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Objective: Many severe acute respiratory infections are caused by viral pathogens, and viruses are responsible for a large number of deaths worldwide. Among the most common respiratory viruses are the influenza A virus (IAV) and, more recently, the SARS-CoV-2 that emerged in 2019 and caused the most significant human pandemic of the beginning of the 21st century. Both IAV and SARS-CoV-2 share clinical features and a common transmission route through the emission of viral particles via aerosols and droplets. These penetrate the host after entry from the nose and mouth or an indirect mode of transmission via contact contamination of different media. These facts prompted us to investigate the possibility of designing a soft cream with a virucidal activity targeted against IAV and SARS-CoV-2. Methods: We first investigated the action of chemical compounds known to have antiviral properties such as cyclodextrin, or algae extracts containing sulfated polysaccharides, on cultured cells infected with lentiviral viral particles pseudotyped (VP) with either proteins HA (hemagglutinin) and NA (neuraminidase) from IAV or the G protein from the vesicular stomatitis virus or spike-bearing particles in order to select molecules with antiviral activities in human embryonic kidney (HEK293T) cells. Results: Our results show that some cyclodextrin-containing creams can significantly reduce the stability of HANA- and spike-bearing particles when they are applied prior to challenge with a viral inoculum on skin. Conclusions: We observed some specificities of these creams towards either IAV or SARS-CoV-2, indicating that the neutralization of viral activity is correlated with the mechanism of receptor interaction and entry of these two pathogens. [ABSTRACT FROM AUTHOR]

Background: Aframomum sp. is a genus of plants in the Zingiberaceae family. It includes several species, some of which are used in cosmetics for their various properties, making them useful in skincare products, particularly for anti-aging, moisturizing, and brightening the skin. However, to date, there is no experimental evidence on its natural extracts obtained or modified using microorganisms (biofermentation) as an anti-aging agent. Objective: The present study aimed to evaluate the antiaging effect of a Biofermented Aframomum angustifolium (BAA) extract on 3D bioprinted skin equivalent. Methods: The consortium of microorganisms contained Komagataeibacter, Gluconobacter, Acetobacter, Saccharomyces, Torulaspora, Brettanomyces, Hanseniaspora, Leuconostoc, Lactobacillus, Schizosaccharomyces. It was developed on a media containing water, sugar, and infused black tea leaves. The seeds of Aframomum angustifolium previously grounded were mixed with the culture medium, and the ferments in growth; this fermentation step lasted 10 days. Then, the medium was collected and filtered (0.22 µm) to obtain the BAA extract. To enhance our comprehension of the impact of BAA extract on skin aging, we developed skin equivalents using bio-printing methods with the presence or absence of keratinocyte stem cells (KSC). These skin equivalents were derived from keratinocytes obtained from both a middle-aged donor, with and without KSC. Moreover, we examined the effects of treating the KSC-depleted skin equivalents with Bio-fermented Aframomum angustifolium (BAA) extract for 5 days. Skin equivalents containing KSC-depleted keratinocytes exhibited histological characteristics typical of aged skin and were compared to skin equivalents derived from young donors. Results: The BAA extract contained specific organic acids such as lactic, gluconic, succinic acid and polyphenols. KSC-depleted skin equivalents that were treated with BAA extract exhibited higher specular reflection, indicating better hydration of the stratum corneum, higher mitotic activity in the epidermis basal layer, improved dermal-epidermal connectivity, and increased rigidity of the dermalepidermal junction compared to non-treated KSC-depleted equivalents. BAA extract treatments also resulted in changes at the dermis level, with an increase in total collagen and a decrease in global laxity, suggesting that this extract could help maintain youthful-looking skin. Conclusion: In summary, our findings indicated that BAA extract treatments have pleiotropic beneficial effects on skin equivalents and that the bio-fermentation provides new biological activities to this plant. [ABSTRACT FROM AUTHOR]

