MicroRNA-155 modulates the interleukin-1 signaling pathway in activated human monocyte-derived dendritic cells. Proc Natl Acad Sci U S A. 2009;106:2735-2740. [PMID: 19193853 DOI: 10.1073/pnas.0811073106]

Critical Role of Alternative M2 Skewing in miR-155 Deletion-Mediated Protection of Colitis

Inflammatory bowel disease (IBD) is associated with dysregulation of both innate and adaptive immune response in the intestine. MicroRNA (miR)-155 is frequently expressed and functions in many immune cell types. Besides its function in adaptive immunity, miR-155 is a key regulator of the innate immune response in macrophages, dendritic cells, and even in epithelia cells. Although the roles of miR-155 within T and B lymphocytes in colitis have been reported, its function in innate immune cells has not been thoroughly examined. In this study, the dextran sulfate sodium (DSS)-induced colitis model was established in wild-type (WT) and miR-155^−/− mice. Our results showed that miR-155 deficiency in macrophages recapitulated the alleviated colitis feature of miR-155^−/− mice and appeared to skew toward the alterative M2 phenotype. Notably, the predominance of M2 in colon can result in dampened intestinal immune cell proliferation and inhibit CD4 T cell polarization toward Th1 and Th17. Moreover, C/EBPβ and SOCS1 were demonstrated as two key functional targets in this process. We also provided evidence for use of miR-155 inhibitor to treat colitis. Collectively, the findings highlight the central role of alternative M2 skewing for miR-155 function in colitis and reveal that macrophages might be a main target for therapeutics.

Regulatory mechanism of ulinastatin on autophagy of macrophages and renal tubular epithelial cells

Kidney ischemia and hypoxia can cause renal cell apoptosis and activation of inflammatory cells, which lead to the release of inflammatory factors and ultimately result in the damage of kidney tissue and the whole body. Renal tubular cell and macrophage autophagy can reduce the production of reactive oxygen species (ROS), thereby reducing the activation of inflammatory cytoplasm and its key effector protein, caspase-1, which reduces the expression of IL-1β and IL-18 and other inflammatory factors. Ulinastatin (UTI), as a glycoprotein drug, inhibits the activity of multiple proteases and reduces myocardial damage caused by ischemia-reperfusion by upregulating autophagy. However, it can be raised by macrophage autophagy, reduce the production of ROS, and ultimately reduce the expression of inflammatory mediators, thereby reducing renal cell injury, promote renal function recovery is not clear. In this study, a series of cell experiments have shown that ulinastatin is reduced by regulating the autophagy of renal tubular epithelial cells and macrophages to reduce the production of reactive oxygen species and inflammatory factors (TNF-α, IL-1β and IL-1), and then, increase the activity of the cells under the sugar oxygen deprivation model. The simultaneous use of cellular autophagy agonists Rapamycin (RAPA) and ulinastatin has a synergistic effect on the production of reactive oxygen species and the expression of inflammatory factors.

Identification of key genes and pathways in regulating immune‑induced diseases of dendritic cells by bioinformatic analysis

Dendritic cells (DCs) serve crucial roles in the activation of the immune response, and imbalance in the activation or inhibition of DCs has been associated with an increased susceptibility to develop immune-induced diseases. However, the molecular mechanisms of regulating immune-induced diseases of DCs are not well understood. The aim of the present study was to identify the gene signatures and uncover the potential regulatory mechanisms in DCs. A total of 4 gene expression profiles (GSE52894, GSE72893, GSE75938 and GSE77969) were integrated and analyzed in depth. In total, 241 upregulated genes and 365 downregulated genes were detected. Gene ontology and pathway enrichment analysis showed that the differentially expressed genes (DEGs) were significantly enriched in the inflammatory response, the tumor necrosis factor (TNF) signaling pathway, the nuclear factor (NF)-κB signaling pathway and antigen processing. The top 10 hub genes were identified from the protein-protein analysis. The most significant 2 modules were filtered from the protein-protein network. The genes in 2 modules were involved in type I interferon signaling, the NF-κB signaling pathway and the TNF signaling pathway. Furthermore, the microRNA-mRNA network analysis was performed. The results of the present study revealed that the identified DEGs and pathways may improve our understanding of the mechanisms of the maturation of DCs, and the candidate hub genes that may be therapeutic targets for immune-induced diseases.

MiR-146a negatively regulates dectin-1-induced inflammatory responses

Dectin-1 is the critical sensor for β-glucan from Candida which is the most common human fungal pathogen and cause superficial and system infection. MicroRNAs (miRNAs) play crucial roles in regulating innate immunity. However, the functional role of miRNAs in inflammatory response dependent on the activation of dectin-1 pathway has not been defined. In the present study, we found insoluble β-glucan from the cell wall of Candida albicans (CaIG) was able to increase the production of of IL-6 and TNFα through Dectin-1-Syk-NF-κB and p38MAPK pathway. MiRNAs profiles combined with real-time PCR validation revealed that miR-146a, miR-30-5p, miR-210-3p expression level were increased in THP-1 cells treated with CaIG. The interaction between Dectin-1 and CaIG resulted in an long lasting increase of miR-146a expression dependent on Dectin-1-Syk-NF-κB, p38MAPK, contrasting with a rapid and transient increase of IL-6 and TNFα. Overexpression of miR-146a significantly suppressed the production of IL-6 and TNFα. MiR-146a mimics inhibited CaIG-induced activity of p-IκBα and translocation of NF-κB p65. Luciferase reporter assays showed miR-146a inhibited NF-κB promoter-binding activity. Together, our data suggest miR-146a may play the potent negative feedback regulator in inflammatory response following Dectin-1 stimulation.

Endothelial microRNAs regulating the NF-κB pathway and cell adhesion molecules during inflammation

The surface of endothelial cells is covered with cell adhesion molecules, including E-selectin, intercellular adhesion molecule 1 (ICAM-1), and vascular cell adhesion molecule 1 (VCAM- 1) , that mediate the adhesion and extravasation of leukocytes and play pivotal roles in inflammatory response. microRNAs (miRNAs) regulate the expression of these important cell adhesion molecules through two distinct major mechanisms, namely via modulating the proinflammatory NF-κB pathway, which controls their transcription, and via directly targeting them. The present review highlights the role of various miRNAs in controlling the expression of E-selectin, ICAM-1, and VCAM-1: a type of regulation that can be harnessed for therapeutic prevention of inflammation-associated diseases such as atherosclerosis and sepsis. The roles of secreted miRNAs as paracrine regulators, and cell adhesion molecule-based miRNA delivery are also addressed.-Zhong, L., Simard, M. J., Huot, J. Endothelial microRNAs regulating the NF-κB pathway and cell adhesion molecules during inflammation.

