Pterostilbene alleviated NAFLD via AMPK/mTOR signaling pathways and autophagy by promoting Nrf2

Targeting the smooth muscle cell KEAP1-Nrf2-STING axis with pterostilbene attenuates abdominal aortic aneurysm

BACKGROUND

Abdominal aortic aneurysm (AAA) is a life-threatening aortic disease, and to date, there are currently no effective pharmacological treatments to address this condition. Activation of cytosolic DNA sensing adaptor stimulator of interferon genes (STING) signaling is a crucial mechanism in AAA formation.

PURPOSE

This study investigated pterostilbene (Pt), a naturally occurring polyphenol and resveratrol analogue, as a STING inhibitor for preventing AAA.

METHODS

We evaluated the effect of Pt on AAA formation in angiotensin II (AngII)-infused apolipoprotein E-deficient (ApoE-/-) mice. We used histological analysis, MMP activity measurement, western blot, and immunohistochemistry to detect AAA formation and development. We applied RNA sequencing, molecular docking, cellular thermal shift assay (CETSA) and functional studies to dissect the molecular mechanism of Pt-regulating KEAP1-Nrf2-STING signaling. We conditionally knocked down Nrf2 in vascular smooth muscle cells (VSMCs) in vivo to investigate its role in Pt-mediated protective effects on AAA.

RESULTS

Pt effectively blocked the formation of AAA in AngII-infused ApoE-/- mice. Whole transcriptome sequencing analysis revealed that nuclear factor erythroid 2-related factor 2 (Nrf2) and STING pathway in VSMCs were linked to the anti-AAA effects of pterostilbene. Mechanistically, Pt upregulated Nrf2 target genes (e.g., HO-1 and NQO1) through activation of the KEAP1/Nrf2 signaling, which restricted the immunostimulatory axis of mtDNA-STING-TBK1-NF-κB, thereby alleviating VSMC inflammation and preserving the VSMC contractile phenotype. Subsequently, molecular docking and CETSA revealed a binding mode between Pt and KEAP1/Nrf2. Intriguingly, the inhibitory effect of Pt on STING signaling and the protective role of Pt in AAA were largely abrogated by VSMC-specific Nrf2 knockdown in mice.

CONCLUSION

Collectively, naturally derived Pt shows promising efficacy for the treatment of AAA by targeting the KEAP1-Nrf2-STING axis in VSMCs.

Targeting antioxidant factor Nrf2 by raffinose ameliorates lipid dysmetabolism-induced pyroptosis, inflammation and fibrosis in NAFLD

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) is a persistent liver condition that affects both human health and animal productive efficiency on a global scale. A number of naturally occurring compounds activate nuclear factor erythroid 2-related factor 2 (Nrf2) as a transcription factor with important protective effects against many liver diseases, including NAFLD. Raffinose (Ra), an oligosaccharide extracted from several plants, exhibits diverse biological functions. However, the uncertainty lies in determining whether the activation of Nrf2 by Ra can provide a preventive effect on liver lipotoxicity.

PURPOSE

The aim of this study was to shed light on the molecular pathways by which Ra possesses its protective benefits against NAFLD.

METHODS

Experimental protocols were established using WT and Nrf2-null (Nrf2-/-) mice. Liver samples from each group were collected for Western blot, RT-qPCR, H & E, Sirius red and Oil red O staining. Additionally, serums were processed for ELISA. ALM12 cells were gathered for Western blot and immunofluorescence. Moreover, to elucidate the molecular mechanism of Ra, molecular docking was performed.

RESULTS

Our results indicated that Ra remarkably alleviated liver lipotoxic in vivo and in vitro. Ra treatment effectively corrected hepatic steatosis, the release of AST, ALT, TG, and TC, as well as the depletion of HDL and LDL. Meanwhile, Ra efficiently prevented inflammation by inhibiting the TLR4-MyD88-NF-κB pathway and pyroptosis. Additionally, these findings implied that Ra reduced the production of fibrosis-related proteins, which enhanced collagen deposition. Molecular docking revealed that Ra possessed the ability to bind specific regions of Nrf2, resulting in the enhancement of Nrf2 activation and nuclear translocation. Ra treatment restored serum redox factors and antioxidant enzymes to normal levels; however, these alterations were clearly reversed in Nrf2-/- mice.

