Nonalcoholic Steatohepatitis: A Review

Therapeutic approaches for non-alcoholic steatohepatitis

Non-alcoholic fatty liver disease (NAFLD) and non-alcoholic steatohepatitis (NASH) have been reported as a novel worldwide epidemic, very often associated with obesity, metabolic syndrome, and type 2 diabetes. Both conditions have also been shown to be associated with a number of endocrine pathologies. Despite the epidemic, the complex pathophysiology and major complications, ranging from metabolic disturbances (diabetes and more) to cardiovascular disease, people with NASH are left with very few management options. The best and most approved therapeutic option is lifestyle intervention. Although pharmacotherapies based on pathophysiological background are in development, response rates appear modest, mainly for fibrosis treatment, which is the reason for lack of approved drug therapy. Previous drugs analyzed, such as pioglitazone and vitamin E, show weak efficacy. From different phase II trials, antidiabetic (injectable) drugs seem to be promising, both in mono- or bitherapy. Also, derivatives of peroxisome proliferator-activated receptors may have an interesting future, as well. For that reason, more focus should be given on prevention of this novel disease entity. In view of this booming epidemic, with a background of obesity and type 2 diabetes, and the important medical consequences, early recognition, prevention and intervention of NAFLD/NASH seems appropriate. In this review, we will focus on the different current and future therapeutic intervention options, taking into consideration the complex pathophysiology of this disease.

Oxidative Stress in NAFLD: Role of Nutrients and Food Contaminants

Non-alcoholic fatty liver disease (NAFLD) is often the hepatic expression of metabolic syndrome and its comorbidities that comprise, among others, obesity and insulin-resistance. NAFLD involves a large spectrum of clinical conditions. These range from steatosis, a benign liver disorder characterized by the accumulation of fat in hepatocytes, to non-alcoholic steatohepatitis (NASH), which is characterized by inflammation, hepatocyte damage, and liver fibrosis. NASH can further progress to cirrhosis and hepatocellular carcinoma. The etiology of NAFLD involves both genetic and environmental factors, including an unhealthy lifestyle. Of note, unhealthy eating is clearly associated with NAFLD development and progression to NASH. Both macronutrients (sugars, lipids, proteins) and micronutrients (vitamins, phytoingredients, antioxidants) affect NAFLD pathogenesis. Furthermore, some evidence indicates disruption of metabolic homeostasis by food contaminants, some of which are risk factor candidates in NAFLD. At the molecular level, several models have been proposed for the pathogenesis of NAFLD. Most importantly, oxidative stress and mitochondrial damage have been reported to be causative in NAFLD initiation and progression. The aim of this review is to provide an overview of the contribution of nutrients and food contaminants, especially pesticides, to oxidative stress and how they may influence NAFLD pathogenesis.

Shifts in the Bacterial Community of Supragingival Plaque Associated With Metabolic-Associated Fatty Liver Disease

Metabolic-associated fatty liver disease (MAFLD), also known as the hepatic manifestation of metabolic disorders, has become one of the most common chronic liver diseases worldwide. The associations between some oral resident microbes and MAFLD have been described. However, changes to the oral microbial community in patients with MAFLD remain unknown. In this study, variations to the supragingival microbiota of MAFLD patients were identified. The microbial genetic profile of supragingival plaque samples from 24 MAFLD patients and 22 healthy participants were analyzed by 16S rDNA sequencing and bioinformatics analysis. Clinical variables, including indicators of insulin resistance, obesity, blood lipids, and hepatocellular damage, were evaluated with laboratory tests and physical examinations. The results showed that the diversity of the supragingival microbiota in MAFLD patients was significantly higher than that in healthy individuals. Weighted UniFrac principal coordinates analysis and partial least squares discriminant analysis showed that the samples from the MAFLD and control groups formed separate clusters (Adonis, P = 0.0120). There were 27 taxa with differential distributions (linear discriminant analysis, LDA>2.0) between two groups, among which Actinomyces spp. and Prevotella 2 spp. were over-represented in the MAFLD group with highest LDA score, while Neisseria spp. and Bergeyella spp. were more abundant in the control group. Co-occurrence networks of the top 50 abundant genera in the two groups suggested that the inter-genera relationships were also altered in the supragingival plaque of MAFLD patients. In addition, in genus level, as risk factors for the development of MAFLD, insulin resistance was positively correlated with the abundances of Granulicatella, Veillonella, Streptococcus, and Scardovia, while obesity was positively correlated to the abundances of Streptococcus, Oslenella, Scardovia, and Selenomonas. Metagenomic predictions based on Phylogenetic Investigation of Communities by Reconstruction of Unobserved States revealed that pathways related to sugar (mainly free sugar) metabolism were enriched in the supragingival plaque of the MAFLD group. In conclusion, as compared to healthy individuals, component and interactional dysbioses were observed in the supragingival microbiota of the MAFLD group.

