Exosomes Released by Influenza-Virus-Infected Cells Carry Factors Capable of Suppressing Immune Defense Genes in Naïve Cells

Abstract

Exosomes are involved in intercellular communication and can transfer regulatory molecules between cells. Consequently, they can participate in host immune response regulation. For the influenza A virus (IAV), there is very limited information on changes in exosome composition during cell infection shedding light on the potential role of these extracellular membrane vesicles. Thus, the aim of our work was to study changes in exosomal composition following IAV infection of cells, as well as to evaluate their effect on uninfected cells. Methods: To characterize changes in the composition of cellular miRNAs and mRNAs of exosomes during IAV infection of A549 cells, NGS was used, as well as PCR to identify viral genes. Naïve A549 cells were stimulated with infected-cell-secreted exosomes for studying their activity. Changes in the expression of genes associated with the cell’s immune response were shown using PCR. The effect of exosomes on IAV replication was shown in MDCK cells using In-Cell ELISA and PCR of the supernatants. Results: A change in the miRNA composition (miR-21-3p, miR-26a-5p, miR-23a-5p, miR-548c-5p) and mRNA composition (RPL13A, MKNK2, TRIB3) of exosomes under the influence of the IAV was shown. Many RNAs were involved in the regulation of the immune response of the cell, mainly by suppressing it. After exosome stimulation of naïve cells, a significant decrease in the expression of genes involved in the immune response was shown (RIG1, IFIT1, MDA5, COX2, NFκB, AnxA1, PKR, IL6, IL18). When infecting MDCK cells, a significant decrease in nucleoprotein levels was observed in the presence of exosomes secreted by mock-infected cells. Viral levels in supernatants also decreased. Conclusions: Exosomes secreted by IAV-infected cells could reduce the immune response of neighboring intact cells, leading to more effective IAV replication. This may be associated both with regulatory functions of cellular miRNAs and mRNAs carried by exosomes, or with the presence of viral mRNAs encoding proteins with an immunosuppressive function.

Resolution pharmacology and the treatment of infectious diseases

“…Inhibition of FPR2 in experimental H1N1 infection decreased the production of IL‐6 and IFN‐ β in BAL fluid, decreased viral titres and decreased lethality rates associated with infection (Tcherniuk et al, 2016). Recent findings indicate that IAV infection stimulates the release of exosomes that down‐regulate several genes involved in the inflammatory response, including the AnxA1 gene (Zabrodskaya et al, 2022). Additionally, in vitro studies have demonstrated that H1N1 infection up‐regulates the expression of FPR2 (Ampomah et al, 2018), likely as a strategy to promote disease progression.…”

Extracellular vesicles and endothelial dysfunction in infectious diseases

“…RNAs: miRNA composition (miR-21-3p, miR-26a-5p, miR-23a-5p, miR-548c-5p) and mRNA composition (RPL13A, MKNK2 and TRIB3) (Zabrodskaya et al, 2022);…”

“…•Suppressing immune defense genes: EVs from IAV-infected cells reduce the immune response of neighbouring intact cells, leading to more effective IAV replication (Zabrodskaya et al, 2022). •Promoting M1 polarization and recruitment of macrophages: EVs from the supernatant of IAV-infected cells promote the recruitment and polarization of peritoneal M1 macrophages .…”

MicroRNAs: Small but Key Players in Viral Infections and Immune Responses to Viral Pathogens

“…For example, miR-mRNA interactions predicted to decrease gene expression by degradation of mRNA should reflect this in both attenuated mRNA transcript levels and reduced protein output [70]. Furthermore, researchers may consider expanding on the local or systemic effects of viral miRNA packaged into exosomes and virus-induced changes in exosomal host miRNA levels [10,83,103]. They should also critically evaluate if changes in host miRNA levels are due to viral manipulation or if they are a potential defensive response to infection.…”