Epigenetic modifiers reduce inflammation and modulate macrophage phenotype during endotoxemia-induced acute lung injury

Host antibacterial defense of 6-10 Gy γ-irradiated mice subjected to lentiviral vector-based Gas5 gene therapy

Gut bacteria-associated sepsis is a serious concern in patients with gastrointestinal acute radiation syndrome (GIARS). In our previous studies, all mice exposed to 8 Gy of whole body γ-irradiation (8 Gy GIARS-mice) died by sepsis stemming from bacterial translocation. M1Mϕ located in the bacterial translocation site (i.e., the mesenteric lymph nodes, MLNs) have been characterized as major antibacterial effector cells. However, M2bMϕ, inhibitor cells for M1Mϕ polarization, predominated in the MLNs of these mice. The reduced expression of long noncoding RNA Gas5 was associated with M2bMϕ polarization. In this study, we tried to reduce the mortality rate of 8 Gy GIARS-mice through Gas5 gene transduction using lentivirus (Gas5 lentivirus). After Gas5 lentivirus injection, Gas5 RNA was overexpressed in MLN-F4/80⁺ cells of 8 Gy GIARS-mice, and these cells were identified as non-M2bMϕ. All of the 8 Gy GIARS-mice injected with Gas5 lentivirus survived 30 days or more after irradiation, and bacterial translocation and subsequent sepsis were shown to be minimal in these mice. These results indicate that the antibacterial resistance of 8 Gy GIASR-mice can be restored through the modulation of M2bMϕ located in the bacterial translocation site by Gas5 transduction.

Epigenetic regulation of macrophage polarization in wound healing

The immune microenvironment plays a critical role in regulating skin wound healing. Macrophages, the main component of infiltrating inflammatory cells, play a pivotal role in shaping the immune microenvironment in the process of skin wound healing. Macrophages comprise the classic proinflammatory M1 subtype and anti-inflammatory M2 population. In the early inflammatory phase of skin wound closure, M1-like macrophages initiate and amplify the local inflammatory response to disinfect the injured tissue. In the late tissue-repairing phase, M2 macrophages are predominant in wound tissue and limit local inflammation to promote tissue repair. The biological function of macrophages is tightly linked with epigenomic organization. Transcription factors are essential for macrophage polarization. Epigenetic modification of transcription factors determines the heterogeneity of macrophages. In contrast, transcription factors also regulate the expression of epigenetic enzymes. Both transcription factors and epigenetic enzymes form a complex network that regulates the plasticity of macrophages. Here, we describe the latest knowledge concerning the potential epigenetic mechanisms that precisely regulate the biological function of macrophages and their effects on skin wound healing.

Sirtuins and Sepsis: Cross Talk between Redox and Epigenetic Pathways

Sepsis and septic shock are the leading causes of death among hospitalized patients in the US. The immune response in sepsis transitions from a pro-inflammatory and pro-oxidant hyper-inflammation to an anti-inflammatory and cytoprotective hypo-inflammatory phase. While 1/3rd sepsis-related deaths occur during hyper-, a vast majority of sepsis-mortality occurs during the hypo-inflammation. Hyper-inflammation is cytotoxic for the immune cells and cannot be sustained. As a compensatory mechanism, the immune cells transition from cytotoxic hyper-inflammation to a cytoprotective hypo-inflammation with anti-inflammatory/immunosuppressive phase. However, the hypo-inflammation is associated with an inability to clear invading pathogens, leaving the host susceptible to secondary infections. Thus, the maladaptive immune response leads to a marked departure from homeostasis during sepsis-phases. The transition from hyper- to hypo-inflammation occurs via epigenetic programming. Sirtuins, a highly conserved family of histone deacetylators and guardians of homeostasis, are integral to the epigenetic programming in sepsis. Through their anti-inflammatory and anti-oxidant properties, the sirtuins modulate the immune response in sepsis. We review the role of sirtuins in orchestrating the interplay between the oxidative stress and epigenetic programming during sepsis.

Ameliorative Effects of Oleuropein on Lipopolysaccharide-Induced Acute Lung Injury Model in Rats

Acute lung injury (ALI) is one of the most common causes of death in diseases with septic shock. Oleuropein, one of the important components of olive leaf, has antioxidant and anti-inflammatory effects. The objective of this study was to investigate the effects of oleuropein on lipopolysaccharide (LPS)-induced ALI in rats. Oleuropein was administered to rats at a dose of 200 mg/kg for 20 days and LPS was given through intratracheal administration to induce ALI. The study was terminated after 12 h. The results showed that in the group treated with oleuropein, inflammatory cytokines and oxidative stress decreased in serum, bronchoalveolar lavage fluid (BALF), and lung tissue, and there were significant improvements in the picture of acute interstitial pneumonia (AIP) caused by LPS in histopathological examination. Based on the findings of the present study, oleuropein showed protective effects against LPS-induced ALI.

Role of Macrophage Polarization in Acute Respiratory Distress Syndrome

Acute Respiratory Distress Syndrome is a familiar and destructive clinical condition characterized by progressive, swift and impaired pulmonary state. It leads to mortality if not managed in a timely manner. Recently the role of imbalanced macrophage polarization has been reported in ARDS. Macrophages are known for their heterogeneity and plasticity. Under different microenvironmental stimuli, they (M0) can switch between classically activated macrophage (M1) and alternatively activated (M2) states. This switch is regulated by several signaling pathways and epigenetic changes. In this review, the importance of macrophage M1 and M2 has been discussed in the arena of ARDS citing the phase-wise impact of macrophage polarization. This will provide a further understanding of the molecular mechanism involved in ARDS and will help in developing novel therapeutic targets. Various biomarkers that are currently used concerning this pathophysiological feature have also been summarized.

Preclinical and clinical progress for HDAC as a putative target for epigenetic remodeling and functionality of immune cells

Genetic changes are difficult to reverse; thus, epigenetic aberrations, including changes in DNA methylation, histone modifications, and noncoding RNAs, with potential reversibility, have attracted attention as pharmaceutical targets. The current paradigm is that histone deacetylases (HDACs) regulate gene expression via deacetylation of histone and nonhistone proteins or by forming corepressor complexes with transcription factors. The emergence of epigenetic tools related to HDACs can be used as diagnostic and therapeutic markers. HDAC inhibitors that block specific or a series of HDACs have proven to be a powerful therapeutic treatment for immune-related diseases. Here, we summarize the various roles of HDACs and HDAC inhibitors in the development and function of innate and adaptive immune cells and their implications for various diseases and therapies.

Transforming Growth Factor-β1 Promotes M1 Alveolar Macrophage Polarization in Acute Lung Injury by Up-Regulating DNMT1 to Mediate the microRNA-124/PELI1/IRF5 Axis

Objective

Macrophages function as key orchestrators in the pathogenesis of acute lung injury (ALI). The current study sets out to investigate the molecular mechanism of transforming growth factor-β (TGFβ1) in the regulation of M1 alveolar macrophage polarization in ALI by modulating DNA methyltransferase 1 (DNMT1), along with the microRNA (miR)-124/Pellino 1 (PELI1)/interferon regulatory factor 5 (IRF5) axis.

Methods

First, ALI mouse models were established, and the proportion of M1 and M2 macrophages in mouse lung tissues was detected using flow cytometry. The targeting relationship between miR-124 and PELI1 was verified with the help of a dual luciferase gene reporter assay. Following TGFβ1 knockdown, RT-qPCR and Western blot assay were performed to analyze the expression patterns of TGFβ1, DNMT1, miR-124, and PELI1 and M1/M2 polarization markers in the lung tissues of ALI mice. Immunofluorescence was further employed to detect nuclear translocation of IRF5 in macrophages.

Results

The polarization of M1 macrophages was found to be positively correlated with the severity of lung injury. TGFβ1, DNMT1, PELI1 were highly expressed, while miR-124 was down-regulated in ALI mice, and IRF5 was primarily distributed in the nucleus. TGFβ1 promoted the polarization of M1 alveolar macrophages by up-regulating DNMT1. Furthermore, DNMT1 down-regulated the expression of miR-124, which led to enhancement of M1 alveolar macrophage polarization. Meanwhile, over-expression of miR-124 inhibited the nuclear translocation of IRF5 and suppressed M1 alveolar macrophage polarization. On the other hand, over-expression of PELI1 reversed the above trends.

Conclusion

Collectively, our findings indicated that TGFβ1 can promote the expression of DNMT1, which down-regulates miR-124 to activate PELI1 and nuclear translocation of IRF5, thereby aggravating ALI in mice.

