Lipotoxic Hepatocyte-Derived Exosomal MicroRNA 192-5p Activates Macrophages Through Rictor/Akt/Forkhead Box Transcription Factor O1 Signaling in Nonalcoholic Fatty Liver Disease

Role and therapeutic perspectives of extracellular vesicles derived from liver and adipose tissue in metabolic dysfunction-associated steatotic liver disease

The global epidemic of metabolic diseases has led to the emergence of metabolic dysfunction-associated steatotic liver disease (MASLD) and metabolic dysfunction-associated steatohepatitis (MASH), which pose a significant threat to human health. Despite recent advances in research on the pathogenesis and treatment of MASLD/MASH, there is still a lack of more effective and targeted therapies. Extracellular vesicles (EVs) discovered in a wide range of tissues and body fluids encapsulate different activated biomolecules and mediate intercellular communication. Recent studies have shown that EVs derived from the liver and adipose tissue (AT) play vital roles in MASLD/MASH pathogenesis and therapeutics, depending on their sources and intervention types. Besides, adipose-derived stem cell (ADSC)-derived EVs appear to be more effective in mitigating MASLD/MASH. This review presents an overview of the definition, extraction strategies, and characterisation of EVs, with a particular focus on the biogenesis and release of exosomes. It also reviews the effects and potential molecular mechanisms of liver- and AT-derived EVs on MASLD/MASH, and emphasises the contribution and clinical therapeutic potential of ADSC-derived EVs. Furthermore, the future perspective of EV therapy in a clinical setting is discussed.

Exosomal Tenascin-C primes macrophage pyroptosis amplifying aberrant inflammation during sepsis-induced acute lung injury

Sepsis-induced acute lung injury (ALI) is a serious complication of sepsis and the predominant cause of death. Exosomes released by lung tissue cells critically influence the progression of ALI during sepsis by modulating the inflammatory microenvironment. However, the molecular mechanisms by which exosome-mediated intercellular signaling exacerbates ALI in septic infection remain undefined. Our study found increased levels of exosomal Tenascin-C (TNC) in the plasma of both patients and mice with ALI, showing a strong association with disease progression. By integrating exosomal proteomics with transcriptome sequencing and experimental validation, we elucidated that LPS induce unresolved endoplasmic reticulum stress (ERs) in alveolar epithelial cells (AECs), ultimately leading to the release of exosomal TNC through the activation of PERK-eIF2α and the transcription factor CHOP. In the sepsis mouse model with TNC knockout, we noted a marked reduction in macrophage pyroptosis. Our detailed investigations found that exosomal TNC binds to TLR4 on macrophages, resulting in an augmented production of ROS, subsequent mitochondrial damage, activation of the NF-κB signaling pathway, and induction of DNA damage response. These interconnected events culminate in macrophage pyroptosis, thereby amplifying the release of inflammatory cytokines. Our findings demonstrate that exosomal Tenascin-C, released from AECs under unresolved ER stress, exacerbates acute lung injury by intensifying sepsis-associated inflammatory responses. This research provides new insights into the complex cellular interactions underlying sepsis-induced ALI.

Macrophages and tertiary lymphoid structures as indicators of prognosis and therapeutic response in cancer patients

Tertiary lymphoid structures (TLS) can reflect cancer prognosis and clinical outcomes in various tumour tissues. Tumour-associated macrophages (TAMs) are indispensable components of the tumour microenvironment and play crucial roles in tumour development and immunotherapy. TAMs are associated with TLS induction via the modulation of the T cell response, which is a major component of the TLS. Despite their important roles in cancer immunology, the subtypes of TAMs that influence TLS and their correlation with prognosis are not completely understood. Here, we provide novel insights into the role of TAMs in regulating TLS formation. Furthermore, we discuss the prognostic value of these TAM subtypes and TLS, as well as the current antitumour therapies for inducing TLS. This study highlights an entirely new field of TLS regulation that may lead to the development of an innovative perspective on immunotherapy for cancer treatment.

Targeting the MCP-GPX4/HMGB1 Axis for Effectively Triggering Immunogenic Ferroptosis in Pancreatic Ductal Adenocarcinoma

Induction of ferroptosis can inhibit cancer cells in vitro, however, the role of ferroptosis in treatment in vivo is controversial. The immunosuppressive cells activated by the ferroptotic tumor cells can promote the growth of residual tumor cells, hindering the application of ferroptosis stimulation in tumor treatment. In this study, a new strategy is aimed to be identified for effectively triggering immunogenic ferroptosis in pancreatic ductal adenocarcinoma (PDAC) and simultaneously stimulating antitumor immune responses. Toward this, several molecular and biochemical experiments are performed using patient-derived organoid models and a KPC mouse model (LSL-KrasG12D /+, LSL-Trp53R172H/+, Pdx-1-Cre). It is observed that the inhibition of macrophage-capping protein (MCP) suppressed the ubiquitin fold modifier (UFM)ylation of pirin (PIR), a newly identified substrate of UFM1, thereby decreasing the transcription of GPX4, a marker of ferroptosis, and promoting the cytoplasmic transportation of HMGB1, a damage-associated molecular pattern. GPX4 deficiency triggered ferroptosis, and the pre-accumulated cytosolic HMGB1 is released rapidly. This altered release pattern of HMGB1 facilitated the pro-inflammatory M1-like polarization of macrophages. Thus, therapeutic inhibition of MCP yielded dual antitumor effects by stimulating ferroptosis and activating antitumor pro-inflammatory M1-like macrophages. The nanosystem developed for specifically silencing MCP is a promising tool for treating PDAC.

Extracellular Vesicles and Their Correlation with Inflammatory Factors in an Experimental Model of Steatotic Liver Disease Associated with Metabolic Dysfunction

Background/Aims: Extracellular vesicles (EVs) are promising as a biomarker of metabolic dysfunction associated steatotic liver disease (MASLD). The objective is to study EVs and their involvement in MASLD concerning the disease's pathogenesis and progression characteristics. Methods: Male adult Sprague Dawley rats were randomly assigned into two experimental models of MASLD: MASLD-16 and MASLD-28, animals received a choline-deficient high-fat diet (CHFD) and Control-16 and Control-28, animals received a standard diet (SD) for 16 and 28 weeks, respectively. Biological samples from these animal models were used, as well as previously registered variables. EVs from hepatic tissue were characterized using confocal microscopy. EVs were isolated through differential ultracentrifugation from serum and characterized using NanoSight. The data from the EVs were correlated with biochemical, molecular, and histopathological parameters. Results: Liver EVs were identified through the flotillin-1 protein. EVs were isolated from the serum of all groups. There was a decrease of EVs concentration in MASLD-28 in comparison with Control-28 (P < 0.001) and a significant increase in EVs concentration in Control-28 compared with Control-16 (P < 0.001). There was a strong correlation between serum EVs concentration with hepatic gene expression of interleukin (Il)6 (r2 = 0.685, P < 0.05), Il1b (r2 = 0.697, P < 0.05) and tumor necrosis factor-alpha (Tnfa; r2 = 0.636, P < 0.05) in MASLD-16. Moreover, there was a strong correlation between serum EVs size and Il10 in MASLD-28 (r2 = 0.762, P < 0.05). Conclusion: The concentration and size of EVs correlated with inflammatory markers, suggesting their involvement in the systemic circulation, cellular communication, and development and progression of MASLD, demonstrating that EVs have the potential to serve as noninvasive biomarkers for MASLD diagnosis and prognosis.

Exosomes regulate SIRT3-related autophagy by delivering miR-421 to regulate macrophage polarization and participate in OSA-related NAFLD

PURPOSE

To analyze the role of and mechanism underlying obstructive sleep apnea (OSA)-derived exosomes in inducing non-alcoholic fatty liver (NAFLD).

METHODS

The role of OSA-derived exosomes was analyzed in inducing hepatocyte fat accumulation in mice models both in vivo and in vitro.

RESULTS

OSA-derived exosomes caused fat accumulation and macrophage activation in the liver tissue. These exosomes promoted fat accumulation; steatosis was more noticeable in the presence of macrophages. Macrophages could internalize OSA-derived exosomes, which promoted macrophage polarization to the M1 type. Moreover, it inhibited sirtuin-3 (SIRT3)/AMP-activated protein kinase (AMPK) and autophagy and promoted the activation of nucleotide-binding domain, leucine-rich-containing family, pyrin domain-containing-3 (NLRP3) inflammasomes. The use of 3-methyladenine (3-MA) to inhibit autophagy blocked NLRP3 inflammasome activation and inhibited the M1 polarization of macrophages. miR-421 targeting inhibited SIRT3 protein expression in the macrophages. miR-421 was significantly increased in OSA-derived exosomes. Additionally, miR-421 levels were increased in OSA + NAFLD mice- and patient-derived exosomes. In the liver tissues of OSA and OSA + NAFLD mice, miR-421 displayed similar co-localization with the macrophages. Intermittent hypoxia-induced hepatocytes deliver miR-421 to the macrophages via exosomes to inhibit SIRT3, thereby participating in macrophage M1 polarization. After OSA and NAFLD modeling in miR-421-/- mice, liver steatosis and M1 polarization were significantly reduced. Additionally, in the case of miR-421 knockout, the inhibitory effects of OSA-derived exosomes on SIRT3 and autophagy were significantly alleviated. Furthermore, their effects on liver steatosis and macrophage M1 polarization were significantly reduced.

