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In the version of this article initially published, in the Acknowledgements, the grant number for the Start Grant TWILIGHT awarded to M.A.L. by the European Research Council was omitted. The correct wording is “Supported by...the European Research Council (...Start Grant TWILIGHT (637801) to M.A.L.).” The error has not been corrected in the original article. © 2020, The Author(s), under exclusive licence to Springer Nature America, Inc.

Tenascin-X, is an extracellular matrix glycoprotein expressed in skin, muscle, tendons, and blood vessels with an anti-adhesive function. Biallelic Tenascin-X mutations cause classical-like Ehlers-Danlos syndrome. We report a 46-year-old woman with slowly progressive weakness of the lower limbs and myalgia from age 28 years. In the past she had Raynaud's phenomenon, multiple sprains and joint dislocations, conjunctival haemorrhages and a colonic perforation during colonoscopy. Neurologic examination showed moderate asymmetric proximal and axial muscular weakness, distal amyotrophy of 4 limbs, moderate skin hyperextensibility, and hypermobility of distal joints of fingers. Whole body Magnetic Resonance Imaging showed symmetric fatty infiltration of thigh and leg muscles, with predominant atrophy of thighs. Next Generation Sequencing revealed two pathogenic TNXB variants, g.32024681C>G, c.7826-1G>C, and g.32016181dup, c.9998dupA, p.(Asn3333Lysfs* 35). Western Blot and immunofluorescence studies confirmed a marked Tenascin-X reduction in both patient's serum and muscle. Here we further detail the clinical and genetic spectrum of a patient with classical-like Ehlers-Danlos syndrome and prominent muscle involvement. (C) 2020 Elsevier B.V. All rights reserved.

Contains fulltext : 182646.pdf (Publisher’s version ) (Open Access) Terminally differentiating epidermal keratinocytes express a large number of structural and antimicrobial proteins that are involved in the physical barrier function of the stratum corneum and provide innate cutaneous host defense. Late cornified envelope (LCE) genes, located in the epidermal differentiation complex on chromosome 1, encode a family of 18 proteins of unknown function, whose expression is largely restricted to epidermis. Deletion of two members, LCE3B and LCE3C (LCE3B/C-del), is a widely-replicated psoriasis risk factor that interacts with the major psoriasis-psoriasis risk gene HLA-C*06. Here we performed quantitative trait locus analysis, utilizing RNA-seq data from human skin and found that LCE3B/C-del was associated with a markedly increased expression of LCE3A, a gene directly adjacent to LCE3B/C-del. We confirmed these findings in a 3-dimensional skin model using primary keratinocytes from LCE3B/C-del genotyped donors. Functional analysis revealed that LCE3 proteins, and LCE3A in particular, have defensin-like antimicrobial activity against a variety of bacterial taxa at low micromolar concentrations. No genotype-dependent effect was observed for the inside-out or outside-in physical skin barrier function. Our findings identify an unknown biological function for LCE3 proteins and suggest a role in epidermal host defense and LCE3B/C-del-mediated psoriasis risk.

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Background: Defensins are antimicrobial peptides that exert immunomodulatory and chemotactic functions. Based on these properties and their high expression levels in the skin, they are likely to affect skin inflammation, infection, and wound healing. This may lead to therapeutic applications in (burn) wound healing. Objective: We aimed to investigate the effects of human β-defensins (hBDs) on keratinocytes and fibroblasts, 2 major skin cell types involved in skin regeneration. Methods: Monolayer keratinocyte and fibroblast cultures were exposed to recombinant hBDs, and we overexpressed hBD2 and hBD3 in keratinocytes of reconstructed epidermal equivalents by lentiviral transduction. The effects were measured by immunohistochemistry, quantitative real-time PCR, and migration assays. Kinome analyses were performed on cultured keratinocytes to investigate the signal transduction events elicited by hBD stimulation. Results: We found that hBD3 induced the expression of cytokines and chemokines in keratinocytes, which was not observed in fibroblasts. hBD2, however, stimulated cell migration only in fibroblasts, which was not found for hBD3. Both defensins are likely to exert receptor-mediated effects in keratinocytes, as witnessed by changes in protein kinase activation following stimulation by hBD2 and hBD3. Kinome analysis suggested that protein kinase C activation was a common event for both defensins. We observed, however, considerable differences in keratinocyte responses between stimulation by exogenous recombinant defensins and endogenous defensins expressed following lentiviral transduction. Conclusion: Defensins exert modest biological effects on skin cells that are potentially beneficial in wound healing, but many questions regarding the biological mechanisms of action and relevance for the in vivo situation are still remaining.

