Alcohol-induced miR-27a regulates differentiation and M2 macrophage polarization of normal human monocytes

A novel experimental model of MetALD in male mice recapitulates key features of severe alcohol-associated hepatitis

BACKGROUND

The recent increase in the incidence of alcohol-associated hepatitis (AH) coincides with the obesity epidemic in the United States. However, current mouse models do not fully replicate the combined insults of obesity, metabolic dysfunction-associated steatohepatitis, and alcohol. The aim of this study was to develop a new mouse model that recapitulates the robust inflammatory and fibrotic phenotype characteristic of human MetALD.

METHODS

Eight- to 10-week-old male C57BL/6 mice were fed chow or high fat-cholesterol-sugar diet (metabolic dysfunction-associated steatohepatitis diet) and in each group, some received alcohol in drinking water (ad libitum) and weekly alcohol binges (EtOH) for 3 months. The liver was assessed for features of AH.

RESULTS

MetALD mice displayed increased liver damage indicated by highly elevated ALT and bilirubin levels compared to all other groups. Liver steatosis was significantly greater in the MetALD mice compared to all other experimental groups. The inflammatory phenotype of MetALD was also recapitulated, including increased IL-6 and IL-1β protein levels as well as increased CD68+ macrophages and Ly6G+ neutrophils in the liver. Sirius red staining and expression of collagen 1, alpha-smooth muscle actin indicated advanced fibrosis in the livers of MetALD mice. In addition, indicators of epithelial-to-mesenchymal transition markers were increased in MetALD mice compared to all other groups. Furthermore, we found increased ductular reaction, dysregulated hedgehog signaling, and decreased liver synthetic functions, consistent with severe AH.

CONCLUSIONS

Alcohol administration in mice combined with metabolic dysfunction-associated steatohepatitis diet recapitulates key characteristics of human AH including liver damage, steatosis, robust systemic inflammation, and liver immune cell infiltration. This model results in advanced liver fibrosis, ductular reaction, decreased synthetic function, and hepatocyte dedifferentiation, suggesting a robust model of MetALD in mice.

miRNAs in patients with alcoholic liver disease: a systematic review and meta-analysis

INTRODUCTION

Alcoholic liver disease (ALD) encompasses a spectrum of liver conditions, including liver steatosis, alcoholic hepatitis (AH), fibrosis, cirrhosis, and hepatocellular carcinoma (HCC). microRNAs (miRNAs) have garnered significant interest as potential biomarkers for ALD.

METHODS

We searched PubMed, Embase, Web of Science and Cochrane Central Register of Controlled Trials (CENTRAL) systemically from inception to June 2024. All extracted data was stratified according to the stages of ALD. The vote-counting strategy performed a meta-analysis on miRNA expression profiles.

RESULTS

We included 40 studies. In serum of individuals with alcohol-use vs. no alcohol-use, miRNA-122 and miRNA-155 were upregulated, and miRNA-146a was downregulated. In patients with ALD vs. healthy controls, miRNA-122 and miRNA-155 were also upregulated and miRNA-146a was downregulated. However, in patients with AH vs. healthy individuals, only the serum miRNA-122 level was upregulated. Due to insufficient data on diagnostic accuracy, we failed to conclude the ability of miRNAs to distinguish different stages of ALD-related liver fibrosis. The results for ALD-related HCC were also insufficient and controversial.

CONCLUSIONS

Circulating miRNA-122 was the most promising biomarker to manage individuals with ALD. More studies were needed for the diagnostic accuracy of miRNAs in ALD.

REGISTRATION

This protocol was registered on the International Prospective Register of Systematic Reviews (PROSPERO) (www.crd.york.ac.uk/prospero/) with registration number CRD42023391931.

Monocytic microRNAs-Novel targets in atherosclerosis therapy

Atherosclerosis is a chronic proinflammatory disease of the vascular wall resulting in narrowing of arteries due to plaque formation, thereby causing reduced blood supply that is the leading cause for diverse end-organ damage with high mortality rates. Monocytes/macrophages, activated by elevated circulating lipoproteins, are significantly involved in the formation and development of atherosclerotic plaques. The imbalance between proinflammatory and anti-inflammatory macrophages, arising from dysregulated macrophage polarization, appears to be a driving force in this process. Proatherosclerotic processes acting on monocytes/macrophages include accumulation of cholesterol in macrophages leading to foam cell formation, as well as dysfunctional efferocytosis, all of which contribute to the formation of unstable plaques. In recent years, microRNAs (miRs) were identified as factors that could modulate monocyte/macrophage function and may therefore interfere with the atherosclerotic process. In this review, we present effects of monocyte/macrophage-derived miRs on atherosclerotic processes in order to reveal new treatment options using miRmimics or antagomiRs.

RNA interference-based therapies for atherosclerosis: Recent advances and future prospects

Atherosclerosis represents a pathological state that affects the arterial system of the organism. This chronic, progressive condition is typified by the accumulation of atheroma within arterial walls. Modulation of RNA molecules through RNA-based therapies has expanded the range of therapeutic options available for neurodegenerative diseases, infectious diseases, cancer, and, more recently, cardiovascular disease (CVD). Presently, microRNAs and small interfering RNAs (siRNAs) are the most widely employed therapeutic strategies for targeting RNA molecules, and for regulating gene expression and protein production. Nevertheless, for these agents to be developed into effective medications, various obstacles must be overcome, including inadequate binding affinity, instability, challenges of delivering to the tissues, immunogenicity, and off-target toxicity. In this comprehensive review, we discuss in detail the current state of RNA interference (RNAi)-based therapies.

MiRNAs in Alcohol-Related Liver Diseases and Hepatocellular Carcinoma: A Step toward New Therapeutic Approaches?

Alcohol-related Liver Disease (ALD) is the primary cause of chronic liver disorders and hepatocellular carcinoma (HCC) development in developed countries and thus represents a major public health concern. Unfortunately, few therapeutic options are available for ALD and HCC, except liver transplantation or tumor resection for HCC. Deciphering the molecular mechanisms underlying the development of these diseases is therefore of major importance to identify early biomarkers and to design efficient therapeutic options. Increasing evidence indicate that epigenetic alterations play a central role in the development of ALD and HCC. Among them, microRNA importantly contribute to the development of this disease by controlling the expression of several genes involved in hepatic metabolism, inflammation, fibrosis, and carcinogenesis at the post-transcriptional level. In this review, we discuss the current knowledge about miRNAs' functions in the different stages of ALD and their role in the progression toward carcinogenesis. We highlight that each stage of ALD is associated with deregulated miRNAs involved in hepatic carcinogenesis, and thus represent HCC-priming miRNAs. By using in silico approaches, we have uncovered new miRNAs potentially involved in HCC. Finally, we discuss the therapeutic potential of targeting miRNAs for the treatment of these diseases.

Characterization of polarization states of canine monocyte derived macrophages

Macrophages can reversibly polarize into multiple functional subsets depending on their micro-environment. Identification and understanding the functionality of these subsets is relevant for the study of immune‑related diseases. However, knowledge about canine macrophage polarization is still in its infancy. In this study, we polarized canine monocytes using GM-CSF/IFN- γ and LPS towards M1 macrophages or M-CSF and IL-4 towards M2 macrophages and compared them to undifferentiated monocytes (M0). Polarized M1 and M2 macrophages were thoroughly characterized for morphology, surface marker features, gene profiles and functional properties. Our results showed that canine M1-polarized macrophages obtained a characteristic large, roundish, or amoeboid shape, while M2-polarized macrophages were smaller and adopted an elongated spindle-like morphology. Phenotypically, all macrophage subsets expressed the pan-macrophage markers CD14 and CD11b. M1-polarized macrophages expressed increased levels of CD40, CD80 CD86 and MHC II, while a significant increase in the expression levels of CD206, CD209, and CD163 was observed in M2-polarized macrophages. RNAseq of the three macrophage subsets showed distinct gene expression profiles, which are closely associated with immune responsiveness, cell differentiation and phagocytosis. However, the complexity of the gene expression patterns makes it difficult to assign clear new polarization markers. Functionally, undifferentiated -monocytes, and M1- and M2- like subsets of canine macrophages can all phagocytose latex beads. M2-polarized macrophages exhibited the strongest phagocytic capacity compared to undifferentiated monocytes- and M1-polarized cells. Taken together, this study showed that canine M1 and M2-like macrophages have distinct features largely in parallel to those of well-studied species, such as human, mouse and pig. These findings enable future use of monocyte derived polarized macrophages particularly in studies of immune related diseases in dogs.

