Procainamide Inhibits DNA Methylation and Alleviates Multiple Organ Dysfunction in Rats with Endotoxic Shock

Metformin attenuated sepsis-related liver injury by modulating the DNA methylation and hydroxymethylation landscape

Sepsis-associated liver injury (SLI) is a common complication of sepsis, for which effective therapeutic strategies are lacking. DNA methylation and hydroxymethylation play crucial roles in the regulation of gene expression. This study investigated the effects of metformin on the DNA methylation landscape in a rat model of cecal ligation and puncture (CLP)-induced SLI. Reduced representation bisulfite sequencing (RRBS) and oxidative RRBS (ox-RRBS) were used to assess global DNA methylation and hydroxymethylation patterns in the liver tissues. The results showed that CLP-induced SLI was associated with global DNA hypomethylation and hyperhydroxymethylation, which were partially reversed by metformin treatment. The expression levels of DNA methyltransferases and ten-eleven translocation 2 (TET2) were elevated in the CLP group and were modulated by metformin. Functional enrichment analysis of differentially methylated and hydroxymethylated genes revealed their involvement in oxidative phosphorylation and metabolic pathways. Furthermore, integration of DNA methylation, hydroxymethylation, and transcriptome data identified two genes, A1cf and Atxn7l1, that exhibited increased methylation and decreased expression in CLP, which were reversed by metformin treatment. These findings provide novel insights into the epigenetic mechanisms underlying SLI and suggest that metformin exerts hepatoprotective effects by modulating DNA methylation and hydroxymethylation.

DNA dioxygenase TET2 deficiency aggravates sepsis-induced acute lung injury by targeting ITGA10 via the PI3K/AKT signaling pathway

BACKGROUND

Sepsis-induced acute lung injury (ALI) is a clinical condition with high morbidity and mortality, and impaired endothelial function is the main pathological characteristic. As a member of DNA demethylases, ten-eleven translocation protein 2 (TET2) is involved in a variety of biological processes. However, the role of TET2 in endothelial dysfunction of sepsis-induced ALI remains unclear.

METHODS

We used cecal ligation and puncture (CLP) to establish a sepsis-induced acute lung injury mouse model and screened out Tet2 from TET family proteins. The results suggested that Tet2 was obviously declined. We used lipopolysaccharide (LPS) to stimulate human pulmonary microvascular endothelial cells (HPMECs) as an in vitro model, and we found the expression of TET2 was also decreased. Then we used small interfering RNAs and adenovirus to knockdown or overexpress TET2 to investigate the effect of TET2 on the function of HPMECs. The changes in sepsis-induced ALI symptoms were also analyzed in Tet2-deficient mice generated by adeno-associated virus 6 (AAV6). Next, RNA sequencing and KEGG analysis were used to find the TET2-regulated downstream target genes and signaling pathways under LPS stimulation. Finally, the rescue experiments were performed to analyze the role of target genes and signaling pathways modulated by TET2 in LPS-treated HPMECs.

RESULTS

TET2 and 5-hmC levels were significantly decreased in both in vitro and in vivo models of sepsis-induced ALI. TET2 knockdown exacerbated the dysfunction and apoptosis of HPMECs induced by LPS. Conversely, TET2 overexpression significantly alleviated these dysfunctions and reduced apoptosis. Meanwhile, the lung injury of Tet2-deficient mice was aggravated by increased inflammation and apoptosis. RNA sequencing and subsequent experiments showed that TET2 overexpression could increase the expression of Integrin α10 (ITGA10) by reducing the methylation level of ITGA10 promoter. This, in turn, activated the PI3K-AKT signaling pathway. Knocking down ITGA10 weakened the beneficial effects of TET2 overexpression in LPS-stimulated endothelial cells.

CONCLUSIONS

In our study, we demonstrated that TET2 deficiency aggravates endothelial cell dysfunction and promotes acute lung injury by targeting ITGA10 via the PI3K-AKT pathway. These findings indicate that TET2 may be a promising therapeutic target for treating sepsis-induced ALI.

Epigenome-wide DNA methylation profiling in septic and non-septic patients with similar infections: potential use as sepsis biomarkers

Introduction

Sepsis is a life-threatening condition caused by a dysregulated immune response to infection, leading to organ failure. Despite its significant global burden, the underlying mechanisms of immune dysfunction in sepsis remain incompletely understood. This study explores the role of DNA methylation in white blood cells in sepsis pathogenesis.

Methods

A prospective case-control study was conducted to compare DNA methylation profiles between patients with community-acquired sepsis and matched controls who had similar infections but did not develop sepsis. Whole blood samples from these patients were analyzed using the Infinium MethylationEPIC v2.0 kit, enabling genome-wide methylation analysis. Selected genes with differential methylation were validated by pyrosequencing.

Results

Significant differential DNA methylation patterns were identified between septic and non-septic individuals uising. Our results suggest that DNA methylation changes are closely linked to the pathophysiological processes of sepsis, influencing immune cell activation, inflammation, and organ dysfunction. The most prominent findings include the hypomethylation of immune-related genes (SERPINA1, AZU1, MPO, and SLX4), which were strongly correlated with clinical severity and inflammatory markers such as SOFA scores and PCT levels. Correlation analyses demonstrated significant associations between the methylation levels of these genes and clinical severity markers, such as SOFA score and PCT levels. Notably, SLX4 hypomethylation showed the highest predictive value for poor prognosis (AUC 0.821), while SERPINA1 hypomethylation exhibited strong diagnostic potential for sepsis (AUC 0.858).

