Characterization of a murine nonalcoholic steatohepatitis model induced by high fat high calorie diet plus fructose and glucose in drinking water

Sestrin2 in POMC neurons modulates energy balance and obesity related metabolic disorders via mTOR signaling

Sestrin2 is a highly conserved protein that can be induced under various stress conditions. Researches have revealed that the signaling pathway of the mammalian target of rapamycin (mTOR) is essential in modulating both glucose and lipid metabolism. However, the precise involvement of Sestrin2 in the hypothalamus, particularly in pro-opiomelanocortin (POMC) neurons, in control of energy homeostasis remains uncertain. In this study, we aimed to investigate the functional role of Sestrin2 in hypothalamic POMC neurons in regulation of energy balance, as well as revealing the underlying mechanisms. Therefore, cre-dependent AAV virus encoding or silencing Sestrin2 was injected into the hypothalamic ARC of pomc-cre transgenic mice. The results demonstrated that Sestrin2 overexpression in POMC neurons ameliorated high-fat diet (HFD)-induced obesity and increased energy expenditure. Conversely, Sestrin2 deficiency in POMC neurons predisposed mice to HFD induced obesity. Additionally, the thermogenesis of brown adipose tissue and lipolysis of inguinal white adipose tissue were both enhanced by the increased sympathetic nerve innervation in Sestrin2 overexpressed mice. Further exploration revealed that Sestrin2 overexpression inhibited the mTOR signaling pathway in hypothalamic POMC neurons, which may account for the alleviation of systematic metabolic disturbance induced by HFD in these mice. Collectively, our findings demonstrate that Sestrin2 in POMC neurons plays a pivotal role in maintaining energy balance in a context of HFD-induced obesity by inhibiting the mTOR pathway, providing new insights into how hypothalamic neurons respond to nutritional signals to protect against obesity-associated metabolic dysfunction.

Investigation of the Hepatitis-B Vaccine's Immune Response in a Non-Alcoholic Fatty Liver Disease Mouse Model

This study aimed to investigate the immunogenicity of the hepatitis B virus (HBV) vaccine by applying a normal and high-dose hepatitis B virus vaccination program in the mice modeling of non-alcoholic fatty liver disease (NAFLD). NAFLD was induced in mouse livers via diet. At the 10-week mark, both groups were divided into 3 subgroups. While the standard dose vaccination program was applied on days 0, 7, and 21, two high-dose programs were applied: one was applied on days 0 and 7, and the other was applied on days 0, 7, and 21. All mice were euthanized. Blood samples from anti-HB titers; T follicular helper, T follicular regulatory, CD27+, and CD38+ cells; and the liver, spleen, and thymus were taken for histopathologic evaluation. NAFLD subgroups receiving high doses showed higher hepatocyte ballooning scores than normal-dose subgroup. There were differences in CD27+ and CD27+CD38+ cells in animals fed on different diets, without any differences or interactions in terms of vaccine protocols. In the NAFLD group, a negative correlation was observed between anti-HB titers and T helper and CD27+ cells, while a positive correlation was observed with CD38+ cells. NAFLD induced changes in immune parameters in mice, but there was no difference in vaccine efficacy among the applied vaccine protocols. Based on this study's results, high-dose vaccination protocols are not recommended in cases of NAFLD, as they do not enhance efficacy and may lead to increased liver damage.

Repurposing of the analgesic Neurotropin for MASLD/MASH treatment

BACKGROUND

The prevalence of metabolic dysfunction-associated steatotic liver disease (MASLD) has increased in recent decades. Approximately 25% of patients with MASLD progress to metabolic dysfunction-associated steatohepatitis, which is characterized by hepatic steatosis plus hepatocyte damage, inflammation, and fibrosis. We previously reported that Neurotropin (NTP), a drug used for relieving pain in Japan and China, inhibits lipid accumulation in hepatocytes by preventing mitochondrial dysfunction. We hypothesized that inhibiting hepatic steatosis and inflammation by NTP can be an effective strategy for treating MASLD and tested this hypothesis in a MASLD mouse model.

METHODS

Six-week-old C57BL/6NJ male mice were fed a normal diet and normal drinking water or a high-fat diet with high fructose/glucose water for 12 weeks. During the last 6 weeks, the mice were also given high-dose NTP, low-dose NTP, or control treatment. Histologic, biochemical, and functional tests were conducted. MitoPlex, a new proteomic platform, was used to measure mitochondrial proteins, as mitochondrial dysfunction was previously reported to be associated with MASLD progression.

RESULTS

NTP inhibited the development of hepatic steatosis, injury, inflammation, and fibrosis induced by feeding a high-fat diet plus high fructose/glucose in drinking water. NTP also inhibited HSC activation. MitoPlex analysis revealed that NTP upregulated the expression of mitochondrial proteins related to oxidative phosphorylation, the tricarboxylic acid cycle, mitochondrial dynamics, and fatty acid transport.

CONCLUSIONS

Our results indicate that NTP prevents the development of hepatic steatosis, injury, and inflammation by preserving mitochondrial function in the liver and inhibits liver fibrosis by suppressing HSC activation. Thus, repurposing NTP may be a beneficial option for treating MASLD/metabolic dysfunction-associated steatohepatitis.

Dynamic changes of gut microbiota in mouse models of metabolic dysfunction-associated steatohepatitis and its transition to hepatocellular carcinoma

Dysbiosis of gut microbiota may account for pathobiology in simple fatty liver (SFL), metabolic dysfunction-associated steatohepatitis (MASH), fibrotic progression, and transformation to MASH-associated hepatocellular carcinoma (MASH-HCC). The aim of the present study is to investigate gut dysbiosis in this progression. Fecal microbial rRNA-16S sequencing, absolute quantification, histopathologic, and biochemical tests were performed in mice fed high fat/calorie diet plus high fructose and glucose in drinking water (HFCD-HF/G) or control diet (CD) for 2, 16 weeks, or 14 months. Histopathologic examination verified an early stage of SFL, MASH, fibrotic, or MASH-HCC progression with disturbance of lipid metabolism, liver injury, and impaired gut mucosal barrier as indicated by loss of occludin in ileum mucosa. Gut dysbiosis occurred as early as 2 weeks with reduced α diversity, expansion of Kineothrix, Lactococcus, Akkermansia; and shrinkage in Bifidobacterium, Lactobacillus, etc., at a genus level. Dysbiosis was found as early as MAHS initiation, and was much more profound through the MASH-fibrotic and oncogenic progression. Moreover, the expansion of specific species, such as Lactobacillus johnsonii and Kineothrix alysoides, was confirmed by an optimized method for absolute quantification. Dynamic alterations of gut microbiota were characterized in three stages of early SFL, MASH, and its HCC transformation. The findings suggest that the extent of dysbiosis was accompanied with MASH progression and its transformation to HCC, and the shrinking or emerging of specific microbial species may account at least in part for pathologic, metabolic, and immunologic alterations in fibrogenic progression and malignant transition in the liver.

The role of pyroptosis in metabolism and metabolic disease

Pyroptosis is a lytic and pro-inflammatory form of regulated cell death characterized by the formation of membrane pores mediated by the gasdermin protein family. Two main activation pathways have been documented: the caspase-1-dependent canonical pathway and the caspase-4/5/11-dependent noncanonical pathway. Pyroptosis leads to cell swelling, lysis, and the subsequent release of inflammatory mediators, including interleukin-1β (IL-1β) and interleukin-18 (IL-18). Chronic inflammation is a well-established foundation and driver for the development of metabolic diseases. Conversely, metabolic pathway dysregulation can also induce cellular pyroptosis. Recent studies have highlighted the significant role of pyroptosis modulation in various metabolic diseases, including type 2 diabetes mellitus, obesity, and metabolic (dysfunction) associated fatty liver disease. These findings suggest that pyroptosis may serve as a promising novel therapeutic target for metabolic diseases. This paper reviews an in-depth study of the current advancements in understanding the role of pyroptosis in the progression of metabolic diseases.

