Skin aging, gene expression and calcium

Anti-ageing mechanism of topical bioactive ingredient composition on skin based on network pharmacology

OBJECTIVE

To elucidate the anti-ageing mechanism of the combination of eight ingredients on the skin from a multidimensional view of the skin.

METHODS

The target pathway mechanisms of composition to delay skin ageing were investigated by a network pharmacology approach and experimentally validated at three levels: epidermal, dermal, and tissue.

RESULTS

We identified 24 statistically significant skin ageing-related pathways, encompassing crucial processes such as epidermal barrier repair, dermal collagen and elastin production, inhibition of reactive oxygen species (ROS), as well as modulation of acetylcholine and acetylcholine receptor binding. Furthermore, our in vitro experimental findings exhibited the following outcomes: the composition promotes fibroblast proliferation and the expression of barrier-related genes in the epidermis; it also stimulated the expression of collagen I, collagen III, and elastic fibre while inhibiting ROS and β-Gal levels in HDF cells within the dermis. Additionally, Spilanthol in the Acmella oleracea extract contained in the composition demonstrated neuro-relaxing activity in Zebrafish embryo, suggesting its potential as an anti-wrinkle ingredient at the hypodermis level.

CONCLUSIONS

In vitro experiments validated the anti-ageing mechanism of composition at multiple skin levels. This framework can be extended to unravel the functional mechanisms of other clinically validated compositions, including traditional folk recipes utilized in cosmeceuticals.

Considerations for managing elderly patients with atopic dermatitis

INTRODUCTION

Atopic dermatitis (AD) diagnosis in elderly is challenging, due to its clinical polymorphism and the lack of diagnostic biomarkers. Moreover, the chronicity of the disease and the complex pathogenetic mechanism, make elderly AD management challenging.

AREAS COVERED

A narrative review of the current literature was performed using the PubMed, Medline, Embase, and Cochrane Skin databases, by researching the following terms: 'atopic dermatitis,' 'clinical phenotypes,' 'eczema,' 'elderly patients,' 'elderly type atopic dermatitis,' 'eczema clinical presentation.' The aim was to report the current knowledge on pathogenesis, clinical presentation, and treatment options of elderly AD.

EXPERT OPINION

Elderly type AD has recently been identified as a separate entity, with an increasing prevalence. With aging, both immunosenescence and barrier alterations can cause or modify AD presentation. Moreover, a chronic proinflammatory state (so-called 'inflammaging') is often present in elderly subjects. Older patients with AD may present with peculiar immunophenotypic profile, making AD diagnosis challenging. Similarly, the chronicity of the disease and the complex pathogenetic mechanism, make AD management a challenge. Indeed, systemic therapies for AD are often contraindicated or not tolerated and the management of elderly type AD is often burdened with numerous difficulties, leading to undertreated disease. Even if dupilumab and tralokinumab represent a valuable therapeutic weapon, more data on safety of JAK inhibitors are required.

Skin-protective biological activities of bio-fermented Aframomum angustifolium extract by a consortium of microorganisms

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 (bio-fermentation) as an anti-aging agent. Objective: The present study aimed to evaluate the antiaging effect of a Bio-fermented 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 dermal-epidermal 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.

N,N-Dimethylglycine Sodium Salt Exerts Marked Anti-Inflammatory Effects in Various Dermatitis Models and Activates Human Epidermal Keratinocytes by Increasing Proliferation, Migration, and Growth Factor Release

N,N-dimethylglycine (DMG) is a naturally occurring compound being widely used as an oral supplement to improve growth and physical performance. Thus far, its effects on human skin have not been described in the literature. For the first time, we show that N,N-dimethylglycine sodium salt (DMG-Na) promoted the proliferation of cultured human epidermal HaCaT keratinocytes. Even at high doses, DMG-Na did not compromise the cellular viability of these cells. In a scratch wound-closure assay, DMG-Na augmented the rate of wound closure, demonstrating that it promotes keratinocyte migration. Further, DMG-Na treatment of the cells resulted in the upregulation of the synthesis and release of specific growth factors. Intriguingly, DMG-Na also exerted robust anti-inflammatory and antioxidant effects, as assessed in three different models of human keratinocytes, mimicking microbial and allergic contact dermatitis as well as psoriasis and UVB irradiation-induced solar dermatitis. These results identify DMG-Na as a highly promising novel active compound to promote epidermal proliferation, regeneration, and repair, and to exert protective functions. Further preclinical and clinical studies are under investigation to prove the seminal impact of topically applied DMG-Na on relevant conditions of the skin and its appendages.

Imaging and Characterization of Oxidative Protein Modifications in Skin

Skin plays an important role in protection, metabolism, thermoregulation, sensation, and excretion whilst being consistently exposed to environmental aggression, including biotic and abiotic stresses. During the generation of oxidative stress in the skin, the epidermal and dermal cells are generally regarded as the most affected regions. The participation of reactive oxygen species (ROS) as a result of environmental fluctuations has been experimentally proven by several researchers and is well known to contribute to ultra-weak photon emission via the oxidation of biomolecules (lipids, proteins, and nucleic acids). More recently, ultra-weak photon emission detection techniques have been introduced to investigate the conditions of oxidative stress in various living systems in in vivo, ex vivo and in vitro studies. Research into two-dimensional photon imaging is drawing growing attention because of its application as a non-invasive tool. We monitored spontaneous and stress-induced ultra-weak photon emission under the exogenous application of a Fenton reagent. The results showed a marked difference in the ultra-weak photon emission. Overall, these results suggest that triplet carbonyl (³C=O^∗) and singlet oxygen (¹O₂) are the final emitters. Furthermore, the formation of oxidatively modified protein adducts and protein carbonyl formation upon treatment with hydrogen peroxide (H₂O₂) were observed using an immunoblotting assay. The results from this study broaden our understanding of the mechanism of the generation of ROS in skin layers and the formation/contribution of various excited species can be used as tools to determine the physiological state of the organism.

Skin Minerals: Key Roles of Inorganic Elements in Skin Physiological Functions

As odd as it may seem at first glance, minerals, it is what we are all about…or nearly. Although life on Earth is carbon-based, several other elements present in the planet’s crust are involved in and often indispensable for functioning of living organisms. Many ions are essential, and others show supportive and accessory qualities. They are operative in the skin, supporting specific processes related to the particular situation of this organ at the interface with the environment. Skin bioenergetics, redox balance, epidermal barrier function, and dermal remodeling are amongst crucial activities guided by or taking advantage of mineral elements. Skin regenerative processes and skin ageing can be positively impacted by adequate accessibility, distribution, and balance of inorganic ions.

