A Fraction of Escherichia coli Bacteria Induces an Increase in the Secretion of Extracellular Vesicle Polydispersity in Macrophages: Possible Involvement of Secreted EVs in the Diagnosis of COVID-19 with Bacterial Coinfections

Extracellular vesicles (EVs) can transport molecules that combat viruses, such as RNA against SARS-CoV-2. Bacterial coinfections can help establish certain viruses and worsen diseases. Thus, we designed a model to induce the secretion of polydisperse EVs shown with SARS-CoV-2 and bacterial coinfection using macrophages and <i>E. coli</i> fractions as in vitro inducers. We obtained short and large macrophage EVs. The <i>E. coli</i> fraction was designated as SDS-soluble bacterial membrane fraction and its associated proteins (SDS-SBMF). The proteins were identified using a mass spectrometer. SDS-SBMF contained mainly OmpF, OmpA, OmpC, OmpX, and lpp. The SDS-SBMF macrophages induced the secretion of polydisperse EVs at 30 min, reaching optimal secretion at 120 min, as observed via scanning electron microscopy and confocal microscopy. Macrophage EVs contained mainly HSP7C, actin, apolipoprotein, GAPDH, annexin A5, PKM, moesin, and cofilin. We observed an increase in EVs in the bloodstream of patients with SARS-CoV-2 and bacterial coinfection, in addition to the presence of SARS-CoV-2 genes (E, ORF) in EVs. This in vitro method for inducing EVs has the potential to be used to obtain larger samples for study and for the detection of diagnostic and prognostic biomarkers of different diseases.