Insulin resistance and reduced metabolic flexibility: cause or consequence of NAFLD?

Forkhead box O1 in metabolic dysfunction-associated fatty liver disease: molecular mechanisms and drug research

Metabolic dysfunction-associated fatty liver disease (MAFLD) is a chronic liver disease that progresses from hepatic steatosis to non-alcoholic steatohepatitis, cirrhosis, and liver cancer, posing a huge burden on human health. Existing research has confirmed that forkhead box O1 (FOXO1), as a member of the FOXO transcription factor family, is upregulated in MAFLD. Its activity is closely related to nuclear-cytoplasmic shuttling and various post-translational modifications including phosphorylation, acetylation, and methylation. FOXO1 mediates the progression of MAFLD by regulating glucose metabolism, lipid metabolism, insulin resistance, oxidative stress, hepatic fibrosis, hepatocyte autophagy, apoptosis, and immune inflammation. This article elaborates on the regulatory role of FOXO1 in MAFLD, providing a summary and new insights for the current status of drug research and targeted therapies for MAFLD.

The roles of type 2 diabetes and obesity in disease activity and progression of non-alcoholic fatty liver disease/non-alcoholic steatohepatitis

OBJECTIVE

We examined the roles of type 2 diabetes (T2D) and obesity in disease activity and fibrosis progression/regression in patients with non-alcoholic fatty liver disease/non-alcoholic steatohepatitis (NAFLD/NASH).

METHODS

This multi-center, retrospective study included patients with suspected or histologically proven NAFLD/NASH from the NASH Clinical Research Network. Outcomes included disease activity and rate of fibrosis, assessed using liver-biopsy driven measures (NAFLD activity score [NAS] and fibrosis score [FS]). Logistic regression and doubly robu estimation of causal effects tested relationships among T2D, obesity, and NAFLD/NASH.

RESULTS

The analytical sample included 870 adult patients with baseline biopsy data and 157 patients with multiple biopsy data. Patients with NAFLD/NASH and T2D had significantly higher baseline average NAS (4.52 vs. 4.13; p = 0.009) and FS (2.17 vs. 1.56; p < 0.0001); those with T2D had a significantly greater reduction in average NAS over time (-0.77/year vs. -0.17/year; p = 0.0008). Change in FS over time did not differ significantly by T2D status (-0.23/year vs. -0.04/year; p = 0.34). Baseline NAS, baseline FS, and change in average NAS over time did not differ significantly by obesity status (4.17 vs. 4.47; p = 0.16; 1.73 vs.1.92; p = 0.31; -0.40/year vs. -0.59/year; p = 0.62, respectively). Patients with obesity had a slight increase in FS but those without obesity had a reduction in average FS over time (0.07/year vs. -0.27/year; p = 0.008).

CONCLUSIONS

Patients with NAFLD/NASH and T2D had greater baseline disease activity versus those without T2D, but there was greater regression of disease activity over time among those with T2D. Patients with NAFLD/NASH and obesity had worsening of fibrosis versus those without obesity. NCT00063622.

The Metabolic Score for Insulin Resistance Index is Superior to the Triglyceride and Glucose Index in Identifying Nonalcoholic Fatty Liver Disease in Hyperuricemia Subjects

Purpose

Hyperuricemia (HUA) is a recognized risk factor for non-alcoholic fatty liver disease (NAFLD). Early diagnosis and the identification of predictive factors are important for the HUA population. This study aimed to investigate the potential relationship between the metabolic score for insulin resistance (METS-IR) index and the triglyceride and glucose (TyG) index with NAFLD in individuals with HUA.

Patients and Methods

A total of 5537 HUA participants were included in the study. Hepatic ultrasonography was conducted following the latest diagnostic criteria to diagnose NAFLD. The relationship between the TyG and METS-IR index and NAFLD was evaluated by multivariable logistic regression analysis and restricted cubic spline model (RCS). In addition, the area under the curve (AUC), positive likelihood ratio, and negative likelihood ratio were explored to compare the predictive value of IR surrogates for NAFLD with HUA. The AUCs of the two indicators were compared using the DeLong test.

Results

Multivariable logistic regression analysis revealed that elevated TyG (OR = 2.285, 95% CI: 1.525, 3.428) and METS-IR (OR = 1.242, 95% CI: 1.219, 1.266) indices significantly increase the risk of NAFLD. Meanwhile, the RCS analysis revealed a -log-shaped nonlinear relationship between NAFLD risk and the METS-IR index (P non-linear < 0.001), contrasting with the linear association observed with the TyG index (P non-linear = 0.763). Notably, the risk of NAFLD demonstrated a significant escalation when the METS-IR index exceeded the threshold of 39.208 (OR=1). Compared to the TyG index (AUC = 0.734, 95% CI: 0.721~0.748), the METS-IR index (AUC = 0.821, 95% CI: 0.810~0.832) demonstrated superior predictive value for NAFLD in individuals with HUA according to the DeLong test.

Conclusion

In the HUA population, the METS-IR index has a higher predictive value for NAFLD than the TyG index, contributing to early diagnosis and disease prevention.

Alleviation of adipose-hepatic glycolipid dysregulation by acetate in experimental PCOS model is associated with NF-κB/NLRP3 repression

This study hypothesized that acetate breaks the vicious cycle driving adipose-hepatic metabolic dysregulation in a rat model of polycystic ovarian syndrome (PCOS), possibly by suppression of nuclear factor-kappaB (NF-κB)/NOD-like receptor protein 3 (NLRP3) inflammasome. Female Wistar rats (8-week-old) were randomly allocated into four groups of n =6/group, which received vehicle, sodium acetate (200 mg), letrozole (1 mg/kg), and letrozole plus sodium acetate, respectively. The animals were treated by oral gavage, once daily for a period of 21 days. The PCOS animals were insulin-resistant, hyperandrogenic, and hypoestrogenic with decreased sex-hormone binding globulin. In addition, the hepatic tissue had increased lipid profile and decreased glycogen synthesis, while the adipose tissue showed decreased lipid profile with elevated glycogen synthesis. Besides, the results also showed increased malondialdehyde, γ-glutamyl transferase, lactate dehydrogenase, and inflammatory mediators with corresponding decrease in antioxidant defense in the hepatic and adipose tissues. Immunohistochemical evaluation also demonstrated severe expression with Bcl2-associated X protein/NLRP3 antibodies. Nonetheless, concomitant acetate supplementation attenuated these derangements. The present data collectively suggest that acetate ameliorates adipose-hepatic glycolipid dysregulation in experimental PCOS model by attenuating androgen excess and NF-κB/NLRP3 immunoreactivity.

Insulin resistance and metabolic flexibility as drivers of liver and cardiac disease in T2DM

Metabolic flexibility refers to the ability of tissues to adapt their use of energy sources according to substrate availability and energy demands. This review aims to disentangle the emerging mechanisms through which altered metabolic flexibility and insulin resistance promote NAFLD and heart disease progression. Insulin resistance and metabolic inflexibility are central drivers of hepatic and cardiac diseases in individuals with type 2 diabetes. Both play a critical role in the complex interaction between glucose and lipid metabolism. Disruption of metabolic flexibility results in hyperglycemia and abnormal lipid metabolism, leading to increased accumulation of fat in the liver, contributing to the development and progression of NAFLD. Similarly, insulin resistance affects cardiac glucose metabolism, leading to altered utilization of energy substrates and impaired cardiac function, and influence cardiac lipid metabolism, further exacerbating the progression of heart failure. Regular physical activity promotes metabolic flexibility by increasing energy expenditure and enabling efficient switching between different energy substrates. On the contrary, weight loss achieved through calorie restriction ameliorates insulin sensitivity without improving flexibility. Strategies that mimic the effects of physical exercise, such as pharmacological interventions or targeted lifestyle modifications, show promise in effectively treating both diabetes and NAFLD, finally reducing the risk of advanced liver disease.

Towards precision medicine in non-alcoholic fatty liver disease

Non-Alcoholic Fatty Liver Disease (NAFLD) refers to the accumulation of lipid laden vacuoles in hepatocytes, occurring in the context of visceral adiposity, insulin resistance and other features of the metabolic syndrome. Its more severe form (NASH, Non-Alcoholic Steatohepatitis) is becoming the leading aetiology of end-stage liver disease and hepatocellular carcinoma, and also contributes to cardiovascular disease, diabetes and extrahepatic malignancy. Management is currently limited to lifestyle modification and optimisation of the metabolic co-morbidities, with some of the drugs used for the latter also having shown some benefit for the liver. Licensed treatment modalities are currently lacking. A particular difficulty is the notorious heterogeneity of the patient population, which is poorly understood. A spectrum of disease severity associates in a non-linear way with a spectrum of severity of underlying metabolic factors. Heterogeneity of the liver in terms of mechanisms to cope with the metabolic and inflammatory stress and in terms of repair mechanisms, and a lack of knowledge hereof, further complicate the understanding of inter-individual variability. Genetic factors act as disease modifiers and potentially allow for some risk stratification, but also only explain a minor fraction of disease heterogeneity. Response to treatment shows a large variation in treatment response, again with little understanding of what is driving the absence of response in individual patients. Management can be tailored to patient's preferences in terms of diet modification, but tailoring treatment to knowledge on disease driving mechanisms in an individual patient is still in its infancy. Recent progress in analysing liver tissue as well as non-invasive tests hold, however, promise to rapidly improve our understanding of disease heterogeneity in NAFLD and provide individualised management.

