Single-cell RNA-seq analysis of cell-cell communications in human lung reveals a novel role of VEGF-D in acute lung injury
Authors: Yuan Yifan , Sharma Lokesh , Tang Wenwen , Raredon Micha Sam , Ahangari Farida , Khoury Johad , Wu Dianqing (Dan) 
Published: May 2024

BACKGROUND: Vascular disorders are a prominent pathological feature across many pulmonary diseases, such as acute lung injury (ALI) or acute respiratory distress syndrome (ARDS), chronic obstructive pulmonary disease (COPD), idiopathic pulmonary fibrosis (IPF), and COVID-19. Paracrine signals are enriched throughout the lung tissue and are critical in maintaining functional microvascular homeostasis. In this study, we applied comprehensive computational tools to analyze single-cell RNA-seq (scRNAseq) datasets in healthy and diseased lungs and identified a local component in human lung microvascular niche VEGF-D exhibiting barrier protective property in ALI/ARDS animal models. METHODS: Leveraging scRNAseq-based ligand-receptor analysis, we studied the cell-cell crosstalk signals in the human lung microvascular niche among healthy adults and in IPF and COPD individuals. The impact of identified ligands on vascular barrier function and anti-inflammation was further assessed in vitro assays and lipopolysaccharide (LPS)-induced lung injury models. RESULTS: scRNAseq datasets reveal over 24 cell populations in the human lung microvascular niche. We applied Connectome to map the averaged gene expression per cell type to known ligand-receptor interactions cataloged in the NicheNet database. Using microvascular ECs, such as EC Aerocyte and EC General Capillary, as signal receivers (Senders) and the putative adjacent cell types (alveolar fibroblast, ATI, ATII, pericyte, plasma cell, etc.) in the microvascular niche as signal senders (Ligands), we identified several specific and abundant ligand-receptor pairs based on their expression levels in the niche, including SLIT2-ROBO4, ANGPT1-TEK, ADM-RAMP2, VEGFD-VEGFR2, BMP5-BMPR2, etc. Interestingly, these highly produced ligands were significantly reduced in patients with IPF or COPD. Upon treatment with these ligands on human lung endothelial cells, we found that VEGF-D could significantly increase the barrier function, unlike its analogs, VEGF-A and VEGF-C. Additionally, VEGF-D exerts barrier-protective properties against tumor necrosis factor-α, interleukin 1-β, and thrombin challenges. The blockage of VEGFR2 through either siRNA or pharmacological inhibitor SU5614 attenuates the impact of VEGF-D. Furthermore, intravenous administration of VEGF-D significantly reduced vascular permeability and immune cell infiltration in the LPS-induced lung injury model. CONCLUSIONS: This study highlights the cell-cell crosstalk signals in lung microvascular niche between healthy and diseased individuals and determines a novel and potentially therapeutic role of VEGF-D in improving lung vascular integrity during acute lung injury. NIH K99HL159261 (Y.Y.). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.