Reduced Carotenoid and Retinoid Concentrations and Altered Lycopene Isomer Ratio in Plasma of Atopic Dermatitis Patients

Characteristics of gut microbiota and serum metabolism in patients with atopic dermatitis

BACKGROUND

Atopic dermatitis (AD) is a chronic inflammatory skin disease that affects 15%-30% of children and 10% of adults globally, with its incidence being influenced by genetic, environmental, and various other factors. While the immune plays a crucial role in the development, the composition of gut microbiota and serum metabolites also contribute to its pathogenesis.

SUBJECT

Study the characteristics of gut microbiota and serum metabolites in patients with atopic dermatitis METHOD: In this study, we collected stool and serum samples from 28 AD patients and 23 healthy individuals (NC) for metagenomic sequencing of gut microbiota and non-targeted metabolomic sequencing of serum.

RESULT

Our results revealed a lower diversity of gut microbiota in the AD group compared to the NC group. The predominant Phylum in AD patients were Bacteroidetes, Pseudomonas, and Verrucomicrobia, with the most dominant bacterial genus being Faecalibacterium. At the species level, Prevotella copri and Faecalibacterium prausnitzii were found to be the most abundant bacteria. Significant differences in serum metabolite profiles were observed between NC and AD patients, with noticeable variations in metabolite expression levels. The majority of metabolites in the serum of AD patients exhibited low expression, while a few showed high expression levels. Notably, metabolites such as Cholesterol glucuronide, Styrene, Lutein, Betaine, Phosphorylcholine, Taurine, and Creatinine displayed the most pronounced alterations.

CONCLUSION

These findings contribute to a further understanding of the complexities underlying this disease.

Modulatory role of vitamins A, B3, C, D, and E on skin health, immunity, microbiome, and diseases

Disruption of the skin barrier and immunity has been associated with several skin diseases, namely atopic dermatitis (AD), psoriasis, and acne. Resident and non-resident immune cells and the barrier system of the skin are integral to innate immunity. Recent advances in understanding skin microbiota have opened the scope of further understanding the various communications between these microbiota and skin immune cells. Vitamins, being one of the important micronutrients, have been reported to exert antioxidant, anti-inflammatory, and anti-microbial effects. The immunomodulatory action of vitamins can halt the progression of skin diseases, and thus, understanding the immuno-pharmacology of these vitamins, especially for skin diseases can pave the way for their therapeutic potential. At the same time, molecular and cellular markers modulated with these vitamins and their derivatives need to be explored. The present review is focused on significant vitamins (vitamins A, B3, C, D, and E) consumed as nutritional supplements to discuss the outcomes and scope of studies related to skin immunity, health, and diseases.

State-of-the-art methodological investigation of carotenoid activity and metabolism - from organic synthesis via metabolism to biological activity - exemplified by a novel retinoid signalling pathway

Carotenoids are the most abundant lipophilic secondary plant metabolites and their dietary intake has been related to a large number of potential health benefits relevant for humans, including even reduced total mortality. An important feature is their potential to impact oxidative stress and inflammatory pathways, by interacting with transcription factors. For example, they may act as precursors of bioactive derivatives activating nuclear hormone receptor mediated signalling. These bioactive derivatives, originating e.g. from β-carotene, i.e. retinoids / vitamin A, can activate the nuclear hormone receptors RARs (retinoic acid receptors). Due to new analytical insights, various novel metabolic pathways were recently outlined to be mediated via distinct nuclear hormone receptor activating pathways that were predicted and further confirmed. In this article, we describe old and novel metabolic pathways from various carotenoids towards novel ligands of alternative nuclear hormone receptors. However, to fully elucidate these pathways, a larger array of techniques and tools, starting from organic synthesis, lipidomics, reporter models, classical in vitro and in vivo models and further omics-approaches and their statistical evaluation are needed to comprehensively and conclusively study this topic. Thus, we further describe state-of-the-art techniques from A to Ω elucidating carotenoid biological mediated activities and describe in detail required materials and methods needed - in practical protocol form - for the various steps of carotenoid investigations.

Plasma Levels of Bioactive Vitamin D and A5 Ligands Positively Correlate with Clinical Atopic Dermatitis Markers

BACKGROUND

Over the past decade, several controversial studies described a relationship between vitamin D and atopic diseases. Low plasma vitamin D levels or even vitamin D deficiency was associated with an increased incidence of atopic disease, postulating that a higher dietary intake of vitamin D may be a beneficial strategy against atopic diseases such as atopic dermatitis (AD).