MiR-155 Alleviates Septic Lung Injury by Inducing Autophagy Via Inhibition of Transforming Growth Factor-β-Activated Binding Protein 2

BACKGROUND

The anti-inflammatory effect of miR-155 was closely linked to transforming growth factor-β-activated kinase-1-binding protein 2 (TAB2) and autophagy. This study investigated the role of miR-155 in attenuation of septic lung injury through TAB2 and autophagy in mouse model and in vitro.

METHODS

Patients who underwent fiberoptic bronchoscope examination with or without septic lung injury were recruited for the collection of bronchoalveolar lavage fluid (BALF) samples. Mouse model of septic lung injury was established by cecal ligation puncture, while alveolar macrophage cell line was treated with lipopolysaccharide (LPS). Agomir miR-155 transfection into the mouse airways was performed to induce miR-155 expression, while miR-155 mimic, miR-155 inhibitor, or TAB2-siRNA was transfected into NR8383 macrophages. Mouse BALF and cell cytokine levels, lung tissue pathology and wet/dry ratio, numbers of autophagy bodies, miR-155, gene and protein expressions were also examined accordingly.

RESULTS

Expression of miR-155 was increased in the BALF of septic lung injury patients, in mouse model and NR8383 macrophages after LPS treatment. Increased numbers of autophagy bodies were also observed in mouse and macrophage models. MiR-155-transfected mice showed alleviation of inflammation, lower water content in lung tissues, increased number of autophagy bodies, increased expression of microtubule-associated protein 1 light chain 3 (LC3 II/I), reduced expressions of cysteinyl aspartate-specific protease-1 (Caspase-1), and TAB2, and decreased cytokines levels. Similar results were obtained in macrophages after LPS treatment. Cells transfected with miR-155 inhibitor showed increased expression of TAB2 and Caspase-1, fewer autophagy bodies, lower LC3 II/I expression, and higher cytokine levels.

CONCLUSION

The current study observed a higher level of miR-155 in the BALF from sepsis patients with acute respiratory distress syndrome and demonstrated that miR-155 alleviated inflammation in septic lung injury in mouse and cell models by inducing autophagy via inhibition of TAB2.

Emerging Mechanisms of Innate Immunity and Their Translational Potential in Inflammatory Bowel Disease

Activation of the innate immune system through pattern-recognition receptor (PRR) signaling plays a pivotal role in the early induction of host defense following exposure to pathogens. Loss of intestinal innate immune regulation leading aberrant immune responses has been implicated in the pathogenesis of inflammatory bowel disease (IBD). The precise role of PRRs in gut inflammation is not well understood, but considering their role as bacterial sensors and their genetic association with IBD, they likely contribute to dysregulated immune responses to the commensal microbiota. The purpose of this review is to evaluate the emerging functions of PRRs including their functional cross-talk, how they respond to mitochondrial damage, induce mitophagy or autophagy, and influence adaptive immune responses by interacting with the antigen presentation machinery. The review also summarizes some of the recent attempts to harness these pathways for therapeutic approaches in intestinal inflammation.

Cas9-mediated excision of proximal DNaseI/H3K4me3 signatures confers robust silencing of microRNA and long non-coding RNA genes

CRISPR/Cas9-based approaches have greatly facilitated targeted genomic deletions. Contrary to coding genes however, which can be functionally knocked out by frame-shift mutagenesis, non-coding RNA (ncRNA) gene knockouts have remained challenging. Here we present a universal ncRNA knockout approach guided by epigenetic hallmarks, which enables robust gene silencing even in provisionally annotated gene loci. We build on previous work reporting the presence of overlapping histone H3 lysine 4 tri-methylation (H3K4me3) and DNaseI hypersensitivity sites around the transcriptional start sites of most genes. We demonstrate that excision of this gene-proximal signature leads to loss of microRNA and lincRNA transcription and reveals ncRNA phenotypes. Exemplarily we demonstrate silencing of the constitutively transcribed MALAT1 lincRNA gene as well as of the inducible miR-146a and miR-155 genes in human monocytes. Our results validate a role of miR-146a and miR-155 in negative feedback control of the activity of inflammation master-regulator NFκB and suggest that cell-cycle control is a unique feature of miR-155. We suggest that our epigenetically guided CRISPR approach may improve existing ncRNA knockout strategies and contribute to the development of high-confidence ncRNA phenotyping applications.

MicroRNA-155-at the Critical Interface of Innate and Adaptive Immunity in Arthritis

MicroRNAs (miRNAs) are small non-coding RNAs that fine-tune the cell response to a changing environment by modulating the cell transcriptome. miR-155 is a multifunctional miRNA enriched in cells of the immune system and is indispensable for the immune response. However, when deregulated, miR-155 contributes to the development of chronic inflammation, autoimmunity, cancer, and fibrosis. Herein, we review the evidence for the pathogenic role of miR-155 in driving aberrant activation of the immune system in rheumatoid arthritis, and its potential as a disease biomarker and therapeutic target.

Dengue virus causes changes of MicroRNA-genes regulatory network revealing potential targets for antiviral drugs

BACKGROUND

Dengue virus (DENV) is an increasing global health threat and associated with induction of both a long-lived protective immune response and immune-suppression. So far, the potency of treatment of DENV via antiviral drugs is still under investigation. Recently, increasing evidences suggest the potential role of microRNAs (miRNAs) in regulating DENV. The present study focused on the function of miRNAs in innate insusceptible reactions and organization of various types of immune cells and inflammatory responses for DENV. Three drugs were tested including antiviral herbal medicine ReDuNing (RDN), Loratadine (LRD) and Acetaminophen.

RESULTS

By the microarray expression of miRNAs in 165 Patients. Results showed that 89 active miRNAs interacted with 499 potential target genes, during antiviral treatment throughout the critical stage of DENV. Interestingly, reduction of the illness threats using RDN combined with LRD treatment showed better results than Acetaminophen alone. The inhibitions of DENV was confirmed by decrease concentrations of cytokines and interleukin parameters; like TNF-α, IFN-γ, TGF-β1, IL-4, IL-6, IL-12, and IL-17; after treatment and some coagulants factors increased.

CONCLUSIONS

This study showed a preliminary support to suggest that the herbal medicine RDN combined with LRD can reduce both susceptibility and the severity of DENV.

Diagnosis and Assessment of Microbial Infections with Host and Microbial MicroRNA Profiles

MicroRNAs (miRNAs) encoded by viral genome or host have been found participating in host-microbe interactions. Differential expression profiles of miRNAs were shown linking to specific disease pathologies which indicated its potency as diagnostic/prognostic biomarkers of infectious disease. This was emphasized by the discovery of circulating miRNAs which were found to be remarkably stable in mammalian biofluids. Standardized methods of miRNA quantification including RNA isolation should be established before they will be ready for use in clinical practice.

