Pseudomonas aeruginosa is an opportunistic pathogen that causes
nosocomial pneumonia and infects patients with
cystic fibrosis. P. aeruginosa lung
infections are difficult to treat due to bacterial resistance to
antibiotics, and strains with multidrug resistance are becoming more prevalent. Here, we examined the use of a small
host defense peptide, innate defense regulator 1002 (IDR-1002), in an acute P. aeruginosa lung
infection in vivo
IDR-1002 significantly reduced the bacterial burden in bronchoalveolar lavage fluid (BALF), as well as MCP-1 in BALF and serum, KC in serum, and
interleukin 6 (IL-6) in BALF. Transcriptome sequencing (
RNA-Seq) was conducted on lungs and whole blood, and the effects of P. aeruginosa,
IDR-1002, and the combination of P. aeruginosa and
IDR-1002 were evaluated. Differential gene expression analysis showed that P. aeruginosa increased multiple inflammatory and innate immune pathways, as well as affected hemostasis,
matrix metalloproteinases,
collagen biosynthesis, and various metabolism pathways in the lungs and/or blood. Infected mice treated with
IDR-1002 had significant changes in gene expression compared to untreated infected mice, with fewer differentially expressed genes associated with the inflammatory and innate immune responses to microbial
infection, and treatment also affected morphogenesis, certain metabolic pathways, and lymphocyte activation. Overall, these results showed that
IDR-1002 was effective in treating P. aeruginosa acute lung
infections and associated
inflammation.