Physiopathology of Lifestyle Interventions in Non-Alcoholic Fatty Liver Disease (NAFLD)

Non-alcoholic fatty liver disease (NAFLD) is a major health problem, and its prevalence has increased in recent years. Diet and exercise interventions are the first-line treatment options, with weight loss via a hypocaloric diet being the most important therapeutic target in NAFLD. However, most NAFLD patients are not able to achieve such weight loss. Therefore, the requisite is the investigation of other effective therapeutic approaches. This review summarizes research on understanding complex pathophysiology underlying dietary approaches and exercise interventions with the potential to prevent and treat NAFLD.

Donor diabetes mellitus is a risk factor for diminished outcome after liver transplantation: a nationwide retrospective cohort study

With the growing incidence of diabetes mellitus (DM), an increasing number of organ donors with DM can be expected. We sought to investigate the association between donor DM with early post‐transplant outcomes. From a national cohort of adult liver transplant recipients (1996–2016), all recipients transplanted with a liver from a DM donor (n = 69) were matched 1:2 with recipients of livers from non‐DM donors (n = 138). The primary end‐point included early post‐transplant outcome, such as the incidence of primary nonfunction (PNF), hepatic artery thrombosis (HAT), and 90‐day graft survival. Cox regression analysis was used to analyze the impact of donor DM on graft failure. PNF was observed in 5.8% of grafts from DM donors versus 2.9% of non‐DM donor grafts (P = 0.31). Recipients of grafts derived from DM donors had a higher incidence of HAT (8.7% vs. 2.2%, P = 0.03) and decreased 90‐day graft survival (88.4% [70.9–91.1] vs. 96.4% [89.6–97.8], P = 0.03) compared to recipients of grafts from non‐DM donors. The adjusted hazard ratio for donor DM on graft survival was 2.21 (1.08–4.53, P = 0.03). In conclusion, donor DM is associated with diminished outcome early after liver transplantation. The increased incidence of HAT after transplantation of livers from DM donors requires further research.

Improving Outcomes of Bariatric Surgery in Patients With Cirrhosis in the United States: A Nationwide Assessment

INTRODUCTION

With increasing burden of obesity and liver disease in the United States, a better understanding of bariatric surgery in context of cirrhosis is needed. We described trends of hospital-based outcomes of bariatric surgery among cirrhotics and determined effect of volume status and type of surgery on these outcomes.

METHODS

In this population-based study, admissions for bariatric surgery were extracted from the National Inpatient Sample using International Classification of Diseases, 9th and 10th Revision, Clinical Modification codes from 2004 to 2016 and grouped by cirrhosis status, type of bariatric surgery, and center volume. In-hospital mortality, complications, and their trends were compared between these groups using weighted counts, odds ratios [ORs], and logistic regression.

RESULTS

Among 1,679,828 admissions for bariatric surgery, 9,802 (0.58%) had cirrhosis. Cirrhosis admissions were more likely to be in white men, had higher Elixhauser Index, and higher in-hospital complications rates including death (1.81% vs 0.17%), acute kidney injury (4.5% vs 1.2%), bleeding (2.9% vs 1.1%), and operative complications (2% vs 0.6%) (P < 0.001 for all) compared to those without cirrhosis. Overtime, restrictive surgeries have grown in number (12%-71%) and complications rates have trended down in both groups. Cirrhotics undergoing bariatric surgery at low-volume centers (<50 procedures per year) and nonrestrictive surgery had a higher inpatient mortality rate (adjusted OR 4.50, 95% confidence interval 3.14-6.45, adjusted OR 4.00, 95% confidence interval 2.68-5.97, respectively).

DISCUSSION

Contemporary data indicate that among admissions for bariatric surgery, there is a shift to restrictive-type surgeries with an improvement in-hospital complications and mortality. However, patients with cirrhosis especially those at low-volume centers have significantly higher risk of worse outcomes (see Visual abstract, Supplementary Digital Content, http://links.lww.com/AJG/B648).

Mesenchymal Stem Cells Induce a Fibrolytic Phenotype By Regulating mmu-miR-6769b-5p Expression in Macrophages

