RNA-containing exosomes in human nasal secretions.

• BACKGROUND: Exosomes are nanovesicles of endocytic origin released by cells and present in human body fluids such as plasma, breast milk, andbronchoalveolar lavage fluid. These vesicles take part in communication between cells. Recently, it was shown that exosomes contain both mRNA andmicroRNA. This RNA can be shuttled between cells (exosomal shuttle RNA), which is a new route of communication between cells. The aim of this study wasto determine whether nasal secretions harbor exosomes and furthermore, whether these exosomes contain RNA.METHODS: Human nasal lavage fluid (NLF) underwent centrifugation and filtration to discard cells and debris, followed by a final ultracentrifugation at 120,000 X g to pellet the exosomes. Exosomes were detected using electron microscopy (EM), flow cytometry, and Western blot. RNA was extracted and analyzed using a Bioanalyzer.RESULTS: Exosomes were visualized as 40-80 nm, CD63+ vesicles using EM. Flow cytometry of exosomes using anti-major histocompatibility complex classII beads revealed exosomes positive for the tetraspanins CD9, CD63, and CD81. Western blot confirmed the presence of exosomal protein and absence ofproteins from the endoplasmic reticulum (ER), because the exosomes were positive for Tsg101, but negative for the ER marker, calnexin. Bioanalyzer analysis revealed that, these exosomes contain RNA.CONCLUSION: This study shows for the first time that NLF contains exosomes and that these exosomes contain RNA. Further characterization of the exosomalRNA and proteins may provide important information about communication in the nose and potentially provide a source of biomarkers for upper airwaydiseases.

Ämnesord

MEDICIN OCH HÄLSOVETENSKAP  -- Medicinska och farmaceutiska grundvetenskaper -- Immunologi inom det medicinska området (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Basic Medicine -- Immunology in the medical area (hsv//eng)

Nyckelord

CD9; CD63; CD81; electron microscopy; exosomal shuttle RNA; exosomes; nasal lavage fluid; nasal secretions; Tsg101; vesicles

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