Exploring the therapeutic potential of silymarin-based herbal remedy (prebiotic) and probiotic blend in a mouse model of NAFLD: Insights into gut microbiota modulation and liver health

Non-alcoholic fatty liver disease (NAFLD) is a significant consequence of metabolic dysfunction, often associated with changes in the intestinal microbiota. Prebiotics and probiotics have shown promise in NAFLD management. This study evaluated a silymarin-based herbal remedy with piperine and fulvic acid, alongside a probiotic blend of Bifidobacterium adolescentis, Bifidobacterium bifidum, Lactobacillus casei, and Lactobacillus rhamnosus. Using a NAFLD mouse model induced by a high-fat and high-fructose diet, we assessed biochemical parameters, liver function, glucose levels, and conducted histological analysis. Stool samples underwent 16S rRNA metagenomic analysis to explore changes in microbiota composition. Mice on the high-fat diet exhibited elevated lipids, liver enzymes, and glucose, with reduced high-density lipoprotein levels (with p value < 0.001). Treatment, particularly with F3 (silymarin-piperine-fulvic acid herbal remedy and probiotic blend), significantly reduced hepatic fat accumulation and improved gut microbiota composition. This study highlights the potential of silymarin-based therapy combined with probiotics in attenuating NAFLD progression.

MASH as an emerging cause of hepatocellular carcinoma: current knowledge and future perspectives

Hepatocellular carcinoma is one of the deadliest and fastest-growing cancers. Among HCC etiologies, metabolic dysfunction-associated fatty liver disease (MAFLD) has served as a major HCC driver due to its great potential for increasing cirrhosis. The obesogenic environment fosters a positive energy balance and results in a continuous rise of obesity and metabolic syndrome. However, it is difficult to understand how metabolic complications lead to the poor prognosis of liver diseases and which molecular mechanisms are underpinning MAFLD-driven HCC development. Thus, suitable preclinical models that recapitulate human etiologies are essentially required. Numerous preclinical models have been created but not many mimicked anthropometric measures and the course of disease progression shown in the patients. Here we review the literature on adipose tissues, liver-related HCC etiologies and recently discovered genetic mutation signatures found in MAFLD-driven HCC patients. We also critically review current rodent models suggested for MAFLD-driven HCC study.

Necroptosis contributes to non-alcoholic fatty liver disease pathoetiology with promising diagnostic and therapeutic functions

Nonalcoholic fatty liver disease (NAFLD) is the most prevalent type of chronic liver disease. However, the disease is underappreciated as a remarkable chronic disorder as there are rare managing strategies. Several studies have focused on determining NAFLD-caused hepatocyte death to elucidate the disease pathoetiology and suggest functional therapeutic and diagnostic options. Pyroptosis, ferroptosis, and necroptosis are the main subtypes of non-apoptotic regulated cell deaths (RCDs), each of which represents particular characteristics. Considering the complexity of the findings, the present study aimed to review these types of RCDs and their contribution to NAFLD progression, and subsequently discuss in detail the role of necroptosis in the pathoetiology, diagnosis, and treatment of the disease. The study revealed that necroptosis is involved in the occurrence of NAFLD and its progression towards steatohepatitis and cancer, hence it has potential in diagnostic and therapeutic approaches. Nevertheless, further studies are necessary.

Hyperacetylated histone H4 is a source of carbon contributing to lipid synthesis

Histone modifications commonly integrate environmental cues with cellular metabolic outputs by affecting gene expression. However, chromatin modifications such as acetylation do not always correlate with transcription, pointing towards an alternative role of histone modifications in cellular metabolism. Using an approach that integrates mass spectrometry-based histone modification mapping and metabolomics with stable isotope tracers, we demonstrate that elevated lipids in acetyltransferase-depleted hepatocytes result from carbon atoms derived from deacetylation of hyperacetylated histone H4 flowing towards fatty acids. Consistently, enhanced lipid synthesis in acetyltransferase-depleted hepatocytes is dependent on histone deacetylases and acetyl-CoA synthetase ACSS2, but not on the substrate specificity of the acetyltransferases. Furthermore, we show that during diet-induced lipid synthesis the levels of hyperacetylated histone H4 decrease in hepatocytes and in mouse liver. In addition, overexpression of acetyltransferases can reverse diet-induced lipogenesis by blocking lipid droplet accumulation and maintaining the levels of hyperacetylated histone H4. Overall, these findings highlight hyperacetylated histones as a metabolite reservoir that can directly contribute carbon to lipid synthesis, constituting a novel function of chromatin in cellular metabolism.

JCAD deficiency delayed liver regenerative repair through the Hippo-YAP signalling pathway

BACKGROUND AND AIMS

Liver regeneration retardation post partial hepatectomy (PH) is a common clinical problem after liver transplantation. Identification of key regulators in liver regeneration post PH may be beneficial for clinically improving the prognosis of patients after liver transplantation. This study aimed to clarify the function of junctional protein-associated with coronary artery disease (JCAD) in liver regeneration post PH and to reveal the underlying mechanisms.

METHODS

JCAD knockout (JCAD-KO), liver-specific JCAD-KO (Jcad△Hep) mice and their control group were subjected to 70% PH. RNA sequencing was conducted to unravel the related signalling pathways. Primary hepatocytes from KO mice were treated with epidermal growth factor (EGF) to evaluate DNA replication. Fluorescent ubiquitination-based cell cycle indicator (FUCCI) live-imaging system was used to visualise the phases of cell cycle.

RESULTS

Both global and liver-specific JCAD deficiency postponed liver regeneration after PH as indicated by reduced gene expression of cell cycle transition and DNA replication. Prolonged retention in G1 phase and failure to transition over the cell cycle checkpoint in JCAD-KO cell line was indicated by a FUCCI live-imaging system as well as pharmacologic blockage. JCAD replenishment by adenovirus reversed the impaired DNA synthesis in JCAD-KO primary hepatocyte in exposure to EGF, which was abrogated by a Yes-associated protein (YAP) inhibitor, verteporfin. Mechanistically, JCAD competed with large tumour suppressor 2 (LATS2) for WWC1 interaction, leading to LATS2 inhibition and thereafter YAP activation, and enhanced expression of cell cycle-associated genes.

CONCLUSION

JCAD deficiency led to delayed regeneration after PH as a result of blockage in cell cycle progression through the Hippo-YAP signalling pathway. These findings uncovered novel functions of JCAD and suggested a potential strategy for improving graft growth and function post liver transplantation.

KEY POINTS

JCAD deficiency leads to an impaired liver growth after PH due to cell division blockage. JCAD competes with LATS2 for WWC1 interaction, resulting in LATS2 inhibition, YAP activation and enhanced expression of cell cycle-associated genes. Delineation of JCADHippoYAP signalling pathway would facilitate to improve prognosis of acute liver failure and graft growth in living-donor liver transplantation.

Perilipin 5 deletion protects against nonalcoholic fatty liver disease and hepatocellular carcinoma by modulating lipid metabolism and inflammatory responses

The molecular mechanisms underlying the transition from nonalcoholic fatty liver disease (NAFLD) to hepatocellular carcinoma (HCC) are incompletely understood. During the development of NAFLD, Perilipin 5 (PLIN5) can regulate lipid metabolism by suppressing lipolysis and preventing lipotoxicity. Other reports suggest that the lack of PLIN5 decreases hepatic injury, indicating a protective role in NAFLD pathology. To better understand the role of PLIN5 in liver disease, we established mouse models of NAFLD and NAFLD-induced HCC, in which wild-type and Plin5 null mice were exposed to a single dose of acetone or 7,12-dimethylbenz[a]anthracene (DMBA) in acetone, followed by a 30-week high-fat diet supplemented with glucose/fructose. In the NAFLD model, RNA-seq revealed significant changes in genes related to lipid metabolism and immune response. At the intermediate level, pathways such as AMP-activated protein kinase (AMPK), signal transducer and activator of transcription 3 (STAT3), c-Jun N-terminal kinase (JNK), and protein kinase B (AKT) were blunted in Plin5-deficient mice (Plin5-/-) compared to wild-type mice (WT). In the NAFLD-HCC model, only WT mice developed liver tumors, while Plin5-/- mice were resistant to tumorigenesis. Furthermore, only 32 differentially expressed genes associated with NALFD progession were identified in Plin5 null mice. The markers of mitochondrial function and immune response, such as the peroxisome proliferator-activated receptor-γ, coactivator 1-α (PGC-1α) and phosphorylated STAT3, were decreased. Lipidomic analysis revealed differential levels of some sphingomyelins between WT and Plin5-/- mice. Interestingly, these changes were not detected in the HCC model, indicating a possible shift in the metabolism of sphingomelins during carcinogenesis.

