Suppressive Effects of Epigallocatechin Gallate Pretreatment on the Expression of Inflammatory Cytokines in RAW264.7 Cells Activated by Lipopolysaccharide Eun Ji Seo 1 , Jun Go 1 , Ji Eun Kim 1 , Eun Kyoung Koh 1 , Sung Hwa Song 1 , Ji Eun Sung 1 , Chan Kyu Park 1 , Hyun Ah Lee 1 , Dong Seob Kim 1 , Hong Joo Son 1 , Cung Yeoul Lee 2 , Hee Seob Lee 3 and Dae Youn Hwang 1 * 1 College of Natural Resources & Life Science/Life and Industry Convergence Research Institute, Pusan National University, Miryang 627-706, Korea 2 Gangrim Organics, Miryang 627-706, Korea 3 College of Human Ecology, Pusan National University, Busan 609-735, Korea Received June 15, 2015 /Revised August 5, 2015 /Accepted September 16, 2015 Epigallocatechin gallate (EGCG), the main catechin in green tea, has been shown to have some benefi- cial effects against various human diseases, including diabetes, neurodegenerative disorders, cancer, cardiovascular disease and obesity. To investigate the mechanism of the suppressive effects of EGCG on inflammatory response in macrophages, alterations on the levels of nitric oxide (NO) regulatory factors and inflammatory cytokines were measured in lipopolysaccharide (LPS)-activated RAW264.7 cells. No significant toxicity was detected in RAW264.7 cells treated with 100–400 μM EGCG. Moreover, the optimal concentration of LPS was determined to be 1 μg/ml based on the results of cell viability assay, NO assay and IL-6 enzyme-linked immunsorbent assay (ELISA). Furthermore, NO levels decreased significantly by 68.2% in the 400 μM EGCG/LPS treated group, while the level of inducible nitric oxide synthase (iNOS) expression decreased by 12-17% in the 200 and 400 μM EGCG/LPS treated group. A significant decrease in transcription of pro-inflammatory cytokines (TNF- α and IL-1β) and anti-inflammatory cytokine (IL-10) was also detected in the EGCG/LPS treated group. However, IL-6 transcript and protein was maintained at a constant level when in the LPS treat- ed group relative to the EGCG/LPS treated group. Overall, these results suggest that the differential regulation of inflammatory cytokines is an important factor influencing the suppressive effects of EGCG against LPS-activated inflammatory response in RAW264.7 cells. Key words : Cytokines, Epigallocatechin gallate (EGCG), inflammatory response, lipopolysaccharide, nitric oxide *Corresponding author *Tel : +82-55-350-5388, Fax : +82-55-350-5389 *E-mail : dyhwang@pusan.ac.kr This is an Open-Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. ISSN (Print) 1225-9918 ISSN (Online) 2287-3406 Journal of Life Science 2015 Vol. 25. No. 9. 961~969 DOI : http://dx.doi.org/10.5352/JLS.2015.25.9.961 서 론 EGCG는 녹차(Camellia sinensis, green tea)에 포함되어 있는 총 폴리페놀 혼합물의 40% 이상을 차하는 대표적인 카테킨 (Catechin)이다[13, 25]. 녹차는 EGCG 이외에도 epicatechin gallate (ECG), epigallocatechin (EGC), epicatechin (EC), 등을 포함하고 있으나 강력한 항산화작용을 통해 인체환에 대한 가장 우수한 효능을 나타내는 것은 EGCG로 알려져 있다[25]. EGCG는 당뇨병, 중추신경계의 퇴행성환, 암, 심혈관 환, 비만 등 다양한 인체환에 대해 우수한 치료효능을 나타 낸다[8, 12, 24]. 일부 당뇨모델동물에서 EGCG는 혈액 내 포도 당의 농도를 감소시키고, 인슐린 감수성을 가시키며, 간에 서 포도당생성을 가시킴으로써 당뇨를 개선시키는 효과를 나타내었다[27-29]. 또한, 대장암 등 다양한 인간의 암세포에 서 EGCG는 epidermal growth factor (EGF)와 plate- let-derived growth factor (PDGF) signaling pathway의 조절 을 통해 세포분열과 세포성장을 억제하고, 세포사(apoptosis) 를 촉시켰으며[17, 20, 22, 30], 췌장암의 invasion, angio- genesis, metastasis를 효과적으로 억제하였다[24]. 더불어, EGCG는 알츠하이머모델인 AβPP/PS-1 (presenilin 1) 이중돌 연변이 형전환마우스에서 뇌조에서 Aβ펩타이드의 침적 을 감소시키고, 미토콘드리아의 기능을 보호하는 효과를 나타 내었으며[5], 파킨슨환의 원인단백인 α-synuclein의 fi- brillogenesis를 억제함으로써 독성물로의 전환을 억제하였 다[3]. 뿐만 아니라, EGCG는 포유동물세포, 실험동물 리고 인 간에서 우수한 항염 효과를 나타내는 것으로 알려져 있다. EGCG는 LPS로 자된 골수유래 수상세포(bone mar- row-derived dendritic cells)와 RAW264.7 세포에서 TNF-α의 생산을 효과적으로 저해하였만, 염사이토카인(inflamma- tory cytokines)의 생산과 MAPKs (mitogen-activated pro- tein kinases) 인산화과정은 세포에 따라 다양한 반응이 관찰 되었다[1, 10, 18, 31]. 또한, EGCG는 BALB/c에서 추출한 peri-