Macrophage polarization and meta-inflammation

Chronic overnutrition and obesity induces low-grade inflammation throughout the body. Termed "meta-inflammation," this chronic state of inflammation is mediated by macrophages located within the colon, liver, muscle, and adipose tissue. A sentinel orchestrator of immune activity and homeostasis, macrophages adopt variable states of activation as a function of time and environmental cues. Meta-inflammation phenotypically skews these polarization states and has been linked to numerous metabolic disorders. The past decade has revealed several key regulators of macrophage polarization, including the signal transducer and activator of transcription family, the peroxisome proliferator-activated receptor gamma, the CCAAT-enhancer-binding proteins (C/EBP) family, and the interferon regulatory factors. Recent studies have also suggested that microRNAs and long noncoding RNA influence macrophage polarization. The pathogenic alteration of macrophage polarization in meta-inflammation is regulated by both extracellular and intracellular cues, resulting in distinct secretome profiles. Meta-inflammation-altered macrophage polarization has been linked to insulin insensitivity, atherosclerosis, inflammatory bowel disease, cancer, and autoimmunity. Thus, further mechanistic exploration into the skewing of macrophage polarization promises to have profound impacts on improving global health.

microRNA expression signatures and parallels between monocyte subsets and atherosclerotic plaque in humans

Small non-coding microRNAs (miRNAs) have emerged to play critical roles in cardiovascular biology. Monocytes critically drive atherosclerotic lesion formation, and can be subdivided into a classical and non-classical subset. Here we scrutinised the miRNA signature of human classical and non-classical monocytes, and compared miRNA expression profiles of atherosclerotic plaques from human carotid arteries and healthy arteries. We identified miRNAs to be differentially regulated with a two-fold or higher difference between classical and non-classical monocyte subsets. Moreover, comparing miRNA expression in atherosclerotic plaques compared to healthy arteries, we observed several miRNAs to be aberrantly expressed, with the majority of miRNAs displaying a two-fold or higher increase in plaques and only few miRNAs being decreased. To elucidate similarities in miRNA signatures between monocyte subsets and atherosclerotic plaque, expression of miRNAs highly abundant in monocytes and plaque tissues were compared. Several miRNAs were found in atherosclerotic plaques but not in healthy vessels or either monocyte subset. However, we could identify miRNAs co-expressed in plaque tissue and classical monocytes (miR-99b, miR-152), or non-classical monocytes (miR-422a), or in both monocytes subsets. We thus unravelled candidate miRNAs, which may facilitate our understanding of monocyte recruitment and fate during atherosclerosis, and may serve as therapeutic targets for treating inflammatory vascular diseases.

Note: The editorial process for this article was fully handled by Prof. G. Y. H. Lip, Editor-in-Chief.

Silencing rno-miR-155-5p in rat temporal lobe epilepsy model reduces pathophysiological features and cell apoptosis by activating Sestrin-3

Temporal lobe epilepsy (TLE) is a chronic neurological disease characterized by recurrent spontaneous seizures. MicroRNAs are dysregulated in various pathological conditions including epilepsy. Therefore, we hypothesized that the dysregulation of these microRNAs might also be associated with the pathogenesis of TLE. In this study, we found that a microRNA, hsa-miR-155-5p, was upregulated in patients with TLE post-surgery, and hence associated with clinical and pathological manifestations and seizure outcomes. We then used a rat model of experimental epilepsy induced by pilocarpine and revealed that the rat homologue was upregulated as well. Importantly, injection of an antagomiR of rno-miR-155-5p in vivo resulted in a reduction of the pathophysiological features associated with the status epilepticus, which was accompanied by decrease of apoptosis in the hippocampus. This effect was correlated with an increase in rat Sestrin-3 expression, which was a gene known to counteract oxidative stress. This rescue was also observed after injection of a lentivirus carrying the small interfering RNA of rat Sestrin-3 gene in the hippocampus. In addition, rno-miR-155-5p as well as rat Sestrin-3 mRNA and protein expression were partly dependent on oxidative stress induced by H₂O₂ in PC12 cells_. Taken together, our data suggest that rno-miR-155-5p is a potent post-transcriptional regulator of rat Sestrin-3 and it may be one of the molecular links between brain damage and increased risk for seizures during damage by oxidative stress.

Molecular Mechanisms Modulating the Phenotype of Macrophages and Microglia

Macrophages and microglia play crucial roles during central nervous system development, homeostasis and acute events such as infection or injury. The diverse functions of tissue macrophages and microglia are mirrored by equally diverse phenotypes. A model of inflammatory/M1 versus a resolution phase/M2 macrophages has been widely used. However, the complexity of macrophage function can only be achieved by the existence of varied, plastic and tridimensional macrophage phenotypes. Understanding how tissue macrophages integrate environmental signals via molecular programs to define pathogen/injury inflammatory responses provides an opportunity to better understand the multilayered nature of macrophages, as well as target and modulate cellular programs to control excessive inflammation. This is particularly important in MS and other neuroinflammatory diseases, where chronic inflammatory macrophage and microglial responses may contribute to pathology. Here, we perform a comprehensive review of our current understanding of how molecular pathways modulate tissue macrophage phenotype, covering both classic pathways and the emerging role of microRNAs, receptor-tyrosine kinases and metabolism in macrophage phenotype. In addition, we discuss pathway parallels in microglia, novel markers helpful in the identification of peripheral macrophages versus microglia and markers linked to their phenotype.

Role of microRNA-155 in rheumatoid arthritis

MicroRNAs (miRNAs) are a recently discovered class of post-transcriptional regulators that induce target messenger RNA degradation or translation inhibition. miRNA-155 (miR-155) is an important regulator of immune cells both in humans and mice, by which these cells play critical roles in the pathogenesis of rheumatoid arthritis (RA). Recent findings showed that expression of miR-155 was elevated in RA patients and arthritis models. Moreover, miR-155 overexpression or knockdown performed significantly in the development of arthritis. This review summarizes the recent findings with respect to miR-155 in immune responses and the underlying mechanisms responsible for miR-155-related autoimmune arthritis. Hopefully the information obtained will benefit the development of novel therapeutic strategies.