The low-frequency contribution to the systematic and random sampling errors in single-tower eddy-covariance flux measurements is investigated using large-eddy simulation (LES). We use a continuous LES integration that covers a full year of realistic weather conditions over Cabauw, the Netherlands, and emulate eddy-covariance measurements. We focus on the daytime flux imbalance, when the turbulent flux is sufficiently resolved. Averaged over the year, daytime single-tower eddy-covariance flux measurements lead to a significant systematic underestimation of the turbulent flux. This underestimation depends on the averaging period and measurement height. For a 3600-s averaging period at 16-m height, the systematic underestimation reduces to a few percent, but for 900-s averaged tall-tower measurements at 100-m height, the fluxes are systematically underestimated by over 20 %. The year-long dataset facilitates an investigation into the environmental conditions that influence the eddy-covariance flux imbalance. The imbalance problem is found to vary widely from day to day, strongly dependent on the flow regime. In general, the imbalance problem reduces with increased mean wind speed, but days having the largest imbalance (over twice the average) are characterized by roll vortices that occur for average wind speeds, typically having a boundary-layer height (zi) to Obukhov length (L) ratio of 10zi/L<100.

Item does not contain fulltext A papillary-structured collagen fibril membrane is created, mimicking the 3D-architecture of the human papillary dermis. Primary human keratinocytes cultured to confluency on papillar-structured films are compared to keratinocytes cultured on flat membranes. Microscopical evaluation reveals the presence of morphologically distinct cells at the base of the papillar structures that are not observed on flat membranes. Gene expression microarrays and RT-qPCR indicate that these cells are in a more proliferative/migrational state, whereas cells on flat membranes have a more differentiated expression profile. Immunohistochemical stainings confirm these results. In conclusion, specific collagen architecture can direct keratinocyte behavior, and this may be used to further improve skin regeneration. 01 mei 2012

Item does not contain fulltext Development of new drugs is a lengthy and complicated process involving many disciplines, Here we provide a background for the audience and review new developments in drug discovery and (pre)clinical development. These include the role of ‘omics’ technologies and the introduction of ‘biologicals’. We discuss the changing roles of academia, small biotech companies and ‘big pharma’.

Contains fulltext : 89106.pdf (Publisher’s version ) (Closed access) BACKGROUND: Microarray studies on the epidermal transcriptome in psoriasis and atopic dermatitis (AD) have revealed genes with disease-specific expression in keratinocytes of lesional epidermis. These genes are possible candidates for disease-specific pathogenetic changes, but could also provide a tool for molecular diagnostics of inflammatory skin conditions in general. OBJECTIVES: To analyse if gene expression signatures as found in purified epidermal cells from AD are also present in other eczematous conditions such as allergic and irritant contact dermatitis. METHODS: We used real-time quantitative polymerase chain reaction, immunohistochemistry and bioinformatics to investigate gene expression in different forms of eczema. Normal epidermis and psoriatic epidermis were analysed for comparison. RESULTS: Carbonic anhydrase II was highly induced in epidermis from all forms of eczema but not in psoriasis. Remarkably, the presumed neuron-specific Nel-like protein 2 showed a strong induction only in AD epidermis. Interleukin-1F9, elafin, beta-defensin-2 and vanin-3 were strongly induced in psoriasis, but not in any type of eczema. High levels of the chemokines CCL17 and CXCL10 were predominantly found in epidermis of allergic contact dermatitis. The chemokine CXCL8 was highly expressed in psoriasis, AD and allergic contact dermatitis, but not in irritant contact dermatitis. Cluster analysis or multinomial logistic regression indicated that expression levels of a set of seven genes are a strong predictor of the type of inflammatory response. CONCLUSIONS: These observations contribute to molecular diagnostic criteria for inflammatory skin conditions. 01 maart 2010

Contains fulltext : 53566.pdf (Publisher’s version ) (Closed access) We analysed the diversity of tenascin-X (TNX) species in serum and studied parameters that could affect determination of TNX levels in serum. Using western blot analysis we identified at least seven distinct TNX species, ranging from 75 kDa to the presumably full-length 450 kDa form. Purification of serum TNX followed by sequence analysis positively identified two major TNX species of 75 and 140 kDa. We found that serum TNX binds to tropoelastin but not to fibrillar collagens. We conclude that serum TNX is composed of distinct molecular species that retain functional activity.

