Characterization of the heterogeneity of endothelial cells in bleomycin-induced lung fibrosis using single-cell RNA sequencing

Xiucheng Liu,Xiucheng Liu,Xiucheng Liu,Yanliang Yuan,Hao Zhang,Bi Chen,Teng Sun,Caili Jia,Chang Chen,Chang Chen,Hao Qin,Xichun Qin

doi:10.1007/s10456-021-09795-5

Xiucheng Liu, Xiucheng Liu + Show 10 more

Open Access

https://doi.org/10.1007/s10456-021-09795-5

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Abstract

The loss of normal alveolar capillary and deregulated angiogenesis occurs simultaneously in idiopathic pulmonary fibrosis (IPF); however the contributions of specific endothelial subpopulations in the development of pulmonary fibrosis are poorly understood. Herein, we perform single-cell RNA sequencing to characterize the heterogeneity of endothelial cells (ECs) in bleomycin (BLM)-induced lung fibrosis in rats. One subpopulation, characterized by the expression of Nos3 and Cav1, is mostly distributed in non-fibrotic lungs and also highly expresses genes related to the “response to mechanical stimulus” and “lung/heart morphogenesis” processes. Another subpopulation of ECs expanded in BLM-treated lungs, characterized by Cxcl12, is observed to be closely related to the pro-fibrotic process in the transcriptome data, such as “regulation of angiogenesis,” “collagen binding,” and “chemokine activity,” and spatially localized to BLM-induced neovascularization. Using CellPhoneDB software, we generated a complex cell–cell interaction network, which predicts the potential roles of EC subpopulations in recruiting monocytes, inducing the proliferation of fibroblasts and promoting the production and remolding of the extracellular matrix (ECM). Taken together, our data demonstrate the high degree of heterogeneity of ECs in fibrotic lung and it is proposed that the interaction between ECs, macrophages, and stromal cells contributes to pathologic IPF.

Highlights

Idiopathic pulmonary fibrosis (IPF), a common form of interstitial lung disease, is a chronic, debilitating, and progressive lung disease with a poor prognosis [1].Epidemiological studies have revealed that the incidence and prevalence of IPF is increasing worldwide, and this may be a consequence of multiple interacting genetic and environmental risk factors [2]
The results indicated that increased cluster a endothelial cells (ECs) in BLM-treated lungs were enriched for processes associated with lung fibrosis, such as “chemotaxis activity,” “VEGF production,” “collagen binding,” and “extracellular matrix (ECM) constituent.”
Appreciable amounts of lung fibrosis and angiogenesis were observed at day 28 in rats treated with BLM (Supplementary Fig. 1)

Summary

Introduction

Epidemiological studies have revealed that the incidence and prevalence of IPF is increasing worldwide, and this may be a consequence of multiple interacting genetic and environmental risk factors [2]. Previous conventional approaches have failed to detect and quantify the detailed contributions of altered cell types (epithelial cells, myofibroblasts, alveolar macrophages (AMs), endothelial cells (ECs)) in the IPF progression. Single-cell RNA sequencing (scRNA-seq) has shown the potential to overcome the large-scale changes and spatial heterogeneity in cell types and allowed the reliable identification of related cell populations and confirmation of the complex molecular procedures in IPF. Xu and co-workers have profiled the roles of epithelial cells in IPF and identified an additional atypical transitional cell which contributes to the pathological processes [6].

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