PNPLA3 I148M and response to treatment for hepatic steatosis: A systematic review

Background

It is unclear whether the patatin-like phospholipase domain-containing protein 3 (PNPLA3) rs738409 C-to-G single nucleotide polymorphism, resulting in the substitution of isoleucine to methionine at position 148 (I148M), impedes regression of hepatic steatosis when treating non-alcoholic fatty liver disease (NAFLD).

Objectives

Investigate if carriage of the PNPLA3 148M allele affects the anti-steatotic efficacy of all possible anti-NAFLD interventions, identify gaps in current knowledge and provide guidance for individual treatment.

Methods

Research available in public databases was searched up to 13 November 2022. Studies were included if a treatment in NAFLD patients decreased hepatic steatosis in the pooled patient group or a PNPLA3 I148M polymorphism subgroup (II/IM/MM). The risk of bias was assessed using the Cochrane Risk-Of-Bias 2 Tool and the Newcastle–Ottawa Scale.

Results

Moderate evidence indicates that NAFLD patients homozygous for the PNPLA3 148M allele benefit less or not at all from omega-3 carboxylic acids to decrease liver fat, while the PNPLA3 148I allele shows moderate benefit. Low evidence suggests that interventions employing lifestyle changes are more effective to reduce liver fat in NAFLD patients homozygous for the PNPLA3 148M allele compared to patients with wild-type PNPLA3.

Conclusions

NAFLD patients homozygous for the PNPLA3 148M allele might not benefit from omega-3 carboxylic acids to reduce hepatic steatosis in contrast to patients with wild-type PNPLA3. Instead, patients with two PNPLA3 148M alleles should be especially advised to adopt lifestyle changes. Genotyping for PNPLA3 I148M should be encouraged in therapeutic studies for NAFLD.

Registration Number (Prospero)

CRD42022375028.     

Non-alcoholic fatty liver disease: an overview

Non-alcoholic fatty liver disease (NAFL) includes a spectrum of clinicopathological conditions with increasing prevalence in the developed world. Although steatosis alone seems to have a benign course, those patients with the diagnosis of non-alcoholic steatohepatitis (NASH) can have a progressive course. Additionally, there is now evolving, indirect evidence that some of the patients with cryptogenic cirrhosis may be the result of 'burned-out' NASH. Although NAFL and NASH are associated with insulin-resistance syndrome, some patients with NAFL may have no obvious risk factors. Despite preliminary data from a number of pilot studies, no established therapies can be offered to patients with NASH. Over the next few years, a number of exciting research projects dealing with the epidemiology as well as the pathogenesis of NAFL are expected to be completed. It is anticipated that, through a better understanding of NAFL, more effective treatment protocols can be developed targeting only those patients with NASH that are at the highest risk for progression to cirrhosis and liver failure.     

Predictors of fibrosis in Asian patients with non-alcoholic steatohepatitis

Background and Aim: Non‐alcoholic steatohepatitis (NASH) is increasingly recognized as an important cause of chronic liver disease. However, data on Asians with NASH is lacking in the literature. The aim of the present study was to describe the clinical, biochemical and histological characteristics of NASH in Asians and to determine the predictors for septal fibrosis. Method: Sixty consecutive patients aged over 18 years with elevated serum alanine transferase, sonographic evidence of steatosis, and consent for liver biopsy were included. Patients with chronic hepatitis B or C, alcoholic, autoimmune, genetic, or drug‐induced liver disease were excluded. Clinical, biochemical and histological variables were tested for association with septal liver fibrosis (F2/3). Results: Median age of the cohort was 45.5 years (range 21–75 years) and 63% were male. Ninety percent of patients were obese (body mass index [BMI]≥ 25), 70% had hypertriglyceridemia, 68% had hypercholesterolemia, 58% had metabolic syndrome, 53% had hypertension, 47% had diabetes mellitus (DM), and 18% had obstructive sleep apnea. Sixty‐eight percent had gamma‐glutamyl transferase (GGT) ≥ 2 × upper limit of normal (ULN), 55% had alanine aminotransferase (ALT) ≥ 2 × ULN, and 23% had aspartate aminotransferase (AST) ≥ 2 × ULN. Of the 40 non‐diabetic patients undergoing oral glucose tolerance testing, 45% had normal tests, 30% had impaired glucose tolerance, 23% DM, and 2% impaired fasting glucose. Eighteen patients (30%) had septal fibrosis (F2/3), but none had cirrhosis. Necroinflammatory grade ≥ 2 (odds ratio [OR] 13), AST ≥ 2 × ULN (OR 5.3) and DM (OR 5) were significantly and independently correlated with septal fibrosis. Conclusion: Septal fibrosis is common in Asians with NASH. Necroinflammatory grade ≥ 2, AST ≥ 2 × ULN and DM are independent predictors for septal fibrosis.     