Objective: This study explored the impact of a black tea extract obtained through (plant small RNA) PSRTM technology, characterized by its abundance of small molecules, particularly citric acid—an antioxidant and tricarboxylic acid (TCA) cycle contributor—on mitochondrial health. The primary focus was to assess whether this extract could counteract reactive oxygen species (ROS)-induced mitochondrial alterations associated with aging, which lead to impaired mitochondrial function, reduced ATP production, and increased ROS generation. Methods: The PSRTM extraction method was employed to obtain a high content of polyphenols and small molecules, particularly citric acid. Results: In comparison with a conventional extract, the PSRTM extract demonstrated significant enhancements in aconitase activity, an ROS-sensitive enzyme in the TCA cycle, as well as basal respiration and ATP synthesis in fibroblast cells and skin biopsies. Moreover, the PSRTM extract effectively reduced ROS production by safeguarding this critical enzyme within the Krebs cycle and displayed superior capabilities in scavenging free radicals when exposed to UV-induced stress. When administered post-UV exposure, the PSRTM extract protected nuclear DNA by reducing the formation of cyclobutane pyrimidine dimers (CPDs) and promoting DNA repair mechanisms. Furthermore, the extract exhibited beneficial effects on the extracellular matrix, characterized by a reduction in matrix metalloprotease 1 (MMP1) and an increase in fibrillin 1 expression. Conclusions: These findings collectively suggest that the PSRTM extract holds promising antiaging potential, potentially functioning as a mitochondrial nutrient/protector due to its multifaceted benefits on mitochondrial function, nuclear DNA integrity, and the extracellular matrix. [ABSTRACT FROM AUTHOR]

In the interfollicular epidermis (IFE), stem cells (KSC) generate transit amplifying (TA) cells that, after symmetric divisions, produce differentiating daughters. Here, we isolated and characterized the highly proliferative interfollicular epidermal basal cell population "early" TA (ETA) cells, based on their capacity to adhere to type IV collagen. Proliferation and colony-forming efficiency in ETA cells are lower than in KSC but higher than in "late" TA (LTA). Stemness, proliferation, and differentiation markers confirmed that ETA cells display a unique phenotype. Skin reconstructs derived from ETA cells present different features (epidermal thickness, Ki67, and Survivin expression), as compared to skin equivalents generated from either KSC or LTA cells. The low-affinity neurotrophin receptor CD271, which regulates the KSC to TA cell transition in the human epidermis through an on/off switch control mechanism, is predominantly expressed in ETA cells. Skin equivalents generated from siRNA CD271 ETA cells display a more proliferative and less differentiated phenotype, as compared to mock-derived reconstructs. Consistently, CD271 overexpression in LTA cells generates a more proliferative skin equivalent than mock LTA cells. Finally, the CD271 level declines with cellular senescence, while it induces a delay in p16INK4 expression. We conclude that ETA cells represent the first KSC progenitor with exclusive features. CD271 identifies and modulates ETA cells, thus participating in the early differentiation and regenerative capacity of the human epidermis. [ABSTRACT FROM AUTHOR]

Reconstructed human epidermis equivalents (RHE) have been developed as a clinical skin substitute and as the replacement for animal testing in both research and industry. KiPS, or keratinocytes derived from induced pluripotent stem cells (iPSCs) are frequently used to generate RHE. In this study, we focus on the mitochondrial performance of the KiPS derived from iPSCs obtained from two donors. We found that the KiPS derived from the older donor have more defective mitochondria. Treatment of these KiPS with a plant extract enriched in compounds known to protect mitochondria improved mitochondrial respiration and rendered them fully competent to derive high-quality RHE. Overall, our results suggest that improving mitochondrial function in KiPS is one of the key aspects to obtain a functional RHE and that our plant extracts can improve in this process. [ABSTRACT FROM AUTHOR]

