Mechanisms of Probiotic Immunomodulatory Effects

Beneficial effects of probiotic consumption in the prevention and treatment of several gastrointestinal diseases, such as inflammatory bowel diseases, antibiotic associated-diarrhoea, neonatal necrotizing enterocolitis, irritahle bowel syndrome, Helicobacter pylori infection, as well as food allergies and intolerances, have been clearly assessed (Sanders et al. 2013). Furthermore, probiotics are effective in reducing cholesterol levels and lowering blood pressure (Kumar et al. 2012). However, molecular mechanisms underlying strain-specific probiotic action and the identity of effector molecules (peptidoglycan, teichoic acid, cell surface polysaccharides, extracellular proteins) still remain to be fully elucidated. 

As to surface proteins, the S-layer protein SlpA of Lact. acidophilus was involved in the modulation of dendritic cells (DCs) and T-cell functions, as it directly interacted with a specific DCs receptor. In fact, the deletion of slpA in mutant strains led to a reduced DCs binding capacity and to an enhanced proinflammatory cytokine production (Konstantinov et al. 2008). Moreova-, tbe amount of SlpA in different Lact. acidophilus strains was related to adhesion to Caco-2 cells as well as to the release of IL-12 from DCs (Ashida et al. 2011). 

Recently, synbiotics, that are suitable combinations of prebiotics and probiotics, have been developed with the aim of further promoting well-being and health (Kolida and Gibson 2011). 

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