Gut commensal Kineothrix alysoides mitigates liver dysfunction by restoring lipid metabolism and gut microbial balance

Metabolic dysfunction-associated steatotic liver disease (MASLD), previously known as Non-Alcoholic Fatty Liver Disease, is a widespread liver condition characterized by excessive fat buildup in hepatocytes without significant alcohol consumption. Manipulation of the gut microbiome has been considered to prevent and improve the occurrence and progression of MASLD, particularly through the gut-liver axis. This study aimed to investigate the correlation between the gut microbiome and liver function and determine whether the gut microbiome can ameliorate MASLD. We comparatively analyzed the gut microbiome composition between mice fed normal chow and those fed a high-fat diet and observed that the abundance of Kineothrix alysoides decreased in the high-fat group. Further analysis showed that treatment with K. alysoides in the high-fat diet group led to decreased weight loss, and MASLD attenuation. Importantly, K. alysoides treatment attenuated MASLD in mice fed a high-fat, high-fructose diet (HFHF), which can cause advanced liver damage. Furthermore, administration of K. alysoides altered the gut microbial composition in the HFHF diet group and improved MASLD. Overall, these findings demonstrate the potential of K. alysoides in restoring gut health and facilitating lipid metabolism to prevent and treat MASLD.

Deficiency of gluconeogenic enzyme PCK1 promotes metabolic-associated fatty liver disease through PI3K/AKT/PDGF axis activation in male mice

Metabolic associated fatty liver disease (MAFLD) encompasses a broad spectrum of hepatic disorders, including steatosis, nonalcoholic steatohepatitis (NASH) and fibrosis. We demonstrated that phosphoenolpyruvate carboxykinase 1 (PCK1) plays a central role in MAFLD progression. Male mice with liver Pck1 deficiency fed a normal diet displayed hepatic lipid disorder and liver injury, whereas fibrosis and inflammation were aggravated in mice fed a high-fat diet with drinking water containing fructose and glucose (HFCD-HF/G). Forced expression of hepatic PCK1 by adeno-associated virus ameliorated MAFLD in male mice. PCK1 deficiency stimulated lipogenic gene expression and lipid synthesis. Moreover, loss of hepatic PCK1 activated the RhoA/PI3K/AKT pathway by increasing intracellular GTP levels, increasing secretion of platelet-derived growth factor-AA (PDGF-AA), and promoting hepatic stellate cell activation. Treatment with RhoA and AKT inhibitors or gene silencing of RhoA or AKT1 alleviated MAFLD progression in vivo. Hepatic PCK1 deficiency may be important in hepatic steatosis and fibrosis development through paracrine secretion of PDGF-AA in male mice, highlighting a potential therapeutic strategy for MAFLD.

Sesamin Attenuates Obesity-Associated Nonalcoholic Steatohepatitis in High-Fat and High-Fructose Diet-Fed Mice

This study explored the effects of sesamin on nonalcoholic steatohepatitis (NASH). High-fat and high-fructose diet-fed mice supplemented with or without sesamin. The results suggested that sesamin-treated mice lost body weight and fat tissue weight, had lower levels of serum metabolic parameters, and insulin resistance was mitigated. Histological examinations showed that sesamin treatment mitigated the progression of hepatic steatosis, and inflammation. In addition, sesamin enhanced hepatic antioxidant capacity, and decreased the activations of hepatic c-jun N-terminal kinase, inhibitor of kappa B kinase α, and insulin receptor substrate 1 as well as hepatic interleukin-6 and tumor necrosis factor-alpha levels. Further experiments indicated that sesamin treatment downregulated GRP78 and phospho-inositol-requiring enzyme 1 (IRE1) expression, and upregulated x-box binding protein 1 (XBP1) expression in hepatic tissue. The aforementioned results suggest that sesamin alleviates obesity-associated NASH, which might be linked to the effect of sesamin on the regulation of the hepatic endoplasmic reticulum stress-IRE1/XBP1 pathway. Thus, sesamin may be a good food functional ingredient in the treatment of obesity-associated NASH.

Deficiency of miR-29a/b1 leads to premature aging and dopaminergic neuroprotection in mice

Parkinson’s disease (PD) is a neurodegenerative disorder characterized by progressive degeneration of midbrain dopaminergic neurons. The miR-29s family, including miR-29a and miR-29b1 as well as miR-29b2 and miR-29c, are implicated in aging, metabolism, neuronal survival, and neurological disorders. In this study, the roles of miR-29a/b1 in aging and PD were investigated. miR-29a/b1 knockout mice (named as 29a KO hereafter) and their wild-type (WT) controls were used to analyze aging-related phenotypes. After challenged with the neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), dopaminergic injuries, glial activation, and mouse behaviors were evaluated. Primary glial cells were further cultured to explore the underlying mechanisms. Additionally, the levels of miR-29s in the cerebrospinal fluid (CSF) of PD patients (n = 18) and healthy subjects (n = 17) were quantified. 29a KO mice showed dramatic weight loss, kyphosis, and along with increased and deepened wrinkles in skins, when compared with WT mice. Moreover, both abdominal and brown adipose tissues reduced in 29a KO mice, compared to their WT counterpart. However, in MPTP-induced PD mouse model, the deficiency of miR-29a/b1 led to less severe damages of dopaminergic system and mitigated glial activation in the nigrostriatal pathway, and subsequently alleviated the motor impairments in 3-month-old mice. Eight-month-old mutant mice maintained such a resistance to MPTP intoxication. Mechanistically, the deficiency of miR-29a/b-1 promoted the expression of neurotrophic factors in 1-Methyl-4-phenylpyridinium (MPP⁺)-treated primary mixed glia and primary astrocytes. In lipopolysaccharide (LPS)-treated primary microglia, knockout of miR-29a/b-1 inhibited the expression of inflammatory factors, and promoted the expression of anti-inflammatory factors and neurotrophic factors. Knockout of miR-29a/b1 increased the activity of AMP-activated protein kinase (AMPK) and repressed NF-κB/p65 signaling in glial cells. Moreover, we found miR-29a level was increased in the CSF of patients with PD. Our results suggest that 29a KO mice display the peripheral premature senility. The combined effects of less activated glial cells might contribute to the mitigated inflammatory responses and elicit resistance to MPTP intoxication in miR-29a/b1 KO mice.

High-fat diet combined with dextran sulfate sodium failed to induce a more serious NASH phenotype than high-fat diet alone

Background and Aims: Animal models are essential tools to investigate the pathogenesis of diseases. Disruption in the intestinal epithelial barrier and gut vascular barrier is an early event in the development of non-alcoholic fatty liver disease (NAFLD). Intestinal epithelial barrier can be destroyed by dextran sulfate sodium (DSS) oral administration. High fat diet (HFD)-induced non-alcoholic steatohepatitis (NASH) rat model has been widely used. Recently, the combination of HFD with DSS induced NASH model has also been reported. The present study aimed to evaluate whether this composite NASH animal model is more ideal than that induced by HFD alone.

Methods: Rats were divided into control, HFD and HFD combined with DSS (DSS + HFD) groups. They were fed with routine diet, high-fat diet, and HFD combined with DSS drinking, respectively, for 22 weeks. Histopathological analysis (HE staining, Oil-Red O staining, Masson staining), lipid parameters testing (TG, TC, GLU, NEFA, TRIG, LDL, HDL), testing on indicators of inflammation (TNF-α, ALT, AST, ALP, LDH) and oxidative stress (MDA, SOD, CAT) were performed.

Results: Rats in HFD and DSS + HFD group displayed increase in the body weight, liver weight, lipids accumulation and the levels of TNF-α, ALT, AST, ALP, MDA in serum and liver accompanied with impaired glucose tolerance, obvious hepatitis, and decreased levels of SOD and CAT in serum and liver compared to those in control group. Moreover, in the DSS + HFD group, but not in the HFD group, proliferation of fibrous tissue in the portal area and the hepatic lobules was found.

Conclusion: The addition of DSS on high-fat diet did not exacerbate lipid accumulation and inflammation, but induced NASH-related liver fibrosis.

A non-mitogenic FGF4 analog alleviates non-alcoholic steatohepatitis through an AMPK-dependent pathway

BACKGROUND & AIMS

Non-alcoholic fatty liver disease (NAFLD) has emerged as a major liver disease increasingly in association with non-alcoholic steatohepatitis (NASH), cirrhosis and hepatocellular carcinoma (HCC). However, there are currently no approved therapies for treating NAFLD and NASH. Fibroblast growth factor 4 (FGF4) has recently been shown as a promising drug candidate for several metabolic diseases.