Skin pigmentation is directed by epidermal melanin units, characterized by long-lived and dendritic epidermal melanocytes ( MC) that interact with viable keratinocytes ( KC) to contribute melanin to the epidermis. Previously, we reported that MC: KC contact is required for melanosome transfer that can be enhanced by filopodi, and by UVR/ UVA irradiation, which can upregulate melanosome transfer via Myosin X-mediated control of MC filopodia. Both MC and KC express Ca2+-dependent E-cadherins. These homophilic adhesion contacts induce transient increases in intra- KC Ca2+, while ultraviolet radiation ( UVR) raises intra- MC Ca2+ via calcium-selective ORAI1 ion channels; both are associated with regulating melanogenesis. However, how Ca2+ triggers melanin transfer remains unclear. Here we evaluated the role of E-cadherin in UVR-mediated melanin transfer in human skin cells. MC and KC in human epidermis variably express filopodia-associated E-cadherin, Cdc42, VASP and β-catenin, all of which were upregulated by UVR in human MC in vitro. Knockdown of E-cadherin revealed that this cadherin is essential for UVR-induced MC filopodia formation and melanin transfer. Moreover, Ca2+ induced a dose-dependent increase in filopodia formation and melanin transfer, as well as increased β-catenin, Cdc42, Myosin X and E-cadherin expression in these skin cells. Together, these data suggest that filopodial proteins and E-cadherin, which are upregulated by intracellular ( UVR-stimulated) and extracellular Ca2+ availability, are required for filopodia formation and melanin transfer. This may open new avenues to explore how Ca2+ signalling influences human pigmentation. [ABSTRACT FROM AUTHOR]

Intracellular autophagy (AP) is a stress response that is enhanced under conditions of limitation of amino acids, growth factors and other nutrients, and also when macromolecules become damaged, aggregated and fibrillated. Aging is generally accompanied by an increase in intracellular stress due to all the above factors. Therefore, we have compared the basal levels of AP in serially passaged human facial skin fibroblasts undergoing aging and replicative senescence in vitro, and ex vivo in the skin biopsies from the photo-protected and photo-exposed area of the arms of 20 healthy persons of young and old ages. Immunofluorescence microscopy, employing antibodies against a specific intracellular microtubule-associated protein-1 light chain-3 (LC3) as a well established marker of AP, showed a 5-fold increase in the basal level of LC3 in near senescent human skin fibroblasts. However, no such age-related increase in LC3 fluorescence and AP could be detected in full thickness skin sections from the biopsies obtained from 10 healthy young (age 25 to 30 yr) and 10 old (age 60 to 65 yr) donors. Furthermore, there was no difference in the basal level of LC3 in the skin sections from photo-protected and photo-exposed areas of the arm. Thus, in normal conditions, the aging phenotype of the skin cells in culture and in the body appears to be different in the case of AP. [ABSTRACT FROM AUTHOR]

The article discusses the relation between autonomic nervous system activity and skin ageing. Topics discussed include evaluating the heart rate variability and skin ageing, measuring of the heart rate variability (HRV) parameters, association between skin wrinkles and ANS function and decrease in the activity of sensory cutaneous nerves.

Repeated exposure to mild heat shock (HS) has been shown to induce a wide range of health promoting hormetic effects in various biological systems, including human cells undergoing aging in vitro. In order to understand how cells distinguish between mild and severe stress, we have investigated the extent of early and immediate HS response by analyzing the nuclear translocation of the transcription factor heat shock factor-1 (HSF1), in serially passaged normal adult human facial skin fibroblasts exposed to mild (41 °C) or severe (43 °C) HS. Cells respond differently when exposed to mild and severe HS at different passage levels in terms of the extent of HSF1 translocation. In early passage young cells there was a 5-fold difference between mild and severe HS in the extent of HSF1 translocation. However, in near senescent late passage cells, the difference between mild and severe stress in terms of the extent of HSF1 translocation was reduced to less than 2-fold. One of the reasons for this age-related attenuation of heat shock response is due to the fact there was a higher basal level of HSF1 in the nuclei of late passage cells, which is indicative of increased intrinsic stress during cellular aging. These observations are consistent with previously reported data that whereas repeated mild stress given at younger ages can slow down aging and increase the lifespan, the same level of stress given at older ages may not provide the same benefits. Therefore, elucidating the early and immediate steps in the induction of stress response can be useful in deciding whether a particular level of stress is potentially hormetically beneficial or not. [ABSTRACT FROM AUTHOR]

Skin aging is the result of intrinsic chronological aging and photoaging, due to UV exposure, that both share important histological modifications and molecular features, including alterations of proteins. One of the main damage is glycation that occurs when reducing sugars react non-enzymatically with proteins. This reaction also happens when the dicarbonyl compounds GO (glyoxal) and MG (methylglyoxal), which are glucose derivatives, react with proteins. These compounds can be detoxified by the glyoxalase system composed of two enzymes, Glo1 (glyoxalase I) and Glo2 (glyoxalase II). The aims of the present mini-review are to briefly summarize our current knowledge of the biological roles of these enzymes in aging and then discuss the relevance of studying the role of glycation and of detoxifying systems in human skin aging. [ABSTRACT FROM AUTHOR]

