HDAC1 and HDAC2 regulate anti-inflammatory effects of anesthetic isoflurane in human monocytes

SDS3 regulates microglial inflammation by modulating the expression of the upstream kinase ASK1 in the p38 MAPK signaling pathway

BACKGROUND

Microglia, the main innate immune cells in the central nervous system, are key drivers of neuroinflammation, which plays a crucial role in the pathogenesis of neurodegenerative diseases. The Sin3/histone deacetylase (HDAC) complex, a highly conserved multiprotein co-repressor complex, primarily performs transcriptional repression via deacetylase activity; however, the function of SDS3, which maintains the integrity of the complex, in microglia remains unclear.

METHODS

To uncover the regulatory role of the transcriptional co-repressor SDS3 in microglial inflammation, we used chromatin immunoprecipitation to identify SDS3 target genes and combined with transcriptomics and proteomics analysis to explore expression changes in cells following SDS3 knocking down. Subsequently, we validated our findings through experimental assays.

RESULTS

Our analysis revealed that SDS3 modulates the expression of the upstream kinase ASK1 of the p38 MAPK pathway, thus regulating the activation of signaling pathways and ultimately influencing inflammation.

CONCLUSIONS

Our findings provide important evidence of the contributions of SDS3 toward microglial inflammation and offer new insights into the regulatory mechanisms of microglial inflammatory responses.

Interplay of human gastrointestinal microbiota metabolites: Short-chain fatty acids and their correlation with Parkinson's disease

Short-chain fatty acids (SCFAs) are, the metabolic byproducts of intestinal microbiota that, are generated through anaerobic fermentation of undigested dietary fibers. SCFAs play a pivotal role in numerous physiological functions within the human body, including maintaining intestinal mucosal health, modulating immune functions, and regulating energy metabolism. In recent years, extensive research evidence has indicated that SCFAs are significantly involved in the onset and progression of Parkinson disease (PD). However, the precise mechanisms remain elusive. This review comprehensively summarizes the progress in understanding how SCFAs impact PD pathogenesis and the underlying mechanisms. Primarily, we delve into the synthesis, metabolism, and signal transduction of SCFAs within the human body. Subsequently, an analysis of SCFA levels in patients with PD is presented. Furthermore, we expound upon the mechanisms through which SCFAs induce inflammatory responses, oxidative stress, abnormal aggregation of alpha-synuclein, and the intricacies of the gut-brain axis. Finally, we provide a critical analysis and explore the potential therapeutic role of SCFAs as promising targets for treating PD.

Epigenetic Regulation of Leukocyte Inflammatory Mediator Production Dictates Staphylococcus aureus Craniotomy Infection Outcome

Staphylococcus aureus is a common cause of surgical-site infections, including those arising after craniotomy, which is performed to access the brain for the treatment of tumors, epilepsy, or hemorrhage. Craniotomy infection is characterized by complex spatial and temporal dynamics of leukocyte recruitment and microglial activation. We recently identified unique transcriptional profiles of these immune populations during S. aureus craniotomy infection. Epigenetic processes allow rapid and reversible control over gene transcription; however, little is known about how epigenetic pathways influence immunity to live S. aureus. An epigenetic compound library screen identified bromodomain and extraterminal domain-containing (BET) proteins and histone deacetylases (HDACs) as critical for regulating TNF, IL-6, IL-10, and CCL2 production by primary mouse microglia, macrophages, neutrophils, and granulocytic myeloid-derived suppressor cells in response to live S. aureus. Class I HDACs (c1HDACs) were increased in these cell types in vitro and in vivo during acute disease in a mouse model of S. aureus craniotomy infection. However, substantial reductions in c1HDACs were observed during chronic infection, highlighting temporal regulation and the importance of the tissue microenvironment for dictating c1HDAC expression. Microparticle delivery of HDAC and BET inhibitors in vivo caused widespread decreases in inflammatory mediator production, which significantly increased bacterial burden in the brain, galea, and bone flap. These findings identify histone acetylation as an important mechanism for regulating cytokine and chemokine production across diverse immune cell lineages that is critical for bacterial containment. Accordingly, aberrant epigenetic regulation may be important for promoting S. aureus persistence during craniotomy infection.

Halogenated anesthetics vs intravenous hypnotics for short and long term sedation in the intensive care unit: A meta-analysis

OBJECTIVE

To comprehensively assess peer-reviewed studies using volatile (VA) or intravenous (i/v) anesthetics for sedation in intensive care units (ICUs), with the hypothesis that the type of sedation may have an impact on survival and other clinically relevant outcomes.

