Hepatic energy metabolism in human diabetes mellitus, obesity and non-alcoholic fatty liver disease

High-fat diet stimulated butyric acid metabolism dysbiosis, altered microbiota, and aggravated inflammatory response in collagen-induced arthritis rats

BACKGROUND

Research has demonstrated that obesity may be associated with rheumatoid arthritis (RA). In addition, Dysbiosis of intestinal microbiota and their metabolites has been linked to the occurrence and development of RA and obesity. However, the mechanism by which obesity affects RA remains unclear.In this study, we explored the impact of high fat diet(HFD) on collagen-induced arthritis (CIA) rats and revealed its mechanisms based on gut microbiota and metabolomics.

METHODS

Based on diet and modeling, rats were divided into normal group (Con), CIA model group, HFD group (HFD), and HFD + CIA group (HCIA). The effect of HFD on arthritis in CIA rats were investigated based on the arthritis index (AI), weight, blood lipid levels, and inflammatory cytokines. Moreover, HE staining and micro-CT were performed to evaluated the effect of HFD on the pathology of joints and synovial tissues in CIA rats.16S rRNA amplicon sequencing and liquid chromatography-mass spectrometry (LC-MS) were employed to explore changes in gut microbiota and short-chain fatty acids (SCFAs).

RESULTS

The AI scores, inflammatory cytokines and bone destruction parameters in the HCIA group were significantly higher than those in the other three groups. The results of 16S rRNA amplicon sequencing and metabolomics showed that compared with the other three groups, the expression of g_Muribaculaceae and butyric acid were reduced in the HCIA group. Spearman and linear correlation analyses revealed a positive correlation between g_Muribaculaceae abundance and butyric acid levels.

CONCLUSIONS

HFD stimulated butyric acid metabolism dysbiosis, altered microbiota, and aggravated inflammatory response in CIA rats.

Mitochondrial structure and function: A new direction for the targeted treatment of chronic liver disease with Chinese herbal medicine

ETHNOPHARMACOLOGICAL RELEVANCE

Excessive fat accumulation, biological clock dysregulation, viral infections, and sustained inflammatory responses can lead to liver inflammation, fibrosis, and cancer, thus promoting the development of chronic liver disease. A comprehensive understanding of the etiological factors leading to chronic liver disease and the intrinsic mechanisms influencing its onset and progression can aid in identifying potential targets for targeted therapy. Mitochondria, as key organelles that maintain the metabolic homeostasis of the liver, provide an important foundation for exploring therapeutic targets for chronic liver disease. Recent studies have shown that active ingredients in herbal medicines and their natural products can modulate chronic liver disease by influencing the structure and function of mitochondria. Therefore, studying how Chinese herbs target mitochondrial structure and function to treat chronic liver diseases is of great significance.

AIM OF THE STUDY

Investigating the prospects of herbal medicine the Lens of chronic liver disease based on mitochondrial structure and function.

MATERIALS AND METHODS

A computerized search of PubMed was conducted using the keywords "mitochondrial structure", "mitochondrial function", "mitochondria and chronic liver disease", "botanicals, mitochondria and chronic liver disease".Data from the Web of Science and Science Direct databases were also included. The research findings regarding herbal medicines targeting mitochondrial structure and function for the treatment of chronic liver disease are summarized.

RESULTS

A computerized search of PubMed using the keywords "mitochondrial structure", "mitochondrial function", "mitochondria and chronic liver disease", "phytopharmaceuticals, mitochondria, and chronic liver disease", as well as the Web of Science and Science Direct databases was conducted to summarize information on studies of mitochondrial structure- and function-based Chinese herbal medicines for the treatment of chronic liver disease and to suggest that the effects of herbal medicines on mitochondrial division and fusion.The study suggested that there is much room for research on the influence of Chinese herbs on mitochondrial division and fusion.

CONCLUSIONS

Targeting mitochondrial structure and function is crucial for herbal medicine to combat chronic liver disease.

Diabetes as a risk factor for MASH progression

Non-alcoholic (now: metabolic) steatohepatitis (MASH) is the progressive inflammatory form of metabolic dysfunction-associated steatotic liver disease (MASLD), which often coexists and mutually interacts with type 2 diabetes (T2D), resulting in worse hepatic and cardiovascular outcomes. Understanding the intricate mechanisms of diabetes-related MASH progression is crucial for effective therapeutic strategies. This review delineates the multifaceted pathways involved in this interplay and explores potential therapeutic implications. The synergy between adipose tissue, gut microbiota, and hepatic alterations plays a pivotal role in disease progression. Adipose tissue dysfunction, particularly in the visceral depot, coupled with dysbiosis in the gut microbiota, exacerbates hepatic injury and insulin resistance. Hepatic lipid accumulation, oxidative stress, and endoplasmic reticulum stress further potentiate inflammation and fibrosis, contributing to disease severity. Dietary modification with weight reduction and exercise prove crucial in managing T2D-related MASH. Additionally, various well-known but also novel anti-hyperglycemic medications exhibit potential in reducing liver lipid content and, in some cases, improving MASH histology. Therapies targeting incretin receptors show promise in managing T2D-related MASH, while thyroid hormone receptor-β agonism has proven effective as a treatment of MASH and fibrosis.

Study on the protective effect of Aronia melanocarpa extract on type 2 diabetes by regulating glucose and lipid metabolism through intestinal flora

Aronia melanocarpa, a plant rich in anthocyanins, has been studied for its potential to regulate blood sugar and blood lipids, although the specific mechanism is not yet understood. This research aims to identify the differential bacterial flora and elucidate the mechanism by which it improves glucose and lipid metabolism disorders through 16S rDNA gene sequencing. The study reveals the protective effect of Aronia melanocarpa extract (AME) on liver damage in type 2 diabetic rats. Experimental results demonstrate that AME can effectively modulate the abundance of intestinal flora, reduce colon tissue damage, enhance the weight of diabetic rats, and lower levels of fasting blood sugar, low-density lipoprotein (LDL), and triglycerides (TG). Additionally, liver morphology analysis shows that AME can effectively mitigate liver tissue structural damage in type 2 diabetic rats. In conclusion, AME regulates glucose and lipid metabolism by influencing intestinal flora, ultimately regulating glucose and lipid metabolism in type 2 diabetic rats.

Shenling Baizhu powder alleviates non-alcoholic fatty liver disease by modulating autophagy and energy metabolism in high-fat diet-induced rats

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) has emerged as a burgeoning health problem worldwide, but no specific drug has been approved for its treatment. Shenling Baizhu powder (SL) is extensively used to treat NAFLD in Chinese clinical practice. However, the therapeutic components and pharmacological mechanisms of SL against NAFLD have not been thoroughly investigated.

PURPOSE

This study aimed to investigate the pharmacological impact and molecular mechanism of SL on NAFLD.

METHODS

First, we established an animal model of NAFLD by high-fat diet (HFD) feeding, and evaluated the therapeutic efficacy of SL on NAFLD by physiological, biochemical, pathological, and body composition analysis. Next, the effect of SL on autophagic flow in NAFLD rats was evaluated by ultrastructure, immunofluorescence staining, and western blotting. Moreover, an integrated strategy of targeted energy metabolomics and network pharmacology was performed to characterize autophagy-related genes and explore the synergistic effects of SL active compounds. UPLC-MS/MS, molecular docking combined with in vivo and in vitro experiments were conducted to verify the key compounds and genes. Finally, a network was established among SL-herb-compound-genes-energy metabolites-NAFLD, which explains the complicated regulating mechanism of SL on NAFLD.

RESULTS

We discovered that SL decreased hepatic lipid accumulation, hepatic steatosis, and insulin resistance, and improved systemic metabolic disorders and pathological abnormalities. Subsequently, an integrated strategy of targeted energy metabolomics and network pharmacology identified quercetin, ellagic acid, kaempferol, formononetin, stigmasterol, isorhamnetin and luteolin as key compounds; catalase (CAT), AKT serine/threonine kinase 1 (AKT), nitric oxide synthase 3 (eNOS), NAD(P)H quinone dehydrogenase 1 (NQO1), heme oxygenase 1 (HO-1) and hypoxia-inducible factor 1 subunit alpha (HIF-1α) were identified as key genes; while nicotinamide adenine dinucleotide phosphate (NADP) and succinate emerged as key energy metabolites. Mechanistically, we revealed that SL may exert its anti-NAFLD effect by inducing autophagy activation and forming a comprehensive regulatory network involving key compounds, key genes, and key energy metabolites, ultimately alleviating oxidative stress, endoplasmic reticulum stress, and mitochondrial dysfunction.

CONCLUSION

Our study demonstrated the therapeutic effect of SL in NAFLD models, and establishes a basis for the development of potential products from SL plant materials for the treatment of NAFLD.

