MicroRNA-150 Suppression of Angiopoetin-2 Generation and Signaling Is Crucial for Resolving Vascular Injury

A Tetrahedral Framework DNA-Based Bioswitchable miR-150 Delivery System for Sepsis

Sepsis is a disease with high morbidity and mortality, for which effective treatments are lacking. In recent years, microRNAs (miRs) have been shown to regulate numerous biological processes and can function as therapeutic options for various diseases. However, the poor stability and cell entry properties of miRs have greatly limited their clinical application. In this study, we developed a tetrahedral framework nucleic acid (tFNA)-based bioswitchable miR delivery system (BiRDS) to deliver miR-150 for the treatment of sepsis. BiRDS showed anti-inflammatory effects both in vitro and in vivo by regulating the NF-κB and Notch1 pathways. Therefore, this system holds promise as an ideal candidate for tackling systemic inflammation and multiorgan dysfunction in septic patients in the future.

MicroRNAs in Sepsis

Sepsis is an insidious and frequent condition of severe inflammation due to infections. Several biomarkers have been established for initial screening, but the non-specific nature of the existing biomarkers has led to the investigation of more sensitive and specific tools, such as microRNAs (miRs). These non-coding RNAs are involved in several diseases, including sepsis, due to their roles in cellular homeostasis. Herein, a literature overview was attempted to distinguish the most prominent miRs identified in septic conditions and their usefulness in diagnosis, prognosis and even classification of sepsis. miRs implicated in the regulation of pro and anti-inflammatory mechanisms, such as MIR-146a, MIR-155, MIR-181b, MIR-223-5p, MIR-494-3p, MIR-2055b, MIR-150 and MIR-143 have been pinpointed as acceptable testing tools. Furthermore, the use of miRs as screening panels, specific for septic parameters, such as type of causal infection, inflammation immune pathways affected (NF-kB, STAT/JACK), organs inflicted, as well as parallel screening of certain miRs alongside other long non-coding RNAs (LNCs), as co-regulators of sepsis progression. Overall, miRs exhibit benefits in terms of specificity and sensitivity, as well as practical ease of use and test stability. Furthermore, miRs could offer valuable insights into the molecular basis of disease causality and provide valuable therapeutic information.

Downregulation of miR-4284 can Inhibit the Apoptosis of Human Arterial Smooth Muscle Cells (HASMCs) in Arteriosclerosis Obliterans (ASO)

INTRODUCTION

The disease arteriosclerosis obliterans (ASO) affects the lower extremities. ASO's mechanism involves the proliferation and migration of vascular smooth muscle cells (VSMCs). The miR-4284 is involved in several biological processes of the cardiovascular system, including VSMC proliferation, migration, and death. However, it is unknown if the miR-4284 gene is involved in the control of ASO. Furthermore, the molecular processes behind the contribution of human arterial smooth muscle cells (HASMCs), one of the most significant components of the arterial wall, to arteriosclerosis obliterans (ASO) pathogenesis remain unknown. Previously, we explored the alterations of miRNAs in the blood of ASO patients, and now we wanted to test further whether these changes also take place in the HASMCs that are responsible for the pathogenesis of ASO.

METHODS

The expression levels of miR-29a in arterial walls were analyzed via a real-time polymerase chain reaction. An ASO cell model was established to investigate the expression of miR- 4284 on HASMCs. The Transwell system and CCK-8 detection were used to assess the migration and proliferation of HASMCs. The proportion of apoptotic cells as well as the concentrations of apoptotic signal protein production were assessed using flow cytometry. A Western blot technique was used to identify B cell lymphoma-2 (Bcl2), Bcl2-associated X protein (BAX), as well as Xlinked inhibitors of apoptosis protein (XIAP).

RESULTS

The results showed that PCR confirmed that the qualified production or expression of miR-4284 was significantly reduced in HASMCs after they were cultured without FBS and in an atmosphere of 1% O2 + 5% CO2 + 94% N2 and that glucose had no effect on its expression. MiR- 4284 has no effect on migration and proliferation, but downregulation of miR-4284 can decrease the apoptotic rate of HASMCs, as revealed by flow cytometry. Furthermore, western blot experiments showed that the expression of BAX was low, while the expression of the other two proteins, viz., Bcl2 and XIAP, was over-expressed.

CONCLUSION

We found that miR-4284 downregulation enhanced Bcl2, as well as XIAP, and decreased Bax. This shows that downregulated miR-4284 regulates apoptosis-related protein expression in HASMCs. The mechanism is not clear, and we need further study to confirm it.

MicroRNA-1 protects the endothelium in acute lung injury

Acute lung injury (ALI) and its most severe form, acute respiratory distress syndrome (ARDS), cause severe endothelial dysfunction in the lung, and vascular endothelial growth factor (VEGF) is elevated in ARDS. We found that the levels of a VEGF-regulated microRNA, microRNA-1 (miR-1), were reduced in the lung endothelium after acute injury. Pulmonary endothelial cell-specific (EC-specific) overexpression of miR-1 protected the lung against cell death and barrier dysfunction in both murine and human models and increased the survival of mice after pneumonia-induced ALI. miR-1 had an intrinsic protective effect in pulmonary and other types of ECs; it inhibited apoptosis and necroptosis pathways and decreased capillary leak by protecting adherens and tight junctions. Comparative gene expression analysis and RISC recruitment assays identified miR-1 targets in the context of injury, including phosphodiesterase 5A (PDE5A), angiopoietin-2 (ANGPT2), CNKSR family member 3 (CNKSR3), and TNF-α-induced protein 2 (TNFAIP2). We validated miR-1-mediated regulation of ANGPT2 in both mouse and human ECs and found that in a 119-patient pneumonia cohort, miR-1 correlated inversely with ANGPT2. These findings illustrate a previously unknown role of miR-1 as a cytoprotective orchestrator of endothelial responses to acute injury with prognostic and therapeutic potential.

