Differential Expression of theSystem by Antimicrobial Peptide LL-37 in Commensal and ClinicalIsolates.

The three-componentsystem senses and responds to cationic antimicrobial peptides (CAMPs), which induces the expression of theoperon and the genesand, modifying the surface net charge in, resulting in the repulsion of CAMPs. Thesystem has been only studied in the1457 strain, and there are no studies of prevalence and level of expression ofin commensal and clinical isolates. From 60 isolates, those selected from commensal healthy skin (n = 20), commensal healthy conjunctive (n = 10), and clinical ocular infection (n = 30) presented the,andgenes in their genomes. Constitutive expression of,andgenes was determined by RT-qPCR in all isolates. It was found that expression of,andwas 3.3-5.9-fold higher in commensal isolates stimulated with LL-37 (15 µg/mL) than in clinical isolates. Similarly, expression of theoperon and the genes, andwas 8-10-fold higher in commensal isolates than in clinical. However, LL-37 did not increase the addition of lysine in the phospholipids of the cytoplasmic membrane in any of the isolates. Mutations in theloop region,, and their promoter sequence were not found. These results demonstrated thatsystem is essential in all isolates for its constitutive expression; however, LL-37 caused an increase ofexpression in commensal isolates, suggesting thatisolates do not respond in the same way to the presence of LL-37.