Protective effect of matrix metalloproteinase inhibitors against epidermal basement membrane damage: skin equivalents partially mimic photoageing process

Radiofrequency Treatment Attenuates Age-Related Changes in Dermal-Epidermal Junctions of Animal Skin

The dermal-epidermal junction (DEJ) is essential for maintaining skin structural integrity and regulating cell survival and proliferation. Thus, DEJ rejuvenation is key for skin revitalization, particularly in age-related DEJ deterioration. Radiofrequency (RF) treatment, known for its ability to enhance collagen fiber production through thermal mechanisms and increase heat shock protein (HSP) expression, has emerged as a promising method for skin rejuvenation. Additionally, RF activates Piezo1, an ion channel implicated in macrophage polarization toward an M2 phenotype and enhanced TGF-β production. This study investigated the impact of RF treatment on HSP47 and HSP90 expression, known stimulators of DEJ protein expression. Furthermore, using in vitro and aged animal skin models, we assessed whether RF-induced Piezo1 activation and the subsequent M2 polarization could counter age-related DEJ changes. The RF treatment of H2O2-induced senescent keratinocytes upregulated the expression of HSP47, HSP90, TGF-β, and DEJ proteins, including collagen XVII. Similarly, the RF treatment of senescent macrophages increased Piezo1 and CD206 (M2 marker) expression. Conditioned media from RF-treated senescent macrophages enhanced the expression of TGF-β and DEJ proteins, such as nidogen and collagen IV, in senescent fibroblasts. In aged animal skin, RF treatment increased the expression of HSP47, HSP90, Piezo1, markers associated with M2 polarization, IL-10, and TGF-β. Additionally, RF treatment enhanced DEJ protein expression. Moreover, RF reduced lamina densa replication, disrupted lesions, promoted hemidesmosome formation, and increased epidermal thickness. Overall, RF treatment effectively enhanced DEJ protein expression and mitigated age-related DEJ structural changes by increasing HSP levels and activating Piezo1.

Organotypic cultures as aging associated disease models

Aging remains a primary risk factor for a host of diseases, including leading causes of death. Aging and associated diseases are inherently multifactorial, with numerous contributing factors and phenotypes at the molecular, cellular, tissue, and organismal scales. Despite the complexity of aging phenomena, models currently used in aging research possess limitations. Frequently used in vivo models often have important physiological differences, age at different rates, or are genetically engineered to match late disease phenotypes rather than early causes. Conversely, routinely used in vitro models lack the complex tissue-scale and systemic cues that are disrupted in aging. To fill in gaps between in vivo and traditional in vitro models, researchers have increasingly been turning to organotypic models, which provide increased physiological relevance with the accessibility and control of in vitro context. While powerful tools, the development of these models is a field of its own, and many aging researchers may be unaware of recent progress in organotypic models, or hesitant to include these models in their own work. In this review, we describe recent progress in tissue engineering applied to organotypic models, highlighting examples explicitly linked to aging and associated disease, as well as examples of models that are relevant to aging. We specifically highlight progress made in skin, gut, and skeletal muscle, and describe how recently demonstrated models have been used for aging studies or similar phenotypes. Throughout, this review emphasizes the accessibility of these models and aims to provide a resource for researchers seeking to leverage these powerful tools.

Regeneration of collagen fibrils at the papillary dermis by reconstructing basement membrane at the dermal-epidermal junction

The epidermal basement membrane deteriorates with aging. We previously reported that basement membrane reconstruction not only serves to maintain epidermal stem/progenitor cells in the epidermis, but also increases collagen fibrils in the papillary dermis. Here, we investigated the mechanism of the latter action. Collagen fibrils in the papillary dermis were increased in organotypic human skin culture treated with matrix metalloproteinase and heparinase inhibitors. The expression levels of COL5A1 and COL1A1 genes (encoding collagen type V α 1 chain and collagen type I α 1 chain, respectively) were increased in fibroblasts cultured with conditioned medium from a skin equivalent model cultured with the inhibitors and in keratinocytes cultured on laminin-511 E8 fragment-coated plates. We then examined cytokine expression, and found that the inhibitors increased the expression of PDGF-BB (platelet-derived growth factor consisting of two B subunits) in epidermis. Expression of COL5A1 and COL1A1 genes was increased in cultured fibroblasts stimulated with PDGF-BB. Further, the bifunctional inhibitor hydroxyethyl imidazolidinone (HEI) increased skin elasticity and the thickness of the papillary dermis in the skin equivalent. Taken together, our data suggests that reconstructing the basement membrane promotes secretion of PDGF-BB by epidermal keratinocytes, leading to increased collagen expression at the papillary dermis.

(-)-Loliolide Isolated from Sargassum horneri Abate UVB-Induced Oxidative Damage in Human Dermal Fibroblasts and Subside ECM Degradation

Ultraviolet (UV) B exposure is a prominent cause of skin aging and a contemporary subject of interest. The effects are progressing through the generation of reactive oxygen species (ROS) that alter cell signaling pathways related to inflammatory responses. The present study evaluates the protective effects of (7aR)-6-hydroxy-4,4,7a-trimethyl-6,7-dihydro-5H-1-benzofuran-2-one (HTT) isolated from the edible brown algae Sargassum horneri against UVB protective effects in human dermal fibroblasts (HDFs). HTT treatment dose-dependently suppressed intracellular ROS generation in HDFs with an IC50 of 62.43 ± 3.22 µM. HTT abated UVB-induced mitochondrial hyperpolarization and apoptotic body formation. Furthermore, UVB-induced activation of key nuclear factor (NF)-κB and mitogen-activated protein kinase signaling proteins were suppressed in HTT treated cells while downregulating pro-inflammatory cytokines (interleukin-1β, 6, 8, 33 and tumor necrosis factor-α). Moreover, HTT treatment downregulated matrix metalloproteinase1, 2, 3, 8, 9 and 13 that was further confirmed by the inhibition of collagenase and elastase activity. The evidence implies that HTT delivers protective effects against premature skin aging caused by UVB exposure via suppressing inflammatory responses and degradation of extracellular matrix (ECM) components. Extensive research in this regard will raise perspectives for using HTT as an ingredient in UV protective ointments.

