Therapeutic Approaches to Nonalcoholic Fatty Liver Disease: Exercise Intervention and Related Mechanisms

Control of inflammatory lung injury and repair by metabolic signaling in endothelial cells

PURPOSE OF REVIEW

Sepsis-induced inflammatory lung injury includes acute lung injury (ALI) and acute respiratory distress syndrome (ARDS). There are currently no effective treatments for ALI/ARDS, but clinical outcomes could be improved by inhibiting lung injury and/or promoting post-sepsis vascular repair. In this review, we describe studies of endothelial cell metabolic pathways in sepsis-induced ALI/ARDS and vascular repair and identify areas of research that deserve attention in future studies. We also describe studies of metabolic interventions that aim to inhibit ALI/ARDS and/or promote post-sepsis vascular repair, including those that target endothelial cell metabolites, endothelial cell metabolic signaling pathways, and endothelial cell metabolism.

RECENT FINDINGS

Endothelial cells are integral to both the injury and repair phases of ALI/ARDS. During the injury phase of ALI/ARDS, lung endothelial cell survival decreases, and lung endothelial cell-to-endothelial cell (EC-EC) junctions are weakened. During the repair phase after sepsis-induced lung injury, lung endothelial cell proliferation and lung EC-EC junction reannealing occur. These crucial aspects of ALI/ARDS and post-sepsis vascular repair, that is, endothelial cell viability, growth, and junction integrity, are controlled by a myriad of metabolites and metabolic signaling pathways in endothelial cells.

SUMMARY

Metabolic signaling pathways in endothelial cells represent a novel class of putative targets for the prevention and treatment of sepsis-induced inflammatory lung injury. Therapies that target metabolic signaling in endothelial cells are currently being explored as potential treatments for sepsis-induced inflammatory lung injury.

Exerkines: Potential regulators of ferroptosis

Ferroptosis is a programmed cell death, and its mechanism involves multiple metabolic pathways, such as iron and lipid metabolism, and redox homeostasis. Exerkines are important mediators that optimize cellular homeostasis and maintain physiological health during exercise stimulation. This article comprehensively examines the mechanisms and regulatory networks for governing ferroptosis and summarizes the impact of exercise and exerkines on ferroptosis under varying load intensities and disease contexts. Notably, despite its significant efficacy and minimal side effects, the therapeutic and prognostic potential of exercise in ferroptosis-related diseases remains largely unexplored. This article, by summarizing recent progresses in the regulation of exerkines-mediated ferroptosis, could further uncover the preventive or alleviative mechanisms of some diseases upon exercise interventions, which will be beneficial to design exercise interventional strategies for alleviating disease progression through the regulation of ferroptosis.

Dietary Interventions and Physical Activity as Crucial Factors in the Prevention and Treatment of Metabolic Dysfunction-Associated Steatotic Liver Disease

Metabolic dysfunction-associated steatotic liver disease (MASLD) is the most common chronic liver disease worldwide and affects nearly 30% of the adult population and 10% of the pediatric population. It is estimated that this number will double by 2030. MASLD is one of the leading causes of hepatocellular carcinoma, cirrhosis, and liver transplantation, as well as a significant risk factor for cardiovascular disease and mortality. Due to the ever-increasing number of patients, the long-term asymptomatic course of the disease, serious complications, and lack of preventive programs, as well as insufficient awareness of the disease among patients and doctors themselves, MASLD is a growing interdisciplinary problem and a real challenge for modern medicine. The main cause of MASLD is an inappropriate lifestyle-inadequate nutrition and insufficient physical activity, which lead to various components of metabolic syndrome. Lifestyle changes-appropriate diet, weight reduction, and systematic physical activity-are also the basis for the prevention and treatment of MASLD. Hence, in recent years, so much importance has been attached to lifestyle medicine, to non-pharmacological treatment as prevention of lifestyle diseases. The narrative review presents possible therapeutic options for non-pharmacological management in the prevention and treatment of MASLD. The best documented and available diets used in MASLD were discussed, focusing on the benefits and drawbacks of the Mediterranean, high-protein, ketogenic, and intermittent fasting diets. In addition, the most recent recommendations regarding physical activity are summarized.

Exercise training ameliorates carbon tetrachloride-induced liver fibrosis and anxiety-like behaviors

Chronic liver diseases and cirrhosis are associated with mood disorders. Regular exercise has various beneficial effects on multiple organs, including the liver and brain. However, the therapeutic effect of exercise on liver fibrosis concomitant with anxiety has not been evaluated. In this study, the effects of exercise training on liver fibrosis-related anxiety-like behaviors were evaluated. Male C57/BL6 mice were divided into four groups: vehicle-sedentary, vehicle-exercise, carbon tetrachloride (CCl4)-sedentary, and CCl4-exercise. Liver fibrosis was induced by CCl4 administration for 8 wk, exercise was applied in the form of voluntary wheel running. After an intervention, anxiety-like behavior was assessed using the elevated plus maze. CCl4 increased liver and serum fibrotic markers, as measured by blood analysis, histochemistry, and qRT-PCR, and these changes were attenuated by exercise training. CCl4 induced anxiety-like behavior, and the anxiolytic effects of exercise occurred in both healthy and liver-fibrotic mice. In the hippocampus, CCl4-induced changes in neuronal nitric oxide synthase (nNOS) were reversed by exercise, and exercise enhanced brain-derived neurotrophic factor (BDNF) induction, even in a state of severe liver fibrosis. These results suggested that hepatic fibrosis-related anxiety-like behaviors may be induced by excess hippocampal nNOS, and the beneficial effects of exercise could be mediated by increases in BDNF and reductions in nNOS. The percentage of fibrotic area was negatively correlated with antianxiety behavior and positively associated with hippocampal nNOS protein levels. Liver fibrosis-related anxiety-like behaviors could be alleviated through the regulation of hippocampal BDNF and nNOS via exercise training. These results support the therapeutic value of exercise by targeting the mechanisms underlying liver fibrosis and associated anxiety.NEW & NOTEWORTHY This study explores how exercise affects liver fibrosis-related anxiety in mice. Researchers found that regular exercise reversed carbon tetrachloride (CCl4)-induced liver fibrosis and reduced anxiety, even in mice with liver fibrosis. Exercise increased brain-derived neurotrophic factor (BDNF) and decreased neuronal nitric oxide synthase (nNOS) in the hippocampus. These findings suggest that exercise has therapeutic potential for treating anxiety associated with chronic liver disease by modulating specific brain factors.

Rate and Associated Factors of Fatigue in Chinese Patients with Non-Alcoholic Fatty Liver Disease: A Cross-Sectional Survey

Purpose

Fatigue was a common symptom of non-alcoholic fatty liver disease (NAFLD), which seriously affected patients' quality of life. The aim of this study was to detect fatigue rate and to evaluate factors associated with fatigue in NAFLD patients.