A look to the future in non-alcoholic fatty liver disease: Are glucagon-like peptide-1 analogues or sodium-glucose co-transporter-2 inhibitors the answer?

The increasing prevalence of diabetes and non-alcoholic fatty liver disease (NAFLD) is a growing public health concern associated with significant morbidity, mortality and economic cost, particularly in those who progress to cirrhosis. Medical treatment is frequently limited, with no specific licensed treatments currently available for people with NAFLD. Its association with diabetes raises the possibility of shared mechanisms of disease progression and treatment. With the ever-growing interest in the non-glycaemic effects of diabetes medications, studies and clinical trials have investigated hepatic outcomes associated with the use of drug classes used for people with type 2 diabetes (T2D), such as glucagon-like peptide-1 (GLP-1) analogues or sodium-glucose co-transporter-2 (SGLT2) inhibitors. Studies exploring the use of GLP-1 analogues or SGLT2 inhibitors in people with NAFLD have observed improved measures of hepatic inflammation, liver enzymes and radiological features over short periods. However, these studies tend to have variable study populations and inconsistent reported outcomes, limiting comparison between drugs and drug classes. As these drugs appear to improve biomarkers of NAFLD, clinicians should consider their use in patients with NAFLD and T2D. However, further evidence with greater participant numbers and longer trial durations is required to support specific licensing for people with NAFLD. Larger trials would allow reporting of major adverse hepatic events, akin to cardiovascular and renal outcome trials, to be determined. This would provide a more meaningful evaluation of the impact of these drugs in NAFLD. Nevertheless, these drugs represent a future potential therapeutic avenue in this difficult-to-treat population and may beget significant health and economic impacts.     

复方甘枣宁预防大鼠非酒精性脂肪肝的实验研究

[目的]研究复方甘枣宁对高脂饮食诱发的大鼠脂肪肝的预防作用.[方法]采用高脂饲料喂饲制作大鼠非酒精性脂肪肝模型,同时以复方甘枣宁灌胃,12周后检测血清中总胆固醇(TC)、三酰甘油(TG)、高密度脂蛋白胆固醇(HDL-C)、低密度脂蛋白胆固醇(LDL-C)、丙氨酸氨基转移酶(ALT)、天冬氨酸转氨酶(AST)水平,并作病理组织学观察,同时称体重、肝脏重,计算肝指数.[结果]复方甘枣宁明显减轻肝组织内脂肪变性,降低血清TC与AST水平.[结论]复方甘枣宁对高脂饮食诱发的大鼠非酒精性脂肪肝具有一定的预防作用.     

How common is non‐alcoholic fatty liver disease in the Asia–Pacific region and are there local differences?

Risk factors for development of non-alcoholic steatohepatitis include obesity, especially central adiposity, glucose intolerance or type 2 diabetes mellitus (T2DM), and dyslipidemia. Non-alcoholic fatty liver disease (NAFLD) is now considered a manifestation of metabolic syndrome. During the last two decades, NAFLD has become the most common chronic liver disease in North America and Europe, but until recently was thought to be uncommon (perhaps due to the lack of study) in Asia. Fatty liver can be identified on imaging modalities (ultrasonography, computed tomography scans, and magnetic resonance imaging) with high sensitivity, but steatohepatitis and fibrosis cannot be distinguished. Thus, an inherent drawback in studying the epidemiology of NAFLD is the lack of definitive laboratory tests, no uniform definition-with different studies using cut-off values of alcohol consumption from <20 g/week to 210 g/week, and case selections where biopsy was used for definition. In studies outside the region, the prevalence of NAFLD varies from 16% to 42% by imaging, and 15-39% of liver biopsies. The major risk factors for NAFLD, central obesity, T2DM, dyslipidemia, and metabolic syndrome, are now widely prevalent and are increasing geometrically in the Asia-Pacific region. It is therefore not surprising that NAFLD is common in this region. Estimates of current prevalence range from 5% to 30%, depending on the population studied. Central obesity, diabetes, and metabolic syndrome are the major risk factors. To date, however, data on the natural history and impact of NAFLD causing serious significant chronic liver disease are lacking and there is a need for prospective, cooperative studies.     