METHODS

Mice fed a high-fat diet with high fructose/glucose drinking water (HF/HFG, Western-like diet) for 21 weeks were intraperitoneally injected with non-mitogenic recombinant FGF4^△NT (rFGF4^△NT, 1.0 mg/kg body weight) every other day for 8 weeks. Primary mouse hepatocytes cultured in medium containing high glucose/palmitic acid (HG/PA) or TNFα/cyclohexane (TNFα/CHX) were treated with 1.0 μg/ml rFGF4^△NT. Changes in parameters for histopathology, lipid metabolism, inflammation, hepatocellular apoptosis and fibrosis were determined. The Caspase6 activity and AMPK pathway were assessed.

RESULTS

Administration of rFGF4^△NT significantly attenuated the Western-like diet-induced hepatic steatosis, inflammation, liver injury and fibrosis in mice. rFGF4^△NT treatment reduced fatty acid-induced lipid accumulation and lipotoxicity-induced hepatocyte apoptosis, which were associated with inhibition of Caspase6 cleavage and activation. Inhibition of AMP-activated protein kinase (AMPK) by Compound C or deficiency of Ampk abrogated rFGF4^△NT-induced hepatoprotection in primary hepatocytes and in mice with NASH.

CONCLUSION

rFGF4^△NT exerts significant protective effects on NASH via an AMPK-dependent signaling pathway. Our study indicates that FGF4 analogs may have therapeutic potential for the Western-like diet induced NASH.

Updates on novel pharmacotherapeutics for the treatment of nonalcoholic steatohepatitis

Nonalcoholic steatohepatitis (NASH) is a progressive form of nonalcoholic fatty liver disease (NAFLD), characterized with hepatocellular steatosis, ballooning, lobular inflammation, fibrotic progression, and insulin resistance. NASH may progress to cirrhosis and hepatocellular carcinoma (HCC), which are the major indications for liver transplantation and the causes for mortality. Thus far, there are no approved pharmacotherapeutics for the treatment of NASH. Given the complexity of NASH pathogenesis at multifaceted aspects, such as lipotoxicity, inflammation, insulin resistance, mitochondrial dysfunction and fibrotic progression, pharmacotherapeutics under investigation target different key pathogenic pathways to gain either the resolution of steatohepatitis or regression of fibrosis, ideally both. Varieties of pharmacologic candidates have been tested in clinical trials and have generated some positive results. On the other hand, recent failure or termination of a few phase II and III trials is disappointing in this field. In face to growing challenges in pharmaceutical development, this review intends to summarize the latest data of new medications which have completed phase II or III trials, and discuss the rationale and preliminary results of several combinatory options. It is anticipated that with improved understanding of NASH pathogenesis and critical endpoints, efficient pharmacotherapeutics will be available for the treatment of NASH with an acceptable safety profile.

Role of the Inflammasome in Liver Disease

The involvement of inflammasomes in the proinflammatory response observed in chronic liver diseases, such as alcohol-associated liver disease (ALD) and nonalcoholic fatty liver disease (NAFLD), is widely recognized. Although there are different types of inflammasomes, most studies to date have given attention to NLRP3 (nucleotide-binding oligomerization domain-like receptor family, pyrin domain containing 3) in the pathogenesis of ALD, NAFLD/nonalcoholic steatohepatitis, and fibrosis. Canonical inflammasomes are intracellular multiprotein complexes that are assembled after the sensing of danger signals and activate caspase-1, which matures interleukin (IL)-1β, IL-18, and IL-37 and also induces a form of cell death called pyroptosis. Noncanonical inflammasomes activate caspase-11 to induce pyroptosis. We discuss the different types of inflammasomes involved in liver diseases with a focus on (a) signals and mechanisms of inflammasome activation, (b) the role of different types of inflammasomes and their products in the pathogenesis of liver diseases, and (c) potential therapeutic strategies targeting components of the inflammasomes or cytokines produced upon inflammasome activation.

The combination of dapagliflozin and statins ameliorates renal injury through attenuating the activation of inflammasome-mediated autophagy in insulin-resistant rats

Long-term use of a high-fat diet with high-fructose (HFF) intake could promote insulin resistance and induce lipid accumulation leading to kidney injury possibly via impairment of the autophagy process and enhancement of the inflammasome pathway. We investigated whether dapagliflozin as a monotherapy or combined with atorvastatin could restore kidney autophagy impairment and reduce inflammasome activation associated with kidney injury induced by HFF consumption. Male Wistar rats were given an HFF for 16 weeks and then treated with dapagliflozin with or without atorvastatin for 4 weeks. Impaired glucose tolerance, dyslipidemia, renal lipid accumulation along with impaired renal autophagy and activated inflammasome pathway promoted renal injury were exhibited in HFF rats. Dapagliflozin with or without atorvastatin treatment could partially restore disrupted metabolic parameters and reduce kidney injury. In particular, the combination treatment group showed significant amelioration of inflammasome activation and autophagy impairment. In conclusion, the combination therapy of dapagliflozin and atorvastatin has a positive effect on renal injury associated with autophagy and inflammasome activation induced by HFF in insulin-resistant rats. This study is the first report demonstrating the underlying mechanism associated with a combination treatment of dapagliflozin and atorvastatin on autophagy and inflammasome pathways in an insulin-resistant condition. Therefore, dapagliflozin in combination with atorvastatin may be a further preventive or therapeutic strategy for chronic kidney disease in an insulin-resistant or diabetic condition.

Prediction of drug efficacy from transcriptional profiles with deep learning

Drug discovery focused on target proteins has been a successful strategy, but many diseases and biological processes lack obvious targets to enable such approaches. Here, to overcome this challenge, we describe a deep learning-based efficacy prediction system (DLEPS) that identifies drug candidates using a change in the gene expression profile in the diseased state as input. DLEPS was trained using chemically induced changes in transcriptional profiles from the L1000 project. We found that the changes in transcriptional profiles for previously unexamined molecules were predicted with a Pearson correlation coefficient of 0.74. We examined three disorders and experimentally tested the top drug candidates in mouse disease models. Validation showed that perillen, chikusetsusaponin IV and trametinib confer disease-relevant impacts against obesity, hyperuricemia and nonalcoholic steatohepatitis, respectively. DLEPS can generate insights into pathogenic mechanisms, and we demonstrate that the MEK-ERK signaling pathway is a target for developing agents against nonalcoholic steatohepatitis. Our findings suggest that DLEPS is an effective tool for drug repurposing and discovery.

LC-MS-based lipidomic analysis in distinguishing patients with nonalcoholic steatohepatitis from nonalcoholic fatty liver

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) is one of the main liver diseases, and its pathologic profile includes nonalcoholic fatty liver (NAFL) and nonalcoholic steatohepatitis (NASH). However, there is no reliable non-invasive parameter in distinguishing NASH from NAFL in clinical practice. The present study was to find a non-invasive way to differentiate these two categories of NAFLD via lipidomic analysis.

METHODS

Lipidomic analysis was used to determine the changes of lipid moieties in blood from 20 NAFL and 10 NASH patients with liver biopsy. Liver histology was evaluated after hematoxylin and eosin staining and Masson's trichrome staining. The profile of lipid metabolites in correlation with steatosis, inflammation, hepatocellular necroptosis, fibrosis, and NAFLD activity score (NAS) was analyzed.

RESULTS

Compared with NAFL patients, NASH patients had higher degree of steatosis, ballooning degeneration, lobular inflammation. A total of 434 different lipid molecules were identified, which were mainly composed of various phospholipids and triacylglycerols. Many lipids, such as phosphatidylcholine (PC) (P-22:0/18:1), sphingomyelin (SM) (d14:0/18:0), SM (d14:0/24:0), SM (d14:0/22:0), phosphatidylethanolamine (PE) (18:0/22:5), PC (O-22:2/12:0), and PC (26:1/11:0) were elevated in the NASH group compared to those in the NAFL group. Specific analysis revealed an overall lipidomic profile shift from NAFL to NASH, and identified valuable lipid moieties, such as PCs [PC (14:0/18:2), PE (18:0/22:5) and PC (26:1/11:0)] or plasmalogens [PC (O-22:0/0:0), PC (O-18:0/0:0), PC (O-16:0/0:0)], which were significantly altered in NASH patients. In addition, PC (14:0/18:2), phosphatidic acid (18:2/24:4) were positively correlated with NAS; whereas PC (18:0/0:0) was correlated positively with fibrosis score.