DESIGN

Systematic review and meta-analysis of randomized and non-randomized trials.

SETTING

ICUs.

PARTICIPANTS

Critically ill and postoperative patients.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Studies comparing VA versus i/v anesthetics used in the ICU settings were independently systematically searched. Finally, 15 studies (1520 patients of predominantly surgical profile needed VA sedation for less than 96h) were included. VA had no impact on all-cause mortality (very low quality of evidence, Odds Ratio=0.82 [0.60-1.12], p=0.20). However, VA were associated with a reduction in duration of mechanical ventilation (p=0.03) and increase in ventilator-free days (p<0.001). VA also reduced postoperative levels of cardiac troponin (24h), time to extubation (p<0.001) and awakening (p=0.04).

CONCLUSIONS

In this meta-analysis, volatile sedation vs propofol caused the increase in ventilator-free days, the reduction in the duration of mechanical ventilation, time to extubation and the troponin release in medical or surgical ICU patients, while in surgical ICU patients the time to awakening was shortened.

Isoflurane impairs GluN2B-containing NMDA receptors trafficking and cognition via decreasing histone acetylation and EphB2 expression in aged hippocampal neurons

Perioperative neurocognitive disorders (PND) is a common complication that occurs among elderly patients in the perioperative course. Current clinical evidence has shown that isoflurane exposure could cause cognitive decline, but the exact molecular mechanisms remain unclear. As both NMDARs-dependent synaptic plasticity and histone acetylation play vital roles in processing learning and memory, we postulated that these alternations might occur in the isoflurane-associated PND. Here, we found that isoflurane impaired fear memory in aged mice, decreased GluN2B-containing NMDA receptors phosphorylation and trafficking, as well as the expression of EphB2, a key regulator of synaptic localization of NMDA receptors. We also identified that isoflurane could increase the expression of HDAC2, which was significantly enriched at the ephb2 gene promoter and regulated the transcription of ephb2. Furthermore, we showed that suberoylanilide hydroxamic acid (SAHA), a nonselective HDAC inhibitor or knocking-down HDAC2 rescued the cognitive dysfunction in isoflurane-treated aged mice via increasing acetylation of H3Ac, expression of EphB2 and promoting NMDA receptor trafficking. Collectively, our study highlighted the crucial role of histone posttranslational modifications for EphB2-GluN2B signals in isoflurane-associated PND, and modulating HDAC2 might be a new therapeutic strategy for isoflurane-associated PND.

Epigenetic Mechanisms of Postoperative Cognitive Impairment Induced by Anesthesia and Neuroinflammation

Cognitive impairment after surgery is a common problem, affects mainly the elderly, and can be divided into postoperative delirium and postoperative cognitive dysfunction. Both phenomena are accompanied by neuroinflammation; however, the precise molecular mechanisms underlying cognitive impairment after anesthesia are not yet fully understood. Anesthesiological drugs can have a longer-term influence on protein transcription, thus, epigenetics is a possible mechanism that impacts on cognitive function. Epigenetic mechanisms may be responsible for long-lasting effects and may implicate novel therapeutic approaches. Hence, we here summarize the existing literature connecting postoperative cognitive impairment to anesthesia. It becomes clear that anesthetics alter the expression of DNA and histone modifying enzymes, which, in turn, affect epigenetic markers, such as methylation, histone acetylation and histone methylation on inflammatory genes (e.g., TNF-alpha, IL-6 or IL1 beta) and genes which are responsible for neuronal development (such as brain-derived neurotrophic factor). Neuroinflammation is generally increased after anesthesia and neuronal growth decreased. All these changes can induce cognitive impairment. The inhibition of histone deacetylase especially alleviates cognitive impairment after surgery and might be a novel therapeutic option for treatment. However, further research with human subjects is necessary because most findings are from animal models.