Significantly Altered Serum Levels of NAD, AGE, RAGE, CRP, and Elastin as Potential Biomarkers of Psoriasis and Aging—A Case-Control Study

Background: This study aims to investigate potential markers of psoriasis and aging, and to elucidate possible connections between these two processes. Methods: The serum samples of 60 psoriatic patients and 100 controls were analysed, and the levels of four selected parameters (AGEs, RAGE, NAD, and elastin) were determined using commercial ELISA kits. Serum C-reactive protein was assayed using an immune-nephelometry method. Findings: Among the patients, the levels of CRP, AGEs, and RAGE were all increased, while the levels of NAD were reduced when compared to the control group. A negative correlation between the levels of AGEs and NAD was found. A negative correlation between age and the NAD levels among the control group was observed, however among the patients the relationship was diminished. While there was no difference in the levels of native elastin between the patients and the controls, a positive correlation between the levels of native elastin and age and a negative correlation between the levels of native elastin and the severity of psoriasis were found. Conclusions: The results of our study support the notion of psoriasis and possibly other immune-mediated diseases accelerating the aging process through sustained systemic damage. The serum levels of CRP, NAD, AGEs, and RAGE appear to be promising potential biomarkers of psoriasis. The decrease in the serum levels of NAD is associated with (pro)inflammatory states. Our analysis indicates that the levels of native elastin might strongly reflect both the severity of psoriasis and the aging process.

Phytocomplex of a Standardized Extract from Red Orange (Citrus sinensis L. Osbeck) against Photoaging

Excessive exposure to solar radiation is associated with several deleterious effects on human skin. These effects vary from the occasional simple sunburn to conditions resulting from chronic exposure such as skin aging and cancers. Secondary metabolites from the plant kingdom, including phenolic compounds, show relevant photoprotective activities. In this study, we evaluated the potential photoprotective activity of a phytocomplex derived from three varieties of red orange (Citrus sinensis (L.) Osbeck). We used an in vitro model of skin photoaging on two human cell lines, evaluating the protective effects of the phytocomplex in the pathways involved in the response to damage induced by UVA-B. The antioxidant capacity of the extract was determined at the same time as evaluating its influence on the cellular redox state (ROS levels and total thiol groups). In addition, the potential protective action against DNA damage induced by UVA-B and the effects on mRNA and protein expression of collagen, elastin, MMP1, and MMP9 were investigated, including some inflammatory markers (TNF-α, IL-6, and total and phospho NFkB) by ELISA. The obtained results highlight the capacity of the extract to protect cells both from oxidative stress—preserving RSH (p < 0.05) content and reducing ROS (p < 0.01) levels—and from UVA-B-induced DNA damage. Furthermore, the phytocomplex is able to counteract harmful effects through the significant downregulation of proinflammatory markers (p < 0.05) and MMPs (p < 0.05) and by promoting the remodeling of the extracellular matrix through collagen and elastin expression. This allows the conclusion that red orange extract, with its strong antioxidant and photoprotective properties, represents a safe and effective option to prevent photoaging caused by UVA-B exposure.

Comparison of Epidermal Gene Expression Profiles in Mice Aged 1 to 20 Months

Introduction

Although it is well known that epidermal function changes with aging, the transcriptomic basis and possible signaling pathways for aging-associated functional changes remain largely unknown.

Methods

Here, we employed RNA sequencing techniques to assess epidermal gene expression profiles in the epidermis of mice aged 1, 2, 6, 12 and 20 months.

Results

A total of 132 genes displayed reductions in expression levels with aging, while expression levels of 406 genes increased with aging. Epidermal gene expression was prominently upregulated in 2-month-old vs 1-month-old mice, while more genes were downregulated in 12-month-old mice. Upregulation of genes associated with immune/inflammatory responses was observed in the epidermis of aged mice in comparison to that of young mice, whereas downregulated signaling pathways in the epidermis of aged mice were primarily involved in metabolism, such as fatty acid elongation, glutathione metabolism and biosynthesis of antibiotics. Some signaling pathways, such as chemokine signaling, cytokine/cytokine receptor interaction signaling and IL-17 signaling pathways, were remarkably upregulated in 12-month-old mice. Steroid synthesis, metabolic pathway, thermogenesis and proteasome pathways were steadily downregulated, starting at 2 months old.

Conclusion

These results indicate that the epidermis of aged mice displays an upregulation of genes associated with inflammatory signaling pathways, and downregulation of genes related to metabolic signaling pathways.

Electrical aspects of skin as a pathway to engineering skin devices

Skin is one of the indispensable organs for life. The epidermis at the outermost surface provides a permeability barrier to infectious agents, chemicals, and excessive loss of water, while the dermis and subcutaneous tissue mechanically support the structure of the skin and appendages, including hairs and secretory glands. The integrity of the integumentary system is a key for general health, and many techniques have been developed to measure and control this protective function. In contrast, the effective skin barrier is the major obstacle for transdermal delivery and detection. Changes in the electrical properties of skin, such as impedance and ionic activity, is a practical indicator that reflects the structures and functions of the skin. For example, the impedance that reflects the hydration of the skin is measured for quantitative assessment in skincare, and the current generated across a wound is used for the evaluation and control of wound healing. Furthermore, the electrically charged structure of the skin enables transdermal drug delivery and chemical extraction. This paper provides an overview of the electrical aspects of the skin and summarizes current advances in the development of devices based on these features.

Calcium Channels: Noteworthy Regulators and Therapeutic Targets in Dermatological Diseases

Dysfunctional skin barrier and impaired skin homeostasis may lead to or aggravate a series of dermatologic diseases. A large variety of biological events and bioactive molecules are involved in the process of skin wound healing and functional recovery. Calcium ions (Ca²⁺) released from intracellular stores as well as influx through plasma membrane are essential to skin function. Growing evidence suggests that calcium influx is mainly regulated by calcium-sensing receptors and channels, including voltage-gated, transient potential receptor, store-operated, and receptor-operated calcium channels, which not only maintain cellular Ca²⁺ homeostasis, but also participate in cell proliferation and skin cell homeostasis through Ca²⁺-sensitive proteins such as calmodulin (CaM). Furthermore, distinct types of Ca²⁺ channels not merely work separately, they may work concertedly to regulate cell function. In this review, we discussed different calcium-sensing receptors and channels, including voltage-gated, transient receptor potential, store-operated, and receptor-operated calcium channels, particularly focusing on their regulatory functions and inherent interactions as well as calcium channels-related reagents and drugs, which is expected to bridge basic research and clinical applications in dermatologic diseases.

