Measurement of Dermatophagoides mite allergens on bedding and human skin surfaces

Impact of house dust mite in vitiligo skin: environmental contribution to increased cutaneous immunity and melanocyte detachment

BACKGROUND

Vitiligo is an autoimmune skin disorder characterized by loss of melanocytes. Protease-mediated disruption of junctions between keratinocytes and/or keratinocyte intrinsic dysfunction may directly contribute to melanocyte loss. House dust mite (HDM), an environmental allergen with potent protease activity, contributes to respiratory and gut disease but also to atopic dermatitis and rosacea.

OBJECTIVES

To verify if HDM can contribute to melanocyte detachment in vitiligo and if so, by which mechanism(s).

METHODS

Using primary human keratinocytes, human skin biopsies from healthy donors and patients with vitiligo, and 3D reconstructed human epidermis, we studied the effect of HDM on cutaneous immunity, tight and adherent junction expression and melanocyte detachment.

RESULTS

HDM increased keratinocyte production of vitiligo-associated cytokines and chemokines and increased expression of toll-like receptor (TLR)-4. This was associated with increased in situ matrix-metalloproteinase (MMP)-9 activity, reduced cutaneous expression of adherent protein E-cadherin, increased soluble E-cadherin in culture supernatant and significantly increased number of suprabasal melanocytes in the skin. This effect was dose-dependent and driven by cysteine protease Der p1 and MMP-9. Selective MMP-9 inhibitor, Ab142180, restored E-cadherin expression and inhibited HDM-induced melanocyte detachment. Keratinocytes from patients with vitiligo were more sensitive to HDM-induced changes than healthy keratinocytes. All results were confirmed in a 3D model of healthy skin and in human skin biopsies.

CONCLUSIONS

Our results highlight that environmental mite may act as an external source of pathogen-associated molecular pattern molecules in vitiligo and topical MMP-9 inhibitors may be useful therapeutic targets. Whether HDM contributes to the onset of flares in vitiligo remains to be tested in carefully controlled trials.

Cross-reactivity of each fraction among cereals in children with wheat allergy

BACKGROUND

Cross-reactivity between wheat and other cereals is a crucial issue in the management of wheat allergy. Few studies have reported in vitro cross-reactivity in immediate-type wheat allergy. The aim of this study aimed to examine cross-reactivity of the three fractions (albumin/globulin, gliadin, and glutenin fractions) among cereals in children with wheat allergy.

METHODS

Sera from 128 children with immediate-type wheat allergy were collected. Specific immunoglobulin E (sIgE) levels against each fraction of wheat, barley, and rye were measured by enzyme-linked immunosorbent assay (ELISA). Cross-reactivities of each fraction among wheat, barley, and rye were examined via inhibition ELISA.

RESULTS

All subjects were sensitized to all fractions of wheat, barley, and rye. The wheat sIgE levels were significantly higher than those of barley and rye in all the fractions (p ≤ .001) and were significantly correlated with sIgE levels in each fraction (r = .887-.969, p < .001). Inhibition ELISA revealed that wheat inhibited the IgE binding to most of the solid phases at lower protein levels compared with barley and rye in all fractions.

CONCLUSIONS

In children with immediate-type wheat allergy, sensitization to all the three fractions of wheat was observed. In addition, they showed sensitization to barley and rye caused by in vitro cross-reactivity with wheat in each fraction. When managing children with wheat allergy, sensitization to barley and rye caused by the cross-reactivities should be considered.

Immunohistopathological Analysis of Immunoglobulin E-Positive Epidermal Dendritic Cells with House Dust Mite Antigens in Naturally Occurring Skin Lesions of Adult and Elderly Patients with Atopic Dermatitis

