Background: Recent studies have suggested that eosinophils may have a direct effect on airway smooth muscle\ncells (ASMC), causing their proliferation in patients with asthma, but the precise mechanism of the interaction\nbetween these cells remains unknown. We propose that changes in Wnt signaling activity and extracellular matrix\n(ECM) production may help explain these findings. Therefore, the aim of this study was to investigate the effect of\neosinophils from asthmatic and non-asthmatic subjects on Wnt-5a, transforming growth factor �²1 (TGF-�²1), and\nECM protein (fibronectin and collagen) gene expression and ASMC proliferation.\nMethods: A total of 18 subjects were involved in the study: 8 steroid-free asthma patients and 10 healthy subjects.\nPeripheral blood eosinophils were isolated using centrifugation and magnetic separation. An individual co-culture\nof eosinophils with human ASMC was prepared for each study subject. Adhesion of eosinophils to ASMC (evaluated\nby assaying eosinophil peroxidase activity) was determined following various incubation periods (30, 45, 60, 120,\nand 240 min). The expression of Wnt-5a, TGF-�²1, and ECM protein genes in ASMC was measured using quantitative\nreal-time polymerase chain reaction (PCR) after 24 h of co-culture. Proliferation of ASMC was measured using the\nAlamar blue method after 48 h and 72 h of co-culture with eosinophils.\nResults: Eosinophils from asthmatic subjects demonstrated increased adhesion to ASMC compared with\neosinophils from healthy subjects (p < 0.05) in vitro. The expression of Wnt-5a, TGF-�²1, collagen, and fibronectin\ngenes in ASMC was significantly higher after 24 h of co-culture with eosinophils from asthmatic subjects, while\nco-culture of ASMC with eosinophils from healthy subjects increased only TGF-�²1 and fibronectin gene expression.\nASMC proliferation was augmented after co-culture with eosinophils from asthma patients compared with\nco-culture with eosinophils from healthy subjects (p < 0.05).\nConclusions: Eosinophils enhance Wnt-5a, TGF-�²1, fibronectin, and collagen gene expression in ASMC and\npromote proliferation of these cells in asthma.
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