Inhibition of EZH2 prevents acute respiratory distress syndrome (ARDS)-associated pulmonary fibrosis by regulating the macrophage polarization phenotype

Background

We recently reported histone methyltransferase enhancer of zeste homolog 2 (EZH2) as a key epigenetic regulator that contributes to the dysfunction of innate immune responses to sepsis and subsequent lung injury by mediating the imbalance of macrophage polarization. However, the role of EZH2 in acute respiratory distress syndrome (ARDS)-associated fibrosis remains poorly understood.

Methods

In this study, we investigated the role and mechanisms of EZH2 in pulmonary fibrosis in a murine model of LPS-induced ARDS and in ex-vivo cultured alveolar macrophages (MH-S) and mouse lung epithelial cell line (MLE-12) by using 3-deazaneplanocin A (3-DZNeP) and EZH2 the small interfering (si) RNA.

Results

We found that treatment with 3-DZNeP significantly ameliorated the LPS-induced direct lung injury and fibroproliferation by blocking EMT through TGF-β1/Smad signaling pathway and regulating shift of macrophage phenotypes. In the ex-vivo polarized alveolar macrophages cells, treatment with EZH2 siRNA or 3-DZNeP suppressed the M1 while promoted the M2 macrophage differentiation through modulating the STAT/SOCS signaling pathway and activating PPAR-γ. Moreover, we identified that blockade of EZH2 with 3-DZNeP suppressed the epithelial to mesenchymal transition (EMT) in co-cultured bronchoalveolar lavage fluid (BALF) and mouse lung epithelial cell line through down-regulation of TGF-β1, TGF-βR1, Smad2 while up-regulation of Smad7 expression.

Conclusions

These results indicate that EZH2 is involved in the pathological process of ARDS-associated pulmonary fibrosis. Targeting EZH2 may be a potential therapeutic strategy to prevent and treat pulmonary fibrosis post ARDS.

Histone Deacetylase 7 Inhibition in a Murine Model of Gram-Negative Pneumonia-Induced Acute Lung Injury

BACKGROUND

Pulmonary infections remain the most common cause of Acute Respiratory Distress Syndrome (ARDS), a pulmonary inflammatory disease with high mortality, for which no targeted therapy currently exists. We have previously demonstrated an ameliorated syndrome with early, broad spectrum Histone Deacetylase (HDAC) inhibition in a murine model of gram-negative pneumonia-induced Acute Lung Injury (ALI), the underlying pulmonary pathologic phenotype leading to ARDS. With the current project we aim to determine if selective inhibition of a specific HDAC leads to a similar pro-survival phenotype, potentially pointing to a future therapeutic target.

METHODS

C57Bl/6 mice underwent endotracheal instillation of 30×10Escherichia coli (strain 19138) versus saline (n = 24). Half the infected mice were administered Trichostatin A (TSA) 30 min later. All animals were sacrificed 6 h later for tissue sampling and HDAC quantification, while another set of animals (n = 24) was followed to determine survival. Experiments were repeated with selective siRNA inhibition of the HDAC demonstrating the greatest inhibition versus scrambled siRNA (n = 24).

RESULTS

TSA significantly ameliorated the inflammatory phenotype and improved survival in infected-ALI mice, and HDAC7 was the HDAC with the greatest transcription and protein translation suppression. Similar results were obtained with selective HDAC7 siRNA inhibition compared with scrambled siRNA.

CONCLUSION

HDAC7 appears to play a key role in the inflammatory response that leads to ALI after gram-negative pneumonia in mice.

Human umbilical cord mesenchymal stem cells in type 2 diabetes mellitus: the emerging therapeutic approach

The umbilical cord has been proved to be an easy-access, reliable, and useful source of mesenchymal stem cells (MSC) for clinical applications due to its primitive, immunomodulatory, non-immunogenic, secretory and paracrine, migratory, proliferative, and multipotent properties. This set of characteristics has recently attracted great research interest in the fields of nanotechnology and regenerative medicine and cellular therapy. Accumulating evidence supports a pronounced therapeutic potential of MSC in many different pathologies, from hematology to immunology, wound-healing, tissue regeneration, and oncology. Diabetes mellitus, branded the epidemic of the century, is considered a chronic metabolic disorder, representing a major burden for health system sustainability and an important public health challenge to modern societies. The available treatments for type 2 diabetes mellitus (T2DM) still rely mainly on combinations of oral antidiabetic agents with lifestyle and nutritional adjustments. Despite the continuous development of novel and better hypoglycemic drugs, their efficacy is limited in the installment and progression of silent T2DM complications. T2DM comorbidities and mortality rates still make it a serious, common, costly, and long-term manageable disease. Recently, experimental models, preclinical observations, and clinical studies have provided some insights and preliminary promising results using umbilical cord MSCs to treat and manage diabetes. This review focuses on the latest research and applications of human-derived umbilical cord MSC in the treatment and management of T2DM, exploring and systematizing the key effects of both umbilical cord MSC and its factor-rich secretome accordingly with the major complications associated to T2DM.

Decitabine Promotes Modulation in Phenotype and Function of Monocytes and Macrophages That Drive Immune Response Regulation

Decitabine is an approved hypomethylating agent used for treating hematological malignancies. Although decitabine targets altered cells, epidrugs can trigger immunomodulatory effects, reinforcing the hypothesis of immunoregulation in treated patients. We therefore aimed to evaluate the impact of decitabine treatment on the phenotype and functions of monocytes and macrophages, which are pivotal cells of the innate immunity system. In vitro decitabine administration increased bacterial phagocytosis and IL-8 release, but impaired microbicidal activity of monocytes. In addition, during monocyte-to-macrophage differentiation, treatment promoted the M2-like profile, with increased expression of CD206 and ALOX15. Macrophages also demonstrated reduced infection control when exposed to Mycobacterium tuberculosis in vitro. However, cytokine production remained unchanged, indicating an atypical M2 macrophage. Furthermore, when macrophages were cocultured with lymphocytes, decitabine induced a reduction in the release of inflammatory cytokines such as IL-1β, TNF-α, and IFN-γ, maintaining IL-10 production, suggesting that decitabine could potentialize M2 polarization and might be considered as a therapeutic against the exacerbated immune response.

A feasibility study of combined epigenetic and vaccine therapy in advanced colorectal cancer with pharmacodynamic endpoint

Epigenetic therapies may modulate the tumor microenvironment. We evaluated the safety and optimal sequence of combination DNA methyltransferase inhibitor guadecitabine with a granulocyte macrophage-colony-stimulating-factor (GM-CSF) secreting colon cancer (CRC) vaccine (GVAX) using a primary endpoint of change in CD45RO + T cells. 18 patients with advanced CRC enrolled, 11 underwent paired biopsies and were evaluable for the primary endpoint. No significant increase in CD45RO + cells was noted. Grade 3-4 toxicities were expected and manageable. Guadecitabine + GVAX was tolerable but demonstrated no significant immunologic activity in CRC. We report a novel trial design to efficiently evaluate investigational therapies with a primary pharmacodynamic endpoint.Trial registry Clinicaltrials.gov: NCT01966289. Registered 21 October, 2013.

Macrophage Plasticity in Reproduction and Environmental Influences on Their Function

Macrophages are key components of the innate immune system and exhibit extensive plasticity and heterogeneity. They play a significant role in the non-pregnant cycling uterus and throughout gestation they contribute to various processes underpinning reproductive success including implantation, placentation and parturition. Macrophages are also present in breast milk and impart immunomodulatory benefits to the infant. For a healthy pregnancy, the maternal immune system must adapt to prevent fetal rejection and support development of the semi-allogenic fetus without compromising host defense. These functions are dependent on macrophage polarization which is governed by the local tissue microenvironmental milieu. Disruption of this microenvironment, possibly by environmental factors of infectious and non-infectious origin, can affect macrophage phenotype and function and is linked to adverse obstetric outcomes, e.g. spontaneous miscarriage and preterm birth. Determining environmental influences on cellular and molecular mechanisms that control macrophage polarization at the maternal-fetal interface and the role of this in pregnancy complications could support approaches to alleviating adverse pregnancy outcomes.

