Probiotic-Derived Bioactives in Gut Immune and Barrier Homeostasis

The field of nutritional science increasingly recognizes the gut microbiota as a key modulator of metabolic and immune homeostasis. Within this context, the study of biomolecules produced by probiotic microorganisms has emerged as a promising frontier in understanding diet-microbe-host interactions. In this Research Topic, probiotic-derived bioactives refer specifically to structurally characterised peptides, exopolysaccharides and S-layer proteins produced by or associated with probiotic strains during growth or fermentation. The topic focuses on purified or otherwise well-characterised molecules or molecular fractions, which may be studied independently or alongside their producing strains, rather than whole microbial preparations or undefined mixtures. Recent findings suggest that these molecules influence mucosal immunity and epithelial barrier integrity, contributing to overall gut and systemic health. However, despite progress in identifying individual bioactive components, the causal pathways linking structural features to biological effects remain incompletely understood. This Research Topic aims to elucidate the nutritionally relevant roles and molecular mechanisms of probiotic-derived peptides, exopolysaccharides and S-layer proteins in modulating gut immunity and epithelial barrier function. It seeks to move beyond traditional probiotic concepts by focusing on structurally defined molecules with documented bioactive properties, clearly differentiated from whole-cell probiotic interventions, undefined microbial extracts and inactivated microbial preparations. Particular emphasis is placed on identifying molecular determinants of activity and elucidating the mechanisms through which individual biomolecules influence host physiology. The objective is to clarify how these molecules interact with host cells and, where relevant, host receptors, trigger specific immune signalling pathways, and maintain barrier function through effects on tight junction proteins, mucin secretion and epithelial renewal. Priority will be given to studies addressing innate immune responses, inflammatory signalling, cytokine regulation, immune tolerance and epithelial-immune crosstalk, as well as adaptive immune responses where relevant. Overall, the Research Topic will link molecular characterisation with demonstrated biological effects to advance understanding of how probiotic-derived peptides, exopolysaccharides and S-layer proteins influence intestinal immune and epithelial functions.To ensure a focused scope, submissions should investigate a structurally characterised probiotic-derived peptide, exopolysaccharide or S-layer protein and provide functional evidence linking that molecule or molecular fraction to an intestinal immune or epithelial outcome. Studies may examine these components independently or in comparison with their producing strains, provided that component-specific effects are assessed.To gather further insights into this research area, we welcome submissions addressing, but not limited to, the following themes:- Structural and functional characterization of probiotic-derived peptides, exopolysaccharides and S-layer proteins- Interactions between these bioactives and host cells, including receptor-mediated mechanisms where demonstrated, and immune signalling pathways- Structure-function relationships of probiotic-derived peptides, exopolysaccharides and S-layer proteins, supported by targeted analytical characterization, including peptidomics or glycomics where relevant- Regulation of intestinal innate immune responses, inflammatory signalling, cytokine regulation, immune tolerance and epithelial-immune crosstalk- Role of these bioactives in modulating epithelial barrier integrity, tight junction dynamics and mucin biosynthesis- Use of intestinal models, including cell-based, organoid and animal models where appropriate, to link mechanistic insights with nutritional and physiological functions- Crosstalk between probiotic peptides, exopolysaccharides or S-layer proteins, dietary components and the host immune system- Translational potential of probiotic-derived peptides, exopolysaccharides and S-layer proteins in nutritional interventions and maintenance of gut health Topic editors: Martina Banić, Nina Čuljak, Nada Oršolić Source: https://www.frontiersin.org/research-topics/83927/probiotic-derived-bioactives-in-gut-immune-and-barrier-homeostasis