Potential involvement of circulating extracellular vesicles and particles on exercise effects in malignancies

Physical activity and exercise have been widely related to prevention, treatment, and control for several non-communicable diseases. In this context, there are innumerous pre-clinical and clinical evidence indicating the potential role of exercise, beyond cancer prevention and survival, improved quality of life, including on psychological components, bone health and cachexia, from cancer survivors is described as well. This mini-review raises the potential role of circulating extracellular and particles vesicles (EVPs) cargo, as exerkines, conducting several positive effects on adjacent and/or distant tissues such as tumor, immune, bone and muscle cells. We highlighted new perspectives about microRNAs into EVPs changes induced by exercise and its benefits on malignancies, since microRNAs can be implicated with intricated physiopathological processes. Potential microRNAs into EVPs were pointed out here as players spreading beneficial effects of exercise, such as miR-150-5p, miR-124, miR-486, and miRNA-320a, which have previous findings on involvement with clinical outcomes and as well as tumor microenvironment, regulating intercellular communication and tumor growth. For example, high-intensity interval aerobic exercise program seems to increase miR-150 contents in circulating EVPs obtained from women with normal weight or overweight. In accordance circulating EVPs miR-150-5p content is correlated with prognosis colorectal cancer, and ectopic expression of miR-150 may reduce cell proliferation, invasion and metastasis. Beyond the involvement of bioactive miRNAs into circulating EVPs and their pathways related to clinical and preclinical findings, this mini review intends to support further studies on EVPs cargo and exercise effects in oncology.

Role of miRNA dysregulation in sepsis

Background

Sepsis is defined as a state of multisystem organ dysfunction secondary to a dysregulated host response to infection and causes millions of deaths worldwide annually. Novel ways to counteract this disease are needed and such tools may be heralded by a detailed understanding of its molecular pathogenesis. MiRNAs are small RNA molecules that target mRNAs to inhibit or degrade their translation and have important roles in several disease processes including sepsis.

Main body

The current review adopted a strategic approach to analyzing the widespread literature on the topic of miRNAs and sepsis. A pubmed search of “miRNA or microRNA or small RNA and sepsis not review” up to and including January 2021 led to 1140 manuscripts which were reviewed. Two hundred and thirty-three relevant papers were scrutinized for their content and important themes on the topic were identified and subsequently discussed, including an in-depth look at deregulated miRNAs in sepsis in peripheral blood, myeloid derived suppressor cells and extracellular vesicles.

Conclusion

Our analysis yielded important observations. Certain miRNAs, namely miR-150 and miR-146a, have consistent directional changes in peripheral blood of septic patients across numerous studies with strong data supporting a role in sepsis pathogenesis. Furthermore, a large body of literature show miRNA signatures of clinical relevance, and lastly, many miRNAs deregulated in sepsis are associated with the process of endothelial dysfunction. This review offers a widespread, up-to-date and detailed discussion of the role of miRNAs in sepsis and is meant to stimulate further work in the field due to the potential of these small miRNAs in prompt diagnostics, prognostication and therapeutic agency.

Supplementary Information

The online version contains supplementary material available at 10.1186/s10020-022-00527-z.

Modes of action and diagnostic value of miRNAs in sepsis

Sepsis is a clinical syndrome defined as a dysregulated host response to infection resulting in life-threatening organ dysfunction. Sepsis is a major public health concern associated with one in five deaths worldwide. Sepsis is characterized by unbalanced inflammation and profound and sustained immunosuppression, increasing patient susceptibility to secondary infections and mortality. microRNAs (miRNAs) play a central role in the control of many biological processes, and deregulation of their expression has been linked to the development of oncological, cardiovascular, neurodegenerative and metabolic diseases. In this review, we discuss the role of miRNAs in sepsis pathophysiology. Overall, miRNAs are seen as promising biomarkers, and it has been proposed to develop miRNA-based therapies for sepsis. Yet, the picture is not so straightforward because of the versatile and dynamic features of miRNAs. Clearly, more research is needed to clarify the expression and role of miRNAs in sepsis, and to promote the use of miRNAs for sepsis management.

Cell-Crossing Functional Network Driven by microRNA-125a Regulates Endothelial Permeability and Monocyte Trafficking in Acute Inflammation

Opening of the endothelial barrier and targeted infiltration of leukocytes into the affected tissue are hallmarks of the inflammatory response. The molecular mechanisms regulating these processes are still widely elusive. In this study, we elucidate a novel regulatory network, in which miR-125a acts as a central hub that regulates and synchronizes both endothelial barrier permeability and monocyte migration. We found that inflammatory stimulation of endothelial cells induces miR-125a expression, which consecutively inhibits a regulatory network consisting of the two adhesion molecules VE-Cadherin (CDH5) and Claudin-5 (CLDN5), two regulatory tyrosine phosphatases (PTPN1, PPP1CA) and the transcription factor ETS1 eventually leading to the opening of the endothelial barrier. Moreover, under the influence of miR-125a, endothelial expression of the chemokine CCL2, the most predominant ligand for the monocytic chemokine receptor CCR2, was strongly enhanced. In monocytes, on the other hand, we detected markedly repressed expression levels of miR-125a upon inflammatory stimulation. This induced a forced expression of its direct target gene CCR2, entailing a strongly enhanced monocyte chemotaxis. Collectively, cell-type-specific differential expression of miR-125a forms a synergistic functional network controlling monocyte trafficking across the endothelial barrier towards the site of inflammation. In addition to the known mechanism of miRNAs being shuttled between cells via extracellular vesicles, our study uncovers a novel dimension of miRNA function: One miRNA, although disparately regulated in the cells involved, directs a biologic process in a synergistic and mutually reinforcing manner. These findings provide important new insights into the regulation of the inflammatory cascade and may be of great use for future clinical applications.

Exosomal miR-150 partially attenuated acute lung injury by mediating microvascular endothelial cells and MAPK pathway

BACKGROUND

Acute lung injury (ALI) is a respiratory disease with high morbidity and mortality rates. Currently, there is no effective treatment to complement mechanical ventilation. Exosomes and microRNAs (miRNAs) are promising agents for the management of this disease.

METHODS

Exosomes were isolated from mouse bone marrow stromal stem cells (BMSCs). The levels of two miRNAs, miR-542-3P and miR-150, in exosomes were determined using RT-PCR, and miR-150 was selected for further study. ALI model was established in mice using lipopolysaccharides, and then, they were treated with saline, exosomes, miRNA agomirs, or miRNA antagomirs. The concentrations of TNF-α, IL-6, and IL-1β and the number of neutrophils and macrophages in the bronchoalveolar lavage fluid were measured. The wet/dry weight ratio of the lung tissue was calculated, and tissue pathology and apoptosis were observed using hematoxylin and eosin and terminal deoxynucleotidyl transferase dUTP nick-end labeling staining. CD34 and VE-cadherin expression was detected using immunofluorescence. Proteins associated with apoptosis and MAPK signaling were detected using Western blotting, and miR-150 expression in lung tissue was evaluated using RT-PCR.

RESULTS

We successfully isolated BMSCs and exosomes and showed that the level of miR-150 was significantly higher than that of miR-542-3p. Exosomes and miR-150 reduced inflammation and lung edema while maintaining the integrity of the alveolar structure. They also mitigated microvascular endothelial cell injury by regulating the caspase-3, Bax/Bcl-2, and MAPK signaling.