Contains fulltext : 147170.pdf (Publisher’s version ) (Open Access) The present invention concerns novel pantothenone compounds having pantetheinase inhibitory activity as well as antiplasmodial activity. These compounds can suitably be used in therapeutic and or prophylactic treatment of malaria. Furthermore, the present invention provides combinations of pantothenone compounds and pantothenamides. Combining a pantothenone with a pantothenamide increases the antimalarial potency by an order of magnitude. It is hypothesized that inhibition of pantetheinase activity could protect pantothenamides against degradation by serum-derived pantetheinases, thereby revealing the hitherto unknown antimalaria activity of pantothenamides. The present invention thus, for the first time, makes available compounds and combinations of compounds for use in therapeutic and or prophylactic treatment of malaria infection in a human or animal subject in need thereof, relying on interference with host or pathogen-derived pantetheinase dependent pathways. 08 december 2011

De vorige eeuw was getuige van de opkomst van numerieke weer- en klimaatmodellen. Weersvoorspelling, voorheen een empirische procedure gebaseerd op de persoonlijke ervaring van de meteoroloog, ontwikkelde zich tot een wetenschappelijke methode om de toekomstige toestand van de atmosfeer te voorspellen op basis van de huidige toestand en tendens. Tegelijkertijd werden klimaatmodellen ontwikkeld om inzicht te krijgen in het gedrag van ons klimaat over tijdspannes van meer dan honderden jaren. Als gevolg van de enorme rekenkracht die vereist is om deze weer- of klimaatmodellen te kunnen draaien, ontstond een nauwe verwikkeling tussen atmosferische en computerwetenschap. Door de combinatie van toenemende computerkracht, beschikbaarheid van globale observaties als invoer en de onophoudelijk doorontwikkeling van weer- en klimaatmodellen, kan de wereldwijde atmosferische stroming nu worden berekend met een ongeloo?ijke nauwkeurigheid. De resterende achilleshiel van weer- en klimaatmodellen blijft echter de representatie van fenomenen op de schaal van turbulentie, zoals turbulent transport, wolken en neerslag. Deze fenomenen kunnen (nog) niet opgelost worden door hedendaagse weer- en klimaatmodellen (daar hebben deze modellen te weinig detail voor), waardoor ze vertegenwoordigd moeten worden door parametrische schema’s. Om de kwaliteit van dit soort schema’s te testen zijn specialistische modellen ontwikkeld, zogenaamde Large-Eddy Simulations (LES), die een beperkt oppervlak betrekken waarop wolken wel realistisch kunnen worden opgelost. In dit proefschrift worden LES modellen ingezet met het doel weer en klimaatvoorspellingen te verbeteren. In hoofdstuk twee worden LES resultaten gebruikt om een analytisch ’geraamte’ op te zetten met betrekking tot de evenwichtsoplossingen van cumulus-bewolking (stapelwolken) voor verschillende grootschalige weersituaties. Zo’n opzet kan ons begrip verbeteren van de manier waarop wolken reageren als de grootschalige situatie veranderd. Gezien weer- en klimaatmodellen projecties kunnen maken van de grootschalige situatie, kunnen we zo beter voorspellen hoe wolken zich zullen gedragen. De ’tradionele’ manier om kennis te combineren van LES en van weer- en klimaatstudies, zoals hierboven beschreven, leunt op de mogelijkheid om de grootschalige situatie te onderscheiden van de kleinschalige situatie. Dit is tegenwoordig echter helemaal niet meer vanzelfsprekend. Computerkracht neemt dermate snel toe dat we binnen twintig jaar in staat zullen zijn om de ontwikkeling van de globale atmosfeer voor de komende week te berekenen op een turbulentie-oplossende manier: dus op een detailniveau dat het mogelijk maakt turbulentie en individuele (stapel)wolken te beschrijven. Traditionele weer- en klimaatmodellen zijn echter niet ontworpen voor dit detailniveau, en kunnen dit niet aan zonder grote ingrepen. LES modellen zijn wel ontworpen voor dit detailniveau, maar niet voor grote oppervlaktes. Het ziet er dus naar uit dat toekomstige weer- en klimaatmodellen kenmerken van beide specializaties zullen krijgen. De rode draad van dit proefschrift is de studie in hoeverre we LES kunnen gebruiken om het ’werkelijke’ weer of klimaat te modelleren. Door de grote hoeveelheid benodigde rekenkracht worden LES modellen typisch alleen toegepast voor geidealiseerde casussen. In hoofdstuk drie wordt echter de mogelijkheid onderzocht om een nieuwe computertechniek toe te passen bij LES modellering: het gebruik van gra?sche co-processor chips (graphics processing unit, GPU). Het blijkt dat als we ons LES model aanpassen op het gebruik van deze chips, het model zodanig versneld kan worden dat nieuwe toepassingen, bijvoorbeeld in weersvoorspelling, mogelijk worden. Het GPU-LES model wordt daarom uitgerust met procedures om op een realistische manier de grond-atmosfeer interactie en de grootschalige invloeden te behandelen. In hoofdstuk vier testen we het model door middel van simulaties van het dagelijkse weer rondom Cabauw voor het gehele jaar 2012. Deze simulaties laten zien dat het LES model waarde kan toevoegen door zijn gedetailleerde representatie van turbulentie en wolkenprocessen. Daarnaast wordt in hoofdstuk vijf deze simulatie gebruikt om inzicht te geven in de kwaliteit van metingen van turbulent transport van warmte en vocht. Deze metingen zijn van groot belang om een goede weerspiegeling van de atmosferische grenslaag te kunnen maken in weer- en klimaatmodellen. Tenslotte wordt in hoofdstuk zes de grootste GPU-supercomputer van Europa ingezet om een ’proof of concept’ te bewerkstelligen van turbulentie-oplossende weersvoorspelling over Nederland met behulp van LES. Dit is een eerste kleine stap richting turbulentie-oplossende (dus met een detailniveau van individuele stapelwolken) weersvoorspelling vanuit een LES invalshoek. Het onderzoek in dit proefschrift kan zo een weg banen voor een nadere fusie van wolkensimulaties en globale weer- en klimaatmodellen.