The effect of 12 weeks of combined training on hepatic fat content and metabolic flexibility of individuals with non-alcoholic fatty liver disease: Protocol of an open-label, single-center randomized control trial

Introduction

Metabolic flexibility (MetF) is the capacity of an organism to oxidate substrate according to substrate availability or demand. The mismatch of substrate availability and oxidation may cause ectopic fat accumulation in the muscle and the liver. The objectives of the study are to examine the effect of 12 weeks of combined exercise on hepatic fat reduction and investigate metabolites related to MetF before and after the high-fat diet between individuals with NAFLD and healthy control with an active lifestyle.

Methods

This study is an open-label, single-center trial randomized controlled clinical study plus a cross-sectional comparison between individuals with NAFLD and healthy control. Individuals with NAFLD were allocated into two groups receiving resistance training (RT) combined with high-intensity interval training (HIIT) or moderate-intensity continuous training (MICT). Anthropometric indicators, clinical blood markers about glucose, lipid metabolism, and hepatic fat content (HFC) were assessed before and after the intervention. The metabolomics was also used to investigate the discrepant metabolites and mechanisms related to MetF.

Discussion

Metabolic flexibility reflects the capacity of an organism to switch the oxidation substrates flexibly, which is associated with ectopic fat accumulation. Our study aimed to explore the discrepant metabolites related to MetF before and after a high-fat diet between individuals with NAFLD and healthy control. In addition, the study also examined the effectiveness of RT combined with HIIT or MICT on hepatic fat reduction and quantificationally analyzed the metabolites related to MetF before and after the intervention. Our results provided a perspective on fatty liver-associated metabolic inactivity.

Trial registration

ClinicalTrials.gov: ChiCTR2200055110; Registered 31 December 2021, http://www.chictr.org.cn/index.aspx.

Metabolic (dysfunction)-associated fatty liver disease in individuals of normal weight

Metabolic (dysfunction)-associated fatty liver disease (MAFLD) affects up to a third of the global population; its burden has grown in parallel with rising rates of type 2 diabetes mellitus and obesity. MAFLD increases the risk of end-stage liver disease, hepatocellular carcinoma, death and liver transplantation and has extrahepatic consequences, including cardiometabolic disease and cancers. Although typically associated with obesity, there is accumulating evidence that not all people with overweight or obesity develop fatty liver disease. On the other hand, a considerable proportion of patients with MAFLD are of normal weight, indicating the importance of metabolic health in the pathogenesis of the disease regardless of body mass index. The clinical profile, natural history and pathophysiology of patients with so-called lean MAFLD are not well characterized. In this Review, we provide epidemiological data on this group of patients and consider overall metabolic health and metabolic adaptation as a framework to best explain the pathogenesis of MAFLD and its heterogeneity in individuals of normal weight and in those who are above normal weight. This framework provides a conceptual schema for interrogating the MAFLD phenotype in individuals of normal weight that can translate to novel approaches for diagnosis and patient care.

Metabolic dysfunction-associated fatty liver disease in obese youth with insulin resistance and type 2 diabetes

PURPOSE OF REVIEW

The aim of this review is to present the new definition of the disease, defining the epidemiology, risk factors with a particular attention to the role of insulin resistance (IR) and to define the main treatments explored.

RECENT FINDINGS

Nonalcoholic fatty liver disease (NAFLD) was previously considered a primary liver disease, but it would be more correct to consider it a component of the metabolic syndrome (MetS) in which IR might play a key role. Based on these findings, it has been recently proposed to modify the classic term of NAFLD to metabolic dysfunction-associated fatty liver disease (MAFLD) that better reflects the pathophysiology of this complex disease.

SUMMARY

Currently, no treatments approved in childhood are available, thus the only recommended approach is the prevention and correction of the known risk factors, and particularly of IR. However, further studies are needed to better clarify the pathogenetic mechanisms of NAFLD in order to establish more tailored therapies.

External validation and comparison of simple tools to screen for nonalcoholic fatty liver disease in Chinese community population

BACKGROUND

Various noninvasive tools based on anthropometric indicators, blood lipids, and liver enzymes, etc. have been developed to screen for nonalcoholic fatty liver disease (NAFLD), with different diagnostic performance and cutoff values among studies. We aimed to validate and compare eight NAFLD-related models developed by simple indicators and to define their cutoff values in Chinese community population.

METHODS

A cross-sectional study was conducted in a health examination cohort of 3259 people. NAFLD was diagnosed by ultrasonography. General, anthropometric and biochemical data were collected. Fatty liver index (FLI), fatty liver disease index (FLD), Zhejiang University index (ZJU), lipid accumulation product (LAP), regression formula of controlled attenuation parameter (CAP), waist-to-height ratio (WHtR), triglyceride and glucose index (TyG), and visceral adiposity index (VAI) were calculated. The accuracy and cutoff points to detect NAFLD were evaluated by area under the receiver operator characteristic curve and the maximum Youden index analysis, respectively. A head-to-head comparison between these models and Decision Curve Analysis (DCA) was conducted.

RESULTS

In eight noninvasive diagnostic models of NAFLD, AUCs of FLI and FLD for NAFLD were higher than those of other models in the whole (0.852 and 0.852), male (0.826 and 0.824), and female (0.897 and 0.888) population, respectively. DCA showed that FLI, FLD, and ZJU have higher net benefit to screen for NAFLD compared to other models.

CONCLUSIONS

FLI and FLD could be the most accurate and applicable of eight models for the noninvasive diagnosis of NAFLD in both male and female groups.

Non-alcoholic fatty liver disease: a multi-system disease influenced by ageing and sex, and affected by adipose tissue and intestinal function

In recent years, a wealth of factors are associated with increased risk of developing non-alcoholic fatty liver disease (NAFLD) and NAFLD is now thought to increase the risk of multiple extra-hepatic diseases. The aim of this review is first to focus on the role of ageing and sex as key, poorly understood risk factors in the development and progression of NAFLD. Secondly, we aim to discuss the roles of white adipose tissue (WAT) and intestinal dysfunction, as producers of extra-hepatic factors known to further contribute to the pathogenesis of NAFLD. Finally, we aim to summarise the role of NAFLD as a multi-system disease affecting other organ systems beyond the liver. Both increased age and male sex increase the risk of NAFLD and this may be partly driven by alterations in the distribution and function of WAT. Similarly, changes in gut microbiota composition and intestinal function with ageing and chronic overnutrition are likely to contribute to the development of NAFLD both directly (i.e. by affecting hepatic function) and indirectly via exacerbating WAT dysfunction. Consequently, the presence of NAFLD significantly increases the risk of various extra-hepatic diseases including CVD, type 2 diabetes mellitus, chronic kidney disease and certain extra-hepatic cancers. Thus changes in WAT and intestinal function with ageing and chronic overnutrition contribute to the development of NAFLD – a multi-system disease that subsequently contributes to the development of other chronic cardiometabolic diseases.

Combination therapy with pioglitazone/exenatide/metformin reduces the prevalence of hepatic fibrosis and steatosis: The efficacy and durability of initial combination therapy for type 2 diabetes (EDICT)

AIM

To compare the efficacy of triple therapy (metformin/exenatide/pioglitazone) versus stepwise conventional therapy (metformin → glipizide → glargine insulin) on liver fat content and hepatic fibrosis in newly diagnosed, drug-naïve patients with type 2 diabetes.

METHODS

Sixty-eight patients completed the 6-year follow-up and had an end-of-study (EOS) FibroScan to provide measures of steatosis (controlled attenuation parameter [CAP] in dB/m) and fibrosis (liver stiffness measurement [LSM] in kPa); 59 had magnetic resonance imaging-proton density fat fraction (MRI-PDFF) to measure liver fat.

RESULTS

At EOS, HbA1c was 6.8% and 6.0% in triple and conventional therapy groups, respectively (P = .0006). Twenty-seven of 39 subjects (69%) receiving conventional therapy had grade 2/3 steatosis (CAP, FibroScan) versus nine of 29 (31%) in triple therapy (P = .0003). Ten of 39 (26%) subjects receiving conventional therapy had stage 3/4 fibrosis (LSM) versus two of 29 (7%) in triple therapy (P = .04). Conventional therapy subjects had more liver fat (MRI-PDFF) than triple therapy (12.9% vs. 8.8%, P = .03). The severity of steatosis (CAP) (r = 0.42, P < .001) and fibrosis (LSM) (r = -0.48, P < .001) correlated inversely with the Matsuda Index of insulin sensitivity, but not with percentage body fat. Aspartate aminotransferase (AST) to Platelet Ratio Index (APRI), non-alcoholic fatty liver disease fibrosis score (NFS), plasma AST, and alanine aminotransferase (ALT) all decreased significantly with triple therapy, but only the decrease in plasma AST and ALT correlated with the severity of steatosis and fibrosis at EOS.

CONCLUSIONS

At EOS, subjects with type 2 diabetes treated with triple therapy had less hepatic steatosis and fibrosis versus conventional therapy; the severity of hepatic steatosis and fibrosis were both strongly and inversely correlated with insulin resistance; and changes in liver fibrosis scores (APRI, NFS, Fibrosis-4, and AST/ALT ratio) have limited value in predicting response to therapy.

