Combination of heat-killed Lactiplantibacillus plantarum YIT 0132 (LP0132) and oral immunotherapy in cow's milk allergy: a randomised controlled trial

Safer and more effective cow milk (CM)-oral immunotherapy that does not induce allergic reactions has not yet been standardised. We sought to explore the efficacy and feasibility of a combination of heat-killed Lactiplantibacillus plantarum YIT 0132 (LP0132) and oral immunotherapy for treating IgE-mediated cow milk allergy (CMA). We conducted a 24-week, double-blind, randomised (1:1), two-arm, parallel-group, placebo-controlled, phase 2 trial of LP0132 intervention for treating IgE-mediated CMA in children aged 1-18 years (n=60) from January 29, 2018 to July 12, 2019 in Tokyo, Japan. Participants were randomly assigned to the LP0132 group receiving citrus juice fermented with LP0132 or to the control group receiving citrus juice without. Both groups received low-dose slow oral immunotherapy with CM. The primary outcome was improved tolerance to CM, proven by the CM challenge test at 24 weeks. Secondary outcomes were changes in serum biomarkers of serum-specific β-lactoglobulin-IgE (sIgE) and β-lactoglobulin-IgG4 (sIgG4). Exploratory outcomes included changes in serum cytokine levels and gut microbiota composition. A total of 61 participants were included. Finally, 31 children were assigned to the LP0132 group and 30 to the control group, respectively. After the intervention, 41.4 and 37.9% of the participants in the LP0132 and control groups, respectively, showed improved tolerance to CM. In serum biomarkers after the intervention, the sIgG4 level was significantly higher, and interleukin (IL)-5 and IL-9 were significantly lower, in the LP0132 group than in the control group. In the gut microbiome, the α-diversity and Lachnospiraceae increased significantly in the LP0132 group, and Lachnospiraceae after the intervention was significantly higher in the LP0132 group than in the control group. In conclusion, low-dose oral immunotherapy with modulating gut microbiota might be a safer and more effective approach for treating cow's milk allergy.