Regulation of vascular endothelial growth factor expression in human keratinocytes by retinoids

Clinical pharmacokinetics and pharmacodynamics of oral systemic nonbiologic therapies for psoriasis patients

INTRODUCTION

Psoriasis is a chronic inflammatory immune condition. Treatments for psoriasis vary with disease severity, ranging from topicals to systemic biologic agents. The pharmacokinetic (PK) and pharmacodynamic (PD) properties of these therapies establish drug efficacy, toxicity, and optimal dosing to ensure therapeutic drug levels are sustained and adverse effects are minimized.

AREAS COVERED

A literature search was performed on PubMed, Google Scholar, and Ovid MEDLINE for PK and PD, efficacy, and safety data regarding oral systemic nonbiologic therapies utilized for moderate-to-severe plaque psoriasis. The findings were organized into sections for each drug: oral acitretin, methotrexate, cyclosporine, apremilast, tofacitinib, and deucravacitinib.

EXPERT OPINION

Some psoriasis patients may not respond to initial therapy. Ongoing research is evaluating genetic polymorphisms that may predict an improved response to specific medications. However, financial and insurance barriers, as well as limited genetic polymorphisms correlated with treatment response, may restrict the implementation of genetic testing necessary to personalize treatments. How well psoriasis patients adhere to treatment may contribute greatly to variation in response. Therapeutic drug monitoring may help patients adhere to treatment, improve clinical response, and sustain disease control.

IL-36γ Is a Strong Inducer of IL-23 in Psoriatic Cells and Activates Angiogenesis

The IL-1 family member cytokine IL-36γ is recognised as key mediator in the immunopathology of psoriasis, hallmarks of which involve the activation of both resident and infiltrating inflammatory myeloid cells and aberrant angiogenesis. This research demonstrates a role for IL-36γ in both myeloid activation and angiogenesis. We show that IL-36γ induces the production of psoriasis-associated cytokines from macrophages (IL-23 and TNFα) and that this response is enhanced in macrophages from psoriasis patients. This effect is specific for IL-36γ and could not be mimicked by other IL-1 family cytokines such as IL-1α. IL-36γ was also demonstrated to induce endothelial tube formation and branching, in a VEGF-A-dependent manner. Furthermore, IL-36γ-stimulated macrophages potently activated endothelial cells and led to increased adherence of monocytes, effects that were markedly more pronounced for psoriatic macrophages. Interestingly, regardless of stimulus, psoriasis monocytes showed increased adherence to both the stimulated and unstimulated endothelium when compared with monocytes from healthy individuals. Collectively, these findings show that IL-36γ has the potential to enhance endothelium directed leucocyte infiltration into the skin and strengthen the IL-23/IL-17 pathway adding to the growing evidence of pathogenetic roles for IL-36γ in psoriatic responses. Our findings also point to a cellular response, which could potentially explain cardiovascular comorbidities in psoriasis in the form of endothelial activation and increased monocyte adherence.

Pivotal role of Acitretin nanovesicular gel for effective treatment of psoriasis: ex vivo-in vivo evaluation study

The goal of the current study was to explore the potential benefits of Acitretin (Act) nanovesicular gel as a prospective antipsoriatic topical delivery system counteracting the drug challenges in terms of its extremely low aqueous solubility, instability, skin irritation, and serious systemic adverse effects. Act-loaded niosomes were successfully developed, entirely characterized, and optimized. Further evaluation of the optimized formula was conducted regarding its stability and ex vivo cytotoxicity on different cell lines. The optimized niosomal vesicles were then incorporated in gel base matrix and investigated by sequential ex vivo (skin permeation and deposition) and in vivo (skin irritation and antipsoriatic activity using mouse tail model) experiments. The optimized Act-loaded niosomes (span 60:cholesterol molar ratio 1:1) were spherical in shape and exhibited the highest entrapment efficiency (90.32±3.80%) with appropriate nanosize and zeta potential of 369.73±45.45 nm and -36.33±1.80 mV, respectively. Encapsulation of the drug in the nanovesicles was further emphasized by differential scanning calorimetric and powder X-ray diffraction studies. After 3 months storage at 4±1°C, the optimized formula preserved its stability. Act nano niosomal gel produced a remarkable enhanced ex vivo permeation profile up to 30 h and significant drug deposition in the viable epidermal-dermal layers compared with those of Act gel. The pronounced antipsoriatic activity of the medicated nano niosomes was proved ex vivo in HaCaT cells (a keratinocyte cell line). Topical application of Act nano niosomal gel to mouse tail model further established its distinct in vivo antipsoriatic superiority in terms of significantly higher orthokeratosis, drug activity, and reduction in epidermal thickness compared with the control and other gel formulations. Also, negligible skin irritation and better skin tolerability of Act nanovesicular gel were revealed by primary irritation index and histopathologic examination.

Excessive angiogenesis associated with psoriasis as a cause for cardiovascular ischaemia

Psoriasis, a common disease affecting 2%-3% of the UK population, produces significant impairment of quality of life and is an immense burden on sufferers and their families. Psoriasis is associated with significant cardiovascular comorbidity and the metabolic syndrome. Angiogenesis, a relatively under-researched component of psoriasis, is a key factor in pathogenesis of psoriasis and also contributes to the development of atherosclerosis. Vascular endothelial growth factor (VEGF) is a well-established mediator of pathological angiogenesis which is upregulated in psoriasis. It is possible that, in patients with psoriasis, cutaneous angiogenesis may be both a marker for systemic vascular pathology and a novel therapeutic target. In this viewpoint study, the role of VEGF-mediated angiogenesis as a cause for cardiovascular events in patients with psoriasis is explored.

Lymphangioma Circumscriptum: Good Clinical Response to Isotretinoin Therapy

Lymphangioma circumscriptum (LC) is a superficial form of lymphatic malformation that can be difficult to treat. Therapeutic approaches to LC such as laser therapy, sclerotherapy, and surgical excision give varying results. This is the first description of a case of LC successfully treated with oral isotretinoin. Further studies are needed to confirm whether this is a reproducible treatment option.

RARα mediates all-trans-retinoic acid-induced VEGF-C, VEGF-D, and VEGFR3 expression in lung cancer cells

The regulation of vascular endothelial growth factors C (VEGF-C) and D (VEGF-D), and their receptor VEGFR3 gene and protein expression by all-trans-retinoic acid (atRA) in A549 lung cancer cells, was investigated. We showed that atRA treatment increased VEGF-C, VEGF-D, and VEGFR3 protein and mRNA contents in dose-dependent manner. atRA-mediated increase of both ligands and receptor expression correlated with the elevated level of retinoic acid receptor α (RARα) expression, while the level of another atRA receptor, peroxisome proliferator-activated receptor β/δ (PPARβ/δ), was decreased. We demonstrated that the classical counterpart of RARα, retinoid X receptor α (RXRα), was down-regulated in both cytoplasm and nucleus of A549 cells upon atRA addition. On the contrary, the nuclear quantity of another possible RARα counterpart, transcription factor Sp1, was increased after atRA treatment.

VEGF-A inhibition ameliorates podocyte apoptosis via repression of activating protein 1 in diabetes

BACKGROUND/AIMS

Vascular endothelial growth factor-A (VEGF-A) upregulation and podocyte apoptosis have been documented in diabetes. This study was designed to investigate whether inhibiting VEGF-A could ameliorate podocyte apoptosis in diabetes and the underlying mechanisms.

METHODS

In vitro, small interfering RNAs (siRNAs) of VEGF-A and activator protein 1 (AP-1, c-fos and c-jun), bevacizumab (VEGF-A inhibitor) and SP600125 (AP-1 inhibitor) were added to high glucose (30 mM) induced podocytes. Luciferase reporter assay was used to investigate whether AP-1 was a direct target of VEGF-A. In vivo, bevacizumab and SP600125 were administered to 12-week-old streptozotocin-induced male Sprague Dawley rats. The level of VEGF-A, c-fos, c-jun and bcl-2 were examined using immunostaining and Western blot analysis. Podocyte apoptosis was detected using the terminal deoxynucleotidyl transferase-mediated uridine 5'-triphosphate-biotin nick end labeling (TUNEL) assay, electron microscopy and flow cytometry.

