Flow cytometric profiles were analyzed using a FACScan analyzer Nutlin-3a molecular weight and CellQuest software (Becton Dickinson, Mountain View, CA, USA). Mice were anesthetized and inoculated i.n. with approximately 107 CFU of A. baumannii

and the lungs harvested on Days 1 and 3 post-infection. Total RNA was isolated from lung tissue using an RNeasy Mini Kit (Qiagen, Tokyo, Japan), and treated with DNaseI (Qiagen). RNA was transcribed to cDNA using M-MLV reverse transcriptase (Promega, Madison, WI, USA) and the cDNA was amplified with AmpliTaq gold (Applied Biosystems, Foster City, CA, USA). The primer pairs used to amplify keratinocyte chemoattractant protein, KC (CXCL1) and hypoxanthine phosphorybosyl transferase (HPRT) were: KC, 5′-TAT CGC CAA TGA GCT GCG C-3′ and 5′-AAG CCA GCG TTC ACC AGA C-3; and HPRT, 5′-CTG TAG ATT TTA TCA GAC TGA AGA G-3′ and 5′-GTC AAG GGC ATA TCC AAC AAC AAA-3′. Groups of five PK136 or rIgG-treated C57BL/6 mice were killed 1 and 3 days after i.n. inoculation with 107 CFU A. baumannii. The trachea were exposed through a midline incision and cannulated with a plastic catheter. Lungs were lavaged twice with 400 μL PBS and the lavage fluid centrifuged at 440 ×g for 5 min. The supernatant was collected and stored at −80°C for ELISA. The levels of KC in

the BAL fluid were determined using mouse CXCL1/KC Quantikine Kits (R & D Systems, Minneapolis, MN, USA). Angiogenesis inhibitor The significance of the differences

was calculated using one-way analysis of variance. A P value of <0.05 was considered to be significant. We first examined the host immune responses to Acinetobacter pneumonia. Because A. baumannii was easily eradicated within 3 days by healthy animals, we focused on the innate immune responses and analyzed the physiological mechanisms involved in the exclusion of A. baumannii. First, the effective Silibinin dose of A. baumannii required for the development of experimental pneumonia in normal C57BL/6 mice was determined. When mice were inoculated with <108 CFU, all the mice survived; however, when a dose of 109 CFU was used, the survival rate was 83% (5/6 mice) after 7 days (data not shown). Therefore, 107 or 108 CFU of A. baumannii was chosen for the pneumonia model. Although all mice inoculated with 107 CFU lost weight up until Day 3 and showed mild clinical signs on Day 1, all recovered completely by Day 4 post-inoculation (Fig. 1A, B). The viable bacterial counts in the lungs and spleens were 105 CFU and 101 CFU, respectively, on Day 1, and no viable bacteria were detected by Day 3 (Fig. 1C). Histological examination of the lungs harvested from mice with pneumonia was undertaken on Days 0, 1, 3, 5, and 7 post-infection (Fig. 2).