Curcumin inhibits the activity and induces apoptosis of activated hepatic stellate cell by suppressing autophagy.

Curcumin, a kind of natural compound, has been previously proven to inhibit the autophagy in hepatic stellate cells (HSCs) and induce their apoptosis. However, it is not clear whether the enhanced apoptosis of activated HSCs (aHSCs) caused by curcumin depends on autophagy inhibition. We aim to verify this hypothesis and explore the potential mechanisms in this study. Immortalized human HSC line LX-2 was used as an experimental specimen and pretreated with transforming growth factor ß1(TGF-ß1) for 24 h to activate it before drug application. The levels of autophagy, apoptosis, cell activity, lipid metabolism, and the activity of the PI3K/Akt/mTOR signal pathway were evaluated by multiple methods, such as Western blotting, mcherry-EGFP-LC3B adenoviruses transfection, immunofluorescence, Nile Red staining, flow cytometry among others. Our results showed that rapamycin, an autophagy activator, could partly offset the effects of curcumin on autophagy and apoptosis of LX-2 cells, while 3-Methyladenine (3-MA), an autophagy inhibitor, could enhance these effects. Furthermore, curcumin could promote the activity of the PI3K/Akt/mTOR signal pathway in LX-2 cells, while PI3K inhibitor could partly offset this effect and increase the autophagy level. Overall, we demonstrated that curcumin could inhibit the activity and promote LX-2 cells apoptosis by suppressing autophagy by activating the PI3K/Akt/mTOR signal pathway. In addition, lipid recovery and energy deprivation due to autophagy inhibition may be the exact mechanism by which curcumin attenuates the pro-fibrotic activity of LX-2.

Research progress of natural compounds in anti-liver fibrosis by affecting autophagy of hepatic stellate cells.

Chronic liver diseases caused by various pathogenesis are marked by inflammatory infiltration and wound healing reaction, while their normal regeneration ability is impaired. The unbalance between the generation and the degradation of extracellular matrix (ECM) leads to collagen accumulation and develops into liver fibrosis. Inflammation, oxidative stress, and autophagy interact closely in the pathogenesis of hepatic fibrosis. Reactive Oxygen Species (ROS) can not only stimulate Kupffer cells to release massive inflammatory factors, but induce autophagy. However, the latter may suppress inflammatory reaction by inhibiting proinflammatory complex formation directly, and removing damaged organelles or pathogenic microorganism indirectly. At present, effective anti-fibrosis drugs are still lacking. Previous studies have found various natural compounds enabled liver protection through anti-inflammatory, antioxidant, and other mechanisms. In recent years, autophagy, a vital life activity, has been found to be involved in the mechanism of liver fibrosis. As a new target, developing anti-liver fibrosis drugs that regulate the activity of autophagy is very promising. In this review, we summarize the latest studies about natural compounds in the treatment of liver fibrosis by regulating autophagy.

Interactions of central obesity with rs3918242 on risk of non-alcoholic fat liver disease: a preliminary case-control study.

NAFLD is a complex disease characterized by inflammation and insulin resistance which is determined by an interaction of genetics and environmental factors. MMP gene has been implicated in relation to inflammation and insulin resistance. The preliminary case-control study aimed to investigate the association between Matrix metalloproteinase (MMP)-9-1562C/T (rs3918242), MMP-2-1306C/T (rs243865) and risk of NAFLD and to further evaluate the interactions of central obesity with rs3918242 and rs243865. Two variants, rs3918242 and rs243865, were genotyped by polymerase chain reaction -restriction fragment length polymorphism. Gene-environment interactions on risk of NAFLD was preliminarily investigated by generalized multifactor dimensionality reduction (GMDR) and further confirmed by unconditional logistic regression methods. After adjusting for covariates, increased risk of NAFLD were observed in subjects carrying TT/CT genotypes in rs3918242 ((Adjust)OR=1.64, 95% CI: 1.24, 2.11, P=0.006). However, decreased risk of non-alcoholic fat liver disease was found when MMP-2 rs243865 (TT/CT) genotype carriers compared with CC carrier ((Adjust)OR=0.65, 95% CI: 0.47, 0.72, P=0.000).Interactions of central obesity with rs3918242 was preliminarily found by GMDR, with a maximum prediction accuracy (67.61%) and a maximum Cross-validation Consistency (10/10).The unconditional logistic regression method indicated central obesity-positive subject with genotype TT/CT had 4.54 times risk of NAFLD compared to central obesity-negative subjects with genotype CC (OR(add)(a)=4.54, 95% CI: 2.81, 7.21, P(add)(a)=0.000), which further confirmed the interactions. The results indicate that both rs3918242 and rs243865 is associated with risk of NAFLD. Furthermore, rs3918242 and central obesity have synergistic effects on risk of NAFLD.