Meta-Inflammation and De Novo Lipogenesis Markers Are Involved in Metabolic Associated Fatty Liver Disease Progression in BTBR ob/ob Mice

Metabolic associated fatty liver disease (MAFLD) is a hepatic manifestation of metabolic syndrome and usually associated with obesity and diabetes. Our aim is to characterize the pathophysiological mechanism involved in MAFLD development in Black Tan and brachyuric (BTBR) insulin-resistant mice in combination with leptin deficiency (ob/ob). We studied liver morphology and biochemistry on our diabetic and obese mice model (BTBR ob/ob) as well as a diabetic non-obese control (BTBR + streptozotocin) and non-diabetic control mice (BTBR wild type) from 4–22 weeks. Lipid composition was assessed, and lipid related pathways were studied at transcriptional and protein level. Microvesicular steatosis was evident in BTBR ob/ob from week 6, progressing to macrovesicular in the following weeks. At 12th week, inflammatory clusters, activation of STAT3 and Nrf2 signaling pathways, and hepatocellular ballooning. At 22 weeks, the histopathological features previously observed were maintained and no signs of fibrosis were detected. Lipidomic analysis showed profiles associated with de novo lipogenesis (DNL). BTBR ob/ob mice develop MAFLD profile that resemble pathological features observed in humans, with overactivation of inflammatory response, oxidative stress and DNL signaling pathways. Therefore, BTBR ob/ob mouse is an excellent model for the study of the steatosis to steatohepatitis transition.

Adipose tissue insulin resistance and lipidome alterations as the characterizing factors of non-alcoholic steatohepatitis

BACKGROUND

The prevalence of non-alcoholic fatty liver disease (NAFLD) is now 25% in the general population but increases to more than 55% in subjects with obesity and/or type 2 diabetes. Simple steatosis (NAFL) can develop into more severe forms, that is non-alcoholic steatohepatitis (NASH), cirrhosis and hepatocellular carcinoma leading to death.

METHODS

In this narrative review, we have discussed the current knowledge in the pathophysiology of fatty liver disease, including both metabolic and non-metabolic factors, insulin resistance, mitochondrial function, as well as the markers of liver damage, giving attention to the alterations in lipid metabolism and production of lipotoxic lipids.

RESULTS

Insulin resistance, particularly in the adipose tissue, is the main driver of NAFLD due to the excess release of fatty acids. Lipidome analyses have shown that several lipids, including DAGs and ceramides, and especially if they contain saturated lipids, act as bioactive compounds, toxic to the cells. Lipids can also affect mitochondrial function. Not only lipids, but also amino acid metabolism is impaired in NAFL/NASH, and some amino acids, as branched-chain and aromatic amino acids, glutamate, serine and glycine, have been linked to impaired metabolism, insulin resistance and severity of NAFLD and serine is a precursor of ceramides.

CONCLUSIONS

The measurement of lipotoxic species and adipose tissue dysfunction can help to identify individuals at risk of progression to NASH.

Diagnostic Value of Acyl-Ghrelin in Type 2 Diabetic Patients with Non-alcoholic Fatty Liver Disease

BACKGROUND: Nonalcoholic fatty liver disease (NAFLD) has become the leading cause of chronic liver disease worldwide. Type 2 diabetes (T2D) is described as one of the most significant risk factor for developing NAFLD, non-alcoholic steatohepatitis, and advanced cirrhosis. Liver biopsy cannot be used routinely to diagnose NAFLD. Therefore, it is critically urgent to develop a simple non-invasive test. AIM: This study examined fasting Acyl-Ghrelin (AG) as a non-invasive biomarker to accurately diagnose NAFLD in diabetic patients. PATIENTS AND METHODS: Sixty-one patients with T2D were divided into a test group with NAFLD, and a control group without NAFLD. Secondary causes of fatty liver, chronic viral hepatitis, and drug-induced liver damage were excluded from the study. Anthropometric measurements, lipid profile, fasting blood sugar (FBS), liver enzyme activities, and fasting AG levels were collected. Data management and analysis were performed using statistical package for social sciences version 20. RESULTS: Fasting AG level (pg/ml) in the test group (56.1 ± 10.7) was increased, but not statically significant compared with the control group (37.8 ± 9.3), p > 0.05. However, significant metabolic changes were observed in body weight, waist circumference, FBS, alanine transaminase, and aspartate transaminase between test and control groups. The mean values in the test group are 93.2 ± 14.5, 115.4 ± 7.6, 144.2 ± 25.9, 21.1 ± 5.7, and 32.3 ± 2.1. While the mean values are 87.7 ± 7.3, 95 ± 3.8, 123.7 ± 20.7, 18.6 ± 5, and 20 ± 7, respectively, in the control group. CONCLUSIONS: While elevated AG levels alone were not significant, elevated AG levels plus other parameters of liver damage and obesity were associated with the diagnosis of NAFLD. However, more studies are needed to consider elevated AG as a diagnostic marker in NAFLD patients with T2D.

The triglyceride-glucose index as a clinical useful marker for metabolic associated fatty liver disease (MAFLD): a population-based study among Iranian adults

Background and aims

There is a bi-directional association between non-alcoholic fatty liver disease (NAFLD) and insulin resistance in type 2 diabetes mellitus (T2DM) and metabolic syndrome. The triglyceride-glucose (TyG) index is a novel surrogate marker of insulin resistance. In this population-based study, we aimed firstly to investigate the association of the TyG-index with metabolic-associated fatty liver disease (MAFLD) risk.

Methods

This case-control study used the data from the first phase of the Persian Cohort Study in Sabzevar. Of 4,241 participants aged 35 to 70 years, we identified and recruited 968 MAFLD cases and 964 age- and sex-adjusted controls. Demographic, lifestyle, anthropometric, and biochemical information were collected. We calculated TyG and a new index combined of TyG and alanine aminotransferase (TyG-ALT). We used the multivariable unconditional logistic regression model to calculate the odds ratios (ORs) of the TyG and TyG-ALT for having MAFLD.

Results

Among those in the highest relative to the lowest TyG and TyG-ALT tertiles, the multivariable-adjusted ORs were 12.01 (95% CI [confidence interval] 9.03 - 15.98; P _trend < 0.001) and 10.89 (95% CI 7.66 - 15.48; P _trend = 0.001), respectively. The area under the curves (AUC) for the TyG-index to predict MAFLD was 8.62, resulting in a cut-off value of 8.62 with a sensitivity of 81.66% and specificity of 75.36%.

Conclusions

The higher TyG and TyG-ALT scores were significantly positively associated with higher MAFLD risk in the Iranian population.

Non-alcoholic fatty liver disease in obese children and adolescents: a role for nutrition?

Non-alcoholic fatty liver disease (NAFLD) has become the most common cause of chronic liver disease in children, paralleling the increasing prevalence of obesity worldwide. The pathogenesis of paediatric NAFLD is not fully understood, but it is known that obesity, nutrition, lifestyle variables, genetic and epigenetic factors may be causally involved in the development of this common metabolic liver disease. In particular, obesity and nutrition are among the strongest risk factors for paediatric NAFLD, which may exert their adverse hepatic effects already before birth. Excess energy intake induces hypertrophy and hyperplasia of adipose tissue with subsequent development of systemic insulin resistance, which is another important risk factor for NAFLD. Diet composition and in particular simple carbohydrate intake (especially high fructose intake) may promote the development of NAFLD, whereas non-digestible carbohydrates (dietary fiber), by affecting gut microbiota, may favour the integrity of gut wall and reduce inflammation, opposing this process. Saturated fat intake may also promote NAFLD development, whereas unsaturated fat intake has some beneficial effects. Protein intake does not seem to affect the development of NAFLD, but further investigation is needed. In conclusion, lifestyle modifications to induce weight loss, through diet and physical activity, remain the mainstay of treatment for paediatric NAFLD. The use of dietary supplements, such as omega-3 fatty acids and probiotics, needs further study before recommendation.

Lipid-Induced Adaptations of the Pancreatic Beta-Cell to Glucotoxic Conditions Sustain Insulin Secretion

Over the last decades, lipotoxicity and glucotoxicity emerged as established mechanisms participating in the pathophysiology of obesity-related type 2 diabetes in general, and in the loss of β-cell function in particular. However, these terms hold various potential biological processes, and it is not clear what precisely they refer to and to what extent they might be clinically relevant. In this review, we discuss the basis and the last advances of research regarding the role of free fatty acids, their metabolic intracellular pathways, and receptor-mediated signaling related to glucose-stimulated insulin secretion, as well as lipid-induced β-cell dysfunction. We also describe the role of chronically elevated glucose, namely, glucotoxicity, which promotes failure and dedifferentiation of the β cell. Glucolipotoxicity combines deleterious effects of exposures to both high glucose and free fatty acids, supposedly provoking synergistic defects on the β cell. Nevertheless, recent studies have highlighted the glycerolipid/free fatty acid cycle as a protective pathway mediating active storage and recruitment of lipids. Finally, we discuss the putative correspondence of the loss of functional β cells in type 2 diabetes with a natural, although accelerated, aging process.

Potential Natural Compounds for the Prevention and Treatment of Nonalcoholic Fatty Liver Disease: A Review on Molecular Mechanisms

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) is a kind of metabolic stress-induced liver injury closely related to insulin resistance and genetic susceptibility, and there is no specific drug for its clinical treatment currently. In recent years, a large amount of literature has reported that many natural compounds extracted from traditional Chinese medicine (TCM) can improve NAFLD through various mechanisms. According to the latest reports, some emerging natural compounds have shown great potential to improve NAFLD but are seldom used clinically due to the lacking special research.