The immunopathogenic role of house dust mite (HDM) allergens in the development of skin lesions in atopic dermatitis (AD) has not yet been precisely clarified. We immunohistopathologically evaluated the localization of immunoglobulin E (IgE)-positive epidermal dendritic cells with HDM antigens in the skin lesions of patients with IgE-allergic AD. Using double-immunofluorescence and single-immunochemical staining methods, we analyzed biopsy specimens from the skin lesions of six patients with IgE-allergic AD and HDM allergy and 11 control subjects with inflammatory skin disorders. Inflammatory dendritic epidermal cells (IDECs; CD11c+ and CD206+ cells) were markedly observed in the central area of the spongiotic epidermis of skin lesions in all AD patients. Furthermore, IgE-positive IDECs with HDM antigens in the central areas of the spongiosis were found in four of the six (66.7%) AD patients. Langerhans cells (LCs; CD207+ cells) with HDM antigens were also observed in the peripheral areas of the spongiosis. Infiltration of CD4+ and CD8+ T cells in association with IgE-positive IDECs and LCs with HDM antigens was seen in the spongiotic epidermis. An IgE-mediated delayed-type hypersensitivity reaction, in combination with IgE-bearing dendritic cells, specific T cells, keratinocytes, and HDM antigens, may lead to spongiotic tissue formation in eczematous dermatitis in AD.

Atopic Dermatitis in Older Adults: A Review of Treatment Options

Atopic dermatitis (AD) in older adults (elderly AD) has recently emerged as a newly defined subgroup of AD. When selecting treatment options, clinical characteristics of elderly AD and age-specific factors of older patients must be considered. As in other age groups, regular application of moisturizers in combination with topical corticosteroids and calcineurin inhibitors, adjunctive administration of oral antihistamines/anti-allergic drugs, and avoidance of exacerbating factors comprise basic treatments for elderly AD. For moderate-to-severe cases and/or in those with a decreased ability to use topical treatments, powerful anti-inflammatory treatments may become necessary as additional treatment options. While low-dose oral corticosteroids may be useful for cases of elderly AD, careful attention should be paid to adverse effects. Oral cyclosporine (ciclosporin) is less commonly used due to the increased risk of malignancy and organ toxicity in older patients with AD. Narrow-band ultraviolet B phototherapy may also be useful for older patients, although the necessity of frequent hospital visits for irradiation therapy may become a burden of disease for such patients. As a biologic, dupilumab therapy markedly improves skin lesions and itch in older patients with AD, with a rapid response and non-serious adverse effects. Nevertheless, injection pain, expensive medical care, and regular follow-up every 2 weeks are disadvantages of dupilumab therapy. Therefore, clinicians must prioritize individualized treatment options that will reduce the burden of disease for cases of elderly AD.

Consideration of methods for identifying mite allergens

House dust mites are small arthropods that produce proteins—found in their feces, body parts, and eggs—that are major triggers of human allergies worldwide. The goal of this review is to describe the current methods used to identify these allergens. A literature search for allergen identification methods employed between 1995 and 2016 revealed multiple techniques that can be broadly grouped into discovery and confirmation phases. The discovery phase employs screening for mite proteins that can bind IgEs in sera from animals or patients allergic to dust mites. The confirmation phase employs biochemical methods to isolate either native or recombinant mite proteins, confirms the IgE binding of the purified allergens, and uses either in vitro or in vivo assays to demonstrate that the purified antigen can stimulate an immune response. The methods used in the two phases are defined and their strengths and weaknesses are discussed. The majority of HDM-allergic patients may respond to just a small subset of proteins, but new protein discovery methods are still warranted in order to develop a complete panel of HDM allergens for component resolved diagnosis and patient-tailored therapies.

Effective allergen avoidance for reducing exposure to house dust mite allergens and improving disease management in adult atopic asthmatics

OBJECTIVE

We investigated the best strategy for adult asthmatics to avoid exposure to Dermatophagoides group (Der-1) allergens.

METHODS

Adult atopic asthmatics (n = 111) followed a 32-item checklist for avoiding Der-1 allergen exposure. Twenty-five patients were excluded through incomplete sampling; 50 remaining patients encased their pillows/futons/mattresses in microfine-fiber covers, 13 used vacuum cleaners with dust-mite-collection nozzles, and 23 acted as non-intervention controls. During August-October 2010 and August-October 2011, dust samples were collected in Petri dishes placed in bedrooms for 2 weeks and from mattresses/futons by using adhesive tape on one morning. A Der-1 level decrease was defined as a mean 2011 Der-1 level of <1 as a ratio of the 2010 level on tape or Petri dish samples. We analyzed the associations between Der-1 level change (by ELISA) and % weekly variability in peak expiratory flow (PEF) or fraction of exhaled nitric oxide (FeNO) after intervention.