Item does not contain fulltext PlsX is an acyl-acyl carrier protein (ACP):phosphate transacylase that interconverts the two acyl donors in Gram-positive bacterial phospholipid synthesis. The deletion of plsX in Staphylococcus aureus results in a requirement for both exogenous fatty acids and de novo type II fatty acid biosynthesis. Deletion of plsX (SP0037) in Streptococcus pneumoniae did not result in an auxotrophic phenotype. The DeltaplsX S. pneumoniae strain was refractory to myristic acid-dependent growth arrest, and unlike the wild-type strain, was susceptible to fatty acid synthesis inhibitors in the presence of exogenous oleate. The DeltaplsX strain contained longer chain saturated fatty acids imparting a distinctly altered phospholipid molecular species profile. An elevated pool of 18- and 20-carbon saturated fatty acids was detected in the DeltaplsX strain. A S. pneumoniae thioesterase (TesS, SP1408) hydrolyzed acyl-ACP in vitro, and the DeltatesS DeltaplsX double knockout strain was a fatty acid auxotroph. Thus, the TesS thioesterase hydrolyzed the accumulating acyl-ACP in the DeltaplsX strain to liberate fatty acids that were activated by fatty acid kinase to bypass a requirement for extracellular fatty acid. This work identifies tesS as the gene responsible for the difference in exogenous fatty acid growth requirement of the DeltaplsX strains of S. aureus and S. pneumoniae.

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Contains fulltext : 50224.pdf (Publisher’s version ) (Open Access) Cystatin M/E is a high affinity inhibitor of the asparaginyl endopeptidase legumain, and we have previously reported that both proteins are likely to be involved in the regulation of stratum corneum formation in skin. Although cystatin M/E contains a predicted binding site for papain-like cysteine proteases, no high affinity binding for any member of this family has been demonstrated so far. We report that human cathepsin V (CTSV) and human cathepsin L (CTSL) are strongly inhibited by human cystatin M/E. Kinetic studies show that Ki values of cystatin M/E for the interaction with CTSV and CTSL are 0.47 and 1.78 nM, respectively. On the basis of the analogous sites in cystatin C, we used site-directed mutagenesis to identify the binding sites of these proteases in cystatin M/E. We found that the W135A mutant was rendered inactive against CTSV and CTSL but retained legumain-inhibiting activity. Conversely, the N64A mutant lost legumain-inhibiting activity but remained active against the papain-like cysteine proteases. We conclude that legumain and papain-like cysteine proteases are inhibited by two distinct non-overlapping sites. Using immunohistochemistry on normal human skin, we found that cystatin M/E co-localizes with CTSV and CTSL. In addition, we show that CTSL is the elusive enzyme that processes and activates epidermal transglutaminase 3. The identification of CTSV and CTSL as novel targets for cystatin M/E, their (co)-expression in the stratum granulosum of human skin, and the activity of CTSL toward transglutaminase 3 strongly imply an important role for these enzymes in the differentiation process of human epidermis.

Item does not contain fulltext The demand for large-scale gene expression analysis tools is on the rise now that several genomes have been sequenced. One of these tools, serial analysis of gene expression (SAGE), allows the qualitative as well as quantitative analysis of a large number of genes in a defined tissue or culture model. SAGE has already been successfully used to identify differentially expressed genes in normal physiological processes and pathological conditions. This chapter focuses on the SAGE protocol and its application to cultured human keratinocytes, and on MicroSAGE, an adapted protocol that allows the use of small amounts of mRNA from isolated epidermis or a skin biopsy.