Immune responses to azacytidine in animal models of inflammatory disorders: a systematic review

Inflammatory disorders like diabetes, systemic lupus erythematodes, inflammatory lung diseases, rheumatoid arthritis and multiple sclerosis, but also rejection of transplanted organs and GvHD, form a major burden of disease. Current classes of immune suppressive drugs to treat these disorders are never curative and side effects are common. Therefore there is a need for new drugs with improved and more targeted modes of action. Potential candidates are the DNA methyl transferase inhibitor 5-azacytidine (Aza) and its derivative 5-aza 2′deoxycitidine (DAC). Aza and DAC have been tested in several pre-clinical in vivo studies. In order to obtain an overview of disorders for which Aza and/or DAC can be a potential treatment, and to find out where information is lacking, we systematically reviewed pre-clinical animal studies assessing Aza or DAC as a potential therapy for distinct inflammatory disorders. Also, study quality and risk of bias was systematically assessed. In the 35 identified studies, we show that both Aza and DAC do not only seem to be able to alleviate a number of inflammatory disorders, but also prevent solid organ rejection and GvHD in in vivo pre-clinical animal models. Aza/DAC are known to upregulate FOXP3, a master transcription factor for Treg, in vitro. Seventeen studies described the effect on Treg, of which 16 studies showed an increase in Treg. Increasing Treg therefore seems to be a common mechanism in preventing inflammatory disorders by Aza/DAC. We also found, however, that many essential methodological details were poorly reported leading to an unclear risk of bias. Therefore, reported effects might be an overestimation of the true effect.

Molecular Mechanisms of Vascular Damage During Lung Injury

A variety of pulmonary and systemic insults promote an inflammatory response causing increased vascular permeability, leading to the development of acute lung injury (ALI), a condition necessitating hospitalization and intensive care, or the more severe acute respiratory distress syndrome (ARDS), a disease with a high mortality rate. Further, COVID-19 pandemic-associated ARDS is now a major cause of mortality worldwide. The pathogenesis of ALI is explained by injury to both the vascular endothelium and the alveolar epithelium. The disruption of the lung endothelial and epithelial barriers occurs in response to both systemic and local production of pro-inflammatory cytokines. Studies that evaluate the association of genetic polymorphisms with disease risk did not yield many potential therapeutic targets to treat and revert lung injury. This failure is probably due in part to the phenotypic complexity of ALI/ARDS, and genetic predisposition may be obscured by the multiple environmental and behavioral risk factors. In the last decade, new research has uncovered novel epigenetic mechanisms that control ALI/ARDS pathogenesis, including histone modifications and DNA methylation. Enzyme inhibitors such as DNMTi and HDACi may offer new alternative strategies to prevent or reverse the vascular damage that occurs during lung injury. This review will focus on the latest findings on the molecular mechanisms of vascular damage in ALI/ARDS, the genetic factors that might contribute to the susceptibility for developing this disease, and the epigenetic changes observed in humans, as well as in experimental models of ALI/ADRS.

Sophoricoside attenuates lipopolysaccharide-induced acute lung injury by activating the AMPK/Nrf2 signaling axis

Sophoricoside (SOP), an isoflavone glycoside isolated from seed of Sophora japonica L., has been reported to have various pharmacological activities, including anti-cancer, anti-allergy and anti-inflammation. However, the effect of SOP on lipopolysaccharides (LPS)-acute lung injury (ALI) is completely unclear. Here, we found that SOP pretreatment significantly ameliorated LPS-induced pathological damage, tissue permeability, neutrophil infiltration and the production of pro-inflammatory cytokines (TNF-α, IL-1β and IL-6) in a murine model of ALI. Besides, SOP reduced the production of pro-inflammatory mediators such as iNOS, NO and inflammatory cytokines including TNF-α, IL-1β and IL-6 in LPS-stimulated RAW264.7 cells and bone marrow derived macrophages. Interestingly, treatment with SOP exhibited no effect on the activation of NF-κB and MAPKs in macrophages but prominently accelerated the expression and nuclear translocation of Nrf2. By using ML385, a specific Nrf2 inhibitor, we found that inhibition of Nrf2 abolished the inhibitory effect of SOP on LPS-induced iNOS expression, NO production as well as pro-inflammatory cytokine generation. SOP also activated AMPK, an upstream protein of Nrf2, under LPS stimuli. Furthermore, we demonstrated that the accelerated expression of Nrf2 induced by SOP was reversed by interference with the AMPK inhibitor Compound C. Taken together, our results suggested that SOP attenuated LPS-induced ALI in AMPK/Nrf2 dependent manner and indicated that SOP might be a potential therapeutic candidate for treating ALI/ARDS.

Bronchial Epithelial Tet2 Maintains Epithelial Integrity during Acute Pseudomonas aeruginosa Pneumonia

Respiratory epithelial cells are important for pulmonary innate immune responses during Pseudomonas aeruginosa infection. Tet methylcytosine dioxygenase 2 (Tet2) has been implicated in the regulation of host defense by myeloid and lymphoid cells, but whether Tet2 also contributes to epithelial responses during pneumonia is unknown. The aim of this study was to investigate the role of bronchial epithelial Tet2 in acute pneumonia caused by P. aeruginosa To this end, we crossed mice with Tet2 flanked by two Lox-P sites (Tet2^fl/fl mice) with mice expressing Cre recombinase under the bronchial epithelial cell-specific Cc10 promoter (Cc10^Cre mice) to generate bronchial epithelial cell-specific Tet2-deficient (Tet2^fl/fl Cc10^Cre ) mice. Six hours after infection with P. aeruginosa, Tet2^fl/fl Cc10^Cre and wild-type mice had similar bacterial loads in bronchoalveolar lavage fluid (BALF). At this time point, Tet2^fl/fl Cc10^Cre mice displayed reduced mRNA levels of the chemokines Cxcl1, Cxcl2, and Ccl20 in bronchial brushes. However, Cxcl1, Cxcl2, and Ccl20 protein levels and leukocyte recruitment in BALF were not different between groups. Tet2^fl/fl Cc10^Cre mice had increased protein levels in BALF after infection, indicating a disturbed epithelial barrier function, which was corroborated by reduced mRNA expression of tight junction protein 1 and occludin in bronchial brushes. Differences detected between Tet2^fl/fl Cc10^Cre and wild-type mice were no longer present at 24 h after infection. These results suggest that bronchial epithelial Tet2 contributes to maintaining epithelial integrity by enhancing intracellular connections between epithelial cells during the early phase of P. aeruginosa pneumonia.

Gene expression signatures identify paediatric patients with multiple organ dysfunction who require advanced life support in the intensive care unit

BACKGROUND

Multiple organ dysfunction syndrome (MODS) occurs in the setting of a variety of pathologies including infection and trauma. Some patients decompensate and require Veno-Arterial extra corporeal membrane oxygenation (ECMO) as a palliating manoeuvre for recovery of cardiopulmonary function. The molecular mechanisms driving progression from MODS to cardiopulmonary collapse remain incompletely understood, and no biomarkers have been defined to identify those MODS patients at highest risk for progression to requiring ECMO support.

METHODS

Whole blood RNA-seq profiling was performed for 23 MODS patients at three time points during their ICU stay (at diagnosis of MODS, 72 hours after, and 8 days later), as well as four healthy controls undergoing routine sedation. Of the 23 MODS patients, six required ECMO support (ECMO patients). The predictive power of conventional demographic and clinical features was quantified for differentiating the MODS and ECMO patients. We then compared the performance of markers derived from transcriptomic profiling including [1] transcriptomically imputed leukocyte subtype distribution, [2] relevant published gene signatures and [3] a novel differential gene expression signature computed from our data set. The predictive power of our novel gene expression signature was then validated using independently published datasets.

FINDING

None of the five demographic characteristics and 14 clinical features, including The Paediatric Logistic Organ Dysfunction (PELOD) score, could predict deterioration of MODS to ECMO at baseline. From previously published sepsis signatures, only the signatures positively associated with patient's mortality could differentiate ECMO patients from MODS patients, when applied to our transcriptomic dataset (P-value ranges from 0.01 to 0.04, Student's test). Deconvolution of bulk RNA-Seq samples suggested that lower neutrophil counts were associated with increased risk of progression from MODS to ECMO (P-value = 0.03, logistic regression, OR=2.82 [95% CI 0.63 - 12.45]). A total of 30 genes were differentially expressed between ECMO and MODS patients at baseline (log2 fold change ≥ 1 or ≤ -1 with false discovery rate ≤ 0.01). These genes are involved in protein maintenance and epigenetic-related processes. Further univariate analysis of these 30 genes suggested a signature of seven DE genes associated with ECMO (OR > 3.0, P-value ≤ 0.05, logistic regression). Notably, this contains a set of histone marker genes, including H1F0, HIST2H3C, HIST1H2AI, HIST1H4, HIST1H2BL and HIST1H1B, that were highly expressed in ECMO. A risk score derived from expression of these genes differentiated ECMO and MODS patients in our dataset (AUC = 0.91, 95% CI 0.79-1.00, P-value = 7e-04, logistic regression) as well as validation dataset (AUC= 0.73, 95% CI 0.53-0.93, P-value = 2e-02, logistic regression).