Liver transplantation is the only radical treatment for decompensated cirrhosis, but its use is limited owing to a shortage of donors; hence, there is an urgent need for new treatments. Previously, we developed a liver-regeneration therapy using autologous bone marrow-derived mesenchymal stem cells (BMSCs), which is under clinical investigation. Cell-cell interactions between BMSCs and macrophages (Mφs) participate in the improvement of liver function and alleviation of liver fibrosis, although the associated mechanisms have not been elucidated. Therefore, in this study, we investigated phenotypic changes in Mφs caused by interactions with BMSCs, as well as the underlying mechanisms. Co-culturing lipopolysaccharide (LPS)-stimulated murine bone marrow-derived Mφs (BMDMs) with BMSCs substantially upregulated matrix metalloproteinase 9 (Mmp9), Mmp12, and Mmp13 expression, and downregulated tumor necrosis factor alpha (Tnfα) expression. To identify humoral factors involved in phenotypic changes occurring in Mφs, microarray analysis was performed with microRNAs (miRNAs) derived from extracellular vesicles in the supernatant of co-cultured BMSCs and LPS-stimulated BMDMs. We found that miR-6769b-5p was highly expressed and that transfecting miR-6769b-5p mimic upregulated MMP9 in LPS-stimulated BMDMs and downregulated Tnfα and interleukin-1 beta (Il-1β). MiR-6769b-5p expression in BMDMs was decreased by LPS stimulation but was increased by co-culture with BMSCs. Microarray and pathway analyses of gene expression in LPS-stimulated, miR-6769b-5p-transfected BMDMs revealed changes in the eukaryotic initiation factor 2-signaling pathway and decreased the expression of activating transcription factor 4 (Atf4). LPS-stimulated BMDMs exhibited increased MMP9 expression and decreased the expression of Tnfα and Il-1β by ATF4 knockdown. These findings indicate that upregulating miR-6769b-5p in BMDMs induced a fibrolytic phenotype, where MMP9 was highly expressed and inflammatory cytokine expression was decreased by the suppression of ATF4 expression. These findings imply that regulating miR-6769b-5p or ATF4 expression in BMDMs may be helpful for treating chronic liver disease.

A New Endemic of Concomitant Nonalcoholic Fatty Liver Disease and Chronic Hepatitis B

Hepatitis B virus (HBV) infection remains a global public problem despite the availability of an effective vaccine. In the past decades, nonalcoholic fatty liver disease (NAFLD) has surpassed HBV as the most common cause of chronic liver disease worldwide. The prevalence of concomitant chronic hepatitis B (CHB) and NAFLD thus reaches endemic proportions in geographic regions where both conditions are common. Patients with CHB and NAFLD are at increased risk of liver disease progression to cirrhosis and hepatocellular carcinoma. Due to the complexity of the pathogenesis, accurate diagnosis of NAFLD in CHB patients can be challenging. Liver biopsy is considered the gold standard for diagnosing and determining disease severity, but it is an invasive procedure with potential complications. There is a growing body of literature on the application of novel noninvasive serum biomarkers and advanced radiological modalities to diagnose and evaluate NAFLD, but most have not been adequately validated, especially for patients with CHB. Currently, there is no approved therapy for NAFLD, although many new agents are in different phases of development. This review provides a summary of the epidemiology, clinical features, diagnosis, and management of the NAFLD and highlights the unmet needs in the areas of CHB and NAFLD coexistence.

Non-alcoholic fatty liver disease (NAFLD) as a neglected metabolic companion of psychiatric disorders: common pathways and future approaches

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) is characterized by hepatic steatosis in over 5% of the parenchyma in the absence of excessive alcohol consumption. It is more prevalent in patients with diverse mental disorders, being part of the comorbidity driving loss of life expectancy and quality of life, yet remains a neglected entity. NAFLD can progress to non-alcoholic steatohepatitis (NASH) and increases the risk for cirrhosis and hepatic carcinoma. Both NAFLD and mental disorders share pathophysiological pathways, and also present a complex, bidirectional relationship with the metabolic syndrome (MetS) and related cardiometabolic diseases.

MAIN TEXT

This review compares the demographic data on NAFLD and NASH among the global population and the psychiatric population, finding differences that suggest a higher incidence of this disease among the latter. It also analyzes the link between NAFLD and psychiatric disorders, looking into common pathophysiological pathways, such as metabolic, genetic, and lifestyle factors. Finally, possible treatments, tailored approaches, and future research directions are suggested.

CONCLUSION

NAFLD is part of a complex system of mental and non-communicable somatic disorders with a common pathogenesis, based on shared lifestyle and environmental risks, mediated by dysregulation of inflammation, oxidative stress pathways, and mitochondrial function. The recognition of the prevalent comorbidity between NAFLD and mental disorders is required to inform clinical practice and develop novel interventions to prevent and treat these complex and interacting disorders.

The diagnostic conundrum in non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) has become the most common liver alteration worldwide. It encompasses a spectrum of disorders that range from simple steatosis to a progressive form, defined non-alcoholic steatohepatitis (NASH), that can lead to advanced fibrosis and eventually cirrhosis and hepatocellular carcinoma. On liver histology, NASH is characterized by the concomitant presence of significant fat accumulation and inflammatory reaction with hepatocellular injury. Until now, liver biopsy is still required to differentiate simple steatosis from NASH and evaluate the degree of liver fibrosis. Unfortunately, this technique has well-known limitations, including invasiveness and expensiveness. Moreover, it may be biased by sampling error and intra- or inter-observed variability. Furthermore, due to the increasing prevalence of NAFLD worldwide, to program a systematic screening with liver biopsy is not imaginable. In recent years, different techniques were developed and validated with the aim of non-invasively identifying NASH and assess liver fibrosis degrees. The non-invasive tests range from simple blood-tests analyses to composite scores and complex imaging techniques. Nevertheless, even if they could represent cost-effective strategies for diagnosing NASH, advanced fibrosis and cirrhosis, their accuracy and consequent usefulness are to be discussed. With this aim, in this review the authors summarize the current state of non-invasive assessment of NAFLD. In particular, in addition to the well-established tests, the authors describe the future perspectives in this field, reporting the latest tests based on OMICS, gut-miocrobioma and micro-RNAs. Finally, the authors provide an accurate assessment of how these non-invasive tools perform in clinical practice depending on the clinical context, with the aim of giving the clinicians a useful tool to try to resolve the diagnostic conundrum of NAFLD.

