Excessive Lipid Accumulation Research Articles

Evaluation of Rosmarinic Acid Attenuation Effect on Endoplasmic Reticulum Stress in Swiss-type Mice Affected With Nonalcoholic Steatohepatiti

Background and Objectives: Nonalcoholic steatohepatitis is a severe liver disease characterized by excess lipid accumulation (steatosis) and inflammation in the liver. Endoplasmic reticulum stress is considered one of the crucial factors in nonalcoholic steatohepatitis pathophysiology. Rosmarinic acid is a herbal medicine with antioxidant and anti-inflammatory properties. This study aimed to evaluate the effect of rosmarinic acid on reducing the endoplasmic reticulum stress induced by nonalcoholic steatohepatitis in male Swiss-type mice. Methods: The study animals were grouped into four: Saline, rosmarinic acid, nonalcoholic steatohepatitis, and nonalcoholic steatohepatitis-rosmarinic acid. Nonalcoholic steatohepatitis was induced by a diet without methionine-choline for 8 weeks, and rosmarinic acid was injected intraperitoneally daily for 8 weeks in mice. After 8 weeks, the animals were killed, and their liver samples were obtained. Real-time PCR was used for molecular studies. Data analyses were performed by one-way analysis of variance and Tukey's post hoc test. Results: Findings of this study showed that rosmarinic acid alleviated mRNA levels of GRP78, IRE-1, and PERK while increasing the Apo B expression. Conclusion: The results suggest that rosmarinic acid ameliorates endoplasmic reticulum stress parameters, upregulates Apo B expression as a key factor in triglyceride exit from the liver, and thereby improves nonalcoholic steatohepatitis in male Swiss-type mice.

Altered drug metabolism and increased susceptibility to fatty liver disease in a mouse model of myotonic dystrophy

Myotonic Dystrophy type 1 (DM1), a highly prevalent form of muscular dystrophy, is caused by (CTG)n repeat expansion in the DMPK gene. Much of DM1 research has focused on the effects within the muscle and neurological tissues; however, DM1 patients also suffer from various metabolic and liver dysfunctions such as increased susceptibility to metabolic dysfunction-associated fatty liver disease (MAFLD) and heightened sensitivity to certain drugs. Here, we generated a liver-specific DM1 mouse model that reproduces molecular and pathological features of the disease, including susceptibility to MAFLD and reduced capacity to metabolize specific analgesics and muscle relaxants. Expression of CUG-expanded (CUG)exp repeat RNA within hepatocytes sequestered muscleblind-like proteins and triggered widespread gene expression and RNA processing defects. Mechanistically, we demonstrate that increased expression and alternative splicing of acetyl-CoA carboxylase 1 drives excessive lipid accumulation in DM1 livers, which is exacerbated by high-fat, high-sugar diets. Together, these findings reveal that (CUG)exp RNA toxicity disrupts normal hepatic functions, predisposing DM1 livers to injury, MAFLD, and drug clearance pathologies that may jeopardize the health of affected individuals and complicate their treatment.

Impacts of time-restricted feeding on middle-aged and old mice with obesity.

Time-restricted feeding is known to ameliorate obesity in young mice. However, evaluation of its effect in old age is still lacking. The current work aims to investigate the effects of time-restricted feeding on treating pre-existing obesity in old animals. The study utilized middle-aged and old high fat diet-induced obese mice and subjected them to 8h daily time-restricted feeding. Aged obese mice did not lose fat mass but lost lean mass after 8 weeks of treatment. In addition, time-restricted feeding reduced adiposity in brown adipose tissue, reversed excessive hepatic lipid accumulation, and improved glucose homeostasis in middle-aged and old obese mice. Mechanistic studies show that these metabolic benefits were mediated by transcriptional downregulation of essential genes responsible for hepatic adipogenesis and adipose tissue chronic inflammation. These results demonstrate that time-restricted feeding improves metabolic health and has beneficial effects in combating diet-induced obesity in aged obese mice. KEY POINTS: Contrary to in young obese mice, in old obese mice time-restricted feeding did not significantly reduce body fat but decreased lean mass. Time-restricted feeding reduced adipose tissue inflammation, reversed fatty liver, and improved glucose homeostasis in aged mice with diet-induced obesity. Time-restricted feeding is effective in improving metabolic homeostasis in aged mice, but less effective in terms of reducing obesity. Future studies should investigate the underlying mechanism of how ageing impaired intermittent fasting induced fat loss.

