[Effects of extensively hydrolyzed protein formula on sensitization and gut microbiota in mice]

Investigating the sensitizing effects of extensively hydrolyzed protein infant formula on mice to provide evidence for the research and clinical application of infant formula.

Female BALB/c mice aged 5 weeks were randomly divided into 4 groups(n=20) by body weight: the blank control group, the positive control group, the extensively hydrolyzed group, and the unhydrolyzed group. All mice were given intragastric administration once a week. On the 29th day of the experiment, half of the mice in each group were subjected to eyeball enucleation for blood(serum) collection to detect specific IgE. On the 35th day, the remaining mice were intraperitoneally injected with 5 mg of β-lactoglobulin for challenge. Subsequently, the changes in rectal temperature and allergic symptoms were monitored; the spleens were harvested to calculate the spleen index; and the colonic contents were collected for gut microbiota detection.

After challenge, the rectal temperature of mice in the positive control group and the unhydrolyzed group decreased significantly(P<0.05), with higher allergic symptom scores; additionally, the spleen index of the positive control group increased significantly(P<0.05). The serum-specific IgE levels of mice showed a sequential decreasing trend among the unhydrolyzed group, positive control group, blank control group, and extensively hydrolyzed protein group, with significant differences observed between all groups(P<0.05). The Richness index of the extensively hydrolyzed protein group was significantly higher than that of the positive control group and the unhydrolyzed group(P<0.05). Firmicutes in the positive control group and the unhydrolyzed group was significantly lower than that in the blank control group and the extensively hydrolyzed protein group(P<0.05), while Bacteroidetes was significantly increased(P<0.05). In the unhydrolyzed group, GGB46150＿SGB63918, Heminiphilus faecis, and GGB29545＿SGB42337 were significantly higher than those in the blank control group(P<0.05), whereas Alistipes sp. DSM＿112343 and Helicobacter ganmani were significantly decreased(P<0.05). Furthermore, Bacteroidetes, GGB27792＿SGB40208, and GGB46150＿SGB63918 were positively correlated with serum-specific IgE levels(P<0.05). In contrast, Firmicutes and Lachnospiraceae bacterium was negatively correlated with serum-specific IgE levels; Candidatus＿Melainabacteria was negatively correlated with allergy symptom scores; and Tenericutes and GGB27792＿SGB40208 was negatively correlated with the spleen index(P<0.05).

Extensively hydrolyzed proteins can reduce the allergenicity of infant formula, providing a scientific evidence for preventing protein allergies in formula.