Regular exercise coupled to diet regimen accelerates reduction of hepatic steatosis and associated pathological conditions in nonalcoholic fatty liver disease

Evidence related to a vegetarian diet and metabolic dysfunction-associated steatotic liver disease: protocol for a scoping review

INTRODUCTION

Metabolic dysfunction-associated fatty liver disease (MASLD) is the hepatic manifestation of metabolic syndrome and the leading cause of chronic liver disease worldwide. Given that there is no pharmacological treatment for MASLD, it is imperative to understand whether lifestyle modifications may improve biochemical and pathological outcomes. One commonly proposed dietary modification is the Mediterranean diet; however, vegetarianism may also be a promising intervention. Vegetarianism has been shown to be associated with reduced morbidity and mortality in metabolic syndrome outcomes in coronary artery disease and diabetes; however, the relationship between vegetarian diet and MASLD is less clear. In this scoping review, we will provide a comprehensive overview of the current body of evidence related to a vegetarian diet and MASLD.

METHODS AND ANALYSIS

The aim of this scoping review is to describe and summarise the current body of evidence related to MASLD and a vegetarian diet. This review will be conducted using Arksey and O'Malley's framework. The literature review will be conducted using the following databases: SCOPUS, Web of Science, CINAHL-Plus, Cochrane Library and Medline. No restriction will be made on publication date. Included studies will encompass clinical trials and observational designs that examine effects or association of vegetarian diet in adults (≥16 years) and report on the incidence, prevalence or progression of MASLD. Grey literature, non-human studies and articles focusing on changes in a specific food or nutraceutical will be excluded. Articles must have an English-language abstract available to be considered for inclusion. Screening and data extraction will be conducted by two independent reviewers. The findings will be summarised with descriptive statistics.

ETHICS AND DISSEMINATION

Approval from a medical ethics committee is not required for this review. Once the review is complete, the findings will be submitted to a peer-reviewed journal.

Downhill running and caloric restriction attenuate insulin resistance associated skeletal muscle atrophy via the promotion of M2-like macrophages through TRIB3-AKT pathway

BACKGROUD

Downhill running has recently become a promising exercise modality for metabolic syndrome, but the effect and precise mechanism of downhill running training on insulin resistance (IR) induced skeletal muscle atrophy remains unclear. The current study aimed to explore the benefits of downhill running training accompanied by a low-fat diet on skeletal muscle atrophy in IR mice and its possible mechanisms.

METHODS

For in vivo study, high fat diet (HFD) -induced IR mice were submitted to the downhill running training or/and caloric restriction for 8 weeks. In vitro study was performed using co-cultured RAW264.7 macrophages and C2C12 myoblasts model. Glucose tolerance test (GTT), insulin tolerance test (ITT), immunofluorescence staining, Western blot analysis, hematoxylin and eosin (H&E) staining, enzyme-linked immunosorbent assay (ELISA), Cell counting kit-8 (CCK-8) assays and glucose uptake assays were employed to explore the benefits and possible mechanisms of downhill running training accompanied by a low-fat diet on IR mice.

RESULTS

Our data revealed that HFD induces IR, which leading to skeletal muscle atrophy. Downhill running accompanied by caloric restriction mitigated HFD-induced IR and improve skeletal muscle atrophy. Further study suggested that descended TRIB3 mediated the favorable impact of downhill running on IR induced skeletal muscle atrophy by suppressing M1-like macrophages and promoting M2-like macrophages. Macrophages-specific knockdown of TRIB3 exerted similar effects on the macrophage polarization and IR related myogenesis to downhill running training accompanied by caloric restriction. In contrast, macrophages-specific overexpression of TRIB3 descended phosphorylation of AKT, further activated M1-like macrophages and aggravated IR related inhibition of myogenesis.

CONCLUSIONS

This finding demonstrated the beneficial effects of downhill running training and caloric restriction on IR related skeletal muscle atrophy by promoting M2-like macrophages through TRIB3-AKT pathway.

Lifestyle Modification: Evaluation of the Effects of Physical Activity and Low-Glycemic-Index Mediterranean Diet on Fibrosis Score

BACKGROUND

Non-Alcoholic Fatty Liver Disease (NAFLD) is one the most prevalent causes of chronic liver disease worldwide. In the absence of an approved drug treatment, lifestyle modification is the first intervention strategy. This study aimed to estimate the main effect of two different physical activity (PA) programs, and a Low-Glycemic-Index Mediterranean Diet (LGIMD), or their combined effect on liver fibrosis parameters in subjects with NAFLD.