Discussion

Our results underscore the potential of DNA methylation changes, particularly in immune-related genes, to enhance the early detection of sepsis and to stratify patients based on severity. Future research should explore the therapeutic implications of these epigenetic alterations in sepsis care.

Factors affecting neutrophil functions during sepsis: human microbiome and epigenetics

Sepsis is a severe disease that occurs when the body's immune system reacts excessively to infection. The body's response, which includes an intense antibacterial reaction, can damage its tissues and organs. Neutrophils are the major components of white blood cells in circulation, play a vital role in innate immunity while fighting against infections, and are considered a feature determining sepsis classification. There is a plethora of basic research detailing neutrophil functioning, among which, the study of neutrophil extracellular traps is providing novel insights into mechanisms and treatments of sepsis. This review explores their functions, dysfunctions, and influences in the context of sepsis. The interplay between neutrophils and the human microbiome and the impact of DNA methylation on neutrophil function in sepsis are crucial areas of study. The interaction between neutrophils and the human microbiome is complex, particularly in the context of sepsis, where dysbiosis may occur. We highlight the importance of deciphering neutrophils' functional alterations and their epigenetic features in sepsis because it is critical for defining sepsis endotypes and opening up the possibility for novel diagnostic methods and therapy. Specifically, epigenetic signatures are pivotal since they will provide a novel implication for a sepsis diagnostic method when used in combination with the cell-free DNA. Research is exploring how specific patterns of DNA methylation in neutrophils, detectable in cell-free DNA, could serve as biomarkers for the early detection of sepsis.

Epigenetic Mechanisms in Sepsis-Associated Acute Kidney Injury

Sepsis, the dysregulated immune response of the host to infections, leads to numerous complications, including multiple organ dysfunction with sepsis-associated acute kidney injury (SA-AKI) being a frequent complication associated with increased risk of mortality and the progression toward chronic kidney disease (CKD). Several mechanisms have been widely investigated in understanding the complex pathophysiology of SA-AKI, including hemodynamic alterations, inflammation, oxidative stress, and direct cellular injury driven by pathogens or cell-derived products (pathogen-associated molecular patterns and damage-associated molecular patterns). Despite advancements in the management of septic patients, the prognosis of SA-AKI patients remains significantly poor and is associated with high in-hospital mortality and adverse long-term outcomes. Therefore, recent research has focused on the early identification of specific SA-AKI endotypes and subphenotypes through epigenetic analysis and the use of potential biomarkers, either alone or in combination with clinical data, to improve prognosis. Epigenetic regulation, such as DNA methylation, histone modifications, and noncoding RNA modulation, is crucial in modulating gene expression in response to stress and renal injury in SA-AKI. At the same time, these modifications are dynamic and reversible processes that can alter gene expression in several pathways implicated in the context of SA-AKI, including inflammation, immune response, and tolerance status. In addition, specific epigenetic modifications may exacerbate renal damage by causing persistent inflammation or cellular metabolic reprogramming, leading to progression toward CKD. This review aims to provide a comprehensive understanding of the epigenetic characteristics that define SA-AKI, also exploring targeted therapies that can improve patient outcomes and limit the chronic progression of this syndrome.

Research progress in the pathogenesis of sepsis-associated encephalopathy

Sepsis is a syndrome that causes dysfunction of multiple organs due to the host's uncontrolled response to infection and is a significant contributor to morbidity and mortality in intensive care units worldwide. Surviving patients are often left with acute brain injury and long-term cognitive impairment, known as sepsis-associated encephalopathy (SAE). In recent years, researchers have directed their focus towards the pathogenesis of SAE. However, due to the complexity of its development, there remains a lack of effective treatment measures that arise as a serious issue affecting the prognosis of sepsis patients. Further research on the possible causes of SAE aims to provide clinicians with potential therapeutic targets and help develop targeted prevention strategies. This paper aims to review recent research on the pathogenesis of SAE, in order to enhance our understanding of this syndrome.

Role and mechanism of DNA methylation and its inhibitors in hepatic fibrosis

Liver fibrosis is a repair response to injury caused by various chronic stimuli that continually act on the liver. Among them, the activation of hepatic stellate cells (HSCs) and their transformation into a myofibroblast phenotype is a key event leading to liver fibrosis, however the mechanism has not yet been elucidated. The molecular basis of HSC activation involves changes in the regulation of gene expression without changes in the genome sequence, namely, via epigenetic regulation. DNA methylation is a key focus of epigenetic research, as it affects the expression of fibrosis-related, metabolism-related, and tumor suppressor genes. Increasing studies have shown that DNA methylation is closely related to several physiological and pathological processes including HSC activation and liver fibrosis. This review aimed to discuss the mechanism of DNA methylation in the pathogenesis of liver fibrosis, explore DNA methylation inhibitors as potential therapies for liver fibrosis, and provide new insights on the prevention and clinical treatment of liver fibrosis.