Patients and Methods

A cross-sectional study was carried out from the Huadong Sanatorium between April 2022 and May 2023, and 133 NAFLD patients were included in this study. They completed Fatigue Severity Scale to assess fatigue, the Hospital Anxiety and Depression Scale to estimate psychological status, and the Pittsburgh Sleep Quality Index for sleep quality. Data were analyzed by independent samples t-tests, χ2 tests and logistic regression models.

Results

We found that 51.1% of NAFLD patients had fatigue. Exercise, anxiety, depression, subjective sleep quality, sleep latency, sleep duration, habitual sleep efficiency, sleep disorders, daytime dysfunction and overall sleep quality were related to fatigue among NAFLD patients. Moreover, logistic regression models indicated anxiety, habitual sleep efficiency and sleep disorders as important predictors of fatigue.

Conclusion

This was the first time to explore demographic, clinical, psychological and sleeping correlated factors for fatigue in Chinese NAFLD patients. Our study showed that more than half of NAFLD patients had fatigue, and anxiety, habitual sleep efficiency and sleep disorders were significantly associated with fatigue in NAFLD. The findings indicated that it was very necessary to pay more attention to fatigue of NAFLD patients, especially those with negative emotions and poor sleep quality by favorable intervention to relieve fatigue symptoms, so as to improve quality of life.

Beneficial Effects of High-Intensity Interval Training and Dietary Changes Intervention on Hepatic Fat Accumulation in HFD-Induced Obese Rats

Lifestyle intervention encompassing nutrition and physical activity are effective strategies to prevent progressive lipid deposition in the liver. This study aimed to explore the effect of dietary change, and/or high-intensity interval training (HIIT) on hepatic lipid accumulation in high fat diet (HFD)-induced obese rats. We divided lean rats into lean control (LC) or HIIT groups (LH), and obese rats into obese normal chow diet (ND) control (ONC) or HIIT groups (ONH) and obese HFD control (OHC) or HIIT groups (OHH). We found that dietary or HIIT intervention significantly decreased body weight and the risk of dyslipidemia, prevented hepatic lipid accumulation. HIIT significantly improved mitochondrial fatty acid oxidation through upregulating mitochondrial enzyme activities, mitochondrial function and AMPK/PPARalpha/CPT1alpha pathway, as well as inhibiting hepatic de novo lipogenesis in obese HFD rats. These findings indicate that dietary alone or HIIT intervention powerfully improve intrahepatic storage of fat in diet induced obese rats. Keywords: Obesity, Exercise, Diet, Mitochondrial function, Lipid deposition.

Effects of nonalcoholic fatty liver disease on sarcopenia: evidence from genetic methods

With the aging of the population, sarcopenia has become more common. Studies have shown a broad association between liver disease and sarcopenia. However, this link remains unclear. Our study explored the link between NAFLD and sarcopenia and predicting the pathogenesis. To begin, we investigated the causal relationship and genetic correlation between them using MR and LDSC. Second, each GWAS was annotated by MAGMA. The annotated genes were analyzed for pleiotropy using the PLACO approach. Finally, functional analysis was conducted on the identified pleiotropic genes. We observed a significant genetic correlation between NAFLD and sarcopenia. Subsequently, we conducted gene-level pleiotropy analysis using PLACO and identified a total of 153 genes with pleiotropic effects. Functional analysis revealed enrichment of these genes in various tissues, including pancreas, liver, heart, blood, brain, and muscle, with involvement in cellular regulation, intracellular function, and antigen response. Moreover, our MR analysis provided evidence of a causal relationship between NAFLD and sarcopenia. Our study has discovered the genetic and causal relationships between NAFLD and sarcopenia, providing further insights into their pathophysiological mechanisms. The identification of pleiotropic genes also offers potential targets for future drug therapies aimed at controlling or treating NAFLD and sarcopenia.

Diet and Exercise Exert a Differential Effect on Glucose Metabolism Markers According to the Degree of NAFLD Severity

BACKGROUND

Non-Alcoholic Fatty Liver Disease (NAFLD) and Type 2 Diabetes (T2D) are highly prevalent diseases worldwide. Insulin Resistance (IR) is the common denominator of the two conditions even if the precise timing of onset is unknown. Lifestyle change remains the most effective treatment to manage NAFLD. This study aimed to estimate the effect of the Low Glycemic Index Mediterranean Diet (LGIMD) and exercise (aerobic and resistance) over a one-year period on the longitudinal trajectories of glucose metabolism regulatory pathways.

MATERIALS AND METHODS

In this observational study, 58 subjects (aged 18-65) with different degrees of NAFLD severity were enrolled by the National Institute of Gastroenterology-IRCCS "S. de Bellis", to follow a 12-month program of combined exercise and diet.

RESULTS

The mean age was 55 ± 7 years old. Gender was equally distributed among NAFLD categories. There was a statistically significant main effect of time for glycosylated hemoglobin (Hb1Ac) over the whole period (-5.41, 95% CI: -7.51; -3.32). There was a steady, statistically significant decrease of HbA1c in participants with moderate and severe NAFLD whereas this effect was observed after the 9th month in those with mild NAFLD.

CONCLUSIONS

The proposed program significantly improves glucose metabolism parameters, especially HbA1c.

The Effect of Walking Combined with Neuromuscular Electrical Stimulation on Liver Stiffness and Insulin Resistance in Patients with Non-alcoholic Fatty Liver Disease: An Exploratory Randomized Controlled Trial

Increased liver stiffness and insulin resistance are important therapeutic targets in patients with nonalcoholic fatty liver disease (NAFLD). A hybrid training system (HTS) has been developed which combines application of electrical stimulation and volitional contractions. We compared the effect of walking exercise (5.6 km/h) both with and without simultaneous HTS on liver stiffness and insulin resistance. In a single-blind, controlled trial, 32 subjects with NAFLD were randomized to 12 weeks of triweekly 30 minute walking exercise with either HTS (HTS group) or without HTS (control group). Transient elastography for the assessment of liver stiffness, body weight, visceral fat, the homeostasis model assessment of insulin resistance, fasting blood glucose, serum aspartate aminotransferase, alanine aminotransferase, and gamma-glutamyl transpeptidase were evaluated. Data were evaluated using the linear model after adjusting the baseline value. In the subjects with BMI of 27 kg/m² or more, the decrement of transient elastography in the HTS group was significantly larger than in the control group (mean ± standard error: Δ2.13 ± 0.64 kPa vs. Δ-0.67 ± 0.42 kPa, p=0.0009). There were no significant differences between groups in other endpoints. These results showed that simultaneously combining electrical stimulation with walking exercise could potentially improve liver stiffness in people who have NAFLD. In fact, because the exercise effect was increased by HTS without increasing the walking speed, this HTS could be especially useful for obese or overweight subjects, in whom NAFLD and joint problems often coexist. However, its effects on insulin resistance and body composition were not clear.

