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J. J. PESTKA, Dept. of Food Science & Human Nutrition, Michigan State Univ., 234-A G. Malcolm Trout FSHN Bldg., East Lansing, MI 48824 The mammalian host responds to invading pathogens such as bacteria, fungi and viruses by both innate and acquired mechanisms . The innate immune system, the first line of defense, senses microbial invaders via a set of evolutionarily conserved receptors that recognize pathogen-associated molecular patterns (PAMPs). Recognition of PAMPs initiates activation of signaling events that induce expression of effector molecules like cytokines and costimulatory molecules. These molecules subsequently drive acquired (ie specific) immune responses such as immunoglobulin production and T cell killing. The toll-like receptors (TLRs) are one major group of PAMP-sensors. The primary cell types that express known TLRs are the mononuclear phagocytes which include macrophages, monocytes and dendritic cells. Activation of TLRs by bacterial components might be a key factor for regulation of the immune response and to mediate a link between the innate and the adaptive immune function. Several lines of evidence suggest differential activation by probiotoc bacteria have the potential to play an immunoregulatory role in the T helper 1 (Th1) cell, Th2 and Th3 balance that can poise a host towards a Th2 (allergic) or Th1 response (inflammatory). Specifically, in vitro, ex vivo and in vivo evidence exists demonstrating that various strains/species of lactobacilli, streptococci and bifidobacteria can alter both cytokine production and/or differentiation of mononuclear phagocytes. Further elucidation of the underlying mechanisms for these effects and subsequent clinical studies will be necessary for developing probiotic supplements or foods that have the potential for ameliorating food allergy.
Session 24, Probiotics in health: Their potential against allergic diseases
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