CONCLUSION

This study reveals novel information on Ra's protective benefits against liver injury caused by abnormal lipid metabolism; these effects are mostly mediated by Nrf2 activation, suggesting a potential new medicine or treatment strategy for NAFLD.

Identification of autophagy-related signatures in nonalcoholic fatty liver disease and correlation with non-parenchymal cells of the liver

Non-alcoholic fatty liver disease (NAFLD) is a chronic hepatic disease. The incidence and prevalence of NAFLD have increased greatly in recent years, and there is still a lack of effective drugs. Autophagy plays an important role in promoting liver metabolism and maintaining liver homeostasis, and defects in autophagy levels are considered to be related to the development of NAFLD. However, the molecular mechanisms of autophagy in NAFLD still remain unknown. In this study, we identified 6 autophagy-associated hub genes using gene expression profiles obtained from the GSE48452 and GSE89632 datasets. Biomarkers were screened according to gene significance (GS) and module membership (MM) using weighted gene co-expression network analysis (WGCNA), and the immune infiltration landscape of the liver in NAFLD patients was explored using the CIBERSORT algorithm. Subsequently, we analyzed the relationship between liver non-parenchymal cells and autophagy-related hub genes using scRNA-seq data (GSE129516). Finally, we separated the NAFLD patients into two groups based on 6 hub genes by consensus clustering and screened 10 potential autophagy-related small molecules based on the cMAP database.

Androsin alleviates non-alcoholic fatty liver disease by activating autophagy and attenuating de novo lipogenesis

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) is a chronic liver disease with therapeutic options on the horizon. Picrorhiza kurroa, enriched with iridoid glycosides like picroside I and picroside II is known for its hepatoprotective activity and anti-inflammatory properties. Androsin, the other phytochemical present in P. kurroa has been shown to have anti-inflammatory and anti-asthmatic properties. However, its role in NAFLD is yet to be investigated.

PURPOSE

This study aims to identify the potent hepatoprotective agent from P. kurroa that can attenuate NAFLD in HFrD-fed ApoE-/- mice, and elucidate the underlying mechanisms governing its effects.

METHODS

Classical purification methods were used to isolate seven compounds, including picroside I, picroside II and androsin from the roots of P. kurroa. NAFLD-induced ApoE-/- mice were administered orally with either picroside I, picroside II, or androsin for 7 weeks. Animals were scanned non-invasively by ultrasonography at 1st and 14th week. Gross histomorphometry was examined by HE and Sirius red staining. mRNA transcript and protein profile associated with autophagy, lipogenesis, inflammation, and fibrosis was done through RT-PCR and Western blot analysis.

RESULTS

In-vitro and in-vivo studies revealed that among the seven evaluated compounds, androsin shows the most potent in-vitro activity. Oral dosing of androsin (10 mg/kg) protected the liver against HFrD-induced NAFLD in ApoE-/- mice model. Biochemical analysis revealed a reduction in ALT and AST enzymes and a significant reduction in cholesterol levels. Hepatocyte ballooning, hepatic lipid deposition, inflammation, and fibrosis were reduced. Androsin treatment significantly reduced fibrosis (α-SMA, collagens, TGF-β) and inflammation (ILs, TNF-α, NFκB) in ApoE-/- mice. Mechanistically, androsin activated AMPKα and down-regulated the expression of SREBP-1c, resulting in ameliorating hepatic lipogenesis.

CONCLUSION

Our results support autophagy as one of the therapeutic strategies to reduce steatosis and hepatic damage. We found that androsin treatment significantly ameliorated hepatic steatosis, serum lipid levels, and hepatic injury in ApoE-/- induced by HFrD. Androsin administration mitigated lipogenesis by inhibiting SREBP1c/FASN pathway and activating autophagy through AMPKα/PI3K/Beclin1/LC3 pathway.

