Article #2: Sniffing for Diseases

A man once discovered he had cancer on his leg after his dog was licking the mole on his leg which turned out to be malignant melanoma. Since then, scientists have been curious to know if animals had receptors in their noses that gave them the ability to smell disease or sense danger because rats and mice are able to sense sick members of their species. A few smell receptors have been identified in mice that can pick up anything from food, fragrance, fear and danger that humans do not acquire. Scientists wondered if rats and mice are able to detect the scent of chemicals from inflammation or bacteria as a result of a disease.

They analyzed the genome of mice and discovered genes for 5 new receptors in the olfactory system, which have sensory cells that connect the nose to the brain, that all belonged to the family of proteins called formyl peptide receptors, FPRs (Thomas 2009). One type of FPR in the immune system is able to detect chemicals given off by pathogens in the blood which help immune cells to track down and attack the foreign invaders. They thought maybe the newly discovered genes could be FPRs in the olfactory cells. With this in mind, all they had to do is to find a linkage between the olfactory cell and how they respond to a disease.

A researcher put this to the test by exposing mouse neurons to disease-causing bacteria which initiated a smell response between the chemical and the neurons. This area of the brain where the smell response occurs is linked to the amygdala, part of the brain responsible for emotions, making the mouse respond quickly to chemicals of foreign microbes. Disease-smelling receptors were also found in gerbils and rats but unfortunately humans lack the ability to detect chemicals from diseases. This new discovery could be a useful technique for early detection of infections or diseases.

Citation Information
Thomas, Claire. 2009 "A Nose for Disease" ScienceNOW Daily News[Internet] Washington DC and Cambridge, UK: High Wire Press; 2009 [cited 2009 May 20]. Available from http://sciencenow.sciencemag.org/cgi/content/full/2009/422/4