Fuzhenghefuzhiyang Formula (FZHFZY) Improves Epidermal Differentiation via Suppression of the Akt/mTORC1/S6K1 Signalling Pathway in Psoriatic Models

Psoriasis is a chronic proliferative skin disorder characterised by abnormal epidermal differentiation. The Fuzhenghefuzhiyang (FZHFZY) formula created by Chuanjian Lu, a master of Chinese medicine in dermatology, has been external used in the Guangdong Provincial Hospital of Chinese Medicine for the treatment of psoriasis, but its mechanisms of action against psoriasis remain poorly understood. This study involved an exploration of the effects of FZHFZY on epidermal differentiation and its underlying mechanisms in interleukin (IL)-17A/IL-22/interferon (IFN)-γ/tumour necrosis factor (TNF)-α–stimulated HaCaT cells and in a mouse model of imiquimod (IMQ)-induced psoriasis. Cell viability was assessed by MTT assay. Epidermal differentiation was detected by reverse-transcription polymerase chain reaction and western blotting. Histological evaluation of the skin tissue was performed via haematoxylin and eosin staining, and the Akt/mTORC1/S6K1 pathway was analysed by western blotting. FZHFZY inhibited proliferation and improved epidermal differentiation in IL-17A/IL-22/IFN-γ/TNF-α–induced HaCaT cells. FZHFZY ameliorated symptoms of psoriasis, regulated epidermal differentiation and inhibited phosphorylation of the Akt/mTORC1/S6K1 pathway in the skin of mice with imiquimod-induced psoriasis. Our results suggest that FZHFZY may exhibit therapeutic action against psoriasis by regulating epidermal differentiation via inhibition of the Akt/mTORC1/S6K1 pathway.

Antioxidant, Anti-Inflammatory, and Anti-Aging Potential of a Kalmia angustifolia Extract and Identification of Some Major Compounds

Skin aging is the most visible element of the aging process, giving rise to a major concern for many people. Plants from the Ericaceae family generally have antioxidant and anti-inflammatory properties, making them potential anti-aging active ingredients. This study aimed to evaluate the safety and anti-aging efficacy of a Kalmia angustifolia extract using reconstructed skin substitutes. The safety evaluation was performed using a 3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide (MTT) assay, while the efficacy was determined by assessing antioxidant and anti-inflammatory activity and analyzing skin substitutes reconstructed according to the self-assembly method by histology and immunofluorescence staining (elastin, collagen-1, collagen-3, aquaporin-3). The cell viability assay established the safety of the extract at a concentration up to 200 μg/mL. The Oxygen Radical Absorbance Capacity (ORAC) assay and a cell-based assay using 2',7'-dichlorofluorescein-diacetate (DCFH-DA) revealed a strong antioxidant activity with an ORAC value of 16 µmol Trolox Equivalent/mg and a half-maximal inhibitory concentration (IC50) of 0.37 ± 0.02 μg/mL, while an interesting anti-inflammatory activity was found in the inhibition of NO production, with an inhibition percentage of NO production of 49 ± 2% at 80 µg/mL. The isolation and characterization of the extract allowed the identification of compounds that could be responsible for these biological activities, with two of them being identified for the first time in K. angustifolia: avicularin and epicatechin-(2β-O-7, 4β-6)-ent-epicatechin. Histological analyses of skin substitutes treated with the extract showed an increase in dermal thickness compared with the controls. K. angustifolia extract enhanced the expression of elastin and collagen-1, which are usually decreased with skin aging. These results suggest that K. angustifolia has promising antioxidant efficacy and anti-aging potential.

The life in a gradient: calcium, the lncRNA SPRR2C and mir542/mir196a meet in the epidermis to regulate the aging process

The turnover of the epidermis beginning with the progenitor cells in the basal layer to the fully differentiated corneocytes is tightly regulated by calcium. Calcium more than anything else promotes the differentiation of keratinocytes which implies the need for a calcium gradient with low concentrations in the stratum basale and high concentrations in the stratum granulosum. One of the hallmarks of skin aging is a collapse of this gradient that has a direct impact on the epidermal fitness. The rise of calcium in the stratum basale reduces cell proliferation, whereas the drop of calcium in the stratum granulosum leads to a changed composition of the cornified envelope. We showed that keratinocytes respond to the calcium induced block of cell division by a large increase of the expression of several miRNAs (hsa-mir542-5p, hsa-mir125a, hsa-mir135a-5p, hsa-mir196a-5p, hsa-mir491-5p and hsa-mir552-5p). The pitfall of this rescue mechanism is a dramatic change in gene expression which causes a further impairment of the epidermal barrier. This effect is attenuated by a pseudogene (SPRR2C) that gives rise to a lncRNA. SPRR2C specifically resides in the stratum granulosum/corneum thus acting as a sponge for miRNAs.

Vesicular hand eczema transcriptome analysis provides insights into its pathophysiology

Hand eczema is a common inflammatory skin condition of the hands whose pathogenesis is largely unknown. More insight and knowledge of the disease on a more fundamental level might lead to a better understanding of the biological processes involved, which could provide possible new treatment strategies. We aimed to profile the transcriptome of lesional palmar epidermal skin of patients suffering from vesicular hand eczema using RNA‐sequencing. RNA‐sequencing was performed to identify differentially expressed genes in lesional vs. non‐lesional palmar epidermal skin from a group of patients with vesicular hand eczema compared to healthy controls. Comprehensive real‐time quantitative PCR analyses and immunohistochemistry were used for validation of candidate genes and protein profiles for vesicular hand eczema. Overall, a significant and high expression of genes/proteins involved in keratinocyte host defense and inflammation was found in lesional skin. Furthermore, we detected several molecules, both up or downregulated in lesional skin, which are involved in epidermal differentiation. Immune signalling genes were found to be upregulated in lesional skin, albeit with relatively low expression levels. Non‐lesional patient skin showed no significant differences compared to healthy control skin. Lesional vesicular hand eczema skin shows a distinct expression profile compared to non‐lesional skin and healthy control skin. Notably, the overall results indicate a large overlap between vesicular hand eczema and earlier reported atopic dermatitis lesional transcriptome profiles, which suggests that treatments for atopic dermatitis could also be effective in (vesicular) hand eczema.