PURPOSE

This paper aims to summarize the molecular mechanisms of the potential natural compounds on improving NAFLD, thus providing a direction and basis for further research on the pathogenesis of NAFLD and the development of effective drugs for the prevention and treatment of NAFLD.

METHODS

By searching various online databases, such as Web of Science, SciFinder, PubMed, and CNKI, NAFLD and these natural compounds were used as the keywords for detailed literature retrieval.

RESULTS

The pathogenesis of NAFLD and the molecular mechanisms of the potential natural compounds on improving NAFLD have been reviewed.

CONCLUSION

Many natural compounds from traditional Chinese medicine have a good prospect in the treatment of NAFLD, which can serve as a direction for the development of anti-NAFLD drugs in the future.

Study on the Hepatoprotection of Schisandra chinensis Caulis Polysaccharides in Nonalcoholic Fatty Liver Disease in Rats Based on Metabolomics

The aim of this study was to investigate the hepatoprotection of Schisandra chinensis Caulis polysaccharides (SCPs) in the nonalcoholic fatty liver disease (NAFLD) induced by high-fat diet (HFD) in rats. A total of 30 Wistar rats were randomly divided into the control group (CON), model group (MOD), and Schisandra chinensis caulis polysaccharide (SCP) group. Except for those in the CON group, the other rats were fed with high-fat diet for 4 weeks to establish an NAFLD model. From the 5th week, rats in the SCP group were given SCP solution (100 mg kg^-1) by gavage for 6 weeks, and those in the CON and MOD groups were given an equal volume of distilled water in the same way. Aspartate aminotransferase (AST), alanine aminotransferase (ALT), triglyceride (TG), total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C) levels in serum, the malondialdehyde (MDA) level, glutathione peroxidase (GSH-Px), and superoxide dismutase (SOD) activities in the liver tissue were detected. The small molecular metabolites in the blood of rats were determined by the metabolomics method of ultra-high-performance liquid chromatography-quadrupole/electrostatic field orbitrap high-resolution mass spectrometry (UHPLC-Q-Orbitrap-MS/MS) combined with multivariate analysis. The enrichment analysis and pathway analysis of the different metabolites were carried out. The therapeutic mechanism of SCP in NAFLD rats was verified by western blot. The results showed that the levels of AST, ALT, TG, TC, and LDL-C in the serum of rats in the SCP group were significantly lower, and the levels of HDL-C were significantly higher than those in the MOD group. The screening and analysis of the metabolic pathways showed that SCP could alleviate the development of NAFLD by regulating the expression of UDP-glucose pyrophosphorylase (UGP2), UDP-glucose 6-dehydrogenase (UGDH), acetyl CoA carboxylase (ACC), and fatty acid synthase (FAS) in the liver of NAFLD rats. This study may provide a theoretical basis for the development and utilization of SCP.

The Role of Mitochondrial Adaptation and Metabolic Flexibility in the Pathophysiology of Obesity and Insulin Resistance: an Updated Overview

PURPOSE OF REVIEW

The term "metabolic flexibility" denotes the dynamic responses of the cellular oxidative machinery in order to adapt to changes in energy substrate availability. A progressive loss of this adaptive capacity has been implicated in the development of obesity-related comorbidities. Mitochondria are dynamic intracellular organelles which play a fundamental role in energy metabolism, and the mitochondrial adaptation to environmental challenges may be viewed as the functional component of metabolic flexibility. Herein, we attempt to comprehensively review the available evidence regarding the role of mitochondrial adaptation and metabolic flexibility in the pathogenesis of obesity and related morbidities, namely insulin resistance states and non-alcoholic fatty liver disease (NAFLD).

RECENT FINDINGS

Overall, there is a concrete body of evidence to support the presence of impaired mitochondrial adaptation as a principal component of systemic metabolic inflexibility in conditions related to obesity. There are still many unresolved questions regarding the relationship between the gradual loss of mitochondrial adaptability and the progression of obesity-related complications, such as causality issues, the timely appearance and reversibility of the described disturbances, and the generalizability of the findings to the mitochondrial content of every affected tissue or organ. The evidence regarding the causality between the observed associations remains inconclusive, although most of the available data points towards a bidirectional, potentially mutually amplifying relationship. The spectrum of NAFLD is of particular interest, since functional and pathological changes in the course of its development closely mirror the progression of dysmetabolism, if not constituting a dynamic component of the latter.

Ethnicity-specific alterations of plasma and hepatic lipidomic profiles are related to high NAFLD rate and severity in Hispanic Americans, a pilot study

Nonalcoholic fatty liver disease (NAFLD) is a progressive condition that includes steatosis (NAFL) and nonalcoholic steatohepatitis (NASH). In the U.S., Hispanics (HIS) are afflicted with NAFLD at a higher rate and severity compared to other ethnicities. To date, the mechanisms underlying this disparity have not been elucidated. In this pilot study, we compared untargeted plasma metabolomic profiles for primary metabolism, complex lipids, choline and related compounds between a group of HIS (n = 7) and White Caucasian (CAU, n = 8) subjects with obesity and biopsy-characterized NAFL to ethnicity-matched lean healthy controls (n = 14 HIS and 8 CAU). We also compared liver and plasma metabolomic profiles in a group of HIS and CAU subjects with obesity and NASH of comparable NAFLD Activity Scores, to BMI-matched NASH-free subjects in both ethnicities. Results highlight signs of metabolic dysregulation observed in HIS, independent of obesity, including higher plasma triglycerides, acylcarnitines, and free fatty acids. With NASH progression, there were ethnicity-related differences in the hepatic profile, including higher free fatty acids and lysophospholipids seen in HIS, suggesting lipotoxicity is involved in the progression of NASH. We also observed greater hepatic triglyceride content, higher plasma triglyceride concentrations and lower hepatic phospholipids with signs of impaired hepatic mitochondrial β-oxidation. These findings provide preliminary evidence indicating ethnicity-related variations that could potentially modulate the risk for progression of NALD to NASH.

Association of Serum Alkaline Phosphatase with the TG/HDL Ratio and TyG Index in Korean Adults

Alkaline phosphatase (ALP) has long been considered a marker of hepatobiliary and bone disorders, but recent studies have shown that increased ALP activity is correlated with various cardio-metabolic diseases. Thus, we investigated the association of serum ALP level with surrogate markers of insulin resistance such as triglyceride to high-density lipoprotein cholesterol ratio (TG/HDL-C ratio) and triglyceride and glucose (TyG) index in the general population. The study included 12,868 men and women aged 19 years and older. Participants were categorized into four groups based on serum ALP level (U/L) as follows: Q1: 55-190 U/L, Q2: 191-224 U/L, Q3: 225-265 U/L, and Q4: 266-923 U/L for men, Q1: 48-161 U/L, Q2: 162-198 U/L, Q3: 199-245 U/L, Q4: 246-790 U/L for women. The insulin resistance cut-off levels were defined corresponding to the 75th percentile of the TyG index and TG/HDL-C ratio in the current samples. Odds ratios (ORs) with 95% confidence intervals (CIs) of insulin resistance according to quartile of serum ALP level were calculated using weighted multivariate logistic regression analysis. Compared with Q1, the adjusted OR (95% CI) for insulin resistance of the Q4 serum ALP group was 1.517 (1.234-1.866) in men and 1.881 (1.399-2.528) in women using the TG/HDL-C ratio and 1.374 (1.093-1.728) in men and 2.047 (1.468-2.855) in women using the TyG index after adjusting for confounding variables. Serum ALP levels are independently and positively associated with surrogate markers of insulin resistance in Korean adults.

Vitamin K2 as a New Modulator of the Ceramide De Novo Synthesis Pathway

The aim of the study was to evaluate the influence of vitamin K2 (VK2) supplementation on the sphingolipid metabolism pathway in palmitate-induced insulin resistant hepatocytes. The study was carried out on human hepatocellular carcinoma cells (HepG2) incubated with VK2 and/or palmitic acid (PA). The concentrations of sphingolipids were measured by high-performance liquid chromatography. The expression of enzymes from the sphingolipid pathway was assessed by Western blotting. The same technique was used in order to determine changes in the expression of the proteins from the insulin signaling pathway in the cells. Simultaneous incubation of HepG2 cells with palmitate and VK2 elevated accumulation of sphinganine and ceramide with increased expression of enzymes from the ceramide de novo synthesis pathway. HepG2 treatment with palmitate and VK2 significantly decreased the insulin-stimulated expression ratio of insulin signaling proteins. Moreover, we observed that the presence of PA w VK2 increased fatty acid transport protein 2 expression. Our study showed that VK2 activated the ceramide de novo synthesis pathway, which was confirmed by the increase in enzymes expression. VK2 also intensified fatty acid uptake, ensuring substrates for sphingolipid synthesis through the de novo pathway. Furthermore, increased concentration of sphingolipids, mainly sphinganine, inhibited insulin pathway proteins phosphorylation, increasing insulin resistance development.

Effects of Cotadutide on Metabolic and Hepatic Parameters in Adults With Overweight or Obesity and Type 2 Diabetes: A 54-Week Randomized Phase 2b Study

OBJECTIVE

Cotadutide, a dual GLP-1 and glucagon receptor agonist, is under development for nonalcoholic steatohepatitis (NASH) and chronic kidney disease with type 2 diabetes. The effects of cotadutide on hepatic and metabolic parameters were evaluated in participants with overweight/obesity and type 2 diabetes.