Microvesicle-Mediated Transfer of DNA Methyltransferase Proteins Results in Recipient Cell Immunosuppression

INTRODUCTION

Patients with sepsis exhibit significant, persistent immunologic dysfunction. Evidence supports the hypothesis that epigenetic regulation of key cytokines plays an important role in this dysfunction. In sepsis, circulating microvesicles (MVs) containing elevated levels of DNA methyltransferase (DNMT) mRNA cause gene methylation and silencing in recipient cells. We sought to examine the functional role of MV DNMT proteins in this immunologic dysfunction.

METHODS

In total, 33 patients were enrolled within 24 h of sepsis diagnosis (23 sepsis, 10 critically ill controls). Blood and MVs were collected on days 1, 3, and 5 of sepsis, and protein was isolated from the MVs. Levels of DNMT protein and activity were quantified. MVs were produced in vitro by stimulating naïve monocytes with lipopolysaccharide. Methylation was assessed using bisulfate site-specific qualitative real-time polymerase chain reaction.

RESULTS

The size of MVs in the patients with sepsis decreased from days 1 to 5 compared to the control group. Circulating MVs contained significantly higher levels of DNMT 1 and 3A, protein. We recapitulated the production of these DNMT-containing MVs in vitro by treating monocytes with lipopolysaccharide. We found that exposing naïve monocytes to these MVs resulted in increased promoter methylation of tumor necrosis factor alpha.

CONCLUSIONS

An analysis of the isolated MVs revealed higher levels of DNMT proteins in septic patients than those in nonseptic patients. Exposing naïve monocytes to DNMT-containing MVs produced in vitro resulted in hypermethylation of tumor necrosis factor alpha, a key cytokine implicated in postsepsis immunosuppression. These results suggest that DNMT-containing MVs cause epigenetic changes in recipient cells. This study highlights a novel role for MVs in the immune dysfunction of patients with sepsis.

Personalizing Care for Critically Ill Adults Using Omics: A Concise Review of Potential Clinical Applications

Current guidelines for critically ill patients use broad recommendations to promote uniform protocols for the management of conditions such as acute kidney injury, acute respiratory distress syndrome, and sepsis. Although these guidelines have enabled the substantial improvement of care, mortality for critical illness remains high. Further outcome improvement may require personalizing care for critically ill patients, which involves tailoring management strategies for different patients. However, the current understanding of disease heterogeneity is limited. For critically ill patients, genomics, transcriptomics, proteomics, and metabolomics have illuminated such heterogeneity and unveiled novel biomarkers, giving clinicians new means of diagnosis, prognosis, and monitoring. With further engineering and economic development, omics would then be more accessible and affordable for frontline clinicians. As the knowledge of pathophysiological pathways mature, targeted treatments can then be developed, validated, replicated, and translated into clinical practice.

Construction of m7G subtype classification on heterogeneity of sepsis

Sepsis is a highly heterogeneous disease and a major factor in increasing mortality from infection. N7-Methylguanosine (m7G) is a widely RNA modification in eukaryotes, which involved in regulation of different biological processes. Researchers have found that m7G methylation contributes to a variety of human diseases, but its research in sepsis is still limited. Here, we aim to establish the molecular classification of m7G gene-related sepsis, reveal its heterogeneity and explore the underlying mechanism. We first identified eight m7G related prognostic genes, and identified two different molecular subtypes of sepsis through Consensus Clustering. Among them, the prognosis of C2 subtype is worse than that of C1 subtype. The signal pathways enriched by the two subtypes were analyzed by ssGSEA, and the results showed that the amino acid metabolism activity of C2 subtype was more active than that of C1 subtype. In addition, the difference of immune microenvironment among different subtypes was explored through CIBERSORT algorithm, and the results showed that the contents of macrophages M0 and NK cells activated were significantly increased in C2 subtype, while the content of NK cells resting decreased significantly in C2 subtype. We further explored the relationship between immune regulatory genes and inflammation related genes between C2 subtype and C1 subtype, and found that C2 subtype showed higher expression of immune regulatory genes and inflammation related genes. Finally, we screened the key genes in sepsis by WGCNA analysis, namely NUDT4 and PARN, and verified their expression patterns in sepsis in the datasets GSE131761 and GSE65682. The RT-PCR test further confirmed the increased expression of NUDTA4 in sepsis patients. In conclusion, sepsis clustering based on eight m7G-related genes can well distinguish the heterogeneity of sepsis patients and help guide the personalized treatment of sepsis patients.

Advanced development and mechanism of sepsis-related acute respiratory distress syndrome

The introduction of the Sepsis 3.0 guidelines in 2016 improved our understanding of sepsis diagnosis and therapy. Personalized treatment strategies and nursing methods for sepsis patients are recommended in the "Save Sepsis Campaign" in 2021. However, mortality in sepsis patients remains high. Patients with sepsis-related acute respiratory distress syndrome account for around 30% of them, with fatality rates ranging from 30 to 40%. Pathological specimens from individuals with sepsis-related ARDS frequently demonstrate widespread alveolar damage, and investigations have revealed that pulmonary epithelial and pulmonary endothelial injury is the underlying cause. As a result, the purpose of this work is to evaluate the mechanism and research progress of pulmonary epithelial and pulmonary endothelial damage in sepsis-related ARDS, which may provide new directions for future research, diagnosis, and therapy.

