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

Emodin suppresses mast cell migration via modulating the JAK2/STAT3/JMJD3/CXCR3 signaling to prevent cystitis

AIMS

This study aimed to determine the preventive effects of emodin on cyclophosphamide (CYP)-induced cystitis and to explore the molecular mechanism.

METHODS

In vivo, mice were modeled by CYP. Before a half hour of CYP treatment, Jumonji domain-containing protein-3 (JMJD3) inhibitors (GSK-J4) and emodin were used to treat CYP model mice. Bladder samples were stained for hematoxylin-eosin and toluidine blue. Next, JMJD3 was quantified by immunofluorescence staining, RT-PCR, and Western blot. CXCR3 was quantified by Western blot and ELISA. In vitro, before stimulated by lipopolysaccharide (LPS), human bladder smooth muscle cells (hBSMCs) were transfected with pcDNA3.1-JMJD3 plasmids, shRNA-JMJD3 plasmids or pretreated with emodin. Collected cells to detect JMJD3 and CXCR3 ligands again; collected supernatant of culture for Transwell assay. Finally, as the JAK2 inhibitor, AG490 was used to pretreat LPS-induced hBSMCs. Western blot was performed to quantify proteins.

RESULTS

Emodin inhibited mast cell migration and suppressed the expression of JMJD3, CXCR3, and CXCR3 ligands, not only in vivo but also in vitro. The pharmacological effects of emodin were similar to GSK-J4 or JMJD3 inhibition. In addition, emodin significantly downregulated the phosphorylation of JAK2 and STAT3, and inhibited JMJD3/CXCR3 axis transduction like AG490.

CONCLUSION

Emodin has a preventive effect on cystitis by inhibiting mast cell migration through inhibition of the JAK2/STAT3/JMJD3/CXCR3 signaling pathway.

Epigenetic regulation of diverse cell death modalities in cancer: a focus on pyroptosis, ferroptosis, cuproptosis, and disulfidptosis

Tumor is a local tissue hyperplasia resulted from cancerous transformation of normal cells under the action of various physical, chemical and biological factors. The exploration of tumorigenesis mechanism is crucial for early prevention and treatment of tumors. Epigenetic modification is a common and important modification in cells, including DNA methylation, histone modification, non-coding RNA modification and m6A modification. The normal mode of cell death is programmed by cell death-related genes; however, recent researches have revealed some new modes of cell death, including pyroptosis, ferroptosis, cuproptosis and disulfidptosis. Epigenetic regulation of various cell deaths is mainly involved in the regulation of key cell death proteins and affects cell death by up-regulating or down-regulating the expression levels of key proteins. This study aims to investigate the mechanism of epigenetic modifications regulating pyroptosis, ferroptosis, cuproptosis and disulfidptosis of tumor cells, explore possible triggering factors in tumor development from a microscopic point of view, and provide potential targets for tumor therapy and new perspective for the development of antitumor drugs or combination therapies.

Icariin ameliorates LPS-induced acute lung injury in mice via complement C5a-C5aR1 and TLR4 signaling pathways

Acute lung injury (ALI) is an acute respiratory-related progressive disorder, which lacks specific pharmacotherapy. Icariin (ICA) has been shown to be effective in treating ALI. However, the targets and pharmacological mechanisms underlying the effects of ICA in the treatment of ALI are relatively lacking. Based on network pharmacology and molecular docking analyses, the gene functions and potential target pathways of ICA in the treatment of ALI were determined. In addition, the underlying mechanisms of ICA were verified by immunohistochemistry, immunofluorescence, quantitative Real-time PCR, and Western blot in LPS-induced ALI mice. The biological processes targeted by ICA in the treatment of ALI included the pathological changes, inflammatory response, and cell signal transduction. Network pharmacology, molecular docking, and in vivo experimental results revealed that ICA inhibited the complement C5a-C5aR1 axis, TLR4 mediated NF-κB, MAPK, and JAK2-STAT3 signaling pathways related gene and protein expressions, and decreased inflammatory cytokine, chemokine, adhesion molecule expressions, and mitochondrial apoptosis in LPS-induced ALI.

Danshensu methyl ester attenuated LPS-induced acute lung injury by inhibiting TLR4/NF-κB pathway

Acute Lung Injury (ALI) manifests as an acute exacerbation of pulmonary inflammation with high mortality. The potential application of Danshensu methyl ester (DME, synthesized in our lab) in ameliorating ALI has not been elucidated. Our results demonstrated that DME led to a remarkable reduction in lung injury. DME promoted a marked increase in antioxidant enzymes, like superoxide dismutase (SOD), and glutathione (GSH), accompanied by a substantial decrease in reactive oxygen species (ROS), myeloperoxidase (MPO), and malondialdehyde (MDA). Moreover, DME decreased the production of IL-1β, TNF-α and IL-6, in vitro and in vivo. TLR4 and MyD88 expression is reduced in the DME-treated cells or tissues, which further leading to a decrease of p-p65 and p-IκBα. Meanwhile, DME effectively facilitated an elevation in cytoplasmic p65 expression. In summary, DME could ameliorate ALI by its antioxidant functionality and anti-inflammation effects through TLR4/NF-κB, which implied that DME may be a viable medicine for lung injury.

