Article

MiR-155 inhibits transformation of macrophages into foam cells via regulating CEH expression

Authors:
To read the full-text of this research, you can request a copy directly from the authors.

No full-text available

Request Full-text Paper PDF

To read the full-text of this research,
you can request a copy directly from the authors.

... Activated endothelial cells will release proinflammatory cytokines and adhesion molecules to provoke the differentiation of monocytes [40]. Upon stimulation by excessive lipids, macrophages will engulf necrotic cells and lipids to become foam cells and trigger more inflammatory responses that only aggravate the condition [22]. Zhang and colleagues (2018) demonstrated the role of miR-155 in the activation of macrophages by targeting cholesterol ester hydrolase (CEH), class A scavenger receptor (SR-A), and ATP binding cassette transporter A1 (ABCA1) proteins [22]. ...
... Upon stimulation by excessive lipids, macrophages will engulf necrotic cells and lipids to become foam cells and trigger more inflammatory responses that only aggravate the condition [22]. Zhang and colleagues (2018) demonstrated the role of miR-155 in the activation of macrophages by targeting cholesterol ester hydrolase (CEH), class A scavenger receptor (SR-A), and ATP binding cassette transporter A1 (ABCA1) proteins [22]. Usually, miR-155 is involved in the body's immune system by regulating the secretion of inflammatory factors in T cells, B cells, monocytes, and macrophages. ...
Article
Full-text available
Ischemic heart disease (IHD) constitutes the leading global cause of mortality and morbidity. Although significant progress has been achieved in the diagnosis, treatment, and prognosis of IHD, more robust diagnostic biomarkers and therapeutic interventions are still needed to circumvent the increasing incidence of IHD. MicroRNAs (miRNAs) are critical regulators of cardiovascular function and are involved in various facets of cardiovascular biology. While the knowledge of the role of miRNAs in IHD as diagnostic biomarkers has improved, research emphasis on how miRNAs can be effectively used for diagnosis and prognosis of IHD is crucial. This review provides an overview of the biology, therapeutic and diagnostic potential, as well as the caveats of using miRNAs in IHD based on existing research.
... 10 In contrary, miR-155 can inhibit the transformation of macrophages into foam cells by enhancing CEH signaling pathway in macrophages. 18 miR-155 also contributes to the autophagy process, which is important for regeneration of vascular intimal wall injury. It promotes autophagy in vascular endothelial cells (VECs) by suppressing phosphorylated PI3K/Akt/mTOR pathway. ...
... 78,79 PI3K/Akt regulates VSMCs proliferation and induces inflammatory response, whereas STAT3 Table 1 Role of miRNA in CAD development miRNA Data from Refs. [9][10][11][12][13][14][15][16][17][18][19]21,24,26,27,29,30,32,34,35,39,41,43,45,46,[52][53][54][55][56][57][58][59][60][61][91][92][93][94][95] miRNAs/lncRNAs-based Therapy in Coronary Artery Disease promotes VSMCs proliferation. 80 Overexpression of MIAT facilitated proliferation, accelerated cell cycle progression, and hindered apoptosis in ox-LDL-induced VSMCs. ...
Article
Full-text available
Noncoding RNAs (ncRNAs), including long noncoding RNAs and microRNAs, play an important role in coronary artery disease onset and progression. The ability of ncRNAs to simultaneously regulate many target genes allows them to modulate various key processes involved in atherosclerosis, including lipid metabolism, smooth muscle cell proliferation, autophagy, and foam cell formation. This review focuses on the therapeutic potential of the most important ncRNAs in coronary artery disease. Moreover, various other promising microRNAs and long noncoding RNAs that attract substantial scientific interest as potential therapeutic targets in coronary artery disease and merit further investigation are presented.
... Another study showed that miR-155 mimics enhanced the expression of CEH at both the transcriptional and translational level in a dose-and time-dependent manner in human foam cells, although this effect may have occurred due to the inhibition in the expression of Tim-3, since overexpression of Tim-3 can inhibit the expression of CEH. Additionally, using a human monocyte cell line, it has been demonstrated that the overexpression of miR-155 can significantly inhibit the expression of SR-A, decrease lipid accumulation, increase the expression of ABCA1 and thereby increase cholesterol efflux [132]. ...
Article
Full-text available
Atherosclerosis is a major cause of human cardiovascular disease, which is the leading cause of mortality around the world. Various physiological and pathological processes are involved, including chronic inflammation, dysregulation of lipid metabolism, development of an environment characterized by oxidative stress and improper immune responses. Accordingly, the expansion of novel targets for the treatment of atherosclerosis is necessary. In this study, we focus on the role of foam cells in the development of atherosclerosis. The specific therapeutic goals associated with each stage in the formation of foam cells and the development of atherosclerosis will be considered. Processing and metabolism of cholesterol in the macrophage is one of the main steps in foam cell formation. Cholesterol processing involves lipid uptake, cholesterol esterification and cholesterol efflux, which ultimately leads to cholesterol equilibrium in the macrophage. Recently, many preclinical studies have appeared concerning the role of non-encoding RNAs in the formation of atherosclerotic lesions. Non-encoding RNAs, especially microRNAs, are considered regulators of lipid metabolism by affecting the expression of genes involved in the uptake (e.g., CD36 and LOX1) esterification (ACAT1) and efflux (ABCA1, ABCG1) of cholesterol. They are also able to regulate inflammatory pathways, produce cytokines and mediate foam cell apoptosis. We have reviewed important preclinical evidence of their therapeutic targeting in atherosclerosis, with a special focus on foam cell formation.
... T IM -3 inhibits proliferat ion a n d migrat ion in PDGF-BB-stimulated HASMCs. Previous studies have reported that the expression of TIM-3 is upregulated in atherosclerotic patients or animal models (16,19,20). In the present study, it was demonstrated that the expression of TIM-3 was upregulated in LEAOD arterial tissues (Fig. 1B). ...
Article
Full-text available
Increasing evidence suggests that T‑cell immunoglobulin and mucin domain 3 (TIM‑3) displays anti‑atherosclerotic effects, but its role in vascular smooth muscle cells (VSMCs) has not been reported. The present study aimed to investigate the function of TIM‑3 and its roles in human artery VSMCs (HASMCs). A protein array was used to investigate the TIM‑3 protein expression profile, which indicated that TIM‑3 expression was increased in the serum of patients with lower extremity arteriosclerosis obliterans disease (LEAOD) compared with healthy individuals. Immunohistochemistry and western blotting of arterial tissue further revealed that TIM‑3 expression was increased in LEAOD artery tissue compared with normal artery tissue. Additionally, platelet‑derived growth factor‑BB (PDGF‑BB) displayed a positive correlation with TIM‑3 expression in HASMCs. TIM‑3 decreased the migration and proliferation of PDGF‑BB‑induced HASMCs, and anti‑TIM‑3 blocked the effects of TIM‑3. The effect of TIM‑3 on the proliferation and migration of HASMCs was further investigated using LV‑TIM‑3‑transduced cells. The results revealed that TIM‑3 also inhibited PDGF‑BB‑induced expression of the inflammatory factors interleukin‑6 and tumor necrosis factor‑α by suppressing NF‑κB activation. In summary, the present study revealed that TIM‑3 displayed a regulatory role during the PDGF‑BB‑induced inflammatory reaction in HASMCs, which indicated that TIM‑3 may display anti‑atherosclerotic effects.
... Mir-155 is one of the extensively studied miRNAs and has been reported to be related to CAD. Studies showed that mir-155 regulates the formation of foam cells by its anti-in ammatory and proin ammatory effects (7) . However, the regulatory network of mir-155 in CAD remains unclear. ...
Preprint
Full-text available
Background: Coronary artery disease (CAD) is one of the leading causes of mortality in the world, and its early diagnosis remains a huge challenge in clinical medicine. Genetic and environmental factors both contribute to the occurrence and development of CAD. It is reported that the inhibition of mitophagy plays an important role in CAD, while the molecular mechanism is still uncertain. In our previous studies, circulating mir-155 in plasma showed a significant differential expression in CAD populations and controls. Method: In this study, we detected the expression of RNAs and proteins in human coronary artery samples with genome sequencing. Bioinformatics analysis was conducted to find the binding sites of circRNAs, mir-155 and protein coding genes. Result: 2135 protein groups, 21703 unique peptides and 1640 circRNAs were identified in the samples. 174 differential expressed proteins and 66 differential expressed circRNAs were screened according to the pathological grading and staging of the samples. GO and KEGG analysis showed that the SDEPs were significantly associated with metabolism, oxidative respiration, and mitochondrial function. Based on the gene-gene interaction and gene-protein interaction analysis, a novel ceRNA network may play a regulatory role in CAD. Conclusion: Hsa_circ_0004182 may inhibit the expression of mir-155 by acting as miRNA sponges, and repress the post-transcriptional repression of GPD1L mediated by mir-155, and promote GPD1L expression in coronary artery disease.
... MiR-146a, on the other hand, promoted the release of ROS and NETs by inhibiting SOD2 (131). In terms of anti-inflammatory, miR-155 from THP-1 macrophages inhibits foam cell formation and enhances cholesterol efflux (203). miR-34a regulates macrophage cholesterol efflux and reverses cholesterol transport by inhibiting ATP-binding cassette subfamily G member 1 (ABCG1) and liver x receptor a (204). ...
