involucrin and Inflammation

Topics: Animals; Epidermis; Humans; Inflammation; Keratinocytes; Mice; Receptors, Calcitriol; Skin; Vitamin D

The prevalence of atopic dermatitis (AD), a disease characterized by severe pruritus, immune imbalance, and skin barrier dysfunction, is rapidly increasing worldwide. Deacetylasperulosidic acid (DAA) has anti-atopic activity in the three main cell types associated with AD: keratinocytes, mast cells, and eosinophils. Our study investigated the anti-atopic activity of DAA in 2,4-dinitrochlorobenzene-induced NC/Nga mice. DAA alleviated the symptoms of AD, including infiltration of inflammatory cells (mast cells and eosinophils), epidermal thickness, ear thickness, and scratching behavior. Furthermore, DAA reduced serum IgE, histamine, and IgG1/IgG2a ratio and modulated the levels of AD-related cytokines and chemokines, namely interleukin (IL)-1β, IL-4, IL-6, IL-9, IL-10, IL-12, tumor necrosis factor-α, interferon-γ, thymic stromal lymphopoietin, thymus and activation-regulated chemokine, macrophage-derived chemokine, and regulated on activation the normal T cell expressed and secreted in the serum. DAA restored immune balance by regulating gene expression and secretion of Th1-, Th2-, Th9-, Th17-, and Th22-mediated inflammatory factors in the dorsal skin and splenocytes and restored skin barrier function by increasing the expression of the pro-filaggrin gene and barrier-related proteins filaggrin, involucrin, and loricrin. These results suggest DAA as a potential therapeutic agent that can alleviate the symptoms of AD by reducing pruritus, modulating immune imbalance, and restoring skin barrier function.

Topics: Animals; Anti-Inflammatory Agents; Chemokines; Dermatitis, Atopic; Dinitrochlorobenzene; Filaggrin Proteins; Immunity; Inflammation; Keratinocytes; Male; Mast Cells; Membrane Proteins; Mice; Plant Extracts; Protein Precursors; Pruritus; Skin; T-Lymphocytes

Psoriasis is an inflammatory skin disorder characterized by the hyperproliferation of basal epidermal cells. It is regarded as T-cell mediated, but the role of keratinocytes (KCs) in the disease pathogenesis has reemerged, with genetic studies identifying KC-associated genes. We applied flow cytometry on KCs from lesional and nonlesional epidermis to characterize the phenotype in the germinative compartment in psoriasis, and we observed an overall increase in the stemness markers CD29 (2.4-fold), CD44 (2.9-fold), CD49f (2.8-fold), and p63 (1.4-fold). We found a reduced percentage of cells positive for the early differentiation marker cytokeratin 10 and a greater fraction of CD29

Topics: Biomarkers; Cell Differentiation; Cells, Cultured; Flow Cytometry; Humans; Inflammation; Integrin beta1; Interleukin-17; Interleukin-22; Interleukins; Keratinocytes; Protein Precursors; Psoriasis; Regeneration; Skin; Stem Cells

The mouse cholesterol sulfotransferase St2b2 contributes to epidermal differentiation by biosynthesizing cholesterol sulfate (CS) from cholesterol in the epidermis. 12-O-Tetradecanoylphorbol-13-acetate (TPA) causes epidermal hyperplasia, an abnormal increase in epidermal cell numbers resulting from aberrant cell differentiation and an increase in St2b2 protein levels. The mechanisms underlying enhanced St2b2 expression and the pathophysiologic significance of the increased expression are unclear, however. To verify whether increased St2b2 levels are necessary for TPA-induced epidermal hyperplasia, the effects of St2b2-specific small hairpin RNA (St2b2-shRNA) on hyperplasia were examined in mice. St2b2-shRNA clearly suppressed TPA-induced epidermal hyperplasia and the expression of a marker of epidermal differentiation, involucrin (INV). Interestingly, treating mouse epidermal cells with tumor necrosis factor-alpha (TNFα) increased St2b2 expression. Furthermore, treatment with TNFα-siRNA or anti-TNF receptor antibodies reduced the TPA-induced enhancement of St2b2 expression. Treatment with BAY 11-7082, a specific inhibitor of nuclear factor-kappa B (NF-κB), diminished TPA-induced St2b2 expression. These results suggested that enhancement of St2b2 expression by TPA treatment occurs mainly through the TNFα-NF-κB inflammatory signaling pathway, which in turn leads to increased CS concentrations in epidermal cells and hyperplasia.