OBJECTIVE

Our aim was to determine the relationship between plasma 25-hydroxyvitamin D3 (25(OH)D3) levels, the levels of the ligand of the vitamin D receptor (VDR) heterodimerization partner as well as the retinoid X receptor (RXR) and the active vitamin A5 derivative 9-cis-13,14-dihydroretinoic acid (9CDHRA) and AD severity.

METHODS/RESULTS

Samples from AD patients (n = 20) and healthy volunteers (n = 20) were assessed. In our study, the frequently measured VDR ligand precursor 25(OH)D3 in addition to the VDR-ligand 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) and 9CDHRA displayed no different levels when compared with the plasma of AD patients and healthy volunteers. When performing further correlation studies focusing on AD patients, plasma 25(OH)D3 levels showed a negative correlation with eosinophils in blood (EOS) and SCORing Atopic Dermatitis (SCORAD) values, while 1,25(OH)2D3 and 9CDHRA levels correlated positively with plasma IgE, EOS, and SCORAD values.

CONCLUSION

In consequence, the metabolic activation of vitamin D from 25(OH)D3 towards 1,25(OH)2D3 as well as the co-liganding of the RXR by 9CDHRA may be an important signalling mechanism, an important marker for AD development and severity as well as the basis for novel nutritional and pharmaceutical AD treatment options.

Lycopene: A Natural Arsenal in the War against Oxidative Stress and Cardiovascular Diseases

Lycopene is a bioactive red pigment found in plants, especially in red fruits and vegetables, including tomato, pink guava, papaya, pink grapefruit, and watermelon. Several research reports have advocated its positive impact on human health and physiology. For humans, lycopene is an essential substance obtained from dietary sources to fulfil the body requirements. The production of reactive oxygen species (ROS) causing oxidative stress and downstream complications include one of the major health concerns worldwide. In recent years, oxidative stress and its counter strategies have attracted biomedical research in order to manage the emerging health issues. Lycopene has been reported to directly interact with ROS, which can help to prevent chronic diseases, including diabetes and neurodegenerative and cardiovascular diseases. In this context, the present review article was written to provide an accumulative account of protective and ameliorative effects of lycopene on coronary artery disease (CAD) and hypertension, which are the leading causes of death worldwide. Lycopene is a potent antioxidant that fights ROS and, subsequently, complications. It reduces blood pressure via inhibiting the angiotensin-converting enzyme and regulating nitrous oxide bioavailability. It plays an important role in lowering of LDL (low-density lipoproteins) and improving HDL (high-density lipoproteins) levels to minimize atherosclerosis, which protects the onset of coronary artery disease and hypertension. Various studies have advocated that lycopene exhibited a combating competence in the treatment of these diseases. Owing to all the antioxidant, anti-diabetic, and anti-hypertensive properties, lycopene provides a potential nutraceutical with a protective and curing ability against coronary artery disease and hypertension.

Illuminating the Role of Vitamin A in Skin Innate Immunity and the Skin Microbiome: A Narrative Review

Vitamin A is a fat-soluble vitamin that plays an important role in skin immunity. Deficiencies in Vitamin A have been linked to impaired immune response and increased susceptibility to skin infections and inflammatory skin disease. This narrative review summarizes recent primary evidence that elucidates the role of vitamin A and its derivatives on innate immune regulators through mechanisms that promote skin immunity and sustain the skin microbiome.

Allergy Modulation by N-3 Long Chain Polyunsaturated Fatty Acids and Fat Soluble Nutrients of the Mediterranean Diet