UTX maintains the functional integrity of the murine hematopoietic system by globally regulating aging-associated genes

Epigenetic regulation is essential for the maintenance of the hematopoietic system, and its deregulation is implicated in hematopoietic disorders. In this study, UTX, a demethylase for lysine 27 on histone H3 (H3K27) and a component of COMPASS-like and SWI/SNF complexes, played an essential role in the hematopoietic system by globally regulating aging-associated genes. Utx-deficient (UtxΔ/Δ) mice exhibited myeloid skewing with dysplasia, extramedullary hematopoiesis, impaired hematopoietic reconstituting ability, and increased susceptibility to leukemia, which are the hallmarks of hematopoietic aging. RNA-sequencing (RNA-seq) analysis revealed that Utx deficiency converted the gene expression profiles of young hematopoietic stem-progenitor cells (HSPCs) to those of aged HSPCs. Utx expression in hematopoietic stem cells declined with age, and UtxΔ/Δ HSPCs exhibited increased expression of an aging-associated marker, accumulation of reactive oxygen species, and impaired repair of DNA double-strand breaks. Pathway and chromatin immunoprecipitation analyses coupled with RNA-seq data indicated that UTX contributed to hematopoietic homeostasis mainly by maintaining the expression of genes downregulated with aging via demethylase-dependent and -independent epigenetic programming. Of note, comparison of pathway changes in UtxΔ/Δ HSPCs, aged muscle stem cells, aged fibroblasts, and aged induced neurons showed substantial overlap, strongly suggesting common aging mechanisms among different tissue stem cells.

Effects of Eggshell Membrane on Keratinocyte Differentiation and Skin Aging In Vitro and In Vivo

Skin aging is one of the hallmarks of the aging process that causes physiological and morphological changes. Recently, several nutritional studies were conducted to delay or suppress the aging process. This study investigated whether nutritional supplementation of the eggshell membrane (ESM) has a beneficial effect on maintaining skin health and improving the skin aging process in vitro using neonatal normal human epidermal keratinocytes (NHEK-Neo) and in vivo using interleukin-10 knockout (IL-10 KO) mice. In NHEK-Neo cells, 1 mg/mL of enzymatically hydrolyzed ESM (eESM) upregulated the expression of keratinocyte differentiation markers, including keratin 1, filaggrin and involucrin, and changed the keratinocyte morphology. In IL-10 KO mice, oral supplementation of 8% powdered-ESM (pESM) upregulated the expression of growth factors, including transforming growth factor β1, platelet-derived growth factor-β and connective tissue growth factor, and suppressed skin thinning. Furthermore, voltage-gated calcium channel, transient receptor potential cation channel subfamily V members were upregulated by eESM treatment in NHEK-Neo cells and pESM supplementation in IL-10 KO mice. Collectively, these data suggest that ESM has an important role in improving skin health and aging, possibly via upregulating calcium signaling.

Abdominal elastotic lesions. A clinicopathologic study of 23 cases

Abdominal elastotic deposits are uncommon lesions that often presents as polyps. They show three histological patterns: fibroelastosis, angioelastosis, and elastofibroma. We describe 23 cases including rare locations, such as mesentery, greater omentum, hernia sac, spleen, peripancreatic fat, and hypodermal fat. The age of the patients ranged from 49 to 93 years (mean, 76.8 years). Most lesions were discovered incidentally in the microscopic study. The most frequent locations were peritoneal subserosa (43.5%) and mesentery/mesocolon/greater omentum (39.1%). The most common pattern was fibroelastosis (69.6%) followed by angioelastosis (26.1%). We observed one case of omental elastofibroma. A review of the 14 abdominal elastofibromas described including our case revealed that the age of the patients ranged from 45 to 88 years (mean, 68.5 years). Female predominance is striking (M:F, 1:12). The most common site was the stomach (50%). The greater omentum (14.3%), small intestine (7.1%), and pancreas (7.1%) are very rare sites for this lesion. Only one case before ours has been published in the greater omentum. The size of the lesions ranged from 0.7 cm to 8 cm (mean 3.2 cm). In 36.4% of the cases located in the digestive tract, the mucosa did not show alterations. Ulcerations (36.4%) or polypoid excrescences (18.2%) were mostly observed. Six (42.9%) cases were asymptomatic and six (42.9%) cases simulated a neoplasm. Two cases were associated with elastofibromas in other locations. Differential diagnosis includes amyloidoma, elastofibrolipoma, mesenteric elastic vascular sclerosis in neuroendocrine tumors, diverticular disease elastosis, pseudoxanthoma elasticum, pulse granuloma, and digestive lesions in patients treated with D-Penicillamine.

Corneotherapie – Pflege und Reparatur der Haut: präzise, effektiv und nachhaltig

Die Pflege und Gesunderhaltung der Haut ist nicht nur für ein gutes Aussehen, sondern auch für das allgemeine Wohlbefinden essenziell. Viele Menschen investieren daher für die Hautpflege nicht nur viel Zeit, sondern auch viel Geld. Oft stellt sich jedoch die Frage, welche Produkte aus der Vielfalt an Angeboten nun besonders effektiv und empfehlenswert sind. Der Artikel gibt darüber Auskunft. Er erläutert die Grundlagen und aktuellen Erkenntnisse der Corneobiologie und zeigt, wie eine präzise, effektive und nachhaltige Hautpflege heute aussehen sollte.

Its written all over your face: The molecular and physiological consequences of aging skin

Perhaps the most recognizable consequences of tissue aging are manifested in the skin. Hair graying and loss, telltale wrinkles, and age spots are indicative of physiological aging symptoms, many of which are analogous to processes in other tissues as well with less visible outcomes. While the study of skin aging has been conducted for decades, more recent work has illuminated many of the fundamental molecular and physiological causes of aging in the skin. Recent technological advances have allowed for the detection and quantification of a variety of physiological triggers that lead to aging in the skin and molecular methods have begun to determine the etiology of these phenotypic features. This review will attempt to summarize recent work in this area and provide some speculation about the next wave of studies.

