| 1. |
- Chamcheu, Jean Christopher
(författare)
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Disease-causing Keratin Mutations and Cytoskeletal Dysfunction in Human Skin : In vitro Models and new Pharmacologic Strategies for Treating Epidermolytic Genodermatoses
- 2010
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Epidermolysis bullosa simplex (EBS) and epidermolytic ichthyosis (EI) are rare skin fragility diseases characterized by intra-epidermal blistering due to autosomal dominant-negative mutations in basal (KRT5 or KRT14) and suprabasal (KRT1 or KRT10) keratin genes, respectively. Despite vast knowledge in the disease pathogenesis, the pathomechanisms are not fully understood, and no effective remedies exist. The purpose of this work was to search for keratin gene mutations in EBS patients, to develop in vitro models for studying EBS and EI, and to investigate novel pharmacological approaches for both diseases. We identified both novel and recurrent KRT5 mutations in all studied EBS patients but one which did not show any pathogenic keratin mutations. Using cultured primary keratinocytes from EBS patients, we reproduced a correlation between clinical severity and cytoskeletal instability in vitro. Immortalized keratinocyte cell lines were established from three EBS and three EI patients with different phenotypes using HPV16-E6E7. Only cell lines derived from severely affected patients exhibited spontaneous keratin aggregates under normal culture conditions. However, heat stress significantly induced keratin aggregates in all patient cell lines. This effect was more dramatic in cells from patients with a severe phenotype. In organotypic cultures, the immortalized cells were able to differentiate and form a multilayered epidermis reminiscent of those observed in vivo. Addition of two molecular chaperones, trimethylamine N-oxide dihydrate (TMAO) and sodium 4-phenylbutyrate (4-PBA), reduced the keratin aggregates in both stressed and unstressed EBS and EI keratinocytes, respectively. The mechanism of action of TMAO and 4-PBA was shown to involve the endogenous chaperone system (Heat shock proteins e.g. Hsp70). Besides, MAPK signaling pathways also seemed to be incriminated in the pathogenesis of EBS. Furthermore, depending on which type of keratin is mutated, 4-PBA up-regulated Hsp70 and KRT4 (possibly compensating for mutated KRT1/5), and down-regulated KRT1 and KRT10, which could further assist in protecting EBS and EI cells against stress. In conclusion, novel and recurrent pathogenic keratin mutations have been identified in EBS. Immortalized EBS and EI cell lines that functionally reflect the disease phenotype were established. Two pharmacologic agents, TMAO and 4-PBA, were shown to be promising candidates as novel treatment of heritable keratinopathies in this in vitro model.
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| 2. |
- Buraczewska, Izabela, 1976-
(författare)
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Skin barrier responses to moisturizers
- 2008
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Moisturizers are used in various types of dry skin disorders, but also by people with healthy skin. It is not unusual that use of moisturizers is continued for weeks, months, or even years. A number of moisturizers have been shown to improve the skin barrier function, while others to deteriorate it, but the reason for observed effects remains unknown. Further understanding of the mechanism by which long-term treatment with moisturizers influences the skin barrier would have clinical implications, as barrier-deteriorating creams may enhance penetration of allergens or irritants and predispose to dry skin and eczema, while barrier-improving ones could reduce many problems. The present research combined non-invasive techniques with analyses of skin biopsies, allowing studies of the epidermis at molecular and cellular level. Test moisturizers were examined on healthy human volunteers for their effect on the skin barrier, with regard to such factors as pH, lipid type, and presence of a humectant, as well as complexity of the product. After a 7-week treatment with the moisturizers, changes in transepidermal water loss, skin capacitance, and susceptibility to an irritant indicated a modified skin barrier function. Moreover, the mRNA expression of several genes involved in the assembly, differentiation and desquamation of the stratum corneum, as well as lipid metabolism, was altered in the skin treated with one of the moisturizers, while the other moisturizer induced fewer changes. In conclusion, long-term use of moisturizers may strengthen the barrier function of the skin, but also deteriorate it and induce skin dryness. Moisturizers have also a significant impact on the skin biochemistry, detectable at molecular level. Since the type of influence is determined by the composition of a moisturizer, more careful selection of ingredients could help to design moisturizers generating a desired clinical effect, and to avoid ingredients with a negative impact on the skin.
