https://orcid.org/0000-0001-9789-0043
Abstract
Sosihotang (SSH) is an herbal medicine traditionally used against the common cold, and hepatic and gastric diseases, in Northeast Asia. In this study, we investigated whether SSH extract can protect against UVB-induced skin damage and photoageing.
HaCaT cells were treated with SSH extract and exposed UVB irradiation at 20 mJ/cm2. Hairless mice were orally administered SSH extract (100 mg/kg per mouse) as UVB irradiation was increased from 60 to 120 mJ/cm2 over the course of 12 weeks.
Treatment with SSH extract inhibited the upregulation of MMP-1 and MMP-9 expression in UVB-irradiated HaCaT cells. In UVB-irradiated hairless mice, treatment with SSH extract restored the levels of factors instrumental in skin hydration (TEWL, capacitance, HA and TGF-β) and those regulating collagen content (procollagen, MMP-1 and MMP-9). This activity inhibited epidermal thickening and disorganization of collagen fibres. Administration of SSH extract also ameliorated the expression of UVB-induced pro-inflammatory cytokines (TNF-α, IL-1β and IL-6) and phosphorylation of MAPK family members (MEK, JNK, ERK and p38) by upregulating the activity of antioxidant enzymes (SOD, CAT, Nrf-2, HO-1 and NQO-1).
These results indicate that SSH extract can be used therapeutically for the treatment of UVB-induced skin damage and photoageing.
Introduction
The major function of the skin is to protect the body and serve as a barrier against internal and external insults such as radiation, pathogens, mechanical damage and noxious substances.[1] Skin ageing is classified as intrinsic and extrinsic ageing; extrinsic ageing is superposed onto intrinsic ageing by exposure to pollution, cigarette smoke, and ultraviolet (UV) and infrared radiation.[2] Clinically, cellular senescence of the epidermis, dermis and hypodermis is affected by accumulated internal and environmental stressors, which eventually cause disorganization of the extracellular matrix (ECM) in the skin.[3]
Ultraviolet B (UVB) radiation alters epidermal morphology by increasing the thickness of stratum corneum (SC); alterations in the thickness of SC can cause an imbalance in permeability barrier and increase TEWL.[4] Hyaluronic acid (HA), a ubiquitous component of the ECM, plays critical roles in the maintenance of matrix stability and tissue hydration. UVB-induced depletion of HA in the dermis can contribute to skin ageing.[5] In dermal fibroblasts, UV irradiation upregulates the levels of MMP-1 via excessive generation of reactive oxygen species (ROS), thereby contributing to photoageing.[6]
The mechanism driving UV radiation-induced skin damage is regulated by a signalling pathway that involves mitogen-activated protein kinases (MAPKs) and pro-inflammatory cytokines.[7] In this process, UVB irradiation of the skin upregulates the release of pro-inflammatory factors, such as interleukin (IL) and tumour necrosis factor (TNF-α), from epidermal keratinocytes and dermal fibroblasts.[8] Thus, activation of the MAPK cascade plays a crucial role in UVB-induced skin damage.[9]
Sosihotang (SSH) is a traditional herbal medicine, widely used in the Northeast Asian countries for the treatment of fever, chills and vomiting caused by the common cold.[10,11] The SSH is comprised of seven medical herbs including Bupleurum root, Glycyrrhizae radix et rhizome, Ginseng radix, Pinellia tuber, Scutellaria root, Zingiberis rhizome crudus and Zizyphi fructus. In RAW 264.7 cells, SSH decreases the production of pro-inflammatory mediators by inhibiting activation of NF-kB. In mouse models of anorexia and cachexia, SSH alleviates cachexia-related symptoms by reducing muscle loss and systemic inflammation.[10] Although SSH is well-known for its pharmacological effects, its effects on skin ageing have not been evaluated.
In this study, we evaluated several factors involved in photoageing to assess the effects of SSH on hydration, wrinkle formation and inflammation in the skin of hairless mice subjected to UVB irradiation.