The potential role of miRNA in regulating macrophage polarization

Macrophage polarization is a dynamic process determining the outcome of various physiological and pathological situations through inducing pro-inflammatory responses or resolving inflammation via exerting anti-inflammatory effects. The miRNAs are epigenetic regulators of different biologic pathways that target transcription factors and signaling molecules to promote macrophage phenotype transition and regulate immune responses. Modulating the macrophage activation, differentiation, and polarization by miRNAs is crucial for immune responses in response to microenvironmental signals and under various physiological and pathological conditions. In term of clinical significance, regulating macrophage polarization via miRNAs could be utilized for inflammation control. Also, understanding the role of miRNAs in macrophage polarization can provide insights into diagnostic strategies associated with dysregulated miRNAs and for developing macrophage-centered therapeutic methods. In this case, targeting miRNAs to further regulate of macrophage polarization may become an efficient strategy for treating immune-associated disorders. The current review investigated and categorized various miRNAs directly or indirectly involved in macrophage polarization by targeting different transcription factors and signaling pathways. In addition, prospects for regulating macrophage polarization via miRNA as a therapeutic choice that could be implicated in various pathological conditions, including cancer or inflammation-mediated injuries, were discussed.

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 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.

Mitochondrial Dysfunction: At the Nexus between Alcohol-Associated Immunometabolic Dysregulation and Tissue Injury

Alcohol misuse, directly or indirectly as a result of its metabolism, negatively impacts most tissues, including four with critical roles in energy metabolism regulation: the liver, pancreas, adipose, and skeletal muscle. Mitochondria have long been studied for their biosynthetic roles, such as ATP synthesis and initiation of apoptosis. However, current research has provided evidence that mitochondria participate in myriad cellular processes, including immune activation, nutrient sensing in pancreatic β-cells, and skeletal muscle stem and progenitor cell differentiation. The literature indicates that alcohol impairs mitochondrial respiratory capacity, promoting reactive oxygen species (ROS) generation and disrupting mitochondrial dynamics, leading to dysfunctional mitochondria accumulation. As discussed in this review, mitochondrial dyshomeostasis emerges at a nexus between alcohol-disrupted cellular energy metabolism and tissue injury. Here, we highlight this link and focus on alcohol-mediated disruption of immunometabolism, which refers to two distinct, yet interrelated processes. Extrinsic immunometabolism involves processes whereby immune cells and their products influence cellular and/or tissue metabolism. Intrinsic immunometabolism describes immune cell fuel utilization and bioenergetics that affect intracellular processes. Alcohol-induced mitochondrial dysregulation negatively impacts immunometabolism in immune cells, contributing to tissue injury. This review will present the current state of literature, describing alcohol-mediated metabolic and immunometabolic dysregulation from a mitochondrial perspective.

miR-27a-5p inhibits acute rejection of liver transplantation in rats by inducing M2 polarization of Kupffer cells through the PI3K/Akt pathway

Liver transplantation (LT), a major therapy for end-stage liver disease, is often associated with acute rejection (AR). MicroRNAs (miRNAs) have been implicated in AR-related gene regulation. In this experiment, the mechanism of miR-27a-5p in AR of LT was studied. Allotransplantation model (LEW-BN) and syngeneic transplantation model (LEW-LEW) of rat orthotopic liver transplantation (OLT) were established. miR-27a-5p was overexpressed in recipient rats 28 days before LT to detect its effects on LT pathology, liver function, and survival time. Kupffer cells (KCs) were isolated and treated with lipopolysaccharide (LPS) and miR-27a-5p overexpression. miR-27a-5p overexpression reduced lymphocyte numbers around portal areas and central veins after LT and mitigated degeneration of epithelial cells of the bile duct. Expression levels of IL-10 and TGF-β1 were increased while IL-12 was decreased. Liver function damage was alleviated and the survival time of rats with LT was prolonged. miR-27a-5p induced M2 polarization of rats with AR after LT and LPS-treated KCs in vitro and promoted activation of the PI3K/Akt pathway in KCs. Inhibition of the PI3K/Akt pathway averted induction of miR-27a-5p on M2 polarization of KCs. Taken together, miR-27a-5p inhibited AR after LT in rats by inducing M2 polarization of KCs through the PI3K/Akt pathway.

The neuroimmune system - Where aging and excess alcohol intersect

As the percentage of the global population over age 65 grows, and with it a subpopulation of individuals with alcohol use disorder (AUD), understanding the effect of alcohol on the aged brain is of utmost importance. Neuroinflammation is implicated in both natural aging as well as alcohol use, and its role in alterations to brain morphology and function may be exacerbated in aging individuals who drink alcohol to excess. The neuroimmune response to alcohol in aging is complex. The few studies investigating this issue have reported heightened basal activity and either hypo- or hyper-reactivity to an alcohol challenge. This review of preclinical research will first introduce key players of the immune system, then explore changes in neuroimmune function with aging or alcohol alone, with discussion of vulnerable brain regions, changes in cytokines, and varied reactions of microglia and astrocytes. We will then consider different levels of alcohol exposure, relevant animal models of AUD, and neuroimmune activation by alcohol across the lifespan. By identifying key findings, challenges, and targets for future research, we hope to bring more attention and resources to this underexplored area of inquiry.

Extracellular Vesicles and Fatty Liver

Fatty liver is a complex pathological process caused by multiple etiologies. In recent years, the incidence of fatty liver has been increasing year by year, and it has developed into a common chronic disease that seriously affects people's health around the world. It is an important risk factor for liver cirrhosis, liver cancer, and a variety of extrahepatic chronic diseases. Therefore, the early diagnosis and early therapy of fatty liver are important. Except for invasive liver biopsy, there is still a lack of reliable diagnosis and staging methods. Extracellular vesicles are small double-layer lipid membrane vesicles derived from most types of cells. They play an important role in intercellular communication and participate in the occurrence and development of many diseases. Since extracellular vesicles can carry a variety of biologically active substances after they are released by cells, they have received widespread attention. The occurrence and development of fatty liver are also closely related to extracellular vesicles. In addition, extracellular vesicles are expected to provide a new direction for the diagnosis of fatty liver. This article reviews the relationship between extracellular vesicles and fatty liver, laying a theoretical foundation for the development of new strategies for the diagnosis and therapy of fatty liver.

CD34+CD10+CD19− Cells in Patients with Unhealthy Alcohol Use Stimulate the M2b Monocyte Polarization

M2b monocytes commonly isolated from patients with unhealthy alcohol use (Alc) have been described as cells that make the host susceptible to opportunistic infections. CD34⁺CD10⁺CD19⁻ cells are multilineage progenitors of CD19⁺ cells, and we show that the effect of these cells from the peripheral blood on M2b monocyte polarization differed between healthy donors and Alc in this study. In healthy donors, these cells consistently differentiated into high-mobility group box-1 (HMGB1)-nonproducing cells (CD19⁺ cells) in response to retinoic acid (RA). However, owing to the lack of expression of RA receptor (RAR), these cells from Alc failed to differentiate into CD19⁺ cells under the same RA stimulation. Conditioned medium (CM) of these cells from Alc induced the polarization of M2b monocytes, which increases the susceptibility of hosts to opportunistic infections in Alc. When the alcoholic individuals were subjected to 2 weeks of abstinence from alcohol, these cells from Alc recovered their RAR expression and differentiated into CD19⁺ cells. Moreover, the CM of these cells from Alc after abstinence lost its ability to induce M2b monocyte polarization. These results indicate that these cells from Alc have different properties from those of healthy donors. In Alc, these cells without RAR stimulate M2b monocyte polarization through the production of HMGB1.