RESULTS

Silencing VEGF-A or AP-1 upregulated bcl-2 and ameliorated podocyte apoptosis. Silencing VEGF-A decreased the level of c-fos and c-jun and bevacizumab and SP600125 treatment attenuated podocyte apoptosis. Luciferase reporter activity of VEGF-A-3'-UTR constructs was significantly provoked when stimulated with TGF-β1. In diabetic rat kidneys, VEGF-A co-localized with bcl-2 in podocytes. With bevacizumab and SP600125 treatment, the level of VEGF-A and AP-1 decreased while bcl-2 increased. Podocyte apoptotic rate was reduced with condensed podocyte nuclei less frequently observed. The urine albumin excretion rate (UAER) and albumin/creatinine were improved.

CONCLUSION

This study demonstrates VEGF-A inhibition ameliorates podocyte apoptosis by regulating AP-1 and bcl-2 signaling. AP-1 is a direct target of VEGF-A and a novel player in podocyte apoptosis.

Keratinocytic vascular endothelial growth factor as a novel biomarker for pathological skin condition

Skin is an emerging target tissue in pharmaceutical and cosmetic science. Safety assessment for dermal toxicity is a critical step for development of topically applicable pharmaceutical agents and ingredients in cosmetics. Urgent needs exist to set up toxicity testing methods for dermal safety, and identification of novel biomarkers for pathological cutaneous alteration is highly required. Here we will discuss if vascular endothelial growth factor (VEGF) has a potential as a biomarker for dermal impairment. Experimental and clinical evidences for induction of keratinocytic VEGF under pathological conditions will be reviewed.

Primary culture of avian embryonic heart forming region cells to study the regulation of vertebrate early heart morphogenesis by vitamin A

Background

Important knowledge about the role of vitamin A in vertebrate heart development has been obtained using the vitamin A-deficient avian in ovo model which enables the in vivo examination of very early stages of vertebrate heart morphogenesis. These studies have revealed the critical role of the vitamin A-active form, retinoic acid (RA) in the regulation of several developmental genes, including the important growth regulatory factor, transforming growth factor-beta2 (TGFβ2), involved in early events of heart morphogenesis. However, this in ovo model is not readily available for elucidating details of molecular mechanisms determining RA activity, thus limiting further examination of RA-regulated early heart morphogenesis. In order to obtain insights into RA-regulated gene expression during these early events, a reliable in vitro model is needed. Here we describe a cell culture that closely reproduces the in ovo observed regulatory effects of RA on TGFβ2 and on several developmental genes linked to TGFβ signaling during heart morphogenesis.

Results

We have developed an avian heart forming region (HFR) cell based in vitro model that displays the characteristics associated with vertebrate early heart morphogenesis, i.e. the expression of Nkx2.5 and GATA4, the cardiogenesis genes, of vascular endothelial growth factor (VEGF-A), the vasculogenesis gene and of fibronectin (FN1), an essential component in building the heart, and the expression of the multifunctional genes TGFβ2 and neogenin (NEO). Importantly, we established that the HFR cell culture is a valid model to study RA-regulated molecular events during heart morphogenesis and that the expression of TGFβ2 as well as the expression of several TGFβ2-linked developmental genes is regulated by RA.

Conclusions

Our findings reported here offer a biologically relevant experimental in vitro system for the elucidation of RA-regulated expression of TGFβ2 and other genes involved in vertebrate early cardiovascular morphogenesis.

Picea mariana polyphenolic extract inhibits phlogogenic mediators produced by TNF-α-activated psoriatic keratinocytes: Impact on NF-κB pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Picea mariana ((Miller) Britton, Sterns, and Poggenburg; Pinaceae) bark has been traditionally used by North American natives for treating topical inflammations. It has been also suggested to improve various inflammatory skin disorders like Psoriasis vulgaris. Extracts from this bark storage protein contain polyphenolic compounds which have well-known antiinflammatory activities. Based on the capacity of polyphenolic compounds to modulate functions of normal human keratinocytes, this study was set up to decipher the mechanisms of action of a chemically characterized polyphenolic extract from Picea mariana bark (BS-EAcf) on lesional keratinocytes of skin with psoriasis vulgaris, a disease driven by the immune system in which TNF-α plays a significant role.

MATERIALS AND METHODS

BS-EAcf corresponds to the ethyl acetate soluble fraction from the hot water extract of Picea mariana bark. BS-EAcf effects were evaluated in normal human (NHK) and psoriatic (PK) keratinocytes stimulated by TNF-α. Cell viability was assessed by lactate deshydrogenase release and propidium iodide (PI) staining. The mechanisms of action of BS-EAcf in keratinocytes were investigated by flow cytometry, ELISAs, RT-PCR and western blot analyses.

RESULTS

PK exhibited a higher response to TNF-α than NHK regarding the ICAM-1 expression and the production of NO, IL-6, IL-8, fractalkine and PGE2, whereas BS-EAcf significantly inhibited this TNF-α-induced increase at concentrations without causing keratinocyte toxicity. Additionally, this extract significantly inhibited the TNF-α-induced release of elafin and VEGF by PK and NHK. Since TNF-α activation of most of these factors is dependent on the NF-κB pathway, this latter was studied in TNF-α-activated PK. BS-EAcf inhibited the TNF-α-induced phosphorylation and degradation of total IκBα as well as phosphorylation of NF-κB p65.

CONCLUSIONS

The ethyl acetate fraction from Picea mariana bark extract showed inhibitory effects of cytokines, chemokines, adhesion molecules, nitric oxide and prostaglandins produced by keratinocytes under TNF-α activation through down-regulating the NF-κB pathway. This study demontrated that this extract could be a potential antiinflammatory agent capable of improving psoriatic skin.

Guidelines for the use of acitretin in psoriasis. Psoriasis Group of the Spanish Academy of Dermatology and Venereology

Phototherapy, classic systemic treatments (methotrexate, acitretin, and ciclosporin), and biologic agents (etanercept, infliximab, adalimumab, and ustekinumab) constitute a broad therapeutic arsenal that increases the likelihood of achieving control of severe and extensive disease in patients with psoriasis. Acitretin continues to be a very valuable tool in both monotherapy, in which it is combined with other systemic treatments (classic or biologic), and in sequential therapy. Thanks to its lack of a direct immunosuppressive effect and its ability to achieve a long-term response, acitretin has an important role in the treatment of psoriasis, although this has not always been acknowledged in relevant treatment guidelines. We present consensus guidelines for the use of acitretin in psoriasis drawn up by the Psoriasis Group of the Spanish Academy of Dermatology and Venereology. These guidelines provide a detailed account of acitretin, including pharmacological properties, indications and contraindications, adverse effects, and factors that should be taken into account to enhance the safe use of this drug. They also propose treatment strategies for use in routine clinical practice. The overall aim of these guidelines is to define the criteria for the use and management of acetretin in psoriasis.

Parent of origin influences the cardiac expression of vascular endothelial growth factor (Vegfa)

Background

Vascular endothelial growth factor A (VEGFA) is a major regulator of both physiological and pathological angiogenesis. Associations between polymorphisms in VEGFA and complex disease have been inconsistent. The parent from whom the allele was inherited may account for these inconsistencies. This study examined the parent of origin effect on the expression of murine Vegfa.

Methods

Two homozygous, inbred mouse strains A/J (AJ) and 129x1/SvJ (129) were crossed to produce reciprocal AJ129 and 129AJ offspring, respectively. RNA was extracted from cardiac tissue of 6 week old male (n = 8) and female (n = 8) parental, and male and female F1 offspring mice (AJ129 n = 8 and 129AJ n = 8). Vegfa and Hif1a expression levels were measured by qPCR and compared between the F1 offspring from the reciprocal crosses.

Results

We found significant differences in the expression of Vegfa in F1 offspring (AJ129 and 129AJ mice) of the reciprocal crosses between AJ and 129 mice. Offspring of male AJ mice had significantly higher expression of Vegfa than offspring of male 129 mice (p = 0.006). This difference in expression was not the result of preferential allele expression (allelic imbalance). Expression of Hif1a, a transcriptional regulator of Vegfa expression, was also higher in F1 offspring of an AJ father (p = 0.004).

