The expression of syndecan-1 in psoriatic epidermis

Periostin C-Terminal Is Intrinsically Disordered and Interacts with 143 Proteins in an In Vitro Epidermal Model of Atopic Dermatitis

Human periostin is a 78-91 kDa matricellular protein implicated in extracellular matrix remodeling, tumor development, metastasis, and inflammatory diseases like atopic dermatitis, psoriasis, and asthma. The protein consists of six domains, including an N-terminal Cys-rich CROPT domain, four fasciclin-1 domains, and a C-terminal domain. The exons encoding the C-terminal domain may be alternatively spliced by shuffling four exons, generating ten variants of unknown function. Here, we investigate the structure and interactome of the full-length variant of the C-terminal domain with no exons spliced out. The structural analysis showed that the C-terminal domain lacked a tertiary structure and was intrinsically disordered. In addition, we show that the motif responsible for heparin-binding is in the conserved very C-terminal part of periostin. Pull-down confirmed three known interaction partners and identified an additional 140 proteins, among which nine previously have been implicated in atopic dermatitis. Based on our findings, we suggest that the C-terminal domain of periostin facilitates interactions between connective tissue components in concert with the four fasciclin domains.

Altered Distribution and Expression of Syndecan-1 and -4 as an Additional Hallmark in Psoriasis

Syndecans act as independent co-receptors to exert biological activities and their altered function is associated with many pathophysiological conditions. Here, syndecan-1 and -4 were examined in lesional skin of patients with psoriasis. Immunohistochemical staining confirmed altered syndecan-1 distribution and revealed absence of syndecan-4 expression in the epidermis. Fibronectin (FN)—known to influence inflammation and keratinocyte hyperproliferation via α5β1 integrin in psoriasis—was also decreased. Syndecan-1 and -4 expression was analyzed in freshly isolated lesional psoriatic human keratinocytes (PHK) characterized based on their proliferation and differentiation properties. mRNA levels of syndecan-1 were similar between healthy and PHK, while syndecan-4 was significantly decreased. Cell growth and release of the pro-inflammatory Tumor Necrosis Factor-alpha (TNFα) were selectively and significantly induced in PHKs plated on FN. Results from co-culture of healthy keratinocytes and psoriatic fibroblasts led to the speculation that at least one factor released by fibroblasts down-regulate syndecan-1 expression in PHK plated on FN. To assay if biological treatments for psoriasis target keratinocyte proliferation, gelatin-based patches enriched with inteleukin (IL)-17α or TNFα blockers were prepared and tested using a full-thickness healthy epidermal model (Phenion^®). Immunohistochemistry analysis showed that both blockers impacted the localisation of syndecan-1 within the refined epidermis. These results provide evidence that syndecans expression are modified in psoriasis, suggesting that they may represent markers of interest in this pathology.

A Peptide/MicroRNA-31 nanomedicine within an electrospun biomaterial designed to regenerate wounds in vivo

microRNA-31 (miR-31) has been identified to be downregulated in pathologies associated with delayed wound repair. Thus, it was proposed that the delivery of a plasmid encoding miR-31 (pmiR-31) to the skin could hold potential in promoting wound healing. Effective delivery of pmiR-31 was potentiated by encapsulation with the CHAT peptide to form nanocomplexes, this improved cellular entry and elicited a potent increase in miR-31 expression in vitro in both skin human keratinocyte cell line (HaCaT) and human microvascular endothelial cell line (HMEC-1). Transfection efficiencies with CHAT/pEFGP-N1 were significant at 15.2 ± 8.1% in HMEC-1 cells and >40% in HaCaT cells. In this study, the CHAT/pmiR-31 nanocomplexes at a N:P ratio of 10 had an average particle size of 74.2 nm with a cationic zeta potential of 9.7 mV. Delivery of CHAT/pmiR-31 to HaCaT and HMEC-1 cells resulted in significant improvements in cell migration capacity and increased angiogenesis. In vivo studies were conducted in C57BL/6 J mice were CHAT/pmiR-31 was delivered via electrospun PVA nanofibres, demonstrating a significant increase in epidermal (increase of ∼38.2 µm) and stratum corneum (increase of 8.2 µm) layers compared to controls. Furthermore, treatment in vivo with CHAT/pmiR-31 increased angiogenesis in wounds compared to controls, with a significant increase in vessel diameter by ∼20.4 µm compared against a commercial dressing control (Durafiber™). Together, these data demonstrate that the delivery of CHAT/pmiR-31 nanocomplexes from electrospun PVA nanofibres represent an innovative therapy for wound repair, eliciting a positive therapeutic response across both stromal and epithelial tissue compartments of the skin. STATEMENT OF SIGNIFICANCE: This study advances research regarding the development of our unique electrospun nanofibre patch to deliver genetic nanoparticles into wounds in vivo to promote healing. The genetic nanoparticles are comprised of: (a) plasmid micro-RNA31 that has been shown to be downregulated in pathologies with delayed wound repair and (b) a 15 amino acid linear peptide termed CHAT. The CHAT facilitates complexation of miR-31 and cellular uptake. Herein, we report for the first time on the use of CHAT to deliver a therapeutic cargo pmiR-31 for wound healing applications from a nanofibre patch. Application of the nanofibre patch resulted in the controlled delivery of the CHAT/pmiR-31 nanoparticles with a significant increase in both epidermal and stratum corneum layers compared to untreated and commercial controls.