Article
Full-text available
An effective acute inflammatory response results in the elimination of infectious microorganisms, followed by a smooth transition to resolution and repair. During the inflammatory response, neutrophils play a crucial role in antimicrobial defense as the first cells to reach the site of infection damage. However, if the neutrophils that have performed the bactericidal effect are not removed in time, the inflammatory response will not be able to subside. Anti-inflammatory macrophages are the main scavengers of neutrophils and can promote inflammation towards resolution. MicroRNAs (miRNAs) have great potential as clinical targeted therapy and have attracted much attention in recent years. This paper summarizes the involvement of miRNAs in the process of chronic diseases such as atherosclerosis, rheumatoid arthritis and systemic lupus erythematosus by regulating lipid metabolism, cytokine secretion, inflammatory factor synthesis and tissue repair in two types of cells. This will provide a certain reference for miRNA-targeted treatment of chronic diseases.
... In agreement, we did not find any significant difference in MiRNA-155 expression among RF, CAS-A and CAS-S patients. However, miRNA-155 has also implicated in lowering inflammation [18], suggesting that it plays a role in regulating immune-inflammatory process underling to the different stages of parietal remodeling. This is, to our knowledge, the first report on expression of MiR-NAs in human PBMCs from CAS patients. ...
Article
Full-text available
Background: The aim of this study was to evaluate miRNA-33 and miRNA-155 expression in Peripheral Blood Mononuclear Cells (PBMC) and carotid specimens of patients affected by Critical Carot- id Artery Stenosis (CAS). Material and Methods: We selected 17 asymptomatic (CAS-A group) and 10 symptomatic (CAS-S group) patients with CAS. Ten patients with traditional cardiovascular risk factors (RF group), matched for age and sex, were used as control group. Results: A significant increase in miRNA-33 expression was observed both in peripheral blood and in carotid specimens of CAS-A patients (p 0.04) in comparison with CAS-S and RF, whereas no significant difference were found among the groups regarding miRNA-155 expression both in peripheral blood and in carotid specimens. Conclusions: This is to our knowledge the first report on miRNAs expression in human PBMCs from CAS patients. Results of this study suggest that miRNA-33 in involved in the process underling plaque formation and growth, but not is plaque instability and ischemic brain damage, whereas miRNA-155 is expressed during all the phases of atherosclerotic disease.
... Inhibition of miR-33 by anti-miR-33 increased HDL levels and decreased lipid accumulation and inflammation and inhibited the transformation of macrophages into foam cells to markedly reduce atherosclerosis plaque progression [54]. Furthermore, overexpression of miR-155 can significantly inhibit foam cell formation by activating cholesterol ester hydrolase (CEH) in macrophages to decrease intracellular lipid accumulation and prevent atherosclerosis plaque formation [55]. Circulatory levels of microRNA-155 were surprisingly higher in CAD patients as compared with controls. ...
Article
Full-text available
Atherosclerotic ischemic coronary artery disease (CAD) is a significant community health challenge and the principal cause of morbidity and mortality in both developed and developing countries for all ethnic groups. The progressive chronic coronary atherosclerosis is the main underlying cause of CAD. Although enormous progress occurred in the last three decades in the management of cardiovascular diseases, the prevalence of CAD continues to increase worldwide, indicating the need for discovery of deeper molecular insights of CAD mechanisms, biomarkers, and innovative therapeutic targets. Recently, several research groups established that microRNAs essentially regulate various cardiovascular development and functions, and a deregulated cardiac enriched microRNA profile plays a vital role in the pathogenesis of CAD and its biological aging. Numerous studies established that over- or downregulation of a single miRNA gene by ago-miRNA or anti-miRNA is enough to modify the CAD disease process, significantly prevent age-dependent cardiac cell death, and markedly improve cardiac function. In the light of more recent experimental and clinical evidences, we briefly reviewed and discussed the involvement of miRNAs in CAD and their possible diagnostic/therapeutic values. Moreover, we also focused on the role of miRNAs in the initiation and progression of the atherosclerosis plaque as the strongest risk factor for CAD.
... Thus, plaque progression and rupture were linked to the expression of miR-23a-5p, miR-210 and miR-222 [16,17] while, on the contrary, miR-19b and miR-33a/miR-33b had protective roles on plaque stability [18,19]. Furthermore, plasma miR-144 and miR-33 levels were seen to be increased in coronary artery disease (CAD) patients [20,21], miR-155 was seen to inhibit transformation of macrophages into foam cells by targeting CEH expression [22], and miR-181b was found to be overexpressed in human atherosclerotic plaques and abdominal aortic aneurysms, where it downregulated expression of the tissue inhibitor of MMP-3, and elastin [23]. Lastly, miR-296 has been described as a positive regulator of ATH onset and progression by promoting neovascularization and favoring M1 macrophage polarization [24]. ...
Article
Full-text available
Background: CD34⁺ Endothelial Progenitor Cells (EPCs) play an important role in the recovery of injured endothelium and contribute to atherosclerosis (ATH) pathogenesis. Previously we described a potential atherogenic role for miR-125 that we aimed to confirm in this work. Methods: Microarray hybridization, TaqMan Low Density Array (TLDA) cards, qPCR, and immunohistochemistry (IHC) were used to analyze expression of the miRNAs, proteins and transcripts here studied. Results: Here we have demonstrated an increase of resident CD34-positive cells in the aortic tissue of human and mice during ATH progression, as well as the presence of clusters of CD34-positive cells in the intima and adventitia of human ATH aortas. We introduce miR-351, which share the seed sequence with miR-125, as a potential effector of CD34. We show a splicing event at an internal/cryptic splice site at exon 8 of the murine Cd34 gene (exonic-switch) that would regulate the differential accession of miRNAs (including miR-125) to the coding region or to the 3'UTR of Cd34. Conclusions: We introduce new potential mediators of ATH progression (CD34 cell-clusters, miR-351), and propose a new mechanism of miRNA action, linked to a cryptic splicing site in the target-host gene, that would regulate the differential accession of miRNAs to their cognate binding sites.
Article
Full-text available
MicroRNAs (miRNAs) are noncoding RNA molecules that play a significant role in atherosclerosis pathogenesis through post-transcriptional regulation. In the present work, a bioinformatic analysis using TargetScan and miRdB databases was performed to identify the miRNAs targeting three genes involved in foam cell atherosclerosis (CD36, SOCS1, and Vav3). A total number of three hundred and sixty-seven miRNAs were recognized and only miR-155–5p was selected for further evaluation based on Venn analysis. Another objective of this study was to evaluate the biological process and regulatory network of miR-155–5p associated with foam cell atherosclerosis using DIANA, DAVID, Cytoscape, and STRING tools. Additionally, the comprehensive literature review was performed to prove the miR-155–5p function in foam cell atherosclerosis. miR-155–5p might be related with ox-LDL uptake and endocytosis in macrophage cell by targeting CD36 and Vav3 genes which was showed from the KEGG pathways hsa04979, hsa04560, hsa04810, and GO:0099632. Furthermore, miR-155–5p was also predicted to increase the cholesterol efflux from macrophage by inhibit SOCS1 expression based on KEGG pathway hsa04120. Eleven original studies were included in the review and strongly suggest the role of miR-155–5p in foam cell atherosclerosis inhibition.
Article
Adipose tissue expansion and subsequent metabolic dysfunction has been considered one of the major risk factors for cardiometabolic disease development. Epicardial adipose tissue (EAT) in particular, is a unique subtype of visceral adipose tissue located on the surface of the heart, around the coronary arteries. Due to its proximity, EAT can modulate the local metabolic and immune function of cardiomyocytes and coronary arteries. Several microRNAs (miRs) have been described as key players in both cardiac and vascular function, that when dysregulated will contribute to dysfunction. Here we review the influence of obesity in the crosstalk between specific adipose tissue types, in particular the EAT secreted miRs, as key modulators of cardiac disease progression, not only as early biomarkers but also as therapeutic targets for cardiometabolic disease. This article is protected by copyright. All rights reserved
Article
Chemically modified chitosan nanoparticles (NPs) are capable of releasing their own substances to target cells or tissues, improving microenvironment and promoting wound healing. This study aimed to explore the molecular mechanism underlying chitosan NPs loaded with TGF-β1 participating in cervical cancer (CC) progression. TGF-β1-loaded-chitosan NPs were prepared and particle size distribution, zeta potential and encapsulation efficiency of NPs were determined. MTT assay assessed the toxicity of NPs to macrophages. CC cells were co-cultured with TGF-β1-loaded chitosan NPs (experimental group) or pure chitosan NPs (control group) and cells were cultured alone to produce control group. After treatment, flow cytometry was conducted to detect apoptosis and cycle. Cancer cell migration was evaluated by Transwell assay, and miR-155 and Tim-3 expression was determined. At a ratio of 2:1 chitosan and TGF-β1, the particle size was102.65±11.98 nm, which was smallest, with high encapsulation rate of 81.26%, and low potential of 1.46±1.71. NP toxicity increased as concentration rose and relative cell proliferation rate was >80%, indicated as non-toxic. CC tissues had positive expression of CD163 and TGF-β1 (95%) (p < 0.05). Treatment with TGF-β1-loaded chitosan NPs induced increased apoptosis rate of 9.13±2.15%, reduced migration (67.65±9.91) and invaded cells (19.98±3.41), causing cell accumulation in the S phase when compared to the blank and control groups (p < 0.05). Besides, experimental group exhibited lower expression of miR-155 (0.39±0.59) and higher expression of Tim-3 (2.87± 0.51), which was higher than the blank group and control group. The optimal concentration ratio for producing TGF-β1-loaded chitosan NPs was 2:1, with less toxicity. The composite NPs suppressed malignant characteristics of CC cells through down-regulation of miR-155 and activation of Tim-3 signal pathway on the surface of macrophages, promoting secretion of macrophage inflammatory factors.
