Mucin 5AC is significantly upregulated in exosomes from the nasal lavage fluid and may promote the expression of COX-2, VEGF and MMP-9: an implication in nasal polyp pathogenesis

Abstract

BACKGROUND: Exosomes are critical mediators of intercellular communication and could be involved in many human diseases; however, little is known about the role of exosomes in nasal polyps (NP). METHODS: Exosomes in nasal lavage fluids (NLF) were isolated by ultracentrifugation. Exosome identity was validated by nanoparticle tracking analysis (NTA), transmission electron microscopy (TEM) and specific exosomal markers. The exosome proteome was revealed by LC-MS/MS, and the expression of the candidate exosomal protein, mucin 5AC, was confirmed by Western blot analysis and immunohistochemistry (IHC). Cellular uptake of the exosomes was monitored by fluorescence confocal microscopy and the ensuing effects on COX-2, VEGF and MMP-2/MMP-9 were determined by Western blotting, ELISA and gelatin zymography, respectively. RESULTS: Mass spectrometry analysis and subsequent verification by Western blotting identified that mucin 5AC was significantly upregulated in exosomes from NLFs of NP patients. Moreover, the expression of mucin 5AC was increased in the tissue specimens of the NP patients. Functional assays suggest that the mucin 5 AC-enriched exosomes could be effectively taken up by chronic rhinosinusitis without NP (CRSsNP)-derived fibroblasts, the control cells, resulting in a significant increase in the expression of COX-2, VEGF and MMP-9. CONCLUSIONS: Mucin 5AC, the major airway mucin, cannot only be carried and transferred by nasal exosomes, but may also promote tissue remodeling and angiogenesis and thus could be a potential therapeutic target of NP.