The effect of ingested copper on the structural and cytotoxic properties of Steatoda grossa (Theridiidae) spider silk.

Spiders, assigned to macroconcentrators of heavy metals, are particularly threatened by the toxic effects of these chemicals. Until now, it has not been specified to what extent metals alter the processes proceeding in silk glands and if such changes could consequently influence the chemical and structural properties of the spun web threads. In the present study selected biological properties of Steatoda grossa (Theridiidae) silk yarn after nutritional exposure to copper at sublethal doses (0.234 mM CuSO4) were assessed. It was determined both changes in ultrastructure of ampullate glands and hunting web's architecture as well the cytotoxic effect in model cells (fibroblasts: line ATCC® CCL-1 NCTC clone 929), that were in contact with the analyzed biomaterial. The exposure of spiders to copper caused the occurrence of apoptotic cells in the ampullate glands as well as a significant reduction in the diameter of single fibers in double and multiple connection complexes as compared with control. At both 24 and 72 h of incubation, intensification of apoptotic and necrotic processes was observed in the fibroblast cultures that were remaining in indirect contact with the webs produced by copper-contaminated individuals. In the case of fibroblasts in direct contact with silk from the copper group, a clear cytotoxic effect resulting in an increased frequency of necrosis was observed after 72 h of incubation. The results indicated that copper may change the biological properties of spider silk and compromise its biomaterial properties.

Nicotinamide Prevents UVB- and Oxidative Stress‒Induced Photoaging in Human Primary Keratinocytes.

Nicotinamide (NAM), a NAM adenine dinucleotide precursor, is known for its benefits to skin health. Under standard culture conditions, NAM delays the differentiation and enhances the proliferation of human primary keratinocytes, leading to the maintenance of stem cells. In this study, we investigated the effects of NAM on photoaging in two-dimensional human primary keratinocyte cultures and three-dimensional organotypic epidermal models. In both models, we found that UVB irradiation and hydrogen peroxide induced human primary keratinocyte premature terminal differentiation and senescence. In three-dimensional organotypics, the phenotype was characterized by a thickening of the granular layer expressing filaggrin and loricrin, but thinning of the epidermis overall. NAM limited premature differentiation and ameliorated senescence, as evidenced by the maintenance of lamin B1 levels in both models, with decreased lipofuscin staining and reduced IL-6/IL-8 secretion in three-dimensional models, compared to those in UVB-only controls. In addition, DNA damage observed after irradiation was accompanied by a decline in energy metabolism, whereas both effects were partially prevented by NAM. Our data thus highlight the protective effects of NAM against photoaging and oxidative stress in the human epidermis and pinpoint DNA repair and energy metabolism as crucial underlying mechanisms.

Niacinamide mitigates SASP-related inflammation induced by environmental stressors in human epidermal keratinocytes and skin.

OBJECTIVE: To evaluate whether niacinamide (Nam) can mitigate production of inflammatory and senescence-related biomarkers induced by environmental stressors. METHODS: Human epidermal keratinocytes were exposed to UVB, urban dust, diesel exhaust and cigarette smoke extract and treated with Nam or vehicle control. Full thickness 3-D skin organotypic models were exposed to a combination of UVB and PM2.5 and treated with Nam or vehicle control. Quantitation of the SASP-related inflammatory mediators PGE2 , IL-6 and IL-8 was performed on cultured media. UVB-exposed keratinocytes treated with and without Nam were immunostained for the senescence biomarker Lamin B1 (LmnB1). Transcriptomics profiling of cigarette smoke extract effects on keratinocytes was performed. A double-blind, placebo-controlled clinical was conducted on 40 female panellists that were pretreated on back sites for two weeks with 5% Nam or vehicle and then exposed to 1.5 minimal erythemal dose (MED) solar-simulated radiation (SSR). Treated sites were compared with non-treated exposed sites for erythema and the skin surface IL-1αRA/IL-1α inflammatory biomarkers. RESULTS: Ultraviolet B induced synthesis of PGE2 , IL-8 and IL-6 and reduced LmnB1 levels in keratinocytes. Urban dust and diesel exhaust only stimulated synthesis of IL-8 whereas cigarette smoke extract only stimulated levels of PGE2 . In all exposures, treatment with Nam significantly mitigated synthesis of the inflammatory mediators and restored levels of UVB-reduced LmnB1. In the 3D skin equivalent model, Nam reduced IL-8 levels stimulated by a combination of topical PM2.5 and UV exposure. In a UV challenge clinical, pretreatment with 5% Nam reduced erythema and skin surface IL-1αRA/IL-1α inflammatory biomarkers that were induced by SSR. CONCLUSION: Since it is known that Nam has anti-inflammatory properties, we tested whether Nam can inhibit environmental stress-induced inflammation and senescence-associated secretory phenotype (SASP) biomarkers. We show Nam can reduce PGE2 , IL-6 and IL-8 levels induced by environmental stressors. Additionally, in vivo pretreatment with Nam can reduce UV-induced erythema and skin surface inflammatory biomarkers. These findings add to the body of evidence that Nam can mitigate the skin's inflammatory response elicited by environmental stressors. This supports Nam can potentially inhibit senescence and premature ageing and thereby maintain skin's functionality and appearance.

