NEW YORK (Reuters Health) - Early results suggest that encapsulated stool from non-allergic donors alters the immune system and increases tolerance to peanuts in peanut-allergic individuals.
A single fecal-microbiota transplant (FMT) led to a "significant increase in the threshold of reactivity to peanut at both one month and four months after treatment, showing that the effect was prolonged. This study is offering hope that microbiome interventions may be effective in food allergy," lead investigator Dr. Rima Rachid, of Boston Children's Hospital and Harvard Medical School, said in a news release.
"It was rather surprising and very interesting to see that the effect of FMT in patients who showed improvement in their threshold dose of reactivity was prolonged and persistent at four months post FMT," Dr. Rachid added in an email to Reuters Health.
"These patients only received one dose of FMT, so that was very encouraging. Larger and randomized placebo-controlled studies are needed to evaluate further the efficacy of FMT and its duration in patients with food allergy," she noted.
Dr. Rachid presented the results at the American Academy of Allergy, Asthma & Immunology (AAAAI) annual meeting.
The phase-1 open-label study included 15 people aged 18 to 33 who had allergic reactions to 100 mg of peanut (half a peanut) or less. All received FMT, derived from stool samples provided by healthy donors with no peanut allergy. Over the course of three hours, they swallowed 36 capsules.
All patients were given the option to receive the capsules administered over a period of two to three days. However, they all said they'd prefer to take the capsules over three hours, rather than return to the research unit for an additional day or two, Dr. Rachid told Reuters Health.
"This dose is very similar to the dose given for C difficile colitis. However, we think that if patients are not able to tolerate this dose in one day, it can be administered over two to three days," she said.
FMT was safe without any allergic reaction or serious adverse events reported and allowed some patients to consume more than two peanuts before reacting. That amount may be enough to eliminate concern about traces of peanut in foods, the researchers say.
While the number of participants was small, laboratory tests were consistent with the clinical results. Participants who responded to FMT showed increases in the regulatory T cells associated with immune tolerance and reductions in the T helper cells associated with allergy.
When their microbiomes were transplanted into allergy-prone mice, the mice showed similar immune changes and were protected from severe allergic reaction after a food challenge.
"We would like to proceed with phase-II randomized placebo-controlled trials, using microbial transfer therapy (MTT) in collaboration with Dr. Alexander Khoruts from the University of Minnesota," Dr. Rachid told Reuters Health.
"MTT undergoes additional cycles of purifications and is much more concentrated in bacteria, and thus contains much less fecal material. Hence the dose of capsules administered under medical supervision will be five," she noted.
"MTT can also be stored in the fridge, hence is a very attractive option for daily home administration after priming with the five capsules. We hope to start the trial in the last quarter of 2022," Dr. Rachid told Reuters Health.
SOURCE: https://bit.ly/3tcTWIe American Academy of Allergy, Asthma & Immunology Annual Meeting, presented February 26, 2022.
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