Barrier function-related genes and proteins have an altered expression in acne-involved skin.

BACKGROUND: Acne vulgaris provides a unique disease setting in which a prominent skin inflammation is coupled with the overproduction of lipid-rich sebum. OBJECTIVES: Our goal was to evaluate the expression of barrier molecules in papular acne skin samples obtained from untreated patients and compare those to the results of healthy and of papulopustular rosacea-involved ones at the mRNA and protein levels. In addition, we aimed to assess the effects of various sebum composing lipids on the expression of proteins involved in barrier formation in keratinocytes. METHODS: Available microarray data sets of papular acne and papulopustular rosacea-affected skin samples were re-analysed with a focus on epidermal barrier-related pathways. Immunohistochemistry was performed to detect barrier molecules in the interfollicular regions of human acne and healthy skin samples. Protein levels of barrier-related genes were measured by western blot in samples of HaCaT keratinocytes treated with selected lipids. RESULTS: Meta-analysis of whole transcriptome data sets revealed that barrier-related pathways are significantly affected in acne vulgaris skin samples. While an altered expression of key molecules in maintaining barrier functions such as filaggrin, keratin 1, involucrin, desmoglein 1, kallikrein 5 and 7, was also observed at the protein levels, our data demonstrated that sebum composing lipids may selectively modify the levels of epidermal barrier-related molecules. CONCLUSIONS: Our results suggest that although not as prominently as in the dry papulopustular rosacea skin, the epidermal barrier in the interfollicular region may be damaged also in the lipid-rich skin samples of papular acne. Furthermore, our findings indicating diverse regulatory effects of various sebum lipids on the expression of barrier molecules in keratinocytes suggest, that they may influence the moisturization of the skin as well. Altogether, our findings could have implications in the development of sebum-modulating anti-acne therapies and even in the care of symptom-free skin.

Epidermal Growth Factor Modulates Palmitic Acid-Induced Inflammatory and Lipid Signaling Pathways in SZ95 Sebocytes.

Epidermal growth factor (EGF) acts as a paracrine and autocrine mediator of cell proliferation and differentiation in various types of epithelial cells, such as sebocytes, which produce the lipid-rich sebum to moisturize the skin. However, sebum lipids via direct contact and by penetrating through the epidermis may have regulatory roles on epidermal and dermal cells as well. As EGF receptor (EGFR) is expressed throughout the proliferating and the lipid-producing layers of sebaceous glands (SGs) in healthy and acne-involved skin, we investigated the effect of EGF on SZ95 sebocytes and how it may alter the changes induced by palmitic acid (PA), a major sebum component with bioactive roles. We found that EGF is not only a potent stimulator of sebocyte proliferation, but also induces the secretion of interleukin (IL)6 and down-regulates the expression of genes involved in steroid and retinoid metabolism. Importantly, when applied in combination with PA, the PA-induced lipid accumulation was decreased and the cells secreted increased IL6 levels. Functional clustering of the differentially regulated genes in SZ95 sebocytes treated with EGF, PA or co-treated with EGF+PA further confirmed that EGF may be a potent inducer of hyperproliferative/inflammatory pathways (IL1 signaling), an effect being more pronounced in the presence of PA. However, while a group of inflammatory genes was up-regulated significantly in EGF+PA co-treated sebocytes, PA treatment in the absence of EGF, regulated genes only related to cell homeostasis. Meta-analysis of the gene expression profiles of whole acne tissue samples and EGF- and EGF+PA -treated SZ95 sebocytes showed that the EGF+PA co-activation of sebocytes may also have implications in disease. Altogether, our results reveal that PA-induced lipid accumulation and inflammation can be modulated by EGF in sebocytes, which also highlights the need for system biological approaches to better understand sebaceous (immuno)biology.

Factor XIII-A in Diseases: Role Beyond Blood Coagulation.

Multidisciplinary research from the last few decades has revealed that Factor XIII subunit A (FXIII-A) is not only involved in blood coagulation, but may have roles in various diseases. Here, we aim to summarize data from studies involving patients with mutations in the F13A1 gene, performed in FXIII-A knock-out mice models, clinical and histological studies assessing correlations between diseases severity and FXIII-A levels, as well as from in vitro experiments. By providing a complex overview on its possible role in wound healing, chronic inflammatory bowel diseases, athe-rosclerosis, rheumatoid arthritis, chronic inflammatory lung diseases, chronic rhinosinusitis, solid tumors, hematological malignancies, and obesity, we also demonstrate how the field evolved from using FXIII-A as a marker to accept and understand its active role in inflammatory and malignant diseases.