Intercellular communication in the tumour microecosystem: Mediators and therapeutic approaches for hepatocellular carcinoma

Hepatocellular carcinoma (HCC), one of the most common tumours worldwide, is one of the main causes of mortality in cancer patients. There are still numerous problems hindering its early diagnosis, which lead to late patients receiving treatment, and these problems need to be solved urgently. The tumour microecosystem is a complex network system comprising seven parts: the hypoxia niche, immune microenvironment, metabolic microenvironment, acidic niche, innervated niche, mechanical microenvironment, and microbial microenvironment. Intercellular communication is divided into direct contact and indirect communication. Direct contact communication includes gap junctions, tunneling nanotubes, and receptor-ligand interactions, whereas indirect communication includes exosomes, apoptotic vesicles, and soluble factors. Mechanical communication and cytoplasmic exchange are further means of intercellular communication. Intercellular communication mediates the crosstalk between the tumour microecosystem and the host as well as that between cells and cell-free components in the tumour microecosystem, causing changes in the tumour hallmarks of the HCC microecosystem such as changes in tumour proliferation, invasion, apoptosis, angiogenesis, metastasis, inflammatory response, gene mutation, immune escape, metabolic reprogramming, and therapeutic resistance. Here, we review the role of the above-mentioned intercellular communication in the HCC microecosystem and discuss the advantages of targeted intercellular communication in the clinical diagnosis and treatment of HCC. Finally, the current problems and prospects are discussed.

Role of Exosomes in Chronic Liver Disease Development and Their Potential Clinical Applications

Extracellular vesicles (EVs) are vesicular bodies (40-1000 nm) with double-layer membrane structures released by different cell types into extracellular environments, including apoptosis bodies, microvesicles, and exosomes. Exosomes (30-100 nm) are vesicles enclosed by extracellular membrane and contain effective molecules of secretory cells. They are derived from intracellular multivesicular bodies (MVBs) that fuse with the plasma membrane and release their intracellular vesicles by exocytosis. Research has shown that almost all human cells could secrete exosomes, which have a certain relationship with corresponding diseases. In chronic liver diseases, exosomes release a variety of bioactive components into extracellular spaces, mediating intercellular signal transduction and materials transport. Moreover, exosomes play a role in the diagnosis, treatment, and prognosis of various chronic liver diseases as potential biomarkers and therapeutic targets. Previous studies have found that mesenchymal stem cell-derived exosomes (MSC-ex) could alleviate acute and chronic liver injury and have the advantages of high biocompatibility and low immunogenicity. In this paper, we briefly summarize the role of exosomes in the pathogenesis of different chronic liver diseases and the latest research progresses of MSC-ex as the clinical therapeutic targets.

Pathogenic role of microRNAs in atherosclerotic ischemic stroke: Implications for diagnosis and therapy

Ischemic stroke resulting from atherosclerosis (particularly in the carotid artery) is one of the major subtypes of stroke and has a high incidence of death. Disordered lipid homeostasis, lipid deposition, local macrophage infiltration, smooth muscle cell proliferation, and plaque rupture are the main pathological processes of atherosclerotic ischemic stroke. Hepatocytes, macrophages, endothelial cells and vascular smooth muscle cells are the main cell types participating in these processes. By inhibiting the expression of the target genes in these cells, microRNAs play a key role in regulating lipid disorders and atherosclerotic ischemic stroke. In this article, we listed the microRNAs implicated in the pathology of atherosclerotic ischemic stroke and aimed to explain their pro- or antiatherosclerotic roles. Our article provides an update on the potential diagnostic use of miRNAs for detecting growing plaques and impending clinical events. Finally, we provide a perspective on the therapeutic use of local microRNA delivery and discuss the challenges for this potential therapy.

Pathological Contribution of Extracellular Vesicles and Their MicroRNAs to Progression of Chronic Liver Disease

Simple Summary

Extracellular vesicles (EVs) are membrane-enclosed vesicles secreted from most types of cells. EVs encapsulate many diverse bioactive cargoes, such as proteins and nucleic acid, of parental cells and delivers them to recipient cells. Upon injury, the contents altered by cellular stress are delivered into target cells and affect their physiological properties, spreading the disease microenvironment to exacerbate disease progression. Therefore, EVs are emerging as good resources for studying the pathophysiological mechanisms of diseases because they reflect the characteristics of donor cells and play a central role in intercellular communication. Chronic liver disease affects millions of people worldwide and has a high mortality rate. In chronic liver disease, the production and secretion of EVs are significantly elevated, and increased and altered cargoes are packed into EVs, enhancing inflammation, fibrosis, and angiogenesis. Herein, we review EVs released under specific chronic liver disease and explain how EVs are involved in intercellular communication to aggravate liver disease.

Abstract

Extracellular vesicles (EVs) are membrane-bound endogenous nanoparticles released by the majority of cells into the extracellular space. Because EVs carry various cargo (protein, lipid, and nucleic acids), they transfer bioinformation that reflects the state of donor cells to recipient cells both in healthy and pathologic conditions, such as liver disease. Chronic liver disease (CLD) affects numerous people worldwide and has a high mortality rate. EVs released from damaged hepatic cells are involved in CLD progression by impacting intercellular communication between EV-producing and EV-receiving cells, thereby inducing a disease-favorable microenvironment. In patients with CLD, as well as in the animal models of CLD, the levels of released EVs are elevated. Furthermore, these EVs contain high levels of factors that accelerate disease progression. Therefore, it is important to understand the diverse roles of EVs and their cargoes to treat CLD. Herein, we briefly explain the biogenesis and types of EVs and summarize current findings presenting the role of EVs in the pathogenesis of CLD. As the role of microRNAs (miRNAs) within EVs in liver disease is well documented, the effects of miRNAs detected in EVs on CLD are reviewed. In addition, we discuss the therapeutic potential of EVs to treat CLD.

Epigenetics of alcohol-related liver diseases

Alcohol-related liver disease (ARLD) is a primary cause of chronic liver disease in the United States. Despite advances in the diagnosis and management of ARLD, it remains a major public health problem associated with significant morbidity and mortality, emphasising the need to adopt novel approaches to the study of ARLD and its complications. Epigenetic changes are increasingly being recognised as contributing to the pathogenesis of multiple disease states. Harnessing the power of innovative technologies for the study of epigenetics (e.g., next-generation sequencing, DNA methylation assays, histone modification profiling and computational techniques like machine learning) has resulted in a seismic shift in our understanding of the pathophysiology of ARLD. Knowledge of these techniques and advances is of paramount importance for the practicing hepatologist and researchers alike. Accordingly, in this review article we will summarise the current knowledge about alcohol-induced epigenetic alterations in the context of ARLD, including but not limited to, DNA hyper/hypo methylation, histone modifications, changes in non-coding RNA, 3D chromatin architecture and enhancer-promoter interactions. Additionally, we will discuss the state-of-the-art techniques used in the study of ARLD (e.g. single-cell sequencing). We will also highlight the epigenetic regulation of chemokines and their proinflammatory role in the context of ARLD. Lastly, we will examine the clinical applications of epigenetics in the diagnosis and management of ARLD.

The Gut-Liver Axis in Chronic Liver Disease: A Macrophage Perspective

Chronic liver disease (CLD) is a growing health concern which accounts for two million deaths per year. Obesity, alcohol overconsumption, and progressive cholestasis are commonly characterized by persistent low-grade inflammation and advancing fibrosis, which form the basis for development of end-stage liver disease complications, including hepatocellular carcinoma. CLD pathophysiology extends to the intestinal tract and is characterized by intestinal dysbiosis, bile acid dysregulation, and gut barrier disruption. In addition, macrophages are key players in CLD progression and intestinal barrier breakdown. Emerging studies are unveiling macrophage heterogeneity and driving factors of their plasticity in health and disease. To date, in-depth investigation of how gut-liver axis disruption impacts the hepatic and intestinal macrophage pool in CLD pathogenesis is scarce. In this review, we give an overview of the role of intestinal and hepatic macrophages in homeostasis and gut-liver axis disruption in progressive stages of CLD.