Gene therapy targeting miR‑212‑3p exerts therapeutic effects on MAFLD similar to those of exercise

Exercise is the main treatment for patients with metabolic‑associated fatty liver disease (MAFLD); however, it may be difficult for some patients to adhere to or tolerate an exercise regime. Thus, finding a treatment alternative to exercise is of particular importance. The authors have previously demonstrated that the high expression of microRNA (miRNA/miR)‑212 promotes lipogenesis in vitro. The present study aimed to explore the therapeutic potential, as well as the mechanisms of action of miR‑212 in MAFLD. The expression of miR‑212‑3p, but not that of miR‑212‑5p, was found to be significantly elevated in MAFLD and to be decreased by exercise. Compared with exercise treatment, the inhibition of miR‑212‑3p expression in a mouse model fed a high‑fat diet exerted beneficial effects on MAFLD similar to those of exercise. Conversely, the overexpression of miR‑212‑3p abolished the ameliorative effects of exercise on MAFLD. Fibroblast growth factor 21 (FGF21) and chromodomain helicase DNA binding protein 1 (CHD1) were identified as target genes of miR‑212‑3p in lipid metabolism using bioinformatics analysis. Mechanistically, the inhibition of miR‑212‑3p mimicked the effects of exercise on lipid metabolism by regulating FGF21, but not CHD1. The exercise‑related transcription factor, early growth response 1 (EGR1), was identified upstream of miR‑212‑3p through promoter motif analysis. EGR1 overexpression inhibited miR‑212‑3p expression. The overexpression of miR‑212‑3p abolished the effects of exercise on lipid metabolism by exogenously attenuating the transcriptional repression of EGR1. Moreover, the overexpression of miR‑212‑3p abolished the regulatory effects of EGR1 on FGF21. On the whole, the present study demonstrates that miR‑212‑3p plays a key role in the effects of exercise on MAFLD. The findings presented herein suggest a potential therapeutic effect of targeting miR‑212‑3p in MAFLD.

The Effect of Low Glycemic Index Mediterranean Diet and Combined Exercise Program on Metabolic-Associated Fatty Liver Disease: A Joint Modeling Approach

Background: Excessive caloric intake and reduced energy expenditure are associated with the onset of metabolic-associated fatty liver disease (MAFLD). The aim of this study was to probe the benefits of a low glycemic index Mediterranean diet (LGIMD) and a combined exercise program (CEP) on MAFLD by monitoring the clinical process through anthropometric measurement, body mass index (BMI), and specific biomarkers, such as the Homeostatic Model Assessment for Insulin Resistance (HOMA-IR). Methods: The study was conducted at the National Institute of Gastroenterology, ‘S. de Bellis’, Italy. Subjects were invited to join the study for 12 months. Results: 54 participants were enrolled. Joint modeling of longitudinal and time-to-event data was applied. Overall, a statistically significant direct effect of LGIMD/CEP adherence on ln (BMI), a statistically significant direct effect of LGIMD/CEP adherence on time-to-event and a strong statistically significant direct effect of log (BMI) on time-to-event were observed. In addition, a statistically significant direct effect of LGIMD/CEP adherence on ln(HOMA-IR), a statistically significant direct effect of LGIMD/CEP adherence on time-to-event and a statistically significant direct effect of ln(HOMA-IR) on time-to-event were observed. Conclusions: LGIMD/CEP significantly improved MAFLD status; in addition, longitudinal BMI and HOMA-IR were good predictors of the disappearance of diagnostic criteria for MAFLD.

Exerkines in health, resilience and disease

The health benefits of exercise are well-recognized and are observed across multiple organ systems. These beneficial effects enhance overall resilience, healthspan and longevity. The molecular mechanisms that underlie the beneficial effects of exercise, however, remain poorly understood. Since the discovery in 2000 that muscle contraction releases IL-6, the number of exercise-associated signalling molecules that have been identified has multiplied. Exerkines are defined as signalling moieties released in response to acute and/or chronic exercise, which exert their effects through endocrine, paracrine and/or autocrine pathways. A multitude of organs, cells and tissues release these factors, including skeletal muscle (myokines), the heart (cardiokines), liver (hepatokines), white adipose tissue (adipokines), brown adipose tissue (baptokines) and neurons (neurokines). Exerkines have potential roles in improving cardiovascular, metabolic, immune and neurological health. As such, exerkines have potential for the treatment of cardiovascular disease, type 2 diabetes mellitus and obesity, and possibly in the facilitation of healthy ageing. This Review summarizes the importance and current state of exerkine research, prevailing challenges and future directions.

Transcriptomics Reveals Discordant Lipid Metabolism Effects between In Vitro Models Exposed to Elafibranor and Liver Samples of NAFLD Patients after Bariatric Surgery

BACKGROUND AND AIMS

Non-alcoholic steatohepatitis (NASH) is a life-threatening stage of non-alcoholic fatty liver disease (NAFLD) for which no drugs have been approved. We have previously shown that human-derived hepatic in vitro models can be used to mimic key cellular mechanisms involved in the progression of NASH. In the present study, we first characterize the transcriptome of multiple in vitro NASH models. Subsequently, we investigate how elafibranor, which is a peroxisome proliferator-activated receptor (PPAR)-α/δ agonist that has recently failed a phase 3 clinical trial as a potential anti-NASH compound, modulates the transcriptome of these models. Finally, we compare the elafibranor-induced gene expression modulation to transcriptome data of patients with improved/resolved NAFLD/NASH upon bariatric surgery, which is the only proven clinical NASH therapy.

METHODS

Human whole genome microarrays were used for the transcriptomics evaluation of hepatic in vitro models. Comparison to publicly available clinical datasets was conducted using multiple bioinformatic application tools.

RESULTS

Primary human hepatocytes (PHH), HepaRG, and human skin stem cell-derived hepatic progenitors (hSKP-HPC) exposed to NASH-inducing triggers exhibit up to 35% overlap with datasets of liver samples from NASH patients. Exposure of the in vitro NASH models to elafibranor partially reversed the transcriptional modulations, predicting an inhibition of toll-like receptor (TLR)-2/4/9-mediated inflammatory responses, NFκB-signaling, hepatic fibrosis, and leukocyte migration. These transcriptomic changes were also observed in the datasets of liver samples of patients with resolved NASH. Peroxisome Proliferator Activated Receptor Alpha (PPARA), PPARG Coactivator 1 Alpha (PPARGC1A), and Sirtuin 1 (SIRT1) were identified as the major common upstream regulators upon exposure to elafibranor. Analysis of the downstream mechanistic networks further revealed that angiopoietin Like 4 (ANGPTL4), pyruvate dehydrogenase kinase 4 (PDK4), and perilipin 2 (PLIN2), which are involved in the promotion of hepatic lipid accumulation, were also commonly upregulated by elafibranor in all in vitro NASH models. Contrarily, these genes were not upregulated in liver samples of patients with resolved NASH.

