Probiotics: effects on immunity

The gastrointestinal tract functions as a barrier against antigens from mic roorganisms and food. The generation of immunophysiologic regulation in the gut depends on the establishment of indigenous microflora. This has led to the introduction of never therapeutic interventions based on the consumpti on of cultures of beneficial live microorganisms that act as probiotics. Am ong the possible mechanisms of probiotic therapy is promotion of a nonimmun ologic gut defense barrier, which includes the normalization of increased i ntestinal permeability and altered gut microecology. Another possible mecha nism of probiotic therapy is improvement of the intestine's immunologic bar rier, particularly through intestinal immunoglobulin A responses and allevi ation of intestinal inflammatory responses, which produce a gut-stabilizing effect. Many probiotic effects are mediated through immune regulation, par ticularly through balance control of proinflammatory and antiinflammatory c ytokines. These data show that probiotics can be used as innovative tools t o alleviate intestinal inflammation, normalize gut mucosal dysfunction, and down-regulate hypersensitivity reactions. More recent data show that diffe rences exist in the immunomodulatory effects of candidate probiotic bacteri a. Moreover, distinct regulatory effects have been detected in healthy subj ects and in patients with inflammatory diseases. These results suggest that specific immunomodulatory properties of probiotic bacteria should be chara cterized when developing clinical applications for extended target populati ons.