Translation efficiency is a determinant of the magnitude of miRNA-mediated repression

MicroRNAs are well known regulators of mRNA stability and translation. However, the magnitude of both translational repression and mRNA decay induced by miRNA binding varies greatly between miRNA targets. This can be the result of cis and trans factors that affect miRNA binding or action. We set out to address this issue by studying how various mRNA characteristics affect miRNA-mediated repression. Using a dual luciferase reporter system, we systematically analyzed the ability of selected mRNA elements to modulate miRNA-mediated repression. We found that changing the 3'UTR of a miRNA-targeted reporter modulates translational repression by affecting the translation efficiency. This 3'UTR dependent modulation can be further altered by changing the codon-optimality or 5'UTR of the luciferase reporter. We observed maximal repression with intermediate codon optimality and weak repression with very high or low codon optimality. Analysis of ribosome profiling and RNA-seq data for endogenous miRNA targets revealed translation efficiency as a key determinant of the magnitude of miRNA-mediated translational repression. Messages with high translation efficiency were more robustly repressed. Together our results reveal modulation of miRNA-mediated repression by characteristics and features of the 5'UTR, CDS and 3'UTR.

Beyond mRNA: The role of non-coding RNAs in normal and aberrant hematopoiesis

The role of non-coding Ribonucleic Acids (ncRNAs) in biology is currently an area of intense focus. Hematopoiesis requires rapidly changing regulatory molecules to guide appropriate differentiation and ncRNA are well suited for this. It is not surprising that virtually all aspects of hematopoiesis have roles for ncRNAs assigned to them and doubtlessly much more await characterization. Stem cell maintenance, lymphoid, myeloid and erythroid differentiation are all regulated by various ncRNAs, including microRNAs (miRNAs), long non-coding RNAs (lncRNAs) and various transposable elements within the genome. As our understanding of the many and complex ncRNA roles continues to grow, new discoveries are challenging the existing classification schemes. In this review we briefly overview the broad categories of ncRNAs and discuss a few examples regulating normal and aberrant hematopoiesis.

Characterization of extracellular vesicles derived from cardiac cells in an in vitro model of preconditioning

Preconditioning is a promising technique to protect the heart from ischaemia-reperfusion injury. In this context, the crosstalk between different cardiac cell types and especially the exchange of cardioprotective mediators has come into the focus of current research. Recently, extracellular vesicles (EVs), nano-sized structures, emerged as possible communication mediators. They are taken up by recipient cells and can alter gene expression or activate intracellular signal cascades. It has been shown that all cardiac cell types are able to secrete EVs, but so far the influence of an in vitro preconditioning stimulus on EV concentration and composition has not been investigated. Therefore, we stimulated primary cardiac myocytes and fibroblasts from neonatal rats, as well as H9c2 cells, with two known in vitro preconditioning stimuli: hypoxia or isoflurane. EVs were isolated from cell culture supernatants 48 h after stimulation by differential centrifugation and size exclusion chromatography. They were characterized by transmission electron microscopy, tunable resistive pulse sensing, miRNA array and Western blot analysis. The detected EVs had the typical cup-shaped morphology and a size of about 150 nm. No significant differences in EV concentration were observed between the different groups. The protein and miRNA load was affected by in vitro preconditioning with isoflurane or hypoxia. EV markers like Alix, CD63, flotillin-1 and especially heat shock protein 70 were significantly up-regulated by the treatments. Several miRNAs like miR-92b-3p, miR-761 and miR-101a-5p were also significantly affected. A migration assay confirmed the physiological benefit of these EVs. Taken together, our findings show that a model of in vitro preconditioning of cardiac cells does not influence EV concentration but strongly regulates the EV cargo and affects migration. This might indicate a role for EV-mediated communication in isoflurane- and hypoxia-induced in vitro preconditioning.

MicroRNA-155 induction via TNF-α and IFN-γ suppresses expression of programmed death ligand-1 (PD-L1) in human primary cells

Programmed death ligand-1 (PD-L1) is a critical regulator of T cell function contributing to peripheral immune tolerance. Although it has been shown that posttranscriptional regulatory mechanisms control PD-L1 expression in cancer, it remains unknown whether such regulatory loops operate also in non-transformed cells. Here we studied PD-L1 expression in human dermal lymphatic endothelial cells (HDLECs), which play key roles in immunity and cancer. Treatment of HDLECs with the pro-inflammatory cytokines IFN-γ and TNF-α synergistically up-regulated PD-L1 expression. IFN-γ and TNF-α also affected expression of several microRNAs (miRNAs) that have the potential to suppress PD-L1 expression. The most highly up-regulated miRNA following IFN-γ and TNF-α treatment in HDLECs was miR-155, which has a central role in the immune system and cancer. Induction of miR-155 was driven by TNF-α, the effect of which was significantly enhanced by IFN-γ. The PD-L1 3′-UTR contains two functional miR-155-binding sites. Endogenous miR-155 controlled the kinetics and maximal levels of PD-L1 induction upon IFN-γ and TNF-α treatments. We obtained similar findings in dermal fibroblasts, demonstrating that the IFN-γ/TNF-α/miR-155/PD-L1 pathway is not restricted to HDLECs. These results reveal miR-155 as a critical component of an inflammation-induced regulatory loop controlling PD-L1 expression in primary cells.

TNF-α mRNA is negatively regulated by microRNA-181a-5p in maturation of dendritic cells induced by high mobility group box-1 protein

Dendritic cell (DC) can be stimulated by both exogenous pathogen-associated molecular patterns (PAMPs) such as lipopolysaccharide (LPS) and endogenous damage-associated molecular patterns (DAMPs) such as high mobility group box-1 protein (HMGB1). MicroRNAs (miRNAs) act as post-transcriptional fine tuners of mRNA. Studies have focused mostly on the potential role of miRNAs in DCs maturation triggered by PAMPs, especially LPS, however, little is known about the regulatory mechanism underlying the effects of miRNAs in DC maturation mediated by DAMPs, including HMGB1. Here, we first profiled a miRNA microarray of DCs stimulated by HMGB1 and determined that the up-regulated miRNA miR-181a-5p may act as a regulatory miRNA in these cells. Computational algorithms predicted TNF-α 3'UTR to be targeted by miR-181a-5p, which was confirmed by the experiments involving luciferase reporters. In addition, we found that TNF-α mRNA was down-regulated by miR-181a-5p mimic, and significantly up-regulated by miR-181a-5p inhibitor. Taken together, we identified miR-181a-5p a negative regulator in HMGB1-induced immune responses by targeting TNF-α mRNA in DCs. Moreover, we suggested that miR-181a-5p may play a role in regulating DC responses to HMGB1 and serve as evidence indicating that novel therapies targeting miRNAs may be useful for treating immune dysfunction in the setting of sepsis.

MicroRNA-488 and -920 regulate the production of proinflammatory cytokines in acute gouty arthritis

Background

Gout is considered one of the most painful acute conditions caused by deposition of monosodium urate (MSU) crystals within joints. Recent studies have shown that interleukin (IL)-1β is a key inflammatory mediator in acute gouty arthritis (GA), and its level is regulated by microRNAs (miRNAs). However, the molecular mechanisms of the regulation remain unclear.

