bims-bac4me 2023-01-08 papers

Issue of 2023–01–08
three papers selected by
Chun-Chi Chang, University Hospital Zurich

Sheng Li Xue Bao. 2022 Dec 25. 74(6): 1031-1038

[Epigenetic regulation of microglia-mediated innate immune memory and neurological diseases].

Microglia have the ability to mediate innate immune memory and can be reprogrammed by primary stimuli to enhance or inhibit the immune response of microglia to secondary stimuli. Inflammatory stimulation is an important factor for microglia to mediate innate immune memory. Single or repeated stimulation can induce microglia to form different phenotypes. Microglia-mediated innate immune response is involved in the regulation of immune memory. Enhancer modification is a key pathway of microglia epigenetic regulation, and the H3K27ac enhancer marker is closely related to immune training. TGF-β1 mediates the interaction between IL-10 and IL-1β, thereby influencing the microglial phenotype. Microglia glycolysis activity is increased after immune training, and oxidative phosphorylation is associated with immune tolerance. Innate immune memory is closely associated with neurodegenerative diseases, brain tumors, brain damage and psychosis. Further study on the mechanism of microglia-mediated innate immune memory is helpful to understand the occurrence and development of central nervous system diseases and provide new options for the treatment of central nervous system diseases.

Front Immunol. 2022 ;13 1086413

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

Sarah Walachowski, Koen Breyne, Thomas Secher, Céline Cougoule, Laurence Guzylack-Piriou, Evelyne Meyer, Gilles Foucras, Guillaume Tabouret.

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, β-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 β-glucans have been reported, such as anticancer, antidiabetic and immune-modulating effects. In vitro, yeast β-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 β-glucans derived from the yeast S. cerevisiae to mice that were further challenged with Escherichia coli.
Results: β-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 β-glucan-supplemented mice showed these cells to lack a trained response versus those from control mice.
Conclusion: In conclusion, dietary β-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: escherichia coli; immune training; inflammation; innate immunity; macrophages; nutritional immuology; saccharomyces cerevisiae; β-glucans

DOI: https://doi.org/10.3389/fimmu.2022.1086413

Biochem Soc Trans. 2023 Jan 06. pii: BST20220216. [Epub ahead of print]

The dynamic balance of the skin microbiome across the lifespan.

Elizabeth C Townsend, Lindsay R Kalan.

For decades research has centered on identifying the ideal balanced skin microbiome that prevents disease and on developing therapeutics to foster this balance. However, this single idealized balance may not exist. The skin microbiome changes across the lifespan. This is reflected in the dynamic shifts of the skin microbiome's diverse, inter-connected community of microorganisms with age. While there are core skin microbial taxa, the precise community composition for any individual person is determined by local skin physiology, genetics, microbe-host interactions, and microbe-microbe interactions. As a key interface with the environment, the skin surface and its appendages are also constantly exchanging microbes with close personal contacts and the environment. Hormone fluctuations and immune system maturation also drive age-dependent changes in skin physiology that support different microbial community structures over time. Here, we review recent insights into the factors that shape the skin microbiome throughout life. Collectively, the works summarized within this review highlight how, depending on where we are in lifespan, our skin supports robust microbial communities, while still maintaining microbial features unique to us. This review will also highlight how disruptions to this dynamic microbial balance can influence risk for dermatological diseases as well as impact lifelong health.

Keywords: host–microbe interactions; microbiome; skin

DOI: https://doi.org/10.1042/BST20220216