The effects of extracellular vesicles and their cargo on metabolism and its adaptation to physical exercise in insulin resistance and type 2 diabetes

Lifestyle modification represents the first-line strategy for the prevention and treatment of type 2 diabetes mellitus (T2DM), which is frequently associated with obesity and characterized by defective pancreatic insulin secretion and/or insulin resistance. Exercise training is an essential component of lifestyle modification and has been shown to ameliorate insulin resistance by reducing body fat mass and by enhancing skeletal muscle mitochondrial biogenesis and insulin-independent glucose uptake. Additionally, exercising stimulates the release of exerkines such as metabolites or cytokines, but also long non-coding RNA, microRNAs, cell-free DNA (cf-DNA), and extracellular vesicles (EVs), which contribute to inter-tissue communication. There is emerging evidence that EV number and content are altered in obesity and T2DM and may be involved in several metabolic processes, specifically either worsening or improving insulin resistance. This review summarizes the current knowledge on the metabolic effects of exercise training and on the potential role of humoral factors and EV as new biomarkers for early diagnosis and tailored treatment of T2DM.

Role of lifestyle and glucagon-like peptide-1 receptor agonists for weight loss in obesity, type 2 diabetes and steatotic liver diseases

BACKGROUND

The current obesity pandemic has given rise to associated comorbidities and complications, including type 2 diabetes and metabolic dysfunction-associated steatotic liver disease (MASLD). During the last decade, certain glucagon-like peptide 1 receptor agonists (GLP-1RA), originally developed as antihyperglycemic drugs, also demonstrated efficacy for weight loss.

AIMS

To review shared pathophysiologic features of common metabolic diseases and compare therapeutic strategies to reduce body weight and related complications.

METHODS

We performed an extensive literature research to describe the effects of lifestyle modification, first-generation anti-obesity drugs, and GLP-1RA on weight loss in humans with obesity, type 2 diabetes and MASLD.

RESULTS

Until recently, treatment of obesity has been limited to lifestyle modification, which offer moderate degree and sustainability of weight loss. The few approved first-generation anti-obesity drugs are either limited to short term use or to certain forms of obesity. Some GLP-1RA significantly decrease caloric intake and body weight. Liraglutide and semaglutide have therefore been approved for treating people with obesity. They also lead to a reduction of hepatic fat content and inflammation in people with biopsy-confirmed MASLD. Possible limitations comprise adverse effects, treatment adherence and persistence.

CONCLUSION

Certain GLP-1RA are superior to lifestyle modification and first-generation anti-obesity drugs in inducing weight loss. They have therefore markedly changed the portfolio of obesity treatment with additional beneficial effects on steatotic liver disease.

High fat diet increases the severity of collagen-induced arthritis in mice by altering the gut microbial community

OBJECTIVES

Research has demonstrated that obesity may be associated with rheumatoid arthritis (RA). In addition, gut microbiota and its metabolites contribute to the occurrence and development of RA and obesity. However, the mechanism by which obesity affects RA remains unclear. In this study, we aimed to investigate whether gut microbiota and their metabolites alter the effects of high fat diet (HFD) on the severity of collagen-induced arthritis (CIA) in mice.

METHODS

Briefly, mice were divided into normal group (N), CIA model group (C), HFD group (T), and HFD CIA group (CT). Hematoxylin and Eosin staining(HE) and Safranin O-fast green staining were conducted, and levels of blood lipid and inflammatory cytokines were measured. 16S rDNA sequencing technique and liquid chromatography-mass spectrometry (LC-MS)-based metabolomics were performed to explore changes in the microbiota structure to further reveal the pathomechanism of HFD on CIA.

RESULTS

HFD aggravated the severity of CIA in mice. The CT group had the highest proportion of microbial abundance of Blautia, Oscillibacter, Ruminiclostridium-9, and Lachnospiraceae UCG 006 at the genus level, but had a lower proportion of Alistipes. Additionally, the fecal metabolic phenotype of the combined CT group shows significant changes, with differential metabolites enriched in 9 metabolic pathways, including primary bile acid biosynthesis, arginine biosynthesis, sphingolipid metabolism, purine metabolism, linoleic acid metabolism, oxytocin signaling pathway, aminoacyl-tRNA biosynthesis, the pentose phosphate pathway, and sphingolipid signaling pathway. Correlation analysis revealed that some of the altered gut microbiota genera were strongly correlated with changes in fecal metabolites, total cholesterol (TC), triglyceride (TG), and inflammatory cytokine levels.

CONCLUSIONS

This study shows that HFD may aggravate inflammatory reaction in CIA mice by altering the gut microbiota and metabolic pathways.

VCD-induced menopause mouse model reveals reprogramming of hepatic metabolism

OBJECTIVE

Menopause adversely impacts systemic energy metabolism and increases the risk of metabolic disease(s) including hepatic steatosis, but the mechanisms are largely unknown. Dosing female mice with vinyl cyclohexene dioxide (VCD) selectively causes follicular atresia in ovaries, leading to a murine menopause-like phenotype.

METHODS

In this study, we treated female C57BL6/J mice with VCD (160 mg/kg i.p. for 20 consecutive days followed by verification of the lack of estrous cycling) to investigate changes in body composition, energy expenditure (EE), hepatic mitochondrial function, and hepatic steatosis across different dietary conditions.

RESULTS

VCD treatment induced ovarian follicular loss and increased follicle-stimulating hormone (FSH) levels in female mice, mimicking a menopause-like phenotype. VCD treatment did not affect body composition, or EE in mice on a low-fat diet (LFD) or in response to a short-term (1-week) high-fat, high sucrose diet (HFHS). However, the transition to a HFHS lowered cage activity in VCD mice. A chronic HFHS diet (16 weeks) significantly increased weight gain, fat mass, and hepatic steatosis in VCD-treated mice compared to HFHS-fed controls. In the liver, VCD mice showed suppressed hepatic mitochondrial respiration on LFD, while chronic HFHS resulted in compensatory increases in hepatic mitochondrial respiration. Also, liver RNA sequencing revealed that VCD promoted global upregulation of hepatic lipid/cholesterol synthesis pathways.

CONCLUSION

Our findings suggest that the VCD-induced menopause model compromises hepatic mitochondrial function and lipid/cholesterol homeostasis that sets the stage for HFHS diet-induced steatosis while also increasing susceptibility to obesity.

Role of Insulin Resistance in the Development of Nonalcoholic Fatty Liver Disease in People With Type 2 Diabetes: From Bench to Patient Care

Insulin resistance is implicated in both the pathogenesis of nonalcoholic fatty liver disease (NAFLD) and its progression from steatosis to steatohepatitis, cirrhosis, and even hepatocellular carcinoma, which is known to be more common in people with type 2 diabetes. This article reviews the role of insulin resistance in the metabolic dysfunction observed in obesity, type 2 diabetes, atherogenic dyslipidemia, and hypertension and how it is a driver of the natural history of NAFLD by promoting glucotoxicity and lipotoxicity. The authors also review the genetic and environmental factors that stimulate steatohepatitis and fibrosis progression and their relationship with cardiovascular disease and summarize guidelines supporting the treatment of NAFLD with diabetes medications that reduce insulin resistance, such as pioglitazone or glucagon-like peptide 1 receptor agonists.

Reductions in liver enzymes are associated with anti-hyperglycaemic and anti-obesity effects of tofogliflozin in people with type 2 diabetes: Post-hoc analyses

AIMS

How the pathology of type 2 diabetes (T2D), including hyperglycaemia and obesity, affects liver enzymes has not been clinically demonstrated. Thus, we compared time courses of gamma-glutamyltransferase (GGT) and alanine aminotransferase (ALT) with those of fasting plasma glucose (FPG) and body weight (BW) during treatment with the SGLT2 inhibitor tofogliflozin for T2D.

MATERIALS AND METHODS

We post-hoc analysed preexisting data on 1046 people with T2D administered tofogliflozin or placebo for 24 weeks in four tofogliflozin studies. First, time courses of percent changes in variables during the intervention were analysed using a mixed effect model to explore the similarity of the time courses and to evaluate time-treatment interactions. Second, clinical factors related to the percent changes in GGT and ALT were clarified using multivariate analyses.

RESULTS

GGT levels and FPG values rapidly and significantly decreased via tofogliflozin as early as week 4, with decreases maintained until week 24. Conversely, BW and ALT decreased progressively until week 24. Time courses of FPG (p = .365, time-treatment interaction) and GGT (p = .510) reductions were parallel between tofogliflozin and placebo from weeks 4 to 24, while BW and ALT reductions (p < .001, respectively) were not. Reductions in GGT at week 24 were associated with reductions in FPG and BW at week 24, whereas ALT reductions were only associated with reductions in BW.

CONCLUSIONS

Reductions in GGT and ALT were associated with the anti-hyperglycaemic and anti-obesity effects of tofogliflozin, respectively, in people with T2D. Therefore, GGT and ALT may be surrogate markers for hyperglycaemia and obesity in T2D.

