Biology and Metabolism of Sepsis: Innate Immunity, Bioenergetics, and Autophagy

Metabolic regulation of neutrophil functions in homeostasis and diseases

Neutrophils are the most abundant leukocytes in humans and play a role in the innate immune response by being the first cells attracted to the site of infection. While early studies presented neutrophils as almost exclusively glycolytic cells, recent advances show that these cells use several metabolic pathways other than glycolysis, such as the pentose phosphate pathway, oxidative phosphorylation, fatty acid oxidation, and glutaminolysis, which they modulate to perform their functions. Metabolism shifts from fatty acid oxidation-mediated mitochondrial respiration in immature neutrophils to glycolysis in mature neutrophils. Tissue environments largely influence neutrophil metabolism according to nutrient sources, inflammatory mediators, and oxygen availability. Inhibition of metabolic pathways in neutrophils results in impairment of certain effector functions, such as NETosis, chemotaxis, degranulation, and reactive oxygen species generation. Alteration of these neutrophil functions is implicated in certain human diseases, such as antiphospholipid syndrome, coronavirus disease 2019, and bronchiectasis. Metabolic regulators such as AMPK, HIF-1α, mTOR, and Arf6 are linked to neutrophil metabolism and function and could potentially be targeted for the treatment of diseases associated with neutrophil dysfunction. This review details the effects of alterations in neutrophil metabolism on the effector functions of these cells.

Oxidative stress, defective proteostasis and immunometabolic complications in critically ill patients

Oxidative stress (OS) develops in critically ill patients as a metabolic consequence of the immunoinflammatory and degenerative processes of the tissues. These induce increased and/or dysregulated fluxes of reactive species enhancing their pro-oxidant activity and toxicity. At the same time, OS sustains its own inflammatory and immunometabolic pathogenesis, leading to a pervasive and vitious cycle of events that contribute to defective immunity, organ dysfunction and poor prognosis. Protein damage is a key player of these OS effects; it generates increased levels of protein oxidation products and misfolded proteins in both the cellular and extracellular environment, and contributes to forms DAMPs and other proteinaceous material to be removed by endocytosis and proteostasis processes of different cell types, as endothelial cells, tissue resident monocytes-macrophages and peripheral immune cells. An excess of OS and protein damage in critical illness can overwhelm such cellular processes ultimately interfering with systemic proteostasis, and consequently with innate immunity and cell death pathways of the tissues thus sustaining organ dysfunction mechanisms. Extracorporeal therapies based on biocompatible/bioactive membranes and new adsorption techniques may hold some potential in reducing the impact of OS on the defective proteostasis of patients with critical illness. These can help neutralizing reactive and toxic species, also removing solutes in a wide spectrum of molecular weights thus improving proteostasis and its immunometabolic corelates. Pharmacological therapy is also moving steps forward which could help to enhance the efficacy of extracorporeal treatments. This narrative review article explores the aspects behind the origin and pathogenic role of OS in intensive care and critically ill patients, with a focus on protein damage as a cause of impaired systemic proteostasis and immune dysfunction in critical illness.

Isopropyl 3-(3,4-dihydroxyphenyl) 2-hydroxypropanoate protects septic myocardial injury via regulating GAS6/Axl-AMPK signaling pathway

