Is Increasing Microbiota Diversity a Novel Anti-Inflammatory Action of Marine n-3 Fatty Acids?

Microbial perspective on the skin-gut axis and atopic dermatitis

Atopic dermatitis (AD) is a relapsing inflammatory skin condition that has become a global health issue with complex etiology and mounting prevalence. The association of AD with skin and gut microbiota has been revealed by virtue of the continuous development of sequencing technology and genomics analysis. Also, the gut-brain-skin axis and its mutual crosstalk mechanisms have been gradually verified. Accordingly, the microbiota-skin-gut axis also plays an important role in allergic skin inflammation. Herein, we reviewed the relationship between the microbiota-skin-gut axis and AD, explored the underlying signaling molecules and potential pathways, and focused on the potential mechanisms of probiotics, antimicrobial peptides (AMPs), coagulase-negative staphylococci transplantation, fecal microbiota transplantation, AMPs, and addition of essential fatty acids in alleviating AD, with the aim to provide a new perspective for targeting microbiota in the treatment of allergic skin inflammation.

Influence of dietary n-3 long-chain fatty acids on microbial diversity and composition of sows' feces, colostrum, milk, and suckling piglets' feces

Introduction

Very little is known about the impact of n-3 long-chain fatty acids (n-3 LCFAs) on the microbiota of sows and their piglets. The aim of this study was to evaluate the effect of n-3 LCFA in sow diets on the microbiota composition of sows' feces, colostrum, and milk as well as that of piglets' feces.

Methods

Twenty-two sows were randomly assigned to either a control or an n-3 LCFA diet from service to weaning. Sows' and piglets' performance was monitored. The gestating and lactating sows' microbiomes in feces, colostrum, and milk were characterized by 16s ribosomal RNA gene sequencing. The fecal microbiome from the two lowest (>800 g) and the two highest birth weight piglets per litter was also characterized, and the LPS levels in plasma were analyzed at weaning.

Results and Discussion

n-3 LCFA increased microbiota alpha diversity in suckling piglets' and gestating sows' feces. However, no effects were observed in colostrum, milk, or lactating sows' feces. Dietary n-3 LCFA modified the microbiota composition of gestating sows' feces, milk, and suckling piglets' feces, without affecting lactating sows' feces or colostrum. In gestating sows' feces and milk, the decrease in genus Succinivibrio and the increase of Proteobacteria phylum, due to the increased genera Brenneria and Escherichia, respectively, stand out. In the feces of suckling piglets, the higher abundance of the beneficial genus Akkermansia and Bacteroides, and different species of Lactobacillus are highlighted. In addition, positive correlations for families and genera were found between lactating sows' feces and milk, milk and suckling piglets' feces, and lactating sows' feces and suckling piglets' feces. To conclude, dietary n-3 LCFA had a positive impact on the microbiome of suckling piglet's feces by increasing microbial diversity and some beneficial bacteria populations, had a few minor modifications on the microbiome of milk and gestating sows' feces and did not change the microbiome in lactating sows' feces or colostrum. Therefore, this study shows the effect of dietary n-3 LCFA on the microbiota of sows, colostrum, milk, and suckling piglets during the lactation period providing crucial information on the microbiota status at the early stages of life, which have an impact on the post-weaning.

Role of Nuclear Factor Erythroid 2 (Nrf2) in the Recovery of Long COVID-19 Using Natural Antioxidants: A Systematic Review

Coronavirus disease 2019 (COVID-19) is an infectious disease with approximately 517 million confirmed cases, with the average number of cases revealing that patients recover immediately without hospitalization. However, several other cases found that patients still experience various symptoms after 3–12 weeks, which is known as a long COVID syndrome. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection can activate nuclear factor kappa beta (NF-κβ) and unbind the nuclear factor erythroid 2-related factor 2 (Nrf2) with Kelch-like ECH-associated protein 1 (Keap1), causing inhibition of Nrf2, which has an important role in antioxidant response and redox homeostasis. Disrupting the Keap1–Nrf2 pathway enhances Nrf2 activity, and has been identified as a vital approach for the prevention of oxidative stress and inflammation. Hence, natural antioxidants from various sources have been identified as a promising strategy to prevent oxidative stress, which plays a role in reducing the long COVID-19 symptoms. Oxygen-rich natural antioxidant compounds provide an effective Nrf2 activation effect that interact with the conserved amino acid residues in the Keap1-binding pocket, such as Ser602, Ser363, Ser508, and Ser555. In this review, the benefits of various natural antioxidant compounds that can modulate the Nrf2 signaling pathway, which is critical in reducing and curing long COVID-19, are highlighted and discussed.

Dietary fatty acids in gut health: Absorption, metabolism and function

In biological responses, fatty acids (FA) are absorbed and metabolized in the form of substrates for energy production. The molecular structures (number of double bonds and chain length) and composition of dietary FA impact digestion, absorption and metabolism, and the biological roles of FA. Recently, increasing evidence indicates that FA are essentially utilized as an energy source and are signaling molecules that exert physiological activity of gut microbiota and immune responses. In addition, FA could serve as natural ligands for orphan G protein-coupled receptors (GPCR), also called free fatty acid receptors (FFAR), which intertwine metabolic and immune systems via multiple mechanisms. The present review explores the recent findings on FA absorption and its impact on gut health, particularly addressing the mechanism by which dietary FA potentially influences intestinal microbiota and epithelial functions. Also, this work attempts to uncover research ideas for devising future strategies for manipulating the composition of dietary FA to regulate gut health and support a normal immune system for metabolic and immune disorders.