VCD-induced menopause mouse model reveals reprogramming of hepatic metabolism

Menopause adversely impacts systemic energy metabolism and increases the risk of metabolic disease(s) including hepatic steatosis, but the mechanisms are largely unknown. Dosing female mice with vinyl cyclohexene dioxide (VCD) selectively causes follicular atresia in ovaries, leading to a murine menopause-like phenotype. In this study, we treated female C57BL6/J mice with VCD (160mg/kg i.p. for 20 consecutive days followed by verification of the lack of estrous cycling) to investigate changes in body composition, energy expenditure (EE), hepatic mitochondrial function, and hepatic steatosis across different dietary conditions. VCD treatment induced ovarian follicular loss and increased follicle-stimulating hormone (FSH) levels in female mice, mimicking a menopause-like phenotype. VCD treatment did not affect body composition, or EE in mice on a low-fat diet or in response to a short-term (1-week) high-fat, high sucrose diet (HFHS). However, the transition to a HFHS lowered cage activity in VCD mice. A chronic HFHS diet (16 weeks) significantly increased weight gain, fat mass, and hepatic steatosis in VCD-treated mice compared to HFHS-fed controls. In the liver, VCD mice showed suppressed hepatic mitochondrial respiration on LFD, while chronic HFHS diet resulted in compensatory increases in hepatic mitochondrial respiration. Also, liver RNA sequencing revealed that VCD promoted global upregulation of hepatic lipid/cholesterol synthesis pathways. Our findings suggest that the VCD- induced menopause model compromises hepatic mitochondrial function and lipid/cholesterol homeostasis that sets the stage for HFHS diet-induced steatosis while also increasing susceptibility to obesity.

Association between hypoglycemic agent use and the risk of occurrence of nonalcoholic fatty liver disease in patients with type 2 diabetes mellitus

Nonalcoholic fatty liver disease (NAFLD) is a growing health concern with increasing prevalence and associated health impacts. Although no approved drugs are available for the NAFLD treatment, several hypoglycemic agents have been investigated as promising therapeutic agents. We aimed to compare the risk of occurrence of NAFLD with respect to the use of different hypoglycemic agents in patients with type 2 diabetes. This retrospective cohort study used data from the National Health Insurance Service-National Sample Cohort of South Korea. Participants newly diagnosed with type 2 diabetes (2003-2019) were included in this study. Two new user-active comparator cohorts were assembled: Cohort 1, new users of thiazolidinediones (TZD) and dipeptidyl peptidase-4 inhibitors (DPP-4i), and Cohort 2, new users of sodium-glucose cotransporter-2 inhibitors (SGLT-2i) and DPP-4i. The occurrence of NAFLD was defined based claims that include diagnostic codes. Hazard ratios (HRs) and 95% confidence intervals (CIs) were estimated using Cox proportional hazard models in 1:3 propensity score (PS)-matched cohorts. For 65,224 patients newly diagnosed with type 2 diabetes, the overall prevalence of NAFLD was 42.6%. The PS-matched Cohort 1 included 6,351 and 2,117 new users of DPP-4i and TZD, respectively. Compared to DPP-4i, TZD use was associated with the decreased risk of NAFLD (HR, 0.66; 95% CI: 0.55-0.78). Cohort 2 consisted of 6,783 and 2,261 new users of DPP-4i and SGLT-2i, respectively; SGLT-2i use was associated with a decreased risk of NAFLD (HR, 0.93; 95% CI: 0.80-1.08). This population-based cohort study supports the clinical implications of prioritizing TZD and SGLT-2i over DPP-4i in reducing the risk of occurrence of NAFLD in patients with type 2 diabetes. However, the findings lacked statistical significance, highlighting the need for further verification studies.

The Roles of NFR2-Regulated Oxidative Stress and Mitochondrial Quality Control in Chronic Liver Diseases

Chronic liver disease (CLD) affects a significant portion of the global population, leading to a substantial number of deaths each year. Distinct forms like non-alcoholic fatty liver disease (NAFLD) and alcoholic fatty liver disease (ALD), though they have different etiologies, highlight shared pathologies rooted in oxidative stress. Central to liver metabolism, mitochondria are essential for ATP production, gluconeogenesis, fatty acid oxidation, and heme synthesis. However, in diseases like NAFLD, ALD, and liver fibrosis, mitochondrial function is compromised by inflammatory cytokines, hepatotoxins, and metabolic irregularities. This dysfunction, especially electron leakage, exacerbates the production of reactive oxygen species (ROS), augmenting liver damage. Amidst this, nuclear factor erythroid 2-related factor 2 (NRF2) emerges as a cellular protector. It not only counters oxidative stress by regulating antioxidant genes but also maintains mitochondrial health by overseeing autophagy and biogenesis. The synergy between NRF2 modulation and mitochondrial function introduces new therapeutic potentials for CLD, focusing on preserving mitochondrial integrity against oxidative threats. This review delves into the intricate role of oxidative stress in CLD, shedding light on innovative strategies for its prevention and treatment, especially through the modulation of the NRF2 and mitochondrial pathways.

Cellular stress in the pathogenesis of nonalcoholic steatohepatitis and liver fibrosis

The burden of chronic liver disease is rising substantially worldwide. Fibrosis, characterized by excessive deposition of extracellular matrix proteins, is the common pathway leading to cirrhosis, and limited treatment options are available. There is increasing evidence suggesting the role of cellular stress responses contributing to fibrogenesis. This Review provides an overview of studies that analyse the role of cellular stress in different cell types involved in fibrogenesis, including hepatocytes, hepatic stellate cells, liver sinusoidal endothelial cells and macrophages.

Increased GH/IGF-I Axis Activity Relates to Lower Hepatic Lipids and Phosphor Metabolism

CONTEXT

Non-alcoholic fatty liver disease (NAFLD) is a leading causes of liver-related morbidity and mortality. While data on acromegaly, a state of chronic growth hormone (GH)/insulin-like growth factor I (IGF-I) excess, suggest an inverse relationship with intrahepatic lipid (IHL) content, less is known about the impact of the GH/IGF-I axis on IHL, lipid composition, and phosphor metabolites in individuals without disorders of GH secretion.

OBJECTIVE

The aim was to investigate the relation between activity of the GH/IGF-I axis and IHL content and phosphor metabolism.

METHODS

We performed a cross-sectional study in 59 otherwise metabolically healthy individuals (30 females), of which 16 met the criteria of NAFLD with IHL of ≥5.6%. The GH/IGF-I axis was evaluated in a fasting state and during an oral glucose tolerance test (OGTT). Insulin sensitivity was estimated by validated indices. IHL, lipid composition (unsaturation index), and phosphate metabolites were analyzed by using 1H/31P magnetic resonance spectroscopy.

RESULTS

In the overall cohort (40.6 ± 15 years; body mass index: 24.5 ± 3 kg/m2; IGF-I: 68.0 ± 17% upper limit of normal), fasting GH (R = -0.31; P = .02), GH during oral glucose tolerance test (R = -0.51; P < .01), and IGF-I (R = -0.28; P = .03) inversely correlated with IHL. GH levels during OGTT were significantly lower in NAFLD than in controls (47.7 [22; 143] ng/mL/min vs 16.8 [7; 32] ng/mL/min; P = .003). GH/IGF-I axis activity correlated with lipid composition and with phosphor metabolites. In multiple regression analysis, the GH/IGF-I axis activity was a strong predictor for IHL and lipid composition independent from insulin sensitivity.

CONCLUSION

GH/IGF-I axis activity impacts hepatic lipid and phosphate metabolism in individuals without disorders in GH secretion. Lower GH axis activity is associated with higher IHL and an unfavorable lipid composition, probably mediated by changes in hepatic energy metabolism.

Lipid Disorders and Metabolic-Associated Fatty Liver Disease

Dyslipidemia has been linked metabolic-associated fatty liver disease (MAFLD). Several genes and transcription factors involved in lipid metabolism can increase susceptibility to MAFLD. Multiple parallel 'hits' have been proposed for developing hepatic steatosis, NASH, and MAFLD, including insulin resistance and subsequent free fatty acid excess, de novo lipogenesis, and excessive hepatic triglyceride and cholesterol deposition in the liver. This lead to defective beta-oxidation in the mitochondria and VLDL export and increased inflammation. Given the significant cardiovascular risk, dyslipidemia associated with MAFLD should be managed by lifestyle changes and lipid-lowering agents such as statins, fenofibrate, and omega-3 fatty acids, with judicious use of insulin-sensitizing agents, and adequate control of dysglycemia.