LncRNA SNHG1 promotes sepsis-induced myocardial injury by inhibiting Bcl-2 expression via DNMT1

Myocardial injury is a frequently occurring complication of sepsis. This study aims to investigate the molecular mechanism of long noncoding RNA (lncRNA) small nucleolar RNA host gene 1 (SNHG1)-mediated DNA methyltransferase 1/B-cell lymphoma-2 (DNMT1/Bcl-2) axis in sepsis-induced myocardial injury. Mice and HL-1 cells were treated with lipopolysaccharide (LPS) to establish animal and cellular models simulating sepsis and inflammation. LncRNA SNHG1 was screened out as a differentially expressed lncRNA in sepsis samples through microarray profiling, and the upregulated expression of lncRNA SNHG1 was confirmed in myocardial tissues of LPS-induced septic mice and HL-1 cells. Further experiments suggested that silencing of lncRNA SNHG1 reduced the inflammation and apoptotic rate of LPS-induced HL-1 cells. LncRNA SNHG1 inhibited Bcl-2 expression by recruiting DNMT1 to Bcl-2 promoter region to cause methylation. Inhibition of Bcl-2 promoter methylation reduced the inflammation and apoptotic rate of LPS-induced HL-1 cells. In vivo experiments substantiated that lncRNA SNHG1 silencing alleviated sepsis-induced myocardial injury in mice. Taken together, lncRNA SNHG1 promotes LPS-induced myocardial injury in septic mice by downregulating Bcl-2 through DNMT1-mediated Bcl-2 methylation.

DNMT1/miR-130a/ZEB1 Regulatory Pathway Affects the Inflammatory Response in Lipopolysaccharide-Induced Sepsis

Sepsis is a global health care issue that affects millions of people. DNA methyltransferase I (DNMT1)-mediated DNA methylation is involved in a number of human diseases by affecting many types of cellular progression events. However, the role and underlying molecular mechanism of DNMT1 in development of sepsis remain largely unknown. Lipopolysaccharide (LPS) induced lung fibrosis in the sepsis mouse model, and DNMT1 was upregulated in lung tissues of a sepsis mouse model compared with lung tissues from control mice. Then, this study demonstrated that LPS induced the production of interleukin (IL)-7 and tumor necrosis factor (TNF)-α and promoted DNMT1 expression in primary type II alveolar epithelial cells (AECII cells). Knockdown of DNMT1 inhibited IL-7 and TNF-α secretion in AECII cells exposed to LPS. Further study demonstrated that DNMT1 repressed the expression of miR-130a in AECII cells with or without LPS exposure. Next, this study demonstrated that miR-130a inhibited ZEB1 expression in AECII cells exposed to LPS. Ultimately, this study revealed the role of the DNMT1/miR-130a/ZEB1 regulatory pathway in AECII cells exposed to LPS. Overall, our data revealed that LPS induced the secretion of inflammatory factors by modulating the DNMT1/miR-130a/ZEB1 regulatory pathway in AECII cells, thus providing a novel theoretical basis that might be beneficial for establishment of diagnostic and therapeutic strategies for sepsis.

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.

Hemorrhage and saline resuscitation are associated with epigenetic and proteomic reprogramming in the rat lung

BACKGROUND

Epigenetic changes have been described in trauma patients in the form of histone acetylation events, but whether DNA-methylation occurs remains unknown. We hypothesized that the combination of hemorrhage and saline resuscitation would alter DNA-methylation and associated proteomic profiles in the rat lung.

METHODS

Ten rats were subjected to a pressure-controlled hemorrhage and resuscitation model consisting of hemorrhage to a mean arterial pressure (MAP) of 35mmHg for 90 minutes, followed by saline resuscitation to a MAP >70mmHg for 90 minutes (n=5) or sham (only anesthesia and cannulation). Lungs were harvested and subjected to reduced genome wide DNA-methylation analysis through bisulphite sequencing as well as proteomics analysis. Data was analyzed for differentially methylated regions and associated alterations in proteomic networks through a weighted correlation network analysis (WCNA). Pathway analysis was used to establish biological relevance of findings.

RESULTS

Hemorrhage and saline resuscitation were associated with differential methylation of 353 sites across the genome compared to the sham group. Of these, 30 were localized to gene promoter regions, 31 to exon regions and 87 to intron regions. Network analysis identified an association between hemorrhage/resuscitation and DNA-methylation events located to genes involved in areas of endothelial and immune response signaling. The associated proteomic response was characterized by activations of mRNA processing as well as endothelial Nitric Oxide Synthase (eNOS) metabolism.

CONCLUSION

We demonstrated an association between DNA-methylation and hemorrhage/saline resuscitation. These results suggest a potential role of DNA-methylation in the host response to injury.

