A choline-deficient diet exacerbates fatty liver but attenuates insulin resistance and glucose intolerance in mice fed a high-fat diet

The ferroptosis mediator ACSL4 fails to prevent disease progression in mouse models of MASLD

BACKGROUND

Metabolic dysfunction-associated steatotic liver disease (MASLD) is an increasingly prevalent condition and a major risk factor for chronic liver damage, potentially leading to steatohepatitis and HCC. It is already known that patients with MASLD show increased systemic and hepatic iron concentrations as well as perturbed lipid metabolism, suggesting the involvement of ferroptosis in the development and progression of MASLD. Consequently, inhibition of ferroptosis represents a potential therapeutic option for patients with MASLD.

METHODS

We investigated whether liver parenchymal cell-specific deletion (LPC-KO) of the pro-ferroptotic gene acyl-CoA synthetase long-chain family member 4 (ACSL4LPC-KO) reduces MASLD onset and progression in mice. ACSL4LPC-KO and wild-type littermates were fed a choline-deficient high-fat diet (CD-HFD) or a Western diet for 20 weeks (CD-HFD and Western diet) or 40 weeks (CD-HFD only) to monitor MASLD progression and metabolic syndrome development.

RESULTS

In contrast to the recently published studies by Duan et al, our results show no significant differences between ACSL4LPC-KO and wild-type mice with regard to the development of MASLD or the progression of metabolic syndrome. Furthermore, no differences were observed in metabolic parameters (ie, weight gain, glucose tolerance test, hepatic steatosis) or MASLD-associated inflammatory response.

CONCLUSIONS

Our analyses, therefore, suggest that loss of ACSL4 has no effect on the progression of MASLD induced by CD-HFD or the Western diet. The discrepancy between our and previously published results could be due to differences in the diets or the influence of a distinct microbiome, so the results obtained with hepatocyte-specific ACSL4LPC-KO should be taken with caution.

Gut microbiota dysbiosis contributes to choline unavailability and NAFLD development

OBJECTIVES

Non-alcoholic fatty Liver Disease (NAFLD) poses a growing global health concern, yet its complex aetiology remains incompletely understood. Emerging evidence implicates the gut microbiome and choline metabolism in NAFLD pathogenesis. This study aims to elucidate the association of choline-consuming bacteria in gut microbiome with choline level.

METHODS

A population comprising 85 NAFLD patients and 30 healthy controls was selected. DNA extraction from stool samples was conducted using the FavorPrep™ Stool DNA Isolation Mini Kit, followed by polymerase chain reaction (PCR) detection of choline-consuming bacterial strains and quantitative PCR (qPCR) for Cut C gene expression. Choline content measurement was performed using fluorescence high-performance liquid chromatography (FL-HPLC).

RESULTS

Our findings revealed a significant reduction in choline levels among NAFLD patients compared to healthy controls. ROC curve analysis demonstrated choline levels and Cut C expression as a promising diagnostic tool for NAFLD, with high sensitivity and specificity. The microbial analysis identified specific choline-consuming bacteria enriched in NAFLD patients, notably Anarococcus Hydrogenalis and Clostridium asparagiforme. This was consistent with higher Cut C gene expression in patients compared to healthy individuals, which is responsible for encoding an enzyme to consume choline by these bacteria.

CONCLUSION

The current study gives a possible association between gut microbiota and the development of NAFLD, possibly due to an alteration in choline bioavailability. Further research is required to determine whether gut bacteria alter in the context of NAFLD or a change in their composition might lead to NAFLD progression, possibly via alternation in choline bioavailability.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s40200-024-01511-6.

Unlocking the gut-liver axis: microbial contributions to the pathogenesis of metabolic-associated fatty liver disease

Metabolic dysfunction-associated fatty liver disease (MAFLD) is a complex metabolic disorder characterized by hepatic lipid accumulation and subsequent inflammation. This condition is closely linked to metabolic syndrome and obesity, with its prevalence rising due to sedentary lifestyles and high-calorie diets. The pathogenesis of MAFLD involves multiple factors, including insulin resistance, lipotoxicity, oxidative stress, and inflammatory responses. The gut microbiota plays a crucial role in MAFLD development, with dysbiosis contributing to liver inflammation through various mechanisms, such as enhanced intestinal permeability and the translocation of bacterial products like lipopolysaccharide (LPS). Microbial metabolites, including short-chain fatty acids (SCFAs) and bile acids, influence hepatic function and immune responses, with potential implications for disease progression. Specific gut microbiome signatures have been identified in MAFLD patients, offering potential diagnostic and therapeutic targets. Moreover, gut-derived toxins, such as endotoxins, lipopolysaccharides, trimethylamine-N-oxide and bacterial metabolites, significantly influence liver damage and inflammation, highlighting the complex interplay between the gut microbiome and hepatic health. This review comprehensively examines the complex interplay between the gut microbiota and MAFLD, focusing on underlying pathogenic mechanisms, potential biomarkers, and emerging microbiome-targeted therapeutic strategies for disease management.

Protective effects of Kaempferol on hepatic apoptosis via miR-26a-5p enhancement and regulation of TLR4/NF-κB and PKCδ in a rat model of nonalcoholic fatty liver

This study aimed to evaluate kaempferol's, a dietary flavonoid widely present in plants, potential impact on nonalcoholic fatty liver disease (NAFLD) and its underlying mechanisms. In this study, 60 adult male rats were used and divided into a control group receiving a standard pellet diet, a kaempferol-treated group receiving kaempferol (250 mg/kg), a high-fat diet (HFD) group receiving HFD, and a kaempferol-treated HFD group. At the end of the experiment, the total lipid profile and liver enzymes were assayed in the serum. Additionally, oxidative stress (malondialdehyde and superoxide dismutase), inflammatory (tumor necrosis factor-alpha), apoptotic (caspase 3) markers, and nuclear factor-κB (NF-κB) and Toll-like receptor 4 (TLR4) concentrations were assayed in the liver tissues. Furthermore, miR-26a and PKCδ gene expression and beclin 1 immunohistochemical expression were determined in liver tissues. Our findings revealed that kaempferol significantly protects against the development of NAFLD in rats as well as inflammatory, oxidative, and apoptotic changes in their liver tissues by inhibiting PKCδ and the TLR-4/NF-κB signaling pathway while enhancing autophagy (Beclin 1 expression) via upregulating miR-26a expression. Accordingly, kaempferol holds promise as a complementary medication for the prevention of NAFLD. Nonetheless, more research is needed to fully understand its additional effects on liver tissue and to develop novel medications that activate miR-26a. A link between lipid metabolic abnormalities and miRNAs was demonstrated as upregulating miR-26a-5p by kaempferol mitigates the inflammation, apoptosis, and disrupted autophagy via regulating TLR4/NF-κB pathway and PKC in NAFLD.

Association of maternal gut microbial metabolites with gestational diabetes mellitus: evidence from an original case-control study, meta-analysis, and Mendelian randomization

BACKGROUND

The associations of gut microbial metabolites, such as trimethylamine N-oxide (TMAO), its precursors, and phenylacetylglutamine (PAGln), with the risk of gestational diabetes mellitus (GDM) remain unclear.

METHODS

Serum samples of 201 women with GDM and 201 matched controls were collected and then targeted metabolomics was performed to examine the metabolites of interest. Multivariable conditional logistic regression was applied to investigate the relationship between metabolites and GDM. Meta-analysis was performed to combine our results and four similar articles searched from online databases, and Mendelian randomization (MR) analysis was eventually conducted to explore the causalities.

RESULTS

In the case-control study, after dichotomization and comparing the higher versus the lower group, the adjusted odds ratio and 95% confidence interval of choline and L-carnitine with GDM were 2.124 (1.186-3.803) and 0.293 (0.134-0.638), respectively; but neutral relationships between TMAO, betaine, and PAGln with GDM were observed. The following meta-analysis consistently revealed that L-carnitine was negatively associated with GDM. However, MR analyses showed no evidence of causalities.

CONCLUSIONS

Maternal levels of L-carnitine were related to the risk of GDM in both the original case-control study and meta-analysis. However, we did not observe any genetic evidence to establish a causal relationship between this metabolite and GDM.

Untargeted and Targeted Lipidomics Unveil Dynamic Lipid Metabolism Alterations in Type 2 Diabetes

BACKGROUND

Type 2 diabetes mellitus (T2DM) is a complex metabolic disorder with a growing body of evidence suggesting the central role of lipid metabolism in its pathogenesis. However, the dynamic changes in lipid metabolism across different stages of T2DM remain understudied.

OBJECTIVE

This study aimed to elucidate the temporal alterations in lipid metabolism in T2DM using an integrated lipidomics approach.

METHOD

Serum samples from 155 subjects were analyzed using LC-MS-based lipidomics, including untargeted and targeted approaches.

RESULTS

We identified significant alterations in 44 lipid metabolites in newly diagnosed T2DM patients and 29 in high-risk individuals, compared with healthy controls. Key metabolic pathways such as sphingomyelin, phosphatidylcholine, and sterol ester metabolism were disrupted, highlighting the involvement of insulin resistance and oxidative stress in T2DM progression. Moreover, 13 lipid metabolites exhibited diagnostic potential for T2DN, showing consistent trends of increase or decrease as the disease progressed.

CONCLUSION

Our findings underscore the importance of lipid metabolism in T2D development and identify potential lipid biomarkers for early diagnosis and monitoring of disease progression, which contribute to paving the way for novel therapeutic strategies.

Improvement in Glycolipid Metabolism Parameters After Supplementing Fish Oil-Derived Omega-3 Fatty Acids Is Associated with Gut Microbiota and Lipid Metabolites in Type 2 Diabetes Mellitus

BACKGROUND/OBJECTIVES

This study aimed to investigate the effects of fish oil-derived omega-3 polyunsaturated fatty acids (omega-3 PUFAs) on gut microbiota and serum lipid metabolites in T2DM.