CONCLUSION

Transcriptomics comparison between in vitro NASH models exposed to elafibranor and clinical datasets of NAFLD patients after bariatric surgery reveals commonly modulated anti-inflammatory responses, but discordant modulations of key factors in lipid metabolism. This discordant adverse effect of elafibranor deserves further investigation when assessing PPAR-α/δ agonism as a potential anti-NASH therapy.

Clinical practice advice on lifestyle modification in the management of nonalcoholic fatty liver disease in Japan: an expert review

Nonalcoholic fatty liver disease (NAFLD) is the most common cause of chronic liver diseases worldwide, including in Japan. The Japanese Society of Gastroenterology (JSGE) and the Japanese Society of Hepatology (JSH) have established the Japanese NAFLD/NASH guidelines in 2014 and revised these guidelines in 2020. As described in these guidelines, weight reduction by diet and/or exercise therapy is important for the treatment of NAFLD patients. The I148M single nucleotide polymorphism (rs738409 C > G) of PNPLA3 (patatin-like phospholipase domain-containing 3 protein) is widely known to be associated with the occurrence and progression of NAFLD. In the Japanese, the ratio of PNPLA3 gene polymorphisms found is approximately 20%, which is higher than that found in Westerners. In addition, the ratio of lean NAFLD patients is also higher in Japan than in Western countries. Therefore, the method for lifestyle guidance for the NAFLD patients in Japan would be different from that for the people in Western countries. The problems in the treatment of NAFLD patients include alcohol consumption and sarcopenia. Therefore, guidelines that can help clinicians treat Japanese patients with NAFLD are needed. In this expert review, we summarize evidence-based interventions for lifestyle modification (diet, exercise, alcohol, and sarcopenia) for the treatment of patients with NAFLD, especially from Japan and Asian countries.

Exercise prevents fatty liver by modifying the compensatory response of mitochondrial metabolism to excess substrate availability

Objective

Liver mitochondria adapt to high-calorie intake. We investigated how exercise alters the early compensatory response of mitochondria, thus preventing fatty liver disease as a long-term consequence of overnutrition.

Methods

We compared the effects of a steatogenic high-energy diet (HED) for six weeks on mitochondrial metabolism of sedentary and treadmill-trained C57BL/6N mice. We applied multi-OMICs analyses to study the alterations in the proteome, transcriptome, and lipids in isolated mitochondria of liver and skeletal muscle as well as in whole tissue and examined the functional consequences by high-resolution respirometry.

Results

HED increased the respiratory capacity of isolated liver mitochondria, both in sedentary and in trained mice. However, proteomics analysis of the mitochondria and transcriptomics indicated that training modified the adaptation of the hepatic metabolism to HED on the level of respiratory complex I, glucose oxidation, pyruvate and acetyl-CoA metabolism, and lipogenesis. Training also counteracted the HED-induced glucose intolerance, the increase in fasting insulin, and in liver fat by lowering diacylglycerol species and c-Jun N-terminal kinase (JNK) phosphorylation in the livers of trained HED-fed mice, two mechanisms that can reverse hepatic insulin resistance. In skeletal muscle, the combination of HED and training improved the oxidative capacity to a greater extent than training alone by increasing respiration of isolated mitochondria and total mitochondrial protein content.

Conclusion

We provide a comprehensive insight into the early adaptations of mitochondria in the liver and skeletal muscle to HED and endurance training. Our results suggest that exercise disconnects the HED-induced increase in mitochondrial substrate oxidation from pyruvate and acetyl-CoA-driven lipid synthesis. This could contribute to the prevention of deleterious long-term effects of high fat and sugar intake on hepatic mitochondrial function and insulin sensitivity.

•

High-energy diet promotes mitochondrial respiration in liver independent of training.

•

High-energy diet combined with training disconnects substrate oxidation from lipid synthesis.

•

High-energy diet combined with training reduces complex I formation in the liver.

•

Trained skeletal muscle unburdens the liver from substrate overload.

•

Comprehensive resource of mitochondrial adaptations to high-energy diet and training.

New Insights into Molecular Mechanisms Mediating Adaptation to Exercise; A Review Focusing on Mitochondrial Biogenesis, Mitochondrial Function, Mitophagy and Autophagy

Exercise itself is fundamental for good health, and when practiced regularly confers a myriad of metabolic benefits in a range of tissues. These benefits are mediated by a range of adaptive responses in a coordinated, multi-organ manner. The continued understanding of the molecular mechanisms of action which confer beneficial effects of exercise on the body will identify more specific pathways which can be manipulated by therapeutic intervention in order to prevent or treat various metabolism-associated diseases. This is particularly important as exercise is not an available option to all and so novel methods must be identified to confer the beneficial effects of exercise in a therapeutic manner. This review will focus on key emerging molecular mechanisms of mitochondrial biogenesis, autophagy and mitophagy in selected, highly metabolic tissues, describing their regulation and contribution to beneficial adaptations to exercise.

The Troubling Link Between Non-alcoholic Fatty Liver Disease (NAFLD) and Extrahepatic Cancers (EHC)

Non-alcoholic fatty liver disease (NAFLD) is a fast-spreading epidemic across the globe and has serious implications far beyond that of a "benign" liver condition. It is usually an outcome of ectopic fat storage due to chronic positive energy balance leading to obesity and is associated with multiple health problems. While association with cardiovascular disease and hepatocellular cancer is well recognized, it is becoming clear the NAFLD carries with it an increased risk of cancers of extrahepatic tissues. Studies have reported a higher risk for cancers of the colon, breast, prostate, lung, and pancreas. Fatty liver is associated with increased mortality; there is an urgent need to understand that fatty liver is not always benign, and not always associated with obesity. It is, however, a reversible condition and early recognition and intervention can alter its natural history and associated complications.