Multimodal nanoparticle-containing modified suberoylanilide hydroxamic acid polymer conjugates to mitigate immune dysfunction in severe inflammation

Excessive immune activation and immunosuppression are opposing factors that contribute to the dysregulated innate and adaptive immune responses seen in severe inflammation and sepsis. Here, a novel analog of the histone deacetylase inhibitor (HDACi), suberoylanilide hydroxamic acid (SAHA-OH), was incorporated into immunomodulatory poly(lactic acid)-based nanoparticles (iNP-SAHA) by employing a prodrug approach through the covalent modification of poly(lactic-co-glycolic acid) (PLGA) with SAHA-OH. iNP-SAHA formulation allowed for controlled incorporation and delivery of SAHA-OH from iNP-SAHA and treatment led to multimodal biological responses including significant reductions in proinflammatory cytokine secretions and gene expression, while increasing the survival of primary macrophages under lipopolysaccharide (LPS) challenge. Using a lethal LPS-induced endotoxemia mouse model of sepsis, iNP-SAHA administration improved the survival of mice in a dose-dependent manner and tended to improve survival at the lowest doses compared to iNP control. Further, iNP-SAHA reduced the levels of plasma proinflammatory cytokines and chemokines associated with sepsis more significantly than iNP and similarly improved inflammation-induced spleen and liver toxicity as iNP, supporting its potential polypharmacological activity. Collectively, iNP-SAHA offers a potential drug delivery approach to modulate the multifaceted inflammatory responses observed in diseases such as sepsis.

Syringaresinol alleviates IgG immune complex induced acute lung injury via activating PPARγ and suppressing pyroptosis

Acute lung injury (ALI) is a life-threatening condition characterized by severe lung inflammation and tissue damage. In this study, we investigate the potential therapeutic efficacy of (+)-Syringaresinol (SYG), a natural compound known for its antioxidant and anti-inflammatory properties, in alleviating ALI induced by IgG immune complexes (IgG-IC). Using MH-S cells as a model, we explore SYG's ability to target peroxisome proliferator-activated receptor gamma (PPARγ) and its anti-inflammatory properties. Our comprehensive investigation aims to elucidate the specific molecular mechanisms underlying SYG's effects against pyroptosis, as revealed through transcriptomic analysis. Validation in C57BL/6 mice provides in vivo support. Our findings indicate that SYG effectively mitigates IgG-IC-induced lung damage, as evidenced by a significant reduction in lung inflammation and tissue injury. SYG treatment notably decreases pro-inflammatory cytokine levels (TNF-α, IL-6, IL-1β) in both lung tissue and cells. Molecular docking analysis reveals SYG's robust binding to PPARγ, leading to the inhibition of IgG-IC-induced inflammatory signaling pathways. Additionally, transcriptomic analysis unveils SYG's potential in suppressing macrophage pyroptosis, potentially through the downregulation of key inflammatory mediators (NLRP3, GSDMD, Caspase-1). In summary, our study presents compelling evidence supporting SYG as an effective therapeutic agent for ALI. SYG's activation of PPARγ contributes to the suppression of NF-κB and C/EBPs expression, thereby mitigating inflammation. Moreover, SYG demonstrates the ability to inhibit macrophage pyroptosis by targeting the NLRP3/GSDMD/caspase-1 axis.

Dexmedetomidine suppresses hippocampal astrocyte pyroptosis in cerebral hypoxic-ischemic neonatal rats by upregulating microRNA-148a-3p to inactivate the STAT/JMJD3 axis

OBJECTIVE

Dexmedetomidine (DEX), a selective α2-adrenoceptor agonist, is an anesthetic and sedative agent and has been reported to confer neuroprotective effects after cerebral hypoxic ischemia (CHI). This study was undertaken to elucidate the mechanisms by which microRNA (miR)-148a-3p is involved in the neuroprotective effect of DEX on hypoxic-ischemic brain damage in neonatal rats.

METHODS

Neonatal rats were exposed to CHI conditions, a miR-148a-3p inhibitor, and DEX. Hippocampal astrocytes were isolated to construct an oxygen-glucose deprivation (OGD) model. qRT-PCR and western blot were utilized to inspect miR-148a-3p, STAT1, STAT3, JMJD3, cleaved-Caspase-1, ASC, NLRP3, GSDMD, and GSDMD-N expression in rats and astrocytes. TUNEL staining was employed to measure astrocyte apoptosis rate, immunofluorescence to inspect cleaved-Caspase-1 and ASC levels, and ELISA to determine IL-1β and IL-18 expression. The target genes of miR-148a-3p were predicted using online software and verified by a dual-luciferase reporter gene assay.

RESULTS

A prominent increase in astrocyte apoptosis rate and the expression of pyroptosis- and inflammation-related factors were found in rats with CHI and OGD-treated astrocytes. DEX suppressed astrocyte apoptosis rate and decreased expression of pyroptosis- and inflammation-related factors. Knockdown of miR-148a-3p facilitated astrocyte pyroptosis, indicating that DEX exerted its protective effect by upregulating miR-148a-3p. miR-148a-3p negatively mediated STAT to inactivate JMJD3. Overexpression of STAT1 and STAT3 facilitated pyroptosis in astrocytes, which was negated by the overexpression of miR-148a-3p.

CONCLUSION

DEX inhibited hippocampal astrocyte pyroptosis by upregulating miR-148a-3p to inactivate the STAT/JMJD3 axis, thereby alleviating cerebral damage in neonatal rats with CHI.

The Role of Histone Deacetylases in Acute Lung Injury-Friend or Foe

Acute lung injury (ALI), caused by intrapulmonary or extrapulmonary factors such as pneumonia, shock, and sepsis, eventually disrupts the alveolar-capillary barrier, resulting in diffuse pulmonary oedema and microatasis, manifested by refractory hypoxemia, and respiratory distress. Not only is ALI highly lethal, but even if a patient survives, there are also multiple sequelae. Currently, there is no better treatment than supportive care, and we urgently need to find new targets to improve ALI. Histone deacetylases (HDACs) are epigenetically important enzymes that, together with histone acetylases (HATs), regulate the acetylation levels of histones and non-histones. While HDAC inhibitors (HDACis) play a therapeutic role in cancer, inflammatory, and neurodegenerative diseases, there is also a large body of evidence suggesting the potential of HDACs as therapeutic targets in ALI. This review explores the unique mechanisms of HDACs in different cell types of ALI, including macrophages, pulmonary vascular endothelial cells (VECs), alveolar epithelial cells (AECs), and neutrophils.