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 Effects of Biological Sex on Sepsis Treatments in Animal Models: A Systematic Review and a Narrative Elaboration on Sex- and Gender-Dependent Differences in Sepsis

Preclinical studies provide an opportunity to evaluate the relationship between sex and sepsis, and investigate underlying mechanisms in a controlled experimental environment. The objective of our systematic review was to assess the impact of biological sex on treatment response to fluid and antibiotic therapy in animal models of sepsis. Furthermore, we provide a narrative elaboration of sex-dependent differences in preclinical models of sepsis.

DATA SOURCES

MEDLINE and Embase were searched from inception to March 16, 2020.

STUDY SELECTION

All studies reporting sex-stratified data comparing antibiotics and/or fluid resuscitation with a placebo or no treatment arm in an in vivo model of sepsis were included.

DATA EXTRACTION

Outcomes of interest were mortality (primary) and organ dysfunction (secondary). Risk of bias was assessed. Study selection and data extraction were conducted independently and in duplicate.

DATA SYNTHESIS

The systematic search returned 2,649 unique studies, and two met inclusion criteria. Both studies used cecal ligation and puncture models with imipenem/cilastatin antibiotics. No eligible studies investigated fluids. In one study, antibiotic therapy significantly reduced mortality in male, but not female, animals. The other study reported no sex differences in organ dysfunction. Both studies were deemed to be at a high overall risk of bias.

CONCLUSIONS

There is a remarkable and concerning paucity of data investigating sex-dependent differences in fluid and antibiotic therapy for the treatment of sepsis in animal models. This may reflect poor awareness of the importance of investigating sex-dependent differences. Our discussion therefore expands on general concepts of sex and gender in biomedical research and sex-dependent differences in key areas of sepsis research such as the cardiovascular system, immunometabolism, the microbiome, and epigenetics. Finally, we discuss current clinical knowledge, the potential for reverse translation, and directions for future studies.

REGISTRATION

PROSPERO CRD42020192738.

Epigenetics of Sepsis

OBJECTIVES

Recent evidence from the fields of microbiology and immunology, as well as a small number of human sepsis studies, suggest that epigenetic regulation may play a central role in the pathogenesis of sepsis. The term "epigenetics" refers to regulatory mechanisms that control gene expression but are not related to changes in DNA sequence. These include DNA methylation, histone modifications, and regulation of transcription via non-coding RNAs. Epigenetic modifications, occurring in response to external stressors, lead to changes in gene expression, and thus lie at the intersection between genetics and the environment. In this review, we examine data from in vitro studies, animal studies, and the existing human sepsis studies in epigenetics to demonstrate that epigenetic mechanisms are likely central to the pathogenesis of sepsis and that epigenetic therapies may have potential in the treatment of sepsis and its associated organ failures.

DATA SOURCES

Online search of published scientific literature via Pubmed using the term "epigenetics" in combination with the terms "sepsis", "infection", "bacterial infection", "viral infection", "critical illness", "acute respiratory distress syndrome", and "acute lung injury".

STUDY SELECTION

Articles were chosen for inclusion based on their relevance to sepsis, acute inflammation, sepsis-related immune suppression, and sepsis-related organ failure. Reference lists were reviewed to identify additional relevant articles.

DATA EXTRACTION

Relevant data was extracted and synthesized for narrative review.

DATA SYNTHESIS

Epigenetic regulation is a key determinant of gene expression in sepsis. At the onset of infection, host-pathogen interactions often result in epigenetic alterations to host cells that favor pathogen survival. In parallel, the host inflammatory response is characterized by epigenetic modifications in key regulatory genes, including tumor necrosis factor and interleukin-1β. In human sepsis patients, multiple epigenetic modifying enzymes show differential expression in early sepsis, suggesting a role for epigenetics in coordinating the response to infection. In the later stages of sepsis, epigenetic modifications accompany endotoxin tolerance and the immune-suppressed state. In animal models, treatment with epigenetic modifiers can mitigate the effects of sepsis and improve survival as well as reverse sepsis-associated organ injury.

CONCLUSIONS

Epigenetic modifications are associated with key phases of sepsis, from the host-pathogen interaction, to acute inflammation, to immune suppression. Epigenetic markers show promise in the diagnosis and prognosis of sepsis and epigenetic modifying agents show promise as therapeutic tools in animal models of sepsis. Human studies in the area of epigenetics are sorely lacking and should be a priority for sepsis researchers.

DNA methylation inhibitors: Retrospective and perspective view

DNA methylation is an epigenetic modification that contributes to essential biological processes such as retrotransposon silencing, cell differentiation, genomic imprinting and X-chromosome inactivation. DNA methylation generates a stable epigenetic mark associated with silencing of gene expression. Aberrant DNA methylation is associated with the development of different tumor types. Reversing DNA methylation is a rational strategy to restore gene re-expression and induce cell differentiation in cancer. DNA hypomethylating agents is a class of drugs that demonstrated efficacy in different tumors. In this chapter, the classification of DNA hypomethylating agents, their pharmacodynamics and their potential drawbacks will be discussed.