Different time-restricted feeding patterns potentially modulate metabolic health by altering tryptophan metabolism of gut microbes in pigs

Time-restricted feeding has emerged as a preferred approach for alleviating metabolic disorders, but the potential microbiological mechanism remains poorly understood. This study used a growing pig model to mimic common-sense eating habits. Four feeding patterns were set up, including ad libitum feeding (ALF) for daily irregulated eating habits, time-restricted feeding (TRF) for three meals a day, early time-restricted feeding (eTRF) for skipping dinner and mid-day time-restricted feeding (mTRF) for skipping breakfast. The results showed that the three time-restricted feeding patterns (TRF, eTRF and mTRF) resulted in a reduction of hepatic fat accumulation and a decrease in hepatic function markers compared to the ALF pattern. However, this was independent of food consumption. Transcriptome analysis of the liver showed that the three time-restricted feeding patterns downregulated the expression of genes related to gluconeogenesis, β-oxidation, lipid accumulation, and urea cycle, and upregulated the expression of genes related to lipogenesis and glycolysis compared to the ALF pattern. Microbiome and metabolome analyses showed that Lactobacillus enriched in the colon of pigs in three time-restricted groups were negatively correlated with serum triglyceride. Meanwhile, three time-restricted feeding patterns elevated the levels of the microbial metabolite indole-3-lactic acid, which was further confirmed to reduce excessive hepatic lipid accumulation in vitro. Overall, time-restricted feeding potentially improved metabolic health by modulating gut microbiota and metabolites.

Distribution of lipid droplets in hippocampal neurons and microglia: impact of diabetes and exercise.

Neuroinflammation, aging, and neurodegenerative disorders are associated with excessive accumulation of neutral lipids in lipid droplets (LDs) in microglia. Type 2 diabetes mellitus (T2DM) may cause neuroinflammation and is a risk factor for neurodegenerative disorders. Here, we show that hippocampal pyramidal neurons contain smaller, more abundant LDs than their neighboring microglia. The density of LDs varied between pyramidal cells in adjacent subregions, with CA3 neurons containing more LDs than CA1 neurons. Within the CA3 region, a gradual increase in the LD content along the pyramidal layer from the hilus toward CA2 was observed. Interestingly, the high neuronal LD content correlated with less ramified microglial morphotypes. Using the db/db model of T2DM, we demonstrated that diabetes increased the number of LDs per microglial cell without affecting the neuronal LD density. High-intensity interval exercise induced smaller changes in the number of LDs in microglia but was not sufficient to counteract the diabetes-induced changes in LD accumulation. The changes observed in response to T2DM may contribute to the cerebral effects of T2DM and provide a mechanistic link between T2DM and neurodegenerative disorders.

NPRC promotes hepatic steatosis via USP30-mediated deubiquitination of C/EBPβ

Background and aimsMetabolic dysfunction-associated fatty liver disease (MAFLD) is a prevalent chronic liver condition characterised by dysregulated lipid metabolism. The role of Natriuretic Peptide Receptor C (NPRC), a receptor responsible for clearing natriuretic peptides, in MAFLD remains elusive. Therefore, the aim of the present study was to elucidate the role of NPRC in MAFLD progression. Approach and resultsThis study demonstrated that NPRC enhanced lipid metabolism reprogramming and accelerated MAFLD progression. Mechanistic investigations, including proteomic and ubiquitination analyses, revealed that elevated NPRC levels stabilized the C/EBPβ protein, leading to excessive lipid accumulation. The DNA-binding domain (DBD) of C/EBPβ interacted with the deubiquitinase USP30, a key regulator that inhibited K149-specific K48-linked polyubiquitination of C/EBPβ. Importantly, the ANPR region of NPRC bound to USP30, facilitating the deubiquitination of C/EBPβ. Furthermore, virtual screening identified punicalin, a natural compound, as a potential inhibitor of NPRC expression, which may reduce hepatic lipid accumulation, inflammation and fibrosis. ConclusionsOur findings indicate that NPRC recruits USP30 to mediate the deubiquitination of C/EBPβ, driving lipid metabolism reprogramming. Targeting NPRC could represent a promising therapeutic approach for MAFLD.