The emerging roles of HDACs and their therapeutic implications in cancer

Deregulation of protein post-translational modifications is intensively involved in the etiology of diseases, including degenerative diseases, inflammatory injuries, and cancers. Acetylation is one of the most common post-translational modifications of proteins, and the acetylation levels are controlled by two mutually antagonistic enzyme families, histone acetyl transferases (HATs) and histone deacetylases (HDACs). HATs loosen the chromatin structure by neutralizing the positive charge of lysine residues of histones; whereas HDACs deacetylate certain histones, thus inhibiting gene transcription. Compared with HATs, HDACs have been more intensively studied, particularly regarding their clinical significance. HDACs extensively participate in the regulation of proliferation, migration, angiogenesis, immune escape, and therapeutic resistance of cancer cells, thus emerging as critical targets for clinical cancer therapy. Compared to HATs, inhibitors of HDAC have been clinically used for cancer treatment. Here, we enumerate and integratethe mechanisms of HDAC family members in tumorigenesis and cancer progression, and address the new and exciting therapeutic implications of single or combined HDAC inhibitor (HDACi) treatment.

Cdyl Deficiency Brakes Neuronal Excitability and Nociception through Promoting Kcnb1 Transcription in Peripheral Sensory Neurons

Epigenetic modifications are involved in the onset, development, and maintenance of pain; however, the precise epigenetic mechanism underlying pain regulation remains elusive. Here it is reported that the epigenetic factor chromodomain Y-like (CDYL) is crucial for pain processing. Selective knockout of CDYL in sensory neurons results in decreased neuronal excitability and nociception. Moreover, CDYL facilitates histone 3 lysine 27 trimethylation (H3K27me3) deposition at the Kcnb1 intron region thus silencing voltage-gated potassium channel (Kv ) subfamily member Kv 2.1 transcription. Loss function of CDYL enhances total Kv and Kv 2.1 current density in dorsal root ganglia and knockdown of Kv 2.1 reverses the pain-related phenotypes of Cdyl deficiency mice. Furthermore, focal administration of a novel potent CDYL antagonist blunts nociception and attenuates neuropathic pain. These findings reveal that CDYL is a critical regulator of pain sensation and shed light on the development of novel analgesics targeting epigenetic mechanisms.

Role of Histone Deacetylases in Monocyte Function in Health and Chronic Inflammatory Diseases

Histone deacetylases (HDACs) are a family of 18 members that participate in the epigenetic regulation of gene expression. In addition to histones, some HDACs also deacetylate transcription factors and specific cytoplasmic proteins.Monocytes, as part of the innate immune system, maintain tissue homeostasis and help fight infections and cancer. In these cells, HDACs are involved in multiple processes including proliferation, migration, differentiation, inflammatory response, infections, and tumorigenesis. Here, a systematic description of the role that most HDACs play in these functions is reviewed. Specifically, some HDACs induce a pro-inflammatory response and play major roles in host defense. Conversely, other HDACs reprogram monocytes and macrophages towards an immunosuppressive phenotype. The right balance between both types helps monocytes to respond correctly to the different physiological/pathological stimuli. However, aberrant expressions or activities of specific HDACs are associated with autoimmune diseases along with other chronic inflammatory diseases, infections, or cancer.This paper critically reviews the interesting and extensive knowledge regarding the role of some HDACs in these pathologies. It also shows that as yet, very little progress has been made toward the goal of finding effective HDAC-targeted therapies. However, given their obvious potential, we conclude that it is worth the effort to develop monocyte-specific drugs that selectively target HDAC subtypes with the aim of finding effective treatments for diseases in which our innate immune system is involved.

NLRP3 Inflammasome: A Potential Target in Isoflurane Pretreatment Alleviates Stroke-Induced Retinal Injury in Diabetes

Ischemic stroke remains a devastating disease which is the leading cause of death worldwide. Visual impairment after stroke is a common complication which may lead to vision loss, greatly impacting life quality of patients. While ischemic stroke is traditionally characterized by a blockage of blood flow to the brain, this may coincide with reduced blood flow to the eye, resulting in retinal ischemia and leading to visual impairment. Diabetes increases the risk of ischemic stroke and induces diabetic retinopathy; the latter may be more sensitive to the ischemic retinal injury. In diabetic status, the underlying mechanism in stroke-induced retinal injury has not been fully clarified. The NLR pyrin domain containing 3 (NLRP3) inflammasome is an important activator of inflammation, which may play a critical role in catalyzing and forming certain pro-inflammatory cytokines in both cerebral and retinal ischemia. Isoflurane has been demonstrated to inhibit the activation of the NLRP3 inflammasome and show neuroprotective effects. In this study, we established a diabetic mouse model and performed the middle cerebral artery occlusion procedure to induce ischemic stroke. Our results revealed that cerebral ischemia-induced retinal injury in the diabetic model. Isoflurane pretreatment alleviated the cerebral and retinal injury after ischemic stroke. Of note, isoflurane pretreatment inhibited the NLRP3 inflammasome activation in the retina, indicating that isoflurane pretreatment may provide substantial retinal protection in stroke-induced retinal injury in diabetes.