OBJECTIF: Évaluer si le niacinamide (Nam) peut atténuer la production de biomarqueurs inflammatoireset liés à la sénescence induits par les facteurs de stress environnementaux. MÉTHODES: Leskératinocytes épidermiques H uman ont été exposés aux UVB, à la poussière urbaine, aux gaz d'échappement diesel et à l'extrait de fumée de cigarette et traités avec nam ou contrôle de véhicule. Les modèles organotypic de peau 3D de pleine épaisseur ont été exposés à une combinaison d'UVB et de PM2.5 et traités avec nam ou commande de véhicule. La quantitation des médiateurs inflammatoires liés à la SASP PGE2 ,IL-6 et IL-8 a été réalisée sur des médias cultivés. Les kératinocytes exposés aux UVB traités avec et sans Nam étaient immunotachés pour le biomarqueur de sénescence Lamin B1 (LmnB1). Le profilage de transcriptomique des effets d'extrait de fumée de cigarette sur les kératinocytes a été exécuté. Un placebo contrôlé clinique à double insu a été menée sur 40 panélistes féminins qui ont été prétraités sur les sites arrière pendant deux semaines avec 5% Nam ou véhicule, puis exposés à 1,5 dose erythémique minimale (MED) rayonnement solaire simulé (SSR). Les sites traités ont été comparés à des sites exposés non traités pour l'érythème et la surface de la peau IL-1▫RA/IL-1▫ biomarqueurs inflammatoiress. RÉSULTATS: Synthèse induite par UVB des niveaux de PGE2, IL-8 et IL-6 et réduit de LmnB1 dans les kératinocytes. La poussière urbaine et les gaz d'échappement diesel n'ont stimulé que la synthèse de l'IL-8 alors que l'extrait de fumée de cigarette ne stimulait que les niveaux de PGE2 . Dans toutes les expositions, le traitement avec Nam a significativement atténué la synthèse des médiateurs inflammatoires et les niveaux restaurés de LmnB1 UVB-réduit. Dans le modèle équivalent de la peau 3D, Nam a réduit les niveaux d'IL-8 stimulés par une combinaison de PM combination of topical PM 2.5 topique et d'exposition aux UV. Dans un uv-défi clinique, prétraitement avec 5% Nam réduit érythème et la surface de la peau IL-1▫RA/IL-1▫ biomarqueurs inflammatoires qui ont été induits par SSR. CONCLUSION: Puisqu'il est connu que Nam a des propriétés anti-inflammatoires, nous avons testé si Nam peut inhiber l'inflammation induite par le stressenvironnementaltion et les biomarqueurs sécrétoires sécrétoires sécrétoires (SASP) associés à la sénescence. We montrent Nam peut réduire PGE2 ,IL-6, et IL-8 niveaux induits par les facteurs de stress environnementaux. En outre, le prétraitement in vivo avec Nam peut réduire l'érythème induit par les UV et les biomarqueurs inflammatoires de surface de la peau. Ces résultats ajoutent à l'oody bde la preuve que Nam peut atténuer la réponse inflammatoire de la peau provoquée par lesfacteurs de stress environnementaux. Cela soutient Nam peut potentiellement inhiber la sénescence et le vieillissement prématuré et ainsi maintenir la fonctionnalité de la peau et l'apparence.