CONCLUSIONS

Exosomal miR-150 attenuates lipopolysaccharide-induced ALI through the MAPK pathway.

Regulatory Role of Non-Coding RNAs on Immune Responses During Sepsis

Sepsis is resulted from a systemic inflammatory response to bacterial, viral, or fungal agents. The induced inflammatory response by these microorganisms can lead to multiple organ system failure with devastating consequences. Recent studies have shown altered expressions of several non-coding RNAs such as long non-coding RNAs (lncRNAs), microRNAs (miRNAs) and circular RNAs (circRNAs) during sepsis. These transcripts have also been found to participate in the pathogenesis of multiple organ system failure through different mechanisms. NEAT1, MALAT1, THRIL, XIST, MIAT and TUG1 are among lncRNAs that participate in the pathoetiology of sepsis-related complications. miR-21, miR-155, miR-15a-5p, miR-494-3p, miR-218, miR-122, miR-208a-5p, miR-328 and miR-218 are examples of miRNAs participating in these complications. Finally, tens of circRNAs such as circC3P1, hsa_circRNA_104484, hsa_circRNA_104670 and circVMA21 and circ-PRKCI have been found to affect pathogenesis of sepsis. In the current review, we describe the role of these three classes of noncoding RNAs in the pathoetiology of sepsis-related complications.

Ultrasound and Microbubbles for Targeted Drug Delivery to the Lung Endothelium in ARDS: Cellular Mechanisms and Therapeutic Opportunities

Acute respiratory distress syndrome (ARDS) is characterized by increased permeability of the alveolar–capillary membrane, a thin barrier composed of adjacent monolayers of alveolar epithelial and lung microvascular endothelial cells. This results in pulmonary edema and severe hypoxemia and is a common cause of death after both viral (e.g., SARS-CoV-2) and bacterial pneumonia. The involvement of the lung in ARDS is notoriously heterogeneous, with consolidated and edematous lung abutting aerated, less injured regions. This makes treatment difficult, as most therapeutic approaches preferentially affect the normal lung regions or are distributed indiscriminately to other organs. In this review, we describe the use of thoracic ultrasound and microbubbles (USMB) to deliver therapeutic cargo (drugs, genes) preferentially to severely injured areas of the lung and in particular to the lung endothelium. While USMB has been explored in other organs, it has been under-appreciated in the treatment of lung injury since ultrasound energy is scattered by air. However, this limitation can be harnessed to direct therapy specifically to severely injured lungs. We explore the cellular mechanisms governing USMB and describe various permutations of cargo administration. Lastly, we discuss both the challenges and potential opportunities presented by USMB in the lung as a tool for both therapy and research.

Reducing Cardiac Injury during ST-Elevation Myocardial Infarction: A Reasoned Approach to a Multitarget Therapeutic Strategy

The significant reduction in ‘ischemic time’ through capillary diffusion of primary percutaneous intervention (pPCI) has rendered myocardial-ischemia reperfusion injury (MIRI) prevention a major issue in order to improve the prognosis of ST elevation myocardial infarction (STEMI) patients. In fact, while the ischemic damage increases with the severity and the duration of blood flow reduction, reperfusion injury reaches its maximum with a moderate amount of ischemic injury. MIRI leads to the development of post-STEMI left ventricular remodeling (post-STEMI LVR), thereby increasing the risk of arrhythmias and heart failure. Single pharmacological and mechanical interventions have shown some benefits, but have not satisfactorily reduced mortality. Therefore, a multitarget therapeutic strategy is needed, but no univocal indications have come from the clinical trials performed so far. On the basis of the results of the consistent clinical studies analyzed in this review, we try to design a randomized clinical trial aimed at evaluating the effects of a reasoned multitarget therapeutic strategy on the prevention of post-STEMI LVR. In fact, we believe that the correct timing of pharmacological and mechanical intervention application, according to their specific ability to interfere with survival pathways, may significantly reduce the incidence of post-STEMI LVR and thus improve patient prognosis.

Characterization of the whole transcriptome of spleens from Chinese indigenous breed Ningxiang pig reveals diverse coding and non-coding RNAs for immunity regulation

The spatio-temporal expression patterns of RNA and comparisons between different developmental stages have been one of the useful techniques for studying animal physiology and functional gene regulations. A Chinese indigenous breed Ningxiang pig is known for its quality meat production, disease resistance and slow growth performances in pig industry. To gain a better understanding of pig immunity and disease resistance, we comprehensively analyzed the whole transcriptome of the spleens from three important developmental nodes of Ningxiang pig at 30, 90 and 210 days of age. By three ways of comparisons (30vs 90 days, 30 vs 210 days and 90 vs 210 days), a total of 364to 865 differentially expressed mRNAs, 37 to 98 differentially expressed miRNAs,220 to 278 lncRNAs, and 96 to 113 circRNAs were identified. Further analysis of expression patterns, potential function and interactions with miRNAs identified the potential non-coding RNAs related to immunomodulation such as ssc-miRNA-150, ssc-miRNA-497, MSTRG24160, MSTRG18646. The results revealed that miRNAs and circRNAs may have evolved to regulate a large set of biological processes of spleen function in Ningxiang pigs, and circRNAs play a role of miRNA sponges. The results from study is the first report of whole transcriptome analysis of Ningxiang pig spleen and provide new insights into the expression changes of RNAs during the spleen development, which contribute to the phenotypic formation of immunity and disease resistancesin Chinese indigenous pig breeds.

Various aspects of inflammation in heart failure

Despite significant advances in the prevention and treatment of heart failure (HF), the prognosis in patients who have been hospitalised on at least one occasion due to exacerbation of HF is still poor. Therefore, a better understanding of the underlying pathophysiological mechanisms of HF is crucial in order to achieve better results in the treatment of this clinical syndrome. One of the areas that, for years, has aroused the interest of researchers is the activation of the immune system and the elevated levels of biomarkers of inflammation in patients with both ischaemic and non-ischaemic HF. Additionally, it is intriguing that the level of circulating pro-inflammatory biomarkers correlates with the severity of the disease and prognosis in this group of patients. Unfortunately, clinical trials aimed at assessing interventions to modulate the inflammatory response in HF have been disappointing, and the modulation of the inflammatory response has had either no effect or even a negative effect on the HF prognosis. The article presents a summary of current knowledge on the role of immune system activation and inflammation in the pathogenesis of HF. Understanding the immunological mechanisms pathogenetically associated with left ventricular remodelling and progression of HF may open up new therapeutic possibilities for HF.