RESULTS

Der-1 levels decreased significantly in the covers group but not the vacuuming group. FeNO levels and PEF variability were unchanged in both groups. In patients whose Petri dish or tape samples showed decreased Der-1 levels, the % PEF variability was lower in 2011 than in 2010, but FeNO levels were unchanged. Three interventions (vacuuming all family members' mattress/futon surfaces at least weekly or after exposure of the futons to sunlight, and floor wiping before vacuuming), plus using covers, were the most effective management strategy in reducing Der-1 levels.

CONCLUSIONS

This environmental and bedding maintenance program may help manage adult atopic asthma.

Encasing bedding in covers made of microfine fibers reduces exposure to house mite allergens and improves disease management in adult atopic asthmatics

BACKGROUND

Studies of avoidance of exposure to group 1 allergens of the Dermatophagoides group (Der p 1) have not yielded consistent improvements in adult asthma through avoidance. We explored whether the use of pillow and bed covers and allergen-avoidance counseling resulted in Der 1-level reduction, as measured by enzyme-linked immunosorbent assay, and thus improved asthma symptoms in adult patients.

METHODS

Twenty-five adult patients with moderate or severe atopic asthma were randomized into intervention and control groups. Intervention patients slept on pillows and mattresses or futons encased in microfine-fiber covers and were counseled in allergen avoidance through bedroom cleaning. Control patients received neither special covers nor counseling. In the period August to October in 2009 (pre-intervention) and 2010 (post-intervention), dust samples were collected in open Petri dishes placed in bedrooms for 2 weeks and by rapid lifting of dust from bedding and skin using adhesive tape on the morning of 1 day of Petri dish placement. We examined the associations between changes in Der 1 level (as measured by enzyme-linked immunosorbent assay) and clinical symptom score, minimum % peak expiratory flow, and fraction of exhaled nitric oxide.

RESULTS

Der 1 allergen levels on the mattress/futon covers and near the floor of the bedrooms of intervention patients, but not controls, were lower in 2010 than in 2009. From 2009 to 2010, asthma symptom scores decreased significantly, and minimum % peak expiratory flow increased significantly, in intervention patients. The fall in Der p 1 concentration was correlated with a reduction in the fraction of exhaled nitric oxide.

CONCLUSIONS

Minimization of Der 1 allergen exposure by encasing pillows and mattresses or futons and receiving counseling on avoiding exposure to indoor allergens improved asthma control in adult patients.

Innate immune responses in house dust mite allergy

Sensitizations to house dust mites (HDM) trigger strong exacerbated allergen-induced inflammation of the skin and airways mucosa from atopic subjects resulting in atopic dermatitis as well as allergic rhinitis and asthma. Initially, the Th2-biased HDM allergic response was considered to be mediated only by allergen B- and T-cell epitopes to promote allergen-specific IgE production as well as IL-4, IL-5, and IL-13 to recruit inflammatory cells. But this general molecular model of HDM allergenicity must be revisited as a growing literature suggests that stimulations of innate immune activation pathways by HDM allergens offer new answers to the following question: what makes an HDM allergen an allergen? Indeed, HDM is a carrier not only for allergenic proteins but also microbial adjuvant compounds, both of which are able to stimulate innate signaling pathways leading to allergy. This paper will describe the multiple ways used by HDM allergens together with microbial compounds to control the initiation of the allergic response through engagement of innate immunity.

