Katja Wichmann

Malassezia sympodialis thioredoxin–specific T cells are highly cross-reactive to human thioredoxin in atopic dermatitis

BACKGROUND IgE-mediated cross-reactivity between fungal antigens and human proteins has been described in patients with atopic dermatitis (AD), but it remains to be elucidated whether there is also cross-reactivity at the T-cell level. OBJECTIVE We sought to explore cross-reactivity at the T-cell level between the fungal thioredoxin (Mala s 13) of the skin-colonizing yeast Malassezia sympodialis and its homologous human thioredoxin (hTrx). METHODS T-cell lines (TCLs) were generated in the presence of rMala s 13 from the peripheral blood and from skin biopsy specimens of positive patch test reactions of patients with AD sensitized to Mala s 13 and hTrx. Patients with AD not sensitized to Malassezia species, healthy subjects, and patients with psoriasis served as control subjects. Mala s 13-specific T-cell clones (TCCs) were generated from TCLs. TCCs were characterized by antigen specificity, phenotype, and cytokine secretion pattern. Human keratinocytes were stimulated with IFN-γ, TNF-α, and IL-4, and the release of hTrx was determined by means of ELISA. RESULTS Mala s 13-specific TCLs and TCCs from the blood and skin of patients with AD sensitized to Mala s 13 and hTrx were fully cross-reactive with hTrx. Mala s 13- and hTrx-specific TCCs could not be generated from control subjects. The majority of cross-reactive TCCs were CD4(+) and coexpressed cutaneous lymphocyte antigen. In addition to T(H)1 and T(H)2 TCCs, we could also identify TCCs secreting IL-17 and IL-22. After stimulation with IFN-γ and TNF-α, keratinocytes released substantial amounts of thioredoxin. CONCLUSION In patients with AD sensitized to Malassezia species, cross-reactivity at the T-cell level to Mala s 13 and the homologous hTrx is detectable. hTrx autoreactive skin-homing T cells might be relevant for cutaneous inflammation in patients with AD.

Isolation of α-toxin-producing Staphylococcus aureus from the skin of highly sensitized adult patients with severe atopic dermatitis.

Background  Staphylococcus aureus (S. aureus) is a well‐known trigger factor of atopic dermatitis (AD). Besides staphylococcal superantigens, α‐toxin may influence cutaneous inflammation via induction of T‐cell proliferation and cytokine secretion.

The role of T‐cell reactivity towards the autoantigen α‐NAC in atopic dermatitis

Background  A subgroup of patients with atopic dermatitis (AD) produces IgE autoantibodies to human proteins which may be present in inflamed skin and perpetuate cutaneous inflammation.

Intrinsic alterations of pro-inflammatory mediators in unstimulated and TLR-2 stimulated keratinocytes from atopic dermatitis patients.

Abstract:  In many patients with atopic dermatitis (AD), the disease is complicated by their enhanced susceptibility to bacterial skin infections, especially with Staphylococcus aureus (S. aureus). Resistance to bacterial skin infections, e.g. S. aureus, is based on the function of intact innate immune mechanisms in the epidermis, mainly provided by keratinocytes. Toll‐like receptor (TLR)‐2 recognizes components of S. aureus and is known to be expressed on keratinocytes. The aim of this study was to investigate intrinsic TLR‐2 expression and cytokine secretion upon TLR‐2 stimulation with peptidoglycan (PGN), lipoteichoic acid (LTA) and N‐palmitoyl‐S‐[2,3‐bis(palmitoyl)‐(2RS)‐propyl]‐(R)cysteinyl‐alanyl‐glycine (Pam3Cys) in keratinocytes from patients with AD compared to healthy controls. Human primary keratinocytes (HPKs) were cultivated from hair follicles of patients with AD and non‐atopic healthy controls and stimulated with Pam3Cys, LTA and PGN. TLR‐2, TLR‐1 and TLR‐6 expression were investigated at the mRNA level. IL‐6, IL‐8, chemokine C‐C motif ligand (CCL)‐20 and MMP‐9 production were studied at the protein level. TLR‐2, TLR‐1 and TLR‐6 were expressed on both HPKs from patients with AD as well as healthy controls without significant differences between these groups. HPKs from patients with AD had an intrinsically reduced capacity to produce IL‐6, IL‐8, CCL‐20 and MMP‐9 and responded less to TLR‐2 stimulation compared to HPKs from healthy controls. Our findings show evidence for intrinsic alterations in HPKs from patients with AD compared to healthy controls and diminished responses upon TLR‐2 stimulation that might contribute to the enhanced susceptibility to skin infections with S. aureus.

