Brain infections such as bacterial meningitis and encephalitis can cause death or serious disability and are difficult to treat with conventional antibiotics because of poor CNS-penetration and bacterial drug-resistance. Small cationic antimicrobial peptides form an important part of the host defence system and have potential as therapeutic agents. Unlike conventional antibiotics, antimicrobial peptides appear to be bacteriocidal rather than bacteriostatic, require a short contact time to induce killing, and do not easily induce resistance. Most small antimicrobial peptides form α-helices or β-sheet-like structures that can insert into, and subsequently disrupt, negatively charged bacterial cell surfaces.
Scientists at Singapore’s Institute of Bioengineering and Nanotechnology have described novel antimicrobial peptide nanoparticles that are able to readily cross the blood brain barrier. The nanoparticles are self-assembled from an amphiphilic oligopeptide containing a motif that promotes cell penetration. The nanoparticles were effective against a range of bacteria, yeasts and fungi in vitro and were also more effective against Staphylococcus aureus infection in mice than their unassembled peptide counterparts. Importantly, the nanoparticles were also able to cross the blood brain barrier and suppress bacterial growth in rabbits with Staphylococcus aureus meningitis. The study showed that antimicrobial nanoparticles are effective against bacterial brain infections in animals and do not damage red blood cells, liver or kidneys at the tested doses. The next challenge will be to develop nanoparticles that can be used in people.
The study is published in the journal Nature Nanotechnology.