Hybrid Training System Improves Insulin Resistance in Patients with Nonalcoholic Fatty Liver Disease: A Randomized Controlled Pilot Study

Insulin resistance is associated with the progression of nonalcoholic fatty liver disease (NAFLD). Insulin resistance is regulated by various cytokines, including interleukin-6 (IL-6), a proinflammatory myokine, and selenoprotein P (SeP), a liver-derived secretory hepatokine. High levels of IL-6 and/or SeP have been shown to contribute to insulin resistance, and exercise is a first-line therapy for NAFLD. We have developed a hybrid training system (HTS): a neuromuscular electrical stimulation device to enhance exercise results. We aimed to investigate the effects of HTS on insulin resistance as well as serum IL-6 and SeP in patients with NAFLD. This is a randomized, single-blind (assessor), controlled trial. Subjects with NAFLD walked on a treadmill with or without HTS (9 subjects each) for 30 minutes three times a week for six weeks (HTS vs. control group; median age 45 vs. 45; male/female 5/4 vs. 6/3). We examined subjects before the first session and at the end of the final session. Serum SeP levels were measured by ELISA which measures the fragment of SeP. In the HTS group, HOMA-IR values were significantly reduced compared to the control group (Δ-0.71 vs. Δ0.05; P < 0.05). IL-6 and SeP levels in serum were also significantly reduced compared to that of the control group (IL-6; Δ-0.6 vs. Δ0.29 pg/mL; P < 0.05, SeP; Δ-1288.5 vs. Δ-435.4 ng/mL; P < 0.05, respectively). In conclusion, we propose that HTS improves insulin resistance by reducing serum IL-6 and SeP levels in patients with NAFLD.

Effect of exercise on cardiometabolic health of adults with overweight or obesity: Focus on blood pressure, insulin resistance, and intrahepatic fat-A systematic review and meta-analysis

This systematic review examined the impact of exercise intervention programs on selected cardiometabolic health indicators in adults with overweight or obesity. Three electronic databases were explored for randomized controlled trials (RCTs) that included adults with overweight or obesity and provided exercise-training interventions. Effects on blood pressure, insulin resistance (homeostasis model of insulin resistance, HOMA-IR), and magnetic resonance measures of intrahepatic fat in exercise versus control groups were analyzed using random effects meta-analyses. Fifty-four articles matched inclusion criteria. Exercise training reduced systolic and diastolic blood pressure (mean difference, MD = -2.95 mmHg [95% CI -4.22, -1.68], p < 0.00001, I²  = 63% and MD = -1.93 mmHg [95% CI -2.73, -1.13], p < 0.00001, I²  = 54%, 60 and 58 study arms, respectively). Systolic and diastolic blood pressure decreased also when considering only subjects with hypertension. Exercise training significantly decreased HOMA-IR (standardized mean difference, SMD = -0.34 [-0.49, -0.18], p < 0.0001, I²  = 48%, 37 study arms), with higher effect size in subgroup of patients with type 2 diabetes (SMD = -0.50 [95% CI: -0.83, -0.17], p = 0.003, I²  = 39%). Intrahepatic fat decreased significantly after exercise interventions (SMD = -0.59 [95% CI: -0.78, -0.41], p < 0.00001, I²  = 0%), with a larger effect size after high-intensity interval training. In conclusion, exercise training is effective in improving cardiometabolic health in adults with overweight or obesity also when living with comorbitidies.

Effect of Different Exercise Methods on Non-Alcoholic Fatty Liver Disease: A Meta-Analysis and Meta-Regression

Exercise could alleviate non-alcoholic fatty liver disease (NAFLD), but it was not clear which exercise methods could effectively treat NAFLD. The purpose of this systematic review and meta-analysis was to evaluate the effects of different exercise patterns on eight indicators in patients with NAFLD. We searched PubMed, Scopus, Web of Science, China National Knowledge Infrastructure, and the Wanfang Data from its inception to 30 June 2020. This review includes all randomized controlled trials (RCT) that assessed and compared the effects of different exercise on eight indicator parameters in patients with NAFLD. The results indicate that aerobic exercises could significantly improve the eight indicators in patients with NAFLD including triglycerides (TG, weighted mean difference (WMD) = −0.53, 95%CI: −0.68~−0.39, Z = 7.37, p < 0.01), total cholesterol (TC, WMD = −0.39, 95%CI: −0.55~−0.23, Z = 4.76, p < 0.01), low density lipoprotein (LDL, WMD = −0.47, 95%CI: −0.68~−0.26, Z = 4.33, p < 0.01), high density lipoprotein (HDL, WMD = 0.12, 95%CI: 0.05~0.18, Z = 3.56, p < 0.01), alanine aminotransferase (ALT, WMD = −6.14, 95%CI: −10.99~−1.29, Z = 2.48, p < 0.05), aspartate aminotransferase (AST, WMD = −5.73, 95%CI: −9.08~−2.38, Z = 3.36, p < 0.01), and body mass index (BMI, WMD = −0.85, 95%CI: −1.19~−0.51, Z = 4.92, p < 0.01). Resistance exercises could significantly reduce the levels of TG (WMD = −0.56, 95%CI: −0.85~−0.28, Z = 3.86, p < 0.01) and AST (WMD = −2.58, 95%CI: −4.79~−0.36, Z = 2.28, p < 0.05) in the patients. High-intensity interval training could significantly improve the level of ALT (WMD = −6.20, 95%CI: −9.34~−3.06, Z = 3.87, p < 0.01) in patients with NAFLD. These three exercise methods had different effects on the eight indexes of NAFLD in our present meta-analysis, providing some reference for the establishment of exercise prescription for patients with NAFLD.

DSS-induced colitis is associated with adipose tissue dysfunction and disrupted hepatic lipid metabolism leading to hepatosteatosis and dyslipidemia in mice

Considering high prevalence of non-alcoholic fatty liver diseases (NAFLD) in patients with inflammatory bowel disease (IBD), this study aimed to elucidate molecular mechanisms for how intestinal inflammatory conditions are causally linked to hepatic steatosis and dyslipidemia. Both younger and older mice treated with acute or chronic dextran sodium sulfate (DSS) developed colitis, which was evidenced by weight loss, colon length shortening, and elevated disease activity index and inflammation score. They also showed decreased expression of intestinal barrier function-related proteins and elevated plasma lipopolysaccharide level, indicating DSS-induced barrier dysfunction and thereby increased permeability. Interestingly, they displayed phenotypes of hepatic fat accumulation and abnormal blood lipid profiles. This DSS-induced colitis-associated lipid metabolic dysfunction was due to overall disruption of metabolic processes including fatty acid oxidation, lipogenesis, lipolysis, reverse cholesterol transport, bile acid synthesis, and white adipose tissue browning and brown adipose tissue thermogenesis, most of which are mediated by key regulators of energy homeostasis such as FGF21, adiponectin, and irisin, via SIRT1/PGC-1α- and LXRα-dependent pathways. Our study suggests a potential molecular mechanism underlying the comorbidity of NAFLD and IBD, which could provide a key to understanding how the two diseases are pathogenically linked and discovering critical therapeutic targets for their treatment.

