The inhibitory effect of A20 on the inflammatory reaction of epidermal keratinocytes.

A20 is a negative regulator of nuclear factor κ-light­chain-enhancer of activated B cells (NF-κB) signaling, and has been implicated in the pathogenesis of psoriasis through genome-wide association study (GWAS). In the present study, we investigated the putative role of A20 in epidermal keratinocytes. Immunohistochemical analysis showed that A20 was expressed in all layers of the epidermis, with an increasing pattern in the upper layers. In our model of calcium-induced keratinocyte differentiation, A20 expression was increased in a time-dependent manner. To investigate whether A20 affected keratinocyte differentiation, we overexpressed A20 in cultured keratinocytes. As a result, we noted that A20 overexpression did not affect keratinocyte differentiation, suggesting that A20 is not a direct modulator of keratinocyte differentiation. Interestingly, we found that A20 levels were decreased in psoriatic lesional skin compared to non-lesional areas. To investigate whether A20 played a role in the innate immune response of keratinocytes, we overexpressed A20 and then examined poly(I:C)-induced cytokine expression. We noted that A20 significantly inhibited poly(I:C)-induced cytokine production, and this effect was related to the inhibition of NF-κB signaling. These results suggest that the downregulation of A20 increased the susceptibility of keratinocytes to external stimuli, thus contributing to the development of psoriasis.

Epigenetic Modulation of Gene Expression during Keratinocyte Differentiation.

BACKGROUND: Epigenetic modulation of gene expression occurs by various methods, including DNA methylation and histone modification. DNA methylation of specific genes may affect the chromatin structure, preventing access by the transcriptional machinery. Although gene expression is dramatically changed during keratinocyte differentiation, there is no evidence of epigenetic modulation during the process of epidermal stratification. OBJECTIVE: We investigated whether epigenetic modulation is involved in keratinocyte differentiation-specific gene regulation. METHODS: We used trypsin to produce epidermal fragmentation (named T1-T4) and performed a morphological analysis using hematoxylin-eosin stain and cytokeratin expression based on reverse transcription polymerase chain reaction. We then constructed a DNA methylation microarray. RESULTS: Each epidermal fragment showed morphological features of the epithelial layer. T1 represented the basal layer, T2 was the spinous layer, T3 was the granular layer, and T4 was the cornified layer. The level of the K14 proliferation marker was increased in the T1 fraction, and the level of K10 differentiation marker was increased in the T2-T4 fractions. Using a methylation microarray with the T1 and T4 fractions, we obtained many hypermethylated and hypomethylated genes from differentiated keratinocytes. CONCLUSION: The importance of epigenetic modulation in target gene expression during keratinocyte differentiation is identified.

Identification of Cutaneous Mycobacterium massiliense Infections Associated with Repeated Surgical Procedures.

Mycobacterium massiliense, an emerging pathogen that is increasingly reported as a causative agent in infections occurring during medical procedures, is difficult to be identified using conventional methods. Here we report the case of a cutaneous M. massiliense infection that was associated with repeated surgical procedures and that was identified via a comparative sequence analysis of rpoB and hsp65. The patient showed a substantial response to treatment with a combination of antimicrobial therapies consisting of clarithromycin, amikacin, and cefoxitin for 6 months.

Expression of N-terminal truncated desmoglein 3 (deltaNDg3) in epidermis and its role in keratinocyte differentiation.

During a search for keratinocyte differentiation-related genes, we obtained a cDNA fragment from the 5'-untranslated region of a previously identified splicing variant of desmoglein 3 (Dg3). This transcript encodes a protein of 282 amino acids, which corresponds to the N-terminal truncated intracellular domain of Dg3 (deltaNDg3). Northern blot analysis detected a 4.6-kb transcript matching the predicted size of deltaNDg3 mRNA, and Western blot analysis with an antibody raised against the Dg3 C-terminus (H-145) detected a 31-kDa protein. Increased deltaNDg3 expression was observed in differentiating keratinocytes by RT-PCR and Western blot analysis, suggesting that deltaNDg3 is indeed a differentiation-related gene product. In immunohistochemical studies of normal and pathologic tissues, H-145 antibody detected the protein in the cytoplasm of suprabasal layer cells, whereas an antibody directed against the N-terminal region of Dg3 (AF1720) reacted with a membrane protein in the basal layer. In addition, deltaNDg3 transcript and protein were upregulated in psoriatic epidermis, and protein expression appeared to increase in epidermal tumors including Bowen's disease and squamous cell carcinoma. Moreover, overexpression of deltaNDg3 led to increased migration and weakening of cell adhesion. These results suggest that deltaNDg3 have a role in keratinocyte differentiation, and that may be related with tumorigenesis of epithelial origin.

A case of isolated plexiform neurofibroma in a patient with myasthenia gravis.

We report a case of an isolated plexiform neurofibroma occurring in a patient with myasthenia gravis. A 48-year-old man presented with asymptomatic skin-colored nodules on the tip of his 4th finger. Microscopically, a plexiform neurofibroma was identified located in the dermis that appeared to originate from small superficial nerves. He had a 20-year history of treated myasthenia gravis; otherwise, his personal and family histories were unremarkable. Given that myasthenia gravis is a disorder of the peripheral nerves, plexiform neurofibromas could be associated with myasthenia gravis. However, the development of an isolated plexiform neurofibroma in a case of myasthenia gravis has not yet been reported. The occurrence of a neurofibromas in a patient with myasthenia gravis suggests a link in the pathogenesis of these two diseases.

Sphingosylphosphorylcholine-induced interleukin-6 production is mediated by protein kinase C and p42/44 extracellular signal-regulated kinase in human dermal fibroblasts.

BACKGROUND: Sphingosylphosphorylcholine (SPC) has been reported as a novel lipid mediator that exerts various actions on wound healing process. OBJECTIVE: The aim of this study is to evaluate the involvement of interleukin-6 (IL-6) in SPC-induced wound healing acceleration. METHODS: We performed immunohistochemical analysis to demonstrate the IL-6 induction by SPC. To analyze the signaling events, skin fibroblasts were treated with SPC, and then RT-PCR, ELISA and Western blot analyses were carried out. RESULTS: SPC markedly induced interleukin-6 (IL-6) expression in rabbit ear wound. SPC also induced IL-6 expression at both the mRNA and protein levels in human dermal fibroblasts cultured in vitro. SPC rapidly phosphorylated p42/44 extracellular signal-regulated kinase (ERK). Pretreatment with PD 98059, a specific MAPK kinase 1/2 inhibitor, markedly suppressed SPC-induced IL-6 expression in a dose-dependent manner. Protein kinase C (PKC) activation by phorbol myristate acetate (PMA) potentiated IL-6 mRNA expression, whereas PKC inhibition by bisindolylmaleimide blocked SPC-induced p42/44 ERK phosphorylation and IL-6 expression. Over-expression of PKCalpha markedly induced the IL-6 expression and p42/44 ERK activation. CONCLUSION: These results suggest that SPC-induced IL-6 production is mediated by PKC-dependent p42/44 ERK activation in human dermal fibroblasts cultured in vitro.