Fulvic Acid Attenuates Atopic Dermatitis by Downregulating CCL17/22

Atopic Dermatitis: The Relationship Between Immune Mediators and Skin Lipid Barrier

Atopic dermatitis (AD) is a chronic inflammatory skin disease that is prevalent worldwide with complex etiology. Skin barrier defects and abnormal immune activation are crucial in the occurrence and development of AD. In the classic model of the skin barrier, lipids are essential for the formation and maintenance of this barrier as a "mortar" component. However, abnormally activated immune responses promote the lipid barrier deficiency through the secretion of various types of immune mediators directly or indirectly. In this review, we first introduce the skin lipid barrier (SLB) under both normal and abnormal conditions, highlighting the contributions of lipids derived from keratinocytes and sebaceous glands (SGs). Subsequently, the relationships between the immune mediators of Th1, Th2, Th17, Th22, and other types (adipokines, prostaglandins, leukotrienes) and SLB are elaborated in turn. Finally, the therapies for restoring SLB to treat AD are summarized, with a focus on the restoration effect of dupilumab on SLB. We hope that this review will offer a comprehensive perspective for understanding the pathogenesis of lipid metabolism disorders and SLB deficiency caused by immune mediators in AD. It also aims to provide guidance for further research on targeting inflammatory mediators to restore SLB.

Effects of fulvic acid on broiler performance, blood biochemistry, and intestinal microflora

To study the effects of mineral fulvic acid (FuA) on broiler performance, slaughter performance, blood biochemistry index, antioxidant function, immune performance, and intestinal microflora, 360 Arbor Acres (AA) broiler chickens with similar body weights were randomly divided into 5 groups with 6 replicates in each group and 12 chickens in each replicate in the current study. Chickens in the control group (C) were fed with the basal diet, and chickens in the test groups (I, II, III, and IV) were fed with the diet supplemented with 0.05%, 0.1%, 0.2%, and 0.3% mineral FuA, respectively. The indicators were measured on the hatching day, d 21 and d 35. From the whole experimental period, FuA supplement significantly increased average body weight (ABW) (P < 0.05), average daily gain (ADG) of broilers (P < 0.05), and thymus weight (P < 0.05) in II and IV groups, but bascially reduced the pH value of thigh meat. FuA supplement significantly improved aspartate aminotransferase (AST) activity in the group III on d 35 (P < 0.05) and the serum levels of IgA and IgG on d 21 and d 35 (P < 0.05), but reduced glutathione peroxidase (GSH-Px) level on d 21 (P < 0.05) and malondialdehyde (MDA) level in serum on d 35 (P < 0.05). FuA supplement significantly affected the abundance of Barnesiella, Lachnospiraceae, Alistipes, Lactobacillus, and Christensenellaceae on genus level. Differences between group III and other groups were significant in the genera microflora composition on d 21 and d 35. Functional analysis showed that the cecum microbiota were mainly enriched in carbohydrate metabolism, amino acid metabolism, and energy metabolism. In conclusion, FuA may potentially have significant positive effects on the growth performance and immune function of AA chickens through the modulation of the gut microbiota, and the 0.1% FuA was the best in broiler diet based on the present study.

Unraveling the gut-skin axis in atopic dermatitis: exploiting insights for therapeutic strategies

Gut microbiota exert functions of high importance in the intestine. Furthermore, there is increasing evidence for its role in immune regulation and maintenance of homeostasis in many physiological processes taking place in distant tissues. In particular, in this review, we explore the impact of metabolites produced by the gut microbiota on the development of atopic dermatitis (AD). Probiotics and prebiotics balance the microbiota and promote the generation of bacterial metabolites, such as short-chain fatty acids and tryptophan derivates, which promote the regulation of the exacerbated AD immune response through regulatory T cells and IL-10 and TGF-β cytokines. Metabolites also have a direct action on keratinocytes once they reach the bloodstream. Besides, probiotics decrease the levels of metabolites associated with AD onset, such as phenols. Understanding all these crosstalk processes between the gut and the skin reveals a number of possibilities, mainly through the manipulation of the gut microbiome, which may represent therapeutic strategies that can contribute to the standard treatments of AD patients to improve their quality of life.