Epigenetic regulation of immunosuppressive tumor-associated macrophages through dysregulated microRNAs

Macrophages are immune cells that play different roles under different physiological conditions. They are present in all tissues where they primarily protect from bacteria and pathogens in addition to assisting in tissue repair. During tumor progression, macrophages can exert contrasting effects based on the M1 vs. M2 polarization. The M2 macrophages support tumor growth through mechanisms that help suppress immune responses and/or circumvent immune-surveillance. A number of such mechanisms such as production of IL-10 and arginase, and expression of PD-L1, V-domain Ig suppressor of T cell activation and B7 family molecule B7-H4 are now believed central to the immunosuppressive effects of tumor-associated macrophages (TAMs). Emerging data has identified epigenetic regulation of these immunosuppressive mechanisms by small non-coding RNAs, the microRNAs (miRNAs). This review discusses the available literature on the subject, including the exosomes mediated transfer of miRNAs between cancer cells and the macrophages within the tumor microenvironment. A number of miRNAs are now believed to be involved in TAMs' production of IL-10 and expression of PD-L1 while the information on such regulation of other immunosuppressive mechanisms is slowly emerging. A better understanding of epigenetic regulation of macrophages-mediated immunosuppressive effect can help identify novel targets for therapy and aid the design of future studies aimed at sensitizing tumors to immune responses.

A mouse model of the regression of alcoholic hepatitis: Monitoring the regression of hepatic steatosis, inflammation, oxidative stress, and NAD+ metabolism upon alcohol withdrawal

This study aimed to develop a well-characterized mouse model of alcoholic hepatitis (AH) regression. Male C57BL/6J mice were fed a Lieber-DeCarli (LD) control diet or LD containing 5% ethanol for ten days followed by one binge, which is the chronic-binge model of AH developed by the National Institute on Alcohol Abuse and Alcoholism. To determine AH regression, mice previously exposed to ethanol were put on LD control diet and metabolic and inflammatory features were monitored weekly for three weeks. Serum alcohol, total cholesterol, and alanine transaminase levels were increased in ethanol-fed mice, which declined to those of no ethanol controls within one and three weeks after ethanol withdrawal, respectively. Serum malondialdehyde was increased with ethanol feeding, but it was restored to no ethanol control levels within one week. Ethanol-induced changes in the hepatic expression of genes involved in lipogenesis, fatty acid oxidation, ethanol metabolism, and antioxidant response were restored to those of no ethanol controls after 3 weeks of ethanol withdrawal. Also, ethanol-induced hepatic inflammation was gradually decreased during the 3 weeks of ethanol withdrawal. Hepatic nicotinamide adenine dinucleotide (NAD⁺) levels and the expression of enzymes involved in the NAD⁺ salvage pathway were decreased by ethanol feeding, which was mitigated after ethanol withdrawal. Ethanol significantly lowered hepatic sirtuin 1 expression, but its levels were restored with ethanol cessation. This study established a mouse model of AH regression, which can be used as a preclinical model to study the potential of dietary bioactives or therapeutic agents on AH regression.

Nicotinamide riboside, an NAD+ precursor, attenuates inflammation and oxidative stress by activating sirtuin 1 in alcohol-stimulated macrophages

Macrophages play an essential role in alcohol-induced inflammation and oxidative stress. We investigated the effects of nicotinamide riboside (NR), a natural nicotinamide adenine dinucleotide (NAD+) precursor, on alcohol-induced inflammation and oxidative stress in macrophages. NR significantly decreased ethanol-induced inflammatory gene expression, with a concomitant decrease in nuclear translocation of nuclear factor κB p65 in RAW 264.7 macrophages and mouse bone marrow-derived macrophages (BMDMs). In macrophages incubated with ethanol or acetaldehyde, NR abolished the accumulation of cellular reactive oxygen species. Ethanol decreased sirtuin 1 (SIRT1) expression and activity, and cellular NAD+ level while inducing pro-inflammatory gene expression. However, NR markedly attenuated the changes. SIRT1 inhibition augmented ethanol-induced inflammatory gene expression, but its activation elicited opposing effects. Also, ethanol did not alter glycolysis but increased glycolytic capacity, glycolytic reserve, and non-glycolytic acidification, with concomitant increases in hypoxia-induced factor 1α expression and activity, phosphorylation of pyruvate dehydrogenase, and extracellular lactate levels. Interestingly, ethanol increased mitochondrial respiration and ATP production but decreased maximal respiration and spare respiration capacity. The latter was linked to decreases in mitochondrial copy numbers. NR abolished the ethanol-induced metabolic changes in the glycolytic and oxidative phosphorylation pathways in RAW 264.7 macrophages. In conclusion, NR exerts anti-inflammatory and antioxidant properties by abrogating the inhibitory effects of ethanol on the SIRT1 pathway by increasing Sirt1 expression and its activator, NAD+. Also, SIRT1 activation and normalization of ethanol-induced changes in NAD+/NADH ratios by NR are likely crucial to counteract the changes in energy phenotypes of macrophages exposed to ethanol.

Melanoidins, extracted from Chinese traditional vinegar powder, inhibit alcohol-induced inflammation and oxidative stress in macrophages via activation of SIRT1 and SIRT3

Alcohol induces inflammation and oxidative stress with the dysregulation of proinflammatory cytokines, which are implicated in the pathogenesis of alcoholic liver injury. Melanoidins are known to exert an antioxidant effect, however, their function in inhibiting alcohol-induced inflammation is unclear. In this study, we examined the role of melanoidins from Chinese traditional vinegar powder in terms of their anti-inflammatory and antioxidant properties in RAW 264.7 macrophages and elucidated their mechanisms of function. In macrophages, melanoidins significantly suppress the mRNA expression of interleukin (Il)-6, Il-1β and tumor necrosis factor α (Tnf-α) with a concomitant inhibitory effect on IL-1β, IL-6 and TNFα secretion, which are increased by ethanol. In addition, ethanol significantly increases the cellular reactive oxygen species (ROS) levels and the expression of cytochrome β-245 and beta polypeptide (Cybb), which are repressed by melanoidins to basal level. However, the expression of genes related to oxidative stress significantly decreases in response to ethanol, while it is significantly increased by melanoidins. Importantly, treatment with ethanol led to significant decreases in SIRT1 and SIRT3 transcription, translation, and activation, as well as the nicotinamide adenine dinucleotide (NAD⁺) levels. Interestingly, all the decreases were markedly attenuated by melanoidins. Ethanol promoted the expression of proinflammatory genes, whereas coincubation with resveratrol (a potent SIRT agonist) inhibited this effect. Conversely, the addition of sirtinol (a known SIRT inhibitor) augmented the proinflammatory gene expression. Taken together, our findings suggest that melanoidins exert anti-inflammatory and antioxidant functions via abolishing decreases in SIRT1 and SIRT3 expression and cellular NAD⁺ levels in ethanol-induced macrophages and may serve as a new therapeutic agent for the prevention of alcohol-induced cell damage.

Alpha defensin-1 attenuates surgically induced osteoarthritis in association with promoting M1 to M2 macrophage polarization

OBJECTIVE

Macrophages play an important part in the pathogenesis of osteoarthritis (OA). Our objective was to determine the effects of α-defensin-1 on macrophage polarization and consequently OA.

METHODS

OA synovial tissue and synovial fluid were assessed for the presence of M1 (CD68⁺CD16⁺CD206^-) and M2 (CD68⁺CD206⁺CD16^-) macrophages by flow cytometry. M0, M1, and M2 macrophages were co-cultured with OA chondrocytes to determine their influence on chondrogenic phenotype. Polarization of THP-1 activated monocytes from M1 to M2 in response to α-defensin-1 was evaluated by flow cytometry, RT-PCR and RNA sequencing. Effects of intra-articular α-defensin-1 in vivo were evaluated in a rat meniscal/ligamentous injury (MLI) model.

RESULTS

The quantity of M1 exceeded M2 polarized macrophages in human OA synovial tissue (mean difference 26.1% [13.6-38.6%], P < 0.001) and fluid (mean difference 10.5% [5.0-16.1%], P = 0.003). M1 to M2 polarization in vitro was most effectively promoted with 10 ng/mL α-defensin-1. Compared with untreated macrophages, the α-defensin-1 polarized macrophages modified co-cultured OA chondrocytes from a pro-catabolic state to a pro-anabolic (regenerative-like) state based on expression of COL2A1, ACN, MMP3, MMP13 and ADAMTS5. Intra-articular α-defensin-1 decreased severity of cartilage damage and synovitis in the MLI rat model. RNAseq analyses suggested insulin and Toll-like receptor signaling pathways in the chondroprotective α-defensin-1 mechanism of action.