METHODS

Subjects with moderate or severe NAFLD grade of severity (n = 144) were randomly assigned to six intervention arms for three months: LGIMD, PA programs, and their combination. Data were collected at baseline, 45 days, and 90 days. Transient elastography was performed to assess the outcome.

RESULTS

at 90 days, a statistically significant reduction in kPa was found among subjects following LGMID (-2.85, 95% CI -5.24, -0.45) and those following an LGIMD plus PA1 (-2.37, 95% CI -4.39, -0.35) and LGIMD plus Pa2 (-2.21, 95% CI -4.10, -0.32). The contrast between time 2 and time 1 of the LGIMD plus PA2 treatment showed a statistically significant increase, and vice versa: the contrast between time 3 and time 2 of the same treatment showed a statistically significant reduction. The PA1 and PA2 arms also showed reduced kPa, although the results did not reach statistical significance.

CONCLUSIONS

The intervention arms, LGIMD, LGIMD+PA1, and LGIMD+PA2, reduced the fibrosis score.

Calorie Restriction With Exercise Intervention Improves Inflammatory Response in Overweight and Obese Adults: A Systematic Review and Meta-Analysis

Background/Purpose: In this systematic review and meta-analysis, we assessed the effects of exercise (EX) combined with calorie restriction (CR) intervention on inflammatory biomarkers, and correlations between biomarkers and participants' characteristics were calculated in overweight and obese adults. Methods: An article search was conducted through PubMed, Web of Science, EMBASE, the Cochrane database, Scopus, and Google Scholar to identify articles published up to April 2021. Studies that examined the effect of EX + CR intervention on inflammatory biomarkers, including C-reactive protein (CRP), interleukin-6 (IL-6), and tumor necrosis factor-alpha (TNF-α), and compared them with a CR trial in overweight and obese adults were included. We calculated the pooled effect by meta-analysis, identified the correlations (between inflammatory biomarkers and participants' characteristics) through meta-regression, and explored the beneficial variable through subgroup analysis. The Cochrane risk of bias tool and Methodological Index for Non-randomized Studies were used to assess the risk of bias for the included trials. Results: A total of 23 trials, including 1196 overweight and obese adults, were included in the meta-analysis. The pooled effect showed that EX + CR intervention significantly decreased CRP levels (P = 0.02), but had no effect on IL-6 (P = 0.62) and TNF-α (P = 0.11). Meta-regression analysis showed that the effect of EX + CR on CRP, IL-6, and TNF-α changes was correlated with lifestyle behavior of adults (Coef. = -0.380, P = 0.018; Coef. = -0.359, P = 0.031; Coef. = -0.424, P = 0.041, respectively), but not with age and BMI. The subgroup analysis results revealed that participants with sedentary lifestyle behavior did not respond to EX + CR intervention, as we found no changes in CRP, IL-6, and TNF-α concentrations (P = 0.84, P = 0.16, P = 0.92, respectively). However, EX + CR intervention significantly decreased CRP (P = 0.0003; SMD = -0.39; 95%CI: -0.60 to -0.18), IL-6 (P = 0.04; SMD = -0.21; 95%CI: -0.40 to -0.01) and TNF-α (P = 0.006; SMD = -0.40, 95%CI: -0.68 to -0.12) in adults without a sedentary lifestyle or with a normal lifestyle. Furthermore, the values between sedentary and normal lifestyle subgroups were statistically significant for CRP, IL-6, and TNF-α. Conclusion: Our findings showed that combination EX + CR intervention effectively decreased CRP, IL-6, and TNF-α in overweight and obese adults with active lifestyles, but not with sedentary lifestyle behavior. We suggest that 'lifestyle behavior' is a considerable factor when designing new intervention programs for overweight or obese adults to improve their inflammatory response.

The addition of exercise to a weight loss diet on inflammatory markers: a systematic review and Meta-analysis of controlled clinical trials

