Atopic dermatitis-like symptoms in HR-1 hairless mice fed a diet low in magnesium and zinc

Rodent models of dermatological disorders

To assess the possible beneficial effects of drugs and drug candidates, different dermatological disease models are available in rodents. These models are able to mimic one or more characteristic features of the disorders, but not completely recapitulate the pathogenesis of the human skin diseases. Therefore, to improve the technology many new models have been developed both by genetic engineering and by chemical or physical induction. Currently the in vivo rodent models provide the physiologically most relevant approach to produce the pathology related to the majority of dermatological diseases. In this short review some widely used animal techniques (psoriasis, allergic contact dermatitis, atopic dermatitis, wound healing, melanoma and non-melanoma type skin cancers and UV erythema) are shown which are currently applied in pharmacological, pharmacokinetic, pharmaceutical and dermatological research. First the main points of the human pathomechanism are shown and afterwards the rodent models are briefly discussed. Finally critical evaluation is provided by the authors. However, according to the 3R rule the number of experimental animals is strongly suggested to be reduced, therefore the advanced in vitro and ex vivo techniques become more and more important contrary to in vivo preclinical methods also in dermatological research. As it is described in the outlook section, although the 2D/3D in vitro and skin on-a-chip techniques are promising and have many advantages they are not able to completely substitute the animal models in their vascular, immunological, secretory and neural complexity.

Sphingolipids as Functional Food Components: Benefits in Skin Improvement and Disease Prevention

Sphingolipids are ubiquitous components in eukaryotic organisms and have attracted attention as physiologically functional lipids. Sphingolipids with diverse structures are present in foodstuffs as these structures depend on the biological species they are derived from, such as mammals, plants, and fungi. The physiological functions of dietary sphingolipids, especially those that improve skin barrier function, have recently been noted. In addition, the roles of dietary sphingolipids in the prevention of diseases, including cancer and metabolic syndrome, have been studied. However, the mechanisms underlying the health-improving effects of dietary sphingolipids, especially their metabolic fates, have not been elucidated. Here, we review dietary sphingolipids, including their chemical structures and contents in foodstuff; digestion, intestinal absorption, and metabolism; and nutraceutical functions, based on the available evidence and hypotheses. Further research is warranted to clearly define how dietary sphingolipids can influence human health.

The contribution of mouse models to understanding atopic dermatitis

Atopic dermatitis (AD) is a dermatological disease accompanied by dry and cracked skin with severe pruritus. Although various therapeutic strategies have been introduced to alleviate AD, it remains challenging to cure the disorder. To achieve such a goal, understanding the pathophysiological mechanisms of AD is a prerequisite, requiring mouse models that properly reflect the AD phenotypes. Currently, numerous AD mouse models have been established, but each model has its own advantages and weaknesses. In this review, we categorized and summarized mouse models of AD and described their characteristics from a researcher's perspective.

Long-chain saturated fatty acids in breast milk are associated with the pathogenesis of atopic dermatitis via induction of inflammatory ILC3s

Breastfeeding influences the immune system development in infants and may even affect various immunological responses later in life. Breast milk provides a rich source of early nutrition for infant growth and development. However, the presence of certain compounds in breast milk, related to an unhealthy lifestyle or the diet of lactating mothers, may negatively impact infants. Based on a cohort study of atopic dermatitis (AD), we find the presence of damage-associated molecular patterns (DAMPs) activity in the mother's milk. By non-targeted metabolomic analysis, we identify the long-chain saturated fatty acids (LCSFA) as a biomarker DAMPs (+) breast milk samples. Similarly, a mouse model in which breastfed offspring are fed milk high in LCSFA show AD onset later in life. We prove that LCSFA are a type of damage-associated molecular patterns, which initiate a series of inflammatory events in the gut involving type 3 innate lymphoid cells (ILC3s). A remarkable increase in inflammatory ILC3s is observed in the gut, and the migration of these ILC3s to the skin may be potential triggers of AD. Gene expression analysis of ILC3s isolated from the gut reveal upregulation of genes that increase ILC3s and chemokines/chemokine receptors, which may play a role in ILC migration to the skin. Even in the absence of adaptive immunity, Rag1 knockout mice fed a high-LCSFA milk diet develop eczema, accompanied by increased gut ILC3s. We also present that gut microbiota of AD-prone PA milk-fed mice is different from non-AD OA/ND milk-fed mice. Here, we propose that early exposure to LCSFAs in infants may affect the balance of intestinal innate immunity, inducing a highly inflammatory environment with the proliferation of ILC3s and production of interleukin-17 and interleukin-22, these factors may be potential triggers or worsening factors of AD.