Effects of body composition on the procoagulant imbalance in obese patients

Obesity is associated with increased thrombotic risk and hypercoagulability whose main driver is an excess of coagulation factor VIII relative to protein C. The aims of this study were to evaluate the association between factor VIII, protein C, factor VIII-to-protein C ratio and bioimpedance parameters of body composition in obese patients. We analysed blood from 69 obese patients and 23 non-obese healthy controls. Plasma levels of factor VIII, protein C, and factor VIII-to-protein C ratio were correlated with total fat, visceral fat, and muscle mass. Compared to controls, obese patients had significantly higher factor VIII (110.5% vs 78.05%, p < 0.001), protein C (120.99% versus 110.51%, p = 0.014), and factor VIII-to-protein C ratio (0.93 versus 0.73, p = 0.002). In obese patients, factor VIII correlated with body-mass index, body fat percentage, muscle mass percentage, and fat-to-muscle ratio, whereas protein C had significant relationships with body fat percentage, muscle mass percentage and fat-to-muscle ratio, but not with body-mass index. Factor VIII-to-protein C ratio > 1 was significantly associated with body-mass index (odds ratio 1.08, 95% CI 1.02 to 1.14) and fat-to-muscle ratio (odds ratio 2.47, 95% CI 1.10 to 5.55). Factor VIII-to-protein C ratio strongly correlated with D-dimer levels in the overall population (rho 0.44, p < 0.001) and obese patients (rho 0.41, p < 0.001). In obese patients, bioimpedance measures of body fat and muscle mass percentage were associated with factor VIII and protein C. Factor VIII-to-protein C ratio was strongly associated with fat-to-muscle ratio and only modestly related to BMI.

Non-alcoholic fatty liver disease (NAFLD) and risk of hospitalization for Covid-19

Background

Covid-19 disease causes significant morbidity and mortality through increase inflammation and thrombosis. Non-alcoholic fatty liver disease and non-alcoholic steatohepatitis are states of chronic inflammation and indicate advanced metabolic disease. We sought to understand the risk of hospitalization for Covid-19 associated with NAFLD/NASH.

Methods

Retrospective analysis of electronic medical record data of 6,700 adults with a positive SARS-CoV-2 PCR from March 1, 2020 to Aug 25, 2020. Logistic regression and competing risk were used to assess odds of being hospitalized. Additional adjustment was added to assess risk of hospitalization among patients with a prescription for metformin use within the 3 months prior to the SARS-CoV-2 PCR result, history of home glucagon-like-peptide 1 receptor agonist (GLP-1 RA) use, and history of metabolic and bariatric surgery (MBS). Interactions were assessed by gender and race.

Results

A history of NAFLD/NASH was associated with increased odds of admission for Covid-19: logistic regression OR 2.04 (1.55, 2.96, p<0.01), competing risks OR 1.43 (1.09-1.88, p<0.01); and each additional year of having NAFLD/NASH was associated with a significant increased risk of being hospitalized for Covid-19, OR 1.86 (1.43-2.42, p<0.01). After controlling for NAFLD/NASH, persons with obesity had decreased odds of hospitalization for Covid-19, OR 0.41 (0.34-0.49, p<0.01). NAFLD/NASH increased risk of hospitalization in men and women, and in all racial/ethnic subgroups. Mediation treatments for metabolic syndrome were associated with non-significant reduced risk of admission: OR 0.42 (0.18-1.01, p=0.05) for home metformin use and OR 0.40 (0.14-1.17, p=0.10) for home GLP-1RA use. MBS was associated with a significant decreased risk of admission: OR 0.22 (0.05-0.98, p<0.05).

Conclusions

NAFLD/NASH is a significant risk factor for hospitalization for Covid-19, and appears to account for risk attributed to obesity. Treatments for metabolic disease mitigated risks from NAFLD/NASH. More research is needed to confirm risk associated with visceral adiposity, and patients should be screened for and informed of treatments for metabolic syndrome.