INTERPRETATION

This study demonstrates that transcriptomic features can serve as indicators of severity that could be superior to traditional methods of ascertaining acuity in MODS patients. Analysis of expression of signatures identified in this study could help clinicians in the diagnosis and prognostication of MODS patients after arrival to the Hospital.

Macrophages in Organ Transplantation

Current immunosuppressive therapy has led to excellent short-term survival rates in organ transplantation. However, long-term graft survival rates are suboptimal, and a vast number of allografts are gradually lost in the clinic. An increasing number of animal and clinical studies have demonstrated that monocytes and macrophages play a pivotal role in graft rejection, as these mononuclear phagocytic cells recognize alloantigens and trigger an inflammatory cascade that activate the adaptive immune response. Moreover, recent studies suggest that monocytes acquire a feature of memory recall response that is associated with a potent immune response. This form of memory is called “trained immunity,” and it is retained by mechanisms of epigenetic and metabolic changes in innate immune cells after exposure to particular ligands, which have a direct impact in allograft rejection. In this review article, we highlight the role of monocytes and macrophages in organ transplantation and summarize therapeutic approaches to promote tolerance through manipulation of monocytes and macrophages. These strategies may open new therapeutic opportunities to increase long-term transplant survival rates in the clinic.

The surviving sepsis campaign: basic/translational science research priorities

Objectives

Expound upon priorities for basic/translational science identified in a recent paper by a group of experts assigned by the Society of Critical Care Medicine and the European Society of Intensive Care Medicine.

Data sources

Original paper, search of the literature.

Study selection

This study is selected by several members of the original task force with specific expertise in basic/translational science. Data extraction and data synthesis are not available.

Conclusions

In the first of a series of follow-up reports to the original paper, several members of the original task force with specific expertise provided a more in-depth analysis of the five identified priorities directly related to basic/translational science. This analysis expounds on what is known about the question and what was identified as priorities for ongoing research. It is hoped that this analysis will aid the development of future research initiatives.

DNA methyltransferase inhibitor alleviates bleomycin-induced pulmonary inflammation

Acute lung injury (ALI) is a severe disease characterized by several inflammatory responses in the lung with high mortality. We applied a mouse model of the pulmonary inflammation induced by the intratracheal instillation of bleomycin which is widely used to induce ALI and fibrosis in animal models. We hypothesized that DNA methyltransferase inhibitor, 5-azacytidine (5-Aza), with its anti-inflammatory benefits, might attenuate bleomycin-induced ALI through the alleviation of inflammation in the lung. We quantified white blood cells with cell blood count (CBC) test, lung inflammation by analyzing cells in the collected bronchoalveolar lavage fluid (BALF) and histological analysis of the lung tissues, and gene expression levels by real-time PCR. Intratracheal administration of bleomycin in mice induced pulmonary inflammation, characterized by increased neutrophil infiltration and inflammatory cytokine expression in the lungs. Mice treated with 5-Aza showed a significant reduction of lung neutrophilia, together with lower expressions of CXCL2 and MCP-1. Furthermore, 5-Aza treatment decreased the expression of proinflammatory cytokines in the lung tissue. Collectively, our data show that DNA methyltransferase inhibitor can alleviate the lung inflammation of bleomycin-induced ALI, indicating an alternative treatment option for the inflammation-triggered lung injury.

Low-Dose Decitabine Assists Human Umbilical Cord-Derived Mesenchymal Stem Cells in Protecting β Cells via the Modulation of the Macrophage Phenotype in Type 2 Diabetic Mice

Background

Progressive β-cell dysfunction, a major characteristic of type 2 diabetes (T2D), is closely related to the infiltration of inflammatory macrophages within islets. Mesenchymal stem cells (MSCs) have been identified to alleviate β-cell dysfunction by modulating macrophage phenotype in T2D, but the restoration of β-cells by a single MSC infusion is relatively transient. Decitabine (DAC) has been reported to polarize macrophages towards the anti-inflammatory phenotype at low doses. We therefore investigated whether low-dose decitabine could enhance the antidiabetic effect of MSCs and further promote the restoration of β-cell function.

Methods

We induced a T2D mice model by high-fat diets and streptozotocin (STZ) injection. Mice were divided into five groups: the normal group, the T2D group, the DAC group, the MSC group, and the MSC plus DAC group (MD group). We examined the blood glucose and serum insulin levels of mice 1, 2, and 4 weeks after MSC and/or DAC treatment. Dynamic changes in islets and the phenotype of intraislet macrophages were detected via immunofluorescence. In vitro, we explored the effect of MSCs and DAC on macrophage polarization.

Results

The blood glucose and serum insulin levels revealed that DAC prolonged the antidiabetic effect of MSCs to 4 weeks in T2D mice. Immunofluorescence staining demonstrated more sustainable morphological and structural amelioration in islets of the MD group than in the MSC group. Interestingly, further analysis showed more alternatively activated macrophages (M2, anti-inflammatory) and fewer classically activated macrophages (M1, proinflammatory) in islets of the MD group 4 weeks after treatment. An in vitro study demonstrated that DAC together with MSCs further polarized macrophages from the M1 to M2 phenotype via the PI3K/AKT pathway.

Conclusion

These data unveiled that DAC prolonged the antidiabetic effect of MSCs and promoted sustainable β-cell restoration, possibly by modulating the macrophage phenotype. Our results offer a preferable therapeutic strategy for T2D.

Damage and Phenotype Change in PC12 Cells Induced by Lipopolysaccharide Can Be Inhibited by Antioxidants Through Reduced Cytoskeleton Protein Synthesis

The present study investigated changes in cellular phenotype and oxidative stress during the inflammatory response in PC12 cells stimulated by lipopolysaccharide (LPS) and assessed the effects of minocycline, astragalus (AST), and baicalin on inflammation. PC12 cells were exposed to LPS with or without minocycline, AST, or baicalin. Cell viability was measured by a thiazolyl blue tetrazolium bromide (MTT) assay. Contrast and laser confocal microscopy were used to analyze changes in cellular phenotype and cytoskeleton synthesis. Western blotting tested the expression of α7nAChR and vimentin. Inhibitory ratio of superoxide dismutase (SOD) activity and leakage of lactate dehydrogenase (LDH) were detected to evaluate cellular oxidative stress. Results showed that LPS could attenuate PC12 cell viability in a time- and dose-dependent manner, which could be rescued by minocycline. In addition, minocycline could reverse PC12 cell phenotypic change and the synthesis of the mesenchymal cytoskeleton protein vimentin, both induced by LPS. During LPS-initiated inflammation, α7nAChR and vimentin expression were obviously inhibited by minocycline, AST, or baicalin. The inhibitory rate of SOD activity and LDH leakage in PC12 cells were increased by LPS and attenuated significantly when exposed to minocycline, AST, or baicalin. These findings suggest phenotype change, altered cytoskeleton protein synthesis, and oxidative stress are all involved in the inflammatory response in PC12 cells during which α7 nicotinic acetylcholine receptor (α7nAChR) is induced by LPS stimulation. Minocycline, AST, and baicalin have a protective effect against PC12 cell injury, acting as antioxidants and inhibitors of mesenchymal proteins.

Identification of amitriptyline HCl, flavin adenine dinucleotide, azacitidine and calcitriol as repurposing drugs for influenza A H5N1 virus-induced lung injury

Infection with avian influenza A H5N1 virus results in acute lung injury (ALI) and has a high mortality rate (52.79%) because there are limited therapies available for treatment. Drug repositioning is an economical approach to drug discovery. We developed a method for drug repositioning based on high-throughput RNA sequencing and identified several drugs as potential treatments for avian influenza A H5N1 virus. Using high-throughput RNA sequencing, we identified a total of 1,233 genes differentially expressed in A549 cells upon H5N1 virus infection. Among these candidate genes, 79 drug targets (corresponding to 59 approved drugs) overlapped with the DrugBank target database. Twenty-two of the 41 commercially available small-molecule drugs reduced H5N1-mediated cell death in cultured A549 cells, and fifteen drugs that protected A549 cells when administered both pre- and post-infection were tested in an H5N1-infection mouse model. The results showed significant alleviation of acute lung injury by amitriptyline HCl (an antidepressant drug), flavin adenine dinucleotide (FAD; an ophthalmic agent for vitamin B2 deficiency), azacitidine (an anti-neoplastic drug) and calcitriol (an active form of vitamin D). All four agents significantly reduced the infiltrating cell count and decreased the lung injury score in H5N1 virus-infected mice based on lung histopathology, significantly improved mouse lung edema by reducing the wet-to-dry weight ratio of lung tissue and significantly improved the survival of H5N1 virus-infected mice. This study not only identifies novel potential therapies for influenza H5N1 virus-induced lung injury but also provides a highly effective and economical screening method for repurposing drugs that may be generalizable for the prevention and therapy of other diseases.

