Akt2 deficiency protects from acute lung injury via alternative macrophage activation and miR-146a induction in mice

Over-expression of miR-223 induces M2 macrophage through glycolysis alteration and attenuates LPS-induced sepsis mouse model, the cell-based therapy in sepsis

The attenuation of hyper-inflammation in sepsis with the administration of anti-inflammatory macrophages is an interesting adjuvant therapy for sepsis. Because the induction of anti-inflammatory macrophages by microRNA (miR), a regulator of mRNA, has been mentioned, the exploration on miR-induced anti-inflammatory macrophages was performed. The over-expression of miR-223 and miR-146a in RAW264.7 induced M2 macrophage-polarization (anti-inflammatory macrophages) as evaluated by the enhanced expression of Arginase-1 and Fizz. However, miR-223 over-expressed cells demonstrated the more potent anti-inflammatory property against LPS stimulation as lesser iNOS expression, lower supernatant IL-6 and higher supernatant IL-10 compared with miR-146a over-expressed cells. Interestingly, LPS stimulation in miR-223 over-expressed cells, compared with LPS-stimulated control cells, demonstrated lower activity of glycolysis pathway and higher mitochondrial respiration, as evaluated by the extracellular flux analysis, and also down-regulated HIF-1α, an important enzyme of glycolysis pathway. In addition, the administration of miR-223 over-expressed macrophages with IL-4 pre-conditioning, but not IL-4 stimulated control cells, attenuated sepsis severity in LPS injected mice as evaluated by serum creatinine, liver enzymes, lung histology and serum cytokines. In conclusion, miR-223 interfered with the glycolysis pathway through the down-regulation of HIF-1α, resulting in the anti-inflammatory status. The over-expression of miR-223 in macrophages prevented the conversion into M1 macrophage polarization after LPS stimulation. The administration of miR-223 over-expressed macrophages, with IL-4 preconditioning, attenuated sepsis severity in LPS model. Hence, a proof of concept in the induction of anti-inflammatory macrophages through the cell-energy interference for sepsis treatment was proposed as a basis of cell-based therapy in sepsis.

Strategies to Modulate MicroRNA Functions for the Treatment of Cancer or Organ Injury

Cancer and organ injury-such as that occurring in the perioperative period, including acute lung injury, myocardial infarction, and acute gut injury-are among the leading causes of death in the United States and impose a significant impact on quality of life. MicroRNAs (miRNAs) have been studied extensively during the last two decades for their role as regulators of gene expression, their translational application as diagnostic markers, and their potential as therapeutic targets for disease treatment. Despite promising preclinical outcomes implicating miRNA targets in disease treatment, only a few miRNAs have reached clinical trials. This likely relates to difficulties in the delivery of miRNA drugs to their targets to achieve efficient inhibition or overexpression. Therefore, understanding how to efficiently deliver miRNAs into diseased tissues and specific cell types in patients is critical. This review summarizes current knowledge on various approaches to deliver therapeutic miRNAs or miRNA inhibitors and highlights current progress in miRNA-based disease therapy that has reached clinical trials. Based on ongoing advances in miRNA delivery, we believe that additional therapeutic approaches to modulate miRNA function will soon enter routine medical treatment of human disease, particularly for cancer or perioperative organ injury. SIGNIFICANCE STATEMENT: MicroRNAs have been studied extensively during the last two decades in cancer and organ injury, including acute lung injury, myocardial infarction, and acute gut injury, for their regulation of gene expression, application as diagnostic markers, and therapeutic potentials. In this review, we specifically emphasize the pros and cons of different delivery approaches to modulate microRNAs, as well as the most recent exciting progress in the field of therapeutic targeting of microRNAs for disease treatment in patients.

Identification of Novel microRNA Profiles Dysregulated in Plasma and Tissue of Abdominal Aortic Aneurysm Patients

microRNAs (miRNAs) are small RNAs that regulate different biological processes. Our objective was to identify miRNAs dysregulated in plasma and tissue of patients with abdominal aortic aneurysm (AAA) and explore new potential targets involved in AAA. Fifty-seven subjects were recruited for a plasma study (30 AAA patients, 16 healthy volunteers and 11 patients with atherosclerosis). The expression level of 179 miRNAs was screened in plasma from a subset of samples, and dysregulated miRNAs were validated in the entire study population. Dysregulated miRNAs were also quantified in aortic tissue of 21 AAA patients and 8 organ donors. Applying a gene set enrichment analysis, an interaction map of dysregulated miRNAs and their targets was built, and selected targets were quantified in tissue samples. miR-27b-3p and miR-221-3p were overexpressed in plasma of AAA patients compared with healthy controls, 1.6 times and 1.9 times, respectively. In AAA tissue, six miRNAs (miR-1, miR-27b-3p, miR-29b-3p, miR-133a-3p, miR-133b, and miR-195-5p) were underexpressed from 1.6 to 4.8 times and four miRNAs (miR-146a-5p, miR-21-5p, miR-144-3p, and miR-103a-3p) were overexpressed from 1.3 to 7.2 times. Thrombospondin-2, a target of miR-195-5p, was increased in AAA tissue and negatively correlated with the expression of miR-195-5p, suggesting their involvement in a common regulatory mechanism.

Let-7b-5p is involved in the response of endoplasmic reticulum stress in acute pulmonary embolism through upregulating the expression of stress-associated endoplasmic reticulum protein 1

The endogenous non-coding microRNA (miRNA) let-7b-5p is highly expressed in the blood of patients with acute pulmonary embolism (PE). However, the mechanism underlying the involvement of let-7b-5p in acute PE remains unclear. To address this, we investigated the role of let-7b-5p in acute PE in both in vitro and in vivo experimental models. The results showed that let-7b-5p upregulated the expression of stress-associated endoplasmic reticulum protein 1 (SERP1) at the post-transcriptional level. SERP1 activation leads to modulation of its chaperone protein SEC61B in the response of endoplasmic reticulum (ER) stress. Furthermore, our data show that the unfolded protein response was triggered and activation of unfolded proteins GRP78, PERK, RNF121, and CHOP occurred through the PERK-CHOP pathway, resulting in an inflammatory response and apoptosis of lung epithelial cells. These characteristics were promoted by the in vitro expression of a let-7b-5p mimic; conversely, transfection with a let-7b-5p inhibitor decreased the response of ER stress in acute PE. The results from this study thus provide evidence that let-7b-5p promotes protein processing during ER stress response by upregulating SERP1 expression, ultimately resulting in an inflammatory response and apoptosis of lung cells, cumulatively playing a critical role in the pathogenesis of acute PE.

Long noncoding RNA MALAT1 inhibits the apoptosis and autophagy of hepatocellular carcinoma cell by targeting the microRNA-146a/PI3K/Akt/mTOR axis

Background

Increased long noncoding RNA (lncRNA) expression is characteristic to hepatocellular carcinoma (HCC) and several other neoplasms. The present study aimed to identify the mechanism underlying modulation of HCC development by the lncRNA metastasis-associated lung adenocarcinoma transcript 1 (MALAT1).

Methods

Quantitative real-time polymerase chain reaction was used to determine MALAT1 and microRNA (miR)-146a expression in HCC tissues and cell lines. Western blotting was performed to measure PI3K, Akt, and mTOR levels. Dual-luciferase reporter assay was used to validate the direct targeting and negative regulatory interaction between miR-146a and MALAT1. Cell viability, proliferation, and apoptosis were analyzed using an 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay, colony formation assay, and flow cytometry, respectively; autophagy was detected based on LC3B expression.