CONCLUSIONS

OSA promotes the delivery of miR-421 from the hepatocytes to macrophages. Additionally, it promotes M1 polarization by regulating the SIRT3/AMPK-autophagy pathway, thereby causing NAFLD.

Metabolic and circadian inputs encode anticipatory biogenesis of hepatic fed microRNAs

Starvation and refeeding are mostly unanticipated in the wild in terms of duration, frequency, and nutritional value of the refed state. Notwithstanding this, organisms mount efficient and reproducible responses to restore metabolic homeostasis. Hence, it is intuitive to invoke expectant molecular mechanisms that build anticipatory responses to enable physiological toggling during fed-fast cycles. In this regard, we report anticipatory biogenesis of oscillatory hepatic microRNAs that peak during a fed state and inhibit starvation-responsive genes. Our results clearly demonstrate that the levels of primary and precursor microRNA transcripts increase during a fasting state, in anticipation of a fed response. We delineate the importance of both metabolic and circadian cues in orchestrating hepatic fed microRNA homeostasis in a physiological setting. Besides illustrating metabo-endocrine control, our findings provide a mechanistic basis for the overarching influence of starvation on anticipatory biogenesis. Importantly, by using pharmacological agents that are widely used in clinics, we point out the high potential of interventions to restore homeostasis of hepatic microRNAs, whose deregulated expression is otherwise well established to cause metabolic diseases.

Ginseng-derived nanoparticles alleviate alcohol-induced liver injury by activating the Nrf2/HO-1 signalling pathway and inhibiting the NF-κB signalling pathway in vitro and in vivo

BACKGROUND

Previous studies have confirmed the antioxidant and anti-inflammatory effects of active ginseng components that protect against liver injury. However, ginseng-derived nanoparticles (GDNPs), low-immunogenicity nanovesicles derived from ginseng, have not been reported to be hepatoprotective.

PURPOSE

In this study, we investigated whether GDNPs could attenuate alcohol-induced liver injury in LO2 cells and mice by modulating oxidative stress and inflammatory pathways, thereby advancing the theoretical basis for the development of novel pharmacological treatments.

STUDY DESIGN

Alcohol was used to construct in vitro and in vivo models of alcoholic liver injury. To explore the mechanisms by which GDNPs exert their protective effects against alcoholic liver injury, we examined the expression of oxidative stress-related genes and analysed inflammatory responses in vitro and in vivo. The experimental findings were verified using network pharmacology.

METHODS

The composition of the GDNPs was analysed using liquid chromatography-mass spectrometry. GDNPs were extracted and purified using differential ultracentrifugation and sucrose density gradient centrifugation. In vitro models of alcoholic liver injury were established using LO2 cells, whereas C57BL/6 J mice were used as in vivo models. Oxidative stress, inflammation, and liver injury indicators were measured using appropriate kits. Levels of proteins associated with oxidative stress and inflammation were measured via western blot, while nuclear factor erythroid2-related factor 2 (Nrf2) and NF-κB protein expression was tested using immunofluorescence, immunohistochemistry, and flow cytometry. The levels of relevant transcription factors were determined using qPCR. Experimental haematoxylin and eosin staining was used to characterise the liver histological appearance and damage in mice. Network pharmacological analysis of GDNP mRNA sequencing of GDNPs was used to predict drug targets and disease associations using TCMSP.

RESULTS

GDNPs primarily included 77 compounds, including organic acids and their derivatives, amino acids and their derivatives, sugars, terpenoids, and flavonoids. GDNPs have features that allow them to be taken up by LO2 cells and promote their proliferation. In vitro data indicated that GDNPs reduced the levels of alcohol-induced reactive oxygen species by activating the Nrf2/HO-1 signalling pathway, whilst inhibiting the NF-κB pathway and thereby reducing NO, tumour necrosis factor-α, and interleukin-1β levels to alleviate inflammation. An in vivo model showed that GDNPs improved the liver parameters and pathology in mice with alcoholic liver injury. GDNPs activate the Nrf2/HO-1/Keap1 signalling pathway in a p62-dependent manner to exert antioxidant effects. Furthermore, the TLR4/NF-κB signalling pathway was involved in the in vivo anti-inflammatory effect. Network pharmacology also confirmed that the effects of GDNPs on liver disease were associated with oxidative stress and inflammation-related targets and pathways.

CONCLUSION

This study showed for the first time that GDNPs can alleviate alcohol-induced liver damage by activating the Nrf2/HO1 signalling pathway and blocking the NF-κB signalling pathway, thus lowering oxidative stress and inflammatory responses. Hereby, we present the Nrf2/HO1 and NF-κB signalling pathways as potential targets and GDNPs as a novel therapeutic approach for the management of alcohol-induced liver damage.

The Role of Extracellular Vesicles in Metabolic Diseases

Extracellular vesicles represent a group of structures with the capacity to communicate with different cells and organs. This complex network of interactions can regulate multiple physiological processes in the organism. Very importantly, these processes can be altered during the appearance of different diseases including cancer, metabolic diseases, etc. In addition, these extracellular vesicles can transport different cargoes, altering the initiation of the disease, driving the progression, or even accelerating the pathogenesis. Then, we have explored the implication of these structures in different alterations such as pancreatic cancer, and in different metabolic alterations such as diabetes and its complications and non-alcoholic fatty liver disease. Finally, we have explored in more detail the communication between the liver and the pancreas. In summary, extracellular vesicles represent a very efficient system for the communication among different tissues and permit an efficient system as biomarkers of the disease, as well as being involved in the extracellular-vesicle-mediated transport of molecules, serving as a potential therapy for different diseases.

Exosomal mediators in sepsis and inflammatory organ injury: unraveling the role of exosomes in intercellular crosstalk and organ dysfunction

Sepsis, a severe systemic inflammatory response to infection, remains a leading cause of morbidity and mortality worldwide. Exosomes, as mediators of intercellular communication, play a pivotal role in the pathogenesis of sepsis through modulating immune responses, metabolic reprogramming, coagulopathy, and organ dysfunction. This review highlights the emerging significance of exosomes in these processes. Initially, it provides an in-depth insight into exosome biogenesis and characterization, laying the groundwork for understanding their diverse and intricate functions. Subsequently, it explores the regulatory roles of exosomes in various immune cells such as neutrophils, macrophages, dendritic cells, T cells, and B cells. This analysis elucidates how exosomes are pivotal in modulating immune responses, thus contributing to the complexity of sepsis pathophysiology. Additionally, this review delves into the role of exosomes in the regulation of metabolism and subsequent organ dysfunction in sepsis. It also establishes a connection between exosomes and the coagulation cascade, which affects endothelial integrity and promotes thrombogenesis in sepsis. Moreover, the review discusses the dual role of exosomes in the progression and resolution of sepsis, exploring their complex involvement in inflammation and healing processes. Furthermore, it underscores their potential as biomarkers and therapeutic targets. Understanding these mechanisms presents new opportunities for novel interventions to mitigate the severe outcomes of sepsis, emphasizing the therapeutic promise of exosome research in critical care settings.

RNAkines are secreted messengers shaping health and disease

Extracellular noncoding RNAs (ncRNAs) have crucial roles in intercellular communications. The process of ncRNA secretion is highly regulated, with specific ncRNA profiles produced under different physiological and pathological circumstances. These ncRNAs are transported primarily via extracellular vesicles (EVs) from their origin cells to target cells, utilising both endocrine and paracrine pathways. The intercellular impacts of extracellular ncRNAs are essential for maintaining homeostasis and the pathogenesis of various diseases. Given the unique aspects of extracellular ncRNAs, here we propose the term 'RNAkine' to describe these recently identified secreted factors. We explore their roles as intercellular modulators, particularly in their ability to regulate metabolism and influence tumorigenesis, highlighting their definition and importance as a distinct class of secreted factors.

Exploring the Potential of Plant-Derived Exosome-like Nanovesicle as Functional Food Components for Human Health: A Review

Plant-derived exosome-like nanovesicles (PELNs) are bilayer membrane-enclosed nanovesicles secreted by plant cells, serving as carriers of various substances such as proteins, RNA, and metabolites. The mounting evidence suggests that PELN plays a crucial role in transmembrane signaling, nutrient transportation, apoptosis, and regulation of gut microbiota composition. This makes it a promising "dark nutrient" for plants to modulate human physiology and pathogenesis. A comprehensive understanding of PELN formation, uptake, and functional mechanisms can offer novel insights into plant nutrition and functional properties, thereby facilitating the precise development of plant-based foods and drugs. This article provides a summary of PELN extraction and characterization, as well as absorption and delivery processes. Furthermore, it focuses on the latest discoveries and underlying physiological mechanisms of PELN's functions while exploring future research directions.

