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。     

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。     

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.     

Peroxisome proliferator-activated receptors alpha and gamma2 polymorphisms in nonalcoholic fatty liver disease: A study in Brazilian patients

Background

Non-alcoholic fatty liver disease (NAFLD) refers to the accumulation of hepatic steatosis in the absence of excess alcohol consumption. The pathogenesis of fatty liver disease and steatohepatitis (NASH) is not fully elucidated, but the common association with visceral obesity, hyperlipidemia, hypertension and type 2 diabetes mellitus (T2DM) suggests that it is the hepatic manifestation of metabolic syndrome. Peroxisome proliferator-activated receptor PPARα and PPARγ are members of a family of nuclear receptors involved in the metabolism of lipids and carbohydrates, adipogenesis and sensitivity to insulin. The objective of this study was to analyze the polymorphisms Leu162Val of PPARα and Pro12Ala of PPARγ as genetic risk factors for the development and progression of NAFLD.

Methods

One hundred and three NAFLD patients (89 NASH, 14 pure steatosis) and 103 healthy volunteers were included. Single nucleotide polymorphisms (SNPs) Leu162Val and Pro12Ala were analyzed by polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP).

Results

NASH patients presented higher BMI, AST and prevalence of T2DM than patients with pure steatosis. A higher prevalence of 12Ala allele was observed in the NASH Subgroup when compared to Control Group. When we grouped NASH and Steatosis Subgroups (NAFLD), we found lower serum glucose and more advanced fibrosis in the Leu162Val SNP. On the other hand, there was no statistical difference in clinical, laboratorial and histological parameters according to the Pro12Ala SNP.

Conclusions

We documented a lower prevalence of 12Ala allele of gene PPARγ in the NASH Subgroup when compared to Control Group. In NAFLD patients, there were no associations among the occurrence of Pro12Ala SNP with clinical, laboratorial and histological parameters. We also documented more advanced fibrosis in the Leu162Val SNP. The obtained data suggest that Pro12Ala SNP may result in protection against liver injury and that Leu162Val SNP may be involved in the progression of NAFLD.     

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.     

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.     

Hypoxia inducible factor-1 promotes liver fibrosis in nonalcoholic fatty liver disease by activating PTEN/p65 signaling pathway

Obesity is a major contributor to the development of steatohepatitis and fibrosis from nonalcoholic fatty liver disease (NAFLD). Hypoxia aggravates progression of NAFLD. In mice on high-fat diet (HFD), hepatic steatosis leads to liver tissue hypoxia, evidenced by accumulation of hypoxia inducible factor-1-alpha (HIF-1α), which is a central regulator of the global response to hypoxia. Hepatocyte cell signaling is an important factor in hepatic fibrogenesis. We here hypothesize that HIF-1α knockout in hepatocyte may protect against liver fibrosis. We first found that HFD led to 80% more hepatic collagen deposition than Hif1a^−/−hep mice, which was confirmed by a-SMA staining of liver tissue. Body weight and liver weight were similar between groups. We then found the increasing HIF1a expression and decreasing PTEN expression in the mice on HFD and in PA-treated HepG2 cells. Finally, we found that HIF1 mediated PTEN/nfkb-p65 pathway plays an important role in the development of NAFLD to liver fibrosis. Collectively, these results identify a novel HIF1a/PTEN/NF-κ Bp65 signaling pathway in NAFLD, which could be targeted for the therapy.     

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.     

非酒精性脂肪肝病患者肠道AKK菌与肝功能指标的变化及其影响

目的探究非酒精性脂肪肝病(NAFLD)患者肠道AKK菌及肝功能指标的变化及其影响。方法选取我院2017年3月至2018年11月门诊诊断为NAFLD的109名患者作为NAFLD组。选取同期352名健康志愿者作为对照组。比较两组研究对象体质量指数(BMI)、总胆固醇(TG)、甘油三酯(TC)、高密度脂蛋白(HDLC)、谷丙转氨酶(ALT)、谷草转氨酶(AST)、谷氨酰转肽酶(GGT)的水平及粪便中AKK菌的相对数量。结果NAFLD组患者肠道AKK菌均数为(6.12±1.04),对照组为(6.78±1.07),差异有统计学意义(t=5.664,P<0.001)。NAFLD组患者BMI、LDLC、ALT、AST、GGT的水平显著高于对照组,而HDLC水平显著低于对照组,差异均有统计学意义(均P<0.05)。多因素Logistic回归分析显示AKK菌数量和HDLC为NAFLD的独立保护因素,BMI、ALT、AST、GGT为独立危险因素。结论NAFLD患者肠道中AKK菌数量发生显著变化,AKK菌对NAFLD患者具有保护作用,可为肠道微生物参与NAFLD的发病机制研究提供新的视角。     

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...     

The DNA damage checkpoint protein ATM promotes hepatocellular apoptosis and fibrosis in a mouse model of non-alcoholic fatty liver disease

Steatoapoptosis is a hallmark of non-alcoholic fatty liver disease (NAFLD) and is an important factor in liver disease progression. We hypothesized that increased reactive oxygen species resulting from excess dietary fat contribute to liver disease by causing DNA damage and apoptotic cell death, and tested this by investigating the effects of feeding mice high fat or standard diets for 8 weeks. High fat diet feeding resulted in increased hepatic H₂O₂, superoxide production, and expression of oxidative stress response genes, confirming that the high fat diet induced hepatic oxidative stress. High fat diet feeding also increased hepatic steatosis, hepatitis and DNA damage as exemplified by an increase in the percentage of 8-hydroxyguanosine (8-OHG) positive hepatocytes in high fat diet fed mice. Consistent with reports that the DNA damage checkpoint kinase Ataxia Telangiectasia Mutated (ATM) is activated by oxidative stress, ATM phosphorylation was induced in the livers of wild type mice following high fat diet feeding. We therefore examined the effects of high fat diet feeding in Atm-deficient mice. The prevalence of apoptosis and expression of the pro-apoptotic factor PUMA were significantly reduced in Atm-deficient mice fed the high fat diet when compared with wild type controls. Furthermore, high fat diet fed Atm^?/? mice had significantly less hepatic fibrosis than Atm^+/+ or Atm^+/? mice fed the same diet. Together, these data demonstrate a prominent role for the ATM pathway in the response to hepatic fat accumulation and link ATM activation to fatty liver-induced steatoapoptosis and fibrosis, key features of NAFLD progression.     