High carbohydrate and noodle/meat-rich dietary patterns interact with the minor haplotype in the 22q13 loci to increase its association with non-alcoholic fatty liver disease risk in Koreans

Non-alcoholic fatty liver(NAFLD) is prevalent in Asians despite the low obesity rate. We hypothesized that the haplotype of genetic variants in the 22q13 loci has a strong association with non-alcoholic fatty liver disease (NAFLD) that can be identified by genome-wide association study and that lifestyles may interact with the haplotype. We tested the hypothesis in middle-aged and elderly adults in a large city hospital-based cohort from the KoGES study. Men and women diagnosed with fatty liver, but who respectively consumed over 40 and 30 g ethanol per day were excluded. The haplotype of the selected SNPs from the 22q13 loci that influences NAFLD risk was generated. Among the 27374 participants, 1486 (5.4%) were diagnosed with NAFLD. LARGE_rs240072, RBFOX2_rs11089778, TRIOBP_rs12628603, PNPLA3_rs738409, and PARVB_rs2073080 in the 22q13 loci were included in the haplotype. Participants with the minor haplotype had 1.8, 2.3, and 1.8 times higher in the risk for NAFLD and serum AST and ALT activities, respectively, than those with the major haplotype. BMI, waist circumferences, serum glucose concentrations, and blood pressure interacted with the haplotype for NAFLD risk. We also found that a high carbohydrate intake and a dietary pattern characterized by high noodle and meat consumption significantly interacted with the minor haplotype to increase the risk of NAFLD. We hypothesized that the high incidence of NAFLD among Koreans, despite a relatively low incidence of obesity, might be due to genetic factors and perhaps their interactions with dietary patterns. The hypothesis was accepted since this study confirmed that participants with the minor allele of the haplotype in the 22q13 loci had a higher NAFLD risk that was exacerbated by high intakes of carbohydrates and a dietary pattern characterized by high noodle and meat consumption.

Mechanisms of nonalcoholic fatty liver disease and implications for surgery

Background

Nonalcoholic fatty liver disease (NAFLD) has become the most common form of chronic liver disease in both adults and children worldwide. Understanding the pathogenic mechanisms behind NAFLD provides the basis for identifying risk factors, such as metabolic syndrome, pancreatoduodenectomy, and host genetics, that lead to the onset and progression of the disease. The progression from steatosis to more severe forms, such as steatohepatitis, fibrosis, and cirrhosis, leads to an increased number of liver and non-liver complications.

Purpose

NAFLD-associated end-stage liver disease (ESLD) and hepatocellular carcinoma (HCC) often require surgery as the only curative treatment. In particular, the presence of NAFLD together with the coexisting metabolic comorbidities that usually occur in these patients requires careful preoperative diagnosis and peri-/postoperative management. Bariatric surgery, liver resection, and liver transplantation (LT) have shown favorable results for weight loss, HCC, and ESLD in patients with NAFLD. The LT demand and the increasing spread of NAFLD in the donor pool reinforce the already existing lack of donor organs.

Conclusion

In this review, we will discuss the diverse mechanisms underlying NAFLD, its implications for surgery, and the challenges for patient management.

Constant Light Exposure Alters Gut Microbiota and Promotes the Progression of Steatohepatitis in High Fat Diet Rats

Background

Non-alcoholic fatty liver disease (NAFLD) poses a significant health concern worldwide. With the progression of urbanization, light pollution may be a previously unrecognized risk factor for NAFLD/NASH development. However, the role of light pollution on NAFLD is insufficiently understood, and the underlying mechanism remains unclear. Interestingly, recent studies indicate the gut microbiota affects NAFLD/NASH development. Therefore, the present study explored effects of constant light exposure on NAFLD and its related microbiotic mechanisms.

Materials and Methods

Twenty-eight SD male rats were divided into four groups (n = 7 each): rats fed a normal chow diet, and exposed to standard light-dark cycle (ND-LD); rats fed a normal chow diet, and exposed to constant light (ND-LL); rats fed a high fat diet, and exposed to standard light-dark cycle (HFD-LD); and rats on a high fat diet, and exposed to constant light (HFD-LL). Body weight, hepatic pathophysiology, gut microbiota, and short/medium chain fatty acids in colon contents, serum lipopolysaccharide (LPS), and liver LPS-binding protein (LBP) mRNA expression were documented post intervention and compared among groups.

Result

In normal chow fed groups, rats exposed to constant light displayed glucose abnormalities and dyslipidemia. In HFD-fed rats, constant light exposure exacerbated glucose abnormalities, insulin resistance, inflammation, and liver steatohepatitis. Constant light exposure altered composition of gut microbiota in both normal chow and HFD fed rats. Compared with HFD-LD group, HFD-LL rats displayed less Butyricicoccus, Clostridium, and Turicibacter, butyrate levels in colon contents, decreased colon expression of occludin-1 and zonula occluden−1 (ZO-1), and increased serum LPS and liver LBP mRNA expression.

Conclusion

Constant light exposure impacts gut microbiota and its metabolic products, impairs gut barrier function and gut-liver axis, promotes NAFLD/NASH progression in HFD rats.