Hepatoprotective effect of dietary pterostilbene against high-fat-diet-induced lipid accumulation exacerbated by chronic jet lag via SIRT1 and SIRT3 activation

Hepatic lipid metabolism is modulated by the circadian rhythm; therefore, circadian disruption may promote obesity and hepatic lipid accumulation. This study aims to investigate dietary pterostilbene (PSB) 's protective effect against high-fat-diet (HFD)-induced lipid accumulation exacerbated by chronic jet lag and the potential role of gut microbiota therein. Mice were treated with a HFD and chronic jet lag for 14 weeks. The experimental group was supplemented with 0.25% (w/w) PSB in its diet to evaluate whether PSB had a beneficial effect. Our study found that chronic jet lag exacerbates HFD-induced obesity and hepatic lipid accumulation, but these adverse effects were significantly mitigated by PSB supplementation. Specifically, PSB promoted hepatic lipolysis and β-oxidation by upregulating SIRT1 expression, which indirectly reduced oxidative stress caused by lipid accumulation. Additionally, the PSB-induced elevation of SIRT1 and SIRT3 expression helped prevent excessive autophagy and mitochondrial fission by activating Nrf2-mediated antioxidant enzymes. The result was evidenced by the use of SIRT1 and SIRT3 inhibitors in in vitro studies, which demonstrated that activation of SIRT1 and SIRT3 by PSB is crucial for the translocation of PGC-1α and Nrf2, respectively. Moreover, the analysis of gut microbiota suggested that PSB's beneficial effects were partly due to its positive modulation of gut microbial composition and functionality. The findings of this study suggest the potential of dietary PSB as a candidate to improve hepatic lipid metabolism via several mechanisms. It may be developed as a treatment adjuvant in the future.

SIRT1: Harnessing multiple pathways to hinder NAFLD

Non-alcoholic fatty liver disease (NAFLD) encompasses hepatic steatosis, non-alcoholic steatohepatitis (NASH), fibrosis, cirrhosis, and hepatocellular carcinoma. It is the primary cause of chronic liver disorders, with a high prevalence but no approved treatment. Therefore, it is indispensable to find a trustworthy therapy for NAFLD. Recently, mounting evidence illustrates that Sirtuin 1 (SIRT1) is strongly associated with NAFLD. SIRT1 activation or overexpression attenuate NAFLD, while SIRT1 deficiency aggravates NAFLD. Besides, an array of therapeutic agents, including natural compounds, synthetic compounds, traditional Chinese medicine formula, and stem cell transplantation, alleviates NALFD via SIRT1 activation or upregulation. Mechanically, SIRT1 alleviates NAFLD by reestablishing autophagy, enhancing mitochondrial function, suppressing oxidative stress, and coordinating lipid metabolism, as well as reducing hepatocyte apoptosis and inflammation. In this review, we introduced the structure and function of SIRT1 briefly, and summarized the effect of SIRT1 on NAFLD and its mechanism, along with the application of SIRT1 agonists in treating NAFLD.

Pterostilbene Protects against Osteoarthritis through NLRP3 Inflammasome Inactivation and Improves Gut Microbiota as Evidenced by In Vivo and In Vitro Studies

Osteoarthritis (OA) is a persistent inflammatory disease, and long-term clinical treatment often leads to side effects. In this study, we evaluated pterostilbene (PT), a natural anti-inflammatory substance, for its protective effects and safety during prolonged use on OA. Results showed that PT alleviated the loss of chondrocytes and widened the narrow joint space in an octacalcium phosphate (OCP)-induced OA mouse model (n = 3). In vitro experiments demonstrate that PT reduced NLRP3 inflammation activation (relative protein expression: C: 1 ± 0.09, lipopolysaccharide (LPS): 1.14 ± 0.07, PT: 0.91 ± 0.07, LPS + PT: 0.68 ± 0.04) and the release of inflammatory cytokines through NF-κB signaling inactivation (relative protein expression: C: 1 ± 0.03, LPS: 3.49 ± 0.02, PT: 0.66 ± 0.08, LPS + PT: 2.78 ± 0.05), ultimately preventing cartilage catabolism. Interestingly, PT also altered gut microbiota by reducing inflammation-associated flora and increasing the abundance of healthy bacteria in OA groups. Collectively, these results suggest that the PT can be considered as a protective strategy for OA.

