Activation of vascular endothelial growth factor receptor 2 in a cellular model of loricrin keratoderma

Dermoscopic furrow ink test of the palmar lesion in loricrin keratoderma

Palmoplantar keratodermas (PPK) comprise a heterogeneous group of keratinization disorders that gradually progress during childhood, resulting in difficulties to establish a diagnosis and to identify a candidate gene for sequencing. Dermoscopic examination with staining of palmoplantar skin using a whiteboard marker, so-called "furrow ink test", could be a useful tool for differentiation between furrow and ridge in understanding the morphological characteristics of PPK. One of the striking features in autosomal dominant loricrin keratoderma (LK) is diffuse PPK with honeycomb pattern. In this study, we performed dermoscopic furrow ink test in a Japanese family of LK with the most frequent mutation c.684dup, p.Ser229Valfs*107 in the loricrin gene. The severe lesion revealed that irregular circular hyperkeratoses were aggregated and normal structures of furrows and ridges were disrupted. To accurately describe the nature of this dermoscopic patterned skin surface, we suggest that the condition could be termed as "irregular cobblestone appearance" rather than "honeycomb pattern". Regular cobblestone appearance to maintain parallel furrow structure was observed in early or mild hyperkeratotic lesions. Eccrine sweat glands that open on the surface of ridges nearly disappeared, resulting in hypohidrosis.

Phosphorus-32 interstitial radiotherapy for recurrent craniopharyngioma: Expressions of vascular endothelial growth factor and its receptor-2 and imaging features of tumors are associated with tumor radiosensitivity

To investigate the relationship of the expression of vascular endothelial growth factor (VEGF)/vascular endothelial growth factor receptor-2 (VEGFR-2) and imaging features with the therapeutic efficacy of Phosphorus-32 colloid interstitial radiotherapy in recurrent craniopharyngioma.Thirty-two patients with recurrent craniopharyngioma underwent phosphorus-32 colloid interstitial radiotherapy. The tumor imaging features were classified into 4 types according to the thickness of the cyst wall and signals of the cyst contents as shown by computed tomography (CT) and magnetic resonance imaging (MRI) images. Protein expressions of VEGF and VEGFR-2 in craniopharyngioma tissues were evaluated with immunohistochemistry before radiotherapy. The tumor radiosensitivity was determined at 12 months after the interstitial radiotherapy.VEGF mainly expressed in the tumor cytoplasm, and VEGFR-2 expressed either in vascular endothelial cells or in tumor endothelial cells. VEGF/VEGFR-2 expressions varied significantly in cases sensitive or insensitive to the radiotherapy (VEGF: P = .028; VEGFR-2: P = .017). Tumor imaging features were associated with the therapeutic efficacy of interstitial radiotherapy (P = .000). VEGF expression had no association with the imaging features of tumors (P = .226), but VEGFR-2 expression was associated with the imaging features of tumors (P = .008).Our results confirmed the association among imaging features, VEGFR-2 expressions, and tumor radiosensitivity in craniopharyngiomas. Imaging features and VEGFR-2 expressions may add useful data to the radiosensitive assessment of craniopharyngiomas.

Netrin-1 acts as a non-canonical angiogenic factor produced by human Wharton's jelly mesenchymal stem cells (WJ-MSC)

BACKGROUND

Angiogenesis, the process in which new blood vessels are formed from preexisting ones, is highly dependent on the presence of classical angiogenic factors. Recent evidence suggests that axonal guidance proteins and their receptors can also act as angiogenic regulators. Netrin, a family of laminin-like proteins, specifically Netrin-1 and 4, act via DCC/Neogenin-1 and UNC5 class of receptors to promote or inhibit angiogenesis, depending on the physiological context.

METHODS

Mesenchymal stem cells secrete a broad set of classical angiogenic factors. However, little is known about the expression of non-canonical angiogenic factors such as Netrin-1. The aim was to characterize the possible secretion of Netrin ligands by Wharton's jelly-derived mesenchymal stem cells (WJ-MSC). We evaluated if Netrin-1 presence in the conditioned media from these cells was capable of inducing angiogenesis both in vitro and in vivo, using human umbilical vein endothelial cells (HUVEC) and chicken chorioallantoic membrane (CAM), respectively. In addition, we investigated if the RhoA/ROCK pathway is responsible for the integration of Netrin signaling to control vessel formation.