Materials and Methods
Preparation of Sosihotang extract
Sosihotang was obtained from pharmaceutical company (Hanpoong pharm Co. Ltd, Jeonju, Korea) produced in GMP facility where it is produced according to the drug regulation of Ministry of Food and Drug Safety (MFDS). The composition of SSH was described in Table 1.
Composition of Sosihotang
| Botanical name | Herbal name |
|---|---|
| Bupleurum falcatum L. | Bupleurum root |
| Panax ginseng C. A. Meyer | Ginseng root |
| Glycyrrhiza uralensis Fisch. | Glycyrrhiza radix |
| Zizyphus jujuba Mill. | Jujube fruit |
| Scutellaria baicalensis Georgi | Scutellaria radix |
| Pinellia ternata Breitenbach | Pinellia tuber |
| Zingiber officinale Roscoe | Ginger radix |
| Botanical name | Herbal name |
|---|---|
| Bupleurum falcatum L. | Bupleurum root |
| Panax ginseng C. A. Meyer | Ginseng root |
| Glycyrrhiza uralensis Fisch. | Glycyrrhiza radix |
| Zizyphus jujuba Mill. | Jujube fruit |
| Scutellaria baicalensis Georgi | Scutellaria radix |
| Pinellia ternata Breitenbach | Pinellia tuber |
| Zingiber officinale Roscoe | Ginger radix |
Composition of Sosihotang
| Botanical name | Herbal name |
|---|---|
| Bupleurum falcatum L. | Bupleurum root |
| Panax ginseng C. A. Meyer | Ginseng root |
| Glycyrrhiza uralensis Fisch. | Glycyrrhiza radix |
| Zizyphus jujuba Mill. | Jujube fruit |
| Scutellaria baicalensis Georgi | Scutellaria radix |
| Pinellia ternata Breitenbach | Pinellia tuber |
| Zingiber officinale Roscoe | Ginger radix |
| Botanical name | Herbal name |
|---|---|
| Bupleurum falcatum L. | Bupleurum root |
| Panax ginseng C. A. Meyer | Ginseng root |
| Glycyrrhiza uralensis Fisch. | Glycyrrhiza radix |
| Zizyphus jujuba Mill. | Jujube fruit |
| Scutellaria baicalensis Georgi | Scutellaria radix |
| Pinellia ternata Breitenbach | Pinellia tuber |
| Zingiber officinale Roscoe | Ginger radix |
Cell culture and UVB irradiation
HaCaT, an immortalized non-tumorigenic line of human keratinocytes, was cultured in Dulbecco’s modified Eagle’s medium (DMEM; Gibco, Rockville, MD, USA) supplemented with 10% fetal bovine serum and 1% antibiotics (100 units/ml penicillin and 100 μg/ml streptomycin; Gibco) at 37 °C and 5% CO2 in a humidified incubator. HaCaT cells were seeded cell culture plates and allowed to adhere for 24 h. The cells were then treated with SSH extract at various concentrations and exposed to UVB radiation at a dose of 20 mJ/cm2. Cells that received no pretreatment and were not exposed to UVB irradiation served as controls. After irradiation with UVB, the levels of MMP-1 and MMP-9 in HaCaT cells were determined using total MMP-1 and MMP-9 ELISA kits (R&D Systems, Minneapolis, MN, USA), respectively.
Animal procedures and oral administration of SSH
All procedures involving animals were approved by the Korea Institute of Oriental Medicine Institutional Animal Care and Use Committee (16-059). Male hairless mice (Hos/HR-1, 6 weeks old), purchased from Japan SLC, Inc. (Shizuoka, Japan), were housed in a temperature-controlled room at 24 °C and 50% humidity at a 12: 12-h light/dark cycle. The mice were acclimatized for 1 week before the study and were provided access to food and water ad libitum. The mice were divided into three groups (n = 6 per group) as follows: control, UVB-irradiated vehicle-treated and UVB-irradiated SSH extract-treated groups. The UVB-irradiated SSH extract-treated group was orally administered 0.1 ml (100 mg/kg per mouse) of SSH extract (5 days a week for 12 weeks). The mice in the vehicle group were orally administered drinking water, whereas those in the unexposed control group did not receive any treatment.
