The gut and oral microbiomes play a crucial role in determining the severity of reactions in individuals with peanut allergies. This may clarify why reactions can vary greatly in intensity among allergic individuals.

According to Rodrigo Jimenez Sais from the Autonomous University of Madrid, “The central question is why some individuals experience more severe allergic reactions than others.”

A peanut allergy arises when the immune system incorrectly identifies proteins from peanuts as harmful, leading to an excessive production of specific antibodies. This immune response can result in symptoms like itching, swelling, and nausea, or in severe cases, anaphylaxis—a life-threatening condition characterized by breathing difficulties.

Since various microbiomes significantly influence our immune systems, Jiménez-Saiz and his team hypothesized that body microorganisms could affect allergy severity.

To test this, they administered peanuts to three groups of non-allergic mice: germ-free mice without a microbiome, mice with a minimally diverse microbiome, and mice with a rich, healthy microbiome.

After 40 minutes, researchers discovered that two proteins, Ara h 1 and Ara h 2, crucial for peanut allergies, were present at elevated levels in the germ-free and minimally diverse microbiome mice compared to those with a diverse microbiome.

Additionally, the mice with a diverse microbiome harbored abundant levels of a beneficial bacteria called Lotia, especially the Lotia R3 strain, which aids in digesting peanuts in the intestines.

To explore whether Lotia R3 could mitigate anaphylaxis risk, the researchers induced severe peanut allergies in another group of mice with minimal microbiome diversity.

They then introduced Lotia R3 and injected peanut paste into all subjects’ intestines. After 40 minutes, while all mice experienced anaphylaxis, those treated with Lotia R3 had an average body temperature drop of just 2%, compared to 3.5% in untreated mice—a notable difference, given that severe drops in temperature can lead to hypothermia and organ failure.

Moreover, levels of MMCP-1, an immune molecule that surges during anaphylaxis, were significantly lower in the blood of mice treated with Lotia R3. According to Mohamed Shamji from Imperial College London, “The findings are compelling. If similar immune responses occur in humans, we could anticipate a decrease in anaphylactic severity.”

In a complementary study involving 19 individuals with peanut allergies, researchers noted that those with higher peanut tolerance exhibited significantly higher levels of Lotia and considerably fewer bacteria in their saliva than those suffering from severe allergies. This indicates that the presence of these bacteria—both in the gut and oral cavity—may impact an individual’s anaphylaxis risk.

Lotia probiotics hold promise for reducing the severity of anaphylaxis during peanut allergies, according to Shamji. “There’s a significant need for such interventions,” he remarks, especially considering they could alleviate fears of accidental peanut exposure and minimize side effects during oral immunotherapy, which involves gradually introducing allergens to desensitize patients.

The research team aspires to eventually conduct a clinical trial, administering either Lotia probiotics or a placebo to participants with peanut allergies prior to their exposure to low doses of peanuts, as explained by Jimenez-Saiz.