Basement Membrane Helps Maintain Epidermal Hyaluronan Content

Hyaluronan (HA) is the major glycosaminoglycan in the extracellular matrix of most mammalian tissues, including the epidermis. It is synthesized in epidermis, and mainly metabolized after transfer to the liver via lymphatic vessels in the dermis following its passage through the basement membrane (BM) at the dermal-epidermal junction. The aim of the present study was to investigate the influence of BM integrity on the level of HA in the epidermis. Epidermal HA content was decreased in sun-exposed skin of older subjects, whose BM structure was impaired, compared with sun-exposed young skin and sun-protected skin, in which BM integrity was well maintained. In an organotypic culture model of sun-exposed facial skin, epidermal HA was increased in the presence of inhibitors of BM-degrading matrix metalloproteinases and heparanase. In a skin equivalent model treated with these inhibitors, HA content was increased in the epidermis, but decreased in conditioned medium. These findings suggest that the BM at the dermal-epidermal junction plays an important role in maintaining epidermal HA levels.

3-O-Laurylglyceryl ascorbate improves the development of sensitive skin through the reduction of oxidative stress

Skin sensitivity is a serious problem for many people, and it can be induced by various factors such as UV irradiation, physical and mental stresses, air pollution, dry air and so on. Skin dryness triggered by UV and dry air is one of the most important causes inducing the development of sensitive skin, and it has been reported that oxidative stress contributes to skin dryness. In this study, we investigated whether treatment with 3-O-laurylglyceryl ascorbate (VC-3LG), which is an amphipathic ascorbic acid derivative, can suppress the development of sensitive skin. The results demonstrate that VC-3LG restores the expression levels of interleukin-1α, nerve growth factor and matrix metalloprotease-9 in the dry skin models of reconstructed human epidermal equivalents (RHEEs) and in H₂ O₂ -treated keratinocytes. In addition, VC-3LG suppresses the dendrite elongation of nerve cells induced in RHEEs by dry skin conditions and by H₂ O₂ treatment of keratinocytes. Therefore, we consider that treatment of the skin with VC-3LG is an effective approach to improve the development of sensitive skin.

Decrease of laminin-511 in the basement membrane due to photoaging reduces epidermal stem/progenitor cells

Daily sunlight exposure damages the epidermal basement membrane (BM) and disrupts epidermal homeostasis. Inter-follicular epidermal stem cells (IFE-SCs) regulate epidermal proliferation and differentiation, which supports epidermal homeostasis. Here, we examine how photoaging affects the function of IFE-SCs and we identify key components in their cellular environment (niche). We found that sun-exposed skin showed a decrease of MCSP-positive and β1-integrin-positive cells concomitantly with a decrease of laminin-511 at the dermal-epidermal junction (DEJ), as compared with sun-protected skin. Higher levels of laminin-511 were associated with not only increased efficiency of colony formation, but also higher expression levels of MCSP as well as other stem cell markers such as Lrig1, ITGB1, CD44, CD46, DLL1, and K15 in keratinocytes from skin of 12- to 62-year-old subjects. UVB exposure to cultured human skin impaired laminin-511 integrity at the dermal-epidermal junction and reduced MCSP-positive basal epidermal cells as well as K15-positive cells. Combined treatment with matrix metalloproteinase and heparanase inhibitors protected the integrity of laminin-511 and inhibited the reduction of MCSP-positive cells and K15-positive cells. These results suggest that photoaging may reduce the levels of MCSP-positive and K15-positive epidermal stem/progenitor cells in the epidermis via loss of laminin-511 at the dermal-epidermal junction.

Construction of Vascularized Oral Mucosa Equivalents Using a Layer-by-Layer Cell Coating Technology

There have been many advances in tissue engineering with respect to in vitro and in vivo models of oral mucosa equivalents (OMEs). To apply in vitro reconstructed oral mucosa models to regenerative medicine and alternatives to animal testing, it is necessary to develop the technology of reconstructing different types of oral tissues, such as control of epithelial differentiation and introduction of appendages. We previously reported that functional three-dimensional (3D) tissue models could be quickly constructed by using a layer-by-layer (LbL) cell coating technique that assembles extracellular matrix (ECM) nanofilms to a cell surface. In this study, 3D human OMEs composed of lamina-propria, keratinized or non-keratinized epithelium, and blood capillaries were constructed by using the LbL cell coating technology. Human oral mucosal fibroblasts (HOMFs) were coated with ECM nanofilms and accumulated for the construction of oral mucosal lamina-propria. To construct OMEs with keratinized or non-keratinized epithelium, human oral keratinocytes isolated from gingiva (human oral gingival keratinocytes: HOGKs) or human oral keratinocytes isolated from oral mucosa (human oral mucosal keratinocytes: HOMKs) were used in this study. We further studied the construction of epithelialized OMEs with density- and size-controlled blood capillary networks by using human umbilical vein endothelial cells (HUVECs). It was revealed that these constructions had barrier functions in accordance with their histological characterization. The OMEs with keratinization (K-OMEs) showed higher transepithelial electrical resistance (TEER) values compared with OMEs with non-keratinization (N-OMEs). The constructed epithelialized OMEs with blood capillaries are useful for in vitro/ex vivo research models and regenerative medicine as in oral tissue regeneration. The results suggest that OMEs with oral tissue appendages are more promising alternatives to animal testing and can be applied to the design of in vitro oral models that mimic human tissue organs.

Antiphotoaging Effects of 3,5-Dicaffeoyl-epi-quinic Acid via Inhibition of Matrix Metalloproteinases in UVB-Irradiated Human Keratinocytes

UVB exposure is one of the causes of several skin complications including but not limited to premature aging, wrinkle formation, and hyperpigmentation. UV-induced skin aging is called photoaging, and oxidative stress-induced overexpression of matrix metalloproteinases (MMPs) is the main reason behind the photoaging-mediated collagen degradation. Natural origin inhibitors of MMPs are regarded as a promising approach to prevent or treat photoaging. Therefore, the present study investigated the protective effects of 3,5-dicaffeoyl-epi-quinic acid (DCEQA) in human HaCaT keratinocytes against UVB irradiation-related dysregulation of MMPs. Changes in the mRNA and protein expression and release of MMP-1, -2, and -9 were observed after UVB irradiation with or without DCEQA treatment. In addition, the effect of DCEQA on the activation of p38, JNK, and ERK MAPKs was analyzed. Treatment of UVB-irradiated HaCaT cells with 10 μM DCEQA significantly suppressed the overexpression of both mRNA and protein of MMP-1, -2, and -9 while slightly increasing the diminished type I procollagen production. UVB-induced activation of MAPKs was also ameliorated by DCEQA treatment in a dose-dependent manner. Results indicated that DCEQA treatment was able to protect keratinocytes from UVB-induced photoaging by inhibiting the stimulated production of MMPs and the related decrease in collagen production. It was suggested that DCEQA downregulated the collagen degradation via inhibition of MAPK activation, which resulted in decreased MMP activity.