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| 3. |
- Zhang, Hanqian
(författare)
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Congenital Recessive Ichthyosis : Studies of Gene Expressions Related to Keratinocyte Differentiation and Skin Barrier Repair
- 2019
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Autosomal recessive congenital ichthyosis (ARCI) is a rare monogenetic disorder characterized by a defective skin barrier, hyperkeratosis, and dry, scaly skin. It affects keratinocyte differentiation and is caused by mutations in any of at least 12 genes believed to control the formation of ω-O-acylceramide and the corneocyte lipid envelope (CLE): ABCA12, ALOXE3, ALOX12B, CERS3, CYP4F22, ELOVL4, LIPN, NIPAL4, PNPLA1, SDR9C7, SLC27A4, and TGM1.Studies of keratinocyte differentiation and gene expression in ARCI may help us better understand the pathobiology of skin barrier formation. One way to verify that ARCI-related gene products are operating in a chain of events essential for lipid barrier formation is to use immunofluorescence and in situ proximity ligation assays to demonstrate the proteins’ colocalizations in the epidermis. In paper I, a new method for the objective quantitative image analysis of protein expression and colocalization in different epidermal layers of skin sections was developed using free, open-source software, CellProfiler. Using this method and microarray analyses of skin biopsies from ARCI patients with TGM1 mutations (n = 5) compared with those of healthy controls (n = 4), many ARCI-related genes were found to be upregulated in patient epidermis (paper II). Because many other genes involved in keratinocyte differentiation and immune/inflammatory response, including PPARD, were also induced in the patients’ microarrays, the effects of a ligand-dependent transcription factor, PPARδ, encoded by PPARD, were studied on ARCI-related gene expression in cultured keratinocytes, usually showing the pronounced upregulation by PPARδ agonists (paper III). Furthermore, using previous array data obtained from cultured differentiated keratinocytes and from skin biopsies of patients with TGM1 mutations, nine novel candidate markers of differentiation were identified, and the upregulation was verified by qPCR of mRNA from cultured keratinocytes and skin biopsies. These transcripts were also induced by PPARδ agonists in cultured proliferating keratinocytes (paper IV).To conclude, the upregulation of other ARCI-related genes in patients with TGM1 mutations might reflect a feedback mechanism in ω-O-acylceramide biosynthesis, which, however, is unable to restore the patients’ skin barrier. In theory, substitution therapy with ω-O-acylceramide and recombinant TGm-1 may be required. Because PPARδ activation appears involved in upregulating ARCI-related genes and nine novel differentiation marker genes, all potentially important for barrier repair, this approach could become a treatment option for several types of ichthyosis and wound healing.
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| 4. |
- Koskela von Sydow, Anita, 1979-
(författare)
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Regulation of fibroblast activity by keratinocytes, TGF-β and IL-1α : studies in two- and three dimensional in vitro models
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Dysregulated wound healing is commonly associated with excessive fibrosis. Connective tissue growth factor (CTGF/CCN2) is characteristically overexpressed in fibrotic diseases and stimulated by transforming growth factor-β (TGF-β) in dermal fibroblasts. Reepithelialisation and epidermal wound coverage counteract excessive scar formation. We have previously shown that interleukin-1α (IL-1α) derived from keratinocytes conteracts TGF-β-stimulated CTGF-expression. The aim of this thesis was to further explore the effects of keratinocytes and IL-1α on gene and protein expression, as well as pathways, in TGF-β stimulated fibroblasts. Fibroblasts were studied in vitro by conventional two dimensional cell culture models and in a three dimensional keratinocyte-fibroblast organotypic skin culture model.The results showed that IL-1 suppresses basal and TGF-β-induced CTGF mRNA and protein, involving a possible TAK1 mechanism. Keratinocytes regulate the expression of fibroblast genes important for the turnover of the extracellular matrix. Most of the genes analysed (11/13) were regulated by TGF-β and counter regulated by keratinocytes. The overall results support a view that keratinocytes regulate fibroblasts to act catabolically (anti-fibrotic) on the extracellular matrix.Transcriptional microarray and gene set enrichment analysis showed that antagonizing effects of IL-1α on TGF-β were much more prominent than the synergistic effects. The most confident of these pathways was the interferon signaling, which were inhibited by TGF-β and activated by IL-1α. A proteomics study confirmed that IL-1α preferentially conteracts TGF-β effects. Six new fibroblast proteins involved in synthesis/ regulation were identified, being regulated by TGF-β and antagonized by IL-1α. Pathway analysis confirmed counter-regulation of interferon signaling by the two cytokines. These findings have implications for understanding the role of fibroblasts for inflammatory responses and development of fibrosis in the skin.