Conclusion

Differences in Vegfa and Hif1a gene expression are likely the result of an upstream angiogenic regulator gene that is influenced by the parent of origin. These results highlight the importance of including inheritance information, such as parent of origin, when undertaking allelic association studies.

Gonadotropin-Mediated Regulation of the Murine VEGF Expression in MA-10 Leydig Cells

Presence of vascular endothelial growth factor (VEGF) is not only limited to cells directly involved in angiogenesis but has also been demonstrated in steroidogenic cells like testicular Leydig cells. Because Leydig cells are subjected to regulation by gonadotropic hormones and produce steroid hormones, we have investigated here the effects of human chorionic gonadotropin (hCG) or steroid hormones on VEGF expression in cultured mouse tumor Leydig cells (MA-10 cells) and have then analyzed the underlying molecular mechanisms. Northern blot analysis and enzyme-linked immunosorbent assays revealed increases in VEGF mRNA and protein levels, respectively, over 3-20 hours in MA-10 cells after stimulation with hCG or 8-Br-cAMP. Although MA-10 cells lack the classical progesterone receptor, progesterone was able to stimulate VEGF expression. Promoter analyses and antibody supershift experiments suggested that the proximal region is able to constitutively bind the transcription factors Sp1 and Sp3. Mutations of 2 potential Sp1 binding sites in the proximal region showed the requirement of these motifs for stimulation of VEGF by hCG and 8-Br-cAMP. The distal cytosine-rich sequence interacts with so far-unidentified faster migrating factors. Following stimulation with hCG or 8-Br-cAMP, the binding of these proteins was increased in the complexes formed in the proximal and distal regions. VEGF expression in Leydig cells is regulated by gonadotropin via a cAMP-dependent mechanism, and the transcription factors Sp1 and Sp3 appear to be involved in the activation of the promoter. Progesterone also appears to play a role in the regulation of VEGF, acting presumably via a nonconventional receptor that remains to be characterized yet.

Suppression of signal transducers and activators of transcription 1 in hepatocellular carcinoma is associated with tumor progression

Signal transducers and activators of transcription (STAT) 1 plays a pivotal role in cell-cycle and cell-fate determination, and vascular endothelial growth factor (VEGF) also contributes tumor growth. Recently, interferon (IFN) α has been reported to be effective for prevention of hepatocellular carcinomas (HCCs) recurrence, but the detailed mechanisms remain elusive. In vitro, cobalt chloride-treated VEGF induction and hypoxia responsive element (HRE) promoter activity were inhibited by IFNs and this abrogation was cancelled by introduction of small interfering RNA for STAT1. Immunoprecipitation/chromatin immunoprecipitation analyses showed STAT1 bound to hypoxia-inducible factor (HIF)-1α and dissociated HIF-complex from HRE promoter lesion. In a xenograft model using Balb/c nude mice, tumor growth was suppressed by IFNα through inhibition of VEGF expression and it was oppositely enhanced when STAT1-deleted cells were injected. This augmentation was due to upregulation of VEGF and hyaluronan synthase 2. In human samples, 29 HCCs were resected, divided into two groups based on STAT1 activation in tumor and the clinical features were investigated. Patients with suppressed STAT1 activity had a shorter recurrence-free survival. Histological and reverse transcriptase-polymerase chain reaction (RT-PCR) analyses showed portal vein microinvasion and increased VEGF levels in tumors from suppressed STAT1 group. These human samples also showed a reverse correlation between VEGF and STAT1-regulated genes expression. These results in vitro and in vivo suggested that IFNα are potential candidates for prevention of vessel invasion acting through inhibition of VEGF expression and need to be properly used when STAT1 expression is suppressed.

Association of psoriasis with the VEGF gene polymorphism in the northern Polish population

BACKGROUND

Neovascularization plays an important role in pathogenesis of psoriasis and vascular endothelial growth factor (VEGF) seems to be the main angiogenic factor involved in this disease. Published studies which analysed the role of VEGF gene polymorphism in psoriasis were limited and they received controversial results. Objective The aim of our study was to evaluate the association between -1154 G/A, -460 T/C and +405 G/C polymorphisms and the psoriasis susceptibility and to determine whether this genetic variation influence levels of VEGF protein expression.

MATERIALS AND METHODS

One hundred and eighty-nine patients with psoriasis and 215 ethnically matched controls were genotyped using ARMS-PCR and PCR-RFLP methods. VEGF serum levels were assessed in 47 patients and 40 controls using ELISA test.

RESULTS

We noted that an increased risk of Type I psoriasis is associated with -1154 G allele (OR = 1.9; P = 0.04), +405 CC (OR = 2.86; P = 0.03) and -460 TT (OR = 1.56; P = 0.05) genotypes and demonstrated that a significantly increased risk of developing disease is related to presence of haplotype GTC among all patients (OR = 1.97; P = 0.001), patients with Type I (OR = 1.87; P = 0.005) and Type II psoriasis (OR = 2.37, P = 0.01). We have found significantly increased serum levels of VEGF in patients with psoriasis compared with those in healthy controls (P = 0.008). Serum levels of VEGF significantly correlated with PASI: r = 0.72, P < 0.00001. Patients with elevated levels of VEGF in the serum showed more frequently: GC genotype (P = 0.04), C allele (P = 0.02) at the locus +405 and TT genotype (P = 0.03) at the locus -460.

CONCLUSION

Our results strongly support the role of VEGF gene polymorphism in the pathogenesis of psoriasis.

Tobacco carcinogen mediated up-regulation of AP-1 dependent pro-angiogenic cytokines in head and neck carcinogenesis

Tobacco is notably genotoxic and associated with head and neck carcinogenesis. Cigarette carcinogens have the capacity to alter early response gene expression in tobacco-related malignancies via genes such as nuclear factor kappa B (NFκB). A number of early response gene activation events are also facilitated by fos/jun activator protein 1 (AP-1) associated pathways. In the present study, we hypothesize that tobacco products may induce microenvironment alterations, promoting angiogenesis and providing a permissive environment for head and neck cancer progression. In an in vitro analysis, we employed immortalized oral keratinocyte (HOK-16B) and laryngeal squamous carcinoma (UM-SCC-11A) cells to investigate interleukin (IL)-8 and vascular endothelial growth factor (VEGF) induction by cigarette smoke condensate (CSC). IL-8 and VEGF expression is based on interactions between NFκB, AP-1, and NF-IL6. We identified at least 1.5-fold dose-dependent induction of AP-1, VEGF, and IL-8 promoter/reporter gene activity after 24 h exposure to CSC. Next, we stably transfected UM-SCC-11A cells with A-Fos, a dominant negative AP-1 protein. Treatment with CSC of the A-Fos cell lines compared to empty vector controls significantly down-regulated AP-1, VEGF, and IL-8 promoter/reporter gene expression. We also performed ELISAs and discovered significant up-regulation of IL-8 and VEGF secretion by UMSCC 11A after treatment with phorbol 12-myristate 13-acetate, tumor necrosis factor alpha, and CSC, which was down-regulated by the A-Fos dominant negative protein. We conclude tobacco carcinogens up-regulate AP-1 activity and AP-1 dependent IL-8 and VEGF gene expression in head and neck cancer. This up-regulation may promote an angiogenic phenotype favoring invasion in both premalignant and squamous cancer cells of the head and neck.

Identification of the Fra-1 transcription factor in healing skin flaps transplants: a potential role as a negative regulator of VEGF release from keratinocytes

The molecular mechanisms underlying successful myocutaneous skin flap integration, as well as the ischemic loss of transplanted tissue on surgery, remain largely unknown. In this study we used a mouse model of caudally based skin flaps to determine molecular patterns of acute transplant re-integration. Gene chip-based transcriptional analysis revealed an up-regulation of the transcription factor Fra-1 in murine skin flap tissue. Epidermal keratinocytes at the wound margins represented a dominant cellular source of Fra-1 in mice. Moreover, Fra-1 protein showed a clear nuclear localization. In addition, Fra-1 protein was also present in nuclei of wound margin keratinocytes located near the suture line in human skin flaps. In vitro studies using the human keratinocyte cell line HaCaT showed that epidermal growth factor (EGF) was a potent inducer of Fra-1 expression in keratinocytes. Ablation of Fral-1 protein using a specific Fra-1 small interfering (si)RNA markedly increased the EGF-induced vascular endothelial growth factor (VEGF) expression from keratinocytes. These data suggest the involvement of an injury-induced Fra-1 transcription factor as a regulator of keratinocyte gene expression, which might act as an antagonistic player to restrict epithelial-driven angiogenic responses during normal skin flap integration.