Activity and phosphatidylcholine transfer protein interactions of skeletal muscle thioesterase Them2 enable hepatic steatosis and insulin resistance

Thioesterase superfamily member 2 (Them2), a long-chain fatty acyl-CoA thioesterase that is highly expressed in oxidative tissues, interacts with phosphatidylcholine transfer protein (PC-TP) to regulate hepatic lipid and glucose metabolism and to suppress insulin signaling. High-fat diet (HFD)-fed mice lacking Them2 globally or specifically in skeletal muscle, but not liver, exhibit reduced hepatic steatosis and insulin resistance. Here, we report that the capacity of Them2 in skeletal muscle to promote hepatic steatosis and insulin resistance depends on both its catalytic activity and interaction with PC-TP. Two residues of Them2 catalytic site were mutated (N50A/D65A) to produce the inactive enzyme while maintaining its homotetrameric structure and interaction with PC-TP. Restoration of skeletal muscle expression in Them2-/- mice using recombinant adeno-associated virus revealed that wild-type (WT), but not N50A/D65A Them2, promoted HFD-induced weight gain and hepatic steatosis. This was accompanied by greater impairment of insulin sensitivity in WT compared with N50A/D65A Them2. Pharmacological inhibition or genetic ablation of PC-TP attenuated these effects. In reductionist experiments, conditioned medium collected from WT primary cultured myotubes promoted excess lipid accumulation in oleic acid-treated primary cultured hepatocytes relative to Them2-/- myotubes, which was attributable to secreted extracellular vesicles (EV). Reconstitution of Them2 expression in Them2-/- myotubes affirmed the requirements for catalytic activity and PC-TP interactions for EV to promote lipid accumulation in hepatocytes. These studies provide valuable mechanistic insights whereby Them2 in skeletal muscle promotes hepatic steatosis and establish both Them2 and PC-TP as represent attractive targets for managing metabolic dysfunction-associated steatotic liver disease.

Targeting ketone body metabolism to treat fatty liver disease.

Metabolic dysfunction-associated steatotic liver disease (MASLD) is a metabolic disorder marked by excessive accumulation of lipids within the liver. If untreated, this condition can progress to metabolic dysfunction-associated steatohepatitis (MASH), fibrosis, cirrhosis, and ultimately, hepatocellular carcinoma (HCC). Given the liver's pivotal role in glucose and fatty acid metabolism, disruptions in these processes are commonly observed in MASLD. Ketone bodies, crucial energy metabolites primarily produced in the liver, are also closely related to the progression of MASLD. Recent studies have demonstrated that disrupted ketogenesis not only accompanies MASLD, but may also play a causal role in its development and progression. Moreover, activation of the ketogenic pathway has been suggested as a promising strategy for reducing excessive hepatic fat accumulation. This review focuses on the regulation of ketogenesis in MASLD, emphasizing the significance of dietary and pharmacological interventions as potential therapeutic approaches to treat fatty liver disease.

Expression of TWEAK/Fn14 axis in the context of metabolic dysfunction associated-fatty liver disease: an approach in liver regeneration

Background: One of the pathways involved in liver regeneration processes is TWEAK/Fn14 (tumor necrosis factor-related weak inducer of apoptosis/fibroblast growth factor-inducible 14), which has been proposed to act directly and selectively on hepatic progenitor cells; however, its role in the regeneration of steatotic liver metabolic dysfunction associated fatty liver disease has not been fully elucidated. Objective: To evaluate the behavior of Fn14 and its ligand TWEAK, as well as cellular stress signals as biochemical cues for possible liver regeneration in MAFLD. Materials and methods: A prospective study was carried out where the behavior of Fn14 and its ligand TWEAK, as well as cellular stress signals were observed as biochemical indications of a possible liver regeneration in a condition of tissue damage caused by excessive lipid accumulation. The expression of TWEAK, Fn14 and heat shock proteins in hepatic steatosis of non-alcoholic origin was assessed using immunohistochemistry and western blotting. Results: The histological classification of the tissues under study corresponded to microvesicular steatosis. We report a high level of expression of heat shock proteins in the cytoplasm. The expression of TWEAK and Fn14 in liver tissue affected by lipid accumulation was localized in the cytoplasm of hepatocytes, showing a higher intensity of reactivity for Fn14 compared to its ligand TWEAK. Conclusion: The expression of TWEAK/Fn14 axis was positive suggesting reactivity of the signaling pathway in metabolic dysfunction associated fatty liver disease.