Phosphorylation: new star of pathogenesis and treatment in steatotic liver disease

Steatotic liver disease poses a serious threat to human health and has emerged as one of the most significant burdens of chronic liver disease worldwide. Currently, the research mechanism is not clear, and there is no specific targeted drug for direct treatment. Phosphorylation is widely regarded as the most common type of protein modification, closely linked to steatotic liver disease in previous studies. However, there is no systematic review to clarify the relationship and investigate from the perspective of phosphorylation. Phosphorylation has been found to mainly regulate molecule stability, affect localization, transform molecular function, and cooperate with other protein modifications. Among them, adenosine 5'-monophosphate-activated protein kinase (AMPK), serine/threonine kinase (AKT), and nuclear factor kappa-B (NF-kB) are considered the core mechanisms in steatotic liver disease. As to treatment, lifestyle changes, prescription drugs, and herbal ingredients can alleviate symptoms by influencing phosphorylation. It demonstrates the significant role of phosphorylation as a mechanism occurrence and a therapeutic target in steatotic liver disease, which could be a new star for future exploration.

Sestrin2 maintains hepatic immune homeostasis and redox balance partially via inhibiting RIPK3-mediated necroptosis in metabolic dysfunction-associated steatohepatitis

BACKGROUND & AIMS

Necroptosis, a novel type of programmed cell death, is intricately associated with inflammatory response. Currently, most studies focus on the activation of necroptosis, while the mechanisms underlying the negative regulation of necroptosis remain poorly understood.

METHODS

The effects of sestrin2 (SESN2) overexpression or knockdown on the regulation of necroptosis were assessed in the TNFα/Smac-mimetic/Z-VAD-FMK (T/S/Z)-induced necroptosis model and palmitic acid (PA)-induced lipotoxicity model. Western-blot, co-Immunoprecipitation, Glutathione S-transferase pull-down, and confocal assays were employed to explore the regulatory mechanisms including protein-protein interactions and post-translational modification. Furthermore, we used GSK'872, a specific inhibitor of receptor-interacting serine/threonine-protein kinase (RIPK) 3, to evaluate the relationship between SESN2-related alterations and RIPK3-mediated necroptosis in T/S/Z-induced necroptosis model, PA-induced lipotoxicity model, and high-fat high-cholesterol diet (HFHCD)-induced non-alcoholic steatohepatitis model.

RESULTS

Our findings revealed that SESN2 was upregulated under conditions that induce necroptosis and functioned as a negative regulator of necroptosis. High levels of SESN2 could equipped hepatocytes with the ability to defend against necroptotic inflammation and oxidative stress. Mechanistically, SESN2 interacted with RIPK3 and tuned down necroptosis by inhibiting the phosphorylation of RIPK3, promoting the ubiquitination of RIPK3, and preventing the formation of the RIPK1/RIPK3 necrosome. The depletion of SESN2 resulted in excessive necroptosis, accompanied by increased fat accumulation, inflammation, and oxidative stress in the experimental steatohepatitis model. Blocking necroptosis by GSK'872 reduced the liberation of pro-inflammatory cytokines and reactive oxygen species generation, but not hepatocyte fat deposition, in both PA-treated SESN2 knockout cells and HFHCD-fed SESN2 knockout mice, suggesting that the activation of RIPK3-mediated necroptosis may partially account for the hyperinflammation and excessive oxidative stress induced by SESN2 deficiency.

CONCLUSION

Our results suggested that SESN2 inhibited RIPK3-mediated necroptosis; this regulation is an important for the immune homeostasis and the redox balance in the liver.

New concepts drive the development of delivery tools for sustainable treatment of diabetic complications

Diabetic complications, especially diabetic retinopathy, diabetic nephropathy and painful diabetic neuropathy, account for a large portion of patients with diabetes and display rising global prevalence. They are the leading causes of blindness, kidney failure and hypersensitivity to pain caused by diabetes. Current approved therapeutics against the diabetic complications are few and exhibit limited efficacy. The enhanced cell-specificity, stability, biocompatibility, and loading capacity of drugs are essential for the mitigation of diabetic complications. In the article, we have critically discussed the recent studies over the past two years in material sciences and biochemistry. The insightful concepts in these studies drive the development of novel nanoparticles and mesenchymal stem cells-derived extracellular vesicles to meet the need for treatment of diabetic complications. Their underlying biochemical principles, advantages and limitations have been in-depth analyzed. The nanoparticles discussed in the article include double-headed nanodelivery system, nanozyme, ESC-HCM-B system, soft polymer nanostars, tetrahedral DNA nanostructures and hydrogels. They ameliorate the diabetic complication through attenuation of inflammation, apoptosis and restoration of metabolic homeostasis. Moreover, mesenchymal stem cell-derived extracellular vesicles efficiently deliver therapeutic proteins to the retinal cells to suppress the angiogenesis, inflammation, apoptosis and oxidative stress to reverse diabetic retinopathy. Collectively, we provide a critical discussion on the concept, mechanism and therapeutic applicability of new delivery tools to treat these three devastating diabetic complications.

Epigenetic modifications in obesity-associated diseases

The global prevalence of obesity has reached epidemic levels, significantly elevating the susceptibility to various cardiometabolic conditions and certain types of cancer. In addition to causing metabolic abnormalities such as insulin resistance (IR), elevated blood glucose and lipids, and ectopic fat deposition, obesity can also damage pancreatic islet cells, endothelial cells, and cardiomyocytes through chronic inflammation, and even promote the development of a microenvironment conducive to cancer initiation. Improper dietary habits and lack of physical exercise are important behavioral factors that increase the risk of obesity, which can affect gene expression through epigenetic modifications. Epigenetic alterations can occur in early stage of obesity, some of which are reversible, while others persist over time and lead to obesity-related complications. Therefore, the dynamic adjustability of epigenetic modifications can be leveraged to reverse the development of obesity-associated diseases through behavioral interventions, drugs, and bariatric surgery. This review provides a comprehensive summary of the impact of epigenetic regulation on the initiation and development of obesity-associated cancers, type 2 diabetes, and cardiovascular diseases, establishing a theoretical basis for prevention, diagnosis, and treatment of these conditions.

Communication between nonalcoholic fatty liver disease and atherosclerosis: Focusing on exosomes

Nonalcoholic fatty liver disease (NAFLD) is the most prevalent chronic hepatic disorder on a global scale. Atherosclerosis (AS), a leading cause of cardiovascular diseases, stands as the primary contributor to mortality among patients diagnosed with NAFLD. However, the precise etiology by which NAFLD causes AS remains unclear. Exosomes are nanoscale extracellular vesicles secreted by cells, and are considered to participate in complex biological processes by promoting cell-to-cell and organ-to-organ communications. As vesicles containing protein, mRNA, non-coding RNA and other bioactive molecules, exosomes can participate in the development of NAFLD and AS respectively. Recently, studies have shown that NAFLD can also promote the development of AS via secreting exosomes. Herein, we summarized the recent advantages of exosomes in the pathogenesis of NAFLD and AS, and highlighted the role of exosomes in mediating the information exchange between NAFLD and AS. Further, we discussed how exosomes play a prominent role in enabling information exchange among diverse organs, delving into a novel avenue for investigating the link between diseases and their associated complications. The future directions and emerging challenges are also listed regarding the exosome-based therapeutic strategies for AS under NAFLD conditions.

M2 macrophage exosome-derived lncRNA AK083884 protects mice from CVB3-induced viral myocarditis through regulating PKM2/HIF-1α axis mediated metabolic reprogramming of macrophages

Viral myocarditis (VM) is a clinically common inflammatory disease. Accumulating literature has indicated that M2 macrophages protect mice from Coxsackievirus B3 (CVB3)-induced VM. However, mechanisms that underlie M2 macrophages alleviating myocardial inflammation remain largely undefined. We found that M2 macrophage-derived exosomes (M2-Exo) can effectively attenuate VM. The long non-coding RNA (lncRNA) AK083884 in M2-Exo was found to be involved in the regulation of macrophage polarization by exosome lncRNA sequencing combined with in vitro functional assays. M2-Exo-derived AK083884 promotes macrophage M2 polarization and protects mice from CVB3-induced VM. Furthermore, we identified pyruvate kinase M2 (PKM2) as a protein target binding to AK083884 and found that PKM2 knockdown could promote macrophages to polarize to M2 phenotype. Intriguingly, functional assay revealed that downregulation of AK083884 promotes metabolic reprogramming in macrophages. In addition, co-immunoprecipitation was performed to reveal AK083884 could interact with PKM2 and inhibition of AK083884 can facilitate the binding of PKM2 and HIF-1α. Collectively, our findings uncovered an important role of M2-Exo-derived AK083884 in the regulation of macrophage polarization through metabolic reprogramming, identified a new participant in the development of VM and provided a potential clinically important therapeutic target.

