Association of Malassezia to Atopic Dermatitis

Purpose of Review

Atopic dermatitis (AD) is a common chronic, inherited, relapsing, inflammatory skin condition. A multifactorial etiology has been postulated, including genetic and immunological factors, impaired skin barrier function and environmental triggers, all of them are relevant in the pathogenesis. Malassezia spp. is the most common fungi of the skin microbiome. Most of the studies comparing the skin colonization with Malassezia spp. in healthy people and AD patients did not show difference between both groups. This review aims to show the studies carried out in this regard and the reported evidence about the role of Malassezia spp. in the pathogenesis of AD.

Recent Findings

The rate of IgE-mediated sensitization Malassezia spp. is very high in AD patients, mainly in adult patients and in patients with involvement in the head and neck. Different mechanisms have been postulated to explain the interaction of Malassezia spp. with human skin cells and immune cells and how its interaction contributes to the inflammation process in AD. Systemic and topical azole antifungals have been used with doubtful results showing beneficial effects in some AD patients.

Summary

There is no clear explanation for the high frequency of Malassezia spp. sensitization in AD patients in relation with healthy individuals. Further research is necessary to determine the specific role of Malassezia in AD and the indication for the use of antifungals in this disease.

     

Chemokine-Like Factor 1 (CLFK1) Is Over-Expressed in Patients with Atopic Dermatitis

Background: Human chemokine-like factor 1 (CKLF1), a recently discovered chemokine, has a broad spectrum of biological functions in immune-mediated diseases. It is highly expressed on Th2 lymphocytes and is a functional ligand for human CCR4. CKLF1 has a major role in the recruitment and activation of leucocytes, which plays an important role in the pathogenesis of allergic diseases. The present study was designed to determine the expression of CKLF1 in skin and serum in patients with atopic dermatitis (AD).Methods: The CKLF1 protein expression in skin lesion was analyzed by immunohistochemistry and ELISA. The mRNA expression of CKLF1 in skin lesion was detected by Real-time PCR. The serum levels of CKLF1, IgE, eotaxin, IL-4, IL-5, and IL-13 were measured by ELISA.Results: Histopathological changes in the skin of AD patients showed local inflammation with epidermal thickening and significant inflammatory cellular infiltration. Immunohistochemistry results demonstrated that CKLF1-staining positive cells were located in the epidermal and dermis, and that the CKLF1 expression in AD patients was significantly higher than that in normal control. The CKLF1 mRNA expression in AD patients was significantly higher than that in healthy controls. Serum CKLF1 and IgE levels were significantly increased in AD patients, as were the serum levels of IL-4, IL-5, IL-13 and eotaxin.Conclusions: Both CKLF1 protien and mRNA levels are overexpressed in the skin lesion of AD patients, along with an increase in serum CKLF1 level, indicating that CKLF1 may play an important role in the development of atopic dermatitis.     

Radioautography of Noradrenaline-14C in Atopic Dermatitis

Since storage-time of administered noradrenaline in the skin of patients with atopic dermatitis may be prolonged, it would be of interest to demonstrate the site of uptake of noradrenaline-¹⁴C in atopic dermatitis as compared with other eczematous and normal skins. Two adult patients with longstanding atopic dermatitis, a patient with contact dermatitis to nickel and one with normal skin, were studied. Identical sites in the four patients were injected intradermally with 0.02 μg. DL-noradrenaline-7-¹⁴C acetate. An 8-mm. punch biopsy of the injected site was performed 24 hours later. Radioautographs were developed between three and 199 days, according to the technique of Kopriwa and Leblond.² At 199 days, the number of grains in atopic dermatitic skin was greater than in contact dermatitis or normal skin. There was a concentration of grains over arrectores pilorum muscles and the upper one-third of the epidermis of atopic skin. Grains were also visible in proximity to arteriolar walls. There were few grains visible in the control sections. The results confirm earlier studies suggesting that atopic dermatitic skin retains noradrenaline longer than other dermatoses. Noradrenaline concentrates in the arrectores pilorum muscles and the upper epidermis. These findings may explain the cutis anserina (goose-flesh) appearance in atopic dermatitis.     

Maternal Filaggrin Mutations Increase the Risk of Atopic Dermatitis in Children: An Effect Independent of Mutation Inheritance