CONCLUSION

α-defensin-1 promotes M1 to M2 macrophage polarization in vitro, has beneficial effects on chondrocytes indirectly via M2 macrophage polarization, and attenuates the severity of OA in vivo, suggesting it might be a candidate treatment for OA.

Mesenchymal Stem Cell-Derived Extracellular Vesicles Alleviate Acute Lung Injury Via Transfer of miR-27a-3p

OBJECTIVES

The goal of this study was to determine the role of microRNA transfer in mediating the effects of mesenchymal stem cell-derived extracellular vesicles in acute lung injury.

DESIGN

Experimental cell and animal studies.

SETTING

University-based research laboratory.

SUBJECTS

THP-1 monocytes, bone marrow-derived macrophages, and C57BL/6 mice.

INTERVENTIONS

To determine the microRNA transfer in vitro, mesenchymal stem cells and mesenchymal stem cell-derived extracellular vesicles were cultured with THP-1 cells and bone marrow-derived macrophages and then assayed for microRNA expression in the target cells. To examine the role of microRNA transfer in vivo, mesenchymal stem cell-derived extracellular vesicles were administered to mice with lipopolysaccharide-induced lung injury.

MEASUREMENTS AND MAIN RESULTS

Mesenchymal stem cell-derived extracellular vesicles were efficiently taken up by macrophages in vitro and in vivo. miR-27a-3p was one of the most highly expressed microRNAs in THP-1 cells in microarray analysis and was transferred from mesenchymal stem cells and mesenchymal stem cell-derived extracellular vesicles to THP-1/bone marrow-derived macrophages. Mesenchymal stem cell-derived extracellular vesicles promoted M2 polarization in bone marrow-derived macrophages, which was inhibited by lentiviral anti-miR-27a-3p transduction. Mesenchymal stem cell-derived extracellular vesicles administered systemically and intratracheally were as effective as mesenchymal stem cells in alleviating acute lung injury, elevating miR-27a-3p levels in alveolar macrophages, and promoting M2 macrophage polarization. Treatment of mesenchymal stem cell-derived extracellular vesicles concurrently decreased alveolar macrophage expression of nuclear factor kappa B subunit 1, a target of miR-27a-3p. Lentiviral transduction of mesenchymal stem cells with anti-miR-27a-3p or knockdown of miR-27a-3p in vivo abolished the effects of mesenchymal stem cell-derived extracellular vesicles on acute lung injury and M2 macrophage polarization.

CONCLUSIONS

Mesenchymal stem cell-derived extracellular vesicles mitigate acute lung injury at least partially via transferring miR-27a-3p to alveolar macrophages. miR-27a-3p acts to target NFKB1 and is a crucial regulator of M2 macrophage polarization.

Alcohol-Related Liver Disease: Basic Mechanisms and Clinical Perspectives

Alcohol-related liver disease (ALD) refers to the liver damage occurring due to excessive alcohol consumption and involves a broad spectrum of diseases that includes liver steatosis, steatohepatitis, hepatitis, cirrhosis, and hepatocellular carcinoma (HCC). The progression of ALD is mainly associated with the amount and duration of alcohol usage; however, it is also influenced by genetic, epigenetic, and environmental factors. The definite diagnosis of ALD is based on a liver biopsy, although several non-invasive diagnostic tools and serum biomarkers have emerging roles in the early detection of ALD. While alcohol abstinence and nutritional support remain the cornerstone of ALD treatment, growing evidence has revealed that the therapeutic agents that target oxidative stress or gut-liver axis, inflammatory response inhibition, and liver regeneration enhancement also play a role in ALD management. Furthermore, microRNAs modulation and mesenchymal stem cell-based therapy have emerging potential as ALD therapeutic options. This review summarizes the updated understanding of the pathophysiology, diagnosis, and novel therapeutic approaches for ALD.

Ethanol modulates the effector functions of human monocyte-derived macrophages in response to Paracoccidioides brasiliensis yeast cells

We aimed to investigate the effects of ethanol and its metabolites (β-hydroxybutyrate and sodium acetate) in the effector functions of macrophages in response to Paracoccidioides brasiliensis yeast cells and to determine their influence in the development of the adaptive response. Purified peripheral blood monocytes were differentiated into macrophages and were treated with ethanol, β-hydroxybutyrate, and sodium acetate, and stimulated with P. brasiliensis yeast cells and evaluated for their phenotypic characteristics, functional activity, and capability to induce T cells activation/differentiation. We found that the ethanol treatment diminished the expression of HLA-AB, HLA-DR, CD80, and CD86, modulating the expression of dectin-1, as well as Syk phosphorylation. The ethanol treatment increased the phagocytic activity, expression of CD206, and IL-10 production; however, reduced ROS production, fungicidal activity, caspase-1 cleavage, and IL-1β and IL-6 production. Our data also showed that the presence of ethanol reduced the differentiation of Th1 and Th17 cells and increased the frequency of Th2 cells. Our results indicated that ethanol exposure could suppress effector function of macrophages, possibly leading to the polarization of M2 macrophages. The ethanol modulates the expression of costimulatory and antigen-presentation molecules and interferes with the NLRP3 inflammasome. Altogether, these alterations affect the development of the adaptive response, decreasing the frequency of IL-17, IL-22, and IFN- γ producing cells, and increasing the frequency of IL-4 producing cells. Therefore, exposure to ethanol can impair the capability of macrophages to exert their effector functions and activate the acquired response related to resistance to P. brasiliensis infection.

Role of autophagy in regulating interleukin-10 and the responses to corticosteroids and statins in asthma

BACKGROUND

Interleukin (IL)-10 is a key anti-inflammatory cytokine that may be reduced in asthma but is enhanced by corticosteroids, especially when combined with a statin, although the mechanisms of these effects are uncertain.

OBJECTIVE

To study the role of autophagy in macrophages in promoting inflammation in asthma through reducing IL-10 secretion and how corticosteroids and statins may reverse this process.

METHODS

We conducted a randomised double-blind placebo-controlled study in moderate to severe asthmatic patients (n = 44) to investigate the effect of an inhaled corticosteroid (budesonide 400 μg/day) and the combination of budesonide with an oral statin (simvastatin 10 mg/day) given for 8 weeks on autophagy protein expression in sputum cells by using immunocytochemistry and measurement of IL-10 release. In in vitro experiments, we studied cross-regulation between autophagy and IL-10 release by measuring the expression of autophagy proteins in M2-like macrophages and the effects of budesonide and simvastatin on these mechanisms.

RESULTS

In asthmatic patients, inhaled budesonide inhibited airway macrophage autophagy (beclin-1, LC3) as well as autophagic flux (p62), which was enhanced by simvastatin and was correlated with increased sputum IL-10 and reduced IL-4 concentrations. In macrophages in vitro, budesonide and simvastatin inhibited rapamycin-induced autophagy as well as autophagic flux, with reduced expression of beclin-1 and LC3, but enhanced the accumulation of p62 and increased expression of IL-10, which itself further inhibited autophagy in macrophages. With siRNA-mediated silencing, LC3-deficient macrophages also showed a maximal induction of IL-10 transcription. Neutralisation of IL-10 with recombinant specific blocking antibody and silencing IL-10 transcription reversed the inhibitory effects of budesonide and simvastatin on macrophage autophagy.

CONCLUSION AND CLINICAL RELEVANCE

Inhibition by corticosteroids and a statin of macrophage autophagy enhances IL-10 production, resulting in the control of asthmatic inflammation.

Implications for MicroRNA involvement in the prognosis and treatment of atherosclerosis

MicroRNAs (miRNAs) are important molecules which implicated in various processes, such as differentiation, development, cell survival, cell apoptosis and also cell metabolism. Investigations over decades have revealed that various genes and signaling pathways are implicated in beginning and development of atherosclerosis, several miRNAs being involved in these dysregulated genes and pathways. miRNAs have provided new molecular vision in the context of atherosclerosis. miRNAs are considered as important regulators of cellular migration, differentiation, proliferation, lipid uptake and efflux, as well as cytokine production. Application of miRNAs as a biomarker in diagnosis, prognosis and even therapy is quiet exciting. Although animal researches showed promising results, still some practical difficulties and technical challenges need to be addressed before translation from researches into clinical practices. In this review, we present important data about three critical cells endothelial cell (EC), vascular smooth muscle cell (VSMC), and monocyte/macrophage and regulation of these cells through miRNAs. Furthermore, we discuss about the potential of miRNAs as a prognostic and diagnostic biomarkers, therapeutic opportunities and challenges, and also future perspective.