Highly pathogenic avian influenza (HPAI) A virus H5N1 causes acute lung injury (ALI) and acute respiratory distress syndrome (ARDS), with mortality as high as 52.79%. No vaccine for HPAI virus is available, and current treatments for influenza A H5N1 virus-induced ALI have limitations. Drug repurposing may be an effective approach for developing novel therapeutic strategies. In this study, we identified 4 drugs, the antidepressant amitriptyline HCl, the ophthalmic flavin adenine dinucleotide, the anti-neoplastic azacitidine and the vitamin D-deficiency treatment calcitriol, as being highly effective for the treatment of H5N1 virus-induced ALI using a transcriptomic-based high-throughput repurposing drug screening. These approved drugs might constitute novel potential remedies for treating influenza H5N1 virus infection, and this screening method may be generalizable for drug repositioning to identify new indications for other diseases.

Glycine Attenuates Lipopolysaccharide-Induced Acute Lung Injury by Regulating NLRP3 Inflammasome and NRF2 Signaling

Glycine supplementation has been reported to alleviate lipopolysaccharide (LPS)-induced lung injury in mice. However, the underlying mechanisms responsible for this beneficial effect remain unknown. In the present study, male C57BL/6 mice were treated with aerosolized glycine (1000 mg in 5 mL of 0.9% saline) or vehicle (0.9% saline) once daily for 7 continuous days, and then were exposed to aerosolized LPS (5 mg in 5 mL of 0.9% saline) for 30 min to induce lung injury. Sera and lung tissues were collected 24 h post LPS challenge. Results showed that glycine pretreatment attenuated LPS-induced decreases of mucin at both protein and mRNA levels, reduced LPS-triggered upregulation of pro-inflammatory cytokines, such as tumor necrosis factor-α (TNF-α), interferons, granulocyte-macrophage colony-stimulating factor (GM-CSF), and interleukins. Further study showed that glycine-reduced LPS challenge resulted in the upregulation of nuclear factor κB (NF-κB), nucleotide binding domain (NOD)-like receptor protein 3 (NLRP3) inflammasome. In addition, LPS exposure led to the downregulation of NRF2 and downstream targets, which were significantly improved by glycine administration in the lung tissues. Our findings indicated that glycine pretreatment prevented LPS-induced lung injury by regulating both NLRP3 inflammasome and NRF2 signaling.

Epigenetic Profiling in Severe Sepsis: A Pilot Study of DNA Methylation Profiles in Critical Illness

OBJECTIVES

Epigenetic alterations are an important regulator of gene expression in health and disease; however, epigenetic data in sepsis are lacking. To demonstrate proof of concept and estimate effect size, we performed the first epigenome-wide methylation analysis of whole blood DNA samples from a cohort of septic and nonseptic critically ill patients.

DESIGN

A nested case-control study using genomic DNA isolated from whole blood from septic (n = 66) and nonseptic (n = 68) critically ill patients on "Day 1" of ICU admission. Methylation patterns were identified using Illumina 450K arrays with percent methylation expressed as β values. After quality control, 134 participants and 414,818 autosomal cytosine-phosphate-guanine sites were used for epigenome-wide methylation analyses.

SETTING

Tertiary care hospitals.

SUBJECTS

Critically ill septic and nonseptic patients.

INTERVENTIONS

Observational study.

MEASUREMENTS AND MAIN RESULTS

A total of 668 differentially methylated regions corresponding to 443 genes were identified. Known sepsis-associated genes included complement component 3; angiopoietin 2; myeloperoxidase; lactoperoxidase; major histocompatibility complex, class I, A; major histocompatibility complex, class II, isotype DR β I; major histocompatibility complex, class I, C; and major histocompatibility complex, class II, isotype DQ β I. When compared with whole blood gene expression data from seven external datasets containing septic and nonseptic patients, 81% of the differentially methylated region-associated genes were differentially expressed in one or more datasets and 31% in three or more datasets. Functional analysis showed enrichment for antigen processing and presentation, methyltransferase activity, cell adhesion, and cell junctions. Analysis by weighted gene coexpression network analysis revealed DNA comethylation modules that were associated with clinical traits including severity of illness, need for vasopressors, and length of stay.

CONCLUSIONS

DNA methylation marks may provide important causal and potentially biomarker information in critically ill patients with sepsis.

Trichostatin A modulates the macrophage phenotype by enhancing autophagy to reduce inflammation during polymicrobial sepsis

Sepsis is a syndrome of life-threatening organ dysfunction caused by dysregulated host responses to infection. Macrophage polarization is a key process involved in the pathogenesis of sepsis. Recent evidence has demonstrated that autophagy participates in the regulation of macrophage polarization in different phases of inflammation. Here, we investigated whether trichostatin A (TSA), a histone deacetylase (HDAC) inhibitor, promotes the macrophage M2 phenotype by enhancing autophagy to counteract excessive inflammation in a cecal ligation and puncture (CLP) mouse model. TSA stimulation increased the proportions of M2 marker (CD206, CD124 and CD23)-labeled RAW264.7 macrophages. Furthermore, with increasing TSA doses, autophagy was enhanced gradually. Interestingly, the autophagy activator rapamycin (Rap), also known as an mTOR inhibitor, unexpectedly decreased the proportions of M2 marker-labeled macrophages. However, TSA treatment reversed the Rap-induced decreases in CD206-labeled macrophages. Next, we stimulated different groups of RAW264.7 cells with the autophagy inhibitors MHY1485 or 3-methyladenine (3-MA). Inhibition of autophagy at any stage in the process suppressed TSA-induced macrophage M2 polarization, but the effect was not associated with mTOR activity. In vivo, TSA administration promoted peritoneal macrophage M2 polarization, increased LC3 II expression, attenuated sepsis-induced organ (lung, liver and kidney) injury, and altered systemic inflammatory cytokine secretion. However, 3-MA abolished the protective effects of TSA in CLP mice and decreased the number of M2 peritoneal macrophages. Therefore, TSA promotes the macrophage M2 phenotype by enhancing autophagy to reduce systemic inflammation and ultimately improves the survival of mice with polymicrobial sepsis.

5-Azacytidine and trichostatin A enhance the osteogenic differentiation of bone marrow mesenchymal stem cells isolated from steroid-induced avascular necrosis of the femoral head in rabbit

Bone marrow mesenchymal stem cells (BMSCs) play an important role in the process of bone repair. The present study investigated the effect of 5-azacytidine (AZA) and trichostatin A (TSA) on BMSC behaviors in vitro. The role of WNT family member 5A (WNT5A)/WNT family member 5A (WNT7A)/beta-catenin signaling was also investigated. BMSCs were isolated from a steroid-induced avascular necrosis of the femoral head (SANFH) rabbit model. The third-generation of BMSCs was used after identification. The results revealed obvious degeneration and necrosis in the SANFH rabbit model. AZA, TSA and TSA + AZA increased BMSC proliferation in a time-dependent fashion. AZA, TSA and TSA + AZA induced the cell cycle release from the G0/G1 phase and inhibited apoptosis in BMSCs. AZA, TSA and TSA + AZA treatment significantly decreased caspase-3 and caspase-9 activities. The treatment obviously increased the activity and relative mRNA expression of alkaline phosphatase. The treatment also significantly up-regulated the proteins associated with osteogenic differentiation, including osteocalcin and runt-related transcription factor 2 (RUNX2), and Wnt/beta-catenin signal transduction pathway-related proteins beta-catenin, WNT5A and WNT7A. The relative levels of Dickkopf-related protein 1 (an inhibitor of the canonical Wnt pathway) decreased remarkably. Notably, TSA + AZA treatment exhibited a stronger adjustment ability than either single treatment. Collectively, the present studies suggest that AZA, TSA and TSA + AZA promote cell proliferation and osteogenic differentiation in BMSCs, and these effects are potentially achieved via upregulation of WNT5A/WNT7A/b-catenin signaling.