Quantitative proteomics analysis of young and elderly skin with DIA mass spectrometry reveals new skin aging-related proteins

Skin aging is a specific manifestation of the physiological aging process that occurs in virtually all organisms. In this study, we used data independent acquisition mass spectrometry to perform a comparative analysis of protein expression in volar forearm skin samples from of 20 healthy young and elderly Chinese individuals. Our quantitative proteomic analysis identified a total of 95 differentially expressed proteins (DEPs) in aged skin compared to young skin. Enrichment analyses of these DEPs (57 upregulated and 38 downregulated proteins) based on the GO, KEGG, and KOG databases revealed functional clusters associated with immunity and inflammation, oxidative stress, biosynthesis and metabolism, proteases, cell proliferation, cell differentiation, and apoptosis. We also found that GAPDH, which was downregulated in aged skin samples, was the top hub gene in a protein-protein interaction network analysis. Some of the DEPs identified herein had been previously correlated with aging of the skin and other organs, while others may represent novel age-related entities. Our non-invasive proteomics analysis of human epidermal proteins may guide future research on skin aging to help develop treatments for age-related skin conditions and rejuvenation.

Reduction of enlarged facial pore using ion-paired amino acid through enhancement in skin permeation and exfoliation: A placebo-controlled in vivo study

BACKGROUND

Serine is a hypoallergenic but inefficient chemical exfoliant. Serine paired with arginine (ion-paired amino acid, IPA) shows enhanced lipophilicity, skin permeation, and exfoliation efficacy.

AIM

This study was conducted to determine whether exfoliation using an emulsion containing IPA could reduce enlarged facial pores and improve the dermis density.

METHODS

IPA formation was validated by spectroscopic analysis. Enhanced permeability and exfoliation efficacy were evaluated ex vivo using porcine skin. In a clinical trial, healthy Korean women aged 20-49 years (mean age ± SD: 35.6 ± 8.6, n = 64) were evaluated, and the right and left sides of the cheeks were randomly chosen. An emulsion containing 4.0% IPA and placebo emulsion were applied to each side for 6 weeks. To evaluate pore sizes following treatment, the number of enlarged facial pores, inner skin structures from the stratum corneum to epidermal-dermal interface, and dermal density on each cheek of the participants were assessed.

RESULTS

IPA showed a significantly increased partition coefficient in n-octanol-water. In porcine skin, permeation of serine after 12 hour was 70% higher for the IPA than for serine alone at the same percent weight concentrations. In the clinical trial, after 6 weeks, the number of enlarged facial pores was changed by -19.317% in the IPA emulsion group (P < .001) and -2.930% in placebo emulsion group (P = .254).

CONCLUSION

Exfoliation with an IPA-containing emulsion reduced enlarged facial pores and increased the dermis density. IPA, effective mild exfoliator, can be used as a major ingredient for the cosmeceutical skincare products in the future.

Clinically Relevant Tissue Scale Responses as New Readouts from Organs-on-a-Chip for Precision Medicine

Organs-on-chips (OOC) are widely seen as being the next generation in vitro models able to accurately recreate the biochemical-physical cues of the cellular microenvironment found in vivo. In addition, they make it possible to examine tissue-scale functional properties of multicellular systems dynamically and in a highly controlled manner. Here we summarize some of the most remarkable examples of OOC technology's ability to extract clinically relevant tissue-level information. The review is organized around the types of OOC outputs that can be measured from the cultured tissues and transferred to clinically meaningful information. First, the creation of functional tissues-on-chip is discussed, followed by the presentation of tissue-level readouts specific to OOC, such as morphological changes, vessel formation and function, tissue properties, and metabolic functions. In each case, the clinical relevance of the extracted information is highlighted.

Monitoring calcium-induced epidermal differentiation in vitro using multiphoton microscopy

SIGNIFICANCE

Research in tissue engineering and in vitro organ formation has recently intensified. To assess tissue morphology, the method of choice today is restricted primarily to histology. Thus novel tools are required to enable noninvasive, and preferably label-free, three-dimensional imaging that is more compatible with futuristic organ-on-a-chip models.

AIM

We investigate the potential for using multiphoton microscopy (MPM) as a label-free in vitro approach to monitor calcium-induced epidermal differentiation.

APPROACH

In vitro epidermis was cultured at the air-liquid interface in varying calcium concentrations. Morphology and tissue architecture were investigated using MPM based on visualizing cellular autofluorescence.

RESULTS

Distinct morphologies corresponding to epidermal differentiation were observed. In addition, Ca2  +  -induced effects could be distinguished based on the architectural differences in stratification in the tissue cultures.

CONCLUSIONS

Our study shows that MPM based on cellular autofluorescence enables visualization of Ca2  +  -induced differentiation in epidermal skin models in vitro. The technique has potential to be further adapted as a noninvasive, label-free, and real-time tool to monitor tissue regeneration and organ formation in vitro.

Senescent human melanocytes drive skin ageing via paracrine telomere dysfunction

Cellular senescence has been shown to contribute to skin ageing. However, the role of melanocytes in the process is understudied. Our data show that melanocytes are the only epidermal cell type to express the senescence marker p16INK4A during human skin ageing. Aged melanocytes also display additional markers of senescence such as reduced HMGB1 and dysfunctional telomeres, without detectable telomere shortening. Additionally, senescent melanocyte SASP induces telomere dysfunction in paracrine manner and limits proliferation of surrounding cells via activation of CXCR3-dependent mitochondrial ROS. Finally, senescent melanocytes impair basal keratinocyte proliferation and contribute to epidermal atrophy in vitro using 3D human epidermal equivalents. Crucially, clearance of senescent melanocytes using the senolytic drug ABT737 or treatment with mitochondria-targeted antioxidant MitoQ suppressed this effect. In conclusion, our study provides proof-of-concept evidence that senescent melanocytes affect keratinocyte function and act as drivers of human skin ageing.