Downregulation of metallothionein-2 contributes to oxaliplatin-induced neuropathic pain

Background

We previously reported a correlation between small doses of oxaliplatin penetrating onto the spinal cord and acute pain after chemotherapy. Here, we propose that MT2 within the spinal dorsal horns participates in the development of oxaliplatin-induced neuropathic pain and may be a pharmacological target for the prevention and treatment of chemotherapy-induced peripheral neuropathy (CIPN).

Methods

The rat model of CIPN was established by 5 consecutive injections of oxaliplatin (0.4 mg/100 g/day). Genetic restoration of neuron-specific metallothionein-2 was implemented 21 days before oxaliplatin treatment, and also, genetic inhibition by metallothionein-2 siRNA was performed. Mechanical allodynia and locomotor activity were assayed. Cell-specific expression of metallothionein-2, the mRNA levels of pro-inflammatory cytokines, nuclear translocation of NF-κB, the protein levels of expression of IκB-α, and interaction between IκB-α and P65 were evaluated in the spinal dorsal horns. Also, in vitro interaction of sequentially deleted IκB-α promoter with metallothionein-2 was used to assess the signal transduction mechanism.

Results

We found that oxaliplatin induced downregulation of metallothionein-2 in rat spinal cord neurons. By contrast, genetic restoration of metallothionein-2 in the spinal dorsal horn neuron blocked and reversed neuropathic pain in oxaliplatin-treated rats of both sexes, whereas genetic inhibition of metallothionein-2 triggered neuropathic pain in normal rats. Overall locomotor activity was not impaired after the genetic alterations of metallothionein-2. At the molecular level, metallothionein-2 modulated oxaliplatin-induced neuroinflammation, activation of NF-κB, and inactive transcriptional expression of IκB-α promoter, and these processes could be blocked by genetic restoration of metallothionein-2 in the spinal dorsal horn neurons.

Conclusions

Metallothionein-2 is a potential target for the prevention and treatment of CIPN. A reduction of NF-κB activation and inflammatory responses by enhancing the transcription of IκB-α promoter is proposed in the mechanism.

Expression of histone deacetylase 2 in tracheal stenosis models and its relationship with tracheal granulation tissue proliferation

The current treatments for benign tracheal stenosis are inefficient. The present study examined the expression of histone deacetylase 2 (HDAC2) in different tracheal stenosis models and explored its association with the proliferation of tracheal granulation tissue and its ability to constitute a potential therapy for tracheal stenosis. Animal tracheal stenosis models were established, as indicated by hematoxylin and eosin (H&E) staining. A total of 24 New Zealand White rabbits were randomly divided into control, erythromycin, budesonide and vorinostat groups. Stenotic tracheal tissues were collected on day 11 after drug administration for 10 days. The degree of tracheal stenosis in each group was calculated, and pathological alterations were observed using H&E staining. The mRNA expression of HDAC2, interleukin-8 (IL-8), transforming growth factor-β1 (TGF-β1) and vascular endothelial growth factor (VEGF) was examined via reverse transcription-quantitative PCR. The protein expression of HDAC2 was examined via immunofluorescence, while the expression of type I and type III collagen was assessed using immunohistochemistry. The results of the present study demonstrated that tracheal epithelial hyperplasia in the erythromycin group was improved, the degree of hyperplasia being the lowest among all groups, and tracheal stenosis was reduced compared with the control group. In the vorinostat group, tracheal epithelial tissue hyperplasia was aggravated and stenosis was increased. The HDAC2 mRNA and protein levels were increased and decreased in the erythromycin and vorinostat groups, respectively. In contrast, the IL-8 mRNA expression levels were decreased and increased in the erythromycin and vorinostat groups, respectively. TGF-β1, VEGF, type I and type III collagen expression was decreased in the erythromycin group, while TGF-β1, VEGF and type III collagen expression was increased in the vorinostat group. Compared with the control, the budesonide group did not exhibit any alterations in all of the indicators examined, including TGF-β1, VEGF, IL-8, HDAC2 and collagen. Erythromycin treatment upregulated the expression of HDAC2, inhibited the inflammatory responses and reduced the proliferation of tracheal granulation tissue. In contrast, vorinostat treatment downregulated HDAC2 expression, promoted the inflammatory responses and increased the proliferation of tracheal granulation tissue. These results suggest that regulating HDAC2 may be used as a potential treatment for benign tracheal stenosis.

