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Purpose: We aimed to assess the biological and clinical significance of the human cysteine protease inhibitor cystatin M/E, encoded by the CTS6 gene, in diseases of human hair and skin., Methods: Exome and Sanger sequencing was performed to reveal the genetic cause in two related patients with hypotrichosis. Immunohistochemical, biophysical, and biochemical measurements were performed on patient skin and 3D-reconstructed skin from patient-derived keratinocytes., Results: We identified a homozygous variant c.361C>T (p.Gln121*), resulting in a premature stop codon in exon 2 of CST6 associated with hypotrichosis, eczema, blepharitis, photophobia and impaired sweating. Enzyme assays using recombinant mutant cystatin M/E protein, generated by site-directed mutagenesis, revealed that this p.Gln121* variant was unable to inhibit any of its three target proteases (legumain and cathepsins L and V). Three-dimensional protein structure prediction confirmed the disturbance of the protease/inhibitor binding sites of legumain and cathepsins L and V in the p.Gln121* variant., Conclusion: The herein characterized autosomal recessive hypotrichosis syndrome indicates an important role of human cystatin M/E in epidermal homeostasis and hair follicle morphogenesis.

Purpose of Review: This article reviews recent findings on the skin microbiome. It provides an update on the current understanding of the role of microbiota in healthy skin and in inflammatory and allergic skin diseases., Recent Findings: Advances in computing and high-throughput sequencing technology have enabled in-depth analysis of microbiota composition and functionality of human skin. Most data generated to date are related to the skin microbiome of healthy volunteers, but recent studies have also addressed the dynamics of the microbiome in diseased and injured skin. Currently, reports are emerging that evaluate the strategies to manipulate the skin microbiome, intending to modulate diseases and/or their symptoms., Summary: The microbiome of normal human skin was found to have a high diversity and high interpersonal variation. Microbiota compositions of diseased lesional skin (in atopic dermatitis and psoriasis) showed distinct differences compared with healthy skin. The function of microbial colonization in establishing immune system homeostasis has been reported, whereas host-microbe interactions and genetically determined variation of stratum corneum properties might be linked to skin dysbiosis. Both are relevant for cutaneous disorders with aberrant immune responses and/or disturbed skin barrier function. Modulation of skin microbiota composition to restore host-microbiota homeostasis could be future strategies to treat or prevent disease.

Pattern recognition receptors (PRRs) evolved to protect organisms against pathogens, but excessive signaling can induce immune responses that are harmful to the host. Putative PRR dysfunction is associated with numerous immune disorders that affect the skin, such as systemic lupus erythematosus, cryopyrin-associated periodic syndrome, and primary inflammatory skin diseases including psoriasis and atopic dermatitis. As yet, the evidence is often confined to genetic association studies without additional proof of a causal relationship. However, insight into the role of PRRs in the pathophysiology of some disorders has already resulted in new therapeutic approaches based on immunomodulation of PRRs., (Copyright © 2012 S. Karger AG, Basel.)

Muto et al. report that UVA light induces the expression of elafin, a potent elastase inhibitor, in skin fibroblasts. Elafin binds to elastic fibers by transglutaminase-mediated cross-linking and protects against proteolytic breakdown. Decreased degradation could contribute to accumulation of elastotic material in photodamaged skin. Elastase and its locally produced inhibitors play a role in actinic elastosis.

Background: Cystatins are natural and specific inhibitors of endogenous mammalian lysosomal cysteine proteinases and exogenous microbial cysteine proteinases. Cystatins were shown to provide regulatory and protective functions against uncontrolled proteolysis in several disease processes. Recently we reported that cystatin M/E, which is a novel member of the cystatin gene family, has an unusually restricted expression pattern that is limited to skin. Although cystatin M/E possesses two distinct biochemical properties (it is a proteinase inhibitor and a substrate for transglutaminase) its physiological function is unknown. Disturbance of the balance between proteinases and their inhibitors can lead to irreversible damage as in chronic inflammatory reactions and tumour invasion., Objectives: To examine the expression pattern of cystatin M/E in inflammatory conditions and neoplastic skin disorders in order to obtain possible clues on its function. Furthermore, we wished to determine whether cystatin M/E expression could discriminate between various types of neoplasia., Methods: Biopsy material of normal skin, atopic dermatitis and psoriatic lesional skin, healing excisional wounds in healthy volunteers, and several types of epidermal neoplasia (keratoacanthoma, actinic keratosis, basal cell carcinoma and squamous cell carcinoma) were used in this study. For comparison we studied the expression of cystatin M/E in squamous neoplasias from non-cutaneous origin. Affinity-purified polyclonal antibodies against cystatin M/E were used for immunohistochemical detection., Results: Cystatin M/E is constitutively expressed in the stratum granulosum of normal skin, sebaceous glands, eccrine sweat glands and the infundibular epithelium of hair follicles. Expression in atopic dermatitis and psoriasis was found to extend to several layers of the stratum spinosum. In wound healing, cystatin M/E was not found in the edge of migrating keratinocytes, but it was strongly expressed in the suprabasal layers of the neo-epidermis. In epidermal neoplasias cystatin M/E expression was only found in differentiated cells and keratinized cell nests., Conclusions: Inflammation causes cystatin M/E to be expressed in the spinous cell layers where it colocalizes with transglutaminase for which it serves as a substrate. Speculatively, increased expression of cystatin M/E is compatible with a role in controlling increased levels of cysteine proteinases during inflammation and infection. Cystatin M/E expression in neoplastic epidermis is confined to well-differentiated cells and as such does not discriminate between benign and (pre)malignant epidermal neoplasias.

