Reduced IFN-γ receptor expression and attenuated IFN-γ response by dendritic cells in patients with atopic dermatitis.

BACKGROUND: Atopic dermatitis (AD) is characterized by a predominance of T(H)2 immune reactions but weaker T(H)1 immune responses in acute skin lesions. OBJECTIVES: To evaluate whether enhanced T(H)2 immunity in patients with AD might impair T(H)1 immune responses by affecting the IFN-γ responsiveness of antigen-presenting cells, we investigated IFN-γ receptor and IL-4 receptor α chain expression, IFN-γ signaling, and the expression of IFN-γ-responsive mediators in dendritic cells (DCs) and their precursors from patients with AD compared with those from healthy subjects. METHODS: Skin biopsy specimens were obtained and both monocytes and monocyte-derived dendritic cells (MoDCs) from patients with AD (n = 86) and control subjects (n = 84) were analyzed by means of flow cytometry, real-time PCR, ELISA, and HPLC. RESULTS: We observed lower IFN-γ receptor II expression combined with higher IL-4 receptor α chain expression on epidermal DCs, monocytes, and MoDCs from patients with AD. Induction of IFN-γ-inducible factors, such as interferon regulatory factor 1, interferon-inducible protein 10, and indoleamine 2,3-dioxygenase, was attenuated in IFN-γ-pulsed MoDCs from patients with AD. Weaker signal transducer and activator of transcription 1 activation mirrored by lower phosphorylated signal transducer and activator of transcription 1 levels in response to IFN-γ stimulation could be observed in epidermal DCs, monocytes, and MoDCs from patients with AD. CONCLUSION: Impaired IFN-γ signaling together with attenuated IFN-γ responses in DCs and their precursor cells might contribute to the T(H)2 bias in patients with AD.

Phl p 5 resorption in human oral mucosa leads to dose-dependent and time-dependent allergen binding by oral mucosal Langerhans cells, attenuates their maturation, and enhances their migratory and TGF-beta1 and IL-10-producing properties.

BACKGROUND: Sublingual immunotherapy (SLIT) is safe and effective as treatment of allergic rhinitis and mild asthma. Oral mucosal Langerhans cells (oLCs) play a central role. However, little is known about allergen binding by oLCs during mucosal allergen resorption and its impact on oLC functions. OBJECTIVE: Binding of Phl p 5 to oLCs was studied in a standardized ex vivo model to investigate mechanisms important for SLIT. METHODS: Human oral mucosal biopsies were incubated with the grass pollen allergen Phl p 5. Migration, binding of Phl p 5, phenotype and cytokine production, and T-cell priming of Phl p 5-binding oLCs were analyzed. RESULTS: Significant uptake required more than 5 minutes, and dose-dependent binding of Phl p 5 to oLCs was saturated at 100 microg/mL Phl p 5. Furthermore, Phl p 5 significantly increased the migratory capacity of oLCs but attenuated their maturation and strongly promoted the release of TGF-beta1 and IL-10 by oLCs themselves as well as by cocultured T cells. CONCLUSION: Oral mucosal Langerhans cells bind Phlp5 in a dose-dependent and time-dependent manner, leading to an increased production of tolerogenic cytokines and an enhanced migratory capacity but decelerated maturation of oLCs.

Expression of chemokines and chemokine receptors in lesional and nonlesional upper skin of patients with atopic dermatitis.

BACKGROUND: Trafficking of dendritic cell (DC) subtypes to and from the skin plays a pivotal role in atopic dermatitis (AD). OBJECTIVES: We sought to determine the CCR pattern of epidermal DC subtypes and CCL expression in relation to the state of AD. METHODS: Shave biopsy specimens were taken from patients with AD before and after 24 and 72 hours of atopy patch testing and from the skin of patients with chronic AD, skin of patients with psoriasis, and healthy skin. CCR expression of epidermal DCs was studied by using flow cytometry, and chemokine mRNA levels in the skin were quantified by means of real-time PCR. RESULTS: The total number of CD1a(+) epidermal DCs increased and the proportion of Langerin-positive CD1a(+) DCs decreased whereas the percentage of Langerin-negative CD1a(+) DCs increased after allergen application. Expression of CCR5 and CCR6 of Langerin-negative CD1a(+) DCs was characteristic for acute AD. Expression of CCL1, CCL3, CCL4, and CCL11 mRNA was greater in patients with acute AD versus that seen in patients with chronic AD. Only a strong increase of CCLs, in particular CCL1, CCL17, and CCL18, went along with eczema development, and increased CCL1, CCL13, CCL17 and CCL18 expression was specific for patients with chronic AD compared with those with psoriasis. CONCLUSION: Modified recruitment and differentiation of DCs from their dermal and blood precursors occurs in the acute phase of AD. A boost in the amplitude of CCLs after allergen application goes along with eczema development.