Regulation of keratin expression by retinoids

Vitamin A and its natural and synthetic metabolites (retinoids) affect growth and differentiation of human skin and among the genes affected by retinoids in epidermis are keratin genes. Keratins are intermediate filament proteins that have essential functions in maintaining the structural integrity of epidermis and its appendages. Their expressions are under strict control to produce keratins that are optimally adapted to their environment. In this article, retinoid regulation of keratin expression in cultured human epidermal keratinocytes and in human skin in vivo will be reviewed. The direct and indirect mechanisms involved will be discussed and novel therapeutic strategies will be proposed for utilizing retinoids in skin disorders due to keratin mutations (e.g., epidermolysis bullosa simplex and epidermolytic ichthyosis).

A woman with a lower lip nodule: what is your diagnosis?

Angiolymphoid hyperplasia with eosinophilia (ALHE), also known as epitheliod hemangioma is an uncommon benign vascular tumor of the skin. It usually presents as nodules and erythema over the ears, forehead, or scalp. Histologically, the lesion is composed of a combination of immature blood vessels, endothelial cells with distinct epitheliod appearance and chronic inflammatory cell infiltration with numerous eosinophils. Such a case occurring on the lower lip of a 55-year-old woman is presented. The lesion was completely excised with clear margins. Surgical resection is the preferred mode of treatment and is curative.

Cysteinyl-leukotrienes induce vascular endothelial growth factor production in human monocytes and bronchial smooth muscle cells

BACKGROUND

Cysteinyl leukotrienes (cysLTs) are suggested to be implicated in the process of airway remodelling in asthma.

OBJECTIVE

We investigated the potential for cysLTs to modulate vascular endothelial growth factor (VEGF) expression, a growth factor involved in the angiogenesis of airway remodelling.

METHODS

VEGF mRNA and protein were quantified by real-time PCR and ELISA, respectively. VEGF promoter activation was assessed using luciferase gene-tagged promoter constructs.

RESULTS

We found that LTD(4) induction of VEGF in human monocytes and bronchial smooth muscle cells is cysLT1 dependent. Stimulation of HEK293 cells stably expressing cysLT1 or cysLT2 with cysLTs showed a concentration-dependent activation of the VEGF promoter and a time-dependent increase in VEGF mRNA and protein. For the cysLT1-mediated response, mutations of hypoxia-induced factor-1 (HIF-1) sites failed to reduce cysLT-induced VEGF promoter activation and 5' deletions showed that the proximal region containing one AP-1 and four specificity protein 1 (Sp1) sites was necessary. Pretreatment with inhibitors of c-Jun N-terminal kinase (JNK) and extracellular signal-regulated kinase (ERK), but not p38, and an overexpression of dominant negative forms of c-Jun, c-Fos or Ras suggested the implication of mitogen-activated protein kinases and AP-1. Mutation of the AP-1-binding element failed to prevent VEGF transactivation suggesting that AP-1 might not act directly on the promoter. Moreover, inhibition of Sp1-dependent transcription by mithramycin completely inhibited VEGF promoter transactivation and VEGF mRNA expression by LTD(4) . Finally, mutations of Sp1 binding elements prevented VEGF promoter transactivation.

CONCLUSION AND CLINICAL RELEVANCE

Our data indicate for the first time that cysLTs can transcriptionally activate VEGF production via cysLT1 receptors, with the involvement of JNK, ERK, the AP-1 complex and Sp1. These findings suggest that cysLTs may be important in the angiogenic process of airway remodelling and potentially provide a previously unknown benefit of using cysLT1 receptor antagonists in the prevention or treatment of airway remodelling in asthma.

Tranilast could has potential therapeutic value in the treatment of psoriasis

Psoriasis is a common chronic skin disease characterized by recurrent erythromatous skin plaques that exhibit epidermal hyperplasia, variable inflammatory cell infiltrate, and abnormalities of the dermal vascularization. The involvement of angiogenic growth factors such as vascular endothelial growth factor (VEGF), matrix metalloproteinases (MMPs) and inflammatory cytokines such as IFNγ, IL-1, IL-2, TNFα, TGFα and β, IL-6, IL-8, amphiregulin and monocyte chemoattractant protein 1 (MCP-1) have been known to play pathogenic roles in traumatic psoriatic skin. However, anti-angiogenic and anti-inflammatory cytokines regimens might favorably affect the psoriasis disease process. Tranilast is an anti-allergic drug now emerging as anti-angiogenesis and anti-inflammatory effects. In vitro and in vivo experiments have also been strongly showed that tranilast would treat skin psoriasis by inhibition of involving factors. Herein, we hypothesize that local administration of tranilast may be potentially clinically useful in psoriasis.

Update of the management of chronic psoriasis: new approaches and emerging treatment options

Psoriasis is a common, chronic inflammatory skin disease which is associated with a number of significant co-morbidities including: impairment of quality of life; cardiovascular disease; and a seronegative arthritis known as psoriatic arthritis. Our understanding of the pathogenesis of psoriasis has developed at a remarkable rate in recent years. These new insights have significantly changed our perception of the condition and have led to the development of several new treatment strategies. Biological agents have proved a major step forward in therapeutic options for psoriasis. The ability to clear, or almost clear, cutaneous disease has changed the outcomes and expectations of many patients with this disease. The impact on both physical and psychological health may be great. This review covers the clinical features and management of psoriasis with specific reference to new therapeutic options.

Keratins 2 and 4/13 in reconstituted human skin are reciprocally regulated by retinoids binding to nuclear receptor RARalpha

Disorders of keratinization are often treated with vitamin A derivatives (retinoids) which affect keratinocyte differentiation, including keratin (KRT) gene expression. In vivo, suprabasal keratinocytes normally express only keratin (K) 1, K2 and K10, but after topical application of all-trans retinoic acid (ATRA), the granular cells will additionally express K4 and K13, i.e. keratins normally present in oral mucosa and in cultured epidermal keratinocytes. To learn more about the retinoid regulation of keratin expression under in vivo-like conditions, we cultured keratinocytes on de-epidermized dermis in only 0.5% serum. These cells produce a normal-looking epidermis that expresses high mRNA levels of KRT1, KRT2 and KRT10, but minimal amounts of KRT4 and KRT13. Addition of ATRA to the medium for 48 h caused a dose-dependent increase in KRT4/KRT13 and a down-regulation of KRT2 mRNA. An increase in K4 protein was also found. The response was greater than the up-regulation of another retinoid-regulated gene, CRABPII. By studying 10 retinoids with different affinities for the retinoic acid receptors (RAR) and retinoid X receptors (RXR) isoforms, the reciprocal expression of KRT2 and KRT4/KRT13 could be connected with agonists for RARalpha. Two of these agonists, CD336/Am580 and CD2081, altered the expression profile with similar potency as the pan-RAR agonists ATRA and CD367. Co-addition of a pan-RAR antagonist (CD3106/AGN193109) markedly inhibited the induction of KRT4/KRT13 expression, whereas the down-regulation of KRT2 was less affected. In conclusion, RARalpha agonists elicit a reciprocal modulation of KRT2 and KRT4/KRT13 expression in human epidermis, but whether or not the keratin genes also possess RARalpha-specific regulatory elements is still unclear.

