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Electronic textiles (e-textiles) are a branch of wearable technology based on integrating smart systems into textile materials creating different possibilities, transforming industries, and improving individuals' quality of life. E-textiles hold vast potential, particularly for use in personal protective equipment (PPE) by embedding sensors and smart technologies into garments, thus significantly enhancing safety and performance. Although this branch of research has been active for several decades now, only a few products have made it to the market. Achieving durability, reliability, user acceptance, sustainability, and integration into current manufacturing processes remains challenging. High levels of reliability and user acceptance are critical for technical textiles, such as those used in PPE. While studies address washing reliability and field tests, they often overlook end user preferences regarding smart textiles. This paper presents a narrow fabric-based e-textile system co-developed by engineers, garment and textiles' manufacturers, and firefighters. It highlights material choices and integration methods, and evaluates the system's reliability, sustainability, and user experience, providing comprehensive insights into developing and analyzing e-textile products, particularly in the PPE field.

The Reconstructed Human Epidermis (RHE) model derived from epidermal keratinocytes offers an ethical and scientific alternative to animal experimentation, particularly in cutaneous toxicology and dermatological research, where the elimination of animal cruelty is of paramount importance. Thus, we compared commercially available chemically defined animal origin-free (cdAOF) supplements, designed for regenerative medicine, to the widely utilized supplement (human keratinocyte growth supplement), which contains growth factors and bovine pituitary extract. Herein we present the extended characterization of RHE derived from newborn, adult, and immortalized N/telomerase reverse transcriptase keratinocytes under cdAOF conditions. Culture of RHE in the cdAOF media produced histological features that were similar to that produced using human keratinocyte growth supplement, with the exception that the basal keratinocytes were less cylindrical. Additionally, immunolocalization of involucrin in the basal layer and increased mRNA expression of several inflammatory-proliferative markers were observed under cdAOF conditions. In RHEs cultured in cdAOF media, expression and immunolocalization of other expected markers of keratinization were similar, while monitoring of barrier function (transepithelial electrical resistance) revealed results that were statistically equal to, or lower than those observed in RHE cultured in human keratinocyte growth supplement. Our study indicates that reconstruction of RHE was accomplished under cdAOF culture conditions and that further refinement could promote an expanded use beyond regenerative medicine, for in vitro toxicology applications., (© 2024 The Authors.)

Atopic dermatitis (AD) is a Th2-type inflammatory disease characterized by an alteration of epidermal barrier following the release of IL-4 and IL-13. These cytokines activate type II IL-4Rα/IL-13Rα1 receptors in the keratinocyte. Whilst IL-2Rγ, that forms type I receptor for IL-4, is only expressed in haematopoietic cells, recent studies suggest its induction in keratinocytes, which questions about its role. We studied expression of IL-2Rγ in keratinocytes and its role in alteration of keratinocyte function and epidermal barrier. IL-2Rγ expression in keratinocytes was studied using both reconstructed human epidermis (RHE) exposed to IL-4/IL-13 and AD skin. IL-2Rγ induction by type II receptor has been analyzed using JAK inhibitors and RHE knockout (KO) for IL13RA1. IL-2Rγ function was investigated in RHE KO for IL2RG. In RHE, IL-4/IL-13 induce expression of IL-2Rγ at the mRNA and protein levels. Its mRNA expression is also visualized in keratinocytes of lesional AD skin. IL-2Rγ expression is low in RHE treated with JAK inhibitors and absent in RHE KO for IL13RA1. Exposure to IL-4/IL-13 alters epidermal barrier, but this alteration is absent in RHE KO for IL2RG. A more important induction of IL-13Rα2 is reported in RHE KO for IL2RG than in not edited RHE. These results demonstrate IL-2Rγ induction in keratinocytes through activation of type II receptor. IL-2Rγ is involved in the alteration of the epidermal barrier and in the regulation of IL-13Rα2 expression. Observation of IL-2Rγ expression by keratinocytes inside AD lesional skin suggests a role for this receptor subunit in the disease., (© 2023 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

