Worm against asthma

A hookworm protein protects mice from allergic overreaction

The hookworm Necator americanus produces a protein that suppresses the allergic reaction in asthma. © Jasper Lawrence / CC-by-sa 4.0
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Parasite as a helper: A parasitic hookworm protein could potentially protect against asthma. Experiments with mice show that the worm protein prevents the allergic inflammatory reaction in the bronchi and lungs. Also in human cell cultures, the protein successfully blocked typical allergic reactions. Whether this also works in asthma patients, but is still unclear.

For some time, there has been evidence that parasites can also do their good: People who are affected by certain worms, less often suffer from allergies and asthma. Researchers even suggest that our immune system is adapted from the past to be constantly on guard against such parasites. Because these are almost invisible to us, the immune system is looking for a kind of substitute opponent. It then reacts even to harmless allergens such as mite faeces or pollen.

However, only very few people are likely to be willing to be infected with parasitic worms to protect against allergies. Researchers have therefore been trying for a long time to come after the allergens-protecting recipe of parasites. Severine Navarro of James Cook University in Cairns and his colleagues could now have found one of these drugs.

From the intestine to the bronchi

Some time ago researchers discovered that certain hookworm proteins (Necator americanus) help against inflammatory bowel disease. The nematode worm releases these substances in order to settle undisturbed in the intestine of its host. The active ingredients inhibit the immune reaction and thus the inflammation.

The researchers' idea: If the hookworm proteins inhibit the misguided immune response to bowel disease, they might also be able to counteract the overreaction in allergic asthma. To test this, they gave mice a specific worm protein called AIP-2 and subsequently provoked an asthma attack. display

Immune reaction suppressed

And indeed, while control mice immediately developed the asthmatic immune responses, the attack did not occur in the AIP-2-treated mice. "The protein suppressed the inflammation of the airways and lungs in this mouse model of asthma, " report Navarro and his colleagues.

Further investigations revealed that the worm protein on the one hand suppresses the production of pro-inflammatory messengers in the tissues. On the other hand, it affects certain T cells and prevents them from accumulating and, as it were, "sounding the alarm". This inhibited the allergic reaction - but without generally acting immunosuppressive, as the researchers emphasize.

Does that also work in humans?

For asthma and allergy sufferers, however, the crucial question is whether this protein also works in humans. To investigate, the researchers performed tests on human cell cultures. The cells, including T cells, were from patients with severe allergy to house dust mites.

It turned out that if the cell cultures were previously treated with the worm protein, they reacted much weaker to mite allergens than untreated cells. The typical rapid increase in regulatory T cells has not materialized, the researchers report. This is at least a first indication that AIP-2 can also protect against asthma and other allergic reactions in humans.

However, more tests have yet to follow to verify these initial promising results. Thus, the worm protein in the mice seems to influence certain cells and tissues more than others. Whether it can therefore protect the airway areas that are crucial for human asthma patients first has to be tested. (Science, Translational Medicine, 2016; doi: 10.1126 / scitranslmed.aaf8807)

(James Cook University, 27.10.2016 - NPO)