RESEARCH DESIGN AND METHODS

In this phase 2b study, 834 adults with BMI ≥25 kg/m² and type 2 diabetes inadequately controlled with metformin (glycated hemoglobin A_1c [HbA_1c] of 7.0%-10.5% [53-91 mmol/mol]) were randomized to double-blind cotadutide 100 μg (n = 100), 200 μg (n = 256), or 300 μg (n = 256); placebo (n = 110); or open-label liraglutide 1.8 mg (n = 110)-all administered subcutaneously. Coprimary end points were changes in HbA_1c and body weight at week 14. The originally randomized interventions were continued to week 54. Liver damage biomarkers and liver fibrosis algorithms were assessed.

RESULTS

Cotadutide significantly decreased HbA_1c and body weight at weeks 14 and 54 versus placebo (all P < 0.001). Improvements in lipid profile, AST and ALT levels, propeptide of type III collagen level, fibrosis-4 index, and nonalcoholic fatty liver disease fibrosis score were observed with cotadutide 300 μg versus placebo, but not with liraglutide. Weight loss with cotadutide 200 μg was similar to that with liraglutide 1.8 mg and greater with cotadutide 300 μg versus liraglutide 1.8 mg. The most common adverse events with cotadutide (nausea, 35%; vomiting, 17%) decreased over time.

CONCLUSIONS

Cotadutide treatment for 54 weeks improved glycemic control and weight loss in participants with overweight/obesity and type 2 diabetes. Ad hoc analyses demonstrated improvements in hepatic parameters and support further evaluation of cotadutide in NASH.

Secretory Galectin-3 promotes hepatic steatosis via regulation of the PPARγ/CD36 signaling pathway

Galectin-3 (Gal3) is an essential regulator of a number of metabolic disorders. Previous studies have established that Gal3 is a positive regulator of inflammation, fibrosis, and insulin resistance. However, its function in the early pathogenesis of hepatic lipid accumulation in non-alcoholic fatty liver disease (NAFLD) remains unresolved. Here, we demonstrate the presence of significantly upregulated extracellular concentrations of Gal3 in the fatty livers of high-fat diet (HFD)-induced mice. Systemic inhibition of Gal3 by injection of TD139 reduced the accumulation of lipid in the livers of HFD-fed mice, accompanied by the decreased expression of CD36 and peroxisome proliferator-activated receptor-gamma (PPARγ). Treatment with Gal3 protein elicited the opposite response in palmitic acid (PA)-induced HepG2 hepatocytes. It was additionally discovered that Gal3 positively regulates CD36 transcription by increased activation of PPARγ, thereby increasing fatty acid uptake, resulting in hepatic steatosis. In conclusion, the present study confirmed the roles of Gal3 in hepatic lipid metabolism in both in vitro and in vivo studies and revealed that Gal3 is a secretory protein that promotes hepatic steatosis through the PPARγ-CD36-dependent pathway, suggesting that targeting Gal3 may represent a potential therapeutic approach for the treatment of NAFLD and related metabolic disorders.

Liraglutide in patients with non-alcoholic fatty liver disease: a systematic review and meta-analysis of randomized controlled trials

BACKGROUND

A few randomized controlled trials (RCTs) have assessed the use of liraglutide as a treatment option in patients with non-alcoholic fatty liver disease (NAFLD). We aimed at critically appraising and summarizing these RCTs, providing precise effect estimates regarding the safety and efficacy of liraglutide in NAFLD.

METHODS

We searched major databases and grey literature from their inception to May 2019, for RCTs comparing liraglutide with placebo or active comparator in patients with NAFLD. We defined as primary efficacy outcomes the observed changes in hepatic fat content (HFC) and alanine aminotransferase levels (ALT). Metabolic outcomes of interest and major safety endpoints were also assessed.

RESULTS

We included five trials with 371 randomised participants in total. Liraglutide produced a non-significant decrease in HFC and ALT levels, compared to control. It induced a significant reduction in body mass index, primarily driven by reduction in patients with type 2 diabetes, while it did not affect significantly glycated hemoglobin levels and Homeostatic Model Assessment of Insulin Resistance. We also showed that liraglutide significantly decreased serum triglyceride levels, also driven by the observed reduction in patients with type 2 diabetes, however it did not significantly affect the rest lipid parameters. Liraglutide was associated with increased incidence of gastrointestinal adverse events, while, no other safety issues were identified.

CONCLUSION

Our results do not substantiate the use of liraglutide in patients with NAFLD yet, despite its promising role.

Upregulated SOCC and IP3R calcium channels and subsequent elevated cytoplasmic calcium signaling promote nonalcoholic fatty liver disease by inhibiting autophagy

Nonalcoholic fatty liver disease (NAFLD) is related to elevated cytoplasmic calcium signaling in hepatocytes, which may be mediated by store-operated calcium channel (SOCC) and inositol triphosphate receptor (IP3R). However, the regulatory effect of calcium signaling on lipid accumulation and degeneration in hepatocytes and the underlying molecular mechanism remain unknown. Autophagy inhibition promotes lipid accumulation and steatosis in hepatocytes. However, the association between elevated calcium signaling and autophagy inhibition in hepatocytes and its effect on hepatocyte fatty lesions remain unclear. Here, we established a mouse hepatocyte fatty gradient model using oleic acid. SOCC and IP3R channel opening and cytoplasmic calcium levels gradually increased with the hepatocyte pimelosis degree, whereas autophagy gradually decreased. We also established an optimal oleic acid (OOA) hepatocyte model, observing significantly increased SOCC and IP3R channel opening and calcium influx alongside significantly decreased autophagy and aggravated cellular fatty lesion. Calcium channel blockers (CCBs) and calcium channel gene silencing reagents (CCGSRs), respectively, reversed these effects, indicating that elevated cytoplasmic calcium signaling promotes NAFLD occurrence and the development by inhibiting hepatocyte autophagy. In the OOA model, upregulated extracellular regulated protein kinases 1/2 (ERK1/2), which can be regulated by SOCC and IP3R proteins transient receptor potential canonical 1 (TRPC1)/IP3R with elevated cytoplasmic calcium signaling, over-inhibited forkhead/winged helix O (FOXO) signaling and over-activated mammalian target of rapamycin complex 1 (mTORC1) signaling. Over-inhibited FOXO signaling significantly downregulated autophagy-related gene 12, which inhibits autophagosome maturation, while over-activated mTORC1 signaling over-inactivated Unc-51 like autophagy activating kinase 1, which inhibits preautophagosome formation. CCBs and CCGSRs recovered autophagy by significantly downregulating ERK1/2 to block abnormal changes in FOXO and mTORC1 signaling. Our findings indicate that upregulated SOCC and IP3R channels and subsequent elevated cytoplasmic calcium signaling in hepatocyte fatty lesions inhibits hepatocyte autophagy through (TRPC1/IP3R)/ERK/(FOXO/mTORC1) signaling pathways, causes lipid accumulation and degeneration in hepatocytes, and promotes NAFLD occurrence and development.

The continuum of disrupted metabolic tempo, mitochondrial substrate congestion, and metabolic gridlock toward the development of non-communicable diseases

Non-communicable diseases (NCD) are the slow-motion disasters with imminent global health care burden. The current dietary management for NCD is dominated by the calorie balance model. Apart from the quantitative balance of calorie, healthy bioenergetics requires temporal eating and fasting rhythms, and the subsequent switching for different metabolic fuels. We herein term these three bioenergetic attributes, i.e., caloric balance, diurnal eating-fasting rhythm, and metabolic flexibility, as the metabolic tempo. These three attributes are intertwined with each other; alteration of one attribute affects one or more other attributes. Lifestyle-induced disrupted metabolic tempo presents a high flux of mixed carbon substrates to mitochondria, with the resulting congestion and indecisiveness of metabolic switches. Such indecisiveness impairs metabolic flexibility, promotes anabolism, and accumulates the energy storage pools. The triggers from hypoxic inducible factor expression could further promote the metabolic gridlock and adipocyte maladaptation. The maladaptive adipocytes lead to ectopic fat deposition, increased circulating lipid levels, insulin resistance, and chronic systemic inflammation. These continuum set stages for clinical NCDs. We propose that the restoration of all tempo attributes through the combined diet-, time-, and calorie-restricted interventions could be the preferred strategy for NCD management.

Long-term androgen excess induces insulin resistance and non-alcoholic fatty liver disease in PCOS-like rats

OBJECTIVE

Women with polycystic ovary syndrome (PCOS) are at higher risk for metabolic disorders compared to healthy women, and about 51 % of women with PCOS suffer from non-alcoholic fatty liver disease (NAFLD). Investigation into the pathological mechanism behind this association will provide insights for the prevention and treatment of this complication.

METHODS

Dihydrotestosterone (DHT), a nonaromatic androgen, was used to mimic the pathological conditions of hyperandrogenism and insulin resistance. Hematoxylin and eosin staining, Oil Red O staining, immunofluorescent staining, Western blots, and qRT-PCR were used to verify the hepatic steatosis and inflammation, and the latter two methods were also used for energy and mitochondrion-related assays. ELISA was used to measure the level of reactive oxygen species.

RESULTS

Twelve weeks of DHT exposure led to obesity and insulin resistance as well as hepatic steatosis, lipid deposition, and different degrees of inflammation. The expression of molecules involved in respiratory chain and aerobic respiration processes, such as electron transfer complex II, pyruvate dehydrogenase, and succinate dehydrogenase complex subunit A, was inhibited. In addition, molecules associated with apoptosis and autophagy were also abnormally expressed, such as increased Bak mRNA, an increased activated caspase-3 to caspase-3 ratio, and increased Atg12 protein expression. All of these changes are associated with the mitochondria and lead to lipid deposition and inflammation in the liver.

