Skin barrier impairment correlates with cutaneous Staphylococcus aureus colonization and sensitization to skin-associated microbial antigens in adult patients with atopic dermatitis.

BACKGROUND: Atopic dermatitis (AD) is a chronic inflammatory skin disease. The pathogenesis of AD involves skin barrier defects and dysregulation of innate and adaptive immunity. Some environmental factors such as stress, infections, and allergens are associated with aggravation of AD. The aim of the study was to investigate the relationship between skin barrier function, skin colonization of Staphylococcus aureus, and sensitization to antigens of skin-associated microorganisms in adult patients with AD. METHODS: Thirty adult patients with AD and 10 controls were recruited. Eczema severity was assessed, and transepidermal water loss (TEWL) was measured. Bacterial samples were taken from the skin using a swab technique for qualitative identification of S. aureus and a contact agar disc method for quantitative assessment. Immunological analyses of specific IgE to staphylococcal enterotoxins and yeasts as well as total serum IgE levels, were performed. RESULTS: TEWL was significantly higher among S. aureus-positive patients in comparison to S. aureus-negative patients with AD (P < 0.05). TEWL increased with increasing bacterial load (P = 0.018). In the group of patients sensitized to all three of the investigated skin-associated microorganisms (S. aureus, Malassezia, and Candida), an increased TEWL was observed, in comparison to patients sensitized to none, or one or two (P = 0.026). CONCLUSION: In adult patients with AD, a disrupted skin barrier promotes skin colonization by microbes, such as S. aureus. Heavy microbial colonization may facilitate skin penetration of microbial antigens leading to subsequent IgE sensitization. These results illustrate the importance of skin-associated microbial colonization and sensitization to microbial-derived allergens in eczema pathogenesis.

Sensitization to skin-associated microorganisms in adult patients with atopic dermatitis is of importance for disease severity.

Atopic dermatitis (AD) is a chronic inflammatory skin disease. Environmental and genetic factors, as well as microbial products from yeasts and bacteria, play a role in triggering the disease. A cohort of 619 adult patients with AD was screened for severity of AD, sensitization to Malassezia sympodialis, Candida albicans, Staphylococcus aureus enterotoxins and Dermatophagoides pteronyssinus. Serum levels of interleukin (IL)-18 were measured. Immunoglobulin E (IgE) sensitization to the combination of both yeast and mite antigens was found to be associated with more severe disease and higher levels of total IgE. AD patients with IgE sensitization to several microbial antigens had more severe disease than those with no IgE sensitization to microbial antigens. Sera from patients with IgE-associated AD showed higher levels of IL-18. Skin-associated microorganisms are exogenous factors triggering IgE-response and severity of AD. These findings are clinically important, and sensitization to these organisms should be assessed and considered in treatment strategies.

Impact on allergic immune response after treatment with vitamin A.

BACKGROUND: Vitamin A may have some influence on the immune system, but the role in allergy modulation is still unclear. OBJECTIVE: To clarify whether high levels of retinoic acid (RA) affects allergic response in vivo, we used a murine experimental model of airway allergic disease. METHODS: Ovalbumin (OVA)-immunization/OVA-challenge (OVA/OVA) and house dust mite (HDM)-immunization/HDM-challenge (HDM/HDM) experimental murine models of allergic airway disease, using C57Bl.10/Q groups of mice (n = 10) treated subcutaneously with different concentrations of all-trans RA (0, 50, 500 and 2,500 ug) every 2-days were used to assess the allergic immune response. RESULTS: Levels of total and specific-IgE in sera were increased in all groups of RA treated OVA/OVA and HDM/HDM mice. Percentage and total amount of recruited eosinophil in airways by bronchoalveolar lavage fluid (BALF) were significantly enhanced in groups treated with 50, 500 and 2,500 ug of RA compared to non-treated mice. However, the group of mice treated with 2,500 ug had less eosinophil recruitment than the other two groups (50 and 500 ug). In parallel, levels of IL-5 and total IgE in BALF were also significantly diminished in the group treated with 2,500 ug compared to the other 2 groups (50 and 500 ug). Finally, total lung resistance was decreased in group treated with 2,500 ug compared to non-treated mice. CONCLUSION: Our results suggest that retinoic acid directly enhances allergic response in vivo, but in higher doses may produce of immune suppression.

Does vitamin D intake during infancy promote the development of atopic allergy?