Results

MALAT1 expression was higher in HCC tissues than in normal tissues. MALAT1 upregulation promoted HCC cell proliferation, whereas MALAT1 downregulation promoted HCC apoptosis and autophagy. Moreover, effects of MALAT1 downregulation on HCC cells were abolished by miR-146a inhibition. miR-146a directly targeted the 3'-untranslated region of PI3K, and PI3K protein level was clearly decreased upon miR-146a mimic transfection.

Conclusions

MALAT1 may modulate HCC cell proliferation, apoptosis, and autophagy via sponging miR-146a, which regulates HCC progression.

LincRNA-p21 promotes classical macrophage activation in acute respiratory distress syndrome by activating NF-κB

Background: Previous studies have revealed the important role of alveolar macrophages (AMs) in the pathogenesis of acute respiratory distress syndrome (ARDS) and potential anti-inflammatory properties of lincRNA-p21. This study aims to study the association between lincRNA-p21 and active AMs to understand the molecular mechanisms of AMs-mediated inflammatory responses in ARDS.Methods: This study was mainly investigated in mice with the intratracheal instillation of lipopolysaccharide (LPS) or LPS-treated AMs. The expression of lincRNA-p21 and classical macrophage markers, IL-12β and iNOS, was detected by quantitative RT-PCR, while NF-κB p65 translocation was measured by western blotting analysis. And, NF-κB activity was analyzed through luciferase report assays. Gain- and loss-of-function studies were also performed for further investigations.Results: Elevated lincRNA-p21 levels were observed in both LPS-induced ARDS mice and LPS-treated AMs, with upregulated expression of IL-12β and iNOS, namely M1 activation, and p65 nuclear translocation. Further in vitro studies showed that LPS-induced M1 activation could be counteracted by both lincRNA-p21 inhibition and inhibited NF-κB activation. Moreover, both p65 nuclear translocation and NF-κB activity were promoted by lincRNA-p21 overexpression, while lincRNA-p21 inhibition showed a negative effect on LPS-induced p65 nuclear translocation and increase of NF-κB activity. Additionally, LPS-induced lung injuries could be attenuated by lincRNA-p21 inhibition in vivo.Conclusion: This study revealed elevated lincRNA-p21 levels in LPS-induced ARDS and investigated the potential role of lincRNA-p21 in LPS-induced pro-inflammatory response via NF-κB/p65 mediated pathways, suggesting the potential application of lincRNA-p21 for ADRS therapy.

Hemorrhagic Shock/Resuscitation Reduces the M2 Phenotype of Alveolar Macrophages: A Potential Mechanism Contributing to Increased LPS-Induced Lung Injury

Major hemorrhage is a significant contributor to the morbidity and mortality resulting from traumatic injury. In addition to its role in in early mortality, hemorrhagic shock followed by resuscitation (HS/R) is known to initiate immunological events that contribute to the development of organ dysfunction. The pathogenesis of acute lung injury following HS/R involves macrophage activation. Recent studies have shown that macrophage function may in part be regulated by polarization toward classical M1 pro-inflammatory cells or alternatively activated anti-inflammatory M2 cells. We hypothesized that alteration in the M1/M2 phenotypic balance of alveolar macrophages in the lung may contribute to a pro-inflammatory state following HS/R. Using a murine model, we show that HS/R causes a rapid reduction in surface cluster of differentiation (CD)206 and CD36, markers of M2 cells, as well as in CD206 messenger ribonucleic acid (mRNA). M1 markers including surface CD80 and tumour necrosis factor alpha and inducible nitric oxide synthase mRNA were increased, albeit in a somewhat delayed time course. The prostaglandin 5-deoxyDelta12,14 prostaglandin J2 (15d-PGJ2), known to polarize cells toward M2, restored levels of M2 macrophages toward control and prevented lung injury, as assessed by bronchoalveolar protein content. Adoptive cell transfer of in vitro M2 polarized macrophages also reduced lung inflammation/injury following hemorrhagic shock. Together, these studies demonstrate that HS/R increases M1/M2 ratio, predominantly by lowering M2 cells, and thus enhances the proinflammatory state. Various strategies aimed at promoting M2 polarization may lessen the magnitude of inflammation and injury. This represents a novel approach to the prevention/treatment of lung injury in critically ill trauma patients.

Amphiregulin inhibits TNF-α-induced alveolar epithelial cell death through EGFR signaling pathway

BACKGROUND

We previously observed that amphiregulin (Areg), a ligand of epithelial growth factor receptor (EGFR), was highly expressed in lipopolysaccharide (LPS)-induced acute lung injury (ALI) lung tissues mainly by the classically activated (M1) alveolar macrophages (AMs). Areg also plays a protective role in LPS-induced injury in lung tissues and alveolar epithelial cells (AECs). However, whether Areg is co-expressed with tumor necrosis factor (TNF)-α in ALI lung tissues, and can directly inhibit TNF-α-induced AEC injury remains unclear.

METHODS

We first detected the kinetic expressions of Areg and TNF-α in LPS-stimulated lung tissues and M1 AMs and then identified the role of exogenous recombinant Areg (rmAreg) in the injured lung tissues. The effect of Areg on TNF-α-induced apoptosis in MLE-12 cells, a kind of AECs, was examined by terminal deoxynucleotidyl transferase dUTP nick end labeling staining. The activation of the EGFR-AKT pathway and caspase-3, -8, and -9 were detected by Western blotting. The EGFR knockdown by small interfering RNA was used to assess the role of EGFR in Areg functions.

RESULTS

Areg production occurred in close parallel with TNF-α expression in M1 AMs and ALI lung tissues, and rmAreg attenuated LPS-induced ALI in mice. TNF-α stimulation induced significant apoptosis in MLE-12 cells, but this apoptosis was inhibited under rmAreg treatment. Moreover, rmAreg enhanced the activation of EGFR and AKT, and reduced the expressions of cleaved caspase-3, -8, and -9 in ALI lung tissues and TNF-α-challenged MLE-12 cells. However, the EGFR knockdown significantly inhibited the Areg-induced improvement in apoptosis, enhancement of EGFR and AKT activation, and reduction of cleaved caspase-3, -8, and -9 expressions.

CONCLUSIONS

Areg and TNF-α were synchronously produced by ALI lung tissues and M1 AMs, and Areg directly inhibited the TNF-induced apoptosis and transduction of caspase death signals in AECs via the EGFR pathway.

Endoplasmic reticulum stress potentiates the autophagy of alveolar macrophage to attenuate acute lung injury and airway inflammation

Endoplasmic reticulum (ER) stress has been reported to play a role in acute lung injury (ALI), yet the in-depth mechanism remains elusive. This study aims to investigate the effect of ER stress-induced autophagy of alveolar macrophage (AM) on acute lung injury (ALI) and airway inflammation using mouse models. ALI models were induced by intranasal instillation of lipopolysaccharide (LPS). The lung weight/body weight (LW/BW) ratio and excised lung gas volume (ELGV) in each group were measured. Mouse bronchoalveolar lavage fluid (BALF) was collected for cell sorting and protein concentration determination. Expression of tumor necrosis factor α (TNF-α) and interleukin-6 (IL-6) in lung tissues and BALF was also detected. Mouse AMs were isolated to observe the autophagy. Expression of GRP78, PERK, LC3I, LC3II and Beclin1 was further determined. The results indicated that tunicamycin (TM) elevated GRP78 and PERK expression of AMs in ALI mice in a dose-dependent manner. Low dosage of TM abated LC3I expression, increased LC3II and Beclin1 expression, triggered ER stress and AM autophagy, and alleviated pathological changes of AMs in ALI mice. Also, in ALI mice, low dosage of TM attenuated goblet cell proliferation of tracheal wall, and declined LW/BW ratio, ELGV, total cells and neutrophils, protein concentrations in BALF, and IL-6 and TNF-α expression in lung tissues and BALF. Collectively, this study suggests that a low dosage of TM-induced ER stress can enhance the autophagy of AM in ALI mice models, thus attenuating the progression of ALI and airway inflammation.

