Skin is the outermost organ and acts as a barrier between the organism and environment. Skin protects the organism from environmental insults, such as chemicals, pathogens, and UV light. Much of the protective function of skin is dependent on the epidermis, a multi-layered epithelium that is composed of various cell types such as keratinocytes and melanocytes. Keratinocytes produce protective components through a sophisticated differentiation process. Disturbance of keratinocyte differentiation is related to several skin diseases such as psoriasis and atopic dermatitis. In this study, we prepared extract of combined medicinal plants (ECMP) consisting of Taraxacum platycarpum H. Dahlstedt, Heartleaf Houttuynia, Glycyrrhiza uralensis Fischer, and root bark of Ulmus davidiana. We demonstrated that ECMP enhanced keratinocyte differentiation and barrier functionality using an in vitro cell culture system and in vivo animal test. Treatment of cultured keratinocytes with ECMP resulted in induction of keratinocyte differentiation, as evidenced by increased differentiation markers such as involucrin, loricrin, and filaggrin. In line with these results, ECMP decreased proliferation of keratinocytes cultured in vitro. ECMP applied topically to tape-stripped mouse skins accelerated reduction of transepidermal water loss (TEWL), indicating fast recovery of barrier function. Immunohistochemistry showed that ECMP increased the filaggrin level in tape-stripped mouse skins. These results suggest that ECMP may be applicable for keratinocyte differentiation-related skin diseases.

Extensive oral mucosa loss from a variety of conditions is associated with significant functional morbidity and mortality. Although it is known that keratinocytes are a rich source of wound healing promoting factors such as transforming growth factor-β1(TGF-β1), it is not clear whether differentiated keratinocytes in a multi-layer form release this multi-functional growth factor. This study examined the hypothesis that keratinocytes in mono- and multi-layer forms expressed different levels of TGF-β1. When NHOK reached confluency in serum free medium(KBM), in test medium containing 1.2 mM Ca++ KBM NHOK were allowed to form multi-layers and differentiate. The purpose of this study were to investigate the mRNA level of TGF-β1, FGF-2, and TIMP-1 by RT-PCR analysis and also to evaluate the expression of TGF-β1 and involucrin in keratinocytes at different times of the onset of differentiation. The numbers and sizes of these nodules were increased as the process of keratinocyte differentiation proceed. Cultured NHOK in preconfluency under KBM medium expressed a significantly higher level of TGF-β1 relative to those grown in multi-layer forms, while the level of TGF-β1 mRNA gradually reduced to its lowest level at 7 days of growing cells in test medium. Cultured NHOK in preconfluency of KBM medium expressed a lower level of FGF-2 and TIMP-1 relative to those grown in multi-layer forms, while the level of FGF-2 and TIMP-1 mRNA showed the highest level at 3 days at gradually reduced to its lowest level at 7 days of growing cells in test medium. As a differentiation marker for keratinocytes at different time points, the highest level of involucrin mRNA expression was found at the later stage of cell differentiation. It suggested that the expression of TGF-β1 mRNA be consistent with the expression of FGF-2 and TIMP-1 mRNA in NHOK grown in high calcium medium during the terminal differentiation. But differentiated NHOK expressing higher involucrin mRNA could show constant espression of TGF-β1, FGF-2 and TIMP-1.

Triterpenoid, saponin, 전분 등이 함유되어 있는 것으로 알려진 Adenophorae radix (A. radix)의 뿌 리 추출물을 이용하여 각질형성세포의 분화와 피부장벽기능에 대한 연구를 수행하였다. A. radix의 뿌리 추출물 은 CV-1 세포를 이용하여 PPARα 발현을 살펴본 결과, Wy-14,643 0.5-1.0 μ M 수준의 발현양을 나타내었 다. 인체 각질형성 세포주(HaCaT)와 각질형성세포(nomal human keratinocyte)에 대한 각질형성능(cornified envelop formation, CE)은 대조군에 비해 통계적으로 유의한 증가를 보였다. HaCaT 세포에 A. radix의 뿌리 추출물 처리하였을 때, transglutaminase (TGase-1)의 유의적 증가를 보였다. A. radix의 뿌리 추출물 을 함유한 간단한 화장품 제형을 약 2주간에 걸쳐 임상시험을 실시한 결과, TEWL의 유의적 감소와 수분량의 증가를 살펴볼 수 있었으며, 하박 내측에서 지질을 추출하여 세라마이드를 분석한 결과 통계적으로 유의한 증가 를 관찰할 수 있었다. 이를 통하여 A. radix의 뿌리 추출물을 건조피부나 아토피 등의 피부질환과 관련된 질환의 예방 및 치료제로 사용될 수 있을 것이다.

본 연구에서는 두충 추출물이 RBL-2H3 세포의 β-hexosaminidase의 분비 억제와 HaCaT keratinocytes피부장벽의 회복과 관련한 filaggrin, transglutaminase-1 (TGase-1), cornified cell envelope(CE)의 발현에 미치는 영향에 관하여 연구하였다. β-hexosaminidase 방출 억제 능은 13% 효능을 확인하였고, 피부장벽기능의 회복과 관련된 인자들은 발현과 활성의 정도가 매우 우수한 것을 확인하였다. 각질형성세포의 분화를 판단할 수 있는 CE 측정에서는 두충추출물이 양성대조군보다 더 좋은 효능을 나타내기도 하였다. 따라서 두충 추출물은 β-hexosaminidase 분비 억제에 효과가 있으며, 손상된 피부장벽강화에 영향을 미치는각질형성세포의 분화 촉진에 효과가 있음을 확인하였다.