Leveraging adrenergic receptor blockade for enhanced nonalcoholic fatty liver disease treatment via a biomimetic nanoplatform

Nonalcoholic fatty liver disease (NAFLD) is characterized by excessive lipid accumulation, steatosis and fibrosis. Sympathetic nerves play a critical role in maintaining hepatic lipid homeostasis and regulating fibrotic progression through adrenergic receptors expressed by hepatocytes and hepatic stellate cells; however, the use of sympathetic nerve-focused strategies for the treatment of NAFLD is still in the infancy. Herein, a biomimetic nanoplatform with ROS-responsive and ROS-scavenging properties was developed for the codelivery of retinoic acid (RA) and the adrenoceptor antagonist labetalol (LA). The nanoplatform exhibited improved accumulation and sufficient drug release in the fibrotic liver, thereby achieving precise codelivery of drugs. Integration of adrenergic blockade effectively interrupted the vicious cycle of sympathetic nerves with hepatic stellate cells (HSCs) and hepatocytes, which not only combined with RA to restore HSCs to a quiescent state but also helped to reduce hepatic lipid accumulation. We demonstrated the excellent ability of the biomimetic nanoplatform to ameliorate liver inflammation, fibrosis and steatosis. Our work highlights the tremendous potential of a sympathetic nerve-focused strategy for the management of NAFLD and provides a promising nanoplatform for the treatment of NAFLD.

Aged garlic oligosaccharides modulate host metabolism and gut microbiota to alleviate high-fat and high-cholesterol diet-induced atherosclerosis in ApoE−/− mice

Atherosclerosis (AS) is a cardiovascular disease caused by excessive accumulation of lipids in arterial walls. In this study, we developed an AS model in ApoE−/− mice using a high-fat, high-cholesterol diet and investigated the anti-AS mechanism of aged garlic oligosaccharides (AGOs) by focusing on the gut microbiota. Results revealed that AGOs exhibited significant anti-AS effects, reduced trimethylamine N-oxide levels from 349.9 to 189.2 ng/mL, and reduced aortic lipid deposition from 31.7 % to 9.5 %. AGOs significantly increased the levels of short-chain fatty acids in feces, in which acetic, propionic, and butyric acids were increased from 1.580, 0.364, and 0.469 mg/g to 2.233, 0.774, and 0.881 mg/g, respectively. An analysis of the gut microbiota indicated that AGOs restored alpha and beta diversity, decreased the Firmicutes/Bacteroidetes ratio, and promoted the dominance of the genus Akkermansia. A metagenomic analysis revealed that AGOs alleviated AS through the ABC transporter pathway and the lipopolysaccharide biosynthesis pathway.

Clinopodium gracile Alleviates Metabolic Dysfunction-Associated Steatotic Liver Disease by Upregulating Peroxisome Proliferator-Activated Receptor α and Inhibiting Mitochondrial Oxidative Damage.

The most prevalent chronic liver disease, known as metabolic dysfunction-associated steatotic liver disease (MASLD), is characterized by an excessive accumulation of lipids and oxidative damage. Clinopodium gracile, a natural herbal medicine widely used by Chinese folk, has antioxidative, anti-inflammatory, and lipid metabolism-regulating effects. Here, we explored the effect of C. gracile extract (CGE) on MASLD using palmitic acid (PA)-induced hepatocytes and high-fat diet (HFD)-fed mice. In vitro, CGE could promote fatty acid oxidation and inhibit fatty acid synthesis and uptake to reduce lipid accumulation by regulating PPARα activation. Moreover, CGE could inhibit reactive oxygen species production and maintain mitochondrial homeostasis in PA-induced HepG2 cells. In vivo, animal study results indicated that CGE could effectively reduce lipid metabolism disorder, inhibit oxidative stress, and upregulate PPARα protein in the liver of HFD-fed mice. Molecular docking results also showed that active compounds isolated from CGE had low binding energy and highly stable binding with PPARα. In summary, these findings reveal that CGE may be a potential therapeutic candidate for MASLD and act by upregulating PPARα to reduce lipid accumulation and suppress mitochondrial oxidative damage.

