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LALPROBIOME heat-treated bacterial strains support gut barrier function
Lallemand Animal Nutrition recently conducted a study in collaboration with the University of Plymouth to compare the beneficial effect of dietary supplementation with Lactobacillus-based products, either live (probiotic) or LALPROBIOME heat-treated (postbiotic), in supporting gut barrier integrity using zebrafish as a vertebrate model.
Why Zebrafish?
Since 1960’s, the 3R’s principle (Replacement, Reduction, and Refinement) has been recognised as a scientific standard for the ethical use of animals and is required in the legislation framework of animal experimentation worldwide. Animal models remain an essential measure in helping researchers to identify and understand biological mechanisms and disease progression, as well as develop new therapeutic possibilities. Mammalian models are replaced by animals considered as less sentient and the use of zebrafish (Danio rerio) has exponentially increased among the scientific community over recent decades. Zebrafish genetic, anatomical and physiological homology to mammals provides an alternative model to rodents and provides superior information to in vitro modelling. Due to the considerable benefits, Lallemand are using zebrafish in many of their research projects.
Gut barrier function: why is it important?
Pathogens have two main pathways for entry into the body: the skin and mucosal surfaces. The gastro-intestinal tract is constantly challenged by multiple stimuli, required to discriminate against pathogens and food antigens, and encounters more antigens than any other bodily site. Gut barrier function and integrity is crucial for homeostasis and immune functioning. The microbiota, mucus and epithelial cells, all act as physical and chemical barriers to protect immuno-competent cells within the gut and the internal body itself.
Goblet cells (GCs) are specialized epithelial cells that line the mucosal surface and are integral for the secretion of mucus. Mucus forms part of the biochemical barrier found within the gut and acts as a sieve-like structure to allow passage of small and selected molecules, while separating and protecting epithelial cells from the microbiota and any potential pathogens. Beyond barrier maintenance, GCs also play a role in innate immunity, acting as antigen sensors. A higher density and coverage of GCs indicates the maintenance of a functional mucus barrier. After the mucus barrier, intestinal epithelial cells form a physical barrier to restrict and control the paracellular diffusion of essential ions, nutrients, microorganisms and toxins. In humans, the intestinal epithelium spans between 200-400m2 and consists of a single layer of cells. Between cells, multi-protein complexes dynamically regulate barrier integrity and are the rate-limiting factor for permeability. Zonula-Occludens (ZO) is an essential protein for the formation and maintenance of these junctions and is ubiquitously expressed in epithelial cells.
The gut mucosal system: a unique network
Approximately 70% of the immune cells are located within the gut, acting as an immunological barrier. The intestinal immune system is a complex network dedicated to the defence of the body against pathogens while maintaining tolerance to beneficial microbes and food antigens. Several specialised cells (lymphocytes, dendritic cells and macrophages) are involved in this system, including, intra-epithelial lymphocytes (IELs). IELs are found within the epithelial layer of the intestinal mucosa and play a crucial role in immune surveillance, maintaining gut homeostasis, and responding to pathogens or other challenges. CD4+ and CD8+ are two subsets of IELs:
- CD4+ T cells can include various subsets, which can help maintain tolerance to dietary antigens and commensal bacteria, participate in immune responses against pathogens, or assist in inflammatory processes.
- CD8+ T cells are often cytotoxic T cells, capable of directly killing infected or aberrant (abnormal) host cells.
The gut immune response: mucosal markers
Conclusion
Using the zebrafish model as a recognised mammalian model of research, this study demonstrates the potential of selected LALPROBIOME probiotic and postbiotic bacterial strains to support gut barrier integrity and natural defences which are crucial factors in supporting pet gastrointestinal homeostasis and immunity.
Published Jun 9, 2024 | Updated Oct 2, 2024
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