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

The severity of pneumonia in respiratory syncytial virus (RSV) infection is strongly related to hostimmune response and external factors such as bacteria and environmental chemicals. Weinvestigated the effect of inactivated Streptococcus pneumoniae (ISP) as non-pathogenic particleson the severity of pneumonia in RSV-infected mice. Mice were intranasally exposed to ISP beforeRSV infection. On day 5 post-infection, we examined the lung tissues, virus titer, and infiltratedcells in the lungs. The ISP did not cause significant histopathological effects on lungs of RSVinfectedmice and reduced virus titer in the lungs. It reduced the ratio of lymphocyte infiltrationinto the lungs and consequently the ratio of macrophage increased. In addition, we found that ISPincreased RANTES level in bronchoalveolar lavage fluid from RSV-infected mice on day 1 postinfection,but reduced type I interferon levels. Thus, ISP did not exacerbate pneumonia in RSVinfection; rather, it might mildly reduce the severity. We characterize and discuss the inherentactivity of ISP as non-pathogenic particles inducing the role of RANTES on the pneumonia in RSVinfection.九州保健福祉大学201

Perinatal Exposure to Insecticide Methamidophos Suppressed Production of Proinflammatory Cytokines Responding to Virus Infection in Lung Tissues in Mice

Methamidophos, a representative organophosphate insecticide, is regulated because of its severe neurotoxicity, but it is suspected of contaminating agricultural foods in many countries due to illicit use. To reveal unknown effects of methamidophos on human health, we evaluated the developmental immunotoxicity of methamidophos using a respiratory syncytial virus (RSV) infection mouse model. Pregnant mice were exposed to methamidophos (10 or 20 ppm) in their drinking water from gestation day 10 to weaning on postnatal day 21. Offsprings born to these dams were intranasally infected with RSV. The levels of interleukin-6 (IL-6) and interferon-gamma in the bronchoalveolar lavage fluids after infection were significantly decreased in offspring mice exposed to methamidophos. Treatment with methamidophos did not affect the pulmonary viral titers but suppressed moderately the inflammation of lung tissues of RSV-infected offspring, histopathologically. DNA microarray analysis revealed that gene expression of the cytokines in the lungs of offspring mice exposed to 20 ppm of methamidophos was apparently suppressed compared with the control. Methamidophos did not suppress IL-6 production in RSV-infected J774.1 cell cultures. Thus, exposure of the mother to methamidophos during pregnancy and nursing was suggested to cause an irregular immune response in the lung tissues in the offspring mice