An In vitro Model for Bacterial Growth on Human Stratum Corneum.

The diversity and dynamics of the skin microbiome in health and disease have been studied recently, but adequate model systems to study skin microbiotas in vitro are largely lacking. We developed an in vitro system that mimics human stratum corneum, using human callus as substrate and nutrient source for bacterial growth. The growth of several commensal and pathogenic bacterial strains was measured for up to one week by counting colony-forming units or by quantitative PCR with strain-specific primers.

Perfusion Intensity Correlates with Expression Levels of Psoriasis-Related Genes and Proteins.

Background: Previous research revealed heterogeneity in the perfusion intensity within clinically homogenous-appearing plaques, without differences in erythema. In addition, an increased perfusion was found within the perilesional skin. This raises the question whether the heterogeneity in perfusion found both inside and outside a lesion influences the expression levels of genes and proteins involved in the pathogenesis of psoriasis.

Analysis of protein-protein interaction between late cornified envelope proteins and corneodesmosin.

Deletion of two members of the late cornified envelope (LCE) family, LCE3B and LCE3C (LCE3C_LCE3B-del), has been identified as risk factor for psoriasis with a possible role in skin barrier function. Moreover, genetic interaction between LCE3C_LCE3B-del and HLA-C*06, located in the psoriasis susceptibility regions 4 and 1 (PSORS4 and 1), has been reported in several populations. Because of high linkage disequilibrium between the PSORS1 genes HLA-C*06 and corneodesmosin (CDSN), both genes are potentially involved in psoriasis.

Genotype-phenotype correlations in a prospective cohort study of paediatric plaque psoriasis: lack of correlation between HLA-C*06 and family history of psoriasis.

This study aims to investigate associations between observed clinical parameters and known genetic risk factors of psoriasis in a well-defined prospective cohort of paediatric patients with plaque psoriasis (n = 151). Significant associations were found for paediatric-onset psoriasis with ERAP1 (p = 0.002), IL23R (p = 0.

Microbiome and skin diseases.

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.

Combination of pantothenamides with vanin inhibitors as a novel antibiotic strategy against gram-positive bacteria.

The emergence of resistance against current antibiotics calls for the development of new compounds to treat infectious diseases. Synthetic pantothenamides are pantothenate analogs that possess broad-spectrum antibacterial activity in vitro in minimal media. Pantothenamides were shown to be substrates of the bacterial coenzyme A (CoA) biosynthetic pathway, causing cellular CoA depletion and interference with fatty acid synthesis.

Skin microbiome imbalance in patients with STAT1/STAT3 defects impairs innate host defense responses.

Background: Chronic mucocutaneous candidiasis (CMC) and hyper-IgE syndrome (HIES) are primary immunodeficiencies mainly caused by mutations in STAT1 and STAT3, respectively. CMC and HIES patients have an increased risk for skin and mucosal infections with fungal pathogens and Staphylococcus aureus. However, it is unknown whether the genetic defects in these patients also affect the skin and mucosal microbiome, which in turn may influence host defense mechanisms.

Towards a role of interleukin-32 in atherosclerosis.

Background: IL-32 has been previously shown to promote inflammation in rheumatoid arthritis patients and to contribute to IL-1β-induced ICAM-1 as well as other proinflammatory cytokines synthesis in human umbilical endothelial cells (HUVECs). Given the high rate of atherosclerosis in RA, these observations suggest that IL-32 may be involved in the inflammatory pathways of atherosclerosis.

Methods: mRNA and protein levels of IL-32 were determined in human atherosclerotic arterial vessel wall tissue by quantitative real-time PCR and immunohistochemistry.

Coal tar induces AHR-dependent skin barrier repair in atopic dermatitis.

Topical application of coal tar is one of the oldest therapies for atopic dermatitis (AD), a T helper 2 (Th2) lymphocyte-mediated skin disease associated with loss-of-function mutations in the skin barrier gene, filaggrin (FLG). Despite its longstanding clinical use and efficacy, the molecular mechanism of coal tar therapy is unknown. Using organotypic skin models with primary keratinocytes from AD patients and controls, we found that coal tar activated the aryl hydrocarbon receptor (AHR), resulting in induction of epidermal differentiation.

Discovery of small molecule vanin inhibitors: new tools to study metabolism and disease.

Vanins are enzymes with pantetheinase activity and are presumed to play a role in the recycling of pantothenic acid (vitamin B5) from pantetheine. Pantothenic acid is an essential nutrient required to synthesize coenzyme A, a cofactor involved in many biological processes such as fatty acid synthesis and oxidation of pyruvate to fuel the citric acid cycle. Hydrolysis of pantetheine also liberates cysteamine, a known antioxidant.

