Diesel Exhaust Enhanced Susceptibility to Influenza Infecton is Associated with Decreased Surfactant Protein Expression

The association of diesel exhaust enhanced susceptibility to influenza infection with decreased surfactant protein (SP) expression was studied. Data were analyzed using a nonparametric one-way analysis of variance (ANOVA), followed by Dunn's multiple comparison post hoc test. Mice exposed to the low dose of diesel exhaust (DE) showed increased influenza staining, confirming the mRNA data. Exposure to DE in the absence of influenza infection had no significant effect on interleukin (IL)-6 mRNA or protein levels. Neither exposure to DE nor infection with influenza significantly increased bronchoalveolar lavage (BAL) fluid protein levels as compared to air exposed noninfected mice. Influenza virus infection significantly increased the expression of SP-A in the lung in mice exposed to air.