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

PD-1 inhibitor inducing exosomal miR-34a-5p expression mediates the cross talk between cardiomyocyte and macrophage in immune checkpoint inhibitor-related cardiac dysfunction

Background

Immune checkpoint inhibitors (ICIs) have been an important therapeutic advancement in the field of cancer medicine. Recent reports provided greater insights into the cardiovascular adverse events, which prohibited the use of ICIs. Cardiovascular adverse events occur in different forms, such as myocarditis and cardiomyopathy, myocardial fibrosis, heart failure and pericardial disease. Cardiac aging overlapped with the occurrence of some cardiac diseases. Exosomes mediate cell–cell cross talk in cardiac diseases by transferring a variety of biomolecules, including microRNAs (miRs). miR-34a-5p is a well-known miR associated with the cardiac senescence. This study aimed to investigate whether cardiovascular adverse effects of the programmed cell death 1 (PD-1) inhibitor, a widely used ICI, were related to exosomal-transferred miR-34a-5p in cardiac senescence in a mouse model.

Methods and results

The upregulation of miR-34a-5p in cardiomyocytes induced by exosomes derived from PD-1 inhibitor–treated macrophages, accompanied by cardiac senescence, caused cardiac injury in mouse hearts. miR-34a-5p was identified as an exosomal transfer RNA to induce cardiac senescence–related injury. Inhibiting miR-34a-5p in macrophages attenuated the exosome^{PD-1 inhibitor}-induced pro-senescent effect in cardiomyocytes. TargetScan and luciferase assay showed that miR-34a-5p targeted the serine/threonine-protein phosphatase 1 regulatory subunit 10 (PNUTS) 3′-untranslated region.

Conclusions

Exosomes derived from PD-1 inhibitor–treated macrophages exerted a pro-senescent effect by modulating the miR-34a-5p/PNUTS signaling pathway. The findings might supply new targets to ameliorate cardiac injury in patients with cancer receiving PD-1 inhibitor treatment.

Pediatric Non-Alcoholic Fatty Liver Disease: Nutritional Origins and Potential Molecular Mechanisms

Non-alcoholic fatty liver disease (NAFLD) is the number one chronic liver disease worldwide and is estimated to affect nearly 40% of obese youth and up to 10% of the general pediatric population without any obvious signs or symptoms. Although the early stages of NAFLD are reversible with diet and lifestyle modifications, detecting such stages is hindered by a lack of non-invasive methods of risk assessment and diagnosis. This absence of non-invasive means of diagnosis is directly related to the scarcity of long-term prospective studies of pediatric NAFLD in children and adolescents. In the majority of pediatric NAFLD cases, the mechanisms driving the origin and rapid progression of NAFLD remain unknown. The progression from NAFLD to non-alcoholic steatohepatitis (NASH) in youth is associated with unique histological features and possible immune processes and metabolic pathways that may reflect different mechanisms compared with adults. Recent data suggest that circulating microRNAs (miRNAs) are important new biomarkers underlying pathways of liver injury. Several factors may contribute to pediatric NAFLD development, including high-sugar diets, in utero exposures via epigenetic alterations, changes in the neonatal microbiome, and altered immune system development and mitochondrial function. This review focuses on the unique aspects of pediatric NAFLD and how nutritional exposures impact the immune system, mitochondria, and liver/gastrointestinal metabolic health. These factors highlight the need for answers to how NAFLD develops in children and for early stage-specific interventions.

G-MDSCs-Derived Exosomal miRNA-143-3p Promotes Proliferation via Targeting of ITM2B in Lung Cancer

Background

The immune environment of lung cancer is complex, and the critical immune factors that promote lung cancer progression need to be explored. Granulocytic myeloid-derived suppressor cells (G-MDSCs) are regarded as immune suppressing cells. However, they also promote tumor progression through other ways, which needs to be explored further. Therefore, we sought to study the regulatory mechanisms underlying the cancer promoting function of G-MDSCs in lung cancer.

Methods

G-MDSCs were isolated from lung cancer tissues using flow cytometry. Exosomes were separated from the G-MDSCs supernatant by ultracentrifugation and verified using flow cytometry, Western blot, and transmission electron microscopy (TEM). RNA sequencing was used to identify the differential miRNAs and genes. Real-time quantitative real-time PCR (RT-qPCR) confirmed these results. The proliferation rate was assessed using the CCK-8 assay. Lentiviral vectors were used to alter the expression of the miRNAs and genes to analyze their effects on lung cancer progression.

