Effets des probiotiques sur le système immunitaire : mécanismes d'action potentiels

One of the most important properties of probiotic micro-organisms relies upon their immunomodulation capacity. Depending on the host (healthy individuals or those with pathological states linked to immune dysfunction such as allergy or inflammatory bowel disease, IBD), their effects can be strikingly different: on the one hand, in normal condition, most probiotic micro-organisms stimulate innate immune defences (phagocytosis, pro-inflammatory cytokines) playing a positive role in shortening mild infectious diseases or strengthening vaccinal response. On the other hand, beneficial anti-inflammatory effects have also been emphasized in various pathological situations (allergy, IBD) with selected strains of probiotics. It is important to stress the specificity of a probiotic effect as each strain in a bacterial species potentially behaves differently. Numerous studies are presently being conducted to identify the mechanisms involved in these beneficial effects. Immuno-stimulant effects in healthy human subjects especially involve more bacterial compounds recognizing invariant receptors on immune cells and anti-inflammatory effects could be related to the release of secreted metabolites (butyrate, NO) or bacterial fragments (lipoteichoic acid, CpG-enriched DNA sequences).