Item does not contain fulltext Cryopyrin-associated periodic syndrome (CAPS) is a hereditary autoinflammatory disorder. Patients suffer from chronic systemic inflammation involving the skin (urticaria), joints arthritis) and in some cases also peritoneum (peritonitis) and meninges (meningitis). Recently, a causative mutation was found in the NLRP3 gene, which results in overactivation of the potent proinflammatory cytokine interleukin-1 beta (IL-1β). Targeted therapies including the IL-1 receptor antagonist (IL-1Ra) anakinra, the IL-1R-Fc fusion protein rilonacept and the monoclonal anti-IL-1β antibody canakinumab are very effective. Schnitzler syndrome is a rare, chronic autoinflammatory disease, characterized by chronic urticaria, paraproteinemia and systemic inflammation. In view of phenotypical similarities to CAPS, anakinra was tried and appeared to be highly effective in Schnitzler syndrome. There are indications that canakinumab is also effective. However, the exact pathophysiology of Schnitzler syndrome remains to be elucidated.

Item does not contain fulltext Ultraviolet B (UVB) irradiation is known to induce activation of cellular stress response pathways in cultured cells or intact human skin, as demonstrated by phosphorylation of MAP kinase family members and up- or down-stream targets, using biochemical assays. This study demonstrates by immunohistochemistry that low-dose UVB irradiation of normal human skin induces rapid and reversible phosphorylation of c-jun (a target of c-jun N-terminal kinase) and p38 mitogen activated protein kinase (p38 MAP kinase). Phosphorylation was maximal at 4-8 h and returned to normal levels at 48 h after irradiation. Nuclear localization of these phosphorylated substrates was found using antisera against the epitope containing the phosphorylated serine-73 of c-jun, and the dually phosphorylated epitope (threonine-180 and tyrosine-182) of p38 MAP kinase. Nearly all epidermal cells were positive for c-jun phosphorylation, whereas p38 phosphorylation was seen predominantly in the differentiated layers. In contrast to the massive activation of c-jun and p38, only a small population of the suprabasal cells showed nuclear translocation of nuclear factor kappa B (NFkappaB), and a few scattered cells became apoptotic, as determined by TUNEL (TdT mediated dUTP nick end labelling) staining. The expression of involucrin and skin-derived anti-leukoproteinase (SKALP)/elafin, two genes putatively under control of the c-jun and p38 pathways, was found to be increased. These findings establish the first cellular localization of UVB-induced protein phosphorylation of stress response proteins in human epidermis, thereby providing a link between cellular activation and gene expression in defined cell populations.

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Contains fulltext : 57333.pdf (Publisher’s version ) (Open Access) Contains fulltext : 57333schalkwijk.pdf (Publisher’s version ) (Closed access) Contains fulltext : 57333timmermans.pdf (Publisher’s version ) (Closed access) BACKGROUND: We recently described a new autosomal recessive type of Ehlers-Danlos syndrome (EDS) based on a deficiency of the extracellular matrix protein tenascin-X (TNX). TNX-deficient patients have hypermobile joints, hyperextensible skin and show easy bruising. Because of the reported cardiovascular abnormalities in other EDS types and the excessive haematoma formation after mild trauma in TNX-deficient individuals, we investigated whether cardiovascular or coagulation abnormalities occur in these patients. METHODS: We examined seven TNX-deficient patients. One of them had a mitral valve prolapse and died postoperatively after valve replacement, before the study was completed. RESULTS: Bleeding time and coagulation factors (INR, APTT, PT and fibrinogen) were all within the normal range. Ultrasonographic examination of the carotid and femoral arteries showed normal vessel wall compliance and distensibility. Echocardiography showed a slight billowing of the mitral valve in two patients from one family. All patients had normal diameters of aortic root and ascending aorta. CONCLUSION: Although the patient group is small, there are no indications of generalised cardiovascular abnormalities in this type of EDS. We would recommend echocardiography for all these patients at the first evaluation and when a cardiac murmur appears.

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Item does not contain fulltext Psoriasis was until recently regarded as a T-cell-driven disease with presumed (auto)immune mechanisms as its primary cause. This view was supported by clinical data and genetic studies that identified risk factors functioning in adaptive and innate immunity, such as HLA-C*06, ERAP1, the IL-23 pathway, and NF-kappaB signaling. Candidate gene approaches and genome-wide association studies, however, have identified copy number polymorphisms of the beta-defensin cluster and deletion of late cornified envelope (LCE) 3B and 3C genes (LCE3C_LCE3B-del) as psoriasis risk factors. As these genes are expressed in epithelial cells and not by the immune system, these findings may cause a change of paradigm for psoriasis, not unlike the reported filaggrin association that has profoundly changed the views on atopic dermatitis. In addition to genetic polymorphisms of the immune system, genetic variations affecting the skin barrier are likely to contribute to psoriasis. Recent studies have shown epistatic interactions involving HLA-C*06, ERAP1, and LCE3C_LCE3B-del, which makes psoriasis a unique model to investigate genetic and biological interactions of associated genes in a complex disease. We present a model for disease initiation and perpetuation, which integrates the available genetic, immunobiological, and clinical data.Journal of Investigative Dermatology advance online publication, 24 May 2012; doi:10.1038/jid.2012.167.