Article
Full-text available
Accumulation of macrophage "foam" cells, laden with cholesterol and cholesteryl ester, within the intima of large arteries, is a hallmark of early "fatty streak" lesions which can progress to complex, multicellular atheromatous plaques, involving lipoproteins from the bloodstream and cells of the innate and adaptive immune response. Sterol accumulation triggers induction of genes encoding proteins mediating the atheroprotective cholesterol efflux pathway. Within the arterial intima, however, this mechanism is overwhelmed, leading to distinct changes in macrophage phenotype and inflammatory status. Over the last decade marked gains have been made in understanding of the epigenetic landscape which influence macrophage function, and in particular the importance of small non-coding micro-RNA (miRNA) sequences in this context. This review identifies some of the miRNA sequences which play a key role in regulating "foam" cell formation and atherogenesis, highlighting sequences involved in cholesterol accumulation, those influencing inflammation in sterol-loaded cells, and novel sequences and pathways which may offer new strategies to influence macrophage function within atherosclerotic lesions.
Article
Splenic hemorrhagic shock is a typical emergency in surgery, seriously threatening human beings' life. Emerging evidence shows that microRNAs (miRNAs) are closely related to inflammation and immunity in the body. However, the detailed effects and underlying mechanisms of miRNAs on the immune function of splenic hemorrhagic shock have not been revealed yet. In the present study, we construct the rat hemorrhagic shock model, and the rats are further cured with splenic blood transport clipping recanalization (SBTCR). MiR-18b-5p was highly expressed in the spleen of hemorrhagic shock rats detected by the qRT-PCR assay. Functionally, down-regulation of miR-18b-5p notably inhibited the levels of SOD1, iNOS and IL-6 in macrophages isolated from splenic tissues detected by qRT-PCR and ELISA assays. In addition, inhibition of miR-18b-5p significantly decreased the M1/M2 ratio of macrophages. Besides, knockdown of miR-18b-5p obviously reduced the Th1/Th2 ratio of CD4⁺ T cells. Moreover, HIF-1α was predicted as a target gene of miR-18b-5p, which was further confirmed by dual-luciferase reporter assay, and HIF-1α was negatively associated with miR-18b-5p. Furthermore, overexpression of HIF-1α partially restored the effects of miR-18b-3p on inflammation and immunity in macrophages. Taken together, miR-18b-5p may be a novel therapeutic candidate target in splenic hemorrhagic shock treatment.
Chapter
Heart failure (HF) is a leading cause of death worldwide and is still growing. Thus, it’s critical to understand the molecular causes of HF and develop effecitive therapies to treat HF. Recently, scientists and clinicians identified that noncoding RNAs play important roles in pathogenesis of HF. Some of noncoding RNAs can serve as novel biomarkers for HF and some of them contribute to the progression of HF. In addition, noncoding RNAs can be related to well-known HF risk factors, such as hypertension, diabetes etc. In this review, we sought to summarize current knowledge about noncoding RNAs and noncoding RNAs mediated regulation of HF and its risk factors.
Article
MicroRNAs (miRNAs) have rapidly emerged as key molecules in cancer initiation and development, showing the capability to regulate pivotal oncogenic pathways. MiR-155 has gathered an increased attention especially in oncology, but also in non-malignanat pathologies. Nowadays, this noncoding RNA is one of the most important miRNAs in cancer, due to the extensive signaling network associated with it, implication in immune system regulation and also deregulation in disease states. Therefore, numerous research protocols are focused on preclinical modulation of miR-155 for therapeutic purposes, or investigation of its dynamic expression for diagnostic/prognostic assessments, with the final intention of bringing this miRNA into the clinical setting. This review comprehensively presents the extended role of miR-155 in cancer and other pathologies, where its expression is dysregulated. Finally, we assess the future steps toward miR-155 based therapeutics.
Article
Intracranial atherosclerosis (ICAS) is the most common etiology of ischemic stroke with the highest rate of stroke recurrence. Little is currently known of the association of circulating inflammation‐regulatory microRNAs (miRNAs) with ICAS. In this review, we briefly discuss that ICAS is characterized as a dynamic and unstable inflammatory process within intracranial arteries. Then, as a topic of discussion, we mainly concentrate on the following crucial miRNAs (miR‐155, miR‐27a/b, miR‐342‐5p, miR‐21, miR‐124, and miR‐223) by virtue of their multiple roles in regulating the progression of atherosclerosis involved with systemic and local inflammatory activities in cerebral arteries. Clinical perspectives of other miRNAs (miR‐146a, miR‐181b, miR‐126, miR‐143, and let‐7b) in ICAS are also mentioned. In relevance to the inflammatory mechanisms of ICAS, the in‐depth knowledge of miRNAs engaged in the progression of intracranial atherosclerotic plaques may provide an approach to a more precise exploration of diagnostic and therapeutic targets for ICAS.
Article
Full-text available
A novel podophyllotoxin derivative, XWL-1-48, was synthesized as an oral topoisomerase II inhibitor. kDNA decatenation assay indicated that XWL-1-48 significantly inhibited topoisomerase II activity in a concentration-dependent manner. Moreover, the cytotoxicity of XWL-1-48 is more potent than its congener GL331 and the IC50 values are from 0.34 ± 0.21 to 3.54 ± 0.54 µM in 10 cancer cell lines including KBV200 cells with P-gp overexpression. Noticeably, XWL-1-48 exerted potent antitumor activity in in vitro and in vivo human hepatocellular carcinoma (HCC) model. Further studies demonstrated that treatment of XWL-1-48 induced γ-H2AX and p-ATM expression, and further triggered DNA damage response through activation of ATM-p53-p21 and ATM-Chk2-Cdc25A pathways. Targeted inhibition of ATM by siRNA attenuated the ability of XWL-1-48 on inducing DNA damage. XWL-1-48 significantly suppressed Cyclin A and p-Cdk2 (Thr160) expression, increased p-Cdk2 (Thr14), led to inactivation of Cyclin A/Cdk2 complex, arrested cell cycle at S phase. Finally, XWL-1-48 elevated the ratio of Bax/Bcl2 and induced Fas and FasL, initiated mitochondria- and death receptor-mediated apoptosis pathway. Meanwhile, XWL-1-48 evidently enhanced degradation of Mdm2, blocked PI3K/Akt/Mdm2 pathway and suppressed HCC cell survival. Thus, XWL-1-48 may be a promising orally topoisomerase II inhibitor for treatment of HCC.
Article
Full-text available
Francisella tularensis is a Gram-negative, facultative intracellular pathogen that replicates in the cytosol of macrophages and is the causative agent of the potentially fatal disease tularemia. A characteristic feature of F. tularensis is its limited proinflammatory capacity, but the mechanisms that underlie the diminished host response to this organism are only partially defined. Recently, microRNAs have emerged as important regulators of immunity and inflammation. In the present study we investigated the microRNA response of primary human monocyte-derived macrophages (MDMs) to F. tularensis and identified 10 microRNAs that were significantly differentially expressed after infection with the live vaccine strain (LVS), as judged by Taqman Low Density Array profiling. Among the microRNAs identified, miR-155 is of particular interest as its established direct targets include components of the Toll-like receptor (TLR) pathway, which is essential for innate defense and proinflammatory cytokine production. Additional studies demonstrated that miR-155 acted by translational repression to downregulate the TLR adapter protein MyD88 and the inositol 5'-phosphatase SHIP-1 in MDMs infected with F. tularensis LVS or the fully virulent strain Schu S4. Kinetic analyses indicated that miR-155 increased progressively 3-18 hours after infection with LVS or Schu S4, and target proteins disappeared after 12-18 hours. Dynamic modulation of MyD88 and SHIP-1 was confirmed using specific pre-miRs and anti-miRs to increase and decrease miR-155 levels, respectively. Of note, miR-155 did not contribute to the attenuated cytokine response triggered by F. tularensis phagocytosis. Instead, this microRNA was required for the ability of LVS-infected cells to inhibit endotoxin-stimulated TNFα secretion 18-24 hours after infection. Thus, our data are consistent with the ability of miR-155 to act as a global negative regulator of the inflammatory response in F. tularensis-infected human macrophages.
