. Intervention: Genetic depletion of macrophages. Primary outcome: Pulmonary vascular remodeling and PAH severity.

What question did this study set out to answer?

This research aims to explore the role of macrophage dysfunction in pulmonary arterial hypertension (PAH) and its contribution to pulmonary vascular remodeling.

May 20, 2026

D106-06 Single-Cell Transcriptomics Identified the Critic Role of Malignant Macrophages in Controlling Vascular Remodeling and Pulmonary Arterial Hypertension

Key Result

Genetic depletion of proliferating macrophages markedly inhibited obliterative pulmonary vascular remodeling and pulmonary arterial hypertension, and promoted survival in a mouse model.

Key Points

This research aims to explore the role of macrophage dysfunction in pulmonary arterial hypertension (PAH) and its contribution to pulmonary vascular remodeling.
Utilized single-cell RNA sequencing to analyze lung cellular changes in Egln1Tie2Cre mice.
Generated CKO/Dep transgene mouse model for targeted depletion of proliferating macrophages.
Measured right ventricular systolic pressure (RVSP) and assessed pulmonary vascular remodeling using Russell-Movat staining.
Genetic depletion of total macrophages reduced PAH severity and improved survival rates in CKO mice.
Identification of a proliferating macrophage subpopulation with malignancy traits in Egln1Tie2Cre mice lungs and PAH patients.
Depletion of proliferating macrophages significantly inhibited pulmonary vascular remodeling and improved survival outcomes.

Structured PICO

Population

Egln1Tie2Cre (CKO) mice (a model of pulmonary arterial hypertension with progressive obliterative vascular remodeling and right heart failure) and lung tissue from idiopathic PAH (IPAH) patients

Intervention

Genetic depletion of total macrophages (using CKO/MaFIA transgenic mice) or specific depletion of Ccnb1+ proliferating macrophages (using CKO/Dep transgene mice receiving tamoxifen and diphtheria toxin)

Comparator

Egln1Tie2Cre mice without macrophage depletion

Outcome

Pulmonary vascular remodeling, right ventricular systolic pressure (RVSP), right ventricular hypertrophy (RV/(LV+S) ratio), and survivalsurrogate

Proliferating macrophages with malignant stem cell-like features drive obliterative pulmonary vascular remodeling in PAH, and their targeted depletion attenuates disease and improves survival in a mouse model.

Abstract

Abstract Rationale Previously we identified a mouse model Tie2Cre-mediated disruption of Egln1 of Pulmonary arterial hypertension (PAH) with progressive obliterative vascular remodeling including vascular occlusion and plexiform-like lesions and right heart failure. Tie2Cre-meidated disruption of Egln1 in bone marrow contributes to the severity of PAH indicating the importance of the immune cells in the pathogenesis of PAH. We hypothesized that Macrophage dysfunction contributes to obliterative pulmonary vascular remodeling and severe PAH in Egln1Tie2Cre (CKO) mice. Methods We utilized single-cell RNA sequencing (scRNAseq) to provide transcriptome insights into cellular composition changes in the lungs of Egln1Tie2Cre mice. Egln1Tie2Cre mice bred with the macrophage Fas-induced apoptosis (MaFIA) transgenic mice (CKO/MaFIA) were employed for depletion of total macrophages. Egln1Tie2Cre mice with CD68-FlpERT2/Ccnb1-frt-stop-frt-Dre/Rosa26-rox-stop-rox-DTR (CKO/Dep) transgene were generated and received tamoxifen and diphtheria toxin to deplete the Ccnb1+ proliferating macrophages during the development of PAH. RVSP and RV/(LV+S) ratio were measured. Russell-Movat pentachrome staining was carried out to assess pulmonary vascular remodeling. Results Genetic depletion of total macrophages attenuated PAH and promoted survival of CKO mice. Single cell RNA sequencing and FACS analyses identified marked accumulation of the Adgre+/Chil3+/Cx3cr1+/Ccnb1+ proliferating macrophages (pM) subpopulation in Egln1Tie2Cre mouse lungs. pMs were accumulated in the pulmonary vessel adventitia of idiopathic PAH (IPAH) patients as well as Egln1Tie2Cre mice and exhibit malignant stem cell-like transcriptomic features. Moreover, genetic depletion of pMs using the novel generated CKO/Dep transgene mouse model markedly inhibited obliterative pulmonary vascular remodeling and PAH and promoted survival. By mapping transcriptionally similar cells along a putative differentiation trajectory, we discovered that the pM may give rise to both the accumulated alveolar macrophages (AM) which contribute to vascular remodeling by matrix metalloproteinase activities. Conclusions Endothelial SDF1 induced accumulation of Adgre+/Chil3+/Cx3cr1+/Ccnb1+ pMs in the adventitia of pulmonary vascular lesions of Egln1Tie2Cre mice and IPAH patients, which contributed to severe PAH though the accumulation of AMs. Thus, targeting abnormal macrophage function and signaling pathways is a potential effective therapeutic strategy for treatment of PAH patients and promotion survival. This abstract is funded by: NHLBI

Bookmark