Probiotics and immunity

Abstract

Probiotics are defi ned as live microorganisms that, when administered in adequate amounts, confer a health benefi t on the host, including the gastrointestinal tract. While this benefi cial effect was originally thought to stem from improvements in the intestinal microbial balance, there is now substantial evidence that probiotics can also provide benefi ts by modulating immune functions. In animal models, probiotic supplementation is able to provide protection from spontaneous and chemically induced colitis by downregulating infl ammatory cytokines or inducing regulatory mechanisms in a strain-specifi c manner. In animal models of allergen sensitization and murine models of asthma and allergic rhinitis, orally administered probiotics can straindependently decrease allergen-specifi c IgE production, in part by modulating systemic cytokine production. Certain probiotics have been shown to decrease airway hyperresponsiveness and infl ammation by inducing regulatory mechanisms. Promising results have been obtained with probiotics in the treatment of human infl ammatory diseases of the intestine and in the prevention and treatment of atopic eczema in neonates and infants. However, the fi ndings are too variable to allow fi rm conclusions as to the effectiveness of specifi c probiotics in these conditions.

Probióticos na avicultura

“…Os estímulos produzidos pela colonização dos probióticos são essenciais para o desenvolvimento de um sistema imunológico funcional e balanceado, incluindo a presença de linfócitos T e B na lâmina própria, assim como a expansão e maturação de IgA e também na indução de tolerância por parte dos antígenos presentes (BORCHERS et al, 2009). O uso dos probióticos favorece a resposta contra algumas vacinas, aumenta as imunoglobulinas tanto no sangue como na mucosa e estimula a maturação de linfócitos T e B (HAGHIGHI et al 2006) (Tabela 3).…”

Role of Toll-like receptors in the development of immunotolerance mediated by probiotics

“…Th2 immune responses involve IL-4, IL-5, IL-6 and IL-13 and induce humoral immunity (14) . Th17 cells are induced by IL-6 plus transforming growth factor-b (TGF-b) and secrete large amounts of IL-17 and IL-12 (7) .…”

Strategies of mucosal immunotherapy for allergic diseases

“…78 Probiotics are dietary supplements that contain beneficial bacteria such as Lactobacillus GG (LGG) and are effective in preventing early atopy in children through the modulation of intestinal microbiota. 79,80 In animal models of asthma, orally administered probiotics can strain-dependently decrease allergen-specific IgE production and modulate systemic cytokine production.…”

“…79,80 In animal models of asthma, orally administered probiotics can strain-dependently decrease allergen-specific IgE production and modulate systemic cytokine production. 78 Certain probiotics (LGG or Bifidobacterium lactis and Lactobacillus reuteri) have been shown to decrease airway hyper-responsiveness and inflammation by inducing regulatory mechanisms. 81,82 However, definitive conclusions are lacking because of the variety of experimental protocols used.…”