UVB irradiation in mice
This experiment was used to examine the effect of orally administered SSH extract on the dorsal skin of UV-irradiated mice. Mice were irradiated at 48-h intervals for 12 weeks using a UVM-225D Mineralight UV Display Lamp (UVP, Phoenix, AZ, USA). The magnitude of irradiation progressively increased from 60 mJ/cm2 per exposure at week 1 (one minimal erythematous dose = 60 mJ/cm2) to 120 mJ/cm2 at week 9.
Evaluation of TEWL and capacitance, and histological examination
TEWL was measured using Tewameter TM 300 (Courage and Khazaka Electronics, Cologne, Germany) equipped with a probe, which was applied to the surface of mouse skin. Electrical capacitance at skin surface was measured using a Corneometer (Courage and Khazaka Electronics). After the mice were euthanized via CO2 asphyxiation, samples of dorsal skin were harvested, fixed in 10% neutral buffered formalin, embedded in paraffin, sectioned at 5 μm and stained with haematoxylin and eosin (H&E). Masson’s trichrome staining was used to visualize collagen fibres. Epidermal thickness was measured via light microscopy using an eyepiece micrometer (Olympus, Tokyo, Japan).
Preparation of skin lysates
After the dorsal skin of the mice was harvested, the fat was dissected out, and the skin was immediately pulverized in liquid nitrogen using a mortar and pestle. The pulverized skin was homogenized on ice with a Precellys®24 tissue homogenizer (Bertin Instruments, Montigny-le-Bretonneux, France). Subsequently, proteins were extracted using 20% SDS solution containing 1 mm phenylmethylsulfonyl fluoride (PMSF), 10 mm iodoacetamide, 1 mm leupeptin, 0.1 mm sodium orthovanadate and 5 mm sodium fluoride. The obtained lysates were centrifuged at 18 214 g (18 214 rcf)for 10 min at 4 °C, and protein content in the supernatant was determined using a Bio-Rad protein assay kit (Bio-Rad, Hercules, CA, USA).
Western blotting
Lysates, prepared using 100 µg mouse dorsal skin from which the fat had been removed, were centrifuged at 18 214 g for 10 min at 4 °C. Aliquots of the supernatant, containing 20 µg total protein, were subjected to sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE; 10% resolving gel). The proteins were then electroblotted onto nitrocellulose membranes, and membranes were blocked by incubation in TBS-T (0.1% Tween 20) containing 5% BSA. The membranes were then incubated with the following primary antibodies: anti-MMP-1, anti-MMP-9, anti-pro-collagen, anti-haem oxygenase-1 (HO-1), anti-nuclear factor (erythroid-derived 2)-like 2 (Nrf-2), anti-NADPH quinone oxidoreductase-1 (NQO-1), anti-phospho-ERK, anti-phospho-MEK, anti-phospho-p38, anti-phospho-JNK, anti-MEK, anti-ERK, anti-p38 and anti-JNK (Cell Signaling Technology, Danvers, MA, USA). The membranes were then washed with TBS-T and incubated with horseradish peroxidase (HRP)-conjugated secondary antibodies (Cell Signaling Technology). Proteins were detected using enhanced chemiluminescence (ECL solution; Bio-Rad) followed by imaging on ImageQuant LAS 4000 equipment (GE Healthcare Life Sciences, BKM, England).
