Schinus terebinthifolia leaf lectin (SteLL) has anti-infective action and modulates the response of Staphylococcus aureus-infected macrophages

Abstract

AbstractStaphylococcus aureusis recognized as an important pathogen causing a wide spectrum of diseases. Here we examined the antimicrobial effects of the lectin isolated from leaves ofSchinus terebinthifoliaRaddi (SteLL) againstS. aureususingin vitroassays and an infection model based onGalleria mellonellalarvae. The actions of SteLL on mice macrophages andS. aureus-infected macrophages were also evaluated. SteLL at 16 µg/mL (8 × MIC) increased cell mass and DNA content ofS. aureusin relation to untreated bacteria, suggesting that SteLL impairs cell division. Unlike ciprofloxacin, SteLL did not induce the expression ofrecA, crucial for DNA repair through SOS response. The antimicrobial action of SteLL was partially inhibited by 50 mMN-acetylglucosamine. SteLL reduced staphyloxathin production and increased ciprofloxacin activity towardsS. aureus. This lectin also improved the survival ofG. mellonellalarvae infected withS. aureus. Furthermore, SteLL induced the release of cytokines (IL-6, IL-10, IL-17A, and TNF-α), nitric oxide and superoxide anion by macrophagens. The lectin improved the bactericidal action of macrophages towardsS. aureus; while the expression of IL-17A and IFN-γ was downregulated in infected macrophages. These evidences suggest SteLL as important lead molecule in the development of anti-infective agents againstS. aureus.