Rivaroxaban improves vascular response in LPS-induced acute inflammation in experimental models

Rivaroxaban (RVX) was suggested to possess anti-inflammatory and vascular tone modulatory effects. The goal of this study was to investigate whether RVX impacts lipopolysaccharide (LPS)-induced acute vascular inflammatory response. Male rats were treated with 5 mg/kg RVX (oral gavage) followed by 10 mg/kg LPS i.p injection. Circulating levels of IL-6, MCP-1, VCAM-1, and ICAM-1 were measured in plasma 6 and 24 hours after LPS injection, while isolated aorta was used for gene expression analysis, immunohistochemistry, and vascular tone evaluation. RVX pre-treatment significantly reduced LPS mediated increase after 6h and 24h for IL-6 (4.4±2.2 and 2.8±1.7 fold), MCP-1 (1.4±1.5 and 1.3±1.4 fold) VCAM-1 (1.8±2.0 and 1.7±2.1 fold). A similar trend was observed in the aorta for iNOS (5.5±3.3 and 3.3±1.9 folds reduction, P<0.01 and P<0.001, respectively), VCAM-1 (1.3±1.2 and 1.4±1.3 fold reduction, P<0.05), and MCP-1 (3.9±2.2 and 1.9±1.6 fold reduction, P<0.01). Moreover, RVX pre-treatment, improved LPS-induced PE contractile dysfunction in aortic rings (Control vs LPS, Emax reduction = 35.4 and 31.19%, P<0.001; Control vs LPS+RVX, Emax reduction = 10.83 and 11.48%, P>0.05, respectively), resulting in 24.5% and 19.7% change in maximal constriction in LPS and LPS+RVX respectively. These data indicate that RVX pre-treatment attenuates LPS-induced acute vascular inflammation and contractile dysfunction.

LPS-Induced Endotoxemia Evokes Epigenetic Alterations in Mitochondrial DNA That Impacts Inflammatory Response

Mitochondrial DNA (mtDNA) plays a vital role as a damage-associated molecular pattern in sepsis being able to shape the immune response. Since pathogen recognition receptors of innate immune cells are activated by demethylated DNA only, we set out to investigate the amount of DNA methyltransferase 1 (DNMT1) in mitochondria and the extent of mtDNA methylation in a human endotoxin model. Peripheral blood mononuclear cells of 20 healthy individuals were isolated from whole blood and stimulated with lipopolysaccharide (LPS) for 48 h. Subsequently, DNMT1 protein abundance was assessed in whole cells and a mitochondrial fraction. At the same time, methylation levels of mtDNA were quantified, and cytokine expression in the supernatant was measured. Despite increased cellular expression of DNMT1 after LPS stimulation, the degree of mtDNA methylation slightly decreased. Strikingly the mitochondrial protein abundance of DNMT1 was reduced by 50% in line with the lower degree of mtDNA methylation. Although only modest alterations were seen in the degree of mtDNA methylation, these strongly correlated with IL-6 and IL-10 expression. Our data may hint at a protein import problem for DNMT1 into the mitochondria under LPS stimulation and suggest a role of demethylated mtDNA in the regulation of the inflammatory immune response.

Inhibiting DNA Methylation Improves Survival in Severe Sepsis by Regulating NF-κB Pathway

Organ dysfunction caused by sepsis is life-threatening and results in high mortality. Therapeutic options for sepsis are limited. Pathogenic factors are considered as components of environmental pressure that modify DNA methylation patterns thereby enhancing disease progression. Here, we found that sepsis patients exhibited higher levels of genomic DNA methylation patterns and hypermethylated genes associated with the NF-kB signaling pathway. Therefore, we hypothesized that a DNA methyl transferase inhibitor, Decitabine, may mitigate inflammation and improve survival by inhibiting the NF-κB signaling pathway. To test the hypothesis, mice challenged with caecal ligation and puncture (CLP) were subcutaneously injected with Decitabine solution (0.5, 1, and 1.5 mg/kg) 2 h following operation. Our results indicated that Decitabine reduces DNA methyltransferases (DNMTs), attenuates NF-κB activation, downregulates inflammatory cytokine levels, and inhibits the progression of sepsis. Thus, DNA methylation may be indispensable for sepsis and serve as a predicting factor. The use of Decitabine could represent a novel strategy in the treatment of sepsis.

Epigenetics Mechanisms in Multiorgan Dysfunction Syndrome

Epigenetic mechanisms including deoxyribonucleic acid (DNA) methylation, histone modifications (eg, histone acetylation), and microribonucleic acids (miRNAs) have gained much scientific interest in the last decade as regulators of genes expression and cellular function. Epigenetic control is involved in the modulation of inflammation and immunity, and its dysregulation can contribute to cell damage and organ dysfunction. There is growing evidence that epigenetic changes can contribute to the development of multiorgan dysfunction syndrome (MODS), a leading cause of mortality in the intensive care unit (ICU). DNA hypermethylation, histone deacetylation, and miRNA dysregulation can influence cytokine and immune cell expression and promote endothelial dysfunction, apoptosis, and end-organ injury, contributing to the development of MODS after a critical injury. Epigenetics processes, particularly miRNAs, are emerging as potential biomarkers of severity of disease, organ damage, and prognostic factors in critical illness. Targeting epigenetics modifications can represent a novel therapeutic approach in critical care. Inhibitors of histone deacetylases (HDCAIs) with anti-inflammatory and antiapoptotic activities represent the first class of drugs that reverse epigenetics modifications with human application. Further studies are required to acquire a complete knowledge of epigenetics processes, full understanding of their individual variability, to expand their use as accurate and reliable biomarkers and as safe target to prevent or attenuate MODS in critical disease.