The DNA damage checkpoint protein ATM promotes hepatocellular apoptosis and fibrosis in a mouse model of non-alcoholic fatty liver disease

Steatoapoptosis is a hallmark of non-alcoholic fatty liver disease (NAFLD) and is an important factor in liver disease progression. We hypothesized that increased reactive oxygen species resulting from excess dietary fat contribute to liver disease by causing DNA damage and apoptotic cell death, and tested this by investigating the effects of feeding mice high fat or standard diets for 8 weeks. High fat diet feeding resulted in increased hepatic H₂O₂, superoxide production, and expression of oxidative stress response genes, confirming that the high fat diet induced hepatic oxidative stress. High fat diet feeding also increased hepatic steatosis, hepatitis and DNA damage as exemplified by an increase in the percentage of 8-hydroxyguanosine (8-OHG) positive hepatocytes in high fat diet fed mice. Consistent with reports that the DNA damage checkpoint kinase Ataxia Telangiectasia Mutated (ATM) is activated by oxidative stress, ATM phosphorylation was induced in the livers of wild type mice following high fat diet feeding. We therefore examined the effects of high fat diet feeding in Atm-deficient mice. The prevalence of apoptosis and expression of the pro-apoptotic factor PUMA were significantly reduced in Atm-deficient mice fed the high fat diet when compared with wild type controls. Furthermore, high fat diet fed Atm^−/− mice had significantly less hepatic fibrosis than Atm^+/+ or Atm^+/− mice fed the same diet. Together, these data demonstrate a prominent role for the ATM pathway in the response to hepatic fat accumulation and link ATM activation to fatty liver-induced steatoapoptosis and fibrosis, key features of NAFLD progression.     

酪酸梭菌活菌胶囊辅助治疗对非酒精性脂肪肝病患者氧化应激损伤的保护作用

目的 探讨酪酸梭菌活菌胶囊辅助治疗对非酒精性脂肪肝病(nonalcoholic fatty liver disease,NAFLD)患者氧化应激损伤的保护作用。 方法 选取2017年1月至2019年3月我院内科门诊就诊的NAFLD患者76例,随机分为观察组和对照组,各38例。两组患者均给予饮食调整、纠正不良生活习惯和适当运动锻炼。对照组患者给予多烯磷脂酰胆碱胶囊456 mg/次,3次/d,口服。观察组患者在对照组基础上加用酪酸梭菌活菌胶囊0.6 g/次,2次/d,温水口服。两组患者连用8周。检测两组患者治疗前后肝功能指标[丙氨酸转氨酶(ALT)、碱性磷酸酶(ALP)、γ 谷氨酰转肽酶(γ GT)]及氧化应激指标[氧化低密度脂蛋白(ox LDL)、过氧化脂质(LPO)、丙二醛(MDA)]水平的变化。 结果 治疗8周后,两组患者血清ALT、ALP和γ GT水平较治疗前明显下降,且观察组下降幅度大于比对照组(均P结论 酪酸梭菌活菌胶囊辅助治疗NAFLD患者能降低血清ox LDL、LPO和MDA水平,抑制氧化应激反应亢进,保护肝功能。     

Lipotoxicity and steatohepatitis in an overfed mouse model for non-alcoholic fatty liver disease

The major risk factors for non-alcoholic fatty liver disease (NAFLD) are obesity, insulin resistance and dyslipidemia. The cause for progression from the steatosis stage to the inflammatory condition (non-alcoholic steatohepatitis (NASH)) remains elusive at present. Aim of this study was to test whether the different stages of NAFLD as well as the associated metabolic abnormalities can be recreated in time in an overfed mouse model and study the mechanisms underlying the transition from steatosis to NASH.Male C57Bl/6J mice were subjected to continuous intragastric overfeeding with a high-fat liquid diet (HFLD) for different time periods. Mice fed a solid high-fat diet (HFD) ad libitum served as controls. Liver histology and metabolic characteristics of liver, white adipose tisue (WAT) and plasma were studied.Both HFD-fed and HFLD-overfed mice initially developed liver steatosis, but only the latter progressed in time to NASH. NASH coincided with obesity, hyperinsulinemia, loss of liver glycogen and hepatic endoplasmatic reticulum stress. Peroxisome proliferator-activated receptor γ (Pparγ), fibroblast growth factor 21 (Fgf21), fatty acid binding protein (Fabp) and fatty acid translocase (CD36) were induced exclusively in the livers of the HFLD-overfed mice. Inflammation, reduced adiponectin expression and altered expression of genes that influence adipogenic capacity were only observed in WAT of HFLD-overfed mice.In conclusion: this dietary mouse model displays the different stages and the metabolic settings often found in human NAFLD. Lipotoxicity due to compromised adipose tissue function is likely associated with the progression to NASH, but whether this is cause or consequence remains to be established.