Dissecting the causes of atopic dermatitis in children: less foods, more mites

Atopic dermatitis (AD) is a common, chronic or chronically relapsing, multifactorial skin disease that mainly occurs in children but affects also adults. AD usually begins early in life and often concerns people with a personal or family history of asthma and allergic rhinitis. AD is characterized by eczematous changes in the epidermis and originates from a late, T-cell mediated reaction associated to the formation and production of memory T-cell of TH2 type, occurrence of homing receptor at skin level and cutaneous lymphocyte-associated (CLA) antigens. Extrinsic or allergic AD, but not intrinsic AD, shows high total serum IgE levels and the presence of specific IgE for environmental and food allergens. A pivotal role in the pathogenesis of AD is played by filaggrin, a protein contained in the granular layer of the epidermis regulating the aggregation of keratin filaments. Mutation in the filaggrin gene causes decreased barrier function of the corny layers of the epidermis. This favours the enter through the skin of environmental allergens, especially the house dust mite, that further facilitates such entering by the proteolytic activity of its major allergen Der p 1. In fact, recent advances suggest that the dust mite, more than foods, is the major cause of allergic AD. As far as the causal diagnosis of AD is concerned, there is notable evidence supporting the capacity of the atopy patch test (APT) to reproduce the pathophysiologic events of AD. This makes APT a valuable diagnostic tool for AD.

Effect of exposure and sensitization to indoor allergens on asthma control level

BACKGROUND

Reducing risk factors, such as exposure to allergens, and stepwise pharmacotherapy to achieve and maintain control of asthma are the mainstay of asthma care. The purpose of this study was to clarify the effect of exposure and sensitization to indoor allergens, including house dust mites, cats, and dogs, on the asthma control level.

METHODS

Dust samples were collected from the mattresses of 101 adult asthma patient homes and the Dermatophagoides mite group 1 (Der 1), Fel d 1, and Can f 1 concentrations were measured using ELISA. Sensitization was determined by positive specific IgE antibodies. The Asthma Control Test (ACT), lowest peak expiratory flow (PEF) during 1 week expressed as a percentage of the highest PEF (Min%Max PEF), and spirometry were measured for the assessment of asthma control. Univariate and multivariate regression analyses were used to assess the relationships.

RESULTS

Sixty-nine patients were exposed to high levels (>10μg/g dust for Der 1 and Can f 1 and >8μg/g dust for Fel d 1) of 1 or more allergens and 39 patients were sensitized to at least one allergen. Multivariate logistic regression analyses revealed that the FEV(1) (% of predicted value) was associated with low ACT scores (≤19) and that the number of highly exposed allergens and inhaled corticosteroid dose were associated with a low level of Min%Max PEF (<80%).

CONCLUSIONS

The level of exposure to multiple indoor allergens, but not sensitization, is associated with the asthma control level determined by PEF variation.

Immunomodulation of skin cytokine secretion by house dust mite extracts

BACKGROUND

Skin contact with house dust mites may contribute to atopic dermatitis and other skin diseases. We sought to determine if molecules from house dust mites could influence the release of proinflammatory cytokines and chemokines from epidermal keratinocytes and dermal fibroblasts grown in a human skin equivalent (HSE) model.

METHODS

HSEs consisting of an epidermis of keratinocytes with stratum corneum over a dermis of fibroblasts in a collagen matrix were challenged with Dermatophagoides farinae, D. pteronyssinus and Euroglyphus maynei mite extracts.

RESULTS

HSEs secreted interleukin (IL)-1α, IL-1 receptor antagonist, IL-6, IL-8, cutaneous T cell-attracting chemokine, transforming growth factor-α, granulocyte/macrophage and macrophage colony-stimulating factors and vascular endothelial cell growth factor in response to at least 1 mite extract. Extracts of different mite species stimulated HSEs to release different cytokines. Therefore, extracts of different species contained different molecules or different concentrations of similar molecules. The cytokine release profiles of cells in the HSEs were not the same as for monocultured keratinocytes and fibroblasts.

CONCLUSIONS

Molecules from house dust mites are capable of inducing the release of multiple proinflammatory cytokines and chemokines from epidermal keratinocytes and dermal fibroblasts. Avoiding skin contact with house dust mites would reduce the possibility of mite-induced inflammation in the skin. Therefore, measures to reduce contact with mite molecules such as frequent vacuuming of upholstered furniture and carpets and laundering of clothing and bedding to remove mite molecules and allergens could reduce skin contact with mite molecules and diminish exacerbations of skin inflammation in patients with atopic dermatitis and other skin diseases.

