Effect of inactivated Streptococcus pneumoniae as non-pathogenic particles on the severity of pneumonia caused by respiratory syncytial virus infection in mice

Publication date: Available online 31 May 2019Source: Toxicology ReportsAuthor(s): Aki Miyauchi, Wataru Watanabe, Toshi Akashi, Seiko Hashiguchi, Hiroki Yoshida, Chihiro Sugita, Masahiko KurokawaABSTRACTThe severity of pneumonia in respiratory syncytial virus (RSV) infection is strongly related to host immune response and external factors such as bacteria and environmental chemicals. We investigated the effect of inactivated Streptococcus pneumoniae (ISP) as non-pathogenic particles on the severity of pneumonia in RSV-infected mice. Mice were intranasally exposed to ISP before RSV infection. On day 5 post-infection, we examined the lung tissues, virus titer, and infiltrated cells in the lungs. The ISP did not cause significant histopathological effects on lungs of RSV-infected mice and reduced virus titer in the lungs. It reduced the ratio of lymphocyte infiltration into the lungs and consequently the ratio of macrophage increased. In addition, we found that ISP increased RANTES level in bronchoalveolar lavage fluid from RSV-infected mice on day 1 post-infection, but reduced type I interferon levels. Thus, ISP did not exacerbate pneumonia in RSV infection; rather, it might mildly reduce the severity. We characterize and discuss the inherent activity of ISP as non-pathogenic particles inducing the role of RANTES on the pneumonia in RSV infection.Graphical abstract
Source: Toxicology Reports - Category: Toxicology Source Type: research