Protective enzyme has a downside: Asthma
By John Travis
An enzyme whose natural job may be to ward off fungi and parasites contributes to the lung inflammation characteristic of asthma, a new study concludes.
The enzyme is known as a chitinase because it breaks down the complex sugar chitin, a tough molecule found in the cell walls of fungi, the surface of parasitic worms, and the exoskeletons of insects and crustaceans. Mammals don’t make chitin, but people have many genes encoding chitinases, so biologists consider the enzymes to be part of the human immune response.