GSDMD调控非酒精性脂肪肝中细胞焦亡的研究进展

细胞焦亡是一种炎症相关的细胞程序性死亡方式,由胱天蛋白酶(caspase)和炎性小体介导,最终依赖gasdermin家族成员gasdermin D(GSDMD)执行。细胞焦亡的发生伴随着细胞内炎性因子的外泄及免疫细胞的活化,因此与炎症反应的发生密切相关。非酒精性脂肪性肝病(nonalcoholic fatty liver disease, NAFLD)是一种病因不明的慢性肝病,如果缺乏有效的干预手段,脂肪变性会逐渐进展至炎症、纤维化,最终发展至肝硬化。GSDMD 介导的细胞焦亡在非酒精性脂肪性肝病的发病过程中扮演重要角色,不仅会导致肝细胞死亡,还会加重炎症反应和纤维化的进程。抑制GSDMD 的功能从而减少细胞焦亡能够有效地缓解NAFLD 中的脂质堆积和炎症反应,这将为NAFLD 的治疗开辟一个新的研究方向。本文将概述GSDMD 介导的细胞焦亡的分子机制,并关注GSDMD 和细胞焦亡在NAFLD 发病机制及治疗方面的研究进展,为NAFLD 的诊治提供新思路。     

A nonsynonymous gene variant in the adiponutrin gene is associated with nonalcoholic fatty liver disease severity

We explored the role of the adiponutrin (PNPLA3) nonsynonymous-rs738409 single nucleotide polymorphism (SNP) in genetic susceptibility to nonalcoholic fatty liver disease (NAFLD) and whether this SNP contributes to the severity of histological disease. Two hundred sixty-six individuals were evaluated in a case-control association study, which included 172 patients with features of NAFLD and 94 control subjects. The rs738409 G allele was significantly associated with NAFLD (P < 0.001; OR 2.8 95%, CI 1.5–5.2), independent of age, sex, body mass index (BMI), and Homeostasis Model Assessment (HOMA) index. When we tested the hypothesis of a relation between the SNP and the histological spectrum of NAFLD, a significant association was observed [chi2 19.9, degree of freedom (df): 2, P < 5 × 10⁻⁵, adjusted for HOMA and BMI]. The degree of liver steatosis, as evaluated by liver biopsy, was significantly associated with the rs738409 G allele. Patients with CC genotype showed a lower steatosis score (14.9% ± 3.9) in comparison with the CG genotype (26.3% ± 3.5) and GG genotype (33.3% ± 4.0) (P < 0.005). The proportion of the total variation attributed to rs738409 genotypes was 5.3% (β 0.23 ± 0.07; P < 0.002). Our data suggest that the rs738409 G allele is associated not only with fat accumulation in the liver but also with liver injury, possibly triggered by lipotoxicity.     

New scoring system combining the FIB-4 index and cytokeratin-18 fragments for predicting steatohepatitis and liver fibrosis in patients with nonalcoholic fatty liver disease

Purpose: To establish a new scoring system as a noninvasive tool for predicting steatohepatitis and liver fibrosis in patients with nonalcoholic fatty liver disease (NAFLD).

Methods: A total of 170 patients histologically diagnosed with nonalcoholic steatohepatitis (NASH) (n?=?130) or nonalcoholic fatty liver (NAFL) (n?=?40) were enrolled. We analyzed receiver operating characteristic (ROC) curves and performed multivariate analysis to predict steatohepatitis and liver fibrosis.

Results: Multivariate analysis showed that cytokeratin-18 fragment (CK18-F) levels (≥278?U/L) (odds ratio [OR], 4.46; 95% confidence interval [CI], 1.42–14.00; p?=?0.010) and the FIB-4 index (≥1.46) (OR, 4.54; 95% CI, 1.93–29.50; p?=?0.004) were independently associated with prediction of NASH. We then established a new scoring system (named the FIC-22 score) for predicting NASH using CK18-F levels and FIB-4 index. The areas under the ROC curve (AUROCs) of the FIC-22 score and NAFIC score were 0.82 (95% CI, 0.75–0.89) and 0.71 (95% CI, 0.62–0.78) (p?=?0.044). Additionally, the AUROC of the FIC-22 score for predicting the presence of fibrosis (F?≥?1) was 0.78 (95% CI, 0.70–0.85).

Conclusions: In patients with NAFLD, the FIC-22 score had high predictive accuracy not only for steatohepatitis but also for the presence of liver fibrosis.     