FABP1 induces lipogenesis by regulating the processing of SREBP1 in hepatocytes of large yellow croaker (Larimichthys crocea).

Fatty acid-binding protein 1 (FABP1) plays an important role in regulating fatty acid metabolism in liver, which is a potential therapeutic target for diseases such as non-alcoholic fatty liver disease (NAFLD). However, the underlying mechanisms are not well defined. Using complementary experimental models, we discovered FABP1 induction in hepatocytes as a primary mediator of lipogenesis when exposed to fatty acids, especially saturated fatty acids (SFAs). In the feeding trial, palm oil led to excess lipid accumulation in the liver of large yellow croaker (Larimichthys crocea), accompanied by significant induction of FABP1. In cultured cells, palmitic acid (PA), a kind of SFA, triggered the fabp1 expression and increased triglyceride (TG) contents. Knockdown of FABP1 dampened PA-induced TG accumulation through mitigated lipogenesis. The overexpression of FABP1 showed the opposite result. Furthermore, the inactivation of FABP1 led to induction in insulin-induced gene 1 (INSIG1) expression, which attenuated the processing of sterol regulatory element-binding protein 1 (SREBP1) by down-regulating the nuclear-localized SREBP1. These results revealed a previously unrecognized function of FABP1 in response to PA, providing additional evidence for targeting FABP1 in the treatment of NAFLD caused by SFA.

Polygala fallax Hemsl polysaccharides alleviated alcoholic fatty liver disease by modifying lipid metabolism via AMPK

Alcoholic fatty liver disease (AFLD) is characterized by excessive lipid accumulation in the liver. This study aimed to investigate the protective effects and mechanisms of Polygala fallax Hemsl polysaccharides (PFPs) on AFLD. PFPs were purified and structurally characterized. An AFLD model was established in mice using alcohol and a high-fat diet. A significant reduction in hepatic steatosis was observed following PFPs treatment, evidenced by decreased fat deposition in liver tissues. Additionally, PFPs reduced various liver injury markers, increased levels of antioxidant enzymes, and improved significantly liver function. RNA sequencing revealed that PFPs improved lipid and CYP450 metabolic pathway abnormalities in AFLD mice. Furthermore, PFPs activated the AMPK pathway, reducing lipid accumulation and enhancing lipid metabolism. A HepG2 cell model treated with ethanol and oleic acid showed significant biochemical improvements with PFPs pretreatment, including reduced lipid accumulation and lower reactive oxygen species (ROS) levels. To further elucidate the AMPK and PFPs correlation in AFLD, an AMPK inhibitor (compound C) was used. In vitro and in vivo qRT-PCR and Western blot results confirmed that PFPs protected against AFLD by activating AMPK phosphorylation, regulating lipid synthesis, and inhibiting lipid accumulation. PFPs also modulated CYP2E1 and oxidative stress-related gene expression, affecting liver metabolism.

Sulforaphane ameliorates non-alcoholic steatohepatitis by KLF4-mediated macrophage M2 polarization

Non-alcoholic fatty liver disease (NAFLD) has become a global issue and a severe threat to public health. However, to date, no approved therapeutic drugs have been developed. Dietary interventions with natural products have shown promise in preventing and treating NAFLD. Sulforaphane (SFN) is a phytocompound with antioxidant and anti-inflammatory properties, and previous research has demonstrated that SFN can ameliorate hepatic lipid accumulation and inflammation. However, the molecular mechanisms underlying these beneficial effects remain unclear. In this study, we confirmed the protective effects of SFN on excessive lipid accumulation and inflammatory injury in a high-fat, high-fructose diet-induced non-alcoholic steatohepatitis (NASH) mouse model. We found that SFN attenuates the inflammatory injury in a macrophage cell line and the liver of NASH mice, owing to the promotion of M1-type macrophage polarization toward the M2-type and the regulation of inflammatory mediators. Further analysis demonstrated that this SFN-induced macrophage M2-type polarization occurs in a Krüppel-like factor 4 (KLF4)-dependent manner. In summary, we uncovered a new mechanism of action underlying SFN activity and provide evidence that dietary intervention with SFN might be protective against NASH.