METHODS

In a three-month, randomized, double-blind, placebo-controlled study, 110 T2DM patients received either fish oil (n = 55) or corn oil (n = 55) capsules daily. Serum lipids, glycemic parameters, gut microbiota diversity, and lipidomics were assessed.

RESULTS

This study found that fish oil-derived omega-3 PUFAs intervention did not significantly lower the fasting plasma glucose levels when compared with the baseline level (p > 0.05). However, serum fasting blood glucose (p = 0.039), glycosylated hemoglobin levels (p = 0.048), HOMA-IR (p = 0.022), total cholesterol (p < 0.001), triglyceride (p = 0.034), LDL cholesterol (p = 0.048), and non-HDL levels (p = 0.046) were significantly lower in the fish oil group compared with the corn oil group after three months of intervention. Also, it altered glycerophospholipid metabolism and gut microbiota. After three months, the fish oil group showed a significantly lower abundance of Desulfobacterota compared with the corn oil control group (p = 0.003), with reduced levels of Colidextribacter (p = 0.002), Ralstonia (p = 0.021), and Klebsiella (p = 0.013). Conversely, the abundance of Limosilactobacillus (p = 0.017), Lactobacillus (p = 0.011), and Haemophilus (p = 0.018) increased significantly. In addition, relevant glycolipid metabolism indicators showed significant correlations with the altered profiles of serum lipid metabolites, intestinal bacteria, and fungi.

CONCLUSIONS

This study highlights the impact of fish oil-derived omega-3 PUFAs on intestinal microbiota structure and function in patients with type 2 diabetes. The observed decrease in pathogenic bacterial species and the enhancement of beneficial species may have significant implications for gut health and systemic inflammation, both of which are pivotal in managing diabetes. Further research is warranted to comprehensively elucidate the long-term benefits and underlying mechanisms of these microbiota alterations.

Cholinized-Polymer Functionalized Lipid-Based Drug Carriers Facilitate Liver Fibrosis Therapy via Ultrafast Liver-Targeting Delivery

Here, we report novel cholinized-polymer functionalized lipid-based nanoparticles (CP-LNPs) for rapid and highly effective delivery of drugs to the liver, achieving targeting within 10 min and nearly 100% efficiency. In this study, CP-LNPs loaded with a promising antifibrotic agent curcumin (CP-LNPs/Cur) significantly improved the stability of curcumin under physiological conditions and its distribution in the liver. In vitro experiments demonstrated that CP-LNPs/Cur effectively suppressed the proliferation and migration of activated hepatic stellate cells (aHSCs), as evidenced by the decreased expression of α-SMA. Moreover, CP-LNPs/Cur attenuated oxidative stress levels in hepatocytes while improving mitochondrial physiological activity. In vivo antifibrosis studies have shown that CP-LNPs/Cur only require a low dose to significantly alleviate liver injury and collagen deposition, thereby preventing the progression of liver fibrosis. These findings indicated that CP-LNPs exhibit great potential in liver fibrosis therapy benefiting from the novel targeting strategy.

Multiomics reveals the ameliorating effect and underlying mechanism of aqueous extracts of polygonatum sibiricum rhizome on obesity and liver fat accumulation in high-fat diet-fed mice

BACKGROUND

Polygonatum sibiricum polysaccharides protect against obesity and NAFLD. However, the potential effects of PS rhizome aqueous extracts (PSRwe) on adiposity and hepatic lipid accumulation remains unexplored.

PURPOSE

Elucidating the impact and underlying mechanism of PSRwe on HFD-induced obesity and liver fat depostition.

STUDY DESIGN

56 male mice, aged eight weeks, were divided into seven groups: Positive, four doses of PSRwe, Model, and Control. HFD was fed for eight weeks, followed by alternate-day gavage of orlistat and PSRwe for an additional eight-week period. Integrative analysis encompassing multiomics, physiological and histopathological, and biochemical indexes was employed.

METHODS

Body weight (BW); liver, fat and Lee's indexes; TC, TG, LDL-C, HDL-C, AST, ALT, FFA, leptin, and adiponectin in the liver and blood; TNFα, IL-6, and LPS in the colon, plasma, and liver; H&E, PAS and oil red O staining on adipose and liver samples were examined. OGTT and ITT were conducted The gut microbiome, microbial metabolome, colonic and liver transcriptome, plasma and liver metabolites were investigated.

RESULTS

PSRwe at the dosage of 7.5 mg/kg demonstrated significant and consistent reduction in BW and hepatic fat deposition than orlistat. PSRwe significantly decreased TC, TG, LDL-C, LEP, FFA levels in blood and liver. PSRwe significantly enhanced the relative abundance of probiotics including Akkermansia muciniphila, Bifidobacterium pseudolongum, Lactobacillus reuteri, and metabolic pathways including glycolysis and fatty acids β-oxidation. The 70 up-regulated microbial metabolites in PSRwe-treated mice mainly involved in nucleotides and amino acids metabolism, while 40 decreased metabolites primarily associated with lipid metabolism. The up-regulated colonic differentially expressed genes (DEGs) participate in JAK-STAT/PI3K-Akt/FoxO signaling pathway, serotonergic/cholinergic/glutamatergic synapses, while the down-regulated DEGs predominantly focused on fat absorption and transport. The up-regulated liver DEGs mainly concentrated on fatty acid oxidation and metabolism. Liver metabolisms revealed 131 differential metabolites, among which carnitine and oxidized lipids significantly increased in PSRwe-treated mice. In plasma, the 58 up-regulated metabolites mainly participate in co-factors/vitamins metabolism while 154 down-regulated ones in fatty acids biosynthesis. Comprehensive multiomics association analysis revealed significant associations between gut microbiota and colonic/liver gene expression, and suggested exogenous and endogenous betaine may be active compound in alleviating HFD-induced symptoms.

CONCLUSION

PSRwe effectively mitigate HFD-induced obesity and hepatic steatosis by increasing beneficial bacteria, reducing colonic fat digestion/absorption, increasing hepatic lipid metabolism, and elevating betaine levels.

Associations of Plasma Lipidomic Profiles with Uric Acid and Hyperuricemia Risk in Middle-Aged and Elderly Chinese

Little is known about the links of disturbed lipid metabolism with hyperuricemia (HUA). We aimed to investigate the associations of lipidomic profiles with uric acid (UA)/HUA and their modifying factors in middle-aged and elderly Chinese. A total of 350 lipids were quantified in 2247 community-based Chinese aged 50-70 years by high-coverage targeted lipidomics. HUA was defined by plasma UA > 420 μmol/L in men or > 360 μmol/L in women. The prevalence of HUA in this population was 10.4%. After multivariable adjustment including BMI and lifestyle, 123 lipids were significantly associated with UA, predominantly glycerolipids (GLs) and glycerophospholipids (GPs). Specifically, diacylglycerol [DAG (16:0/22:5), DAG (16:0/22:6), DAG (18:1/20:5), DAG (18:1/22:6)], phosphatidylcholine [PC (16:0/20:5)), and triacylglycerol (TAG (53:0)] were the most significant lipid signatures positively associated with HUA risk, while lysophosphatidylcholine (LPC (20:2)) was inversely associated with HUA risk (p < 0.05). Network analysis also showed a positive association between TAGs/PCs/DAGs contained module and HUA risk (p < 0.01). Notably, HUA-related lipids were associated with de novo lipogenesis fatty acids, especially 16:1n-7 (Spearman correlation coefficients = 0.32-0.41, p < 0.001). Reduced rank regression showed that increased aquatic products intake was correlated to elevated HUA risk and HUA-associated lipids; while high dairy consumption was correlated with low level of HUA-associated lipids (|factor loadings| ≥ 0.2). Moreover, mediation analyses suggested that the lipid-HUA associations were partially mediated by retinol-binding protein 4 (RBP4, mediation proportion 5-14%), an adipokine linked with dyslipidemia and insulin resistance. In conclusion, disturbed specific metabolisms of GLs and GPs were associated with high prevalent HUA, partially mediated by RBP4 and/or influenced by certain dietary factors.

Supplementary Information

The online version contains supplementary material available at 10.1007/s43657-024-00157-x.

MASLD does not affect fertility and senolytics fail to prevent MASLD progression in male mice

Senescent cells have been linked to the pathogenesis of metabolic dysfunction-associated steatotic liver disease (MASLD). However, the effectiveness of senolytic drugs in reducing liver damage in mice with MASLD is not clear. Additionally, MASLD has been reported to adversely affect male reproductive function. Therefore, this study aimed to evaluate the protective effect of senolytic drugs on liver damage and fertility in male mice with MASLD. Three-month-old male mice were fed a standard diet (SD) or a choline-deficient western diet (WD) until 9 months of age. At 6 months of age mice were randomized within dietary treatment groups into senolytic (dasatinib + quercetin [D + Q]; fisetin [FIS]) or vehicle control treatment groups. We found that mice fed choline-deficient WD had liver damage characteristic of MASLD, with increased liver size, triglycerides accumulation, fibrosis, along increased liver cellular senescence and liver and systemic inflammation. Senolytics were not able to reduce liver damage, senescence and systemic inflammation, suggesting limited efficacy in controlling WD-induced liver damage. Sperm quality and fertility remained unchanged in mice developing MASLD or receiving senolytics. Our data suggest that liver damage and senescence in mice developing MASLD is not reversible by the use of senolytics. Additionally, neither MASLD nor senolytics affected fertility in male mice.

Serum lipid metabolism characteristics and potential biomarkers in patients with unilateral sudden sensorineural hearing loss

BACKGROUND

Glycerophospholipids (GPLs) are essential for cell membrane structure and function. Sphingomyelin and its metabolites regulate cell growth, apoptosis, and stress responses. This study aimed to investigate lipid metabolism in patients experiencing sudden sensorineural hearing loss across all frequencies (AF-SSNHL).