Association of adiponectin gene functional polymorphisms (-11377C/G and +45T/G) with nonalcoholic fatty liver disease

Adiponectin levels are reduced in NAFLD patients and genetic variants of adiponectin have been frequently associated with type 2 diabetes and insulin resistance. To determine the genotypic frequencies of adiponectin functional polymorphisms (-11377C/G and +45T/G) and their subsequent effect on disease progression and plasma adiponectin levels in the patients with NAFLD. A total of 137 NAFLD patients and 250 matched controls were enrolled in the study. DNA sequencing and genotyping were performed to identify the genetic variants. The plasma adiponectin levels were assessed by ELISA. Homozygous mutant genotype of adiponectin SNPs, -11377C/G and +45T/G, were significantly more prevalent in NAFLD patients than controls (Bonferroni corrected p=0.014 and 0.018, respectively). Plasma adiponectin levels were significantly lower in the NAFLD patients as compared to controls. Moreover, presence of 'G' allele at position -11377C/G and +45T/G was found to be associated with necroinflammatory grade and reduced adiponectin levels, (p values 0.02 and 0.01) respectively. -11377G and +45G alleles are associated with severity of liver disease and hypoadiponectemia, in the patients with NAFLD, respectively.     

Association between resistin + 299A/A genotype and nonalcoholic fatty liver disease in Chinese patients with type 2 diabetes mellitus

Objective

To investigate the relationship between the resistin intronic + 299G/A polymorphism and nonalcoholic fatty liver disease (NAFLD) in patients with type 2 diabetes mellitus (T2DM).

Methods

We selected 738 T2DM patients, including 395 with NAFLD and 343 without fatty liver disease, as well as 279 healthy control individuals, and analyzed their resistin + 299G/A polymorphism genotype by polymerase chain reaction–restriction fragment length polymorphism.

Results

Plasma resistin levels in T2DM patients with NAFLD were at the highest (P < 0.05). The frequency of AA genotype at the + 299 site of the resistin gene in patients with concurrent T2DM combined with NAFLD was significantly different from that in the control (P < 0.05). The AA genotype was found to be associated with a 1.80-fold increased risk for T2DM combined with NAFLD, 2.05-fold increased risk for obesity and 2.37-fold increased risk for obesity of abdominal type compared to the GG (P < 0.05, respectively). The multivariate non-conditional logistic regression model analysis further shows that the AA genotype is a risk factor for the development of NAFLD in T2DM patients (OR, 2.32; 95% CI, 1.05–4.68; P < 0.05).

Conclusion

The resistin + 299AA genotype may be associated with increases in the risk of the NAFLD development in T2DM patients.     

Leukemia inhibitory factor protects against liver steatosis in nonalcoholic fatty liver disease patients and obese mice

Nonalcoholic fatty liver disease (NAFLD) is one of the most common chronic liver diseases worldwide. However, the molecular mechanisms that promote dysregulation of hepatic triglyceride metabolism and lead to NAFLD are poorly understood, and effective treatments are limited. Leukemia inhibitory factor (LIF) is a member of the interleukin-6 cytokine family and has been shown to regulate a variety of physiological processes, although its role in hepatic triglyceride metabolism remains unknown. In the present study, we measured circulating LIF levels by ELISA in 214 patients with biopsy-diagnosed NAFLD as well as 314 normal control patients. We further investigated the potential role and mechanism of LIF on hepatic lipid metabolism in obese mice. We found that circulating LIF levels correlated with the severity of liver steatosis. Patients with ballooning, fibrosis, lobular inflammation, and abnormally elevated liver injury markers alanine transaminase and aspartate aminotransferase also had higher levels of serum LIF than control patients. Furthermore, animal studies showed that white adipose tissue–derived LIF could ameliorate liver steatosis through activation of hepatic LIF receptor signaling pathways. Together, our results suggested that targeting LIF-LIF receptor signaling might be a promising strategy for treating NAFLD.     