Epigenetic mechanisms of Immune remodeling in sepsis: targeting histone modification

Sepsis is a life-threatening disorder disease defined as infection-induced dysregulated immune responses and multiple organ dysfunction. The imbalance between hyperinflammation and immunosuppression is a crucial feature of sepsis immunity. Epigenetic modifications, including histone modifications, DNA methylation, chromatin remodeling, and non-coding RNA, play essential roles in regulating sepsis immunity through epi-information independent of the DNA sequence. In recent years, the mechanisms of histone modification in sepsis have received increasing attention, with ongoing discoveries of novel types of histone modifications. Due to the capacity for prolonged effects on immune cells, histone modifications can induce immune cell reprogramming and participate in the long-term immunosuppressed state of sepsis. Herein, we systematically review current mechanisms of histone modifications involved in the regulation of sepsis, summarize their role in sepsis from an immune perspective and provide potential therapeutic opportunities targeting histone modifications in sepsis treatment.

HDAC Inhibitor SAHA Alleviates Pyroptosis by up-regulating miR-340 to Inhibit NEK7 Signaling in Subarachnoid Hemorrhage

BACKGROUND

Subarachnoid hemorrhage (SAH) is a cerebral hemorrhagic disease with a high disability and fatality rate. Cell pyroptosis is involved in the brain injury following SAH. Here, we explored the effect of HDAC inhibitor SAHA against cell pyroptosis after SAH.

METHODS

The rat SAH model was established by endovascular perforation and the rat microglia were treated with 25 μm oxyhemoglobin (OxyHb) for 24 h to mimic SAH model in vitro. Neurological score and brain edema were assessed in rat SAH model. TUNEL staining detected apoptosis. qRT-PCR and western blotting were employed to detect expression levels of miR-340, NEK7 and inflammatory cytokines. ELISA assay determined the secretion of IL-1β and IL-18 in rat serum and cell supernatant. A lactate dehydrogenase (LDH) kit measured the LDH activity in rat primary microglia. Microglia pyroptosis was detected by flow cytometry. RIP and dual luciferase reporter assays confirmed the binding relationship between miR-340 and NEK7.

RESULTS

SAHA alleviated neurological dysfunction, inflammatory injury and microglia pyroptosis in SAH rats. SAHA suppressed LDH release, inflammatory factor expression and pyroptosis in microglia treated with OxyHb. Meanwhile, SAHA increased miR-340 expression and inhibited NEK7 level in vivo and in vitro SAH models. Further, miR-340 directly targeted NEK7 to inhibit the NLRP3 signaling pathway. Knockdown of miR-340 or overexpression of NEK7 reversed the suppressive effects of SAHA on microglia inflammation and pyroptosis. Additionally, knockdown of NEK7 impaired microglia inflammation and pyroptosis induced by miR-340 inhibitor.

CONCLUSION

HDAC inhibitor SAHA ameliorates microglia pyroptosis in SAH through triggering miR-340 expression to suppress NEK7 signaling. This novel mechanism provides promise for SAHA in SAH treatment.

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.

Novel pharmacological inhibition of JMJD3 improves necrotizing enterocolitis by attenuating the inflammatory response and ameliorating intestinal injury

Necrotizing enterocolitis (NEC), an acute intestinal inflammatory disease of premature infants, is one of the leading causes of death in neonates. Effective measures for clinical treatment are limited and there is a pressing need in searching for new therapeutic strategies. Jumonji domain-containing protein D3 (JMJD3), a histone H3 lysine 27 (H3K27) demethylase plays a proinflammatory role in sepsis and neuroinflammation. However, whether JMJD3 is involved in the pathogenesis of NEC has not been elucidated. Here we report that overexpressed JMJD3 was revealed in the intestine of NEC patients by bioinformatic analysis. Moreover, upregulated JMJD3 and suppressed H3K27me3 were detected in both NEC patients and neonatal mice subjected to experimental NEC. Importantly, administration of GSK-J4, a specific JMJD3 inhibitor, rescued neonatal mice from NEC-associated lethality by suppressing proinflammatory response with attenuated IL-6, TNF-α, and MCP-1 levels and ameliorating intestinal injury with reversed claudin-1, occludin, and E-cadherin expression. Remarkably, administration of GSK-J4 attenuated intestinal injury by inhibiting activation of intestinal necroptosis in NEC mice. Administration of GSK-J4 regulated intestinal inflammation via NF-κB and JAK2/STAT3 pathway. These results indicate that JMJD3 is involved in the development of NEC and inhibition of JMJD3 overexpression by mean of GSK-J4 could be a potential therapeutic approach in the prevention and treatment of NEC.

