You may be wondering what the hookworm parasite has to do with allergies. Professor Graham Le Gros from the Malaghan Institute of Medical Research studies an interesting relationship. People with hookworm tend not to get allergies (including asthma).
Hookworm is a nasty parasite that lives mostly in tropical countries. These parasites burrow into your skin – usually through your foot and move up through your body to the lungs. The worm moves up to the throat where it is swallowed. Once in the stomach, they ‘hook’ onto the stomach wall and live there for several months feeding off your blood and reproducing. They deplete you of iron, cause malnutrition and make you very sick. People can die because of hookworm.
Using the New Zealand mouse worm for the investigation
When Graham and his team discovered the relationship between hookworm and allergies, they decided to investigate further. We don’t have hookworm in New Zealand so they used a mouse version for their research. Graham says the enzymes that the mouse worms make are comparable to the overseas hookworm and can be used for their studies of the allergic disease process.
Hookworms calm the immune system
The team studied the effects of the worms on the immune system. Although the hookworm is a terrible parasite, it may be possible to exploit it for good purposes in stopping our allergic reactions.
An allergic reaction is when the immune system responds to something normally harmless (like pollen) in the same way as it might to a parasite. That is, it tries to get rid of it. An asthmatic attack is an example of an allergic response in the lungs. The lungs produce mucus and make you cough in the same way they would to expel a parasite – only it’s not a parasite. It is something harmless.
Graham says they don’t know why the immune system behaves in this way. What they do know is the effect the hookworm has on the immune system. The hookworm does not want to be dislodged from its host so it produces enzymes that calm the immune system down to stop it from being expelled.
An enzyme that will prevent asthma and other allergies
Graham and his team have been able to isolate the enzyme of the hookworm that causes the immune system to calm down.
Part of this process is to determine both the protein sequence and the DNA sequence of the enzyme. Once this is determined, they can clone the gene for the enzyme and investigate its use in therapies or vaccines to treat inflammatory diseases like asthma and other allergies. However, this is very expensive, and Graham says it might be cheaper and easier to find a drug that will do this. They can use the hookworm enzyme to screen for other chemicals that will do the same job. Graham says many chemicals will do this – they just need to identify them.
… and a vaccine for hookworm
Graham is passionate about helping other people. He is researching the hookworm to find a cure for allergic diseases for the people in New Zealand, but he also recognises that the people in developing countries with hookworm are suffering and dying. He says we benefit from our asthma research but we should not be just takers. He stresses that the scientific community is a global partnership and they should all work together to help people who haven’t got the money to help themselves. Graham says here in New Zealand we have the tools available to make a vaccine against hookworm. In 2010 he obtained a grant from the government to work on a vaccine that will stop people in other countries from getting hookworm.
In July 2019 the Malaghan Institute announced human clinical trials to further study hookworm. "Funded by the Health Research Council, and in collaboration with the University of Otago Wellington, the trial will see up to 15 healthy Wellingtonians infected with a low, safe dose of Necator americanus larvae, and studied over the course of a year."
Read more about this in this news article, Kiwi researchers to start world-first human trial exploring the health potential of parasitic worms.
The research was extended in September 2020 to investigate the possibility of using human hookworms as a medication-free maintenance therapy for ulcerative colitis, an inflammatory bowel disease. Malaghan has similar trials in development for perennial hay fever and a chronic, allergic inflammatory disease of the oesophagus.
Nature of science
Sometimes organisms scientists are studying are difficult or impossible to obtain. In this case, they use something else that will work in the same way to give the same results. In this study, the scientists at Malaghan use a New Zealand mouse version of hookworm. It responds in the same way as the human hookworm so can be used in the study.
The scientific community is a global partnership – scientists like to use their research to help people globally.