'Magnesium'-the master cation-as a drug-possibilities and evidences

Magnesium (Mg²⁺) is the 2nd most abundant intracellular cation, which participates in various enzymatic reactions; there by regulating vital biological functions. Magnesium (Mg²⁺) can regulate several cations, including sodium, potassium, and calcium; it consequently maintains physiological functions like impulse conduction, blood pressure, heart rhythm, and muscle contraction. But, it doesn't get much attention in account with its functions, making it a "Forgotten cation". Like other cations, maintenance of the normal physiological level of Mg²⁺ is important. Its deficiency is associated with various diseases, which point out to the importance of Mg²⁺ as a drug. The roles of Mg²⁺ such as natural calcium antagonist, glutamate NMDA receptor blocker, vasodilator, antioxidant and anti-inflammatory agent are responsible for its therapeutic benefits. Various salts of Mg²⁺ are currently in clinical use, but their application is limited. This review collates all the possible mechanisms behind the behavior of magnesium as a drug at different disease conditions with clinical shreds of evidence.

Dietary ceramide 2-aminoethylphosphonate, a marine sphingophosphonolipid, improves skin barrier function in hairless mice

Sphingolipids are one of the major components of cell membranes and are ubiquitous in eukaryotic organisms. Ceramide 2-aminoethylphosphonate (CAEP) of marine origin is a unique and abundant sphingophosphonolipid with a C-P bond. Although molluscs such as squids and bivalves, containing CAEP, are consumed globally, the dietary efficacy of CAEP is not understood. We investigated the efficacy of marine sphingophosphonolipids by studying the effect of dietary CAEP on the improvement of the skin barrier function in hairless mice fed a diet that induces severely dry-skin condition. The disrupted skin barrier functions such as an increase in the transepidermal water loss (TEWL), a decrease in the skin hydration index, and epidermal hyperplasia were restored by CEAP dietary supplementation. Correspondingly, dietary CAEP significantly increased the content of covalently bound ω-hydroxyceramide, and the expression of its biosynthesis-related genes in the skin. These effects of dietary CAEP mimic those of dietary plant glucosylceramide. The novel observations from this study show an enhancement in the skin barrier function by dietary CAEP and the effects could be contributed by the upregulation of covalently bound ω-hydroxyceramide synthesis in the skin.

Serum Zinc Status and Its Association with Allergic Sensitization: The Fifth Korea National Health and Nutrition Examination Survey

Zinc (Zn) is an essential trace element that plays important roles in the immune system. There is little known about the role of trace elements in allergic diseases, and previous reports have shown conflicting results. The aim of this study was to investigate the relationship between serum Zn levels and total or allergen-specific immunoglobulin E (IgE) levels. The initial candidates for this study were those who participated in the 5^th Korean National Health and Nutrition Examination Survey 2010 (n = 8,958), and 1,867 adults who had serum total and allergen specific-IgE levels measured were included. Upon adjusting for covariates, mean total IgE, Dermatophagoides farinae and dog-specific IgE levels increased significantly as the Zn levels decrease from the highest to the lowest quartile (p = 0.009, 0.004, and < 0.001, respectively). The multiple logistic regression analyses showed significant negative linear correlations between serum Zn levels and total, D. farinae-, cockroach-, and dog-specific IgE levels (p-value for linear trend = 0.004, 0.006, 0.027, and < 0.001, respectively). This study demonstrated that total/allergen specific IgE and Zn levels are significantly inversely related.