RNA extraction and quantitative real-time polymerase chain reaction
Total RNA was extracted from UVB-irradiated mouse skin using TRIzol in accordance with the manufacturer’s protocol (Invitrogen, Carlsbad, CA, USA). Expression levels of IL-1β, IL-6 and TGF-β were determined via quantitative real-time polymerase chain reaction (qRT-PCR) using TaqMan (Applied Biosystems, Foster City, CA, USA) on a QuantStudio™ 6 Flex Real-Time PCR system (Applied Biosystems). Each sample was assayed in triplicate, and relative mRNA expression levels were normalized to those of β-actin mRNA using the method.
Activity of antioxidant enzymes
The activity of superoxide dismutase (SOD) and catalase (CAT) was measured using a colorimetric assay kit (Cayman Chemical Co., Ann Arbor, MI, USA) in accordance with the manufacturer’s protocol. For protein extraction, skin tissue was homogenized in cold lysis buffer. Absorbance was measured at 450 nm to determine SOD activity and at 540 nm to determine CAT activity, using a plate reader (Molecular Devices, Sunnyvale, CA, USA).
Expression levels of MMP-1, MMP-9, HA and TNF-α as assessed by ELISA
Expression levels of MMP-1, MMP-9 and HA in the mouse skin post-irradiation with UVB were determined using total MMP-1, MMP-9, HA and TNF-α ELISA kits (R&D Systems), respectively, in accordance with the manufacturer’s instructions. The levels of MMP-1, MMP-9, HA and TNF-α were quantified via colorimetric analysis using a plate reader (Molecular Devices).
Statistical analysis
All parameters were measured in triplicate, and all data are presented as the mean ± standard error of the mean (SEM). All variables were assessed via analysis of variance (ANOVA), followed by Tukey’s multiple comparison test to analyse the differences between groups, and P < 0.05 was considered statistically significant.
Results
Effects of SSH extract on UVB-induced overexpression of MMP-1 and MMP-9
To evaluate the effect of SSH extract on the expression of MMPs, we used an ELISA immunoassay to analyse the level of MMP-1 and MMP-9 released into the culture media of UVB-irradiated HaCaT cells. The expression of MMP-1 and MMP-9, which was markedly upregulated by UVB irradiation, was decreased significantly by treatment with SSH (Figure 1). These results indicate that SSH extract can provide protection against UVB-induced photoageing.
Effects of SSH extract on MMP-1 and MMP-9 expression in HaCaT cells after UVB irradiation. HaCaT cells were pretreated with the indicated concentrations of SSH extract for 24 h, followed by UVB irradiation. Data are reported as percentages. #P < 0.05 for the comparison with the control group and *P < 0.05 for the comparison with the vehicle group.
Effect of SSH extract on epidermal thickness and composition in UVB-irradiated hairless mice
To determine whether SSH could protect the skin against the effects of photoageing in vivo, hairless mice were orally administered SSH extract during a course of UVB irradiation. Histological analysis of H&E-stained skin sections showed that SSH exerted protective effects against UVB-induced epidermal changes (Figure 2a). Epidermal thickness of the UVB-exposed group treated with SSH extract was 33.8 µm compared with the thickness of 49.1 µm observed in the UV-exposed group treated with vehicle (Figure 2c). Masson’s trichrome staining showed that the skin of UVB-exposed group treated with vehicle contained lower collagen fibre abundance and density than those of the control group. These changes were alleviated by treatment with the SSH extract (Figure 2b). These results show that treatment with SSH extract preserved epidermal thickness and collagen integrity, and indicate that SSH extract can be used as an effective photoprotective agent.
Effect of treatment with SSH extract on UVB-induced skin thickening of hairless mice. (a) Haematoxylin and eosin staining of UVB-irradiated skin of hairless mice. Original magnification: ×400. (b) SSH extract prevented changes in collagen fibres, as shown by histological analysis of hairless mouse skin via Masson’s trichrome staining. Collagen fibres are shown in blue, and images were obtained at a magnification of × 400. (c) Epidermal thickness in dorsal skin. Original magnification, ×400. ###P < 0.001 for the comparison with the control group and ***P < 0.001 for the comparison with the vehicle group. Scale bar: 20 µm.