Article
Full-text available
Hydrolysis of intra-cellular cholesteryl ester (CE) is the rate-limiting step in the efflux of cholesterol from macrophage foam cells. In mouse peritoneal macrophages (MPMs), this process is thought to involve several enzymes: hormone-sensitive lipase (Lipe), carboxylesterase 3 (Ces3), neutral CE hydrolase 1 (Nceh1). However, there is some disagreement over the relative contributions of these enzymes. To solve this problem, we first compared the abilities of several compounds to inhibit the hydrolysis of CE in cells overexpressing Lipe, Ces3 or Nceh1. Cells overexpressing Ces3 had negligible neutral CE hydrolase activity. We next examined the effects of these inhibitors on the hydrolysis of CE and subsequent cholesterol trafficking in MPMs. CE accumulation was increased by a selective inhibitor of Nceh1, paraoxon and two non-selective inhibitors of Nceh1, (+)-AS115 and (-)-AS115, but not by two Lipe-selective inhibitors, orlistat and 76-0079. Paraoxon inhibited cholesterol efflux to apolipoprotein A-I or HDL, while 76-0079 did not. These results suggest that Nceh1 plays a dominant role over Lipe in the hydrolysis of CE and subsequent cholesterol efflux in MPMs.
Article
Full-text available
The progressive dementia that is characteristic of Alzheimer's disease is associated with the accumulation of amyloid-beta (Abeta) peptides in extracellular plaques and within neurons. Abeta peptides are targeted to cholesterol-rich membrane micro-domains called lipid rafts. Observations that many raft proteins undertake recycling pathways that avoid the lysosomes suggests that the accumulation of Abeta in neurons may be related to Abeta targeting lipid rafts. Here we tested the hypothesis that the degradation of Abeta by neurons could be increased by drugs affecting raft formation. Primary neurons were incubated with soluble Abeta preparations. The amounts of Abeta42 in neurons or specific cellular compartments were measured by ELISA. The effects of drugs on the degradation of Abeta42 were studied. Abeta42 was targeted to detergent-resistant, low density membranes (lipid rafts), trafficked via a pathway that avoided the lysosomes and was slowly degraded by neurons (half-life was greater than 5 days). The metabolism of Abeta42 was sensitive to pharmacological manipulation. In neurons treated with the cholesterol synthesis inhibitor squalestatin, less Abeta42 was found within rafts, greater amounts of Abeta42 were found in lysosomes and the half-life of Abeta42 was reduced to less than 24 hours. Treatment with phospholipase A2 inhibitors or platelet-activating factor (PAF) antagonists had the same effects on Abeta42 metabolism in neurons as squalestatin. PAF receptors were concentrated in the endoplasmic reticulum (ER) along with enzymes that constitute the cholesterol ester cycle. The addition of PAF to ER membranes triggered activation of cholesterol ester hydrolases and the release of cholesterol from stores of cholesterol esters. An inhibitor of cholesterol ester hydrolases (diethylumbelliferyl phosphate) also increased the degradation of Abeta42 in neurons. We conclude that the targeting of Abeta42 to rafts in normal cells is a factor that affects its degradation. Critically, pharmacological manipulation of neurons can significantly increase Abeta42 degradation. These results are consistent with the hypothesis that the Abeta-induced production of PAF controls a cholesterol-sensitive pathway that affects the cellular localisation and hence the fate of Abeta42 in neurons.
Article
Full-text available
Liver plays a central role in the final elimination of cholesterol from the body either as bile acids or as free cholesterol (FC) and lipoprotein-derived cholesterol is the major source of total biliary cholesterol. HDL is the major lipoprotein responsible for removal and transport of cholesterol mainly as cholesteryl esters (CE) from the peripheral tissues to the liver. While HDL-FC is rapidly secreted into bile, the fate of HDL-CE remains unclear. We have earlier demonstrated the role of human cholesteryl ester hydrolase (CEH, CES1) in hepatic hydrolysis of HDL-CE and increasing bile acid synthesis, a process dependent on SR-BI expression. In the present study, we examined the hypothesis that by enhancing the elimination of HDL-CE into bile/feces liver-specific transgenic expression of CEH will be anti-atherogenic. Increased CEH expression in the liver significantly increased the flux of HDL-CE to bile acids. In LDLR-/- background, this enhanced elimination of cholesterol led to attenuation of diet-induced atherosclerosis with a consistent increase in fecal sterol secretion primarily as bile acids. Taken together with the observed reduction in atherosclerosis by increasing macrophage CEH-mediated cholesterol efflux, these studies establish CEH as an important regulator in enhancing cholesterol elimination and also as an anti-atherogenic target.
Article
Full-text available
Liver is the sole organ responsible for the final elimination of cholesterol from the body either as biliary cholesterol or bile acids. High-density lipoprotein (HDL)-derived cholesterol is the major source of biliary sterols and represents a mechanism for the removal of cholesterol from peripheral tissues including artery wall-associated macrophage foam cells. Via selective uptake through Scavenger receptor BI (SR-BI) HDL cholesterol is thought to be directly secreted into bile, and HDL cholesteryl esters (HDL-CEs) enter the hepatic metabolic pool and need to be hydrolyzed prior to conversion to bile acids. However, the identity of hepatic CE hydrolase (CEH) as well as the role of SR-BI in bile acid synthesis remains elusive. In this study we examined the role of human hepatic CEH (CES1) in facilitating hydrolysis of SR-BI delivered HDL-CE. Over-expression to CEH led to increased hydrolysis of HDL-[3H]-CE in primary hepatocytes and SR-BI expression was required for this process. Intracellular CEH associated with BODIPY-CE delivered by selective uptake via SR-BI. CEH and SR-BI expression enhanced the movement of [3H]-label from HDL-[3H]-CE to bile acids in vitro and in vivo. Taken together, these studies demonstrate that SR-BI delivered HDL-CEs are hydrolyzed by hepatic CEH and utilized for bile acid synthesis.
Article
Full-text available
Activation of naive CD4(+) T-helper cells results in the development of at least two distinct effector populations, Th1 and Th2 cells. Th1 cells produce cytokines (interferon (IFN)-gamma, interleukin (IL)-2, tumour-necrosis factor (TNF)-alpha and lymphotoxin) that are commonly associated with cell-mediated immune responses against intracellular pathogens, delayed-type hypersensitivity reactions, and induction of organ-specific autoimmune diseases. Th2 cells produce cytokines (IL-4, IL-10 and IL-13) that are crucial for control of extracellular helminthic infections and promote atopic and allergic diseases. Although much is known about the functions of these two subsets of T-helper cells, there are few known surface molecules that distinguish between them. We report here the identification and characterization of a transmembrane protein, Tim-3, which contains an immunoglobulin and a mucin-like domain and is expressed on differentiated Th1 cells. In vivo administration of antibody to Tim-3 enhances the clinical and pathological severity of experimental autoimmune encephalomyelitis (EAE), a Th1-dependent autoimmune disease, and increases the number and activation level of macrophages. Tim-3 may have an important role in the induction of autoimmune diseases by regulating macrophage activation and/or function.
Article
Full-text available
T cell immunoglobulin and mucin domain-containing 3 (Tim-3) is an inhibitory receptor that is expressed on exhausted T cells during infection with HIV-1 and hepatitis C virus. By contrast, Tim-3 expression and function are defective in multiple human autoimmune diseases. However, the molecular mechanisms modulating Tim-3 function are not well understood. Here we show that human leukocyte antigen B (HLA-B)-associated transcript 3 (Bat3) binds to, and represses the function of, Tim-3. Bat3 protects T helper type 1 (T(H)1) cells from galectin-9-mediated cell death and promotes both proliferation and proinflammatory cytokine production. Bat3-deficient T cells have elevated expression of exhaustion-associated molecules such as Tim-3, Lag3, Prdm1 and Pbx3, and Bat3 knockdown in myelin-antigen-specific CD4(+) T cells markedly inhibits the development of experimental autoimmune encephalomyelitis while promoting the expansion of a dysfunctional Tim-3(hi), interferon-γ (IFN-γ)(lo)CD4(+) cell population. Furthermore, expression of Bat3 is reduced in exhausted Tim-3(+) T cells from mouse tumors and HIV-1-infected individuals. These data indicate that Bat3 acts as an inhibitor of Tim-3-dependent exhaustion and cell death. Bat3 may thus represent a viable therapeutic target in autoimmune disorders, chronic infections and cancers.
Article
Full-text available
Coronary artery disease (CAD) arising from atherosclerosis is a leading cause of death and morbidity worldwide. The underlying pathogenesis involves an imbalanced lipid metabolism and a maladaptive immune response entailing a chronic inflammation of the arterial wall. The disturbed equilibrium of lipid accumulation, immune responses and their clearance is shaped by leukocyte trafficking and homeostasis governed by chemokines and their receptors. New pro- and anti-inflammatory pathways linking lipid and inflammation biology have been discovered, and genetic profiling studies have unveiled variations involved in human CAD. The growing understanding of the inflammatory processes and mediators has uncovered an intriguing diversity of targetable mechanisms that can be exploited to complement lipid-lowering therapies. Here we aim to systematically survey recently identified molecular mechanisms, translational developments and clinical strategies for targeting lipid-related inflammation in atherosclerosis and CAD.
