Toll-like receptor 7/8 agonists stimulate plasmacytoid dendritic cells to initiate TH17-deviated acute contact dermatitis in human subjects.

BACKGROUND: A standardized human model to study early pathogenic events in patients with psoriasis is missing. Activation of Toll-like receptor 7/8 by means of topical application of imiquimod is the most commonly used mouse model of psoriasis. OBJECTIVE: We sought to investigate the potential of a human imiquimod patch test model to resemble human psoriasis. METHODS: Imiquimod (Aldara 5% cream; 3M Pharmaceuticals, St Paul, Minn) was applied twice a week to the backs of volunteers (n = 18), and development of skin lesions was monitored over a period of 4 weeks. Consecutive biopsy specimens were taken for whole-genome expression analysis, histology, and T-cell isolation. Plasmacytoid dendritic cells (pDCs) were isolated from whole blood, stimulated with Toll-like receptor 7 agonist, and analyzed by means of extracellular flux analysis and real-time PCR. RESULTS: We demonstrate that imiquimod induces a monomorphic and self-limited inflammatory response in healthy subjects, as well as patients with psoriasis or eczema. The clinical and histologic phenotype, as well as the transcriptome, of imiquimod-induced inflammation in human skin resembles acute contact dermatitis rather than psoriasis. Nevertheless, the imiquimod model mimics the hallmarks of psoriasis. In contrast to classical contact dermatitis, in which myeloid dendritic cells sense haptens, pDCs are primary sensors of imiquimod. They respond with production of proinflammatory and TH17-skewing cytokines, resulting in a TH17 immune response with IL-23 as a key driver. In a proof-of-concept setting systemic treatment with ustekinumab diminished imiquimod-induced inflammation. CONCLUSION: In human subjects imiquimod induces contact dermatitis with the distinctive feature that pDCs are the primary sensors, leading to an IL-23/TH17 deviation. Despite these shortcomings, the human imiquimod model might be useful to investigate early pathogenic events and prove molecular concepts in patients with psoriasis.

Clinical features and management of superficial fibromatoses.

Fibromatoses are a group of benign connective tissue tumors characterized by the infiltrative, aggressive proliferation of well-differentiated fibroblasts, leading to frequent local recurrence. Within this heterogeneous disease group, superficial fibromatoses show slower growth and more benign infiltration of surrounding tissues than deep fibromatoses. Superficial fibromatoses relevant to dermatology include palmar, plantar, and penile fibromatosis, knuckle pads, pachydermodactyly and infantile digital fibromatosis. They present clinically with subcutaneous nodules or cords that lead to local infiltration and limited mobility of the affected areas. Treatment options vary from watchful waiting, non-invasive methods such as radiotherapy and intralesional corticosteroid/collagenase injections to radical surgical procedures. Early intervention may disrupt disease progression and may even restore functional ability. These disorders should therefore be recognized and treated early in the course of the disease.

Toll-Like Receptor 7 Staining in Malignant Epithelial Tumors.

BACKGROUND: As important players of the innate immune system, Toll-like receptors (TLRs) and their role for tumorigenesis have been in the focus of research. In particular TLR7 is an interesting candidate, as TLR7 agonists are broadly used for the treatment of cutaneous tumors. However, data addressing the baseline expression of TLR7 in both basal cell carcinoma (BCC) and squamous cell carcinoma (SCC) on the protein level are lacking, while on the genomic level significantly elevated expression of TLR7 in SCC but not in BCC has been demonstrated. AIM: Our aim was to characterize the immunohistochemical staining pattern of TLR7 in SCC and BCC. Besides, we aimed to clarify if, in case of different TLR7 expression between SCC and BCC, TLR7 expression would help to define basosquamous carcinoma (BSC), a tumor entity sharing characteristics of both SCC and BCC. METHODS: We examined histopathological samples from 23 BCC, 4 BSC, and 24 SCC and characterized the expression of TLR7 by immunohistochemistry and immunofluorescence. RESULTS: We found that TLR7 was not expressed by the tumor tissue of SCC, BCC, and BSC, but by inflammatory cells located within the tumoral and/or peritumoral tissue. Whereas the overall expression of TLR7 did not differ between BCC and SCC (30.4% vs. 45.8%, respectively), we found that within the group of SCC, the well-differentiated SCC showed strong tumoral and/or peritumoral immunocellular TLR7 reactivity in contrast to the poorly differentiated SCC (73.33% vs. 11.1%, respectively). Besides, immunofluorescence double staining revealed the expression of TLR7 in immune cells closely interacting with T cells and natural killer cells. CONCLUSIONS: In contrast to genomic data, we did not find a general difference between baseline TLR7 expression of SCC and BCC on the protein level. Nevertheless, the expression of TLR7 by the inflammatory infiltrate associated with SCC may correlate with the degree of differentiation of SCC possibly indicating better outcome.

A novel molecular disease classifier for psoriasis and eczema.

