Exposed tissue surfaces, including skin and mucous membranes, are under constant threat of attack by microorganisms in the environment. The layer of cells that line these areas, known as epithelial cells, are the first line of defense against these pathogens, but the underlying molecular mechanisms that allow them to repel microbes are unknown.
In this issue of the Journal of Clinical Investigation, researchers at the University of California, Berkeley, report that epithelial cells in the cornea, which is highly resistant to bacterial infection, express small antimicrobial peptides, portions of human cytokeratin 6A, that defend the eye against infection. Using mass spectrometry, Suzanne Fleiszig and colleagues determined that these peptides protect against multiple bacterial pathogens by preventing the bacteria from binding to the epithelial cells.
Additionally, they found that mice lacking cytokeratin 6A were more susceptible to eye infections. In an accompanying commentary, Michael Zasloff of Georgetown University School of Medicine discusses the implications of these findings for the development of antimicorbial therapeutics.