CONCLUSIONS

The present study revealed overall lipidomic profile shift from NAFL to NASH, identified valuable lipid moieties which may be non-invasive biomarkers in the categorization of NAFLD. The correlations between lipid moieties and NAS and fibrosis scores indicate that these lipid biomarkers may be used to predict the severity of the disease.

Diet-Induced Models of Non-Alcoholic Fatty Liver Disease: Food for Thought on Sugar, Fat, and Cholesterol

Non-alcoholic fatty liver disease (NAFLD) affects approximately 1 in 4 people worldwide and is a major burden to health care systems. A major concern in NAFLD research is lack of confidence in pre-clinical animal models, raising questions regarding translation to humans. Recently, there has been renewed interest in creating dietary models of NAFLD with higher similarity to human diets in hopes to better recapitulate disease pathology. This review summarizes recent research comparing individual roles of major dietary components to NAFLD and addresses common misconceptions surrounding frequently used diet-based NAFLD models. We discuss the effects of glucose, fructose, and sucrose on the liver, and how solid vs. liquid sugar differ in promoting disease. We consider studies on dosages of fat and cholesterol needed to promote NAFLD versus NASH, and discuss important considerations when choosing control diets, mouse strains, and diet duration. Lastly, we provide our recommendations on amount and type of sugar, fat, and cholesterol to include when modelling diet-induced NAFLD/NASH in mice.

Effects of a high-fat diet and global aryl hydrocarbon receptor deficiency on energy balance and liver retinoid status in male Sprague-Dawley rats

The physiological functions of the aryl hydrocarbon receptor (AHR) are only beginning to unfold. Studies in wildtype and AHR knockout (AHRKO) mice have recently disclosed that AHR activity is required for obesity and steatohepatitis to develop when mice are fed with a high-fat diet (HFD). In addition, a line of AHRKO mouse has been reported to accumulate retinoids in the liver. Whether these are universal manifestations across species related to AHR activity level is not known yet. Therefore, we here subjected wildtype and AHRKO male rats (on Sprague-Dawley background) to HFD feeding coupled with free access to 10% sucrose solution and water; controls received a standard diet and water. Although the HFD-fed rats consumed more energy throughout the 24-week feeding regimen, they did not get overweight. However, relative weights of the brown and epididymal adipose tissues were elevated in HFD-fed rats, while that of the liver was lower in AHRKO than wildtype rats. Moreover, the four groups exhibited diet- or genotype-dependent differences in biochemical variables, some of which suggested marked dissimilarities from AHRKO mice. Expression of pro- and anti-inflammatory genes was induced in livers of HFD-fed AHRKO rats, but histologically they did not differ from others. HFD reduced the hepatic concentrations of retinyl palmitate, 9-cis-4-oxo-13,14-dihydroretinoic acid and (suggestively) retinol, whereas AHR status had no effect. Hence, the background strain/line of AHRKO rat is resistant to diet-induced obesity, and AHR does not modulate this or liver retinoid concentrations. Yet, subtle AHR-dependent differences in energy balance-related factors exist despite similar weight development.

Saskatoon berry powder reduces hepatic steatosis and insulin resistance in high fat-high sucrose diet-induced obese mice

Non-alcoholic fatty liver disease is a common metabolic disorder associated with insulin resistance and lacks a specific treatment. Our previous studies demonstrated that freeze-dried Saskatoon berry powder (SBp) reduced high fat-high sucrose (HFHS) diet-induced hyperglycemia and insulin resistance in mice. The present study examined the effect of SBp and one of its active components, cyanidin-3-glucoside (C3G), on hepatic steatosis in mice fed with HFHS diet for 10 weeks. HFHS diet significantly increased fasting plasma glucose, cholesterol, triglycerides, insulin resistance, inflammatory markers (tumor necrosis factor-α, monocyte chemotactic protein-1, plasminogen activator inbitor-1), alanine aminotransferase activity, and monocyte adhesion compared to control diet. In the liver, HFHS diet increased steatosis, lipid accumulation, collagen deposition, and the abundance of patatin-like phospholipase domain-containing 3, CCAAT-enhancer-binding protein homologous protein, toll-like receptor-4, and macrophage marker. Supplementation with SBp (5%) or C3G in an amount corresponding to that in 5% SBp to HFHS diet had similar effects to reduced fasting plasma glucose, liver steatosis, enzyme activity, lipid, collagen and macrophage deposition, hyperglycemia, hyperlipidemia, insulin resistance, monocyte adhesion, markers related to liver steatosis, inflammation, oxidative or endoplasmic reticulum stress in the peripheral circulation and/or liver compared to mice fed with HFHS diet alone. No significant difference in the studied variables was detected between mice treated with HFHS+SBp and C3G diet. The results suggest that SBp or C3G administration attenuates HFHS diet-induced liver steatosis in addition to insulin resistance and chronic inflammation in mice. C3G may contribute to the beneficial effects of SBp.

NLRP3 deficiency did not attenuate NASH development under high fat calorie diet plus high fructose and glucose in drinking water

NOD-like receptor protein 3 (NLRP3) promotes the inflammatory response during progression of nonalcoholic fatty liver (NAFL) to nonalcoholic steatohepatitis (NASH). This study aimed to further delineate the role of NLRP3 in NASH development by abolishing its expression in mice. A high-fat and calorie diet plus high fructose and glucose in drinking water (HFCD-HF/G) was used to establish NASH in both wild-type (WT) and NLRP3 knock-out (KO) mice. Hepatocellular injury, hepatic steatosis and fibrosis, as well as inflammatory response and insulin resistance in the liver and epidydimal white adipose tissue (eWAT) were determined. Elevated body weight, liver weight and serum alanine transaminase level, increased hepatic triglyceride accumulation and collagen deposition, and worsened systemic insulin resistance were observed in Nlrp3-/- mice compared to WT mice under HFCD-HF/G feeding. Upregulated hepatic transcription of tumor necrosis factor-α (TNF-α) and monocyte chemotactic protein-1 (MCP-1), and enhanced infiltration of inducible nitric oxide synthase-positive (iNOS+) M1 macrophages were also documented in HFCD-HF/G-fed Nlrp3-/- mice in comparison to HFCD-HF/G-fed WT mice. Moreover, transcription of TNF-α and MCP-1 and infiltration of iNOS+ M1 macrophages were increased in the liver of Nlrp3-/- mice under control diet. NLRP3 deficiency did not attenuate, but instead aggravated NASH development under HFCD-HF/G feeding. The worsened extent of NASH might be attributed to enhanced hepatic MCP-1 expression and M1 macrophage infiltration in Nlrp3-/- mice. Our study points to additional caution when NLRP3 blockade is considered as a therapeutic strategy in the treatment of human NASH.

Berberine attenuates non-alcoholic steatohepatitis by regulating chemerin/CMKLR1 signalling pathway and Treg/Th17 ratio

To observe the therapeutic effect of berberine (BBR) on non-alcoholic steatohepatitis (NASH) in rats and the underlying mechanism. A rat model of NASH was established by a high-fat diet, and BBR was used as treatment. Haematoxylin-eosin staining and Oil Red O staining were used to observe the pathological changes in the liver tissue. Western blotting and real-time PCR were used to measure the mRNA and protein levels in the liver. Flow cytometry was performed to detect the number of intrahepatic lymphocyte subtypes. The expression of pro-inflammatory cytokines in the peripheral blood was measured by ELISA. An automatic biochemical method was used to examine the level of blood lipids in the blood. Compared with the rats in the model group, the rats in the BBR group showed significantly improved liver histopathology and serum pro-inflammatory cytokines and free fatty acid (FFA) levels. Moreover, the protein and mRNA expression of chemerin, CMKLR1 and CCR2 in the liver were obviously reduced by BBR treatment. In addition, the high-fat diet remarkably reduced the intrahepatic Treg/Th17 ratio, which could be recovered by BBR treatment. Berberine can ameliorate non-alcoholic steatohepatitis, and its mechanism may be related to restoring the Treg/Th17 ratio, regulating the chemerin/CMKLR1 signalling pathway to reduce liver inflammation and reducing lipid deposition.