Inhibition of GSK3B phosphorylation improves glucose and lipid metabolism disorder

Hepatic glycolipid metabolism disorder is considered as one of the key pathogenic factors for many chronic diseases. Revealing the molecular mechanism of metabolic disorder and exploring drug targets are crucial for the treatment of glucose and lipid metabolic diseases. Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) has been reported to be associated with the pathogenesis of various metabolic diseases. Herein, GAPDH-knockdown ZFL cells and GAPDH-downregulation zebrafish exhibited significant lipid deposition increase and glycogen reduction, thus inducing glucose and lipid metabolism disorders. Using high-sensitivity mass spectrometry-based proteomic and phosphoproteomic analysis, we identified 6838 proteins and 3738 phosphorylated proteins in GAPDH-knockdown ZFL cells. The protein-protein interaction network and DEPPs analyses showed that gsk3ba^Y216 were involved in lipid and glucose metabolism, which was verified by In vitro study. The enzyme activity analysis and cell staining results showed that HepG2 and NCTC-1469 cells transfected with GSK3B^Y216F plasmid had significantly lower glucose and insulin levels, the decreased lipid deposition, and the increased glycogen synthesis than those transfected with GSK3B^Y216E plasmid, suggesting that inhibition of GSK3B phosphorylation could significantly improve GSK3B hyperphosphorylation-induced glucose tolerance impairment and insulin sensitivity reduction. To our knowledge, this is the first multi-omic study of GAPDH-knockdown ZFL cells. This study provides insights into the molecular mechanism of glucose and lipid metabolic disorder, and provides potential targets (kinases) for the treatments of human glucose and lipid metabolic diseases.

Transgenic type2 diabetes mouse models for in vivo redox measurement of hepatic mitochondrial oxidative stress

BACKGROUND

Oxidative stress is involved in the progression of diabetes and its associated complications. However, it is unclear whether increased oxidative stress plays a primary role in the onset of diabetes or is a secondary indicator caused by tissue damage. Previous methods of analyzing oxidative stress have involved measuring the changes in oxidative stress biomarkers. Our aim is to identify a novel approach to clarify whether oxidative stress plays a primary role in the onset of diabetes.

METHODS

We constructed transgenic type 2 diabetes mouse models expressing redox-sensitive green fluorescent proteins (roGFPs) that distinguished between mitochondria and whole cells. Pancreas, liver, skeletal muscle, and kidney redox states were measured in vivo.

RESULTS

Hepatic mitochondrial oxidation increased when the mice were 4 weeks old and continued to increase in an age-dependent manner. The increase in hepatic mitochondrial oxidation occurred simultaneously with weight gain and increased blood insulin levels before the blood glucose levels increased. Administering the oxidative stress inducer acetaminophen increased the vulnerability of the liver mitochondria to oxidative stress.

CONCLUSIONS

This study demonstrates that oxidative stress in liver mitochondria in mice begins at the onset of diabetes rather than after the disease has progressed.

GENERAL SIGNIFICANCE

RoGFP-expressing transgenic type 2 diabetes mouse models are effective and convenient tools for measuring hepatic mitochondrial redox statuses in vivo. These models may be used to assess mitochondria-targeting antioxidants and establish the role of oxidative stress in type 2 diabetes.

Serum C1q/TNF-Related Protein 4 Levels are Associated with Nonalcoholic Fatty Liver Disease in Type 2 Diabetic Patients

Introduction: There is a strong bidirectional relationship between nonalcoholic fatty liver disease (NAFLD) and type 2 diabetes mellitus (T2DM), both of which can lead to an increase in harmful metabolism and cardiovascular risk. It was discovered that C1q/TNF-related protein 4 (CTRP4) regulates glucolipid metabolism and feeding behavior. However, the correlation between serum CTRP4 and NAFLD in T2DM patients is not yet fully understood. Methods: This study enrolled 188 T2DM participants who were separated into 2 distinct groups (NAFLD and non-NAFLD) according to abdominal ultrasound imaging results. The enzyme-linked immunosorbent assay was utilized to evaluate the levels of serum CTRP4. Clinical data and CTRP4 concentration were compared between the two groups. Linear and logistic regression analyses were performed to evaluate the correlation of serum CTRP4 levels with NAFLD risk in T2DM patients. Results: Compared with non-NAFLD, the concentration of CTRP4 was lower in NAFLD group (median 2.46 vs. 2.89, P < 0.001). The log(CTRP4) value was found to be negatively correlated with alanine aminotransferase, aspartate aminotransferase, body mass index (BMI), and waist circumference in a Pearson correlation analyses (r = -0.159, -0.156, -0.224, -0.268, all P < 0.05); besides, the trend χ² test demonstrated that the prevalence of NAFLD rose as CTRP4 concentration decreased (P < 0.001). Regression analysis suggested that NAFLD served as an independent factor influencing log(CTRP4) independently (β-coefficient = -0.12, P = 0.011), even after adjusting for high-sensitivity C-reactive protein and white blood cells. Finally, the results of the logistic regression analysis demonstrated that BMI [odds ratio (OR) = 1.196, P = 0.028], triglyceride (OR = 2.744, P < 0.001), and CTRP4 (OR = 0.615, P = 0.032) were independently associated with NAFLD in T2DM. Conclusions: T2DM patients with NAFLD have lower CTRP4 serum concentrations than those without NAFLD. The risk of NAFLD in patients with T2DM is inversely correlated with serum CTRP4 levels.

Hepatic gene expression profiles during fed-fasted-refed state in mice

Background: Regulation of nutrient status during fasting and refeeding plays an important role in maintaining metabolic homeostasis in the liver. Thus, we investigated the impact of the physiological Fed-Fast-Refed cycle on hepatic gene expression in nutrient-sensitive mice. Methods: We performed transcriptomic analysis of liver samples in fed, fasted and refed groups of mice. Through mRNA-sequencing (RNA-Seq) and miRNA-Seq, we compared fasted and fed states (fasted versus fed cohort) as well as refed and fasted states (refed versus fasted cohort) to detect dynamic alterations of hepatic mRNA-miRNA expression during the fed-fasted-refed cycle. Results: We found dozens of dysregulated mRNAs-miRNAs in the transition from fed to fasted and from fasted to refed states. Gene set enrichment analysis showed that gene expression of the two cohorts shared common pathways of regulation, especially for lipid and protein metabolism. We identified eight significant mRNA and three miRNA clusters that were up-downregulated or down-upregulated during the Fed-Fast-Refed cycle. A protein-protein interaction network of dysregulated mRNAs was constructed and clustered into 22 key modules. The regulation between miRNAs and target mRNAs was presented in a network. Up to 42 miRNA-mRNA-pathway pairs were identified to be involved in metabolism. In lipid metabolism, there were significant correlations between mmu-miR-296-5p and Cyp2u1 and between mmu-miR-novel-chr19_16777 and Acsl3. Conclusion: Collectively, our data provide a valuable resource for the molecular characterization of the physiological Fed-Fast-Refed cycle in the liver.

Succinate dehydrogenase as a new target for melatonin binding in the complex diabetes mellitus treatment

Relevance. Alloxan, destroying the beta cells of the pancreas, provokes hyperglycemia, which causes a hypoenergetic state. Mitochondrial succinate dehydrogenase dysfunction plays an important role in the pathogenesis of diabetes. Pharmacotherapy of diabetes mellitus has been and remains the subject of numerous studies. Recently, the attention of researchers is increasingly attracted by the hormone of the pineal gland - melatonin, due to its biological and pharmacological properties. The aim of the study was to study the effect of melatonin on the activity of succinate dehydrogenase as a new target in experimental alloxan-induced diabetes mellitus. Materials and methods. The studies were carried out on male Wistar rats, with an average mass of 120-150 g, which were kept on a standard diet. The animals were divided into 4 groups. The control group was injected with saline solution, the second group was injected with melatonin at a dose of 1 mg/kg daily for 14 days, experimental diabetes in animals was simulated by intraperitoneal administration of alloxan at a dose of 150 mg/kg with diabetes. The fourth group of animals received melatonin on the background of alloxan. Succinate dehydrogenase activity was determined in liver and pancreatic tissues by photometric method. For the docking analysis, the AutoDock Vina and AutoDock Tools software packages were used. Results and Discussion. According to the results obtained, reciprocal relationships arise under the influence of alloxan in the activity of SDH in the liver and pancreas. Alloxan causes an increase in the activity of SDH in the liver by 1.9 times, and in the pancreatic tissue there is a significant decrease - by 5 times. The use of melatonin for animals with alloxan diabetes led to a decrease in the activity of succinate dehydrogenase in the liver by one and a half times in comparison with the indicators of rats with alloxan diabetes. In the pancreas, on the contrary, the activity of the enzyme increased by 3.3 times, which may indicate the restoration of the function of Langerhans beta cells. Conclusion. Melatonin blocking succinate dehydrogenase domain A reduces the hyperactivity of the enzyme in the liver, and in the pancreas through its specific receptors (MR1 and MR2) present on the surface of the membranes of β- and α-cells directly interferes with the function of the cellular elements of the islets of Langerhans, restoring them.