Opuntiol Prevents Photoaging of Mouse Skin via Blocking Inflammatory Responses and Collagen Degradation

In the present study, we investigated the potential of opuntiol, isolated from Opuntia ficus-indica, against UVA radiation-mediated inflammation and skin photoaging in experimental animals. The skin-shaved experimental mouse was subjected to UVA exposure at the dosage of 10 J/cm² per day for ten consecutive days (cumulative UVA dose: 100 J/cm²). Opuntiol (50 mg/kg b.wt.) was topically applied one hour before each UVA exposure. UVA (100 J/cm²) exposure induces epidermal hyperplasia and collagen disarrangement which leads to the photoaging-associated molecular changes in the mouse skin. Opuntiol pretreatment prevented UVA-linked clinical macroscopic skin lesions and histological changes in the mouse skin. Further, opuntiol prevents UVA-linked dermal collagen fiber loss in the mouse skin. Short-term UVA radiation (100 J/cm²) activates MAPKs through AP-1 and NF-κB p65 transcriptional pathways and subsequently induces the expression of inflammatory proteins and matrix-degrading proteinases in the mouse skin. Interestingly, opuntiol pretreatment inhibited UVA-induced activation of iNOS, VEGF, TNF-α, and COX-2 proteins and consequent activation of MMP-2, MMP-9, and MMP-12 in the mouse skin. Moreover, opuntiol was found to prevent collagen I and III breakdown in UVA radiation-exposed mouse skin. Thus, opuntiol protects mouse skin from UVA radiation-associated photoaging responses through inhibiting inflammatory responses, MAPK activation, and degradation of matrix collagen molecules.

Senescent dermal fibroblasts negatively influence fibroblast extracellular matrix-related gene expression partly via secretion of complement factor D

Aging is associated with a decrease of extracellular matrix and an increase of senescent cells in the dermal layer. Here, to examine whether and how senescent cells are involved in aging-related deterioration of the dermal layer, we cocultured dermal young fibroblasts (low-passage number) with senescent cells (high-passage number) in Transwells, in which the two cell types are separated by a semipermeable membrane. Young fibroblasts in coculture showed decreased collagen type I alpha 1 chain and elastin gene expression, and increased matrix metalloproteinase 1 (MMP1) gene expression. To identify causative factors, we compared gene expression of young and senescent cells and selected candidate secretory factors whose expression was increased by ≥2.5 in senescent fibroblasts. Then, we used siRNAs to knock down each of the 11 candidate genes in senescent fibroblasts in the coculture system. Knockdown of complement factor D (CFD) in senescent fibroblasts significantly reduced the increase of MMP1 in the cocultured young fibroblasts. In monocultures, treatment of young fibroblasts with CFD resulted in increased MMP1 gene expression, while knockdown of CFD in senescent fibroblasts decreased MMP1 gene expression. In addition, production of CFD was increased in culture medium of untreated senescent fibroblasts. Furthermore, CFD gene and protein expression were increased in the dermal layer of skin specimens from aged subjects (>70 years old), compared to young subjects (<20 years old). Overall, these results suggest that senescent cells negatively influence matrix production and promote degradation of nearby fibroblasts in the dermal layer, in part through secretion of CFD.

Anti-Inflammatory Effect of ETAS®50 by Inhibiting Nuclear Factor-κB p65 Nuclear Import in Ultraviolet-B-Irradiated Normal Human Dermal Fibroblasts

Ultraviolet (UV) irradiation induces proinflammatory responses in skin cells, including dermal fibroblasts, accelerating premature skin aging (photoaging). ETAS 50, a standardized extract from the Asparagus officinalis stem, is a novel and unique functional food that suppresses proinflammatory responses of hydrogen peroxide-stimulated skin fibroblasts and interleukin- (IL-) 1β-stimulated hepatocytes. To elucidate its antiphotoaging potencies, we examined whether ETAS 50 treatment after UV-B irradiation attenuates proinflammatory responses of normal human dermal fibroblasts (NHDFs). UV-B-irradiated NHDFs showed reduced levels of the cytosolic inhibitor of nuclear factor-κB α (IκBα) protein and increased levels of nuclear p65 protein. The nuclear factor-κB nuclear translocation inhibitor JSH-23 abolished UV-B irradiation-induced IL-1β mRNA expression, indicating that p65 regulates transcriptional induction. ETAS 50 also markedly suppressed UV-B irradiation-induced increases in IL-1β mRNA levels. Immunofluorescence analysis revealed that ETAS 50 retained p65 in the cytosol after UV-B irradiation. Western blotting also showed that ETAS 50 suppressed the UV-B irradiation-induced increases in nuclear p65 protein. Moreover, ETAS 50 clearly suppressed UV-B irradiation-induced distribution of importin-α protein levels in the nucleus without recovering cytosolic IκBα protein levels. These results suggest that ETAS 50 exerts anti-inflammatory effects on UV-B-irradiated NHDFs by suppressing the nuclear import machinery of p65. Therefore, ETAS 50 may prevent photoaging by suppressing UV irradiation-induced proinflammatory responses of dermal fibroblasts.

