Oral supplementation with yeast β-glucans improves the resolution of Escherichia coli-associated inflammatory responses independently of monocyte/macrophage immune training

Sarah Walachowski (1) , Koen Breyne (2, 3) , Thomas Secher (4, 5) , Céline Cougoule (6) , Laurence Guzylack-Piriou (1) , Evelyne Meyer (7) , Gilles Foucras (1) , Guillaume Tabouret (1)

1 IHAP - Interactions hôtes-agents pathogènes [Toulouse]
2 Department of Neurology [Boston]
3 Massachusetts General Hospital [Boston, MA, USA]
4 CEPR - Centre d’Etude des Pathologies Respiratoires (CEPR), UMR 1100
5 Faculté de médecine, Université de Tours
6 IPBS - Institut de pharmacologie et de biologie structurale
7 UGENT - Universiteit Gent = Ghent University

Introduction: Confronted with the emerging threat of antimicrobial resistance, the development of alternative strategies to limit the use of antibiotics or potentiate their effect through synergy with the immune system is urgently needed. Many natural or synthetic biological response modifiers have been investigated in this context. Among them, beta-glucans, a type of soluble or insoluble polysaccharide composed of a linear or branched string of glucose molecules produced by various cereals, bacteria, algae, and inferior (yeast) and superior fungi (mushrooms) have garnered interest in the scientific community, with not less than 10,000 publications over the last two decades. Various biological activities of beta-glucans have been reported, such as anticancer, antidiabetic and immune-modulating effects. In vitro, yeast beta-glucans are known to markedly increase cytokine secretion of monocytes/macrophages during a secondary challenge, a phenomenon called immune training. Methods: Here, we orally delivered beta-glucans derived from the yeast S. cerevisiae to mice that were further challenged with Escherichia coli, Results: beta-glucan supplementation protected the mice from E. coli intraperitoneal and intra-mammary infections, as shown by a lower bacterial burden and greatly diminished tissue damage. Surprisingly, this was not associated with an increased local immune response. In addition, granulocyte recruitment was transient and limited, as well as local cytokine secretion, arguing for faster resolution of the inflammatory response. Furthermore, ex-vivo evaluation of monocytes/macrophages isolated or differentiated from beta-glucan-supplemented mice showed these cells to lack a trained response versus those from control mice. Conclusion: In conclusion, dietary beta-glucans can improve the outcome of Escherichia coli infections and dampen tissue damages associated to excessive inflammatory response. The mechanisms associated with such protection are not necessarily linked to immune system hyper-activation or immune training.

Keywords: innate immunity inflammation macrophages immune training b-glucans saccharomyces cerevisiae escherichia coli nutritional immuology; innate immunity; inflammation; macrophages; immune training; b-glucans; saccharomyces cerevisiae; escherichia coli; nutritional immuology

Domains: Life Sciences [q-bio]

Sarah Walachowski, Koen Breyne, Thomas Secher, Céline Cougoule, Laurence Guzylack-Piriou, et al.. Oral supplementation with yeast β-glucans improves the resolution of Escherichia coli-associated inflammatory responses independently of monocyte/macrophage immune training. Frontiers in Immunology, 2022, 13, pp.1086413. ⟨10.3389/fimmu.2022.1086413⟩. ⟨hal-03957147⟩