Evaluation of the presence of house dust mites in horse rugs

A sample of fourteen horse rugs and two saddle blankets stored in south western Sydney, Australia, an area of known high dust mite prevalence in the human environment, were analysed for the presence of house dust mites. Dust samples from the rugs, blankets and 16 control sites were collected using a vacuum cleaner with a modified attachment and filter. Dust mites were extracted using an adapted floatation technique. Eight rugs and all control samples were positive for mites, which were confirmed to be house dust mites of the genus Dermatophagoides. This study confirms that exposure to house dust mites from horse rugs can occur, indicating that house dust mite allergen reactivity on intradermal and serum allergy testing in atopic horses may represent true dust mite hypersensitivity. Nevertheless, quantification studies will be necessary to ensure that there is adequate mite exposure for development of hypersensitivity, and further evaluation of immunological responses, avoidance and provocation, and specific immunotherapy are required to confirm the clinical relevance. To the authors' knowledge, this is the first study to document the presence of house dust mites in the equine environment.

Barrier dysfunction caused by environmental proteases in the pathogenesis of allergic diseases

Skin barrier dysfunction has emerged as a critical driving force in the initiation and exacerbation of atopic dermatitis and the "atopic march" in allergic diseases. The genetically determined barrier deficiency and barrier disruption by environmental and endogenous proteases in skin and epithelium are considered to increase the risk of sensitization to allergens and contribute to the exacerbation of allergic diseases. Sources of allergens such as mites, cockroaches, fungi, and pollen, produce or contain proteases, which are frequently themselves allergens. Staphylococcus aureus, which heavily colonizes the lesions of atopic dermatitis patients and is known to trigger a worsening of the disease, also produces extracellular proteases. Environmental proteases can cause barrier breakdown in the skin, not only in the epithelium, and stimulate various types of cells through IgE-independent mechanisms. Endogenous protease inhibitors control the functions of environmental and endogenous proteases. In this review, we focus on the barrier dysfunction caused by environmental proteases and roles of endogenous protease inhibitors in the pathogenesis of allergic diseases. Additionally, we examine the subsequent innate response to Th2-skewed adaptive immune reactions.

[Dampness, biological factors and sick house syndrome]

Sick house syndrome is caused by not only chemicals but also dampness and biological factors. Many European and North American studies have shown that dampness associated with condensation, visible mold, moldy odor, and water-induced damage among others affects residents' health. Recent Japanese studies have also shown a similar significant relationship. Mold can cause infection and allergy, and can produce chemicals such as microbial volatile organic compounds (MVOCs) and (1-->3)-Beta-D-glucan. Mold exposure can be analyzed using culture-based (colony forming unit count) enumeration techniques. More recently, other nonculture-based methods of measuring mold concentrations in indoor environments have been described, which may provide more valid measures of exposure. These are based on measurement of specific mold markers in dust or air, such as ergosterol, genus-specific extracellular polysaccharides or (1-->3)-Beta-D-glucan. Mites are major indoor allergens. The gold standard for measuring exposure to mite allergens is enzyme-linked immunosorbent assay (ELISA), but it is relatively expensive and requires specialized techniques. Several simple semiquantitative dust mites allergen test have b available in Japan.

Mite serine protease activates protease-activated receptor-2 and induces cytokine release in human keratinocytes

BACKGROUND

House dust mites produce serine and cysteine proteases. Mite-derived proteases have been suggested to be involved in the pathogenesis of allergies; however, whether mite-derived serine protease activity can stimulate keratinocytes remains unknown.

METHODS

We examined the activation of primary human keratinocytes by serine protease-rich extract of whole mite culture and compared with that by recombinant group 1 allergens (rDer f 1 and rDer p 1), which exclusively exhibit cysteine protease activity.