METHODS

The study included 60 patients diagnosed with unilateral AF-SSNHL, among whom 30 patients had a level of hearing improvement ≥ 15 dB after 6 months of follow-up. A propensity score-matched (2:1) control group was used. Liquid chromatography‒mass spectrometry based untargeted lipidomics analysis combined with multivariate statistics was performed to investigate the lipids change. The "lipidome" R package and weighted gene co-expression network analysis (WGCNA) were utilised to assess the lipids' structural features and the association between lipids and hearing.

RESULTS

Lipidomics successfully differentiated the AF-SSNHL group from the control group, identifying 17 risk factors, mainly including phosphatidylcholine (PC), phosphatidylethanolamine (PE), and related metabolites. The ratios of lysophosphatidylcholine/PC, lysophosphatidylethanolamine/PE, and lysodimethylphosphatidylethanolamine/PE were upregulated, while some glycerophospholipid (GPL)-plasmalogens were downregulated in the AF-SSNHL group, indicating abnormal metabolism of GPLs. Trihexosylceramide (d34:1), PE (18:1e_22:5), and sphingomyelin (d40:3) were significantly different between responders and nonresponders, and positively correlated with hearing improvement. Additionally, the results of the WGCNA also suggested that partial GPL-plasmalogens were positively associated with hearing improvement.

CONCLUSION

AF-SSNHL patients exhibited abnormally high blood lipids and pronounced GPLs metabolic abnormalities. Sphingolipids and GPL-plasmalogens had an association with the level of hearing improvement. By understanding the lipid changes, clinicians may be able to predict the prognosis of hearing recovery and personalize treatment approaches.

Lactate transporter MCT1 in hepatic stellate cells promotes fibrotic collagen expression in nonalcoholic steatohepatitis

Circulating lactate is a fuel source for liver metabolism but may exacerbate metabolic diseases such as nonalcoholic steatohepatitis (NASH). Indeed, haploinsufficiency of lactate transporter monocarboxylate transporter 1 (MCT1) in mice reportedly promotes resistance to hepatic steatosis and inflammation. Here, we used adeno-associated virus (AAV) vectors to deliver thyroxin binding globulin (TBG)-Cre or lecithin-retinol acyltransferase (Lrat)-Cre to MCT1fl/fl mice on a choline-deficient, high-fat NASH diet to deplete hepatocyte or stellate cell MCT1, respectively. Stellate cell MCT1KO (AAV-Lrat-Cre) attenuated liver type 1 collagen protein expression and caused a downward trend in trichrome staining. MCT1 depletion in cultured human LX2 stellate cells also diminished collagen 1 protein expression. Tetra-ethylenglycol-cholesterol (Chol)-conjugated siRNAs, which enter all hepatic cell types, and hepatocyte-selective tri-N-acetyl galactosamine (GN)-conjugated siRNAs were then used to evaluate MCT1 function in a genetically obese NASH mouse model. MCT1 silencing by Chol-siRNA decreased liver collagen 1 levels, while hepatocyte-selective MCT1 depletion by AAV-TBG-Cre or by GN-siRNA unexpectedly increased collagen 1 and total fibrosis without effect on triglyceride accumulation. These findings demonstrate that stellate cell lactate transporter MCT1 significantly contributes to liver fibrosis through increased collagen 1 protein expression in vitro and in vivo, while hepatocyte MCT1 appears not to be an attractive therapeutic target for NASH.

Effect of the gut microbiome, plasma metabolome, peripheral cells, and inflammatory cytokines on obesity: a bidirectional two-sample Mendelian randomization study and mediation analysis

Background

Obesity is a metabolic and chronic inflammatory disease involving genetic and environmental factors. This study aimed to investigate the causal relationship among gut microbiota abundance, plasma metabolomics, peripheral cell (blood and immune cell) counts, inflammatory cytokines, and obesity.

Methods

Summary statistics of 191 gut microbiota traits (N = 18,340), 1,400 plasma metabolite traits (N = 8,299), 128 peripheral cell counts (blood cells, N = 408,112; immune cells, N = 3,757), 41 inflammatory cytokine traits (N = 8,293), and 6 obesity traits were obtained from publicly available genome-wide association studies. Two-sample Mendelian randomization (MR) analysis was applied to infer the causal links using inverse variance-weighted, maximum likelihood, MR-Egger, weighted median, weighted mode, and Wald ratio methods. Several sensitivity analyses were also utilized to ensure reliable MR results. Finally, we used mediation analysis to identify the pathway from gut microbiota to obesity mediated by plasma metabolites, peripheral cells, and inflammatory cytokines.

Results

MR revealed a causal effect of 44 gut microbiota taxa, 281 plasma metabolites, 27 peripheral cells, and 8 inflammatory cytokines on obesity. Among them, five shared causal gut microbiota taxa belonged to the phylum Actinobacteria, order Bifidobacteriales, family Bifidobacteriaceae, genus Lachnospiraceae UCG008, and species Eubacterium nodatum group. Furthermore, we screened 42 shared causal metabolites, 7 shared causal peripheral cells, and 1 shared causal inflammatory cytokine. Based on known causal metabolites, we observed that the metabolic pathways of D-arginine, D-ornithine, linoleic acid, and glycerophospholipid metabolism were closely related to obesity. Finally, mediation analysis revealed 20 mediation relationships, including the causal pathway from gut microbiota to obesity, mediated by 17 metabolites, 2 peripheral cells, and 1 inflammatory cytokine. Sensitivity analysis represented no heterogeneity or pleiotropy in this study.

Conclusion

Our findings support a causal relationship among gut microbiota, plasma metabolites, peripheral cells, inflammatory cytokines, and obesity. These biomarkers provide new insights into the mechanisms underlying obesity and contribute to its prevention, diagnosis, and treatment.

Serum betaine and dimethylglycine in mid-pregnancy and the risk of gestational diabetes mellitus: a case-control study

PURPOSE

To investigate the associations of choline, betaine, dimethylglycine (DMG), L-carnitine, and Trimethylamine-N-oxide (TMAO) with the risk of Gestational diabetes mellitus (GDM) as well as the markers of glucose homeostasis.

METHODS

We performed a case-control study including 200 diagnosed GDM cases and 200 controls matched by maternal age (±2 years) and gestational age (±2 weeks). Concentrations of serum metabolites were measured by the high-performance liquid chromatography - tandem mass spectrometry (HPLC-MS/MS).

RESULTS

Compared to the control group, GDM group had significantly lower serum betaine concentration and betaine/choline ratio, and higher DMG concentration. Furthermore, decreased betaine concentration and betaine/choline ratio, increased DMG concentration showed significant association with the risk of GDM. In addition, serum betaine concentrations were negatively associated with blood glucose levels at 1-h post-glucose load (OGTT-1h), and both betaine and L-carnitine concentrations were positively associated with 1,5-anhydroglucitol levels. Betaine/choline ratio was negatively associated with OGTT-1h and blood glucose levels at 2-h post-glucose load (OGTT-2h) and serum choline concentrations were negatively associated with fasting blood glucose and positively associated with OGTT-2h.

CONCLUSION

Decreased serum betaine concentrations and betaine/choline ratio, and elevated DMG concentrations could be significant risk factors for GDM. Furthermore, betaine may be associated with blood glucose regulation and short-term glycemic fluctuations.

Lactate transporter MCT1 in hepatic stellate cells promotes fibrotic collagen expression in nonalcoholic steatohepatitis

Circulating lactate is a fuel source for liver metabolism but may exacerbate metabolic diseases such as nonalcoholic steatohepatitis (NASH). Indeed, haploinsufficiency of lactate transporter monocarboxylate transporter 1 (MCT1) in mice reportedly promotes resistance to hepatic steatosis and inflammation. Here, we used adeno-associated virus (AAV) vectors to deliver thyroxin binding globulin (TBG)-Cre or lecithin-retinol acyltransferase (Lrat)-Cre to MCT1fl/fl mice on a choline deficient, high fat NASH diet to deplete hepatocyte or stellate cell MCT1, respectively. Stellate cell MCT1KO (AAV-Lrat-Cre) attenuated liver type 1 collagen protein expression and caused a downward trend in trichrome staining. MCT1 depletion in cultured human LX2 stellate cells also diminished collagen 1 protein expression. Tetra-ethylenglycol-cholesterol (Chol)-conjugated siRNAs, which enter all hepatic cell types, and hepatocyte-selective tri-N-acetyl galactosamine (GN)-conjugated siRNAs were then used to evaluate MCT1 function in a genetically obese NASH mouse model. MCT1 silencing by Chol-siRNA decreased liver collagen 1 levels, while hepatocyte-selective MCT1 depletion by AAV-TBG-Cre or by GN-siRNA unexpectedly increased collagen 1 and total fibrosis without effect on triglyceride accumulation. These findings demonstrate that stellate cell lactate transporter MCT1 significantly contributes to liver fibrosis through increased collagen 1 protein expression in vitro and in vivo, while hepatocyte MCT1 appears not to be an attractive therapeutic target for NASH.

Dyrk2 gene transfer suppresses hepatocarcinogenesis by promoting the degradation of Myc and Hras

Background & Aims

Hepatocellular carcinoma (HCC) is one of the most common cancers worldwide, and has a poor prognosis. However, the molecular mechanisms underlying hepatocarcinogenesis and progression remain unknown. In vitro gain- and loss-of-function analyses in cell lines and xenografts revealed that dual-specificity tyrosine-regulated kinase 2 (DYRK2) influences tumour growth in HCC.

Methods

To investigate the role of Dyrk2 during hepatocarcinogenesis, we developed liver-specific Dyrk2 conditional knockout mice and an in vivo gene delivery system with a hydrodynamic tail vein injection and the Sleeping Beauty transposon. The antitumour effects of Dyrk2 gene transfer were investigated in a murine autologous carcinogenesis model.

