Mice have tens of thousands of chemical sensing nose cells that can cause an allergic reaction. Researchers say this discovery could help us understand how the immune system reacts to inhaled allergens and why some people with allergies lose their sense of smell.
We know that in humans and mice, breathing in allergens such as house dust mite droppings or mould can cause inflammation in the nose. This triggers a further allergic response driven by immune cells, but we don鈥檛 fully understand the process.
To try to learn more, a team at Harvard University isolated cells from the noses of mice and sorted them into different types according to their shape, size and the specific proteins they displayed on their surface.
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By doing this, they identified chemical sensing cells that react to allergens in the air soon after they are inhaled. These cells start releasing molecules that cause inflammation in the nose even before immune cells are delivered to the nose in the bloodstream.
The chemical sensing cells in the nose release 鈥渂oatloads鈥� of inflammatory molecules, says Lora Bankova, who led the work. These are the same molecules that drive allergic conditions like asthma, and are usually only produced by immune cells.
Cells similar to those in the nose have been found in the lower airway and the gut in mice and humans, but they were thought to be extremely rare. Bankova says she was surprised to discover there are 20,000 to 30,000 of these nose cells in mice. There are equivalent chemical sensing cells in the human nose, says Bankova, but we don鈥檛 know if they have a similar function.
The cells are also surprising because they are mostly found in the part of the nose involved in smell, says Bankova, which hadn鈥檛 previously been thought to play a role in allergic responses. This might explain why some people with chronic allergies lose their sense of smell, says Bankova. 鈥淚t might be because there is so much inflammation in that area that we hadn鈥檛 previously recognised,鈥� she says. As well as detecting allergens, these cells may also be able to sense invading microbes such as the common cold virus, says Bankova.
A better understanding of these cells may lead to new treatments for allergies, says Emmanuelle Sidot at the University of Oxford.
Journal reference: Science, DOI:
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