RESULTS

Protease activity of whole mite culture extract (WCE), rDer f 1 and rDer p 1 induced the release of IL-8 and granulocyte-macrophage colony-stimulating factor. Protease activity of WCEs induced a significant upregulation of their mRNA expression but rDer f 1 had much less effect. Protease activity of the WCE stimulated intracellular Ca(2+) mobilization but rDer f 1 and rDer p 1 did not. The mobilization induced by agonists for the human protease-activated receptor (PAR)-2, an agonist peptide or trypsin, was diminished by pre-incubation of keratinocytes with WCE. rDer f 1 inefficiently cleaved a synthetic N-terminal peptide of PAR-2 at different sites from trypsin, but the resultant peptides did not stimulate the release of interleukin-8.

CONCLUSIONS

The results suggest that mite-derived serine protease activity may contribute to the pathogenesis of atopic dermatitis by activating keratinocytes via PAR-2 activation but cysteine protease activity of Der f 1 and Der p 1 acts via another mechanism.

House dust mite extracts activate cultured human dermal endothelial cells to express adhesion molecules and secrete cytokines

The human skin contacts molecules from house dust mites that are ubiquitous in many environments. These mite-derived molecules may penetrate the skin epidermis and dermis and contact microvascular endothelial cells and influence their function. The purpose of this study was to determine the response of normal human dermal microvascular endothelial cells to extracts of the dust mites, Dermatophagoides farinae, D. pteronyssinus, and Euroglyphus maynei with and without endotoxin (lipopolysaccharide). Endothelial cells were stimulated with mite extracts and the expression of surface molecules and the secretion of cytokines were measured in the absence and presence of polymyxin B to bind endotoxin. All three mite extracts stimulated endothelial cells to express intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), and E-selectin and to secrete interleukin (IL)-6, IL-8, monocyte chemoattractant protein (MCP-1), and granulocyte/macrophage colony stimulating factor (GM-CSF). Euroglyphus maynei-induced expression of all the cell surface molecules was not inhibited when the endotoxin activity in the mite extract was inhibited. In contrast, endothelial cells challenged with D. farinae or D. pteronyssinus extract depleted of endotoxin activity expressed only constitutive levels of ICAM-1, VCAM-1, and E-selectin. D. farinae and E. maynei extracts depleted of endotoxin activity still induced secretion of IL-8 and MCP-1 but at reduced levels. Only constitutive amounts of IL-6, G-CSF, and GM-CSF were secreted in response to any of the endotoxin-depleted mite extracts. Extracts of D. farinae, D. pteronyssinus, and E. maynei contain both endotoxins and other molecules that can stimulate expression of cell adhesion molecules and chemokine receptors and the secretion of cytokines by normal human microvascular endothelial cells.

House dust mites on skin, clothes, and bedding of atopic dermatitis patients

BACKGROUND

Atopic dermatitis is a common allergic condition in children, often associated with a positive skin reaction to house dust mite allergens.

AIM

To determine the presence of house dust mites on the skin, clothes, and bedding of patients with atopic dermatitis.

METHODS

Nineteen patients with atopic dermatitis were examined during a 2-year period. Samples from affected and healthy skin surfaces were obtained with adhesive tape, and dust samples from bedding and clothes were collected with a vacuum cleaner at the start of the study and 3-6 weeks later, and examined for the presence of house dust mites. The findings were compared with those of 21 healthy controls.

RESULTS

The most common mite species on skin were Dermatophagoides pteronyssinus and Dermatophagoides farinae, which were found in nine patients and three controls. The patient group showed a significantly larger percentage of samples with mites than did the control group (34.9% and 7.9%, respectively) (P < 0.001), and a significantly larger percentage of individuals with at least one positive sample (84.2% and 14.2%, respectively) (P < 0.0001). No correlation was found between the number of mites on the skin and clothes/bedding of patients, or between patients and controls with regard to the number of mites on the clothes and bedding.

CONCLUSIONS

Patients with atopic dermatitis showed a higher prevalence of mites on their skin than did healthy individuals, which could be involved in allergic sensitization and disease exacerbation.