Results

Dyrk2 expression was reduced in tumours, and that its downregulation was induced before hepatocarcinogenesis. Dyrk2 gene transfer significantly suppressed carcinogenesis. It also suppresses Myc-induced de-differentiation and metabolic reprogramming, which favours proliferative, and malignant potential by altering gene profiles. Dyrk2 overexpression caused Myc and Hras degradation at the protein level rather than at the mRNA level, and this degradation mechanism was regulated by the proteasome. Immunohistochemical analyses revealed a negative correlation between DYRK2 expression and MYC and longer survival in patients with HCC with high-DYRK2 and low-MYC expressions.

Conclusions

Dyrk2 protects the liver from carcinogenesis by promoting Myc and Hras degradation. Our findings would pave the way for a novel therapeutic approach using DYRK2 gene transfer.

Impact and Implications

Hepatocellular carcinoma (HCC) is one of the most common cancers, with a poor prognosis. Hence, identifying molecules that can become promising targets for therapies is essential to improve mortality. No studies have clarified the association between DYRK2 and carcinogenesis, although DYRK2 is involved in tumour growth in various cancer cells. This is the first study to show that Dyrk2 expression decreases during hepatocarcinogenesis and that Dyrk2 gene transfer is an attractive approach with tumour suppressive activity against HCC by suppressing Myc-mediated de-differentiation and metabolic reprogramming that favours proliferative and malignant potential via Myc and Hras degradation.

Non-Alcoholic Fatty Liver Disease: Translating Disease Mechanisms into Therapeutics Using Animal Models

Nonalcoholic fatty liver disease (NAFLD) is a range of pathologies arising from fat accumulation in the liver in the absence of excess alcohol use or other causes of liver disease. Its complications include cirrhosis and liver failure, hepatocellular carcinoma, and eventual death. NAFLD is the most common cause of liver disease globally and is estimated to affect nearly one-third of individuals in the United States. Despite knowledge that the incidence and prevalence of NAFLD are increasing, the pathophysiology of the disease and its progression to cirrhosis remain insufficiently understood. The molecular pathogenesis of NAFLD involves insulin resistance, inflammation, oxidative stress, and endoplasmic reticulum stress. Better insight into these molecular pathways would allow for therapies that target specific stages of NAFLD. Preclinical animal models have aided in defining these mechanisms and have served as platforms for screening and testing of potential therapeutic approaches. In this review, we will discuss the cellular and molecular mechanisms thought to contribute to NAFLD, with a focus on the role of animal models in elucidating these mechanisms and in developing therapies.

Gut microbiota and obesity: an overview of microbiota to microbial-based therapies

The increasing prevalence of obesity and overweight is a significant public concern throughout the world. Obesity is a complex disorder involving an excessive amount of body fat. It is not just a cosmetic concern. It is a medical challenge that increases the risk of other diseases and health circumstances, such as diabetes, heart disease, high blood pressure and certain cancers. Environmental and genetic factors are involved in obesity as a significant metabolic disorder along with diabetes. Gut microbiota (GM) has a high potential for energy harvesting from the diet. In the current review, we aim to consider the role of GM, gut dysbiosis and significant therapies to treat obesity. Dietary modifications, probiotics, prebiotics, synbiotics compounds, using faecal microbiota transplant, and other microbial-based therapies are the strategies to intervene in obesity reducing improvement. Each of these factors serves through various mechanisms including a variety of receptors and compounds to control body weight. Trial and animal investigations have indicated that GM can affect both sides of the energy-balancing equation; first, as an influencing factor for energy utilisation from the diet and also as an influencing factor that regulates the host genes and energy storage and expenditure. All the investigated articles declare the clear and inevitable role of GM in obesity. Overall, obesity and obesity-relevant metabolic disorders are characterised by specific modifications in the human microbiota's composition and functions. The emerging therapeutic methods display positive and promising effects; however, further research must be done to update and complete existing knowledge.

Dietary choline and betaine intake, cardio-metabolic risk factors and prevalence of metabolic syndrome among overweight and obese adults

BACKGROUND

Choline is an important metabolite involved in phospholipids synthesis, including serum lipids, and is the immediate precursor of betaine. There are numerous studies with inconsistent results that evaluated the association between dietary choline intakes with cardiovascular risk factors. In addition, the association between dietary betaine and choline intakes with cardio-metabolic risk factors is not well studied. In the current study, our aim was to evaluate dietary choline and betaine intakes in the usual diet of obese individuals and to assess its association with serum lipids, blood pressure and glycemic markers among obese individuals.

METHODS

We recruited a total number of 359 obese people aged between 20 and 50 years in the present study. A semi-quantitative food frequency questionnaire (FFQ) was used for dietary assessment; dietary choline and betaine intakes were calculated using the United States Department of Agriculture (USDA) database. National cholesterol education program adult treatment panel (NCEP-ATP)-III criteria was used metabolic syndrome (MetS) definition. Enzymatic methods were used to assess biochemical variables. Body composition was measured with the bioelectrical impedance analysis (BIA) method.

RESULTS

Higher body mass index (BMI), waist to hip ratio (WHR), fat-free mass (FFM) and basal metabolic rate (BMR) were observed in higher tertiles of dietary choline intake (P < 0.01). There was no significant difference in terms of biochemical parameters among different tertiles of dietary choline intake, while systolic blood pressure (SBP) and diastolic blood pressure (DBP) were reduced in higher betaine tertiles (P < 0.05). For total dietary choline and betaine intakes, there was a reduction in DBP and low density lipoprotein (LDL) concentrations (P < 0.05). Also, a non-significant reduction in serum total cholesterol (TC), triglyceride (TG) and MetS prevalence was observed in higher tertiles of dietary choline and betaine intakes. After classification of the study population according to MetS status, there was no significant difference in biochemical variables in subjects with MetS (P > 0.05), while in the non-MetS group, SBP, DBP, TG and insulin levels reduced in higher tertiles of dietary betaine and choline (P > 0.05).

CONCLUSION

According to our findings, higher dietary intakes of choline and betaine were associated with lower levels of blood pressure and LDL concentrations among obese individuals. Further studies are warranted to confirm the results of the current study.

Innate-like T lymphocytes in chronic liver disease

In addition to its metabolic activities, it is now clear that the liver hosts a number of diverse immune cell types that control tissue homeostasis. Foremost among these are innate-like T lymphocytes, including natural killer T (NKT) and mucosal-associated innate T (MAIT) cells, which are a population of specialized T cells with innate characteristics that express semi-invariant T cell receptors with non-peptide antigen specificity. As primary liver residents, innate-like T cells have been associated with immune tolerance in the liver, but also with a number of hepatic diseases. Here, we focus on the biology of NKT and MAIT cells and how they operate during the course of chronic inflammatory diseases that eventually lead to hepatocellular carcinoma.

Single-Cell Analysis of Primary Liver Cancer in Mouse Models

Primary liver cancer (PLC), consisting mainly of hepatocellular carcinoma and intrahepatic cholangiocarcinoma, is one of the major causes of cancer-related mortality worldwide. The curative therapy for PLC is surgical resection and liver transplantation, but most PLCs are inoperable at diagnosis. Even after surgery, there is a high rate of tumor recurrence. There is an unmet clinical need to discover more effective treatment options for advanced PLCs. Pre-clinical mouse models in PLC research have played a critical role in identifying key oncogenic drivers and signaling pathways in hepatocarcinogenesis. Furthermore, recent advances in single-cell RNA sequencing (scRNA-seq) have provided an unprecedented degree of resolution in such characterization. In this review, we will summarize the recent studies that utilized pre-clinical mouse models with the combination of scRNA-seq to provide an understanding of different aspects of PLC. We will focus particularly on the potentially actionable targets regarding the cellular and molecular components. We anticipate that the findings in mouse models could complement those in patients. With more defined etiological background, mouse models may provide valuable insights.

The interplay between nonalcoholic fatty liver disease and atherosclerotic cardiovascular disease

Therapeutic approaches that lower circulating low-density lipoprotein (LDL)-cholesterol significantly reduced the burden of cardiovascular disease over the last decades. However, the persistent rise in the obesity epidemic is beginning to reverse this decline. Alongside obesity, the incidence of nonalcoholic fatty liver disease (NAFLD) has substantially increased in the last three decades. Currently, approximately one third of world population is affected by NAFLD. Notably, the presence of NAFLD and particularly its more severe form, nonalcoholic steatohepatitis (NASH), serves as an independent risk factor for atherosclerotic cardiovascular disease (ASCVD), thus, raising interest in the relationship between these two diseases. Importantly, ASCVD is the major cause of death in patients with NASH independent of traditional risk factors. Nevertheless, the pathophysiology linking NAFLD/NASH with ASCVD remains poorly understood. While dyslipidemia is a common risk factor underlying both diseases, therapies that lower circulating LDL-cholesterol are largely ineffective against NASH. While there are no approved pharmacological therapies for NASH, some of the most advanced drug candidates exacerbate atherogenic dyslipidemia, raising concerns regarding their adverse cardiovascular consequences. In this review, we address current gaps in our understanding of the mechanisms linking NAFLD/NASH and ASCVD, explore strategies to simultaneously model these diseases, evaluate emerging biomarkers that may be useful to diagnose the presence of both diseases, and discuss investigational approaches and ongoing clinical trials that potentially target both diseases.