Using Bronchoalveolar Lavage to Evaluate Changes in Pulmonary Diseases

Bronchoalveolar lavage (BAL) is a procedure that can be used to collect samples from human and animal lungs to efficiently evaluate the immune response and the potentially pathological changes by examining both the compositions of cells and fluid from lavage. There are observable changes including inflammatory response in human and animal lungs exposed to environmental exposures such as toxic chemicals and microorganisms, or under pathophysiological conditions in respiratory system. The profile of inflammatory cells in BAL provides a qualitative description of inflammatory response, and the secretion in BAL fluid contains secreted proteins of inflammatory mediators and albumin as a quantitative measurement of inflammation and tissue injury in the lungs. Mouse is the most common model system being used for pulmonary disease-related research. A consistent experimental approach on how to lavage mouse lungs and collect samples from mouse lungs is important for a reproducible evaluation of pathological and physiological changes in mouse lung especially for the analysis of inflammation.

PP2ACα of Alveolar Macrophages Is a Novel Protective Factor for LPS-Induced Acute Respiratory Distress Syndrome

Protein phosphatase 2A (PP2A) is one main serine/threonine phosphatase in eukaryotes, and its activation changes have been linked to modulation of numerous pathological processes, such as cancer, inflammation, fibrosis, and neurodegenerative diseases. Acute respiratory distress syndrome (ARDS), the major cause of respiratory failure, remains with limited therapies available up to now. Alveolar macrophages (AMs) are essential to innate immunity and host defense, participating in the pathogenesis of ARDS. As a result, AMs are considered as a potential therapeutic target for ARDS. In our study, we firstly found that PP2A activity was significantly decreased in the lipopolysaccharide (LPS)-stimulated AMs. Furthermore, adoptive transfer of AMs with enhanced PP2A enzyme activity that was improved by C2-ceramide prior to LPS exposure alleviated acute lung inflammation. Conversely, AM-specific ablation of PP2ACα exacerbated inflammatory responses to LPS. Mechanistically, PP2ACα negatively regulates LPS-induced cytokine secretion of AMs by NF-κB and MAPK pathways. Together, these findings provide the evidence to guide the development of novel therapeutic options targeting PP2ACα for ARDS/acute lung injury.

Exosomes derived from pro-inflammatory bone marrow-derived mesenchymal stem cells reduce inflammation and myocardial injury via mediating macrophage polarization

Exosomes are served as substitutes for stem cell therapy, playing important roles in mediating heart repair during myocardial infarction injury. Evidence have indicated that lipopolysaccharide (LPS) pre-conditioning bone marrow-derived mesenchymal stem cells (BMSCs) and their secreted exosomes promote macrophage polarization and tissue repair in several inflammation diseases; however, it has not been fully elucidated in myocardial infarction (MI). This study aimed to investigate whether LPS-primed BMSC-derived exosomes could mediate inflammation and myocardial injury via macrophage polarization after MI. Here, we found that exosomes derived from BMSCs, in both Exo and L-Exo groups, increased M2 macrophage polarization and decreased M1 macrophage polarization under LPS stimulation, which strongly depressed LPS-dependent NF-κB signalling pathway and partly activated the AKT1/AKT2 signalling pathway. Compared with Exo, L-Exo had superior therapeutic effects on polarizing M2 macrophage in vitro and attenuated the post-infarction inflammation and cardiomyocyte apoptosis by mediating macrophage polarization in mice MI model. Consequently, we have confidence in the perspective that low concentration of LPS pre-conditioning BMSC-derived exosomes may develop into a promising cell-free treatment strategy for clinical treatment of MI.

Scrub Typhus Pathogenesis: Innate Immune Response and Lung Injury During Orientia tsutsugamushi Infection

Scrub typhus is an understudied, potentially lethal disease caused by infection with Orientia tsutsugamushi. Despite causing an estimated 1 million cases per year and an increasing global presence, mechanisms of scrub typhus pathogenesis remain unclear. One of the most life-threatening conditions that can arise in scrub typhus patients is acute respiratory distress syndrome (ARDS). The development of ARDS is a complex process; some of its pathological hallmarks, including prolonged recruitment of inflammatory immune cells to the lung and vasculature damage, have been observed in humans and/or animal models of O. tsutsugamushi infection. Although different cell types and mechanisms may contribute to ARDS development during O. tsutsugamushi infection, this review highlights our current evidence of pulmonary endothelial activation and damage, the potential roles of neutrophils and macrophages in the lung, and the knowledge gaps in this field. Continued investigation of the lung microenvironment and cellular interactions will help elucidate disease pathogenesis and possible treatment during scrub typhus.

Macrophages Are Key Regulators of Stem Cells during Skeletal Muscle Regeneration and Diseases

Muscle regeneration is a closely regulated process that involves a variety of cell types such as satellite cells, myofibers, fibroadipogenic progenitors, endothelial cells, and inflammatory cells. Among these different cell types, macrophages emerged as a central actor coordinating the different cellular interactions and biological processes. Particularly, the transition of macrophages from their proinflammatory to their anti-inflammatory phenotype was shown to regulate inflammation, myogenesis, fibrosis, vascularization, and return to homeostasis. On the other hand, deregulation of macrophage accumulation or polarization in chronic degenerative muscle disorders was shown to impair muscle regeneration. Considering the key roles of macrophages in skeletal muscle, they represent an attractive target for new therapeutic approaches aiming at mitigating various muscle disorders. This review aims at summarizing the novel insights into macrophage heterogeneity, plasticity, and functions in skeletal muscle homeostasis, regeneration, and disease.

CXCR4 knockdown prevents inflammatory cytokine expression in macrophages by suppressing activation of MAPK and NF-κB signaling pathways

Background

Recent evidence has shown that C-X-C chemokine receptor type 4 (CXCR4) plays a crucial role in acute lung injury (ALI). Macrophages are key factors in the pathogenesis of ALI. The aim of this study was to investigate the role of CXCR4 in macrophages after lipopolysaccharide (LPS) stimulation and confirm that CXCR4 knockdown can inhibit inflammatory cytokines by suppressing mitogen-activated protein kinase (MAPK) and nuclear factor-κB (NF-κB) signaling pathway activation.

Results

In this study, we found that CXCR4 expression in lung tissue of ALI was significantly increased using immunofluorescence. We also found that the expression of CXCR4 in macrophages sorted from bronchoalveolar lavage fluid (BALF) of ALI was obviously upregulated through RT-qPCR. After CXCR4 knockdown using siRNA, we found that the expression of interleukin-6 (IL-6) and tumor necrosis factor alpha (TNF-α) was obviously down regulated in macrophages. Additionally, the phosphorylation of p38, Erk, and p65 was significantly decreased after CXCR4 knockdown through western blotting.

Conclusions

Taken together, the present study suggests that CXCR4 knockdown may inhibit inflammatory cytokine expression in macrophages by suppressing MAPK and NF-κB signaling pathway activation. Therefore, CXCR4 knockdown may have potential clinical value in treating ALI.