Targeting autophagy drug discovery: Targets, indications and development trends

Autophagy plays a vital role in sustaining cellular homeostasis and its alterations have been implicated in the etiology of many diseases. Drugs development targeting autophagy began decades ago and hundreds of agents were developed, some of which are licensed for the clinical usage. However, no existing intervention specifically aimed at modulating autophagy is available. The obstacles that prevent drug developments come from the complexity of the actual impact of autophagy regulators in disease scenarios. With the development and application of new technologies, several promising categories of compounds for autophagy-based therapy have emerged in recent years. In this paper, the autophagy-targeted drugs based on their targets at various hierarchical sites of the autophagic signaling network, e.g., the upstream and downstream of the autophagosome and the autophagic components with enzyme activities are reviewed and analyzed respectively, with special attention paid to those at preclinical or clinical trials. The drugs tailored to specific autophagy alone and combination with drugs/adjuvant therapies widely used in clinical for various diseases treatments are also emphasized. The emerging drug design and development targeting selective autophagy receptors (SARs) and their related proteins, which would be expected to arrest or reverse the progression of disease in various cancers, inflammation, neurodegeneration, and metabolic disorders, are critically reviewed. And the challenges and perspective in clinically developing autophagy-targeted drugs and possible combinations with other medicine are considered in the review.

Effects of intermittent cold stimulation on growth performance, meat quality, antioxidant capacity and liver lipid metabolism in broiler chickens

Intermittent cold stimulation (ICS) enhances broilers' resistance to cold stress. Nonetheless, further research is needed to investigate the underlying mechanisms that enhance cold stress resistance. A total of 160 one-day-old male Ross 308 broilers were randomly divided into 2 groups (CC and CS5), with the CC group managing temperature according to the standard for broiler growth stages, while the CS5 group were subjected to cold stimulation at a temperature 3℃ lower than the CC group for 5 h, every 2 d from 15 to 35 d. Sampling was conducted at 36 d (36D), 50 d (50D) and after acute cold stress for 24 h (Y24). First, we examined the effects of ICS on broiler growth performance, meat quality, antioxidant capacity, and lipid metabolism. The results demonstrated that ICS enhanced the performance of broilers to a certain degree. Specifically, the average weight gain in the CS5 group was significantly higher than that of the CC group, and the feed conversion ratio significantly decreased compared to CC at 4 W and 6 W (P ≤ 0.05). Compared with the CC group, cold stimulation significantly reduced drip loss, shearing force, and yellowness (a* value) of chicken meat, while significantly increased redness (b* value) (P ≤ 0.05). At Y24, the levels of T-AOC and GSH-PX in the serum of the CS5 group were significantly higher than those of the CC group, while the level of MDA was significantly lower (P ≤ 0.05). The content of TG, FFA, and VLDL in the serum of the CS5 group was significantly elevated, whereas the level of TC and HDL was significantly lower (P ≤ 0.05). In addition, we further explored whether AMPK-mTOR pathway is involved in the regulation of changes in lipid metabolism and the possible regulatory mechanisms downstream of the signaling pathway. The results showed that ICS significantly upregulated the expression levels of AMPK mRNA and protein in the liver of the CS5 group at 36D and Y24, while significantly down-regulating mTOR (P ≤ 0.05). Compared with the CC group, ICS significantly down-regulated the mRNA expression levels of lipid synthesis and endoplasmic reticulum stress-related genes (SREBP1c, FAS, SCD, ACC, GRP78 and PERK) at 36D and Y24, while significantly up-regulating the mRNA expression levels of lipid decomposition and autophagy-related genes (PPAR and LC3) (P ≤ 0.05). In addition, at Y24, the protein expression levels of endoplasmic reticulum stress-related genes (GRP78) in the CS5 group were significantly lower, while autophagy-related genes (LC3 and ATG7) were significantly higher (P ≤ 0.05). ICS can affect meat quality and lipid metabolism in broilers, and when broilers are subjected to acute cold stress, broilers trained with cold stimulation have stronger lipid metabolism capacity.

Pterostilbene targets the molecular oscillator RORγ to restore circadian rhythm oscillation and protect against sleep restriction induced metabolic disorders

BACKGROUND

Considerable researches have directed toward metabolic disorders caused by sleep restriction (SR). SR-induced disruption of circadian metabolic rhythmicity is identified as an important pathophysiological mechanism. The flavonoid pterostilbene (PTE) is abundant in the traditional Chinese medicine dragon's blood with protective efficacy against obesity-related metabolic dysfunctions. Our previous study found that PTE ameliorates exercise intolerance and clock gene oscillation in the skeletal muscles subjected to SR.

PURPOSE

This study aimed to explore whether PTE improves SR-induced metabolic disorders and delineate the relationship between PTE and the circadian clock.