Contains fulltext : 107850.pdf (Publisher’s version ) (Closed access) BACKGROUND: Recent studies have emphasized the importance of heritable and acquired skin barrier abnormalities in common inflammatory diseases such as psoriasis and atopic dermatitis (AD). To date, no comprehensive studies on the effect of experimental barrier disruption on cornified envelope protein expression have been performed. OBJECTIVES: To analyse the effect of experimental skin barrier disruption on the expression of cornified envelope structural proteins and keratinocyte differentiation-regulating proteins. METHODS: We examined mRNA (day 1, 3 and 7) and protein (day 1, 2, 4 and 9) expression levels of structural proteins and regulatory molecules after sodium dodecyl sulphate (SDS) application on normal skin, and tape stripping of uninvolved epidermis of patients with psoriasis and AD and healthy controls. RESULTS: Upon tape stripping, several structural molecules were significantly downregulated (at the mRNA level as well as the protein level), including LCE5A, LCE2B, FLG, FLG2 and LOR, whereas others were upregulated: IVL, SPRR1, SPRR2, HRNR and most notably LCE3A. The epidermal crosslinking enzymes TGM1, TGM3 and TGM5 were all upregulated, whereas proteases involved in the desquamation process (CTSV, KLK5 and KLK7) were downregulated or unaffected. Most results were similar in SDS-instigated irritant contact dermatitis. There was no significant difference in response between normal epidermis and nonlesional skin of patients with psoriasis and AD. CONCLUSIONS: Skin barrier disruption induces a temporary barrier repair response composed of increased expression of several cornification-related proteins, and decreased expression of some structural and desquamation-related proteins. 01 juni 2012

Item does not contain fulltext BACKGROUND: Recent genome-wide association studies have identified several genetic risk factors for psoriasis, but data on their association with age at onset are lacking. OBJECTIVES: To compare the association between known risk alleles and psoriasis in well-defined cohorts with paediatric- and adult-onset psoriasis. METHODS: Based on previous studies we selected seven genes and loci associated with psoriasis. Patients with paediatric-onset (< 18 years) and adult-onset psoriasis (>/= 18 years) and controls were genotyped. Genotype frequencies were compared between controls (n = 450) and all cases (n = 217), and between controls and cases stratified for confirmed age at onset (paediatric onset n = 80, adult onset n = 85). RESULTS: Paediatric-onset psoriasis showed a significant association with single nucleotide polymorphisms in the ERAP1 (P = 0.042) and IL23R loci (P = 0.042), LCE3C_LCE3B-del (P = 0.003) and HLA-C*06 (P = 1.72 x 10(-19)) when compared with the control group. A significant association of these four genes was also demonstrated when all psoriasis cases were compared with controls. In adult-onset psoriasis a significant association was found for HLA-C*06 (P = 5.11 x 10(-6)) and for LCE3C_LCE3B-del (P = 0.042). No associations were found for the IFIH1, IL12B and TRAF3IP2 loci. CONCLUSIONS: Notwithstanding the small cohort sizes, we demonstrated an association with established and recently discovered genetic risk factors in paediatric-onset psoriasis including genes involved in epidermal barrier function and adaptive immunity. Our data suggest that heritable factors may play a more important role in paediatric-onset psoriasis than in adult-onset psoriasis.

Contains fulltext : 89038schalkwijk.pdf (Publisher’s version ) (Closed access) Tenascin-X is a large extracellular matrix glycoprotein that is widely distributed within connective tissues and is associated with an autosomal recessive type of Ehlers-Danlos syndrome (EDS). Tenascin-X represents the first EDS susceptibility gene that does not code for a fibrillar collagen or collagen-processing enzyme. We describe a paediatric case of tenascin-X deficiency and review the literature. 01 december 2010

Contains fulltext : 88300.pdf (Publisher’s version ) (Closed access) BACKGROUND: Psychological stressors might contribute to the severity of chronic inflammatory diseases such as psoriasis by dysregulating hypothalamic-pituitary-adrenal (HPA) axis activity. OBJECTIVES: To evaluate the role of cortisol, a key component of the HPA axis, in reaction to psychological stress in patients with psoriasis. METHODS: Serum cortisol, clinical indicators of disease severity (Psoriasis Area and Severity Index) and self-report measures of daily stressors were measured monthly for 6 months in 62 patients with psoriasis. RESULTS: In addition to the previous findings in this sample showing that peak levels of daily stressors predicted an increase in disease severity a month later, the peak levels of daily stressors were also significantly associated with a lower cortisol level. Moreover, patients who persistently experienced higher levels of daily stressors had lower mean cortisol levels than patients who experienced lower levels of daily stressors. CONCLUSIONS: Results suggest that daily stressors influence disease outcome in patients with psoriasis by affecting cortisol levels at moments of high stress. Furthermore, patients with persistently high levels of stressors seem to have a specific psychophysiological profile of lowered cortisol levels and may be particularly vulnerable to the influence of stressors on their psoriasis. 01 november 2010