The expression of tenascin, a recently discovered extracellular matrix glycoprotein, was studied by immunohistochemistry in normal human skin and in a number of skin diseases with epidermal hyperproliferation such as psoriasis, basal cell carcinoma, Bowen's disease and solar keratosis. Tenascin expression in the upper dermis of normal skin was found to vary from almost absent to patchy along the basal membrane. Staining was continuous and intense around blood vessels, hair follicles and eccrine sweat ducts. In basal cell carcinoma a marked expression of tenascin was found in the tumour stroma, especially adjacent to the basal membrane surrounding the tumour cell nests. In Bowen's disease and solar keratosis, tenascin expression was found in the dermis next to the keratinocytes. In psoriasis the dermal papillae of clinically involved skin were intensely stained and a continuous band of tenascin was present in the upper dermis along the basal membrane. The distribution of tenascin differed from other known extracellular matrix components.

Elastase inhibiting activity (EIA) has been observed in normal skin as a response to surface trauma, immediately following the intra-epidermal accumulation of polymorphonuclear leukocytes (PMN). In order to elucidate the relation between EIA and inflammation, the inhibiting activity was assessed in skin samples of scaling dermatoses (a) without significant inflammation: erythrodermic autosomal recessive lamellar ichthyosis (EARLI), non-erythrodermic autosomal recessive lamellar ichthyosis (NEARLI), X-linked recessive ichthyosis (XLRI) and X-linked dominant chondrodysplasia punctata (XLD-CDP); (b) with predominantly mononuclear cell infiltration: atopic dermatitis; (c) with mixed infiltration of PMN and mononuclear cells: psoriasis and Netherton syndrome. All skin disorders investigated showed an increased EIA as compared with normal skin. Scales from psoriatic lesions, EARLI and Netherton syndrome showed a statistically significant increase in EIA above that observed in other monogenic disorders of keratinization NEARLI, XLRI XLD-CDP and above atopic dermatitis. EIA proved to be an indicator for abnormal keratinization with a marked expression when a mixed infiltrate is present in the skin.

Introduction: Tenascin-X (TNX) is an extracellular matrix (ECM) glycoprotein, the absence of which in humans leads to a recessive form of Ehlers-Danlos syndrome (EDS), a group of inherited connective tissue disorders characterized by joint hypermobility, skin hyperextensibility, and tissue fragility. A mouse model of TNX-deficient type EDS has been used to characterize the dermatological, orthopedic, and obstetrical features. The growing insight in the clinical overlap between myopathies and inherited connective tissue disorders asks for a study of the muscular characteristics of inherited connective tissue diseases. Therefore, this study aims to define the muscular phenotype of TNX knockout (KO) mice. Materials and methods: We performed a comprehensive study on the muscular phenotype of these TNX KO mice, consisting of standardized clinical assessment, muscle histology, and gene expression profiling of muscle tissue. Furthermore, peripheral nerve composition was studied by histology and electron microscopy. Results: The main findings are the presence of mild muscle weakness, mild myopathic features on histology, and functional upregulation of genes encoding proteins involved in ECM degradation and synthesis. Additionally, sciatic nerve samples showed mildly reduced collagen fibril density of endoneurium. Discussion: The muscular phenotype of TNX KO mice consists of mild muscle weakness with histological signs of myopathy and of increased turnover of the ECM in muscle. Furthermore, mildly reduced diameter of myelinated fibers and reduction of collagen fibril density of endoneurium may correspond with polyneuropathy in TNX-deficient EDS patients. This comprehensive assessment can serve as a starting point for further investigations on neuromuscular function in TNX KO mice. [ABSTRACT FROM AUTHOR]