The anti-photoaging and moisturizing effects of Bouea macrophylla extract in UVB-irradiated hairless mice

Ultraviolet (UV) light, a main cause of photoaging, leads to collapse of skin structure, resulting in wrinkle formation and dehydration. The present study assessed the anti-photoaging and moisturizing effects of Bouea macrophylla extract (BRE). UVB-irradiated hairless mice were orally administered with BME (300 mg/kg/day) for 8 weeks. BME ameliorated wrinkle formation, skin thickening, and inelasticity. BME upregulated COL1A1, COL3A1, COL4A1, and COL7A1 mRNA levels through activation of the transforming growth factor-β (TGF-β)/Smad pathway, thereby recovering the content of collagen reduced by UVB. Further, BME suppressed UVB-induced matrix metalloproteinase (MMP)-3 and MMP-13 expression and inhibited MMP-2 and MMP-9 activity by mediating the mitogen-activated protein kinases (MAPKs)/activator protein-1 (AP-1). BME improved moisture content by stimulating the expression of cornified envelope proteins and filaggrin-processing enzymes. Overall, the results show that BME prevents photoaging and promotes moisturization in UVB-irradiated hairless mice, suggesting its potential as a nutraceutical candidate for anti-photoaging and moisturizing effects.

The flavonoid hesperidin exerts anti-photoaging effect by downregulating matrix metalloproteinase (MMP)-9 expression via mitogen activated protein kinase (MAPK)-dependent signaling pathways

Background

Hesperidin is a flavonoid with antioxidant, anti-inflammatory, and immune modulatory activities. Photoaging is a consequence of chronic exposure to the sun and ultraviolet (UV) radiation. This study was designed to evaluate the efficacy of hesperidin against photoaging of dorsal skin in hairless mice.

Methods

Hairless male mice (6-week-old) were divided into three groups (n = 7): control, UVB-treated vehicle, and UVB-treated hesperidin groups. UVB-irradiated mice from hesperidin group were orally administered 0.1 mL of water containing 100 mg/kg body weight per day hesperidin.

Results

The mean length and depth of wrinkles in the UVB-treated hesperidin group significantly improved after the oral administration of hesperidin, which significantly inhibited the increase in epidermal thickness and epidermal hypertrophy (P < 0.05). UVB irradiation of mice induced epidermal barrier dysfunction including an increase in the transepidermal water loss (TEWL); however, hesperidin decreased the TEWL. UVB irradiation increased the expression of MMP-9 and pro-inflammatory cytokines whereas UVB-treated hesperidin group showed reduced expression. These results indicate that hesperidin showed anti-photoaging activity in the UVB-irradiated hairless mice. In conclusion, hesperidin inhibited the UVB-induced increase in skin thickness, wrinkle formation, and collagen fiber loss in male hairless mice.

Conclusions

These results suggest that hesperidin shows potent anti-photoaging activity by regulating MMP-9 expression through the suppression of MAPK-dependent signaling pathways.

Visualization of viscoelastic behavior in skin equivalent using optical coherence tomography-based straingraphy

BACKGROUND/PURPOSE

The relationships between the skin components and these mechanical roles are still unclear. To clarify these relationships, we investigated spatial mapping of the mechanical behavior of cultured skin equivalents (SEs) using optical coherence tomography (OCT)-based straingraphy.

METHODS

We built a strain relaxation test system combined with OCT and developed an algorithm that could visualize a time-dependent strain distribution, named dynamic-optical coherence straingraphy (D-OCSA). Using this system, we analyzed how the spatial mechanical changes in the SEs depended on the culture duration. For quantitative analysis of viscoelastic behavior, we defined a relaxation attenuation coefficient of strain rate, which indicates the ratio of viscosity and elasticity in the Klevin-Voight model.

RESULTS

By culturing for 4 days in comparison to culturing for 1 day, the strain relaxation attenuation coefficient of the whole skin, especially at the region of the dermal-epidermal junction (DEJ), significantly increased in the negative direction. In tissue slices taken for microscopy, several cracks were observed in the SEs cultured for 4 days.

CONCLUSION

This study is the first to provide quantified evidence that the DEJ is a dynamically specialized region. An OCT-based straingraphy system (D-OCSA) would be beneficial for evaluating the quality of SEs, as well as functional analysis of their mechanics.

Antioxidant and Skin Anti-Aging Effects of Marigold Methanol Extract

The objective of this study was to evaluate the antioxidant and anti-aging effects of marigold methanol extract (MGME) in human dermal fibroblasts. Total polyphenolic and flavonoid contents in MGME were 74.8 mg TAE (tannic acid equivalent)/g and 85.6 mg RE (rutin equivalent)/g, respectively. MGME (500 μg/mL) increased 1,1-diphenyl-2-picryl hydrazyl (DPPH) and 2,2′-azino-3-ethylbenzothiazoline-6-sulfonic acid (ABTS) radical-scavenging, and superoxide dismutase (SOD)-like antioxidant activities by 36.5, 54.7, and 14.8%, respectively, compared with the control. At 1,000 μg/mL, these activities increased by 63.7, 70.6, and 20.6%, respectively. MGME (100 μg/mL) significantly increased the synthesis of type 1 procollagen by 83.7% compared with control treatment. It also significantly decreased Matrix Metalloproteinase-2 (MMP-2) activity and MMP-1 mRNA expression by 36.5% and 69.5%, respectively; however, it significantly increased laminin-5 mRNA expression by 181.2%. These findings suggest that MGME could protect human skin against photo-aging by attenuating oxidative damage, suppressing MMP expression and/or activity as well as by stimulating collagen synthesis.

Protective effects of compounds from Garcinia mangostana L. (mangosteen) against UVB damage in HaCaT cells and hairless mice

Ultraviolet B (UVB) radiation causes alterations in the skin, such as epidermal thickening, wrinkle formation and inflammation. Therefore, preventing UVB-induced skin damage can promote general health among the human population. Garcinia mangostana L. (mangosteen) is a fruit that has become a popular botanical dietary supplement because of its perceived role in promoting overall health. The present study investigated the photoprotective effects of α-, β-, γ-mangostins and gartanin against UVB radiation using the HaCaT immortalized human keratinocyte cell line as an in vitro model and hairless mice as an in vivo model. UVB radiation increased the expression of matrix metalloproteinase (MMP)‑1 and ‑9 and decreased the mRNA expression levels of involucrin, filaggrin and loricrin in HaCaT cells; however, these changes were attenuated by pretreating the cells with α-, β-, γ-mangostins and gartanin. Among these compounds, α-mangostin exhibited the greatest effects in reducing UVB-induced skin wrinkles, inhibited epidermal thickening in hairless mice in vivo. Exposure to UVB radiation increased the expression of MMPs and pro-inflammatory cytokines and activated mitogen-activated protein kinases in hairless mice, but these changes were attenuated by α-mangostin. The authors suggested that α-mangostin exerts anti-wrinkle and anti-aging properties.