Mitochondrial transplantation: opportunities and challenges in the treatment of obesity, diabetes, and nonalcoholic fatty liver disease

Metabolic diseases, including obesity, diabetes, and nonalcoholic fatty liver disease (NAFLD), are rising in both incidence and prevalence and remain a major global health and socioeconomic burden in the twenty-first century. Despite an increasing understanding of these diseases, the lack of effective treatments remains an ongoing challenge. Mitochondria are key players in intracellular energy production, calcium homeostasis, signaling, and apoptosis. Emerging evidence shows that mitochondrial dysfunction participates in the pathogeneses of metabolic diseases. Exogenous supplementation with healthy mitochondria is emerging as a promising therapeutic approach to treating these diseases. This article reviews recent advances in the use of mitochondrial transplantation therapy (MRT) in such treatment.

Emerging Role of Hepatic Ketogenesis in Fatty Liver Disease

Non-alcoholic fatty liver disease (NAFLD), the most common chronic liver diseases, arise from non-alcoholic fatty liver (NAFL) characterized by excessive fat accumulation as triglycerides. Although NAFL is benign, it could progress to non-alcoholic steatohepatitis (NASH) manifested with inflammation, hepatocyte damage and fibrosis. A subset of NASH patients develops end-stage liver diseases such as cirrhosis and hepatocellular carcinoma. The pathogenesis of NAFLD is highly complex and strongly associated with perturbations in lipid and glucose metabolism. Lipid disposal pathways, in particular, impairment in condensation of acetyl-CoA derived from β-oxidation into ketogenic pathway strongly influence the hepatic lipid loads and glucose metabolism. Current evidence suggests that ketogenesis dispose up to two-thirds of the lipids entering the liver, and its dysregulation significantly contribute to the NAFLD pathogenesis. Moreover, ketone body administration in mice and humans shows a significant improvement in NAFLD. This review focuses on hepatic ketogenesis and its role in NAFLD pathogenesis. We review the possible mechanisms through which impaired hepatic ketogenesis may promote NAFLD progression. Finally, the review sheds light on the therapeutic implications of a ketogenic diet in NAFLD.

Metabolic associated fatty liver disease is a disease related to sympathetic nervous system activation

Strong evidence from animal and human studies shows that sympathetic nervous system (SNS) activation is a key factor in the development of metabolic associated fatty liver disease (MAFLD). Activation of the sympathetic nervous system plays an important role in the pathogenesis of obesity, metabolic syndrome, diabetes, hypertension, and MAFLD. When genetically susceptible subjects are exposed to a variety of epigenetic changes, their liver damage may develop into MAFLD. Thus, the pathogenesis of MAFLD is complex, involving the complex interaction of insulin resistance, abnormal hormone secretion, obesity, diet, genetic factors, immune activation, gut microbiota, and other factors. In these processes, the role of sympathetic nerves cannot be underestimated. Notably, SNS has been proposed as a therapeutic target for MAFLD by inhibiting sympathetic nerves. It is worthy of further discussion and research.

The role of mitochondria in the pathophysiology and treatment of common metabolic diseases in humans

Common metabolic diseases such as obesity, type 2 diabetes mellitus and non-alcoholic fatty liver disease significantly contribute to morbidity and mortality worldwide. They frequently associate with insulin resistance and altered mitochondrial functionality. Insulin-responsive tissues can show changes in mitochondrial features such as oxidative capacity, mitochondrial content and turnover, which do not necessarily reflect abnormalities but rather adaption to a certain metabolic condition. Lifestyle modifications and classic or novel drugs can modify these alterations and help treating these metabolic diseases. This review addresses the role of mitochondria in human metabolic diseases and discusses potential future research directions.

Substitution of Sugar-Sweetened Beverages for Other Beverages: Can It Be the Next Step Towards Healthy Aging?

PURPOSE OF REVIEW

With the prolongation of life expectancy, the gap between lifespan and "health span," the disease-free lifespan, has been widening due to the massive burden of age-related chronic diseases and research on healthy aging has been gaining momentum. A growing body of evidence suggests that diet is a strong determinant of healthy aging and consumption of sugar-sweetened beverages (SSB), a major source of added sugars, predicts poor health outcomes in the aging population, including cardiovascular disease, diabetes, and cancer. Evidence further supports a link between sugar-sweetened beverages-triggered pathological processes and biologic factors of aging, including inflammaging, oxidative stress, and alterations in intestinal microbiota. At present, substitution of sugar-sweetened beverages with healthier alternative beverage remains the most robust strategy to limit the deleterious effects of sugar-sweetened beverages on health worldwide and may help achieve healthy longevity. The purpose of this review is to provide an overview of mechanisms by which sugar-sweetened beverages consumption may impact the physiological aging process and how a simple intervention of beverage replacement may promote healthy aging.

RECENT FINDINGS

Recent findings indicate that SSB are associated with accelerated aging phenotype and activate various adverse biological processes such as chronic inflammation, oxidative stress, insulin resistance, and gut dysbiosis. Replacing SSB with healthier beverages may be a reasonable option to reduce the burden of chronic disease in the aging population and even prolong life and healthspan.

Development of a Multivariable Prediction Model for Citrate Accumulation in Liver Transplant Patients Undergoing Continuous Renal Replacement Therapy with Regional Citrate Anticoagulation

INTRODUCTION

Patients with impaired citrate metabolism may experience citrate accumulation (CA), which causes life-threatening metabolic acidosis and hypocalcemia. CA poses a challenge for clinicians when deciding on the use of regional citrate anticoagulation (RCA) for patients with liver dysfunction. This study aimed to develop a prediction model integrating multiple clinical variables to assess the risk of CA in liver transplant patients.

METHODS

This single-center prospective cohort study included postoperative liver transplant patients who underwent continuous renal replacement therapy (CRRT) with RCA. The study end point was CA. A prediction model was developed using a generalized linear mixed-effect model based on the Akaike information criterion. The predictive values were assessed using the receiver operating characteristic curve and bootstrap resampling (times = 500) to estimate the area under the curve (AUC) and the corresponding 95% confidence interval (CI). A nomogram was used to visualize the model.

RESULTS

This study included 32 patients who underwent 133 CRRT sessions with RCA. CA occurred in 46 CRRT sessions. The model included lactate, norepinephrine >0.1 μg/kg/min, alanine aminotransferase, total bilirubin, and standard bicarbonate, which were tested before starting each CRRT session and body mass index, diabetes mellitus, and chronic kidney disease as predictors. The AUC of the model was 0.867 (95% CI 0.786-0.921), which was significantly higher than that of the single predictor (p < 0.05). A nomogram visualized the prediction model.

CONCLUSIONS

The prediction model integrating multiple clinical variables showed a good predictive value for CA. A nomogram visualized the model for easy application in clinical practice.

Early changes in hepatic energy metabolism and lipid content in recent-onset type 1 and 2 diabetes mellitus

BACKGROUND & AIMS

Non-alcoholic fatty liver disease (NAFLD) is associated with abnormal mitochondrial capacity. While oxidative capacity can be increased in steatosis, hepatic ATP decreases in long-standing diabetes. However, longitudinal studies on diabetes-related NAFLD and its relationship to hepatic energy metabolism are lacking.

METHODS

This prospective study comprised volunteers with type 1 (T1DM, n = 30) and type 2 (T2DM, n = 37) diabetes. At diagnosis and 5 years later, we used ¹H/³¹P magnetic resonance spectroscopy to measure hepatocellular lipid (HCL), γATP and inorganic phosphate (Pi) concentrations, and to assess adipose tissue volumes. Insulin sensitivity was assessed by hyperinsulinemic-euglycemic clamps.

RESULTS

At diagnosis, individuals with T2DM had higher HCL and adipose tissue volumes, but lower whole-body insulin sensitivity than those with T1DM, despite comparable glycemic control. NAFLD was present in 38% of individuals with T2DM and 7% with T1DM. After 5 years, visceral adipose tissue only increased in individuals with T2DM, while HCL almost doubled in this group (p <0.001), resulting in a 70% prevalence of NAFLD (independent of diabetes treatment). Changes in HCL correlated with adipose tissue volume and insulin resistance (r = 0.50 and r = 0.44, both p <0.05). Pi decreased by 17% and 10% in individuals with T2DM and T1DM (p <0.05), respectively. In T1DM, HCL did not change, whereas γATP decreased by 10% and correlated negatively with glycated hemoglobin (r = -0.56, p <0.05).

CONCLUSIONS

The rapid increase in HCL during the early course of T2DM likely results from enlarging adipose tissue volume and insulin resistance in response to impaired hepatic mitochondrial adaptation. The decrease of phosphorus metabolites in T1DM may be due to pharmacological insulin supply.

LAY SUMMARY

Previous studies suggested that the impaired function of mitochondria, the power plants of cells, can promote fatty liver and type 2 diabetes mellitus. This study now shows that during the first 5 years of type 2 diabetes the increase in body fat content rapidly leads to a doubling of liver fat content, whereas the energy metabolism of the patients' livers progressively declines. These data suggest that fat tissue mass and liver mitochondria have an important role in the development of fatty liver disease in humans with diabetes.