Human CYP2B6 produces oxylipins from polyunsaturated fatty acids and reduces diet-induced obesity

Multiple factors in addition to over consumption lead to obesity and non-alcoholic fatty liver disease (NAFLD) in the United States and worldwide. CYP2B6 is the only human detoxification CYP whose loss is associated with obesity, and Cyp2b-null mice show greater diet-induced obesity with increased steatosis than wildtype mice. However, a putative mechanism has not been determined. LC-MS/MS revealed that CYP2B6 metabolizes PUFAs, with a preference for metabolism of ALA to 9-HOTrE and to a lesser extent 13-HOTrE with a preference for metabolism of PUFAs at the 9- and 13-positions. To further study the role of CYP2B6 in vivo, humanized-CYP2B6-transgenic (hCYP2B6-Tg) and Cyp2b-null mice were fed a 60% high-fat diet for 16 weeks. Compared to Cyp2b-null mice, hCYP2B6-Tg mice showed reduced weight gain and metabolic disease as measured by glucose tolerance tests, however hCYP2B6-Tg male mice showed increased liver triglycerides. Serum and liver oxylipin metabolite concentrations increased in male hCYP2B6-Tg mice, while only serum oxylipins increased in female hCYP2B6-Tg mice with the greatest increases in LA oxylipins metabolized at the 9 and 13-positions. Several of these oxylipins, specifically 9-HODE, 9-HOTrE, and 13-oxoODE, are PPAR agonists. RNA-seq data also demonstrated sexually dimorphic changes in gene expression related to nuclear receptor signaling, especially CAR > PPAR with qPCR suggesting PPARγ signaling is more likely than PPARα signaling in male mice. Overall, our data indicates that CYP2B6 is an anti-obesity enzyme, but probably to a lesser extent than murine Cyp2b's. Therefore, the inhibition of CYP2B6 by xenobiotics or dietary fats can exacerbate obesity and metabolic disease potentially through disrupted PUFA metabolism and the production of key lipid metabolites.

A Study of the Metabolic Pathways Affected by Gestational Diabetes Mellitus: Comparison with Type 2 Diabetes

BACKGROUND

Gestational diabetes mellitus (GDM) remains incompletely understood and increases the risk of developing Diabetes mellitus type 2 (DM2). Metabolomics provides insights etiology and pathogenesis of disease and discovery biomarkers for accurate detection. Nuclear magnetic resonance (NMR) spectroscopy is a key platform defining metabolic signatures in intact serum/plasma. In the present study, we used NMR-based analysis of macromolecules free-serum to accurately characterize the altered metabolic pathways of GDM and assessing their similarities to DM2. Our findings could contribute to the understanding of the pathophysiology of GDM and help in the identification of metabolomic markers of the disease.

METHODS

Sixty-two women with GDM matched with seventy-seven women without GDM (control group). ¹H NMR serum spectra were acquired on an 11.7 T Bruker Avance DRX NMR spectrometer.

RESULTS

We identified 55 metabolites in both groups, 25 of which were significantly altered in the GDM group. GDM group showed elevated levels of ketone bodies, 2-hydroxybutyrate and of some metabolic intermediates of branched-chain amino acids (BCAAs) and significantly lower levels of metabolites of one-carbon metabolism, energy production, purine metabolism, certain amino acids, 3-methyl-2-oxovalerate, ornithine, 2-aminobutyrate, taurine and trimethylamine N-oxide.

CONCLUSION

Metabolic pathways affected in GDM were beta-oxidation, ketone bodies metabolism, one-carbon metabolism, arginine and ornithine metabolism likewise in DM2, whereas BCAAs catabolism and aromatic amino acids metabolism were affected, but otherwise than in DM2.

Ethnic disparities attributed to the manifestation in and response to type 2 diabetes: insights from metabolomics

Type 2 diabetes (T2D) associated health disparities among different ethnicities have long been known. Ethnic variations also exist in T2D related comorbidities including insulin resistance, vascular complications and drug response. Genetic heterogeneity, dietary patterns, nutrient metabolism and gut microbiome composition attribute to ethnic disparities in both manifestation and progression of T2D. These factors differentially regulate the rate of metabolism and metabolic health. Metabolomics studies have indicated significant differences in carbohydrate, lipid and amino acid metabolism among ethnicities. Interestingly, genetic variations regulating lipid and amino acid metabolism might also contribute to inter-ethnic differences in T2D. Comprehensive and comparative metabolomics analysis between ethnicities might help to design personalized dietary regimen and newer therapeutic strategies. In the present review, we explore population based metabolomics data to identify inter-ethnic differences in metabolites and discuss how (a) genetic variations, (b) dietary patterns and (c) microbiome composition may attribute for such differences in T2D.

Associations of plasma glycerophospholipid profile with modifiable lifestyles and incident diabetes in middle-aged and older Chinese

AIMS/HYPOTHESIS

Glycerophospholipid (GPL) perturbance was linked to the pathogenesis of diabetes in animal studies but prospective studies in humans are rare, particularly in Asians. We aimed to investigate the associations between plasma GPLs and incident diabetes and to explore effects of lifestyle on the associations in a Chinese population.

METHODS

The study included 1877 community-dwelling Chinese individuals aged 50-70 years (751 men and 1126 women), free of diabetes at baseline and followed for 6 years. A total of 160 GPL species were quantified in plasma at baseline by using high-throughput targeted lipidomics. Log-Poisson regression was used to assess the associations between GPLs and incidence of diabetes.

RESULTS

Over the 6 years of follow-up, 499 participants (26.6%) developed diabetes. After multivariable adjustment, eight GPLs were positively associated with incident diabetes (RR_{per SD} 1.13-1.25; all false-discovery rate [FDR]-corrected p < 0.05), including five novel GLPs, namely phosphatidylcholines (PCs; 16:0/18:1, 18:0/16:1, 18:1/20:3), lysophosphatidylcholine (LPC; 20:3) and phosphatidylethanolamine (PE; 16:0/16:1), and three reported GPLs (PCs 16:0/16:1, 16:0/20:3 and 18:0/20:3). In network analysis, a PC-containing module was positively associated with incident diabetes (RR_{per SD} 1.16 [95% CI 1.06, 1.26]; FDR-corrected p < 0.05). Notably, three of the diabetes-associated PCs (16:0/16:1, 16:0/18:1 and 18:0/16:1) and PE (16:0/16:1) were associated not only with fatty acids in the de novo lipogenesis (DNL) pathway, especially 16:1n-7 (Spearman correlation coefficients = 0.35-0.62, p < 0.001), but also with an unhealthy dietary pattern high in refined grains and low in fish, dairy and soy products (|factor loadings| ≥0.2). When stratified by physical activity levels, the associations of the eight GPLs and the PC module with incident diabetes were stronger in participants with lower physical activity (RR_{per SD} 1.24-1.49, FDR-corrected p < 0.05) than in those with the median and higher physical activity levels (RR_{per SD} 1.03-1.12, FDR-corrected p ≥ 0.05; FDR-corrected p_interaction < 0.05).

CONCLUSIONS/INTERPRETATION

Eight GPLs, especially PCs associated with the DNL pathway, were positively associated with incident diabetes in a cohort of Chinese men and women. The associations were most prominent in participants with a low level of physical activity.

Optimal Dietary Intake Composition of Choline and Betaine Is Associated with Minimized Visceral Obesity-Related Hepatic Steatosis in a Case-Control Study

Few studies on humans have comprehensively evaluated the intake composition of methyl-donor nutrients (MDNs: choline, betaine, and folate) in relation to visceral obesity (VOB)-related hepatic steatosis (HS), the hallmark of non-alcoholic fatty liver diseases. In this case-control study, we recruited 105 patients with HS and 104 without HS (controls). HS was diagnosed through ultrasound examination. VOB was measured using a whole-body analyzer. MDN intake was assessed using a validated quantitative food frequency questionnaire. After adjustment for multiple HS risk factors, total choline intake was the most significant dietary determinant of HS in patients with VOB (Beta: -0.41, p = 0.01). Low intake of choline (<6.9 mg/kg body weight), betaine (<3.1 mg/kg body weight), and folate (<8.8 μg/kg body weight) predicted increased odds ratios (ORs) of VOB-related HS (choline: OR: 22, 95% confidence interval [CI]: 6.5-80; betaine: OR: 14, 95% CI: 4.4-50; and folate: OR: 19, 95% CI: 5.2-74). Combined high intake of choline and betaine, but not folate, was associated with an 81% reduction in VOB-related HS (OR: 0.19, 95% CI: 0.05-0.69). Our data suggest that the optimal intake of choline and betaine can minimize the risk of VOB-related HS in a threshold-dependent manner.

Local free fatty acids trigger the expression of lipopolysaccharide-binding protein in murine white adipose tissue

Although lipopolysaccharide (LPS)-binding protein (LBP) is an acute-phase protein mainly produced by hepatocytes, it has also been proposed to be a pro-inflammatory adipokine. Obesity and the consumption of a high-fat diet (HFD) are reportedly associated with elevated levels of LPS in plasma and free fatty acids (FFAs) in white adipose tissue (WAT). We examined whether circulating LPS or local FFAs are responsible for the HFD-induced increase of LBP in WAT. Male C57BL/6J mice were fed either a normal-fat diet (NFD) or an HFD. The mRNA levels in the liver and mesenteric WAT (mWAT), total FFA content in mWAT, and LBP and LPS concentrations in plasma were determined. The Lbp mRNA level in mWAT was higher in mice fed the HFD than in those fed the NFD for 3, 7, or 28 days or 14 weeks, whereas the hepatic Lbp mRNA level did not differ between the groups. The Lbp mRNA level in mWAT was also increased by the HFD in germ-free mice, which do not have gut microbiota, the source of LPS. The plasma LPS level did not show a significant correlation with the mWAT Lbp mRNA level. The total FFA content in mWAT was higher in mice fed the HFD than in those fed the NFD and positively correlated with the Lbp mRNA level. Supplementation with palmitic acid increased the Lbp mRNA level in 3T3-L1 adipocytes. We propose that local FFAs, but not circulating LPS, are the trigger for increased Lbp expression in mWAT of mice fed the HFD.

