Hayato Go, Fukushima Medical Iniversity, Fukushima, Fukushima, Japan; Nozomi Kashiwabara, Fukushima Medical University,, Fukushima, Fukushima, Japan; Hajime Maeda, School of Medicine, Fukushima Medical University, Fukushima, Fukushima, Japan; Koichi Hashimoto, Fukushima Medical University, Fukushima, Fukushima, Japan
Associate professor Fukushima Medical Iniversity Fukushima Medical University Fukushima, Fukushima, Japan
Background: Respiratory syncytial virus (RSV) is the leading cause of bronchitis in young children. Children with RSV bronchiolitis, severe enough for hospitalization, have a higher risk of developing recurrent wheezing, childhood asthma, or allergic rhinoconjunctivitis. However, further investigation into the pathogenesis of recurrent wheezing and childhood asthma after RSV infection is still needed to ease the suffering of infants affected by RSV bronchitis. Our previous study demonstrated that lung periostin, IL-4 and IL-13 mRNA levels elevated in mice infected with RSV. On the other hand, miR-21 and miR-155 are known to increase innate immune cells in response to IL-13 and IL-4. In this study, we hypothesized that miR-21 and miR-155 are associated with the pathogenesis of wheezing and asthma after RSV infection. Objective: To evaluate the exact contribution of miR-21 and miR-155 in the pathogenesis in a mouse model of RSV and mouse lung function after RSV infection. Design/Methods: Human RSV strain A2 was propagated in Vero cells using serum-free medium and stored at -80℃. Mice (5wks old) were infected intranasally with 1×107 PFU /g in 100 ul serum free medium. Control and UV mice were sham infected with serum- free medium and UV irradiated RSV. Lung samples were collected at 2,4,7 and 14 days post infection (dpi). RNA was extracted from whole lung homogenates using the mirVANA-RNA isolation kit ((Life technologies). 18s and U6 were used as normalized controls. Quantiative real-time PCR was performed using TaqMan Gene and miRNA expression assay (Life technologies) for the following genes: miR-21, miR-155, IL-6, TNFα, IL-1b, CCL, IL-17 and INFγ. At 2,4,7 days, plaque assay was analyzed. And, lung function such as minute volume (MV) at day 0 to 14 was performed using plethysmography (emka science). Results: As shown in Figure 1, RSV virus titer/ left lung weight (pfu/mg(log10)) was increased in RSV infected mouse lung compared with UV irradiated RSV and controls mouse lung. Lung miR-21, expression levels at dpi 2,4,7,14 and lung miR-155 expression levels at dpi 2, 7, and lung IL-6, IL-1b, and CCL expression levels at dpi 2,4,7 were significantly increased in RSV infected mouse compared with UV irradiated RSV and controls mouse lung (Figure 2 and 3). MV in RSV infected mice at day 1 was significantly decreased compared with UV irradiated RSV and controls mice.
Conclusion(s): RSV infection alters pro-inflammatory molecules such as miR-21, miR-155, IL-6, IL-1b and CCL in mouse lung.