STUDY DESIGN AND METHODS

Two hundred male C57/B6J mice were kept awake for 20 h/d over five consecutive days and concurrently gavaged with 50, 100, or 200 mg/kg·bw/d PTE. Food consumption and body weight were monitored, and the metabolic status of the mice was evaluated by performing OGTT and ITT, measuring the serum lipid profiles and liver histopathology in response to SR. Daily behavior was analyzed by Clocklab™. The circadian rhythms of the liver clock genes and metabolic output genes were evaluated by cosine analysis. Binding between PTE and RORα/γ or NR1D1/2 was investigated by molecular docking. A luciferase reporter assay was used to determine the impact of PTE on Bmal1 transcription in SR-exposed mice co-transfected with Ad-BMAL1-LUC plus Ad-RORγ-mCherry or Ad-NR1D1-EGFP.

RESULTS

PTE significantly ameliorated abnormal glucose and lipid metabolism (p < 0.05) in SR-exposed mice. PTE improved circadian behavior (p < 0.05) and rescued the circadian rhythm oscillation of the liver clock (p < 0.05) and metabolic output genes (p < 0.05) under SR condition. Molecular docking disclosed that PTE might interact with RORs, and PTE was found to increase Bmal1 promoter luciferase activity with RORE elements in the presence of Ad-RORγ-mCherry (p < 0.05).

CONCLUSIONS

PTE may protect against SR-induced metabolic disorders by directly modulating RORγ to maintain circadian metabolic rhythm. The findings provide valuable insights into the potential use of PTE in the treatment of metabolic disorders associated with disruptions in the circadian rhythm.

Integrated Pharmaco-Bioinformatics Approaches and Experimental Verification To Explore the Effect of Britanin on Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD) is a prevalent global liver disorder, posing substantial health risks. Britanin, a bioactive sesquiterpene lactone extracted from Inula japonica, has demonstrated antidiabetic, hypolipidemic, and hepatoprotective attributes. Nonetheless, the precise impact of Britanin on NAFLD and the intricate biological mechanisms underpinning this interaction remain unexplored. We integrated computer-aided methods to unearth shared biological targets and signaling pathways associated with both Britanin and NAFLD. A network was constructed by compiling putative targets associated with Britanin and NAFLD, followed by a stringent screening of key targets and mechanisms through protein-protein interaction analysis along with GO and KEGG pathway enrichment analyses. Molecular docking was integrated as an evaluation tool, culminating in the identification of HO-1 as the pivotal therapeutic target, showcasing a satisfactory binding affinity. The primary mechanism was ascribed to biological processes and pathways linked to oxidative stress, as evidenced by the outcomes of enrichment analyses. Of these, the AMPK/SREBP1c pathway assumed centrality in this mechanism. Furthermore, in vivo experiments substantiated that Britanin effectively curtailed NAFLD development by ameliorating liver injury, modulating hyperlipidemia and hepatic lipid accumulation, and alleviating oxidative stress and apoptosis. In summary, this study demonstrates the potential of Britanin as a promising therapeutic drug against NAFLD.

Liraglutide improves sevoflurane-induced postoperative cognitive dysfunction via activating autophagy and inhibiting apoptosis

BACKGROUND

Postoperative cognitive dysfunction (POCD) is a common postoperative complication in elderly patients. Liraglutide (LRG) has high homology (97%) with natural glucagon like peptide-1, and it has been proved to be effective in some nervous system diseases. Whether LRG could regulate POCD has not been reported.

METHODS

Sevoflurane (Sev) was used to simulate postoperative cognitive dysfunction (POCD) model. Morris water maze test was performed to evaluate the memory ability and neurological function of rats. Escape latency, swim distance, crossing platform times, average velocity, and targeting quadrant time were analyzed. The cell apoptosis, mRNA and protein expression were measured through flow cytometry, PCR, and western blotting, respectively.

RESULTS

LRG significantly improved the memory ability and neurological function of Sev-treated rats, but 3-MA reversed the effects of LRG. LRG remarkably inhibited apoptosis but up-regulated autophagy related proteins both in vivo and in vitro levels. However, knocking down AMPK could markedly reverse the influence of LRG on apoptosis, autophagy, and cell apoptosis.

CONCLUSIONS

LRG induced autophagy activation can maintain cell homeostasis and promote cell survival by blocking the apoptotic pathway. LRG could improve Sev-induced POCD via activating autophagy, inhibiting apoptosis, and regulating AMPK/mTOR signaling pathway. This study provides a novel therapeutic strategy for the prevention and treatment of POCD.