In a previous study, we used metabolomic techniques to identify a new metabolite of Danshen Dripping Pills called isopropyl 3-(3,4-dihydroxyphenyl)-2-hydroxypropanoate (IDHP), which has potential as a drug candidate for cardiovascular diseases. This study aimed to explore the protective effects of IDHP against septic myocardial injury, as well as its molecular mechanism. Wild type or GAS6 knockout mice injured by cecal ligation and puncture (CLP) were used to observe the effect of IDHP. Here, we found that a specific concentration of IDHP (60 mg/kg) significantly increased the survival rate of septic mice to about 75 % at 72 h post CLP, and showed improvements in sepsis score, blood biochemistry parameters, cardiac function, and myocardial tissue damage. Furthermore, IDHP inhibited myocardial oxidative stress, inflammatory response, apoptosis, and mitochondrial dysfunction. Molecularly, we discovered that IDHP treatment reversed the CLP-induced downregulation of GAS6, Axl, and p-AMPK/AMPK expression. In addition, GAS6 knockout reversed the positive effect of IDHP in septic mice, indicated by more severe myocardial tissue damage, oxidative stress, inflammatory response, and mitochondrial dysfunction. GAS6 knockout also resulted in decreased levels of GAS6, Axl, and p-AMPK/AMPK. Taken together, our study provides evidence that IDHP has significant cardioprotective effects against sepsis by regulating the GAS6/Axl-AMPK signaling pathway. This finding has important therapeutic potential for treating sepsis.

Application and value of hydrogen sulfide modulated autophagy in sepsis

Sepsis is is anabnormalhost immune responsecausedbyinfection. Antibiotics, anti-viral drugs, and vasoactive drugs have always been used in the traditional treatment of sepsis, but there are no specific and effective drugs in clinical practice. Autophagy is a highly conservative process in biological evolution, and plays an important role in maintaining intracellular homeostasis and cellular self-renewal. Autophagy can remove and degrade misfolding proteins and damaged organelles in cells, providing materials for cell repair and self-renewal. Hydrogen sulfide (H2S) is a colorless gas that smells likerotteneggs. It is the third endogenous gas signal molecule discovered after nitric oxide and carbon monoxide and has become a research hotspot in recent years. H2S has a variety of biological functions and plays an important role in various physiological and pathological processes. Thereisgrowingevidencethat H2S can regulate autophagy. The intervention of autophagy is a promising therapeutic strategy to improve sepsis organ damage. This article reviews the organ protection of autophagy in sepsis and the role of H2S in regulating autophagy in sepsis, revealing that H2S intervention with autophagy may be a a worthy target in sepsis treatment.

Integrative single-cell RNA sequencing and metabolomics decipher the imbalanced lipid-metabolism in maladaptive immune responses during sepsis

Background

To identify differentially expressed lipid metabolism-related genes (DE-LMRGs) responsible for immune dysfunction in sepsis.

Methods

The lipid metabolism-related hub genes were screened using machine learning algorithms, and the immune cell infiltration of these hub genes were assessed by CIBERSORT and Single-sample GSEA. Next, the immune function of these hub genes at the single-cell level were validated by comparing multiregional immune landscapes between septic patients (SP) and healthy control (HC). Then, the support vector machine-recursive feature elimination (SVM-RFE) algorithm was conducted to compare the significantly altered metabolites critical to hub genes between SP and HC. Furthermore, the role of the key hub gene was verified in sepsis rats and LPS-induced cardiomyocytes, respectively.

Results

A total of 508 DE-LMRGs were identified between SP and HC, and 5 hub genes relevant to lipid metabolism (MAPK14, EPHX2, BMX, FCER1A, and PAFAH2) were screened. Then, we found an immunosuppressive microenvironment in sepsis. The role of hub genes in immune cells was further confirmed by the single-cell RNA landscape. Moreover, significantly altered metabolites were mainly enriched in lipid metabolism-related signaling pathways and were associated with MAPK14. Finally, inhibiting MAPK14 decreased the levels of inflammatory cytokines and improved the survival and myocardial injury of sepsis.

Conclusion

The lipid metabolism-related hub genes may have great potential in prognosis prediction and precise treatment for sepsis patients.