Heparanase Inhibitors Facilitate the Assembly of the Basement Membrane in Artificial Skin

Recent research suggests that the basement membrane at the dermal-epidermal junction of the skin plays an important role in maintaining a healthy epidermis and dermis, and repeated damage to the skin can destabilize the skin and accelerate the aging process. Skin-equivalent models are suitable for studying the reconstruction of the basement membrane and its contribution to epidermal homeostasis because they lack the basement membrane and show abnormal expression of epidermal differentiation markers. By using these models, it has been shown that reconstruction of the basement membrane is enhanced not only by supplying basement membrane components, but also by inhibiting proteinases such as urokinase and matrix metalloproteinase. Although matrix metalloproteinase inhibitors assist in the reconstruction of the basement membrane structure, their action is not sufficient to promote its functional recovery. However, heparanase inhibitors stabilize the heparan sulfate chains of perlecan (a heparan sulfate proteoglycan) and promote the regulation of heparan sulfate binding growth factors in the basement membrane. Heparan sulfate promotes effective protein-protein interactions, thereby facilitating the assembly of type VII collagen anchoring fibrils and elastin-associated microfibrils. Using both matrix metalloproteinase inhibitors and heparanase inhibitors, the basement membrane in a skin-equivalent model comes close to recapitulating the structure and function of an in vivo basement membrane. Therefore, by using an appropriate dermis model and suitable protease inhibitors, it may be possible to produce skin-equivalent models that are more similar to natural skin

How Does Chronic Cigarette Smoke Exposure Affect Human Skin? A Global Proteomics Study in Primary Human Keratinocytes

Cigarette smoking has been associated with multiple negative effects on human skin. Long-term physiological effects of cigarette smoke are through chronic and not acute exposure. Molecular alterations due to chronic exposure to cigarette smoke remain unclear. Primary human skin keratinocytes chronically exposed to cigarette smoke condensate (CSC) showed a decreased wound-healing capacity with an increased expression of NRF2 and MMP9. Using quantitative proteomics, we identified 4728 proteins, of which 105 proteins were overexpressed (≥2-fold) and 41 proteins were downregulated (≤2-fold) in primary skin keratinocytes chronically exposed to CSC. We observed an alteration in the expression of several proteins involved in maintenance of epithelial barrier integrity, including keratin 80 (5.3 fold, p value 2.5 × 10-7), cystatin A (3.6-fold, p value 3.2 × 10-3), and periplakin (2.4-fold, p value 1.2 × 10-8). Increased expression of proteins associated with skin hydration, including caspase 14 (2.2-fold, p value 4.7 × 10-2) and filaggrin (3.6-fold, p value 5.4 × 10-7), was also observed. In addition, we report differential expression of several proteins, including adipogenesis regulatory factor (2.5-fold, p value 1.3 × 10-3) and histone H1.0 (2.5-fold, p value 6.3 × 10-3) that have not been reported earlier. Bioinformatics analyses demonstrated that proteins differentially expressed in response to CSC are largely related to oxidative stress, maintenance of skin integrity, and anti-inflammatory responses. Importantly, treatment with vitamin E, a widely used antioxidant, could partially rescue adverse effects of CSC exposure in primary skin keratinocytes. The utility of antioxidant-based new dermatological formulations in delaying or preventing skin aging and oxidative damages caused by chronic cigarette smoke exposure warrants further clinical investigations and multi-omics research.

Enzyme-Treated Asparagus Extract Attenuates Hydrogen Peroxide-Induced Matrix Metalloproteinase-9 Expression in Murine Skin Fibroblast L929 Cells

Enzyme-treated asparagus extract (ETAS) exerts a wide variety of beneficial biological actions including facilitating anti-cortisol stress and neurological anti-aging responses. However, the anti-skin aging effects of ETAS remain to be elucidated. Reactive oxygen species (ROS) play pivotal roles in skin aging. Increased ROS levels in fibroblasts in response to ultraviolet irradiation activate c-Jun N-terminal kinase (JNK) and its downstream transcription factor activator protein-1 (AP-1), and the resultant gene expression of matrix metalloproteinase (MMP) isoforms accelerates collagen breakdown in the dermis. Therefore, we explored whether ETAS has anti-skin aging effects by attenuating the oxidative stress responses in fibroblasts. Simultaneous treatment of murine skin L929 fibroblasts with hydrogen peroxide (H2O2) and either ETAS or dextrin showed that ETAS significantly suppressed H2O2-induced expression of MMP-9 mRNA as measured by real-time polymerase chain reaction. ETAS also clearly suppressed H2O2-stimulated phosphorylation of c-Jun (AP-1 subunit) and JNK as determined by Western blot. However, ETAS did not affect the increased amounts of carbonyl proteins in response to H2O2, also as determined by Western blotting. These results suggest that ETAS diminishes cellular responsiveness to ROS but does not scavenge ROS. Thus, ETAS has the potential to prevent skin aging through attenuating the oxidative stress responses in dermal fibroblasts.

Collagen VII Half-Life at the Dermal-Epidermal Junction Zone: Implications for Mechanisms and Therapy of Genodermatoses

The tissue half-life of proteins largely determines treatment frequency of non-gene-editing-based therapies targeting the cause of genodermatoses. Surprisingly, such knowledge is missing for a vast number of proteins involved in pathologies. The dermal-epidermal junction zone is believed to be a rather static structure, but to our knowledge no detailed analysis of the stability of proteins within this zone has been performed. Here, we addressed the in vivo half-life of collagen type VII using genetic ablation of its expression and therapeutic introduction of exogenous collagen VII in a preclinical model. A similar in vivo stability of collagen VII was observed in the skin, tongue, and esophagus, with a half-life of about 1 month. Collagen VII expressed by intradermally injected mesenchymal stromal cells also exhibited a similar half-life. Our study provides key information needed for the development of protein replacement or cell-based therapies for dystrophic epidermolysis bullosa caused by genetic deficiency of collagen VII. Moreover, by showing what we define as an intermediate half-life of collagen VII, our study challenges the view of the dermal-epidermal junction zone as a static structure with very slow turnover.