Skin acts as a barrier between the environment and internal organs and performs functions that are critical for the preservation of body homeostasis. In mammals, a complex network of circadian clocks and oscillators adapts physiology and behavior to environmental changes by generating circadian rhythms. These rhythms are induced in the central pacemaker and peripheral tissues by similar transcriptional-translational feedback loops involving clock genes. In this work, we investigated the presence of functional oscillators in the human skin by studying kinetics of clock gene expression in epidermal and dermal cells originating from the same donor and compared their characteristics. Primary cultures of fibroblasts, keratinocytes, and melanocytes were established from an abdominal biopsy and expression of clock genes following dexamethasone synchronization was assessed by qPCR. An original mathematical method was developed to analyze simultaneously up to nine clock genes. By fitting the oscillations to a common period, the phase relationships of the genes could be determined accurately. We thereby show the presence of functional circadian machinery in each cell type. These clockworks display specific periods and phase relationships between clock genes, suggesting regulatory mechanisms that are particular to each cell type. Taken together, our data demonstrate that skin has a complex circadian organization. Oscillators are present not only in fibroblasts but also in epidermal keratinocytes and melanocytes and are likely to act in coordination to drive rhythmic functions within the skin. [ABSTRACT FROM AUTHOR]

Cathepsin S (catS), which is expressed in normal human keratinocytes and localized close to the dermal-epidermal junction (DEJ) degrades some of major basement membrane (BM) constituents. Among them, catS readily hydrolyzed in a time and dose dependent manner human nidogen-1 (nid-1) and nidogen-2, which are key proteins in the BM structure. CatS preferentially cleaved nid-1 at both acid and neutral pH. Hydrolysis of nid-1 was hampered in murine ctss-/- spleen lysates pretreated with inhibitors of other classes of proteases. Nid-1 was cleaved within its G2 and G3 globular domains that are both involved in interactions with other BM components. Binding assays with soluble and immobilized ligands indicated that catS altered the formation of complexes between nid-1 and other BM components. Assuming that the cleavage of nid-1 impairs its ability to crosslink with BM partners and perturbs the viscoelastic properties of BM matrix, these data indicate that catS may participate in BM proteolysis, in addition to already identified proteases. [ABSTRACT FROM AUTHOR]

Transfer of the melanocyte-specific and lysosome-related organelle, the melanosome, from melanocytes to keratinocytes is crucial for the protection of the skin against harmful ultraviolet radiation (UVR)--our main physiological cutaneous stressor. However, this commonplace event remains a most enigmatic process despite several early hypotheses. Recently, we and others have proposed a role for filopodia in melanin transfer, although conclusive experimental proof remained elusive. Using known filopodial markers (MyoX/Cdc42) and the filopodial disrupter, low-dose cytochalasin-B, we demonstrate here a requirement for filopodia in melanosome transfer from melanocytes to keratinocytes and also, unexpectedly, between keratinocytes. Melanin distribution throughout the skin represents the key phenotypic event in skin pigmentation. Melanocyte filopodia were also necessary for UVR-stimulated melanosome transfer, as this was also inhibited by MyoX knockdown and low-dose cytochalasin-B. Knockdown of keratinocyte MyoX protein, in its capacity as a phagocytosis effector, resulted in the inhibition of melanin uptake by keratinocytes. This indicates a central role for phagocytosis by keratinocytes of melanocyte filopodia. In summary, we propose a new model for the regulation of pigmentation in human skin cells under both constitutive and facultative (post-UVR) conditions, which we call the "filopodial-phagocytosis model." This model also provides a unique and highly accessible way to study lysosome-related organelle movement between mammalian cells. [ABSTRACT FROM AUTHOR]

The article focuses on the study for examining role of glyoxalase system (GLO) in epidermis and its regulation during aging and photoageing. Topics include skin aging associated to molecular damage due to protein alteration, producing advanced glycation endproducts (AGE) by reaction of methylglyoxal (MG) and dicarbonyl compounds glyoxal (GO) and involvement of glyoxalases in detoxification of GO and MG. Other topics include GLO enzymes helping progenitor cells to fight against oxidative stress.