Effect of SSH extract on skin hydration
TEWL was higher in the UVB-exposed vehicle-treated group (4.63 g/m2 per h) than in the normal group (1.93 g/m2 per h); this effect, however, was ameliorated in the UVB-exposed group treated with SSH extract (Figure 3a). Furthermore, irradiation with UVB decreased the hydration of the stratum corneum. However, the UVB-exposed group treated with SSH exhibited increased skin capacitance compared with that of UVB-exposed group treated with vehicle (P < 0.01; Figure 3b). Moreover, the levels of HA and TGF-β were markedly increased in the skin of UVB-exposed group treated with SSH extract compared with those of the UVB-exposed group treated with vehicle (Figure 3c and 3d). These results indicate that treatment with SSH extract increased the level of skin hydration and alleviated the damage associated with increased TEWL.
Effects of SSH extract on skin hydration in UVB-irradiated hairless mice. (a) Transepidermal water loss and (b) capacitance in UVB-irradiated hairless mice after administration of SSH extract over the course of 10 weeks. (c) Hyaluronan levels in skin tissue and (d) TGF-β mRNA levels in skin tissue. ###P < 0.001 and #P < 0.05 for the comparison with the control group and ***P < 0.001 and **P < 0.01 for the comparison with the vehicle group.
SSH extract inhibits UVB-induced overexpression MMP-1 and MMP-9
Ultraviolet B irradiation upregulated the levels of MMP-1 and MMP-9 in the skin of hairless mice. We analysed the levels of MMP-1 and MMP-9 using ELISA, which showed that treatment with SSH extract downregulated the levels of MMP-1 and MMP-9 that had been increased by UVB irradiation (Figure 4a and 4b). Consistently, protein expression of MMP-1 and MMP-9 was also downregulated in the UVB-irradiated group treated with SSH extract compared with the levels observed in the UVB-irradiated group treated with vehicle (Figure 4c, middle panel). Furthermore, protein expression of procollagen, reduced by irradiation with UVB, was rescued by treatment with SSH extract (Figure 4c, upper panel). These results indicate that treatment with SSH extract significantly downregulated the UVB-induced overexpression of MMP-1 and MMP-9.
Effect of SSH extract on MMP and procollagen expression. (a) MMP-1 and (b) MMP-9 protein levels in UVB-irradiated skin of hairless mice. (c) Western blot was used to analyse the effects of SSH extract on UVB-mediated degradation of procollagen by MMP-1 and MMP-9. ####P < 0.0001 and ###P < 0.001 for the comparison with the control group and ****P < 0.0001 and ***P < 0.001 for the comparison with the vehicle group.
Effects of SSH extract on antioxidant activity of UVB-irradiated hairless mice
To evaluate whether SSH extract possesses free radical-scavenging ability, we examined the activity of the antioxidant enzymes SOD and CAT in UVB-induced hairless mice. The activity of SOD, which was lower in the UVB-irradiated group treated with vehicle than in the unexposed control group, was rescued in the UVB-irradiated group treated with SSH extract (Figure 5a). Consistently, the activity of CAT, decreased by UVB irradiation, was increased by treatment with SSH extract (Figure 5b). We also assessed the Nrf-2-dependent antioxidant activity of SSH extract. Protein expression of HO-1, Nrf-2 and NQO-1, which was suppressed in UVB-irradiated group treated with vehicle, was restored in the UVB-irradiated group treated with SSH extract. These results indicate that SSH extract rescued the activity of free radical-scavenging antioxidant enzymes, thereby inhibiting UVB-induced oxidative stress.