Effects of estrogen and androgen deprivation on the progression of non-alcoholic steatohepatitis (NASH) in male Sprague–Dawley rats

Aim:  We studied the mechanisms of estrogen/androgen involvement in the induction of NASH by treating Sprague–Dawley (SD) rats fed with a normal or high fat (HF) diet by depriving them of endogenous estrogens/androgens.
Methods:  Male adult SD rats ( n  = 10/group) on normal or HF diets were treated for 75 days either with tamoxifen (Tam) or flutamide (Flu) or Tam + Flu in order to induce NASH. We analyzed histopathologically the liver samples from the treated groups for NASH, checked the serum biochemical and lipid profile markers and finally analyzed the signal pathways underlying the molecular mechanisms for the induction process of NASH.
Results:  Deprivation of endogenous estrogens and/or androgens (Tam or Flu or Tam + Flu) without the HF diet did not induce NASH. Tam or Tam + Flu induced NASH, compared to milder lesions without fibrosis in HF diet and Flu-treated liver. Serum alanine aminotransferase or lipid profile markers further proved the Tam, Flu or Tam + Flu effects on the induction of NASH in conjunction with a HF diet. Tam treatment predominantly downregulated the ERα and FAS and upregulated UCP2 and TNF-α.
Conclusions:  Deprivation of endogenous estrogen/androgens in conjunction with a HF diet may induce NASH where the downregulated ERα and FAS, and upregulated UCP2 and TNF-α could be involved in their molecular pathomechanism pathways. These results could suggest the potential negative roles of estrogenic/androgenic depriving compounds in the induction of NASH, along with obesity.     

Commonly used animal models of non-alcoholic steatohepatitis

BACKGROUND:Animal models are an essential tool in non-alcoholic steatohepatitis (NASH) studies. Ideally, such models should reflect the etiology, disease progression, and the established pathology of human NASH. To date, no single animal model displays the range of histopathologic and pathophysiologic features associated with human NASH. The currently available models do not or only partially reflect the real picture of human NASH. In particular, insulin resistance and fibrosing steatohepatitis are rarely r...     

Current management of non‐alcoholic steatohepatitis

Non‐alcoholic steatohepatitis (NASH) is the most common cause of liver disease in Western populations, and its prevalence is increasing rapidly. It is part of a multisystem disease affecting other organs such as the kidneys, heart and blood vessels, and is closely associated with the components of the metabolic syndrome. Physicians managing patients with NASH should not only focus on the management of NASH, but also on associated comorbidities in individual patients. The approaches to treatment of NASH include either limiting energy surplus alone, or in combination with targeting of downstream pathways of inflammation and fibrosis. In this mini‐review, we discuss the currently available treatment options for NASH, as well as those in late‐stage clinical trials. We discuss the challenges of managing these patients with a limited number of approved therapies, as well as managing advanced‐stage patients with NASH and cirrhosis. We also discuss the specific management of comorbidities in NASH patients, in particular diabetes, hypertension, dyslipidaemia and cardiovascular diseases. Finally, we present the screening protocols for both hepatocellular carcinoma and extrahepatic malignancies in these patients.     

罗格列酮对大鼠非酒精性脂肪性肝炎逆转机制的研究

目的 探讨过氧化物酶体增殖物激活受体γ（PPAR-γ）激动剂罗格列酮对库普弗细胞中LPS诱导的IκB激酶-β（IKK-β）表达以及对NASH大鼠肝组织核因子-κB（NF-κB）活性和环氧合酶-2（COX-2）表达水平的影响及意义。方法 采用Ⅳ型胶原酶消化和密度梯度离心的方法分离纯化正常Wistar大鼠库普弗细胞,并应用LPS（1μg／ml）及不同浓度的罗格列酮（10 nmol／L和50 nmol／L）干预培养,收集细胞及培养上清液。体内实验：健康雄性Wistar大鼠随机分为正常组和模型组,后者以高脂饲料（2％胆固醇＋10%猪油＋5％玉米油）喂养复制NASH大鼠动物模型,造模成功后,分别以1 mg·kg^-1·d^-1、4mg·kg^-1·d^-1剂量的罗格列酮和等容积等渗盐水灌胃,实验结束后采集大鼠血清和肝组织标本。RT-PCR检测库普弗中细胞IKK-β、肝组织中COX-2 mRNA的表达,Western blot和电泳迁移率改变分析（EMSA）分别检测库普弗细胞中IKK-β蛋白表达和肝组织NF-κB活性变化,ELISA检测细胞培养上清液及血清中TNFα水平。结果 LPS可显著增高体外培养库普弗细胞中IKK-βmRNA、蛋白的表达及上清液中TNFα水平。模型组大鼠肝组织COX-2 mRNA和蛋白的表达均较正常对照组增强,NF-κB活性与COX-2的表达和血清TNFα水平呈正相关。罗格列酮体外可抑制LPS诱导库普弗细胞中IKK-βmRNA和蛋白的表达,体内通过抑制肝组织NF-κB活化,减少COX-2表达,均表明罗格列酮可通过抑制炎症细胞活化,下调炎症介质基因表达,从而减少了NFα等炎症介质合成、释放,抑制肝脏炎症反应。结论 PPAR-γ特异性激动剂罗格列酮通过干预IKK-β／IκB／NF-κβB／TNFα信号通路而发挥抗炎作用,从细胞分子水平逆转NASH大鼠肝组织的炎症反应,这为临床上有效治疗NASH提供了新思路。     

