Lung transplant recipients with severe acute respiratory syndrome-coronavirus 2 infection and asymptomatic carriers waiting for lung transplantation induce circulating exosomes with severe acute respiratory syndrome-coronavirus 2 spike protein s2

Purpose: Exosomes are vesicles released by cells into body fluids. We demonstrated increased circulating exosomes with lung self-antigens (Collagen V, Kα1 Tubulin) and viral antigens in lung transplant recipients (LTxRs) undergoing rejection. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV2), an important risk factor for LTxRs in immunosuppression and patients with diseased lungs waiting for transplantation. Our goal is to determine that exosomes from LTxRs with SARSCoV2 infection carry SARS-CoV2 spike protein. Methods: We analyzed 30 patients waiting for LTx with no clinical symptoms and 7 LTxRs with SARS-CoV2 infection and symptoms. Exosomes were isolated from plasma by precipitation kit, 0.2 micron filtration and size determination by Nanosight300. Eluted protein from gel was analyzed by mass spectrometry and peptides were aligned with SARS-CoV2. Transmission electron microscopy of exosomes was performed for spike and nucleocapsid antigen. Exosomes were also characterized by western blot for immune and molecular markers. Serum cytokines were analyzed using 25 Plex on Luminex. Results: Exosomes from symptomatic (7/7) and 7/30 (23.3%) asymptomatic LTxRs contained SARS-CoV2 spike protein S2 and increased levels of SARS-CoV2 RNA. SARS-CoV2 spike protein in exosomes was confirmed by mass spectroscopy. Transmission electron microscopy from symptomatic and asymptomatic LTxRs revealed spike protein and nucleocapsid antigen on exosomes. Exosomes contained macrophage stimulating factor 1, GRAnzyme B and angiotensin type II receptor 1 proteins. Increased levels of CXCL10 in sera were detected in SARS-CoV2 positive symptomatic patients, agreeing with the reports that CXCL10 levels correlate with disease severity. Conclusions: SARS-CoV2 infected LTxRs symptomatic and asymptomatic induced circulating exosomes having spike protein, nucleic acid and antigens related to viral entry (angiotensin type II receptor), infection (macrophage stimulating factor 1) and cytotoxic molecule (GRAnzyme B) suggesting that the exosomes induced by SARS-CoV2 will have functional consequences. Exosomes also contained increased levels of viral RNA and antigens suggesting that circulating exosomes may provide a noninvasive tool for detection of SARS-CoV2 infection.