Deletion of Sox9 in the liver leads to hepatic cystogenesis in mice by transcriptionally downregulating Sec63

Hepatic cysts are found in heterogeneous disorders with different pathogeneses, of which simple hepatic cysts and polycystic liver diseases are two major types. The process of hepatic cytogenesis for these two diseases is caused by defects in remodelling of the ductal plate during biliary tract development, which is called ductal plate malformation. SOX9 is a transcription factor participating in the process of bile duct development, and thus, its dysregulation may play important roles in hepatic cystogenesis. SEC63 encodes an endoplasmic reticulum membrane protein that is mutated in human autosomal dominant polycystic liver disease. However, the transcriptional regulation of SEC63 is largely unknown. In the present study, a liver-specific Sox9 knockout (Sox9^LKO ) mouse was generated to investigate the roles and underlying mechanism of SOX9 in hepatic cystogenesis. We found that hepatic cysts began to be observed in Sox9^LKO mice at 6 months of age. The number and size of cysts increased with age in Sox9^LKO mice. In addition, the characteristics of hepatic cytogenesis, including the activation of proliferation, absence of primary cilium, and disorder of polarity in biliary epithelial cells, were detected in the livers of Sox9^LKO mice. RNAi silencing of SOX9 in human intrahepatic biliary epithelial cells (HIBEpic) resulted in increased proliferation and reduced formation of the primary cilium. Moreover, Sec63 was downregulated in primary biliary epithelial cells from Sox9^LKO mice and SEC63 in HIBEpic transfected with siSOX9. Chromatin immunoprecipitation assays and luciferase reporter assays further demonstrated that SOX9 transcriptionally regulated the expression of SEC63 in biliary epithelial cells. Importantly, the overexpression of SEC63 in HIBEpic partially reversed the effects of SOX9 depletion on the formation of primary cilia and cell proliferation. These findings highlight the biological significance of SOX9 in hepatic cytogenesis and elucidate a novel molecular mechanism underlying hepatic cytogenesis. © 2021 The Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Serum lipocalin-2 is a potential biomarker for the clinical diagnosis of nonalcoholic steatohepatitis

Background/Aims

Nonalcoholic steatohepatitis (NASH) is a progressive form of nonalcoholic fatty liver disease (NAFLD) characterized by hepatic steatosis, inflammation, hepatocellular injury, and fibrosis. We aimed to investigate the usefulness of a key biomarker, lipocalin-2 (LCN2), for the detection of NASH progression.

Methods

A mouse NASH model was established using a high-fat diet and a high-sugar drinking water. Gene expression profile of the NASH model was analyzed using RNA sequencing. Moreover, 360 NAFLD patients (steatosis, 83; NASH, 277), 40 healthy individuals, and 87 patients with alcoholic fatty liver disease were recruited.

Results

Inflammatory infiltration, focal necrosis in the leaflets, steatosis, and fibrosis were documented in the mouse liver. In total, 504 genes were differentially expressed in the livers of NASH mice, and showed significant functional enrichment in the inflammation-related category. Upregulated liver LCN2 was found to be significantly interactive with various interleukins and toll-like receptors. Serum LCN2 levels were significantly increased in NAFLD patients. Serum LCN2 levels were correlated with steatosis, intralobular inflammation, semiquantitative fibrosis score, and nonalcoholic fatty liver disease activity score. The area under the curve of serum LCN2 was 0.987 with a specificity of 100% and a sensitivity of 93.5% for NASH diagnosis, and 0.977 with almost the same specificity and sensitivity for steatosis.

Conclusions

LCN2 might be involved in the transition from NAFL to NASH by mediating inflammation. Serum LCN2 levels might be a novel biomarker for the diagnosis of NASH.

The pharmacodynamic and differential gene expression analysis of PPAR α/δ agonist GFT505 in CDAHFD-induced NASH model

Peroxisome proliferator-activated receptor α/δ (PPAR α/δ), regulating glucolipid metabolism and immune inflammation, has been identified as an effective therapeutic target in non-alcoholic steatohepatitis (NASH). Dual PPAR α/δ agonist, such as GFT505 (also known as elafibranor), demonstrated potential therapeutic effect for NASH in clinical trials. To profile the regulatory network of PPAR α/δ agonist in NASH, the choline-deficient, L-amino acid-defined, high-fat diet (CDAHFD) induced NASH model was used to test the pharmacodynamics and transcriptome regulation of GFT505 in this study. The results showed that GFT505 ameliorated hepatic steatosis, inflammation and fibrosis in CDAHFD mice model. RNA-sequencing yielded 3995 up-regulated and 3576 down-regulated genes with GFT505 treatment. And the most significant differentialy expressed genes involved in glucolipid metabolism (Pparα, Acox1, Cpt1b, Fabp4, Ehhadh, Fabp3), inflammation (Ccl6, Ccl9, Cxcl14) and fibrosis (Timp1, Lamc3, Timp2, Col3a1, Col1a2, Col1a1, Hapln4, Timp3, Pik3r5, Pdgfα, Pdgfβ, Tgfβ1, Tgfβ2) were confirmed by RT-qPCR. The down-regulated genes were enriched in cytokine-cytokine receptor interaction pathway and ECM-receptor interaction pathway, while the up-regulated genes were enriched in PPAR signaling pathway and fatty acid degradation pathway. This study provides clues and basis for further understanding on the mechanism of PPAR α/δ agonist on NASH.

The American lifestyle-induced obesity syndrome diet in male and female rodents recapitulates the clinical and transcriptomic features of nonalcoholic fatty liver disease and nonalcoholic steatohepatitis

The pathogenesis of nonalcoholic fatty liver disease (NAFLD) and the progression to nonalcoholic steatohepatitis (NASH) and increased risk of hepatocellular carcinoma remain poorly understood. Additionally, there is increasing recognition of the extrahepatic manifestations associated with NAFLD and NASH. We demonstrate that intervention with the American lifestyle-induced obesity syndrome (ALIOS) diet in male and female mice recapitulates many of the clinical and transcriptomic features of human NAFLD and NASH. Male and female C57BL/6N mice were fed either normal chow (NC) or ALIOS from 11 to 52 wk and underwent comprehensive metabolic analysis throughout the duration of the study. From 26 wk, ALIOS-fed mice developed features of hepatic steatosis, inflammation, and fibrosis. ALIOS-fed mice also had an increased incidence of hepatic tumors at 52 wk compared with those fed NC. Hepatic transcriptomic analysis revealed alterations in multiple genes associated with inflammation and tissue repair in ALIOS-fed mice. Ingenuity Pathway Analysis confirmed dysregulation of metabolic pathways as well as those associated with liver disease and cancer. In parallel the development of a robust hepatic phenotype, ALIOS-fed mice displayed many of the extrahepatic manifestations of NAFLD, including hyperlipidemia, increased fat mass, sarcopenia, and insulin resistance. The ALIOS diet in mice recapitulates many of the clinical features of NAFLD and, therefore, represents a robust and reproducible model for investigating the pathogenesis of NAFLD and its progression.NEW & NOTEWORTHY Nonalcoholic fatty liver disease (NAFLD) affects 30% of the general population and can progress to nonalcoholic steatohepatitis (NASH) and potentially hepatocellular carcinoma. Preclinical models rely on mouse models that often display hepatic characteristics of NAFLD but rarely progress to NASH and seldom depict the multisystem effects of the disease. We have conducted comprehensive metabolic analysis of both male and female mice consuming a Western diet of trans fats and sugar, focusing on both their hepatic phenotype and extrahepatic manifestations.

Mitigation of renal inflammation and endoplasmic reticulum stress by vildagliptin and statins in high-fat high-fructose diet-induced insulin resistance and renal injury in rats

Dyslipidemia and insulin resistance in obesity can lead to lipotoxicity and cellular damage. Renal lipotoxicity in association with an impairment of lipid metabolism induces renal damage through the activation of inflammation, ER stress, fibrosis and apoptosis. We investigated the effects of a combination treatment of the DPP-4 inhibitor vildagliptin and atorvastatin on renal lipotoxicity related to renal dysfunction and injury in a high-fat high-fructose diet (HFF)-induced insulin resistant condition. Male Wistar rats were fed on a high-fat diet and were given drinking water with 10% fructose for 16 weeks. After that, rats were divided into: no treatment (HFF), treatment with vildagliptin, atorvastatin and vildagliptin plus atorvastatin for 4 weeks. The results demonstrated that the combination treatment prominently improved insulin resistance, dyslipidemia and kidney morphological changes induced by HFF. These changes correlated well with the increased expression of nephrin and podocin and decreased urine protein. Notably, the combined treatment produced greater improvement in renal lipid metabolism through increasing fatty acid oxidation with the decreases in fatty acid transporters and fatty acid synthesis, thereby reducing renal lipid accumulation in HFF rats. The reduction in renal lipotoxicity via diminishing renal inflammation, ER stress, fibrosis and apoptosis was also more significant in the combined treatment group than in the other groups in which the drug was used as a monotherapy. In conclusion, the combination therapy produced synergistic beneficial effects on metabolic parameters, lipid metabolism and accumulation related to renal lipid accumulation-induced lipotoxicity and kidney injury in the HFF-induced insulin resistant model with improved outcomes.