The effects of sepsis on endothelium and clinical implications

ABSTRACT

Sepsis accounts for nearly 700 000 deaths in Europe annually and is caused by an overwhelming host response to infection resulting in organ failure. The endothelium is an active contributor to sepsis and as such represents a major target for therapy. During sepsis, endothelial cells amplify the immune response and activate the coagulation system. They are both a target and source of inflammation and serve as a link between local and systemic immune responses. In response to cytokines produced by immune cells, the endothelium expresses adhesion molecules and produces vasoactive compounds, inflammatory cytokines, and chemoattractants, thus switching from an anticoagulant to procoagulant state. These responses contribute to local control of infection, but systemic activation can lead to microvascular thrombosis, capillary permeability, hypotension, tissue hypoxia, and ultimately tissue damage. This review focuses on the role of the endothelium in leucocyte adhesion and transmigration as well as production of reactive oxygen and nitrogen species, microRNAs and cytokines, formation of signalling microparticles, and disseminated intravascular coagulation. We also discuss alterations in endothelial permeability and apoptosis. Finally, we review the diagnostic potential of endothelial markers and endothelial pathways as therapeutic targets for this devastating disease.

The Role of MicroRNAs in Acute Respiratory Distress Syndrome and Sepsis, From Targets to Therapies: A Narrative Review

Acute respiratory distress syndrome (ARDS) is a significant cause of morbidity and mortality in the intensive care unit (ICU) and is characterized by lung epithelial and endothelial cell injury, with increased permeability of the alveolar-capillary membrane, leading to pulmonary edema, severe hypoxia, and difficulty with ventilation. The most common cause of ARDS is sepsis, and currently, treatment of ARDS and sepsis has consisted mostly of supportive care because targeted therapies have largely been unsuccessful. The molecular mechanisms behind ARDS remain elusive. Recently, a number of microRNAs (miRNAs) identified through high-throughput screening studies in ARDS patients and preclinical animal models have suggested a role for miRNA in the pathophysiology of ARDS. miRNAs are small noncoding RNAs ranging from 18 to 24 nucleotides that regulate gene expression via inhibition of the target mRNA translation or by targeting complementary mRNA for early degradation. Unsurprisingly, some miRNAs that are differentially expressed in ARDS overlap with those important in sepsis. In addition, circulatory miRNA may be useful as biomarkers or as targets for pharmacologic therapy. This can be revolutionary in a syndrome that has neither a measurable indicator of the disease nor a targeted therapy. While there are currently no miRNA-based therapies targeted for ARDS, therapies targeting miRNA have reached phase II clinical trials for the treatment of a wide range of diseases. Further studies may yield a unique miRNA profile pattern that serves as a biomarker or as targets for miRNA-based pharmacologic therapy. In this review, we discuss miRNAs that have been found to play a role in ARDS and sepsis, the potential mechanism of how particular miRNAs may contribute to the pathophysiology of ARDS, and strategies for pharmacologically targeting miRNA as therapy.

Mechanisms of Endothelial Regeneration and Vascular Repair and Their Application to Regenerative Medicine

Endothelial barrier integrity is required for maintaining vascular homeostasis and fluid balance between the circulation and surrounding tissues and for preventing the development of vascular disease. Despite comprehensive understanding of the molecular mechanisms and signaling pathways that mediate endothelial injury, the regulatory mechanisms responsible for endothelial regeneration and vascular repair are incompletely understood and constitute an emerging area of research. Endogenous and exogenous reparative mechanisms serve to reverse vascular damage and restore endothelial barrier function through regeneration of a functional endothelium and re-engagement of endothelial junctions. In this review, mechanisms that contribute to endothelial regeneration and vascular repair are described. Targeting these mechanisms has the potential to improve outcome in diseases that are characterized by vascular injury, such as atherosclerosis, restenosis, peripheral vascular disease, sepsis, and acute respiratory distress syndrome. Future studies to further improve current understanding of the mechanisms that control endothelial regeneration and vascular repair are also highlighted.

Extracellular vesicles released from p18 overexpressing pulmonary endothelial cells are barrier protective - potential implications for acute respiratory distress syndrome

The novel endosome protein, p18, and the early endosome GTPase, Rab4, play a significant role in protecting the pulmonary vasculature against permeability associated with acute respiratory distress syndrome. Recently, endothelial-derived extracellular vesicles have been identified to play a key role in the endothelial permeability associated with acute respiratory distress syndrome. Therefore, we investigated the effect of these microparticles, released from endothelial cells overexpressing p18 and Rab4, on pulmonary endothelial barrier function. Endothelial-derived extracellular vesicles isolated from lung microvascular endothelial cells which overexpressed cDNA for wild-type p18 protected a naïve monolayer against lipopolysaccharide-induced permeability. In contrast, endothelial-derived extracellular vesicles from cells overexpressing the non-endosomal binding p18 mutant (p18^N39) exerted no protective effect on the endothelial monolayer. Cells overexpressing either dominant active or inactive Rab4 released endothelial-derived extracellular vesicles which had no effect on lipopolysaccharide-induced permeability. miRNA analysis and permeability studies of endothelial-derived extracellular vesicle isolated from wild-type p18-overexpressing cells demonstrates that let-7i-5p, miR-96-5p, and miR-137-3p are endothelial-derived extracellular vesicle cargo which exert protective effects on the pulmonary endothelium. Finally, we observed down-regulation of p18 protein expression in both the lung and endothelium in an in vivo and in vitro model of acute respiratory distress syndrome. These results demonstrate that endothelial-derived extracellular vesicle released from cells overexpressing p18, but not Rab4, contain miRNA cargo which likely promote a barrier-protective effect on the pulmonary endothelium in settings of acute respiratory distress syndrome. Findings indicate the importance of p18 in the pulmonary vasculature and demonstrate that targeting this protein may provide a novel therapeutic strategy to reduce endothelial permeability associated with acute respiratory distress syndrome.