Oral administration of β-carotene or lycopene prevents atopic dermatitis-like dermatitis in HR-1 mice

Atopic dermatitis (AD) is a chronic relapsing eczematous skin disease. Certain populations of patients are resistant to standard therapies with topical steroids and/or calcineurin inhibitors, and require systemic medication, such as immunosuppressants. Recently, several reports have shed light on the anti-allergic effects of carotenoids. Therefore, we investigated the effect of p.o. administration of β-carotene or lycopene on AD-like symptoms of HR-1 hairless mice fed with a low zinc/magnesium diet. Mice were divided into four groups: (i) fed with a standard diet (Co group); (ii) low zinc/magnesium diet (HR group); (iii) low zinc/magnesium and β-carotene diet (HR-C group); and (iv) low zinc/magnesium and lycopene diet (HR-L group). They were then fed these diets for 8 weeks. Severities of dermatitis were assessed by their appearance, and histopathological and hematological observations. Mice in the HR group developed AD-like dermatitis both clinically and histologically. HR-C and HR-L group mice also developed xerosis and wrinkle-like skin changes, but they were milder than those of HR group mice. Histological analysis revealed that epidermis thickening and inflammatory cell infiltration in the skin of the HR-C and HR-L groups were both statistically less than those of the HR group. The concentration of thymus and activation regulated chemokine in the skin of the HR-L group and the concentration of CCL27 in the skin of the HR-C group were significantly lower than those of the HR group, respectively. In conclusion, p.o. administration of β-carotene or lycopene prevents AD-like symptoms in association with a suppression of T-helper 2 chemokines in a murine model. Ingestion of carotenoids may be beneficial for patients with AD.

Potential Applications of Phyto-Derived Ceramides in Improving Epidermal Barrier Function

The outer most layer of the skin, the stratum corneum, consists of corneocytes which are coated by a cornified envelope and embedded in a lipid matrix of ordered lamellar structure. It is responsible for the skin barrier function. Ceramides (CERs) are the backbone of the intercellular lipid membranes. Skin diseases such as atopic dermatitis and psoriasis and aged skin are characterized by dysfunctional skin barrier and dryness which are associated with reduced levels of CERs. Previously, the effectiveness of supplementation of synthetic and animal-based CERs in replenishing the depleted natural skin CERs and restoring the skin barrier function have been investigated. Recently, however, the barrier function improving effect of plant-derived CERs has attracted much attention. Phyto-derived CERs (phytoCERs) are preferable due to their assumed higher safety as they are mostly isolated from dietary sources. The beneficial effects of phytoCER-based oral dietary supplements for skin hydration and skin barrier reinforcement have been indicated in several studies involving animal models as well as human subjects. Ingestible dietary supplements containing phytoCERs are also widely available on the market. Nonetheless, little effort has been made to investigate the potential cosmetic applications of topically administered phytoCERs. Therefore, summarizing the foregoing investigations and identifying the gap in the scientific data on plant-derived CERs intended for skin-health benefits are of paramount importance. In this review, an attempt is made to synthesize the information available in the literature regarding the effects of phytoCER-based oral dietary supplements on skin hydration and barrier function with the underlying mechanisms.

The Effect of Fexofenadine on Pruritus in a Mouse Model (HR-ADf) of Atopic Dermatitis

Fexofenadine, a histamine H1-receptor antagonist, is approved for the treatment of pruritus associated with atopic dermatitis. The effects of fexofenadine on scratching behaviour, and plasma levels of histamine and eotaxin were assessed in a new model of atopic dermatitis. Mice fed a diet low in Mg2+ and Zn2+ (special diet S) were compared with mice on a normal diet (N) or diet S plus fexofenadine HCl for weeks 0-10 (S + F0-10), 0-5 (S + F0-5) or 6-10 (S + F6-10) (seven mice per group). Compared with group N, group S mice showed significantly greater scratching frequency, and plasma histamine and eotaxin concentrations; these three variables were significantly lower in group S + F0-10 than in group S. Scratching frequency increased when fexofenadine was discontinued. Fexofenadine significantly reduced mast cell and eosinophil numbers. Histamine may be important in the pathological changes seen in this model of atopic dermatitis, suggesting that it might aid future development of antihistamines for the treatment of atopic dermatitis.