CLINICAL TRIAL NUMBER

NCT01055093.

Metabolic Dysfunction-Associated Fatty Liver Disease (MAFLD)-A Condition Associated with Heightened Sympathetic Activation

Metabolic dysfunction-associated fatty liver disease (MAFLD) is the most common liver disease affecting a quarter of the global population and is often associated with adverse health outcomes. The increasing prevalence of MAFLD occurs in parallel to that of metabolic syndrome (MetS), which in fact plays a major role in driving the perturbations of cardiometabolic homeostasis. However, the mechanisms underpinning the pathogenesis of MAFLD are incompletely understood. Compelling evidence from animal and human studies suggest that heightened activation of the sympathetic nervous system is a key contributor to the development of MAFLD. Indeed, common treatment strategies for metabolic diseases such as diet and exercise to induce weight loss have been shown to exert their beneficial effects at least in part through the associated sympathetic inhibition. Furthermore, pharmacological and device-based approaches to reduce sympathetic activation have been demonstrated to improve the metabolic alterations frequently present in patients with obesity, MetSand diabetes. Currently available evidence, while still limited, suggests that sympathetic activation is of specific relevance in the pathogenesis of MAFLD and consequentially may offer an attractive therapeutic target to attenuate the adverse outcomes associated with MAFLD.

Role of the sympathetic nervous system in cardiometabolic control: implications for targeted multiorgan neuromodulation approaches

Sympathetic overdrive plays a key role in the perturbation of cardiometabolic homeostasis. Diet-induced and exercise-induced weight loss remains a key strategy to combat metabolic disorders, but is often difficult to achieve. Current pharmacological approaches result in variable responses in different patient cohorts and long-term efficacy may be limited by medication intolerance and nonadherence. A clinical need exists for complementary therapies to curb the burden of cardiometabolic diseases. One such approach may include interventional sympathetic neuromodulation of organs relevant to cardiometabolic control. The experience from catheter-based renal denervation studies clearly demonstrates the feasibility, safety and efficacy of such an approach. In analogy, denervation of the common hepatic artery is now feasible in humans and may prove to be similarly useful in modulating sympathetic overdrive directed towards the liver, pancreas and duodenum. Such a targeted multiorgan neuromodulation strategy may beneficially influence multiple aspects of the cardiometabolic disease continuum offering a holistic approach.

Disruption of fertility, placenta, pregnancy outcome, and multigenerational inheritance of hepatic steatosis by organotin exposure from contaminated seafood in rats

Early life exposure to endocrine-disrupting chemicals (EDCs) is an emerging risk factor for development of complications later in life and in subsequent generations. We previously demonstrated that exposure to the EDC organotin (OT), which is present in contaminated seafood, resulted in reproductive abnormalities in female rats. However, few studies have explored the effect of OT accumulation in seafood on pregnancy outcomes. This led us to consider the potential effects of the OT present in seafood on fertility, pregnancy, the placenta, and the offspring. In this investigation, we assessed whether exposure to the OT in contaminated seafood resulted in abnormal fertility and pregnancy features and offspring complications. OT in contaminated seafood (LNI) was administered to female rats, and their fertility, pregnancy outcomes, and fetal liver morphology were assessed. LNI caused abnormal fertility, a reduction in the total number of pups, and an increase in serum testosterone levels compared to controls. Furthermore, LNI exposure caused irregular uterine morphology with inflammation and fibrosis and led to a reduction in embryonic implantation. In pregnant rats, LNI caused abnormal lipid profiles and livers with steatosis features. LNI exposure also causes placental morpho-physiology disruption, a high presence of glycogen and inflammatory cells, and irregular lipid profiles. In addition, LNI exposure caused an increase in large amounts of carbohydrate and lipid delivery to the fetus via an increase in placental nutrient sensor protein expressions (GLUT1, IRβ/mTOR and Akt). In both genders of offspring, LNI exposure led to an increase in body weights, liver megakaryocytes, lipid accumulation, and oxidative stress (OS) levels. Collectively, these data suggest that OT exposure from contaminated seafood in female rats leads to reduced fertility, uterine implantation failure, pregnancy and placental metabolic outcome irregularities, offspring adiposity, liver steatosis, and an increase in OS. Furthermore, some of the effects of OT may be the result of obesogenic and multigenerational effects of OT in adult female rats.

Alternate-day fasting alleviates diabetes-induced glycolipid metabolism disorders: roles of FGF21 and bile acids

Glycolipid metabolism disorder is one of the causes of type 2 diabetes (T2D). Alternate-day fasting (ADF) is an effective dietary intervention to counteract T2D. The present study is aimed to determine the underlying mechanisms of the benefits of ADF metabolic on diabetes-induced glycolipid metabolism disorders in db/db mice. Here, leptin receptor knock-out diabetic mice were subjected to 28 days of isocaloric ADF. We found that ADF prevented insulin resistance and bodyweight gain in diabetic mice. ADF promoted glycogen synthesis in both liver and muscle. ADF also activated recombinant insulin receptor substrate-1 (IRS-1)/protein kinase B (AKT/PKB) signaling，inactivated inflammation related AMP-activated protein kinase (AMPK) and the inflammation-regulating nuclear factor kappa-B (NF-κB) signaling in the liver. ADF also suppressed lipid accumulation by inactivating the expression of peroxisome proliferator-activated receptor gamma (PPAR-γ) and sterol regulatory element-binding protein-1c (SREBP-1c). Furthermore, ADF elevated the expression of fibroblast growth factor 21 (FGF21) and down-stream signaling AMPK/silent mating type information regulation 2 homolog 1 (SIRT1)/peroxisome proliferator-activated receptor gamma coactivator-1 alpha (PGC-1α) in the liver of diabetic mice. The mitochondrial biogenesis and autophagy were also stimulated by ADF. Interestingly, ADF also enhanced the bile acids (BAs) metabolism by generating more cholic acid (CA), deoxycholic acid (DCA) and tauroursodeoxycholic acid (TUDCA) in db/db mice. In conclusion, ADF could significantly inhibit T2D induced insulin resistance and obesity, promote insulin signaling，reduce inflammation, as well as promote glycogen synthesis and lipid metabolism. It possibly depends on FGF21 and BA metabolism to enhance mitochondrial biosynthesis and energy metabolism.

Increased ATP synthesis might counteract hepatic lipid accumulation in acromegaly

Patients with active acromegaly (ACRO) exhibit low hepatocellular lipids (HCL), despite pronounced insulin resistance (IR). This contrasts the strong association of IR with nonalcoholic fatty liver disease in the general population. Since low HCL levels in ACRO might be caused by changes in oxidative substrate metabolism, we investigated mitochondrial activity and plasma metabolomics/lipidomics in active ACRO. Fifteen subjects with ACRO and seventeen healthy controls, matched for age, BMI, sex, and body composition, underwent 31P/1H-7-T MR spectroscopy of the liver and skeletal muscle as well as plasma metabolomic profiling and an oral glucose tolerance test. Subjects with ACRO showed significantly lower HCL levels, but the ATP synthesis rate was significantly increased compared with that in controls. Furthermore, a decreased ratio of unsaturated-to-saturated intrahepatocellular fatty acids was found in subjects with ACRO. Within assessed plasma lipids, lipidomics, and metabolomics, decreased carnitine species also indicated increased mitochondrial activity. We therefore concluded that excess of growth hormone (GH) in humans counteracts HCL accumulation by increased hepatic ATP synthesis. This was accompanied by a decreased ratio of unsaturated-to-saturated lipids in hepatocytes and by a metabolomic profile, reflecting the increase in mitochondrial activity. Thus, these findings help to better understanding of GH-regulated antisteatotic pathways and provide a better insight into potentially novel therapeutic targets for treating NAFLD.

Sarcodon aspratus polysaccharides ameliorated obesity-induced metabolic disorders and modulated gut microbiota dysbiosis in mice fed a high-fat diet

The polysaccharides isolated from the fruit body of S. aspratus (SATPs) might be a potential health supplement or prebiotic in the prevention of obesity and associated metabolic disorders.

Fat and Sugar-A Dangerous Duet. A Comparative Review on Metabolic Remodeling in Rodent Models of Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD) is a common disease in Western society and ranges from steatosis to steatohepatitis to end-stage liver disease such as cirrhosis and hepatocellular carcinoma. The molecular mechanisms that are involved in the progression of steatosis to more severe liver damage in patients are not fully understood. A deeper investigation of NAFLD pathogenesis is possible due to the many different animal models developed recently. In this review, we present a comparative overview of the most common dietary NAFLD rodent models with respect to their metabolic phenotype and morphological manifestation. Moreover, we describe similarities and controversies concerning the effect of NAFLD-inducing diets on mitochondria as well as mitochondria-derived oxidative stress in the progression of NAFLD.