Article
Full-text available
The transmembrane protein Tim-3 has been shown to negatively regulate T-cell-dependent immune responses and was recently demonstrated to be associated with the phenomenon of immune exhaustion, which can occur as a consequence of chronic viral infection. Unlike other negative regulators of T-cell function (e.g., PD-1), Tim-3 does not contain any obvious inhibitory signaling motifs. We have found that ectopic expression of Tim-3 in T cells leads to enhancement of T-cell receptor (TCR)-dependent signaling pathways, which was observed at the level of transcriptional reporters and endogenous cytokine production. We have exploited this observation to dissect what elements within the cytoplasmic tail of Tim-3 are required for coupling to downstream signaling pathways. Here we have demonstrated that two of the more membrane-proximal cytoplasmic tail tyrosines are required for Tim-3 signaling to T-cell activation pathways in a redundant fashion. Furthermore, we show that Tim-3 can directly bind to the Src family tyrosine kinase Fyn and the p85 phosphatidylinositol 3-kinase (PI3K) adaptor. Thus, at least under conditions of short-term stimulation, Tim-3 can augment T-cell activation, although this effect can be blocked by the inclusion of an agonistic antibody to Tim-3. These findings should help further the study of Tim-3 function in other physiological settings, such as those that lead to immune exhaustion.
Article
Full-text available
Atherosclerosis is an inflammatory disease that involves the arterial wall and is characterised by the progressive accumulation of lipids in the vessel wall. The first step is the internalisation of lipids (LDL) in the intima with endothelial activation which enhances the permeability of the endothelial layer and the expression of cytokines/chemokines and adhesion molecules. These events increase LDL particles accumulation in the extracellular matrix where they aggregate/fuse, are retained by proteoglycans and become targets for oxidative and enzymatic modifications. In turn, retained pro-atherogenic LDLs enhance selective leukocyte recruitment and attachment to the endothelial layer inducing their transmigration across the endothelium into the intima. While smooth muscle cell numbers decline with the severity of plaque progression, monocytes differentiate into macrophages, a process associated with the upregulation of pattern recognition receptors including scavenger receptors and Toll-like receptors leading to foam cell formation. Foam cells release growth factors, cytokines, metalloproteinases and reactive oxygen species all of which perpetuate and amplify the vascular remodelling process. In addition, macrophages release tissue factor that, upon plaque rupture, contributes to thrombus formation. Smooth muscle cells exposed in eroded lesions are also able to internalise LDL through LRP-1 receptors acquiring a pro-thrombotic phenotype and releasing tissue factor. Platelets recognise ligands in the ruptured or eroded atherosclerotic plaque, initiate platelet activation and aggregation leading to thrombosis and to the clinical manifestation of the atherothrombotic disease. Additionally, platelets contribute to the local inflammatory response and may also participate in progenitor cell recruitment.
Article
Full-text available
Cellular cholesterol balance induces changes in the inflammatory status of macrophages, and low grade chronic inflammation is increasingly being recognized as one of the key steps in the development of atherosclerosis as well as insulin resistance. Cholesteryl ester hydrolase (CEH) catalyzes the hydrolysis of intracellular stored cholesteryl esters (CEs) and thereby enhances free cholesterol efflux and reduces cellular CE content. We have earlier reported reduced atherosclerosis and lesion necrosis in macrophage-specific CEH transgenic mice on a Ldlr−/− background. In the present study, we tested the hypothesis that reduced intracellular accumulation of CE in macrophages from CEH transgenic mice will attenuate expression of proinflammatory mediators, thereby reducing infiltration into adipose tissue, alleviating inflammation, and resulting in improved insulin sensitivity. Western diet fed Ldlr−/−CEH transgenic mice showed improved insulin sensitivity as assessed by glucose and insulin tolerance tests. Macrophages from CEH transgenic mice expressed significantly lower levels of proinflammatory cytokines (interleukin-1β and interleukin-6) and chemokine (MCP-1; monocyte chemoattractant protein). Attenuation of NF-κB- and AP-1-driven gene expression was determined to be the underlying mechanism. Infiltration of macrophages into the adipose tissue that increases inflammation and impairs insulin signaling was also significantly reduced in Ldlr−/−CEH transgenic mice. In the OP-9 adipocyte peritoneal macrophage co-culture system, macrophages from CEH transgenic mice had a significantly reduced effect on insulin signaling as measured by Akt phosphorylation compared with nontransgenic macrophages. Taken together, these studies demonstrate that macrophage-specific overexpression of CEH decreases expression of proinflammatory mediators and attenuates macrophage infiltration into the adipose tissue, resulting in decreased circulating cytokines and improved insulin sensitivity.
Article
Full-text available
HDL cholesterol levels are decreased in Crohn's disease, a tumor necrosis factor-alpha (TNF-alpha)-driven chronic inflammatory condition involving the gastrointestinal tract. ATP-binding cassette transporter A1 (ABCA1), one of several liver X receptor (LXR) target genes, is a cell surface transporter that mediates the rate-controlling step in HDL synthesis. The regulation of ABCA1 and HDL cholesterol efflux by TNF-alpha was investigated in the human intestinal cell line Caco-2. In response to cholesterol micelles or T0901317, an LXR nonsterol agonist, TNF-alpha decreased the basolateral efflux of cholesterol to apolipoprotein A1 (apoA1). TNF-alpha, by attenuating ABCA1 promoter activity, markedly decreased ABCA1 gene expression without attenuating the expression of LXR-alpha, LXR-beta, and most other LXR target genes, such as ABCG1, FAS, ABCG8, scavenger receptor-B1 (SR-B1), and apoC1. TNF-alpha also decreased ABCA1 mass by markedly enhancing the rate of ABCA1 degradation and modestly inhibiting its rate of synthesis. Inhibitors of the nuclear factor-kappaB (NF-kappaB) pathway, which is activated by TNF-alpha, partially reverse the effect of TNF-alpha on ABCA1 protein expression. The results suggest that TNF-alpha, the major cytokine implicated in the inflammation of Crohn's disease, decreases HDL cholesterol levels by attenuating the expression of intestinal ABCA1 and cholesterol efflux to apoA1.
Article
Full-text available
High levels of the inflammatory cytokine tumor necrosis factor-alpha (TNF-alpha) are present in atherosclerotic lesions. TNF-alpha regulates expression of multiple genes involved in various stages of atherosclerosis, and it exhibits proatherosclerotic and antiatherosclerotic properties. ACAT catalyzes the formation of cholesteryl esters (CE) in monocytes/macrophages, and it promotes the foam cell formation at the early stage of atherosclerosis. We hypothesize that TNF-alpha may be involved in regulating the ACAT gene expression in monocytes/macrophages. In this article, we show that in cultured, differentiating human monocytes, TNF-alpha enhances the expression of the ACAT1 but not ACAT2 gene, increases the cholesteryl ester accumulation, and promotes the lipid-laden cell formation. Several other proinflammatory cytokines tested do not affect the ACAT1 gene expression. The stimulation effect is consistent with a receptor-dependent process, and is blocked by using nuclear factor-kappa B (NF-kappa B) inhibitors. A functional and unique NF-kappa B element located within the human ACAT1 gene proximal promoter is required to mediate the action of TNF-alpha. Our data demonstrate that TNF-alpha, through the NF-kappa B pathway, specifically enhances the expression of human ACAT1 gene to promote the CE-laden cell formation from the differentiating monocytes, and our data support the hypothesis that TNF-alpha is proatherosclerotic during early phase of lesion development.
Article
Obesity is associated with chronic inflammation and is known as a major risk factor for several diseases including chronic kidney disease, diabetes, and cardiovascular diseases. Macrophages play a critical role in the development of obesity-induced inflammation. Efficient delivery of therapeutic anti-inflammatory molecules, such as interleukin (IL)-10, to macrophages can dramatically improve therapeutic efficacy of obesity treatments. We used liposomes containing the 'eat-me' signal phosphatidylserine (PS) (PS-containing liposomes; PSL), which have macrophage targeting ability and anti-inflammatory functions, as a biomaterial carrier for the delivery of IL-10 to macrophages. The IL-10-conjugated PSL (PSL-IL10) showed high affinity for macrophages. In obese mice, PSL-IL10 treatment exhibited significant anti-obesity and anti-inflammatory effects, such as reduced serum total cholesterol, adipocyte size, crown-like structures, proinflammatory cytokine secretion (IL-6 and tumor necrosis factor α) in adipose tissue, liver injury, hepatic steatosis, and inflammation foci, while treatment with IL-10 or PSL alone did not. These findings suggest that the PSL-IL10 has macrophage targeting ability and enhanced anti-inflammatory effect due to the synergistic anti-inflammatory effects of IL-10 and PSL, and can be used as a macrophage-targeted therapeutic material for inflammation-related diseases, including obesity.
Article
Macrophage migration inhibitory factor (MIF), a pleiotropic proinflammatory cytokine, is a key regulator in both innate and acquired immunity system. MIF has become a promising drug target for inflammatory diseases. Apart from its cytokine activities, MIF is known to act as a D-dopachrome tautomerase. Our previous work have identified that 3-[(biphenyl-4-ylcarbonyl)carbamothioyl]amino benzoic acid (Z-590) exhibited a potent inhibitory activity against MIF. In this study, we investigated the effect of Z-590 on lipopolysaccharide (LPS)-activated microglial cell activation. Our results demonstrated Z-590 significantly decreased the production of nitric oxide (NO), tumor necrosis factor-alpha (TNF-α), interleukin (IL)-6, interleukin (IL)-1β, cyclooxygenase (COX-2), inducible nitric oxide synthase (iNOS) as well as reactive oxygen species (ROS) involved in inhibiting MAKPs signaling pathway in LPS-stimulated microglia cells. Furthermore, Z-590 reduced cytotoxicity of activated microglia toward HT-22 hippocampal cells in a microglia-conditioned medium system. Taken together, these results indicated that MIF inhibitor Z-590 elicits a potent inhibitor for microglia-mediated neuroinflammation. This article is protected by copyright. All rights reserved.
