probiotic & immunity

Probiotics and immunity
ANDREA T. BORCHERS1
, CARLO SELMI2,3, FREDERICK J. MEYERS4
, CARL L. KEEN1
, and M. ERIC GERSHWIN2
1
Department of Nutrition, Allergy and Clinical Immunology, University of California at Davis, Davis, CA, USA
2
Division of Rheumatology, Allergy and Clinical Immunology, University of California at Davis, Genome and Biomedical Sciences Facility,
451 Health Sciences Drive, Suite 6510, Davis, CA 95616, USA
3
Department of Internal Medicine, IRCCS Istituto Clinico Humanitas, University of Milan, Milan, Italy
4
Department of Internal Medicine, University of California at Davis Medical Center, Sacramento, CA, USA
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.
Key words: microfl ora, nutritional immunology, dietary
supplement, innate immunity, vaccine