Contains fulltext : 51741.pdf (Publisher’s version ) (Open Access) Recent work has demonstrated an unexpected prevalence of copy number variation in the human genome, and has highlighted the part this variation may play in predisposition to common phenotypes. Some important genes vary in number over a high range (e.g. DEFB4, which commonly varies between two and seven copies), and have posed formidable technical challenges for accurate copy number typing, so that there are no simple, cheap, high-throughput approaches suitable for large-scale screening. We have developed a simple comparative PCR method based on dispersed repeat sequences, using a single pair of precisely designed primers to amplify products simultaneously from both test and reference loci, which are subsequently distinguished and quantified via internal sequence differences. We have validated the method for the measurement of copy number at DEFB4 by comparison of results from >800 DNA samples with copy number measurements by MAPH/REDVR, MLPA and array-CGH. The new Paralogue Ratio Test (PRT) method can require as little as 10 ng genomic DNA, appears to be comparable in accuracy to the other methods, and for the first time provides a rapid, simple and inexpensive method for copy number analysis, suitable for application to typing thousands of samples in large case-control association studies.

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Contains fulltext : 47314schalkwijk.pdf (Publisher’s version ) (Closed access) Ehlers-Danlos syndrome (EDS) is a heterogeneous group of connective tissue disorders with characteristic skin and joint involvement. The concept that EDS is a disease of fibrillar collagen was challenged by the identification of a clinically distinct, recessive type of EDS caused by deficiency of the extracellular matrix protein tenascin-X (TNX). Interestingly, haploinsufficiency of TNX is associated with the dominantly inherited hypermobility type of EDS. In this study, we examined whether missense mutations in the TNX gene can account for some of the cases of hypermobility type EDS. Furthermore, we studied whether missense mutations or heterozygosity for truncating mutations in the TNX gene lead to alterations in the dermal connective tissue. Sequence analysis revealed three missense mutations in TNX in hypermobility type EDS patients, which were not present in 192 control alleles. Morphometric analysis of skin biopsies of these patients showed altered elastic fibers in one of them, suggesting that this missense mutation is disease causing. Light microscopic and ultrastructural changes of the elastic fibers were observed in TNX-haploinsufficient hypermobility type EDS patients, which were not found in hypermobility type EDS patients in whom TNX mutations were excluded. Our results indicate that the observed alterations in elastic fibers are specific for hypermobility type EDS patients with mutations of TNX.

Contains fulltext : 47358schalkwijk.pdf (Publisher’s version ) (Closed access) Tenascin-X is an extracellular matrix protein initially identified because the gene encoding it overlaps with the human CYP21B gene. Because studies of gene and protein function of other tenascins had been poorly predictive of essential functions in vivo, we used a genetic approach that critically relied on an understanding of the genomic locus to uncover an association between inactivating tenascin-X mutations and novel recessive and dominant forms of Ehlers-Danlos syndrome (EDS). Tenascin-X provides the first example of a gene outside of the fibrillar collagens and their processing enzymes that causes EDS. Tenascin-X null mice recapitulate the skin findings of the human disease, confirming a causative role for this gene in EDS. Further evaluation of these mice showed that tenascin-X is an important regulator of collagen deposition in vivo, suggesting a novel mechanism of disease in this form of EDS. Further studies suggest that tenascin-X may do this through both direct and indirect interactions with the collagen fibril. Recent studies show that TNX effects on matrix extend beyond the collagen to the elastogenic pathway and matrix remodeling enzymes. Tenascin-X serves as a compelling example of how human "experiments of nature" can guide us to an understanding of genes whose function may not be evident from their sequence or in vitro studies of their encoded proteins. (c) 2005 Wiley-Liss, Inc.

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Item does not contain fulltext Pharmacological treatments for psoriasis are generally based on antiproliferative, anti-inflammatory, or differentiation-modifying activity, or a combination of two or more of these actions. Potentially new drugs for treatment of psoriasis, which act on proliferation, can be identified by screening large compound libraries in a cell proliferation model that allows for characterization of drug effects on in vitro growth of normal human keratinocytes. High-throughput programs based on biological testing of diverse collections of compounds can rapidly identify leads for potential drug candidates in the treatment of psoriasis. In this study, we describe nonradioactive measurement of keratinocyte proliferation in the exponential growth phase in a 96-well format, using a sensitive deoxyribonucleic acid-binding dye to analyze drugs that are pharmacologically active in growth inhibition. Release of lactate dehydrogenase was used to exclude cytotoxic effects. We examined a number of compounds in a test range of 10(-7) to 10(-5) M, including known antipsoriatic drugs, and experimental drugs that are potentially useful in the treatment of psoriasis. We found strong concentration-dependent growth inhibition by dithranol, an antipsoriatic compound that is presumed to target the epidermal compartment. Methotrexate, cyclosporin A, and all-trans retinoic acid did not significantly affect proliferation at therapeutically relevant concentrations. The p38 mitogen-activated protein kinase inhibitor, SB220025, and curcumin, a natural phytochemical, inhibited keratinocyte proliferation at 10(-5) M. We conclude that this assay, in combination with the previously developed assays for psoriatic differentiation, provides a useful tool for identification of antipsoriatic drugs.

