Cathelicidins are peptide components of the innate immune system of mammals. Apart from exerting a direct antibiotic activity, they can also trigger specific defense responses in the host. Their roles in various pathophysiological conditions have been studied, but there is a lack of published information on their expression and activities in the context of mastitis. The aims of this study were to investigate the expression of the bovine cathelicidins BMAP-27, BMAP-28, Bac5, and indolicidin in healthy and infected mammary tissue and in lipopolysaccharide (LPS)-treated cells, to determine their activities against bacteria isolated from bovine mastitis, and to examine their potentials to trigger defense responses in bovine mammary cells. The genes were found to be upregulated in LPS-stimulated neutrophils, but not in infected quarters or epithelial cells. All peptides showed a variably broad spectrum of activity against 28 bacterial isolates from bovine mastitis (MIC values, 0.5 to 32 M), some of which were antibiotic resistant. The activity of each peptide was significantly enhanced when it was pairwise tested with the other peptides, reaching the synergy threshold when indolicidin was present. The bactericidal activity was sensitive to milk components; BMAP-27 and -28 were highly effective in mastitic bovine milk and inhibited in milk from healthy cows. Both peptides were also active in whey and in blood serum and triggered the expression of tumor necrosis factor alpha (TNF-␣) in bovine mammary epithelial cells. Our results indicate multiple roles for the bovine cathelicidins in mastitis, with complementary and mutually enhanced antimicrobial activities against causative pathogens and the capacity to activate host cells.

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Designing small molecules able to break down G4 structures in mRNA (RG4s) offers an interesting approach to cancer therapy. Here, we have studied cationic porphyrins (CPs) bearing an alkyl chain up to 12 carbons, as they bind to RG4s while generating reactive oxygen species upon photoirradiation. Fluorescence-activated cell sorting (FACS) and confocal microscopy showed that the designed alkyl CPs strongly penetrate cell membranes, binding to KRAS and NRAS mRNAs under low-abundance cell conditions. In Panc-1 cells, alkyl CPs at nanomolar concentrations promote a dramatic downregulation of KRAS and NRAS expression, but only if photoactivated. Alkyl CPs also reduce the metabolic activity of pancreatic cancer cells and the growth of a Panc-1 xenograft in SCID mice. Propidium iodide/annexin assays and caspase 3, caspase 7, and PARP-1 analyses show that these compounds activate apoptosis. All these data demonstrate that the designed alkyl CPs are efficient photosensitizers for the photodynamic therapy of ras-driven cancers.

The prevention of implant-associated infection, one the most feared complications in orthopaedic surgery, remains a major clinical challenge and urges development of effective methods to prevent bacterial colonization of implanted devices. Alpha-helical antimicrobial peptides (AMPs) may be promising candidates in this respect due to their potent and broad-spectrum antimicrobial activity, their low tendency to elicit resistance and possible retention of efficacy in the immobilized state. The aim of this study was to evaluate the potential of five different helical AMPs, the cathelicidins BMAP-27 and BMAP-28, their (1-18) fragments and the rationally designed, artificial P19(9/G7) peptide, for the prevention of orthopaedic implant infections. Peptides were effective at micromolar concentrations against 22 Staphylococcus and Streptococcus isolates from orthopaedic infections, while only BMAP-28 and to a lesser extent BMAP-27 were active against Enterococcus faecalis. Peptides in solution showed activities comparable to those of cefazolin and linezolid, on a molar basis, and also a variable capacity to neutralize bacterial lipopolysaccharide, while devoid of adverse effects on MG-63 osteoblast cells at concentrations corresponding to the MIC. The (1-18) BMAP fragments and P19(9/G7) were selected for further examination, based on better selectivity indices, and showed effectiveness in the presence of hyaluronic acid and in synovial fluid, while human serum affected their activity to variable extents, with BMAP-27(1-18) best retaining activity. This peptide was immobilized on streptavidin-resin beads and retained activity against reference Staphylococcus epidermidis and Staphylococcus aureus strains, with negligible toxicity towards osteoblasts, underlining its potential for the development of infection-resistant biomaterials for orthopaedic application. Copyright © 2017 European Peptide Society and John Wiley & Sons, Ltd.