Variant ATRX syndrome with dysfunction of ATRX and MAGT1 genes

A 0.8 kb intronic duplication in MAGT1 and a single base pair deletion in the last exon of ATRX were identified using a chromosome X-specific microarray and exome sequencing in a family with five males demonstrating intellectual disability (ID) and unusual skin findings (e.g., generalized pruritus). MAGT1 is an Mg²⁺ transporter previously associated with primary immunodeficiency and ID, whereas mutations in ATRX cause ATRX-ID syndrome. In patient cells, the function of ATRX was demonstrated to be abnormal based on altered RNA/protein expression, hypomethylation of rDNA, and abnormal cytokinesis. Dysfunction of MAGT1 was reflected in reduced RNA/protein expression and Mg²⁺ influx. The mutation in ATRX most likely explains the ID, whereas MAGT1 disruption could be linked to abnormal skin findings, as normal magnesium homeostasis is necessary for skin health. This work supports observations that multiple mutations collectively contribute to the phenotypic variability of syndromic ID, and emphasizes the importance of correlating clinical phenotype with genomic and cell function analyses.

Magnesium sulfate protects fetal skin from intrauterine ischemia reperfusion injury

Intrauterine ischemia-reperfusion (I/R) injury in fetus occurs with multifactorial pathogenesis and results with multiorgan injury including skin. Magnesium has widespread use in obstetric practice. Inn addition to magnesium's tocolytic and neuroprotective properties, it also has free radical reducing effects. The aim of the present study was to demonstrate whether magnesium sulfate could have protective effect on fetal rat skin in intrauterine ischemia-reperfusion (I/R) injury. Fetal skin ischemia was induced by clamping the utero-ovarian arteries bilaterally for 30 min, and reperfusion was achieved by removing the clamps for 60 min in 19-day pregnant rats. Magnesium Sulfate (MgSO(4)) was given to pregnant rats 20 min before I/R injury at the dose of 600 mg/kg in magnesium treatment group. No ischemia reperfusion was applied to control and sham-operated groups. Lipid peroxidation from the skin tissues was determined as thiobarbituric acid reactive substances (TBARS). Myeloperoxidase (MPO) activity was determined for neutrophil activation. The results showed that the levels of TBARS and MPO increased significantly in the fetal rat skin after I/R injury compared to control group. Levels of TBARS and MPO were significantly lower than those of I/R group in Magnesium-treated group. In conclusion, intrauterine ischemia-reperfusion may produce considerable fetal skin injury. Increased TBARS and MPO activity can be inhibited by magnesium treatment. This suggests that magnesium treatment may have protective effect on fetal rat skin in intrauterine I/R injury.

Antioxidant nutrient intakes and corresponding biomarkers associated with the risk of atopic dermatitis in young children

BACKGROUND/OBJECTIVES

To investigate the association of antioxidant nutritional status with the risk of atopic dermatitis (AD) in young children in a case-control, population-based study.

SUBJECTS/METHODS

Identified from preschools by using the Korean version of the International Study of Asthma and Allergies in Childhood (ISAAC). Final analysis included 180 AD (mean age 5.3+/-0.9 years) and 242 non-AD (mean age 5.2+/-1.0 years) children. Diet was assessed using a validated semi-quantitative food frequency questionnaire. Fasting blood samples were used for analyses of fat-soluble vitamins (retinol, alpha-tocopherol, and beta-carotene) and vitamin C.