Psychological stressors might contribute to the severity of chronic inflammatory diseases such as psoriasis by dysregulating hypothalamic-pituitary-adrenal (HPA) axis activity. To evaluate the role of cortisol, a key component of the HPA axis, in reaction to psychological stress in patients with psoriasis. 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. 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. 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. [ABSTRACT FROM AUTHOR]

Background The antiprotease activity of cystatin M/E regulates skin barrier formation, as it inhibits the activity of cathepsin V, cathepsin L and legumain, thereby controlling the processing of transglutaminase 3. Misregulation of this pathway by unrestrained protease activity, as seen in cystatin M/E-deficient mice, leads to abnormal stratum corneum and hair follicle formation, and severe disturbance of skin barrier function. Objectives Our major aim was to make a quantitative analysis of the expression of all players of this pathway in the epidermis of patients with inflammatory skin diseases. A second aim was to determine if reconstructed human skin could be used as an in vitro model system to investigate this pathway. Methods Autopsy material from normal human tissues, biopsies from normal skin of healthy volunteers, and lesional skin from patients with atopic dermatitis and psoriasis were used to study the expression of the above-mentioned molecules at the mRNA level by quantitative real-time polymerase chain reaction. Localization of the protein was performed by immunofluorescence microscopy, and expression was quantitated by image analysis. Results In skin, cystatin M/E is expressed at relatively higher levels than its target proteases, when compared with other tissues, which emphasizes its prominent role in cutaneous biology. We found decreased expression of cystatin M/E and cathepsin V in lesional atopic dermatitis and psoriasis epidermis at the mRNA level as well as the protein level. Cathepsin L and transglutaminase 3 were increased at the transcriptional level; however, this was not reflected by higher protein levels. Interestingly, the expression of all these molecules in reconstructed skin was qualitatively and quantitatively similar to the in vivo situation. Conclusions Disturbance of the cystatin M/E – cathepsin pathway could contribute to the dysregulated skin barrier function observed in inflammatory dermatoses. Human reconstructed skin appears to be a valuable model to study this novel biochemical pathway in vitro. [ABSTRACT FROM AUTHOR]

Background There is increasing evidence that stressors contribute to the severity of chronic inflammatory diseases such as psoriasis. However, much less is known about possible individual differences between patients in their stress reactivity, particularly the role of cognitive and behavioural factors, such as the role of worrying or scratching behaviour, in reaction to itch. Objectives To investigate the direct and moderating role of individual stress reactivity factors, particularly of cognitive and behavioural patterns of worrying and scratching, on the relationship between daily stressors and changes in disease severity [Psoriasis Area and Severity Index (PASI)] and itch in patients with psoriasis. Methods Patients were followed for 6 months through monthly clinical and self-reported measures of daily stressors, itch, disease severity and individual reactivity factors. Data from 62 patients were suitable for analysis. Results Cognitive and behavioural patterns of worrying and scratching were both independently related to an increase 4 weeks later in disease severity (PASI) and itch, at moments when patients experienced a high level of daily stressors. At these moments, stressors also interacted with vulnerability factors, showing that patients with more daily stress and high worrying and scratching had particularly worsened disease severity and itch. Conclusions Patients with high levels of worrying and scratching are most vulnerable to the impact of stressors on their psoriasis, particularly at highly stressful periods. [ABSTRACT FROM AUTHOR]

Keratinocytes of inflamed epidermis (psoriasis, wound healing) are hyperproliferative and display an abnormal differentiation programme. This regenerative differentiation pathway is characterized by the induction of genes that are not expressed by keratinocytes in normal skin, such as the cytokeratins CK6, CK16, CK17, and the proteinase inhibitor SKALP/¶elafin. In the study reported here we investigated the induction and regulation of SKALP expression as a marker for regenerative differentiation in epidermal keratinocytes. Various cytokines and growth factors known to be present in psoriatic epidermis were examined for their ability to induce SKALP gene expression in cultured human keratinocytes. Tumour necrosis factor-alpha (TNF-α) and serum were found to be potent inducers of SKALP expression at both the mRNA and the protein levels. SB202190 or SB203580, two specific p38 MAP kinase inhibitors almost completely blocked the induction of SKALP expression by TNF-α and serum. These results suggest that in keratinocytes, p38 activity is crucial for the induction of SKALP gene expression. These findings could be relevant for the elucidation of the mechanisms involved in normal and disturbed epidermal differentiation. [ABSTRACT FROM AUTHOR]