Induction of ANGPTL4 expression in human airway smooth muscle cells by PMA through activation of PKC and MAPK pathways

In this study, we demonstrate that protein kinase C (PKC) activators, including phorbol-12-myristate-13-acetate (PMA), 1,2-dioctanoyl-sn-glycerol (DOG), and platelet-derived growth factor alpha are potent inducers of angiopoietin-like protein 4 (ANGPTL4) expression in several normal lung cell types and carcinoma cell lines. In human airway smooth muscle (HASM) cells induction of ANGPTL4 expression is observed as early as 2 h after the addition of PMA. PMA also increases the level of ANGPTL4 protein released in the medium. PKC inhibitors Ro31-8820 and Gö6983 greatly inhibit the induction of ANGPTL4 mRNA by PMA suggesting that this up-regulation involves activation of PKC. Knockdown of several PKCs by corresponding siRNAs suggest a role for PKCalpha. PMA does not activate MAPK p38 and p38 inhibitors have little effect on the induction of ANGPTL4 indicating that p38 is not involved in the regulation of ANGPTL4 by PMA. In contrast, treatment of HASM by PMA induces phosphorylation and activation of Ra, MEK1/2, ERK1/2, JNK, Elk-1, and c-Jun. The Ras inhibitor manumycin A, the MEK1/2 inhibitor U0126, and the JNK inhibitor SP600125, greatly reduce the increase in ANGPTL4 expression by PMA. Knockdown of MEK1/2 and JNK1/2 expression by corresponding siRNAs inhibits the induction of ANGPTL4. Our observations suggest that the induction of ANGPTL4 by PMA in HASM involves the activation of PKC, ERK, and JNK pathways. This induction may play a role in tissue remodeling during lung injury and be implicated in several lung pathologies.

Retinoic acid is a cofactor for translational regulation of vascular endothelial growth factor in human endometrial stromal cells

Vascular endothelial growth factor (VEGF) and endometrial angiogenesis play a critical role in successful embryonic implantation. Despite many studies of the effects of estrogen and progesterone on VEGF expression, its focal regulation at the site of implantation is unknown. Retinoic acid (RA) has been reported to regulate VEGF in a variety of cell types. Because localized RA synthesis occurs within the periimplantation endometrium, we tested the possibility that RA regulates VEGF production in endometrial stromal cells. Using primary and telomerase-immortalized human endometrial stromal cells, we determined that RA alone did not alter constitutive levels of VEGF production, but markedly amplified secretion when the cells were cotreated with activators of VEGF gene transcription (12-O-tetradecanoyl phorbol-13-acetate, TPA; TGF-beta; and IL-1beta). Whereas TPA or TGF-beta alone stimulated VEGF promoter activity and up-regulated mRNA levels, significant protein secretion was detected only after RA was added to the culture systems. Analysis of retinoids in secretory phase endometrial biopsies indicated that endogenous RA accumulated at concentrations sufficient to induce VEGF secretion. Polyribosome profile analysis showed that the addition of RA to transcriptional activators of VEGF shifted the translational suppressed VEGF mRNA transcripts into larger polyribosome complexes engaged in active translation. Although the precise mechanism(s) of the RA effect remains to be defined, it appears to be mediated by reactive oxygen species; the antioxidant N-acetylcysteine inhibited RA+TPA-stimulated secretion of VEGF by more than 80%. Together, our results demonstrate that in human endometrial stromal cells, RA can combine with transcriptional activators of VEGF to augment VEGF secretion through a translational mechanism of action mediated by reactive oxygen species. These findings suggest a link between the spatiotemporal changes of retinoid synthesis in the periimplantation stroma and the capacity to quickly up-regulate focal VEGF secretion needed to induce early angiogenic events of pregnancy.

Vitamin-regulated cytokines and growth factors in the CNS and elsewhere

There is a growing awareness that natural vitamins (with the only exception of pantothenic acid) positively or negatively modulate the synthesis of some cytokines and growth factors in the CNS, and various mammalian cells and organs. As natural vitamins are micronutrients in the human diet, studying their effects can be considered a part of nutritional genomics or nutrigenomics. A given vitamin selectively modifies the synthesis of only a few cytokines and/or growth factors, although the same cytokine and/or growth factor may be regulated by more than one vitamin. These effects seem to be independent of the effects of vitamins as coenzymes and/or reducing agents, and seem to occur mainly at genomic and/or epigenetic level, and/or by modulating NF-kappaB activity. Although most of the studies reviewed here have been based on cultured cell lines, but their findings have been confirmed by some key in vivo studies. The CNS seems to be particularly involved and is severely affected by most avitaminoses, especially in the case of vitamin B(12). However, the vitamin-induced changes in cytokine and growth factor synthesis may initiate a cascade of events that can affect the function, differentiation, and morphology of the cells and/or structures not only in the CNS, but also elsewhere because most natural vitamins, cytokines, and growth factors cross the blood-brain barrier. As cytokines are essential to CNS-immune and CNS-hormone system communications, natural vitamins also interact with these circuits. Further studies of such vitamin-mediated effects could lead to vitamins being used for the treatment of diseases which, although not true avitaminoses, involve an imbalance in cytokine and/or growth factor synthesis.

Association of the CTG (-2578/-460/+405) haplotype within the vascular endothelial growth factor gene with early-onset psoriasis

Polymorphism of vascular endothelial growth factor (VEGF) influences the VEGF production and is subjected to genetic susceptibility of many diseases including psoriasis. Three single nucleotide polymorphisms (SNPs) within the promoter and exon 1 region [-2578(C/A), -460(C/T) and +405(C/G)] were analyzed in 154 patients with chronic plaque psoriasis and in 234 ethnically matched healthy controls from Thailand. The CTG (-2578/-460/+405) haplotype frequency was higher in patients with early-onset psoriasis (44.12%) compared with healthy controls (33.33%) (odds ratio = 1.54, 95% confidence interval = 1.08-2.18, P = 0.016, corrected P value: P(c) = 0.048). The results suggest that the CTG haplotype can be used as a genetic marker for psoriasis especially the early-onset group of Thais.

Commitment of mouse embryonic stem cells to the adipocyte lineage requires retinoic acid receptor beta and active GSK3

Key events leading to terminal differentiation of preadipocytes into adipocytes have been identified in recent years. However, signaling pathways involved in the decision of stem cells to follow the adipogenic lineage have not yet been characterized. We have previously shown that differentiating mouse embryonic stem (mES) cells give rise to functional adipocytes upon an early treatment with retinoic acid (RA). The goal of this work was to identify regulators of RA-induced commitment of mES cells to the adipocyte lineage. First, we investigated the role of RA receptor (RAR) isotypes in the induction of mES cell adipogenesis. Using synthetic retinoids selective of RAR isotypes, we show that RARbeta activation is both sufficient and necessary to trigger commitment of mES cells to adipocytes. Then, we performed a small-scale drug screening to find signaling pathways involved in RARbeta-induced mES cell adipogenesis. We show that pharmacological inhibitors of glycogen synthase kinase (GSK) 3, completely inhibit RARbeta-induced adipogenesis in mES cells. This finding uncovers the requirement of active GSK3 in RARbeta-induced commitment of mES cells toward the adipocyte lineage. Finally, we investigated the role of the Wnt pathway, in which GSK3 is a critical negative regulator, in adipocyte commitment by analyzing Wnt pathway activity in RA- and RARbeta-induced mES cell adipogenesis. Our results suggest that although RARbeta and active GSK3 are required for RA-induced adipogenesis, they might be acting through a Wnt pathway-independent mechanism.

Vascular endothelial growth factor in psoriasis: an indicator of disease severity and control

BACKGROUND

Psoriasis is a chronic disease characterized by abnormal epidermal proliferation, inflammation and angiogenesis. It has been reported that vascular endothelial growth factor (VEGF) is overexpressed in lesional psoriatic skin and its serum levels are significantly elevated in patients with moderate to severe disease.

OBJECTIVE

This study aims to evaluate the possible role of VEGF in the pathogenesis of psoriasis, and its significance as an indicator of disease severity and control.

METHODS

Thirty patients with moderate to severe psoriasis and 10 healthy controls were subjected to baseline evaluation of VEGF. Patients were divided into three groups according to the received treatment: psoralen plus ultraviolet A (PUVA) thrice weekly (group 1), acitretin 50 mg daily (group 2), and combined PUVA twice weekly and acitretin 25 mg daily (group 3).Treatment continued for 16 weeks or up to clinical cure. Every patient was subjected to severity evaluation by Psoriasis Area and Severity Index (PASI) and measurement of serum VEGF before and after treatment.

RESULTS

Mean serum levels of VEGF were significantly elevated in patients (327 +/- 66.2 pg/mL) than control subjects (178 +/- 83.4 pg/mL). A highly significant correlation was found between VEGF and PASI score, but not with other variables. The best clinical response, the least side-effects and the highest reduction of VEGF serum levels were achieved by the combined therapy.

