Extracellular molecular effectors mediating probiotic attributes

Abstract

Interest in probiotic bacteria, in the context of health and disease, is increasing and gathering scientific evidence, as is reflected by their growing utilization in food and pharma industry. As a consequence, many research effort over the past few years has been dedicated to discern the molecular mechanisms responsible for their purported attributes. Remarkably, whereas the traditional probiotic concept assumes that bacteria must be alive during their administration to exert health-promoting effects, evidence is being accumulated that supports defined bacterial secreted molecules and/or isolated surface components mediating attributed cross talk dialogue between the host and the probiotic cells. Indeed, administration of the isolated bacterial-derived metabolites or molecules may be sufficient to promote the desired effects and may represent a promising safer alternative in inflammatory disorders. Here, we summarize the current knowledge of molecular effectors of probiotic bacteria that have been involved in mediating their effects.

Microbial lysate upregulates host oxytocin

“…Specific bacterial components with health-promoting effects are termed ‘postbiotics’ and hold promise as a more precise, controlled and effective therapeutic approach compared to live probiotic cell consumption (Adams, 2010; Caselli et al, 2011; Kataria et al, 2009; Ruiz et al, 2014; Sanchez et al, 2010). The retaining of beneficial health effects and immunomodulatory properties has been described for many different postbiotic forms of Lactobacillus spp.…”

The Surface-Associated Exopolysaccharide of Bifidobacterium longum 35624 Plays an Essential Role in Dampening Host Proinflammatory Responses and Repressing Local T H 17 Responses

“…This suggests that not all immune-regulatory effects induced by B. longum 35624 are mediated solely by exopolysaccharide. The bifidobacterial cell wall is a complex arrangement of macromolecules, consisting of a thick peptidoglycan layer that surrounds the cytoplasmic membrane, which is decorated with other glycopolymers, such as (lipo)teichoic acids, polysaccharides, and proteins, all of which may influence the immune response (45,46) A few examples include the cell wall-associated proteins p40 and p75 from L. casei subsp. rhamnosus GG, the S-layer protein from Lactobacillus acidophilus, and the STp peptide from Lactobacillus plantarum (47)(48)(49).…”

Lactobacillus-derived extracellular vesicles enhance host immune responses against vancomycin-resistant enterococci

“…For example, a bacteriocin produced by lactobacilli formed pores in the membranes of pathogens and thus caused leaking of target cells [14, 15]. More recently, studies have revealed that extracellular vesicles (EVs) and associated proteins from lactobacilli can also modulate the activity of immune cells and affect host innate and adaptive immune responses [16–18]. For example, EVs from lactobacilli were found to enhance cellular TLR2/1 and TLR4 responses while suppressing TLR2/6 signaling [17].…”