When chronic liver diseases last, due to different factors such as metabolic disorders, viral infection, drugs, or immune disease, lead to liver fibrosis (1). The result of sustaining chronic liver disease is progression to fibrosis, which eventually leads to cirrhosis and the development of hepatocellular carcinoma. (2, 3). Liver fibrosis is a global problem today. Immunosuppressive factors or antiviral drugs may prohibit the progression of liver fibrosis at the first stages. However, efficient treatments are not available for many patients and proper treatment is still far from satisfactory (4, 5). Definite suppressive and therapeutic actions have not been found yet, so it is necessary to detect antifibrotic elements. Deposition of extracellular matrix (ECM) and mass production of Collagen type I (COLA1) are important signs of Liver fibrosis onset and progression (6, 7).
The major origin of ECM is hepatic stellate cells (HSCs).These cells are inactive during physiological situations and store retinoid and vitamin A (8, 9). In hepatic fibrosis, HSCs that have been activated, express much amount of fibrogenec genes such as Collagen1 α (COL 1α) and Alpha Smooth Muscle Actin (α-SMA). Increased producing COL 1α and α-SMA is known as markers which show HSCs have become activated. (10).
HSCs can be activated by various factors and change to myofibroblast-like shape and express much COLA1 and α-SMA (11). Proliferative and Fibrogenic elements that raise the proliferation of HSCs and the generation of ECM are made by activated HSCs (12). Preventing of HSC activation and proliferation, inhibiting equal generation, and degradation of ECM, all are the most main agents for liver fibrosis treatment. Diverse inflammatory cytokines and growth factors can create the activation of HSCs. PDGF-BB (platelet-derived growth factor) is one of the most potential proliferative cytokines which can activate HSCs. After the liver injury, PDGF-BB expressions and related receptors (PDGF-R) are increased. (13) PI3K (The phosphatidylinositol3-kinase)-PKB/Akt (protein kinase B) is a signal transduction pathway that controls the survival and growth of cells in response to extracellular signals. PI3K produces 3’phosphoinositides to engage aim proteins (Akt which is located in the membrane of the plasma). Akt as a Ser-Thr kinase is an effector of PI3K which begin a kinase cascade that ends up controlling cellular activities (14, 15). Past studies have found the PI3K/Akt signaling pathway has the ability to impose proliferation of HSC, reduce HSC apoptosis, as well as regulate the liver fibrosis progression through its impact on the degradation of ECM (16, 17). Past studies show that phosphoinositide 3-kinase (PI3K) proliferative kinase signaling pathway could be activated in myofibroblast-like cells of rats and expression levels of COLA1 and α-SMA, an important marker of activated HSCs, are upregulated (17, 18). In contrast, various studies indicated PI3K activities inhibition represses proliferation of cells and COLA1 and α-SMA expressions in activated HSCs (19). Therefore, activation of PI3K plays a significant role in regulating HSC activation. Isorhamnetin, as a flavonoid, has antioxidant, anti-inflammatory, and antitumor activity. Isorhamnetin is gotten from the plant Hippophae rhamnoides L which owns hepatoprotective impacts by restricting autophagy of hepatocytes and increasing apoptosis (20). Lately, Yang et al stated Isorhamnetin weakens CCl4-induced hepatic fibrosis by reducing TGF-β Mediated SMAD Signaling (21). But, whether Isorhamnetin can reduce hepatic fibrosis in the PDGF-BB induced HSC-T6 Rat Hepatic Stellate Cell Line is unclear, and the involvement of through PI3K-AKT signaling pathway has not been investigated. The HSC-T6 rat hepatic stellate cell line is a valuable cell model for study of metabolism based on their similar retinoid phenotype to primary cells. There is currently little information on the mechanism of Isorhamnetin action in liver fibrosis, especially in the PI3K-AKT signaling pathway