Hope in small doses for chil­dren suf­fer­ing from peanut al­lergy

A small study shows im­munother­apy can put peanut al­lergy into re­mis­sion, but it is not a cure yet.

Cosmos - - Digest -

Peanut but­ter sand­wiches at child­care are a thing of the past thanks to an alarm­ing surge in peanut al­ler­gies over re­cent decades. But a new study has found that for some chil­dren the al­lergy can be coaxed into re­mis­sion.

The prospect of a cure for peanut al­lergy is tan­ta­lis­ing, not least be­cause even small amounts can spark a po­ten­tially lethal re­ac­tion. Peanut al­lergy also has the pesky habit of stick­ing around – only 15% to 20% of kids grow out of it, com­pared with about 85% of kids with milk or egg al­ler­gies.

One ap­proach be­ing in­ves­ti­gated to quell peanut al­ler­gies is oral im­munother­apy. This in­volves feed­ing al­ler­gic kids a daily dose of peanuts, start­ing with tiny amounts and care­fully in­creas­ing the dose over a pe­riod of months.

Oral im­munother­apy has been shown to de­sen­si­tise most chil­dren to peanuts, but usu­ally only if taken re­li­giously. Skip a day or two and the prob­lem comes roar­ing back. Only a hand­ful of kids ever man­age to build a tol­er­ance that per­sists af­ter a cou­ple of weeks of go­ing with­out peanuts.

Mimi Tang and col­leagues at the Mur­doch Chil­dren’s Re­search In­sti­tute in Mel­bourne, Australia, won­dered whether they could im­prove these odds by adding a pro­bi­otic into the mix.

“The in­testi­nal mi­cro­biome is re­ally im­por­tant in pro­gram­ming healthy im­mune re­sponses,” Tang says.

Lifestyle fac­tors, such as diet and hy­giene, that disrupt gut mi­crobes in young chil­dren could be part of the rea­son for ris­ing rates of food al­ler­gies. But pro­bi­otics might com­pen­sate.

“I though the im­mune sys­tem might ben­e­fit from a bit of a help to point it in the right di­rec­tion. That’s what the pro­bi­otic is do­ing,” Tang adds.

The team used a strain of Lac­to­bacil­lus rham­no­sus shown to bump up pro­duc­tion of im­mune cells that help to put a brake on overzeal­ous im­mune re­ac­tions.

That orig­i­nal trial ended in 2011, and 82% of kids – 23 of 29 – treated with the peanut-pro­bi­otic combo had no re­ac­tion when fed peanuts fol­low­ing two weeks’ ab­sti­nence. This com­pared to just one of 28 given a mock im­munother­apy.

The cur­rent study, pub­lished in the Lancet Child and Ado­les­cent Health jour­nal, is a fol­low-up to that trial, track­ing how kids fare years af­ter they stop daily treat­ment.

Two-thirds of the kids who were treated were still prac­tis­ing oral im­munother­apy four years later.

The real test, though, was whether the tol­er­ance held. Twelve par­tic­i­pants who had been treated – 10 of whom had tested un­re­spon­sive im­me­di­ately fol­low­ing treat­ment – un­der­went an oral food chal­lenge af­ter go­ing cold turkey for eight weeks. Seven of these were un­re­spon­sive, com­pared to just one of 15 placebo kids.

“[In] no other study of oral im­munother­apy have in­di­vid­u­als been able to in­gest the al­ler­gen with this in­fre­quency and re­main non-re­ac­tive,” writes Matthew Green­hawt of the Univer­sity of Colorado School of Medicine in an ac­com­pa­ny­ing com­men­tary on the study.

But was the pro­bi­otic the cru­cial in­gre­di­ent? From this re­search, it is not cer­tain, says Robert Loblay, di­rec­tor of the Al­lergy Unit at Royal Prince Al­fred Hospi­tal in Syd­ney: “The trou­ble is it’s not clear what was re­spon­si­ble for the ef­fect they ob­served.” To know if the pro­bi­otic boosted the im­munother­apy’s ef­fec­tive­ness, he says, a head-to­head com­par­i­son with a peanut-only im­munother­apy is needed.

Tang and her team are em­bark­ing on just such a study, en­rolling 200 chil­dren across three hos­pi­tals. If the pro­bi­otic does turn out to have a gen­uine ef­fect, ad­di­tional stud­ies will also be re­quired to fig­ure out ex­actly how and why it works.

As for a cure: “We’re quite a long way away, un­for­tu­nately, but we’re work­ing to­wards it slowly,” Tang says.

CREDIT: BRUNO CRESCIA / GETTY IMAGES

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