Non-alcoholic steatohepatitis in type 2 diabetes mellitus

BACKGROUND AND AIMS: Non-alcoholic steatohepatitis (NASH) is commonly associated with type 2 diabetes mellitus (DM). Prevalence of NASH in type 2 DM has not been well studied and there is an epidemic rise in type 2 DM in Asian and Western populations. Its association with chronic liver disease in the form of NASH makes it an important health problem. Hence we have studied its prevalence and correlation of biochemical parameters with histological grades of non-alcoholic fatty liver disease (NAFLD) in otherwise asymptomatic type 2 DM patients. METHODS: One hundred and forty-eight individuals were screened. Forty-eight individuals were excluded due to history of alcohol intake or liver disease as a result of other causes. One hundred non-alcoholic individuals with type 2 DM underwent abdominal ultrasonography (US abdomen). Forty-nine patients had evidence of fatty liver on US abdomen, and 32 of these 49 patients underwent liver biopsy. RESULTS: Four of 32 (12.5%) individuals had steatosis alone. Mild, moderate and severe NASH was present in 21/32 (65.5%), 4/32 (12.5%) and 3/32 (9.35%), respectively. Fibrosis was present in 7/32 (21.8%) patients (four grade 1 and three grade 3). There was no significant difference in body mass index (BMI), transaminase levels, serum cholesterol and triglyceride levels among patients with non-alcoholic fatty liver disease. CONCLUSION: We conclude that the prevalence of NASH is high in type 2 DM patients and liver biopsy is the only investigation to differentiate between non-alcoholic fatty liver and steatohepatitis.     

成人非酒精性脂肪肝与代谢综合征关系的研究

目的探讨非酒精性脂肪肝(NAFLD)和代谢综合征(MS)的关系。方法对2006年10～12月长沙市某企业3744例20岁以上职工进行问卷调查、体格检查、空腹血糖、血脂、丙氨酸转氨酶、血尿酸检测以及肝脏B超检查。结果(1)NAFLD患病率23.5%,MS患病率22.8%,两病的共患病率12.6%。(2)MS、中心性肥胖、血压升高、空腹血糖升高、高三酰甘油、低高密度脂蛋白胆固醇各组NAFLD患病风险分别是对照组的13.4～22.2倍。(3)以NAFLD取代MS5个组分中的任何一个后,与原诊断定义相比有较高一致性(Kappa值0.53～0.89,P<0.01)。(4)采用多因素Logistic回归分析,调整了性别、年龄和多项代谢成分的影响后,NAFLD与MS独立相关(OR2.342,95%CI:1.825～3.007;P<0.01)。结论该人群中1/5以上患有NAFLD和MS,且NAFLD与MS密切相关;NAFLD可纳入MS的组成成分。     

非酒精性脂肪性肝病与过氧化物酶体活化物激活受体α基因Val227Ala多态性的关系

脂肪肝是遗传-环境-代谢应激相关因素所致的以肝细胞脂肪变性为主的临床病理综合征,临床上则有酒精性脂肪性肝病和NAFLD之分。过氧化物酶体活化物激活受体α(peroxisome proliferator-activated receptor alpha,PPARα)基因参与体内脂质代谢平衡,PPARα功能异常会影响脂肪酸的正常代谢引起肝细胞脂肪变性。本研究旨在通过研究NAFLD患者与正常人群PPARα基因Val227Ala多态性的分布,进一步探讨其与PPARα基因Val227Ala多态性与     

Impact of Pemafibrate in Patients with Hypertriglyceridemia and Metabolic Dysfunction-associated Fatty Liver Disease Pathologically Diagnosed with Non-alcoholic Steatohepatitis: A Retrospective,Single-arm Study