Results

G-MDSCs secreted more exosomes in the lung cancer tissues, which promoted cancer progression by accelerating proliferation. Micro RNA-143-3p (miR-143-3p) increased in G-MDSCs derived exosomes and downregulated integral membrane protein 2B (ITM2B) by targeting the 3ʹ-untranslated region (UTR) region. Overexpression of miR-143-3p enhanced proliferation by inhibiting transcription of ITM2B to activate the PI3K/Akt signaling pathway, which can be blocked by deguelin. This phenomenon was further confirmed by accelerated tumor growth and worse prognosis in mice.

Conclusion

The key findings of this study highlight the potential of the G-MDSC-derived exosomes and the miR-143-3p/ITM2B axis as therapeutic targets and clinical indicators of lung cancer.

Roles of Macrophages and Exosomes in Liver Diseases

Exosomes are small discoid extracellular vesicles (EVs) originating from endosomes that are 30-150 nm in diameter and have a double lipid layer. They participate in the immune response, cell migration, cell differentiation, and tumor invasion and mediate intercellular communication, regulating the biological activity of receptor cells through the proteins, nucleic acids, and lipids that they carry. Exosomes also play vital roles in the diagnosis and treatment of liver diseases. Macrophages, which show unique phenotypes and functions in complex microenvironments, can be divided into M1 and M2 subtypes. M1 macrophages function in immune surveillance, and M2 macrophages downregulate the immune response. Recent studies have shown that macrophages are involved in non-alcoholic fatty liver disease, liver fibrosis, and hepatocellular carcinoma. Moreover, several studies have demonstrated that liver diseases are associated with exosomes derived from or transferred to macrophages. This review focuses on the participation of macrophages and exosomes in liver diseases.

Serum exosomal microRNA-766-3p expression is associated with poor prognosis of esophageal squamous cell carcinoma

The aim was to analyze the association between exosomal microRNA (miR)‐766‐3p expression levels in serum and the prognosis of esophageal squamous cell carcinoma (ESCC). The serum global exosomal miRNA expression of ESCC patients was measured by microRNA microarray. Quantitative real‐time PCR was used to analyze the expression levels of candidate miRNAs in both serum and tissues from ESCC patients. Wilcoxon tests were applied to evaluate clinical characteristics and their association with serum levels of exosomal miR‐766‐3p. A Cox regression model was used to identify prognostic factors. The effects of miR‐766‐3p expression on cell migration and invasion were examined using Transwell assays, and CCK‐8 assays were carried out to measure cell proliferation. The TNM stage was associated with high serum exosomal miR‐766‐3p levels of ESCC patients (P = .030). Higher serum exosomal miR‐766‐3p expression levels were associated with poor prognosis (for overall survival, hazard ratio [HR] [95% confidence interval (CI)], 2.21 [1.00, 4.87]; for disease‐free survival, HR [95% CI], 2.15 [1.01, 4.59]). However, we found no association between the expression of miR‐766‐3p in tissue and ESCC prognosis. In vitro results showed that miR‐766‐3p promotes cell migration and invasion, but not cell proliferation. By using dual‐luciferase reporter assay, HOXA13 was confirmed as a direct target gene of miR‐766‐3p. The ESCC patients with highly expressed serum exosomal miR‐766‐3p had a significantly worse survival. Therefore, serum exosomal miR‐766‐3p could serve as a prognostic marker for the assessment of ESCC.