Effect of Dihydroquercetin on Energy Metabolism in LPS-Induced Inflammatory Mice

This study investigated the effects and alterations of dihydroquercetin on the growth performance, nutriment metabolism, antioxidant and immune function, and energy substrate utilization in lipopolysaccharide-challenged mice. A total of 0, 50, and 200 mg/kg of dihydroquercetin were intragastrically administered once a day for 21 days. After the pretreatment with dihydroquercetin, each group was subjected to a lipopolysaccharide challenge (except for the control group). After lipopolysaccharide injection, food intake, body weight, metabolic indexes of blood and liver nutrients, blood inflammatory factors, and liver oxidative stress indexes were measured at 6, 12, 24, and 48 h, respectively. Indirect calorimetry analysis was performed by respiratory gas analysis for 48 h to calculate the energy substrate metabolism of carbohydrate, fat, and protein. Urinary nitrogen excretion was measured to evaluate the urinary protein metabolism to calculate the substrate utilization. The results showed that dihydroquercetin pretreatment can significantly increase the weight gain and average food intake and decrease the mortality rate in lipopolysaccharide-induced inflammation mice. Furthermore, dihydroquercetin pretreatment can alleviate the negative effects of lipopolysaccharides by increasing levels of superoxide dismutase and glutathione peroxidase and by decreasing the malondialdehyde and serum inflammatory cytokines (interleukin-1β, nuclear factor κB, and interleukin-6). Dihydroquercetin pretreatment also can relieve nutrient metabolic disorder by increasing blood glucose, serum total protein, and liver glycogen levels and reducing serum and liver triglycerides, serum cholesterol, serum lactate dehydrogenase, and serum urea nitrogen levels. Meanwhile, it increases the relative utilization of carbohydrate, reducing relative utilization of protein and lipid, alleviating the change in energy metabolism pattern from glucose-predominant to lipid-predominant caused by lipopolysaccharide stimulation. In addition, the degree of metabolic pattern transformation depends on the dose of dihydroquercetin supplement. Finally, according to principal component analysis, we found that the inflammation was strongest in the mice at 24 h and was subsequently relieved in the LPS-stimulated group, whereas in the dihydroquercetin-pretreated group, the inflammation was initially relieved. To summarize, dihydroquercetin pretreatment can improve energy metabolism disorder and attenuate the negative effects of lipopolysaccharide challenge in mice from the initial stage of inflammation.

Epigenetic Regulation of Inflammatory Signaling and Inflammation-Induced Cancer

Epigenetics comprise a diverse array of reversible and dynamic modifications to the cell’s genome without implicating any DNA sequence alterations. Both the external environment surrounding the organism, as well as the internal microenvironment of cells and tissues, contribute to these epigenetic processes that play critical roles in cell fate specification and organismal development. On the other hand, dysregulation of epigenetic activities can initiate and sustain carcinogenesis, which is often augmented by inflammation. Chronic inflammation, one of the major hallmarks of cancer, stems from proinflammatory cytokines that are secreted by tumor and tumor-associated cells in the tumor microenvironment. At the same time, inflammatory signaling can establish positive and negative feedback circuits with chromatin to modulate changes in the global epigenetic landscape. In this review, we provide an in-depth discussion of the interconnected crosstalk between epigenetics and inflammation, specifically how epigenetic mechanisms at different hierarchical levels of the genome control inflammatory gene transcription, which in turn enact changes within the cell’s epigenomic profile, especially in the context of inflammation-induced cancer.

Inhibition of Histone H3 Lysine-27 Demethylase Activity Relieves Rheumatoid Arthritis Symptoms via Repression of IL6 Transcription in Macrophages

Rheumatoid arthritis (RA) occurs in about 5 per 1,000 people and can lead to severe joint damage and disability. However, the knowledge of pathogenesis and treatment for RA remains limited. Here, we found that histone demethylase inhibitor GSK-J4 relieved collagen induced arthritis (CIA) symptom in experimental mice model, and the underlying mechanism is related to epigenetic transcriptional regulation in macrophages. The role of epigenetic regulation has been introduced in the process of macrophage polarization and the pathogenesis of inflammatory diseases. As a repressive epigenetic marker, tri-methylation of lysine 27 on histone H3 (H3K27me3) was shown to be important for transcriptional gene expression regulation. Here, we comprehensively analyzed H3K27me3 binding promoter and corresponding genes function by RNA sequencing in two differentially polarized macrophage populations. The results revealed that H3K27me3 binds on the promoter regions of multiple critical cytokine genes and suppressed their transcription, such as IL6, specifically in M-CSF derived macrophages but not GM-CSF derived counterparts. Our results may provide a new approach for the treatment of inflammatory and autoimmune disorders.

HDAC11 promotes both NLRP3/caspase-1/GSDMD and caspase-3/GSDME pathways causing pyroptosis via ERG in vascular endothelial cells

Histone deacetylase 11 (HDAC11), a sole member of the class IV HDAC subfamily, participates in various cardiovascular diseases. Recent evidence showed that pyroptosis was a form of inflammatory programmed cell death and is critical for atherosclerosis (AS). However, little is known about the effect of HDAC11 on endothelial cell pyroptosis in AS. Thus, this study aims to investigate the role of HDAC11 in vascular endothelial cell pyroptosis and its molecular mechanism. Firstly, we found that HDAC11 expression was up-regulated and pyroptosis occurred in the aorta of ApoE^−/− mice fed with a high-fat diet (HFD) for 8 or 12 weeks. Then, in vitro study found the treatment of human umbilical vein endothelial cells (HUVECs) with tumor necrosis factor-α (TNF-α) resulted in pyroptosis, as evidenced by activation of caspase-1 and caspase-3 activation, cleavage of downstream gasdermin D (GSDMD) and gasdermin E (GSDME/DFNA5), the release of pro-inflammatory cytokines interleukin (IL)-1β, IL-6 and IL-18, as well as elevation of LDH activity and increase of propidium iodide (PI)-positive cells. Besides, TNF-α increased HDAC11 expression and induced pyroptosis via TNFR1 in HUVECs. HDAC11 knockdown mitigated pyroptosis by suppressing both NLRP3/caspase-1/GSDMD and caspase-3/GSDME pathways in TNF-α-induced HUVECs. Moreover, GSDME knockdown by siRNA significantly decreased pyroptosis and inflammatory response, while treatment with disulfiram or necrosulfonamide (NSA) further augmented the inhibitory effects of GSDME siRNA on pyroptosis and inflammatory response. Further studies found HDAC11 formed a complex with ERG and decreased the acetylation levels of ERG. More importantly, ERG knockdown augmented vascular endothelial cell pyroptosis in TNF-α-induced HUVECs. Taken together, our study suggests that HDAC11 might promote both NLRP3/caspase-1/GSDMD and caspase-3/GSDME pathways leading to pyroptosis via regulation of ERG acetylation in HUVECs. Modulation of HDAC11 may serve as a potential target for therapeutic strategies of AS.