Article
Background: Macrophages can imbibe low-density lipoprotein (LDL) through scavenger receptors to become foam cells, which is critical in the initiation and progression of atherosclerosis. Mounting evidence suggests that the anti-inflammatory nature of Chinese herbs have the capacity to halt the complex mechanisms underlying atherosclerosis. This study examined the effects of Chinese herbs on foam cell formation. Methods: Chinese herbs were obtained from the Sun Ten pharmaceutic company. Using oxidized LDL (OxLDL) uptake and a cell toxicity assay, we screened more than 30 types of Chinese herbs. Western blotting was used to determine expressions of scavenger receptors (SRs) and extracellular-signal-regulated kinase (ERK) activities. Results: We found that Gentiana scabra reduced oxidized LDL uptake effectively in THP-1 macrophages (p < 0.05 vs. OxLDL treated control). Moreover, treatment with Gentiana scabra in THP-1 macrophages resulted in decreased expression of scavenger receptor- A (SR-A) (p < 0.05 vs. control). Molecular investigation revealed that Gentiana scabra inhibited SR-A protein expression, possibly by regulating ERK signaling pathways (p < 0.05 vs. control). Conclusions: By regulating SR-A expression, Gentiana scabra reduced oxidized LDL uptake in human macrophages. These results support the potential use of Gentiana scabra in treating atherosclerosis.
Article
ATP-binding cassette transporter A1 (ABCA1), ATP-binding cassette transporter G1 (ABCG1), and scavenger receptor-B1 (SR-B1) promote cholesterol efflux from cells to lipid-poor apolipoprotein A-I and play an important role in the development of atherosclerosis. Liver X receptor (LXRα) and peroxisome proliferator-activated receptor-gamma (PPARγ) operate as cholesterol sensors, which may protect from cholesterol overload by stimulating cholesterol efflux from cells to high-density lipoprotein through ABCA1, ABCG1, and SR-B1. Propofol administration is associated with cardiovascular protective effects, including anti-inflammatory and antioxidant properties. Here, we examined the effect of propofol on ABCA1, ABCG1, and SR-B1 expression and explored whether PPARγ and LXRα were involved in the regulation of propofol-induced ABCA1, ABCG1, and SR-B1 expression in THP-1 macrophage-derived foam cells. Propofol significantly increased expression levels of ABCA1, ABCG1, and SR-B1 in a time-dependent manner. Cellular cholesterol content was decreased while cholesterol efflux was increased by propofol treatment. Moreover, PPARγ and LXRα were up-regulated by propofol treatment. In addition, the up-regulated expression of ABCA1, ABCG1, and SR-B1 by propofol was significantly abolished by both PPARγ siRNA and LXRα siRNA in THP-1 macrophage-derived foam cells. These results provide evidence that propofol up-regulates expression of ABCA1, ABCG1, and SR-B1 through the PPARγ/LXRα pathway in THP-1 macrophage-derived foam cells. Copyright © 2015 Elsevier Inc. All rights reserved.
Article
Immune cells in tumor microenvironment play a prominent role in tumor progression and metastasis. MicroRNA-155 (miR-155) represents an important player in innate and adaptive immunity by regulating differentiation, maturation and activation of macrophages, dendritic cells, B cells and T cells. However, the role of miR-155 expression in immune cells in solid tumor development is less elucidated. Our current study showed that both B16-F10 melanoma and Lewis lung carcinoma (LLC) tumors grew much faster in bic/miR-155 knockout (miR-155-/-) mice along with an increase of myeloid-derived suppressor cells (MDSCs) accumulation in tumors, compared to that in wild-type mice. Bone marrow transplantation study showed that bone marrow miR-155 deficiency could replicate the above tumor-promoting phenotype. In vitro study demonstrated that tumor-infiltrating miR-155-/- MDSCs showed greater migration ability and expressed higher level of multiple chemokines. Furthermore, we found that the level of HIF-1α, a direct target of miR-155, was increased in miR-155 deficient MDSCs, and that the increased HIF-1α up-regulated CXCL1, CXCL3 and CXCL8 expression in MDSCs, contributing to the enhanced recruitment of miR-155-/- MDSCs to the tumors. Moreover, miR-155-/- MDSCs showed enhanced immunosuppressive and pro-angiogenic capacities. Taken together, our study, for the first time, demonstrated that miR-155 deficiency promoted solid tumor growth through increasing the recruitment of MDSCs to tumor microenvironment and enhancing the tumor-promoting functions of the recruited MDSCs. Thus, upregulating miR-155 expression in MDSCs may be developed as a therapeutic approach to halt tumor development. © 2014 Wiley Periodicals, Inc.
Article
Sepsis is a life-threatening condition, but the pathophysiological basis and biomarkers for the monitoring of sepsis and as targets for therapy remain to be determined. We previously showed that Tim-3, a negative immune regulator, is involved in the physiopathology of sepsis, but the underlying mechanisms remain unclear. In the present study, we showed that Tim-3 signaling modulated the response patterns of both macrophages and T helper cells in sepsis. Blockade of the Tim-3 pathway exacerbated sepsis-induced pro-inflammatory macrophage responses and lymphocyte apoptosis during the early phase of sepsis, and enhanced the shift to anti-inflammatory responses for both macrophages and T helper cells during the late phase of sepsis. Tim-3 signaling was found to regulate CD80 and CD86 expression on macrophages both in vivo and in vitro. Co-culture of T cells with Tim-3 knockdown macrophages led to a biased Th2 response, partially explaining how Tim-3 signaling shapes inflammation patterns in vivo. Further studies on this pathway might shed new light on the pathogenesis of sepsis and suggest new approaches for intervention.
Article
microRNA-155 (miR155) plays a critical role in immunity and macrophage inflammation. We aim to investigate the role of miR155 in atherogenesis. Quantitative real-time polymerase chain reaction showed that miR155 was expressed in mouse and human atherosclerotic lesions. miR155 expression in macrophages was correlated positively with proinflammatory cytokine expression. Lentivirus-mediated overexpression of miR155 in macrophages enhanced their inflammatory response to lipopolysaccharide through targeting SOCS-1 and impaired cholesterol efflux from acetylated low-density lipoprotein-loaded macrophages, whereas deficiency of miR155 blunted macrophage inflammatory responses and enhanced cholesterol efflux possibly via enhancing lipid loading-induced macrophage autophagy. We next examined the atherogenesis in apolipoprotein E-deficient (apoE(-/-)) and miR155(-/-)/apoE(-/-) (double knockout) mice fed a Western diet. Compared with apoE(-/-) mice, the double knockout mice developed less atherosclerosis lesion in aortic root, with reduced neutral lipid content and macrophages. Flow cytometric analysis showed that there were increased number of regulatory T cells and reduced numbers of Th17 cells and CD11b+/Ly6C(high) cells in the spleen of double knockout mice. Peritoneal macrophages from the double knockout mice had significantly reduced proinflammatory cytokine expression and secretion both in the absence and presence of lipopolysaccharide stimulation. To determine whether miR155 in leukocytes contributes to atherosclerosis, we performed bone marrow transplantation study. Deficiency of miR155 in bone marrow-derived cells suppressed atherogenesis in apoE(-/-) mice, demonstrating that hematopoietic cell-derived miR155 plays a critical role. miR155 deficiency attenuates atherogenesis in apoE(-/-) mice by reducing inflammatory responses of macrophages, enhancing macrophage cholesterol efflux and resulting in an antiatherogenic leukocyte profile. Targeting miR155 may be a promising strategy to halt atherogenesis.
Article
The T-cell immunoglobulin and mucin domain-(Tim)-1 molecule and Tim-3 are mainly expressed on activated T helper (Th) 2 and Th1 cells, respectively, and have been implicated in the pathogenesis of some autoimmune diseases. Immune thrombocytopenia (ITP) is a common autoimmune disorder, and the complex dysregulation of cellular immunity has been observed; however, the relationship between Tims and excessive immune responses in ITP remains unclear. Using real-time quantitative polymerase chain reaction (RT-PCR), the mRNA expression levels of Tim-1, Tim-3, T-box transcription factor (T-bet) and GATA binding protein 3 (GATA-3) were measured in the peripheral blood mononuclear cells (PBMCs) of 45 newly diagnosed patients with active ITP, 34 ITP patients in remission and 31 healthy volunteers. Tim-3 mRNA expression in PBMCs in newly diagnosed patients was significantly decreased. At the same time, Tim-1 mRNA was not significantly declined, which resulted in a decreased ratio of Tim-3 to Tim-1 in ITP patients with active disease. During the remission stages, the levels of these transcription factors were comparable with those observed in healthy controls. The reduced levels of Tim-3/Tim-1 in PBMCs during active stages of the disease suggest a possible role in the pathogenesis and course of ITP. Regulating the balance of Tim-1 and Tim-3 in ITP patients could also be a therapeutic approach against ITP.