This systematic review and meta-analysis of controlled clinical trials was performed to evaluate the effects of weight-loss diets plus exercise compared with weight-loss diets alone on inflammatory biomarkers in adults. PubMed, Scopus, EMBASE, Web of Science (ISI), and Google Scholar were searched up to April 2021. Overall effects were derived using a random effects model. The overall quality of evidence was assessed using Grading of Recommendations Assessment, Development, and Evaluation (GRADE). Twenty-nine trials were included in this systematic review and meta-analysis. The meta-analysis showed no significant difference in serum high sensitivity C-reactive protein (hs-CRP) [weighted mean difference (WMD) = -0.004 mg/l, 95% CI: -0.140, 0.132, P = 0.954], interleukin-6 (IL-6) (WMD = -0.039 pg/ml, 95% CI: -0.233 to 0.156, P = 0.696), and tumor necrosis factor-α (TNF-α) (WMD = 0.405 ng/ml, 95% CI: -1.036 to 0.226, P = 0.209) after adding exercise to a weight-loss diet compared with a weight-loss diet alone. Subgroup analysis revealed that exercise plus a weight-loss diet significantly reduced TNF-α in studies greater than 16 weeks in duration (WMD = -0.742 ng/ml, 95% CI: -1.384 to -0.1, P = 0.024). This systematic review and meta-analysis indicate that exercise in addition to a weight-loss diet does not have a significant effect on further reducing inflammatory markers compared to a weight loss diet alone.

Relationships of Dietary Habits and Physical Activity Status with Non-Alcoholic Fatty Liver Disease Featuring Advanced Fibrosis

(1) Aim: Hepatic fibrosis is a prognostic factor for disease progression in non-alcoholic fatty liver disease (NAFLD). We aimed to determine the relationships between diet, physical activity, and the progression of liver fibrosis. (2) Methods: The 349 participants were categorized by their FibroScan-aspartate aminotransferase score, and they completed a questionnaire regarding their diet and physical activity. (3) Results: There were 233 patients in the negative-on-screening group, 78 in the gray zone group, and 38 in the positive-on-screening group. The frequencies of consumption of soybeans and soybean products and of light-colored vegetables were lower in the positive group; whereas the frequencies of consumption of snack food and fried sweets, jelly and pudding, fried food, and butter, lard, and beef tallow were higher. The odds ratios for the fibrosis progression in patients who consumed fried food ≥4 times/week was 2.21. The positive group also showed lower physical activity level (PAL) and exercise (Ex, metabolic equivalents for tasks (METs)/hour/week). The patients who undertook Ex at >7.5 had an odds ratio of 0.21 for the fibrosis progression. (4) Conclusion: High consumption of fried food and low Ex are risk factors for the fibrosis progression in NAFLD.

Perfluorooctanesulfonic Acid (PFOS) Thwarts the Beneficial Effects of Calorie Restriction and Metformin

A combination of calorie restriction (CR), dietary modification, and exercise is the recommended therapy to reverse obesity and nonalcoholic fatty liver disease. In the liver, CR shifts hepatic metabolism from lipid storage to lipid utilization pathways, such as AMP-activated protein kinase (AMPK). Perfluorooctanesulfonic acid (PFOS), a fluorosurfactant previously used in stain repellents and anti-stick materials, can increase hepatic lipids in mice following relatively low-dose exposures. To test the hypothesis that PFOS administration interferes with CR, adult male C57BL/6N mice were fed ad libitum or a 25% reduced calorie diet concomitant with either vehicle (water) or 100 μg PFOS/kg/day via oral gavage for 6 weeks. CR alone improved hepatic lipids and glucose tolerance. PFOS did not significantly alter CR-induced weight loss, white adipose tissue mass, or liver weight over 6 weeks. However, PFOS increased hepatic triglyceride accumulation, in both mice fed ad libitum and subjected to CR. This was associated with decreased phosphorylated AMPK expression in liver. Glucagon (100 nM) treatment induced glucose production in hepatocytes, which was further upregulated with PFOS (2.5 μM) co-treatment. Next, to explore whether the observed changes were related to AMPK signaling, HepG2 cells were treated with metformin or AICAR alone or in combination with PFOS (25 μM). PFOS interfered with glucose-lowering effects of metformin, and AICAR treatment partially impaired PFOS-induced increase in glucose production. In 3T3-L1 adipocytes, metformin was less effective with PFOS co-treatment. Overall, PFOS administration disrupted hepatic lipid and glucose homeostasis and interfered with beneficial glucose-lowering effects of CR and metformin.

Modulation of TRIB3 and Macrophage Phenotype to Attenuate Insulin Resistance After Downhill Running in Mice