Lifelong dietary omega-3 fatty acid suppresses thrombotic potential through gut microbiota alteration in aged mice

Aging is a major risk factor for cardiovascular diseases, including thrombotic events. The gut microbiota has been implicated in the development of thrombotic risk. Plant-derived omega-3 fatty acid ɑ-linolenic acid (ALA) confers beneficial anti-platelet and anti-inflammatory effects. Hence, antithrombotic activity elicited by ALA may be partly dependent on its interaction with gut microbiota during aging. Here, we demonstrate that lifelong dietary ALA decreases platelet hyperresponsiveness and thrombus formation in aged mice. These phenotypic changes can be partly attributed to alteration of microbial composition and reduction of its metabolite trimethylamine N-oxide and inflammatory mediators including TNF-α, as well as the upregulated production of short-chain fatty acid acetate. ALA-rich diet also dampens secretion of increased procoagulant factors, tissue factor and plasminogen activator inhibitor-1, in aged mice. Our results suggest long-term ALA supplementation as an attractive, accessible, and well-tolerated nutritional strategy against age-associated platelet hyperreactivity and thrombotic potential.

Omega-3 Polyunsaturated Fatty Acids and the Intestinal Epithelium-A Review

Epithelial cells (enterocytes) form part of the intestinal barrier, the largest human interface between the internal and external environments, and responsible for maintaining regulated intestinal absorption and immunological control. Under inflammatory conditions, the intestinal barrier and its component enterocytes become inflamed, leading to changes in barrier histology, permeability, and chemical mediator production. Omega-3 (ω-3) polyunsaturated fatty acids (PUFAs) can influence the inflammatory state of a range of cell types, including endothelial cells, monocytes, and macrophages. This review aims to assess the current literature detailing the effects of ω-3 PUFAs on epithelial cells. Marine-derived ω-3 PUFAs, eicosapentaenoic acid and docosahexaenoic acid, as well as plant-derived alpha-linolenic acid, are incorporated into intestinal epithelial cell membranes, prevent changes to epithelial permeability, inhibit the production of pro-inflammatory cytokines and eicosanoids and induce the production of anti-inflammatory eicosanoids and docosanoids. Altered inflammatory markers have been attributed to changes in activity and/or expression of proteins involved in inflammatory signalling including nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), peroxisome proliferator activated receptor (PPAR) α and γ, G-protein coupled receptor (GPR) 120 and cyclooxygenase (COX)-2. Effective doses for each ω-3 PUFA are difficult to determine due to inconsistencies in dose and time of exposure between different in vitro models and between in vivo and in vitro models. Further research is needed to determine the anti-inflammatory potential of less-studied ω-3 PUFAs, including docosapentaenoic acid and stearidonic acid.

Effects of dietary fatty acids on gut health and function of pigs pre- and post-weaning

Fatty acids (FA) play a major role in relation to mucosal immune responses, epithelial barrier functions, oxidative stress, and inflammatory reactions. The dietary FA composition and the molecular structures (chain length and number of double bonds) influence digestion, absorption and metabolism, and the bioactivity of the FA. Piglets post-weaning having an immature intestine and not fully formed immune functions are very vulnerable to invading microorganisms. Manipulation of the milk FA composition via sow nutrition, or inclusion of dietary fat sources in the feed for newly weaned pigs, may be used as a strategic tool to enhance pig performance and their gut health and function pre- and post-weaning. Medium-chain fatty acids (MCFA) are absorbed directly into the portal blood and may contribute to immediate energy for the enterocytes. In addition, the MCFA, similarly to the short-chain fatty acids (SCFA), possess antibacterial effects and may thereby prevent overgrowth of pathogenic bacteria in the gastrointestinal tract. The essential FA, linoleic (LA) and α-linolenic (ALA) FA, form the building blocks for the long-chain polyunsaturated n-3 and n-6 FA. The conversion of ALA and LA into n-3 and n-6 eicosanoids, respectively, influences the molecular structures of metabolites and inflammatory reactions and other immune responses upon bacterial challenges. Dietary manipulation of the lactating sow influences the transfer of the n-3 and n-6 polyunsaturated fatty acids (PUFA) from the sow milk to the piglet and the incorporation of the FA into piglet enteric tissues and cell membranes, which exerts bioactivity of importance for immune responses and the epithelial barrier function. Especially, the n-3 PUFA present in fish oil seem to influence the gut health and function of pigs, and this is of importance during the transition periods such as post-weaning in which piglets are prone to inflammation. The proportion of unsaturated FA in the cell membranes influences the susceptibility to oxidative stress. Oxidative stress accompanies infectious diseases, and the development of lipid peroxides and other reactive oxygen products may be harmful to the epithelial barrier function. Fatty acid peroxides from the feed may also be absorbed with other lipid-solubles and thereby harm the intestinal function. Hence, antioxidative protection is important for the enteric cells. In conclusion, manipulation of the dietary FA composition can influence the gut health and function in pigs and may support a normal immune system and modulate resistance to infectious diseases during especially stressful phases of a pig's life such as post-weaning.