Metabolic Comorbidities and Risk of Development and Severity of Drug-Induced Liver Injury

The incidence and rates of diagnosis of drug-induced liver injury (DILI) have been increasing in recent years as findings from basic research and the examination of clinical databases reveal information about the clinical course, etiology, and prognosis of this complex disease. The prevalence of metabolic comorbidities (e.g., diabetes mellitus, fatty liver, obesity, and metabolic syndrome (MetS)) has been increasing during the same period. The results of preclinical and clinical research studies indicate that characteristics of metabolic comorbidities are also factors that affect DILI phenotype and progression. The objective of this review is to present the evidence for DILI and hepatotoxicity mechanisms, incidence, and outcomes in patients with MetS and nonalcoholic fatty liver disease. Moreover, we also summarize the relationships between drugs used to treat metabolic comorbidities and DILI.

Prospective association between added sugars and frailty in older adults

Background

Sugar-sweetened beverages and added sugars (monosaccharides and disaccharides) in the diet are associated with obesity, diabetes, and cardiovascular disease, which are all risk factors for decline in physical function among older adults.

Objective

The aim of this study was to examine the association between added sugars in the diet and incidence of frailty in older people.

Design

Data were taken from 1973 Spanish adults ≥60 y old from the Seniors-ENRICA cohort. In 2008-2010 (baseline), consumption of added sugars (including those in fruit juices) was obtained using a validated diet history. Study participants were followed up until 2012-2013 to assess frailty based on Fried's criteria. Statistical analyses were performed with logistic regression adjusted for age, sex, education, smoking status, body mass index, energy intake, self-reported comorbidities, Mediterranean Diet Adherence Score (excluding sweetened drinks and pastries), TV watching time, and leisure-time physical activity.

Results

Compared with participants consuming <15 g/d added sugars (lowest tertile), those consuming ≥36 g/d (highest tertile) were more likely to develop frailty (OR: 2.27; 95% CI: 1.34, 3.90; P-trend = 0.003). The frailty components "low physical activity" and "unintentional weight loss" increased dose dependently with added sugars. Association with frailty was strongest for sugars added during food production. Intake of sugars naturally appearing in foods was not associated with frailty.

Conclusions

The consumption of added sugars in the diet of older people was associated with frailty, mainly when present in processed foods. The frailty components that were most closely associated with added sugars were low level of physical activity and unintentional weight loss. Future research should determine whether there is a causal relation between added sugars and frailty.

A simple method to monitor hepatic gluconeogenesis and triglyceride synthesis following oral sugar tolerance test in obese adolescents

Hepatic energy metabolism is a key element in many metabolic diseases. Hepatic anaplerosis provides carbons for gluconeogenesis (GNG) and triglyceride (TG) synthesis. We aimed to optimize a protocol that measures hepatic anaplerotic contribution for GNG, TG synthesis, and hepatic pentose phosphate pathway (PPP) activity using a single dose of oral [U^-13C₃]glycerol paired with an oral sugar tolerance test (OSTT) in a population with significant insulin resistance. The OSTT (75 g glucose + 25 g fructose) was administered to eight obese adolescents with polycystic ovarian syndrome (PCOS) followed by ingestion of [U-¹³C₃]glycerol at t = 180 or t = 210 min. ¹³C-labeling patterns of serum glucose and TG-glycerol were determined by nuclear magnetic resonance. ¹³C enrichment in plasma TG-glycerol was detectable and stable from 240 to 390 min with the [U-¹³C₃]glycerol drink at t = 180 min(3.65 ± 2.3 to 4.47 ± 1.4%; P > 0.4), but the enrichment was undetectable at 240 min with the glycerol drink at t = 210 min. The relative contribution from anaplerosis was determined at the end of the OSTT [18.5 ±3.4% (t = 180 min) vs. 16.0 ± 3.5% (t = 210 min); P = 0.27]. [U-¹³C₃]glycerol was incorporated into GNG 390 min after the OSTT with an enrichment of 7.5-12.5%. Glucose derived from TCA cycle activity was 0.3-1%, and the PPP activity was 2.8-4.7%. In conclusion, it is possible to obtain relative measurements of hepatic anaplerotic contribution to both GNG and TG esterification following an OSTT in a highly insulin-resistant population using a minimally invasive technique. Tracer administration should be timed to allow enough de novo TG esterification and endogenous glucose release after the sugar drink.

Hepatic protein Carbonylation profiles induced by lipid accumulation and oxidative stress for investigating cellular response to non-alcoholic fatty liver disease in vitro

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) is caused by excessive accumulation of fat within the liver, leading to further severe conditions such as non-alcoholic steatohepatitis (NASH). Progression of healthy liver to steatosis and NASH is not yet fully understood in terms of process and response. Hepatic oxidative stress is believed to be one of the factors driving steatosis to NASH. Oxidative protein modification is the major cause of protein functional impairment in which alteration of key hepatic enzymes is likely to be a crucial factor for NAFLD biology. In the present study, we aimed to discover carbonylated protein profiles involving in NAFLD biology in vitro.

METHODS

Hepatocyte cell line was used to induce steatosis with fatty acids (FA) in the presence and absence of menadione (oxidative stress inducer). Two-dimensional gel electrophoresis-based proteomics and dinitrophenyl hydrazine derivatization technique were used to identify carbonylated proteins. Sequentially, in order to view changes in protein carbonylation pathway, enrichment using Funrich algorithm was performed. The selected carbonylated proteins were validated with western blot and carbonylated sites were further identified by high-resolution LC-MS/MS.

RESULTS

Proteomic results and pathway analysis revealed that carbonylated proteins are involved in NASH pathogenesis pathways in which most of them play important roles in energy metabolisms. Particularly, carbonylation level of ATP synthase subunit α (ATP5A), a key protein in cellular respiration, was reduced after FA and FA with oxidative stress treatment, whereas its expression was not altered. Carbonylated sites on this protein were identified and it was revealed that these sites are located in nucleotide binding region. Modification of these sites may, therefore, disturb ATP5A activity. As a consequence, the lower carbonylation level on ATP5A after FA treatment solely or with oxidative stress can increase ATP production.

CONCLUSIONS

The reduction in carbonylated level of ATP5A might occur to generate more energy in response to pathological conditions, in our case, fat accumulation and oxidative stress in hepatocytes. This would imply the association between protein carbonylation and molecular response to development of steatosis and NASH.

Innate immune regulatory networks in hepatic lipid metabolism

Hepatic lipid metabolism is closely associated with certain diseases, such as obesity, diabetes, fatty liver, and hepatic fibrosis. Hepatic steatosis results from systemic metabolic dysfunction that occurs via multiple processes. The initial process has been characterized as hepatic lipid accumulation that may be caused by increased liver lipid uptake and de novo lipogenesis or decreased lipid oxidation and lipid export; subsequently, multiple additional factors that trigger inflammation and insulin resistance (IR) aggravate the progression of hepatic steatosis. Emerging evidence indicates that inflammation stands at the crossroads of innate immunity and lipid metabolism and links the initial metabolic stress and subsequent metabolic events in lipid metabolism. Therefore, in this review, we summarize the regulatory role of innate immune signaling molecules in maintaining lipid metabolic homeostasis; these revelations can guide the development of potential therapies for nonalcoholic fatty liver disease (NAFLD).

Investigating the Role of Mitochondria in Type 2 Diabetes - Lessons from Lipidomics and Proteomics Studies of Skeletal Muscle and Liver

Mitochondrial dysfunction is discussed as a key player in the pathogenesis of type 2 diabetes mellitus (T2Dm), a highly prevalent disease rapidly developing as one of the greatest global health challenges of this century. Data however about the involvement of mitochondria, central hubs in bioenergetic processes, in the disease development are still controversial. Lipid and protein homeostasis are under intense discussion to be crucial for proper mitochondrial function. Consequently proteomics and lipidomics analyses might help to understand how molecular changes in mitochondria translate to alterations in energy transduction as observed in the healthy and metabolic diseases such as T2Dm and other related disorders. Mitochondrial lipids integrated in a tool covering proteomic and functional analyses were up to now rarely investigated, although mitochondrial lipids might provide a possible lynchpin in the understanding of type 2 diabetes development and thereby prevention. In this chapter state-of-the-art analytical strategies, pre-analytical aspects, potential pitfalls as well as current proteomics and lipidomics-based knowledge about the pathophysiological role of mitochondria in the pathogenesis of type 2 diabetes will be discussed.