MicroRNA-mediated inflammation and coagulation effects in rats exposed to an inhaled analog of sulfur mustard

Exposure of rats to 2-chloroethyl ethyl sulfide (CEES), an analog of sulfur mustard, can cause acute lung injury (ALI), resulting in increased inflammation and coagulation and altered levels of plasma microRNAs (miRNAs). Rats were exposed to aerosolized CEES and euthanized 12 h later for collection of tissue and plasma. Profiling of miRNAs in plasma, using a TaqMan-based RT-PCR array, revealed 14 differentially expressed miRNAs. Target gene prediction and pathway analysis revealed miRNA-mediated regulation of organismal injury, inflammation, and respiratory diseases. miR-140-5p, a marker of ALI, was downregulated in the plasma, lung, liver, and kidney of CEES-exposed rats, with a concomitant increase in the expression of the inflammation markers IL-6 and IL-1α and the coagulation marker tissue factor (F3). Exposure of rat airway epithelial cells (RL-65) to CEES (0.5 mM) caused cell death and a decrease in miR-140-5p both in cells and media supernatant. This was accompanied by an increase in cellular mRNA levels of IL-6, IL-1α, and F3, as well as FGF9 and EGR2, putative targets of miR-140. Knockdown of miR-140 by specific oligos in RL-65 cells mimicked the in vivo CEES-mediated effects, leading to significantly increased mRNA levels of IL-6, IL-1α, F3, FGF9, and EGR2. Our study identifies miR-140-5p as a mediator of CEES-induced ALI, which could potentially be targeted for therapy.

miR-144-mediated Inhibition of ROCK1 Protects against LPS-induced Lung Endothelial Hyperpermeability

Dysfunctional endothelial cell (EC) barrier and increased lung vascular permeability is a cardinal feature of acute lung injury and sepsis that may result in a pathophysiological condition characterized by alveolar flooding, pulmonary edema, and subsequent hypoxemia. In lung ECs, activation of Rho-associated kinase-1 (ROCK1) phosphorylates myosin light chain (MLC)-associated phosphatase at its inhibitory site, which favors phosphorylation of MLC, stress fiber formation, and hyperpermeability during acute lung injury. The role of microRNA-144 (miR-144) has been well investigated in many human diseases, including cardiac ischemia/reperfusion-induced injury, lung cancer, and lung viral infection; however, its role in pulmonary EC barrier regulation remains obscure. Here, we investigated the miR-144-mediated mechanism in the protection of endothelial barrier function in an LPS-induced lung injury model. By using transendothelial electrical resistance and transwell permeability assay to examine in vitro permeability and immunofluorescence microscopy to determine barrier integrity, we showed that ectopic expression of miR-144 effectively blocked lung EC barrier disruption and hyperpermeability in response to proinflammatory agents. Furthermore, using a gain-and-loss-of-function strategy, overexpression of miR-144 significantly decreased ROCK1 expression. Concomitantly, miR-144 inhibits ROCK1-mediated phosphorylation of MLC phosphatase^Thr853 and thus phosphorylation of MLC^Thr18/Ser19 to counteract stress fiber formation in LPS-activated EC. Finally, in LPS-challenged mice, intranasal delivery of miR-144 mimic via liposomes attenuated endotoxemia-induced increases in lung wet/dry ratio, vascular permeability, and inflammation. In conclusion, these data suggest that miR-144-attenuated activation of inflammatory ROCK1/MLC pathway in vascular ECs is a promising therapeutic strategy to counter inflammatory lung injury.

MicroRNA-34a Promotes Endothelial Dysfunction and Mitochondrial-mediated Apoptosis in Murine Models of Acute Lung Injury

Recent evidence has shown that microRNAs (miRs) are involved in endothelial dysfunction and vascular injury in lung-related diseases. However, the potential role of miR-34a in the regulation of pulmonary endothelial dysfunction, vascular injury, and endothelial cells (ECs) apoptosis in acute lung injury (ALI)/acute lung respiratory distress syndrome is largely unknown. Here, we show that miR-34a-5p was upregulated in whole lungs, isolated ECs from lungs, and ECs stimulated with various insults (LPS and hyperoxia). Overexpression of miR-34a-5p in ECs exacerbated endothelial dysfunction, inflammation, and vascular injury, whereas the suppression of miR-34a-5p expression in ECs and miR-34a-null mutant mice showed protection against LPS- and hyperoxia-induced ALI. Furthermore, we observed that miR-34a-mediated endothelial dysfunction is associated with decreased miR-34a direct-target protein, sirtuin-1, and increased p53 expression in whole lungs and ECs. Mechanistically, we show that miR-34a leads to translocation of p53 and Bax to the mitochondrial compartment with disruption of mitochondrial membrane potential to release cytochrome C into the cytosol, initiating a cascade of mitochondrial-mediated apoptosis in lungs. Collectively, these data show that downregulating miR-34a expression or modulating its target proteins may improve endothelial dysfunction and attenuate ALI.

The relevance of microRNA in post-infarction left ventricular remodelling and heart failure

Myocardial infarction and post-infarction left ventricular remodelling involve a high risk of morbidity and mortality. For this reason, ongoing research is being conducted in order to learn the mechanisms of unfavourable left ventricular remodelling following a myocardial infarction. New biomarkers are also being sought that would allow for early identification of patients with a high risk of post-infarction remodelling and dysfunction of the left ventricle. In recent years, there has been ever more experimental data that confirms the significance of microRNA in cardiovascular diseases. It has been confirmed that microRNAs are stable in systemic circulation, and can be directly measured in patients' blood. It has been found that significant changes occur in the concentrations of various types of microRNA in myocardial infarction and heart failure patients. Various types of microRNA are also currently being intensively researched in terms of their usefulness as markers of cardiomyocyte necrosis, and predictors of the post-infarction heart failure development. This paper is a summary of the current knowledge on the significance of microRNA in post-infarction left ventricular remodelling and heart failure.

Role of Angiopoietin-2 in Vascular Physiology and Pathophysiology

Angiopoietins 1–4 (Ang1–4) represent an important family of growth factors, whose activities are mediated through the tyrosine kinase receptors, Tie1 and Tie2. The best characterized are angiopoietin-1 (Ang1) and angiopoietin-2 (Ang2). Ang1 is a potent angiogenic growth factor signaling through Tie2, whereas Ang2 was initially identified as a vascular disruptive agent with antagonistic activity through the same receptor. Recent data demonstrates that Ang2 has context-dependent agonist activities. Ang2 plays important roles in physiological processes and the deregulation of its expression is characteristic of several diseases. In this review, we summarize the activity of Ang2 on blood and lymphatic endothelial cells, its significance in human physiology and disease, and provide a current view of the molecular signaling pathways regulated by Ang2 in endothelial cells.

Exercise responsive micro ribonucleic acids identify patients with coronary artery disease

Aims

Exercise is a trigger for acute coronary events especially in the untrained. Identifying subjects at risk remains a challenge. We set out to assess whether a distinct pattern of micro ribonucleic acids (miRNAs) expressed in response to an acute bout of all-out exercise might exist that would allow discrimination between health and disease.

Methods

Twenty healthy subjects and 20 patients with coronary artery disease (CAD) performed an all-out cycle ergometry. Total RNA was extracted from blood drawn before and after exercise. Each blood sample was analysed for 187 target miRNAs by quantitative reverse transcription polymerase chain reaction.