Royal jelly regulates the proliferation of human dermal microvascular endothelial cells through the down-regulation of a photoaging-related microRNA

Although royal jelly is believed to prevent skin aging, the underlying mechanism is not known in detail. In the present study, we investigated the plausibility of the involvement of microRNAs in the manifestation of this effect of royal jelly. The expression of microRNAs was determined by PCR array analysis and real-time PCR and the number of cells was counted with a cell counter. Using PCR array, we identified four microRNAs that were downregulated by royal jelly in cultured human dermal microvascular endothelial cells (HDMEC). Upon comparison of the expression of the four microRNAs between young and senescent facial skin, miR-129-5p was found to be significantly upregulated in senescent skin. Consistently, the expression of miR-129-5p in HDMEC was significantly increased by UVB radiation, suggesting that this microRNA is related to photoaging. The royal jelly treatment increased the number of HDMEC. Furthermore, forced overexpression of miR-129-5p resulted in significant decrease in the number of HDMEC, and its forced downregulation increased the number of cells. The number and density of vessels is reported to be decreased in aged skin. Our results indicate that miR-129-5p is induced in damaged endothelial cells upon exposure to UV radiation, which decreases the cell number. Furthermore, administration of royal jelly downregulated the expression of miR-129-5p in endothelial cells, and might prevent skin aging by maintaining the number of cells. The present study elucidates the mechanism of vessel aging caused by UV exposure and the anti-aging effects of royal jelly through the involvement of microRNA.

Atopic dermatitis in the elderly: a review of clinical and pathophysiological hallmarks

BACKGROUND

Atopic dermatitis (AD) is a multifactorial and complex disease, characterized by an impaired skin barrier function and abnormal immune response. Many elderly patients present with pruritus and xerosis to dermatology, allergy and primary care clinics, and there is a lack of information available to clinicians regarding the proper diagnosis and management of these patients. Although the elderly are described as having a distinct presentation of AD and important comorbidities, most investigations and clinical care guidelines pertaining to AD do not include patients aged 60 years and older as a separate group from younger adults.

OBJECTIVES

To summarize current information on pathophysiology, diagnosis and management of AD in the elderly population and identify areas of insufficient information to be explored in future investigations.

METHODS

We carried out a systematic review of published literature, which assessed changes in the skin barrier and immune function with ageing and current information available for physicians to use in the diagnosis and treatment of AD in elderly patients.

RESULTS

Many age-related changes overlap with key hallmarks observed in AD, most notably a decline in skin barrier function, dysregulation of the innate immune system, and skewing of adaptive immunity to a type-2 T helper cell response, in addition to increased Staphylococcus aureus infection.

CONCLUSIONS

While general physiological alterations with ageing overlap with key features of AD, a research gap exists regarding specific ageing-related changes in AD disease development. More knowledge about AD in the elderly is needed to establish firm diagnostic and treatment methodologies. What's already known about this topic? Atopic dermatitis (AD) is a common inflammatory skin disease that causes significant burden worldwide. Recently, elderly patients have been considered a subgroup of patients with distinct AD manifestation. Limited studies have characterized the clinical presentation and role of IgE-mediated allergy in elderly patients with AD. What does this study add? This review offers a summary of age-related skin and immune alterations that correspond to pathogenic changes noted in patients with AD. The role of itch, environmental factors and skin microbiota in AD disease presentation in ageing patients is explored.

Aging of the skin barrier

The skin barrier is mainly present in the stratum corneum (SC), composed of corneocytes surrounded by intercellular lipid lamellae, and attached by corneodesmosome. The tight junction attached to the lateral walls of keratinocytes in the upper part of the stratum granulosum is also included in the skin barrier. During aging, the following structures and functions of the skin barrier are changed or disturbed: (1) skin barrier structure, (2) permeability barrier function, (3) epidermal calcium gradient, (4) epidermal lipid synthesis and SC lipid processing, (5) cytokine production and response after insults, (6) SC acidity, (7) SC hydration, and (8) antimicrobial barrier. Patients with diabetes also show changes in the skin barrier similar to those in aged skin, and the characteristics of the skin barrier are very similar. Understanding the pathogenic mechanisms of the skin barrier in aging will permit us to develop therapeutic strategies for aged or diabetic skin.

Beneficial Effects of Marine Algae-Derived Carbohydrates for Skin Health

Marine algae are considered to be an abundant sources of bioactive compounds with cosmeceutical potential. Recently, a great deal of interest has focused on the health-promoting effects of marine bioactive compounds. Carbohydrates are the major and abundant constituent of marine algae and have been utilized in cosmetic formulations, as moisturizing and thickening agents for example. In addition, marine carbohydrates have been suggested as promising bioactive biomaterials for their various properties beneficial to skin, including antioxidant, anti-melanogenic and skin anti-aging properties. Therefore, marine algae carbohydrates have potential skin health benefits for value-added cosmeceutical applications. The present review focuses on the various biological capacities and potential skin health benefits of bioactive marine carbohydrates.

Ultrastructural and Molecular Analysis of Ribose-Induced Glycated Reconstructed Human Skin

Aging depicts one of the major challenges in pharmacology owing to its complexity and heterogeneity. Thereby, advanced glycated end-products modify extracellular matrix proteins, but the consequences on the skin barrier function remain heavily understudied. Herein, we utilized transmission electron microscopy for the ultrastructural analysis of ribose-induced glycated reconstructed human skin (RHS). Molecular and functional insights substantiated the ultrastructural characterization and proved the relevance of glycated RHS beyond skin aging. In particular, electron microscopy mapped the accumulation and altered spatial orientation of fibrils and filaments in the dermal compartment of glycated RHS. Moreover, the epidermal basement membrane appeared thicker in glycated than in non-glycated RHS, but electron microscopy identified longitudinal clusters of the finest collagen fibrils instead of real thickening. The stratum granulosum contained more cell layers, the morphology of keratohyalin granules decidedly differed, and the stratum corneum lipid order increased in ribose-induced glycated RHS, while the skin barrier function was almost not affected. In conclusion, dermal advanced glycated end-products markedly changed the epidermal morphology, underlining the importance of matrix⁻cell interactions. The phenotype of ribose-induced glycated RHS emulated aged skin in the dermis, while the two to three times increased thickness of the stratum granulosum resembled poorer cornification.