Methods

A miRNA microarray was used to analyze the miRNA expression profiles in peripheral white blood cells (WBCs) of patients with GA. THP-1 cells were transfected with miRNA mimics, stimulated by MSU crystals, and then subjected to quantitative real-time polymerase chain reaction or Western blot analysis. Levels of IL-1β, IL-8, and tumor necrosis factor (TNF)-α in culture supernatants of THP-1 cells were measured by enzyme-linked immunosorbent assay. A luciferase reporter assay was conducted to confirm the interaction of miRNA and IL-1β 3′-untranslated regions (UTRs).

Results

Combining bioinformatics and miRNA expression profiles, we found five miRNAs (hsa-miR-30c-1-3p, hsa-miR-488-3p, hsa-miR-550a-3p, hsa-miR-663a, and hsa-miR-920) that possibly target IL-1β. Then, we demonstrated that miR-488 and miR-920 were significantly decreased in the WBCs of patients with GA and that MSU crystals could inhibit expression of miR-488 and miR-920. Upregulation of miR-488 and miR-920 could suppress MSU-induced IL-1β protein expression in THP-1 cells, but no significant difference in IL-1β messenger RNA levels was observed. Moreover, we found that miR-488 and miR-920 could directly target the 3′-UTR of IL-1β. Overexpression of miR-488 and miR-920 could significantly inhibit the gene and protein expression of IL-8 and TNF-α in MSU-induced THP-1 cells.

Conclusions

This study demonstrates the roles of miR-488 and miR-920 in regulating the production of proinflammatory cytokines in the pathogenesis of GA. These findings suggest that miR-488 and miR-920 could serve as potential therapeutic targets in the treatment of GA.

Electronic supplementary material

The online version of this article (doi:10.1186/s13075-017-1418-6) contains supplementary material, which is available to authorized users.

IκK-16 decreases miRNA-155 expression and attenuates the human monocyte inflammatory response

Excessive inflammatory responses in the surgical patient may result in cellular hypo-responsiveness, which is associated with an increased risk of secondary infection and death. microRNAs (miRNAs), such as miR-155, are powerful regulators of inflammatory signalling pathways including nuclear factor κB (NFκB). Our objective was to determine the effect of IκK-16, a selective blocker of inhibitor of kappa-B kinase (IκK), on miRNA expression and the monocyte inflammatory response. In a model of endotoxin tolerance using primary human monocytes, impaired monocytes had decreased p65 expression with suppressed TNF-α and IL-10 production (P < 0.05). miR-155 and miR-138 levels were significantly upregulated at 17 h in the impaired monocyte (P < 0.05). Notably, IκK-16 decreased miR-155 expression with a corresponding dose-dependent decrease in TNF-α and IL-10 production (P < 0.05), and impaired monocyte function was associated with increased miR-155 and miR-138 expression. In the context of IκK-16 inhibition, miR-155 mimics increased TNF-α production, while miR-155 antagomirs decreased both TNF-α and IL-10 production. These data demonstrate that IκK-16 treatment attenuates the monocyte inflammatory response, which may occur through a miR-155-mediated mechanism, and that IκK-16 is a promising approach to limit the magnitude of an excessive innate inflammatory response to LPS.

Inflammatory Diseases and Growth: Effects on the GH-IGF Axis and on Growth Plate

This review briefly describes the most common chronic inflammatory diseases in childhood, such as cystic fibrosis (CF), inflammatory bowel diseases (IBDs), juvenile idiopathic arthritis (JIA), and intrauterine growth restriction (IUGR) that can be considered, as such, for the changes reported in the placenta and cord blood of these subjects. Changes in growth hormone (GH) secretion, GH resistance, and changes in the insulin-like growth factor (IGF) system are described mainly in relationship with the increase in nuclear factor-κB (NF-κB) and pro-inflammatory cytokines. Changes in the growth plate are also reported as well as a potential role for microRNAs (miRNAs) and thus epigenetic changes in chronic inflammation. Many mechanisms leading to growth failure are currently known; however, it is clear that further research in the field is still warranted.

Dexmedetomidine Prevents Lipopolysaccharide-Induced MicroRNA Expression in the Adult Rat Brain

During surgery or infection, peripheral inflammation can lead to neuroinflammation, which is associated with cognitive impairment, neurodegeneration, and several neurodegenerative diseases. Dexmedetomidine, an α-2-adrenoceptor agonist, is known to exert anti-inflammatory and neuroprotective properties and reduces the incidence of postoperative cognitive impairments. However, on the whole the molecular mechanisms are poorly understood. This study aims to explore whether dexmedetomidine influences microRNAs (miRNAs) in a rat model of lipopolysaccharide (LPS)-induced neuroinflammation. Adult Wistar rats were injected with 1 mg/kg LPS intraperitoneal (i.p.) in the presence or absence of 5 µg/kg dexmedetomidine. After 6 h, 24 h, and 7 days, gene expressions of interleukin 1-β (IL1-β), tumor necrosis factor-α (TNF-α), and microRNA expressions of miR 124, 132, 134, and 155 were measured in the hippocampus, cortex, and plasma. Dexmedetomidine decreased the LPS-induced neuroinflammation in the hippocampus and cortex via significant reduction of the IL1-β and TNF-α gene expressions after 24 h. Moreover, the LPS-mediated increased expressions of miR 124, 132, 134, and 155 were significantly decreased after dexmedetomidine treatment in both brain regions. In plasma, dexmedetomidine significantly reduced LPS-induced miR 155 after 6 h. Furthermore, there is evidence that miR 132 and 134 may be suitable as potential biomarkers for the detection of neuroinflammation.

TNF-α-induced miR-155 regulates IL-6 signaling in rheumatoid synovial fibroblasts

Background

MicroRNAs (miRNAs) are important regulators of a variety of inflammatory mediators. The present study was undertaken to elucidate the role of miRNAs in the rheumatoid cytokine network.

Methods

We analyzed miRNA expression in rheumatoid synovial fibroblasts (RASFs). miRNA array-based screening was used to identify miRNAs differentially expressed between tumor necrosis factor-α (TNF-α)-activated RASFs and untreated RASFs. Transfection of RASFs with miR-155 was used to analyze the function of miR-155. Real-time polymerase chain reaction (PCR) was used to measure the levels of miR-155 in RASFs.

Results

miRNA microarray analysis revealed that miR-155-5p was the most highly induced miRNA in TNF-α-stimulated RASFs. TNF-α-induced miR-155 expression in RASFs was time-dependent and TNFα dose-dependent, whereas, IL-6 stimulation did not affect miR-155 expression in RASFs. Transfection of miR-155 mimics into RASFs resulted in the decrease JAK2/STAT3 phosphorylation in IL-6-treated RASFs.