Decitabine assists umbilical cord-derived mesenchymal stem cells in improving glucose homeostasis by modulating macrophage polarization in type 2 diabetic mice

Background

Mesenchymal stem cells (MSCs) have emerged as a promising therapy for type 2 diabetes (T2D). Mechanistic researches demonstrate that the anti-diabetic effect of MSCs is partially mediated by eliciting macrophages into an anti-inflammatory phenotype thus alleviating insulin resistance. However, single MSC infusion is insufficient to ameliorate sustained hyperglycemia or normalize blood glucose levels. In this study, we used decitabine (DAC), which is involved in the regulation of macrophage polarization, to test whether MSCs combined with decitabine can prolong and enhance the anti-diabetic effect in T2D mice.

Methods

High-fat diet (HFD) and streptozocin (STZ) were given to induce T2D mouse model. Successfully induced T2D mice were randomly divided into four groups: T2D group, MSC group, DAC group, and MSC + DAC group. Blood glucose was monitored, and glucose tolerance and insulin sensitivity were evaluated during the entire analysis period. Epididymal fat was extracted for analysis of macrophage phenotype and inflammation in adipose tissue. In vitro, we examined the effect of MSC + DAC on macrophage polarization in bone marrow-derived macrophages (BMDMs) and explore the possible mechanism.

Results

MSC infusion effectively improved insulin sensitivity and glucose homeostasis in T2D mice within 1 week, whereas combination therapy of MSCs + DAC extended the anti-diabetic effects of MSCs from 1 to 4 weeks (the end of the observation). Correspondingly, more M2 macrophages in adipose tissue were observed in the combination therapy group over the entire study period. In vitro, compared with the MSC group, MSCs combined with decitabine more effectively polarized M1 macrophages to M2 macrophages. Further analysis showed that the effect of MSC + DAC on macrophage polarization was largely abrogated by the peroxisome proliferator-activated receptor gamma (PPARγ) antagonist GW9662.

Conclusions

Our data suggest that MSCs combined with decitabine can more effectively alleviate insulin resistance and prolong and enhance the anti-diabetic effect of MSCs in T2D mice in part by prompting M2 polarization in a PPARγ-dependent manner. Thus, decitabine may be an applicable addition to MSCs for diabetes therapy.

Graphic Abstract

UC-MSCs combined with decitabine activate the IL4R/STAT6/STAT3/PPARγ axis to further promote M2 macrophage polarization in adipose tissue, reduce inflammation, improve insulin sensitivity, and lead to better glucose metabolism and long-term hypoglycemic effects

Electronic supplementary material

The online version of this article (10.1186/s13287-019-1338-2) contains supplementary material, which is available to authorized users.

Histone deacetylase 6 regulates endothelial MyD88-dependent canonical TLR signaling, lung inflammation, and alveolar remodeling in the developing lung

Lung endothelial cell (EC) immune activation during bacterial sepsis contributes to acute lung injury and bronchopulmonary dysplasia in premature infants. The epigenetic regulators of sepsis-induced endothelial immune activation, lung inflammation, and alveolar remodeling remain unclear. Herein, we examined the role of the cytoplasmic histone deacetylase, HDAC6, in regulating EC Toll-like receptor 4 (TLR4) signaling and modulating sepsis-induced lung injury in a neonatal model of sterile sepsis. In human primary microvascular endothelial cells (HPMEC), lipopolysaccharide (LPS)-induced MAPK, IKK-β, and p65 phosphorylation as well as inflammatory cytokine expression were exaggerated with the HDAC6 inhibitor tubastatin A, and by dominant-negative HDAC6 with a mutated catalytic domain 2. Expression of HDAC6 wild-type protein suppressed LPS-induced myeloid differentiation primary response 88 (MyD88) acetylation, p65 (Lys³¹⁰) acetylation, MyD88/TNF receptor-associated factor 6 (TRAF6) coimmunoprecipitation, and proinflammatory TLR4 signaling in HPMEC. In a neonatal mouse model of sepsis, the HDAC6 inhibitor tubastatin A amplified lung EC TLR4 signaling and vascular permeability. HDAC6 inhibition augmented LPS-induced MyD88 acetylation, MyD88/TRAF6 binding, p65 acetylation, canonical TLR4 signaling, and inflammation in the developing lung. Sepsis-induced decreases in the fibroblast growth factors FGF2 and FGF7 and increase in matrix metalloproteinase-9 were worsened with HDAC6 inhibition, while elastin expression was equally suppressed. Exaggerated sepsis-induced acute lung inflammation observed with HDAC6 inhibition worsened alveolar simplification evidenced by increases in mean linear intercepts and decreased radial alveolar counts. Our studies reveal that HDAC6 is a constitutive negative regulator of cytoplasmic TLR4 signaling in EC and the developing lung. The therapeutic efficacy of augmenting HDAC6 activity in neonatal sepsis to prevent lung injury needs to be evaluated.

Activation of death-associated protein kinase 1 promotes neutrophil apoptosis to accelerate inflammatory resolution in acute respiratory distress syndrome

Acute respiratory distress syndrome (ARDS) is a uniform progression of overwhelming inflammation in lung tissue with extensive infiltration of inflammatory cells. Neutrophil apoptosis is thought to be a significant process in the control of the resolution phase of inflammation. It has been proved that 5-Aza-2'-deoxycytidine (Aza) can inhibit cancer by activating death-associated protein kinase 1 (DAPK1) to promote apoptosis. However, the effect of DAPK1 on neutrophil apoptosis is unclear, and research on the role of Aza in inflammation is lacking. Here, we investigated whether Aza can regulate DAPK1 expression to influence the fate of neutrophils in ARDS. In vitro, we stimulated neutrophil-like HL-60 (dHL-60) cells with different concentrations of Aza for different durations and used RNA interference to up- or downregulate DAPK1 expression. We observed that culturing dHL-60 cells with Aza increased apoptosis by inhibiting NF-κB activation to modulate the expression of Bcl-2 family proteins, which was closely related to the levels of DAPK1. In vivo, ARDS was evoked by intratracheal instillation of lipopolysaccharide (LPS; 3 mg/kg). One hour after LPS administration, mice were treated with Aza (1 mg/kg, i.p.). To inhibit DAPK1 expression, mice were intraperitoneally injected with a DAPK1 inhibitor. Aza treatment accelerated inflammatory resolution in LPS-induced ARDS by suppressing pulmonary edema, alleviating lung injury and decreasing the infiltration of inflammatory cells in bronchoalveolar lavage fluid (BALF). Moreover, Aza reduced the production of proinflammatory cytokines. However, administration of the DAPK1 inhibitor attenuated the protective effects of Aza. Similarly, the proapoptotic function of Aza was prevented when DAPK1 was inhibited either in vivo or in vitro. In summary, Aza promotes neutrophil apoptosis by activating DAPK1 to accelerate inflammatory resolution in LPS-induced ARDS. This study provides the first evidence that Aza prevents LPS-induced neutrophil survival by modulating DAPK1 expression.

Valproic acid attenuates sepsis-induced myocardial dysfunction in rats by accelerating autophagy through the PTEN/AKT/mTOR pathway

AIMS

Sepsis is a leading cause of death and disability worldwide. Autophagy may play a protective role in sepsis-induced myocardial dysfunction (SIMD). The present study investigated whether valproic acid (VPA), a class I histone deacetylase (HDAC) inhibitor, can attenuate SIMD by accelerating autophagy.

MAIN METHODS

A sepsis model was established via the cecum ligation and puncture of male Sprague-Dawley rats. Cardiac injuries were measured using serum markers, echocardiographic cardiac parameters, and hematoxylin and eosin staining. Cardiac mitochondria injuries were detected with transmission electron microscopy, adenosine triphosphate (ATP) and cardiac mitochondrial DNA (mtDNA) contents. Cardiac oxidative levels were measured using redox markers in the cardiac homogenate. Real-time polymerase chain reaction (RT-PCR) and Western blot were performed to detect the expression levels of relative genes and proteins. HDAC binding to the phosphatase and tensin homolog deleted on chromosome ten (PTEN) promoters and histone acetylation levels of the PTEN promoters were analyzed via chromatin immunoprecipitation and quantitative RT-PCR.

KEY FINDINGS

VPA can ameliorate SIMD by enhancing the autophagy level of the myocardium to reduce mitochondrial damage, oxidative stress, and myocardial inflammation in septic rats. Moreover, this study demonstrated that VPA induces autophagy by inhibiting HDAC1- and HDAC3-mediated PTEN expression in the myocardial tissues of septic rats.

SIGNIFICANCE

This study found that VPA attenuates SIMD through myocardial autophagy acceleration by increasing PTEN expression and inhibiting the AKT/mTOR pathway. These findings preliminarily suggest that VPA may be a potential approach for the intervention and treatment of SIMD.