Hepatokines as a Molecular Transducer of Exercise

Exercise has health benefits and prevents a range of chronic diseases caused by physiological and biological changes in the whole body. Generally, the metabolic regulation of skeletal muscle through exercise is known to have a protective effect on the pathogenesis of metabolic syndrome, non-alcoholic fatty liver disease (NAFLD), type 2 diabetes (T2D), and cardiovascular disease (CVD). Besides this, the importance of the liver as an endocrine organ is a hot research topic. Hepatocytes also secrete many hepatokines in response to nutritional conditions and/or physical activity. In particular, certain hepatokines play a major role in the regulation of whole-body metabolic homeostasis. In this review, we summarize the recent research findings on the exercise-mediated regulation of hepatokines, including fibroblast growth factor 21, fetuin-A, angiopoietin-like protein 4, and follistatin. These hepatokines serve as molecular transducers of the metabolic benefits of physical activity in chronic metabolic diseases, including NAFLD, T2D, and CVDs, in various tissues.

Vitamin B6 efficacy in the treatment of nonalcoholic fatty liver disease: an open-label, single-arm, single-center trial

Vitamin B6 is an important cofactor in fat metabolism and its deficiency has been correlated with nonalcoholic fatty liver disease. However, no study has investigated the efficacy of vitamin B6 supplementation in these patients. The aim of this open-label, single-arm, single-center study was to examine the therapeutic effect of vitamin B6 in patients with nonalcoholic fatty liver disease. Twenty-two patients with nonalcoholic fatty liver disease received vitamin B6 (90 mg/day) orally for 12 weeks. Clinical parameters were evaluated, and liver fat and fibrosis were quantified before and after treatment using magnetic resonance imaging-based proton density fat fraction and magnetic resonance elastography. Serum alanine aminotransferase levels, the primary endpoint, did not change significantly after vitamin B6 treatment (93.6 ± 46.9 to 93.9 ± 46.6, p = 0.976). On the other hand, magnetic resonance imaging-based proton density fat fraction, a parameter of hepatic lipid accumulation, was significantly reduced (18.7 ± 6.1 to 16.4 ± 6.4, p<0.001) despite no significant changes in body mass index, even in those not taking vitamin E (n = 17, 18.8 ± 6.9 to 16.7 ± 7.3, p = 0.0012). Vitamin B6 administration significantly ameliorated hepatic fat accumulation. As an inexpensive agent with few side effects, vitamin B6 could be a novel therapeutic agent for the treatment of nonalcoholic fatty liver disease.

Aerobic Exercise in the Management of Metabolic Dysfunction Associated Fatty Liver Disease

Sedentarism is the pandemic of modern times. It is associated with several medical conditions including obesity, type 2 diabetes mellitus, cardiovascular diseases and also liver disease, particularly metabolic dysfunction associated fatty liver disease (MAFLD). In an era when MAFLD is the most prevalent chronic liver disease worldwide, whilst no pharmacological therapy has been approved for it, exercise has proved to be effective in improving liver steatosis. Interestingly, exercise decreases liver fat even in the absence of weight loss. The challenge for the clinician is to motivate the obese patient with MAFLD, and associated co-morbidities, who has crystallized a sedentary behavior, at times when every need is at the distance of a click on the Internet, and the entire world can be visited behind a screen. In this review, the aggregate evidence on the mechanisms and effects of exercise in the management of MAFLD is summarized, with simple recommendations for everyday clinical practice.

Delayed Exercise Training Improves Obesity-Induced Chronic Kidney Disease by Activating AMPK Pathway in High-Fat Diet-Fed Mice

Exercise training is now recognized as an interesting therapeutic strategy in managing obesity and its related disorders. However, there is still a lack of knowledge about its impact on obesity-induced chronic kidney disease (CKD). Here, we investigated the effects of a delayed protocol of endurance exercise training (EET) as well as the underlying mechanism in obese mice presenting CKD. Mice fed a high-fat diet (HFD) or a low-fat diet (LFD) for 12 weeks were subsequently submitted to an 8-weeks EET protocol. Delayed treatment with EET in obese mice prevented body weight gain associated with a reduced calorie intake. EET intervention counteracted obesity-related disorders including glucose intolerance, insulin resistance, dyslipidaemia and hepatic steatosis. Moreover, our data demonstrated for the first time the beneficial effects of EET on obesity-induced CKD as evidenced by an improvement of obesity-related glomerulopathy, tubulo-interstitial fibrosis, inflammation and oxidative stress. EET also prevented renal lipid depositions in the proximal tubule. These results were associated with an improvement of the AMPK pathway by EET in renal tissue. AMPK-mediated phosphorylation of ACC and ULK-1 were particularly enhanced leading to increased fatty acid oxidation and autophagy improvement with EET in obese mice.

Water Extract of Artemisia annua L. Exhibits Hepatoprotective Effects Through Improvement of Lipid Accumulation and Oxidative Stress-Induced Cytotoxicity

Nonalcoholic fatty liver disease (NAFLD) is a metabolic liver disease with a complex underlying mechanism that has not been completely understood. Thus, effective and safe drugs for this disease are not yet available. Artemisia annua L. is a medicinal plant with potent antimicrobial and antioxidant activities. In this study, we prepared a water extract of A. annua (WEAA) and examined its potential for NAFLD treatment. First, we pretreated HepG2 cells (human hepatocarcinoma cell line) with WEAA and then treated the cells with oleic acid or tert-butylhydroperoxide to examine the effect of WEAA on the lipid accumulation and the cytotoxicity, respectively. WEAA not only inhibited lipid accumulation within HepG2 cells but also protected cells from oxidative stress-mediated damage through the activation of antioxidant enzymes (such as activation of superoxide dismutase and production of glutathione) and its own scavenging activity. Next, to confirm protective effect of the WEAA in in vivo, mice were intragastrically administered with WEAA, extract of Silybum marianum or water once a day, and simultaneously provided with high-fat diet to induce fatty liver and hepatic steatosis. Oral administration of WEAA ameliorated weight gain and hepatic lipid accumulation in high-fat diet-fed mice. Moreover, the plasma levels of triglyceride, aspartate aminotransferase, and alanine aminotransferase were reduced in the WEAA-treated group. Our findings indicated that WEAA may be a potential intervention for preventing or treating hepatic lipid accumulation and liver damage.

