Extracellular vesicles from lung tissue drive bone marrow neutrophil recruitment in inflammation

Abstract

Extracellular vesicles (EVs) are single-membrane vesicles that play an essential role in long-range intercellular communications. EV investigation has been explored largely through cell-culture systems, but it remains unclear how physiological EVs exert homeostatic or pathological functions in vivo. Here, we report that lung EVs promote chemotaxis of neutrophils in bone marrow through delivery of double stranded DNA (dsDNA). We have identified and characterized EVs containing dsDNA collected from both human and murine lung tissues using newly developed approaches. Our analysis of EV proteomics together with single-cell RNA sequencing data reveals that type II alveolar epithelial cells are the main source of the lung EVs. Furthermore, we demonstrate that the lung EVs accumulate in bone marrow and enhance neutrophil recruitment under inflammation conditions. Moreover, lung EV-DNA stimulates neutrophils to release the chemokines CXCL1 and CXCL2 via DNA-TLR9 signalling. Our findings establish a molecular basis of lung EVs in enhancement of host immune response to bacterial infection and provide new insights into understanding of vesicle-mediated systematic communications.

Proteomic Characterization of Peritoneal Extracellular Vesicles in a Mouse Model of Peritoneal Fibrosis

“…Astrocyte-derived EVs were confirmed to play a key role in the pathogenesis of Alzheimer’s disease. In addition, Liu et al used integrative analysis of public scRNA-seq data and their lung EV LC–MS/MS data to identify the cell source of lung EVs . In this study, we used scRNA-seq data from mouse omentum to deconvolute our proteomic data and found that more than half of DEPs in peritoneal EVs were overlapped with the cluster-marker genes and 25.6% of DEPs were markers of mesothelial cells, suggesting that mesothelial cells mainly cause EV molecular alterations.…”

“…For example, integrin subunit beta 1 (ITGB1) protein in brain tissue-derived EVs has been confirmed to participate in the pathogenesis of Alzheimer’s disease . In addition, lung tissue-derived EVs can promote the chemotaxis of neutrophils in bone marrow via transportation of double-stranded DNA . However, reliable techniques for EV isolation from peritoneal tissues are lacking.…”

Bacterial extracellular vesicles: A position paper by the microbial vesicles task force of the Chinese society for extracellular vesicles

“…Differential centrifugation (300 � g for 10 min, 5000 � g for 15 min, 10,000 � g for 30 min) removed cell debris to obtain an extracellular matrix suspension of the tissue, which was stored at −80 °C or directly subjected to ultracentrifugation to separate the EVs. 60,[168][169][170] After the total EVs have been obtained, the BEVs should be further separated and purified using a specific marker or a specific method, which can be characterized in section 4.3.2.…”

“…These tiny vesicles contain biomolecules that can provide valuable information about the bacteria and their host environment, enabling researchers to detect early signs of infection and identify the specific type of bacteria responsible for the illness. 60,61 Furthermore, BEVs not only contain bacterial DNA and RNA but also carry a variety of biomolecules such as lipids, proteins, and metabolites. In contrast, nucleic acid detection primarily focuses on the detection of DNA and RNA.…”

“…Increasing evidence suggests that BEVs have significant potential as diagnostic biomarkers for various bacterial infections. These tiny vesicles contain biomolecules that can provide valuable information about the bacteria and their host environment, enabling researchers to detect early signs of infection and identify the specific type of bacteria responsible for the illness 60,61 . Furthermore, BEVs not only contain bacterial DNA and RNA but also carry a variety of biomolecules such as lipids, proteins, and metabolites.…”