Strong induction of AIM2 expression in human epidermis in acute and chronic inflammatory skin conditions.

Absent in melanoma 2 (AIM2) is a double-stranded DNA receptor, and its activation initiates an interleukin-1 beta processing inflammasome. AIM2 is implicated in host defense against several pathogens, but could hypothetically also contribute to autoinflammatory or autoimmune diseases, such as is the case for NLRP3. Using thoroughly characterised antibodies, we analysed AIM2 expression in human tissues and primary cells.

Cystatin M/E knockdown by lentiviral delivery of shRNA impairs epidermal morphogenesis of human skin equivalents.

The protease inhibitor cystatin M/E (CST6) regulates a biochemical pathway involved in stratum corneum homeostasis, and its deficiency in mice causes ichthyosis and neonatal lethality. Cystatin M/E deficiency has not been described in humans so far, and we did not detect disease-causing mutations in the CST6 gene in a large number of patients with autosomal recessive congenital ichthyosis, who were negative for mutations in known ichthyosis-associated genes. To investigate the phenotype of CST6 deficiency in human epidermis, we used lentiviral delivery of short hairpin RNAs that target CST6 in a 3D reconstructed skin model.

Microbiome dynamics of human epidermis following skin barrier disruption.

Background: Recent advances in sequencing technologies have enabled metagenomic analyses of many human body sites. Several studies have catalogued the composition of bacterial communities of the surface of human skin, mostly under static conditions in healthy volunteers. Skin injury will disturb the cutaneous homeostasis of the host tissue and its commensal microbiota, but the dynamics of this process have not been studied before.

Rho kinase inhibitor Y-27632 prolongs the life span of adult human keratinocytes, enhances skin equivalent development, and facilitates lentiviral transduction.

The use of tissue-engineered human skin equivalents (HSE) for fundamental research and industrial application requires the expansion of keratinocytes from a limited number of skin biopsies donated by adult healthy volunteers or patients. A pharmacological inhibitor of Rho-associated protein kinases, Y-27632, was recently reported to immortalize neonatal human foreskin keratinocytes. Here, we investigated the potential use of Y-27632 to expand human adult keratinocytes and evaluated its effects on HSE development and in vitro gene delivery assays.

Pattern recognition receptors in infectious skin diseases.

During the last decade, multiple pattern recognition receptors (PRRs) have been identified. These are involved in the innate immune response against a plethora of pathogens. However, PRR functioning can also be detrimental, even during infections.

Construction of a microstructured collagen membrane mimicking the papillary dermis architecture and guiding keratinocyte morphology and gene expression.

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.

Pattern recognition receptors in immune disorders affecting the skin.

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.

Type 2 helper T-cell cytokines induce morphologic and molecular characteristics of atopic dermatitis in human skin equivalent.

Both the immune system and the epidermis likely have an important role in the pathogenesis of atopic dermatitis (AD). The objective of the present study was to develop a human skin equivalent model exhibiting morphologic and molecular characteristics of AD in a controlled manner. Skin equivalents generated from normal adult human keratinocytes were stimulated with type 2 T-helper cell (Th2) cytokines IL-4 and IL-13, and morphologic features and gene expression of the epidermis were studied.

Psoriasis risk genes of the late cornified envelope-3 group are distinctly expressed compared with genes of other LCE groups.

Deletion of the late cornified envelope (LCE) genes LCE3B and LCE3C has recently been identified as a risk factor for psoriasis. Expression of 16 LCE genes of LCE groups 1, 2, 3, 5, and 6 was examined in vivo and in vitro. Quantitative PCR demonstrated that moderate to high LCE expression was largely confined to skin and a few oropharyngeal tissues.

Meta-analysis confirms the LCE3C_LCE3B deletion as a risk factor for psoriasis in several ethnic groups and finds interaction with HLA-Cw6.

A multicenter meta-analysis including data from 9,389 psoriasis patients and 9,477 control subjects was performed to investigate the contribution of the deletion of genes LCE3C and LCE3B, involved in skin barrier defense, to psoriasis susceptibility in different populations. The study confirms that the deletion of LCE3C and LCE3B is a common genetic factor for susceptibility to psoriasis in the European populations (OR(Overall) = 1.21 (1.

A genome-wide association study identifies new psoriasis susceptibility loci and an interaction between HLA-C and ERAP1.

To identify new susceptibility loci for psoriasis, we undertook a genome-wide association study of 594,224 SNPs in 2,622 individuals with psoriasis and 5,667 controls. We identified associations at eight previously unreported genomic loci. Seven loci harbored genes with recognized immune functions (IL28RA, REL, IFIH1, ERAP1, TRAF3IP2, NFKBIA and TYK2).