LL‐37 fragments have antimicrobial activity against Staphylococcus epidermidis biofilms and wound healing potential in HaCaT cell line

Abstract

Staphylococcus epidermidis is a common nosocomial pathogen able to form biofilms in indwelling devices, resulting in chronic infections, which are refractory to antibiotics treatment. Staphylococcal biofilms are also associated with the delayed reepithelization and healing of chronic wounds. The human cathelicidin peptide LL-37 has been proven active against S. epidermidis biofilms in vitro and to promote wound healing. As previous studies have demonstrated that fragments of LL-37 could possess an equal antibacterial activity as the parent peptide, we tested whether shorter (12-mer) synthetic fragments of LL-37 maintained the antibiofilm and/or immune modulating activity, aiming at the identification of essential regions within the LL-37 parent sequence. Three fragments of LL-37 displayed improved activity against S. epidermidis in terms of biofilm inhibition and eradication, a reduced cytotoxicity to human keratinocytes and erythrocytes. In addition, KR-12 and VQ-12 enhanced wound healing potential, relative to LL37. FK-12 and KR-12 are truncated version of the cathelicidin, previously reported as valid antimicrobials, whereas VQ-12 is a single substituted LL-37 fragment. Remarkably, the single substitution aspartic acid to valine in position 26 caused gain of antimicrobial function in the inactive VQ-12 fragment. The combination of antibiofilm, wound healing potential, and low cytotoxicity makes KR-12 and VQ-12 promising therapeutic agents and lead compounds for further improvement and understanding of antibiofilm and wound healing properties.

Immunomodulatory potential of Nisin A with application in wound healing

“…L. lactis was cultivated in tryptic soy broth (pH of 6.5) at 30 °C. For Galleria mellonella infection experiments, two bacterial strains were employed, Escherichia coli (ATCC25922) and Staphylococcus epidermidis kindly donated from Dr. Løbner‐Olesen . Strains were cultivated in Mueller‐Hinton broth (MHB; BD Difco) or agar (MHB with 1.5% agar) and incubated at 37 °C with shaking at 180 rpm (orbital shaker, g force does not really apply).…”

Evaluation of Nisin and LL-37 Antimicrobial Peptides as Tool to Preserve Articular Cartilage Healing in a Septic Environment

“…AMPs solutions were prepared fresh prior to each experiment by diluting the AMPs' mother solutions directly in the appropriate cell or bacteria culture medium. AMPs were tested at the concentrations detailed in Table 1, based on previously reported MIC values in literature for LL-37 (Overhage et al, 2008;Leszczynska et al, 2013;Luo et al, 2017;Saporito et al, 2018;Kamysz et al, 2020) and Nisin (Brumfitt et al, 2002;Piper et al, 2009;Dosler and Gerceker, 2011;Iancu et al, 2012;Shin et al, 2015).…”

Antibacterial mechanisms of GN‐2 derived peptides and peptoids against Escherichia coli

“…A microtiter broth dilution method was used to determine the minimal inhibitory concentrations (MICs) for the tested compounds. In brief, a bacterial inoculum of 2 to 8 × 10 5 CFU/mL was prepared in Mueller‐Hinton broth, and added to a microtiter plate.…”

“…Eradication of preformed bacterial biofilm was monitored in a microtiter plate assay with minor modifications of growth media and the crystal violet biomass staining procedure. The biofilm was formed by overnight incubation of 100 μL/well of a 1:100 dilution of a fresh overnight culture.…”

“…Peptide/peptoid secondary structures were experimentally investigated using a J‐815 circular dichroism (CD) spectropolarimeter (Jasco, Easton, Maryland, USA) . Far‐UV spectra between 190 and 280 nm were recorded over a 1 mm path length quartz cell after five accumulations at 20 °C, scanning 100 nm/minute with a band width of 1 nm.…”