Epigenetic Regulation: A Link between Inflammation and Carcinogenesis

Simple Summary

Epigenetics encompasses all the modifications that occur within cells that are independent of gene mutations. The environment is the main influencer of these alterations. It is well known that a proinflammatory environment can promote and sustain the carcinogenic process and that this environment induces epigenetic alterations. In this review, we will report how a proinflammatory microenvironment that encircles the tumor core can be responsible for the induction of epigenetic drift.

Abstract

Epigenetics encompasses a group of dynamic, reversible, and heritable modifications that occur within cells that are independent of gene mutations. These alterations are highly influenced by the environment, from the environment that surrounds the human being to the internal microenvironments located within tissues and cells. The ways that pigenetic modifications promote the initiation of the tumorigenic process have been widely demonstrated. Similarly, it is well known that carcinogenesis is supported and prompted by a strong proinflammatory environment. In this review, we introduce our report of a proinflammatory microenvironment that encircles the tumor core but can be responsible for the induction of epigenetic drift. At the same time, cancer cells can alter their epigenetic profile to generate a positive loop in the promotion of the inflammatory process. Therefore, an in-depth understanding of the epigenetic networks between the tumor microenvironment and cancer cells might highlight new targetable mechanisms that could prevent tumor progression.

Cordyceps militaris extract induces apoptosis and pyroptosis via caspase-3/PARP/GSDME pathways in A549 cell line

Cordyceps militaris (CM) is traditionally used as dietary therapy for lung cancer patients in China. CM extract (CME) is hydrosoluble fraction of CM and extensively investigated. Caspase-3-involved cell death is considered as its major anticancer mechanism but inconclusive. Therefore, we explore its caspase-3-dependent programmed cell death nature (apoptosis and pyroptosis) and validate its caspase-3-dependent property in loss-of-function experiment. Component profile of CME is detected by High Performance Liquid Chromatography- quadrupole time-of-flight mass spectrometry (HPLC-qTOF). Results show that CME causes pyroptosis-featured cell bubbling and cell lysis and inhibits cell proliferation in A549 cell. CME induces chromatin condensing and makes PI+/annexin V+ staining in bubbling cells, indicating genotoxicity, apoptosis, and pyroptosis cell death are caused by CME. High concentration of CME (200 μg/ml) exerts G2/M and G0 cell cycles arresting and suppresses P53-downstream proliferative proteins, including P53, P21, CDC25B, CyclinB1, Bcl-2, and BCL2 associated agonist of cell death (BAD), but 1-100 μg/ml of CME show less effect on proteins above. Correspondingly, caspase-3 activity and caspase-3 downstream proteins including pyroptotic effector gasdermin-E (GSDME) and apoptotic marker cleaved-poly-ADP-ribose polymerase (PARP) are significantly promoted by CME. Moreover, regarding membrane pore formation in pyroptotic cell, expression of membrane GSDME (GSDME antibody conjugated with PE-Cy7 for detection in flow cytometry) is remarkably increased by CME treatment. By contrast, other pyroptosis-related proteins such as P2X7, NLRP3, GSDMD, and Caspase-1 are not affected after CME treatment. Additionally, TET2 is unexpectedly raised by CME. In present of caspase-3 inhibitor Ac-DEVD-CHO (Ac-DC), CME-induced cytotoxicity, cell bubbling, and genotoxicity are reduced, and CME-induced upregulation of apoptosis (cleaved-PARP-1) and pyroptosis (GSDME-NT) proteins are reversed. Lastly, 22 components are identified in HPLC-qTOF experiment, and they are classified into trophism, neoadjuvant component, cytotoxic component, and cancer deterioration promoter according to previous references. Conclusively, CME causes caspase-3-dependent apoptosis and pyroptosis in A549 through caspase-3/PARP and caspase-3/GSDME pathways, and it provides basic insight into clinic application of CME for cancer patients.

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.

Downregulation of HDAC8 expression decreases CD163 levels and promotes the apoptosis of macrophages by activating the ERK signaling pathway in recurrent spontaneous miscarriage

Recurrent spontaneous miscarriage (RSM) is a systemic disorder that has been defined as two or more pregnancies lost before the 20th week of gestation. Although the impaired function of macrophages at the maternal-fetal interface has been reported to be associated with RSM, the underlying mechanisms have not been fully elucidated. Here, we revealed that HDAC8 plays a critical role in RSM. Our results show that the mRNA and protein expression of HDAC8 was decreased in decidual macrophages from RSM patients. Moreover, the knockdown of HDAC8 resulted in a significant decrease in CD163 expression and an increase in apoptosis in dTHP-1 macrophages. Mechanistically, the ERK signaling pathway was activated in HDAC8-knockdown macrophages. When HDAC8-knockdown cells were pretreated with the ERK inhibitor U0126, expression levels of CD163, activated caspases 3, 7 and 9, and the apoptosis rate, were rescued. Taken together, our current results suggest that HDAC8 plays an important role in macrophage activation and apoptosis and may contribute to maintaining normal pregnancy by increasing the expression of M2 marker genes and inhibiting the apoptosis of macrophages at the maternal-fetal interface.

Dexmedetomidine preconditioning ameliorates lung injury induced by pulmonary ischemia/reperfusion by upregulating promoter histone H3K4me3 modification of KGF-2

Keratinocyte growth factor (KGF)-2 has been highlighted to play a significant role in maintaining the endothelial barrier integrity in lung injury induced by ischemia-reperfusion (I/R). However, the underlying mechanism remains largely unknown. The aims of this study were to determine whether dexmedetomidine preconditioning (DexP) modulates pulmonary I/R-induced lung injury through the alteration in KGF-2 expression. In our I/R-modeled mice, DexP significantly inhibited pathological injury, inflammatory response, and inflammatory cell infiltration, while promoted endothelial barrier integrity and KGF-2 promoter activity in lung tissues. Bioinformatics prediction and ChIP-seq revealed that I/R significantly diminished the level of H3K4me3 modification in the KGF-2 promoter, which was significantly reversed by DexP. Moreover, DexP inhibited the expression of histone demethylase JMJD3, which in turn promoted the expression of KGF-2. In addition, overexpression of JMJD3 weakened the protective effect of DexP on lung injury in mice with I/R. Collectively, the present results demonstrated that DexP ameliorates endothelial barrier dysfunction via the JMJD3/KGF-2 axis.