Insights Into Extracellular Vesicles as Biomarker of NAFLD Pathogenesis

Nonalcoholic fatty liver disease (NAFLD) is the most common cause of chronic liver disease around the world estimated to affect up to one-third of the adult population and is expected to continue rising in the coming years. Nonalcoholic fatty liver disease is considered as the hepatic manifestation of the metabolic syndrome because it is strongly associated with obesity, insulin resistance, type 2 diabetes mellitus, and cardiovascular complications. Despite its high prevalence, factors leading to NAFLD progression from simple steatosis to nonalcoholic steatohepatitis, cirrhosis, and, ultimately hepatocellular carcinoma remain poorly understood. To date, no treatment has proven efficacy, and also no reliable method is currently available for diagnosis or staging of NAFLD beyond the highly invasive liver biopsy. Recently, extracellular vesicles (EVs) have emerged as potential candidate biomarkers for the diagnosis of NAFLD. Extracellular vesicles are circulating, cell-derived vesicles containing proteins and nucleic acids, among other components, that interact with and trigger a plethora of responses in neighbor or distant target cells. Several mechanisms implicated in NAFLD progression, such as inflammation, fibrosis, and angiogenesis, all related to metabolic syndrome–associated lipotoxicity, trigger EV production and release by liver cells. As hepatocytes represent ~80% of the liver volume, in this review we will focus on hepatocyte-derived EVs as drivers of the interactome between different liver cell types in NAFLD pathogenesis, as well as in their role as noninvasive biomarkers for NAFLD diagnosis and progression. Based on that, we will highlight the research that is currently available on EVs in this topic, the current limitations, and future directions for implementation in a clinical setting as biomarkers or targets of liver disease.

Immune checkpoint inhibitor induces cardiac injury through polarizing macrophages via modulating microRNA-34a/Kruppel-like factor 4 signaling

Cancer immunotherapy has become a well-established treatment option for some cancers; however, its use is hampered by its cardiovascular adverse effects. Immune checkpoint inhibitors (ICIs)-related cardiac toxicity took place in kinds of different forms, such as myocarditis, acute coronary syndrome, and pericardial disease, with high mortality rates. This study aimed to investigate the roles of programmed death-1 (PD-1) inhibitor, one of widespread used ICIs, in the development of murine cardiac injury. PD-1 inhibitor is known to transduce immunoregulatory signals that modulate macrophages polarization to attack tumor cells. Hence, this study explored whether the cardiovascular adverse effects of PD-1 inhibitor were related to macrophage polarization. MicroRNA-34a (miR-34a), which appears to regulate the polarization of cultured macrophages to induce inflammation, is examined in cardiac injury and macrophage polarization induced by the PD-1 inhibitor. As a target of miR-34a, Krüppel-like factor 4 (KLF4) acted as an anti-inflammation effector to take cardiac protective effect. Further, it investigated whether modulating the miR-34a/KLF4-signaling pathway could influence macrophage polarization. The PD-1 inhibitor markedly induced M1 phenotype macrophage polarization with impaired cardiac function, whereas miR-34a inhibitor transfection treatment reversed M1 polarization and cardiac injury in vivo. In vitro, PD-1 inhibitor-induced M1 polarization was accompanied by an increase in the expression of miR-34a but a decrease in the expression of KLF4. TargetScan and luciferase assay showed that miR-34a targeted the KLF4 3′-untranslated region. Either miR-34a inhibition or KLF4 overexpression could abolish M1 polarization induced by the PD-1 inhibitor. The findings strongly suggested that the PD-1 inhibitor exerted its effect in promoting M1 polarization and cardiac injury by modulating the miR-34a/KLF4-signaling pathway and inducing myocardial inflammation. These findings might help us to understand the pathogenesis of cardiac injury during immunotherapy, and provide new targets in ameliorating cardiac injury in patients with cancer receiving PD-1 inhibitor treatment.

Efficacy of serum miRNA test as a non-invasive method to diagnose nonalcoholic steatohepatitis: a systematic review and meta-analysis

Background

Nonalcoholic steatohepatitis (NASH) is a key turning point during the progression of nonalcoholic fatty liver disease (NAFLD). Recent studies have shown that serum miRNA tests may be effective in the diagnosis of NAFLD. We conducted a meta-analysis to assess the evidence for the diagnostic efficacy of serum miRNAs in patients with NAFLD and its subtype, NASH, in particular.

Methods

After a systematic review, sensitivity, specificity, and area under the receiver operating characteristics curve (AUROC) were pooled to determine the efficacy of serum miRNA test for the diagnosis of NAFLD and NASH. Clinical utility was evaluated by Fagan’s nomogram and likelihood ratio scattergram. Heterogeneity was evaluated by subgroup analysis and meta-regression. Publication bias was detected by Deeks’ funnel plot.