Pterostilbene alleviates abdominal aortic aneurysm via inhibiting macrophage pyroptosis by activating the miR-146a-5p/TRAF6 axis

Pterostilbene (PTE), a natural stilbene found in blueberries and several varieties of grapes, has several pharmacological activities, including anti-inflammatory and antioxidative activities. However, its role in abdominal aortic aneurysm (AAA), which is a severe inflammatory vascular disease, remains incompletely understood. In this study, we investigated the protective effects of natural stilbene PTE on AAA formation and the underlying mechanism. Two AAA mouse models (Ang II-induced model and PPE-induced model) were used to examine the effect of PTE on AAA formation. We showed that PTE administration attenuated AAA formation in mice. Furthermore, we found that PTE significantly inhibited inflammatory responses in mouse aortas, as PTE suppressed macrophage pyroptosis and prevented macrophage infiltration in aortas, resulting in reduced expression of pro-inflammatory cytokines in aortas. We also observed similar results in LPS + ATP-treated Raw 264.7 cells (a macrophage cell line) and primary peritoneal macrophages in vitro. We showed that pretreatment with PTE restrained inflammatory responses in macrophages by inhibiting macrophage pyroptosis. Mechanistically, miR-146a-5p and TRAF6 interventions in vivo and in vitro were used to investigate the role of the miR-146a-5p/TRAF6 axis in the beneficial effect of PTE on macrophage pyroptosis and AAA. We found that PTE inhibited macrophage pyroptosis by miR-146a-5p-mediated suppression of downstream TRAF6 expression. Moreover, miR-146a-5p knockout or TRAF6 overexpression abrogated the protective effect of PTE on macrophage pyroptosis and AAA formation. These findings suggest that miR-146a-5p/TRAF6 axis activation by PTE protects against macrophage pyroptosis and AAA formation. PTE might be a promising agent for preventing inflammatory vascular diseases, including AAA.

Cell-type specific role of autophagy in the liver and its implications in non-alcoholic fatty liver disease

Autophagy, a cellular degradative process, has emerged as a key regulator of cellular energy production and stress mitigation. Dysregulated autophagy is a common phenomenon observed in several human diseases, and its restoration offers curative advantage. Non-alcoholic fatty liver disease (NAFLD), more recently renamed metabolic dysfunction-associated steatotic liver disease, is a major metabolic liver disease affecting almost 30% of the world population. Unfortunately, NAFLD has no pharmacological therapies available to date. Autophagy regulates several hepatic processes including lipid metabolism, inflammation, cellular integrity and cellular plasticity in both parenchymal (hepatocytes) and non-parenchymal cells (Kupffer cells, hepatic stellate cells and sinusoidal endothelial cells) with a profound impact on NAFLD progression. Understanding cell type-specific autophagy in the liver is essential in order to develop targeted treatments for liver diseases such as NAFLD. Modulating autophagy in specific cell types can have varying effects on liver function and pathology, making it a promising area of research for liver-related disorders. This review aims to summarize our present understanding of cell-type specific effects of autophagy and their implications in developing autophagy centric therapies for NAFLD.

Shikonin promotes hypertrophic scar repair by autophagy of hypertrophic scar-derived fibroblasts

PURPOSE

To investigate the Shikonin (SHI) induce autophagy of hypertrophic scar-derived fibroblasts (HSFs) and the mechanism of which in repairing hypertrophic scar.

METHODS

This study showed that SHI induced autophagy from HSFs and repaired skin scars through the AMPK/mTOR pathway. Alamar Blue and Sirius red were used to identify cell activity and collagen. Electron microscopy, label-free quantitative proteomic analysis, fluorescence and other methods were used to identify autophagy. The differences in the expression of autophagy and AMPK/mTOR pathway-related proteins after SHI treatment were quantitatively analyzed by Western blots. A quantitative real-time polymerase chain reaction assay was used to detect the expression of LC3, AMPK and ULK after adding chloroquine (CQ) autophagy inhibitor.