Epidemiological studies suggest that allergy risk is preferentially transmitted through mothers. This can be due to genomic imprinting, where the phenotype effect of an allele depends on its parental origin, or due to maternal effects reflecting the maternal genome''s influence on the child during prenatal development. Loss-of-function mutations in the filaggrin gene (FLG) cause skin barrier deficiency and strongly predispose to atopic dermatitis (AD). We investigated the 4 most prevalent European FLG mutations (c.2282del4, p.R501X, p.R2447X, and p.S3247X) in two samples including 759 and 450 AD families. We used the multinomial and maximum-likelihood approach implemented in the PREMIM/EMIM tool to model parent-of-origin effects. Beyond the known role of FLG inheritance in AD (R1_{meta-analysis} = 2.4, P = 1.0 x 10⁻³⁶), we observed a strong maternal FLG genotype effect that was consistent in both independent family sets and for all 4 mutations analysed. Overall, children of FLG-carrier mothers had a 1.5-fold increased AD risk (S1 = 1.50, P_{meta-analysis} = 8.4 x 10⁻⁸). Our data point to two independent and additive effects of FLG mutations: i) carrying a mutation and ii) having a mutation carrier mother. The maternal genotype effect was independent of mutation inheritance and can be seen as a non-genetic transmission of a genetic effect. The FLG maternal effect was observed only when mothers had allergic sensitization (elevated allergen-specific IgE antibody plasma levels), suggesting that FLG mutation-induced systemic immune responses in the mother may influence AD risk in the child. Notably, the maternal effect reported here was stronger than most common genetic risk factors for AD recently identified through genome-wide association studies (GWAS). Our study highlights the power of family-based studies in the identification of new etiological mechanisms and reveals, for the first time, a direct influence of the maternal genotype on the offspring’s susceptibility to a common human disease.     

WBN/Kob-Ht Rats Spontaneously Develop Dermatitis under Conventional Conditions: Another Possible Model for Atopic Dermatitis.

WBN/Kob-Ht rats (Ht-rats) raised under conventional conditions spontaneously developed dermatitis. In this study, we carried out histopathological analysis to elucidate the pathological features of the dermatitis in Ht-rats. We then tried to detect Staphylococcus species recovered from the skin lesions of Ht-rats. We also measured the serum levels of total IgE, IL-4 and IFN-gamma in these rats. The histopathological data indicated that inflammatory cells had infiltrated the skin lesions. Staphylococcus aureus was recovered from the skin lesions, and the serum levels of total IgE and IL-4 were elevated in Ht-rats with dermatitis. These results suggest that dermatitis in Ht-rats is similar to that in the DS-Nh mice, which has recently been proposed as an animal model for human atopic dermatitis.     

Validation of Treatment Escalation as a Definition of Atopic Eczema Flares

Background

Atopic eczema (AE) is a chronic disease with flares and remissions. Long-term control of AE flares has been identified as a core outcome domain for AE trials. However, it is unclear how flares should be defined and measured.

Objective

To validate two concepts of AE flares based on daily reports of topical medication use: (i) escalation of treatment and (ii) days of topical anti-inflammatory medication use (topical corticosteroids and/or calcineurin inhibitors).

Methods

Data from two published AE studies (studies A (n=336) and B (n=60)) were analysed separately. Validity and feasibility of flare definitions were assessed using daily global bother (scale 0 to 10) as the reference standard. Intra-class correlations were reported for continuous variables, and odds ratios and area under the receiver operator characteristic (ROC) curve for binary outcome measures.

Results

Good agreement was found between both AE flare definitions and change in global bother: area under the ROC curve for treatment escalation of 0.70 and 0.73 in studies A and B respectively, and area under the ROC curve of 0.69 for topical anti-inflammatory medication use (Study A only). Significant positive relationships were found between validated severity scales (POEM, SASSAD, TIS) and the duration of AE flares occurring in the previous week – POEM and SASSAD rose by half a point for each unit increase in number of days in flare. Smaller increases were observed on the TIS scale. Completeness of daily diaries was 95% for Study A and 60% for Study B over 16 weeks).

Conclusion

Both definitions were good proxy indicators of AE flares. We found no evidence that ‘escalation of treatment’ was a better measure of AE flares than ‘use of topical anti-inflammatory medications’. Capturing disease flares in AE trials through daily recording of medication use is feasible and appears to be a good indicator of long-term control.

Trial registration

Current Controlled Trials ISRCTN71423189 (Study A).     

Topical Application of Flurandrenolone in the Treatment of Atopic Dermatitis

The effect of flurandrenolone, 0.05%, in a cream base was compared with that of hydrocortisone, 1%, in the same base in 35 cases of atopic dermatitis, using contralateral application technique. The efficacy of flurandrenolone was found to be superior to that of hydrocortisone in 23 instances and equal in 12 cases. A fourfold dilution of this cream, flurandrenolone 0.0125%, was compared with 1% hydrocortisone cream in 18 patients and similar results were obtained. The superiority of flurandrenolone was particularly evident during the first week of application. The therapeutic efficacy of small amounts of flurandrenolone results in economic advantage to the patient and enables him to use applications of this preparation more freely.     

