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The ubiquitin-editing enzyme A20 (tumor necrosis factor-alpha-induced protein 3) serves as a critical brake on nuclear factor kappa B (NF-kappa B) signaling. In humans, polymorphisms in or near the A20 gene are associated with several inflammatory disorders, including psoriasis. We show here that epidermis-specific A20-knockout mice (A20(EKO)) develop keratinocyte hyperproliferation, but no signs of skin inflammation, such as immune cell infiltration. However, A20(EKO) mice clearly developed ectodermal organ abnormalities, including disheveled hair, longer nails and sebocyte hyperplasia. This phenotype resembles that of mice overexpressing ectodysplasin-A1 (EDA-A1) or the ectodysplasin receptor (EDAR), suggesting that A20 negatively controls EDAR signaling. We found that A20 inhibited EDAR-induced NF-kappa B signaling independent from its de-ubiquitinating activity. In addition, A20 expression was induced by EDA-A1 in embryonic skin explants, in which its expression was confined to the hair placodes, known to be the site of EDAR expression. In summary, our data indicate that EDAR-induced NF-kappa B levels are controlled by A20, which functions as a negative feedback regulator, to assure proper skin homeostasis and epidermal appendage development. Cell Death and Differentiation (2011) 18, 1845-1853; doi:10.1038/cdd.2011.55; published online 13 May 2011

Necroptosis, necrosis and secondary necrosis following apoptosis represent different modes of cell death that eventually result in similar cellular morphology including rounding of the cell, cytoplasmic swelling, rupture of the plasma membrane and spilling of the intracellular content. Subcellular events during tumor necrosis factor (TNF)-induced necroptosis, H2O2-induced necrosis and anti-Fas-induced secondary necrosis were studied using high-resolution time-lapse microscopy. The cellular disintegration phase of the three types of necrosis is characterized by an identical sequence of subcellular events, including oxidative burst, mitochondrial membrane hyperpolarization, lysosomal membrane permeabilization and plasma membrane permeabilization, although with different kinetics. H2O2-induced necrosis starts immediately by lysosomal permeabilization. In contrast, during TNF-mediated necroptosis and anti-Fas-induced secondary necrosis, this is a late event preceded by a defined signaling phase. TNF-induced necroptosis depends on receptor-interacting protein-1 kinase, mitochondrial complex I and cytosolic phospholipase A(2) activities, whereas H2O2-induced necrosis requires iron-dependent Fenton reactions.

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Background and aims-It is not known whether lymphocytic colitis and collagenous colitis represent different clinical entities or constitute part of a spectrum of disease. Methods-Detailed clinical features and histological findings were compared in a large series of patients with confirmed lymphocytic and collagenous colitis. Results-Histological diagnosis was confirmed in 96 patients with collagenous colitis and 80 with lymphocytic colitis. Twenty eight per cent of patients with collagenous colitis and 26% of patients with lymphocytic colitis had overlapping but less pronounced histological features. Both groups were equal in terms of age, use of aspirin and non-steroidal antiinflammatory drugs, associated autoimmune conditions, arthritis, diarrhoea, and abdominal pain. The male:female ratio was 27:73 for collagenous colitis and 45:55 for lymphocytic colitis (p=0.013). Twenty five per cent of patients with collagenous colitis compared with 14% of patients with lymphocytic colitis were active smokers; only 8.3% of patients with collagenous colitis had stopped smoking compared with 23% of patients with lymphocytic colitis (p=0.013). Drug induced disease was suspected for ticlopidine (two collagenous colitis, four lymphocytic colitis) and flutamide (four lymphocytic colitis). Mean duration of symptoms before diagnosis was two months for lymphocytic colitis and four months for collagenous colitis. Overall prognosis was generally mild; 84% of patients with lymphocytic colitis and 74% of patients with collagenous colitis reported resolution or significant improvement (p=0.033). Conclusions-Collagenous and lymphocytic colitis are similar but not identical. Patients with lymphocytic colitis present somewhat earlier and are less likely to be active smokers. Symptoms are milder and more likely to disappear in lymphocytic colitis, Ticlopidine and flutamide should be added to the list of drugs inducing colitis.

H. Ryckeboer Woordenboek van de Vlaamse Dialekten, deel I: Landbouwwoordenschat, Par. Veeteelt, Afl. Rund 1 Tongeren:z.u., Item does not contain fulltext