Probiotics, Prebiotics and Immunomodulation of Gut Mucosal Defences: Homeostasis and Immunopathology

Abstract

Probiotics are beneficial microbes that confer a realistic health benefit on the host, which in combination with prebiotics, (indigestible dietary fibre/carbohydrate), also confer a health benefit on the host via products resulting from anaerobic fermentation. There is a growing body of evidence documenting the immune-modulatory ability of probiotic bacteria, it is therefore reasonable to suggest that this is potentiated via a combination of prebiotics and probiotics as a symbiotic mix. The need for probiotic formulations has been appreciated for the health benefits in “topping up your good bacteria” or indeed in an attempt to normalise the dysbiotic microbiota associated with immunopathology. This review will focus on the immunomodulatory role of probiotics and prebiotics on the cells, molecules and immune responses in the gut mucosae, from epithelial barrier to priming of adaptive responses by antigen presenting cells: immune fate decision—tolerance or activation? Modulation of normal homeostatic mechanisms, coupled with findings from probiotic and prebiotic delivery in pathological studies, will highlight the role for these xenobiotics in dysbiosis associated with immunopathology in the context of inflammatory bowel disease, colorectal cancer and hypersensitivity.

Probiotics for Fibromyalgia: Study design for a pilot double-blind, randomized controlled trial.

“…The proposed mechanisms of action of probiotics include competition against the pathogenic bacteria to bind to the intestinal epithelial cells, enhancement of the intestinal epithelial barrier function, inhibition of pathogens' growth by secretion of antimicrobial peptides, and augmentation of the production of serum IgA (58,59). Probiotics may also affect the central nervous system via the gutbrain axis by: a) enhancing the production and delivery of neuroactive substances, such as gamma-amino butyric acid (GABA), serotonin, dopamine and acetylcholine; b) the vagus nerve (60); and c) decreasing pro-inflammatory cytokines, which are able to cross the blood-brain barrier and elicit mood and behavioral changes (58). For instance, some probiotics have been shown to induce an elevation of tryptophan levels in plasma (61), which is a precursor of serotonin.…”

Physiology and immunology of mucosal barriers in catfish (Ictalurus spp.)

“…44 Probiotics and prebiotics, known to positively impact mucus secretion and gut health in mammals, are increasingly added to fish diets, including catfish. 45 However, few studies have examined their impact on mucin expression, goblet cell numbers or mucus secretion (see refs. 46 for an exception to this).…”

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“…Defensins are a family of highly conserved small cysteine-rich antimicrobial peptides particularly abundant at mucosal sites where they contribute to the host defense by disrupting the cytoplasmic membrane of susceptible microorganisms (Hardy et al 2013). The probiotic E. coli Nissle strain has been shown to induce expression of human beta-defensin 2 in Caco-2 intestinal epithelial cells and this type of effect may contribute to an improved mucosal barrier and provide a means of limiting access of enteric pathogens (Ng et al 2009).…”

“…Mucin polymerization provides the structural foundation of the mucus, granting protection from pathogens, enzymes, toxins, dehydration and abrasion. Lactobacillus plantarum 299v and Lactobacillus rhamnosus GG have been shown to upregulate production of intestinal mucins (MUC 2 and MUC 3) which subvert the adherence of the enteropathogenic bacterium Escherichia coli O157:H7 to intestinal epithelial cells, consequently preventing pathogenic bacterial translocation (Hardy et al 2013).…”