CONCLUSIONS

Long-term androgen excess contributes to insulin resistance and hepatic steatosis by affecting mitochondrial function and causing an imbalance in apoptosis and autophagy, thus suggesting the pathogenesis of NAFLD in women with PCOS.

From Nonalcoholic Fatty Liver Disease (NAFLD) to Metabolic Dysfunction-Associated Fatty Liver Disease (MAFLD)-New Terminology in Pediatric Patients as a Step in Good Scientific Direction?

Nonalcoholic fatty liver disease (NAFLD) is the most common chronic liver disease in the world, which predispose to more serious hepatic conditions. It ranges from simple liver steatosis to nonalcoholic steatohepatitis (NASH), which may progress to cirrhosis, and even end-stage liver disease. Since obesity became one of the most important health concerns wordwide, a considerable increase in the prevalance of NAFLD and other metabolic implications has been observed, both in adults and children. Due to the coexistence of visceral obesity, insulin resistance, dyslipidemia, NAFLD is considered to be the hepatic manifestation of metabolic syndrome (MetS). These relationships between NAFLD and MetS led to the set up in adults of a new term combining both of these conditions, called metabolic dysfunction-associated fatty liver disease (MAFLD). Based on these findings, we propose a set of criteria, which may be useful to diagnose MAFLD in children and adolescents.

Berberine inhibits liver damage in rats with non-alcoholic fatty liver disease by regulating TLR4/MyD88/NF-κB pathway

BACKGROUND/AIMS

This study aimed to explore the therapeutic effects and underlying mechanism of berberine (BBR) on the non-alcoholic fatty liver disease (NAFLD) induced by high-fat diet (HFD).

MATERIALS AND METHODS

Rats were randomly divided into the following 4 groups: control (normal diet), model (HFD), polyene phosphatidylcholine HFD+PPC, and BBR (HFD+BBR) group. The NAFLD models were prepared by feeding with HFD for 12 weeks. The liver tissues were observed by oil red O staining. H-E staining was used to detect pathological changes in the liver tissues. Serum levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), total cholesterol (TC), triglyceride (TG), low-density lipoprotein cholesterol (LDL-C), and high-density lipoprotein cholesterol (HDL-C) were detected by an automatic biochemical analyzer. ELISA was performed to observe the inflammatory cytokines (TNF-α, IL-6, and IL-1β) expressions. The levels of TLR4, MyD88, and NF-κB p65 were analyzed using western blot and qRT-PCR, respectively. The nuclear translocation levels of NF-κB in the primary liver cells were measured using flow cytometry.

RESULTS

BBR could significantly alleviate the liver tissue steatosis and inflammatory cell infiltration; reduce the NAFLD activity scores and serum levels of ALT, AST, TC, and LDL-C; decrease the levels of TNF-α, IL-6, and IL-1β, and reduce the expression of TLR4, MyD88, and NF-κB in the liver tissues. BBR could also reverse the nuclear translocation of NF-κB in the primary liver cells.

CONCLUSION

BBR alleviated the progress of NAFLD and liver damage, which might contribute to inhibit the nuclear translocation of NF-κB via the TLR4/MyD88/NF-κB pathway.

Obesity and impairment of pancreatic β-cell function in early adulthood, independent of obesity age of onset: The Santiago Longitudinal Study

AIM

We investigated the relation of time of onset and length of obesity with biomarkers of β-cell function in early adulthood in an infancy cohort.

MATERIAL AND METHODS

In 1039 23-year-olds, body-mass index (BMI) was measured at multiple time-points from enrollment. BMI trajectories were interpolated with cubic polynomials. Fasting glucose, insulin and adiponectin were measured at 23 years. Homeostatic model assessment-insulin resistance (HOMA-IR), HOMA-S, HOMA-β, HOMA-adiponectin (AD) and disposition index (DI) were estimated. IR and non-alcoholic fatty liver (NAFL) were diagnosed. According to the BMI trajectory, five groups were defined: participants who were never obese (NOB); participants with obesity starting in adolescence and remained obese into adulthood (recent-onset obesity, ROB); participants who were obese in early childhood but transitioned to non-obesity as preadolescents (former obesity, FOB); participants who were obese in early childhood and remained obese into adulthood (persistent obesity, POB); participants with obesity starting in preadolescence and transitioned to non-obesity as adolescents (transient obesity; TOB).

RESULTS

Obesity was present in 47% of participants during at least one time-point. ROBs and POBs had higher insulin, HOMA-IR and HOMA-β, lower HOMA-S and DI, and higher prevalence of IR and NAFL at 23 years than NOBs, TOBs and FOBs. No differences were found in the β-cell functionality of NOBs, TOBs and FOBs.

CONCLUSIONS

Persistent and recent obesity are both related to IR, NAFL and a decline of β-cell function in emerging adulthood. Defeating obesity in childhood or adolescence allows reaching emerging adulthood with β-cell functioning similar to that of subjects who were NOB.

Hepatic steatosis relates to gastrointestinal microbiota changes in obese girls with polycystic ovary syndrome

Objective

Hepatic steatosis (HS) is common in adolescents with obesity and polycystic ovary syndrome (PCOS). Gut microbiota are altered in adults with obesity, HS, and PCOS, which may worsen metabolic outcomes, but similar data is lacking in youth.

Methods

Thirty-four adolescents with PCOS and obesity underwent stool and fasting blood collection, oral glucose tolerance testing, and MRI for hepatic fat fraction (HFF). Fecal bacteria were profiled by high-throughput 16S rRNA gene sequencing.

Results

50% had HS (N = 17, age 16.2±1.5 years, BMI 38±7 kg/m², HFF 9.8[6.5, 20.7]%) and 50% did not (N = 17, age 15.8±2.2 years, BMI 35±4 kg/m², HFF 3.8[2.6, 4.4]%). The groups showed no difference in bacterial α-diversity (richness p = 0.202; evenness p = 0.087; and diversity p = 0.069) or global difference in microbiota (β-diversity). Those with HS had lower % relative abundance (%RA) of Bacteroidetes (p = 0.013), Bacteroidaceae (p = 0.009), Porphyromonadaceae (p = 0.011), and Ruminococcaceae (p = 0.008), and higher Firmicutes:Bacteroidetes (F:B) ratio (47.8% vs. 4.3%, p = 0.018) and Streptococcaceae (p = 0.034). Bacterial taxa including phyla F:B ratio, Bacteroidetes, and family Bacteroidaceae, Ruminococcaceae and Porphyromonadaceae correlated with metabolic markers.

Conclusions

Obese adolescents with PCOS and HS have differences in composition of gut microbiota, which correlate with metabolic markers, suggesting a modifying role of gut microbiota in HS and PCOS.

Relationship between triglyceride glucose index and the incidence of non-alcoholic fatty liver disease in the elderly: a retrospective cohort study in China

OBJECTIVE

Non-alcoholic fatty liver disease (NAFLD) is one of the major causes of liver-related diseases but relationship between triglyceride glucose (TyG) and NAFLD in the elderly is not reported yet. In this study, we investigated the role of TyG index for predicting the incidence of NAFLD in the elderly.

DESIGN AND SETTING

This is a prospective cohort study in Henan, China, from 2011 to 2018.

PARTICIPANTS AND METHODS

In total, 46 693 elderly who participated in a routine physical examination programme from 2011 to 2018 were included in this study. TyG index was calculated as ln (fasting triglyceride (mg/dL)×fasting plasma glucose (mg/dL)/2), while NAFLD was defined as hepatic steatosis after excluding other causes based on the results of abdominal ultrasonography; Cox regression model was performed to explore the relationship between TyG index and NAFLD. Also, mediation effect was used to analyse the role of the TyG index in WHtR (waist-to-height ratio) and NAFLD.

RESULTS

During the 149 041 person-years follow-up, a total of 5660 NAFLD events occurred (3.80/100 person-years). After adjusting for potential confounding factors, quartiles 4 of TyG index significantly increased the incidence of NAFLD compared with quartile 1, the HRs and 95% CI were 1.314 (1.234 to 1.457). In addition, TyG index played a partial mediating role in the relationship between WHtR and NAFLD and indirect effect was 1.009 (1.006 to 1.011).

CONCLUSION

Higher TyG index was associated with higher risk of NAFLD in the aged, and therefore, TyG index may be a novel predictor for incidence of NAFLD. Further, regular examination and evaluation of the TyG index might be useful for controlling the occurrence of NAFLD.

Abnormal metabolic processes involved in the pathogenesis of non-alcoholic fatty liver disease (Review)

Non-alcoholic fatty liver disease (NAFLD) is one of the most common chronic liver diseases and can lead to liver cirrhosis or liver cancer in severe cases. In recent years, the incidence of NAFLD has increased substantially. The trend has continued to increase and has become a key point of concern for health systems. NAFLD is often associated with metabolic abnormalities caused by increased visceral obesity, including insulin resistance, diabetes mellitus, hypertension, dyslipidemia, atherosclerosis and systemic microinflammation. Therefore, the pathophysiological mechanisms of NAFLD must be clarified to develop new drug treatment strategies. Recently, researchers have conducted numerous studies on the pathogenesis of NAFLD and have identified various important regulatory factors and potential molecular mechanisms, providing new targets and a theoretical basis for the treatment of NAFLD. However, the pathogenesis of NAFLD is extremely complex and involves the interrelationship and influence of multiple organs and systems. Therefore, the condition must be explored further. In the present review, the abnormal metabolic process, including glucose, lipid, amino acid, bile acid and iron metabolism are reviewed. It was concluded that NAFLD is associated with an imbalanced metabolic network that involves glucose, lipids, amino acids, bile acids and iron, and lipid metabolism is the core metabolic process. The current study aimed to provide evidence and hypotheses for research and clinical treatment of NAFLD.