House dust and storage mite extracts influence skin keratinocyte and fibroblast function

BACKGROUND

The bodies of allergy-causing dust and storage mites likely contain many bioreactive molecules, including some that are allergenic. These molecules may penetrate the epidermis and dermis of the skin. However, little is known about the effects that most of the molecules from mites have on the function of cells in the skin, the overall inflammatory and immune reactions and the manifestation of allergic disease. The purpose of this research was to determine the response of cultured skin cells (keratinocytes and fibroblasts) to extracts of house dust and storage mites.

METHODS

Normal human epidermal keratinocytes and dermal fibroblasts were cultured with varying doses of extracts of the storage mites Acarus siro, Chortoglyphus arcuatus or Lepidoglyphus destructor or of the house dust mites Dermatophagoides farinae, D. pteronyssinus or Euroglyphus maynei in the absence or presence of lipopolysaccharide. Culture supernatants were collected 24 h later and assayed for the presence of various chemokines and cytokines.

RESULTS

Keratinocytes constitutively secreted interleukin (IL)-1 receptor antagonist/IL-1F3, growth-related oncogene alpha and transforming growth factor alpha, and these secretions were modulated by extracts of 1 or more of the mites tested. Mite extracts also modulated the production of IL-6, IL-8, monocyte chemoattractant protein 1, macrophage colony-stimulating factor and vascular endothelial growth factor from fibroblasts.

CONCLUSIONS

The effects that mite extracts exerted on both keratinocytes and fibroblasts varied among the house dust mite species, among the storage mite species and between the house dust and storage mites. This study showed that extracts of mites contain substances that modulate the production of proinflammatory cytokines and chemokines secreted by normal human epidermal keratinocytes and dermal fibroblasts, and therefore may influence the course of pathophysiology in the skin in atopic dermatitis.

Symptom definitions for SBS (sick building syndrome) in residential dwellings

The potential risk factors for sick building syndrome (SBS) in newly built dwellings were investigated. Two different definitions for SBS were used, a narrow definition (symptoms related to home environment and continuously occurring in the last 3 months were regarded as positive) and another relatively broad definition (symptoms related to home environment and either continuously or sporadically occurring in the last 3 months were regarded as positive). With both definitions indoor air chemicals, especially TVOC, and high stress during work were found to be significantly associated with SBS symptoms. Allergic history was more associated with narrow-sense symptoms and odor perception with broad-sense symptoms. The results indicate that the broad definition be preferred to find more potential risk factors.

Cystatin A inhibits IL-8 production by keratinocytes stimulated with Der p 1 and Der f 1: Biochemical skin barrier against mite cysteine proteases

BACKGROUND

Der p 1 and Der f 1 are the most immunodominant allergens produced by house dust mites and are suspected to be involved in the pathogenesis of allergy through their cysteine protease activity. However, stimulation of keratinocytes by these protease allergens and protective systems in the skin against them have not been well investigated.

OBJECTIVE

We purified and identified the dominant skin-derived inhibitor against the proteolytic activities of these allergens and analyzed its effect on keratinocyte activation.

METHODS

Recombinant allergens were used for the experiments. We analyzed whether human sweat inhibits the enzymatic activities of Der p 1 and Der f 1 and used sweat as the skin-derived material to isolate the inhibitor. The inhibitor was purified by means of column chromatography and subsequently identified by means of protein sequencing and immunoblotting. Keratinocytes were stimulated with the allergens in the absence or presence of the inhibitor, and the concentration of secreted IL-8 was measured.

RESULTS

Sweat inhibited the proteolytic activities of Der p 1 and Der f 1. The sweat inhibitor was identified as cystatin A. The stimulation of normal human keratinocytes and the human keratinocyte cell line HaCaT with these protease allergens upregulated IL-8 secretion, and addition of cystatin A blocked this upregulation. Normal human keratinocytes secreted cystatin A into the medium.

CONCLUSIONS

The proteolytic activity of Der p 1 and Der f 1 stimulates human keratinocytes in vitro. Cystatin A produced by keratinocytes is the dominant biochemical skin barrier that eliminates the enzymatic activity of these mite cysteine proteases and prevents them from stimulating keratinocytes.