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.

Sevoflurane Exposure Results in Sex-Specific Transgenerational Upregulation of Target IEGs in the Subiculum

Large body of animal work and emerging clinical findings have suggested that early exposure to anesthetics may result in increased risk of learning disabilities and behavioral impairments. Recent studies have begun to investigate anesthesia-induced epigenetic modifications to elucidate their role in behavioral and neurodevelopmental abnormalities. Here we examine sevoflurane-induced transgenerational modifications of subicular neuronal DNA methylation and expression of immediate early genes (IEGs), arc and junB, crucial to synaptic plasticity and normal neuronal development. We show that 6 h sevoflurane exposure in postnatal day 7 rat pups resulted in decreased neuronal 5-methycytosine, indicating reduced DNA methylation. This effect is transgenerationally expressed in offspring born to exposed mothers which is of importance considering that decreased DNA methylation in the brain has been linked with functional decline in learning and memory. We further show that sevoflurane exposure induces upregulation of Arc and JunB mRNA expression, 42.7% and 35.2%, respectively. Transgenerational changes in Arc and JunB mRNA were sexually dimorphic only occurring in males born to exposed females, expressed as upregulation of Arc and JunB mRNA, 71.6% and 74.0%, respectively. We further investigated correlation between altered arc promoter methylation and observed upregulation of Arc mRNA and observed that sevoflurane reduced methylation in the 5-upstream promoter region of females exposed to sevoflurane. Transgenerational hypomethylation and modifications to IEGs crucial to synaptic plasticity, observed following neonatal sevoflurane exposure could contribute to morphological and cognitive deficits known to occur with neonatal sevoflurane exposure.

Cyclodextrin potentiometric sensors based on selective recognition sites for procainamide: Comparative and theoretical study

Polyvinyl chloride (PVC) membrane sensors were constructed and developed for the determination of procainamide HCl (PR). Three membrane sensors incorporating α-, β- and γ- cyclodextrin (CD) as ionophores with potassium tetrakis (4-chlorophenyl) borate (KTpClPB) as the ion additive, o-nitro phenyl ether (o-NPOE) as the plasticizer and a PVC matrix. The reaction mechanisms were based on inclusion complexes. The developed α- and β- CD sensors exhibited near-Nernstian profile, whereas γ- CD showed a non-Nernstian response. At pH 4 -8, the sensors exhibited a calibration range for PR of 10-3 to 10−6, and the detection limits were 2.40 × 10-6, 2.12 × 10-6, 2.40 × 10-6 for α-, β- and γ- CD sensors, respectively. Interference was investigated by studying the selectivity coefficient values of the test sensors, which indicated that the methods were free from interference from investigated species. The determination of PR exhibited high recovery and favorable relative standard deviation using the investigated sensors. The sensors were subsequently used for the quantification of PR in a pharmaceutical formulation and the potentiometric results agreed with those of a spectrophotometric method. A molecular docking (MD) study was used to predict the structure of the inclusion complexes of PR (guest) and α- or β- or γ-CD (host). The study results indicated that the formed complexes were stable with sufficient binding energy.

Epigenetic and metabolic programming of innate immunity in sepsis

Sepsis, the 10th leading cause of death, is the most expensive condition in the United States. The immune response in sepsis transitions from hyperinflammatory to a hypoinflammatory and immunosuppressive phase; individual variations regarding timing and overlap between hyper- and hypoinflammation exist in a number of patients. While one third of the sepsis-related deaths occur during hyperinflammation, majority of the sepsis-mortality occurs during the hypoinflammatory phase. Currently, no phase-specific molecular-based therapies exist to treat sepsis. Coordinated epigenetic and metabolic perturbations orchestrate this shift from hyper- to hypoinflammation in innate immune cells during sepsis. These epigenetic and metabolic changes during sepsis progression and therapeutic opportunities they pose are described in this review.

Simultaneous Determination of Procainamide and N-acetylprocainamide in Rat Plasma by Ultra-High-Pressure Liquid Chromatography Coupled with a Diode Array Detector and Its Application to a Pharmacokinetic Study in Rats

A simple, sensitive, and reliable reversed-phase, Ultra-High-Pressure Liquid Chromatography (UHPLC) coupled with a Diode Array Detector (DAD) method for the simultaneous determination of Procainamide (PA) and its major metabolite, N-acetylprocainamide (NAPA), in rat plasma was developed and validated. A simple deproteinization method with methanol was applied to the rat plasma samples, which were analyzed using UHPLC equipped with DAD at 280 nm, and a Synergi™ 4 µm polar, reversed-phase column using 1% acetic acid (pH 5.5) and methanol (76:24, v/v) as eluent in isocratic mode at a flow rate 0.2 mL/min. The method showed good linearity (r² > 0.998) over the concentration range of 20–100,000 and 20–10,000 ng/mL for PA and NAPA, respectively. Intra- and inter-day accuracies ranged from 97.7 to 110.9%, and precision was <10.5% for PA and 99.7 to 109.2 and <10.5%, respectively, for NAPA. The lower limit of quantification was 20 ng/mL for both compounds. This is the first report of the UHPLC-DAD bioanalytical method for simultaneous measurement of PA and NAPA. The most obvious advantage of this method over previously reported HPLC methods is that it requires small sample and injection volumes, with a straightforward, one-step sample preparation. It overcomes the limitations of previous methods, which use large sample volume and complex sample preparation. The devised method was successfully applied to the quantification of PA and NAPA after an intravenous bolus administration of 10 mg/kg procainamide hydrochloride to rats.