CONCLUSION

The present study supported the proposed role of VEGF in the pathogenesis of psoriasis, and suggested that it could serve as a good indicator of disease severity and control.

Systemic therapies for psoriasis: methotrexate, retinoids, and cyclosporine

Despite the current use and ongoing development of the biological therapies 'traditional' systemic agents will continue to form a key part of the therapeutic armamentarium for patients with severe psoriasis. Long-term maintenance therapy with retinoids and methotrexate is cost-effective and, for many patients with psoriasis, life changing. Regular monitoring is required for both treatments, particularly methotrexate to prevent significant bone marrow suppression and hepatotoxicity. Ideally, cyclosporine should be used for short courses of 3 to 4 months duration, within which it provides excellent disease control. Close assessment of renal function and blood pressure is essential.

Reproductive inhibition and transgenerational toxicity of triphenyltin on medaka (Oiyzias latipes) at environmentally relevant levels

An increasing number of studies have reported unexpectedly high body burdens of triphenyltin (TPT) in wild fishes around the world. To assess the effects of TPT on fish, we exposed pairs of medaka (Oryzias latipes) to different levels of TPT for 5 weeks, and the reproduction responses and transgenerational effects were studied. The results demonstrated that TPT exposure markedly suppressed the spawning frequency, spawned egg number, egg quality and gonad development, and induced teratogenesis, such as hemorrhaging, eye defects, morphological malformation and conjoined twins, less hatchability, and swim-up failure in the F1 generation, thereby resulting in a significant decrease in the capacity to produce viable offspring (p < 0.01). The residual TPT levels in the exposure fish are in the range of 6.52 +/- 0.56 to 5595 +/- 1016 ng of TPT/g of wet weight, similar to those reported in wild fish around the world, indicating TPT contamination in the real world would have a significant adverse effect on the health of fish population. Down-regulation of vitellogenin (VTG) genes in the female of the TPT exposure groups was recognized as a cause for the decreased fecundity. Expressions of VEGFs and PAX6 associated with vascular or ocular development respectively, were measured in hemorrhaging and eye defects embryos and showed good correlations with response outcomes.

Overexpression of vascular endothelial growth factor (VEGF) receptors on keratinocytes in psoriasis: regulated by calcium independent of VEGF

Psoriasis is a common chronic inflammatory disease of the skin characterized by epidermal hyperplasia and angiogenesis. Recently, vascular endothelial growth factor receptors (VEGFRs, including VEGFR-1, VEGFR-2 and VEGFR-3) were found to be expressed in normal human epidermis and associated with proliferation and migration of keratinocytes. The purpose of this study is to investigate the expression of VEGFRs on psoriatic keratinocytes and the roles of calcium and VEGF in regulating VEGFR expression. Skin samples from 17 patients with chronic plaque psoriasis and 11 normal controls were included. The expression of VEGFRs in psoriatic keratinocytes at mRNA and protein levels was determined by reverse transcriptase-polymerase chain reaction (RT-PCR) and Western blot analysis. Localization of the VEGFRs in skin lesions was determined by immuno-fluorescent method. Since keratinocyte proliferation and differentiation rely on calcium concentrations, and VEGF is overexpressed in psoriatic epidermis, we further investigated the roles of calcium and VEGF in regulating the expression of VEGFRs. Overexpression of VEGFR-1, VEGFR-2 and VEGFR-3 in psoriatic epidermis was demonstrated both at mRNA and protein levels in vitro. VEGFRs were strongly labeled in non-lesional, perilesional and lesional psoriatic keratinocytes in all viable epidermal stratums in vivo. Furthermore, both exogenous VEGF165 and calcium enhanced the expression of VEGFRs. Calcium also enhanced the expression of VEGF in non-lesional psoriatic keratinocytes, while targeted blockade of VEGF activity by bevacizum-ab could not inhibit calcium-induced up-regulation of protein levels of VEGFRs. We conclude from these results that VEGFRs are overexpressed in lesional psoriatic epidermal keratinocytes. Both calcium and VEGF regulate VEGFRs expression in psoriatic epidermis. More importantly, calcium is a potential regulator for VEGFR independent of VEGF.

Epidermal vascular endothelial growth factor production is required for permeability barrier homeostasis, dermal angiogenesis, and the development of epidermal hyperplasia: implications for the pathogenesis of psoriasis

Primary abnormalities in permeability barrier function appear to underlie atopic dermatitis and epidermal trauma; a concomitant barrier dysfunction could also drive other inflammatory dermatoses, including psoriasis. Central to this outside-inside view of disease pathogenesis is the epidermal generation of cytokines/growth factors, which in turn signal downstream epidermal repair mechanisms. Yet, this cascade, if sustained, signals downstream epidermal hyperplasia and inflammation. We found here that acute barrier disruption rapidly stimulates mRNA and protein expression of epidermal vascular endothelial growth factor-A (VEGF-A) in normal hairless mice, a specific response to permeability barrier requirements because up-regulation is blocked by application of a vapor-impermeable membrane. Moreover, epidermal vegf(-/-) mice display abnormal permeability barrier homeostasis, attributable to decreased VEGF signaling of epidermal lamellar body production; a paucity of dermal capillaries with reduced vascular permeability; and neither angiogenesis nor epidermal hyperplasia in response to repeated tape stripping (a model of psoriasiform hyperplasia). These results support a central role for epidermal VEGF in the maintenance of epidermal permeability barrier homeostasis and a link between epidermal VEGF production and both dermal angiogenesis and the development of epidermal hyperplasia. Because psoriasis is commonly induced by external trauma [isomorphic (Koebner) phenomenon] and is associated with a prominent permeability barrier abnormality, excess VEGF production, prominent angiogenesis, and epidermal hyperplasia, these results could provide a potential outside-inside mechanistic basis for the development of psoriasis.

Prenatal administration of vitamin A alters pulmonary and plasma levels of vascular endothelial growth factor in the developing mouse

Vitamin A and the retinoids play a unique role in mammalian embryonic and foetal development and are essential for both cellular differentiation and the establishment of normal morphogenesis. Vascular endothelial growth factor (VEGF) is a known potent mitogenic factor that plays a key role in lung development and function maintenance. In order to contribute to a better knowledge of the modulating effects of vitamin A in lung development, we investigated the effects of the antenatal administration of vitamin A on VEGF expression in lungs and plasma from foetuses and neonates. Pregnant mice were subjected to subcutaneous administration of vitamin A on the 12th gestational day. The lungs and plasma from foetuses and neonates were collected daily from the 15th gestational day till the day of birth. Our results show that vitamin A modulates VEGF concentrations both in lungs and plasma. Statistically significant differences were observed at gestational days 15 (P = 0.004 for lungs; P < 0.0001 for plasma), 16 (P < 0.0001 for lungs and plasma) and 18 (P < 0.0001 for lungs; P < 0.05 for plasma). Vitamin A tends to increase the expression of this factor in the lung, particularly during the critical period of perinatal adaptation to postnatal life. These effects seem to be spatial and temporally regulated, and point out to the important role of vitamin A during lung development.

Retinoic acid inhibits angiogenesis and tumor growth of thyroid cancer cells

The anti-proliferative effect of retinoic acid (RA) has been documented for various tumors. Some 40% of patients with advanced and poorly differentiated thyroid cancer have been shown to respond to RA with increased uptake of radioiodine. It has been suggested that these effects may be caused by redifferentiation. Presently, little is known about the effects of RA on tumor angiogenesis, a prerequisite for growth and metastatic spread. The aim of the current study was to determine, whether tumor-induced angiogenesis of thyroid cancer is affected by RA. In vitro, the effect of 0.1/10 microM 13-cis RA on tumor cell number (MTT assay) and secretion of VEGF (ELISA) was analyzed in three thyroid cancer cell lines (FTC 236, C634 and XTC), as well as in endothelial cells (HUVEC) over several passages. In vivo, tumor growth, VEGF-expression and microvessel density (VSD) of RA treated thyroid cancer cells after xenotransplantation to nude mice was evaluated by morphometric analysis. In vitro, thyroid cancer cell lines responded to RA with reduced proliferation, ranging from 26 to 34% after 2 weeks of treatment and with up to 80% reduced secretion of VEGF. In vivo, tumor volumes of animals receiving RA were reduced by 33% (FTC 236), 27% (C643) and 6% (XTC), respectively. VSD of experimental tumors was diminished in the FTC 236 (25%) and the C643 cell line (15%), and almost unchanged in XTC tumors (7%). In vivo, VEGF-expression and apoptosis were not significantly affected by RA. In vitro, proliferation of HUVEC was inhibited by conditioned medium of C643 cells pretreated with RA (0.1/10 microM), as well as by administration of RA (0.1/10 microM). This study confirms thyroid tumor cell growth to be inhibited by RA. It demonstrates a decrease of in vitro VEGF accumulation and reduction of VSD in experimental undifferentiated thyroid carcinoma, suggesting that reduced angiogenesis may be an important mechanism responsible for the therapeutic effect of RA in thyroid cancer. Moreover, a direct anti-proliferative effect of RA on human endothelial cells is suggested.