Insulin Signaling and Insulin Resistance Facilitate Trained Immunity in Macrophages Through Metabolic and Epigenetic Changes

Adaptation of the innate immune system has been recently acknowledged, explaining sustained changes of innate immune responses. Such adaptation is termed trained immunity. Trained immunity is initiated by extracellular signals that trigger a cascade of events affecting cell metabolism and mediating chromatin changes on genes that control innate immune responses. Factors demonstrated to facilitate trained immunity are pathogenic signals (fungi, bacteria, viruses) as well non-pathogenic signals such as insulin, cytokines, adipokines or hormones. These signals initiate intracellular signaling cascades that include AKT kinases and mTOR as well as histone methylases and demethylases, resulting in metabolic changes and histone modifications. In the context of insulin resistance, AKT signaling is affected resulting in sustained activation of mTORC1 and enhanced glycolysis. In macrophages elevated glycolysis readily impacts responses to pathogens (bacteria, fungi) or danger signals (TLR-driven signals of tissue damage), partly explaining insulin resistance-related pathologies. Thus, macrophages lacking insulin signaling exhibit reduced responses to pathogens and altered metabolism, suggesting that insulin resistance is a state of trained immunity. Evidence from Insulin Receptor as well as IGF1Receptor deficient macrophages support the contribution of insulin signaling in macrophage responses. In addition, clinical evidence highlights altered macrophage responses to pathogens or metabolic products in patients with systemic insulin resistance, being in concert with cell culture and animal model studies. Herein, we review the current knowledge that supports the impact of insulin signaling and other insulin resistance related signals as modulators of trained immunity.

SALL4-mediated upregulation of exosomal miR-146a-5p drives T-cell exhaustion by M2 tumor-associated macrophages in HCC

Emerging evidence indicates that cancer cell-derived exosomes contribute to cancer progression through the modulation of tumor microenvironment, but the underlying mechanisms are not fully elucidated. Here, we reported that hepatocellular carcinoma (HCC)-derived exosomes could remodel macrophages by activating NF-κB signaling and inducing pro-inflammatory factors, and resulted in M2-polarized tumor-associated macrophages. In addition, the expression of IFN-γ and TNF-α was inhibited, while the expression of inhibitory receptors such as PD-1 and CTLA-4 was upregulated in T cells by HCC-derived exosome educated macrophages. Data also revealed that HCC exosomes were enriched with miR-146a-5p and promoted M2-polarization. Further investigation demonstrated that the transcription factor Sal-like protein-4 (SALL4) was critical for regulating miR-146a-5p in HCC exosomes and M2-polarization. Mechanistically, SALL4 could bind to the promoter of miR-146a-5p, and directly controlled its expression in exosomes. Blocking the SALL4/miR-146a-5p interaction in HCC reduced the expression of inhibitory receptors on T cells, reversed T cell exhaustion, and delayed HCC progression in DEN/CCL₄-induced HCC mice. In conclusion, identification of a role of the exosomal SALL4/miR-146a-5p regulatory axis in M2-polarization as well as HCC progression provides potential targets for therapeutic and diagnostic applications in liver cancer.

A Molecular Targeted Immunotherapeutic Strategy for Ulcerative Colitis via Dual-targeting Nanoparticles Delivering miR-146b to Intestinal Macrophages

BACKGROUND AND AIMS

Macrophages are a promising therapeutic target for intestinal mucosal repair. MiR-146b appears to control macrophage activation and cell proliferation.

METHODS

By loading miR-146b mimic on mannose-modified trimethyl chitosan [MTC]-conjugated nanoparticles [NPs] [MTC-miR146b], a molecular targeted immunotherapeutic approach was developed to selectively target intestinal macrophages for mucosal regeneration and tumourigenesis in mouse models.

RESULTS

We first confirmed that miR-146b expression was significantly enhanced during mucosal regeneration in a murine colitis model. Moreover， after mucosal damage, MTC-miR146b mimic-treated wild-type mice had dramatically restored body weight and mucosal barrier function compared with MTC-NC treated mice. Strikingly, MTC-miR146b mimic oral administration protected miR-146b-deficient mice from dextran sodium sulphate [DSS] injury and the colitis-associated cancer process. Mechanistically, miR-146b strongly inhibited M1 macrophage activation by suppressing the Toll-like receptor 4 [TLR4] signalling pathway, resulting in the repression of the induction of pro-inflammatory cytokines including TNF-α, IL-6, and IL-1β. More importantly, miR-146b overexpression in bone marrow-derived macrophages [BMDMs] in M1 differentiation conditions induced a phenotype similar to M2 macrophages and improved the proliferation of co-cultured colonic epithelial cells via STAT3-dependent IL-10 production.

CONCLUSIONS

MTC-miR146b should be regarded as an effective candidate for oral delivery and could improve the efficacy of immunotherapies for ulcerative colitis and colitis-associated cancer.

Insulin Resistance in Macrophages Alters Their Metabolism and Promotes an M2-Like Phenotype

Obesity and insulin resistance influences metabolic processes, but whether it affects macrophage metabolism is not known. In this study, we demonstrate that chronic exposure of macrophages to insulin either in culture or in vivo in diet-induced, glucose-intolerant mice rendered them resistant to insulin signals marked by failure to induce Akt2 phosphorylation. Similarly, macrophages lacking Akt2 or IGF1 receptor were also resistant to insulin signals. Insulin-resistant macrophages had increased basal mTORC1 activity, possessed an M2-like phenotype, and reduced LPS responses. Moreover, they exhibited increased glycolysis and increased expression of key glycolytic enzymes. Inhibition of mTORC1 reversed the M2-like phenotype and suppressed glycolysis in insulin-resistant macrophages. In the context of polymicrobial sepsis, mice harboring insulin-resistant macrophages exhibited reduced sepsis-induced lung injury. Thus, macrophages obtain resistance to insulin characterized by increased glycolysis and a unique M2-like phenotype, termed M-insulin resistant, which accounts for obesity-related changes in macrophage responses and a state of trained immunity.

Neorogioltriol and Related Diterpenes from the Red Alga Laurencia Inhibit Inflammatory Bowel Disease in Mice by Suppressing M1 and Promoting M2-Like Macrophage Responses

Macrophages are central mediators of inflammation, orchestrating the inflammatory response through the production of cytokines and nitric oxide. Macrophages obtain pro-inflammatory (M1) and anti-inflammatory (M2) phenotypes, which can be modulated by soluble factors, including natural products. Despite the crucial protective role of inflammation, chronic or deregulated inflammation can lead to pathological states, such as autoimmune diseases, metabolic disorders, cardiovascular diseases, and cancer. In this case, we studied the anti-inflammatory activity of neorogioltriol (1) in depth and identified two structurally related diterpenes, neorogioldiol (2), and O¹¹,15-cyclo-14-bromo-14,15-dihydrorogiol-3,11-diol (3), with equally potent activity. We investigated the mechanism of action of metabolites 1⁻3 and found that all three suppressed macrophage activation and promoted an M2-like anti-inflammatory phenotype by inducing expression of Arginase1, MRC1, IRAK-M, the transcription factor C/EBPβ, and the miRNA miR-146a. In addition, they suppressed iNOS induction and nitric oxide production. Importantly, treatment of mice with 2 or 3 suppressed DSS-induced colitis by reducing tissue damage and pro-inflammatory cytokine production. Thus, all these three diterpenes are promising lead molecules for the development of anti-inflammatory agents targeting macrophage polarization mechanisms.