Robust Lentiviral Gene Delivery But Limited Transduction Capacity of Commonly Used Adeno-Associated Viral Serotypes in Xenotransplanted Human Skin

Skin is an easily accessible organ, and therapeutic gene transfer to skin remains an attractive alternative for the treatment of skin diseases. Although we have previously documented potent lentiviral gene delivery to human skin, vectors based on adeno-associated virus (AAV) rank among the most promising gene delivery tools for in vivo purposes. Thus, we compared the potential usefulness of various serotypes of recombinant AAV vectors and lentiviral vectors for gene transfer to human skin in a xenotransplanted mouse model. Vector constructs encoding firefly luciferase were packaged in AAV capsids of serotype 1, 2, 5, 6, 8, and 9 and separately administered by intradermal injection in human skin transplants. For all serotypes, live bioimaging demonstrated low levels of transgene expression in the human skin graft, and firefly luciferase expression was observed primarily in neighboring tissue outside of the graft. In contrast, gene delivery by intradermally injected lentiviral vectors was efficient and led to extensive and persistent firefly luciferase expression within the human skin graft only. The study demonstrates the limited capacity of single-stranded AAV vectors of six commonly used serotypes for gene delivery to human skin in vivo.

Proteoglycans in Normal and Healing Skin

Significance: Proteoglycans have a distinct spatial localization in normal skin and are essential for the correct structural development, organization, hydration, and functional properties of this tissue. The extracellular matrix (ECM) is no longer considered to be just an inert supportive material but is a source of directive, spatial and temporal, contextual information to the cells via components such as the proteoglycans. There is a pressing need to improve our understanding of how these important molecules functionally interact with other matrix structures, cells and cellular mediators in normal skin and during wound healing. Recent Advances: New antibodies to glycosaminoglycan side chain components of skin proteoglycans have facilitated the elucidation of detailed localization patterns within skin. Other studies have revealed important proliferative activities of proteinase-generated fragments of proteoglycans and other ECM components (matricryptins). Knockout mice have further established the functional importance of skin proteoglycans in the assembly and homeostasis of the normal skin ECM. Critical Issues: Our comprehension of the molecular and structural complexity of skin as a complex, dynamic, constantly renewing, layered connective tissue is incomplete. The impact of changes in proteoglycans on skin pathology and the wound healing process is recognized as an important area of pathobiology and is an area of intense investigation. Future Directions: Advanced technology is allowing the development of new artificial skins. Recent knowledge on skin proteoglycans can be used to incorporate these molecules into useful adjunct therapies for wound healing and for maintenance of optimal tissue homeostasis in aging skin.

Heparanase is preferentially expressed in human psoriatic lesions and induces development of psoriasiform skin inflammation in mice

Heparanase is the sole mammalian endoglycosidase that selectively degrades heparan sulfate, the key polysaccharide associated with the cell surface and extracellular matrix of a wide range of tissues. Extensively studied for its capacity to promote cancer progression, heparanase enzyme was recently implicated as an important determinant in several inflammatory disorders as well. Applying immunohistochemical staining, we detected preferential expression of heparanase by epidermal keratinocytes in human psoriatic lesions. To investigate the role of the enzyme in the pathogenesis of psoriasis, we utilized heparanase transgenic mice in a model of 12-O-tetradecanoyl phorbol 12-myristate 13-acetate-induced cutaneous inflammation. We report that over-expression of the enzyme promotes development of mouse skin lesions that strongly recapitulate the human disease in terms of histomorphological appearance and molecular/cellular characteristics. Importantly, heparanase of epidermal origin appears to facilitate abnormal activation of skin-infiltrating macrophages, thus generating psoriasis-like inflammation conditions, characterized by induction of STAT3, enhanced NF-κB signaling, elevated expression of TNF-α and increased vascularization. Taken together, our results reveal, for the first time, involvement of heparanase in the pathogenesis of psoriasis and highlight a role for the enzyme in facilitating abnormal interactions between immune and epithelial cell subsets of the affected skin. Heparanase inhibitors (currently under clinical testing in malignant diseases) could hence turn highly beneficial in psoriatic patients as well.