The active metabolite of vitamin D, 1,25-(OH)2D3, has immunomodulatory properties in addition to its more established action on bone and calcium metabolism. Recently vitamin D has been proposed as one of several environmental factors responsible for the increase in atopic diseases during the last decades. The objective of this study was to determine whether the estimated dose of dietary vitamin D3 during the first year of life is associated with atopic diseases up to the age of 6 years. In a prospective birth cohort study 123 six-year-old children were investigated for the cumulative incidence of atopic dermatitis, allergic rhinitis or asthma by means of a postal questionnaire. Their vitamin D3 intake during infancy was recorded in a previous study and the relationship between lower or higher vitamin D3 intake and atopic illness later in childhood was assessed. Atopic manifestations were more prevalent in the group with higher intake of vitamin D3. Although small, this study supports previous investigations suggesting a role of vitamin D intake during infancy in the development of atopic allergy later in childhood. If these findings are confirmed in prospective controlled clinical trials, prevention through modified vitamin D3 supplementation in infancy could be discussed to reduce the burden of atopic illnesses.

The prevalence of Malassezia yeasts in patients with atopic dermatitis, seborrhoeic dermatitis and healthy controls.

Cultures for Malassezia yeasts were taken from both normal-looking skin and lesional skin in 124 patients with atopic dermatitis, 16 patients with seborrhoeic dermatitis and from normal skin of 31 healthy controls. Positive Malassezia growth was found in fewer patients with atopic dermatitis (56%) than in patients with seborrhoeic dermatitis (88%) or in healthy controls (84%, p<0.01). In the patients with atopic dermatitis, fewer positive cultures were found in lesional (28%) than in non-lesional skin (44%, p<0.05), while positive cultures were found in 75% of both lesional and non-lesional skin of patients with seborrhoeic dermatitis (not significant). M. sympodialis dominated in patients with atopic dermatitis (46%) and in healthy controls (69%). In patients with seborrhoeic dermatitis both M. sympodialis and M. obtusa were cultured in 43%. A Malassezia species extract mixture would increase the possibility of detecting IgE sensitization to Malassezia in patients with atopic dermatitis.

Dual effects of vitamin D-induced alteration of TH1/TH2 cytokine expression: enhancing IgE production and decreasing airway eosinophilia in murine allergic airway disease.

BACKGROUND: Vitamin D, a common food additive, has been shown to prevent the induction of experimental autoimmune diseases in mice. A possible immune deviation from T(H)1 to T(H)2 responses has been postulated. Although there is no doubt about the beneficial effects of vitamin D, its role in allergy has not been investigated. OBJECTIVE: To define the role of vitamin D in modulating the development of a T(H)2-mediated disease, we used a murine model of pulmonary eosinophilic inflammation. METHODS: Five-week-old mice were primed on day 0 with ovalbumin intraperitoneally. Then they were nasally challenged with ovalbumin on days 7, 8, 9, and 10, and on day 11, samples were studied. Some mice received subcutaneous injections of vitamin D every second day as follows: days -3, -1, 1, 3, 5, 7, and 9. The control groups received PBS on the same days. RESULTS: Early treatment with vitamin D augmented allergen-induced T-cell proliferation along with T(H)2 cytokine (IL-4 and IL-13) and IgE production. Surprisingly, the local inflammatory response in bronchoalveolar lavage fluid and lung tissue was significantly ameliorated with impaired recruitment of eosinophils and inferior levels of IL-5. These findings were attributed to late treatment with vitamin D after establishment of an early immune response. CONCLUSION: We suggest that excess supplementation of vitamin D could influence the development of a sustained T(H)2 response, leading to an increasing prevalence of allergy, whereas vitamin D might hold promising beneficial effects in airway eosinophilia.

Decreased frequency of intracellular IFN-gamma producing T cells in whole blood preparations from patients with atopic dermatitis.

There have been contradictory reports on the shift in the T-cell cytokine expression pattern of peripheral blood mononuclear cells from patients with atopic dermatitis (AD); more specifically the interleukin (IL)-4 and interferon (IFN)-gamma profiles. The aim of this study was to shed further light on this contradiction by measuring the intracellular cytokines IL-4 and IFN-gamma by flow cytometry on unseparated whole blood to obtain results that, as accurately as possible, reflect the situation in circulating cells in vivo. The patient group including 64 patients with AD was compared with 18 nonatopic healthy adults. The results showed that the percentage of CD4+ T cells expressing IFN-gamma was significantly decreased (P < or = 0.001), as well as the percentage expressing IL-4 (P < 0.05) in AD patients compared with healthy controls. Furthermore, in supernatants from whole blood samples stimulated with phorbol 12-myristate 13-acetate and ionomycin, production of IFN-gamma was significantly decreased, while IL-4 production remained unchanged in AD patients compared with healthy controls. We also investigated if there was a relationship between serum IgE level and Phadiatop, a screening test for atopy, vs. the levels of IL-4 and IFN-gamma, but found no correlation with either. However, there was a significant correlation between disease severity and the level of total IgE (r = 0.67, P < 0.05). In conclusion, our results support the evidence for a decreased ability of peripheral CD4+ T cells to produce IFN-gamma among AD patients.