Plasma Extracellular Vesicles from Bronchopulmonary Dysplasia Infants Initiate Inflammation and Abnormal Angiogenesis in Neonatal Murine Retinas.

To investigate the mechanisms by which plasma extracellular vesicles (EVs) from preterm infants with bronchopulmonary dysplasia (BPD) elicit inflammation and abnormal angiogenesis in neonatal mouse retinas. EVs from the plasma of 7-day-old preterm infants, born between 230/7 and 296/7 weeks of gestation, with BPD or without BPD (nBPD) at 36 weeks postmenstrual ages, were adoptively transferred into postnatal day 3 (P3) mice via intravenous retro-orbital sinus injection. Inflammation and pathological neovascularization in neonatal mouse retinas were examined by immunohistochemistry of retinal flat mounts for Allograft Inflammatory Factor 1 (AIF1), CD206, or Glial Fibrillary Acidic Protein (GFAP) and isolectin-B4 (IB4) staining on P17. Retinal inflammation-related transcripts were assessed by qRT-PCR. Proteomic profiles of BPD and nBPD EVs were examined by Liquid Chromatograph Mass Spectrometer/Mass Spectrometer (LC-MS/MS) and Gene Set Enrichment Analysis (GSEA). Adoptively transferred EVs from BPD and nBPD infants crossed the blood-retinal barrier (BRB) in recipient mouse pups. BPD-EVs increased retinal activated microglia, Müller cells, and twisted proliferative neovascularization compared to nBPD-EVs. BPD-EVs also elevated retinal transcripts regulating inflammation and angiogenesis, including NOD-, LRR- and pyrin domain-containing protein 3 (Nlrp3), Apoptosis-associated speck-like protein containing a caspase recruitment domain (Asc), Caspase 3 (Casp3), Caspase 8 (Casp8), Gasdermin D (Gsdmd), Il1β, Il6, Aif1, and Vascular endothelial growth factor (Vegf). Proteomics analysis revealed that BPD-EVs had significantly elevated levels of inflammation and angiogenesis-related proteins compared to nBPD-EVs. BPD-EVs promote inflammation and abnormal neovascularization by upregulating genes related to apoptosis and inflammation in neonatal mouse retinas. EV protein profiles suggest that elevated levels of proteins such as Defensin alpha 1B (DEFA1B), Insulin-like growth factor binding protein 2 (IGFBP2), CD5 antigen-like (CD5L), von Willebrand factor (vWF), and Tenascin C (TNC) in BPD-EVs may contribute to the observed inflammation and angiogenesis.