Stimulatory effect of fibroblast-derived prostaglandin E₂ on keratinocyte stratification in the skin equivalent

Epidermal-dermal interaction plays important roles in physiological events such as wound healing. In this study, we examined a double paracrine mechanism between keratinocytes and fibroblasts through interleukin-1 (IL-1) and an IL-1-induced inflammatory mediator prostaglandin E₂ (PGE₂) using the skin equivalent. The epidermal layer of the skin equivalent expressed high levels of IL-1α mRNA (IL1A mRNA) and relatively low levels of IL-1β mRNA (IL1B mRNA). IL1A mRNA was not detected in fibroblasts. Fibroblasts also expressed low but not negligible levels of IL1B mRNA only in the presence of keratinocytes. Expression of prostaglandin-endoperoxide synthase 2 mRNA (PTGS2 mRNA) and production of PGE₂ in three-dimensionally cultured fibroblasts were noticeably stimulated by co-culture with keratinocytes, whereas PTGS2 mRNA expression in the epidermal layer was very low. In addition, hydroxyprostaglandin dehydrogenase 15-(NAD) mRNA was highly expressed in keratinocytes but not in fibroblasts, and exogenous IL-1β stimulated PTGS2 mRNA expression in the dermal equivalent. The thickness of the epidermal layer and the number of MKI67-positive keratinocytes in the skin equivalent were decreased by treatment with indomethacin, and the decrease recovered when exogenous PGE₂ was added. These results indicate that keratinocytes stimulate their own proliferation through a double paracrine mechanism mediated by IL-1 and PGE₂.

The development of hyperbaric oxygen therapy for skin rejuvenation and treatment of photoaging

Hyperbaric oxygen therapy (HBOT), a therapy that have patients breath in pure oxygen in a pressurized chamber, has been long used as a treatment for conditions such as decompression sickness and carbon monoxide poisoning. Oxygen recently has been found to be an important component in skin rejuvenation, treatment of photoaging skin, and improvement in skin complexions. The interest in the use of HBOT for this purpose is continually growing and becoming more widespread. In addition to aging and genetic makeup, chronic UV radiation due to everyday exposure, especially UV-B, can greatly increase the rate of wrinkle formation through increasing skin angiogenesis and degradation of extracellular matrix molecules. The use of HBOT and hyperoxia conditions has been found to attenuate the formation of wrinkles from UV irradiation. It accomplishes the task by possibly inhibiting various processes and pathways involved such as the HIF1-α, VEGF, neutrophil infiltrations, and MMP-2 & MMP-9, which are directly involved with promoting skin angiogenesis in its active state. There are currently medical aesthetic clinics that are using oxygen therapy under high pressure applied directly to skin to reduce visible wrinkles but this procedure is not widespread yet due to more research that needs to be done on this topic. However, this treatment for wrinkles is definitely growing due to recent studies done showing the effectiveness of oxygen therapy on wrinkles. This review article will explore and summarize researches done on possible mechanisms dealing with the use of oxygen therapy for reduction of UVB-caused wrinkles, its side effects, and its possible future improvement and use in medicine.

Effects of serially passaged fibroblasts on dermal and epidermal morphogenesis in human skin equivalents

Serial passaging has a profound effect on primary cells. Since serially passaged cells show signs of cellular aging, serial passaging is used as an in vitro model of aging. To relate the effect of in vitro aging more to in vivo aging, we generated human skin equivalents (HSEs). We investigated if HSEs generated with late passage fibroblasts show characteristics of aged skin when compared with HSEs generated with early passage fibroblasts. Late passage fibroblasts had enlarged cell bodies and were more often positive for myofibroblast marker α-smooth muscle actin, senescence associated β-galactosidase and p16 compared with early passage fibroblasts. Skin equivalents generated with late passage fibroblasts had a thinner dermis, which could partly be explained by increased matrix metalloproteinase-1 secretion. In equivalents generated with late passage fibroblasts epidermal expression of keratin 6 was increased, and of keratin 10 slightly decreased. However, epidermal proliferation, epidermal thickness and basement membrane formation were not affected. In conclusion, compared with HSEs generated with early passage fibroblasts, HSEs generated with late passage fibroblasts showed changes in the dermis, but no or minimal changes in the basement membrane and the epidermis.

Inhibition of UVB-induced wrinkle formation and MMP-9 expression by mangiferin isolated from Anemarrhena asphodeloides

Chronic exposure of human skin to solar ultraviolet (UV) radiation causes photoaging. Naturally occurring phytochemicals are known to have anti-photoaging effects. The present study examined the effect of mangiferin isolated from Anemarrhena asphodeloides on wrinkle formation, skin thickness, and changes in collagen fibers in hairless mice. The in vitro effects and possible mechanism of mangiferin on UVB irradiation were determined in human keratinocyte (HEKa) cells. In vitro results showed that mangiferin reduced UVB-induced matrix metalloproteinase (MMP)-9 protein expression and enzyme activity and subsequent attenuation of UVB-induced phosphorylation of mitogen-activated protein kinase kinase1 (MEK) and extracellular signal-regulated kinase (ERK). In the in vivo studies, mangiferin inhibited UVB-induced mean length and mean depth of skin wrinkle based on skin replica, epidermal thickening, and damage to collagen fiber. Taken together, these results indicate that mangiferin exerts anti-photoaging activity in UVB-irradiated hairless mice by regulating MMP-9 expression through inhibition of MEK and ERK.