Epigenetics in Sepsis: Understanding Its Role in Endothelial Dysfunction, Immunosuppression, and Potential Therapeutics

Sepsis has a complex pathophysiology in which both excessive and refractory inflammatory responses are hallmark features. Pro-inflammatory cytokine responses during the early stages are responsible for significant endothelial dysfunction, loss of endothelial integrity, and organ failure. In addition, it is now well-established that a substantial number of sepsis survivors experience ongoing immunological derangement and immunosuppression following a septic episode. The underpinning mechanisms of these phenomena are incompletely understood yet they contribute to a significant proportion of sepsis-associated mortality. Epigenetic mechanisms including DNA methylation, histone modifications, and non-coding RNAs, have an increasingly clear role in modulating inflammatory and other immunological processes. Recent evidence suggests epigenetic mechanisms are extensively perturbed as sepsis progresses, and particularly play a role in endothelial dysfunction and immunosuppression. Whilst therapeutic modulation of the epigenome is still in its infancy, there is substantial evidence from animal models that this approach could reap benefits. In this review, we summarize research elucidating the role of these mechanisms in several aspects of sepsis pathophysiology including tissue injury and immunosuppression. We also evaluate pre-clinical evidence for the use of "epi-therapies" in the treatment of poly-microbial sepsis.

Therapeutic Epigenetic Reprogramming of Trained Immunity in Myeloid Cells

Infiltrating and tissue-resident myeloid cells are essential regulators of innate and adaptive immunity. During inflammation, and in response to microbial products, these cells can adapt to microenvironmental conditions and acquire specialized functions, including phagocytosis and the production of proinflammatory cytokines. Such myeloid plasticity is driven, in part, by epigenetic dynamics that can sustain stable phenotypes after activation, and which may lead to maladaptive cell polarization states associated with inflammation and autoimmunity. Here, we review recent reports describing epigenetic mechanisms linked to such polarization states and innate immune memory (tolerance and training) in monocyte and macrophage lineages. We discuss how these mechanisms might be targeted to develop putative immunomodulatory tools that might be used to treat a variety of immune-mediated diseases.

TET1 Knockdown Inhibits Porphyromonas gingivalis LPS/IFN-γ-Induced M1 Macrophage Polarization through the NF-κB Pathway in THP-1 Cells

Tet-eleven translocation 1 (TET1) is a dioxygenase that plays an important role in decreasing the abundance of DNA methylation and changing the expression levels of specific genes related to inflammation. Porphyromonas gingivalis (Pg.) lipopolysaccharide (LPS) can induce periodontal diseases that present with severe bone loss and collagen fiber destruction accompanied by a high number of M1 macrophages. M1-polarized macrophages are pivotal immune cells that promote the progression of the periodontal inflammatory response, but the function of TET1 during M1 macrophage activation is still unknown. Our results showed that the mRNA and protein expression levels of TET1 decreased in THP-1 cells during M1 macrophage differentiation. TET1 knockdown resulted in a significant decrease in the production of proinflammatory markers such as IL-6, TNF-α, CCL2, and HLA-DR in Pg. LPS/IFN-γ- and Escherichia coli (E. coli) LPS/IFN-γ-induced M1 macrophages. Mechanistically, TET1 knockdown downregulated the activity of the NF-κB signaling pathway. After treatment with the NF-κB inhibitor BAY 11-7082, M1 marker expression showed no significant difference between the TET1 knockdown group and the control group. Taken together, these results suggest that TET1 depletion inhibited Pg. LPS/IFN-γ-induced M1 macrophage polarization through the NF-κB pathway in THP-1 cells.

Aflatoxin B1 Induces Immunotoxicity through the DNA Methyltransferase-Mediated JAK2/STAT3 Pathway in 3D4/21 Cells

As the most toxic mycotoxin of all of the fungal toxins, aflatoxin B₁ (AFB₁) has carcinogenesis, heptotoxicity, and immunotoxicity. DNA methylation plays a critical role in gene expression regulation of the pathological process. However, the relationship between DNA methylation and AFB₁-induced immunotoxicity was not yet reported. Therefore, the objectives of this study were to verify AFB₁-induced immunotoxicity and investigate the potential role of the DNA methyltransferase (DNMT) family in AFB₁-induced immunotoxicity and the pathway mechanism in 3D4/21 cells. The results showed that AFB₁ could induce cytotoxicity, apoptosis, pro-inflammatory cytokine expression, DNA damage, and oxidative stress and decrease phagocytotic capacity. Meanwhile, the levels of DNMT1 and DNMT3a were significantly increased in 0.04 and 0.08 μg/mL AFB₁ compared to the control. Inhibition of DNMT1 and DNMT3a by 5-Aza-2dc could reverse changes of the above parameters. Further, the JAK2/STAT3 pathway was significantly activated in 0.04 μg/mL AFB₁. Inhibition of p-JAK2 and p-STAT3 by AG490 could alleviate AFB₁-induced immunotoxicity. Moreover, inhibition of DNMT1 and DNMT3a by 5-Aza-2dc could suppress the phosphorylation of JAK2 and STAT3. Taken together, AFB₁-induced immunotoxicity is related to the JAK2/STAT3 pathway mediated by DNMTs in 3D4/21 cells.

Protective Effect of Tubastatin A in CLP-Induced Lethal Sepsis

We have found earlier that Tubastatin A (TubA), a selective inhibitor of histone deacetylase 6 (HDAC6), improves survival in a mouse model of lethal cecal ligation and puncture (CLP)-induced sepsis. However, the underlying mechanisms have not been fully established. This study sought to test the hypothesis that TubA could affect both lung and splenic functions. C57BL/6J mice were subjected to CLP, and randomized to receive either TubA (70 mg/kg) dissolved in dimethyl sulfoxide (DMSO), or DMSO alone, 1 h following CLP. Sham animals acted as control. Twenty-four hours later, lung tissue was harvested for pathological examination, and splenic tissue was harvested for bacterial colonization. In a parallel study, the spleen was collected 48 h following CLP, and single cell suspension was prepared. Splenocytes then underwent flow cytometry to analyze the immune cell population. RAW264.7 macrophages were treated with lipopolysaccharide (LPS) with or without the presence of TubA (10 μM) at 37 °C for 3 h to assess the effect on macrophage phagocytosis. We found that acute lung injury secondary to lethal sepsis was attenuated by TubA. Treatment with TubA restored the percentage of B lymphocytes, and significantly increased percentages of innate immune cells and macrophages compared to the vehicle-treated CLP group. Moreover, TubA significantly decreased the bacterial load in the spleen, and improved the phagocytic ability of RAW264.7 murine macrophages in vitro. Such findings may help to explain the beneficial effects of TubA treatment in a model of lethal sepsis, as previously reported.

Histone Deacetylation Inhibitors as Therapy Concept in Sepsis

Sepsis is characterized by dysregulated gene expression, provoking a hyper-inflammatory response occurring in parallel to a hypo-inflammatory reaction. This is often associated with multi-organ failure, leading to the patient’s death. Therefore, reprogramming of these pro- and anti-inflammatory, as well as immune-response genes which are involved in acute systemic inflammation, is a therapy approach to prevent organ failure and to improve sepsis outcomes. Considering epigenetic, i.e., reversible, modifications of chromatin, not altering the DNA sequence as one tool to adapt the expression profile, inhibition of factors mediating these changes is important. Acetylation of histones by histone acetyltransferases (HATs) and initiating an open-chromatin structure leading to its active transcription is counteracted by histone deacetylases (HDACs). Histone deacetylation triggers a compact nucleosome structure preventing active transcription. Hence, inhibiting the activity of HDACs by specific inhibitors can be used to restore the expression profile of the cells. It can be assumed that HDAC inhibitors will reduce the expression of pro-, as well as anti-inflammatory mediators, which blocks sepsis progression. However, decreased cytokine expression might also be unfavorable, because it can be associated with decreased bacterial clearance.

New frontiers in precision medicine for sepsis-induced immunoparalysis

INTRODUCTION

In the last decade, the sepsis research field has shifted focus from targeting hyperinflammation to reversing sepsis-induced immunoparalysis. Sepsis-induced immunoparalysis is very heterogeneous: the magnitude and the nature of the underlying immune defects differ considerably between patients, but also within individuals over time. Therefore, a 'one-treatment-fits-all' strategy for sepsis-induced immunoparalysis is bound to fail, and an individualized 'precision medicine' approach is required. Such a strategy is nevertheless hampered by the unsuitability of the currently available markers to identify the many immune defects that can manifest in individual patients. Areas covered: We describe the currently available markers for sepsis-induced immunoparalysis and limitations pertaining to their use. Furthermore, future prospects and caveats are discussed, focusing on 'omics' approaches: genomics, transcriptomics, epigenomics, and metabolomics. Finally, we present a contemporary overview of adjuvant immunostimulatory therapies. Expert opinion: The integration of multiple omics techniques offers a systems biology approach which can yield biomarker profiles that accurately and comprehensively gauge the extent and nature of sepsis-induced immunoparalysis. We expect this development to be instrumental in facilitating precision medicine for sepsis-induced immunoparalysis, consisting of the application of targeted immunostimulatory therapies and follow-up measurements to monitor the response to treatment and to titrate or adjust medication.