Atg6 promotes organismal health by suppression of cell stress and inflammation

Autophagy targets cytoplasmic materials for degradation, and influences cell health. Alterations in Atg6/Beclin-1, a key regulator of autophagy, are associated with multiple diseases. While the role of Atg6 in autophagy regulation is heavily studied, the role of Atg6 in organism health and disease progression remains poorly understood. Here, we discover that loss of Atg6 in Drosophila results in various alterations to stress, metabolic and immune signaling pathways. We find that the increased levels of circulating blood cells and tumor-like masses in atg6 mutants vary depending on tissue-specific function of Atg6, with contributions from intestine and hematopoietic cells. These phenotypes are suppressed by decreased function of macrophage and inflammatory response receptors crq and drpr. Thus, these findings provide a basis for understanding how Atg6 systemically regulates cell health within multiple organs, and highlight the importance of Atg6 in inflammation to organismal health.

COVID-19 and Long-Term Outcomes: Lessons from Other Critical Care Illnesses and Potential Mechanisms

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a novel coronavirus that is currently causing a pandemic and has been termed coronavirus disease (COVID-19). The elderly or those with preexisting conditions like diabetes, hypertension, coronary heart disease, chronic obstructive pulmonary disease, cerebrovascular disease, or kidney dysfunction are more likely to develop severe cases when infected. Patients with COVID-19 admitted to the ICU have higher mortality than non-ICU patients. Critical illness has consistently posed a challenge not only in terms of mortality but also in regard to long-term outcomes of survivors. Patients who survive acute critical illness including, but not limited to, pulmonary and systemic insults associated with acute respiratory distress syndrome, pneumonia, systemic inflammation, and mechanical ventilation, will likely suffer from post-ICU syndrome, a phenomenon of cognitive, psychiatric, and/or physical disability after treatment in the ICU. Post-ICU morbidity and mortality continue to be a cause for concern when considering large-scale studies showing 12-month mortality risks of 11.8-21%. Previous studies have demonstrated that multiple mechanisms, including cytokine release, mitochondrial dysfunction, and even amyloids, may lead to end-organ dysfunction in patients. We hypothesize that COVID-19 infection will lead to post-ICU syndrome via potentially similar mechanisms as other chronic critical illnesses and cause long-term morbidity and mortality in patients. We consider a variety of mechanisms and questions that not only consider the short-term impact of the COVID-19 pandemic but its long-term effects that may not yet be imagined.

Nicotinamide Mononucleotide Administration Triggers Macrophages Reprogramming and Alleviates Inflammation During Sepsis Induced by Experimental Peritonitis

Peritonitis and subsequent sepsis lead to high morbidity and mortality in response to uncontrolled systemic inflammation primarily mediated by macrophages. Nicotinamide adenine dinucleotide (NAD+) is an important regulator of oxidative stress and immunoinflammatory responses. However, the effects of NAD+ replenishment during inflammatory activation are still poorly defined. Hence, we investigated whether the administration of β-nicotinamide mononucleotide (β-NMN), a natural biosynthetic precursor of NAD+, could modulate the macrophage phenotype and thereby ameliorate the dysregulated inflammatory response during sepsis. For this purpose, C57BL6 mice were subjected to the cecal ligation and puncture (CLP) model to provoke sepsis or were injected with thioglycolate to induce sterile peritonitis with recruitment and differentiation of macrophages into the inflamed peritoneal cavity. β-NMN was administered for 4 days after CLP and for 3 days post thioglycolate treatment where peritoneal macrophages were subsequently analyzed. In the CLP model, administration of β-NMN decreased bacterial load in blood and reduced clinical signs of distress and mortality during sepsis. These results were supported by transcriptomic analysis of hearts and lungs 24 h post CLP-induction, which revealed that β-NMN downregulated genes controlling the immuno-inflammatory response and upregulated genes involved in bioenergetic metabolism, mitochondria, and autophagy. In the thioglycolate model, a significant increase in the proportion of CD206 macrophages, marker of anti-inflammatory M2 phenotype, was detected on peritoneal exudate macrophages from β-NMN-administered mice. Transcriptomic signature of these macrophages after bacterial stimulation confirmed that β-NMN administration limited the pro-inflammatory M1 phenotype and induced the expression of specific markers of M2 type macrophages. Furthermore, our data show that β-NMN treatment significantly impacts NAD + metabolism. This shift in the macrophage phenotype and metabolism was accompanied by a reduction in phagolysosome acidification and secretion of inflammatory mediators in macrophages from β-NMN-treated mice suggesting a reduced pro-inflammatory activation. In conclusion, administration of β-NMN prevented clinical deterioration and improved survival during sepsis. These effects relied on shifts in the metabolism of organs that face up an increased energy requirement caused by bacterial infection and in innate immunity response, including reprogramming of macrophages from a highly inflammatory phenotype to an anti-inflammatory/pro-resolving profile.

