Features

Peanut allergies cracked?

12 January 2018

Researchers in Australia have made a discovery that raises hopes for the treatment of peanut allergy – a potentially lethal threat to many. We delve deeper with lead researcher, Professor Mimi Tang.

Peanuts

During the summer a small glimmer of hope appeared on the horizon for people with a peanut allergy when researchers at the Murdoch Children’s Research Institute in Melbourne, Australia, said they had made a breakthrough in managing the condition (Hsiao, et al, 2017).

The researchers, led by Professor Mimi Tang, set out to test the potential of oral immunotherapy (giving small doses of an allergen in a bid to desensitise the immune system) as a treatment. They changed tack when they wondered what would happen if they added a probiotic. So in the 2013 study, which involved 62 children with a peanut allergy, they gave one group a probiotic and peanut oral immunotherapy (PPOIT) treatment, and the other a placebo. After 18 months, 82% of the children given the PPOIT developed short-term tolerance to peanut, compared to just 4% in the placebo group. Vitally, the recent follow-up study four years later in 48 of the children, found that 80% of the children who responded to PPOIT initially were still eating peanuts in varying amounts as part of their normal diets (16/20). And 70% who had a further challenge test demonstrated long-term tolerance.

The study is now changing the way clinicians think about managing peanut allergy, and Professor Mimi Tang, is hoping it will have far-reaching consequences:

 

What was the impetus for the research?

We have seen some immunotherapy treatments achieve lasting effects for other allergic conditions. You could almost call them a cure. For example, immunotherapy for insect stings or grass pollen appears to have achieved long-term remission for a large number of individuals. One of the most researched approaches in food allergies has been oral immunotherapy. This involves giving patients increasing amounts of the food. But while it seemed to be good for desensitising people, it was uncertain that it could induce any lasting remission.

 

What is the difference between desensitisation and lasting remission?

Desensitisation is where you suppress the reaction without changing the underlying allergy. You just change the immune reactivity. So if treatment is stopped for a while and then the patient eats the allergen, they are likely to have an allergic reaction. On the other hand, ‘tolerance’ is a word we use with caution. True tolerance would mean permanent removal of the allergy without the need to continue in taking the allergen. We don’t know if that is achievable in food allergy. So for now we prefer the term ‘sustained unresponsiveness’. This means that you still have a degree of protection even if you stop treatment for weeks, months, or longer. Oral immunotherapy seems to be good for desensitisation, but we wanted to find something that could induce a long-lasting remission (sustained unresponsiveness) or switch off the disease altogether.

 

Is that how the idea of the probiotic came about?

I think that immunotherapy just reminds the immune system to react in the usual way to the allergen like a booster vaccine. We thought we needed to do something else to encourage the immune system to respond differently. So we added an immune modifying agent. We combined the standard oral immunotherapy for peanuts with a probiotic. Both were taken at the same time, as a powder, every day for 18 months. The probiotic was a fixed dose, whereas the peanut immunotherapy started very low and gradually built up to the equivalent of around eight peanuts. At the end we tested for desensitisation. We then stopped the treatment for between two to six weeks, and tested again for sustained unresponsiveness.

 

How reliable were the impressive results?

That two- to six-week period between stopping treatment and the sustained unresponsiveness test was relatively short. Some individuals may just have been desensitised. So we did the 2017 follow-up study of children from the 2013 trial to see if the original protection had persisted. We asked them about their peanut intake, their reactions to peanuts, and gave them a skin-prick test. They also had the option to take part in a food challenge where they stopped eating peanuts for at least eight weeks. This revealed that anybody who responded to the probiotic peanut therapy in the first instance was likely to have retained protection four years later. Nobody would claim this is a cure, but it’s exciting because it’s the first time any treatment has demonstrated long-term remission after immunotherapy.

 

Where do you go from here?

We are now running a large trial that compares probiotic and peanut therapy with just peanut therapy alone. We’re also running an open study to confirm the findings of our 2013 trial. If our data are repeated and confirmed, and we show it’s as effective in other forms of food allergy, this therapy could be rolled out into a clinical setting in the next decade. It could change the way we manage food allergy. And we really need something, because the food allergy burden is out of control. Fingers crossed, if it pans out, this will be a major breakthrough.

  • Professor Mimi Tang is group leader of allergy and immune disorders, Murdoch Children’s Research Institute, Australia.

Allergy in the UK

  • An estimated 1% to 2% of adults and 5% to 8% of children have a food allergy – that’s around two million people
  • Up to 1 in 55 children has a peanut allergy
  • Hospital admissions for children with food allergies have risen 700% since 1990

(Food Standards Agency, 2016)


Food allergy facts

  • Food allergies may trigger anaphylactic shock, which can be fatal if not treated immediately, usually with an adrenaline injection
  • There is currently no cure for food allergies. Treatments are being tested, but the only reliable way to prevent a reaction is to avoid the food
  • Most children grow out of allergies to eggs, milk, wheat and soya by about the age of five, as their guts and immune systems mature
  • They are unlikely to grow out of allergies to peanuts, seafood, fish and tree nuts
  • Allergies run in families: children whose parents or a sibling have an allergic condition are at a higher risk of developing one. Though it may not be the same one.

(NHS Choices, 2014)

 

Picture credit | Getty


References

FSA. (2016) Allergy basics and stats. See: bit.ly/2AtiPUb (accessed 4 December 2017).

NHS Choices. (2014) Food allergy and intolerance myth buster. See: bit.ly/2ByJRc5 (accessed 4 December 2017).

Tang ML, et al. (2015) Administration of a probiotic with peanut oral immunotherapy: a randomized trial. The Journal of Allergy and Clinical Immunology 135(3): 737-44.

Hsiao KC, et al. (2017) Long-term clinical and immunological effects of probiotic and peanut oral immunotherapy after treatment cessation: four-year follow-up of a randomised, double-blind, placebo-controlled trial. The Lancet Child & Adolescent Health 1(2): 97-105.

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