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| 5. |
- Sturesdotter Hoppe, Torborg
(författare)
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Skin Barrier Function and mRNA Expression Profiles in Patients with Atopic Dermatitis, Ichthyosis Vulgaris, and X-linked Recessive Ichthyosis : Aetiopathogenic Differences and the Impact of Moisturizing Treatment
- 2013
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Atopic dermatitis (AD), ichthyosis vulgaris (IV), and X-linked recessive ichthyosis (XLRI) are characterized by dry skin and impaired skin barrier. AD and IV are related to loss-of-function mutations in FLG (encoding filaggrin), whereas XLRI is caused by deletions or inactivating mutations in the steroid sulphatase gene (STS). Patients regularly use moisturizing creams, but little is known about the creams’ effects on the skin barrier.The present work combines objective scorings, non-invasive techniques, and molecular analyses of skin biopsies to characterize the skin in 57 patients with AD, IV, or XLRI, and in 14 healthy controls. Patients were classified according to their FLG and STS mutation status: AD with FLG+/+ (n = 14), AD with FLG+/– (n = 14), AD/IV with FLG–/– (n = 15), and XLRI with STS– (n = 14), as well as one man with a novel point mutation. Assessments were conducted at baseline and after four weeks of treatment with three different moisturizers applied to volar forearm skin.At baseline, dryness scoring and non-invasive assessments verified impaired skin barrier function in all patients. In patients with AD/IV, microarray analysis identified 300–3000 up- or downregulated mRNA transcripts involved in signalling pathways important for inflammation and barrier repair. The skin phenotype and number of altered transcripts were correlated with the FLG mutation status, with FLG–/– patients displaying the highest transepidermal water loss (TEWL) and the most altered transcript levels. In contrast, despite an equally dysfunctional skin barrier, only limited changes in mRNA transcripts occurred in XLRI patients. Treatment with moisturizers improved skin dryness similarly in all groups, but TEWL behaved differently: it decreased slightly in the AD/IV group and increased in the XLRI group, especially after urea treatment. Only minute effects on skin pH and mRNA expression were observed.In conclusion, FLG mutations elicit pro-inflammatory mechanisms probably aimed at restoring barrier competence. This does not occur in patients with XLRI, presumably because STS deficiency automatically increases the barrier thickness. Moisturizing treatment improves skin dryness in patients with AD, IV, or XLRI, but does not seem to normalize the altered epidermal gene expression profile in AD/IV patients.
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| 6. |
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| 7. |
- Kolundzic, Nikola, et al.
(författare)
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Induced pluripotent stem cell (iPSC) line from an epidermolysis bullosa simplex patient heterozygous for keratin 5 E475G mutation and with the Dowling Meara phenotype
- 2019
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Ingår i: Stem Cell Research. - : ELSEVIER SCIENCE BV. - 1873-5061 .- 1876-7753. ; 37
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Tidskriftsartikel (refereegranskat)abstract
- We have generated MLi002-A, a new induced pluripotent stem cell (iPSC) line derived from keratinocytes of a skin punch biopsy of a female patient with the severe epidermolysis bullosa simplex Dowling-Meara phenotype and the keratin K5 E475G mutation. Keratinocytes were reprogrammed using non-integrating Sendai virus vectors, and xeno-free culture conditions were used throughout. The characterization of MLi002-A cell line consisted of molecular karyotyping, mutation screening using restriction enzyme digestion and Sanger sequencing, and testing of the pluripotency and differentiation potentials by immunofluorescence of associated markers both in vitro and in vivo. This is the first iPSC model of EB Simplex.