Inhibitory effects of ethanol extracts from nuruk on oxidative stress, melanogenesis, and photo-aging

Nuruk contributes to the unique characteristics of Korean alcoholic beverages. In this study, the effects of nuruk extracts (NE) on anti-oxidant characters, melanogenesis, and anti-photoaging activity were investigated. NEs were obtained from the 70% ethanol extracts of six types of nuruk, which have been used in brewing of fermented alcohol beverages in Korea. First, various antioxidant characteristics were identified in terms of 2,2'-azino-bis(3-ethylbenzthiozoline-6-sulphonic acid) (ABTS) radical scavenging activity, superoxide dismutase (SOD) expression, and inhibition of xanthine oxidase activity. NE#4 exhibited potent ABTS radical scavenging activity (IC(50) = 19.51 µg/mL). Compared with NE#4, relatively lower levels of activity were observed for NE#3 and NE#6, with IC(50) values of 90.99 and 76.88 µg/mL, respectively. According to results of western blot analysis for determination of SOD expression in H(2)O(2)-treated HepG2 cells, NE#5 and NE#6 induced a dramatic increase in the expression ratio of SOD, compared to the group treated with H(2)O(2) only. Activity of xanthine oxidase, which converts xanthine into uric acid, generating superoxide ions, was inhibited by NE#4 and NE#6 in a dose-dependent manner. NE#4 induced significant inhibition of mushroom tyrosinase activity. A reduction in cellular melanin contents of 80% was observed in B16F1 melanocytes treated with NE#5 and NE#6; these effects were similar to those of arbutin at 100 µM. In addition, gelatin zymography and reverse transcription-PCR analysis were performed for assessment of anti-photoaging activity of Nuruk. Treatment with NE#6 resulted in dramatically inhibited activities of matrix metalloproteinase (MMP)-2/-9, suppressed expression of MMP-1, and increased expression of type-1 procollagen. Results of gelatin zymography for NE#4 and NE#5 were similar, to a slightly lesser degree. These results suggest the potential of NE#4 and NE#6 as natural ingredients for use in functional foods and cosmetics.

UV radiation-induced skin aging in hairless mice is effectively prevented by oral intake of sea buckthorn (Hippophae rhamnoides L.) fruit blend for 6 weeks through MMP suppression and increase of SOD activity

Oxidative stress and oxidative photodamage induced by UV radiation can cause serious skin damage that is characterized by wrinkling, roughness, laxity and pigmentation. The effects of a sea buckthorn (Hippophae rhamnoides L.) fruit blend (SFB) containing sea buckthorn fruit extract, blueberry extract and collagen on UV-induced skin aging were examined by treating hairless mice for 6 weeks with UV irradiation and SFB administered orally. The effects of SFB were measured in the skin of these mice by phenotypical and histological analysis and western blotting. According to wrinkle formation analysis, the oral intake of SFB induced a decrease in wrinkle formation in the damaged skin of UV-irradiated mice. The thickness of the epidermis and dermis in the vitamin extracts (Vit)- and SFB-treated group was lower than that in the vehicle-treated group, but the group treated with SFB50 was the most effective group. The mice treated with the Vit- or SFB solution maintained a normal moisture content through the inhibition of transdermal water loss (TEWL) and an increase in skin moisture content. Furthermore, the levels of matrix metalloproteinase (MMP) and collagen protein expression were assessed in five groups to examine the mechanisms underlying the effects of SFB oral intake. The application of SFB induced a decrease in MMP-1 and -9 expression to the levels observed in the vehicle-treated group, but MMP-9 expression showed a much larger decrease than MMP-1. Furthermore, the expression of collagen-1 in the skin corresponded to MMP expression except for the SFB30-treated group, whereas the superoxide dismutase (SOD) activity was increased dramatically in the SFB50-treated group. These results suggest that SFB has potential as a protective and therapeutic drug candidate against skin aging that functions by regulating the moisture content, MMP expression levels and SOD activity.

Key role of heparan sulfate chains in assembly of anchoring complex at the dermal-epidermal junction

Epidermal basement membrane forms anchoring complex composed of hemidesmosomes, anchoring filaments, lamina densa and anchoring fibrils to link epidermis to dermis. However, the anchoring complex is rarely formed in skin equivalent models, probably because of degradation of extracellular matrix (ECM) proteins and heparan sulfate chains by matrix metalloproteinases (MMPs) and heparanase, respectively. To explore the roles of ECM proteins and heparan sulfate in anchoring complex assembly, we used specific inhibitors of MMPs and heparanase, and the formation of anchoring complex was analysed in terms of polarized deposition of collagen VII, BP180 and β4 integrin at the dermal-epidermal junction (DEJ) by means of immunohistochemistry and transmission electron microscopy (TEM). The deposition of collagen VII was polarized to the basal side by the addition of MMP inhibitor, and the staining intensity was increased by combined treatment with MMP inhibitor and heparanase inhibitor, which enhanced anchoring fibril formation as observed by TEM. BP180 was polarized to the basal side by heparanase inhibitor, which protects HS chains, but not by MMP inhibitor. MMP inhibitor improved the polarization of β4 integrin. Hemidesmosomes were formed in the presence of each inhibitor, as observed by TEM, and formation was greatly enhanced by the combined treatment. These findings suggest that heparan sulfate chains, in addition to ECM proteins at the DEJ, play an important role in the assembly of anchoring complex, especially hemidesmosomes and anchoring fibrils.

Characterization of dense artificial connective tissues generated in a newly designed bioreactor

Dense connective tissues were generated simultaneously by accumulating collagen fibrils and fibroblasts on stainless steel mesh using a bioreactor system that we designed. The advantage of our system is that the artificial connective tissues can be generated within 24 hr in the absence of inhibitors against matrix metalloproteinases. The fibroblasts were suspended in 200 mL of Dulbecco's modified Eagle's medium containing 10% fetal bovine serum and 0.5 mg/mL type I collagen. The mixed solution was circulated in two types of bioreactors with cylindrical or vertical configurations to generate luminal or parenchymal tissues, respectively. The gelatin zymography showed that MMPs were first detected in the media after 8 hr from the start of circulation and reached the highest levels on day 3. Glossy white aggregates, 1-3 mm in thickness, depending on the circulation period, accumulated on mesh grids. Fibroblasts were embedded in the network of collagen fibrils and possessed oval nuclei with or without prominent cell processes to form a bipolar shape. We could not observe distended cisternae of the endoplasmic reticula, the Golgi apparatus, or exploded mitochondria, showing hypoxic degenerative alterations of fibroblasts in dense connective tissues. The artificial tissues generated by our system will be useful for biological studies and transplantation therapy.