Eccentric exercise training accompanied by a low-fat diet can prevent insulin resistance (IR) and is currently an effective method for the treatment of IR induced by high-fat diet (HFD)-associated obesity. However, the molecular mechanisms underlying this improvement of IR in adipose tissue are still not completely clear. In this study, 5–6-week-old male mice were randomly divided into a standard control diet (SCD) group (SC, n = 12) and a HFD group (HF, n = 72). After 12 weeks, 12 mice in each group were randomly sacrificed. The remaining mice in the HF group were randomly submitted to one of the following experimental protocols for 8 weeks: obesity-HFD-sedentary (OHF-Sed, n = 14), obesity-HFD-exercise (OHF-Ex, n = 16), obesity-SCD-sedentary (OSC-Sed, n = 14), and obesity-SCD-exercise (OSC-Ex, n = 16). All obese mice in the exercise group were subjected to downhill running. Half of the mice in each group received an insulin injection (0.75 U/kg) before sample collection. Epididymal fat was removed and weighed. Adipocyte size and inflammatory cell infiltration were observed by H&E staining. Both basal and insulin-stimulated GLUT4 fluorescence and protein contents were detected by immunofluorescence and Western blot. Levels of IL-1β and IL-10 were detected by ELISA. Protein contents of iNOS, Arg-1, TRIB3, p-AKT, and AKT were determined by Western blot. CD86 and CD206 fluorescence were determined by immunofluorescence. The results showed that a HFD for 12 weeks induced IR accompanied by adipose tissue macrophages M1 polarization (increased iNOS protein content and CD86 fluorescence) and TRIB3-AKT activation. Downhill running accompanied by a low-fat diet attenuated IR (p < 0.01), reduced inflammation levels (increased IL-10 protein content and decreased IL-1β protein content), inhibited adipose tissue macrophages M1 polarization (decreased iNOS protein content and CD86 fluorescence) and promoted M2 polarization (increased Arg-1 protein content and CD206 fluorescence), and suppressed TRIB3-AKT signaling. We concluded that downhill running accompanied by dietary fat regulation attenuates HFD-related IR in mice, which may be associated with reduced TRIB3-AKT signaling and activated M2 macrophages in adipose tissue.

Effects of Exercise on the Oral Microbiota and Saliva of Patients with Non-Alcoholic Fatty Liver Disease

Exercise can be hypothesized to play an important role in non-alcoholic fatty liver disease (NAFLD) treatment by changing the oral bacterial flora and in the mechanism underlying periodontal disease. We performed salivary component analysis before and after an exercise regimen, and genome analysis of the oral bacterial flora to elucidate the underlying mechanism. Obese middle-aged men with NAFLD and periodontal disease were allocated to 12-week exercise (n = 49) or dietary restriction (n = 21) groups. We collected saliva to compare the oral microflora; performed predictive analysis of metagenomic functions; and, measured the salivary immunoglobulin A, cytokine, bacterial lipopolysaccharide (LPS), and lactoferrin concentrations. The exercise group showed improvements in the clinical indices of oral environment. Salivary component analysis revealed significant reductions in LPS, and lactoferrin during the exercise regimen. Diversity analysis of oral bacterial flora revealed higher alpha- and beta-diversity after the exercise regimen. Analysis of the microbial composition revealed that the numbers of Campylobacter (+83.9%), Corynebacterium (+142.3%), Actinomyces (+75.9%), and Lautropia (+172.9%) were significantly higher, and that of Prevotella (−28.3%) was significantly lower. The findings suggest that an exercise regimen improves the oral environment of NAFLD patients by increasing the diversity of the oral microflora and reducing the number of periodontal bacteria that produce LPS and its capability.

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.

The impact of exercise training versus caloric restriction on inflammation markers: a systemic review and meta-analysis

Obesity is associated with an increased risk of chronic, low-grade systematic inflammation for which exercise training (EX) and caloric restriction (CR) are potential treatments. We therefore performed a systematic meta-analysis to compare the effect of EX vs. CR and EX + CR vs. CR on inflammation markers in overweight and obese individuals. PubMed, Scopus, Web of Science and the Cochrane were searched up to April 2020 for EX vs. CR or EX + CR vs. CR interventions studies on inflammatory makers i.e. CRP, IL-6 and TNF-α in overweight and obese individuals. Standardized mean differences and 95% confidence intervals were calculated. Thirty two articles (reporting 38 trials) involving 2108 participants were included in the meta-analysis. Based on studies that directly compared EX and CR, there were no evidence for an effect of EX on IL-6 (p = 0.20) and TNF-α (p = 0.58), when compared with a CR. However, when compared to EX, CR has a statistically greater benefit on CRP (p = 0.01). In those studies, directly comparing EX + CR and CR, EX + CR caused a larger decrease in TNF-α (p = 0.002) and IL-6 (p = 0.02) and tended to decrease CRP (p = 0.06) when compared with CR. These results suggest that a combination of EX and CR may be more effective than CR alone at reducing inflammatory cytokines and CRP in overweight and obese individuals.