Conclusions

The current results demonstrate that TNF-α modulated miRNA expressions in RASFs. Our data showed that miR-155, which is highly induced by TNF-α stimulation, inhibits IL-6-mediated JAK2/STAT3 activation in RASFs. These findings suggest that miR-155 contributes to the cross-regulation between TNF-α and IL-6-mediated inflammatory pathways in RA.

Induction of miR-155 after Brain Injury Promotes Type 1 Interferon and has a Neuroprotective Effect

Traumatic brain injury (TBI) produces profound and lasting neuroinflammation that has both beneficial and detrimental effects. Recent evidence has implicated microRNAs (miRNAs) in the regulation of inflammation both in the periphery and the CNS. We examined the expression of inflammation associated miRNAs in the context of TBI using a mouse controlled cortical impact (CCI) model and found increased levels of miR-21, miR-223 and miR-155 in the hippocampus after CCI. The expression of miR-155 was elevated 9-fold after CCI, an increase confirmed by in situ hybridization (ISH). Interestingly, expression of miR-155 was largely found in neuronal nuclei as evidenced by co-localization with DAPI in MAP2 positive neurons. In miR-155 knock out (KO) mice expression of type I interferons IFNα and IFNβ, as well as IFN regulatory factor 1 and IFN-induced chemokine CXCL10 was decreased after TBI relative to wild type (WT) mice. Unexpectedly, miR-155 KO mice had increased levels of microglial marker Iba1 and increased neuronal degeneration as measured by fluoro-jade C (FJC) staining, suggesting a neuroprotective role for miR-155 in the context of TBI. This work demonstrates a role for miR-155 in regulation of the IFN response and neurodegeneration in the aftermath of TBI. While the presence of neuronal nuclear miRNAs has been described previously, their importance in disease states is relatively unknown. Here, we show evidence of dynamic regulation and pathological function of a nuclear miRNA in TBI.

miR-181d regulates human dendritic cell maturation through NF-κB pathway

OBJECTIVES

MicroRNAs (miRNAs) are considered as the cellular regulators which post-transcriptionally modulate gene expression in diverse biological processes including cell development and immunity. In this study, we investigated functions of miR-181d in dendritic cells (DCs) maturation, and the underlying mechanisms were also explored.

MATERIALS AND METHODS

Here we did the miRNA screening in human DCs in response to lipopolysaccharides (LPS) by quantitative real-time PCR (qRT-PCR). The expressions of DCs maturation markers were measured after miRNA mimics transfections. The pharmacological inhibitors of signalling pathways were applied to examine miR-181d effect on DCs maturation by Western blot. Luciferase assay and mixed lymphocyte reaction (MLR) were also performed to reveal the target gene of miR-181d and test the viability of T cells treated with miR-181d transfected DCs.

RESULTS

Overexpression of miR-181d per se is sufficient to promote DCs maturation, and up-regulate CD80 and CD83 expressions without LPS. Besides, we showed that miR-181d activated NF-κB pathway and also promoted the expression of pro-inflammatory cytokine IL12 and TNF-α. Inhibition of NF-κB pathway suppressed DCs maturation. Luciferase reporter assay and target gene knockdown assay indicated that miR-181d targets regulator cylindromatosis (CYLD), a primary negative regulator of NF-κB pathway. MLR assay showed that miR-181d-transfected DCs could promote T-cell proliferation than iDCs in vitro.

CONCLUSION

Our study demonstrates that miR-181d is required for DCs maturation through the activation of NF-κB pathway by targeting CYLD.

Inhibition of Toll-Like Receptor Signaling as a Promising Therapy for Inflammatory Diseases: A Journey from Molecular to Nano Therapeutics

The recognition of invading pathogens and endogenous molecules from damaged tissues by toll-like receptors (TLRs) triggers protective self-defense mechanisms. However, excessive TLR activation disrupts the immune homeostasis by sustained pro-inflammatory cytokines and chemokines production and consequently contributes to the development of many inflammatory and autoimmune diseases, such as systemic lupus erythematosus (SLE), infection-associated sepsis, atherosclerosis, and asthma. Therefore, inhibitors/antagonists targeting TLR signals may be beneficial to treat these disorders. In this article, we first briefly summarize the pathophysiological role of TLRs in the inflammatory diseases. We then focus on reviewing the current knowledge in both preclinical and clinical studies of various TLR antagonists/inhibitors for the prevention and treatment of inflammatory diseases. These compounds range from conventional small molecules to therapeutic biologics and nanodevices. In particular, nanodevices are emerging as a new class of potent TLR inhibitors for their unique properties in desired bio-distribution, sustained circulation, and preferred pharmacodynamic and pharmacokinetic profiles. More interestingly, the inhibitory activity of these nanodevices can be regulated through precise nano-functionalization, making them the next generation therapeutics or “nano-drugs.” Although, significant efforts have been made in developing different kinds of new TLR inhibitors/antagonists, only limited numbers of them have undergone clinical trials, and none have been approved for clinical uses to date. Nevertheless, these findings and continuous studies of TLR inhibition highlight the pharmacological regulation of TLR signaling, especially on multiple TLR pathways, as future promising therapeutic strategy for various inflammatory and autoimmune diseases.

miR-155 Deletion in Mice Overcomes Neuron-Intrinsic and Neuron-Extrinsic Barriers to Spinal Cord Repair

Axon regeneration after spinal cord injury (SCI) fails due to neuron-intrinsic mechanisms and extracellular barriers including inflammation. microRNA (miR)-155-5p is a small, noncoding RNA that negatively regulates mRNA translation. In macrophages, miR-155-5p is induced by inflammatory stimuli and elicits a response that could be toxic after SCI. miR-155 may also independently alter expression of genes that regulate axon growth in neurons. Here, we hypothesized that miR-155 deletion would simultaneously improve axon growth and reduce neuroinflammation after SCI by acting on both neurons and macrophages. New data show that miR-155 deletion attenuates inflammatory signaling in macrophages, reduces macrophage-mediated neuron toxicity, and increases macrophage-elicited axon growth by ∼40% relative to control conditions. In addition, miR-155 deletion increases spontaneous axon growth from neurons; adult miR-155 KO dorsal root ganglion (DRG) neurons extend 44% longer neurites than WT neurons. In vivo, miR-155 deletion augments conditioning lesion-induced intraneuronal expression of SPRR1A, a regeneration-associated gene; ∼50% more injured KO DRG neurons expressed SPRR1A versus WT neurons. After dorsal column SCI, miR-155 KO mouse spinal cord has reduced neuroinflammation and increased peripheral conditioning-lesion-enhanced axon regeneration beyond the epicenter. Finally, in a model of spinal contusion injury, miR-155 deletion improves locomotor function at postinjury times corresponding with the arrival and maximal appearance of activated intraspinal macrophages. In miR-155 KO mice, improved locomotor function is associated with smaller contusion lesions and decreased accumulation of inflammatory macrophages. Collectively, these data indicate that miR-155 is a novel therapeutic target capable of simultaneously overcoming neuron-intrinsic and neuron-extrinsic barriers to repair after SCI.

