IgE-positive epidermal Langerhans cells in allergic contact dermatitis lesions provoked in patients with atopic dermatitis

Effect of Mechanical Stretch on the DNCB-induced Proinflammatory Cytokine Secretion in Human Keratinocytes

Skin is exposed to various physico-chemical cues. Keratinocytes, a major component of the skin epidermis, directly interact with the surrounding extracellular matrix, and thus, biochemical and biophysical stimulations from the matrix regulate the function of keratinocytes. Although it was reported that inflammatory responses of skin were altered by an applied mechanical force, understanding how the keratinocytes sense the mechanical stimuli and regulate a cytokine secretion remains unclear. Here, we designed a device that is able to apply chemo-mechanical cues to keratinocytes and assess their proinflammatory cytokine IL-6 production. We showed that when chemical stimuli were applied with mechanical stimuli simultaneously, the IL-6 production markedly increased compared to that observed with a single stimulus. Quantitative structural analysis of cellular components revealed that the applied mechanical stretch transformed the cell morphology into an elongated shape, increased the cell size, and dictated the distribution of focal adhesion complex. Our results suggest that the mechanical cue-mediated modulation of focal adhesion proteins and actin cytoskeleton translates into intracellular signaling associated with the IL-6 production particularly in skin sensitization. Our study can be applied to understand proinflammatory responses of skin under altered biophysical environments of the skin.

Effects of Angelica gigas Nakai as an Anti-Inflammatory Agent in In Vitro and In Vivo Atopic Dermatitis Models

We investigated the cellular and molecular mechanisms mediating the effects of Angelica gigas Nakai extract (AGNE) through the mitogen-activated protein kinases (MAPKs)/NF-κB pathway using in vitro and in vivo atopic dermatitis (AD) models. We examined the effects of AGNE on the expression of proinflammatory cytokines and chemokines in human mast cell line-1 (HMC-1) cells. Compound 48/80-induced pruritus and 2,4-dinitrochlorobenzene- (DNCB-) induced AD-like skin lesion mouse models were also used to investigate the antiallergic effects of AGNE. AGNE reduced histamine secretion, production of proinflammatory cytokines including interleukin- (IL-) 1β, IL-4, IL-6, IL-8, and IL-10, and expression of cyclooxygenase- (COX-) 2 in HMC-1 cells. Scratching behavior and DNCB-induced AD-like skin lesions were also attenuated by AGNE administration through the reduction of serum IgE, histamine, tumor necrosis factor-α (TNF-α), IL-6 levels, and COX-2 expression in skin tissue from mouse models. Furthermore, these inhibitory effects were mediated by the blockade of the MAPKs and NF-κB pathway. The findings of this study proved that AGNE improves the scratching behavior and atopy symptoms and reduces the activity of various atopy-related mediators in HMC-1 cells and mice model. These results suggest the AGNE has a therapeutic potential in anti-AD.

Allergic and immunologic disorders of the eye. Part I: immunology of the eye

Immuno-ophthalmology evolved during the 20th century as a subspecialty linking ophthalmologists and immunologists. This emerging subspecialty has focused on the use of immunology to better understand and treat ocular disorders. To help the allergist/clinical immunologist better appreciate the growing field of immuno-ophthalmology, this 2-part review series (Part II: Ocular Allergy will appear in the December issue of the Journal) will provide an overview of the impact that immunology has had on our understanding and treatment of allergic and immunologic eye diseases. The current review will focus on mechanisms by which mast cells, T cells, eosinophils, cytokines, and other inflammatory constituents contribute to the unique features of eye disease and their link to allergic responses that occur in other organs of the body.

Increased number of IgE positive Langerhans cells in the conjunctiva of patients with atopic dermatitis

AIM

To determine the role of Langerhans cells (LCs) found to bear IgE in patients with atopic dermatitis (AD) by evaluating the surface distribution of these cells in the conjunctival epithelium and epidermis of skin lesions in patients with AD.

METHODS

The double labelling method was used to evaluate IgE positive cells that were positive for anti-CD1a or anti-CD23 antibody in an epithelial sheet of the conjunctival limbus. Specimens of conjunctiva were obtained from 12 men, six of whom had AD and ocular complications. Five patients without atopic disease served as controls, plus one additional patient with asthma but no AD. A similar study was conducted using epidermal sheets obtained from two patients with AD and from one without AD.

