Microbe-host interplay in atopic dermatitis and psoriasis.

Despite recent advances in understanding microbial diversity in skin homeostasis, the relevance of microbial dysbiosis in inflammatory disease is poorly understood. Here we perform a comparative analysis of skin microbial communities coupled to global patterns of cutaneous gene expression in patients with atopic dermatitis or psoriasis. The skin microbiota is analysed by 16S amplicon or whole genome sequencing and the skin transcriptome by microarrays, followed by integration of the data layers.

Optimizing of the basophil activation test: Comparison of different basophil identification markers.

Background: Flowcytometric identification of basophils is a prerequisite for measuring activation of basophils with IgE-dependent or IgE-independent stimuli. Aim of this study was to compare different marker combinations in a simultaneous multicolor flowcytometric measurement.

Methods: Ten patients with a grass pollen allergy and three controls were included in the study.

Optimizing of the basophil activation test: Comparison of different basophil identification markers.

Background Flowcytometric identification of basophils is a prerequisite for measuring activation of basophils with IgE-dependent or IgE-independent stimuli. Aim of this study was to compare different marker combinations in a simultaneous multicolor flowcytometric measurement. Methods Ten patients with a grass pollen allergy and 3 controls were included in the study.

Basophil activation test using recombinant allergens: highly specific diagnostic method complementing routine tests in wasp venom allergy.

Background: Skin testing can expose allergic subjects to potential systemic reactions, sensitization against unrelated proteins, and increased risk of future sting reactions. Therefore the continuous improvement of in vitro diagnostic methods is desirable. Recombinant allergens have been shown to improve the sensitivity of specific IgE (sIgE) detection in vitro whilst no data is available regarding their application and reliability in basophil activation test (BAT).

Allergic contact dermatitis in psoriasis patients: typical, delayed, and non-interacting.

Psoriasis is characterized by an apoptosis-resistant and metabolic active epidermis, while a hallmark for allergic contact dermatitis (ACD) is T cell-induced keratinocyte apoptosis. Here, we induced ACD reactions in psoriasis patients sensitized to nickel (n = 14) to investigate underlying mechanisms of psoriasis and ACD simultaneously. All patients developed a clinically and histologically typical dermatitis upon nickel challenge even in close proximity to pre-existing psoriasis plaques.

Intraindividual genome expression analysis reveals a specific molecular signature of psoriasis and eczema.

Previous attempts to gain insight into the pathogenesis of psoriasis and eczema by comparing their molecular signatures were hampered by the high interindividual variability of those complex diseases. In patients affected by both psoriasis and nonatopic or atopic eczema simultaneously (n = 24), an intraindividual comparison of the molecular signatures of psoriasis and eczema identified genes and signaling pathways regulated in common and exclusive for each disease across all patients. Psoriasis-specific genes were important regulators of glucose and lipid metabolism, epidermal differentiation, as well as immune mediators of T helper 17 (TH17) responses, interleukin-10 (IL-10) family cytokines, and IL-36.

CX₃CL1 (fractalkine) and its receptor CX₃CR1 regulate atopic dermatitis by controlling effector T cell retention in inflamed skin.

Atopic dermatitis (AD) is a chronic allergic dermatosis characterized by epidermal thickening and dermal inflammatory infiltrates with a dominant Th2 profile during the acute phase, whereas a Th1 profile is characteristic of the chronic stage. Among chemokines and chemokine receptors associated with inflammation, increased levels of CX3CL1 (fractalkine) and its unique receptor, CX3CR1, have been observed in human AD. We have thus investigated their role and mechanism of action in experimental models of AD and psoriasis.

Human IL-31 is induced by IL-4 and promotes TH2-driven inflammation.

Background: The pruritic cytokine IL-31 has been shown to be expressed by murine activated effector T Lymphocytes of a TH2 phenotype. Like IL-17 and IL-22, IL-31 is a tissue-signaling cytokine the receptor of which is mainly found on nonimmune cells. An overabundance of IL-31 has been shown in patients with atopic disorders, including dermatitis, as well as asthma, and therefore represents a promising drug target, although its regulation in the context of the human TH2 clusters is not yet known.

IL-22 suppresses IFN-γ-mediated lung inflammation in asthmatic patients.

Background: IL-22 controls tissue homeostasis by both proinflammatory and anti-inflammatory effects. However, the anti-inflammatory mechanisms of IL-22 remain poorly investigated.

Objective: We sought to investigate the anti-inflammatory role for IL-22 in human asthma.

Human T cell priming assay (hTCPA) for the identification of contact allergens based on naive T cells and DC--IFN-γ and TNF-α readout.