RESULTS

The paracrine angiogenic effect of the WJ-MSC-conditioned media is mediated at least in part by Netrin-1 given that pharmacological blockage of Netrin-1 in WJ-MSC resulted in diminished angiogenesis on HUVEC. When HUVEC were stimulated with exogenous Netrin-1 assayed at physiological concentrations (10-200 ng/mL), endothelial vascular migration occurred in a concentration-dependent manner. In line with our determination of Netrin-1 present in WJ-MSC-conditioned media we were able to obtain endothelial tubule formation even in the pg/mL range. Through CAM assays we validated that WJ-MSC-secreted Netrin-1 promotes an increased angiogenesis in vivo. Netrin-1, secreted by WJ-MSC, might mediate its angiogenic effect through specific cell surface receptors on the endothelium, such as UNC5b and/or integrin α6β1, expressed in HUVEC. However, the angiogenic response of Netrin-1 seems not to be mediated through the RhoA/ROCK pathway.

CONCLUSIONS

Thus, here we show that stromal production of Netrin-1 is a critical component of the vascular regulatory machinery. This signaling event may have deep implications in the modulation of several processes related to a number of diseases where angiogenesis plays a key role in vascular homeostasis.

Suppressing AP1 factor signaling in the suprabasal epidermis produces a keratoderma phenotype

Keratodermas comprise a heterogeneous group of highly debilitating and painful disorders characterized by thickening of the skin with marked hyperkeratosis. Some of these diseases are caused by genetic mutation, whereas other forms are acquired in response to environmental factors. Our understanding of signaling changes that underlie these diseases is limited. In the present study, we describe a keratoderma phenotype in mice in response to suprabasal epidermis-specific inhibition of activator protein 1 transcription factor signaling. These mice develop a severe phenotype characterized by hyperplasia, hyperkeratosis, parakeratosis, and impaired epidermal barrier function. The skin is scaled, constricting bands encircle the tail and digits, the footpads are thickened and scaled, and loricrin staining is markedly reduced in the cornified layers and increased in the nucleus. Features of this phenotype, including nuclear loricrin localization and pseudoainhum (autoamputation), are characteristic of the Vohwinkel syndrome. We confirm that the phenotype develops in a loricrin-null genetic background, indicating that suppressed suprabasal AP1 factor function is sufficient to drive this disease. We also show that the phenotype regresses when suprabasal AP1 factor signaling is restored. Our findings suggest that suppression of AP1 factor signaling in the suprabasal epidermis is a key event in the pathogenesis of keratoderma.

Reduced expression of epidermal growth factor receptor, E-cadherin, and occludin in the skin of flaky tail mice is due to filaggrin and loricrin deficiencies

Disruption of skin barrier function leads to increases in the percutaneous transfer of allergens and the incidence of atopic dermatitis. Flaky tail (Flg(ft)) mice have been used as a model of atopic dermatitis with skin barrier dysfunction. Although Flg(ft) mice are known to have filaggrin mutation, the mechanism responsible for the skin barrier dysfunction that they display needs to be determined, especially for the roles of epidermal adhesion and junction proteins. Herein, we report the decreased expression of epidermal growth factor receptor (EGFR), E-cadherin, occludin, and SIRT1 in the skin of Flg(ft) mice, compared with those in C57BL/6J mice. Administration of N-acetyl-L-cysteine, an antioxidant, in the drinking water improved these protein expressions in the skin of Flg(ft) mice. Notably, we discovered that loricrin expression was suppressed in Flg(ft) mice. In vitro experiments showed that filaggrin small interfering RNA, loricrin small interfering RNA, or SIRT1 inhibitor sirtinol suppressed the expression levels of EGFR, E-cadherin, and occludin in a human immortalized keratinocyte cell line (HaCaT cells). Our findings suggest that the observed reductions in EGFR, E-cadherin, and occludin expression were due to filaggrin deficiency accompanied with subsequent loricrin deficiency and disruption of the SIRT1 pathway in the skin of Flg(ft) mice.