Membrane-Binding Adhesive Particulates Enhance the Viability and Paracrine Function of Mesenchymal Cells for Cell-Based Therapy

Understanding the fundamental cell-material interactions is essential to designing functional materials for biomedical applications. Although mesenchymal stromal cells (MSCs) are known to secrete cytokines and exosomes that are effective to treat degenerative diseases, the inherent property of biomaterials to modulate the therapeutic function of MSCs remains to be investigated. Here, a multivalent cell-membrane adhesive conjugate was generated through polyamindoamine (PAMAM) and an oligopeptide, IKVAV, and the conjugate was further complexed with hyaluronic acid (HA). The adhesive particulates were used to coat the surface of adipose-derived mesenchymal stromal cells (Ad-MSCs) and studied in the MSC spheroid culture. The analysis showed that the adhesive complexes formed via PAMAM conjugates and HA significantly promoted the proliferation and the gene expression of pro-angiogenesis cytokines in MSCs; the production of anti-inflammatory miRNAs in exosomes could also be elevated. The transplantation of the Ad-MSCs primed with PAMAM-IKVAV/HA composite particulates in a rat myocardial infarction model further demonstrated the beneficial effects of membrane-binding materials on improving the cell retention and tissue angiogenesis. The new function of membrane-binding adhesive materials potentially provides useful ways to improve cell-based therapy.

miR‑625‑5p suppresses inflammatory responses by targeting AKT2 in human bronchial epithelial cells

Asthma is a common chronic inflammatory airway disease; however, whether microRNAs (miRs) could be used in the treatment of asthma remains unclear. The aim of the present study was to investigate the role of miR‑625‑5p in the inflammatory response of human bronchial epithelial cells (HBECs). Inflammation in the HBEC line, 16HBEC, was induced using different concentrations of lipopolysaccharide (LPS), which demonstrated that 1 µg/ml LPS was an appropriate concentration for further experiments. The association between protein kinase B2 (AKT2) and miR‑625‑5p was verified using a luciferase reporter assay. LPS was added to 16HBECs following the administration of miR‑625‑5p mimics or miR‑625‑5p inhibitors, and cells with silenced or overexpressed AKT2 levels. miR‑625‑5p was expressed at a high level in LPS‑activated 16HBECs. Overexpression of miR‑625‑5p inhibited interleukin (IL)‑6 and tumor necrosis factor (TNF)‑α secretion in 16HBECs. Inhibition of miR‑625‑5p enhanced LPS‑induced IL‑6 and TNF‑α secretion. miR‑625‑5p negatively regulated the expression of AKT2 in 16HBECs. A dual‑luciferase reporter assay system confirmed that miR‑625‑5p directly targeted the 3'untranslated region of AKT2. Transfection with a small interfering RNA against AKT2 inhibited inhibitor of κB phosphorylation. In brief, miR‑625‑5p may protect LPS‑induced HBECs by targeting AKT2 and inhibiting the nuclear factor‑κB signaling pathway. Therefore, miR‑625‑5p may function as an inhibitor of asthma airway inflammation in HBECs by targeting AKT2.

Overexpression of miR-146a Might Regulate Polarization Transitions of BV-2 Cells Induced by High Glucose and Glucose Fluctuations

Microglia are critical in neuroinflammation. M1/M2 polarization transitions of microglial phenotypes determine the states of neuroinflammation and are regulated by multiple pathways, including miRNAs and other epigenetic regulations. This study investigated the polarization transitions of microglia induced by high glucose and glucose fluctuations, and the role of miR-146a in regulating M1/M2 polarization transitions of microglia. BV-2 cells were cultured with 25 mmol/L glucose, 75 mmol/L glucose, and 25 mmol/L-75 mmol/L glucose fluctuation for 48 h. BV-2 cells overexpressing miR-146a were generated using a lentiviral vector. Quantitative real-time polymerase chain reaction (qRT-PCR) was used to measure mRNA expression of miR-146a, CD11b, iNOS, Arg-1, IRAK1, TRAF6, and NF-κB. Immunofluorescence was used to measure CD11b expression. Western blot was used to measure protein expression of CD11b, iNOS, and Arg-1. Compared with those in the 25 mmol/L glucose control group, expression of CD11b, iNOS, TNF-α, and IL-6 in the 75 mmol/L glucose or glucose fluctuation groups of cultured BV-2 cells were significantly increased, while Arg-1 and IL-10 was significantly decreased. These effects were reversed by overexpression of miR-146a. Furthermore, expression of IRAK1, TRAF6, and NF-κB was significantly increased in the high glucose and glucose fluctuation groups; this was reduced after miR-146a overexpression. In sum, high glucose and glucose fluctuations induced polarization transitions from M1 to M2 phenotype in BV-2 cells. Overexpression of miR-146a might protect BV-2 cells from high glucose and glucose fluctuation associated with M1/M2 polarization transitions by downregulating the expression of IRAK1, TRAF6, and NF-κB.

Downregulated microRNA-27b attenuates lipopolysaccharide-induced acute lung injury via activation of NF-E2-related factor 2 and inhibition of nuclear factor κB signaling pathway

Acute lung injury (ALI) is a life-threatening, diffuse heterogeneous lung injury characterized by acute onset, pulmonary edema, and respiratory failure. Lipopolysaccharide (LPS) is a leading cause for ALI and when administered to a mouse it induces a lung phenotype exhibiting some of the clinical characteristics of human ALI. This study focused on investigating whether microRNA-27b (miR-27b) affects ALI in a mouse model established by LPS-induction and to further explore the underlying mechanism. After model establishment, the mice were treated with miR-27b agomir, miR-27b antagomir, or D-ribofuranosylbenzimidazole (an inhibitor of nuclear factor-E2-related factor 2 [Nrf2]) to determine levels of miR-27b, Nrf2, nuclear factor kappa-light-chain-enhancer of activated B cells nuclear factor κB (NF-κB), p-NF-κB, and heme oxygenase-1 (HO-1). The levels of interleukin (IL)-1β, IL-6, and tumor necrosis factor-α (TNF-α) in bronchoalveolar lavage fluid (BALF) were determined. The results of luciferase activity suggested that Nrf2 was a target gene of miR-27b. It was indicated that the Nrf2 level decreased in lung tissues from ALI mice. The downregulation of miR-27b decreased the levels of IL-1β, IL-6, and TNF-α in BALF of ALI mice. Downregulated miR-27b increased Nrf2 level, thus enhancing HO-1 level along with reduction of NF-κB level as well as the extent of NF-κB phosphorylation in the lung tissues of the transfected mice. Pathological changes were ameliorated in LPS-reduced mice elicited by miR-27b inhibition. The results of this study demonstrate that downregulated miR-27b couldenhance Nrf2 and HO-1 expressions, inhibit NF-κB signaling pathway, which exerts a protective effect on LPS-induced ALI in mice.

Regulation of Endotoxin Tolerance and Compensatory Anti-inflammatory Response Syndrome by Non-coding RNAs

The onset and the termination of innate immune response must be tightly regulated to maintain homeostasis and prevent excessive inflammation, which can be detrimental to the organism, particularly in the context of sepsis. Endotoxin tolerance and compensatory anti-inflammatory response syndrome (CARS) describe a state of hypo-responsiveness characterized by reduced capacity of myeloid cells to respond to inflammatory stimuli, particularly those initiated by bacterial lipopolysaccharide (LPS). To achieve endotoxin tolerance, extensive reprogramming otherwise termed as “innate immune training”, is required that leads to both modifications of the intracellular components of TLR signaling and also to alterations in extracellular soluble mediators. Non-coding RNAs (ncRNAs) have been recognized as critical regulators of TLR signaling. Specifically, several microRNAs (miR-146, miR-125b, miR-98, miR-579, miR-132, let-7e and others) are induced upon TLR activation and reciprocally promote endotoxin tolerance and/or cross tolerance. Many other miRNAs have been also shown to negatively regulate TLR signaling. The long non-coding (lnc)RNAs (Mirt2, THRIL, MALAT1, lincRNA-21 and others) are also altered upon TLR activation and negatively regulate TLR signaling. Furthermore, the promotion or termination of myeloid cell tolerance is not only regulated by intracellular mediators but is also affected by other TLR-independent soluble signals that often achieve their effect via modulation of intracellular ncRNAs. In this article, we review recent evidence on the role of different ncRNAs in the context of innate immune cell tolerance and trained immunity, and evaluate their impact on immune system homeostasis.