Novel specific therapies for psoriasis and eczema have been developed, and they mark a new era in the treatment of these complex inflammatory skin diseases. However, within their broad clinical spectrum, psoriasis and eczema phenotypes overlap making an accurate diagnosis impossible in special cases, not to speak about predicting the clinical outcome of an individual patient. Here, we present a novel robust molecular classifier (MC) consisting of NOS2 and CCL27 gene that diagnosed psoriasis and eczema with a sensitivity and specificity of >95% in a cohort of 129 patients suffering from (i) classical forms; (ii) subtypes; and (iii) clinically and histologically indistinct variants of psoriasis and eczema. NOS2 and CCL27 correlated with clinical and histological hallmarks of psoriasis and eczema in a mutually antagonistic way, thus highlighting their biological relevance. In line with this, the MC could be transferred to the level of immunofluorescence stainings for iNOS and CCL27 protein on paraffin-embedded sections, where patients were diagnosed with sensitivity and specificity >88%. Our MC proved superiority over current gold standard methods to distinguish psoriasis and eczema and may therefore build the basis for molecular diagnosis of chronic inflammatory skin diseases required to establish personalized medicine in the field.

Type I Immune Response Induces Keratinocyte Necroptosis and Is Associated with Interface Dermatitis.

Interface dermatitis is a characteristic histological pattern that occurs in autoimmune and chronic inflammatory skin diseases. It is unknown whether a common mechanism orchestrates this distinct type of skin inflammation. Here we investigated the overlap of two different interface dermatitis positive skin diseases, lichen planus and lupus erythematosus. The shared transcriptome signature pointed toward a strong type I immune response, and biopsy-derived T cells were dominated by IFN-γ and tumor necrosis factor alpha (TNF-α) positive cells. The transcriptome of keratinocytes stimulated with IFN-γ and TNF-α correlated significantly with the shared gene regulations of lichen planus and lupus erythematosus. IFN-γ, TNF-α, or mixed supernatant of lesional T cells induced signs of keratinocyte cell death in three-dimensional skin equivalents. We detected a significantly enhanced epidermal expression of receptor-interacting-protein-kinase 3, a key regulator of necroptosis, in interface dermatitis. Phosphorylation of receptor-interacting-protein-kinase 3 and mixed lineage kinase domain like pseudokinase was induced in keratinocytes on stimulation with T-cell supernatant-an effect that was dependent on the presence of either IFN-γ or TNF-α in the T-cell supernatant. Small hairpin RNA knockdown of receptor-interacting-protein-kinase 3 prevented cell death of keratinocytes on stimulation with IFN-γ or TNF-α. In conclusion, type I immunity is associated with lichen planus and lupus erythematosus and induces keratinocyte necroptosis. These two mechanisms are potentially involved in interface dermatitis.

Influence of alpine mountain climate of Bavaria on patients with atopic diseases: studies at the Environmental Research Station Schneefernerhaus (UFS - Zugspitze) - a pilot study.

Mountain and maritime climate therapy takes advantage of specific climatic conditions to treat chronic allergic diseases. It was the aim of the study to investigate effects of a 5 day sojourn on atopic diseases at the highest German mountain. In this pilot study 18 patients with grass pollen-induced rhinoconjunctivitis, atopic ezcema or asthma and 11 non-allergic controls were included. Skin physiology parameters, changes of the respiratory and nasal functions, subjective symptoms and blood parameters were measured during a 5-day observation period in the Environmental Research Station Schneefernerhaus (UFS) at the moderate altitude mountain region (Zugspitze; 2650 m alt.) compared to a low altitude area (Munich; 519 m alt.). Several of the skin physiology parameters changed significantly during the observation period (decrease of skin hydration, increase of skin smoothness, skin roughness, skin scaliness and pH-value). In patients with atopic eczema, the SCORAD (Severity Scoring of Atopic Dermatitis) and the scores of the DIELH (Deutsches Instrument zur Erfassung der Lebensqualität bei Hauterkrankungen) did not change significantly. Histamine induced itch decreased significantly. Parameters of nasal function did not change significantly. Several lung parameters showed a slight, but statistically significant improvement (forced expiratory volume in one second/volume capacity [FEV1/VC], peak expiratory flow [PEF], maximum expiratory flow at 50% of vital capacity [MEF 50], maximal mid-expiratory flow between 25% and 75% of vital capacity [MMFEF 25/75]), whereas the vital capacity (VC) decreased significantly. ECP (eosinophil cationic protein) in the serum and parameters of blood count changed significantly. These results show that the benefit of a moderate altitude mountain climate sojourn over a period of 5 days differs in depending on the atopic disease. Especially asthma parameters and itching of the skin improved. It would be interesting to assess the parameters during longer observation periods in alpine climate.

Anaphylactic reactions to local anesthetics.

Local anesthetics (LA) are common elicitors of adverse reactions and the clinical symptoms often correspond to anaphylaxis with tachycardia, hypotension and subjective feelings of weakness, heat or vertigo. The pathomechanism of immediate hypersensitivity reactions to LA is largely unknown -they are commonly regarded as 'pseudo-allergic' or 'non-immune type' anaphylaxis. Immunologically mediated reactions have rarely been observed with positive skin prick tests. Other ingredients in LA preparations have to be considered as elicitors, e.g. preservatives like benzoates or sulfites or latex contaminants in injection bottles. Practical management of patients with a history of LA reaction includes a careful allergy history, skin-prick and intradermal tests. Undiluted LA solutions may elicit false-positive intradermal test reactions. If prick and intradermal tests are negative, the procedure of subcutaneous provocation testing is applied in a placebo-controlled manner. When patients are constantly reacting to placebo, a regimen of 'reverse placebo provocation' with injection of a LA (verum) is applied while the patient is informed about receiving placebo in order to 'rule out psychosomatic involvement'. With this regimen it is possible to eliminate anxiousness and fear, and the patient has proof that he has tolerated the respective LA substance.