Drug discovery and treatment paradigms in nonalcoholic steatohepatitis

Nonalcoholic fatty liver disease (NAFLD) is the most common chronic liver disease in western populations, and is closely associated with features of the metabolic syndrome. The burden of disease is set to rise exponentially, and this is further compounded by the lack of good medications. In addition, these patients tend to have multiple comorbidities that may not be adequately managed. In this article, we review the biological basis of potential therapies in nonalcoholic steatohepatitis (NASH), the current drugs being tested in clinical trials, as well some practical considerations in managing patients in the clinic.

Role of Androgen in Liver Fat Content in Women: Metabolically Advantageous or Disadvantageous?

OBJECTIVE

Androgens have a controversial effect on liver fat content (LFC) in androgen-excess females and androgen-deficient males. Polycystic ovarian syndrome (PCOS) is often associated with hyperandrogenism and nonalcoholic fatty liver disease. The aim of this study was to explore the association between hyperandrogenemia and increased liver fat content in women with PCOS, independent of other metabolic parameters.

METHODS

This case series study included 501 women with PCOS and 112 aged-matched controls in the outpatient department of a tertiary hospital. Anthropometric measurements, hepatic and renal function, glucose and lipid metabolism parameters, and sex hormones were examined in these women. LFC was measured by quantitative ultrasonography.

RESULTS

Women with hyperandrogenism (P<.001), an oligomenorrhoea/anovulation phenotype (P = .0064), and a diagnosis of PCOS (P<.001) had higher LFC. Androgen level is an important factor among the 9 independent risk factors of LFC (P = .0239) and may have a dimorphic impact on LFC. In all women, when the free androgen index (FAI) was less than 41.94, LFC increased with the elevated FAI; when the FAI was greater than 41.94, LFC decreased with the elevated FAI (P<.001). In women with PCOS, receiver operating characteristic curve analysis demonstrated that LFC could at least partially predict impaired glucose regulation, impaired lipid metabolism, and insulin resistance (P<.0001 for all).

CONCLUSION

Androgen level is associated with LFC in dimorphic directions. LFC may be a predictive factor of insulin resistance, impaired glucose regulation, and impaired lipid metabolism in women with PCOS.

The Gut Microbiota and Its Metabolites, Novel Targets for Treating and Preventing Non-Alcoholic Fatty Liver Disease

Non-alcoholic fatty liver disease (NAFLD) is one of the most prevalent metabolic disorders worldwide, along with obesity and type 2 diabetes. NAFLD involves a series of liver abnormalities from simple hepatic steatosis to non-alcoholic steatohepatitis, which can ultimately lead to liver cirrhosis and cancer. The gut-liver axis plays an important role in the development of NAFLD, which depends mainly on regulation of the gut microbiota and its bacterial products. These intestinal bacterial species and their metabolites, including bile acids, tryptophan catabolites, and branched-chain amino acids, regulate adipose tissue and intestinal homeostasis and contribute to the pathogenesis of NAFLD/non-alcoholic steatohepatitis. In this review, the current evidence regarding the key role of the gut microbiota and its metabolites in the pathogenesis and development of NAFLD is highlighted, and the advances in the progression and applied prospects of gut microbiota-targeted dietary and exercise therapies is also discussed.

β-Hydroxybutyrate is reduced in humans with obesity-related NAFLD and displays a dose-dependent effect on skeletal muscle mitochondrial respiration in vitro

Nonalcoholic fatty liver disease (NAFLD) is characterized by hepatic fat accumulation and impaired insulin sensitivity. Reduced hepatic ketogenesis may promote these pathologies, but data are inconclusive in humans and the link between NAFLD and reduced insulin sensitivity remains obscure. We investigated individuals with obesity-related NAFLD and hypothesized that β-hydroxybutyrate (βOHB; the predominant ketone species) would be reduced and related to hepatic fat accumulation and insulin sensitivity. Furthermore, we hypothesized that ketones would impact skeletal muscle mitochondrial respiration in vitro. Hepatic fat was assessed by ¹H-MRS in 22 participants in a parallel design, case control study [Control: n = 7, age 50 ± 6 yr, body mass index (BMI) 30 ± 1 kg/m²; NAFLD: n = 15, age 57 ± 3 yr, BMI 35 ± 1 kg/m²]. Plasma assessments were conducted in the fasted state. Whole body insulin sensitivity was determined by the gold-standard hyperinsulinemic-euglycemic clamp. The effect of ketone dose (0.5-5.0 mM) on mitochondrial respiration was conducted in human skeletal muscle cell culture. Fasting βOHB, a surrogate measure of hepatic ketogenesis, was reduced in NAFLD (-15.6%, P < 0.01) and correlated negatively with liver fat (r² = 0.21, P = 0.03) and positively with insulin sensitivity (r² = 0.30, P = 0.01). Skeletal muscle mitochondrial oxygen consumption increased with low-dose ketones, attributable to increases in basal respiration (135%, P < 0.05) and ATP-linked oxygen consumption (136%, P < 0.05). NAFLD pathophysiology includes impaired hepatic ketogenesis, which is associated with hepatic fat accumulation and impaired insulin sensitivity. This reduced capacity to produce ketones may be a potential link between NAFLD and NAFLD-associated reductions in whole body insulin sensitivity, whereby ketone concentrations impact skeletal muscle mitochondrial respiration.

Chia (Salvia hispanica)-supplemented diet ameliorates non-alcoholic fatty liver disease and its metabolic abnormalities in humans

Background

Non-alcoholic fatty liver disease (NAFLD) is a public health problem lacking an approved pharmacological treatment. Omega-3 fatty acids have shown to reverse NAFLD. Chia is a seed rich in α-linolenic acid (ALA), antioxidants, and fiber; therefore, it could be useful to treat NAFLD.

Methods

In a single arm experimental design study, the effect of 25 g/day of milled chia was assessed in 25 patients with NAFLD. After two weeks of dietary stabilization (basal condition) and eight weeks of a chia-supplemented isocaloric diet, liver:spleen attenuation index and visceral abdominal fat (VAF) were measured by computed tomography. Lipids, lipoproteins, free fatty acids (FFA), and ALA plasma concentrations were also determined.

Results

Dietary chia supplementation induced an increase in plasma ALA concentration (75%) and dietary fiber (55%) consumption. After chia supplementation, VAF (9%), body weight (1.4%), total cholesterol (2.5%), non-high density lipoprotein cholesterol (3.2%), and circulating FFA (8%) decreased. Furthermore, NAFLD regressed in 52% of the treated patients (P < 0.05 for all).

Conclusions

The results of the present study show that 25 g/day of milled chia ameliorates NAFLD. Chia is an accessible vegetal source of omega-3 fatty acids, antioxidants, and fiber, which could have the potential to prevent metabolic abnormalities in NAFLD patients. Considering that there is no pharmacological treatment approved for NAFLD, the findings of the present study suggest that a chia-supplemented diet could be an innovative alternative to control this disease.

Retrospectively registered

https://clinicaltrials.gov/show/NCT03942822

Long noncoding RNA CCAT1 inhibits miR-613 to promote nonalcoholic fatty liver disease via increasing LXRα transcription

Nonalcoholic fatty liver disease (NAFLD) is regarded as a threat to public health; however, the pathologic mechanism of NAFLD is not fully understood. We attempted to identify abnormally expressed long noncoding RNA (lncRNAs) and messenger RNA that may affect the occurrence and development of NAFLD in this study. The expression of differentially expressed lncRNAs in NAFLD was determined in oleic acid (OA)-treated L02 cells, and the functions of CCAT1 in lipid droplet formation were evaluated in vitro. Differentially expressed genes (DEGs) were analyzed by microarray analysis, and DEGs related to CCTA1 were selected and verified by weighted correlation network analysis. The dynamic effects of LXRα and CCTA1 on lipid droplet formation and predicted binding was examined. The binding between miR-631 and CCAT1 and LXRα was verified. The dynamic effects of miR-613 inhibition and CCTA1 silencing on lipid droplet formation were examined. The expression and correlations of miR-631, CCAT1, and LXRα were determined in tissue samples. As the results show, CCAT1 was induced by OA and upregulated in NAFLD clinical samples. CCAT1 silencing significantly suppressed lipid droplet accumulation in vitro. LXRα was positively correlated with CCAT1. By inhibiting miR-613, CCAT1 increased the transcription of LXRα and promoted LXRα expression. The expression of LXRα was significantly increased in NAFLD tissues and was positively correlated with CCAT1. In conclusion, CCAT1 increases LXRα transcription by serving as a competing endogenous RNA for miR-613 in an LXRE-dependent manner, thereby promoting lipid droplet formation and NAFLD. CCAT1 and LXRα might be potent targets for NAFLD treatment.

Inflexibility of the plasma miRNA response following a high-carbohydrate meal in overweight insulin-resistant women

Context

Metabolic inflexibility is a characteristic of insulin resistance, limiting the ability to transiently regulate oxidative metabolism and gene expression in response to nutrient availability. Little is known of the flexibility of post-transcriptional regulation, including circulatory miRNAs (c-miRNAs).