Immunolocalization and expression of vascular endothelial growth factor receptors (VEGFRs) and neuropilins (NRPs) on keratinocytes in human epidermis

Vascular endothelial growth factor (VEGF) plays an important role in normal and pathological angiogenesis. VEGF receptors (VEGFRs, including VEGFR-1, VEGFR-2, and VEGFR-3) and neuropilins (NRPs, including NRP-1 and NRP-2) are high-affinity receptors for VEGF and are typically considered to be specific for endothelial cells. Here we showed expression of VEGFRs and NRPs on cultured epidermal keratinocytes at both mRNA and protein levels. We further localized these receptors by immunofluorescence (IF) staining in the epidermis of surgical skin specimens. We found positive staining for VEGFRs and NRPs in all layers of the epidermis except for the stratum corneum. VEGFR-1 and VEGFR-2 are primarily expressed on the cytoplasmic membrane of basal cells and the adjacent spinosum keratinocytes. All layers of the epidermis except for the horny cell layer demonstrated a uniform pattern of VEGFR-3, NRP-1, and NRP-2. Sections staining for NRP-1 and NRP-2 also showed diffuse intense fluorescence and were localized to the cell membrane and cytoplasm of keratinocytes. In another panel of experiments, keratinocytes were treated with different concentrations of VEGF, with or without VEGFR-2 neutralizing antibody in culture. VEGF enhanced the proliferation and migration of keratinocytes, and these effects were partially inhibited by pretreatment with VEGFR-2 neutralizing antibody. Adhesion of keratinocytes to type IV collagen-coated culture plates was decreased by VEGF treatment, but this reduction could be completely reversed by pretreatment with VEGFR-2 neutralizing antibody. Taken together, our results suggest that the expression of VEGFRs and NRPs on keratinocytes may constitute important regulators for its activity and may possibly be responsible for the autocrine signaling in the epidermis.

Angiolymphoid hyperplasia with eosinophilia: efficacy of isotretinoin?

BACKGROUND

Angiolymphoid hyperplasia with eosinophilia (ALHE) is a benign but potentially disfiguring vascular lesion. It is usually characterized by dermal and subcutaneous nodules, primarily in the head and neck region. Spontaneous regression is common, but persistent or recurrent lesions may require treatment. Several treatments have been reported but surgery is the most efficient one.

METHODS AND RESULTS

We report a 32-year-old man presenting with multiple nodules on the cheeks, preauricular region and the scalp and who received treatment with isotretinoin (0.5 mg/kg/day) for 1 year with complete resolution of one of his scalp nodules. The rest of the lesions remained stable and were treated with surgical excision without recurrence.

CONCLUSION

Isotretinoin may play a role in the treatment of ALHE due to its antiangiogenic properties via a reduction of vascular endothelial growth factor (VEGF) production by keratinocytes.

Current status and perspective of antiangiogenic therapy for cancer: hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is well known as a typical angiogenic tumor, especially in the moderately to poorly differentiated type. Such clinicopathological characteristics are not only useful for imaging diagnosis but are also applicable to the treatment of HCC. In addition, recent molecular studies have revealed that angiogenesis is closely related to hepatocarcinogenesis. In this review, the molecular mechanism of HCC angiogenesis and the antiangiogenic prevention of HCC are reviewed to introduce the latest trends in antiangiogenic treatment of cancers, including HCC.

All-trans retinoic acid antagonizes UV-induced VEGF production and angiogenesis via the inhibition of ERK activation in human skin keratinocytes

Incident UV radiation leads to the upregulation of vascular endothelial growth factor (VEGF), a potent angiogenic factor, in human skin. However, the molecular basis of UV-induced angiogenesis in skin remains to be elucidated. In this study, we investigated the roles of UV exposure on cutaneous angiogenesis, its associated signaling mechanisms, and the effect of all-trans retinoic acid (tRA) on UV-induced vascularization, and VEGF expression. Using a human epidermal cell line, HaCaT, we found that UV induces VEGF mRNA and protein expression via the MAPK/ERK kinase-ERK1/2 (extracellular signal-regulated kinase 1/2) pathway but not via the phosphatidylinositol 3-kinase (PI3K)/Akt pathway, and that tRA pretreatment significantly inhibits UV-induced VEGF overexpression and ERK1/2 activation. In human skin in vivo, we confirmed that skin vascularization significantly increased after a single exposure to UV, as was evidenced by a prominent increase in vessel size, vascular density, and in the cutaneous area occupied by vessels, and we found that these events are associated with VEGF upregulation. Topical pretreatment with tRA under occlusion inhibited not only UV-induced VEGF upregulation and angiogenesis with a significant reduction of vessel density but also UV-induced ERK1/2 activation in human skin. Collectively, our data demonstrate that tRA inhibits the UV-induced angiogenic switch via downmodulation of ERK1/2 activation and consecutive VEGF overexpression. These findings may help us understand the molecular mechanisms that regulate skin angiogenesis due to UV exposure, and provide evidence of the potential of tRA in terms of preventing angiogenesis-associated skin damage following exposure to UV irradiation.

Vascular endothelial growth factor gene polymorphisms increase the risk to develop psoriasis

We investigated the relationship between eight polymorphisms in the gene encoding for vascular endothelial growth factor (VEGF) (-1540C > A, -1512Ins18, -1451C > T, -460T > C, -160C > T, -152G > A, -116G > A and +405G > C) and plaque-type psoriasis stratified for age at onset, gender and family history of dermatosis. For this purpose, 117 patients with chronic plaque-type psoriasis and 215 healthy subjects were enrolled. We found that being homozygous -1540AA, -1512InsIns, -1451TT, -460CC and -152AA conferred a significant risk in developing psoriasis compared with heterozygous (-1540CA, -1512 + Ins, -1451CT, -460CT and -152AG) and homozygous genotypes (-1540CC, -1512 + +-1451CC, -460TT and -152GG) grouped together [odds ratio (ORs) = 1.73, 1.73, 1.73, 1.77 and 1.87, respectively]. Conversely, having the -116AA or +405GG genotype did not significantly increase the risk of disease expression compared with other genotypes of the same loci. Interestingly, we found that -1540AA, -1512InsIns, -1451TT, -460CC and -152AA homozygous genotypes have a significant two-fold increased risk in developing psoriasis after the age of 40 years (late-onset psoriasis) (ORs = 2.19, 2.19, 2.19, 2.05 and 2.26; P = 0.02, 0.02, 0.02, 0.04 and 0.02, respectively) as compared with controls. On the contrary, we found no phenotype-genotype association of the same magnitude among the patients in whom psoriasis developed at or before the age of 40 years (early-onset psoriasis) compared with controls. Genotype distributions were not significantly different when cases and controls were stratified either by gender or family history of psoriasis. Finally, VEGF plasma concentration was not significantly different between patients and controls and was not correlated with the severity of the disease.