Liver macrophages mediate effects of downhill running and caloric restriction on nonalcoholic fatty liver disease of high fat diet-fed mice

AIMS

The mechanism of physical activity and calorie restriction remedying non-alcoholic fatty liver disease (NAFLD) remains elusive. The purpose of this study is to explore the effects of eccentric exercise and dietary regulation allied or alone on high-fat diet (HFD) induced NAFLD and its potential mechanism.

MATERIALS AND METHODS

Mice were fed with HFD for 12 weeks and subsequently treated with chronic downhill running and caloric restriction for 8 weeks. Related biochemical index were examined both before and during intervention to evaluate the liver injury and dyslipidemia. Levels of MCP1, TNFα, IL-1β, IL-6 and IL-10 were detected by ELISA. Liver morphology was observed by H&E and oil red O staining. Protein contents of iNOS, Arg-1, IL-1β and IL-10 were determined by Western blot. CD86 and CD206 fluorescence were determined by Immunofluorescence. KEY FINDING: (1) 12 weeks' HFD induced hyperlipemia and hepatic steatosis by activating M1 macrophages phenotype and inhibiting M2 macrophages. (2) Chronic downhill running and caloric restriction promoted liver M2 macrophages phenotype, and inhibited M1 macrophages, to attenuate chronic inflammation and ameliorate hepatic steatosis. (3) The effects of downhill running and dietary regulation allied were more effective on improving NAFLD compared with downhill running or caloric restriction alone.

SIGNIFICANCE

Eccentric exercise accompanied by caloric restriction attenuates HFD-related NAFLD by promoting M2 macrophages phenotype and inhibiting M1 macrophages in liver. These findings may be help to designing better non-pharmacological intervention programs for NAFLD patients.

Exercising the hepatobiliary-gut axis. The impact of physical activity performance

BACKGROUND

Physical inactivity puts the populations at risk of several health problems, while regular physical activity brings beneficial effects on cardiovascular disease, mortality and other health outcomes, including obesity, glycaemic control and insulin resistance. The hepatobiliary tract is greatly involved in several metabolic aspects which include digestion and absorption of nutrients in concert with intestinal motility, bile acid secretion and flow across the enterohepatic circulation and intestinal microbiota. Several metabolic abnormalities, including nonalcoholic fatty liver as well as cholesterol cholelithiasis, represent two conditions explained by changes of the aforementioned pathways.

MATERIALS AND METHODS

This review defines different training modalities and discusses the effects of physical activity in two metabolic disorders, that is nonalcoholic fatty liver disease (NAFLD) and cholelithiasis. Emphasis is given to pathogenic mechanisms involving intestinal bile acids, microbiota and inflammatory status.

RESULTS

A full definition of physical activity includes the knowledge of aerobic and endurance exercise, metabolic equivalent tasks, duration, frequency and intensity, beneficial and harmful effects. Physical activity influences the hepatobiliary-gut axis at different levels and brings benefits to fat distribution, liver fat and gallbladder disease while interacting with bile acids as signalling molecules, intestinal microbiota and inflammatory changes in the body.

CONCLUSIONS

Several beneficial effects of physical activity are anticipated on metabolic disorders linking liver steatosis, gallstone disease, gut motility, enterohepatic circulation of signalling bile acids in relation to intestinal microbiota and inflammatory changes.

The Effects of Physical Exercise on Fatty Liver Disease

The increasing prevalence of obesity has made nonalcoholic fatty liver disease (NAFLD) the most common chronic liver disease. As a consequence, NAFLD and especially its inflammatory form nonalcoholic steatohepatitis (NASH) are the fastest increasing etiology of end-stage liver disease and hepatocellular carcinoma. Physical inactivity is related to the severity of fatty liver disease irrespective of body weight, supporting the hypothesis that increasing physical activity through exercise can improve fatty liver disease. This review summarizes the evidence for the effects of physical exercise on NAFLD and NASH. Several clinical trials have shown that both aerobic and resistance exercise reduce the hepatic fat content. From clinical and basic scientific studies, it is evident that exercise affects fatty liver disease through various pathways. Improved peripheral insulin resistance reduces the excess delivery of free fatty acids and glucose for free fatty acid synthesis to the liver. In the liver, exercise increases fatty acid oxidation, decreases fatty acid synthesis, and prevents mitochondrial and hepatocellular damage through a reduction of the release of damage-associated molecular patterns. In conclusion, physical exercise is a proven therapeutic strategy to improve fatty liver disease.

The rising incidence of nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is the leading cause of liver disease in the United States and will soon be the leading indication for liver transplantation. NAFLD can lead to cirrhosis of the liver and is usually asymptomatic. Prompt referral to a hepatologist may halt the morbidity and mortality associated with NAFLD.