RESULTS

AD was associated negatively with intakes of antioxidant-related nutrients. The adjusted odds ratio (OR) and 95% confidence interval (95% CI) were 0.44 (0.22-0.88) for the highest (vs lowest) quintile of beta-carotene. A similar association was observed for dietary vitamin E (OR=0.33, 95% CI=0.16-0.67), folic acid (OR=0.37, 95% CI=0.18-0.73), and iron (OR=0.39, 95% CI=0.19-0.79). Reduced AD risk was found with 1 s.d. increase of serum alpha-tocopherol [OR=0.64, 95% CI=0.41-0.98) and retinol (OR=0.74, 95% CI=0.58-0.96) concentrations, and marginally with that of serum beta-carotene levels (P=0.0749 for trend). There was no relationship of AD risk with dietary and plasma vitamin C as well as nutrient supplement intake regardless of nutrient type. AD was predicted better by the intake measure than the corresponding blood biomarker regarding vitamin E and beta-carotene.

CONCLUSIONS

These findings suggest that higher antioxidant nutritional status reduces the risk of AD and that such risk-reduction effects depend on nutrient type.

Mast cells in atopic dermatitis

Mast cells play as the major effector cells in immediate hypersensitivity through activation via the high-affinity IgE receptor, Fc epsilon RI, although many other functions have recently been discovered for this cell type. Given the broad array of proinflammatory mediators secreted from Fc epsilon RI-activated mast cells, as well as sensitization to allergens, IgE elevation, and increased mast cells in a majority of atopic dermatitis patients, mast cells are believed to be involved in the pathogenesis of atopic dermatitis. Numerous animal models have been used to study this epidemic disease. Here we review the recent progress to synthesize our current understanding of this disease and potential mechanisms for a mast cell's role in the disease.

The effect of wasabi rhizome extract on atopic dermatitis-like symptoms in HR-1 hairless mice

We investigated the effect of wasabi rhizome extract on atopic dermatitis (AD) model mice. The wasabi extract was fed to the HR-1 hairless mice, which develop AD-like symptoms with a special diet (HR-AD diet). The extract was expected to reduce the symptoms induced. Wasabi rhizome-containing HR-AD diet (5% and 10%) reduced the scratching behavior, and the 10% wasabi rhizome HR-AD diet significantly reduced scratching behavior on days 28, 35 and 42. Plasma components (histamine, eotaxin, IgE and thymus and activation-regulated chemokine (TARC)) were decreased in the 10% wasabi rhizome HR-AD diet. In histopathological examinations (toluidine blue (T.B.), major basic protein (MBP), CD4, IL-4, IL-5, eotaxin, TARC and IgE), the wasabi rhizome-containing HR-AD diet (5% and 10%) significantly reduced the number of positive stained cells. These results suggested that the wasabi rhizome extract improved the AD-like symptoms of HR-1 hairless mice.

A novel atopic dermatitis model induced by topical application with dermatophagoides farinae extract in NC/Nga mice

BACKGROUND

Atopic dermatitis is a chronically relapsing inflammatory skin disease. Animal models induced by relevant allergens play a very important role in the elucidation of the disease. The patients with atopic dermatitis are highly sensitized with mite allergens such as Dermatophagoides farinae (Df). Therefore, in the present study, we tried to develop a novel model for atopic dermatitis by repeated application with Df extract ointment.

METHODS

Df extract ointment was repeatedly applied to the back of NC/Nga mice together with barrier disruption. Atopic dermatitis-like skin lesions were evaluated by dermatitis scores, skin histology and immunological parameters. The effect of corticosteroid and calcineurin inhibitor was also examined.

RESULTS

Repeated application of Df extract ointment caused rapid increase in dermatitis scores. Clinical (skin dryness, erythema, edema and erosion) and histological symptoms (dermal and epidermal thickening, hyperkeratosis, parakeratosis and inflammatory cell infiltration) in this model were very similar to those in human atopic dermatitis. Serum total and Df-specific IgE levels were elevated in this model compared with normal mice, and draining lymph node cells isolated from the mice that exhibited dermatitis produced significant amounts of interleukin-5, interleukin-13 and interferon-gamma after re-stimulation with Df. Furthermore, current first-line drugs for the treatment of human atopic dermatitis, corticosteroid and tacrolimus ointments, were effective against the clinical and histological symptoms in this model.

CONCLUSIONS

These results suggest that the model we have established is useful for not only elucidating the pathogenesis of atopic dermatitis but also for evaluating therapeutic agents.

