Aster glehni Extract Containing Caffeoylquinic Compounds Protects Human Keratinocytes through the TRPV4-PPARδ-AMPK Pathway

Hindawi Evidence-Based Complementary and Alternative Medicine Volume 2018, Article ID 9616574, 13 pages https://doi.org/10.1155/2018/9616574 Research Article Aster glehni Extract Containing Caffeoylquinic Compounds Protects Human Keratinocytes through the TRPV4-PPAR𝛿-AMPK Pathway Yong-Jik Lee ,1 Yoo-Na Jang,1 Yoon-Mi Han,1 Hyun-Min Kim,1,2 Changbae Jin ,3 Hyoung Ja Kim ,3 and Hong Seog Seo 1,2 1 Cardiovascular Center, Korea University Guro Hospital, 148, Gurodong-ro, Guro-gu, Seoul 08308, Republic of Korea Department of Medical Science, Korea University College of Medicine (BK21 Plus KUMS Graduate Program), Main building 6F Room 655. 73, Inchon-ro (Anam-dong 5-ga), Seongbuk-gu, Seoul 136-705, Republic of Korea 3 Molecular Recognition Research Center, Materials and Life Science Research Division, Korea Institute of Science and Technology, Hwarangno 14 gil 5, Seoul 136-791, Republic of Korea 2 Correspondence should be addressed to Hyoung Ja Kim; and Hong Seog Seo; Received 29 August 2018; Revised 21 October 2018; Accepted 12 November 2018; Published 9 December 2018 Academic Editor: Simona Martinotti Copyright © 2018 Yong-Jik Lee et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Aster glehni (AG) has been used in cooking and as a medicine to treat various diseases for over hundreds of years in Korea. To speculate the protective effects of AG on skin barrier, we estimated the protein levels of biomarkers related to skin barrier protection in human keratinocytes, HaCaT cells treated with sodium dodecyl sulfate (SDS), or 2,4-dinitrochlorobenzene (DNCB). The protein levels for keratin, involucrin, defensin, tumor necrosis factor alpha (TNF𝛼), peroxisome proliferator-activated receptor delta (PPAR𝛿), 5󸀠 adenosine monophosphate-activated protein kinase (AMPK), serine palmitoyltransferase long chain base subunit 2 (SPTLC2), and transient receptor potential cation channel subfamily V member 4 (TRPV4) were evaluated using western blotting or immunocytochemistry in HaCaT cells. AG extract increased the protein levels of PPAR𝛿, phosphorylated AMPK, SPTLC2, keratin, involucrin, and defensin compared to the SDS or DNCB control group. However, TNF𝛼 expression increased by SDS or DNCB was decreased with AG extract. The order of action of each regulatory biomarker in AG pathway was identified TRPV4󳨀→PPAR𝛿 󳨀→AMPK from antagonist and siRNA treatment studies. AG can ameliorate the injury of keratinocytes caused by SDS or DNCB through the sequential regulation of TRPV4󳨀→PPAR𝛿 󳨀→AMPK pathway. 1. Introduction The skin, also called integument, consists of three major layers, namely epidermis, dermis, and hypodermis (subcutis). In particular, the epidermis is the outer region of the skin and has four layers—stratum basale, stratum spinosum, stratum granulosum, and stratum corneum (the outermost thin layer of the skin). Keratinocytes are the main cells that make up the epidermis, and they contribute to the construction of a defense wall for the body through keratinization. In stratum spinosum, keratinocytes produce keratin1 and 10, and keratin10 is a main constituent of desmosome. In general, the permeability barrier of skin is provided by stratum corneum and is composed of corneocytes, cornified envelope, corneodesmosome, and intercorneocyte lipid. The cornified envelope comprises transglutaminase, involucrin, loricrin, and filaggrin, and it serves as a complete permeability barrier through the formation of the multilayered structure of intercorneocyte lipid. Interconeocyte lipids comprise ceramide, cholesterol, free fatty acids, and cholesterol sulfate, and, among them, ceramide content is the highest. The main functions of the skin are to prevent the loss of body fluids, attack of toxins, and invasion of pathogens [1–3]. Therefore, the impairment of skin permeability barrier function is not a simple mechanical destruction of the outer layer of the skin. The damaged skin can cause severe immune reactions through the invasion and colonization of various pathogens. Sodium dodecyl sulfate (SDS) is generally known as a skin 2 Evidence-Based Complementary and Alternative Medicine irritant as well as an anionic surfactant. As a detergent, SDS induces skin surface polarity and skin barrier disruption and can facilitate epidermal lipid extraction [4]. In addition, SDS elevates transepidermal water loss from the stratum corneum and induces inflammation [5, 6]. Although atopic dermatitis (AD) develops in early infancy, it is also seen in adults. In general, AD is a chronic and pruritic inflammatory skin disease characterized by increased immunoglobulin E (IgE) production, relapsing eczematous skin lesions, infiltration of inflammatory immune cells, and defective skin barrier, and its underlying cause is almost unknown [7, 8]. With the advancement of industrialization, AD has become more prevalent. Therefore, finding effective remedies for AD is very urgent and socioeconomically important. 2,4-Dinitrochlorobenzene (DNCB) is reported to induce contact dermatitis and AD [9, 10]. Aster glehni (AG) has been used as an edible food, and medicine for over hundreds of years in Korea. In Korean traditional medicine, Aster glehni (AG) has been used to cure fever, pain, phlegm, and cough. Other functions of AG have been reported previously as follows. An ethyl acetate extract of AG inhibited the protein expression of tyrosinase and tyrosinase-related protein 1, which are involved in melanin biosynthesis in melanocytes [11]. In another study, the ethyl acetate extract of AG showed antioxidant effect and inhibited the protein expression of induced nitric oxide synthase (iNOS), which is involved in inflammation [12]. To clarify the effects and mechanism of AG on skin permeability barrier protection, we estimated the expression levels of biomarkers related to permeability barrier maintenance in HaCaT cells treated with SDS or DNCB which is a skin irritant or an inducer of dermatitis containing atopic dermatitis. Particularly, in previous studies, peroxisome proliferator-activated receptor 𝛿 (PPAR𝛿), AMP-activated protein kinase (AMPK), and transient receptor potential cation channel subfamily V member 4 (TRPV4) participated in the maintaining of structural integrity of keratinocytes [13–17] , and in general the impairment of skin permeability barrier mainly composed by keratinocytes induces dermatitis containing atopic dermatitis [18, 19]. Therefore this study was conducted with a focus on the roles of PPAR𝛿, AMPK, and TRPV4 as the regulators in the functions of AG. Waters, Worcester, MA, USA). Separation was performed using a Luna C18 column (5 𝜇m, 250 × 4.6 mm, Phenomenex, Torrance, CA, USA) with a sample injection volume of 10 𝜇L at 30∘ C. The mobile phase was a gradient of acetonitrile and 1% phosphoric acid. The gradient system was a (...truncated)