A non-invasive, low dose vaccine that redirects an uncomfortable and sometimes life-threatening immune response to peanuts might one day save human lives.
Trials based on mice have delivered promising results, suggesting we’re not only well on our way to having a simple nasal vaccine that could ‘turn off’ this common allergy, but could finally understand how it develops in the first place.
A study conducted by researchers from the University of Michigan found it took just two weeks for peanut-sensitive mice to develop a tolerance to the food after a monthly dose of a nasal spray emulsion over a three month period.
“Right now, the only FDA approved way to address food allergy is to avoid the food or suppress allergic reactions after they have already started,” says the study’s lead author and pharmacologist Jessica O’Konek.
“Our goal is to use immunotherapy to change the immune system’s response by developing a therapeutic vaccine for food allergies.”
Hormones called cytokines are responsible for kicking off various functions that help our body protect itself from invaders and toxic materials.
White blood cells called helper T cells produce two varieties of these hormones. Th1-type cytokines seemed to evolve to destroy things that get inside cells, such as bacteria and protozoa, and are often behind autoimmune responses.
For dangerous pathogens outside of cells, such as parasites, Th2-type cytokines can call on mast cells to release things such as histamine in an effort to expel the invaders.
The two categories of cytokines also counteract one another, ensuring they don’t get out of hand.
Allergies seem to be the result of a hyped up Th2-type cytokine response overwhelming Th1-type, making this pathway a key focus for immunologists.
It’s hypothesised that a failure to be exposed to certain materials early in life might promote Th2 immune responses over Th1, leading some to believe a pristine, super-hygienic world might be at least partially responsible for allergies.
This has led some to experiment with slowly exposing individuals over time to increasing doses of peanuts to rebalance the two responses.
While there has been some success with this approach, such as in experiments that couple peanuts with probiotics, a simple, low-dose vaccine would be a lot easier to deliver.
This nasal-spray vaccine was designed to bump up the Th1 antibody response in order to dampen the Th2 pathway.
“We’re changing the way the immune cells respond upon exposure to allergens,” says O’Konek.
“Importantly, we can do this after allergy is established, which provides for potential therapy of allergies in humans.”
To see if it works as predicted, the researchers tested the emulsion on mice that were sensitised to respond to peanuts by developing breathing difficulties and itchy skin.
Sure enough, a few weeks after several squirts on their nasal membranes, they showed a significant decrease in their hypersensitivity. Analysis of their cytokine secretions also showed significant reduction in their Th2 response.
Of course, proof of concept in mice doesn’t mean it’ll be effective in humans, even if the allergic responses in each animal are virtually the same – but these results are very encouraging.
The next step will be to do several rounds of clinical trials to ensure safety and efficacy.
If this works out, it would be amazing – a short course of a nasal spray would be a great way to prevent peanut allergies in children.
As many as 3 percent of children have some sort of allergic response to peanuts.
About one in five will grow out of it, but it still leaves a number of adults who have to avoid coming into contact with a food many of us love to eat, or risk distressing symptoms.
While rare, peanut allergies make up the bulk of all food allergy deaths.
Hopefully we won’t have to wait too long for the next stage in testing for this revolutionary treatment.
This research can be found in the Journal of Allergy and Clinical Immunology.