Results

At baseline, 18 miRNAs allowed discrimination between healthy subjects and CAD patients. In response to an acute all-out exercise in healthy subjects 51 miRNAs and in CAD patients 60 miRNAs were significantly modulated (all p < 0.05). Using logistic regression analysis, a unique pattern of pre-exercise miR-150-5p, post-exercise miR-101-3p, miR-141-3p and miR-200b-3p together with maximal oxygen uptake and maximal power corrected for bodyweight allowed discrimination between healthy subjects and CAD patients with an accuracy of 92.5%.

Conclusion

In this most comprehensive analysis of exercise effects on circulating miRNAs to date we demonstrate for the first time that a distinct combination of miRNAs together with variables of exercise capacity allow robust discrimination between healthy subjects and CAD patients. We postulate that miRNAs may eventually serve as biomarkers to identify patients with CAD and possibly even those at risk of exercise-induced cardiac events.

MicroRNA dysregulation in lung injury: the role of the miR-26a/EphA2 axis in regulation of endothelial permeability

MicroRNAs (miRNAs) are noncoding RNAs that regulate gene expression in many diseases, although the contribution of miRNAs to the pathophysiology of lung injury remains obscure. We hypothesized that dysregulation of miRNA expression drives the changes in key genes implicated in the development of lung injury. To test our hypothesis, we utilized a model of lung injury induced early after administration of intratracheal bleomycin (0.1 U). Wild-type mice were treated with bleomycin or PBS, and lungs were collected at 4 or 7 days. A profile of lung miRNA was determined by miRNA array and confirmed by quantitative PCR and flow cytometry. Lung miR-26a was significantly decreased 7 days after bleomycin injury, and, on the basis of enrichment of predicted gene targets, it was identified as a putative regulator of cell adhesion, including the gene targets EphA2, KDR, and ROCK1, important in altered barrier function. Lung EphA2 mRNA, and protein increased in the bleomycin-injured lung. We further explored the miR-26a/EphA2 axis in vitro using human lung microvascular endothelial cells (HMVEC-L). Cells were transfected with miR-26a mimic and inhibitor, and expression of gene targets and permeability was measured. miR-26a regulated expression of EphA2 but not KDR or ROCK1. Additionally, miR-26a inhibition increased HMVEC-L permeability, and the disrupted barrier integrity due to miR-26a was blocked by EphA2 knockdown, shown by VE-cadherin staining. Our data suggest that miR-26a is an important epigenetic regulator of EphA2 expression in the pulmonary endothelium. As such, miR-26a may represent a novel therapeutic target in lung injury by mitigating EphA2-mediated changes in permeability.

Novel mechanisms regulating endothelial barrier function in the pulmonary microcirculation

The pulmonary epithelial and vascular endothelial cell layers provide two sequential physical and immunological barriers that together form a semi-permeable interface and prevent alveolar and interstitial oedema formation. In this review, we focus specifically on the continuous endothelium of the pulmonary microvascular bed that warrants strict control of the exchange of gases, fluid, solutes and circulating cells between the plasma and the interstitial space. The present review provides an overview of emerging molecular mechanisms that permit constant transcellular exchange between the vascular and interstitial compartment, and cause, prevent or reverse lung endothelial barrier failure under experimental conditions, yet with a clinical perspective. Based on recent findings and at times seemingly conflicting results we discuss emerging paradigms of permeability regulation by altered ion transport as well as shifts in the homeostasis of sphingolipids, angiopoietins and prostaglandins.

MicroRNA-150 restores endothelial cell function and attenuates vascular remodeling by targeting PTX3 through the NF-κB signaling pathway in mice with acute coronary syndrome

MicroRNAs (miRNAs) have been known to function as important regulators in the vascular system, with various physiopathological effects such as vascular remodeling and hypertension modulation. We aimed to explore whether microRNA-150 (miR-150) regulates endothelial cell function and vascular remodeling in acute coronary syndrome (ACS), and the involvement of PTX3 and NF-κB signaling pathway. Ten normal mice and sixty ApoE^-/- mice were chosen, and their coronary artery tissues and endothelial cells were extracted. ApoE^-/- mice were injected with a series of inhibitor or mimic for miR-150, or siRNA against PTX3. The miR-150 expression, NF-κB1, RELA, and PTX3 mRNA expression were assessed by reverse transcription quantitative polymerase chain reaction, and pentraxin-3, p-P50, and p-P65 protein expression by Western blot analysis. Cell viability and migration were assessed by MTT assay and scratch test. Matrigel tube formation assay was employed to determine vascular remodeling of endothelial cells. The dual-luciferase reporter assay verified that PTX3 was a target of miR-150. Mice with ACS presented with decreased miR-150 but increased PTX3. It was observed that the miR-150 mimic and siRNA against PTX3 reduced levels of PTX3, NF-κB1, and RELA in mice, and the miR-150 inhibitor reversed the tendency. The in vitro cell experimentation proved that miR-150 might facilitate endothelial cell proliferation, migration, and restrain vascular remodeling via inhibiting PTX3 expression. On the basis of the results of this study, it was hypothesized that miR-150 could possibly maintain endothelial cell function and suppress vascular remodeling by inhibiting PTX3 through the NF-κB signaling pathway in mice with ACS.

The role of microRNAs in prethrombotic status associated with coronary artery disease

The acute cardiovascular events following thrombus formation is a primary cause of morbidity and mortality of patients with coronary artery disease (CAD). Numerous studies have shown that a prethrombotic status, which can be defined as an imbalance between the procoagulant and anticoagulant conditions, would exist for a period of time before thrombogenesis. Therefore, early diagnosis and intervention of prethrombotic status are important for reducing acute cardiovascular events. However, none of prethrombotic indicators have been identified as golden standard for diagnosis of prethrombotic status to date. MicroRNAs (miRNAs), a class of short non-coding RNAs, have been shown to be involved in pathophysiologic processes related to prethrombotic status, such as endothelial dysfunction, platelet activation, impaired fibrinolysis and elevated procoagulant factors, etc. Owing to their multiple and fine-tuning impacts on gene expression, miRNAs raise a novel understanding in the underlying mechanism of prethrombotic status. This review aims to discuss the role of miRNAs in prethrombotic status, especially the differently expressed miRNAs in CAD, which may be meaningful for developing promising diagnostic biomarkers and therapeutic strategies for CAD patients in future.