Role of microRNA in severe asthma

The various roles of microRNAs (miRNAs) in the epigenetic regulation of human disease are gaining importance as areas of research, and a better understanding of these roles may identify targets for development of novel therapies for severe asthma. MiRNAs, a class of small non-coding RNAs that serve as post-transcriptional gene repressors, are recognized as critical components in regulating tissue homeostasis. Alteration in miRNA expression disrupts homeostasis and is an underlying mechanism for development of chronic respiratory diseases, including asthma. Differential profiles of miRNA expression are involved in inflammation and remodeling pathogenicity via activating airway structural cells and immune cells and inducing cytokine releases. miRNA action leads to asthma progression from mild to severe stages. Here, current knowledge of the heterogeneous roles of miRNAs in severe asthma, including biological mechanisms underlying Th2 and macrophage polarization, type 2 innate lymphoid cell (ILC2) biology regulation, steroid-resistant asthma phenotype, airway smooth muscle (ASM) dysfunction, and impaired anti-viral innate immune, are reviewed.

Smiglaside A ameliorates LPS-induced acute lung injury by modulating macrophage polarization via AMPK-PPARγ pathway

Macrophages, which have various phenotypes and diverse functions, are becoming the target cells in inflammatory diseases. In this study, we evaluated the effects of the natural product smiglaside A, a phenylpropanoid glycoside isolated from the traditional Chinese medicinal herb Smilax riparia, on macrophage polarization and investigated the underlying mechanisms. We found that smiglaside A promoted M2 polarization and reduced M1 polarization in LPS-stimulated RAW264.7 cells and primary mouse peritoneal macrophages. Further mechanistic studies showed that the promoting effect of smiglaside A on M2 polarization was attenuated by pharmacological inhibition or gene silencing of AMP-activated protein kinase (AMPK) or peroxisome proliferator-activated receptor γ (PPARγ). Moreover, smiglaside A-enhanced PPARγ activity was prevented by the AMPK inhibitor compound C and by an siRNA. These findings indicate that the AMPK-PPARγ pathway is involved in promotion of M2 macrophages by smiglaside A. In a mouse model of LPS-induced acute lung injury, smiglaside A significantly increased the survival rate of LPS-injected mice and ameliorated the LPS-induced inflammatory response and lung damage. In addition, smiglaside A enhanced the protein expression levels of phosphorylated AMPK and PPARγ in the lung and promoted alveolar macrophages to the M2 phenotype in this mouse model. Taken together, our results indicate that smiglaside A can promote macrophage polarization to an anti-inflammatory M2 phenotype via stimulating the AMPK-PPARγ signaling pathway. Our study may provide novel approaches and/or targets for drug development to treat inflammatory diseases such as acute lung injury and sepsis.

Pro inflammatory stimuli enhance the immunosuppressive functions of adipose mesenchymal stem cells-derived exosomes

The predominant mechanism by which adipose mesenchymal stem cells (AMSCs) participate to tissue repair is through a paracrine activity and their communication with the inflammatory microenvironment is essential part of this process. This hypothesis has been strengthened by the recent discovery that stem cells release not only soluble factors but also extracellular vesicles, which elicit similar biological activity to the stem cells themselves. We demonstrated that the treatment with inflammatory cytokines increases the immunosuppressive and anti-inflammatory potential of AMSCs-derived exosomes, which acquire the ability to shift macrophages from M1 to M2 phenotype by shuttling miRNA regulating macrophages polarization. This suggests that the immunomodulatory properties of AMSCs-derived exosomes may be not constitutive, but are instead induced by the inflammatory microenvironment.

Involvement of miR-455 in the protective effect of H2S against chemical hypoxia-induced injury in BEAS-2B cells

The protective effect of hydrogen sulfide (H₂S) against hypoxia-induced injury via anti-apoptosis is well established, but the underlying mechanism remains unclear. The present study aimed to investigate whether miR-455 participated in the H₂S protection of lung epithelial cells against CoCl₂-induced apoptosis by regulating endoplasmic reticulum stress (ERS)-related genes. Human lung epithelial cells BEAS-2B were subjected to hypoxia injury with or without H₂S preconditioning. It was found that hypoxia injury increased apoptosis of BEAS-2B cells, down-regulated the expression of miR-455, and upregulated the expression of calreticulin (Calr). H₂S preconditioning attenuated lung epithelial cells apoptosis, enhanced cell viability, up-regulated the expression of miR-455, as well as down-regulated the expression of Calr following hypoxia injury. In addition, Calr, GRP78, C/EBP homologous protein (CHOP) and Caspase-12 protein was down-regulated by the miR-455 mimic and up-regulated by the miR-455 inhibitor. These results implicate miR-455 regulated H₂S protection of lung epithelial cells against hypoxia-induced apoptosis by stimulating Calr.

DHEA inhibits acute microglia-mediated inflammation through activation of the TrkA-Akt1/2-CREB-Jmjd3 pathway

Dehydroepiandrosterone (DHEA) is the most abundant circulating steroid hormone in humans, produced by the adrenals, the gonads and the brain. DHEA was previously shown to bind to the nerve growth factor receptor, tropomyosin-related kinase A (TrkA), and to thereby exert neuroprotective effects. Here we show that DHEA reduces microglia-mediated inflammation in an acute lipopolysaccharide-induced neuro-inflammation model in mice and in cultured microglia in vitro. DHEA regulates microglial inflammatory responses through phosphorylation of TrkA and subsequent activation of a pathway involving Akt1/Akt2 and cAMP response element-binding protein. The latter induces the expression of the histone 3 lysine 27 (H3K27) demethylase Jumonji d3 (Jmjd3), which thereby controls the expression of inflammation-related genes and microglial polarization. Together, our data indicate that DHEA-activated TrkA signaling is a potent regulator of microglia-mediated inflammation in a Jmjd3-dependent manner, thereby providing the platform for potential future therapeutic interventions in neuro-inflammatory pathologies.

Nrf2 protects against acute lung injury and inflammation by modulating TLR4 and Akt signaling

Lung injury, which is associated with systemic inflammatory responses, is a common problem with significant morbidity and mortality. Here, we examined the involvement of toll-like receptor 4 (TLR4) and nuclear factor erythroid 2-related factor 2 (Nrf2) on intestinal ischemia-reperfusion (I/R)-induced lung injury in vivo and in vitro. Analysis of lung tissues in Nrf2-knockout mice by western blotting, immunohistochemistry, and TUNEL assay, and analysis of bronchoalveolar lavage fluid showed that Nrf2 deficiency upregulated TLR4, enhanced I/R-induced lung injury, apoptosis, inflammation, and autophagy, and increased the I/R-induced inactivation of Akt. In mouse lung epithelial cells subjected to oxygen and glucose deprivation/reperfusion (OGD/Rep), Nrf2 silencing increased the OGD/Rep-induced upregulation of TLR4 and MyD88 and downregulation of HO-1, and exacerbated OGD/Rep-induced apoptosis, autophagy, and the downregulation of phospho-Akt. TLR4 silencing and Akt inhibition experiments indicated that OGD/Rep-induced cell death by suppressing Akt signaling, and Nrf2 protected lung cells by modulating TLR4 and Akt signaling. These results indicated that the Nrf2/TLR4/Akt axis plays a role in inflammation-associated lung damage, suggesting potential therapeutic targets for the treatment of lung injury.