Anti-Inflammatory and Anti-Oxidant Activity of Portulaca oleracea Extract on LPS-Induced Rat Lung Injury

Acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) are classified as two lung complications arising from various conditions such as sepsis, trauma, and lung inflammation. Previous studies have shown that the extract of the leaves of Portulaca oleracea (PO) possesses anti-inflammatory and anti-oxidant activities. In the present study, the effects of PO (50–200 mg/kg) and dexamethasone (Dexa; 1.5 mg/kg) on lipopolysaccharide (LPS)-induced ALI were investigated. Subsequentially, the lung wet/dry ratio; white blood cells (WBC); levels of nitric oxide (NO); myeloperoxidase (MPO); malondialdehyde (MDA); thiol groups formation; super oxide dismutase (SOD) and catalase (CAT) activities; and levels of interleukin (IL)-1β, tumor necrosis factor (TNF)-α, IL-6, IL-10, prostaglandin E2 (PGE₂), and transforming growth factor (TGF)-β in the broncho alveolar lavage fluid (BALF) were evaluated in order to demonstrate the anti-oxidant and anti-inflammatory activity of PO. Our results show that PO suppresses lung inflammation by the reduction of IL-β, IL-6, TNF-α, PGE₂, and TGF-β, as well as by the increase of IL-10 levels. We also found that PO improves the level of WBC, MPO, and MDA, as well as thiol group formation and SOD and CAT activities, compared with the LPS group. The results of our investigation also show that PO significantly decreased the lung wet/dry ratio as an index of interstitial edema. Taken together, our findings reveal that PO extract dose-dependently displays anti-oxidant and anti-inflammatory activity against LPS-induced rat ALI, paving the way for rational use of PO as a protective agent against lung-related inflammatory disease.

Essential oil from Korean Chamaecyparis obtusa leaf ameliorates respiratory activity in Sprague‑Dawley rats and exhibits protection from NF-κB-induced inflammation in WI38 fibroblast cells

To date, Korean hinoki cypress (Chamaecyparis obtusa), has been widely used for household and commercial purposes. Although the medicinal efficacy of hinoki cypress essential oil has been observed, that of the essential oil‑derived terpenes, which exhibit a mechanism that acts against lung inflammation, remains to be fully elucidated. The present study investigated the anti‑inflammatory effect of hinoki cypress leaf extracted essential oil on lipopolysaccharide (LPS)‑stimulated WI38 fibroblast cells by inhibiting the nuclear factor κ‑light‑chain‑enhancer of activated B cells (NF‑κB) pathway, which exhibited lung tissue protection through the olfactory administration of essential oil in Sprague‑Dawley rats. GC/MS analysis derived 24 terpenes from the essential oil. The morphological observations revealed that, upon LPS stimulation of WI38 fibroblast cells, inflammation was induced, whereas the condition of the cells reverted to normal in the essential oil extract pre‑treated group. The results of western blot analysis revealed the inhibition of inducible nitric oxide synthase, activation of cyclooxygnase‑2, and the degradation of cytosolic p65 and inhibitor of NF‑κB‑α in the LPS‑stimulated group. Additionally, confocal imaging of nuclei revealed the translocation of phosphorylated p65, which was recovered in the cytosol in the phytoncide essential oil pre‑treated group. Histopathological observation revealed that the alveolar capacity was enhanced in the essential oil olfactory administered rat group, compared with that in the normal rat group. These findings suggest that terpenes in essential oil from the Chamaecyparis obtusa leaf have therapeutic potential against respiratory inflammation‑related disease.

The emerging spectrum of early life exposure-related inflammation and epigenetic therapy

Early life exposure to a variety of insults during sensitive windows of development can reprogram normal physiological responses and alter disease susceptibility later in life. During this process, Inflammation triggered by a variety of adverse exposures plays an important role in the initiation and development of many types of diseases including tumorigenesis. This review article summaries the current knowledge about the role and mechanism of inflammation in development of diseases. In addition, epigenome alteration related to inflammation and treatment options using epigenetic modifiers are highlighted and discussed.

DNMT and HDAC inhibitors together abrogate endotoxemia mediated macrophage death by STAT3-JMJD3 signaling

Acute lung injury (ALI) is a common complication of sepsis that often leads to fatal lung disease without effective therapies. It is known that bone marrow derived macrophages are important in resolving the inflammation and maintaining tissue homeostasis. Here, we hypothesize that treatment in combination of DNA methyl transferase inhibitor (DNMTi) 5-Aza 2-deoxycytidine (Aza) and histone deacetylase inhibitor (HDACi) Trichostatin A (TSA) mitigates the inflammation induced pyroptosis and apoptosis during endotoxemia induced ALI. To test this hypothesis, the mice challenged with a sublethal dose of LPS followed by one-hour post-treatment with a single dose of Aza and TSA intraperitoneally showed a substantial attenuation of apoptosis and inflammation. Importantly, we observed significant changes in the mitochondrial membrane structure, and lower levels of DNA fragmentation, reduced expression of apoptotic and pyroptotic genes both transcriptionally and translationally in LPS induced BMDMs treated by a combination of Aza and TSA than in LPS-induced BMDMs treated with either drug alone. The protection was mediated by an inhibition of JNK-ERK and STAT3-JMJD3 activated pathways. Thus, targeting these important signaling pathways with the combination of Aza and TSA would be a good treatment modality for ALI.

IRF5 is elevated in childhood-onset SLE and regulated by histone acetyltransferase and histone deacetylase inhibitors

Interferon regulatory factor 5 (IRF5) plays a critical role in the induction of type I interferon, proinflammatory cytokines and chemokines, and participates in the pathogenesis of autoimmune diseases such as systemic lupus erythematosus (SLE). However, the relationship between IRF5 and childhood-onset SLE remains elusive. In the present study, we demonstrated that levels of mRNA expression of IRF5, IFN-α, and Sp1 were significantly increased in childhood-onset SLE, as seen on quantitative real-time PCR, and the expression of Sp1 and IFN-α was positively correlated with IRF5. In addition to being used as antitumor drugs, a number of histone deacetylase inhibitors (HDACi) display potent anti-inflammatory properties; however, their effects on IRF5 expression remain unclear. In this study, we identified that HDACi trichostatin A (TSA) and histone acetyltransferase (HAT)-p300 downregulated IRF5 promoter activity, mRNA expression, and protein level, whereas the HAT-p300/CBP-associated factor had no effect. Moreover, TSA inhibited the production of TNF-α and IL-6 in differentiated THP-1cells. Furthermore, chromatin immunoprecipitation assays revealed that TSA inhibited DNA binding of Sp1, RNA polymerase II, HDAC3, and p300 to the core promoter region of IRF5. Our results suggest that HDACi may have therapeutic potential in patients with autoimmune diseases such as SLE through repression of IRF5 expression.

Macrophage Polarization in Chronic Inflammatory Diseases: Killers or Builders?

Macrophages are key cellular components of the innate immunity, acting as the main player in the first-line defence against the pathogens and modulating homeostatic and inflammatory responses. Plasticity is a major feature of macrophages resulting in extreme heterogeneity both in normal and in pathological conditions. Macrophages are not homogenous, and they are generally categorized into two broad but distinct subsets as either classically activated (M1) or alternatively activated (M2). However, macrophages represent a continuum of highly plastic effector cells, resembling a spectrum of diverse phenotype states. Induction of specific macrophage functions is closely related to the surrounding environment that acts as a relevant orchestrator of macrophage functions. This phenomenon, termed polarization, results from cell/cell, cell/molecule interaction, governing macrophage functionality within the hosting tissues. Here, we summarized relevant cellular and molecular mechanisms driving macrophage polarization in "distant" pathological conditions, such as cancer, type 2 diabetes, atherosclerosis, and periodontitis that share macrophage-driven inflammation as a key feature, playing their dual role as killers (M1-like) and/or builders (M2-like). We also dissect the physio/pathological consequences related to macrophage polarization within selected chronic inflammatory diseases, placing polarized macrophages as a relevant hallmark, putative biomarkers, and possible target for prevention/therapy.