LncRNA MEG3 ameliorates respiratory syncytial virus infection by suppressing TLR4 signaling

Maternally expressed gene 3 (MEG3), a long noncoding RNA (lncRNA) has been dysregulated in various tumors. However, the expression level and functional role of MEG3 in the progression of respiratory syncytial virus (RSV) infection remains to be elucidated. The present study quantified the expression level of MEG3 in the nasopharyngeal (NPA) samples of RSV-infected patients and in BEAS-2B cells infected with RSV. The findings of the present study demonstrated that the expression level of lncRNA MEG3 was reduced in the NPA samples of RSV-infected patients and in BEAS-2B cells infected with RSV. In vitro transfection revealed increased mRNA expression levels of toll-like receptor 4 (TLR4), tumor necrosis factor- (TNF) and interleukin (IL)-8 following RSV infection in BEAS-2B cells. Additionally, ectopic expression of MEG3 reduced the expression level of TLR4, subsequently suppressing the mRNA expression levels of TNF and IL-8, indicating the protective role of MEG3 in the process of RSV infection. It is of note, that RSV infection-induced p38 mitogen activated protein kinase (MAPK) and nuclear factor-B (NF-B) activation was partly abolished by overexpression of MEG3. In conclusion, to the best of our knowledge, the present study provided the first evidence that lncRNA MEG3 expression level was reduced in the NPA samples of patients with RSV infection and RSV-infected cells. Additionally, it was demonstrated that MEG3 protected human airway epithelial cells from RSV infection, primarily by suppressing TLR4-dependent p38 MAPK and NF-B signaling.