RESULTS

The number of CD1a+ cells present in the conjunctival epithelium of the patients with AD significantly exceeded that of the patients without AD. Most CD1a+ cells in the conjunctival epithelium and epidermis from the patients with AD bore IgE on their surfaces. Few such cells from patients without AD bore IgE. No CD23+ cells were found in the patients with or without AD.

CONCLUSIONS

The presence of an increased number of LCs bearing IgE on their surfaces in the conjunctival epithelium of patients with AD suggests that these cells may be involved in eliciting the hypersensitivity reaction and participate in ocular inflammation.

Aeroallergen patch testing for patients presenting to contact dermatitis clinics

BACKGROUND

The role of aeroallergens in the production of allergic contact dermatitis or "allergic contact dermatitis-like" atopic dermatitis is controversial. Although techniques and allergens lack standardization, most studies find positive patch test results in 30% to 40% of patients with atopic dermatitis.

OBJECTIVE

Our purpose was to determine the prevalence and clinical significance of positive aeroallergen patch tests in patients undergoing standard patch testing for suspected "nonaeroallerge" allergic contact dermatitis.

METHODS

One hundred three consecutive patients referred to three university patch test clinics for patch testing were alos patch tested with six common aeroallergens in glycerine-dust, mold, cat epithelium, tree, grass, and weed-as well as with a glycerine control. Patches were removed at 48 hours. Readings were performed at this time and at 3 to 7 days after initial application.

RESULTS

As determined by history, these 103 patients included 16 patients with both atopic dermatitis and mucosal atopy, 10 patients with atopic dermatitis only, 22 patients with mucosal atopy only, and 55 patients with neither atopic dermatitis nor mucosal atopy. Allergic reactions were seen to one aeroallergen in five patients (three with atopic dermatitis and mucosal allergy, and two with no history of atopy). The prevalence (3 of 16 [18.8%]) of reactions in patients with both atopic dermatitis and mucosal allergy was significantly greater than the prevalence (2 of 87 [2.3%]) in patients with only one or neither of these two atopic disorders (p = 0.02). None of these aeroallergen contact hypersensitivities were deemed significant in the patients' current dermatitis. However, reactions were of past relevance in two of the three patients with atopic dermatitis and mucosal allergy.

CONCLUSION

In this referral group, none of the six common aeroallergens tested was relevant in the origin of suspected "nonaeroallergen" allergic contact dermatitis. This study suggests that aeroallergen patch testing is of little use in the evaluation of patients referred for routine patch testing for suspected "nonaeroallergen" allergic contact dermatitis. Similar but larger studies inclusive of the assessment of relevance, as well as masked controlled clinical trials assessing the effect of aeroallergen exposure and avoidance, are needed to evaluate this issue more fully.

Immunophenotyping of the cellular infiltrate in the early elicitation phase of contact dermatitis in the skin of presensitized atopic individuals

Little is known about the composition of the cellular infiltrate in the early elicitation phase of contact allergy in atopic individuals. Therefore, we rechallenged ten presensitized disease-free atopic volunteers with their known contact allergen and performed biopsies at time 0 and after 6 and 24 h. Ten patients with acute exacerbated atopic dermatitis in the early stage were chosen as a control group. Skin biopsy specimens were processed for immunohistochemistry (APAAP) and evaluated by computer-assisted morphometry. CD4+ and CD45R0+ cells were found to be significantly increased after 6 (t6) and 24 h (t24), and this was accompanied by an enhanced TCR alpha/beta receptor expression at t6-CD45O+ cells showed a marked influx into the epidermis at t24. CD8+ cells infiltrated the basal layer of the epidermis, thus changing the CD4/CD8 ratio from 4.6:1 at t0 to 2.2:1 at t6. CD1a+ epidermal dendritic cells increased significantly from 811 +/- 240/mm2 at t0, to 1210 +/- 333/mm2 at t24 (P < 0.01). At t6 and t24, a so-called 'epitope CD1a+ shedding' was observed into the intercellular spaces of keratinocytes as well as an elongation and enlargement of the dendrites of CD1a+ cells. In the upper dermis, the number of CD1a+ cells increased from 1098 +/- 485/mm2 at t0 to 2388 +/- 740/mm2 at t24 (P < 0.01). In 7/10 volunteers, IgE+ dendritic cells increased significantly in number at t6 (P < 0.02). The activation markers HLA-DR and CD25 were expressed most distinctly at t24. Interestingly, expression of ICAM-1 on keratinocytes occurred only in four of the ten atopic volunteers.(ABSTRACT TRUNCATED AT 250 WORDS)