Role of vitamin A oral supplementation on oxidative stress and inflammatory response in the liver of trained rats

The use of dietary supplements to enhance the benefit of exercise training is a common practice. The liver is the organ where all substances are metabolized, and certain supplements have been associated with liver injury. Vitamin A (VA), a liposoluble vitamin stored in the liver, is commonly used as an antioxidant supplement. Here, we evaluated the effect of chronic VA supplementation on oxidative damage and stress parameters in trained rats. Animals were divided into the following groups: sedentary (SE), sedentary/VA (SE+VA), exercise training (ET), and exercise training/VA (ET+VA). During 8 weeks, animals were subjected to swimming (0%, 2%, 4%, 6% body weight) for 5 days/week and a VA daily intake of 450 retinol equivalents/day. Parameters were evaluated by enzymatic activity analysis, ELISA, and Western blotting. VA caused liver lipid peroxidation and protein damage in exercised rats and inhibited the increase in HSP70 expression acquired with exercise alone. The ET group showed higher levels of antioxidant enzyme activity, and VA inhibited this adaptation. Expression of the pro-inflammatory cytokines, interleukin (IL)-1β, and tumor necrosis factor-α was reduced in the ET+VA group, while the anti-inflammatory cytokine, IL-10, was increased. Western blotting showed that both exercised groups had lower levels of the receptor for advanced glycation end products, suggesting that VA did not affect this receptor. Our study demonstrated that, although VA caused oxidative damage, a controlled administration might exert anti-inflammatory effects. Further studies with higher VA doses and longer ET interventions would elucidate more the effects of the supplementation and exercise on liver parameters.

Adipokines in nonalcoholic fatty liver disease

Since the discovery of adipose tissue as a higly active endocrine tissue, adipokines, peptides produced by adipose tissue and exerting autocrine, paracrine and endocrine function, have gained increasing interest in various obesity-related diseases, including nonalcoholic fatty liver disease (NAFLD). Data regarding the association between NAFLD and circulating leptin and adiponectin levels are generally well documented: leptin levels increase, whereas adiponectin levels decrease, by increasing the severity of NAFLD. Data regarding other adipokines in histologically confirmed NAFLD populations are inconclusive (e.g., resistin, visfatin, retinol-binding protein-4, chemerin) or limited (e.g., adipsin, obestatin, omentin, vaspin etc.). This review summarizes evidence on the association between adipokines and NAFLD. The first part of the review provides general consideration on the interplay between adipokines and NAFLD, and the second part provides evidence on specific adipokines possibly involved in NAFLD pathogenesis. A thorough insight into the pathophysiologic mechanisms linking adipokines with NAFLD may result in the design of studies investigating the combined adipokine use as noninvasive diagnostic markers of NAFLD and new clinical trials targeting the treatment of NAFLD.

Medical and Surgical Treatment Options for Nonalcoholic Steatohepatitis

Nonalcoholic fatty liver disease (NAFLD) is the most common cause of liver disease in the USA with a growing prevalence worldwide. Nonalcoholic steatohepatitis (NASH), progressive form of NAFLD, can lead to the development of cirrhosis, hepatocellular carcinoma, and the need for liver transplantation. Treatment of NASH may decrease the risk of progressive disease. Treatment for NAFLD should center around weight loss and exercise. Pharmacotherapy with vitamin E and pioglitazone should be considered for those with NASH, especially those with fibrosis. Weight loss surgery is also an effective treatment for NASH in individuals with other indications for surgery. In this review, we will discuss the currently available therapies for NASH including lifestyle, pharmacologic, and surgical options.

Endoplasmic reticulum stress and Oxidative stress in the pathogenesis of Non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) is the hepatic manifestation of metabolic syndrome. The underlying causes of the disease progression in NAFLD are unclear. Recent evidences suggest endoplasmic reticulum stress in the development of lipid droplets (steatosis) and subsequent generation of reactive oxygen species (ROS) in the progression to non-alcoholic steatohepatitis (NASH). The signalling pathway activated by disruption of endoplasmic reticulum (ER) homoeostasis, called as unfolded protein response, is linked with membrane biosynthesis, insulin action, inflammation and apoptosis. ROS are important mediators of inflammation. Protein folding in ER is linked to ROS. Therefore understanding the basic mechanisms that lead to ER stress and ROS in NAFLD have become the topics of immense interest. The present review focuses on the role of ER stress and ROS in the pathogenesis of NAFLD. We also highlight the cross talk between ER stress and oxidative stress which suggest and encourage the development of therapeutics for NAFLD. Further we have reviewed various strategies used for the management of NAFLD/NASH and limitations of such strategies. Our review therefore highlights the need for newer strategies with regards to ER stress and oxidative stress.