Integrating Choline and Specific Intestinal Microbiota to Classify Type 2 Diabetes in Adults: A Machine Learning Based Metagenomics Study

Emerging evidence is examining the precise role of intestinal microbiota in the pathogenesis of type 2 diabetes. The aim of this study was to investigate the association of intestinal microbiota and microbiota-generated metabolites with glucose metabolism systematically in a large cross-sectional study in China. 1160 subjects were divided into three groups based on their glucose level: normal glucose group (n=504), prediabetes group (n=394), and diabetes group (n=262). Plasma concentrations of TMAO, choline, betaine, and carnitine were measured. Intestinal microbiota was measured in a subgroup of 161 controls, 144 prediabetes and 56 diabetes by using metagenomics sequencing. We identified that plasma choline [Per SD of log-transformed change: odds ratio 1.36 (95 confidence interval 1.16, 1.58)] was positively, while betaine [0.77 (0.66, 0.89)] was negatively associated with diabetes, independently of TMAO. Individuals with diabetes could be accurately distinguished from controls by integrating data on choline, and certain microbiota species, as well as traditional risk factors (AUC=0.971). KOs associated with the carbohydrate metabolism pathway were enhanced in individuals with high choline level. The functional shift in the carbohydrate metabolism pathway in high choline group was driven by species Ruminococcus lactaris, Coprococcus catus and Prevotella copri. We demonstrated the potential ability for classifying diabetic population by choline and specific species, and provided a novel insight of choline metabolism linking the microbiota to impaired glucose metabolism and diabetes.

Recombinant human GLP-1 beinaglutide regulates lipid metabolism of adipose tissues in diet-induced obese mice

GLP-1 analogs are a class of glucose-lowering agents with multiple benefits in diabetes, but its role in adipose tissues remains to be elucidated. The aim of this study was to determine the action of recombinant human GLP-1 (rhGLP-1) Beinaglutide (BN) in the insulin sensitivity and lipid metabolism of adipose tissues. We have shown that, after BN injection, obese mice displayed lower body weight, fat mass, and plasma lipid levels. In addition, BN promoted the insulin sensitivity in the white adipose tissues. Furthermore, we have found that the BN treatment caused significant changes in content and composition of different lipid classes, including glycerolipids, glycerophospholipids, and sphingolipids, as well as expression of genes in lipid metabolic pathways in the adipose tissues. Taken together, our data demonstrate that BN could resist HFD-induced obesity by targeting the composition of major lipid classes and the expression of genes in lipid metabolism of adipose tissues.

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Recombinant human GLP-1 Beinaglutide (BN) reduces high-fat-diet-induced obesity

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BN increases insulin sensitivity of adipocytes in vivo and in vitro

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BN alters lipidomic and transcriptomic profiles in adipose tissues of obese mice

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BN promotes thermogenic gene expression in adipose tissues

Serum and Amniotic Fluid Metabolic Profile Changes in Response to Gestational Diabetes Mellitus and the Association with Maternal-Fetal Outcomes

This study was designed to identify serum and amniotic fluid (AF) metabolic profile changes in response to gestational diabetes mellitus (GDM) and explore the association with maternal-fetal outcomes. We established the GDM rat models by combining a high-fat diet (HFD) with an injection of low-dose streptozotocin (STZ), detected the fasting plasma glucose (FPG) of pregnant rats in the second and third trimester, and collected AF and fetal rats by cesarean section on gestational day 19 (GD19), as well as measuring the weight and crown-rump length (CRL) of fetal rats. We applied liquid chromatography-tandem mass spectrometry (LC-MS/MS) for the untargeted metabolomics analyses of serum and AF samples and then explored their correlation with maternal-fetal outcomes via the co-occurrence network. The results showed that 91 and 68 metabolites were upregulated and 125 and 78 metabolites were downregulated in serum and AF samples exposed to GDM, respectively. In maternal serum, the obvious alterations emerged in lipids and lipid-like molecules, while there were great changes in carbohydrate and carbohydrate conjugates, followed by amino acids, peptides, and analogs in amniotic fluid. The altered pathways both in serum and AF samples were amino acid, lipid, nucleotide, and vitamin metabolism pathways. In response to GDM, changes in the steroid hormone metabolic pathway occurred in serum, and an altered carbohydrate metabolism pathway was found in AF samples. Among differential metabolites in two kinds of samples, there were 34 common biochemicals shared by serum and AF samples, and a mutual significant association existed. These shared differential metabolites were implicated in several metabolism pathways, including choline, tryptophan, histidine, and nicotinate and nicotinamide metabolism, and among them, N1-methyl-4-pyridone-3-carboxamide, 5'-methylthioadenosine, and kynurenic acid were significantly associated with both maternal FPG and fetal growth. In conclusion, serum and AF metabolic profiles were remarkably altered in response to GDM. N1-Methyl-4-pyridone-3-carboxamide, 5'-methylthioadenosine, and kynurenic acid have the potential to be taken as biomarkers for maternal-fetal health status of GDM. The common and inter-related differential metabolites both in the serum and AF implied the feasibility of predicting fetal health outcomes via detecting the metabolites in maternal serum exposed to GDM.

Plasma choline and betaine and risks of cardiovascular events and recurrent stroke after ischemic stroke

BACKGROUND

Choline and betaine have been suggested to play a pivotal role in neurotransmitter synthesis, cell membrane integrity, and methyl-group metabolism, exerting neuroprotective effects in patients with various neurological disorders. However, population-based evidence on choline and betaine with subsequent cardiovascular events after stroke is rare.

OBJECTIVES

We aimed to prospectively investigate the relationships of circulating choline and betaine with cardiovascular events and recurrent stroke in patients with ischemic stroke.

METHODS

We performed a nested case-control study within the China Antihypertensive Trial in Acute Ischemic Stroke. A total of 323 cardiovascular events (including 264 recurrent strokes) and 323 controls (free of recurrent cardiovascular events) matched for age (±1 y), sex, and treatment group were included. The primary endpoint was a composite of cardiovascular events after ischemic stroke. Plasma choline and betaine were measured at baseline by ultra-high-performance LC-MS/MS. Conditional logistic regression models were applied, and discrimination, reclassification, and calibration of models with choline pathway metabolites were evaluated.

RESULTS

Plasma choline and betaine were inversely associated with cardiovascular events and recurrent stroke after ischemic stroke. Specifically, in fully adjusted models, each additional SD of choline and betaine was associated with 35% (95% CI: 20%-48%) and 30% (95% CI: 14%-43%) decreased risks of subsequent cardiovascular events, respectively, and 34% (95% CI: 16%-48%) and 29% (95% CI: 12%-43%) decreased risks of recurrent stroke, respectively. In addition, both choline and betaine offered substantial risk discrimination and reclassification improvement for cardiovascular events and recurrent stroke beyond traditional risk factors, as evidenced by an increase in C statistics, the net reclassification index, and integrated discrimination improvement.

CONCLUSIONS

Plasma choline pathway metabolites, including choline and betaine, were associated with decreased risks of cardiovascular events and recurrent stroke and provided incremental value in risk discrimination and stratification in patients with ischemic stroke. This nested case-control study was based on the China Antihypertensive Trial in Acute Ischemic Stroke, which is registered at clinicaltrials.gov as NCT01840072.

Plasma glycerophospholipid profile, erythrocyte n-3 PUFAs, and metabolic syndrome incidence: a prospective study in Chinese men and women

BACKGROUND

Animal studies have highlighted critical roles of glycerophospholipid (GP) metabolism in various metabolic syndrome (MetS)-related features such as dyslipidemia, obesity, and insulin resistance. However, human prospective studies of associations between circulating GPs and risks of MetS are scarce.

OBJECTIVES

We aimed to investigate whether GPs are associated with incidence of MetS in a well-established cohort.

METHODS

A total of 1243 community-dwelling Chinese aged 50-70 y without MetS at baseline and followed up for 6 y were included in current analyses. A total of 145 plasma GPs were quantified by high-throughput targeted lipidomics. MetS was defined using the updated National Cholesterol Education Program Adult Treatment Panel III criteria for Asian Americans.

RESULTS

After 6 y, 429 participants developed MetS. Eleven GPs, especially those with long-chain polyunsaturated fatty acids (LCPUFAs) or very-long-chain polyunsaturated fatty acids (VLCPUFAs) at the sn-2 position, including 1 phosphatidylcholine (PC) [PC(18:0/22:6)], 9 phosphatidylethanolamines (PEs) [PE(16:0/22:6), PE(18:0/14:0), PE(18:0/18:1), PE(18:0/18:2), PE(18:0/20:3), PE(18:0/22:5), PE(18:0/22:6), PE(18:1/22:6), and PE(18:2/22:6)], and 1 phosphatidylserine (PS) [PS(18:0/18:0)], were positively associated with incident MetS (RRs: 1.16-1.30 per SD change; Bonferroni-corrected P < 0.05). In network analysis, the strongest positive association for MetS incidence was evidenced in a module mainly composed of PEs containing C22:6 and PSs [RR: 1.21; 95% CI: 1.12, 1.31 per SD change; Bonferroni-corrected P < 0.05]. This association was more pronounced in participants with lower erythrocyte total n-3 PUFA concentrations [Bonferroni-corrected Pinter(P value for the interaction)< 0.05].

CONCLUSIONS

Elevated plasma concentrations of GPs, especially PEs with LCPUFAs or VLCPUFAs at the sn-2 position, are associated with higher risk of incident MetS. Future studies are merited to confirm our findings.

