Acute exacerbation of chronic obstructive pulmonary disease was associated with respiratory syncytial virus infection and the upregulation of TLR3

Respiratory syncytial virus (RSV) infection is known as a risk factor for chronic obstructive pulmonary disease (COPD). RSV infection induces the upregulation of Toll-like receptor 3 (TLR3). This study aimed to investigate the association of TLR3 with RSV induced acute exacerbations of chronic obstructive pulmonary disease (AECOPD). Serum/sputum samples from AECOPD patients, stable chronic obstructive pulmonary disease (SCOPD) patients, and healthy controls were collected. Nested PCR was used to detect RSV. The lung function parameters were assessed by blood gas and lung function analysis. The expression levels of inflammatory factors in sputum and serum samples were determined by enzyme-linked immunosorbent assay. BEAS-2B cell lines were infected with RSV, and the expression of TLR3 mRNA was determined by PCR and the levels of inflammatory factors were also investigated. The presence of RSV was detected in 3 SCOPD and 8 AECOPD patients, but not in healthy patients. The expression levels of TNF-alpha and IRF-3 in both sputum and serum samples of RSV-positive group were significantly higher than in RSV-negative group. TLR3 mRNA levels in RSV-positive group were significantly higher than those in RSVnegative group. Interestingly, the level of TLR3 mRNA expression was negatively correlated with oxygenation index and lung function parameters. Furthermore, BEAS-2B cells infected with RSV led to significant increase of the expression of TLR3 mRNA and inflammatory factors IFN-beta, IL-13, IL-32, and TNF-alpha. Our observations indicate that AECOPD is associated with RSV infection and the upregulation of TLR3.