Exosomal miRNA-166-5p derived from G-MDSCs promotes proliferation by targeting ITM3E in colorectal cancer

BACKGROUND

The immune milieu of colorectal cancer is a complex phenomenon. It is imperative to investigate the crucial immune factors that promote the progression of colorectal cancer. Immune suppressor cells are granulocytic myeloid-derived suppressor cells (G-MDSCs). However, they also increased cancer growth in other ways that need to be investigated further.

METHODS

Using flow cytometry, we isolated G-MDSCs from colorectal cancer tissues. Ultracentrifugation was used to separate exosomes from the supernatant of G-MDSCs, and western blotting, transmission electron microscopy (TEM), and flow cytometry were used to confirm their presence. RNA sequencing was used to identify unique miRNAs and transcripts, which were subsequently confirmed by RT-qPCR (real-time quantitative real-time PCR). The CCK-8 test was used to determine the rate of proliferation. Lentiviral vectors were employed to manipulate the expression of miRNAs and genes in order to investigate their role in the development of colorectal cancer.

RESULTS

Colorectal cancer tissues have been found to contain granulocyte-myeloid-derived suppressor cells (G-MDSCs) that secrete exosomes. These exosomes have been shown to accelerate cancer progression by promoting cell proliferation. Further research has identified microRNA-166-5p as a target from G-MDSC-derived exosomes. This downregulation leads to the inhibition of integral membrane protein 2B (ITM3E) transcription, which in turn activates the PI3K/Akt signaling pathway. This pathway promotes cell proliferation and can be inhibited using deguelin. The accelerated development of colorectal cancer has been further confirmed in mice models.

CONCLUSION

The primary results of this work show that exosomes produced from G-MDSCs and the miR-166-5p/ITM3E axis have therapeutic and diagnostic promise in colorectal cancer.

Investigating the Role of Non-Coding RNA in Non-Alcoholic Fatty Liver Disease

Non-coding RNAs (ncRNAs) are RNA molecules that do not code for protein but play key roles in regulating cellular processes. NcRNAs globally affect gene expression in diverse physiological and pathological contexts. Functionally important ncRNAs act in chromatin modifications, in mRNA stabilization and translation, and in regulation of various signaling pathways. Non-alcoholic fatty liver disease (NAFLD) is a set of conditions caused by the accumulation of triacylglycerol in the liver. Studies of ncRNA in NAFLD are limited but have demonstrated that ncRNAs play a critical role in the pathogenesis of NAFLD. In this review, we summarize NAFLD's pathogenesis and clinical features, discuss current treatment options, and review the involvement of ncRNAs as regulatory molecules in NAFLD and its progression to non-alcoholic steatohepatitis (NASH). In addition, we highlight signaling pathways dysregulated in NAFLD and review their crosstalk with ncRNAs. Having a thorough understanding of the disease process's molecular mechanisms will facilitate development of highly effective diagnostic and therapeutic treatments. Such insights can also inform preventive strategies to minimize the disease's future development.

Extracellular vesicles from normal tissues orchestrate the homeostasis of macrophages and attenuate inflammatory injury of sepsis

Extracellular vesicles (EVs) exist throughout our bodies. We recently revealed the important role of intracardiac EVs induced by myocardial ischemia/reperfusion on cardiac injury and dysfunction. However, the role of EVs isolated from normal tissues remains unclear. Here we found that EVs, derived from murine heart, lung, liver and kidney have similar effects on macrophages and regulate the inflammation, chemotaxis, and phagocytosis of macrophages. Interestingly, EV-treated macrophages showed LPS resistance with reduced expressions of inflammatory cytokines and enhanced phagocytic activity. Furthermore, we demonstrated that the protein content in EVs contributed to the activation of inflammation, while the RNA component mainly limited the excessive inflammatory response of macrophages to LPS. The enrichment of miRNAs, including miR-148a-3p, miR-1a-3p and miR-143-3p was confirmed in tissue EVs. These EV-enriched miRNAs contributed to the inflammation remission in LPS induced macrophages through multiple pathways, including STAT3, P65 and SAPK/JNK. Moreover, administration of both EVs and EV-educated macrophages attenuated septic injury and cytokine storm in murine CLP models. Taken together, the present study disclosed that EVs from normal tissues can orchestrate the homeostasis of macrophages and attenuate inflammatory injury of sepsis. Therefore, tissue derived EVs or their derivatives may serve as potential therapeutic strategies in inflammatory diseases.

miR-192 inhibits the activation of hepatic stellate cells by targeting Rictor

The activation of hepatic stellate cells (HSCs) is regarded as the primary driving factor of liver fibrosis. miR-192, a miRNA associated with hepatocellular carcinoma and enriched in HSCs, has an undisclosed role in HSC activation and liver fibrosis. In this study, a CCl4-induced rat liver fibrosis model and transforming growth factor-beta 1 (TGF-β1)-treated HSC lines (LX-2 and HSC-T6) were used to detect miR-192 and Rictor levels in vivo and in vitro. Bioinformatic analysis and a dual luciferase assay were used to predict and confirm the interaction of Rictor with miR-192. Gain- and/or loss-of-function methods evaluated molecular changes and HSC activation phenotypes, detected by quantitative real-time PCR, western blotting, and immunofluorescence. We observed a gradual downregulation of miR-192 and upregulation of Rictor during CCl4-induced liver fibrosis/cirrhosis in rats. Enriched miR-192 was downregulated, while Rictor was upregulated in TGF-β1-activated HSCs. miR-192 inhibited the activation of HSCs by directly targeting Rictor. High miR-192/low Rictor expression attenuated the fibrotic-related gene expression by AKT/mTORC2 signaling. In conclusion, miR-192 could inhibit the activation of HSCs by directly targeting Rictor in the AKT/mTORC2 signaling pathway. This study provides insights into potential therapeutic targets for liver fibrosis and cirrhosis.

MiR-192-5p Ameliorates Hepatic Lipid Metabolism in Non-Alcoholic Fatty Liver Disease by Targeting Yy1

Non-alcoholic fatty liver disease (NAFLD) is characterized by excessive lipid accumulation in the liver. Clarifying the molecular mechanism of lipid metabolism is crucial for the treatment of NAFLD. We examined miR-192-5p levels in the livers of mice in which NAFLD was induced via a high-fat diet (HFD), as well as in mouse primary hepatocytes and human HepG2 cells treated with free fatty acids (FFAs). MiR-192-5p inhibitor was administered to NAFLD mice and hepatocytes to verify the specific function of miR-192-5p in NAFLD. We validated the target gene of miR-192-5p and further illustrated the effects of this miRNA on the regulation of triglyceride (TG) metabolism. We found that miR-192-5p was significantly increased in the livers of NAFLD mice and FFA-treated hepatocytes. Inhibition of miR-192-5p increased the accumulation of hepatic TGs and aggravated hepatic steatosis in NAFLD mice. In FFA-treated hepatocytes, miR-192-5p inhibitors markedly increased TG content, whereas overexpression of miR-192-5p reduced TG levels. Yin Yang 1 (Yy1) was identified as the target gene of miR-192-5p, which regulates TG synthesis via the YY1/fatty-acid synthase (FASN) pathway. Our results demonstrated that miR-192-5p should be considered a protective regulator in NAFLD that can inhibit hepatic TG synthesis by targeting Yy1.

Rictor mediates p53 deactivation to facilitate the malignant transformation of hepatocytes and promote hepatocarcinogenesis

BACKGROUND

Mutations in TP53 gene is considered a main driver of hepatocellular carcinoma (HCC). While TP53 mutations are the leading cause of p53 dysfunction, their occurrence rates may drop to approximately 10% in cohorts without hepatitis B virus and aflatoxin exposure. This observation suggests that the deactivation of wild-type p53 (p53wt) may be a critical factor in the majority of HCC cases. However, the mechanism undermining p53wt activity in the liver remains unclear.

METHODS

Microarray analysis and luciferase assay were utilized to confirm target associations. Gain- and/or loss-of-function methods were employed to assess alterations in signaling pathways. Protein interactions were analyzed by molecular immunological methods and further visualized by confocal microscopy. Bioinformatic analysis was performed to analyze clinical significance. Tumor xenograft nude mice were used to validate the findings in vivo.

RESULTS

Our study highlights the oncogenic role of Rictor, a key component of the mammalian target of rapamycin complex 2 (mTORC2), in hepatocytes. Rictor exerts its oncogenic function by binding to p53wt and subsequently blocking p53wt activity based on p53 status, requiring the involvement of mTOR. Moreover, we observed a dynamic nucleocytoplasmic distribution pattern of Rictor, characterized by its translocation from the nucleus (in precancerous lesions) to the cytoplasm (in HCCs) during malignant transformation. Notably, Rictor is directly targeted by the liver-enriched microRNA miR-192, and the disruption of the miR-192-Rictor-p53-miR-192 signaling axis was consistently observed in both human and rat HCC models. Clinical analysis associated lower miR-192/higher Rictor with shorter overall survival and more advanced clinical stages (P < 0.05). In mice, xenograft tumors overexpressing miR-192 exhibited lower Rictor expression levels, leading to higher p53 activity, and these tumors displayed slower growth compared to untreated HCC cells.

