ABSTRACT
BACKGROUND: The differentiation resp. death of human monocytic THP-1 cells induced by polysaccharide extracts of the medicinal mushrooms Phellinus linteus, Agaricus bisporus and Agaricus brasiliensis have been studied. This study aims to identify leads for the causal effects of these mushroom components on cell differentiation and death. METHODS: THP-1 cells were treated with different polysaccharide extracts of mushrooms and controls. Morphological effects were observed by light microscopy. Flow cytometry was applied to follow the cell differentiation by cell cycle shifts after staining with propidium iodide, changes of mitochondrial membrane potential after incubation with JC-1, and occurrence of intracellular reactive oxygen species after incubation with hydroethidine. Principal component analysis of the data was performed to evaluate the cellular effects of the different treatments. RESULTS: P. linteus polysaccharide extracts induced dose-dependent apoptosis of THP-1 cells within 24 h, while A. bisporus and A. brasiliensis polysaccharide extracts caused differentiation into macrophages. A pure P. linteus polysaccharide had no effect. Apoptosis was inhibited by preincubating THP-1 cells with human serum. The principal component analysis revealed that P. linteus, A. bisporus and A. brasiliensis polysaccharide extracts increased reactive oxygen species production. Both A. bisporus and A. brasiliensis polysaccharide extracts decreased the mitochondrial membrane potential, while this was increased by P. linteus polysaccharide extracts. CONCLUSIONS: P. linteus polysaccharide extracts caused apoptosis of THP-1 monocytes while A. bisporus and A. brasiliensis polysaccharide extracts caused these cells to differentiate into macrophages. The protective effects of human serum suggested that P. linteus polysaccharide extract induced apoptosis by extrinsic pathway, i.e. by binding to the TRAIL receptor. The mitochondrial membrane potential together with reactive oxygen species seems to play an important role in cell differentiation and cell death.
ABSTRACT
BACKGROUND: The hepatoprotective potential of Phellinus linteus polysaccharide (PLP) extracts has been described. However, the molecular mechanism of PLP for the inhibition of liver fibrosis is unclear. This study aims to investigate the molecular protein signatures involved in the hepatoprotective mechanisms of PLP via a proteomics approach using a thioacetamide (TAA)-induced liver fibrosis rat model. METHODS: Male Sprague-Dawley rats were divided into three groups of six as follows: Normal group; TAA group, in which rats received TAA only; and PLP group, in which rats received PLP and TAA. Liver fibrosis was induced in the rats by repeated intraperitoneal injections of TAA at a dose of 200 mg/kg body weight twice a week for 4 weeks. PLP was given orally at a dose of 50 mg/kg body weight twice a day from the beginning of the TAA treatment until the end of the experiment. The development of liver cirrhosis was verified by histological examination. Liver proteomes were established by two-dimensional gel electrophoresis. Proteins with significantly altered expression levels were identified by matrix-assisted laser desorption/ionization-time of flight/time of flight mass spectrometry and the differentially expressed proteins were validated by immunohistochemical staining and reverse transcription polymerase chain reaction. RESULTS: Histological staining showed a remarkable reduction in liver fibrosis in the rats with PLP treatment. A total of 13 differentially expressed proteins including actin, tubulin alpha-1C chain, preprohaptoglobin, hemopexin, galectin-5, glutathione S-transferase alpha-4 (GSTA4), branched chain keto acid dehydrogenase hterotetrameric E1 subunit alpha (BCKDHA), glutathione S-transferase mu (GSTmu); glyceraldehyde-3-phosphate dehydrogenase (GAPDH); thiosulfate sulfurtransferase (TFT); betaine-homocysteine S-methyltransferase 1 (BHMT1); quinoid dihydropteridine reductase (QDPR); ribonuclease UK114 were observed between the TAA and PLP groups. These proteins are involved in oxidative stress, heme and iron metabolism, cysteine metabolism, and branched-chain amino acid catabolism. CONCLUSION: The proteomics data indicate that P. linteus may be protective against TAA-induced liver fibrosis via regulation of oxidative stress pathways, heat shock pathways, and metabolic pathways for amino acids and nucleic acids.