RESULTS

After treatment with SHI for 24 hours, it was found that the viability of HSFs was significantly reduced, the protein expression of LC3-II/LC3-I and Beclin1 increased, while the protein expression of P62 decreased. The expression of phosphorylated AMPK increased and expression of phosphorylated mTOR decreased. After the use of CQ, the cell autophagy caused by SHI was blocked. The key genes LC3 and P62 were then reexamined by immunohistochemistry using a porcine full-thickness burn hypertrophic scar model, and the results verified that SHI could induce autophagy in vivo.

CONCLUSIONS

These findings suggested that SHI promoted autophagy of HSFs cells, and the potential mechanism may be related to the AMPK/mTOR signal pathway, which provided new insights for the treatment of hypertrophic scars.

Natural products in non-alcoholic fatty liver disease (NAFLD): Novel lead discovery for drug development

With changing lifestyles, non-alcoholic fatty liver disease (NAFLD) has become the most prevalent liver disease worldwide. A substantial increase in the incidence, mortality, and associated burden of NAFLD-related advanced liver disease is expected. Currently, the initial diagnosis of NAFLD is still based on ultrasound and there is no approved treatment method. Lipid-lowering drugs, vitamin supplementation, and lifestyle improvement treatments are commonly used in clinical practice. However, most lipid-lowering drugs can produce poor patient compliance and specific adverse effects. Therefore, the exploration of bio-diagnostic markers and active lead compounds for the development of innovative drugs is urgently needed. More and more studies have reported the anti-NAFLD effects and mechanisms of natural products (NPs), which have become an important source for new drug development to treat NAFLD due to their high activity and low side effects. At present, berberine and silymarin have been approved by the US FDA to enter clinical phase IV studies, demonstrating the potential of NPs against NAFLD. Studies have found that the regulation of lipid metabolism, insulin resistance, oxidative stress, and inflammation-related pathways may play important roles in the process. With the continuous updating of technical means and scientific theories, in-depth research on the targets and mechanisms of NPs against NAFLD can provide new possibilities to find bio-diagnostic markers and innovative drugs. As we know, FXR agonists, PPARα agonists, and dual CCR2/5 inhibitors are gradually coming on stage for the treatment of NAFLD. Whether NPs can exert anti-NAFLD effects by regulating these targets or some unknown targets remains to be further studied. Therefore, the study reviewed the potential anti-NAFLD NPs and their targets. Some works on the discovery of new targets and the docking of active lead compounds were also discussed. It is hoped that this review can provide some reference values for the development of non-invasive diagnostic markers and new drugs against NAFLD in the clinic.

Tetrahydropalmatine ameliorates hepatic steatosis in nonalcoholic fatty liver disease by switching lipid metabolism via AMPK-SREBP-1c-Sirt1 signaling axis

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) is becoming a global epidemic without effective treatment currently available. NAFLD is characterized by an increase in hepatic de novo lipogenesis (DNL) and inadequate compensatory enhancement in fatty acid oxidation (FAO), which disturbs lipid homeostasis. In NAFLD, lipid metabolism relies heavily on metabolic reprogramming. Moreover, lipid metabolism plays an essential role in switching between lipogenesis and FAO, which is beneficial for the anti-NAFLD therapy. Our recent study demonstrated that the phytochemical tetrahydropalmatine (THP) has positive efficacy in hepatocellular carcinoma (HCC). However, it remains unclear whether the therapeutic benefits of THP are primarily due to delaying the progression of hepatic steatosis to HCC.

PURPOSE

This work aimed to systemically evaluate the pharmacological functions and underlying mechanisms of THP in NAFLD using both in vitro and in vivo models.

METHODS

NAFLD models were established using high-fat diet (HFD)-fed mice in vivo and palmitic acid- and oleic acid-challenged hepatocytes in vitro. Metabonomics analysis concomitant with biochemical indices and computational biology assays were performed comprehensively to reveal the key link between the treatment of NAFLD and the AMPK-SREBP-1c-Sirt1 signaling axis.

RESULTS

Hepatic metabolomics analysis revealed that THP altered lipid metabolism by enhancing FAO and inhibiting glycolysis, tricarboxylic acid cycle, and urea cycle in HFD-fed mice. Analysis of gene expression showed that THP profoundly suppressed hepatic DNL and promoted FAO. THP supplementation not only significantly decreased body/liver weight gain and serum indices but also ameliorated hepatic steatosis. Simultaneously, impaired lipotoxicity was observed in vivo and in vitro after THP supplementation, protecting against steatosis-driven injury. Metabolic phenotype assays showed that THP promoted switching from glycolysis inhibition to FAO enhancement in steatotic cells, resulting in reprogramming lipid metabolism. Mechanistically, THP accelerated lipid oxidation by activating AMPK-SREBP-1c-Sirt1 axis signaling. Applying molecular docking combined with surface plasmon resonance and cellular thermal shift assay target engagement, as well as siRNA assays, AMPKα was confirmed as a direct molecular target of THP.