Succinate-GPR-91 receptor signalling is responsible for nonalcoholic steatohepatitis-associated fibrosis: Effects of DHA supplementation

BACKGROUND AND AIMS

Treatment of non-alcoholic steatohepatitis (NASH) is challenging, because suppressing fibrotic progression has not been achieved consistently by drug candidates currently in clinical trials. The aim of this study was to investigate the molecular interplays underlying NASH-associated fibrosis in a mouse NASH model and human specimens.

METHODS

Mice were divided into 4 groups: Controls; NASH (high fat/Calorie diet plus high fructose and glucose in drinking water, HFCD-HF/G) for 16 weeks; HFCD-HF/G plus docosahexaenoic acid (DHA) for 16 or 8 weeks.

RESULTS

Along with NASH progression, fibrotic deposition was documented in HFCD-HF/G-fed mice. Liver succinate content was significantly increased along with decreased expression of succinate dehydrogenase-A (SDH-A) in these mice; whereas, GPR-91 receptor expression was much enhanced in histology compared to control mice, and co-localized histologically with hepatic stellate cells (HSCs). Succinate content was increased in fatty acid-overloaded primary hepatocytes with significant oxidant stress and lipotoxicity. Exposure to succinate led to up-regulation of GPR-91 receptor in primary and immortalized HSCs. In contrast, suppression of GPR-91 receptor expression abolished succinate stimulatory role in GPR-91 expression and extracellular matrix production in HSCs. All these changes were minimized or abrogated by DHA supplementation in vivo or in vitro. Moreover, GPR-91 receptor expression correlates with severity of fibrosis in human NASH biopsy specimens.

CONCLUSION

Succinate accumulation in steatotoic hepatocytes may result in HSC activation through GPR-91 receptor signalling in NASH progression, and the cross-talk between hepatocytes and HSC through GPR-91 signalling is most likely to be the molecular basis of fibrogenesis in NASH.

Hepalatide ameliorated progression of nonalcoholic steatohepatitis in mice

BACKGROUND

No FDA-approved medications are available for the treatment of nonalcoholic steatohepatitis (NASH). The present study aimed to assess the effects of Hepalatide, a sodium taurocholate cotransporting polypeptide (NTCP) receptor-binding agent, on metabolic and histopathologic changes of a mouse model of NASH caused by high fat/calorie diet plus high fructose/glucose in drinking water (HFCD-HF/G) for 16 weeks.

METHODS

Male mice were randomly divided into 4 groups: controls (normal diet), HFCD-HF/G group, HFCD-HF/G plus low or high dose of Hepalatide (20 or 60 mg/kg, LH or HH, s.c. from 9 to 16 weeks).

RESULTS

Compared to HFCD-HF/G-fed mice, serum triglyceride and cholesterol levels in mice fed HFCD-HF/G plus LH or HH were decreased. The treatment with Hepalatide decreased serum alanine aminotransferase levels significantly. Liver histology and TUNEL staining showed that Hepalatide remarkably attenuated inflammation, hepatocellular steatosis and apoptosis. Hepalatide treatment decreased fasting blood glucose, serum insulin and HOMA insulin resistance index in the HH group. Moreover, Masson's staining, semi-quantitative score of fibrosis, and hydroxyproline content demonstrated that Hepalatide mitigated fibrotic progression in this murine NASH model. Additionally, most components of liver and few serum bile acids were increased in mice treated with HH.

CONCLUSION

Hepalatide effectively alleviated the pathological process, metabolic profile, hepatocellular steatosis and injury, insulin resistance, halted hepatic fibrotic progression in a mouse model of NASH, most likely through the increase of serum bile acids.

Yin Zhi Huang, a traditional Chinese herbal formula, ameliorates diet-induced obesity and hepatic steatosis by activating the AMPK/SREBP-1 and the AMPK/ACC/CPT1A pathways

Background

Yin Zhi Huang (YZH) is a formula composed of Artemisia scoparia, Gardeniae fructus, Scutellaria baicalensis Georgi, and Lonicerae Japonicae Flos. Most of the components are eaten as food in Asia. Here, we evaluated the role of YZH on a high-fat diet (HFD)-induced obesity and hepatic steatosis.

Methods

Male C57BL/6J mice were fed with normal-chow diet, HFD, and HFD with low- or high-dose YZH for 16 weeks. Body weight gain, adipose mass, and plasma lipids levels were measured to evaluate the effect of YZH on obesity. Liver weight and staining methods on liver tissues were used to determine hepatic steatosis. The expression of involved genes and proteins were screened with qRT-PCR and immunoblotting, respectively.

Results

The results showed that YZH significantly reduced body weight gain, adipose mass, and the size of adipocytes, while did not affect food intake in HFD-fed mice. H&E staining, bodipy staining, and oil red O staining displayed that YZH alleviates hepatic lipid accumulation. It also effectively restored elevated plasma levels of triglycerides (TG), total cholesterol (TC), alanine aminotransferase, and aspartate aminotransferase in HFD-fed mice. Mechanistically, these effects of YZH have associated with a decrease of AMPK/SREBP-1 pathway-mediated de novo lipogenesis and an increase of AMPK/ACC/CPT1A pathway-mediated mitochondrial fatty acid β oxidation.

Conclusions

YZH supplementation ameliorated diet-induced obesity and hepatic steatosis by decreasing AMPK/SREBP-1 pathway-mediated de novo lipogenesis and increasing AMPK/ACC/CPT1A pathway-mediated mitochondrial fatty acid β oxidation.

Novel Chemical Scaffolds to Inhibit the Neutral Amino Acid Transporter B0AT1 (SLC6A19), a Potential Target to Treat Metabolic Diseases

Lack of B⁰AT1 (SLC6A19) partially protects mice against the onset of non-alcoholic steatohepatitis (NASH). To achieve a similar outcome through pharmacological treatment, we improved previously identified inhibitors of B⁰AT1 by medicinal chemistry and identified second generation inhibitors by high through-put screening. Modified diarylmethine compounds inhibited B⁰AT1 with IC₅₀ values ranging from 8-90 μM. A second generation of inhibitors was derived from high-throughput screening and showed higher affinity (IC₅₀ of 1-15 μM) and strong selectivity against amino acid transporters with similar substrate specificity, such as ASCT2 (SLC1A5) and LAT1 (SLC7A5). All compounds were unrelated to B⁰AT1 substrates, but were likely to bind in the vicinity of the substrate binding site.

Saroglitazar Deactivates the Hepatic LPS/TLR4 Signaling Pathway and Ameliorates Adipocyte Dysfunction in Rats with High-Fat Emulsion/LPS Model-Induced Non-alcoholic Steatohepatitis

The most epidemic liver disorder non-alcoholic steatohepatitis (NASH) is characterized by hepatic steatosis and inflammation with hepatocellular damage. Recently, it is predictable to be the extensive cause for liver transplantation. The absence of an approved therapeutic agent for NASH is the reason for investigating saroglitazar (SAR) which showed promising effects as a dual PPAR-α/γ agonist in recent studies on NASH. Here, we aimed to investigate the effect of SAR on NASH induced in rats by the administration of high-fat emulsion (HFE) and small doses of lipopolysaccharides (LPS) for 5 weeks. Rats were divided into three groups: negative control group (saline and standard rodent chow), model group (HFE(10 ml/kg/day, oral gavage) + LPS(0.5 mg/kg/week, i.p)), and SAR-treated group (HFE(10 ml/kg/day, oral gavage) + LPS(0.5 mg/kg/week, i.p.) + SAR(4 mg/kg/day, oral gavage) starting at week 3.Treatment with SAR successfully ameliorated the damaging effects of HFE with LPS, by counteracting body weight gain and biochemically by normalization of liver function parameters activity, glucose, insulin, homeostasis model of assessment (HOMA-IR) score, lipid profile levels, and histopathological examination. Significant changes in adipokine levels were perceived, resulting in a significant decline in serum leptin and tumor necrosis factor-α (TNF-α) level concurrent with adiponectin normalization. The positive effects observed for SAR on NASH are due to the downregulation of the LPS/TLR4 pathway, as indicated by the suppression of hepatic Toll-like receptor 4 (TLR4), NF-κB, TNF-α, and transforming growth factor-β1 (TGF-β1) expression. In conclusion, this work verified that SAR ameliorates NASH through deactivation of the hepatic LPS/TLR4 pathway and inhibition of adipocyte dysfunction.

