A team of researchers has developed an anti-microbial peptide that can destroy many types of bacteria, including some that are resistant to most antibiotics. ‘One of our main goals is to provide solutions to try to combat antibiotic resistance. This peptide is exciting in the sense that it provides a new alternative for treating these infections, which are predicted to kill more people annually than any other cause of death in our society, including cancer,’ said Cesar de la Fuente, researcher at the Massachusetts Institute of Technology, in the US. Anti-microbial peptides, produced by all living organisms as part of their immune defences, kill microbes in several different ways. First, they poke holes in the invaders’ cell membranes. Once inside, they can disrupt several cellular targets, including DNA, RNA, and proteins. In the study published in the journal Scientific Reports, the researchers began with a naturally occurring anti-microbial peptide called clavanin-A. Anti-microbial peptides have a positively charged region that allows them to poke through bacterial cell membranes, and a hydrophobic stretch that enables interaction with and translocation into membranes.
The researchers decided to add a sequence of five amino acids that would make the peptides even more hydrophobic, in hopes that it would improve their killing ability. This new peptide, which they called clavanin-MO, was very potent against many bacterial strains. In tests in mice, the researchers found that it could kill strains of Escherichia coli and Staphylococcus aureus that are resistant to most antibiotics. Another key advantage of these peptides is that while they recruit immune cells to combat the infection, they also suppress the overactive inflammatory response that can cause sepsis, a life threatening condition. ‘In this single molecule, you have a synthetic peptide that can kill microbes — both susceptible and drug-resistant — and at the same time can act as an anti-inflammatory mediator and enhance protective immunity,’ de la Fuente added. The researchers also found that these peptides can destroy certain biofilms, which are thin layers of bacterial cells that form on surfaces. This raises the possibility of using them to treat infections caused by biofilms, such as the Pseudomonas aeruginosa infections that often affect the lungs of cystic fibrosis patients