title: Novel Mechanisms Underlying the Therapeutic Effect of Glycomacropeptide on Allergy: Change in Gut Microbiota, Upregulation of TGF-β, and Inhibition of Mast Cells.
abstract: BACKGROUND
  The prevalence of allergic diseases is globally increasing. We have previously described that glycomacropeptide (GMP), a bioactive milk peptide, has therapeutic value in experimental models of skin hypersensitivity, anaphylaxis, and asthma, as it prevents an excessive T helper type 2 cell immune response. The aim of this study was to analyze the effect of GMP on key elements directly involved in the development or control of allergy, in order to improve the precise knowledge about its mechanism of action.
  
  
  METHODS
  Rats were systemically sensitized with ovalbumin and orally treated with GMP. Levels of Lactobacillus, Bifidobacterium, and Bacteroides were analyzed in their feces. Splenocytes were isolated and the production of transforming growth factor (TGF)-β by allergens was measured. Intradermal skin reactions were developed to evaluate in vivo activation of mast cells. Peritoneal mast cells were isolated and activated by the allergen, and histamine secretion was determined.
  
  
  RESULTS
  GMP administration increased the amount of intestinal Lactobacillus and Bifidobacterium of allergen-sensitized animals after 3 days of treatment. The increase in Bacteroides was also significant, but only after 17 days of GMP administration. Ten days after treatment cessation, Lactobacillus and Bacteroides were still elevated. GMP intake also elevated the production of TGF-β in the splenocytes of sensitized animals. In addition, treatment with GMP attenuated mast cell activation by the allergen and inhibited histamine secretion, without affecting the number of mast cells.
  
  
  CONCLUSIONS
  The prebiotic action of GMP on allergy-protective microbiota, an increase in TGF-β production, and a reduction in mast cell response to allergens are novel mechanisms that explain the antiallergic activity of GMP.
authors.affiliation: Department of Microbiology, Basic Science Center, Autonomous University of Aguascalientes, Aguascalientes, Mexico.
authors.forename: Mariela
authors.initials: M
authors.lastname: Jiménez
authors.forename: Daniel
authors.initials: D
authors.lastname: Cervantes-García
authors.forename: Yualli Haydee
authors.initials: YH
authors.lastname: Muñoz
authors.forename: Alejandra
authors.initials: A
authors.lastname: García
authors.forename: Luis Miguel
authors.initials: LM
authors.lastname: Haro
authors.forename: Eva
authors.initials: E
authors.lastname: Salinas
mesh_terms: D000818:Animals; D002364:Caseins / Q000494:pharmacology*; D004195:Disease Models, Animal; D005243:Feces / Q000382:microbiology; D000069196:Gastrointestinal Microbiome; D006636:Histamine Release / Q000187:drug effects; D006967:Hypersensitivity / Q000188:drug therapy / Q000209:etiology* / Q000378:metabolism*; D007114:Immunization; D008407:Mast Cells / Q000276:immunology* / Q000378:metabolism*; D010446:Peptide Fragments / Q000494:pharmacology*; D051381:Rats; D012867:Skin / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D016212:Transforming Growth Factor beta / Q000378:metabolism*
chemical_list: D002364:Caseins; D010446:Peptide Fragments; D016212:Transforming Growth Factor beta; C065989:caseinomacropeptide