The role of Sox9 in maintaining the characteristics and pluripotency of Arbas Cashmere goat hair follicle stem cells

In our previous work, we isolated Arbas Cashmere goat hair follicle stem cells (gHFSCs) and explored the pluripotency. In this study, we investigated the expression and putative role of Sox9 in the gHFSCs. Immunofluorescence staining showed that Sox9 is predominantly expressed in the bulge region of the Arbas Cashmere goat hair follicle, and also positively expressed in both nucleus and cytoplasm of the gHFSCs. When the cells were transfected using Sox9-shRNA, cell growth slowed down and the expression of related genes decreased significantly, cell cycle was abnormal, while the expression of terminal differentiation marker loricrin was markedly increased; cells lost the typical morphology of HFSCs; the mRNA and protein expression of gHFSCs markers and stem cell pluripotency associated factors were all significantly decreased; the expression of Wnt signaling pathway genes LEF1, TCF1,c-Myc were significantly changed. These results suggested that Sox9 plays important role in gHFSCs characteristics and pluripotency maintenance.

The cytotoxic mechanism of epigallocatechin gallate on proliferative HaCaT keratinocytes

BACKGROUND

Epigallocatechin gallate (EGCG) is the major ingredient of sinecatechins ointment, approved for the treatment of external genital and perianal warts. However, the molecular mechanism for EGCG's effect on warts resulting from the human papillomavirus (HPV) infection of keratinocytes is not well understood. HPV may survive in proliferative keratinocytes and may be involved in cell cycle regulation and progression. The objective of this study was to investigate the mechanism underlying EGCG's treatment on external genital warts of HPV infection through the cultured keratinocyte cells from the HaCaT cell line.

METHODS

MTT and flow cytometry assays were used to measure cell viability and the cell cycle profile, with and without EGCG treatment, for HaCaT keratinocyte cells cultured in a calcium-free medium and 1.8 mM calcium which induced proliferative and differentiated keratinocytes, respectively, for 24 h. The expression levels of cytotoxic proteins and factors were evaluated with the RT-PCR and western blotting analysis.

RESULTS

EGCG influenced the proliferation stage but not the differentiation stage of keratinocytes. We suggest that apoptosis and autophagy might be the possible mechanism for the EGCG's effect on the proliferative HaCaT cells. Furthermore, we found that EGCG reduced the protein levels of cyclin D1 and Zac1 (a zinc-finger protein which regulates apoptosis and cell cycle arrest 1) dose-dependently in proliferative as compared to differentiated keratinocytes. It also induced the expression of p21 and DEC1 (differentiated embryo-chondrocyte expressed gene 1), and promoted G1 arrest of cell cycle in proliferative keratinocytes.

CONCLUSIONS

These results help clarify the mechanisms of EGCG treatment of HPV-infected keratinocytes and may contribute to new targets, such as Zac1 and DEC1 for external genital and perianal warts.

Type XVII collagen coordinates proliferation in the interfollicular epidermis

Type XVII collagen (COL17) is a transmembrane protein located at the epidermal basement membrane zone. COL17 deficiency results in premature hair aging phenotypes and in junctional epidermolysis bullosa. Here, we show that COL17 plays a central role in regulating interfollicular epidermis (IFE) proliferation. Loss of COL17 leads to transient IFE hypertrophy in neonatal mice owing to aberrant Wnt signaling. The replenishment of COL17 in the neonatal epidermis of COL17-null mice reverses the proliferative IFE phenotype and the altered Wnt signaling. Physical aging abolishes membranous COL17 in IFE basal cells because of inactive atypical protein kinase C signaling and also induces epidermal hyperproliferation. The overexpression of human COL17 in aged mouse epidermis suppresses IFE hypertrophy. These findings demonstrate that COL17 governs IFE proliferation of neonatal and aged skin in distinct ways. Our study indicates that COL17 could be an important target of anti-aging strategies in the skin.

[Epidermal aging and anti-aging strategies]

Epithelial senescence is a complex process depending on intrinsic as well as extrinsic factors (e.g., UV or IR light, tobacco smoke) and must be seen in the context of the aging process especially of the corium and the subcutis. Morphological alterations become apparent in the form of epithelial atrophy, structural changes within the basal membrane, and a decrease in cell count of melanocytes and Langerhans cells. Signs of cellular senescence are reduced proliferation of keratinocytes, cumulation of dysplastic keratinocytes, various mutations (e.g., c-Fos/c-Jun, STAT3, FoxO1), as well as multiple lipid or amino acid metabolic aberrations (e.g., production of advanced glycation endproducts). This causes functional changes within the physical (lipid deficiency, water distribution dysfunction, lack of hygroscopic substances), chemical (pH conditions, oxygen radicals), and immunological barrier. Prophylactically, barrier-protective care products, antioxidant substances (e.g., vitamin C, B3, E, polyphenols, flavonoids), sunscreen products/measurements, and retinoids are used. For correcting alterations in aged epidermis, chemical peelings (fruit acids, β-hydroxy acid, trichloroacetic acid, phenolic compounds), non-ablative (IPL, PDL, Nd:YAG) as well as ablative (CO2, Erbium-YAG) light-assisted methods are used.

Transcription factor 7-like 1 dysregulates keratinocyte differentiation through upregulating lipocalin 2

Recent studies strongly suggested that transcription factor 7-like 1 (Tcf7l1, also known as Tcf3) is involved in the differentiation of several types of cells, and demonstrated that Tcf7l1 modulates keratinocytes physiologically through regulating lipocalin 2 (LCN2), a key regulator of cell differentiation. To reveal the potential role of Tcf7l1 in the dysregulation of keratinocyte differentiation, both Tcf7l1 and LCN2 were determined in a variety of skin disorders. The in vitro effect of Tcf7l1 on keratinocyte differentiation was studied by culturing SCC-13 cells, and the human foreskin keratinocytes (HFKs) that were transfected with vectors for overexpressing human papillomavirus E6/E7 or Tcf7l1 genes. We found that both Tcf7l1 and LCN2 were highly expressed in those diseases characterized by defective keratinocyte differentiation (especially psoriasis vulgaris, condyloma acuminatum, squamous cell carcinoma, etc). Moreover, compared with control HFKs, SCC-13 cells and E6/E7-harboring HFKs expressed more Tcf7l1 and LCN2. Tcf7l1 siRNA transfection decreased LCN2 but increased involucrin and loricrin in HFKs under calcium stimuli. Conversely, Tcf7l1 overexpression in SCC-13 cells or vector-transfected HFKs induced lower involucrin and loricrin expression and less keratinocyte apoptosis, both of which, however, were partially abrogated by LCN2 siRNA or neutralizing anti-LCN2 antibody. Interestingly, the Tcf7l1 expression in HFKs correlated positively with the MMP-2 level, and the inhibition of MMP-2 decreased the LCN2 level and even attenuated the effect of Tcf7l1 on LCN2 expression. Therefore, Tcf7l1 dysregulates keratinocyte differentiation, possibly through upregulating the LCN2 pathway in an MMP-2 mediated manner. Elucidating the interaction between Tcf7l1 and LCN2 may help understand disordered cell differentiation in some skin diseases.