Atopic dermatitis: recent trends in pathogenesis and therapy

Emerging concepts in the areas related to the pathogenesis and treatment of atopic dermatitis are reviewed. In particular, recent findings have revealed several key steps in the maintenance of a vicious circle of spongiotic dermatitis associated with elevated T-lymphocyte activation, hyperstimulatory Langerhans cells, defective cell-mediated immunity, and B-cell IgE overproduction. The discovery of specific IgE-binding structures on Langerhans cells provides a mechanism for Langerhans cells to capture and present IgE-targeted allergens to allergen-specific T cells. Furthermore, certain microbial allergens that tend to preferentially elicit IgE-type responses also elicit a T-cell response dominated by the IgE-inducing lymphokine interleukin 4. Repeated stimulation by activated Langerhans cells appears to induce just such a response. Abnormal biochemical responsiveness and mediator release by AD monocytes, mast cells, and eosinophils also participate in the sustainment or initiation of such a vicious circle, and contribute directly to the dermatitis as well. Developments in the areas of neuropeptides, genetics, microbial superantigens, and cytokine networks in the skin also appear to have promise in providing a rational link between immune defects and the inflammatory events in AD. Conventional therapy remains the mainstay of atopic dermatitis management; however, new therapies based upon the above concepts are being tested in clinical trials. Although the difficulty of objectively grading AD lesional activity and the high placebo response of AD patients hampers the interpretation of many reports, several types of approaches are coming into focus. The effectiveness of cyclosporin A, which targets T-cell activation and antigen presentation, indicates that additional agents with such activity should be effective, and verifies the criticality of these cells in AD pathogenesis. Therapy with biologic response modifiers, such as interferon gamma or thymopentin, is oriented toward normalization of imbalanced immune responsiveness, rather than direct suppression of the immune system. The mechanism of action of and toxicities of Chinese herbal mixtures require further investigation, but may reveal hitherto unconsidered avenues. Other recent therapeutic trials have focused on reduction of trigger factors, such as house dust mite exposure, foods, and the abnormal epidermal lipid barrier to irritation.

A comparison of expression of surface-bound immunoglobulin E on antigen-presenting cells in cutaneous tissue between patients with allergic, irritant and atopic dermatitis

The expression of surface-bound immunoglobulin E by dendritic cells within cutaneous tissue has been compared in atopic and contact dermatitis. 45 patients were recruited into 4 groups using clinical criteria and patch testing to a standard series of allergens: atopic (12 cases), allergic contact dermatitis (14 cases), irritant contact dermatitis (10 cases) and the control group (9 cases); using clinical criteria and patch testing to a standard series of allergens. Skin biopsies from each patient were analysed by the indirect immunofluorescence technique. This differentiated 3 patterns of cutaneous IgE distribution: (i) no detectable cutaneous IgE; (ii) detection of IgE solely within the dermis; (iii) detection of IgE within both epidermis and dermis. Detection of IgE within the epidermis was always associated with the presence of IgE within the dermis. In each case, IgE was surface-bound by dendritic cells. Immunoglobulin E was detected within both epidermis and dermis in skin biopsies from 8 (66.7%) atopic patients and 2 (20%) patients with irritant contact dermatitis. No other cases demonstrated IgE deposition within both the epidermis and dermis. Atopic patients were significantly more likely to have detectable IgE deposition, within both epidermis and dermis, than patients with contact dermatitis (allergic and irritant groups combined, p = 0.0011) or controls (p = 0.0049). This finding suggests that the demonstration of IgE within both epidermis and dermis supports a diagnosis of atopic dermatitis. It would therefore be of value in differentiating between atopic and contact dermatitis, where clinical diagnosis is in doubt.