Inhibitory efficacy of Castanopsis sieboldii on hepatitis via kupffer cell regulation

Abstract

간은 인체에서 체내 대사 및 해독작용을 담당하는 가장 큰 기관으로 70%의 간 실질세포와 30%의 쿠퍼세포, 간성상세포를 포함하는 비 실질세포로 이루어져 있다. 과도한 알코올이나 고지방식이 섭취와 같은 요인들에 의해 장벽의 기능이 약화되면 장벽의 투과성이 증가하고 장내 내독소가 간으로 유입 될 수 있다. 이는 간에서 염증반응을 유도하여 간염증, 섬유증 및 간암과 같은 간질환을 유발할 수 있다. 쿠퍼세포는 간 내 상주하는 대식세포로써, 활성화되어 자극에 다라 전염증성 형태인 M1표현형 또는 항염증성 형태인 M2표현형으로 분극화 되며 간 내 면역 및 수복반응을 담당한다. 현재까지 보고 된 연구결과에 따르면 M1포현형으로 분극화한 쿠퍼세포에서 분비된 사이토카인이 간성상세포의 활성화에 영향을 주어 간섬유화 및 간염의 발병에 영향을 주는 것으로 알려져 있다. 따라서 쿠퍼세포의 분극화 제어 약물 발굴과 그 기전에 대한 이해가 간질환의 발병 및 진행에 중요하다. 최근 한반도 남부, 특히 제주 등지에 분포하는 난대수종 구실잣밤나무 열매 추출물의 항산화 및 세포사멸 억제 효능에 대한 연구결과가 보고 된 바 있다. 하지만 염증에 효과가 있다고 알려진 EGCG(epigallocatechin gallate)와 GA(gallic acid)가 높은 함량을 이루고 있지만 염증을 비롯한 면역반응 조절에 대한 구실잣밤나무 잎추출물의 효능연구는 거의 이루어지지 않고 있는 실정이다. 따라서 본 연구에서는 LPS(지질다당체, 내독소)를 이용한 염증성 손상 유도 시 간 내 대식세포인 쿠퍼세포의 분극화에 대한 구실잣밤나무 잎추출물의 효능 및 관련 보호기전 연구를 진행하고자 한다. |The largest solid organ in the human body is the liver which is responsible for metabolism and detoxification. The liver mass is composed of 80% of parenchyma cells (hepatocytes) and 20% of non-parenchymal cells (lymphocytes, kupffer cells, hepatic stellate cells and endothelial cells) [1]. Kupffer cells, the liver-resident macrophage, play a central role in the pathogenesis of a diversity of liver diseases including alcoholic liver disease, steatohepatitis, intrahepatic cholestasis, viral hepatitis and liver fibrosis [2]. Activated Kupffer cells, in liver injury, are a major source of inflammatory mediators including nitric oxide, cytokines, chemokines, superoxide, eicosanoids [3], resulting in an excessive inflammatory response and hepatitis. Hepatitis can be split into acute and chronic based on the duration of the inflammation of the liver. The natural recovery of acute hepatitis is sometimes possible [4], however, treatment is limited as antiviral agents or corticosteroids. The treatment of choice for patients with severe alcoholic hepatitis (AH), autoimmune hepatitis is use of corticosteroids. However, the use of corticosteroids acute hepatitis is still controversial until now. In contrast, chronic hepatitis can cause chronic liver diseases including liver fibrosis, cirrhosis, liver cancer leading to significant morbidity and mortality [5]. Current treatments for end stage of liver diseases such as liver failure or decompensated cirrhosis are still limited, and liver transplantation remnants the only available approach to improve survival. Thus, research on identification of new drug targets and candidate drugs that can control acute hepatitis is very important. Kupffer cells are responsible for immune and repair reactions in the liver and polarized into M1 phenotype (a pro-inflammatory form) or M2 phenotype (an anti-inflammatory form) [6, 7]. Polarization to the M1 phenotype, induced by LPS, TNF-α and IFN-γ and express pro-inflammatory cytokines, are involved in the pathogenesis of liver inflammation. When kupffer cells stimulated by LPS and/or IFN-γ, also formed the NLRP3 inflammasome and GSDMD is cleaved, resulting in pyroptosis. Pyroptosis, a kind of lytic programmed cell death, is stimulated by proinflammatory signals and connected with inflammation [8, 9]. Accumulation evidence show that pyroptosis in kupffer cells also contributes to sterile inflammatory liver diseases via release of pro-inflammatory cytokines like as IL18- or IL-1β [10]. However, there is no candidates for the treatment or prevention of acute hepatitis targeting pyroptosis in Kupffer cells. Castanopsis sieboldii, a species of the warm-temperature tree species, is native to the southern part of the Korean Peninsula and Jeju Island. The warm-temperature tree species, distributed in subtropical regions, is gradually expanding on the Korean Peninsula due to global warming and climate change. The fruits of the Castanopsis sieboldii have been used for food since ancient times, and the its branches have recently been used as wood. In addition, it is known that the leaf extract of the Castanopsis sieboldii has high antioxidant and antibacterial activity [11]. Recently, we identified that extract of Castanopsis sieboldii leaf (CSL) has cytoprotective and antioxidant efficacy in skin keratinocytes against UV-mediated phototoxicity [not published]. However, the role of the CSL extract in anti-inflammatory efficacy against pyroptosis-mediated hepatitis has not scrutinized. Therefore, the aim of current study is examined whether CSL3 inhibited inflammatory response and pyroptosis by LPS or LPS/ATP-induced activated macrophages. Furthermore, we investigated in vivo effect CSL3 in acute hepatitis mice model.