[Association between patatin-like phospholipase domain-containing protein 3 gene rs738409 polymorphism and non-alcoholic fatty liver disease susceptibility: a meta-analysis].

OBJECTIVE: To explore the association between patatin-like phospholipase domain-containing protein 3(PNPLA3) gene rs738409 polymorphism and the susceptibility of non-alcoholic fatty liver disease(NAFLD). METHODS: Data bases were comprehensively searched to retrace all the related studies on the association between PNPLA3 gene rs738409 polymorphism and susceptibility. Of NAFLD, the pooled OR with 95% CI of the association between PNPLA3 gene rs738409 polymorphism and NAFLD susceptibility were performed using different genetic models. Subgroup analysis based on the source of population and sensitivity analysis was performed to detect the stability of results. RESULTS: 28 original studies with 6 216 patients and 8 218 controls were involved in the final combination of data. Findings from the meta-analyses showed that there were strong associations between PNPLA3 gene rs738409 polymorphism and the susceptibility of NAFLD, under different genetic model comparisons[GG vs. CC:OR = 2.42, 95%CI:1.83-3.21, P < 0.001;CG vs. CC:OR = 1.28, 95%CI:1.15-1.43, P < 0.001;CG+GG vs. CC:OR = 1.31, 95%CI:1.17-1.46, P < 0.001; GG vs. CC+GC:OR = 2.26, 95%CI:1.76-2.90, P < 0.001]. Similar results were found in both Asian and Caucasian populations. CONCLUSION: Results from the Meta-analysis strongly suggested that there appeared significant association between PNPLA3 gene rs738409 polymorphism and the susceptibility of NAFLD.

[Study on the interaction between matrix metalloproteinases gene polymorphism and central obesity in nonalcoholic fatty liver disease].

OBJECTIVE: To study whether matrix metalloproteinases-9 (MMP) -1562C/T (rs3918242) and MMP-2-1306C/T (rs243865) were associated with the susceptibility on nonalcoholic fatty liver disease (NAFLD) and the interactions between the two factors and central obesity. METHODS: Genotypes of 545 patients and 636 subjects with NAFLD under control were examined by polymerase chain reaction-based restriction fragment length polymorphism (PCR-RFLP). Unconditional logistic regression (ULR) was performed to assess the NAFLD risk. The gene-environment interactions on the risk of NAFLD were explored by generalized multifactor dimensionality reduction (GMDR) and ULR methods. RESULTS: Results from the case-control analysis indicated that there was an increased risk of developing NAFLD for MMP-9 rs3918242 (TT/CT) genotype carriers, when compared with the non-carriers (CC) , with OR=1.67, 95%CI: 1.32-2.12, P=0.001; Adjusted OR=1.65, 95% CI: 1.31-2.01 (P=0.008). However, risk reduction of NAFLD was found when MMP-2 rs243865 (TT/CT) genotype carriers compared with the non-carriers (CC) , with OR=0.68, 95% CI: 0.53-0.86, P=0.001; with adjusted OR=0.66, 95% CI: 0.49-0.90 (P=0.007). Data from the GMDR showed that gene-environment interaction among rs3918242 and central obesity on the risk of NAFLD might be significant (P=0.001). By using the ULR method, subjects as central obesity-positive but with genotype CT/TT, appeared having 4.50 (95% CI: 2.78-7.17, P= 0.007) times risk of NAFLD, when compared to the central obesity-negative subjects with genotype CC after adjusting for the covariates. CONCLUSION: MMP-9 rs3918242, MMP-2 rs243865 were associated with risk of NAFLD while both rs3918242 and central obesity showing synergistic effects on the risk of the NAFLD.