New peptides with immunomodulatory activity in macrophages and antibacterial activity against multiresistant Staphylococcus aureus

Staphylococcus aureus infections are a common concern world-wide due to the increasing number of bacterial strains with multiresistant properties to existing antibiotics, incrementing the need for novel molecules and therapy approaches for their treatment. This study evaluated the antibacterial and immunomodulatory activity of eight new peptides (AA, KS, NS, RN, AT, GF, KV and LK) as the basis for the search of new antibacterial and therapeutic agents for topic prevention and treatment against S. aureus infections. Here, there are characterized in silico eight new antimicrobial peptides. Their antibacterial activity against S. aureus and cytotoxic activity in mammalian cell lines were evaluated in vitro with the peptides individually and combined. Three of the peptides (GF, AT and AA) immunomodulatory activity was assessed in macrophages and under three scenarios: non-stimulation, Escherichia coli LPS stimulation and S. aureus lysate stimulation. Results showed that three peptides individually showed the best antibacterial activity against the S. aureus bacteria evaluated. The peptides presented immunomodulatory activity in THP-1 macrophages by displaying different profiles, increasing or decreasing four cytokines (IL-1{beta}, TNF-, IL-8 and CCL2 (MCP1)). This activity depended on the peptide concentration and the stimulation in which the macrophages were exposed to. Taken together, these results demonstrate the potential of these peptides to be used in further studies as novel antimicrobial molecules for the prevention and treatment of S. aureus infections.