High-Throughput Analysis of Water-Soluble Forms of Choline and Related Metabolites in Human Milk by UPLC-MS/MS and Its Application

Choline and related metabolites are key factors in many metabolic processes, and insufficient supply can adversely affect reproduction and fetal development. Choline status is mainly regulated by intake, and human milk is the only choline source for exclusively breastfed infants. Further, maternal status, genotype, and phenotype, as well as infant outcomes, have been related to milk choline concentrations. In order to enable the rapid assessment of choline intake for exclusively breastfed infants and to further investigate the associations between milk choline and maternal and infant status and other outcomes, we have developed a simplified method for the simultaneous analysis of human milk choline, glycerophosphocholine, phosphocholine, and the less abundant related metabolites betaine, carnitine, creatinine, dimethylglycine (DMG), methionine, and trimethylamine N-oxide (TMAO) using ultraperformance liquid chromatography–tandem mass spectrometry (UPLC–MS/MS). These analytes have milk concentrations ranging over 3 orders of magnitude. Unlike other recently described LC-based methods, our approach does not require an ion-pairing reagent or high concentrations of solvent modifiers for successful analyte separation and thus avoid signal loss and potential permanent contamination. Milk samples (10 μl) were diluted (1:80) in water : methanol (1:4, v:v) and filtered prior to analysis with an optimized gradient of 0.1% propionic acid_aq and acetonitrile, allowing efficient separation and removal of contaminants. Recovery rates ranged from 108.0 to 130.9% (inter-day variation: 3.3–9.6%), and matrix effects (MEs) from 54.1 to 114.3%. MEs were greater for carnitine, creatinine, and TMAO at lower dilution (1:40, p < 0.035 for all), indicating concentration-dependent ion suppression. Milk from Brazilian women (2–8, 28–50, and 88–119 days postpartum, n_total = 53) revealed increasing concentration throughout lactation for glycerophosphocholine, DMG, and methionine, while carnitine decreased. Choline and phosphocholine were negatively correlated consistently at all three collection time intervals. The method is suitable for rapid analysis of human milk water-soluble forms of choline as well as previously not captured related metabolites with minimal sample volumes and preparation.

Dietary anthocyanins as potential natural modulators for the prevention and treatment of non-alcoholic fatty liver disease: A comprehensive review

Nonalcoholic fatty liver disease (NAFLD) refers to a metabolic syndrome linked with type 2 diabetes mellitus, obesity, and cardiovascular diseases. It is characterized by the accumulation of triglycerides in the hepatocytes in the absence of alcohol consumption. The prevalence of NAFLD has abruptly increased worldwide, with no effective treatment yet available. Anthocyanins (ACNs) belong to the flavonoid subclass of polyphenols, are commonly present in various edible plants, and possess a broad array of health-promoting properties. ACNs have been shown to have strong potential to combat NAFLD. We critically assessed the literature regarding the pharmacological mechanisms and biopharmaceutical features of the action of ACNs on NAFLD in humans and animal models. We found that ACNs ameliorate NAFLD by improving lipid and glucose metabolism, increasing antioxidant and anti-inflammatory activities, and regulating gut microbiota dysbiosis. In conclusion, ACNs have potential to attenuate NAFLD. However, further mechanistic studies are required to confirm these beneficial impacts of ACNs on NAFLD.

Differences in metabolic and liver pathobiology induced by two dietary mouse models of nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is a growing epidemic linked to metabolic disease. The first stage of NAFLD is characterized by lipid accumulation in hepatocytes, but this can progress into nonalcoholic steatohepatitis (NASH), cirrhosis, and hepatocellular carcinoma (HCC). Western diets, high in fats, sugars, and cholesterol, are linked to NAFLD development. Murine models are often used to study NAFLD; however, there remains debate on which diet-induced model best mimics both human disease progression and pathogenesis. In this study, we performed a side-by-side comparison of two popular diet models of murine NAFLD/NASH and associated HCC, a high-fat diet supplemented with 30% fructose water (HFHF) and a Western diet high in cholesterol (WDHC), and these were compared with a common grain-based chow diet (GBD). Mice on both experimental diets developed liver steatosis, and WDHC-fed mice had greater levels of hepatic inflammation and fibrosis than HFHF-fed mice. In contrast, HFHF-fed mice were more obese and developed more severe metabolic syndrome, with less pronounced liver disease. Despite these differences, WDHC-fed and HFHF-fed mice had similar tumor burdens in a model of diet-potentiated liver cancer. Response to diet and resulting phenotypes were generally similar between sexes, albeit delayed in females. This study shows that modest differences in diet can significantly uncouple glucose homeostasis and liver damage. In conclusion, long-term feeding of either HFHF or WDHC is a reliable method to induce NASH and diet-potentiated liver cancer in mice of both sexes; however, the choice of diet involves a trade-off between severity of metabolic syndrome and liver damage.

The Association of Dietary Choline and Betaine With the Risk of Type 2 Diabetes: The Atherosclerosis Risk in Communities (ARIC) Study

OBJECTIVE

To examine the association between dietary intake of choline and betaine and the risk of type 2 diabetes.

RESEARCH DESIGN AND METHODS

Among 13,440 Atherosclerosis Risk in Communities (ARIC) study participants, the prospective longitudinal association between dietary choline and betaine intake and the risk of type 2 diabetes was assessed using interval-censored Cox proportional hazards and logistic regression models adjusted for baseline potential confounding variables.

RESULTS

Among 13,440 participants (55% women, mean age 54 [SD 7.4] years), 1,396 developed incident type 2 diabetes during median follow-up of 9 years from 1987 to 1998. There was no statistically significant association between every 1-SD increase in dietary choline and risk of type 2 diabetes (hazard ratio [HR] 1.01 [95% CI 0.87, 1.16]) nor between dietary betaine intake and the risk of type 2 diabetes (HR 1.01 [0.94, 1.10]). Those in the highest quartile of dietary choline intake did not have a statistically significant higher risk of type 2 diabetes than those in the lowest choline quartile (HR 1.09 [0.84, 1.42]); similarly, dietary betaine intake was not associated with the risk of type 2 diabetes comparing the highest quartile to the lowest (HR 1.06 [0.87, 1.29]). Among women, there was a higher risk of type 2 diabetes, comparing the highest to lowest dietary choline quartile (HR 1.54 [1.06, 2.25]), while in men, the association was null (HR 0.82 [0.57, 1.17]). Nevertheless, there was a nonsignificant interaction between high choline intake and sex on the risk of type 2 diabetes (P = 0.07). The results from logistic regression were similar.

CONCLUSIONS

Overall and among male participants, dietary choline or betaine intakes were not associated with the risk of type 2 diabetes. Among female participants, there was a trend for a modestly higher risk of type 2 diabetes among those with the highest as compared with the lowest quartile of dietary choline intake. Our study should inform clinical trials on dietary choline and betaine supplementation in relationship with the risk of type 2 diabetes.

Gut Dysbiosis and Increased Intestinal Permeability Drive microRNAs, NLRP-3 Inflammasome and Liver Fibrosis in a Nutritional Model of Non-Alcoholic Steatohepatitis in Adult Male Sprague Dawley Rats

BACKGROUND/AIM

The interactions between the gut and liver have been described in the progression of non-alcoholic steatohepatitis (NASH). The aim of this study was to develop an experimental nutritional model of NASH simulating metabolic changes occurring in humans.

MATERIALS AND METHODS

Adult male Sprague Dawley rats were randomized into two groups: controls (standard diet) and intervention (high-fat and choline-deficient diet) for 16 weeks, each experimental group with 10 animals. Biochemical analysis, hepatic lipid content, microRNAs, inflammatory, gut permeability markers and gut microbiota were measured.

RESULTS

Animals in the intervention group showed significantly higher delta Lee index (p=0.017), abdominal circumference (p<0.001), abdominal adipose tissue (p<0.001) and fresh liver weight (p<0.001), as well as higher serum levels of alanine aminotransferase (p=0.010), glucose (p=0.013), total cholesterol (p=0.033), LDL cholesterol (p=0.011), and triglycerides (p=0.011), and lower HDL cholesterol (p=0.006) compared to the control group. Higher TLR4 (p=0.041), TLR9 (p=0.033), MyD88 (p=0.001), Casp1 (p<0.001), NLPR3 (p=0.019), liver inflammation index interleukin (IL)-1β/IL10 (p<0.001), IL6/IL10 (p=0.002) and TNFα/IL10 (p=0.001) were observed in the intervention group, and also lower permeability markers Ocln (p=0.003) and F11r (p=0.041). Gene expression of miR-122 increased (p=0.041) and miR-145 (p=0.010) decreased in the intervention group. Liver steatosis, inflammation and fibrosis, along with collagen fiber deposition increment (p<0.001), were seen in the intervention group. Regarding gut microbiota, Bray-Curtis dissimilarity index and number of operational taxonomic units were significantly different (p<0.001) between the groups. Composition of the gut microbiota showed a significant correlation with histopathological score of NAFLD (r=0.694) and index IL-1β/IL-10 (r=0.522).

CONCLUSION

This experimental model mimicking human NASH demonstrated gut and liver interaction, with gut microbiota and intestinal permeability changes occurring in parallel with systemic and liver inflammation, miRNAs regulation and liver tissue damage.

Hypoxia aggravates non-alcoholic fatty liver disease in presence of high fat choline deficient diet: A pilot study

AIM

NAFLD is a chronic and progressive disease for which there are no FDA-approved drugs available in the market. Drug discovery is a time-consuming procedure and requires screening of hundreds of small molecules to find new chemical entities (NECs) for a particular disease. Current preclinical NAFLD animal models take a longer time, which enhances the duration and expenses of the screening procedure. Hence to shorten the duration, we have proposed a preclinical animal model for rapid induction of non-alcoholic steatohepatitis (NASH), an advanced stage of NAFLD in rats.

METHODOLOGY

The animals were divided into three groups; control, high fat choline deficient (HFCD) and high fat choline deficient diet with sodium nitrite (40 mg/kg b.w. i.p. per day) (HFCD + NaNO₂) respectively. Four weeks later physical and serum biochemical parameters were assessed, intraperitoneal glucose tolerance test was performed, and histopathology and gene expression were analysed.

KEY FINDINGS

Hypoxic stress aggravates the lipid accumulation, ballooning, lobular inflammation and fibrosis in hepatic tissue in presence of HFCD diet.

SIGNIFICANCE

This novel rodent model could be a useful NAFLD model to screen small molecules rapidly for treatment of NASH.

Long-Term Ketogenic Diet Induces Metabolic Acidosis, Anemia, and Oxidative Stress in Healthy Wistar Rats

Background

Ketogenic diet has been used as supportive therapy in a range of conditions including epilepsy, diabetes mellitus, and cancer.

Objective

This study aimed to investigate the effects of long-term consumption of ketogenic diet on blood gas, hematological profiles, organ functions, and superoxide dismutase level in a rat model.