Impaired mitophagy triggers NLRP3 inflammasome activation during the progression from nonalcoholic fatty liver to nonalcoholic steatohepatitis

Activation of inflammation is an important mechanism in the development of nonalcoholic steatohepatitis (NASH). This study aims to delineate how mitophagy affects NLRP3 inflammasome activation in hepatic lipotoxicity. Mice were fed a high fat/calorie diet (HFCD) for 24 weeks. Primary rat hepatocytes were treated with palmitic acid (PA) for various periods of time. Mitophagy was measured by protein levels of LC3II and P62. NLRP3, caspase-1, interleukin (IL)-18, and IL-1β at mRNA and protein levels were used as indicators of inflammasome activation. Along with steatotic progression in HFCD-fed mice, ratio of LC3II/β-actin was decreased concurrently with increased levels of liver P62, NLRP3, caspase-1, IL-1β, IL-18, and serum IL-1β levels in late-stage NASH. PA treatment resulted in mitochondrial oxidative stress and initiated mitophagy in primary hepatocytes. The addition of cyclosporine A did not change LC3II/Τοmm20 ratios; but P62 levels were increased after an extended duration of PA exposure, indicating a defect in autophagic activity. Along with impaired mitophagy, mRNA and protein levels of NLRP3, caspase-1, IL-18 and IL-1β were upregulated by PA treatment. Pretreatment with MCC950, N-acetyl cysteine or acetyl-L-carnitine reversed inflammasome activation and a pyroptotic cascade. Additionally, mitophagic flux was partially recovered as indicated by increases in LC3II/Tomm20 ratio, parkin, and PINK1 expression, and decreased P62 expression. The findings suggest that impaired mitophagy triggers hepatic NLRP3 inflammasome activation in a murine NASH model and primary hepatocytes. The new insights into inflammasome activation through mitophagy advance our understanding of how fatty acids elicit lipotoxicity through oxidant stress and autophagy in mitochondria.

Short-term High Fructose Intake Reprograms the Transcriptional Clock Rhythm of the Murine Extraorbital Lacrimal Gland

Purpose

To determine whether high fructose intake (HFI) influences the daily transcriptional clock rhythms of murine extraorbital lacrimal glands (ELGs).

Methods

Timed ELGs were collected from two groups of C57BL/6J mice subjected to a 12-hour light/12-hour dark (LD) cycle for 10 days; the first group received water-only feeding and the second received water with 15% fructose. Total RNA was extracted and subjected to RNA sequencing. A JTK_CYCLE algorithm and computational software were used to determine the periodicity, rhythmicity, and amplitude of the cycling transcripts. The rhythmic transcripts from different conditions were analyzed using the Kyoto Encyclopedia of Genes and Genomes (KEGG) database.

Results

HFI feeding caused massive remodeling of the preexisting rhythmic genes in the normal control (NC)-fed ELGs. The induced transcripts in HFI-fed mice resulted in a profound reorganization of the coordinated transcriptional oscillations and KEGG pathways. Moreover, HFI feeding significantly altered the distribution of the KEGG pathways over an LD in the ELGs. Finally, we found that the ELGs have a robust core clock machinery and HFI feeding altered amplitude and the peak phase of clock gene transcriptional oscillation in ELGs.

Conclusions

Short-term HFI reprograms the daily transcriptomic oscillation of murine ELGs. This information may deepen our understanding of the outcomes of lacrimal glands altered by nutritional challenge.

Metformin attenuates the onset of non-alcoholic fatty liver disease and affects intestinal microbiota and barrier in small intestine

The antidiabetic drug metformin has been proposed to affect non-alcoholic fatty liver disease (NAFLD) through its effects on intestinal microbiota and barrier function. However, so far most studies focused on long-term effects and more progressed disease stages. The aim of this study was to assess in two experimental settings, if the onset of NAFLD is associated with changes of intestinal microbiota and barrier function and to determine effects of metformin herein. C57Bl/6J mice were fed a liquid control diet (C) or fat-, fructose- and cholesterol-rich diet (FFC) for four days or six weeks ±300 mg/kg BW/day metformin (Met). Markers of liver health, intestinal barrier function and microbiota composition were assessed. Metformin treatment markedly attenuated FFC-induced NAFLD in both experiments with markers of inflammation and lipidperoxidation in livers of FFC + Met-fed mice being almost at the level of controls. Metformin treatment attenuated the loss of tight junction proteins in small intestine and the increase of bacterial endotoxin levels in portal plasma. Changes of intestinal microbiota found in FFC-fed mice were also significantly blunted in FFC + Met-fed mice. Taken together, protective effects of metformin on the onset of NAFLD are associated with changes of intestinal microbiota composition and lower translocation of bacterial endotoxins.

Cholesterol cholelithiasis: part of a systemic metabolic disease, prone to primary prevention

Cholesterol gallstone disease have relationships with various conditions linked with insulin resistance, but also with heart disease, atherosclerosis, and cancer. These associations derive from mechanisms active at a local (i.e. gallbladder, bile) and a systemic level and are involved in inflammation, hormones, nuclear receptors, signaling molecules, epigenetic modulation of gene expression, and gut microbiota. Despite advanced knowledge of these pathways, the available therapeutic options for symptomatic gallstone patients remain limited. Therapy includes oral litholysis by the bile acid ursodeoxycholic acid (UDCA) in a small subgroup of patients at high risk of postdissolution recurrence, or laparoscopic cholecystectomy, which is the therapeutic radical gold standard treatment. Cholecystectomy, however, may not be a neutral event, and potentially generates health problems, including the metabolic syndrome. Areas covered: Several studies on risk factors and pathogenesis of cholesterol gallstone disease, acting at a systemic level have been reviewed through a PubMed search. Authors have focused on primary prevention and novel potential therapeutic strategies. Expert commentary: The ultimate goal appears to target the manageable systemic mechanisms responsible for gallstone occurrence, pointing to primary prevention measures. Changes must target lifestyles, as well as experimenting innovative pharmacological tools in subgroups of patients at high risk of developing gallstones.

Medium-chain triglyceride reinforce the hepatic damage caused by fructose intake in mice

We aimed to investigate the effects of medium-chain triglyceride oil on the high fructose diet-provoked hepatic abnormalities in mice. We used C57bl/6 mice of 3-months-old divided into four groups for 12 weeks: control (C), control with MCT (C-MCT), fructose (F), and fructose with MCT (F-MCT). We investigated food and water intake, body mass, blood pressure, glucose tolerance, plasma and liver biochemistry, hepatic protein and gene expression. There were no changes in body mass, food intake and glucose tolerance among the groups. The F group presented increased water intake and blood pressure associated with hepatic steatosis and elevated de novo lipogenesis, beta-oxidation, mitochondrial biogenesis and inflammation in the liver. Surprisingly, the C-MCT group also showed hepatic steatosis and inflammation in the liver, and the F-MCT group had no exacerbations of fructose-induced abnormalities, showing marked hepatic steatosis, lipogenesis de novo and hepatic inflammation. The MCT oil groups also presented increased beta-oxidation and mitochondrial biogenesis. In conclusion, MCT oil showed detrimental hepatic effects and should be used with caution, especially in the presence of hepatic alterations.

Oleiferasaponin A₂, a Novel Saponin from Camellia oleifera Abel. Seeds, Inhibits Lipid Accumulation of HepG2 Cells Through Regulating Fatty Acid Metabolism

A new triterpenoid saponin, named oleiferasaponin A₂, was isolated and identified from Camellia oleifera defatted seeds. Oleiferasaponin A₂ exhibited anti-hyperlipidemic activity on HepG2 cell lines. Further study of the hypolipidemic mechanism showed that oleiferasaponin A₂ inhibited fatty acid synthesis by significantly down-regulating the expression of SREBP-1c, FAS and FAS protein, while dramatically promoting fatty acid β-oxidation by up-regulating the expression of ACOX-1, CPT-1 and ACOX-1 protein. Our results demonstrate that the oleiferasaponin A₂ possesses potential medicinal value for hyperlipidemia treatment.