The miR-23a∼27a∼24-2 microRNA Cluster Promotes Inflammatory Polarization of Macrophages

Macrophages are critical for regulating inflammatory responses. Environmental signals polarize macrophages to either a proinflammatory (M1) state or an anti-inflammatory (M2) state. We observed that the microRNA (miRNA) cluster mirn23a, coding for miRs-23a, -27a, and -24-2, regulates mouse macrophage polarization. Gene expression analysis of mirn23a-deficient myeloid progenitors revealed a decrease in TLR and IFN signaling. Mirn23a ^-/- bone marrow-derived macrophages (BMDMs) have an attenuated response to LPS, demonstrating an anti-inflammatory phenotype in mature cells. In vitro, mirn23a^-/- BMDMs have decreased M1 responses and an enhanced M2 responses. Overexpression of mirn23a has the opposite effect, enhancing M1 and inhibiting M2 gene expression. Interestingly, expression of mirn23a miRNAs goes down with inflammatory stimulation and up with anti-inflammatory stimulation, suggesting that its regulation prevents locking macrophages into polarized states. M2 polarization of tumor-associated macrophages (TAMs) correlates with poor outcome for many tumors, so to determine if there was a functional consequence of mirn23a loss modulating immune cell polarization, we assayed syngeneic tumor growth in wild-type and mirn23a ^-/- mice. Consistent with the increased anti-inflammatory/immunosuppressive phenotype in vitro, mirn23a ^-/- mice inoculated with syngeneic tumor cells had worse outcomes compared with wild-type mice. Coinjecting tumor cells with mirn23a ^-/- BMDMs into wild-type mice phenocopied tumor growth in mirn23a ^-/- mice, supporting a critical role for mirn23a miRNAs in macrophage-mediated tumor immunity. Our data demonstrate that mirn23a regulates M1/M2 polarization and suggests that manipulation of mirn23a miRNA can be used to direct macrophage polarization to drive a desired immune response.

Harnessing noncoding RNA-based macrophage polarization: Emerging therapeutic opportunities for fibrosis

Aim

Organ fibrosis is a common pathological outcome of persistent tissue injury correlated with organ failure and death. Although current antifibrotic therapies have led to unprecedented successes, only a minority of patients with fibrosis benefit from these treatments. There is an urgent need to identify new targets and biomarkers that could be exploited in the diagnosis and treatment of fibrosis.

Methods

Macrophages play a dual role in the fibrogenesis across different organs either by promoting pro‐inflammatory or anti‐inflammatory responses. Noncoding RNAs (ncRNAs) have been demonstrated to play key roles in macrophage functions by manipulating macrophage polarization. Therefore, understanding the mechanism of ncRNA‐associated macrophage polarization is important to move toward therapeutic interventions.

Results

In this review, we provide an overview of recent insights into the role of ncRNAs in different fibrotic diseases by modulating macrophage phenotypic plasticity and functional heterogeneity. We also discuss the potential mechanisms of different ncRNAs integrate heterogeneous macrophages in fibrogenesis,including regulatory signatures, networks, and reciprocal interactions.

Conclusions

A broader understanding of how ncRNA‐directed macrophage phenotype transition in immunity and fibrosis might promote the development of a novel strategy for antifibrotic treatment.

Inhibition of alcohol-induced inflammation and oxidative stress by astaxanthin is mediated by its opposite actions in the regulation of sirtuin 1 and histone deacetylase 4 in macrophages

We previously demonstrated that astaxanthin (ASTX), a xanthophyll carotenoid, repressed ethanol-induced inflammation and oxidative stress in macrophages. We explored the role of sirtuin 1 (SIRT1) and histone deacetylase 4 (HDAC4) in the inhibitory effect of ASTX on inflammation and oxidative stress in macrophages exposed to ethanol. Ethanol decreased mRNA and protein of SIRT1 while increasing those of HDAC4, which was attenuated by ASTX in RAW 264.7 macrophages and mouse bone marrow-derived macrophages (BMDMs). Inhibition of SIRT1 expression or activity augmented ethanol-induced Hdac4 expression, but SIRT1 activation elicited the opposite effect. Consistently, Hdac4 knockdown increased Sirt1 expression with decreases in ethanol-induced inflammatory gene expression, but its overexpression resulted in the opposite effects. Furthermore, BMDMs from mice with macrophage specific-deletion of Hdac4 (Hdac4^MKO) showed significant decreases in ethanol-induced inflammatory genes and ROS accumulation but an increase in Sirt1 expression. Macrophage specific deletion of Hdac4 or ASTX abolished the changes in genes for mitochondrial biogenesis and glycolysis by ethanol. Ethanol increased mitochondrial respiration, ATP production, and proton leak, but decreased maximal respiration and spare respiratory capacity, all of which were abolished by ASTX in RAW 264.7 macrophages. The ethanol-induced alterations in mitochondrial respiration were abrogated in Hdac4^MKO BMDMs. In conclusion, the anti-inflammatory and antioxidant properties of ASTX in ethanol-treated macrophages may be mediated, at least partly, by its opposite effect on SIRT1 and HDAC4 to empower SIRT1 to counteract ethanol-induced activation of HDAC4.

Mesenchymal stem cell-derived extracellular vesicles alter disease outcomes via endorsement of macrophage polarization

Mesenchymal stem cells (MSCs) are adult stromal cells that reside in virtually all postnatal tissues. Due to their regenerative and immunomodulatory capacities, MSCs have attracted growing attention during the past two decades. MSC-derived extracellular vesicles (MSC-EVs) are able to duplicate the effects of their parental cells by transferring functional proteins and genetic materials to recipient cells without cell-to-cell contact. MSC-EVs also target macrophages, which play an essential role in innate immunity, adaptive immunity, and homeostasis. Recent studies have demonstrated that MSC-EVs reduce M1 polarization and/or promote M2 polarization in a variety of settings. In this review, we discuss the mechanisms of macrophage polarization and roles of MSC-EV-induced macrophage polarization in the outcomes of cardiovascular, pulmonary, digestive, renal, and central nervous system diseases. In conclusion, MSC-EVs may become a viable alternative to MSCs for the treatment of diseases in which inflammation and immunity play a critical role.

Marine-inspired molecular mimicry generates a drug-free, but immunogenic hydrogel adhesive protecting surgical anastomosis

Herein, we report the synthesis of a biomimic hydrogel adhesive that addresses the poor healing of surgical anastomosis. Dopamine-conjugated xanthan gum (Da-g-Xan) is fabricated using deep insights into the molecular similarity between mussels' adhesive and dopamine as well as the structural similarity between barnacle cement proteins and xanthan gum. The hydrogel mimics marine animals’ adherence to wet tissue surfaces. Upon applying this adhesive to colonic anastomosis in a rat model, protective effects were shown by significantly improving the bursting pressure. Mechanistically, the architecture of Da-g-Xan hydrogel is maintained by dynamic intermolecular hydrogen bonds that allow the quick release of Da-g-Xan. The free Da-g-Xan can regulate the inflammatory status and induce type 2 macrophage polarization (M2) by specifically interacting with mannose receptors (CD206) revealed by RNA-sequencing and molecular binding assays. Consequently, an appropriate microenvironment for tissue healing is created by the secretion of chemokines and growth factors from M2 macrophages, strengthening the fibroblast migration and proliferation, collagen synthesis and epithelial vascularization. Overall, this study demonstrates an unprecedented strategy for generating an adhesive by synergistic mimicry inspired by two marine animals, and the results show that the Da-g-Xan adhesive augments native tissue regenerative responses, thus enabling enhanced recovery following surgical anastomosis.

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Dual-biomimic conjugates, Da-g-Xan, are synthesized.

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Da-g-Xan adhesive hydrogels are degradable, self-healing, and injectable.

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Released Da-g-Xan induces type 2 macrophage polarizations by specifically interacting with mannose receptors.

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Paracrine action by the type 2 macrophage polarizations promotes the surgical anastomosis healing.