Melanosomes are melanocyte-specific lysosome-related organelles that are transferred to keratinocytes of the epidermis and anagen hair bulb. Transferred melanin forms supra-nuclear caps that protect epidermal keratinocytes against UV irradiation. The mechanism(s) responsible for melanosome transfer into keratinocytes and their subsequent intra-keratinocyte distribution has long remained one of the most enigmatic of heterotypic cell interactions. Although there have been many attempts to study this process, significant progress has been hindered by the absence of an adequate in vitro model. During our ongoing study of melanocyte–keratinocyte interactions in skin and hair follicle, we have developed a novel in vitro assay that exploits the specificity of Silv/Pmel17/gp100 expression for melanosome/melanin granules. Using matched cultures of keratinocytes and melanocytes isolated from normal healthy epidermis together with double immunofluorescence, we have determined that gp100 is a surprisingly useful tracker of transferred melanin. Moreover, transferred gp100 stained melanin granules emit a bright fluorescence signal, facilitating ready quantification of melanin transfer levels between melanocytes and keratinocytes. This quantitative approach was validated using known inducers and inhibitors of the melanocyte phenotype. This assay further confirmed that cytophagocytosis of melanocyte components (e.g. dendrite tips) by keratinocytes is one route for melanin incorporation into keratinocytes. Lastly, a role for the recently proposed filopodium as a direct conduit for melanin transfer was substantiated using this novel approach. In conclusion, this assay promises to significantly aid our investigations of the molecular basis of melanosome transfer and offers a new tool for the clinical evaluation of melanocyte modulators. [ABSTRACT FROM AUTHOR]

Cellular aging is characterized by the accumulation of oxidatively modified proteins that result, at least in part, from impaired degradation of abnormal proteins. The proteasome is the major intracellular proteolytic system implicated in the removal of abnormal and oxidized proteins. In human epidermal cells, previous studies have evidenced that proteasome function is decreased during aging as well as upon UV irradiation, which is the main component of photoaging. The age-related decline of proteasome activity has been reported to be due to either or both decreased proteasome subunits expression and content, inactivation upon alteration of proteasome subunits, and accumulation of endogenous inhibitors, such as highly oxidized and cross-linked proteins. To gain further insight in the mechanisms that might be implicated in the decreased activity of the proteasome upon photoaging, purified 20S human proteasome has been exposed to UVA- and UVB-irradiation. The effect of such an irradiation on proteasome peptidase activities has been monitored and shown to promote a stimulation or an inhibition of the peptidase activities depending on whether the proteasome is under its latent or a nonphysiological active form. Analysis of the patterns of proteasome subunits by 2D gel electrophoresis has revealed modification for several subunits for UV-irradiated proteasome only in its irreversibly activated form, compared with nonirradiated and irradiated latent forms, indicating that the 20S proteasome is rather resistant to UV irradiation. [ABSTRACT FROM AUTHOR]

Senile lentigo (SL) is a common component of photoaged skin. It is characterized by hyperpigmented macules which affect chronically irradiated skin mostly after 50 years of age. This study was undertaken to assess the basic morphology of SL on dorsum of hands. A systematic comparison between lesional vs. perilesional skin using immunohistochemistry and electron microscopy was done to detect precursor lesions of SL and to determine whether melanocytes or keratinocytes were first affected in the evolution of lesions. In 12 cases studied, the main findings show that clusters of perilesional keratinocytes accumulate melanin in large melanosomial complexes, and that melanocytes counts are increased respective to total length of section in lesional skin, but the increment is probably due to the development of characteristic epidermal rete ridges. Melanocytes had overall a normal ultrastructure, with mostly quiescent features in perilesional skin and melanosomial transport seeming more active in lesional skin. Our data indicate that SL may represent a loss of epidermal melanin unit homeostasis due to chronic irradiation, where keratinocytic changes predominate over melanocytic changes. We hypothesize that abnormal pigment retention in keratinocytes is the primary defect in SL, which may partly explain the therapeutic effect of retinoids. Cario-Andre M, Lepreux S, Pain C, Nizard C, Noblesse E, Taïeb A. Perilesional vs. lesional skin changes in senile lentigo. [ABSTRACT FROM AUTHOR]