Observations on the Antipruritic Effect of Guanethidine in Atopic Dermatitis

Guanethidine, 0.75 to 1.25 mg. per kg. per day, was found to alleviate the pruritus of acute atopic dermatitis in 19 out of 20 patients. It was not effective in patients with other dermatoses. An apparent partial tolerance to this treatment developed in six out of 10 patients re-treated. It had little or no therapeutic effect in 10 patients with a variety of other pruritic dermatoses, suggesting that this drug has a specific antipruritic action in patients with atopic dermatitis. In a double-blind study, 11 of 12 patients with atopic dermatitis treated with guanethidine experienced relief of pruritus. Four out of 12 patients using a placebo had complete or partial relief. Guanethidine, 1% to 10%, used topically was therapeutically no more effective than placebo. In view of the reported side effects and the anesthetic hazard encountered with guanethidine, further long-term studies are indicated before this drug is adopted for clinical use in the treatment of atopic dermatitis. The findings support the hypothesis that atopic dermatitis may be a manifestation of a hereditary defect in cutaneous noradrenaline binding.     

Indoor Air Pollution Aggravates Symptoms of Atopic Dermatitis in Children

Most of researches on the impact of indoor air pollutants on atopic dermatitis (AD) have been based upon animal models, in vitro experiments and case-control studies. However, human data to elucidate the role of indoor air pollution on worsening symptoms of pre-existing AD from a longitudinal study are scarce. The objective of this prospective study was to evaluate the effect of indoor air pollution on AD symptoms in children. We surveyed 30 children with AD in a day-care centre, which moved to a new building during the study. These children stayed there for 8 hours a day Monday through Friday, and their daily symptom scores were recorded. Indoor and outdoor air pollutant levels were continuously measured 24 hours a day for 12 months (Period 1 to 4). Data were analyzed using a generalized linear mixed model. Compared to the period before moving (Period 1), concentrations of indoor air pollutants mostly increased after moving (Period 2) and decreased by natural ventilation and bake-out (Periods 3 and 4). The rate of positive AD symptom increased from 32.8% (Period 1) up to 43.8% (Period 2) and 50.5% (Period 3), then decreased to 35.4% in Period 4 (P < 0.0001). When the delayed effects of indoor air pollutants on AD symptoms 2 days later were evaluated, AD symptoms significantly increased by 12.7% (95% CI: -0.01 to 27.1) as toluene levels increased by 1 ppb (P = 0.05). In conclusion, indoor air pollutants increase the risk of AD aggravation in children and toluene in the indoor environment might act as an aggravating factor.     

Altered lipid properties of the stratum corneum in Canine Atopic Dermatitis

Skin barrier disruption plays a role in the pathogenesis of atopic dermatitis (AD) in humans. However, little is known about skin barrier (dys-) function in Canine Atopic Dermatitis. The properties of lipids located in the outermost layer of the skin, the stratum corneum (SC) are considered to be important for the barrier. In the present study the lipid composition and lipid organization of the SC of AD dogs and control dogs were examined. The lipid composition of lesional AD skin as compared to control skin, showed a reduced free fatty acid level and a decreased ratio of ceramide[NS] C44/C34, in which C44 and C34 are the total numbers of carbon atoms of the sphingosine (S) and non-hydroxy (N) acyl chains. As a consequence of the observed changes in lipid composition in AD lesional skin the lamellar organization of lipids altered and a shift from orthorhombic to hexagonal lipid packing was monitored. Simultaneously an increased conformational disordering occurred. These changes are expected to compromise the integrity of the skin barrier. The C44/C34 chain length ratio of ceramide[NS] also showed a decreasing nonlinear relationship with the AD severity score (CADESI). Taken together, canine atopic skin showed alterations in SC lipid properties, similar to the changes observed in atopic dermatitis in humans, that correlated with a disruption of the skin barrier. Hence lipids play an important role in the pathogenesis of Canine Atopic Dermatitis.     

Profiling of Serum and Urinary MicroRNAs in Children with Atopic Dermatitis

Background

Atopic dermatitis (AD) is the most prevalent chronic inflammatory skin disease in children characterized by dermatitis and pruritus. MicroRNAs (miRNAs) have been shown as great potential biomarkers for disease fingerprints to predict prognostics. We aimed to identify miRNA signature from serum and urine for the prognosis of AD patient by genome-wide miRNA profiling analysis.

Methods

Serum and urine from 30 children with AD and 28 healthy children were collected and their genome-wide miRNA expression profiles were measured by TaqMan-based array and confirmed by quantitative real-time PCR. Inflammatory factors in serum were detected by Antibody Array System.

Results

miR-203 and miR-483-5p were significantly up-regulated in serum of children with AD compared with healthy children. The level of miR-483-5p in serum was significantly associated with other atopic conditions, such as rhinitis and/or asthma. However, miR-203 was markedly decreased in urine of children with AD compared with healthy children. Down-regulated miR-203 in urine was significant associated with abnormal level of serum IgE in AD patients. 7 inflammatory factors in serum were altered in children with AD compared with healthy children. Up-regulated miR-203 in serum was significantly associated with increased sTNFRI and sTNFRII.

Conclusions

Up-regulated miR-483-5p in serum may be indicative of other atopic conditions in children with AD. Down-regulated miR-203 in urine may serve as a biomarker for the severity of inflammation in children with AD.