Interaction between Genetic Control of Vascular Endothelial Growth Factor Production and Retinoid Responsiveness in Psoriasis

Vascular endothelial growth factor (VEGF) promotes angiogenesis, and elevated levels are found in plaques of psoriasis. Two VEGF polymorphisms, +405 and -460, are associated with early-onset psoriasis and are close to the functional activator protein-1 site (+419) through which retinoids, an established systemic therapy for psoriasis, can block production of VEGF. We report that peripheral blood mononuclear cells (PBMCs) and epidermal keratinocytes (KC) from patients with psoriasis demonstrate differential, genotype-dependent, regulation of VEGF. For PBMCs, VEGF genotype distinguishes two groups of patients with psoriasis - "high and low VEGF producers" (P < 0.001). In contrast, KC production of VEGF is not genotype dependent. However, the effects of all-trans retinoic acid (RA) on cellular expression of VEGF are determined by both cell type and genotype. RA inhibits KC production of VEGF in a genotype-dependent manner (P < 0.005) whereas RA stimulates PBMCs production irrespective of VEGF genotype (P < 0.001). We also report that the -460 VEGF polymorphism appears to have a clinical pharmacogenetic role in predicting response or non-response of psoriasis to acitretin (P = 0.01). In future, determination of VEGF gene polymorphisms and thus individual patient VEGF "signatures" may be used as a prognostic factor for psoriasis susceptibility/severity and as a means for optimizing treatment response.

Vascular endothelial growth factor acts in an autocrine manner in rhabdomyosarcoma cell lines and can be inhibited with all-trans-retinoic acid

Vascular endothelial growth factor (VEGF) is a potent signalling molecule that acts through two tyrosine kinase receptors, VEGFR1 and VEGFR2. The upregulation of VEGF and its receptors is important in tumour-associated angiogenesis; however, recent studies suggest that several tumour cells express VEGF receptors and may be influenced by autocrine VEGF signalling. Rhabdomyosarcoma (RMS) is the most common paediatric soft-tissue sarcoma, and is dependent on autocrine signalling for its growth. The alveolar subtype of RMS is often characterized by the presence of a PAX3-FKHR translocation, and when introduced into non-RMS cells, the resultant fusion protein induces expression of VEGFR1. In our study, we examined the expression of VEGF and its receptors in RMS, and autocrine effects of VEGF on cell growth. VEGF and receptor mRNA and protein were found to be expressed in RMS cells. Exogenous VEGF addition resulted in extracellular signal-regulated kinase-1/2 phosphorylation and cell proliferation, and both were reduced by VEGFR1 blockade. Growth was also slowed by VEGFR1 inhibitor alone. Treatment of RMS cells with all-trans-retinoic acid decreased VEGF secretion and slowed cell growth, which was rescued by VEGF. These data suggest that autocrine VEGF signalling likely influences RMS growth and its inhibition may be an effective treatment for RMS.

Retinoic Acid and its 4-Oxo Metabolites are Functionally Active in Human Skin Cells In Vitro

Retinoic acid exerts a variety of effects on gene transcription that regulate growth, differentiation, and inflammation in normal and neoplastic skin cells. Because there is a lack of information regarding the influence of metabolic transformation of retinoids on their pharmacologic effects in skin, we have analyzed the functional activity of all-trans-, 9-cis-, and 13-cis-retinoic acid and their 4-oxo-metabolites in normal human epidermal keratinocytes (NHEKs) and dermal fibroblasts using gene and protein expression profiling techniques, including cDNA microarrays, two-dimensional gel electrophoresis, and MALDI-MS. It was previously thought that the 4-oxo-metabolites of RA are inert catabolic end-products but our results indicate instead that they display strong and isomer-specific transcriptional regulatory activity in both NHEKs and dermal fibroblasts. Microarray and proteomic analyses identified a number of novel genes/gene products that are influenced by RA treatment of NHEKs or fibroblasts, including genes for enzymes catalyzing biotransformation of retinoids, corticosteroids, and antioxidants and structural and transport proteins known to be essential for homeostasis. Our results expand current knowledge regarding retinoic acid action within skin cells and the target tissue/cell regulatory systems that are important for modulating the physiological and pharmacological effects of this important class of dermatological drugs.

Ligation of RARgamma inhibits proliferation of phytohaemagglutinin-stimulated T-cells via down-regulating JAK3 protein levels

The mechanisms whereby Vitamin A regulates the immune system are poorly understood. We have shown previously that retinoic acids, the Vitamin A derivatives, promote both apoptosis of neglected thymocytes and the activation-induced cell death of peripheral T-cells via ligating the nuclear retinoid receptor (RAR) gamma. In the present study, we found that human peripheral T-cells express RARalpha and gamma, but not RARbeta. Increasing concentrations of 9-cis RA inhibited phytohaemagglutinin (PHA)-induced proliferation of T-cells, an effect that could be mimicked only by addition of RARgamma agonists and could be inhibited by an RARgamma antagonist. Interleukin-2 (IL-2) produced is known to mediate PHA-induced proliferation of T lymphocytes. Ligation of RARgamma did not affect the PHA-induced high affinity IL-2 receptor expression, slightly reduced the PHA-induced IL-2 production, but interfered with the IL-2-mediated signal transduction resulting in inhibition of PHA-induced phosphorylation of retinoblastoma protein and of up-regulation of Bcl-2. Janus kinases JAK1 and JAK3 play a determinant role in IL-2-dependent signal transduction. Ligation of RARgamma did not affect the levels of JAK1, but prevented IL-2-induced expression of JAK3 resulting in inhibition of PHA-induced phosphorylation of Stat5 molecules. Our data suggest that the previously observed toxic effect of high concentrations of retinoids on the immune system might be mediated via formation of 9-cis RA, which via ligation of RARgamma not only induces cell death in immature thymocytes, but inhibits proliferation of T-cells as well.

Possible involvement of p44/p42 MAP kinase in retinoic acid-stimulated vascular endothelial growth factor release in aortic smooth muscle cells

Retinoic acid modulates cell growth and differentiation of the vascular system. Vascular endothelial growth factor (VEGF) is known as a vascular permeability factor and a potent mitogen for vascular endothelial cells. In the present study, we investigated whether retinoic acid induces VEGF release in aortic smooth muscle A10 cells and if so, the mechanism of VEGF release. Retinoic acid stimulated VEGF release dose-dependently over the range 0.1 nM-0.1 microM. The retinoic acid-stimulated VEGF release was significantly reduced by actinomycin D. Retinoic acid induced the phosphorylation of p44/p42 mitogen-activated protein (MAP) kinase but not p38 MAP kinase or stress-activated protein kinase/c-Jun N-terminal kinase among the MAP kinase superfamily. This effect of retinoic acid was dose-dependent (30 nM-5 microM) and the maximum effect was observed at 0.3 microM. The retinoic acid-stimulated release of VEGF was significantly reduced by PD98059 and U0126, specific MEK inhibitors, which attenuated the retinoic acid-induced phosphorylation of p44/p42 MAP kinase. These results strongly suggest that retinoic acid stimulates the release of VEGF in a p44/p42 MAP kinase-dependent manner in aortic smooth muscle cells.

Retinoic acid decreases nitric oxide production in endothelial cells: a role of phosphorylation of endothelial nitric oxide synthase at Ser(1179)

The effects of retinoic acid (RA) on nitric oxide (NO) production are controversial. Furthermore, it has never been studied whether these effects are mediated by direct modulation of phosphorylation of endothelial nitric oxide synthase (eNOS). Using bovine aortic endothelial cells, we found that all-trans RA (atRA) dose- and time-dependently decreased NO production without alteration in eNOS expression. This decrease was accompanied by reduction in eNOS-Ser(1179) phosphorylation. However, atRA did not alter the phosphorylation of eNOS-Ser(116) or eNOS-Thr(497). Concurrently, atRA also decreased the expressions of vascular endothelial growth factor (VEGF) and its receptor KDR/Flk-1, and Akt phosphorylation. Co-treatment with troglitazone, an activator of VEGF expression, reversed the atRA-induced reductions in eNOS-Ser(1179) phosphorylation and NO production, with concomitant restoration in VEGF expression. Direct treatment with VEGF also reversed these inhibitory effects, suggesting an important role for VEGF. Nonetheless, the RARalpha antagonist Ro 41-5253 did not block all the inhibitory effects of atRA, indicating that these inhibitory effects are not mediated by the RA response element (RARE). Thus, atRA decreases eNOS-Ser(1179) phosphorylation through a mechanism that depends on VEGF-KDR/Flk-1-mediated Akt phosphorylation but is independent of RARE, leading to reduction in NO production.