CONCLUSIONS

Rictor dynamically shuttles between the nucleus and cytoplasm during HCC development. Its pivotal oncogenic role involves binding and inhibiting p53wt activity within the nucleus in early hepatocarcinogenesis. Targeting Rictor presents a promising strategy for HCC based on p53 status.

Inflammation and cardiometabolic diseases induced by persistent organic pollutants and nutritional interventions: Effects of multi-organ interactions

The development and outcome of inflammatory diseases are associated with genetic and lifestyle factors, which include chemical and nonchemical stressors. Persistent organic pollutants (POPs) are major groups of chemical stressors. For example, dioxin-like polychlorinated biphenyls (PCBs), per- and polyfluoroalkyl substances (PFASs), and polybrominated diphenyl ethers (PBDEs) are closely associated with the incidence of inflammatory diseases. The pathology of environmental chemical-mediated inflammatory diseases is complex and may involve disturbances in multiple organs, including the gut, liver, brain, vascular tissues, and immune systems. Recent studies suggested that diet-derived nutrients (e.g., phytochemicals, vitamins, unsaturated fatty acids, dietary fibers) could modulate environmental insults and affect disease development, progression, and outcome. In this article, mechanisms of environmental pollutant-induced inflammation and cardiometabolic diseases are reviewed, focusing on multi-organ interplays and highlighting recent advances in nutritional strategies to improve the outcome of cardiometabolic diseases associated with environmental exposures. In addition, advanced system biology approaches are discussed, which present unique opportunities to unveil the complex interactions among multiple organs and to fuel the development of precision intervention strategies in exposed individuals.

Exosomes: New Insights into the Pathogenesis of Metabolic Syndrome

Exosomes are a subtype of extracellular vesicles (EVs) with a diameter of 30~150 nm (averaging ~100 nm) that are primarily produced through the endosomal pathway, and carry various components such as lipids, proteins, RNA, and other small molecular substances. Exosomes can mediate intercellular communication through the bioactive substances they carry, thus participating in different physiological activities. Metabolic syndrome (MS) is a disease caused by disturbances in the body's metabolism, mainly including insulin resistance (IR), diabetes, obesity, non-alcoholic fatty liver disease (NAFLD), hyperlipidemia, and atherosclerosis (AS). Recent studies have shown that exosomes are closely related to the occurrence and development of MS. Exosomes can act as messengers to mediate signaling transductions between metabolic cells in the organism and play a bidirectional regulatory role in the MS process. This paper mainly reviews the components, biogenesis, biological functions and potential applications of exosomes, and exosomes involved in the pathogenesis of MS as well as their clinical significance in MS diagnosis.

Function of macrophage-derived exosomes in chronic liver disease: From pathogenesis to treatment

Chronic liver disease (CLD) imposes a heavy burden on millions of people worldwide. Despite substantial research on the pathogenesis of CLD disorders, no optimal treatment is currently available for some diseases, such as liver cancer. Exosomes, which are extracellular vesicles, are composed of various cellular components. Exosomes have unique functions in maintaining cellular homeostasis and regulating cell communication, which are associated with the occurrence of disease. Furthermore, they have application potential in diagnosis and treatment by carrying diverse curative payloads. Hepatic macrophages, which are key innate immune cells, show extraordinary heterogeneity and polarization. Hence, macrophage-derived exosomes may play a pivotal role in the initiation and progression of various liver diseases. This review focuses on the effects of macrophage-derived exosomes on liver disease etiology and their therapeutic potential, which will provide new insights into alleviating the global pressure of CLD.

The promise of small particles: extracellular vesicles as biomarkers in liver pathology

Extracellular vesicles (EVs) are nanoscopic packages that are heterogeneous and bona fide players in hepatic physiology and pathology as they are involved in intercellular communication. EVs carrying bioactive cargoes rich in lipids, proteins or nucleic acids are implicated in the onset and progression of liver diseases. Liver pathology using liver biopsy has been assessed for several intricate conditions such as viral hepatitis, alcoholic and non-alcoholic fatty liver disease, hepatic malignancies and drug-induced liver injury. The lacunae, however, lie in early diagnosis and timely treatment of the above conditions, underscoring the need for non-invasive, accurate diagnostic tools that could replace the gold standard method of tissue biopsy. In this regard, EVs have emerged as promising candidates that could serve as potential biomarkers. In the last two decades, EVs, owing to their multifaceted charm in bringing out cell-free therapeutic responses and the ability of their cargoes to be applied to novel biomarkers, have drawn the great attention of researchers with the advancement and clinical application of liquid biopsy. In this review, we recapitulate the role of EVs and provide insights into the promising role of these small packages as biomarkers in liver pathology.

A bibliometric analysis and visualization of nonalcoholic fatty liver disease from 2012 to 2021

As a common chronic liver disease, nonalcoholic fatty liver disease (NAFLD) has attracted increasing attention in the past decade. Nevertheless, there are few bibliometric analyses that systematically study this field as a whole. This paper explores the latest research progress and future research trends of NAFLD through the method of bibliometric analysis. The articles related to NAFLD, published from 2012 to 2021 in the Web of Science Core Collections, were searched on February 21, 2022, using relevant keywords. Two different scientometrics software tools were used to conduct the knowledge maps of NAFLD research field. A total of 7975 articles on NAFLD research were included. From 2012 to 2021, the publications related to NAFLD increased by year. China ranked on the top of the list with 2043 publications, and the University of California System emerged as the premier institution in this field. PLOs One, Journal of Hepatology and Scientific Reports became the prolific journals in this research field. Co-cited reference analysis revealed the landmark literature in this research field. In terms of potential hotspots, the burst keywords analysis revealed that liver fibrosis stage, sarcopenia, and autophagy will become the focus of future NAFLD research. The annual output of the global publications in the field of NAFLD research showed a strong upward trend. Research in the field of NAFLD in China and America is more mature than in other countries. Classic literature lays the foundation for research, and multi-field studies provide the new development directions. And besides, fibrosis stage, sarcopenia and autophagy research are the hot spots and frontiers of this field.

MicroRNAs and Nonalcoholic Steatohepatitis: A Review

Non-alcoholic fatty liver disease (NAFLD) is a clinicopathologic syndrome caused by fat deposition in hepatocytes. Patients with nonalcoholic steatohepatitis (NASH), an advanced form of NAFLD with severe fibrosis, are at high risk for liver-related complications, including hepatocellular carcinoma (HCC). However, the mechanism of progression from simple fat deposition to NASH is complex, and previous reports have linked NAFLD to gut microbiota, bile acids, immunity, adipokines, oxidative stress, and genetic or epigenetic factors. NASH-related liver injury involves multiple cell types, and intercellular signaling is thought to be mediated by extracellular vesicles. MicroRNAs (miRNAs) are short, noncoding RNAs that play important roles as post-transcriptional regulators of gene expression and have been implicated in the pathogenesis of various diseases. Recently, many reports have implicated microRNAs in the pathogenesis of NALFD/NASH, suggesting that exosomal miRNAs are potential non-invasive and sensitive biomarkers and that the microRNAs involved in the mechanism of the progression of NASH may be potential therapeutic target molecules. We are interested in which miRNAs are involved in the pathogenesis of NASH and which are potential target molecules for therapy. We summarize targeted miRNAs associated with the etiology and progression of NASH and discuss each miRNA in terms of its pathophysiology, potential therapeutic applications, and efficacy as a NASH biomarker.

From NAFLD to HCC: Advances in noninvasive diagnosis

Non-alcoholic fatty liver disease (NAFLD) has gradually become one of the major liver health problems in the world. The dynamic course of the disease goes through steatosis, inflammation, fibrosis, and carcinoma. Before progressing to carcinoma, timely and effective intervention will make the condition better, which highlights the importance of early diagnosis. With the further study of the biological mechanism in the pathogenesis and progression of NAFLD, some potential biomarkers have been discovered, and the possibility of their clinical application is gradually being discussed. At the same time, the progress of imaging technology and the emergence of new materials and methods also provide more possibilities for the diagnosis of NAFLD. This article reviews the diagnostic markers and advanced diagnostic methods of NAFLD in recent years.