Dynamic changes in matrix metalloproteinase 9 and tissue inhibitor of metalloproteinase 1 levels during wound healing in diabetic rats

BACKGROUND

We investigated the mechanism of delayed would healing caused by diabetes and measured the dynamic changes in matrix metalloproteinase 9 (MMP-9) and tissue inhibitor of metalloproteinase 1 (TIMP-1) levels. We noted differences in the ratio of MMP-9 to TIMP-1 in the wounds of diabetic and nondiabetic rats.

METHODS

Forty-two Sprague-Dawley rats weighing 250 g were randomly assigned to either the control group or the streptozotocin-induced diabetes group. Then, full-thickness excision wounds were created on the middle of the back of each animal. Skin biopsy specimens were obtained on days 0, 3, 7, and 14 after incision. The content of collagen was quantified by Masson's staining and the macrophage marker, and CD68 was detected by immunohistochemical analysis. Messenger RNA and protein expression of MMP-9 and TIMP-1 was measured by reverse transcriptase-polymerase chain reaction and Western blot, respectively.

RESULTS

Diabetic rats exhibited slower wound healing than control animals (P < .05). On days 3, 7, and 14 after incision, higher levels of MMP-9 messenger RNA and protein expression were detected in the diabetic group compared with the control group (P < .05), and expression of TIMP-1 messenger RNA and protein was significantly decreased. In addition, the ratio of MMP-9 to TIMP-1 was stable in controls, whereas there was a marked increase in the ratio in diabetic skin wounds.

CONCLUSIONS

The balance between MMP-9 and its inhibitor, TIMP-1, is disturbed in diabetic skin tissue after injury, which may lead to histologic abnormality of diabetic skin and delayed wound healing.

Myricetin suppresses UVB-induced wrinkle formation and MMP-9 expression by inhibiting Raf

Chronic exposure to solar ultraviolet (UV) light causes skin photoaging. Many studies have shown that naturally occurring phytochemicals have anti-photoaging effects, but their direct target molecule(s) and mechanism(s) remain unclear. We found that myricetin, a major flavonoid in berries and red wine, inhibited wrinkle formation in mouse skin induced by chronic UVB irradiation (0.18J/cm(2), 3 days/week for 15 weeks). Myricetin treatment reduced UVB-induced epidermal thickening of mouse skin and also suppressed UVB-induced matrix metalloproteinase-9 (MMP-9) protein expression and enzyme activity. Myricetin appeared to exert its anti-aging effects by suppressing UVB-induced Raf kinase activity and subsequent attenuation of UVB-induced phosphorylation of MEK and ERK in mouse skin. In vitro and in vivo pull-down assays revealed that myricetin bound with Raf in an ATP-noncompetitive manner. Overall, these results indicate that myricetin exerts potent anti-photoaging activity by regulating MMP-9 expression through the suppression of Raf kinase activity.

Two new lipoaminoacids with complementary modes of action: new prospects to fight out against skin aging

The mode of action of two cosmetic active ingredients (AIs), palmitoyl glycine (PG) and cocoyl alanine (CA) was studied with cDNA array experiments and quantitative PCR confirmations, which were performed on experimentally aged human fibroblasts. These preliminary studies revealed complementary profiles. Thus, specific supplementary investigations were then carried out for each AI. Protocols used were based either on in vitro models: (i) biochemical assays, (ii) monolayer cell culture (primary human fibroblasts and keratinocytes) and (iii) the model of capillary-like tube formation by human endothelial cells or on ex vivo models, i.e. topically treated skin explants and both immunohistochemical and Chromameter(TM) investigations. New prospects are proposed to fight out against skin aging. Indeed, PG and CA showed complementary properties and thus enabled a regulation or a restoration effect on main aging-associated disorders. Thus, they can not only act on tissue architecture, cell-cell interactions and extracellular matrix protection but also on inflammation, cell longevity, skin immune system protection, skin radiance and stem cell survey. Finally, a clinical trial performed on Caucasian women confirmed AI anti-wrinkle efficacy, which was superior to that of a market reference ingredient. In the future, complementary experiments enabling a better understanding of the aging-induced decline of epidermal stem cells would be of a great interest.

Coenzyme Q10 protects against oxidative stress-induced cell death and enhances the synthesis of basement membrane components in dermal and epidermal cells

Coenzyme Q10 (CoQ10), which has both energizing and anti-oxidative effects, is also reported to have antiaging action, e.g., reducing the area of facial wrinkles. However, the mechanism of its anti-aging activity is not fully established. Here, we examined the effect of CoQ10 on human dermal and epidermal cells. CoQ10 promoted proliferation of fibroblasts but not keratinocytes. It also accelerated production of basement membrane components, i.e., laminin 332 and type IV and VII collagens, in keratinocytes and fibroblasts, respectively; however, it had no effect on type I collagen production in fibroblasts. CoQ10 also showed protective effects against cell death induced by several reactive oxygen species in keratinocytes, but only when its cellular absorption was enhanced by pretreatment of the cells with highly CoQ10-loaded serum. These results suggest that protection of epidermis against oxidative stress and enhancement of production of epidermal basement membrane components may be involved in the antiaging properties of CoQ10 in skin.

Silybin from Silybum Marianum Seeds Inhibits Confluent-Induced Keratinocytes Differentiation as Effectively as Retinoic Acid without Inducing Inflammatory Cytokine

Retinoic acid (RA) has been effective for improving wrinkles. However, it has also been reported that RA induces skin irritation. In this study, we explored new botanical compounds that show RA-like activity, but do not induce inflammation in vitro. Keratinocytes were maintained in a confluent condition and induced differentiation. Under this condition keratinocytes were treated with many botanical extracts and their morphological change were observed and compared with RA-treated. We found that silybin, which is a major flavonolignan from Silybum Marianum seeds, induced RA-like morphological change and prevented differentiation. We showed that silybin, like RA, reduced the expression of keratinocyte terminal differentiation markers and stimulated the expression of basement membrane component proteins. In contrast, silybin, unlike RA, did not stimulate the secretion of IL-1α, which is a skin irritation mediator. These results suggest that silybin has RA-like activity on keratinocytes and has the potential to improve winkle without inducing skin irritation.