Risk Prediction for Non-alcoholic Fatty Liver Disease Based on Biochemical and Dietary Variables in a Chinese Han Population

Nonalcoholic fatty liver disease (NAFLD) is a common liver disease globally, but there are no optimal methods for its prediction or diagnosis. The present cross-sectional study proposes a non-invasive tool for NAFLD screening. The study included 2,446 individuals, of whom 574 were NAFLD patients. Multivariable logistic regression analysis was used to identify risk factors for NAFLD and incorporate them in a risk prediction nomogram model; the variables included both clinical and lifestyle-related variables. Following stepwise regression, BMI, waist circumference, serum triglyceride, high-density lipoprotein cholesterol, alanine aminotransferase, presence of diabetes and hyperuricemia, tuber and fried food consumption were identified as significant risk factors and used in the model. The final nomogram was found to have good discrimination ability (area under the receiver operating characteristic curve = 0.843 [95% CI: 0.819-0.867]), and reasonable accuracy for the prediction of NAFLD risk. A cut-off score of <180 for the nomogram was found to have high sensitivity and predictivity for the exclusion of individuals from screening. The model can be used as a non-invasive tool for mass screening.

Physical activity impacts insulin sensitivity post metabolic bariatric surgery in adolescents with severe obesity

BACKGROUND/OBJECTIVES

We hypothesized that physical activity (PA) improves insulin sensitivity in adolescents with severe obesity beyond that attributable to metabolic bariatric surgery (MBS).

SUBJECTS/METHODS

StepWatch^TM monitors objectively measured PA in 88 participants in the Teen Longitudinal Assessment of Bariatric Surgery (Teen-LABS) study. Primary outcomes included absolute change in fasting insulin, HOMA-IR, and fasting glucose from pre-surgery (baseline) to 6, 12, 24, and 36 months post-MBS. SAS PROC TRAJ generated activity trajectories based on probability and individual participant step count trajectories. Linear regression models were used, adjusted for baseline value, visit, surgical procedure, sex, and percent change in BMI. Additional models adjusted for percent change in iliac waist circumference (IWC) or percent body fat (BF), measured by bio-impedance.

RESULTS

Two activity trajectories were identified: more active (MA, n = 13) and less active (LA, n = 75). MA baseline mean daily step count was >6000, increasing to >9000 at 2 years. LA mean daily step count remained at ~4000. Few participants recorded moderate step activity (cadence >80 steps/minute). Still, fasting insulin and HOMA-IR differed in association with activity trajectoy. MA was associated with a greater absolute decrease in fasting insulin (-7.8 μU/ml [95% CI: (-11.8, -3.7)], p ≤ 0.001) and a greater decrease in HOMA-IR (-1.9 [95% CI: (-3.0, -0.7)], p = 0.001), when adjusted for percent change in BMI. The significant independent effect of MA remained when adjusted for percent change in IWC or percent BF. Clinically, 100% of MA trajectory participants normalized fasting insulin, HOMA-IR, and fasting glucose by 6 months and normalization remained throughout the 36 months follow up. In contrast, 76.3 and 65.8% of LA trajectory participants normalized fasting insulin and HOMA-IR, respectively, by 12 months with 28.6% of both remaining normalized at 36 months.

CONCLUSIONS

PA is independently associated with improved insulin sensitivity beyond that attributable to MBS in adolescents with severe obesity.

A descriptive cross sectional study comparing barriers and determinants of physical activity of Sri Lankan middle aged and older adults

BACKGROUND

Benefits of physical activities are numerous. Barriers for physical exercise may differ among middle aged and older adults. Therefore, identifying and comparing the barriers for participating in regular physical exercises among middle aged and older adults will be useful in designing age specific physical exercise programmes.

METHODS

This descriptive cross sectional study was carried out among 206 Sri Lankan adults in the age range of 40-84 years in the Colombo North region of Sri Lanka using culturally validated questionnaires to determine and compare the barriers and factors associated with regular physical activity participation. Majority were males (56%) and 54% were < 60 years. People in the age range of 40-59 years were considered as middle age and ≥ 60 years as older adults. Bivariate analysis and multivariate analysis was carried out to determine the significant factors that are associated with regular physical activity participation.

RESULTS

Lack of free time (52%), feeling too lazy (26%) and bad weather (29%) were the main barriers for the participants. In < 60 years, high level of income (p = 0.008) and in ≥ 60 years, being a male (p = 0.016), having a high level of education (P = 0.002) and a high BMI (p = 0.002) had a significant negative association with the level of physical activities.

CONCLUSIONS

Contrary to findings from surveys in several developed countries, this study showed that having a high level of education and being a male were strongly related with lack of physical activity participation.

Mechanisms of Fibrosis Development in Nonalcoholic Steatohepatitis

Nonalcoholic fatty liver disease is the most prevalent liver disease worldwide, affecting 20%-25% of the adult population. In 25% of patients, nonalcoholic fatty liver disease progresses to nonalcoholic steatohepatitis (NASH), which increases the risk for the development of cirrhosis, liver failure, and hepatocellular carcinoma. In patients with NASH, liver fibrosis is the main determinant of mortality. Here, we review how interactions between different liver cells culminate in fibrosis development in NASH, focusing on triggers and consequences of hepatocyte-macrophage-hepatic stellate cell (HSC) crosstalk. We discuss pathways through which stressed and dead hepatocytes instigate the profibrogenic crosstalk with HSC and macrophages, including the reactivation of developmental pathways such as TAZ, Notch, and hedgehog; how clearance of dead cells in NASH via efferocytosis may affect inflammation and fibrogenesis; and insights into HSC and macrophage heterogeneity revealed by single-cell RNA sequencing. Finally, we summarize options to therapeutically interrupt this profibrogenic hepatocyte-macrophage-HSC network in NASH.

Amount and Intensity of Leisure-Time Physical Activity and Lower Cancer Risk

PURPOSE

To determine whether recommended amounts of leisure-time physical activity (ie, 7.5-15 metabolic equivalent task [MET] hours/week) are associated with lower cancer risk, describe the shape of the dose-response relationship, and explore associations with moderate- and vigorous-intensity physical activity.

METHODS

Data from 9 prospective cohorts with self-reported leisure-time physical activity and follow-up for cancer incidence were pooled. Multivariable Cox regression was used to estimate adjusted hazard ratios (HRs) and 95% CIs of the relationships between physical activity with incidence of 15 types of cancer. Dose-response relationships were modeled with restricted cubic spline functions that compared 7.5, 15.0, 22.5, and 30.0 MET hours/week to no leisure-time physical activity, and statistically significant associations were determined using tests for trend (P < .05) and 95% CIs (< 1.0).

RESULTS

A total of 755,459 participants (median age, 62 years [range, 32-91 years]; 53% female) were followed for 10.1 years, and 50,620 incident cancers accrued. Engagement in recommended amounts of activity (7.5-15 MET hours/week) was associated with a statistically significant lower risk of 7 of the 15 cancer types studied, including colon (8%-14% lower risk in men), breast (6%-10% lower risk), endometrial (10%-18% lower risk), kidney (11%-17% lower risk), myeloma (14%-19% lower risk), liver (18%-27% lower risk), and non-Hodgkin lymphoma (11%-18% lower risk in women). The dose response was linear in shape for half of the associations and nonlinear for the others. Results for moderate- and vigorous-intensity leisure-time physical activity were mixed. Adjustment for body mass index eliminated the association with endometrial cancer but had limited effect on other cancer types.