Sprouty2 Inhibits Migration and Invasion of Fibroblast-Like Synoviocytes in Rheumatoid Arthritis by Down-regulating ATF2 Expression and Phosphorylation

Activating transcription factor 2(ATF2), a transcription factor belonging to the AP-1 family, plays an important role in inflammation. However, its biological functions and underlying molecular mechanisms in rheumatoid arthritis (RA) remain unclear. Western blot and immunohistochemistry were used to identify the expression of ATF2 and Sprouty2(SPRY2) in RA synovial tissues. SW982 cells were stimulated by TNF-α to establish an in vitro RA fibroblast-like synoviocyte (RA-FLS) model. Transwell and monolayer wound-healing were used to detect cell migration and invasion. RNA interference (si-ATF2) and adenovirus vector (Ad-SPRY2) methods were employed to manipulate ATF2 or SPRY2 expression in SW982 cells. The protein expression and phosphorylation levels in SW982 cells were evaluated by western blot. ATF2 expression and phosphorylation were upregulated in the RA synovial tissues. In RA-FLS model, ATF2 expression and phosphorylation were increased in a time-dependent manner. ATF2 knockdown inhibited the migration and invasion of RA-FLS model, reducing the inflammatory factors, which was consistent with the influence on cell behaviors caused by SPRY2 overexpression. Moreover, SPRY2 overexpression inhibited the TNF-α-induced phosphorylation of ERK and ATF2 in SW982 cells. The high expression and phosphorylation of ATF2 promoted migration and invasion of RA-FLSs. SPRY2 might inhibited the inflammatory responses of RA-FLSs via suppressing ERK-ATF2 pathway.

Role of microRNAs in neurodegeneration induced by environmental neurotoxicants and aging

The progressive loss of neuronal structure and functions resulting in the death of neurons is considered as neurodegeneration. Environmental toxicants induced degeneration of neurons is accelerated with aging. In adult brains, most of the neurons are post-mitotic, and their loss results in the development of diseases like amyotrophic lateral sclerosis (ALS), Parkinson's disease (PD), Alzheimer's disease (AD), and Huntington's disease (HD). Neurodegenerative diseases have several similarities at the sub-cellular and molecular levels, such as synaptic degeneration, oxidative stress, inflammation, and cognitive decline, which are also known in brain aging. Identification of these similarities at the molecular level offers hope for the development of new therapeutics to ameliorate all neurodegenerative diseases simultaneously. Aging is known as the most strongly associated additive factor in the pathogenesis of neurodegenerative diseases. Studies carried out so far identified several genes, which are responsible for selective degeneration of neurons in different neurodegenerative diseases. Countless efforts have been made in identifying therapeutics for neurodegenerative diseases; however, the discovery of effective therapy remains elusive. Findings made in the last two decades identified microRNAs (miRNAs) as the most potent post-transcription regulatory RNA molecule, which can condition protein levels in the cell and tissue-specific manner. Identification of miRNAs, which regulate both neurotoxicant and aging-associated degeneration of brain cells, raises the possibility that roads leading to aging and neurotoxicant induced neurodegeneration cross at some point. Identification of miRNAs, which are common to aging and neurotoxicant induced neurodegeneration, will help in understanding the complex mechanism of neurodegenerative disease development. In the future, the use of natural miRNAs in vivo in therapy will be able to tackle several issues of aging and neurodegeneration. In the present review, we have provided a summary of findings made on the role of miRNAs in neurodegeneration and explored the common link made by miRNAs between aging and neurotoxicants induced neurodegeneration.

Epigenetic Mechanisms in Monocytes/Macrophages Regulate Inflammation in Cardiometabolic and Vascular Disease

Cardiometabolic and vascular disease, with their associated secondary complications, are the leading cause of morbidity and mortality in Western society. Chronic inflammation is a common theme that underlies initiation and progression of cardiovascular disease. In this regard, monocytes/macrophages are key players in the development of a chronic inflammatory state. Over the past decade, epigenetic modifications, such as DNA methylation and posttranslational histone processing, have emerged as important regulators of immune cell phenotypes. Accumulating studies reveal the importance of epigenetic enzymes in the dynamic regulation of key signaling pathways that alter monocyte/macrophage phenotypes in response to environmental stimuli. In this review, we highlight the current paradigms of monocyte/macrophage polarization and the emerging role of epigenetic modification in the regulation of monocyte/macrophage phenotype in obesity, diabetes mellitus, atherosclerosis, and abdominal aortic aneurysms.

Immune cell extracellular vesicles and their mitochondrial content decline with ageing

Background

Although the mechanisms of action are not fully understood, extracellular vesicles (EVs) have emerged as key indicators and effectors of immune function. Characterizing circulating EVs associated with stem and immune cells across the lifespan of healthy individuals could aid an understanding of immunosenescence, a process of age-related decline of cells in both adaptive and innate immune systems.

Results

Using high resolution multicolor flow cytometry, we identified three major subsets of EVs of varying sizes in healthy control (HC) plasma. Multiple plasma EVs associated with immune cells declined with ageing in HCs. In addition, we observed age-associated declines of respiring mitochondria cargo in EVs of several types of immune cells, suggesting that these parent cells may experience a decline in mitophagy or a mitochondrial dysfunction-induced immunosenescence. By contrast, the number of CD34⁺ hematopoietic stem cell-associated EVs were high and carried respiring mitochondria, which did not decline with age.

Conclusion

As demonstrated here, multicolor flow cytometry simultaneously measures plasma EV size, surface markers and cargo that reflect biological processes of specific cell types. The distinct surface markers and cytokine cargo of plasma EVs suggest that they may carry different bio-messages and originate by different biogenesis pathways.

Development of Capsular Fibrosis Beneath the Liver Surface in Humans and Mice

Glisson's capsule is the connective tissue present in the portal triad as well as beneath the liver surface. Little is known about how Glisson's capsule changes its structure in capsular fibrosis (CF), which is characterized by fibrogenesis beneath the liver surface. In this study, we found that the human liver surface exhibits multilayered capsular fibroblasts and that the bile duct is present beneath the mesothelium, whereas capsular fibroblasts are scarce and no bile ducts are present beneath the mouse liver surface. Patients with cirrhosis caused by alcohol abuse or hepatitis C virus infection show development of massive CF. To examine the effect of alcohol on CF in mice, we first injected chlorhexidine gluconate (CG) intraperitoneally and then fed alcohol for 1 month. The CG injection induces CF consisting of myofibroblasts beneath the mesothelium. One month after CG injection, the fibrotic area returns to the normal structure. In contrast, additional alcohol feeding sustains the presence of myofibroblasts in CF. Cell lineage tracing revealed that mesothelial cells give rise to myofibroblasts in CF, but these myofibroblasts disappear 1 month after recovery with or without alcohol feeding. Capsular fibroblasts isolated from the mouse liver spontaneously differentiated into myofibroblasts and their differentiation was induced by transforming growth factor beta 1 (TGF-β1) or acetaldehyde in culture. In alcohol-fed mice, infiltrating CD11b⁺ Ly-6C^Low/- monocytes had reduced mRNA expression of matrix metalloproteinase 13 and matrix metalloproteinase 9 and increased expression of tissue inhibitor of matrix metalloproteinase 1, Tgfb1, and interleukin-10 during resolution of CF. Conclusion: The present study revealed that the structure of Glisson's capsule is different between human and mouse livers and that alcohol impairs the resolution of CF by changing the phenotype of Ly-6C^Low/- monocytes.

Electrostatic Surface Potential of Macrophages Correlates with Their Functional Phenotype

Macrophages exist in various functional phenotypes, which could be identified by specific surface molecules. Previous studies have shown that modulation of surface charges could alter the phagocytic function of macrophages. In this study, we show that activation of both human peripheral blood monocyte and THP-1-derived macrophages with lipopolysaccharide (LPS) or IL-1β resulted in a significant decrease in the zeta potential compared to freshly isolated monocytes and unstimulated macrophages. Interestingly, interaction with bacteria significantly increased the zeta potential of such cells irrespective of activation conditions. Similarly, IFNγ-treated pro-inflammatory macrophages showed lesser negative zeta potential compared to untreated control. A moderate reduction was also seen in IL-4-treated anti-inflammatory subtype. Additionally, in an LPS-induced systemic inflammation model, bone marrow cells isolated after 2 h of LPS injection showed significant reduction in zeta potential compared to naïve cells. Furthermore, electrostatic potential measurement of surface proteins associated with pro-inflammatory and anti-inflammatory macrophages, using in silico modeling under physiological and protonation conditions, showed that the average electrostatic potential of pro-inflammatory type surface proteins was less negative than anti-inflammatory subtype. These data suggest that the expression of different protein molecules on macrophages under different environments may contribute to the zeta potential and that this quick and low-cost technique could be used in monitoring macrophage functional phenotypes.