Effects of SSH extract on the antioxidant activity of (a) superoxide dismutase and (b) catalase in the skin of hairless mouse exposed to UVB. (c) Protein levels of antioxidant-related protein-containing haem oxygenase (HO)-1, Nrf-2 and NADPH quinone oxidoreductase (NQO)-1 as assessed using Western blotting. ####P < 0.0001 and #P < 0.05 for the comparison with the control group and ****P < 0.0001 and *P < 0.05 for the comparison with the vehicle group.
Effects of SSH extract on inflammatory cytokines
We examined the expression of pro-inflammatory cytokines to assess whether SSH extract could mediate the expression of these factors in the skin of UVB-irradiated hairless mice. As shown in Figure 6, mRNA levels of IL-1β and IL-6 and expression of TNF-α were increased in the skin of UVB-irradiated group treated with vehicle compared with those of the unexposed control group. Interestingly, the increased expression of IL-1β, IL-6 and TNF-α was decreased by treatment with SSH extract. These data indicate that SSH extract can protect against the photoageing, induced by UVB irradiation, by reducing inflammatory responses.
Effects of SSH extract on the expression of pro-inflammatory cytokines in UVB-irradiated skin of hairless mice. The mRNA expression levels of (a) IL-1β and (b) IL-6 were determined by qRT-PCR. (c) The expression levels of TNF-α were analysed by ELISA. ####P < 0.0001 and ###P < 0.001 for the comparison with the control group and ****P < 0.0001, *** P < 0.001 and **P < 0.01 for the comparison with the vehicle group.
Effect of SSH extract on MAPK phosphorylation in UVB-exposed hairless mice
We examined the effect of UVB irradiation on activation of the MAPK signalling cascade. As shown in Figure 7, UVB irradiation induced the phosphorylation of MEK, ERK, p38 and JNK, whereas treatment with SSH extract suppressed this effect. These data suggest that SSH extract prevented UVB-induced skin damage by downregulating activation of the MAPK signalling cascade.
SSH extract inhibits the phosphorylation of mitogen-activated protein kinase (MAPK), MEK, ERK, p38 and JNK in hairless mice irradiated with UVB.
Discussion
Photoageing, also called extrinsic ageing, is commonly induced by external stimuli such as UV radiation, environmental toxins and infectious agents.[12,13] Repetitive exposure to UV radiation accelerates skin ageing and leads to wrinkling, the most obvious symptom of ageing.[14] In the dermis, disruption of the ECM structure stemming from reduced levels of collagen, elastic fibres, and HA, results in formation of fine wrinkles.[15] In this study, we examined the effects of SSH, a traditional herbal medicine widely used in Northeast Asia, against photoageing of the skin induced by UVB irradiation.
Chronic exposure to UV radiation causes changes in the structure of epidermis and dermis.[16] The dermis, which is located under the epidermis, contains fibroblasts and ECM components such as HA, proteoglycans, elastin fibres, collagens and fibronectin.[17] The stratum corneum (SC) is the outermost layer of the epidermis and is composed of dead cells called corneocytes. A recent study on dermal dehydration has shown that reduction in the moisture content of the SC is likely caused by its decreased ability to bind and retain water.[18] SC plays a critical role is skin barrier function, protecting the deeper-lying layers, preventing water loss, retaining adequate water content, and preventing overhydration.[19] Baseline TEWL increases with age, likely due to reduced water content in aged skin.[20] Treatment with SSH extract, examined in this study, effectively reduced the TEWL, which had been increased by UVB irradiation, thereby restoring adequate levels of skin hydration and preventing skin damage. Furthermore, the levels of HA and TGF-β, which are the markers of skin hydration, were upregulated in UVB-irradiated mice treated with SSH extract compared to with those of UVB-irradiated mice treated with vehicle.
The transcription factor TGF-β promotes secretion of procollagen by dermal fibroblasts, which is also regulated by MMP-1.[21] Collagen degradation and damage are commonly observed in photoageing; hence, upregulation of MMP expression is a hallmark of UV-induced skin injury.[22] Consistently, our results indicate that UVB irradiation downregulated procollagen production, and upregulated the levels of MMP-1 and MMP-9; these effects of UVB irradiation were ameliorated by SSH extract.