Results

We included 27 trials containing 1775 NAFLD patients (including simple steatosis and NASH) and 586 NASH patients. For NAFLD vs NASH, the pooled sensitivity, specificity, and AUROC were (0.71 vs. 0.74), (0.76 vs. 0.85) and (0.80 vs. 0.86), respectively. Serum miRNA had high accuracy for distinguishing NASH from simple steatosis, with an AUROC of 0.91. Among the most commonly studied serum miRNAs, miRNA-34a showed moderate diagnostic accuracy for NAFLD and the lowest heterogeneity (sensitivity I² = 5.73%, specificity I² = 33.16%, AUROC = 0.85). According to subgroup analysis and meta-regression, a lower BMI (< 30 kg/m²) might be a crucial source of heterogeneity.

Conclusions

As a novel non-invasive method, serum miRNA test exhibited robust diagnostic efficacy for NASH. Among these well-studied miRNAs, miRNA-34a was more available for diagnosis. Diagnosis of NAFLD by serum miRNA is more likely to be accurate in patients with BMI ≥ 30 kg/m².

Rapamycin-Loaded mPEG-PLGA Nanoparticles Ameliorate Hepatic Steatosis and Liver Injury in Non-alcoholic Fatty Liver Disease

Non-alcoholic fatty liver disease (NAFLD) is characterized by excessive lipid accumulation and liver injury, and is the leading cause of chronic liver disease worldwide. There is an urgent need to develop novel pathophysiology-oriented therapy in human. Rapamycin (RAPA) has been recognized as a promising drug for alleviating hepatic steatosis on NAFLD, but the poorly water-soluble properties and side effects of RAPA limit their clinical use. In this study, we aimed to investigate the in vitro and in vivo therapeutic efficacy of biodegradable mPEG-PLGA polymers loaded with RAPA (NP-RAPA) on NAFLD. NP-RAPA were prepared by a green process using an emulsion/solvent evaporation method, the therapeutic efficacy on NAFLD were investigated on HepG2 cells incubated with oleic acid (OA) and in the livers of mice with NAFLD induced by high-fat diet (HFD). Compared with free RAPA, NP-RAPA significantly reduced lipid accumulation in HepG2 cells, and obviously ameliorated hepatic steatosis and liver injury in mice though enhancing the therapeutic efficacy of RAPA through reducing SREBP-1c-dependent de novo lipogenesis (DNL) and promoting PPARα-mediated fatty acid oxidation. This study suggests that mPEG-PLGA can be used as the potential therapeutic strategy and novel drug delivery for improving the efficacy of rapamycin for treatment of NAFLD.

Macrophages in metabolic associated fatty liver disease

Metabolic associated fatty liver disease (MAFLD), formerly named non-alcoholic fatty liver disease is the most common liver disorder in many countries. The inflammatory subtype termed steatohepatitis is a driver of disease progression to cirrhosis, hepatocellular carcinoma, liver transplantation, and death, but also to extrahepatic complications including cardiovascular disease, diabetes and chronic kidney disease. The plasticity of macrophages in response to various environmental cues and the fact that they can orchestrate cross talk between different cellular players during disease development and progression render them an ideal target for drug development. This report reviews recent advances in our understanding of macrophage biology during the entire spectrum of MAFLD including steatosis, inflammation, fibrosis, and hepatocellular carcinoma, as well as for the extra-hepatic manifestations of MAFLD. We discuss the underlying molecular mechanisms of macrophage activation and polarization as well as cross talk with other cell types such as hepatocytes, hepatic stellate cells, and adipose tissue. We conclude with a discussion on the potential translational implications and challenges for macrophage based therapeutics for MAFLD.