The beneficial impact of curcumin on cardiac lipotoxicity.

Lipotoxicity is defined as a prolonged metabolic imbalance of lipids that results in ectopic fat distribution in peripheral organs such as the liver, heart, and kidney. The harmful consequences of excessive lipid accumulation in cardiomyocytes cause cardiac lipotoxicity, which alters the structure and function of the heart. Obesity and diabetes are linked to lipotoxic cardiomyopathy. These anomalies might be caused by a harmful metabolic shift that accumulates toxic lipids and shifts glucose oxidation to less fatty acid oxidation. Research has linked fatty acids, fatty acyl coenzyme A, diacylglycerol, and ceramide to lipotoxic stress in cells. This stress can be brought on by apoptosis, impaired insulin signaling, endoplasmic reticulum stress, protein kinase C activation, p38 Ras-mitogen-activated protein kinase (MAPK) activation, or modification of peroxisome proliferator-activated receptors (PPARs) family members. Curcuma longa is used to extract curcumin, a hydrophobic polyphenol derivative with a variety of pharmacological characteristics. Throughout the years, curcumin has been utilized as an anti-inflammatory, antioxidant, anticancer, hepatoprotective, cardioprotective, anti-diabetic, and anti-obesity drug. Curcumin reduces cardiac lipotoxicity by inhibiting apoptosis and decreasing the expression of apoptosis-related proteins, reducing the expression of inflammatory cytokines, activating the autophagy signaling pathway, and inhibiting the expression of endoplasmic reticulum stress marker proteins.

Lactic acid regulates lipid droplet aggregation through a microglia-neuron axis in neuroinflammation

Neuroinflammation, marked by the release of proinflammatory cytokines and resulting neuronal death, is a multifaceted process extending beyond traditional inflammatory pathways. Microglia, primary cells in the inflammatory response, rapidly activate during neuroinflammation and produce proinflammatory and cytotoxic factors that affect neuronal function. Recent evidence highlights the significant role of abnormal lipid droplet (LD) deposition in the pathogenesis of neuroinflammation. While microglia are known to influence LD aggregation during neuroinflammation, the regulatory mechanism within neurons is not well understood. Our study demonstrates that lipopolysaccharide-activated microglia induce the accumulation of LD in neurons, identifying microglial-derived lactic acid as a key mediator in this process. Excessive lipid accumulation threatens neuronal function, a phenomenon reversed by eliminating microglia. Our study demonstrates that lipopolysaccharide-activated microglia induce the accumulation of LD in neurons, identifying microglial-derived lactic acid as a key mediator in this process. Excessive lipid accumulation threatens neuronal function, a phenomenon reversed by eliminating microglia.

Epigallocatechin gallate improves oleic acid-induced hepatic steatosis in laying hen hepatocytes via the MAPK pathway

Fatty liver disease in laying hens, characterized by excessive lipid accumulation in hepatocytes, poses significant challenges to poultry health and production efficiency. In this study, we investigated the therapeutic potential of epigallocatechin gallate (EGCG), a bioactive compound found in green tea, in mitigating oleic acid (OA)-induced hepatic steatosis in primary chicken hepatocytes. Treatment with EGCG effectively attenuated lipid deposition by downregulating lipid synthesis-related genes. Moreover, EGCG mitigated oxidative stress, inflammation, DNA damage, and apoptosis induced by OA, thereby preserving hepatocyte viability. Mechanistically, EGCG exerted its protective effects by modulating the p38 MAPK signaling pathway. Our findings suggest that EGCG holds promise as a therapeutic agent for managing fatty liver disease in poultry, offering insights into novel strategies for improving poultry health and production outcomes.