The Mediterranean diet, containing valuable nutrients such as n-3 long chain poly-unsaturated fatty acids (LCPUFAs) and other fat-soluble micronutrients, is known for its health promoting and anti-inflammatory effects. Its valuable elements might help in the battle against the rising prevalence of non-communicable diseases (NCD), including the development of allergic diseases and other (chronic) inflammatory diseases. The fat fraction of the Mediterranean diet contains bioactive fatty acids but can also serve as a matrix to dissolve and increase the uptake of fat-soluble vitamins and phytochemicals, such as luteolin, quercetin, resveratrol and lycopene with known immunomodulatory and anti-inflammatory capacities. Especially n-3 LCPUFAs such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) derived from marine oils can target specific receptors or signaling cascades, act as eicosanoid precursors and/or alter membrane fluidity and lipid raft formation, hereby exhibiting anti-inflammatory properties. Beyond n-3 LCPUFAs, fat-soluble vitamins A, D, E, and K1/2 have the potential to affect pro-inflammatory signaling cascades by interacting with receptors or activating/inhibiting signaling proteins or phosphorylation in immune cells (DCs, T-cells, mast cells) involved in allergic sensitization or the elicitation/effector phase of allergic reactions. Moreover, fat-soluble plant-derived phytochemicals can manipulate signaling cascades, mostly by interacting with other receptors or signaling proteins compared to those modified by fat-soluble vitamins, suggesting potential additive or synergistic actions by applying a combination of these nutrients which are all part of the regular Mediterranean diet. Research concerning the effects of phytochemicals such as polyphenols has been hampered due to their poor bio-availability. However, their solubility and uptake are improved by applying them within the dietary fat matrix. Alternatively, they can be prepared for targeted delivery by means of pharmaceutical approaches such as encapsulation within liposomes or even unique nanoparticles. This review illuminates the molecular mechanisms of action and possible immunomodulatory effects of n-3 LCPUFAs and fat-soluble micronutrients from the Mediterranean diet in allergic disease development and allergic inflammation. This will enable us to further appreciate how to make use of the beneficial effects of n-3 LCPUFAs, fat-soluble vitamins and a selection of phytochemicals as active biological components in allergy prevention and/or symptom reduction.

Vitamin A deficiency exacerbates extrinsic atopic dermatitis development by potentiating type 2 helper T cell-type inflammation and mast cell activation

BACKGROUND

Vitamin A deficiency (VAD) has been hypothesized to play a role in the pathophysiology of atopic dermatitis (AD).

OBJECTIVE

We sought to verify whether VAD can exacerbate AD development, and explore the possible pathophysiologic mechanism.

METHODS

We detected serum vitamin A (VA) concentration in different phenotypes of AD infants (intrinsic AD, iAD and extrinsic AD, eAD), and established ovalbumin (OVA) percutaneous sensitized AD model and passive cutaneous anaphylaxis (PCA) model on VAD and vitamin A supplementation (VAS) model in wild-type mice (C57BL/6) and established AD model on both normal VA (VAN) and VAD feeding mast cell deficiency mice (ckit^w-sh/w-sh ).

RESULTS

The average serum VA concentration of eAD was significantly lower than that of iAD, as well as healthy controls. In OVA-induced C57BL/6 mouse AD model, compared with VAN group, VAD mice manifested significantly more mast cells accumulation in the skin lesions, more severe Th2-mediated inflammation, including higher serum IgG1 and IgE levels, more IL-4, IL-13 mRNA expression in OVA-sensitized skin, and lower Th1 immune response, including lower serum IgG2a and IFN-γ mRNA expression in the skin. But there was no significant difference in the expression of IL-17 mRNA between OVA-treated skin of VAN and VAD mice. However, in OVA-induced ckit^w-sh/w-sh mouse AD model, we did not find any significant differences in the above measurements between VAD and VAN group. In PCA model, VAD mice showed remarkable more blue dye leakage than that in VAN mice. Compared with VAD group, the above-mentioned inflammatory measurements in VAS group and VAN group were similar in OVA-induced AD model mice.

CONCLUSIONS AND CLINICAL RELEVANCE

VAD can exacerbate extrinsic AD by augmenting Th2-mediated inflammation and mast cell activation. Therapeutic VAS can rescue VAD-aggravated eAD. It may provide a new strategy for future prevention or treatment of atopic dermatitis.

β-Carotene in the human body: metabolic bioactivation pathways - from digestion to tissue distribution and excretion

β-Carotene intake and tissue/blood concentrations have been associated with reduced incidence of several chronic diseases. Further bioactive carotenoid-metabolites can modulate the expression of specific genes mainly via the nuclear hormone receptors: retinoic acid receptor- and retinoid X receptor-mediated signalling. To better understand the metabolic conversion of β-carotene, inter-individual differences regarding β-carotene bioavailability and bioactivity are key steps that determine its further metabolism and bioactivation and mediated signalling. Major carotenoid metabolites, the retinoids, can be stored as esters or further oxidised and excreted via phase 2 metabolism pathways. In this review, we aim to highlight the major critical control points that determine the fate of β-carotene in the human body, with a special emphasis on β-carotene oxygenase 1. The hypothesis that higher dietary β-carotene intake and serum level results in higher β-carotene-mediated signalling is partly questioned. Alternative autoregulatory mechanisms in β-carotene / retinoid-mediated signalling are highlighted to better predict and optimise nutritional strategies involving β-carotene-related health beneficial mediated effects.