Epigenetic Regulation in Lean Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD), the most prominent cause of chronic liver disease worldwide, is a rapidly growing epidemic. It consists of a wide range of liver diseases, from steatosis to nonalcoholic steatohepatitis, and predisposes patients to liver fibrosis, cirrhosis, and even hepatocellular carcinoma. NAFLD is strongly correlated with obesity; however, it has been extensively reported among lean/nonobese individuals in recent years. Although lean patients demonstrate a lower prevalence of diabetes mellitus, central obesity, dyslipidemia, hypertension, and metabolic syndrome, a percentage of these patients may develop steatohepatitis, advanced liver fibrosis, and cardiovascular disease, and have increased all-cause mortality. The pathophysiological mechanisms of lean NAFLD remain vague. Studies have reported that lean NAFLD demonstrates a close association with environmental factors, genetic predisposition, and epigenetic modifications. In this review, we aim to discuss and summarize the epigenetic mechanisms involved in lean NAFLD and to introduce the interaction between epigenetic patterns and genetic or non genetic factors. Several epigenetic mechanisms have been implicated in the regulation of lean NAFLD. These include DNA methylation, histone modifications, and noncoding-RNA-mediated gene regulation. Epigenetics is an area of special interest in the setting of lean NAFLD as it could provide new insights into the therapeutic options and noninvasive biomarkers that target this under-recognized and challenging disorder.

Saturated fatty acid-enriched small extracellular vesicles mediate a crosstalk inducing liver inflammation and hepatocyte insulin resistance

Background & Aims

Lipotoxicity triggers non-alcoholic fatty liver disease (NAFLD) progression owing to the accumulation of toxic lipids in hepatocytes including saturated fatty acids (SFAs), which activate pro-inflammatory pathways. We investigated the impact of hepatocyte- or circulating-derived small extracellular vesicles (sEV) secreted under NAFLD conditions on liver inflammation and hepatocyte insulin signalling.

Methods

sEV released by primary mouse hepatocytes, characterised and analysed by lipidomics, were added to mouse macrophages/Kupffer cells (KC) to monitor internalisation and inflammatory responses. Insulin signalling was analysed in hepatocytes exposed to conditioned media from sEV-loaded macrophages/KC. Mice were i.v. injected sEV to study liver inflammation and insulin signalling. Circulating sEV from mice and humans with NAFLD were used to evaluate macrophage-hepatocyte crosstalk.

Results

Numbers of sEV released by hepatocytes increased under NAFLD conditions. Lipotoxic sEV were internalised by macrophages through the endosomal pathway and induced pro-inflammatory responses that were ameliorated by pharmacological inhibition or deletion of Toll-like receptor-4 (TLR4). Hepatocyte insulin signalling was impaired upon treatment with conditioned media from macrophages/KC loaded with lipotoxic sEV. Both hepatocyte-released lipotoxic sEV and the recipient macrophages/KC were enriched in palmitic (C16:0) and stearic (C18:0) SFAs, well-known TLR4 activators. Upon injection, lipotoxic sEV rapidly reached KC, triggering a pro-inflammatory response in the liver monitored by Jun N-terminal kinase (JNK) phosphorylation, NF-κB nuclear translocation, pro-inflammatory cytokine expression, and infiltration of immune cells into the liver parenchyma. sEV-mediated liver inflammation was attenuated by pharmacological inhibition or deletion of TLR4 in myeloid cells. Macrophage inflammation and subsequent hepatocyte insulin resistance were also induced by circulating sEV from mice and humans with NAFLD.

Conclusions

We identified hepatocyte-derived sEV as SFA transporters targeting macrophages/KC and activating a TLR4-mediated pro-inflammatory response enough to induce hepatocyte insulin resistance.

Impact and Implications

Small extracellular vesicles (sEV) released by the hepatocytes under non-alcoholic fatty liver disease (NAFLD) conditions cause liver inflammation and insulin resistance in hepatocytes via paracrine hepatocyte-macrophage-hepatocyte crosstalk. We identified sEV as transporters of saturated fatty acids (SFAs) and potent lipotoxic inducers of liver inflammation. TLR4 deficiency or its pharmacological inhibition ameliorated liver inflammation induced by hepatocyte-derived lipotoxic sEV. Evidence of this macrophage-hepatocyte interactome was also found in patients with NAFLD, pointing to the relevance of sEV in SFA-mediated lipotoxicity in NAFLD.

Role of extracellular vesicles in nonalcoholic fatty liver disease

Background

Nonalcoholic fatty liver disease (NAFLD) is a common chronic liver disease that affects approximately one-quarter of the global population and is becoming increasingly prevalent worldwide. The lack of current noninvasive tools and efficient treatment is recognized as a significant barrier to the clinical management of these conditions. Extracellular vesicles (EVs) are nanoscale vesicles released by various cells and deliver bioactive molecules to target cells, thereby mediating various processes, including the development of NAFLD.

Scope of review

There is still a long way to actualize the application of EVs in NAFLD diagnosis and treatment. Herein, we summarize the roles of EVs in NAFLD and highlight their prospects for clinical application as a novel noninvasive diagnostic tool as well as a promising therapy for NAFLD, owing to their unique physiochemical characteristics. We summarize the literatures on the mechanisms by which EVs act as mediators of intercellular communication by regulating metabolism, insulin resistance, inflammation, immune response, intestinal microecology, and fibrosis in NAFLD. We also discuss future challenges that must be resolved to improve the therapeutic potential of EVs.

Major conclusions

The levels and contents of EVs change dynamically at different stages of diseases and this phenomenon may be exploited for establishing sensitive stage-specific markers. EVs also have high application potential as drug delivery systems with low immunogenicity and high biocompatibility and can be easily engineered. Research on the mechanisms and clinical applications of EVs in NAFLD is in its initial phase and the applicability of EVs in NAFLD diagnosis and treatment is expected to grow with technological progress.

The challenging role of micro-RNAs in non-alcoholic fatty liver disease in children with obesity: is it time for a new era?

INTRODUCTION

As the pediatric obesity epidemic, nonalcoholic fatty liver disease (NAFLD) has become the most common chronic liver disease in childhood. Pediatric NAFLD pathophysiology is tangled and still unclear, but insulin resistance (IR), genetics, epigenetics, oxidative stress, and inflammation act as key players. Due to the increased cardiometabolic risk of these patients, several biomarkers have been proposed for early NAFLD identification, but their clinical utility is poor. Recently, hepatic dysregulation of microRNAs (miRNAs) has been linked to metabolic dysfunction, which in turn implied in NAFLD development. Evidence on the intriguing role of miRNAs in NAFLD pathogenesis has emerging especially in at-risk children such as those with obesity. However, pediatric evidence supporting their potential use as early noninvasive NAFLD tools is still limited but promising.

AREAS COVERED

We provided an overview on the emerging role of miRNAs in pediatric NAFLD by addressing some issues regarding their pathophysiological link with the metabolic milieu and their role as reliable NAFLD markers in children with obesity.

EXPERT OPINION

Strong evidence supports a potential role of miRNAs as early biomarkers of NAFLD in children with obesity. They might represent a valid diagnostic and targeted therapeutic tool due to its close pathogenic link with the metabolic milieu.

A narrative review of the role of exosomes and caveolin-1 in liver diseases and cancer

Exosomes are nanoscale (40-100 nm) vesicles secreted by different types of cells and have attracted extensive interest in recent years because of their unique role in disease development. It can carry related goods, such as lipids, proteins, and nucleic acids, to mediate intercellular communication. This review summarizes exosome biogenesis, release, uptake, and their role in mediating the development of liver diseases and cancer, such as viral hepatitis, drug-induced liver injury, alcohol-related liver disease, non-alcoholic fatty liver disease, hepatocellular carcinoma, and other tumors. Meanwhile, a fossa structural protein, caveolin-1(CAV-1), has also been proposed to be involved in the development of various diseases, especially liver diseases and tumors. In this review, we discuss the role of CAV-1 in liver diseases and different tumor stages (inhibition of early growth and promotion of late metastasis) and the underlying mechanisms by which CAV-1 regulates the process. In addition, CAV-1 has also been found to be a secreted protein that can be released directly through the exosome pathway or change the cargo composition of the exosomes, thus contributing to enhancing the metastasis and invasion of cancer cells during the late stage of tumor development. In conclusion, the role of CAV-1 and exosomes in disease development and the association between them remains to be one challenging uncharted area.

Extracellular Vesicles in Hepatobiliary Health and Disease

Extracellular vesicles (EVs) are membrane-bound nanoparticles released by cells and are an important means of intercellular communication in physiological and pathological states. We provide an overview of recent advances in the understanding of EV biogenesis, cargo selection, recipient cell effects, and key considerations in isolation and characterization techniques. Studies on the physiological role of EVs have relied on cell-based model systems due to technical limitations of studying endogenous nanoparticles in vivo . Several recent studies have elucidated the mechanistic role of EVs in liver diseases, including nonalcoholic fatty liver disease, viral hepatitis, cholestatic liver disease, alcohol-associated liver disease, acute liver injury, and liver cancers. Employing disease models and human samples, the biogenesis of lipotoxic EVs downstream of endoplasmic reticulum stress and microvesicles via intracellular activation stress signaling are discussed in detail. The diverse cargoes of EVs including proteins, lipids, and nucleic acids can be enriched in a disease-specific manner. By carrying diverse cargo, EVs can directly confer pathogenic potential, for example, recruitment and activation of monocyte-derived macrophages in NASH and tumorigenicity and chemoresistance in hepatocellular carcinoma. We discuss the pathogenic role of EVs cargoes and the signaling pathways activated by EVs in recipient cells. We review the literature that EVs can serve as biomarkers in hepatobiliary diseases. Further, we describe novel approaches to engineer EVs to deliver regulatory signals to specific cell types, and thus use them as therapeutic shuttles in liver diseases. Lastly, we identify key lacunae and future directions in this promising field of discovery and development. © 2023 American Physiological Society. Compr Physiol 13:4631-4658, 2023.