Tryptophan supplements in high-carbohydrate diets by improving insulin response and glucose transport through PI3K-AKT-GLUT2 pathways in blunt snout bream (Megalobrama amblycephala)

The aim of this experiment was to elucidate the metabolic ramifications of tryptophan supplementation in the context of high-carbohydrate diet-feeding, which is important for improving feeding strategies in aquaculture in order to improve fish carbohydrate metabolism. Juvenile blunt snout bream with an initial mean body mass of 55.0±0.5 g were allocated to consume one of three experimental diets: CN, a normal diet with carbohydrate content of 30% (w/w); HC, a diet with high carbohydrate content of 43% (w/w); and HL, a high-carbohydrate diet to which 0.8% L-tryptophan (L-trp) had been added. These diets were fed for 8 weeks, and the effects of the carbohydrate and tryptophan contents of the diets were assessed.Histological analysis using Hematoxylin and Eosin (H&E) and Oil Red O staining revealed that high-carbohydrate intake was associated with abnormal hepatocyte morphology and excessive liver lipid accumulation, which were notably ameliorated by tryptophan supplementation. A significant increase in plasma glucose, glucagon, AGEs (advanced glycation end products), triglycerides, total cholesterol, and a significant decrease in insulin and hepatic glycogen after a high-carbohydrate diet in terms of plasma indices, compared to the control group. Almost all of them were restored to the normal level in the HL group. The present study might preliminarily suggest that tryptophan supplementation ameliorates the imbalance in glucose metabolism of this species induced by a high-carbohydrate diet. Transcriptomics showed that glucose metabolism under high carbohydrate was mainly regulated by the PI3K-AKT signaling pathway. The mRNA expression and protein levels of GLUT2 also varied with this pathway, which would suggest that sustained activation of this pathway with the addition of tryptophan accelerates glucose transport and insulin secretion under high-carbohydrate diet. Subsequent GTT and ITT experiments have also demonstrated that tryptophan improves glucose tolerance and insulin tolerance in blunt snout bream on a high-carbohydrate diet.In conclusion, these findings elucidate the positive regulatory effect of tryptophan on the PI3K-AKT-GLUT2 pathway under a high carbohydrate diet and provide a theoretical basis for the subsequent rational application of high carbohydrate diets in the future.

TFEB activator tanshinone IIA and derivatives derived from Salvia miltiorrhiza Bge. Attenuate hepatic steatosis and insulin resistance

Ethnopharmacological relevanceSalvia miltiorrhiza Bge. (SMB) is an herbal medicine extensively used for improving metabolic disorders, including Nonalcoholic fatty liver disease (NAFLD). However, the potential material basis and working mechanism still remained to be elucidated. Aim of the studyTo find potential ingredients for therapy of NAFLD by high content screening and further verify the efficacy on restoring hepatic steatosis and insulin resistance, and clarify the potential working mechanism. Materials and methodsThe mouse transcription factor EB (Tfeb) in preadipocytes was knocked out by CRISPR-Cas9 gene editing. High content screening of TFEB nuclear translocation was performed to identify TFEB activators. The effect of candidate compounds on reducing lipid accumulation was evaluated using Caenorhabditis elegans (C. elegans). Then the role of Salvia miltiorrhiza extract (SMB) containing Tanshinone IIA and the derivatives were further investigated on high-fat diet (HFD) fed mice. RNA-seq was performed to explore potential molecular mechanism of SMB. Finally, the gut microbiota diversity was evaluated using 16S rRNA sequencing to investigate the protective role of SMB on regulating gut microbiota homeostasis. ResultsKnockout of Tfeb led to excessive lipid accumulation in adipocytes while expression of TFEB homolog HLH-30 in C. elegans (MAH240) attenuated lipid deposition. Screening of TFEB activators identified multiple candidates from Salvia miltiorrhiza, all of them markedly induced lysosome biogenesis in HepG2 cells. One of the candidate compounds Tanshinone IIA significantly decreased lipid droplet deposition in HFD fed C. elegans. Administration of SMB on C57BL/6J mice via gastric irrigation at the dose of 15 g/kg/d markedly alleviated hepatic steatosis, restored serum lipid profile, and glucose tolerance. RNA-seq showed that gene expression profile was altered and the genes related to lipid metabolism were restored. The disordered microbiome was remodeled by SMB, Firmicutes and Actinobacteriotawere notably reduced, Bacteroidota and Verrucomicrobiota were significantly increased. ConclusionTaken together, the observations presented here help address the question concerning what were the main active ingredients in SMB for alleviating NAFLD, and established that targeting TFEB was key molecular basis for the efficacy of SMB.