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| 8. |
- Li, Hao, 1984-
(författare)
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In vitro Studies of Genodermatoses Affecting Cytoskeletal Integrity and Lipid Processing in Human Epidermis : Pathogenic Mechanisms and Effects of Retinoid Therapy
- 2012
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Autosomal dominant epidermolytic ichthyosis (EI) is a rare disease characterized by intra-epidermal blistering due to mutations in either of two keratin genes, KRT1 and KRT10, expressed by suprabasal keratinocytes. Autosomal recessive congenital ichthyosis (ARCI) is a non-blistering, hyperkeratotic disease caused by mutations in one of the following genes: ABCA12, ALOX12B, ALOXE3, TGM1, CYP4F22, NIPAL4 and SLC27A4, which are all essential for skin barrier homeostasis. ARCI and EI often respond well to treatment with retinoids, but the mechanism of action is unclear. The aim of this thesis was to increase the knowledge of pathogenic pathways in ichthyosis and to find new explanations to the effect of retinoids.In vitro studies of immortalized keratinocytes from EI patients showed an abnormal keratin aggregation after heat stress, that could be partially inhibited by pre-treatment with all-trans retinoic acid (ATRA) or retinoic acid receptor α-agonists. ATRA treatment also reduced the relative expression of mutated vs wildtype KRT10. The clearance of ATRA in human keratinocytes was found to be mediated by CYP26B1.In skin biopsies from ARCI patients, immunofluorescence analysis of 12R-LOX, eLOX-3, TGM1, ichthyin and FATP4 showed altered expression, not only of the mutated protein, but also of the other proteins. These observations are consistent with a feedback regulatory mechanism by which the loss of one protein results in an up-regulation of other proteins. Furthermore, 12R-LOX, eLOX-3 and TGM1 were intimately co-localized in stratum corneum, as were ichthyin and FATP4, suggesting that the proteins are linked to the same metabolic pathway. When treated with a CYP26 inhibitor known to raise the endogenous ATRA level of the skin, two patients with NIPAL4 mutations, initially exhibiting increased co-localization signals for 12R-LOX and eLOX-3, displayed normalized lipoxygenase expressions and showed clinical improvement.In conclusion, mechanisms are proposed by which pathogenic keratin aggregations in EI and epidermal protein deficiencies in ARCI patients may be mitigated by retinoids. Furthermore, the vivid crosstalk between proteins incriminated in ARCI suggests that these enzymes operate along a common metabolic pathway essential for producing barrier lipids in stratum corneum. Any abrogation of this production may cause barrier failure, hence resulting in a compensatory hyperkeratosis characteristic of congenital ichthyosis.
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| 9. |
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| 10. |
- Vahlquist, Anders, et al.
(författare)
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Ichthyosis : A Road Model for Skin Research
- 2020
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Ingår i: Acta Dermato-Venereologica. - : Medical Journals Sweden AB. - 0001-5555 .- 1651-2057. ; 100, s. 197-206
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Forskningsöversikt (refereegranskat)abstract
- The understanding of monogenetic disorders of cornification, including the group of diseases called ichthyoses, has expanded greatly in recent years. Studies of the aetiology of more than 50 types of ichthyosis have almost invariably uncovered errors in the biosynthesis of epidermal lipids or structural proteins essential for normal skin barrier function. The barrier abnormality per se may elicit epidermal inflammation, hyperproli-feration and hyperkeratosis, potentially contributing to the patient's skin symptoms. Despite this and other new knowledge about pathomechanisms, treatment of ichthyosis often remains unsatisfactory. This review highlights a series of approaches used to elucidate the pathobiology and clinical consequences of different types of ichthyosis, and related diseases with the ultimate goal of finding new and better treatments.
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