TSG-6 is a soluble protein secreted in the extracellular matrix by various cell types in response to inflammatory stimuli. TSG-6 interacts with extracellular matrix molecules, particularly hyaluronan (HA), and promotes cutaneous wound closure in mice. Between epidermal cells, the discrete extracellular matrix contains HA and a tiny amount of TSG-6. However, challenges imposed to keratinocytes in reconstructed human epidermis revealed strong induction of TSG-6 expression, after exposure to T helper type 2 cytokines to recapitulate the atopic dermatitis phenotype or after fungal infection that causes secretion of cytokines and antimicrobial peptides. After both types of challenge, enhanced release of TSG-6 happens simultaneously with increased HA production. TSG-6 deficiency in N/TERT keratinocytes was created by inactivating TNFAIP6 using CRISPR/Cas9. Some TSG-6 -/- keratinocytes analyzed through scratch assays tend to migrate more slowly but produce reconstructed human epidermis that exhibits normal morphology and differentiation. Few significant alterations were noticed by transcriptomic analysis. Nevertheless, reduced HA content in TSG-6 -/- reconstructed human epidermis was observed, along with enhanced HA release into the culture medium, and this phenotype was even more pronounced after the challenging conditions. Reintroduction of cells producing TSG-6 in reconstructed human epidermis reduced HA leakage. Our results show a role for TSG-6 in sequestering HA between epidermal cells in response to inflammation., (© 2021 The Authors.)

Inhibition of CYP450-mediated retinoic acid (RA) metabolism by RA metabolism blocking agents increases endogenous retinoids and is an alternative to retinoid therapy. Currently available RA metabolism blocking agents (i.e., liarozole and talarozole) tend to have fewer adverse effects than traditional retinoids but lack target specificity. Substrate-based inhibitor DX314 has enhanced selectivity for RA-metabolizing enzyme CYP26B1 and may offer an improved treatment option for keratinization disorders such as congenital ichthyosis and Darier disease. In this study, we used RT-qPCR, RNA sequencing, pathway, upstream regulator, and histological analyses to demonstrate that DX314 can potentiate the effects of all-trans-RA in healthy and diseased reconstructed human epidermis. We unexpectedly discovered that DX314, but not all-trans-RA or previous RA metabolism blocking agents, appears to protect epidermal barrier integrity. In addition, DX314-induced keratinization and epidermal proliferation effects are observed in a rhino mice model. Altogether, the results indicate that DX314 inhibits all-trans-RA metabolism with minimal off-target activity and shows therapeutic similarity to topical retinoids in vitro and in vivo. Findings of a barrier-protecting effect require further mechanistic study but may lead to a unique strategy in barrier-reinforcing therapies. DX314 is a promising candidate compound for further study and development in the context of keratinization disorders., (Copyright © 2020 The Authors. Published by Elsevier Inc. All rights reserved.)

Hyaluronan (HA) is synthesized by three HA synthases (HAS1, HAS2, and HAS3) and secreted in the extracellular matrix. In human skin, large amounts of HA are found in the dermis. HA is also synthesized by keratinocytes in the epidermis, although its epidermal functions are not clearly identified yet. To investigate HA functions, we studied the effects of HA depletion on human keratinocyte physiology within in vitro reconstructed human epidermis. Inhibition of HA synthesis with 4-methylumbelliferone (4MU) did not modify the expression profile of the epidermal differentiation markers involucrin, keratin 10, and filaggrin during tissue reconstruction. In contrast, when keratinocytes were incubated with 4MU, cell proliferation was decreased. In an attempt to rescue the proliferation function, HA samples of various mean molecular masses were added to keratinocyte cultures treated with 4MU. These samples were unable to rescue the initial proliferation rate. Furthermore, treatments with HA-specific hyaluronidase, although removing almost all HA from keratinocyte cultures, did not alter the differentiation or proliferation processes. The differences between 4MU and hyaluronidase effects did not result from differences in intracellular HA, sulfated glycosaminoglycan concentration, apoptosis, or levels of HA receptors, all of which remained unchanged. Similarly, knockdown of UDP-glucose 6-dehydrogenase (UGDH) using lentiviral shRNA effectively decreased HA production but did not affect proliferation rate. Overall, these data suggest that HA levels in the human epidermis are not directly correlated with keratinocyte proliferation and differentiation and that incubation of cells with 4MU cannot equate with HA removal., (© 2016 by The American Society for Biochemistry and Molecular Biology, Inc.)

This chapter provides methods suitable for the culture of primary human keratinocytes in serum-free culture conditions, starting from very small skin biopsies. It also explains procedures required for reconstruction of a stratified epidermis on polycarbonate filter, starting from keratinocytes cultured in serum-free conditions. Tissues reconstructed according to this method have been proven suitable for characterization of epidermal morphogenesis and for in vitro studies of the epidermal barrier. Utilization of the same method for successful isolation of keratinocytes from a patient suffering from Darier's disease and the reconstruction of a pathological epidermis which displays the same histological features as in vivo are also presented.