Laboratory Biosafety-2, Institute of Pediatrics, Children's Hospital of Chongqing Medical University, Chongqing, China.
PLoS One. 2013 Sep 9;8(9):e73488. doi: 10.1371/journal.pone.0073488. eCollection 2013.
Respiratory syncytial virus (RSV) and human metapneumovirus (hMPV) are common causes of respiratory infections in children. Diseases caused by hMPV are generally considered to be less severe than those caused by RSV; the underlying mechanisms, however, remain unknown. In the present study, the expressions of TLRs in airway epithelial cells and lungs of BALB/c mice infected by hMPV or RSV were measured in an attempt to explore the differences in the airway inflammation caused by the two viruses. Our results demonstrate that both hMPV and RSV infection upregulated the expressions of TLRs and inflammatory cytokines. Specifically, the TLR3 expression was revealed to be elevated in vitro and in mouse lungs. IFN-α produced by A549 cells after RSV or hMPV infection remained undistinguishable, whereas production of TNF-α was significantly higher after RSV infection than hMPV infection either in the presence or absence of Poly I:C. This study provides a clue that more severe clinical syndrome of RSV infection may be due to the greater magnitude of induction of airway inflammation by RSV involving TLR3 activation and production of TNF-α.
呼吸道合胞病毒（RSV）和人偏肺病毒（hMPV）是儿童呼吸道感染的常见病因。一般认为，hMPV 引起的疾病比 RSV 引起的疾病要轻；然而，其潜在机制尚不清楚。本研究通过测量 BALB/c 小鼠感染 hMPV 或 RSV 后气道上皮细胞和肺部中 TLRs 的表达，试图探讨这两种病毒引起的气道炎症的差异。研究结果表明，hMPV 和 RSV 感染均上调了 TLRs 和炎症细胞因子的表达。具体而言，TLR3 的表达在体外和小鼠肺部均升高。RSV 或 hMPV 感染 A549 细胞后产生的 IFN-α无明显差异，而 RSV 感染后产生的 TNF-α无论是在 Poly I:C 存在与否的情况下均显著高于 hMPV 感染。本研究提供了一个线索，即 RSV 感染更严重的临床综合征可能是由于 RSV 通过 TLR3 激活和 TNF-α产生引起的气道炎症程度更大。