FOXK1 promotes nonalcoholic fatty liver disease by mediating mTORC1-dependent inhibition of hepatic fatty acid oxidation

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Study on the correlation between urinary retinol-binding protein and nonalcoholic fatty liver disease

BackgroundNonalcoholic fatty liver disease (NAFLD) affects human health worldwide. Our objective was to explore the correlation between urinary retinol-binding protein (URBP) and NAFLD.MethodsThis cross-sectional study included 445 NAFLD patients and 911 healthy controls. The URBP level and other parameters were measured.ResultsThe URBP level (expressed by the RBP/creatinine ratio) was higher in the NAFLD patients compared with the non-NAFLD patients. The urinary RBP/creatinine ratio was an independent risk factor for NAFLD after univariate and multivariate regression analysis, with the or values of 2.271 (1.795-2.872, P < 0.001) and 2.338 (1.775-3.080, P < 0.001), respectively. The prevalence of the urinary RBP/creatinine ratio (groups 1, 2, 3, 4) was 20.0%, 17.3%, 27.3%, and 35.4%, respectively (P < 0.001), and the prevalence of NAFLD in the high urinary RBP/creatinine ratio group was significantly higher than that in the low urinary RBP/creatinine ratio group.ConclusionsOur results revealed that the urinary RBP/creatinine ratio was an independent risk factor for NAFLD.     

莪术醇对非酒精性脂肪性肝大鼠肝功能和肝纤维化的影响及机制*

目的:探讨莪术醇(CC)对非酒精性脂肪性肝(NAFLD)大鼠模型肝功能和肝纤维化的影响及机制。方法:采用高脂饮食构建非酒精脂肪肝炎(NASH)伴肝纤维化的大鼠模型,将60只SD大鼠随机分为:空白对照组、模型组(NASH)、NASH+复方鳖甲软肝片(CBT)组(阳性对照组)、NASH+CC组(25、50、100 mg/kg),每组10只。测量大鼠肝脏占体重的百分比,测量大鼠高密度脂蛋白(HDL)、甘油三酯(TG)、谷丙转氨酶(ALT)、谷草转氨酶(AST)水平,HE染色观察肝纤维化情况,免疫组化检测鼠肝组织α-平滑肌肌动蛋白(α-SMA)表达及肝组织核因子κB p65(NF-κB p65)的阳性染色情况,蛋白印迹(Western blot)检测α-SMA、基质金属蛋白酶-1(MMP-1)、基质金属蛋白酶抑制剂-1(TIMP-1)蛋白表达及Toll样受体-4(TLR4)、转化生长因子激活激酶-1(TAK1)、NF-κB p65、血管细胞粘附分子-1(VCAM-1)蛋白的表达情况,酶联免疫吸附法(ELISA)检测肝组织中白介素(IL-6、IL-10、IL-1β)、肿瘤坏死因子-α(TNF-α)的表达。结果:与空白对照组相比,模型组大鼠HDL、 IL-10含量、MMP-1蛋白表达量显著降低(P＜0.05),TG、ALT、AST、肝组织P65阳性率,α-SMA、TIMP-1、TLR4、TAK1、NF-κB p65、VCAM-1表达、IL-6、TNF-α及IL-1β含量显著升高(P＜0.05)。与模型组相比,CBT和CC处理后大鼠HDL、 IL-10含量、MMP-1蛋白表达量显著升高(P＜0.05),TG、ALT、AST、肝组织P65阳性率,α-SMA、TIMP-1、TLR4、TAK1、NF-κB p65、VCAM-1表达、IL-6、TNF-α及IL-1β含量显著降低(P＜0.05),其中模型+CC组以高浓度组改善最显著(P＜0.05),但各剂量改善幅度均低于模型+CBT组(P＜0.05)。结论:莪术醇通过调节TLR4、TAK1、NF-κB p65信号通路,减轻炎症反应,改善肝功能,从而缓解非酒精性脂肪肝肝肝纤维化,且在一定范围内呈浓度依赖性。     

Progress in the search for circulating biomarkers of nonalcoholic fatty liver disease

Abstract

Context: The definitive standard for the diagnosis of nonalcoholic fatty liver disease (NAFLD) is clinico-pathological correlation, but frequently the only laboratory abnormality is an elevation of serum aminotransferases.

Objective: This has resulted in the search for more specific laboratory biomarkers.

Methods: The literature was searched for novel plasma/serum markers of NAFLD.

Results: Studies reviewed here included histologically-confirmed patients presenting some stage of NAFLD and monitored one or more novel serum/plasma biomarkers.

Conclusion: The most promising application of some of these novel biomarkers for the detection and quantification of NAFLD and particularly NASH appears to be in the combination of several into diagnostic panels.     