Transcriptional Regulation of Macrophages Polarization by MicroRNAs

Diversity and plasticity are the hallmarks of cells from the monocyte-macrophage lineage. Macrophages undergo classical M1 or alternative M2 activation in response to the microenvironment signals. Several transcription factors, such as peroxisome proliferator-activated receptors, signal transducers and activators of transcription, CCAAT-enhancer-binding proteins, interferon regulatory factors, Kruppel-like factors, GATA binding protein 3, nuclear transcription factor-κB, and c-MYC, were found to promote the expression of specific genes, which dictate the functional polarization of macrophages. Importantly, these transcription factors can be regulated by microRNAs (miRNAs), a group of small non-coding RNAs, which regulate gene expression through translation repression or mRNA degradation. Recent studies have also revealed that miRNAs control macrophage polarization by regulating transcription factors in response to the microenvironment signals. This review will summarize recent progress of miRNAs in the transcriptional regulation of macrophage polarization and provide the insights into the development of macrophage-centered diagnostic and therapeutic strategies.

The Role of Macrophages in the Pathogenesis of ALI/ARDS

Despite development in the understanding of the pathogenesis of acute lung injury (ALI)/acute respiratory distress syndrome (ARDS), the underlying mechanism still needs to be elucidated. Apart from leukocytes and endothelial cells, macrophages are also essential for the process of the inflammatory response in ALI/ARDS. Notably, macrophages play a dual role of proinflammation and anti-inflammation based on the microenvironment in different pathological stages. In the acute phase of ALI/ARDS, resident alveolar macrophages, typically expressing the alternatively activated phenotype (M2), shift into the classically activated phenotype (M1) and release various potent proinflammatory mediators. In the later phase, the M1 phenotype of activated resident and recruited macrophages shifts back to the M2 phenotype for eliminating apoptotic cells and participating in fibrosis. In this review, we summarize the main subsets of macrophages and the associated signaling pathways in three different pathological phases of ALI/ARDS. According to the current literature, regulating the function of macrophages and monocytes might be a promising therapeutic strategy against ALI/ARDS.

Effects and molecular mechanisms of intrauterine infection/inflammation on lung development

BACKGROUND

Intrauterine infection/inflammation plays an important role in the development of lung injury and bronchopulmonary dysplasia (BPD) in preterm infants, While a multifactorial genesis is likely, mechanisms involved in BPD after intrauterine infection/inflammation are largely unknown. Recent studies have suggested microRNAs (miRNAs) are likely to play a role. Therefore, this study aimed to study the effects and mechanisms of intrauterine infection/inflammation on lung development, and to identify miRNAs related to lung injury and BPD.

METHODS

An animal model of intrauterine infection/inflammation was established with pregnant SD rats endocervically inoculated with E.coli. The fetal and neonatal rats were observed at embryonic day (E) 17, 19, 21 and postnatal day (P) 1, 3, 7, 14, respectively. Body weight, lung weight, the expression levels of NLRP3, TNF-α, IL-lβ, IL-6, VEGF, Collagen I, SP-A, SP-B and SP-C in the lung tissues of fetal and neonatal rats were measured. Expression profiles of 1218 kinds of miRNAs in the lungs of neonatal rats were detected by miRNA microarray technique. Target genes of the identified miRNAs were predicted through online software.

RESULTS

Intrauterine infection/inflammation compromised not only weight development but also lung development of the fetal and neonatal rats. The results showed significantly increased expression of NLRP3, TNF-α, IL-1β, IL-6, Collagen I, and significantly decreased expression of VEGF, SP-A, SP-B and SP-C in the fetal and neonatal rat lung tissues in intrauterine infection group compared to the control group at different observation time point (P < 0.05). Forty-three miRNAs with significant differential expression were identified. Possible target genes regulated by the identified miRNAs are very rich.

CONCLUSIONS

Intrauterine infection/inflammation results in lung histological changes which are very similar to those observed in BPD. Possible mechanisms may include NLRP3 inflammasome activation followed by inflammatory cytokines expression up-regulated, inhibiting the expression of pulmonary surfactant proteins, interfering with lung interstitial development. There are many identified miRNAs which target a wide range of genes and may play an important role in the processes of lung injury and BPD.

Candidate Genes as Biomarkers in Lipopolysaccharide-Induced Acute Respiratory Distress Syndrome Based on mRNA Expression Profile by Next-Generation RNA-Seq Analysis

Up until now, the regulation mechanism at the level of gene during lipopolysaccharide- (LPS-) induced acute respiratory distress syndrome (ARDS) remains unclear. The discovery of differentially expressed genes (DEGs) between LPS-induced ARDS rats and normal rats by next-generation RNA sequencing analysis is of particular interest for the current study. These DEGs may help clinical diagnosis of ARDS and facilitate the selection of the optimal treatment strategy. Randomly, 20 rats were equally divided into 2 groups, the control group and the LPS group. Three rats from each group were selected at random for RNA sequencing analysis. Sequence reads were obtained from Illumina HiSeq4000 and mapped onto the rat reference genome RN6 using Hisat2. We identified 5244 DEGs (Fold_Change > 1.5, and P < 0.05) in the lung tissues from LPS-treated rats compared with normal rats, including 1413 upregulated and 3831 downregulated expressed genes. Lots of chemokine family members were among the most upregulated genes in LPS group. Gene ontology (GO) analysis revealed that almost all of the most enriched and meaningful biological process terms were mainly involved in the functions like immune-inflammation response and the pathways like cytokine-cytokine receptor interaction. We also found that, as for GO molecular function terms, the enriched terms were mainly related to chemokines and cytokines. DEGs with fold change over 100 were verified by quantitative real-time polymerase chain reaction and reanalyzed by gene-gene coexpression network, and the results elucidated central roles of chemokines in LPS-induced ARDS. Our results revealed some new biomarkers for uncovering mechanisms and processes of ARDS.

Middle east respiratory syndrome corona virus spike glycoprotein suppresses macrophage responses via DPP4-mediated induction of IRAK-M and PPARγ

Middle East Respiratory Syndrome Corona Virus (MERS-CoV) is transmitted via the respiratory tract and causes severe Acute Respiratory Distress Syndrome by infecting lung epithelial cells and macrophages. Macrophages can readily recognize the virus and eliminate it. MERS-CoV infects cells via its Spike (S) glycoprotein that binds on Dipeptidyl-Peptidase 4 (DPP4) receptor present on macrophages. Whether this Spike/DPP4 association affects macrophage responses remains unknown. Herein we demonstrated that infection of macrophages with lentiviral particles pseudotyped with MERS-CoV S glycoprotein results in suppression of macrophage responses since it reduced the capacity of macrophages to produce TNFα and IL-6 in naive and LPS-activated THP-1 macrophages and augmented LPS-induced production of the immunosuppressive cytokine IL-10. MERS-CoV S glycoprotein induced the expression of the negative regulator of TLR signaling IRAK-M as well as of the transcriptional repressor PPARγ. Inhibition of DPP4 by its inhibitor sitagliptin or siRNA abrogated the effects of MERS-CoV S glycoprotein on IRAK-M, PPARγ and IL-10, confirming that its immunosuppressive effects were mediated by DPP4 receptor. The effect was observed both in THP-1 macrophages and human primary peripheral blood monocytes. These findings support a DPP4-mediated suppressive action of MERS-CoV in macrophages and suggest a potential target for effective elimination of its pathogenicity.