Objective The therapeutic effect of pemafibrate on metabolic dysfunction-associated fatty liver disease (MAFLD) remains unknown. This retrospective, single-arm study investigated the efficacy and safety of pemafibrate in MAFLD patients with hypertriglyceridemia. Methods A total of 10 patients who received pemafibrate (oral, 0.1 mg, twice a day) at Gunma Saiseikai Maebashi Hospital between September 2018 and September 2019 were included. All patients underwent a liver biopsy, and the disease grade and stage were pathologically assessed based on the FLIP algorithm. Results The median age was 66.0 (53.8-74.8) years old, and 5 patients (50.0%) were men. All patients were diagnosed with non-alcoholic steatohepatitis (NASH). The fasting and non-fasting triglyceride (TG) levels were 175 (149-247) mg/dL and 228 (169-335) mg/dL, respectively. The AST and ALT values at 6 months were significantly lower than at baseline [AST: 28.0 (22.0-33.8) U/L vs. 43.5 (24.0-55.0) U/L, p=0.008, ALT: 23.0 (14.8-26.5) U/L vs. 51.5 (23.0-65.3) U/L, p=0.005, respectively], especially in NASH patients with significant activity and advanced fibrosis (p=0.040 and 0.014, respectively). Fasting TG levels were significantly lower and HDL-C levels significantly higher at 6 months than at baseline (p=0.005 and 0.032, respectively). At six months, FIB-4, the aspartate aminotransferase-to-platelet ratio index, and the macrophage galactose-specific lectin-2 binding protein glycosylation isomer level were significantly improved compared with baseline (p=0.041, 0.005 and 0.005, respectively). Treatment-related adverse events were not observed. Conclusion Pemafibrate treatment may be safe and effective for MAFLD patients with hypertriglyceridemia.     

Inflammatory and fibrotic mechanisms in NAFLD—Implications for new treatment strategies

Non-alcoholic fatty liver disease is comprised of either simple steatosis (non-alcoholic fatty liver) or a more advanced inflammatory and fibrogenic stage (non-alcoholic steatohepatitis [NASH]). NASH affects a growing proportion of the global adult and pediatric population, leading to rising rates of liver fibrosis and hepatocellular carcinoma. NASH is a multifactorial disease that is part of a systemic metabolic disorder. Here, we provide an overview of the metabolic underpinnings of NASH pathogenesis and established drivers of inflammation and fibrosis. Clarification of underlying fibrogenic and inflammatory mechanisms will advance the development of novel treatment strategies as there are no approved therapies at present. We discuss emerging experimental approaches and potential novel investigational strategies derived from animal models including the inflammasome, epigenetic reprogramming, Hippo signaling, Notch signaling, engineered T cells to remove fibrogenic HSCs, and HSC-specific targeting therapies. Recently completed and ongoing clinical trials and antifibrotics are discussed, illuminating the growing expectation that one or more therapies will yield clinical benefit in NASH in the coming years.     

Non-alcoholic fatty liver disease in the Asia-Pacific region: definitions and overview of proposed guidelines

Non-alcoholic fatty liver disease (NAFLD) is the most common liver disorder in Western industrialized countries, affecting 20-40% of the general population. Large population-based surveys in China, Japan, and Korea indicate that the prevalence of NAFLD is now 12% to 24% in population subgroups, depending on age, gender, ethnicity, and location (urban versus rural). There is strong evidence that the prevalence of NAFLD has increased recently in parallel with regional trends in obesity, type 2 diabetes, and metabolic syndrome; and that further increases are likely. The relationship between NAFLD, central obesity, diabetes, and metabolic syndrome is clearly evident in retrospective and prospective Asian studies, but the strength of association with these metabolic risk factors is only appreciated when regional definitions of anthropometry are used. Pathological definition of NAFLD, particularly its activity and the extent of liver fibrosis, requires histological examination, but liver biopsy is often not appropriate in this disorder for logistic reasons. An alternative set of operational definitions is proposed here. Clinicians need guidelines as how best to diagnose and manage NAFLD and its associated metabolic disorders in countries with scant healthcare resources. The Asia-Pacific Working Party (APWP) for NAFLD was convened to collate evidence and deliberate these issues. Draft proposals were presented and discussed at Asia-Pacific Digestive Week at Cebu, Philippines, in late November 2006, and are published separately in this issue of the Journal as an Executive Summary. The present document reviews the reasoning and evidence behind the APWP-NAFLD proposals for definition, assessment, and management of NAFLD in the Asia-Pacific region.