Inhibition of TREM-1 attenuates inflammation and lipid accumulation in diet-induced nonalcoholic fatty liver disease

In the liver tissues of obese diabetic or nondiabetic patients, triggering receptor expressed on myeloid cells-1 (TREM-1) is usually found to be upregulated, thus leading to upregulation of various inflammatory cytokines and lipid accumulation. On the other hand, nonalcoholic fatty liver disease (NAFLD), characterized by excess lipid accumulation, and inflammatory injury in liver, is becoming an epidemic disease, globally. In the present study, we aimed to investigate the biological role and the underlying mechanisms of TREM-1 in NAFLD. upregulation of TREM-1 occurred in high-fat diet (HFD)-induced mice NAFLD model and oleic acid-treated HepG2 and primary mouse hepatocytes cell model at messenger RNA and protein levels. Functional studies established that overexpression of TREM-1 displayed hyperlipidemia, and increased in inflammatory indicators and lipid accumulation-related genes, which was ameliorated by knockdown of TREM-1. Our results also showed that obvious lipid accumulation and inflammatory injury occurred in the liver tissue of HFD-fed mice, while treatment with lentiviral vector short hairpin TREM showed marked improvement in tissue morphology and architecture and less lipid accumulation, thus deciphering the mechanism through which knockdown of TREM-1 ameliorated the inflammatory response and lipid accumulation of NAFLD mice through inactivation of the nuclear factor-κB (NF-κB) and PI3K/AKT signal pathways, respectively. In conclusion, TREM-1/NF-κB and TREM-1/PI3K/AKT axis could be an important mechanism in ameliorating the inflammatory response and lipid accumulation, respectively, thus shedding light on the development of novel therapeutics to the treatment of NAFLD.     

非酒精性脂肪肝病形成机制:补体和线粒体在其形成中的作用

非酒精性脂肪肝病(nonalcoholic fatty liver disease,NAFLD)作为一种流行性代谢疾病,一直是研究热点之一.NAFLD的形成涉及线粒体功能障碍、胰岛素抵抗、氧化应激、炎症反应等机制,而线粒体与补体在其中占据重要位置.然而,线粒体与补体在NAFLD形成过程中的内在关联及协同作用目前尚不十分...     

Probiotics: A possible specific liver drug for non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) is and will continue to be a major liver health issue worldwide in the coming decades. There are no leading drug candidates at this point, although there are several promising concepts in drug development. Recent studies have proposed a possible role of intestinal bacterial overgrowth in the development of non-alcoholic steatohepatitis, thus indicated probiotics maybe a potential specific liver drug for NAFLD in the future.     

Liver-directed microRNA-7a depletion induces nonalcoholic fatty liver disease by stabilizing YY1-mediated lipogenic pathways in zebrafish

Nonalcoholic fatty liver disease (NAFLD) has been associated with the function and changes in expression levels of microRNAs (miRs). MiR-7 has been proven to play an important role in many cellular processes; however, its functions in the context of liver lipogenesis remain unknown. We applied the microRNA-sponge (miR-SP) technology and generated transgenic miR-7a-SP models (hC7aSP and bC7aSP), which disrupted the activities of hepatic miR-7a and induced the early onset of NAFLD and nonalcoholic steatohepatitis (NASH) in zebrafish. We identified a novel miR-7a target, YY1, and demonstrated novel miR-7a functions to regulate zebrafish hepatic lipid metabolism by controlling YY1 stabilization through the regulation of the expression of lipogenic signaling pathways. Correspondingly, liver specific miR-7a depletion functionally promoted lipid accumulation in hC7ASP livers. NASH hC7aSP increased the expression of inflammatory genes (il-1b, il-6, tnf-α, ifn-γ, nfkb2, and NF-kB) and endoplasmic reticulum stress markers (atf6, ern2, ire1, perk, hspa5 and ddit3). Molecular analysis revealed that miR-7a-SP can stabilize YY1 expression and contribute to the accumulation of hepatic triglycerides by reducing the CHOP-10 expression in the hC7aSP and then inducing the transactivation of C/EBP-α and PPAR-γ expression. PPAR-γ antagonists and miR-7a mimic treatment ameliorate hC7aSP NASH phenotypes. Conclusion: Our results suggest that miR-7a-SP acts as a lipid enhancer by directly increasing YY1 stability to disrupt CHOP-10-dependent suppression of lipogenic pathways, resulting in increased lipid accumulation. MiR-7a expression improves liver steatosis and steatohepatitis in hC7aSPs, which suggests a novel strategy for the prevention and early treatment of NASH in humans.