Materials and Methods

Fifteen male Wistar rats were divided into control (n = 8) and ketogenic (n = 7) groups. Controls received standard diet contained 52.20% of carbohydrates, 7.00% fat, and 15.25% protein; meanwhile, the ketogenic group received a high-fat-low-carbohydrate diet which contained 5.66% of carbohydrate, 86.19% fat, and 8.15% protein. All rats were caged individually and received 30g of either standard or high-fat-low-carbohydrate pellets. The experiment was carried out for 60 days before the blood samples were taken and analyzed to obtain blood gas, cell counts, organ biomarkers, and plasma antioxidant superoxide dismutase (SOD) levels.

Results

The rats subjected to ketogenic diet experienced a marked decrease in body weight, blood sugar, and increased blood ketones (p < 0.05). The average blood pH was 7.36 ± 0.02 and base excess was −5.57 ± 2.39 mOsm/L, which were significantly lower than controls (p < 0.05). Hematological analysis showed significantly lower erythrocyte, hemoglobin, and hematocrit levels. No significant changes were found in alanine aminotransferase, aspartate aminotransferase, urea, and creatinine levels, indicating normal liver and kidney functions. Nevertheless, plasma SOD level significantly reduced with ketogenic diet.

Conclusion

Long-term ketogenic diet induces metabolic acidosis, anemia, and reduced antioxidant enzyme level in rats following 60 days of consuming high-fat-low-carbohydrate diet.

Hippocampal neural cell degeneration and memory deficit in high-fat diet-induced postnatal obese rats- exploring the comparable benefits of choline and DHA or environmental enrichment

Purpose: Childhood obesity increases risk for neural dysfunctions causing learning and memory deficits. The objective of the study is to identify the effects of high fat diet-induced obesity in postnatal period on serum lipids, memory and neural cell survival in hippocampus and compare the role of choline and DHA or environmental enrichment in attenuating the alterationsMaterials and methods: 21 day postnatal male Sprague Dawley rats were assigned as Normal control [NC] fed normal chow diet, Obesity-induced [OB] fed high fat diet, Obesity-induced fed choline & DHA [OB + CHO + DHA], Obesity-induced environmental enrichment [OB + EE] [n = 8/group]. Memory was assessed using radial arm maze. Subsequently blood was collected for serum lipid analysis and rats were euthanized. 5 µm hippocampal sections were processed for cresyl-violet stain. Surviving neural cells were counted using 100 µm scale.Results: Memory errors were significantly higher [p < 0.001, 0.01] in OB compared to same in NC rats. Mean number of surviving neural cells in hippocampus of OB was significantly lesser [p < 0.01] compared to same in NC. Interventions in OB + CHO + DHA and OB + EE significantly attenuated [p < 0.01] memory errors and number of surviving neural cells in hippocampus [CA1, CA3 and DG] compared to same in OB. Moreover, hippocampal neural cell survival was found to be inversely related to serum lipid profile in OB group and was attenuated in OB + CHO + DHA and OB + EE rats.Conclusions: High fat diet-induced postnatal obesity in rats causes CA1/CA3 hippocampal neuro-degeneration and memory deficits. Supplementation of choline and DHA in obese rats attenuates these deficits.

Targeted Nutrient Modifications in Purified Diets Differentially Affect Nonalcoholic Fatty Liver Disease and Metabolic Disease Development in Rodent Models

Nonalcoholic fatty liver disease (NAFLD) is a complex spectrum of disorders ranging from simple benign steatosis to more aggressive forms of nonalcoholic steatohepatitis (NASH) and fibrosis. Although not every patient with NAFLD/NASH develops liver complications, if left untreated it may eventually lead to cirrhosis and hepatocellular carcinoma. Purified diets formulated with specific nutritional components can drive the entire spectrum of NAFLD in rodent models. Although they may not perfectly replicate the clinical and histological features of human NAFLD, they provide a model to gain further understanding of disease progression in humans. Owing to the growing demand of diets for NAFLD research, and for our further understanding of how manipulation of dietary components can alter disease development, we outlined several commonly used dietary approaches for rodent models, including mice, rats, and hamsters, time frames required for disease development and whether other metabolic diseases commonly associated with NAFLD in humans occur.

Exercise Attenuates the Transition from Fatty Liver to Steatohepatitis and Reduces Tumor Formation in Mice

Non-alcoholic fatty liver disease (NAFLD) leads to steatohepatitis (NASH), fibrosis, and hepatocellular carcinoma. For sedentary patients, lifestyle interventions combining exercise and dietary changes are a cornerstone of treatment. However, the benefit of exercise alone when dietary changes have failed is uncertain. We query whether exercise alone arrests the progression of NASH and tumorigenesis in a choline-deficient, high-fat diet (CD-HFD) murine model. Male C57Bl/6N mice received a control diet or CD-HFD for 12 weeks. CD-HFD mice were randomized further for 8 weeks of sedentariness (SED) or treadmill exercise (EXE). CD-HFD for 12 weeks produced NAFL. After 20 weeks, SED mice developed NASH and hepatic adenomas. Exercise attenuated the progression to NASH. EXE livers showed lower triglycerides and tumor necrosis factor-α expression, less fibrosis, less ballooning, and a lower NAFLD activity score than did SED livers. Plasma transaminases and triglycerides were lower. Exercise activated AMP-activated protein kinase (AMPK) with inhibition of mTORC1 and decreased S6 phosphorylation, reducing hepatocellular adenoma. Exercise activated autophagy with increased LC3-II/LC3-I and mitochondrial recruitment of phosphorylated PTEN-induced kinase. Therefore, exercise attenuates the transition from NAFL to NASH, improves biochemical and histological parameters of NAFLD, and impedes the progression of fibrosis and tumorigenesis associated with enhanced activation of AMPK signaling and favors liver autophagy. Our work supports the benefits of exercise independently of dietary changes.

A Role for Gut Microbiome Fermentative Pathways in Fatty Liver Disease Progression

Non-alcoholic fatty liver disease (NAFLD) is a multifactorial disease in which environmental and genetic factors are involved. Although the molecular mechanisms involved in NAFLD onset and progression are not completely understood, the gut microbiome (GM) is thought to play a key role in the process, influencing multiple physiological functions. GM alterations in diversity and composition directly impact disease states with an inflammatory course, such as non-alcoholic steatohepatitis (NASH). However, how the GM influences liver disease susceptibility is largely unknown. Similarly, the impact of strategies targeting the GM for the treatment of NASH remains to be evaluated. This review provides a broad insight into the role of gut microbiota in NASH pathogenesis, as a diagnostic tool, and as a therapeutic target in this liver disease. We highlight the idea that the balance in metabolic fermentations can be key in maintaining liver homeostasis. We propose that an overabundance of alcohol-fermentation pathways in the GM may outcompete healthier, acid-producing members of the microbiota. In this way, GM ecology may precipitate a self-sustaining vicious cycle, boosting liver disease progression.

Gut microbiota and human NAFLD: disentangling microbial signatures from metabolic disorders

Gut microbiota dysbiosis has been repeatedly observed in obesity and type 2 diabetes mellitus, two metabolic diseases strongly intertwined with non-alcoholic fatty liver disease (NAFLD). Animal studies have demonstrated a potential causal role of gut microbiota in NAFLD. Human studies have started to describe microbiota alterations in NAFLD and have found a few consistent microbiome signatures discriminating healthy individuals from those with NAFLD, non-alcoholic steatohepatitis or cirrhosis. However, patients with NAFLD often present with obesity and/or insulin resistance and type 2 diabetes mellitus, and these metabolic confounding factors for dysbiosis have not always been considered. Patients with different NAFLD severity stages often present with heterogeneous lesions and variable demographic characteristics (including age, sex and ethnicity), which are known to affect the gut microbiome and have been overlooked in most studies. Finally, multiple gut microbiome sequencing tools and NAFLD diagnostic methods have been used across studies that could account for discrepant microbiome signatures. This Review provides a broad insight into microbiome signatures for human NAFLD and explores issues with disentangling these signatures from underlying metabolic disorders. More advanced metagenomics and multi-omics studies using system biology approaches are needed to improve microbiome biomarkers.

New insight into the mechanism of POP-induced obesity: Evidence from DDE-altered microbiota

Although epidemiological studies demonstrate that persistent organic pollutants (POPs) could lead to metabolic syndrome, the mechanism has remained unclear. The dysbiosis of gut microbiota and the lipid metabolome have been put forward in the pathophysiology of metabolic syndrome. In this study, we used dichlorodiphenyldichloroethylene (DDE) as an example to study the effects of POP-impaired microbial composition and metabolome homeostasis on metabolic syndrome. The results showed that DDE exposure increased body weight and fat content and impaired glucose homeostasis. Further investigation revealed that DDE induced gut dysbiosis as indicated by an increased Firmicutes-to-Bacteroidetes ratio, which may impact energy harvest efficiency. Meanwhile, the plasma lipid metabolome profile was significantly altered by DDE. Furthermore, phosphatidylcholine, phosphatidylserine, phosphatidylethanolamine, and triacylglycerol were identified as key metabolites affected by DDE treatment, and these altered lipid metabolites were highly correlated with changed microbiota composition. This study provides novel insight into the underlying mechanism of POP-induced obesity and diabetes, pointing to gut microbiota as one of the targets.

NAFLD Preclinical Models: More than a Handful, Less of a Concern?

Non-alcoholic fatty liver disease (NAFLD) is a spectrum of liver diseases ranging from simple steatosis to non-alcoholic steatohepatitis, fibrosis, cirrhosis, and/or hepatocellular carcinoma. Due to its increasing prevalence, NAFLD is currently a major public health concern. Although a wide variety of preclinical models have contributed to better understanding the pathophysiology of NAFLD, it is not always obvious which model is best suitable for addressing a specific research question. This review provides insights into currently existing models, mainly focusing on murine models, which is of great importance to aid in the identification of novel therapeutic options for human NAFLD.