A mix of dietary fermentable fibers improves lipids handling by the liver of overfed minipigs

Obesity induced by overfeeding ultimately can lead to nonalcoholic fatty liver disease, whereas dietary fiber consumption is known to have a beneficial effect. We aimed to determine if a supplementation of a mix of fibers (inulin, resistant starch and pectin) could limit or alleviate overfeeding-induced metabolic perturbations. Twenty female minipigs were fed with a control diet (C) or an enriched fat/sucrose diet supplemented (O + F) or not (O) with fibers. Between 0 and 56 days of overfeeding, insulin (+88%), HOMA (+102%), cholesterol (+45%) and lactate (+63%) were increased, without any beneficial effect of fibers supplementation. However, fibers supplementation limited body weight gain (vs. O, -15% at D56) and the accumulation of hepatic lipids droplets induced by overfeeding. This could be explained by a decreased lipids transport potential (-50% FABP1 mRNA, O + F vs. O) inducing a down-regulation of regulatory elements of lipids metabolism / lipogenesis (-36% SREBP1c mRNA, O + F vs. O) but not to an increased oxidation (O + F not different from O and C for proteins and mRNA measured). Glucose metabolism was also differentially regulated by fibers supplementation, with an increased net hepatic release of glucose in the fasted state (diet × time effect, P<.05 at D56) that can be explained partially by a possible increased glycogen synthesis in the fed state (+82% GYS2 protein, O + F vs. O, P=.09). The direct role of short chain fatty acids on gluconeogenesis stimulation is questioned, with probably a short-term impact (D14) but no effect on a long-term (D56) basis.

miR-125a-5p ameliorates hepatic glycolipid metabolism disorder in type 2 diabetes mellitus through targeting of STAT3

Glycolipid metabolic disorder is an important cause for the development of type 2 diabetes mellitus (T2DM). Clarification of the molecular mechanism of metabolic disorder and exploration of drug targets are crucial for the treatment of T2DM.

Methods: We examined miR-125a-5p levels in palmitic acid-induced AML12 cells and the livers of type 2 diabetic rats and mice, and then validated its target gene. Through gain- and loss-of-function studies, the effects of miR-125a-5p via targeting of STAT3 on regulating glycolipid metabolism were further illustrated in vitro and in vivo.

Results: We found that miR-125a-5p was significantly decreased in the livers of diabetic mice and rats, and STAT3 was identified as the target gene of miR-125a-5p. Overexpression of miR-125a-5p in C57BL/6 mice decreased STAT3 level and downregulated the expression levels of p-STAT3 and SOCS3. Consequently, SREBP-1c-mediated lipogenesis pathway was inhibited, and PI3K/AKT pathway was activated. Moreover, silencing of miR-125a-5p significantly increased the expression levels of STAT3, p-STAT3 and SOCS3, thus activating SREBP-1c pathway and suppressing PI3K/AKT pathway. Therefore, hyperglycemia, hyperlipidemia and decreased liver glycogen appeared in C57BL/6 mice. In palmitic acid-induced AML12 cells, miR-125a-5p mimic markedly increased glucose consumption and uptake and decreased the accumulation of lipid droplets by regulating STAT3 signaling pathway. Consistently, miR-125a-5p overexpression obviously inhibited STAT3 expression in diabetic KK-Ay mice, thereby decreasing blood glucose and lipid levels, increasing hepatic glycogen content, and decreasing accumulation of hepatic lipid droplets in diabetic mice. Furthermore, inhibition of miR-125a-5p in KK-Ay mice aggravated glycolipid metabolism dysfunction through regulating STAT3.

Conclusions: Our results confirmed that miR-125a-5p should be considered as a regulator of glycolipid metabolism in T2DM, which can inhibit hepatic lipogenesis and gluconeogenesis and elevate glycogen synthesis by targeting STAT3.

Adaptations of hepatic lipid metabolism and mitochondria in dairy cows with mild fatty liver

The inevitable deficiency in nutrients and energy at the onset of lactation requires an optimal adaptation of the hepatic metabolism to overcome metabolic stress. Fatty liver is one of the main health disorders after parturition. Therefore, to investigate changes in hepatic lipid metabolic status and mitochondria in dairy cows with mild fatty liver, liver and blood samples were collected from healthy cows (n = 15) and cows with mild fatty liver (n = 15). To determine the effects of palmitic acids (PA), one of the major component of fatty acids, on lipid metabolism and mitochondria in vitro, calf hepatocytes were isolated from healthy calves and treated with various concentrations of PA (0, 50, 100, and 200 μM). Dairy cows with mild fatty liver displayed hepatic lipid accumulation. The protein levels of sterol regulatory element-binding protein 1c (SREBP-1c) and peroxisome proliferator-activated receptor-α (PPARα) and mRNA levels of acetyl CoA carboxylase 1 (ACC1), fatty acid synthase (FAS), acyl-CoA oxidase (ACO), and carnitine palmitoyltransferase 1A (CPT1A) were significantly higher in dairy cows with mild fatty liver than in control cows. The hepatic mitochondrial DNA content, mRNA levels of oxidative phosphorylation complexes I to V (CO 1-V), protein levels of cytochrome c oxidase subunit IV (COX IV), voltage dependent anion channel 1 (VDAC1), peroxisome proliferator activated receptor-γ coactivator-1α (PGC-1α) and nuclear respiratory factor 1 (NRF1), and adenosine triphosphate (ATP) content were all markedly increased in the liver of dairy cows with mild fatty liver compared with healthy cows. The PA treatment significantly increased lipid accumulation; protein levels of SREBP-1c and PPARα; and mRNA levels of ACC1, FAS, ACO, and CPT1A in calf hepatocytes. Moreover, the mitochondrial DNA content, mRNA levels of CO 1-V, protein levels of COX IV, VDAC1, PGC-1α, NRF1, mitochondrial transcription factor A, and ATP content were significantly increased in PA-treated hepatocytes compared with control hepatocytes. The protein level of mitofusin-2 was significantly decreased in PA-treated groups. In conclusion, lipid synthesis and oxidation, number of mitochondria, and ATP production were increased in the liver of dairy cows with mild fatty liver and PA-treated calf hepatocytes. These changes in hepatic mitochondria and lipid metabolism may be the adaptive mechanism of dairy cows with mild fatty liver.

Meal-derived glucagon responses are related to lower hepatic phosphate concentrations in obesity and type 2 diabetes

AIM

Type 2 diabetes (T2D) alters glucagon, glucagon-like peptide (GLP)-1, glucose-dependent insulinotropic polypeptide (GIP) and hepatic energy metabolism, yet the possible relationships remain unclear.

METHODS

In this observational study, lean insulin-sensitive control subjects (BMI: 23.2±1.5kg/m²), age-matched insulin-resistant obese subjects (BMI: 34.3±1.7kg/m²) and similarly obese elderly T2D patients (BMI: 32.0±2.4kg/m²) underwent mixed-meal tolerance tests (MMTTs), and assessment of hepatic γATP, inorganic phosphate (P_i) and lipids using ³¹P/¹H magnetic resonance spectroscopy. Meal-induced secretion of glucagon and incretins was calculated from incremental areas under the concentration-time curves (iAUCs). Peripheral and adipose tissue insulin sensitivity were assessed from time courses of circulating glucose, insulin and free fatty acids.

RESULTS

MMTT-derived peripheral insulin sensitivity was lowest in T2D patients (P<0.001), while glucagon concentrations were comparable across all three groups. At 260min, GLP-1 was lower in T2D patients than in controls, whereas GIP was lowest in obese individuals. Fasting glucagon concentrations correlated positively with fasting (r=0.60) and postprandial hepatocellular lipid levels (160min: r=0.51, 240min: r=0.59), and negatively with adipose tissue insulin sensitivity (r=-0.73). Higher meal-induced glucagon release (iAUC_0-260min) correlated with lower fasting (r=-0.62) and postprandial P_i levels (160min: r=-0.43, 240min: r=-0.42; all P<0.05). Higher meal-induced release of GIP (iAUC_0-260min) correlated positively with fasting (r=0.54) and postprandial serum triglyceride concentrations (iAUC_0-260min, r=0.54; all P<0.01).

CONCLUSION

Correlations between fasting glucagon and hepatic lipids and between meal-induced glucagon and hepatic P_i suggest a role for glucagon in hepatic energy metabolism.

Challenges in diagnosing and monitoring diabetes in patients with chronic liver diseases

The prevalence and mortality of diabetes mellitus and liver disease have risen in recent years. The liver plays an important role in glucose homeostasis, and various chronic liver diseases have a negative effect on glucose metabolism with the consequent emergence of diabetes. Some aspects related to chronic liver disease can affect diagnostic tools and the monitoring of diabetes and other glucose metabolism disorders, and clinicians must be aware of these limitations in their daily practice. In cirrhotic patients, fasting glucose may be normal in up until 23% of diabetes cases, and glycated hemoglobin provides falsely low results, especially in advanced cirrhosis. Similarly, the performance of alternative glucose monitoring tests, such as fructosamine, glycated albumin and 1,5-anhydroglucitol, also appears to be suboptimal in chronic liver disease. This review will examine the association between changes in glucose metabolism and various liver diseases as well as the particularities associated with the diagnosis and monitoring of diabetes in liver disease patients. Alternatives to routinely recommended tests will be discussed.