Article
Atherosclerosis is widely appreciated to involve a chronic lipid-induced inflammatory reaction of the arterial wall in response to haemodynamic stress and dyslipidaemia. The dysfunction of resident vascular cells and recruitment of infiltrating leukocyte cells orchestrate a complex interplay in the initiation and development of atherosclerosis. Despite a great many advances in recent years, the detailed mechanisms modulating the inflammation in atherosclerosis have not been fully elucidated. MicroRNAs (miRNAs) are small non-coding RNA (ncRNA) molecules that regulate gene expression post-transcriptionally by degradation and translational repression of target messenger RNAs (mRNAs). Substantial evidence demonstrates that miRNAs play a vital role in the physiological control of gene expression and in the pathogenesis of malignant, infectious, and cardiovascular disorders. MiR-155, a typical multi-functional miRNA, has recently emerged as a novel component of inflammatory signal transduction in the pathogenesis of atherosclerosis. MiR-155-mediated regulation is extensively involved in endothelial cells (ECs), macrophages, dendritic cell (DCs), vascular smooth muscle cells (VSMCs) and differentiation of leukocyte subsets. MiR-155 can modulate the expression of genes correlated with inflammation in different cell types in vitro and also affect the atherogenesis in vivo. However, miR-155 appears to play a conflicting role in the disease pathogenesis. Besides, miR-155 is potentially applied as a novel disease biomarker and therapeutic target in diagnosing and treating atherosclerosis. This article reviews the pertinent literature and mechanisms of action of miR-155 that have thus far been associated with atherosclerosis. Here we first introduce in brief the basic knowledge of the miRNA regulation and later discuss with emphasis the regulatory role of miR-155 in various cell types involved in atherosclerosis.
Article
Objective: Liver is the major organ responsible for the final elimination of cholesterol from the body either as biliary cholesterol or as bile acids. Intracellular hydrolysis of lipoprotein-derived cholesteryl esters (CEs) is essential to generate the free cholesterol required for this process. Earlier, we demonstrated that overexpression of human CE hydrolase (Gene symbol CES1) increased bile acid synthesis in human hepatocytes and enhanced reverse cholesterol transport in mice. The objective of the present study was to demonstrate that liver-specific deletion of its murine ortholog, Ces3, would decrease cholesterol elimination from the body and increase atherosclerosis. Approach and results: Liver-specific Ces3 knockout mice (Ces3-LKO) were generated, and Ces3 deficiency did not affect the expression of genes involved in cholesterol homeostasis and free cholesterol or bile acid transport. The effects of Ces3 deficiency on the development of Western diet-induced atherosclerosis were examined in low density lipoprotein receptor knock out(-/-) mice. Despite similar plasma lipoprotein profiles, there was increased lesion development in low density lipoprotein receptor knock out(-/-)Ces3-LKO mice along with a significant decrease in the bile acid content of bile. Ces3 deficiency significantly reduced the flux of cholesterol from [(3)H]-CE-labeled high-density lipoproteins to feces (as free cholesterol and bile acids) and decreased total fecal sterol elimination. Conclusions: Our results demonstrate that hepatic Ces3 modulates the hydrolysis of lipoprotein-delivered CEs and thereby regulates free cholesterol and bile acid secretion into the feces. Therefore, its deficiency results in reduced cholesterol elimination from the body, leading to significant increase in atherosclerosis. Collectively, these data establish the antiatherogenic role of hepatic CE hydrolysis.
Article
Cellular cholesterol balance induces changes in the inflammatory status of macrophages, and low grade chronic inflammation is increasingly being recognized as one of the key steps in the development of atherosclerosis as well as insulin resistance. Cholesteryl ester hydrolase (CEH) catalyzes the hydrolysis of intracellular stored cholesteryl esters (CEs) and thereby enhances free cholesterol efflux and reduces cellular CE content. We have earlier reported reduced atherosclerosis and lesion necrosis in macrophage-specific CEH transgenic mice on a Ldlr−/− background. In the present study, we tested the hypothesis that reduced intracellular accumulation of CE in macrophages from CEH transgenic mice will attenuate expression of proinflammatory mediators, thereby reducing infiltration into adipose tissue, alleviating inflammation, and resulting in improved insulin sensitivity. Western diet fed Ldlr−/−CEH transgenic mice showed improved insulin sensitivity as assessed by glucose and insulin tolerance tests. Macrophages from CEH transgenic mice expressed significantly lower levels of proinflammatory cytokines (interleukin-1β and interleukin-6) and chemokine (MCP-1; monocyte chemoattractant protein). Attenuation of NF-κB- and AP-1-driven gene expression was determined to be the underlying mechanism. Infiltration of macrophages into the adipose tissue that increases inflammation and impairs insulin signaling was also significantly reduced in Ldlr−/−CEH transgenic mice. In the OP-9 adipocyte peritoneal macrophage co-culture system, macrophages from CEH transgenic mice had a significantly reduced effect on insulin signaling as measured by Akt phosphorylation compared with nontransgenic macrophages. Taken together, these studies demonstrate that macrophage-specific overexpression of CEH decreases expression of proinflammatory mediators and attenuates macrophage infiltration into the adipose tissue, resulting in decreased circulating cytokines and improved insulin sensitivity.
Article
Cholesteryl ester (CE) hydrolysis is the rate-limiting step in the removal of free cholesterol (FC) from macrophage foam cells, and several enzymes have been identified as intracellular CE hydrolases in human macrophages. We have previously reported the antiatherogenic role of a carboxylesterase [carboxylesterase 1 (CES1)], and the objective of the present study was to determine the contribution of CES1 to total CE hydrolytic activity in human macrophages. Two approaches, namely, immune depletion and short hairpin (sh)RNA-mediated knockdown, were used. Immuneprecipitation by a CES1-specific antibody resulted in a 70-80% decrease in enzyme activity, indicating that CES1 is responsible for >70% of the total CE hydrolytic activity. THP1-shRNA cells were generated by stably transfecting human THP1 cells with four different CES1-specific shRNA vectors. Despite a significant (>90%) reduction in CES1 expression both at the mRNA and protein levels, CES1 knockdown neither decreased intracellular CE hydrolysis nor decreased FC efflux. Examination of the underlying mechanisms for the observed lack of effects of CES1 knockdown revealed a compensatory increase in the expression of a novel CES, CES3, which is only expressed at <30% of the level of CES1 in human macrophages. Transient overexpression of CES3 led to an increase in CE hydrolytic activity, mobilization of intracellular lipid droplets, and a reduction in cellular CE content, establishing CES3 as a bona fide CE hydrolase. This study provides the first evidence of functional compensation whereby increased expression of CES3 restores intracellular CE hydrolytic activity and FC efflux in CES1-deficient cells. Furthermore, these data support the concept that intracellular CE hydrolysis is a multienzyme process.
Article
MicroRNAs (miRNAs) have emerged as key gene regulators in diverse biological pathways. These small non-coding RNAs bind to target sequences in mRNAs, typically resulting in repressed gene expression. Several methods are now available for identifying miRNA target sites, but the mere presence of an miRNA-binding site is insufficient for predicting target regulation. Regulation of targets by miRNAs is subject to various levels of control, and recent developments have presented a new twist; targets can reciprocally control the level and function of miRNAs. This mutual regulation of miRNAs and target genes is challenging our understanding of the gene-regulatory role of miRNAs in vivo and has important implications for the use of these RNAs in therapeutic settings.
Article
Cardiovascular disease is the biggest killer globally and the principal contributing factor to the pathology is atherosclerosis; a chronic, inflammatory disorder characterized by lipid and cholesterol accumulation and the development of fibrotic plaques within the walls of large and medium arteries. Macrophages are fundamental to the immune response directed to the site of inflammation and their normal, protective function is harnessed, detrimentally, in atherosclerosis. Macrophages contribute to plaque development by internalizing native and modified lipoproteins to convert them into cholesterol-rich foam cells. Foam cells not only help to bridge the innate and adaptive immune response to atherosclerosis but also accumulate to create fatty streaks, which help shape the architecture of advanced plaques. Foam cell formation involves the disruption of normal macrophage cholesterol metabolism, which is governed by a homeostatic mechanism that controls the uptake, intracellular metabolism, and efflux of cholesterol. It has emerged over the last 20 years that an array of cytokines, including interferon-γ, transforming growth factor-β1, interleukin-1β, and interleukin-10, are able to manipulate these processes. Foam cell targeting, anti-inflammatory therapies, such as agonists of nuclear receptors and statins, are known to regulate the actions of pro- and anti-atherogenic cytokines indirectly of their primary pharmacological function. A clear understanding of macrophage foam cell biology will hopefully enable novel foam cell targeting therapies to be developed for use in the clinical intervention of atherosclerosis.
Article
In atherosclerosis, the accumulation of apolipoprotein B-lipoproteins in the matrix beneath the endothelial cell layer of blood vessels leads to the recruitment of monocytes, the cells of the immune system that give rise to macrophages and dendritic cells. Macrophages derived from these recruited monocytes participate in a maladaptive, nonresolving inflammatory response that expands the subendothelial layer due to the accumulation of cells, lipid, and matrix. Some lesions subsequently form a necrotic core, triggering acute thrombotic vascular disease, including myocardial infarction, stroke, and sudden cardiac death. This Review discusses the central roles of macrophages in each of these stages of disease pathogenesis.
