Melatonin mediates mucosal immune cells, microbial metabolism, and rhythm crosstalk: A therapeutic target to reduce intestinal inflammation

Abstract

Nowadays, melatonin, previously considered only as a pharmaceutical product for rhythm regulation and sleep aiding, has shown its potential as a co‐adjuvant treatment in intestinal diseases, however, its mechanism is still not very clear. A firm connection between melatonin at a physiologically relevant concentration and the gut microbiota and inflammation has recently established. Herein, we summarize their crosstalk and focus on four novelties. First, how melatonin is synthesized and degraded in the gut and exerts potentially diverse phenotypic effects through its diverse metabolites. Second, how melatonin mediates the activation and proliferation of intestinal mucosal immune cells with paracrine and autocrine properties. By modulating T/B cells, mast cells, macrophages and dendritic cells, melatonin immunomodulatory involved in regulating T‐cell differentiation, intervening T/B cell interaction and attenuating the production of pro‐inflammatory factors, achieving its antioxidant action via specific receptors. Third, how melatonin exerts antimicrobial action and modulates microbial components, such as lipopolysaccharide, amyloid‐β peptides via nuclear factor κ‐light‐chain‐enhancer of activated B cells (NF‐κB) or signal transducers and activators of transcription (STAT1) pathway to modulate intestinal immune function in immune‐pineal axis. The last, how melatonin mediates the effect of intestinal bacterial activity signals on the body rhythm system through the NF‐κB pathway and influences the mucosal epithelium oscillation via clock gene expression. These processes are achieved at mitochondrial and nuclear levels to control the host immune cell development. Considering unclear mechanisms and undiscovered actions of melatonin in gut‐microbiome‐immune axis, it's time to reveal them and provide new insight for the outlook of melatonin as a potential therapeutic target in the treatment and management of intestinal diseases.

Antihyperlipidaemic effect of microencapsulated Lactobacillus plantarum LIP‐1 on hyperlipidaemic rats

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“…They are produced by fermentation of carbohydrate in the colon by bacteria; they are trophic to the small intestinal and colonic mucosa, and they stimulate the proliferation of intestinal mucosa epithelial cells and reduce intestinal permeability. 40,41 Trautwein et al 42 found that propionate and butyrate provide a source of energy for human colon epithelial cells and inhibit the growth of pathogenic bacteria and putrefaction bacteria; at the same time, they promote the growth of probiotics (such as Bifidobacterium species, and Lactobacillus species) in the intestine. Marcil et al 40 found that butyrate can stimulate the intestinal epithelial cells to regulate the absorption and metabolism of lipids, thereby reducing blood CHO.…”

Reversing UVB‐induced photoaging with Hibiscus sabdariffa calyx aqueous extract

“…Oxidative pressure can be generated by the external environment and internal resources, causing some of the primary damage resulting from the peroxide (e.g., ROS, superoxide radical, hydroxyl radical and hydrogen peroxide) . The lack of antioxidants leads to oxidative stress and excessive free radicals, which affect the structure of the protein and making the function abnormal.…”

“…Oxidative pressure can be generated by the external environment and internal resources, causing some of the primary damage resulting from the peroxide (e.g., ROS, superoxide radical, hydroxyl radical and hydrogen peroxide). [37][38][39][40][41][42][43][44] The lack of antioxidants leads to oxidative stress and excessive free radicals, which affect the structure of the protein and making the function abnormal. Reactive oxygen species attack and react with stable skin cell molecules, causing cross-linking of collagen and elastin and reducing the skin's ability to repair itself.…”

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“…Considering various metabolic characteristics or roles of the microorganism under different background and growth conditions, Bacteroides species induced by co-consumption of DF appear to be associated with an increased nutrient pool for members of the gut microbiota (Cockburn & Koropatkin, 2016). This would allow them to produce shortchain fatty acids, which would have easier access to intestinal epithelial cells, resulting in a series of pathway changes to achieve immune or metabolic regulation against obesity, diabetes, and inflammation, etc (Ma, Zhang, Reiter, & Ma, 2019;Zhou, 2017). Similarly, compared with the RM group, Akkermansia were found in relative higher abundance in mice on the HF diet.…”