History of Nonalcoholic Fatty Liver Disease

Based on the assumption that characterizing the history of a disease will help in improving practice while offering a clue to research, this article aims at reviewing the history of nonalcoholic fatty liver disease (NAFLD) in adults and children. To this end, we address the history of NAFLD histopathology, which begins in 1980 with Ludwig's seminal studies, although previous studies date back to the 19th century. Moreover, the principal milestones in the definition of genetic NAFLD are summarized. Next, a specific account is given of the evolution, over time, of our understanding of the association of NAFLD with metabolic syndrome, spanning from the outdated concept of "NAFLD as a manifestation of the Metabolic Syndrome", to the more appropriate consideration that NAFLD has, with metabolic syndrome, a mutual and bi-directional relationship. In addition, we also report on the evolution from first intuitions to more recent studies, supporting NAFLD as an independent risk factor for cardiovascular disease. This association probably has deep roots, going back to ancient Middle Eastern cultures, wherein the liver had a significance similar to that which the heart holds in contemporary society. Conversely, the notions that NAFLD is a forerunner of hepatocellular carcinoma and extra-hepatic cancers is definitely more modern. Interestingly, guidelines issued by hepatological societies have lagged behind the identification of NAFLD by decades. A comparative analysis of these documents defines both shared attitudes (e.g., ultrasonography and lifestyle changes as the first approaches) and diverging key points (e.g., the threshold of alcohol consumption, screening methods, optimal non-invasive assessment of liver fibrosis and drug treatment options). Finally, the principal historical steps in the general, cellular and molecular pathogenesis of NAFLD are reviewed. We conclude that an in-depth understanding of the history of the disease permits us to better comprehend the disease itself, as well as to anticipate the lines of development of future NAFLD research.

Secreted phosphoglucose isomerase is a novel biomarker of nonalcoholic fatty liver in mice and humans

The current gold standard for diagnosis of nonalcoholic fatty liver disease (NAFLD) and nonalcoholic steatohepatitis (NASH) is through a liver biopsy, and there is an urgent need to develop non-invasive methods for early detection. We previously demonstrated metabolic remodeling in the mouse fatty liver, which is marked by increased hepatic expression and activities of phosphoglucose isomerase (PGI) and several other glycolytic enzymes. Since PGI is actively transported out of the cell, acting as a multifunctional cytokine referred to as autocrine motility factor (AMF), we explored the possibility that PGI secreted from the fatty liver may be targeted for early detection of the silent disease. We report here that mice with NASH exhibited significantly elevated serum PGI enzyme activities compared to normal control (P < 0.005). We further confirmed the finding using serum/plasma samples (n = 73) collected from a cohort of NASH patients who were diagnosed according to Kleiner’s criteria, showing a normal mean PGI of 19.5 ± 8.8 IU/L and patient mean PGI of 105.6 ± 79.9 IU/L (P < 0.005). In addition, elevated blood PGI in NASH patients coincided with increased blood L-lactate. Cell culture experiments were then conducted to delineate the PGI-lactate axis, which revealed that treatment of HepG2 cells with recombinant PGI protein stimulated glycolysis and lactate output, suggesting that the disease-induced PGI likely contributed to the increased lactate in NASH patients. Taken together, the preclinical and clinical data validate secreted PGI as a useful biomarker of the fatty liver that can be easily screened at the point of care.

Pdgfrα-Cre mediated knockout of the aryl hydrocarbon receptor protects mice from high-fat diet induced obesity and hepatic steatosis

Aryl hydrocarbon receptor (AHR) agonists such as dioxin have been associated with obesity and the development of diabetes. Whole-body Ahr knockout mice on high-fat diet (HFD) have been shown to resist obesity and hepatic steatosis. Tissue-specific knockout of Ahr in mature adipocytes via adiponectin-Cre exacerbates obesity while knockout in liver increases steatosis without having significant effects on obesity. Our previous studies demonstrated that treatment of subcutaneous preadipocytes with exogenous or endogenous AHR agonists disrupts maturation into functional adipocytes in vitro. Here, we used platelet-derived growth factor receptor alpha (Pdgfrα)-Cre mice, a Cre model previously established to knock out genes in preadipocyte lineages and other cell types, but not liver cells, to further define AHR's role in obesity. We demonstrate that Pdgfrα-Cre Ahr-floxed (Ahrfl/fl) knockout mice are protected from HFD-induced obesity compared to non-knockout Ahrfl/fl mice (control mice). The Pdgfrα-Cre Ahrfl/fl knockout mice were also protected from increased adiposity, enlargement of adipocyte size, and liver steatosis while on the HFD compared to control mice. On a regular control diet, knockout and non-knockout mice showed no differences in weight gain, indicating the protective phenotype arises only when animals are challenged by a HFD. At the cellular level, cultured cells from brown adipose tissue (BAT) of Pdgfrα-Cre Ahrfl/fl mice were more responsive than cells from controls to transcriptional activation of the thermogenic uncoupling protein 1 (Ucp1) gene by norepinephrine, suggesting an ability to burn more energy under certain conditions. Collectively, our results show that knockout of Ahr mediated by Pdgfrα-Cre is protective against diet-induced obesity and suggest a mechanism by which enhanced UCP1 activity within BAT might confer these effects.

