Knockdown of versican V1 induces a severe inflammatory response in LPS-induced acute lung injury via the TLR2-NF-κB signaling pathway in C57BL/6J mice

The versican family is important in the modulation of inflammation, however, the role of versican V1 (V1) in lipo-polysaccharide (LPS)-induced acute lung injury (ALI) and the underlying mechanisms remain to be elucidated. To investigate this, the present study performed experiments in male C57BL/6J mice, which were randomly divided into a normal control group (control; n=6), an LPS-stimulated ALI group (LPS; n=6), a scramble small interfering (si)RNA group (scramble; n=6), a V1-siRNA group (V1-siRNA; n=6), a scramble siRNA and LPS-stimulated group (scramble+LPS; n=6) and a V1-siRNA and LPS-stimulated group (V1-siRNA+LPS; n=6). On day 1, the mice were anesthetized, and 5 nmol scramble siRNA or V1-siRNA were administered intratracheally. On day 3, LPS (1 mg/kg) or phosphate-buffered saline (50 mu l per mouse) were injected intratracheally. All the mice were anesthetized and sacrificed on day 4, and samples were collected and analyzed. The mRNA and protein expression levels were examined using reverse transcription-quantitative polymerase chain reaction analysis, immunohistochemical staining and western blot analysis. ALI was evaluated based on lung injury scores, cell counts and total protein concentrations in the bronchoalveolar lavage fluid (BALF). Inflammatory mediators were detected using an enzyme-linked immunosorbend assay. V1 was increased by LPS in the mouse ALI model, whereas specific V1 knockdown induced higher lung injury scores, and higher total cell counts and protein concentrations in the BALF. Tumor necrosis factor-alpha (TNF)-alpha was upregulated, and interleukin-6 exhibited an increasing trend. The expression of toll-like receptor 2 (TLR2), but not TLR4, increased, and the nuclear factor (NF)-kappa B pathway subunit, P65, was phosphorylated. Taken together, the expression of V1 was upregulated by LPS, and V1 inhibition resulted in the aggravation of LPS-induced ALI via the activation of TLR2-NF-kappa B and release of TNF-alpha.