CONCLUSION

In summary, THP ameliorates hepatic steatosis in NAFLD by switching lipid metabolism via the AMPK-SREBP-1c-Sirt1 pathway. This work provides an attractive phytochemical component for therapy against hepatic steatosis in NAFLD.

Recent Insights into the Biomarkers, Molecular Targets and Mechanisms of Non-Alcoholic Steatohepatitis-Driven Hepatocarcinogenesis

Non-alcoholic fatty liver disease (NAFLD) or metabolic dysfunction-associated steatotic liver disease (MASLD) and steatohepatitis (NASH) are chronic hepatic conditions leading to hepatocellular carcinoma (HCC) development. According to the recent "multiple-parallel-hits hypothesis", NASH could be caused by abnormal metabolism, accumulation of lipids, mitochondrial dysfunction, and oxidative and endoplasmic reticulum stresses and is found in obese and non-obese patients. Recent translational research studies have discovered new proteins and signaling pathways that are involved not only in the development of NAFLD but also in its progression to NASH, cirrhosis, and HCC. Nevertheless, the mechanisms of HCC developing from precancerous lesions have not yet been fully elucidated. Now, it is of particular importance to start research focusing on the discovery of novel molecular pathways that mediate alterations in glucose and lipid metabolism, which leads to the development of liver steatosis. The role of mTOR signaling in NASH progression to HCC has recently attracted attention. The goals of this review are (1) to highlight recent research on novel genetic and protein contributions to NAFLD/NASH; (2) to investigate how recent scientific findings might outline the process that causes NASH-associated HCC; and (3) to explore the reliable biomarkers/targets of NAFLD/NASH-associated hepatocarcinogenesis.

Plantamajoside modulates immune dysregulation and hepatic lipid metabolism in rats with nonalcoholic fatty liver disease via AMPK/Nrf2 elevation

Nonalcoholic fatty liver disease (NAFLD) is a hepatic metabolic syndrome with a rapidly increasing prevalence globally. Plantamajoside (PMS), a phenylethanoid glycoside component extracted from Plantago asiatica, has various biological properties. However, its effect on NAFLD remains unknown. The study aimed to explore the effect and mechanism of PMS on NAFLD in the high-fat diet (HFD)-feeding rats. PMS induced a decrease in body and liver weight, and the amelioration in the blood lipid parameters and pathological symptoms in HFD-feeding rats. The increase in the serum concentrations and the relative protein expressions of proinflammatory factors was decreased by the PMS treatment in HFD-induced NAFLD rats. Additionally, PMS reduced the excessive lipid vacuoles, and modified the relative expressions of proteins involved in the fatty acid synthesis and uptake in HFD-feeding rats. Mechanically, the downregulation of AMPK/Nrf2 pathway in HFD-feeding rats was restored by the PMS treatment. Inhibition of AMPK pathway reversed the PMS-induced the increase in the level of inflammatory factors, pathological symptoms, excessive lipid vacuoles, and the relative expression of proteins involved in the fatty acid synthesis and uptake. Collectively, PMS ameliorated immune dysregulation and abnormal hepatic lipid metabolism by activating AMPK/Nrf2 pathway in rats with NAFLD.

The essential effect of mTORC1-dependent lipophagy in non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) is a chronic progressive liver disease with increasing prevalence. Lipophagy is a type of programmed cell death that plays an essential role in maintaining the body's balance of fatty acid metabolism. However, the livers of NAFLD patients are abnormally dysregulated in lipophagy. mTORC1 is a critical negative regulator of lipophagy, which has been confirmed to participate in the process of lipophagy through various complex mechanisms. Therefore, targeting mTORC1 to restore failed autophagy may be an effective therapeutic strategy for NAFLD. This article reviews the main pathways through which mTORC1 participates in the formation of lipophagy and the intervention effect of mTORC1-regulated lipophagy in NAFLD, providing new therapeutic strategies for the prevention and treatment of NAFLD in the future.