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Purpose: The incidence and prevalence of food allergy have sharply risen over the past several decades. Oral administration of probiotic stains has been proven as a safe and effective method to control food allergy. In this study, it aims to comprehensively investigate the anti-allergic effect of Lactobacillus plantarum JC7. Methods: Balb/c mice were randomly divided into three groups and received OVA (20 µg/mouse, intraperitoneal injection), L. plantarum JC7 (2 × 108 CFU/mouse, intragastric administration) + OVA (20 µg/mouse, intraperitoneal injection) or 0.9% saline (intragastric administration) for 3 weeks. Body weight was monitored weekly, and allergic reactions were evaluated after challenge of OVA. Serum levels of OVA-specific immunoglobulins and various cytokines were tested using ELISA, and the cecum microbiota was analysed by 16S rRNA sequencing to explore the relationships between these indicators and OVA-induced food allergy. Western blotting was used to identify the expression levels of phosphorylated IκBα and nuclear factor kappa B p65. Results: OVA-sensitised mice showed mitigation of respiratory manifestations, alleviation of lung inflammation and congestion, and the presence of an intact intestinal villus structure. Furthermore, OVA-specific immunoglobulin E (IgE), OVA-specific-IgG1, and plasma histamine levels were declined in mice treated with L. plantarum JC7 than in OVA-sensitised mice. In addition, interferon-γ (IFN-γ) and interleukin 10 (IL-10) levels were significantly increased, while IL-4 and IL-17A levels were clearly decreased in mice that had undergone oral administration of L. plantarum JC7, compared with OVA-sensitised mice. These findings indicated imbalances of T helper cell type 1 (Th1)/Th2 and regulatory T cells (Treg)/Th17, which were confirmed by quantitative polymerase chain reaction (PCR). Western blotting demonstrated that the expression levels of phosphorylated IκBα and nuclear factor kappa B p65 were significantly increased in OVA-sensitised mice, but these changes were partly reversed after treatment with L. plantarum JC7. Oral administration of L. plantarum JC7 increased the richness, diversity, and evenness of cecum microbiota, characterised by higher Bacteroidetes abundance and lower Firmicutes abundance. Additionally, the intestinal microbial community composition was significantly altered in the OVA-sensitised group, indicating a disordered intestinal microbiota that was restored by the oral administration of L. plantarum JC7. Conclusion: Overall, L. plantarum JC7 can prevent food allergy by rectifying Th1/Th2 and Treg/Th17 imbalances, combined with modifications of disordered intestinal microbiota. [ABSTRACT FROM AUTHOR]

Food allergy is an abnormal immune reaction triggered by food protein antigens. Relevant studies have suggested that probiotic supplementation was with the potential to alleviate food allergy. This study aimed to explore the effects of Lactobacillus plantarum A56 on the alleviation of ovalbumin (OVA)-induced food allergy via immunomodulatory function, antioxidation, and modification of intestinal microbiota. Balb/c mice were sensitized with OVA (20 µg/mouse) by intraperitoneal injection for 3 weeks and accompanied by oral administration of L. plantarum A56 (109 CFU/mL), subsequently with orally challenged twice by OVA at 50 mg/mL for 1 week. The results showed that oral supplementation of L. plantarum A56 could effectively relieve allergic symptoms of mice, and decreased OVA-specific IgE and IgG1 concentrations. It also declined interleukin (IL)-4 level, raised interferon-γ (IFN-γ) in serum, and splenocyte supernatant, and the qPCR results were consistent with above results. Moreover, L. plantarum A56 treatment also fortified superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) levels, and reduced malondialdehyde (MDA) level in serum. The increased nuclear factor (erythroid-derived 2)-like 2 (Nrf2) and forkhead box O1 (Foxo1) expression indicated that L. plantarum A56 exerted antioxidation through Nrf2-Foxo1 pathway. In addition, L. plantarum A56 treatment elevated Bacteroidetes richness, ASV/OTU number, species diversity, etc. Notably, Spearman correlation analysis indicated that Bacteroidetes displayed obviously negative correlation with IgE and IgG1, but Actinobacteria and Acidobacteria exhibited significantly positive correlation with IgG1 and IgE. Collectively, these results suggested that L. plantarum A56 could alleviate OVA-induced food allergy by regulating Th1/Th2 imbalance, antioxidation, and modulating intestinal microbiota. Balb/c mice were used to construct an OVA-induced animal model to explore the effects of Lactobacillus plantarum A56 on the alleviation of OVA-induced food allergy in a Balb/c model via immunomodulatory function, antioxidation, and modification of intestinal microbiota composition. The results clearly showed that oral supplementation of L. plantarum A56 could effectively relieve allergic symptoms of mice, and decreased IgE and IgG1 levels. It also declined IL-4 level, raised IFN-γ, and the detection results at transcription level were consistent with above results. Moreover, L. plantarum A56 treatment also fortified SOD and GSH-Px levels and reduced MDA level in serum. The increased Nrf2 and Foxo1 expression levels indicated that L. plantarum A56 exerted antioxidation through Nrf2-Foxo1 pathway. In addition, the intestinal microbiota composition was reshaped after oral administration of L. plantarum A56. [Display omitted] [ABSTRACT FROM AUTHOR]