Keratin—a small protein—is found in grand abundance in animals of all kinds. Keratins are found in the upper layer of our skin, in the tough layers of our nails, and twisted into bundles to form the core of each strand of our hair. Scientists have long understood keratin as a passive biological building block—sturdy, and strong, giving shape and definition to the structures it serves.
But new work suggests that fragments of this protein are doing double duty as warriors, contributing to the ongoing defense of the cornea against bacterial infection and, more importantly, may serve as the building block of powerful new antibiotics.
A team of vision scientists and infectious disease experts at the University of California, Berkeley, discovered bits of the protein in the outer regions of the eye, and surmising a bug-killing power, tested them on a whole range of bacteria. Commonplace villains which cause diarrhea (E.coli) and staph infections (Staph aureus) were snuffed out, and hardier strains which cause strep throat and the flesh-eating disease (Streptococcus pyogenes) were also overcome.
"It really helps us understand why the corneal surface is resistant to infection," Suzanne Fleiszig, who led the study, tells Co.Exist. In fact, she added, "It’s possible we’ve stumbled on a whole system. It could be that they work together as a family." Because the fragments are so small, they can be easily synthesized for study. And when they are better understood, they could one day be cheaply produced in large quantities as antimicrobial drugs.
In their tests, the team found that different fragments targeted and killed different bacteria. Finding out how exactly the fragments work is high on the to-do list, but it’s likely that each uses a different mode of attack to disarm the bacteria they go after. If that’s indeed the case, one hypothesis is that combining the fragments will yield a versatile antibiotic—one that bacteria find more difficult to grow resistant to.
Fleiszig says she is particularly enthused about the possibility that the peptides play well together because it suggests that this new class of drugs could fight bacteria that have developed antimicrobial resistance. "We may be able to design drugs where you’re not just using one fragment but more than one," Fleiszig says. "If you use more than one together, then you might decrease the chance of resistance happening." (With more than one kind of opponent, the probability that the bacteria develop a resistance to the antimicrobial agent falls dramatically.)
At present, several questions remain. It’s not quite clear how the fragments peel off from the keratin and assemble in the cornea, for example, or where they carry out their attack. And an early next step will be to understand how they work—separately and together—in killing the microbes they encounter. But this late discovery of a simple soldier in the battle against infection allows for the exciting possibility that there are other fighters, as yet unrecognized, lurking by their side.