Limited role for hyperammonemia in the progression of diet-induced nonalcoholic steatohepatitis

OBJECTIVES

To determine whether hyperammonemia has a direct impact on steatohepatitis in mice fed with a high-fat diet (HFD).

METHODS

Male C57BL/6 mice were divided into two groups receiving either chow diet or HFD. After 12-week NASH modeling, hyperammonemia was induced by intragastric administration of ammonium chloride solution (NH4 Cl) or liver-specific carbamoyl phosphate synthetase 1 (Cps1) knockdown. In vitro experiments were performed in HepG2 cells induced by free fatty acid (FFA) and NH4 Cl.

RESULTS

NH4 Cl administration led to increased levels of plasma and hepatic ammonia in NASH mice. NH4 Cl-induced hyperammonemia did not influence liver histological changes in mice fed with HFD; however, elevated plasma cholesterol level, and an increasing trend of liver lipid content were observed. No significant effect of hyperammonemia on hepatic inflammation and fibrosis in NASH mice was found. In vitro cell experiments showed that NH4 Cl treatment failed to increase the lipid droplet content and the expressions of de novo lipogenesis genes in HepG2 cells induced by FFA. The knockdown of Cps1 in HFD-fed mice resulted in elevated plasma ammonia levels but did not cause histological change in the liver.

CONCLUSIONS

Our study revealed a limited role of ammonia in aggravating the progression of NASH. Further studies are needed to clarify the role and mechanism of ammonia in NASH development.

Role of adipocyte-derived extracellular vesicles during the progression of liver inflammation to hepatocellular carcinoma

Extracellular vesicles are membrane-bound cargos that vary in size and are stably transported through various bodily fluids. Extracellular vesicles communicate information between the cells and organs. Extracellular vesicles from the diseased cells alter cellular responses of the recipient cells contributing to disease progression. In obesity, adipocytes become hypertrophic and the extracellular vesicles from these dysfunctional adipocytes showed altered cargo contents instigating pathophysiological response leading to chronic liver diseases. In this review, the role of adipocyte-derived extracellular vesicles on the progression of liver inflammation, fibrosis, cirrhosis, and hepatocellular carcinoma are extensively discussed. Newer approaches are crucial to take advantage of extracellular vesicles and their content as biomarkers to diagnose initial liver inflammation before reaching to an irreversible liver failure stage.

Current Status and Prospect of Delivery Vehicle Based on Mesenchymal Stem Cell-Derived Exosomes in Liver Diseases

With the improvement of the average life expectancy and increasing incidence of obesity, the burden of liver disease is increasing. Liver disease is a serious threat to human health. Currently, liver transplantation is the only effective treatment for end-stage liver disease. However, liver transplantation still faces unavoidable difficulties. Mesenchymal stem cells (MSCs) can be used as an alternative therapy for liver disease, especially liver cirrhosis, liver failure, and liver transplantation complications. However, MSCs may have potential tumorigenic effects. Exosomes derived from MSCs (MSC-Exos), as the important intercellular communication mode of MSCs, contain various proteins, nucleic acids, and DNA. MSC-Exos can be used as a delivery system to treat liver diseases through immune regulation, apoptosis inhibition, regeneration promotion, drug delivery, and other ways. Good histocompatibility and material exchangeability make MSC-Exos a new treatment for liver diseases. This review summarizes the latest research on MSC-Exos as delivery vehicles in different liver diseases, including liver injury, liver failure, liver fibrosis, hepatocellular carcinoma (HCC), and ischemia and reperfusion injury. In addition, we discuss the advantages, disadvantages, and clinical application prospects of MSC-Exos-based delivery vectors in the treatment of liver diseases.

Circulating miRNA-192 and miR-29a as Disease Progression Biomarkers in Hepatitis C Patients with a Prevalence of HCV Genotype 3

MicroRNAs miR-29a and miR-192 are involved in inflammatory and fibrotic processes of chronic liver disease, and circulating miR-29a is suggested to diagnose fibrosis progression due to hepatitis C virus (HCV) infection. This study aimed to evaluate the expression profile of circulating miR-192 and 29a in a patient cohort with a high frequency of HCV genotype-3. A total of 222 HCV blood samples were collected and serum were separated. Patients were classified into mild, moderate, and severe liver injury based on their Child-Turcotte-Pugh CTP score. RNA was isolated from the serum and used for quantitative real-time PCR. The HCV genotype-3 (62%) was the predominant HCV genotype. In HCV patients, the serum miR-192 and miR-29a levels were significantly upregulated in comparison to healthy controls (p = 0.0017 and p = 0.0001, respectively). The progression rate of miR-192 and 29a in the patient group with mild was highly upregulated compared to patients with moderate and severe hepatitis infection. The ROC curve of miR-192 and miR-29a of moderate liver disease had a significant diagnostic performance compared to the other HCV-infected groups. The increase in miR-29a and miR-192 serum levels was even slightly higher in patients with HCV genotype-3 than in non-genotype-3 patients. In conclusion, serum miR-192 and miR-29a levels significantly increased during the progression of chronic HCV infection. The marked upregulation in patients with HCV genotype-3 suggests them as potential biomarkers for hepatic disease, independently of the HCV genotype.

Exosomes: Nomenclature, Isolation, and Biological Roles in Liver Diseases

The biogenesis and biological roles of extracellular vesicles (EVs) in the progression of liver diseases have attracted considerable attention in recent years. EVs are membrane-bound nanosized vesicles found in different types of body fluids and contain various bioactive materials, including proteins, lipids, nucleic acids, and mitochondrial DNA. Based on their origin and biogenesis, EVs can be classified as apoptotic bodies, microvesicles, and exosomes. Among these, exosomes are the smallest EVs (30-150 nm in diameter), which play a significant role in cell-to-cell communication and epigenetic regulation. Moreover, exosomal content analysis can reveal the functional state of the parental cell. Therefore, exosomes can be applied to various purposes, including disease diagnosis and treatment, drug delivery, cell-free vaccines, and regenerative medicine. However, exosome-related research faces two major limitations: isolation of exosomes with high yield and purity and distinction of exosomes from other EVs (especially microvesicles). No standardized exosome isolation method has been established to date; however, various exosome isolation strategies have been proposed to investigate their biological roles. Exosome-mediated intercellular communications are known to be involved in alcoholic liver disease and nonalcoholic fatty liver disease development. Damaged hepatocytes or nonparenchymal cells release large numbers of exosomes that promote the progression of inflammation and fibrogenesis through interactions with neighboring cells. Exosomes are expected to provide insight on the progression of liver disease. Here, we review the biogenesis of exosomes, exosome isolation techniques, and biological roles of exosomes in alcoholic liver disease and nonalcoholic fatty liver disease.

Quercetin alleviates tubulointerstitial inflammation by inhibiting exosomes-mediated crosstalk between tubular epithelial cells and macrophages

BACKGROUND

Tubulointerstitial inflammation (TII) is a critical pathological feature of kidney disease leading to renal fibrosis, and its treatment remains a major clinical challenge. We sought to explore the role of quercetin, a potential exosomes inhibitor, in exosomes release and TII.

METHODS

The effects of quercetin on exosomes release and TII were examined by two TII mouse models: the unilateral ureteral obstruction (UUO) models and the LPS-induced mouse models. In vitro, exosomes-mediated crosstalk between tubular epithelial cells (TECs) and macrophages was performed to investigate the mechanisms by which quercetin inhibited exosomes and TII.

RESULTS

In this study, we found that exosomes-mediated crosstalk between TECs and macrophages contributed to the development of TII. In vitro, exosomes released from LPS-stimulated TECs induced increased expression of inflammatory cytokines and fibrotic markers in Raw264·7 cells and vice versa. Interestingly, heat shock protein 70 (Hsp70) or Hsp90 proteins could control exosomes release from TECs and macrophages both in vivo and in vitro. Importantly, quercetin, a previously recognized heat shock protein inhibitor, could significantly reduce exosomes release in TII models by down-regulating Hsp70 or Hsp90. Quercetin abrogated exosomes-mediated intercellular communication, which attenuated TII and renal fibrosis accordingly.

CONCLUSION

Quercetin could serve as a novel strategy for treatment of tubulointerstitial inflammation by inhibiting the exosomes-mediated crosstalk between tubules and macrophages.