SIGNIFICANCE STATEMENT

Axon regeneration after spinal cord injury (SCI) fails due to neuron-intrinsic mechanisms and extracellular barriers, including inflammation. Here, new data show that deleting microRNA-155 (miR-155) affects both mechanisms and improves repair and functional recovery after SCI. Macrophages lacking miR-155 have altered inflammatory capacity, which enhances neuron survival and axon growth of cocultured neurons. In addition, independent of macrophages, adult miR-155 KO neurons show enhanced spontaneous axon growth. Using either spinal cord dorsal column crush or contusion injury models, miR-155 deletion improves indices of repair and recovery. Therefore, miR-155 has a dual role in regulating spinal cord repair and may be a novel therapeutic target for SCI and other CNS pathologies.

MicroRNAs That Contribute to Coordinating the Immune Response in Drosophila melanogaster

Small noncoding RNAs called microRNAs (miRNAs) have emerged as post-transcriptional regulators of gene expression related to host defenses. Here, we have used Drosophila melanogaster to explore the contribution of individual or clusters of miRNAs in countering systemic Candida albicans infection. From a total of 72 tested, we identify 6 miRNA allelic mutant backgrounds that modulate the survival response to infection and the ability to control pathogen number. These mutants also exhibit dysregulation of the Toll pathway target transcripts Drosomycin (Drs) and Immune-Induced Molecule 1 (IM1). These are characteristics of defects in Toll signaling, and consistent with this, we demonstrate dependency for one of the miRNA mutants on the NF-κΒ homolog Dif. We also quantify changes in the miRNA expression profile over time in response to three pathogen types, and identify 13 mature miRNA forms affected by pathogens that stimulate Toll signaling. To complement this, we provide a genome-wide map of potential NF-κB sites in proximity to miRNA genes. Finally, we demonstrate that systemic C. albicans infection contributes to a reduction in the total amount of branch-chained amino acids, which is miRNA-regulated. Overall, our data reveal a new layer of miRNA complexity regulating the fly response to systemic fungal infection.

Hypoxia in CNS Pathologies: Emerging Role of miRNA-Based Neurotherapeutics and Yoga Based Alternative Therapies

Cellular respiration is a vital process for the existence of life. Any condition that results in deprivation of oxygen (also termed as hypoxia) may eventually lead to deleterious effects on the functioning of tissues. Brain being the highest consumer of oxygen is prone to increased risk of hypoxia-induced neurological insults. This in turn has been associated with many diseases of central nervous system (CNS) such as stroke, Alzheimer's, encephalopathy etc. Although several studies have investigated the pathophysiological mechanisms underlying ischemic/hypoxic CNS diseases, the knowledge about protective therapeutic strategies to ameliorate the affected neuronal cells is meager. This has augmented the need to improve our understanding of the hypoxic and ischemic events occurring in the brain and identify novel and alternate treatment modalities for such insults. MicroRNA (miRNAs), small non-coding RNA molecules, have recently emerged as potential neuroprotective agents as well as targets, under hypoxic conditions. These 18-22 nucleotide long RNA molecules are profusely present in brain and other organs and function as gene regulators by cleaving and silencing the gene expression. In brain, these are known to be involved in neuronal differentiation and plasticity. Therefore, targeting miRNA expression represents a novel therapeutic approach to intercede against hypoxic and ischemic brain injury. In the first part of this review, we will discuss the neurophysiological changes caused as a result of hypoxia, followed by the contribution of hypoxia in the neurodegenerative diseases. Secondly, we will provide recent updates and insights into the roles of miRNA in the regulation of genes in oxygen and glucose deprived brain in association with circadian rhythms and how these can be targeted as neuroprotective agents for CNS injuries. Finally, we will emphasize on alternate breathing or yogic interventions to overcome the hypoxia associated anomalies that could ultimately lead to improvement in cerebral perfusion.

Brucella Omp25 Upregulates miR-155, miR-21-5p, and miR-23b to Inhibit Interleukin-12 Production via Modulation of Programmed Death-1 Signaling in Human Monocyte/Macrophages

Brucella spp. infection results in compromised Type1 (Th1) cellular immune response. Several reports have described an immunomodulatory function for Brucella major outer membrane protein Omp25. However, the mechanism by which Omp25 modulates macrophage dysfunction has not been defined. Herein, we reported that Omp25-deficient mutant of Brucella suis exhibited an enhanced ability to induce interleukin (IL)-12 whereas ectopic expression of Omp25 protein inhibited TLR agonists-induced IL-12 p70 production through suppression of both IL-12 p40 and p35 subunit expression in THP-1 cells. In addition, Omp25 significantly upregulated miR-155, -23b and -21-5p, as well as the immunomodulator molecule programmed death-1 (PD-1) in monocyte/macrophages. The upregulation of miR-155 and -23b correlated temporally with decreased TAB2 levels, IκB phosphorylation and IL-12 p40 levels by targeting TAB2 and il12B 3' untranslated region (UTR), respectively, while miR-21-5p increase directly led to the reduction of lipopolysaccharide (LPS)/R848-induced IL-12 p35 protein by targeting il12A 3'UTR. Consistent with this finding, reduction of miR-155 and -23b attenuated the inhibitory effects of Omp25 on LPS/R848-induced IL-12 p40 expression at both transcriptional and posttranscriptional levels, while reduction of miR-21-5p attenuated the inhibitory effects of Omp25 on LPS/R848-induced IL-12 p35 expression at the posttranscriptional level, together significantly enhanced IL-12 p70 production upon LPS/R848 stimulation. We also found that blocking PD-1 signaling decreased the expression of miR-155, -23b and -21-5p induced by Omp25 and enhanced IL-12 production in monocyte/macrophages. Altogether, these data demonstrate that Brucella Omp25 induces miR-155, -23b and -21-5p to negatively regulate IL-12 production at both transcriptional and posttranscriptional levels via regulation of PD-1 signaling, which provides an entirely new mechanism underlying monocyte/macrophages dysfunction during Brucella spp. infection.

miR-146 and miR-155: Two Key Modulators of Immune Response and Tumor Development

MicroRNAs (miRNAs or miRs) are a class of evolutionarily-conserved small, regulatory non-coding RNAs, 19–3 nucleotides in length, that negatively regulate protein coding gene transcripts’ expression. miR-146 (146a and 146b) and miR-155 are among the first and most studied miRs for their multiple roles in the control of the innate and adaptive immune processes and for their deregulation and oncogenic role in some tumors. In the present review, we have focused on the recent acquisitions about the key role played by miR-146a, miR-146b and miR-155 in the control of the immune system and in myeloid tumorigenesis. Growing experimental evidence indicates an opposite role of miR-146a with respect to miR-155 in the fine regulation of many steps of the immune response, acting at the level of the various cell types involved in innate and adaptive immune mechanisms. The demonstration that miR-155 overexpression plays a key pathogenic role in some lymphomas and acute myeloid leukemias has led to the development of an antagomir-based approach as a new promising therapeutic strategy.

