Protective effects of Asiaticoside on acute liver injury induced by lipopolysaccharide/D-galactosamine in mice.

Asiaticoside (AS), a triterpenoid product isolated from Centella asiatica, has been described to exhibit anti-in fl ammatory activities in several inflammatory models. However, the effects of AS on liver injury are poorly understood. The present study was undertaken to investigate whether AS is efficacious against Lipopolysaccharide (LPS) /D-galactosamine (D-GalN)-induced acute liver injury in mice and its potential mechanisms. AS (5, 10 and 20 mg/kg/d) was pretreated orally once daily for 3 days before LPS/D-GalN injected in mice. The mortality, hepatic tissue histology, plasma levels of Tumor necrosis factor-alpha (TNF-alpha) and alanine aminotransferase (ALT) and aspartate aminotransferase (AST), hepatic tissue TNF-alpha and caspase-3 activity were measured. Besides, western blotting analysis of phospho-p38 mitogen-activated protein kinase (phospho-p38 MAPK), phospho-c-jun N-terminal kinase (phospho-JNK) and phospho-extracellular signal regulated kinase (phospho-ERK) were determined. As a result, AS showed significant protection as evidenced by the decrease of elevated aminotransferases, hepatocytes apoptosis and caspase-3, alleviation of mortality and improvement of liver pathological injury in a dose-dependent manner. Further, we found that AS dose-dependently reduced the elevation of phospho-p38 MAPK, phospho-JNK, phospho-ERK protein and TNF-alpha mRNA expression in liver tissues and plasma TNF-alpha. These results suggest that AS has remarkable hepatoprotective effects on LPS/D-GalN-induced liver injury and the possible mechanism is related to inhibition of TNF-alpha and MAPKs.

Tetrandrine attenuates lipopolysaccharide-induced fulminant hepatic failure in D-galactosamine-sensitized mice.

Fulminant hepatic failure (FHF) remains an extremely poor prognosis and high mortality; better treatments are urgently needed. Tetrandrine (TET), a traditional anti-inflammatory drug, has been reported to exhibit hepatoprotective activities in several liver injury models. We now investigated the effects and underlying mechanisms of TET on lipopolysaccharide (LPS) and D-galactosamine (D-GalN)-induced FHF in mice. TET (50, 100, and 200 mg/kg) was given intraperitoneally 1h before LPS/D-GalN injection in mice. The mortality and liver injury was evaluated subsequently. The results showed that administering TET to mice reduced mortality and improved liver injury induced by LPS/D-GalN in a dose-dependent manner. In addition, TET dose-dependently inhibited LPS/D-GalN-induced NF-kappaB activation, serum and hepatic tissues tumor necrosis factor-alpha (TNF-alpha) production, caspase-3 activation and hepatocellular apoptosis, myeloperoxidase (MPO) activity, intercellular adhesion molecule-1 (ICAM-1) and endothelial cell adhesion molecule-1 (ECAM-1) expression. Our experimental data indicated that TET might alleviate the FHF induced by LPS/D-GalN through inhibiting NF-kappaB activation to reduce TNF-alpha production.

[Inhibitiory action of asiaiticoside on collagen-induced arthritis in mice].

The study is to investigate the effect of asiaticoside on collagen-induced arthritis (CIA). The model of CIA mice was prepared and the change of secondary paw swelling and the arthritis scores were observed. In vitro proliferation of spleen cells was examined using MTT assay. The cell-free protein extracts from the arthritic joints and nonarthritic joints were used for the analysis of protein expression of cyclooxygenase-2 (COX-2). And the level of PGE2 in joints was assayed using PGE2 express EIA kit. The tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6) levels in the serum were measured by ELISA. Histopathological examination was performed by hematoxylin-eosin (HE) stain method. Asiaticoside (10, 20 and 40 mg x kg(-1) x d(-1), 22 d, ig) significantly reduced paw swelling, and decreased the arthritis scores. There was a significant reduction in proliferation of spleen cells of CIA mice treated with asiaticoside as compared with that of untreated CIA mice. COX-2, PGE2, TNF-alpha and IL-6 production in CIA mice were inhibited by asiaticoside. Meanwhile, the pathological examination showed that articular cartilage degeneration with synovial hyperplasia and inflammatory cells infiltration in CIA mice was suppressed by asiaticoside. Its active mechanism may be related to inhibiting proliferation of lymphocyte and reduction of expression of COX-2 and inflammatory cytokines.

[Progress of the study on endotoxin tolerance mechanisms].

Endotoxin tolerance has been attracted for more than 50 years, but so far its molecular mechanisms remain to be resolved. TLR4, the major receptor for LPS, was found to be involved in LPS signaling transduction and to have a close relationship with endotoxin tolerance. Quantitative, structural and functional changes of receptors, adaptor proteins and transcription factors in TLR4 signaling pathways might have effects on the decrease in proinflammatory cytokines, increase in anti-inflammatory cytokines and activation of special signaling pathways (such as PI3K pathways) as well as some negative regulation factors (SHIP1,SOCS, FLN29, et al) during the development of endotoxin tolerance. Furthermore, TLR2, Gi protein, PKC and several selective splicing isoforms are involved in endotoxin tolerance. So endotoxin tolerance is a complicated pathophysiological process caused by diverse reasons and involved in many biological substances. It is also an important protective mechanism of human body infected with G- bacteria. Exploring the mechanism of endotoxin tolerance, seeking endogenous protective mechanism of human body would provide new theory and new ways to overcome series of fatal infective diseases including sepsis.