Design

The abundances of targeted c-miRNAs, with reported functions in metabolic regulation, were analysed in response to a high-carbohydrate meal in healthy weight insulin-sensitive (IS) and overweight insulin-resistant (IR) women.

Participants

Age-matched healthy weight IS (n = 20, BMI = 24.3 ± 0.70) and overweight IR (n = 20, BMI = 28.6 ± 0.67) women.

Methods

An abundance of c-miRNAs was quantified prior to and following a high-carbohydrate breakfast meal (2500 kJ; 50% carbohydrate, 20% fat and 27% protein). Target genes of the differentially regulated c-miRNA were measured in RNA extracted from circulatory peripheral blood mononuclear cells (PBMCs).

Results

In healthy weight IS women, both miR-15a-5p (p = 0.03) and miR-17-5p (p < 0.01) levels were halved at 4 h post-meal. These miRNA remained unaltered following the same meal in the overweight IR women. Furthermore, amongst genes targeted by these miRNA, CPT1A (p = 0.01) and IL8 (p = 0.03) had also reduced expression 4 h post-meal only in the healthy weight IS women.

Conclusions

The study findings provide preliminary evidence for a possible extension of metabolic inflexibility to include c-miRNAs.

Trial registration

The clinical trial is registered with Australian New Zealand Clinical Trials Registry under Trial registration: ANZCTR: ACTRN12615001108505. Registered on 21 October 2015.

Nonalcoholic fatty liver disease in women with polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) affects 6-15% of women of reproductive age. Nonalcoholic fatty liver disease (NAFLD) affects 25-30% of the general population and its prevalence increases in parallel with the epidemics of obesity and type 2 diabetes mellitus. A growing body of evidence suggests that NAFLD and PCOS quite often co-exist. The aim of this article is to summarize and critically appraise the literature regarding: (1) the rates of co-existence of the two entities, (2) the possible pathophysiological links, (3) the proper diagnostic assessment and (4) the appropriate management of women with NAFLD and PCOS. Data from clinical studies and meta-analyses indicate a higher prevalence of NAFLD in women with PCOS ranging from 34% to 70% compared with 14% to 34% in healthy women. Inversely, women with NAFLD are more often diagnosed with PCOS. Insulin resistance (IR) and hyperandrogenism are two main potential pathophysiological links between the two entities. In this regard, IR seems to interplay with obesity and hyperandrogenism, thus affecting NAFLD and PCOS and being affected by them. Women with PCOS, particularly those with IR and/or hyperandrogenism, are suggested to be screened for NAFLD, while premenopausal women with NAFLD is suggested to be screened for PCOS. Lifestyle recommendations with a change in dietary habits, weight loss and exercise, constitute currently the cornerstone of the management of both NAFLD and PCOS. Insulin sensitizers maybe used for the treatment of these women, while there are limited promising data for the use of liraglutide.

Sarcopoterium spinosum Inhibited the Development of Non-Alcoholic Steatosis and Steatohepatitis in Mice

Non-alcoholic fatty liver disease (NAFLD) is a comorbidity of obesity, which gradually develops from hepatic steatosis into steatohepatitis (NASH) and eventually even into fibrosis or hepatic carcinoma. To date, there has been no specific and effective treatment for NAFLD. Sarcopoterium spinosum extract (SSE) was found to improve insulin sensitivity. Recognizing the intimate link between insulin resistance and NAFLD, the aim of this study was to investigate the effectivity of SSE in the prevention and management of NAFLD at various severities. SSE was given to high-fat diet (HFD)-fed mice (steatosis model) or to mice given a Western diet (WD) in the short or long term (NASH prevention or treatment, respectively). SSE reduced body weight accumulation, improved glucose tolerance and insulin sensitivity and prevented the development of hepatic steatosis. SSE also blocked the progression of liver disease toward NASH in a dose-dependent manner. The expression of genes involved in lipid metabolism, inflammation, and antioxidant machinery was regulated by SSE in both models of steatosis and NASH development. However, SSE failed to reverse the hepatic damage in the advanced model of NASH. In summary, SSE might be considered as a botanical supplement for the prevention and treatment of hepatic steatosis, and for slowing the deterioration toward NASH.

Sinapine reduces non-alcoholic fatty liver disease in mice by modulating the composition of the gut microbiota

Non-alcoholic fatty liver disease (NAFLD) is associated with low-grade chronic inflammation and intestinal dysbiosis. In this study, we investigated the potential benefits of sinapine, a rapeseed polyphenol known to exert anti-inflammatory and anti-oxidant effects, on high-fat diet (HFD)-induced NAFLD in C57BL/6 J mice and the underlying mechanisms. Four week-old mice were randomly divided into four groups and fed a low-fat diet (LFD), a HFD, a HFD with common rapeseed oil (HFD + CRO) and a HFD with sinapine in rapeseed oil (HFD + SRO) for 12 weeks. Supplementation with sinapine reduced the body weight of HFD mice by 10.99%, and decreased the levels of TG and LDL-C by 15.67% and 73.62%, respectively. In addition, sinapine also suppressed the intestinal NF-κB and TNF-α expressions and enhanced the adipose tissue IRS-1 expression in the HFD mice (P < 0.05). In terms of effects on the gut microbiota, sinapine induced a decrease in the ratio of Firmicutes to Bacteroidetes and increased the abundance of probiotics, such as Lactobacillaceae, Akkermansiaceae and Blautia, along with metabolite short-chain fatty acid (SCFA)-mediated upregulation of G protein-coupled receptor 43 (GPR43) to inhibit expression of inflammatory factors. Our collective results strongly supported the fact that the utility of sinapine as a prebiotic agent could prevent gut dysbiosis and obesity-related chronic diseases, such as insulin resistance (IR) and NAFLD.

Lipidomic biomarkers and mechanisms of lipotoxicity in non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) represents the most common form of chronic liver disease worldwide (about 25% of the general population) and 3-5% of patients develop non-alcoholic steatohepatitis (NASH), characterized by hepatocytes damage, inflammation and fibrosis, which increase the risk of developing liver failure, cirrhosis and hepatocellular carcinoma. The pathogenesis of NAFLD, particularly the mechanisms whereby a minority of patients develop a more severe phenotype, is still incompletely understood. In this review we examine the available literature on initial mechanisms of hepatocellular damage and inflammation, deriving from toxic effects of excess lipids. Accumulating data indicate that the total amount of triglycerides stored in the liver cells is not the main determinant of lipotoxicity and that specific lipid classes act as damaging agents. These lipotoxic species affect the cell behavior via multiple mechanisms, including activation of death receptors, endoplasmic reticulum stress, modification of mitochondrial function and oxidative stress. The gut microbiota, which provides signals through the intestine to the liver, is also reported to play a key role in lipotoxicity. Finally, we summarize the most recent lipidomic strategies utilized to explore the liver lipidome and its modifications in the course of NALFD. These include measures of lipid profiles in blood plasma and erythrocyte membranes that can surrogate to some extent lipid investigation in the liver.

From circadian clocks to non-alcoholic fatty liver disease

Introduction: The circadian rhythm is an integral regulator of various endocrine processes in the body, including sleep-wake cycles, hormonal regulation, and metabolism. In addition to metabolic, genetic, and environmental factors, a dysregulated circadian rhythm resulting from lifestyle changes has been implicated in the pathogenesis of nonalcoholic fatty liver disease (NAFLD). An accumulating body of evidence also supports strong association between NAFLD and metabolic disorder, the pathogenesis of which is related to periodic fluctuations in hormonal homeostasis. It is clear that endocrine and circadian rhythms are tightly interconnected. Generally, the circadian rhythm regulates flux patterns of physiological functions. The present review will discuss the modulation of bodily processes by the circadian rhythm with specific attention to the regulation of NAFLD by leptin and related hormones.Areas covered: PubMed/MEDLINE was searched for articles related to concomitant occurrence of NAFLD and T2DM between January 1995 and September 2019. Areas covered included epidemiological, physiology and pathophysiology aspects.Expert opinion: NAFLD and NASH are increasingly prevalent and may be largely mitigated with effective lifestyle modification and, potentially, circadian rhythm stabilization. Improved knowledge of the specific pathogenesis of NAFLD in addition to enhanced diagnostic screening tools and prediction of future disease burden is imperative.

From "two hit theory" to "multiple hit theory": Implications of evolution of pathogenesis concepts for treatment of non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) is becoming a burgeoning and burdensome public health problem worldwide, along with diabetes and metabolic syndrome. In the NAFLD spectrum, non-alcoholic steatohepatitis can progress to hepatic fibrosis, especially progressive fibrosis, which can lead to cirrhosis or even hepatocellular carcinoma. However, the pathogenesis of NAFLD is extremely complex and has not yet been fully elucidated, thus there is a lack of effective treatment. In recent years, the classic "two-hit" hypothesis has been gradually surpassed and supplemented by a great deal of findings, and the "multiple hit" hypothesis has been proposed and is being accepted. The study on the interaction among cellular and molecular mechanisms, environmental and genetic factors has revealed a number of critical targets in the pathogenesis of NAFLD, providing broad directions for the development of diagnostic markers and targeted therapeutic drugs. Here we elaborate the latest advances in understanding the pathogenesis of NAFLD from multiple perspectives, in order to analyze and evaluate the prospect of developing diagnostic biomarkers and therapeutic targets based on those pathogeneses.