Long noncoding RNA FOXD3-AS1 regulates oxidative stress-induced apoptosis via sponging microRNA-150

The function of most human long noncoding RNAs (lncRNAs) remains unclear. Our studies identified a highly up-regulated mammalian lncRNA, FOXD3-AS1, known as linc1623 in mice, in the setting of hyperoxia/reactive oxygen species (ROS)-induced lung injury. We found that ROS induced a robust expression of FOXD3-AS1 in mouse lung tissue. Functionally, FOXD3-AS1 promoted oxidative stress-induced lung epithelial cell death. In human lung epithelial cells, the microRNA-150 (miR-150) was identified to interact with FOXD3-AS1; this finding was confirmed using the luciferase reporter assays. Consistently, mutation on the miR-150 pairing sequence in FOXD3-AS1 abolished the interactions between FOXD3-AS1 and miR-150. Additionally, miR-150 mimics suppressed the level of FOXD3-AS1. The antisense oligos of FOXD3-AS1 significantly augmented the intracellular level of miR-150, supporting the theory of sponging effects of FOXD3-AS1 on miR-150. We further investigated the cellular function of miR-150 in our lung injury models. MiR-150 conferred a cytoprotective role in lung epithelial cells after oxidative stress, whereas FOXD3-AS1 promoted cell death. Taken together, our studies indicated that FOXD3-AS1 serves as a sponge or as a competing endogenous noncoding RNA for miR-150, restricting its capability to promote cell growth and thereby exaggerating hyperoxia-induced lung epithelial cell death.-Zhang, D., Lee, H., Haspel, J. A., Jin, Y. Long noncoding RNA FOXD3-AS1 regulates oxidative stress-induced apoptosis via sponging microRNA-150.

Roles of miR‑4463 in H2O2‑induced oxidative stress in human umbilical vein endothelial cells

Oxidative stress is implicated in the pathophysiology of vascular diseases, including atherosclerosis, aneurysm and arteriovenous fistula. A previous study from our lab suggested that microRNA (miR)-4463 may be involved in the pathogenesis of vascular disease; however, the roles of oxidative stress in the molecular mechanisms underlying the actions of miR-4463 in vascular disease have yet to be elucidated. The aim of the present study was to investigate the role of miR-4463 in hydrogen peroxide (H₂O₂)-induced oxidative stress in human umbilical vein endothelial cells (HUVECs). Reverse transcription-quantitative polymerase chain reaction was used to assess the expression levels of miR-4463 in HUVECs treated with various concentrations of H₂O₂. Flow cytometry was used to evaluate the percentage of apoptotic cells, and the protein expression levels of the apoptotic markers cleaved (C)-caspase3, poly (adenosine diphosphate-ribose) polymerase 1 (PARP1), B cell lymphoma-2 (Bcl-2), Bcl-2-associated X protein (Bax) and X-linked inhibitor of apoptosis protein (XIAP) were determined using western blot analysis. The results demonstrated that the apoptotic rate of HUVECs was increased following treatment with H₂O₂ in a concentration-dependent manner, and the expression of miR-4463 was also upregulated in a dose-dependent manner. Following transfection with miR-4463 mimics, the levels of malondialdehyde and reactive oxygen species were increased in HUVECs, with a corresponding increase in the apoptotic rate. Furthermore, western blot analysis revealed that the protein expression levels of C-caspase3, PARP1 and Bax were upregulated, whereas the levels of Bcl-2 and XIAP were downregulated. In conclusion, the present findings suggested that the upregulation of miR-4463 may enhance H₂O₂-induced oxidative stress and promote apoptosis in HUVECs in vitro.

Protein Interactions at Endothelial Junctions and Signaling Mechanisms Regulating Endothelial Permeability

The monolayer of endothelial cells lining the vessel wall forms a semipermeable barrier (in all tissue except the relatively impermeable blood-brain and inner retinal barriers) that regulates tissue-fluid homeostasis, transport of nutrients, and migration of blood cells across the barrier. Permeability of the endothelial barrier is primarily regulated by a protein complex called adherens junctions. Adherens junctions are not static structures; they are continuously remodeled in response to mechanical and chemical cues in both physiological and pathological settings. Here, we discuss recent insights into the post-translational modifications of junctional proteins and signaling pathways regulating plasticity of adherens junctions and endothelial permeability. We also discuss in the context of what is already known and newly defined signaling pathways that mediate endothelial barrier leakiness (hyperpermeability) that are important in the pathogenesis of cardiovascular and lung diseases and vascular inflammation.

STIM1 Phosphorylation at Y361 Recruits Orai1 to STIM1 Puncta and Induces Ca2+ Entry

Store-operated Ca²⁺ entry (SOCE) mediates the increase in intracellular calcium (Ca²⁺) in endothelial cells (ECs) that regulates several EC functions including tissue-fluid homeostasis. Stromal-interaction molecule 1 (STIM1), upon sensing the depletion of (Ca²⁺) from the endoplasmic reticulum (ER) store, organizes as puncta that trigger store-operated Ca²⁺ entry (SOCE) via plasmalemmal Ca²⁺-selective Orai1 channels. While the STIM1 and Orai1 binding interfaces have been mapped, signaling mechanisms activating STIM1 recruitment of Orai1 and STIM1-Orai1 interaction remains enigmatic. Here, we show that ER Ca²⁺-store depletion rapidly induces STIM1 phosphorylation at Y361 via proline-rich kinase 2 (Pyk2) in ECs. Surprisingly, the phospho-defective STIM1-Y361F mutant formed puncta but failed to recruit Orai1, thereby preventing. SOCE Furthermore, studies in mouse lungs, expression of phosphodefective STIM1-Y361F mutant in ECs prevented the increase in vascular permeability induced by the thrombin receptor, protease activated receptor 1 (PAR1). Hence, Pyk2-dependent phosphorylation of STIM1 at Y361 is a critical phospho-switch enabling recruitment of Orai1 into STIM1 puncta leading to SOCE. Therefore, Y361 in STIM1 represents a novel target for limiting SOCE-associated vascular leak.

MicroRNA-150 targets ELK1 and modulates the apoptosis induced by ox-LDL in endothelial cells

Atherosclerosis, a chronic inflammatory disease, is the major cause of life-threatening complications such as myocardial infarction and stroke. Endothelial cells (ECs) apoptosis plays a vital role in the initiation and progression of atherosclerosis. Although a subset of microRNAs (miRNAs) have been identified as critical regulators of atherosclerosis, studies on their participation in endothelial apoptosis in atherosclerosis have been limited. In the current study, we show that miRNA-150 (miR-150) expression was substantially up-regulated during the oxidized low-density lipoprotein (ox-LDL)-induced apoptosis in human umbilical cord vein endothelial cells (HUVECs). Forced expression of miR-150 enhanced apoptosis in ECs, whereas inhibition of miR-150 could partly alleviate apoptotic cell death mediated by ox-LDL. Further analysis identified ELK1 as a direct target of miR-150, and ELK1 knockdown abolished the anti-apoptotic effect of miR-150 inhibitor. These findings reveal a novel role of miR-150 in endothelial apoptosis and indicate a therapeutic potential of miR-150 for endothelial dysfunction and atherosclerosis.