Impetigo herpetiformis (IH) is a rare pustular dermatosis with unknown aetiology, typically occurring during pregnancy. Based upon a similar clinical and histological presentation, i.e. spongiform accumulation of polymorphonuclear leucocytes in the stratum corneum, several authors consider IH as a variant of generalized pustular psoriasis (GPP), while others state that IH is a separate entity. Skin-derived antileucoproteinase (SKALP) is a strong and specific inhibitor of human leucocyte elastase (HLE) and proteinase 3, two neutral proteinases that have been implicated in leucocyte migration and tissue destruction. Previously, we reported decreased SKALP activity in pustular forms of psoriasis compared with plaque psoriasis. In this study we present a case study of a patient with IH, where SKALP activity was measured using biochemical and immunochemical techniques. Epidermal scales and sera were collected during the course of the disease. Comparison was made with three patients with GPP and six patients with plaque psoriasis. Initially, anti-HLE activity in epidermal scales of the patient with IH was comparable with values in patients with GPP, i.e. decreased compared with plaque psoriasis. During the course of the disease, anti-elastase activity dropped to undetectable levels, concomitant with the appearance of free elastase activity. This finding suggests a total saturation of epidermal anti-HLE activity. Low levels of SKALP. presumably complexed with HLE, could be measured immunochemically in scale extracts. Serum levels of total SKAEP correlated with the disease activity. We suggest that a reduced amount of epidermal SKAEP contributes to an imbalance between elastase and its inhibitor, resulting in the formation of epidermal pustules. This mechanism of pustule formation could apply both to GPP and IH, suggesting a final common pathway in the pathogenic mechanisms of IH and GPP. [ABSTRACT FROM AUTHOR]

The distribution of three (recently discovered) extracellular matrix components (tenascin, biglycan and decorin) was studied in normal adult human skin and in a number in monogenic disorders of keratinization, using immunohistology. The expression of tenascin, which is sparsely distributed in normal human dermis, was found to he grossly increased in epidermolytic hyper keratoses and in Darier's disease. Tenascin expression in three types of ichthyosis (X-linked recessive ichthyosis, autosomal dominant ichthyosis vulgaris, non-erythrodermic lamellar ichthyosis) was similar to that of normal skin. The presence of biglycan and decorin did not show a marked variation between the different disorders studied, suggesting that their expression is subject to regulatory mechanisms distinct from those of tenascin. The increased expression of tenascin in two disorders of keratinization with a hyper proliferative phenotype, lends further support to the hypothesis that dermal tenascin expression is increased as a result of epidermal hyperproliferation. [ABSTRACT FROM AUTHOR]

Elastase inhibiting activity (EIA) was demonstrated in the epidermis from lesions and in psoriatic scale, whereas normal epidermis did not contain significant EIA. Two new elastase inhibitors were partially purified and characterized using psoriatic scale as a source. The two species (approximate molecular weights 10 and 20 kDa) were shown to be stable, and high-affinity inhibitors of human leucocyte elastase (Ki < 10-10 M). No activity against human cathepsin G could be demonstrated. Cultured human keratinocytes were shown to contain EIA activity similar to that found in psoriatic scale. EIA could also be demonstrated in human epidermis following the induction of an experimental inflammatory response by sellotape-stripping. We propose the acronym SKALP (skin-derived antileucoprotease) as a name for these new proteinase inhibitors. [ABSTRACT FROM AUTHOR]

We report an investigation of peripheral blood polymorphonuclear leukocytes (PMN) from untreated patients with mild, quiescent psoriasis. Four aspects of the ‘metabolic burst’ were measured to illustrate phagocytosis-related events. These were: myeloperoxidase activity, hydrogen peroxide release, superoxide production and luminol-amplified chemiluminescence. Our study does not support the concept of an intrinsic abnormality of the PMN in psoriasis, but provides additional evidence for disease activity-dependent changes in phagocytic behaviour. Possible interactions with certain humoral factors, the so-called opsonins, are discussed. [ABSTRACT FROM AUTHOR]

Two new elastase inhibitors (SKALP, skin-derived antileucoproteases) were recently described in the lesional skin in psoriasis. The present study investigated the distribution of SKALP activity in the marginal zone of spreading psoriatic plaques. In a 4-mm zone immediately adjacent to the erythematosquamous plaques, SKALP activity was slightly increased compared to distant uninvolved skin. Within the lesion the anti-elastase activity was pronounced, but was significantly higher in the central zone of the plaque compared to the periphery. The appearance of SKALP in the psoriatic lesion appears to be a late event compared to endothelial involvement, intraepidermal accumulation of PMNs, epidermal proliferation and abnormal keratinization. This observation lends further support for the hypothesis that the induction of anti-elastase activity is associated with the off-switch of cutaneous inflammation. [ABSTRACT FROM AUTHOR]