Mechanism
Immune Modulation:
The gut microbiota modulates the immune system via the production of molecules with immunomodulatory and anti-inflammatory functions that are capable of stimulating immune cells.The adaptive immune response depends on B and T lymphocytes, which bind to specific antigens.
In contrast, the innate system responds to common structures, called pathogen-associated molecular patterns (PAMPs), shared by a majority of pathogens. The primary response to pathogens is produced by pattern recognition receptors (PRRs), which bind to PAMPs. Consequently, PRRs comprise TLRs, which are transmembrane proteins that are expressed on various immune and nonimmune cells, such as B-cells, natural killer cells, DCs, macrophages, fibroblast cells, epithelial cells, and endothelial cells.
Enzymatic Activity:
Probiotics interact with bile acids in the gut lumen, modifying bile acid metabolism and in turn influencing cholesterol absorption. Bile salt hydrolase (BSH) is an enzyme produced by bacterial species of several genera associated with the gastrointestinal tract and by most of the known probiotics; this enzyme may participate in the first reaction of the deconjugation of biliary salts.
With respect to probiotics for the prevention of pediatric diarrhea and antibiotic-associated diarrhea, it has been described that probiotics can restore microbial balance and thus inhibit the proliferation of pathogens.
In addition, probiotics increase intestinal cell adhesion and mucin production and modulate the activity of gut-associated lymphoid tissue and the immune system. Similarly, probiotic metabolites are able to interact with the brain-gut axis and play a role in behavior.