Epigenetic Regulation in Sepsis, Role in Pathophysiology and Therapeutic Perspective

Sepsis is characterized by an initial hyperinflammatory response, with intense cell activation and cytokine storm. In parallel, a prolonged compensatory anti-inflammatory response, known as immunological tolerance, can lead to immunosuppression. Clinically, this condition is associated with multiple organ failure, resulting in the patient's death. The mechanisms underlying the pathophysiology of sepsis are not yet fully understood, but evidence is strong showing that epigenetic changes, including DNA methylation and post-translational modifications of histones, modulate the inflammatory response of sepsis. During the onset of infection, host cells undergo epigenetic changes that favor pathogen survival. Besides, epigenetic changes in essential genes also orchestrate the patient's inflammatory response. In this review, we gathered studies on sepsis and epigenetics to show the central role of epigenetic mechanisms in various aspects of the pathogenesis of sepsis and the potential of epigenetic interventions for its treatment.

The Role of Immune Cells in Recurrent Spontaneous Abortion

Recurrent spontaneous abortion affects approximately 1–2% of women of childbearing, and describes a condition in which women suffer from three or more continuous spontaneous miscarriages. However, the origin of recurrent spontaneous abortion (RSA) remains unknown, preventing effective treatment and placing stress upon patients. It has been acknowledged that successful pregnancy necessitates balanced immune responses. Therefore, immunological aberrancy may be considered a root cause of poor pregnancy outcomes. Considerable published studies have investigated the relationship between various immune cells and RSA. Here, we review current knowledge on this area, and discuss the five main categories of immune cells involved in RSA; these include innate lymphocytes (ILC), macrophages, decidual dendritic cells (DCs), and T cells. Furthermore, we sought to summarize the impact of the multiple interactions of various immune cells on the emergence of RSA. A good understanding of pregnancy-induced immunological alterations could reveal new therapeutic strategies for favorable pregnancy outcomes.

Hydroxytyrosol Acetate Inhibits Vascular Endothelial Cell Pyroptosis via the HDAC11 Signaling Pathway in Atherosclerosis

Hydroxytyrosol acetate (HT-AC), a natural polyphenolic compound in olive oil, exerts an anti-inflammatory effect in cardiovascular diseases (CVDs). Pyroptosis is a newly discovered form of programmed inflammatory cell death and is suggested to be involved in the atherosclerosis (AS) process. However, the effect of HT-AC on vascular endothelial cell pyroptosis remains unknown. Thus, we aimed to investigate the effect of HT-AC on vascular endothelial cell pyroptosis in AS and related signaling pathways. In vivo studies showed that HT-AC alleviated the formation of atherosclerotic lesions and inhibited pyroptosis in the aortic intima of ApoE^−/− mice fed a high-fat diet (HFD) for 12 weeks. In vitro, we found that HT-AC treatment of human umbilical vein endothelial cells (HUVECs) alleviated tumor necrosis factor-alpha (TNF-α)-induced pyroptosis by decreasing the number of PI positive cells, decreasing the enhanced protein expressions of activated caspase-1 and gasdermin D (GSDMD), as well as by decreasing the release of pro-inflammatory interleukin (IL)-1β and IL-6. Besides, HT-AC down-regulated HDAC11 expression in the aortic intima of HFD-fed ApoE^−/− mice and TNF-α-stimulated HUVECs. To determine the underlying mechanism of action, molecular docking and drug affinity responsive target stability (DARTS) were utilized to identify whether HDAC11 protein is a target of HT-AC. The molecular docking result showed good compatibility between HT-AC and HDAC11. DARTS study's result showed that HDAC11 protein may be a target of HT-AC. Further study demonstrated that knockdown of HDAC11 augmented the inhibition of HT-AC on pyroptosis in TNF-α-stimulated HUVECs. These findings indicate that HT-AC might prevent vascular endothelial pyroptosis through down-regulation of HDAC11 related signaling pathway in AS.

Histone Deacetylase 6 Regulates the Activation of M1 Macrophages by the Glycolytic Pathway During Acute Liver Failure

Background

The glycolysis pathway of M1 macrophages is a key factor affecting the inflammatory response. The aim of this article is to investigate the role of histone deacetylase 6 (HDAC6) in the M1 macrophage glycolysis pathway during acute liver failure (ALF).

Methodology

Targeted metabolomics for quantitative analysis of energy metabolites technology was used to detect the characteristics of energy metabolism for 8 ALF patients and 8 normal volunteers. The ALF mice model was intervened with HDAC6 inhibitor ACY-1215. iTRAQ/TMT quantitative proteomics was used to detect protein expression in livers in different mice groups. The liver function, energy metabolites, M1 macrophages, cytokines, and pathological structure, DDX3X, NLRP3 and DNMT1 in liver tissue were detected. The changes of the above molecules were verified in cell groups.

Results

ALF patients and mice have significant energy metabolism disorders, accompanied by activation of M1 macrophages. After the intervention of ACY-1215, the activated M1 macrophages and cytokines levels in the mouse liver were reduced. The levels of IDH1, MDH1, and ATP were significantly increased. The expression of DDX3X increased, while the expression of NLRP3 and DNMT1 decreased. ACY-1215 could reduce the model cell apoptosis level and inflammatory response, and improve energy metabolism. It could also promote the expression of DDX3X, and inhibit the expression of NLRP3 and DNMT1.