Hepatocyte-derived extracellular vesicles miR-122-5p promotes hepatic ischemia reperfusion injury by regulating Kupffer cell polarization

Ischemia reperfusion injury remains a major barrier to liver transplantation, especially using grafts from donation after circulatory death, and it is also a pressing issue to be solved in clinical practice. Kupffer cell polarization toward a proinflammatory M1 phenotype is an early trigger of liver ischemia-reperfusion injury. However, the molecular mechanism regulating Kupffer cell polarization has not yet been fully elucidated. We induced liver ischemia reperfusion injury in mice and obtained samples from patients undergoing liver transplantation, serum and hepatocytes-derived extracellular vesicles were isolated by differential ultracentrifugation. Kupffer cell polarization was examined by flow cytometry and immunofluorescence histochemistry. RNA-seq was conducted to detect the differentially expressed miRNAs in extracellular vesicles. The role and mechanism of exosomal miR-122-5p in liver ischemia-reperfusion injury were determined both in vitro and in vivo. We identified ischemia reperfusion induced extracellular vesicles as a major cause of hepatic inflammation and tissue damage using adoptive transfer and release inhibition. The study also demonstrated that hepatocyte-derived exosomal miR-122-5p mediates liver ischemia reperfusion injury by polarizing Kupffer cell via PPARδ down-regulation and NF-κB pathway activation using profiling and functional analysis. Moreover, inhibiting miR-122-5p with antagomir suppressed Kupffer cell M1 polarization and attenuated liver ischemia reperfusion injury. Overall, our study demonstrated that hepatocyte-derived exosomal miR-122-5p played a critical role in promoting hepatic ischemia reperfusion injury through modulating PPARδ signaling and NF-κB pathway to introduce M1 polarization of Kupffer cell. Inhibition of miR-122-5p exhibited a protective effect against liver ischemia reperfusion injury, suggesting a potential therapeutic target for liver transplantation.

Emerging role of engineered exosomes in nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is the most common chronic liver disease worldwide. NAFLD comprises a continuum of liver abnormalities from nonalcoholic fatty liver to nonalcoholic steatohepatitis, and can even lead to cirrhosis and liver cancer. However, a well-established treatment for NAFLD has yet to be identified. Exosomes have become an ideal drug delivery tool because of their high transmissibility, low immunogenicity, easy accessibility and targeting. Exosomes with specific modifications, known as engineered exosomes, have the potential to treat a variety of diseases. Here, we review the treatment of NAFLD with engineered exosomes and the potential use of exosomes as biomarkers and therapeutic targets for NAFLD.

The diverse roles of macrophages in metabolic inflammation and its resolution

Macrophages are one of the most functionally diverse immune cells, indispensable to maintain tissue integrity and metabolic health. Macrophages perform a myriad of functions ranging from promoting inflammation, through inflammation resolution to restoring and maintaining tissue homeostasis. Metabolic diseases encompass a growing list of diseases which develop from a mix of genetics and environmental cues leading to metabolic dysregulation and subsequent inflammation. In this review, we summarize the contributions of macrophages to four metabolic conditions-insulin resistance and adipose tissue inflammation, atherosclerosis, non-alcoholic fatty liver disease and neurodegeneration. The role of macrophages is complex, yet they hold great promise as potential therapies to address these growing health concerns.

Integrated miRNA-mRNA analysis reveals the dysregulation of lipid metabolism in mouse liver induced by developmental arsenic exposure

Developmental arsenic exposure leads to increased susceptibility to liver diseases including nonalcoholic fatty liver diseases, but the mechanism is incompletely understood. In this study, C57BL/6J mice were used to establish a lifetime arsenic exposure model covering developmental stage. We found that arsenic-exposed offspring in later life showed hepatic lipid deposition and increased triglyceride content. Despite no significant hepatic pathological changes in the offspring at weaning, 86 miRNAs and 136 mRNAs were differentially expressed according to miRNA array and mRNA sequencing. The differentially expressed genes (DEGs) were crossed with the target genes predicted by differentially expressed miRNAs (DEMs), and 47 differentially expressed target genes (DETGs) were obtained. Functional annotation suggested that lipid metabolism related pathways were significantly enriched. The pivotal regulator in the four major pathways to maintain liver lipid homeostasis were further determined, with significant alterations found in FABP5, SREBP1, ACOX1 and EHHADH. Of note, miRNA-mRNA integration analysis revealed that miR-7118-5p, miR-7050-5p, miR-27a/b-3p, and miR-103-3p acted as key regulators of fatty acid metabolism genes. Taken together, miRNA-mRNA integration analysis indicates that the lipid metabolism pathway in the liver of weaned mice was dysregulated by developmental arsenic exposure, which may contribute to the development of NAFLD in later life.

Gamma-Muricholic Acid Inhibits Nonalcoholic Steatohepatitis: Abolishment of Steatosis-Dependent Peroxidative Impairment by FXR/SHP/LXRα/FASN Signaling

Nonalcoholic steatohepatitis (NASH) reflects the outcome of steatosis-based peroxidative impairment. Here, the effect and mechanism of γ-muricholic acid (γ-MCA) on NASH were investigated on the basis of its actions in hepatic steatosis, lipid peroxidation, peroxidative injury, hepatocyte apoptosis, and its NAFLD activity score (NAS). The agonist action of γ-MCA on farnesoid X receptor (FXR) upregulated the small heterodimer partner (SHP) expression of hepatocytes. An increase in SHP attenuated the triglyceride-dominated hepatic steatosis which was induced in vivo by a high-fat high-cholesterol (HFHC) diet and in vitro by free fatty acids depending on the inhibition of liver X receptor α (LXRα) and fatty acid synthase (FASN). In contrast, FXR knockdown abrogated the γ-MCA-dependent lipogenic inactivation. When compared to their excessive production in HFHC diet-induced rodent NASH, products of lipid peroxidation (MDA and 4-HNE) exhibited significant reductions upon γ-MCA treatment. Moreover, the decreased levels of serum alanine aminotransferases and aspartate aminotransferases demonstrated an improvement in the peroxidative injury of hepatocytes. By TUNEL assay, injurious amelioration protected the γ-MCA-treated mice against hepatic apoptosis. The abolishment of apoptosis prevented lobular inflammation, which downregulated the incidence of NASH by lowering NAS. Collectively, γ-MCA inhibits steatosis-induced peroxidative injury to ameliorate NASH by targeting FXR/SHP/LXRα/FASN signaling.

Hepatic-Targeted Nano-enzyme with Resveratrol Loading for Precise Relief of Nonalcoholic Steatohepatitis

Nonalcoholic steatohepatitis (NASH) is characterized by massive lipid deposition in hepatocytes and is often associated with hepatic inflammation and other severe metabolic syndromes. The intervention of NASH can prevent its further progression into hepatocarcinoma. In this study we have successfully constructed liver-targeted Ce-based hollow mesoporous nanocarriers loaded with bioactive drugs. This may provide an effective approach for eliminating NASH. Liver-section-specific targeting was realized by covalently linked galactose (Gal), which can be specifically recognized by receptors in the membranes of hepatocytes. Meanwhile, resveratrol (Res), a drug used to treat NASH, was efficiently loaded into the pores and cavity of CeO₂ (Res@H-CeO₂ -Gal). In steatotic HepG2 cells (free fatty acid induction), this nanosystem was found to enhance cellular Res internalization for improved anti-lipogenesis activity. In mice with NASH, Res@H-CeO₂ -Gal increased Res delivery to liver sections for a reduction in lipid accumulation and enhanced anti-inflammatory activity from the antioxidant capacity of Ce-based nanocarriers. This effectively recovered NASH mice to the normal state. These findings show that the hepatic targeting and Res delivery nanoplatform could act as a safe and promising strategy for the elimination of NASH and other liver diseases.

The role of miRNAs in liver diseases: Potential therapeutic and clinical applications

MicroRNAs (miRNAs) are a class of short, non-coding RNAs that function post-transcriptionally to regulate gene expression by binding to particular mRNA targets and causing destruction of the mRNA or translational inhibition of the mRNA. The miRNAs control the range of liver activities, from the healthy to the unhealthy. Considering that miRNA dysregulation is linked to liver damage, fibrosis, and tumorigenesis, miRNAs are a promising therapeutic strategy for the evaluation and treatment of liver illnesses. Recent findings on the regulation and function of miRNAs in liver diseases are discussed, with an emphasis on miRNAs that are highly expressed or enriched in hepatocytes. Alcohol-related liver illness, acute liver toxicity, viral hepatitis, hepatocellular carcinoma, liver fibrosis, liver cirrhosis, and exosomes in chronic liver disease all emphasize the roles and target genes of these miRNAs. We briefly discuss the function of miRNAs in the etiology of liver diseases, namely in the transfer of information between hepatocytes and other cell types via extracellular vesicles. Here we offer some background on the use of miRNAs as biomarkers for the early prognosis, diagnosis, and assessment of liver diseases. The identification of biomarkers and therapeutic targets for liver disorders will be made possible by future research into miRNAs in the liver, which will also help us better understand the pathogeneses of liver diseases.