Procaine stimulates aquaporin‑5 expression in human salivary gland ductal cells via the suppression of DNA methyltransferase‑1

The present study aimed to investigate whether procaine may upregulate the expression of aquaporin‑5 (AQP5) in human salivary gland ductal cells and the underlying mechanisms of this upregulation. Immortalized normal human salivary gland ductal cells (NS‑SV‑DC), lacking AQP5 protein expression, were used to measure the glandular secretion rate following treatment with procaine, and the protein expression levels of AQP5 in NS‑SV‑DC cells were measured by western blotting. In order to investigate the mechanism of procaine action on AQP5 protein expression, the protein expression and activity of DNA methyltransferase (DNMT)1, and the CpG methylation of AQP5, were investigated further. In NS‑SV‑DC cells treated with procaine, the mRNA and protein levels of AQP5, and the secretion rate of cells, were significantly increased. Although no significant alterations were observed in the protein expression of DNMT1 following procaine treatment, its enzymatic activity was reduced, resulting in CpG island demethylation at Sp1‑2 and Sp1‑3 sites of the AQP5 gene, which may contribute to the significantly upregulated AQP5 gene expression. The results of the present study indicate that procaine may upregulate the protein expression of AQP5 in human submandibular glands by inhibiting the activity of DNMT1 and promoting liquid secretion. The procaine‑mediated expression of AQP5 may provide a novel regimen for the treatment of SS syndrome.

Comprehensive Analysis of Gene Expression Profiles of Sepsis-Induced Multiorgan Failure Identified Its Valuable Biomarkers

Sepsis is an inflammatory-related disease, and severe sepsis would induce multiorgan dysfunction, which is the most common cause of death of patients in noncoronary intensive care units. Progression of novel therapeutic strategies has proven to be of little impact on the mortality of severe sepsis, and unfortunately, its mechanisms still remain poorly understood. In this study, we analyzed gene expression profiles of severe sepsis with failure of lung, kidney, and liver for the identification of potential biomarkers. We first downloaded the gene expression profiles from the Gene Expression Omnibus and performed preprocessing of raw microarray data sets and identification of differential expression genes (DEGs) through the R programming software; then, significantly enriched functions of DEGs in lung, kidney, and liver failure sepsis samples were obtained from the Database for Annotation, Visualization, and Integrated Discovery; finally, protein-protein interaction network was constructed for DEGs based on the STRING database, and network modules were also obtained through the MCODE cluster method. As a result, lung failure sepsis has the highest number of DEGs of 859, whereas the number of DEGs in kidney and liver failure sepsis samples is 178 and 175, respectively. In addition, 17 overlaps were obtained among the three lists of DEGs. Biological processes related to immune and inflammatory response were found to be significantly enriched in DEGs. Network and module analysis identified four gene clusters in which all or most of genes were upregulated. The expression changes of Icam1 and Socs3 were further validated through quantitative PCR analysis. This study should shed light on the development of sepsis and provide potential therapeutic targets for sepsis-induced multiorgan failure.

A synthetic cationic antimicrobial peptide inhibits inflammatory response and the NLRP3 inflammasome by neutralizing LPS and ATP

Antimicrobial peptides (AMPs) are one of the most important defense mechanisms against bacterial infections in insects, plants, non-mammalian vertebrates, and mammals. In the present study, a class of synthetic AMPs was evaluated for anti-inflammatory activity. One cationic AMP, GW-A2, demonstrated the ability to inhibit the expression levels of nitric oxide (NO), inducible NO synthase (iNOS), cyclooxygenase-2 (COX-2), tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) in lipopolysaccharide (LPS)-activated macrophages. GW-A2 reduced LPS-induced increases in the phosphorylation of mitogen-activated protein kinase and protein kinase C-α/δ and the activation of NF-κB. GW-A2 also inhibited NLRP3 inflammasome activation induced by LPS and ATP. Furthermore, in the mice injected with LPS, GW-A2 reduced (1) the concentration of IL-1β, IL-6 and TNF-α in the serum; (2) the concentration of TNF-α in the peritoneal lavage; (3) the expression levels of iNOS, COX-2 and NLRP3 in the liver and lung; (4) the infiltration of polymorphonuclear neutrophils in the liver and lung. The underlying mechanisms for the anti-inflammatory activity of GW-A2 were found to be partially due to LPS and ATP neutralization. These results provide insights into how GW-A2 inhibits inflammation and the NLRP3 inflammasome and provide a foundation for the design of rational therapeutics for inflammation-related diseases.