Relationship Between Insect Polymer, Human Gene and Asthma

Chitin (C8H13O5N) is a long-chain polymer of a N-acetylglucosamine, a derivative of glucose, and it is found throughout the natural world. It is the main component of the cell walls of fungi, the exoskeletons of arthropods, such as crustaceans (like the crab, lobster and shrimp) and the insects, including ants, beetles and butterflies.

The English word "chitin" was derived from the Latin word "chitōn", meaning mollusk (source: Wikipedia).


A cicada sheds its chitinous exoskeleton. Image source: Wikipedia, Creative Commons "Attribution ShareAlike 2.0 France" Licence.


Structure of the chitin molecule. Image source: Wikipedia, public domain.

Chitinases are digestive enzymes that break down glycosidic bonds in chitin. Because chitin composes the cell walls of fungi and exoskeletal elements of some animals (including worms and arthropods), chitinases are generally found in organisms that either need to reshape their own chitin or to dissolve and digest the chitin of fungi or animals (source: Wikipedia).


Chitinase from barley seeds. Image source: Wikipedia, public domain.

A recent NEJM study reported that a chitinase-like protein (YKL-40) was involved in asthma inflammation and tissue remodeling. Elevated serum YKL-40 levels were correlated with asthma severity, thickening of the subepithelial basement membrane, and pulmonary function.

A new study found that single-nucleotide polymorphisms (SNPs, CHI3L1) that affect YKL-40 can be described as a susceptibility gene for asthma, bronchial hyperresponsiveness, and reduced lung function.

Chitinase 3-like 1 protein (YKL-40) Increases Bronchial Smooth Muscle Remodeling in Patients with Asthma http://goo.gl/Rwhsy

References:

Effect of Variation in CHI3L1 on Serum YKL-40 Level, Risk of Asthma, and Lung Function. NEJM, 04/2008.

YKL-40 could identify patients with COPD who have an increased risk of dying. MedPageToday, 2010.
Chitinase 3-like 1 protein (YKL-40) Increases Bronchial Smooth Muscle Remodeling in Patients with Asthma http://goo.gl/Rwhsy