Dietary glucosylceramide improves skin barrier function in hairless mice

BACKGROUND

Sphingolipids are known to play an important role in both water retention and epidermal permeability barrier function in mammalian stratum corneum. However, little is known about the effects on epidermal function of orally administered sphingolipids.

OBJECTIVE

We examined the effect of dietary glucosylceramide (GluCer) on the maintenance and recovery of epidermal barrier function.

METHODS

Hairless mice were fed a particular diet (HR-AD) for 4 weeks to induce chronic skin perturbation. Subsequently, a normal diet supplemented with GluCer (from rice bran and germ) was provided for the next 4 weeks. Transepidermal water loss (TEWL) and stratum corneum flexibility were measured throughout this recovery phase. Additional hairless mice were fed a diet with or without a maize-extracted GluCer supplement for 5 weeks, then their skin was acutely perturbed with repeated tape-stripping, and the TEWL was measured.

RESULTS

Although skin functions were generally lower following chronic perturbation, in GluCer-fed mice the TEWL was significantly reduced at 2 weeks and the stratum corneum flexibility was increased at 3 weeks compared to controls. Following acute barrier perturbation by tape-stripping, mice an HR-AD fed a GluCer diet exhibited enhanced recovery compared with the control diet group.

CONCLUSION

These results demonstrate that in hairless mice skin barrier functions impaired by chronic or acute perturbations were improved by dietary GluCer. The oral administration of GluCer may be useful for the preservation and recovery of epidermal barrier functions an HR-AD.

Altered immune cell proportions in the radiodermatitis induced hairless mice-1 (HR-1)

Accidental radiation exposures or radiation therapy can cause internal and external damage including radiodermatitis. Even though radiodermatitis is one of the dose limiting factors in radiotherapy, the immunological nature of it is not yet been clearly understood. In this study, we have examined the alteration in immune cell population during the radiodermatitis process. A radiodermatitis model was established in HR-1 mice by locally exposing a posterior dorsal region to 10 Gy X-ray/day for 4 consecutive days. Collagen accumulation, redness, erythema, and dry desquamation of the skin were detected after X-irradiation. The size and total cell number of the spleen decreased immediately after X-irradiation, compared to those of the sham-irradiated mice, and recovered to the normal levels two weeks later. Reduction and recovery of the bone marrow cell population preceded a similar change of the spleen cell population. The proportion of CD4+ T cell increased, while the proportion of CD8+ T cell decreased ahead of the obvious skin damage, in both lymph node and spleen of the irradiated mice. Interestingly, the proportion of splenic monocytes/macrophages was expanded gradually at a similar kinetics with the aggravation of the radiodermatitis. The infiltration of the CD11b+ monocyte/macrophage to the X-irradiated skin also coincided with the development of radiodermatitis. These altered proportions of immune cells may play important roles in radiodermatitis.

Drinking deep-sea water restores mineral imbalance in atopic eczema/dermatitis syndrome

OBJECTIVE

The effect of drinking deep-sea water on hair minerals was studied in patients with atopic eczema/dermatitis syndrome (AEDS). Study of hair minerals revealed an imbalance of essential minerals and an increase in toxic minerals in AEDS patients.

DESIGN

After drinking deep-sea water (Amami no Mizu) for 6 months in AEDS patients, hair minerals (essential minerals and toxic minerals), clinical evaluation of the skin symptoms were compared before drinking with after drinking.

SUBJECTS

After obtaining informed consent, 33 patients (mean age 26 y, range 1-50 y, 13 male and 20 female subjects) with mild to moderate AEDS were enrolled.

RESULTS

After drinking deep-sea water, the levels of the essential mineral, potassium (K), were significantly decreased, while the levels of selenium (Se) increased. On the other hand, drinking deep-sea water significantly decreased the levels of the toxic minerals, mercury and lead. Moreover, after drinking deep-sea water, the skin symptoms were improved in 27 out of 33 patients.

CONCLUSION

These results indicate that the mineral abnormalities/imbalance may be involved in the pathogenesis of AEDS, and that drinking deep-sea water may be useful in the treatment of AEDS.