ABSTRACT
The sequence of events that lead to inflammation and fibrosing nonalcoholic steatohepatitis (NASH) is incompletely understood. Hence, we investigated the chronology of whole body, tissue, and cellular events that occur during the evolution of diet-induced NASH. Male C57Bl/6 mice were assigned to a fast-food (FF; high calorie, high cholesterol, high fructose) or standard-chow (SC) diet over a period of 36 wk. Liver histology, body composition, mitochondrial respiration, metabolic rate, gene expression, and hepatic lipid content were analyzed. Insulin resistance [homeostasis model assessment-insulin resistance (HOMA-IR)] increased 10-fold after 4 wk. Fibrosing NASH was fully established by 16 wk. Total hepatic lipids increased by 4 wk and remained two- to threefold increased throughout. Hepatic triglycerides declined from sixfold increase at 8 wk to threefold increase by 36 wk. In contrast, hepatic cholesterol levels steadily increased from baseline at 8 wk to twofold by 36 wk. The hepatic immune cell population altered over time with macrophages persisting beyond 16 wk. Mitochondrial oxygen flux rates of FF mice diet were uniformly lower with all the tested substrates (13-276 pmol·s-1·ml-1 per unit citrate synthase) than SC mice (17-394 pmol·s-1·ml-1 per unit citrate synthase) and was accompanied by decreased mitochondrial:nuclear gene copy number ratios after 4 wk. Metabolic rate was lower in FF mice. Mitochondrial glutathione was significantly decreased at 24 wk in FF mice. Expression of dismutases and catalase was also decreased in FF mice. The evolution of NASH in the FF diet-induced model is multiphasic, particularly in terms of hepatic lipid composition. Insulin resistance precedes hepatic inflammation and fibrosis. Mitochondrial dysfunction and depletion occur after the histological features of NASH are apparent. Collectively, these observations provide a unique overview of the sequence of changes that coevolve with the histological evolution of NASH.NEW & NOTEWORTHY This study demonstrates in a first of kind longitudinal analysis, the evolution of nonalcoholic steatohepatitis (NASH) on a fast-food diet-induced model. Key findings include 1) hepatic lipid composition changes in a multiphasic fashion as NASH evolves; 2) insulin resistance precedes hepatic inflammation and fibrosis, answering a longstanding chicken-and-egg question regarding the relationship of insulin resistance to liver histology in NASH; and 3) mitochondrial dysfunction and depletion occur after the histological features of NASH are apparent.
Subject(s)
Liver Cirrhosis/metabolism , Liver/metabolism , Non-alcoholic Fatty Liver Disease/metabolism , Adiposity , Animals , Biomarkers/blood , Blood Glucose/metabolism , Diet, High-Fat , Disease Models, Animal , Disease Progression , Energy Metabolism , Humans , Inflammation Mediators/blood , Insulin/blood , Insulin Resistance , Lipids/blood , Liver/physiology , Liver/physiopathology , Liver Cirrhosis/genetics , Liver Cirrhosis/pathology , Liver Cirrhosis/physiopathology , Male , Mice, Inbred C57BL , Mitochondria, Liver/metabolism , Mitochondria, Liver/pathology , Non-alcoholic Fatty Liver Disease/genetics , Non-alcoholic Fatty Liver Disease/pathology , Non-alcoholic Fatty Liver Disease/physiopathology , Organ Size , Species Specificity , Time Factors , Weight GainABSTRACT
The present study describes the anti-leukemic potential of a novel stereo bioactive secondary metabolite, (R)-5-hydroxy-2-methylchroman-4-one (HMC) isolated from a novel endophytic fungus source (Cryptosporiopsis sp. H2-1, NFCCI-2856), associated with Clidemia hirta. HMC inhibited cell proliferation of different cancer cell lines with IC50 values in the range of 8-55 µg/ml. The cytotoxicity window of HMC was 6-12 times lower in normal cells as compared to susceptible leukemic HL-60, MOLT-4 and K-562 cells. It persuades apoptosis through both intrinsic and extrinsic pathways in above leukemic cell lines, which was evident through Hoechst staining, Annexin-V binding, cell cycle analysis, loss of mitochondrial membrane potential (Δψm), release of cytochrome c, Bax, Bid, over-expression of apical death receptors, activation of caspase-3,-8,-9 and PARP (poly ADP ribose polymerase) cleavage. HMC induced caspase dependent apoptosis and robustly attenuate transcription factor, p-STAT-3 in myeloid and lymphoid leukemia cells. The mechanism of HMC arbitrated inhibition of p-STAT-3 was due to the activation of ubiquitin dependent degradation of p-STAT-3. Therefore, our study not only describes the anti-leukemic potential of HMC but also provides insights into how endophytes can be useful in discovery and development of novel anticancer therapeutics.