Topics: Animals; Antibodies; Cholesterol Esters; Epidermis; Female; Hyperplasia; Inflammation; Mice; Mice, Inbred Strains; NF-kappa B; Nitriles; Protein Precursors; Receptors, Tumor Necrosis Factor; RNA, Small Interfering; Signal Transduction; Skin Neoplasms; Sulfones; Sulfotransferases; Tetradecanoylphorbol Acetate; Tumor Necrosis Factor-alpha

alpha2beta1 integrins are normally confined to the proliferating basal layers of the epidermis. However, during wound healing and in psoriasis, these integrins are expressed on keratinocytes in suprabasal layers correlating with a less differentiated phenotype. Transgenic mice expressing alpha2beta1 integrins under the involucrine promoter have previously been demonstrated, to various degrees, spontaneously develop a skin disorder resembling psoriasis. Herein, we show that a mild epidermal wounding induces a uniform acanthosis together with an influx of immune cells. The disease initiates as a normal wound healing process and is completely restored in wildtype mice by day 14. However, in the integrin transgenic mice a chronic inflammation develops, a process that can be compared to the Koebner phenomenon in psoriatic patients. In this study, we have followed the integrin transgenic mice for five weeks, where substantial keratinocyte hyper-proliferation, inflammatory infiltration and high cytokine levels within the skin can still be observed. In addition, draining lymph nodes were dramatically increased in size and contained highly activated T cells, as well as APCs secreting large amounts of pro-inflammatory cytokines. Furthermore, the systemic immune response was affected with increased spleen size, elevated cytokine levels in the serum and altered lymphocyte trafficking patterns, very much resembling what is seen in psoriasis patients. Finally, CD4(+) T cell depletion was not able to affect the onset or progression of skin inflammation. This suggests that altered keratinocyte differentiation and proliferation can drive a skin inflammation and cause chronic immune cell activation both at a local and systemic level.

Topics: Animals; Cell Differentiation; Cell Movement; Cell Proliferation; Cytokines; Humans; Inflammation; Integrin alpha2beta1; Keratinocytes; Lymphocyte Activation; Mice; Mice, Inbred C57BL; Mice, Transgenic; Protein Precursors; Psoriasis; Skin; T-Lymphocytes; Wound Healing

The transcription factor Ets1 is normally expressed in the proliferative layer of stratified epithelium, but expression of Ets1 is significantly upregulated in squamous cell carcinomas. How elevated levels of Ets1 impact tumor initiation and progression is not well understood. To determine the biological consequences of overexpression of Ets1, we developed a transgenic mouse model that allows induction of Ets1 expression in keratinocytes of stratified epithelium in a regulatable fashion. Induction of Ets1 during embryonic development results in a dramatic alteration in epidermal structure and function by suppressing the expression of multiple stratum corneum constituents, while at the same time inducing expression of EGF ligands, AP1 transcription factors and matrix metalloproteases. Interestingly, expression of certain immune-related genes, including defensins, chemokines and cytokines was increased as well, suggesting a possible role for immune dysregulation in the promotion of squamous dysplasia. Experiments using cultured mouse keratinocytes indicate that Ets1 can induce expression of some of these mediators in a cell-intrinsic fashion. Collectively, our data reveal that elevated expression of Ets1 has a much broader array of pro-tumorigenic effects on epithelial cells than previously appreciated.

Topics: Animals; Blotting, Western; Cell Differentiation; Cell Proliferation; Cells, Cultured; Chemokines; Epidermal Cells; Epidermis; Filaggrin Proteins; Fluorescent Antibody Technique, Indirect; Hair Follicle; Immunity, Innate; Inflammation; Intermediate Filament Proteins; Keratin-10; Keratin-14; Keratin-5; Keratin-6; Keratinocytes; Membrane Proteins; Mice; Mice, Transgenic; Oligonucleotide Array Sequence Analysis; Protein Precursors; Proto-Oncogene Protein c-ets-1; Reverse Transcriptase Polymerase Chain Reaction

Inflammatory skin disorders result in significant epidermal changes, including keratinocyte hyperproliferation, incomplete differentiation, and impaired barrier. Here we test whether, conversely, an impaired epidermal barrier can promote an inflammatory response. Mice lacking the transcription factor Kruppel-like factor 4 (Klf4) have a severe defect in epidermal barrier acquisition. Transcription profiling of Klf4(-/-) newborn skin revealed similar changes in gene expression to involved psoriatic plaques, including a significant upregulation of the gap junction protein connexin 26 (Cx26). Ectopic expression of Cx26 from the epidermis-specific involucrin (INV) promoter (INV-Cx26) demonstrated that downregulation of Cx26 is required for barrier acquisition during development. In juvenile and adult mice, persistent Cx26 expression kept wounded epidermis in a hyperproliferative state, blocked the transition to remodeling, and led to an infiltration of immune cells. Mechanistically, ectopic expression of Cx26 in keratinocytes resulted in increased ATP release, which delayed epidermal barrier recovery and promoted an inflammatory response in resident immune cells. These results provide a molecular link between barrier acquisition in utero and epidermal remodeling after wounding. More generally, these studies suggest that the most effective treatments for inflammatory skin disorders might concomitantly suppress the immune response and enhance epidermal differentiation to restore the barrier.

Topics: Animals; Animals, Newborn; Connexin 26; Connexins; Epidermis; Gene Expression Regulation, Developmental; Inflammation; Kruppel-Like Factor 4; Kruppel-Like Transcription Factors; Mice; Mice, Transgenic; Promoter Regions, Genetic; Protein Precursors; Skin Diseases; Wound Healing