Why Do Allergens Make Us Cough and Sneeze?
Allergens can make us coughing and sneezing by pushing holes in the cells of the respiratory tract
The immune system detects damage to cell membranes caused by pore formation proteins and mounts a response
FCAFOTODIGITALS / GETTY images
The sneezing, the eyes of itching and the cough caused by certain allergens are caused by proteins creating holes in the cells of the respiratory tract, reports a study published this week in Nature.
The results call into question the understanding of scientists of how allergies are triggered, explains Feargal Ryan, who is studying host-microbe interactions at Flinders University in Adélaïde, Australia. Before that, the mechanism that triggers immune responses to allergens was not really understood. Researchers mainly focused on how only one allergen arouses a reaction, rather than looking for a generalizable mechanism.
The results could also modify allergies treatment strategies, which generally target the allergen directly or downstream of the immune responses. Researchers can now start to look for means to target proteins for creating holes that initiate the immune response, says Ryan.
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Pore training proteins
Researchers based in Beijing, China, have identified two proteins in the mold Alternaria Alternatawhich causes allergic reactions to around 5% of people, who trigger the inflammation of the respiratory tract observed during allergic reactions.
Together, the proteins, called AEG-S and AEG-L, create a pore in the membranes of the cells lining the nose, the throat and the lungs. This allows calcium ions to enter the cells and release molecules that alert the immune system to danger. Damage to cellular membranes of these proteins forming pores could be a “common signal that our body uses to recognize something like an allergen,” explains co-author MO XU, who studies immune responses at the University of Tsinghua.
To test how proteins stimulated the immune system, the team treated pulmonary cells with proteins. Protein administration at the same time has triggered a response similar to that of the administration of an extract from A. AlternataBut this answer was not observed when the proteins received one at a time.
Researchers also tested if proteins could cause allergic inflammation of the respiratory tract in mice. Six hours after the mice received proteins intranasically, rodents have shown immune responses similar to those triggered by exposure to exposure to exposure to exposure to exposure A. Alternata.
The team also observed signs that the mice had developed a respiratory allergy, such as increased levels of immunoglobulin E (IGE) – an antibody produced in response to allergens – after the mice received proteins every three days for two weeks. This response was not observed when the proteins were administered separately, or when the mice were exposed to a genetically modified mold without the other protein.
Common trigger
The team suspected that other allergens with pore training proteins would also induce an immune response. When the researchers exposed mice to pore training proteins of airborne mold Aspergillus Niger – an allergen – and the venom of the sea anemone Actinia EquinaThey observed an immune response similar to that induced by AEG-S and AEG-L. They also found that allergic inflammation of the respiratory tract was triggered by pore drilling proteins from the earthworm Eisenia FetidaThe King Oyster fungus Pleurotus EryngiiThe bacteria Clostridium perfringens And the fungus Laetiportus sulfureus.
The results suggest that allergens that are not linked to each other can trigger allergic reactions in the same way, because they have pore drill proteins that have been preserved by evolution, explains Ryan. “It’s a new way of thinking of allergens,” he says. Future treatments could wonder if there is a way to block or inactivate these proteins and stop reactions, he adds.
Xu says that his team studies immune response ways after proteins forming pores damage cell membranes and allergens with proteins do not form pores, such as mites or pollens, use the same way.
This article is reproduced with permission and was first publication July 31, 2025.