CONCLUSION

Health care providers, fitness professionals, and public health practitioners should encourage adults to adopt and maintain physical activity at recommended levels to lower risks of multiple cancers.

Sphingolipids in Non-Alcoholic Fatty Liver Disease and Hepatocellular Carcinoma: Ceramide Turnover

Non-alcoholic fatty liver disease (NAFLD) has emerged as one of the main causes of chronic liver disease worldwide. NAFLD comprises a group of conditions characterized by the accumulation of hepatic lipids that can eventually lead to non-alcoholic steatohepatitis (NASH), fibrosis, cirrhosis, and hepatocellular carcinoma (HCC), the fifth most common cancer type with a poor survival rate. In this context, several works have pointed out perturbations in lipid metabolism and, particularly, changes in bioactive sphingolipids, as a hallmark of NAFLD and derived HCC. In the present work, we have reviewed existing literature about sphingolipids and the development of NAFLD and NAFLD-derived HCC. During metabolic syndrome, considered a risk factor for steatosis development, an increase in ceramide and sphigosine-1-phosphate (S1P) have been reported. Likewise, other reports have highlighted that increased sphingomyelin and ceramide content is observed during steatosis and NASH. Ceramide also plays a role in liver fibrosis and cirrhosis, acting synergistically with S1P. Finally, during HCC, metabolic fluxes are redirected to reduce cellular ceramide levels whilst increasing S1P to support tumor growth.

Mediterranean Diet and NAFLD: What We Know and Questions That Still Need to Be Answered

Non-alcoholic fatty liver disease (NAFLD) is the hepatic manifestation of metabolic syndrome and is expected to become the leading cause of end-stage liver disease worldwide over the next few decades. In fact, NAFLD encompasses different clinical scenarios, from the simple accumulation of fat (steatosis) to steatohepatitis (NASH), NASH-cirrhosis, and cirrhosis complications. In this context, it is fundamental to pursue strategies aimed at both preventing the disease and reducing the progression of liver fibrosis once liver damage is already initiated. As of today, no pharmacological treatment has been approved for NAFLD/NASH, and the only recommended treatment of proven efficacy are life-style modifications, including diet and physical exercise pointing at weight loss of 5%–7%. Different dietetic approaches have been proposed in this setting, and in this review, we will discuss the evidence regarding the efficacy of the Mediterranean Diet as a treatment for NAFLD. In particular, we will report the effects on liver-related outcomes.

Myokines in metabolic homeostasis and diabetes

Physical activity exerts multiple beneficial effects and the myokine concept provides a framework for understanding the molecular pathways that integrate contracting muscle in the complex network of organ communication. This network includes multiple distinct and distal organs; however, the autocrine and paracrine effects of myokines within skeletal muscle (in which they are produced) also need specific attention. In humans, the functional allocation of myokines remains limited and recent findings on fibre type-specific myokine signatures point to an additional level of complexity. Myokines are involved in the anti-inflammatory effect of physical activity and, therefore, critically counteract insulin resistance and the metabolic perturbations of obesity and type 2 diabetes. Future work needs to address the role of myokines in concert with other crosstalk molecules, and to define their specific impact for metabolic homeostasis.

Perspectives on Interval Exercise Interventions for Non-Alcoholic Fatty Liver Disease

Non-alcoholic fatty liver disease (NAFLD) is the most common chronic liver disease and is associated with an increased risk of type 2 diabetes, cardiovascular disease, cirrhosis, and liver cancer. Exercise therapy is the most effective treatment for patients with NAFLD. High-intensity interval training (HIIT) is attracting attention as a time-efficient and an effective exercise modality for treating patients with NAFLD. Previous studies have shown that HIIT can reduce fat mass, visceral adipose tissue, and intrahepatic lipid levels and improve hepatic stiffness. HIIT may be an optimal exercise therapy to improve NAFLD in patients with a lack of time.

Importance of fatigue and its measurement in chronic liver disease

The mechanisms of fatigue in the group of people with non-alcoholic fatty liver disease and non-alcoholic steatohepatitis are protean. The liver is central in the pathogenesis of fatigue because it uniquely regulates much of the storage, release and production of substrate for energy generation. It is exquisitely sensitive to the feedback controlling the uptake and release of these energy generation substrates. Metabolic contributors to fatigue, beginning with the uptake of substrate from the gut, the passage through the portal system to hepatic storage and release of energy to target organs (muscle and brain) are central to understanding fatigue in patients with chronic liver disease. Inflammation either causing or resulting from chronic liver disease contributes to fatigue, although inflammation has not been demonstrated to be causal. It is this unique combination of factors, the nexus of metabolic abnormality and the inflammatory burden of non-alcoholic fatty liver disease and non-alcoholic steatohepatitis that creates pathways to different types of fatigue. Many use the terms central and peripheral fatigue. Central fatigue is characterized by a lack of self-motivation and can manifest both in physical and mental activities. Peripheral fatigue is classically manifested by neuromuscular dysfunction and muscle weakness. Therefore, the distinction is often seen as a difference between intention (central fatigue) versus ability (peripheral fatigue). New approaches to measuring fatigue include the use of objective measures as well as patient reported outcomes. These measures have improved the precision with which we are able to describe fatigue. The measures of fatigue severity and its impact on usual daily routines in this population have also been improved, and they are more generally accepted as reliable and sensitive. Several approaches to evaluating fatigue and developing endpoints for treatment have relied of biosignatures associated with fatigue. These have been used singly or in combination and include: physical performance measures, cognitive performance measures, mood/behavioral measures, brain imaging and serological measures. Treatment with non-pharmacological agents have been shown to be effective in symptom reduction, whereas pharmacological agents have not been shown effective.

Role of exercise-induced hepatokines in metabolic disorders

The health-promoting effects of physical activity to prevent and treat metabolic disorders are numerous. However, the underlying molecular mechanisms are not yet completely deciphered. In recent years, studies have referred to the liver as an endocrine organ, since it releases specific proteins called hepatokines. Some of these hepatokines are involved in whole body metabolic homeostasis and are theorized to participate in the development of metabolic disease. In this regard, the present review describes the role of Fibroblast Growth Factor 21, Fetuin-A, Angiopoietin-like protein 4, and Follistatin in metabolic disease and their production in response to acute exercise. Also, we discuss the potential role of hepatokines in mediating the beneficial effects of regular exercise and the future challenges to the discovery of new exercise-induced hepatokines.