HDAC1 regulates the chemosensitivity of laryngeal carcinoma cells via modulation of interleukin-8 expression

Chemotherapies such as 5-fluorouracil (5-FU) and cisplatin (CDDP) have been widely used to treat laryngeal squamous cell carcinoma (LSCC), the second most common head and neck squamous cell carcinoma. However, chemoresistance seriously impairs chemotherapeutic efficacy. Our present study reveals that 5-FU and CDDP treatment increase the expression of histone deacetylase 1 (HDAC1) in LSCC cells. Consistently, increased levels of HDAC1 are observed in chemoresistant cells. Knockdown of HDAC1 significantly restores the sensitivity of LSCC cells, as HDAC1 increases the expression of interleukin-8 (IL-8), which is essential for LSCC chemoresistance. Mechanistically, HDAC1 directly initiates the transcription of IL-8 though binding to its promoter. Simultaneously, si-HDAC1 increases the levels of miR-93, which binds to the 3'UTR of IL-8 mRNA to trigger its degradation. In summary, the HDAC1/IL-8 axis can confer chemotherapeutic resistance to LSCC cells.

ATF4-mediated histone deacetylase HDAC1 promotes the progression of acute pancreatitis

Acute pancreatitis (AP), an acute inflammatory process, can be difficult to diagnose. Activating transcription factor 4 (ATF4) has been reported to participate in the pathogenesis of AP. Additionally, histone deacetylases (HDACs) are shown to be closely related to the development of a variety of diseases, including inflammation disease. In our study, we tried to highlight the role of ATF4 in AP through regulation of HDAC1. Firstly, we validated the effect of ATF4 on pancreatic acinar cell proliferation, apoptosis, and inflammation through in vitro experiments on cellular models of caerulein-induced AP. Next, we examined the correlation between ATF4 and HDAC1, and between HDAC1 with neutral endopeptidase (NEP) and kruppel-like factor 4 (KLF4). Finally, the regulatory role of ATF4 in AP was further assessed by determination of pathological conditions, biochemical indicators and inflammation through in vivo experiments on caerulein-induced AP mouse models. After AP induction, highly expressed ATF4 was observed, and silencing ATF4 could promote pancreatic acinar cell proliferation and inhibit apoptosis. ATF4 could bind to the HDAC1 promoter and upregulate its expression in AP. Moreover, HDAC1 could increase KLF4 expression by inhibiting NEP expression. Functionally, silencing ATF4 could suppress AP through regulation of NEP-mediated KLF4 via downregulation of HDAC1. Above all, our study uncovered the promotive role of ATF4 in AP through upregulation of HDAC1.

Isoflurane Regulates Proliferation, Apoptosis, and Inflammatory Response of Lipopolysaccharide-Induced Human Astrocyte through the miR-206/BDNF Axis

Objective. To investigate the effect of isoflurane (ISO) on the proliferation, apoptosis, and inflammatory response of lipopolysaccharide- (LPS-) induced normal human astrocytes (NHAs) by regulating the miR-206/BDNF axis. Methods. NHA proliferation activity was measured by MTT; NHA apoptotic rates were measured by Annexin V-FITC/PI; western blotting was used to measure the BDNF expression; ELISA was used to measure the IL-6, IL-1β, and TNF-α expression in NHAs; qPCR was used to measure the expressions of miRNAs that are related to NHAs proliferation and apoptosis; dual-luciferase reporter was constructed to validate the targeting relationship between miR-206 and BDNF. Results. LPS increased the proliferation activity and decreased the apoptosis rate of NHAs which were effectively reversed by the ISO (p<0.05); LPS significantly inhibited the expression of miRNAs related to proliferation and apoptosis in NHAs (p<0.05, p<0.01), whereas ISO significantly increased the expression of miR-206 (p<0.01) by downregulating the expression of BDNF, thus inhibiting NHA proliferation and inflammatory response and enhancing apoptosis. Conclusion. ISO can inhibit the expression of BDNF by upregulating the expression of miR-206, thereby inhibiting the proliferation and inflammatory response of NHAs and promoting its apoptosis.