Conclusion

ACY-1215 could inhibit the activation of M1 macrophages by improving the glycolytic pathway through regulating DNMT1 and DDX3X/NLRP3 signals to alleviate ALF.

Sepsis, immunosuppression and the role of epigenetic mechanisms

Introduction: Sepsis has pro- and anti-inflammatory processes caused by infectious agents. Sepsis survivors have impaired immune response due to immunosuppression. Gene expression during the inflammatory process is guided by transcriptional access to chromatin, with post-translational changes made in histones that determine whether the loci of the inflammatory gene are active, balanced, or suppressed. For this, a review literature was performed in PubMed included 'sepsis' and 'epigenetic' and 'immunosuppression' terms until May 2020.Areas covered: This review article explores the relationship between epigenetic mechanisms and the pathophysiology of sepsis. Epigenetic changes, vulnerable gene expression, and immunosuppression are related to inflammatory insults that can modify the dynamics of the central nervous system. Therefore, it is important to investigate the timing of these changes and their dynamics during the disease progression.Expert opinion: Epigenetic changes are associated with the main stages of sepsis, from the pathogen-host interaction to inflammation and immunosuppression. These changes are key regulators of gene expression during physiological and pathological conditions. Thus, epigenetic markers have significant prognostic and diagnostic potential in sepsis, and epigenetic changes can be explored in combination with therapeutic strategies in experimental models of the disease.

Inflammatory Caspases Drive Pyroptosis in Acute Lung Injury

Acute lung injury (ALI), a critical respiratory disorder that causes diffuse alveolar injury leads to high mortality rates with no effective treatment. ALI is characterized by varying degrees of ventilation/perfusion mismatch, severe hypoxemia, and poor pulmonary compliance. The diffuse injury to cells is one of most important pathological characteristics of ALI. Pyroptosis is a form of programmed cell death distinguished from apoptosis induced by inflammatory caspases, which can release inflammatory cytokines to clear cells infected by pathogens and promote monocytes to reassemble at the site of injury. And pyroptosis not only promotes inflammation in certain cell types, but also regulates many downstream pathways to perform different functions. There is increasing evidence that pyroptosis and its related inflammatory caspases play an important role in the development of acute lung injury. The main modes of activation of pyroptosis is not consistent among different types of cells in lung tissue. Meanwhile, inhibition of inflammasome, the key to initiating pyroptosis is currently the main way to treat acute lung injury. The review summarizes the relationship among inflammatory caspases, pyroptosis and acute lung injury and provides general directions and strategies to conduct further research.

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.

Cellular and molecular features of senescence in acute lung injury

A wide range of insults can trigger acute injury in the lungs, which eventually may lead to respiratory failure and death of patients. Current treatment relies mainly on supportive measures and mechanical ventilation. Even so, survivors frequently develop important sequels that compromise quality of life. In the search for new approaches to prevent and treat acute lung injury, many investigations have focused on molecular and cellular pathways which could exert a pathogenic role in this disease. Herein, we review recent findings in the literature suggesting that cellular senescence could be involved in lung injury and discuss the potential use of senotherapies to prevent disease progression.

Low shear stress regulates vascular endothelial cell pyroptosis through miR-181b-5p/STAT-3 axis

Low shear stress and pyroptosis both play an important role in the onset and development of atherosclerosis (AS). MicroRNAs (miRNAs) are a kind of short (18-22) nucleotide sequences that can bind to the 3'-untranslated region (3'-UTR) of messenger RNA, thereby regulating programmed cell death including pyroptosis. However, the function of miRNAs in cells subjected to shear stress conditions is unknown. Therefore, we conducted the current study to demonstrate the effect of low shear stress on pyroptosis and the underlying mechanism. Human umbilical vein endothelial cells (HUVECs) stimulated by undisturbed shear stress (5 dynes/cm² ) were the experimental group while HUVECs without shear stress treatment were the control group in our experiments. We observed that shear stress can suppress mechanosensitive miR-181b-5p expression, accompanying the elevated expression of NLRP3 inflammasome-dependent pyroptosis. Introduction of miR-181b-5p could alleviate NLRP3 inflammasome-dependent pyroptosis. Luciferase assay showed specific binding of miR-181b-5p to the 3'-UTR of signal transduction and transcriptional activation factor 3 (STAT-3) gene. Inhibition of STAT-3 gene expression at the posttranscriptional level results in the alleviation of NLRP3 inflammasome-dependent pyroptosis. Besides, the silencing of STAT-3 reduced anti-miR-181b-5p-mediated HUVEC pyroptosis via regulating NLRP3 inflammasome activation. Given the role of mechanosensitive miR-181b-5p and STAT-3 in the shear stress-induced pyroptosis, regulation of their expression levels may be a promising strategy to control AS.

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.

Novel HSP90-PI3K Dual Inhibitor Suppresses Melanoma Cell Proliferation by Interfering with HSP90-EGFR Interaction and Downstream Signaling Pathways

Melanoma is the deadliest form of skin cancer, and its incidence has continuously increased over the past 20 years. Therefore, the discovery of a novel targeted therapeutic strategy for melanoma is urgently needed. In our study, MTT-based cell proliferation assay, cell cycle, and apoptosis assays through flow cytometry, protein immunoblotting, protein immunoprecipitation, designing of melanoma xenograft models, and immunohistochemical/immunofluorescent assays were carried out to determine the detailed molecular mechanisms of a novel HSP90-PI3K dual inhibitor. Our compound, named DHP1808, was found to suppress A375 cell proliferation through apoptosis induction by activating the Fas/FasL signaling pathway; it also induced cell-cycle arrest and inhibited the cell migration and invasion of A375 cells by interfering with Hsp90-EGFR interactions and downstream signaling pathways. Our results indicate that DHP1808 could be a promising lead compound for the Hsp90/PI3K dual inhibitor.