MiRNA-Mediated Macrophage Polarization and its Potential Role in the Regulation of Inflammatory Response

Monocytes and macrophages are important components of the immune system, specialized in either removing pathogens as part of innate immunity or contributing to adaptive immunity through antigen presentation. Essential to such functions is classical activation (M1) and alternative activation (M2) of macrophages. M1 polarization of macrophages is characterized by production of pro-inflammatory cytokines, antimicrobial and tumoricidal activity, whereas M2 polarization of macrophages is linked to immunosuppression, tumorigenesis, wound repair, and elimination of parasites. MiRNAs are small non-coding RNAs with the ability to regulate gene expression and network of cellular processes. A number of studies have determined miRNA expression profiles in M1 and M2 polarized human and murine macrophages using microarray and RT-qPCR arrays techniques. More specifically, miR-9, miR-127, miR-155, and miR-125b have been shown to promote M1 polarization while miR-124, miR-223, miR-34a, let-7c, miR-132, miR-146a, and miR-125a-5p induce M2 polarization in macrophages by targeting various transcription factors and adaptor proteins. Further, M1 and M2 phenotypes play distinctive roles in cell growth and progression of inflammation-related diseases such as sepsis, obesity, cancer, and multiple sclerosis. Hence, miRNAs that modulate macrophage polarization may have therapeutic potential in the treatment of inflammation-related diseases. This review highlights recent findings in miRNA expression profiles in polarized macrophages from murine and human sources, and summarizes how these miRNAs regulate macrophage polarization. Last, therapeutic potential of miRNAs in inflammation-related diseases through modulation of macrophage polarization is also discussed.

Anti-inflammatory effect of stem bark of Paulownia tomentosa Steud. in lipopolysaccharide (LPS)-stimulated RAW264.7 macrophages and LPS-induced murine model of acute lung injury

ETHNOPHARMACOLOGICAL RELEVANCE

The leaves, bark, and flowers of Paulownia tomentosa Steud. have been widely used as a traditional medicine in East Asia to treat inflammatory and infectious diseases.

AIM OF THE STUDY

We investigated the protective effect of the methanol stem bark extract of P. tomentosa using an animal model of lipopolysaccharide (LPS)-induced acute lung injury (ALI).

MATERIALS AND METHODS

The UPLC Q-TOF-MS profiles for the methanol extract of P. tomentosa stem bark showed that verbascoside and isoverbascoside were the predominant compounds. Raw 264.7 cells were used for inhibitory effects of cytokine production in vitro. C57BL/6N mice were administered intranasally with LPS (10μg/per mouse) to induce ALI. H&E staining was used to evaluate histological changes in the lung.

RESULTS

Treatment with P. tomentosa stem bark extract (PTBE) suppressed the production of IL-6 and TNF-α in LPS-stimulated RAW 264.7 macrophages, and the recruitment of neutrophils and macrophages in the BALF of mice with LPS-induced ALI. PTBE also decreased the levels of reactive oxygen species (ROS) and pro-inflammatory cytokines in the BALF. PTBE reduced the levels of nitric oxide (NO) in the serum and of inducible nitric oxide synthase (iNOS) in the lung of ALI mice. PTBE also attenuated the infiltration of inflammatory cells and the expression of monocyte chemoattractant protein-1 (MCP-1) in the lung. In addition, PTBE suppressed the activation of NF-κB and the reduced expression of superoxide dismutase 3 (SOD3) in the lung.

CONCLUSION

The results suggest that PTBE has a protective effect on LPS-induced ALI.

MicroRNAs as biomarkers of acute lung injury

Acute respiratory distress syndrome (ARDS) is a common and complex inflammatory lung diseases affecting critically ill patients requiring mechanical ventilation. MicroRNAs (miRNAs), a novel pathway of non-coding RNA molecules that regulate gene expression at the post-transcriptional level, have emerged as a novel class of gene expression, and can play important roles in inflammation or apoptosis, which are common manifestations of ARDS and diffuse alveolar damage (DAD). In the present review, we discuss the role of miRNAs as biomarkers of ARDS and DAD, and their potential use as therapeutic targets for this condition.

Macrophage polarization and allergic asthma

Allergic asthma is associated with airway inflammation and airway hyperresponsiveness. Macrophage polarization has been shown to have a profound impact on asthma pathogenesis. On exposure to local microenvironments, recruited macrophages can be polarized into either classically activated (or M1) or alternatively activated (or M2) phenotypes. Macrophage polarization has been heavily associated with development of asthma. The process of regulation of macrophage polarization involves an intricate interplay between various cytokines, chemokines, transcriptional factors, and immune-regulatory cells. Different signals from the microenvironment are controlled by different receptors on the macrophages to initiate various macrophage polarization pathways. Most importantly, there is an increased attention on the epigenetic changes (eg, microRNAs, DNA methylation, and histone modification) that impact macrophage functional responses and M1/M2 polarization through modulating cellular signaling and signature gene expression. Thus, modulation of macrophage phenotypes through molecular intervention by targeting some of those potential macrophage regulators may have therapeutic potential in the treatment of allergic asthma and other allergic diseases. In this review, we will discuss the origin of macrophages, characterization of macrophages, macrophage polarization in asthma, and the underlying mechanisms regarding allergen-induced macrophage polarization with emphasis on the regulation of epigenetics, which will provide new insights into the therapeutic strategy for asthma.

Phorbol ester (PMA)-treated U937 cells cultured on type I collagen-coated dish express a lower production of pro-inflammatory cytokines through lowered ROS levels in parallel with cell aggregate formation

The present study is aimed to investigate the effect of collagen I on U937 cells, human monocyte-like histiocytic lymphoma cell line. Differentiation of U937 cells was induced by phorbol ester (PMA) treatment. The cells were cultured on the collagen I-coated plate. PMA-stimulated U937 cells formed multicellular aggregates on collagen I-coated surface, whereas PMA-unstimulated cells kept themselves away off each other. Moreover, the levels of reactive oxygen species (ROS) and productions of pro-inflammatory cytokines such as IL-1β, TNFα and PGE2, pro-inflammatory mediator, were down-regulated in differentiated U937 cells cultured on collagen I-coated dishes. However, collagen I did not influence the capacity of E. coli phagocytosis. Cell aggregation as well as the down-regulation of IL-1β, TNFα and PGE2 caused by the culture on collagen I-coated surface were suppressed by ROS donor, tert-butylhydroperoxide (tBHP). The sizes of cell aggregates became bigger in differentiated U937 cells by treatment with ROS scavengers such as N-acetylcysteine (NAC), superoxide dismutase (SOD), catalase (CAT) and glutathione (GSH). In conclusion, collagen I-coated culture induces the differentiated U937 cells to form cell aggregates and decreases the production of pro-inflammatory cytokines through down-regulating ROS generation.

ENaCs as Both Effectors and Regulators of MiRNAs in Lung Epithelial Development and Regeneration

Epithelial sodium channels (ENaC) play an important role in re-absorbing excessive luminal fluid by building up an osmotic Na+ gradient across the tight epithelium in the airway, the lung, the kidney, and the colon. The ENaC is a major pathway for retention of salt in kidney too. MicroRNAs (miRs), a group of non-coding RNAs that regulate gene expression at the post-transcriptional level, have emerged as a novel class of regulators for ENaC. Given the ENaC pathway is crucial for maintaining fluid homeostasis in the lung and the kidney and other cavities, we summarized the cross-talk between ENaC and miRs and recapitulated the underlying regulatory factors, including aldosterone, transforming growth factor-β1, and vascular endothelial growth factor-A in the lung and other epithelial tissues/organs. We have compared the profiling of miRs between normal and injured mice and human lungs, which showed a significant alteration in numerous miRs in mouse models of LPS and ventilator induced ARDS. In addition, we reiterated the potential regulation of the ENaC by miRs in stem/ progenitor cell-based re-epithelialization, and identified a promising pharmaceutic target of ENaC for removing edema fluid in ARDS by mesenchymal stem cells-released paracrine. In conclusion, it seems that the interactions between miRs and scnn1s/ENaCs are critical for lung development, epithelial cell turnover in adult lungs, and re-epithelialization for repair.

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.