Item does not contain fulltext Serial analysis of gene expression (SAGE) has been used for quantitative analysis of gene expression. We applied cluster analysis on multiple SAGE libraries derived from premalignant epidermal tissue (actinic keratosis), normal human epidermis, and cultured keratinocytes. The samples were obtained from skin biopsies without contamination by dermal tissue or blood. A total of 60,000 transcripts (tags) were analyzed. Two-way cluster analysis was applied to both the transcripts and the tissues, resulting in separation of the cultured cells from the epidermal samples, and clustering of many, presumably coregulated, genes. Two clusters of genes, strongly up-regulated in the tumor tissue compared with normal epidermis, were investigated in more detail. The differential expression of genes could be confirmed in actinic keratosis from four patients. Several of these genes have been previously associated with carcinogenesis or are likely to be important on the basis of their presumed function. Automated literature search tools show that a subgroup of these genes is coexpressed in other tissues and is part of an epidermal differentiation gene cluster on chromosome 1q21. We conclude that cluster analysis on large data sets uncovers clear partitions and correlations that could be confirmed by independent methods. We predict that these partitions will lead to biological interpretations that can be relevant for understanding the processes of carcinogenesis and tumor progression.

Item does not contain fulltext In the present study we compared the effect of a ceramide 3-containing emollient (Locobase(R) Repair) with a control emollient (vaselinum album/cremor lanette ana) and untreated damaged skin using clinical, bioengineering and immunohistochemical methods in two different models of experimentally induced skin barrier dysfunction. In model A (n = 13) skin barrier dysfunction was inflicted at three investigation sites by tape stripping. In model B (n = 13) the volunteers were patch tested at three investigation sites with sodium dodecyl sulphate (0.2%) for 4 h a day for 4 consecutive days. The investigation sites were treated once a day with the above-mentioned agents. Irritant reaction was assessed daily by erythema scoring and measurements of transepidermal water loss (TEWL). After 5D, punch biopsies were taken from all sites. Immunohistochemical assessment was carried out with respect to epidermal proliferation, epidermal differentiation and Langerhans cells. Tape stripping resulted in an erythematous reaction and an increase of TEWL associated with up-regulation of cycling cells, involucrin and expression of cytokeratin 16. At day 4, ceramide 3-containing emollient significantly decreased (p < 0.03) the erythema score, TEWL and cycling cells in comparison with the untreated site. Repetitive exposure to SDS induced a variable degree of erythema, gradual increase of TEWL, an increase of cycling cells, and up-regulation of involucrin, E-FABP and SKALP. The treatment with the control emollient significantly prevented erythema, increase of TEWL and cycling cells at day 4 compared to the untreated site. In summary, the present study demonstrated that both tested emollients improve skin barrier in different conditions compared to the untreated skin. There is some indication that formulations containing skin-related lipids might be of benefit in barrier disruption following tape stripping. Different models and clinical trials are needed to establish the usefulness in specific conditions of emollients containing skin-related lipids.

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Heparan sulfate proteoglycans (HSPGs) are components of the basement membrane (BM) of various tissues. They consist of a core protein and negatively charged glycosaminoglycan side chains: the heparan sulfate (HS) moieties. In psoriasis, uninvolved skin of psoriasis patients and in normal skin, the distribution of HSPGs was studied immunohistochemically by means of three different monoclonal antibodies: JM-72, directed against the HSPG-core protein, JM-13 against the sulfated domains of HS and JM-403 against the unmodified/low sulfated parts of HS. In psoriasis JM-13 staining was consistently absent in the tips of the dermal papillae, whereas JM-13 showed a continuous staining in the BM of uninvolved and normal skin. JM-403 staining was present in BM of all specimens. In addition, a honeycomb-like staining was found in epidermis of normal skin and to a lesser extent in uninvolved skin, due to binding with plasma membrane-associated HS. In psoriasis this JM-403 staining of the epidermis was invariably absent. JM-72 showed a continuous staining of BM in all biopsies. In conclusion, normal human skin and involved psoriatic skin show clear differences in expression of HS. These data may provide insight into the role of HSPGs in psoriasis, which remains further to be elucidated.

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