The therapeutic effect of dexmedetomidine on protection from renal failure via inhibiting KDM5A in lipopolysaccharide-induced sepsis of mice

BACKGROUND

Sepsis is an inflammatory response undergoing the complicate pathophysiological changes for host defense against pathogens. Previous studies suggested that dexmedetomidine (DEX) was served to controlling the over-reactive inflammatory effects to protect from the sepsis-induced organ failure via modulating histone methylation. However, the genome-wide changes of histone methylations upon DEX for sepsis treatment were poorly explored.

MATERIALS AND METHODS

The acute kidney injury (AKI) mouse model were induced by lipopolysaccharide (LPS). DEX and KDM5 (H3K4 demethylases) inhibitors were used to add additionally. H3K4me3 antibody was used to conduct the ChIP-seq assay in renal cortex tissues.

RESULTS

We observed that the overall H3K4me3 levels were obviously declined in AKI group compared to the normal control. We further observed that the therapeutic effect of DEX was basically equal with CPI-455 and KDM5A-IN-1 but better than PBIT. The overall H3K4me3 level was reduced in AKI group compared to DEX (p = 0.008), and KDM5A-IN-1 groups (p = 0.022). The H3K4me3 enrichment of the multiple genes associated with inflammatory cytokines such as TNF-α, NOS2 and CCL2 increased in AKI model, but decreased upon DEX or KDM5A-IN-1 treatment. Consistently, transcription and protein levels of genes such as TLR4, MYD88, MTA1, PTGS2, CASP3 associated with NF-κB signaling pathway were all compromising after treated with DEX or KDM5A-IN-1 groups compared to AKI group.

CONCLUSION

Taken together, our data determined that DEX could attenuate AKI through KDM5A inhibition in sepsis.

Epigenetic Modification in Macrophages: A Promising Target for Tumor and Inflammation-associated Disease Therapy

Macrophages are essential for supporting tissue homeostasis, regulating immune response, and promoting tumor progression. Due to its heterogeneity, macrophages have different phenotypes and functions in various tissues and diseases. It is becoming clear that epigenetic modification playing an essential role in determining the biological behavior of cells. In particular, changes of DNA methylation, histone methylation and acetylation regulated by the corresponding epigenetic enzymes, can directly control macrophages differentiation and change their functions under different conditions. In addition, epigenetic enzymes also have become anti-tumor targets, such as HDAC, LSD1, DNMT, and so on. In this review, we presented an overview of the latest progress in the study of macrophages phenotype and function regulated by epigenetic modifications, including DNA methylation and histone modifications, to better understand how epigenetic modification controls macrophages phenotype and function in inflammation-associated diseases, and the application prospect in anti-tumor.

Role of histone acetylation and DNA methylation in hepatic inflammatory response

In recent years, many studies have confirmed that the interaction between histone acetylation and DNA methylation plays an important role in the process of hepatic inflammatory response. This article systematically introduces the role of histone acetylation and DNA methylation in the liver inflammatory response, as well as the current research status, existing problems, and corresponding solutions, with an aim to help find new potential intervention strategies for the control of hepatic inflammatory response.

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.

Modulations of Histone Deacetylase 2 Offer a Protective Effect through the Mitochondrial Apoptosis Pathway in Acute Liver Failure

The purpose of this study was to investigate the modulation of histone deacetylase 2 (HDAC2) on mitochondrial apoptosis in acute liver failure (ALF). The cellular model was established with LO2 cells stimulated by tumor necrosis factor alpha (TNF-α)/D-galactosamine (D-gal). Rats were administrated by lipopolysaccharide (LPS)/D-gal as animal model. The cell and animal models were then treated by HDAC2 inhibitor CAY10683. HDAC2 was regulated up or down by lentiviral vector transfection in LO2 cells. The mRNA levels of bcl2 and bax were detected by real-time PCR. The protein levels of HDAC2, bcl2, bax, cytochrome c (cyt c) in mitochondrion and cytosol, apoptosis protease activating factor 1 (apaf1), caspase 3, cleaved-caspase 3, caspase 9, cleaved-caspase 9, acetylated histone H3 (AH3), and histone H3 (H3) were assayed by western blot. Apoptosis was detected by flow cytometry. The serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), and total bilirubin (TBIL) levels were also assayed. The openness degree of the mitochondrial permeability transition pore (MPTP) was detected by ultraviolet spectrophotometry. The apoptosis of hepatocytes in liver tissues was determined by tunnel staining. The liver tissue pathology was detected by hematoxylin eosin (HE) staining. The ultrastructure of liver tissue was observed by electron microscopy. Compared with cell and rat model groups, the bax mRNA level was decreased, and bcl2 mRNA was increased in the CAY10683 treatment group. The protein levels of HDAC2, bax, cyt c in cytosol, apaf1, cleaved-caspase 3, and cleaved-caspase 9 were decreased, and the apoptosis rate was decreased (P < 0.05), whereas the protein level of bcl2 and cyt c in the mitochondrion was elevated (P < 0.05) in the CAY10683 treatment group. In the HDAC2 down- or upregulated LO2 cells, the mitochondrial apoptosis pathway was inhibited or activated, respectively. After being treated with TNF-α/D-gal in HDAC2 down- or upregulated LO2 cells, the mitochondrial apoptosis pathway was further suppressed or activated, respectively. The MPTP value was elevated in CAY10683-treated groups compared with the rat model group (P < 0.05). Liver tissue pathological damage and apoptotic index in the CAY10683-treated group were significantly reduced. In addition, AH3 was elevated in both cell and animal model groups (P < 0.05). Downregulated or overexpressed HDAC2 could accordingly increase or decrease the AH3 level, and TNF-α/D-gal could enhance the acetylation effect. These results suggested that modulations of histone deacetylase 2 offer a protective effect through the mitochondrial apoptosis pathway in acute liver failure.

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.