Low-temperature atmospheric plasma increases the expression of anti-aging genes of skin cells without causing cellular damages

Efforts to employ various types of plasma in the field of skin care have increased consistently because it can regulate many biochemical reactions that are normally unaffected by light-based therapy. One method for skin rejuvenation adopted a high-temperature plasma generator to remove skin epithelial cells. In this case, the catalyzing effects of the plasma were rarely used due to the high temperature. Hence, the benefits of the plasma were not magnified. Recently, many types of low-temperature plasma devices have been developed for medical applications but their detailed functions and working mechanisms are unclear. The present study examined the effect of low-temperature microwave plasma on skin cells. Treatment with low-temperature plasma increased the expression of anti-aging genes in skin cells, including collagen, fibronectin and vascular endothelial growth factor. Furthermore, the plasma treatment did not cause cell death, but only induced slight cell growth arrest at the G2 phase. Although the cells treated with low-temperature plasma showed moderate growth arrest, there were no signs of thermal or genetic damage of skin cells. Overall, this low-temperature microwave plasma device induces the expressions of some anti-aging-related genes in skin cells without causing damage.

Interaction of the profilaggrin N-terminal domain with loricrin in human cultured keratinocytes and epidermis

The relationship between the two coexpressed differentiation markers, profilaggrin and loricrin, is not clear right now. In this study, we explored the interaction of profilaggrin N-terminal domain (PND) with loricrin in keratinocytes and epidermis. Confocal immunofluorescence microscopic analysis of human epidermis showed that PND colocalized with loricrin. Loricrin nucleofected into HaCaT cells colocalized with PND in the nucleus and cytoplasm. The PND localizes to both the nucleus and cytoplasm of epidermal granular layer cells. Nucleofected PND also colocalized with keratin 10 (K10) in the nucleus and cytoplasm. Immunoelectron microscopic analysis of human epidermis confirmed the findings in nucleofected keratinocytes. Yeast two-hybrid assays showed that the B domain of human and mouse PND interacted with loricrin. The glutathione S-transferase (GST) pull-down analysis using recombinant GST-PND revealed that PND interacted with loricrin and K10. Knockdown of PND in an organotypic skin culture model caused loss of filaggrin expression and a reduction in both the size and number of keratohyalin granules, as well as markedly reduced expression of loricrin. Considering that expression of PND is closely linked to keratinocyte terminal differentiation, we conclude that PND interacts with loricrin and K10 in vivo and that these interactions are likely to be relevant for cornified envelope assembly and subsequent epidermal barrier formation.

Lipid peroxidation-induced VEGF expression in the skin of KKAy obese mice

Obesity is known to be associated with a number of effects on skin physiology. KKA(y) obese mouse is a model of type 2 diabetes characterized by systemic oxidative stress because of severe obesity, hypertriglyceridaemia, hyperglycaemia and hyperinsulinaemia. We investigated lipid peroxidation and vascular endothelial growth factor (VEGF) expression in the skin of KKA(y) obese mice. We also investigated the effect of lipid peroxidation derivatives on VEGF production and proliferation in human epidermal keratinocyte cell line (HaCaT). The lipid peroxidation level in the mouse skin tissue was determined by measuring the levels of thiobarbituric acid-reactive substances. The levels of VEGF expression, p44/p42 mitogen-activated protein kinase (MAPK) activation and CD36 expression were analysed by Western blot. Their localization was examined by immunofluorescence. For the in vitro experiments, an enzyme-linked immunosorbent assay was utilized to measure VEGF secretion in the medium. In vitro experiments demonstrated that lipid peroxidation derivatives increased VEGF production in HaCaT cells, which was blocked by a p44/p42 MAPK inhibitor and anti-CD36 antibody. We observed increased levels of lipid peroxidation derivatives, p44/p42 MAPK activation and VEGF expression in the skin of KKA(y) obese mice. Notably, pitavastatin, an inhibitor of competitive 3-hydroxy-3-methylglutaryl coenzyme A reductase, suppressed all of these processes. Our results suggest that lipid peroxidation induces VEGF expression via CD36 and p44/p42 MAPK pathway in the skin of obese mice.