The potential role of adherence factors in probiotic function in the gastrointestinal tract of adults and pediatrics: a narrative review of experimental and human studies

Abstract

Numerous studies point to the important role of probiotic bacteria in gastrointestinal health. Probiotics act through mechanisms affecting enteric pathogens, epithelial barrier function, immune signaling, and conditioning of indigenous microbiota. Once administered, probiotics reach the gastrointestinal tract and interact with the host through bacterial surface molecules, here called adhesion factors, which are either strain- or specie-specific. Probiotic adhesion, through structural adhesion factors, is a mechanism that facilitates persistence within the gastrointestinal tract and triggers the initial host responses. Thus, an understanding of specific probiotic adhesion mechanisms could predict how specific probiotic strains elicit benefits and the potential of adherence factors as a proxy to predict probiotic function. This review summarizes the present understanding of probiotic adherence in the gastrointestinal tract. It highlights the bacterial adhesion structure types, their molecular communication with the host and the consequent impact on intestinal diseases in both adult and pediatric populations. Finally, we discuss knockout/isolation studies as direct evidence for adhesion factors conferring anti-inflammatory and pathogen inhibition properties to a probiotic. What is known : Probiotics can be used to treat clinical conditions. Probiotics improve dysbiosis and symptoms. Clinical trials may not confirm in vitro and animal studies. What is new : Adhesion structures may be important for probiotic function. Need to systematically determine physical characteristics of probiotics before selecting for clinical trials. Probiotics may be genetically engineered to add to clinical efficacy.

Probiotic Properties of Lactococcus lactis Strains Isolated from Natural Whey Starter Cultures

“…The adhesion of probiotics to the intestinal epithelium is essential for their beneficial effects. They exert a positive regulation of the immune system, interacting with the cells of the immune system present in the gut-associated lymphoid tissue and counteracting the onset of massive inflammatory phenomena [ 58 ]; furthermore, they are able to produce bioactive products, such as antimicrobial peptides [ 55 ], short-chain fatty acids [ 59 ], and other metabolites, in proximity to the host cells, and to strengthen the gastrointestinal barrier through the production of tight junctions. In particular, by adhering to the intestinal epithelium, probiotics protect against pathogen attack through a competitive exclusion mechanism [ 60 ].…”

Probiotics: Health benefits, food application, and colonization in the human gastrointestinal tract

“…To be effective, a potential probiotic should possess the ability to adhere to and colonize the intestinal cell wall. This is crucial for initiating direct interactions between probiotics and host cells, ultimately resulting in the competitive exclusion of pathogens and the modulation of host cell responses (Gorreja & Walker, 2022). Probiotics must possess significant antimicrobial activity against pathogenic bacteria while remaining safe for human consumption (Acharjee et al, 2022).…”

The potential of short-chain fatty acid epigenetic regulation in chronic low-grade inflammation and obesity

“…On the other hand, the fact that in vivo human studies do not demonstrate such strong translatability of mice studies, suggests that the amounts and viability of bacteria may be affected by several factors of the gastro-intestinal (GI) tract. Effective encapsulation and the ability of the probiotic to adhere to the gut epithelium play also an important role in this context ( 104 – 106 ). Recently, a lot of attention is directed towards bacterial exopolysaccharides (EPSs), which can be used as an effective carrier protecting from GI stressors, increasing muco-adhesion but also a synergistic compound to promote gut homeostasis ( 107 – 109 ).…”