Modification of proteins by reactive oxygen species is implicated in different disorders. The proteasome is a multicatalytic proteinase in charge of intracellular protein turnover and of oxidized proteins degradation. Consequently, proteasome function is very important in controlling the level of altered proteins in eukaryotic cells. Evidence for a decline in proteasome activity during skin photo-aging has been provided in Bulteau et al. in 2002. The ability of a lipid algae extract (Phaeodactylum tricornutum) to stimulate 20S proteasome peptidase activities was described by Nizard et al. in 2001. Furthermore, keratinocytes treated with Phaeodactylum tricornutum extract and then UVA and UVB irradiated, exhibited a sustained level of proteasome activity comparable to the one of nonirradiated cells. The level of modified proteins can be quantified by measurement of protein carbonyl content (Oxyblot technique), which has been shown to increase with aging and other disorders. In this paper, it is described that, in the presence of this lipid algae extract, the level of oxidized proteins is reduced, as assessed by the Oxyblot technique. These results are obtained both with culture of human keratinocytes and stratum corneum skin cells (obtained by stripping) from human volunteers. Altogether, these results argue for the presence of compounds in this algae extract that have a stimulating and/or protective effect on proteasome activity, resulting in a decreased level of protein oxidation. [ABSTRACT FROM AUTHOR]

Heat shock protein (HSP) 47 is a specific chaperone of procollagen. This heat shock protein is responsible for the correct three-dimensional organization of procollagen and its control-quality prior secretion. The aim of the study is to evaluate the level of HSP 47 in aged, photoaged, and senescent fibroblasts and its modulation by a plant extract (Salix alba). The level of HSP 47 and/or procollagen expression in fibroblasts was measured by real-time RT-PCR (mRNA transcripts) and by flow cytometry (immunochemistry technique for measurement of arbitrary fluorescence intensity). Immunochemistry techniques and confocal microscopy were used to visualize the cellular localization of HSP 47 and procollagen. These parameters were compared with different age donors, nonsenescent, and senescent fibroblasts. Fibroblasts were irradiated by a noncytotoxic dose of UVA (6 J/cm²), and HSP 47 level was evaluated. S. alba extract was tested for its capacity to modulate HSP 47 expression. Colocalization of HSP 47 and procollagen was shown by confocal microscopy, indicating that HSP 47 could play a role of procollagen molecular chaperone in the cellular model. It was also shown that the HSP 47 level is decreased in old-donor cells, senescent, and irradiated cells. This decrease can be modulated by a S. alba extract (polyphenols rich) in a dose-dependent manner. The evaluation of HSP 47 expression in the experimental conditions can lead to a new approach of aging and photoaging, pointing out the implication of this chaperone in these pathophysiologic phenomena. Modulation of HSP 47 expression by this family of molecules could be of cosmetic and/or dermatologic interest. [ABSTRACT FROM AUTHOR]

Ultraviolet A (UVA) (320-400 nm) radiation is known to cause cutaneous aging and skin cancer. We studied the effect of UVA (365 nm) radiation on the human epidermis by focusing on keratinocyte gap junction-mediated intercellular communication (GJIC). We observed a dose-dependent 10-fold decrease in GJIC induced by UVA in normal human keratinocytes. This decrease in GJIC was associated with time-dependent internalization of connexin43 (Cx43). UVA radiation also damaged the actin cytoskeleton, as shown by microfilament disappearance. Importantly, the decrease in GJIC was transient when keratinocytes were irradiated with 10 J/cm² UVA, with a return to baseline values after 8 h. Concomitantly, Cx43 was relocalized and the actin cytoskeleton was restored. UVA irradiation and 12-O-tetradecanoylphorbol 13-acetate (TPA) treatment activated protein kinase C and reduced GJIC. However, Cx43 localization and phosphorylation were differently regulated by the two treatmeats. This suggests that at least two different pathways may mediate the observed fall in GJIC. These findings identify keratinocyte GJIC as a new UVA target that might sensitize human skin to photoaging and cancer formation. [ABSTRACT FROM AUTHOR]