Extracellular Vesicles in NAFLD/ALD: From Pathobiology to Therapy

In recent years, knowledge on the biology and pathobiology of extracellular vesicles (EVs) has exploded. EVs are submicron membrane-bound structures secreted from different cell types containing a wide variety of bioactive molecules (e.g., proteins, lipids, and nucleic acids (coding and non-coding RNA) and mitochondrial DNA). EVs have important functions in cell-to-cell communication and are found in a wide variety of tissues and body fluids. Better delineation of EV structures and advances in the isolation and characterization of their cargo have allowed the diagnostic and therapeutic implications of these particles to be explored. In the field of liver diseases, EVs are emerging as key players in the pathogenesis of both nonalcoholic liver disease (NAFLD) and alcoholic liver disease (ALD), the most prevalent liver diseases worldwide, and their complications, including development of hepatocellular carcinoma. In these diseases, stressed/damaged hepatocytes release large quantities of EVs that contribute to the occurrence of inflammation, fibrogenesis, and angiogenesis, which are key pathobiological processes in liver disease progression. Moreover, the specific molecular signatures of released EVs in biofluids have allowed EVs to be considered as promising candidates to serve as disease biomarkers. Additionally, different experimental studies have shown that EVs may have potential for therapeutic use as a liver-specific delivery method of different agents, taking advantage of their hepatocellular uptake through interactions with specific receptors. In this review, we focused on the most recent findings concerning the role of EVs as new structures mediating autocrine and paracrine intercellular communication in both ALD and NAFLD, as well as their potential use as biomarkers of disease severity and progression. Emerging therapeutic applications of EVs in these liver diseases were also examined, along with the potential for successful transition from bench to clinic.

The cellular pathways of liver fibrosis in non-alcoholic steatohepatitis

Non-alcoholic steatohepatitis (NASH) is considered the advanced stage of non-alcoholic fatty liver disease (NAFLD). It is characterized by liver steatosis, inflammation and different degrees of fibrosis. Although the exact mechanisms by which fatty liver progresses to NASH are still not well understood, innate and adaptive immune responses seem to be essential key regulators in the establishment, progression, and chronicity of these disease. Diet-induced lipid overload of parenchymal and non-parenchymal liver cells is considered the first step for the development of fatty liver with the consequent organelle dysfunction, cellular stress and liver injury. These will generate the production of pro-inflammatory cytokines, chemokines and damage-associated molecular patterns (DAMPs) that will upregulate the activation of Kupffer cells (KCs) and monocyte-derived macrophages (MMs) favoring the polarization of the tolerogenic environment of the liver to an immunogenic phenotype with the resulting transdifferentiation of hepatic stellate cells (HSCs) into myofibroblasts developing fibrosis. In the long run, dendritic cells (DCs) will activate CD4+ T cells polarizing into the pro-inflammatory lymphocytes Th1 and Th17 worsening the liver damage and inflammation. Therefore, the objective of this review is to discuss in a systematic way the mechanisms known so far of the immune and non-proper immune liver cells in the development and progression of NASH.

Retracted Article: Macrophage-derived exosomes mediate osteosarcoma cell behavior by activating AKT signaling

Osteosarcoma is the most common type of bone tumor, which severely threatens the health of adolescents and young adults. Tumor-infiltrating macrophages have been shown to mediate cancer progression via extracellular vesicles. However, their potential mechanisms in osteosarcoma progression and in drug-resistance are still not yet known. The macrophage cell line THP1 was stimulated by phorbol myristate acetate (PMA) to secrete exosomes. The exosomes isolated from THP1 were characterized via transmission electron microscopy (TEM), nanoparticle tracking analysis (NTA) and by a western blot. Cell proliferation was determined using CCK-8. A transwell assay and flow cytometry were conducted to detect cell migration and apoptosis, respectively. The expression levels of AKT and its phosphorylation status were determined using a western blot. PMA-treated activated THP1 cells secreted an abundance of exosomes with the characteristics of being less than 200 nm in diameter, and showing the robust expression of exosome markers CD63 and CD81. The THP1-derived exosomes promoted cell proliferation, migration and drug-resistance to the chemical drug docetaxel in both osteosarcoma cell lines MG63 and 143B. The inhibition of the generation of exosomes by the knockdown of ALIX clearly suppressed the cell proliferation, migration and drug-resistance. Mechanistically, the THP1-derived exosomes activated AKT signaling by inducing the increased expression of the phosphorylated AKT at serine 473 (p-AKT). The AKT inhibitor MK2206 significantly abolished exosome-mediated cell proliferation and drug-resistance in osteosarcoma cells. In summary, our data demonstrated that macrophage-derived exosomes promoted osteosarcoma progression and drug-resistance by activating AKT signaling that could be used as a potential molecular target for osteosarcoma treatment.

Osteosarcoma is the most common type of bone tumor, which severely threatens the health of adolescents and young adults.