Physical activity as a treatment of non-alcoholic fatty liver disease: A systematic review

AIM

To review the effectiveness of exercise as a therapy for nonalcoholic fatty liver disease (NAFLD) and potential benefits in treating insulin resistance and atherosclerosis.

METHODS

Medline (EBSCOhost) and PubMed were searched for English-language randomized controlled trials and prospective cohort studies in human adults aged ≥ 18 which investigated the various effects of exercise alone, a combination of exercise and diet, or exercise and diet coupled with behavioral modification on NAFLD from 2010 to Feburary 2015.

RESULTS

Eighteen of 2298 available studies were chosen for critical review, which included 6925 patients. Nine (50%) studies were randomized controlled trials. Five (27.8%) studies utilized biopsy to examine the effects of physical activity on hepatic histology. The most commonly employed imaging modality to determine change in hepatic steatosis was hydrogen-magnetic resonance spectroscopy. Only two studies examined the effects of low impact physical activity for patients with significant mobility limitations and one compared the efficacy of aerobic and resistance exercise. No studies examined the exact duration of exercise required for hepatic and metabolic improvement in NAFLD.

CONCLUSION

While exercise improved hepatic steatosis and underlying metabolic abnormalities in NAFLD, more studies are needed to define the most beneficial form and duration of exercise treatment.

Moderate to vigorous physical activity volume is an important factor for managing nonalcoholic fatty liver disease: a retrospective study

Recently, the beneficial effects of increased physical activity (PA) on nonalcoholic fatty liver disease (NAFLD) in obese subjects were reported. However, the optimal strength and volume of PA in lifestyle modification to improve NAFLD pathophysiology and be recommended as an appropriate management of this condition are unclear. The primary goal of this retrospective study was to estimate the beneficial effects of a varying volume of moderate to vigorous intensity PA (MVPA) on the improvement of NAFLD. A total of 169 obese, middle-aged men were enrolled in a 12-week weight reduction program through lifestyle modification consisting of dietary restrictions plus aerobic exercise. Among these obese subjects, 40 performed MVPA for <150 min·wk(-1) , 42 performed MVPA for 150-250 min·wk(-1) , and 87 performed MVPA for >250 min·wk(-1) . The subjects in the MVPA ≥250 min·wk(-1) group, in comparison with those in the MVPA <250 min·wk(-1) group, showed significantly attenuated levels of hepatic steatosis (-31.8% versus -23.2%). This attenuation was likely independent of the detectable weight reduction. MVPA for ≥250 min·wk(-1) in comparison with that for <150 min·wk(-1) led to a significant decrease in the abdominal visceral adipose tissue severity (-40.6% versus -12.9%), levels of ferritin (-13.6% versus +1.5%), and lipid peroxidation (-15.1% versus -2.8%), and a significant increase in the adiponectin levels (+17.1% versus +5.6%). In association with these changes, the gene expression levels of sterol regulatory element-binding protein-1c and carnitine palmitoyltransferase-1 in peripheral blood mononuclear cells also significantly decreased and increased, respectively.

CONCLUSION

MVPA for ≥250 min·wk(-1) as part of lifestyle management improves NAFLD pathophysiology in obese men. The benefits seem to be acquired through reducing inflammation and oxidative stress levels and altering fatty acid metabolism.

Chemokine ligand 2 and paraoxonase-1 in non-alcoholic fatty liver disease: The search for alternative causative factors

The incidence and prevalence of non-alcoholic fatty liver disease (NAFLD) is constantly increasing. Despite this is apparently associated with the growing increase in obesity, insulin resistance and obesity-related metabolic disturbances their presence is not a necessary or sufficient condition to explain the accumulation of fat in the liver. Conversely, NAFLD is a predictor of other metabolic risks. NAFLD is currently the most frequent chronic liver disease but should not be considered benign or anecdotic because a considerable proportion of patients with NAFLD progress to cirrhosis and end-stage liver disease. Consequently, the search for alternative molecular mechanisms with therapeutic implications in NAFLD and associated disorders deserves a careful consideration. Mitochondria are possible targets as these organelles generate energy from nutrient oxidation. Some findings, generated in patients with extreme obesity and in murine models, support the notion that NAFLD could be a mitochondrial disease. This is plausible because mitochondrial dysfunction affects the accumulation of lipids in hepatocytes and promotes lipid peroxidation, the production of reactive oxygen species, the release of cytokines causing inflammation and cell death. Here we discuss basic research and mechanistic studies targeting the role of chemokine ligand 2 in liver inflammation and that of the paraoxonases in the oxidative stress. Their combination and association with mitochondrial dysfunction may uncover mechanisms underlying the progression of NAFLD and may help to identify novel therapeutic targets.