Capparis spinosa improves the high fat diet-induced non-alcoholic steatohepatitis in rats: the possible role of FGF21

OBJECTIVES

This study focused on the beneficial effects of Capparis spinosa (CS) treatment on the steatohepatitis induced by the administration of a high-fat emulsion in rats. Changes of hepatic expression and secretion of fibroblast growth factor 21 (FGF21) were also evaluated as a probable mechanism of the CS effects on fatty liver. Male Wistar rats were allocated in different groups to receive a normal diet (NC group), a high-fat diet (HF group), or the high-fat emulsion plus CS extract at a dose of 20 mg/kg (HF+CS group). Body and liver weight, liver index, serum biochemical factors, histopathological examination, and serum level and hepatic gene expression of FGF21 were determined.

RESULTS

CS administration markedly reduced liver weight and index, serum levels of glucose, lipids, alanine aminotransferase (ALT), and aspartate aminotransferase (AST) and improved histological features of nonalcoholic steatohepatitis (NASH) which were induced by HF feeding in this model. CS supplementation also restored the decreased hepatic and serum FGF21 levels in the fatty liver rats. We propose that the FGF21 up-regulation may partly account for the favorable effects of CS in this steatohepatitis model.

[New pharmacological treatment options for nonalcoholic fatty liver disease]

The prevalence of nonalcoholic fatty liver disease (NAFLD) continues to increase worldwide, presently affecting 25% of the adult population, and is associated with an elevated risk of total and liver-specific mortality. NAFLD is a chronic disease and results from a combination of genetic, environmental and predominantly lifestyle-related causes. Therefore, NAFLD, similarly to cardiovascular disease, type 2 diabetes and many different types of cancer, can be considered a noncommunicable disease. Consequently, lifestyle intervention, particularly if associated with a large amount of weight loss, is considered highly effective and safe to treat NAFLD. For patients with advanced-stage NAFLD or that cannot lose weight, metabolically-based pharmacotherapy is effective to improve liver histology and cardiometabolic risk profile. If a moderate or advanced stage of liver fibrosis is present, additional antifibrotic therapy is necessary to halt the progression of the disease.

Association between periodontal disease, tooth loss and liver diseases risk

AIM

The purpose of this study is to assess the associations between periodontal disease, tooth loss and liver diseases.

MATERIALS AND METHODS

PubMed and Embase databases were utilized to search eligible studies. Odds ratio (OR) with 95% confidence interval (CI) was used as effect size to assess the associations between periodontal disease, tooth loss and liver diseases risk.

RESULTS

Our results indicated positive associations between periodontal disease and non-alcoholic fatty liver disease (NAFLD) (OR = 1.19, 95% CI = 1.06-1.33), liver cirrhosis (OR = 2.28, 95% CI = 1.50-3.48) and elevated transaminase level risk (OR = 1.08, 95% CI = 1.02-1.15). Moreover, tooth loss could increase NAFLD (OR = 1.33, 95% CI = 1.12- 1.56) and liver cancer risk (OR = 1.34, 95% CI = 1.04-1.74), and every five increment in tooth loss was associated with 5% increased liver cancer risk (OR = 1.05, 95% CI = 1.01 - 1.10) with a linear relationship. In addition, tooth loss had a positive tendency towards liver cirrhosis risk (OR = 2.03, 95% CI = 0.85-4.85) although there was no statistical significance.

CONCLUSION

Periodontal disease and tooth loss are positively associated with liver diseases including NAFLD, elevated transaminase level, liver cirrhosis and liver cancer.

Hyperthermia-induced changes in liver physiology and metabolism: a rationale for hyperthermic machine perfusion

Liver transplantation is the standard treatment for end-stage liver disease. However, due to the ongoing disparity between supply and demand for optimal donor organs, there is increasing usage of extended criteria donor organs, including steatotic liver grafts. To mitigate the increased risks associated with extended criteria donor livers, ex situ oxygenated machine perfusion (MP) has received increasing attention in recent years as an emerging platform for dynamic preservation, reconditioning, and viability assessment to increase organ utilization. MP can be applied at different temperatures. During hypothermic MP (4-12°C), liver metabolism is reduced, while oxygenation restores the intracellular levels of adenosine triphosphate. The liver is quickly "recharged" to support metabolism when at normothermia (35-37°C) and to ameliorate the detrimental effects of ischemia/reperfusion injury during transplantation. During normothermia, MP can be applied to assess hepatocellular and cholangiocellular viability. MP at hyperthermic (>38°C) temperatures (HyMP), however, remains relatively understudied. The liver is an important component in the regulation of core body temperature and, as such, displays significant physiological and metabolic changes in response to different temperatures. Hyperthermia may promote vasodilation, increase aerobic metabolism and induce production of protective molecules such as heat shock proteins. Therefore, HyMP could provide an attractive reconditioning strategy for steatotic livers. In this review, we describe current literature on the physiological and metabolic effects of the liver at hyperthermia for human, rodents, and pigs and provide a rationale for using therapeutic HyMP during isolated liver machine perfusion to recondition extended criteria donor livers, including steatotic livers, before transplantation.

