Determination of ICAM-1 protein levels in the lungs Lungs were homogenized in RIPA buffer containing a protease inhibitor cocktail (Sigma). Separation of protein by SDS-PAGE, transfer to nitrocellulose membrane, EPZ-6438 mw and detection was performed using standard immunoblot methods. Goat polyclonal antibody to ICAM-1 (Santa Cruz Biotechnology) was used for detection. Relative protein levels were determined by densitometric analysis of Western blot bands using a Molecular Imager Gel Doc XR System (BioRad, Hercules, CA). To ensure that equal amount of protein had been probed, and to permit normalization of ICAM-1 across samples, membranes were
stripped and the amount of actin determined using rabbit anti-actin antibodies (Bethyl Laboratories, Inc., Montgomery, TX). Statistical analysis For comparisons between cohorts either a One-way ANOVA or two-tailed Birinapant nmr Student’s t test was used as indicated. P values <0.05 were considered significant. For survival analyses a Kaplan-Meier Log Rank Survival Test was used. Results Oral statin prophylaxis decreases the severity of pneumococcal pneumonia in mice To determine the effect of simvastatin prophylaxis on disease severity we first assessed bacterial burden during pneumonia. Pneumococcal titers in the lungs collected at 24 h post-infection (hpi) did not significantly differ between the simvastatin fed and control cohorts (Figure 1); although bacterial
titers in the lungs of mice on HSD had a trend towards reduced bacterial load
(P = 0.08). At 42 hpi, mice on the control diet had approximately 50- (P = 0.02) and 100-fold (P = 0.002) more bacteria in their lungs than mice on LSD and HSD, respectively. In agreement with this reduced bacterial load, histological analysis of lung sections demonstrated decreased lung damage with less evidence of lung consolidation, edema, and hemorrhage in the HSD mice versus controls (Figure 2A). Mice receiving LSD had no discernible difference in lung damage versus controls. Analysis of BAL fluid for evidence of vascular leakage demonstrated that mice on HSD had reduced albumin in nearly their lungs 24 hpi (Figure 2B). No differences in albumin levels were found between mice receiving the LSD versus the control diet or in baseline levels of albumin prior to infection. Thus, HSD seemed to protect vascular integrity during infection. Figure 1 Simvastatin prophylaxis decreases bacterial burdens in the lungs. Bacterial titers in the lungs 24 and 42 h after infection of mice fed the Control, Low or High statin diet and challenged intratracheally with 1 X 105 cfu. Each circle represents an individual mouse. Horizontal lines indicate the median; dashed lines indicate limit of detection Mice receiving statins had significantly lower bacterial titers in the lungs 42 h after infection. Data are presented as the mean ± SEM. Statistics were determined by a two-tailed student’s t-test. P < 0.05 was considered significant on comparison to Control fed mice.