Article
Cardiovascular disease, a leading cause of mortality worldwide, is caused mainly by atherosclerosis, a chronic inflammatory disease of blood vessels. Lesions of atherosclerosis contain macrophages, T cells and other cells of the immune response, together with cholesterol that infiltrates from the blood. Targeted deletion of genes encoding costimulatory factors and proinflammatory cytokines results in less disease in mouse models, whereas interference with regulatory immunity accelerates it. Innate as well as adaptive immune responses have been identified in atherosclerosis, with components of cholesterol-carrying low-density lipoprotein triggering inflammation, T cell activation and antibody production during the course of disease. Studies are now under way to develop new therapies based on these concepts of the involvement of the immune system in atherosclerosis.
Article
It has been proposed that the inflammatory response of monocytes/macrophages induced by oxidized low-density lipoprotein (oxLDL) is a key event in the pathogenesis of atherosclerosis. MicroRNA-155 (miR-155) is an important regulator of the immune system and has been shown to be involved in acute inflammatory response. However, the function of miR-155 in oxLDL-stimulated inflammation and atherosclerosis remains unclear. Here, we show that the exposure of human THP-1 macrophages to oxLDL led to a marked up-regulation of miR-155 in a dose-dependent manner. Silencing of endogenous miR-155 in THP-1 cells using locked nucleic acid-modified antisense oligonucleotides significantly enhanced oxLDL-induced lipid uptake, up-regulated the expression of scavenger receptors (lectinlike oxidized LDL receptor-1, cluster of differentiation 36 [CD36], and CD68), and promoted the release of several cytokines including interleukin (IL)-6, -8, and tumor necrosis factor α (TNF-α). Luciferase reporter assay showed that targeting miR-155 promoted nuclear factor-kappa B (NF-κB) nuclear translocation and potentiated the NF-κB-driven transcription activity. Moreover, miR-155 knockdown resulted in a marked increase in the protein amount of myeloid differentiation primary response gene 88 (MyD88), an important adapter protein used by Toll-like receptors to activate the NF-κB pathway. Our data demonstrate that miR-155 serves as a negative feedback regulator in oxLDL-stimulated THP-1 inflammatory responses and lipid uptake and thus might have potential therapeutic implications in atherosclerosis.
Article
The inflammatory responses of monocytes/macrophages and the stimulation of lipid uptake into these cells by oxidized low density lipoprotein (oxLDL) are critical to the initiation and development of atherosclerosis. Increasing evidence has demonstrated that many microRNAs play important roles in the cell proliferation, apoptosis, and differentiation that accompany inflammatory responses. However, whether microRNAs are associated with monocyte/macrophage inflammatory responses or oxLDL stimulation is not yet known. The aim of the present study is to investigate microRNAs in monocytes/macrophages and their potential role in oxLDL-stimulation of lipid uptake and other atherosclerotic responses. Microarrays were used to analyse the global expression of microRNAs in oxLDL-stimulated human primary peripheral blood monocytes. Expression profiles of the microRNAs were verified using TaqMan real-time PCR. Five microRNAs (microRNA-125a-5p, microRNA-9, microRNA-146a, microRNA-146b-5p, and microRNA-155) were aberrantly expressed after oxLDL treatment of human primary monocytes. Bioinformatics analysis suggested that microRNA-125a-5p is related to a protein similar to ORP9 (oxysterol binding protein-like 9) and this was confirmed by a luciferase reporter assay. MicroRNA-125a-5p was found to mediate lipid uptake and to decrease the secretion of some inflammatory cytokines (interleukin-2, interleukin-6, tumour necrosis factor-alpha, transforming growth factor-beta) in oxLDL-stimulated monocyte-derived macrophages. MicroRNA-125a-5p may partly provide post-transcriptional regulation of the proinflammatory response, lipid uptake, and expression of ORP9 in oxLDL-stimulated monocyte/macrophages.
Article
In the last years small RNA molecules, i.e. microRNA (miRNA) encoded by miR genes, have been found to play a crucial role in regulating gene expression of a considerable part of plant's and animal's genome. Here, we report the essential information on biogenesis of miRNAs and recent evidence on their important role in human diseases. Emphasis has been given to miR-155, since this molecule represents a typical multifunctional miRNA. Recent data indicate that miR-155 has distinct expression profiles and plays a crucial role in various physiological and pathological processes such as haematopoietic lineage differentiation, immunity, inflammation, cancer, and cardiovascular diseases. Moreover, miR-155 has been found to be implicated in viral infections, particularly in those caused by DNA viruses. The available experimental evidence indicating that miR-155 is over expressed in a variety of malignant tumors allows us to include this miRNA in the list of genes of paramount importance in cancer diagnosis and prognosis. Exogenous molecular control in vivo of miR-155 expression could open up new ways to restrain malignant growth and viral infections, or to attenuate the progression of cardiovascular diseases.
Article
The absence of the scavenger receptor A (SR-A)-I/II has produced variable effects on atherosclerosis in different murine models. Therefore, we examined whether SR-AI/II deficiency affected atherogenesis in C57BL/6 mice, an inbred strain known to be susceptible to diet-induced atherosclerotic lesion formation, and whether the deletion of macrophage SR-AI/II expression would modulate lesion growth in C57BL/6 mice and LDL receptor (LDLR)(-/-) mice. SR-AI/II-deficient (SR-AI/II(-/-)) female and male mice on the C57BL/6 background were challenged with a butterfat diet for 30 weeks. No differences were detected in plasma lipids between SR-AI/II(-/-) and SR-AI/II(+/+) mice, whereas both female and male SR-AI/II(-/-) mice had a tremendous reduction (81% to 86%) in lesion area of the proximal aorta compared with SR-AI/II(+/+) mice. Next, to analyze the effect of macrophage-specific SR-AI/II deficiency in atherogenesis, female C57BL/6 mice were lethally irradiated, transplanted with SR-AI/II(-/-) or SR-AI/II(+/+) fetal liver cells, and challenged with the butterfat diet for 16 weeks. In a separate experiment, male LDLR(-/-) mice were reconstituted with SR-AI/II(-/-) or SR-AI/II(+/+) fetal liver cells and challenged with a Western diet for 10 weeks. No significant differences in plasma lipids and lipoprotein profiles were noted between the control and experimental groups in either experiment. SR-AI/II(-/-)-->C57BL/6 mice, however, had a 60% reduction in lesion area of the proximal aorta compared with SR-AI/II(+/+)-->C57BL/6 mice. A similar level of reduction (60%) in lesion area was noted in the proximal aorta and the entire aorta en face of SR-AI/II(-/-)-->LDLR(-/-) mice compared with SR-AI/II(+/+)-->LDLR(-/-) mice. These results demonstrate in vivo that SR-AI/II expression has no impact on plasma lipid levels and that macrophage SR-AI/II contributes significantly to atherosclerotic lesion formation.
Article
The appearance of scavenger receptor class B type I (SR-BI) and ATP-binding cassette transporter A1 (ABCA1) in macrophages and liver implicates these transporters in different stages of reverse cholesterol transport. This review focuses on the role of SR-BI and ABCA1 in reverse cholesterol transport in the context of atherosclerotic lesion development. Recent studies indicate that hepatic expression of ABCA1 and SR-BI is important for the generation of nascent HDL and the delivery of HDL cholesteryl esters to the liver, respectively. Although macrophage SR-BI and ABCA1 do not contribute significantly to circulating HDL levels, the perpetual cycle of HDL lipidation and delipidation by the liver ensures the availability of acceptors for cholesterol efflux that maintain cholesterol homeostasis in arterial macrophages, thereby reducing atherogenesis. In addition to its established role in the selective uptake of HDL cholesteryl esters, there is now evidence that hepatic SR-BI facilitates postprandial lipid metabolism, and that hepatic secretion of VLDL is dependent on ABCA1-mediated nascent HDL formation. Thus, remnant and HDL metabolism are more intimately intertwined in hepatic lipid metabolism than has previously been appreciated. Recent advances in the understanding of the role of ABCA1 and SR-BI in HDL metabolism and their atheroprotective properties indicate the significant potential of modulating ABCA1 and SR-BI expression in both arterial wall macrophages and the liver for the treatment of atherosclerotic coronary artery disease.
MiR-155 regulates interferon-C producti -on in natural killer cells via Tim-3 signalling in chronic hepatitis C virus infection
  • Q C Yong
  • P R Jun
  • Z Juan
Q.C. Yong, P.R. Jun, Z. Juan, et al., MiR-155 regulates interferon-C producti -on in natural killer cells via Tim-3 signalling in chronic hepatitis C virus infection, Immunology 145 (2015) 485-497.
  • M Rangachari
  • C Zhu
  • K Sakuishi
M. Rangachari, C. Zhu, K. Sakuishi, et al., Bat3 promotes T cell responses and F. Zhang et al. Biomedicine & Pharmacotherapy 104 (2018) 645-651
autoimmunity by repressing Tim-3 -mediated cell death and exhaustion
autoimmunity by repressing Tim-3 -mediated cell death and exhaustion, Nat. Med. 18 (2012) 1394-1400.
MiR-155 regulates interferon-C producti -on in natural killer cells via Tim-3 signalling in chronic hepatitis C virus infection
  • Yong