Crosstalk Between Liver Macrophages and Surrounding Cells in Nonalcoholic Steatohepatitis

Nonalcoholic steatohepatitis (NASH), the advanced stage of nonalcoholic fatty liver disease (NAFLD), is emerging as a leading cause of progressive liver fibrosis and end-stage liver disease. Liver macrophages, mainly composed of Kupffer cells (KCs) and monocyte-derived macrophages (MoMFs), play a vital role in NASH progression and regression. Recent advances suggest that cell–cell communication is a fundamental feature of hepatic microenvironment. The reprogramming of cell–cell signaling between macrophages and surrounding cells contributes to the pathogenesis of NASH. In this review, we summarize the current knowledge of NASH regarding the composition of liver macrophages and their communication with surrounding cells, which are composed of hepatocytes, hepatic stellate cells (HSCs), liver sinusoidal endothelial cells (LSECs) and other immune cells. We also discuss the potential therapeutic strategies based on the level of macrophages.

Heightened Plasma Levels of Transforming Growth Factor Beta (TGF-β) and Increased Degree of Systemic Biochemical Perturbation Characterizes Hepatic Steatosis in Overweight Pediatric Patients: A Cross-Sectional Study

Nonalcoholic Fatty Liver Disease (NAFLD) is a common cause of chronic liver disease in childhood and strongly associated with obesity. Routine biochemical non-invasive tests remain with low accuracy for diagnosis of NAFLD. We performed a cross-sectional study to examine potential associations between anthropometric and biochemical parameters, specially TGF-β, a prognosis marker for hepatic steatosis (HS). Between May and October 2019, seventy-two overweight adolescents were enrolled, of which 36 had hepatic steatosis. Hepatic, lipidic and glycemic profiles, and levels of vitamin D, ferritin and TGF-β were analyzed. Hierarchical cluster and a discriminant model using canonical correlations were employed to depict the overall expression profile of biochemical markers and the biochemical degree of perturbation. Median values of alanine aminotransferase (ALT), gamma glutamyl transpeptidase (GGT), and TGF-β were higher in the adolescents with HS. Values of body mass index (BMI)/age and ALT, but not of TGF-β, were gradually increased proportionally to augmentation of steatosis severity. In a multivariate analysis, TGF-β plasma concentrations were associated with occurrence of hepatic steatosis independent of other covariates. Discriminant analysis confirmed that TGF-β concentrations can identify HS cases. Our data reveal that HS patients exhibit a distinct biosignature of biochemical parameters and imply TGF-β as an important biomarker to evaluate risk of steatosis development.

A Candidate Drug for Nonalcoholic Fatty Liver Disease: A Review of Pharmacological Activities of Polygoni Multiflori Radix

Nonalcoholic fatty liver disease, a type of metabolic syndrome, continues to rise globally. Currently, there is no approved drug for its treatment. Improving lifestyle and exercise can alleviate symptoms, but patients' compliance is poor. More and more studies have shown the potential of Polygoni Multiflori Radix (PMR) in the treatment of NAFLD and metabolic syndrome. Therefore, this paper reviews the pharmacological effects of PMR and its main chemical components (tetrahydroxystilbene glucoside, emodin, and resveratrol) on NAFLD. PMR can inhibit the production of fatty acids and promote the decomposition of triglycerides, reduce inflammation, and inhibit the occurrence of liver fibrosis. At the same time, it maintains an oxidation equilibrium status in the body, to achieve the therapeutic purpose of NAFLD and metabolic syndrome. Although more standardized studies and clinical trials are needed to confirm its efficacy, PMR may be a potential drug for the treatment of NAFLD and its complications. However, the occurrence of adverse reactions of PMR has affected its extensive clinical application. Therefore, it is necessary to further study its toxicity mechanism, enhance efficacy and control toxicity, and even reduce toxicity, which will contribute to the safe clinical use of PMR.

NAFLD as a continuum: from obesity to metabolic syndrome and diabetes

BACKGROUND

The prevalence of non-alcoholic fatty liver disease (NAFLD) has been increasing rapidly. It is nowadays recognized as the most frequent liver disease, affecting a quarter of global population and regularly coexisting with metabolic disorders such as type 2 diabetes, hypertension, obesity, and cardiovascular disease. In a more simplistic view, NAFLD could be defined as an increase in liver fat content, in the absence of secondary cause of steatosis. In fact, the clinical onset of the disease is a much more complex process, closely related to insulin resistance, limited expandability and dysfunctionality of adipose tissue. A fatty liver is a main driver for a new recognized liver-pancreatic α-cell axis and increased glucagon, contributing to diabetes pathophysiology.

MAIN TEXT

This review will focus on the clinical and pathophysiological connections between NAFLD, insulin resistance and type 2 diabetes. We reviewed non-invasive methods and several scoring systems for estimative of steatosis and fibrosis, proposing a multistep process for NAFLD evaluation. We will also discuss treatment options with a more comprehensive view, focusing on the current available therapies for obesity and/or type 2 diabetes that impact each stage of NAFLD.

CONCLUSION

The proper understanding of NAFLD spectrum-as a continuum from obesity to metabolic syndrome and diabetes-may contribute to the early identification and for establishment of targeted treatment.