The Landscape of Featured Metabolism-Related Genes and Imbalanced Immune Cell Subsets in Sepsis

Sepsis is a heterogeneous disease state triggered by an uncontrolled inflammatory host response with high mortality and morbidity in severely ill patients. Unfortunately, the treatment effectiveness varies among sepsis patients and the underlying mechanisms have yet to be elucidated. The present aim is to explore featured metabolism-related genes that may become the biomarkers in patients with sepsis. In this study, differentially expressed genes (DEGs) between sepsis and non-sepsis in whole blood samples were identified using two previously published datasets (GSE95233 and GSE54514). A total of 66 common DEGs were determined, namely, 52 upregulated and 14 downregulated DEGs. The Gene Set Enrichment Analysis (GSEA) results indicated that these DEGs participated in several metabolic processes including carbohydrate derivative, lipid, organic acid synthesis oxidation reduction, and small-molecule biosynthesis in patients with sepsis. Subsequently, a total of 8 hub genes were screened in the module with the highest score from the Cytoscape plugin cytoHubba. Further study showed that these hub DEGs may be robust markers for sepsis with high area under receiver operating characteristic curve (AUROC). The diagnostic values of these hub genes were further validated in myocardial tissues of septic rats and normal controls by untargeted metabolomics analysis using liquid chromatography-mass spectrometry (LC-MS). Immune cell infiltration analysis revealed that different infiltration patterns were mainly characterized by B cells, T cells, NK cells, monocytes, macrophages, dendritics, eosinophils, and neutrophils between sepsis patients and normal controls. This study indicates that metabolic hub genes may be hopeful biomarkers for prognosis prediction and precise treatment in sepsis patients.

Pink1/Parkin-Mediated Mitophagy Regulated the Apoptosis of Dendritic Cells in Sepsis

Dendritic cells (DCs) are vital antigen-presenting cells (APCs) in the immune system, whose apoptosis is closely related to the development of sepsis. Mitophagy is one of the necessary forms of selective autophagy that removes damaged or dysfunctional mitochondria to regulate immunity and inflammation. However, its effect on the apoptosis of DC in sepsis remains unknown. Here, we showed that sepsis activated the apoptosis and mitophagy of DC, and mitophagy had an anti-apoptotic effect on sepsis-induced DC apoptosis. In this study, we used cecal ligation and puncture (CLP) to simulate the pathophysiological state of sepsis. Apoptosis and mitophagy of DC were significantly enhanced in CPL mice compared with controls, and in the Pink1-KO (Pink1-knockout) mice CLP model, the level of apoptosis in DC was further increased while the level of mitophagy was decreased. In addition, more severe mitochondrial dysfunction was exhibited in DC of Pink1-KO mice CLP model compared to wild-type (WT) mice. The results suggest that Pink1/Parkin-mediated mitophagy is activated during sepsis and has an anti-apoptotic effect on DC, which regulates immune functions.

