Antibiotics are most commonly used to treat bacterial infections, but bacteria are rapidly able to evolve and resist these drugs, contributing to superbugs. Immune killer cells or white blood cells, however, are seemingly more effective at destroying bacteria cells. How do our immune cells fight bacteria so efficiently? What exact mechanisms do killer cells use to track and destroy bacteria and can we replicate those mechanisms with drugs?
A common way immune cells can the trigger death of bacteria is by oxidizing the bacterial cells. However, immune cells are still able to destroy bacteria in environments without oxygen leading scientists to believe other methods are also used in attacking bacteria.
Scientists have recently discovered that immune cells methodically kill cells without the use of oxygen. The immune cells do this by shooting enzymes into bacteria to program the bacteria to self-destruct. Scientists have discovered this by observing immune killer cells as they destroy E. coli and the bacteria responsible for Listeria and tuberculosis. They measured the protein levels of each different bacteria before, during, and after the immune cells killed the bacteria. Each bacterial strain started with about 3000 proteins and ended up losing around 10% of their proteins due to the immune cells injected enzyme called granzyme B. Those 10% of proteins destroyed, however, were necessary to the survival of each bacteria. Granzyme B also shuts down ribosomes preventing the bacteria from making new proteins.
This discovery is significant at a time where antibiotics are becoming less efficient and superbugs are becoming prevalent. Scientists hope to design a new drug that will treat bacterial infections in a similar way to our own immune killer cells.