Oxidative stress, microRNAs and cytosolic calcium homeostasis

Reactive oxygen species increase cytosolic [Ca(2+)], (Cai), and also modulate the expression of some microRNAs (miRNAs), however the link among oxidative stress, miRNAs and Cai is poorly characterized. In this review we have focused on three groups of miRNAs: (a) miRNAs that are modulated both by ROS and Cai: miR-181a and miR-205; (b) miRNAs that are modulated by ROS and have an effect on Cai: miR-1, miR-21, miR-24, miR-25, miR-185 and miR-214; (c) miRNAs that modulate both ROS and Cai: miR-133; miR-145, miR-495, and we have analyzed their effects on cell signaling and cell function. Finally, in the last section we have examined the role of these miRNAs in the skin, under conditions associated with enhanced oxidative stress, i.e. skin aging, the response to ultraviolet light and two important skin diseases, psoriasis and atopic dermatitis. It is apparent that although some experimental evidence is already available on (a) the role of Cai in miRNAs expression and (b) on the ability of some miRNAs to modulate Cai-dependent intracellular signaling, these research lines are still largely unexplored and represent important areas of future studies.

Transcriptome and ultrastructural changes in dystrophic Epidermolysis bullosa resemble skin aging

The aging process of skin has been investigated recently with respect to mitochondrial function and oxidative stress. We have here observed striking phenotypic and clinical similarity between skin aging and recessive dystrophic Epidermolysis bullosa (RDEB), which is caused by recessive mutations in the gene coding for collagen VII, COL7A1. Ultrastructural changes, defects in wound healing, and inflammation markers are in part shared with aged skin. We have here compared the skin transcriptomes of young adults suffering from RDEB with that of sex‐ and age‐matched healthy probands. In parallel we have compared the skin transcriptome of healthy young adults with that of elderly healthy donors. Quite surprisingly, there was a large overlap of the two gene lists that concerned a limited number of functional protein families. Most prominent among the proteins found are a number of proteins of the cornified envelope or proteins mechanistically involved in cornification and other skin proteins. Further, the overlap list contains a large number of genes with a known role in inflammation. We are documenting some of the most prominent ultrastructural and protein changes by immunofluorescence analysis of skin sections from patients, old individuals, and healthy controls.

Pax8 plays a pivotal role in regulation of cardiomyocyte growth and senescence

Congenital heart disease (CHD) is a worldwide health problem, particularly in young populations. In spite of the advancement and progress in medical research and technology, the underlying causative factors and mechanisms of CHD still remain unclear. Bone morphogenetic protein receptor IA (ALK3) mediates the development of ventricular septal defect (VSD). We have recently found that paired box gene 8 (Pax8) may be the downstream molecule of ALK3. Paired box gene 8 plays an essential role in VSD, and apoptosis and proliferation imbalance leads to septal dysplasia. Recent studies have also disclosed that cellular senescence also participates in embryonic development. Whether programmed senescence exists in cardiac organogenesis has not ever been reported. We hypothesized that together with various biological processes, such as apoptosis, enhanced cellular senescence may occur actively in the development of Pax8 null mice murine hearts. In H9C2 myogenic cells, Pax8 overexpression can rescue caspase‐dependent apoptosis induced by ALK3 silencing. Senescent cells and senescence‐associated mediators in Pax8 knockout hearts increased compared with the wild‐type ones in an age‐dependent manner. These results suggest that Pax8 maybe the downstream molecule of ALK3, it mediates the murine heart development perhaps via cellular senescence, which may serve as a mechanism that compensates for the cell loss via apoptosis in heart development.

Programmed cell death in aging

Programmed cell death (PCD) pathways, including apoptosis and regulated necrosis, are required for normal cell turnover and tissue homeostasis. Mis-regulation of PCD is increasingly implicated in aging and aging-related disease. During aging the cell turnover rate declines for several highly-mitotic tissues. Aging-associated disruptions in systemic and inter-cell signaling combined with cell-autonomous damage and mitochondrial malfunction result in increased PCD in some cell types, and decreased PCD in other cell types. Increased PCD during aging is implicated in immune system decline, skeletal muscle wasting (sarcopenia), loss of cells in the heart, and neurodegenerative disease. In contrast, cancer cells and senescent cells are resistant to PCD, enabling them to increase in abundance during aging. PCD pathways limit life span in fungi, but whether PCD pathways normally limit adult metazoan life span is not yet clear. PCD is regulated by a balance of negative and positive factors, including the mitochondria, which are particularly subject to aging-associated malfunction.

Oxidative stress in aging human skin

Oxidative stress in skin plays a major role in the aging process. This is true for intrinsic aging and even more for extrinsic aging. Although the results are quite different in dermis and epidermis, extrinsic aging is driven to a large extent by oxidative stress caused by UV irradiation. In this review the overall effects of oxidative stress are discussed as well as the sources of ROS including the mitochondrial ETC, peroxisomal and ER localized proteins, the Fenton reaction, and such enzymes as cyclooxygenases, lipoxygenases, xanthine oxidases, and NADPH oxidases. Furthermore, the defense mechanisms against oxidative stress ranging from enzymes like superoxide dismutases, catalases, peroxiredoxins, and GSH peroxidases to organic compounds such as L-ascorbate, α-tocopherol, beta-carotene, uric acid, CoQ10, and glutathione are described in more detail. In addition the oxidative stress induced modifications caused to proteins, lipids and DNA are discussed. Finally age-related changes of the skin are also a topic of this review. They include a disruption of the epidermal calcium gradient in old skin with an accompanying change in the composition of the cornified envelope. This modified cornified envelope also leads to an altered anti-oxidative capacity and a reduced barrier function of the epidermis.