Down-regulation of miRNAs in the brain and development of diet-induced obesity

Novel therapeutic interventions for obesity and comorbid conditions require knowledge of the molecular elements playing a role in the development of obesity. Chronic low-grade inflammation has been consistently reported in obese individuals. In this study, we first determined whether key molecular modulators of inflammation, microRNA-155 (miR-155) and microRNA-146a (miR-146a), are regulated by an obesogenic diet within brain regions associated with reward, metabolism and energy balance. C57BL/6J mice were chronically exposed to a high-fat diet (HFD) or a standard chow (CTL). Significant reductions in the levels of miR-155 (82%) and miR-146a (41%) levels were observed within the nucleus accumbens of HFD mice compared to CTL. Further analysis of miR-155 regulation showed no significant changes in levels across peripheral tissue (white adipose, spleen, kidney or liver) between HFD and CTL mice. The effect of lower miR-155 on the development of obesity was determined by exposing wild-type (WT) and miR-155 knockout mice (miR-155 KO) to HFD. Male miR-155 KO gained significantly more weight than WT littermates. Metabolic analyses revealed that miR-155 KO significantly ate more HFD compared to WT, without differing in other metabolic measures including energy expenditure. Together, these data show that miR-155 is physiologically down-regulated after intake of an obesogenic diet, and that loss of miR-155 increases intake of an obesogenic diet. Moreover, these findings shed light on a potential miRNA-based mechanism contributing to the development of diet-induced obesity.

Noncoding RNAs in Cancer Immunology

Cancer immunology is the study of interaction between cancer cells and immune system by the application of immunology principle and theory. With the recent approval of several new drugs targeting immune checkpoints in cancer, cancer immunology has become a very attractive field of research and is thought to be the new hope to conquer cancer. This chapter introduces the aberrant expression and function of noncoding RNAs, mainly microRNAs and long noncoding RNAs, in tumor-infiltrating immune cells, and their significance in tumor immunity. It also illustrates how noncoding RNAs are shuttled between tumor cells and immune cells in tumor microenvironments via exosomes or other microvesicles to modulate tumor immunity.

Characterization of basal and lipopolysaccharide-induced microRNA expression in equine peripheral blood mononuclear cells using Next-Generation Sequencing

The innate immune response to lipopolysaccharide contributes substantially to the morbidity and mortality of gram-negative sepsis. Horses and humans share an exquisite sensitivity to lipopolysaccharide and thus the horse may provide valuable comparative insights into this aspect of the inflammatory response. MicroRNAs, small non-coding RNA molecules acting as post-transcriptional regulators of gene expression, have key roles in toll-like receptor signaling regulation but have not been studied in this context in horses. The central hypothesis of this study was that lipopolysaccharide induces differential microRNA expression in equine peripheral blood mononuclear cells in a manner comparable to humans. Illumina Next Generation Sequencing was used to characterize the basal microRNA transcriptome in isolated peripheral blood mononuclear cells from healthy adult horses, and to evaluate LPS-induced changes in microRNA expression in cells cultured for up to four hours. Selected expression changes were validated using quantitative reverse-transcriptase PCR. Only miR-155 was significantly upregulated by LPS, changing in parallel with supernatant tumor necrosis factor-α concentration. Eight additional microRNAs, including miR-146a and miR-146b, showed significant expression change with time in culture without a clear LPS effect. Target predictions indicated a number of potential immunity-associated targets for miR-155 in the horse, including SOCS1, TAB2 and elements of the PI3K signaling pathway, suggesting that it is likely to influence the acute inflammatory response to LPS. Gene alignment showed extensive conservation of the miR-155 precursor gene and associated promoter regions between horses and humans. The basal and LPS-stimulated microRNA expression pattern characterized here were similar to those described in human leukocytes. As well as providing a resource for further research into the roles of microRNAs in immune responses in horses, this will facilitate inter-species comparative study of the role of microRNAs in the inflammatory cascade during endotoxemia and sepsis.

MicroRNA-155: a Novel Armamentarium Against Inflammatory Diseases

An increasing number of diseases are being newly closely associated with inflammation, where microRNAs seem to play a critical role in the whole disease process from initiation to development. MicroRNAs are small non-coding RNAs that govern gene expression and modulation by means of mRNA degradation or translational repression. After several profound research studies, new correlations between microRNA-155 and inflammation-related diseases are strongly emerging. Hence, we review in this paper the possible molecular mechanisms of microRNA-155 in inflammatory disorders. Furthermore, we also consider the feasibility of targeting it as a bright alternative to improve the early diagnose statistics and treatments in those diseases. MicroRNA-155 features a novel breakthrough in fine-tuning inflammatory responses and, thereby, in treating a wide spectrum of diseases with inflammation as a common denominator.

Down-regulation of microRNA-155 promotes selenium deficiency-induced apoptosis by tumor necrosis factor receptor superfamily member 1B in the broiler spleen

The aim of this work was to explore the microRNA profile and the effect of microRNA-155 on apoptosis in the spleen of selenium-deficient broilers. We replicated the splenic-apoptotic model in selenium-deficient broilers. In vitro, microRNA-155 oligonucleotides were transfected into lymphocytes and subsequently treated with H₂O₂. We observed that selenium deficiency altered the microRNA profile and decreased the expression of microRNA-155 in the broiler spleens. Tumor necrosis factor receptor superfamily member 1B was verified as a target of microRNA-155 in the splenocytes. Morphological changes, increased levels of tumor necrosis factor receptor superfamily member 1B, c-Jun N-terminal kinase, Bak, Bax, Cyt-c, caspase9 and caspase3 and decreased levels of Bcl-2 demonstrated that selenium deficiency induced apoptosis in the spleen tissues. In vitro, microRNA-155 m inhibited the levels of ROS and reduced apoptosis compared with microRNA-155i in the lymphocytes. These results suggested that the reduced levels of microRNA-155 due to selenium deficiency could promote oxidative stress-induced apoptosis by increased tumor necrosis factor receptor superfamily member 1B in splenic cells.