The involvement of regulatory non-coding RNAs in sepsis: a systematic review

Background

Sepsis coincides with altered gene expression in different tissues. Accumulating evidence has suggested that microRNAs, long non-coding RNAs, and circular RNAs are important molecules involved in the crosstalk with various pathways pertinent to innate immunity, mitochondrial functions, and apoptosis.

Methods

We searched articles indexed in PubMed (MEDLINE), EMBASE and Europe PubMed Central databases using the Medical Subject Heading (MeSH) or Title/Abstract words (“microRNA”, “long non-coding RNA”, “circular RNA”, “sepsis” and/or “septic shock”) from inception to Sep 2016. Studies investigating the role of host-derived microRNA, long non-coding RNA, and circular RNA in the pathogenesis of and as biomarkers or therapeutics in sepsis were included. Data were extracted in terms of the role of non-coding RNAs in pathogenesis, and their applicability for use as biomarkers or therapeutics in sepsis. Two independent researchers assessed the quality of studies using a modified guideline from the Systematic Review Center for Laboratory animal Experimentation (SYRCLE), a tool based on the Cochrane Collaboration Risk of Bias tool.

Results

Observational studies revealed dysregulation of non-coding RNAs in septic patients. Experimental studies confirmed their crosstalk with JNK/NF-κB and other cellular pathways pertinent to innate immunity, mitochondrial function, and apoptosis. Of the included studies, the SYRCLE scores ranged from 3 to 7 (average score of 4.55). This suggests a moderate risk of bias. Of the 10 articles investigating non-coding RNAs as biomarkers, none of them included a validation cohort. Selective reporting of sensitivity, specificity, and receiver operating curve was common.

Conclusions

Although non-coding RNAs appear to be good candidates as biomarkers and therapeutics for sepsis, their differential expression across tissues complicated the process. Further investigation on organ-specific delivery of these regulatory molecules may be useful.

Electronic supplementary material

The online version of this article (doi:10.1186/s13054-016-1555-3) contains supplementary material, which is available to authorized users.

MicroRNA Regulation of Endothelial Junction Proteins and Clinical Consequence

Cellular junctions play a critical role in structural connection and signal communication between cells in various tissues. Although there are structural and functional varieties, cellular junctions include tight junctions, adherens junctions, focal adhesion junctions, and tissue specific junctions such as PECAM-1 junctions in endothelial cells (EC), desmosomes in epithelial cells, and hemidesmosomes in EC. Cellular junction dysfunction and deterioration are indicative of clinical diseases. MicroRNAs (miRNA) are ~20 nucleotide, noncoding RNAs that play an important role in posttranscriptional regulation for almost all genes. Unsurprisingly, miRNAs regulate junction protein gene expression and control junction structure integrity. In contrast, abnormal miRNA regulation of junction protein gene expression results in abnormal junction structure, causing related diseases. The major components of tight junctions include zonula occluden-1 (ZO-1), claudin-1, claudin-5, and occludin. The miRNA regulation of ZO-1 has been intensively investigated. ZO-1 and other tight junction proteins such as claudin-5 and occludin were positively regulated by miR-126, miR-107, and miR21 in different models. In contrast, ZO-1, claudin-5, and occludin were negatively regulated by miR-181a, miR-98, and miR150. Abnormal tight junction miRNA regulation accompanies cerebral middle artery ischemia, brain trauma, glioma metastasis, and so forth. The major components of adherens junctions include VE-cadherin, β-catenin, plakoglobin, P120, and vinculin. VE-cadherin and β-catenin were regulated by miR-9, miR-99b, miR-181a, and so forth. These regulations directly affect VE-cadherin-β-catenin complex stability and further affect embryo and tumor angiogenesis, vascular development, and so forth. miR-155 and miR-126 have been shown to regulate PECAM-1 and affect neutrophil rolling and EC junction integrity. In focal adhesion junctions, the major components are integrin β4, paxillin, and focal adhesion kinase (FAK). Integrin β4 has been regulated by miR-184, miR-205, and miR-9. Paxillin has been regulated by miR-137, miR-145, and miR-218 in different models. FAK has been regulated by miR-7, miR-138, and miR-135. Deregulation of miRNAs is caused by viral infections, tumorigenesis, and so forth. By regulation of posttranscription, miRNAs manipulate junction protein expression in all cellular processes and further determine cellular fate and development. Elucidation of these regulatory mechanisms will become a new alternative therapy for many diseases, such as cancers and inflammatory diseases.

microRNA-150 inhibits the formation of macrophage foam cells through targeting adiponectin receptor 2

Transformation of macrophages into foam cells plays a critical role in the pathogenesis of atherosclerosis. The aim of this study was to determine the expression and biological roles of microRNA (miR)-150 in the formation of macrophage foam cells and to identify its functional target(s). Exposure to 50 μg/ml oxidized low-density lipoprotein (oxLDL) led to a significant upregulation of miR-150 in THP-1 macrophages. Overexpression of miR-150 inhibited oxLDL-induced lipid accumulation in THP-1 macrophages, while knockdown of miR-150 enhanced lipid accumulation. apoA-I- and HDL-mediated cholesterol efflux was increased by 66% and 43%, respectively, in miR-150-overexpressing macrophages relative to control cells. In contrast, downregulation of miR-150 significantly reduced cholesterol efflux from oxLDL-laden macrophages. Bioinformatic analysis and luciferase reporter assay revealed adiponectin receptor 2 (AdipoR2) as a direct target of miR-150. Small interfering RNA-mediated downregulation of AdipoR2 phenocopied the effects of miR-150 overexpression, reducing lipid accumulation and facilitating cholesterol efflux in oxLDL-treated THP-1 macrophages. Knockdown of AdipoR2 induced the expression of proliferator-activated receptor gamma (PPARγ), liver X receptor alpha (LXRα), ABCA1, and ABCG1. Moreover, pharmacological inhibition of PPARγ or LXRα impaired AdipoR2 silencing-induced upregulation of ABCA1 and ABCG1. Taken together, our results indicate that miR-150 can attenuate oxLDL-induced lipid accumulation in macrophages via promotion of cholesterol efflux. The suppressive effects of miR-150 on macrophage foam cell formation are mediated through targeting of AdipoR2. Delivery of miR-150 may represent a potential approach to prevent macrophage foam cell formation in atherosclerosis.