The Beneficial Effect of Lactobacillus Gasseri PM-A0005 and Its Immunoregulatory Protein PMA5P40 on Milk-Induced Allergic Enteritis

Food allergy is one of the common allergic diseases in the world. Probiotics are shown to promote the endogenous host defense and modulate the host’s immune responses to potentially harmful antigens. In this study, we first established a mouse model of food allergey by i.p. sensitization with OVA or β-lactoglobulin, and were orally challenged with protein allergen, OVA, or β-lactoglobulin in BALB/c mice. We found that the body weights and body temperatures immediately after food allergen challenged were significantly decreased as compared with the control mice. And the symptoms of food allergy, the levels of total IgE, allergen-specific IgE, IgG1, IgG2a, IgA of sera and the levels of IgE, IgA, IL-4 and IL-17 of intestine lavage fluids (ILF) of food allergen mice were significantly increased as compared with the control mice. After oral administration with 10⁷ CFU Lactobacillus gasseri PM-A0005 (L. gasseri ) at the same time during food allergen sensitization and challenge, the body temperature, body weight, the levels of antigen-specific IgA of sera, and IL-10 concentration of the ILF, and the levels of IL-10, IL12, INF-γ, TGF-β of the culture medium and the cellular numbers of CD11c⁺CD103⁺, CD11b^-CD8a⁺ dendritic cells (DCs), CD4⁺FoxP3⁺ (Treg cells), CD4⁺T bet⁺ (TH1 cells) in the Peyer's patches and draining lymph nodes of L. gasseri-treated mice were significantly increased as compared with the non-treated food allergy mice. In contrast, the food allergy symptoms, the levels of antigen-specific IgE, IgG1 of sera and the levels of total IgE, antigen-specific IgE, IgG1, α1-antitrypsin, IL-17, IL-6 of the ILF and the concentrations of TNF-α, IL-23, IL-6 of the culture medium and the cellular numbers of CD4⁺RORγt⁺ (TH17 cells) , CD4⁺GATA3⁺ (TH2 cells), lymphocytes proliferation and the intestinal inflammation of L.gasseri-treated mice with food hypersensitivity were significantly decreased as compared with the non-treated control mice. To further explore the anti-allergy effect of L. gasseri of dendritic cells (DCs) on food allergy development, bone marrow-derived dendritic cells (BMDCs) isolated from naïve mice were stimulated for 24 hrs with recombinant of L. gasseri. The PMA5P40-primed BMDCs were collected and adoptive transfer to mice sensitized and challenged with food allergens. These finding suggested that L. gasseri and recombinant of protein PMA5P40 have anti-allergy effect on the mice sensitized and challenged with food allergens, such as OVA and cow’s milk. And this anti-allergic effect may be mediated through the tolergenic effect of dendritic cells that enhance immune-regulatory effect on T and B lymphocytes, which may have clinical application in patients suffered with food allergy.