Leptin in nonalcoholic fatty liver disease: a narrative review

Leptin, the first described adipokine, interplays with hepatic metabolism. The aim of this review was to summarize available data on the association between leptin and nonalcoholic fatty liver disease (NAFLD). Leptin has a potential dual action on NAFLD experimental models, exerting a possible anti-steatotic, but also a proinflammatory and profibrogenic action. Observational clinical studies have shown higher or similar leptin levels between simple steatosis and nonalcoholic steatohepatitis (NASH) compared with controls. Interventional studies showed that circulating leptin diminishes together with body mass index after successful weight loss following lifestyle modifications or bariatric surgery. Studies providing evidence for the effect of other medications on leptin levels in NAFLD populations are limited and of low power. Data from small studies claim that recombinant leptin administration had a possibly beneficial effect on steatosis, but not fibrosis, in NAFLD patients with hypoleptinemia. Although the aforementioned dual leptin action has not yet been validated in humans, leptin administration in NAFLD patients with normoleptinemia or hyperleptinemia is discouraged. Further well-controlled studies in cautiously selected populations are needed to elucidate whether leptin has any prognostic and therapeutic role in NAFLD patients.

Role of physical exercise on hepatic insulin, glucocorticoid and inflammatory signaling pathways in an animal model of non-alcoholic steatohepatitis

AIMS

Pro-inflammatory mediators, glucocorticoids and transforming growth factor (TGF)-β are implicated in the pathogenesis of non-alcoholic steatohepatitis (NASH)-related insulin resistance. As physical activity is beneficial against NASH, we analyzed the voluntary physical activity (VPA) and endurance training (ET) (preventive and therapeutic strategies) effects on hepatic insulin, pro-inflammatory and glucocorticoid signaling regulators/mediators in high-fat (Lieber-DeCarli) diet (HFD)-induced NASH.

MAIN METHODS

Adult male Sprague-Dawley rats were divided in standard diet (SD) or HFD, with sedentary, VPA and ET animals in both diet regimens. Plasma glucose and insulin concentrations were analyzed; plasma insulin sensitivity index (ISI) was calculated. Hepatic insulin, pro-inflammatory and glucocorticoid signaling regulators/mediators were evaluated by Western blot or reverse transcriptase-PCR.

KEY FINDINGS

ET improved ISI in both diet regimens. HFD-feeding increased interleukin-1β and induced a similar pattern on interleukin-6 and TGF-β, which were globally reduced by physical exercise. ET decreased HFD leukemia inhibitory factor level, SD+VPA animals presenting higher values than HFD+VPA animals. HFD increased the ratio of IRS-1(Ser307)/total IRS-1, which was completely mitigated by physical exercise. Physical exercise reduced total ERK and JNK (total and activated) expression in HFD. In SD vs. HFD, VPA presented higher activated JNK and ET presented higher total JNK. Generally, in HFD, the ratio (activated/total) of AKT, and each separately, decreased with exercise and also for activated AKT in SD. Overall, in both diets, exercise reduced 11β-hydroxysteroid dehydrogenase type 1. ET increased glucocorticoid receptor and reduced PTP1B in HFD.

SIGNIFICANCE

Physical exercise mitigates the expression of pro-inflammatory mediators and positively modulates insulin and glucocorticoid signaling in NASH.

Non-alcoholic fatty liver disease, obesity and the metabolic syndrome

Nonalcoholic fatty liver disease (NAFLD) is now recognized as the most common cause of chronic liver disease worldwide. Its prevalence has increased to more than 30% of adults in developed countries and its incidence is still rising. The majority of patients with NAFLD have simple steatosis but in up to one third of patients, NAFLD progresses to its more severe form nonalcoholic steatohepatitis (NASH). NASH is characterized by liver inflammation and injury thereby determining the risk to develop liver fibrosis and cancer. NAFLD is considered the hepatic manifestation of the metabolic syndrome. However, the liver is not only a passive target but affects the pathogenesis of the metabolic syndrome and its complications. Conversely, pathophysiological changes in other organs such as in the adipose tissue, the intestinal barrier or the immune system have been identified as triggers and promoters of NAFLD progression. This article details the pathogenesis of NAFLD along with the current state of its diagnosis and treatment.