Dysregulated Lipid Transport Proteins Correlate With Pathogenesis and Outcome in Severe Alcoholic Hepatitis

Severe alcoholic hepatitis (SAH) has high mortality. Dysregulated lipid transport and metabolism in liver/macrophages contributes to disease pathophysiology. Paraoxonase/arylesterase 1 (PON1), a liver‐specific enzyme, inhibits oxidation of phospholipids and prevents lipid‐mediated oxidative damage. However, its functional contribution in macrophage‐mediated hepatic injury warrants elucidation. Plasma proteome of patients with SAH (n = 20), alcoholic cirrhosis (n = 20), and healthy controls was analyzed. Dysregulated pathways were identified, validated, and correlated with severity and outcomes in 200 patients with SAH. Tohoku‐Hospital‐Pediatrics‐1 (THP1)‐derived macrophages were treated with plasma from study groups in the presence/absence of recombinant PON1 and the phenotype; intracellular lipid bodies and linked functions were evaluated. In patients with SAH, 208 proteins were >1.5 fold differentially regulated (32 up‐regulated and 176 down‐regulated; P < 0.01).Validation studies confirmed lower levels of lipid transporter proteins (Pon1, apolipoprotein [Apo]B, ApoA1, ApoA2, and ApoC3; P < 0.01). Low PON1 levels inversely correlated with severity and mortality (r² > 0.3; hazard ratio, 0.91; P < 0.01) and predicted nonsurvivors (area under the receiver operating characteristic curve, 0.86; cut‐off, <18 μg/mL; log rank, <0.01). Low PON1 levels corroborated with increased oxidized low‐density lipoprotein levels, intracellular lipid bodies, lipid uptake, lipid metabolism, biosynthesis, and alternative macrophage activation genes in nonsurvivors (P < 0.01). Importantly, in vitro recombinant PON1 treatment on THP1 macrophages reversed these changes (P < 0.01), specifically by alteration in expression of clusters of differentiation 36 (CD36) and adenosine triphosphate‐binding cassette subfamily A1 (ABCA1) receptor on macrophages. Conclusion: Lipid transport proteins contribute to the pathogenesis of SAH, and low PON1 levels inversely correlate with the severity of alcoholic hepatitis and 28‐day mortality. Restitution of circulating PON1 may be beneficial and needs therapeutic evaluation in patients with SAH.

Biomarkers of Macrophage Activation and Immune Danger Signals Predict Clinical Outcomes in Alcoholic Hepatitis

Although mortality due to acute alcoholic hepatitis (AH) correlates with Model for End-Stage Liver Disease (MELD) scores, biomarkers are critically needed to manage this disease. Increases in inflammatory markers and macrophage activation are associated with acute AH and could be potential biomarkers of clinical events and/or mortality. We enrolled 89 clinically diagnosed AH patients in four US academic medical centers. Plasma from AH patients had a significant increase in gut microbial translocation indicators (endotoxin, bacterial 16S ribosomal DNA) and host response indicators (soluble cluster of differentiation 14 [sCD14] and lipopolysaccharide binding protein [LBP]) compared to controls. Patient MELD score and Glasgow Alcoholic Hepatitis score (GAHS) correlated with endotoxin levels. AH patients also had a significant increase in high mobility group protein 1 (HMGB1), a sterile danger signal molecule, and osteopontin (OPN), a multifunctional phosphoprotein involved in neutrophil activation, compared to controls. Increased levels of OPN positively correlated with increasing MELD score, GAHS, and LBP levels. Consistent with these results, AH patients had significantly increased circulating levels of macrophage activation (sCD163 and sCD206) markers compared to healthy controls, and sCD163 and sCD206 significantly and positively correlated with OPN, HMGB1, and LBP levels as well as with MELD score and GAHS. These findings indicate a connection between microbial translocation, immune cell activation, and AH severity. Plasma sCD14, OPN, sCD163, and sCD206 levels were significantly higher in nonsurvivors than survivors. In multivariate regression models, we identified sCD14, sCD163, and OPN as independent predictors of 90-day mortality, infection, and organ failure development, respectively. Conclusion: Our study suggests that sCD14, LBP, OPN, sCD163, and sCD206 are biomarkers to indicate severity and predict clinical outcomes in AH.

MicroRNA-27a (miR-27a) in Solid Tumors: A Review Based on Mechanisms and Clinical Observations

MicroRNAs (miRNAs) are a family of highly conserved, non-coding single-stranded RNAs transcribed as ~70 nucleotide precursors to an 18–22 nucleotide product (1). miRNAs can silence their homologous target genes at the post-transcriptional level, and these genes have been revealed to play an important role in tumorigenesis, invasion and metastasis (2). MicroRNA-27a (miR-27a), transcripted by miR-27a gene, has proved to implicate with many kinds of solid tumors, showing potential as a useful biomarker or drug target for clinical application. However, even though miR-27a has been reported in many cancers, the mechanism and signal pathways of miR-27 in oncogenesis, invasion, and metastasis are still obscure. Moreover, recent studies show that miR-27a pays an important role in epithelial-mesenchymal-transition, regulating tumor immune response, and chemoresistance. In this review, we summarize the current literature, demonstrate the established link between miR-27a and tumorigenesis, and focus on recently identified mechanisms. The review also aims to demonstrate the potential of miR-27a as a diagnostic and/or prognostic biomarker in solid tumors and to discuss the possibilities of targeted therapy and drug design.

Melanoma-conditioned medium promotes cytotoxic immune responses by murine bone marrow-derived monocytes despite their expression of 'M2' markers

Macrophages have been shown to infiltrate a wide range of malignancies and are often considered to promote tumour survival, growth and spread. However, the source and behaviour of discrete tumour-associated macrophage populations are still poorly understood. Here we show a novel method for the rational development of bone marrow-derived monocytes appropriate for the study of processes which involve the contribution of circulating inflammatory monocytes. We have shown that in response to tumour-conditioned medium, these cells upregulate CD206 and CD115, markers traditionally associated with M2-type macrophages. Treated cells show reduced capacity for cytokine secretion but significantly impact CD4⁺ and CD8⁺ T-cell proliferation and polarization. Coculture with conditioned bone marrow-derived monocytes significantly reduced CD4⁺ T-cell proliferation but increased CD8⁺ T-cell proliferation and granzyme B expression with significant induction of IFNγ secretion by both CD4⁺ and CD8⁺ T cells, indicating that these cells may have a role in promoting anti-cancer immunity.

Protocatechuic Acid-Mediated miR-219a-5p Activation Inhibits the p66shc Oxidant Pathway to Alleviate Alcoholic Liver Injury

Alcohol abuse has become common worldwide and has been recognized as a major cause of chronic alcoholic liver disease (ALD). ALD encompasses a complex process that includes a broad scope of hepatic lesions, ranging from steatosis to cirrhosis. In particular, reactive oxygen species (ROS) are mainly involved. Numerous studies have shown that p66shc plays a significant role in ALD. Protocatechuic acid (PCA), a dihydroxybenzoic acid that is naturally found in green tea, vegetables, and fruits, has efficient free radical scavenging effects. In this study, we aimed to assess the protective effect of PCA on ALD and to evaluate the microRNA- (miRNA-) p66shc-mediated reduction of ROS formation in ALD. Our results demonstrated that PCA treatment significantly decreased p66shc expression and downstream ROS formation in ALD. miR-219a-5p, which was identified by bioinformatics and experimental analysis, was enhanced by PCA and subsequently suppressed p66shc expression. Importantly, p66shc played an essential role in the protection of PCA-stimulated miR-219a-5p overexpression. Overall, these findings show that PCA-stimulated miR-219a-5p expression mitigates ALD by reducing p66shc-mediated ROS formation. This study may contribute to the development of therapeutic interventions for ALD.