Effects of structured patient education in adults with atopic dermatitis: Multicenter randomized controlled trial

Background Atopic dermatitis (AD) is a chronic relapsing skin disease prevalent in 1% to 3% of adults in Western industrialized countries. Objective We sought to investigate the effectiveness of educational training in an outpatient setting on coping with the disease, quality of life, symptoms, and severity in adults with AD. Methods In this German prospective, randomized controlled multicenter study, adult patients with moderate‐to‐severe AD were educated by referring to a comprehensive 12‐hour training manual consented by a multiprofessional study group from different centers (Arbeitsgemeinschaft Neurodermitisschulung für Erwachsene [ARNE]). Patients were randomly allocated to the intervention or waiting control groups. Study visits were performed at baseline and after 1 year (1 year of follow‐up). Primary outcomes were defined as a decrease in (1) “catastrophizing cognitions” with respect to itching (Juckreiz‐Kognitions‐Fragebogen questionnaire), (2) “social anxiety” (Marburger Hautfragebogen questionnaire), (3) subjective burden by symptoms of the disease (Skindex‐29 questionnaire), and (4) improvement of disease signs and symptoms assessed by using the SCORAD index at 1 year of follow‐up. Data were analyzed on an intention‐to‐treat basis. Results At 1 year of follow‐up, patients from the intervention group (n = 168) showed a significantly better improvement compared with the waiting group (n = 147) in the following defined primary study outcomes: coping behavior with respect to itching (P < .001), quality of life assessed by using the Skindex‐29 questionnaire (P < .001), and the SCORAD index (P < .001). Conclusions This is the first randomized, controlled multicenter study on patient education in adult AD. The ARNE training program shows significant beneficial effects on a variety of psychosocial parameters, as well as AD severity.

Birch pollen influence the severity of atopic eczema – prospective clinical cohort pilot study and ex vivo penetration study

There is little clinical evidence for a correlation between the severity of atopic eczema (AE) and pollen exposition. To obtain more data, we performed a clinical cohort pilot study about the influence of pollen on AE between sensitized and nonsensitized subjects and an experimental study addressing the cutaneous penetration of pollen into the skin. Fifty-five patients were monitored during birch pollen season. To study the cutaneous penetration, grass pollen allergens were applied on excised skin and the uptake in CD1c-expressing dendritic cells was investigated. The correlation between environmental pollen load and severity of the Scoring Atopic Dermatitis (SCORAD) score and pruritus was observed, regardless of the status of sensitization. The sensitized group recovered significantly worse after the birch pollen season. Remarkably higher amounts of pollen allergens taken up by CD1c cells were detected in epidermal cells derived from skin explants with a disturbed epidermal barrier. These findings suggest an exacerbating role of pollen in AE utilizing the epidermal route.

Participation of Complement 3a receptor (C3aR) in the sensitization phase of Th2 mediated allergic contact dermatitis

Abstract:  The complement system has emerged as a bridge between innate and adaptive immune responses. An involvement of C3aR has been described during skin inflammation. The aim of the study was to investigate the role of C3a in a mouse model of allergic skin inflammation, such as allergic contact dermatitis (ACD) which is a clinical manifestation of contact sensitivity (CS). The sensitization phase was studied using the local lymph node test: Mice were sensitized on three consecutive days by application of non‐irritant concentrations of toluene‐2,4‐diisocyanate (TDI; 0.5%) onto the ear skin. On day 5, auricular draining lymph nodes were obtained. The elicitation phase was investigated by sensitization with TDI on the depilated and tape‐stripped abdominal skin and challenge with TDI on the ear skin and measuring of ear swelling in vivo and cytokine secretion in activated splenocytes in vitro respectively. Complement 3a receptor deficient (C3aRKO) mice showed increased cytokine responses (interleukin[IL]‐5, IL‐6, IL‐17, granulocyte macrophage‐colony stimulating factor [GM‐CSF]) in the sensitization phase of ACD to TDI. However, no differences in CS responses to TDI were observed in C3aR KO mice compared with WT controls in the elicitation phase of ACD as assessed by measuring of ear swelling in vivo and cytokines in skin and in activated splenocytes in vitro, namely IL‐1α, IL‐2, IL‐4, IL‐5, IL‐6, IL‐10, IL‐17, interferon‐γ (IFN‐γ), GM‐CSF and tumor necrosis factor (TNF)‐α. These findings provide a new insight into the participation of C3a in the sensitization phase of CS immune responses.