Many small protein reactive organic and inorganic chemicals can cause allergic contact dermatitis, a T cell mediated inflammatory skin disease. In vitro alternatives to animal testing are needed for the identification of chemicals that pose such risks to human health. We here publish the standard operation procedure for a human T cell priming assay developed primarily for the identification of contact allergens within the integrated EU project Sens-it-iv.

Th17 and Th22 in skin allergy.

Development of eczematous skin reactions depends on disease-specific and time-dependent recruitment of a variety of leukocytes affecting resident skin cells through cytotoxic mechanisms and release of cytokines. Th17 and Th22, defined as RORC+IL-17+ and IL-17-IFN-γ-IL-22+ cells, respectively, belong to a newly identified class of lymphocytes specifically involved in dialogue with non-immune cells. In line with this function, both Th17 and Th22 cells are enriched in many immune-mediated skin diseases, such as a topic dermatitis, allergic contact dermatitis and psoriasis.

IL-22 and TNF-α represent a key cytokine combination for epidermal integrity during infection with Candida albicans.

T cells exercise their full impact on target cells through a combination of secreted cytokines. The recently described T helper cell subset Th22 is characterized by a combinatorial secretion of IL-22 and TNF-α. Here, we demonstrate that IL-22 increases the TNF-α-dependent induction and secretion of several immune-modulatory molecules such as initial complement factors C1r and C1s, antimicrobial peptides S100A7 and HBD-2 (human β defensin 2), and antimicrobial chemokines CXCL-9/-10/-11 in primary human keratinocytes.

CD56 highCD16 - NK cell involvement in cutaneous lichen planus.

Lichen planus is an inflammatory disease of the skin and mucous membranes characterized by vacuolization of basal keratinocytes associated with a prominent junctional lymphocyte infiltrate which comprises T lymphocytes, NK cells, myeloid and plasmacytoid dendritic cells. Basal keratinocyte damage is considered as being a consequence of a lymphocytic cytotoxic attack, mostly mediated by perforin+CD8+ T lymphocytes. NK cells have been described to infiltrate inflamed skin and significantly contribute to the amplification of immune-mediated skin diseases, thanks to their cytotoxic activity and the release of pro-inflammatory cytokines.

IL-17 amplifies human contact hypersensitivity by licensing hapten nonspecific Th1 cells to kill autologous keratinocytes.

Th17 is a newly identified lineage of effector T cells involved in autoimmunity and immune responses to pathogens. We demonstrate in this study the pathogenic role of IL-17-producing CD4(+) T lymphocytes in allergic contact dermatitis (ACD) to skin-applied chemicals. IL-17(+) T cells infiltrate ACD reactions and predominantly distribute at the site of heavy spongiosis.

Ochratoxin A induces craniofacial malformation in mice acting on Dlx5 gene expression.

Ochratoxin A (OTA) is a mycotoxin produced by fungal of Aspergillus species absorbed in human through contaminate food in gastrointestinal tract. OTA has been demonstrated to be teratogenic in a number of species including mice and potentially human. Mice exposed in uterus to OTA develop craniofacial abnormalities such as exencephaly, microencephaly, microphthalmia and facial clefts.

CD56highCD16-CD62L- NK cells accumulate in allergic contact dermatitis and contribute to the expression of allergic responses.

Allergic contact dermatitis is a common disease caused by an exaggerated T cell-mediated immune response to skin-applied haptens. We show in this study that NK cells affect skin immune responses to haptens by releasing type 1 cytokines and inducing keratinocytes apoptosis. Immunohistochemical stainings demonstrated that NK lymphocytes constitute approximately 10% of the inflammatory infiltrate mostly distributed in the superficial dermis and in the epidermis at the site of intense spongiotic changes.

Th22 cells represent a distinct human T cell subset involved in epidermal immunity and remodeling.

Th subsets are defined according to their production of lineage-indicating cytokines and functions. In this study, we have identified a subset of human Th cells that infiltrates the epidermis in individuals with inflammatory skin disorders and is characterized by the secretion of IL-22 and TNF-alpha, but not IFN-gamma, IL-4, or IL-17. In analogy to the Th17 subset, cells with this cytokine profile have been named the Th22 subset.

IL-17 in atopic eczema: linking allergen-specific adaptive and microbial-triggered innate immune response.

Background: Patients with atopic eczema (AE) regularly experience colonization with Staphylococcus aureus that is directly correlated with the severity of eczema. Recent studies show that an impaired IL-17 immune response results in diseases associated with chronic skin infections.

Objective: We sought to elucidate the effect of IL-17 on antimicrobial immune responses in AE skin.