In dermal fibroblasts, UVB irradiation stimulates excessive generation of ROS, which plays a critical role in photoageing by increasing the synthesis and expression of MMPs.[23] Oxidative stress in the skin is caused by UV exposure and is one of the most important risk factors for developing skin conditions such as wrinkles.[24] Following UV exposure, ROS trigger the release of growth factors and pro-inflammatory cytokines.[25] Nrf-2 regulates the expression of antioxidative and detoxifying factors, such as HO-1, SOD and CAT, in human skin; hence, Nrf-2 is one of the key components of the endogenous antioxidant system.[26] NQO-1, another important antioxidant enzyme, suppresses ROS production in keratinocytes.[27] The results of our present study indicate that SSH extract preserved the activity of SOD, CAT, HO-1, NQO-1 and Nrf-2, thereby inhibiting UVB-induced oxidative stress.
Upregulation of inflammation-related markers, such as that of TNF-α and IL-6, is observed in most ageing-associated diseases.[28] Keratinocytes, which are a major target of UVB, play a central role in inflammatory and immunomodulatory cascade in the skin by secreting pro-inflammatory cytokines including IL-1, IL-6 and TNF-α.[29] The results obtained in this study observed that treatment with SSH extract inhibited the release of inflammatory mediators, such as IL-1β, IL-6 and TNF-α, in the skin of UVB-irradiated hairless mice.
UV-induced ROS production is particularly effective at activating MAPK cascades, and increased phosphorylation of p38, JNK, MEK and ERK, in turn, upregulates ROS production to induce the chronic, low-grade inflammation known as inflammaging.[30] The transcription of c-Jun and c-Fos is directly and indirectly regulated by transcription factors that are largely dependent on activation of the MAPK pathways.[31] Our results show that administration of SSH extract inhibited the activation of p38, JNK, MEK and ERK pathways induced by UVB irradiation.
The nutricosmetics are the latest trend in the skin care and cosmetic industry; thus, recent studies are more focused on nutricosmetics rather than general cosmetics for topical treatment.[32,33] Many studies are reported that oral supplementation of natural molecules has the properties of anti-ageing, antioxidant, antimicrobial and antiseptic.[32,33] Vitamin E concentration in the skin is significantly increased by oral administration for 8 weeks, and UV-induced skin damage is more restored by vitamin C and E administration than vitamin C alone.[34,35] Cooperstone et al. reported that a prolonged consumption of tomato could ameliorate UV-induced skin sunburn, and Haruta-Ono et al. reported that orally administered sphingomyelin improved the water-holding capacity and barrier function in the skin.[36,37] Similarly, this study also showed that oral administration of SSH improved a skin health by maintaining homeostasis and providing protection against UV-induced photodamage.
Conclusions
In this study, we determined that treatment with SSH extract can protect against UVB-induced photodamage in vitro and in vivo. In vitro, treatment with SSH extract inhibited the upregulation of MMP-1 and MMP-9 expression in UVB-irradiated HaCaT cells. In vivo, administration of SSH extract restored the levels of skin hydration markers and factors regulating collagen synthesis; this activity inhibited skin thickening and disorganization of collagen fibres in hairless mice subjected to UVB irradiation. Moreover, treatment with SSH extract attenuated overexpression of UVB-induced pro-inflammatory cytokines and prevented MAPK phosphorylation by upregulating the activity of antioxidant enzymes. Thus, our results indicate that SSH extract can provide protection against UVB-induced skin damage and photoageing.
Declarations
Conflict of interest
The authors have no conflict of interest to declare.
Funding
This study was supported by grant from the Korea Institute of Oriental Medicine (K18300).
References
Author notes
A-Rang Im and Kon-Young Ji are contributed equally to this work.