A digital health platform for assisting the diagnosis and monitoring of COVID-19 progression: An adjuvant approach for augmenting the antiviral response and mitigating the immune-mediated target organ damage

Coronavirus disease 2019 (COVID-19), which is a respiratory illness associated with high mortality, has been classified as a pandemic. The major obstacles for the clinicians to contain the disease are limited information availability, difficulty in disease diagnosis, predicting disease prognosis, and lack of disease monitoring tools. Additionally, the lack of valid therapies has further contributed to the difficulties in containing the pandemic. Recent studies have reported that the dysregulation of the immune system leads to an ineffective antiviral response and promotes pathological immune response, which manifests as ARDS, myocarditis, and hepatitis. In this study, a novel platform has been described for disseminating information to physicians for the diagnosis and monitoring of patients with COVID-19. An adjuvant approach using compounds that can potentiate antiviral immune response and mitigate COVID-19-induced immune-mediated target organ damage has been presented. A prolonged beneficial effect is achieved by implementing algorithm-based individualized variability measures in the treatment regimen.

Hydrogen alleviates cell damage and acute lung injury in sepsis via PINK1/Parkin-mediated mitophagy

BACKGROUND

Multiple organ failure (MOF) is the main cause of early death in septic shock. Lungs are among the organs that are affected in MOF, resulting in acute lung injury. Inflammation is an important factor that causes immune cell dysfunction in the pathogenesis of sepsis. Autophagy is involved in the process of inflammation and also occurs in response to cell and tissue injury in several diseases. We previously demonstrated that hydrogen alleviated the inflammation-induced cell injury and organ damage in septic mice.

AIM

The focus of the present study was to elucidate whether mitophagy mediates the inflammatory response or oxidative injury in sepsis in vitro and in vivo. Furthermore, we evaluated the role of mitophagy in the protective effects of hydrogen against cell injury or organ dysfunction in sepsis.

METHOD

RAW 264.7 macrophages induced by lipopolysaccharide (LPS) were used as an in vitro model for inflammation, and cecal ligation and puncture (CLP)-induced acute lung injury mice were used as an in vivo model for sepsis. The key protein associated with mitophagy, PTEN-induced putative kinase 1 (PINK1), was knocked down by PINK1 shRNA transfection in RAW 264.7 macrophages or mice.

RESULTS

Hydrogen ameliorated cell injury and enhanced mitophagy in macrophages stimulated by LPS. PINK1 was required for the mitigation of the cell impairment in LPS-stimulated macrophages by hydrogen treatment. PINK1 knockdown abrogated the beneficial effects of hydrogen on mitophagy in LPS-stimulated macrophages. Hydrogen inhibited acute lung injury in CLP mice via activation of PINK1-mediated mitophagy.

CONCLUSION

These results suggest that PINK1-mediated mitophagy plays a key role in the protective effects of hydrogen against cell injury in LPS-induced inflammation and CLP-induced acute lung injury.

Multi-Organ Transcriptome Dynamics in a Mouse Model of Cecal Ligation and Puncture-Induced Polymicrobial Sepsis

PURPOSE

During sepsis, an excessive inflammatory immune reaction contributes to multi-organ dysfunction syndrome (MODS), a critical condition associated with high morbidity and mortality; however, the molecular mechanisms driving MODS remain elusive.

METHODS

We used RNA sequencing to characterize transcriptional changes in the early phase of sepsis, at 6, 12, 24 hour time points in lung, kidney, liver, and heart tissues, in a cecal ligation and puncture (CLP)-induced polymicrobial sepsis murine model.

RESULTS

The CLP surgery induced significant changes (adj. p-value<0.05) in expression of hundreds of transcripts in the four organs tested, with the highest number exceeding 2,000 differentially expressed genes (DEGs) in all organs at 12 hours post-CLP. Over-representation analysis by functional annotations of DEGs to the Reactome database revealed the immune system, hemostasis, lipid metabolism, signal transduction, and extracellular matrix remodeling biological processes as significantly altered in at least two organs, while metabolism of proteins and RNA were revelaed as being liver tissue specific in the early phase of sepsis.

CONCLUSION

RNA sequencing across organs and time-points in the CLP murine model allowed us to study the trajectories of transcriptome changes demonstrating alterations common across multiple organs as well as biological pathways altered in an organ-specific manner. These findings could pave new directions in the research of sepsis-induced MODS and indicate new sepsis treatment strategies.

Metabolic Alterations in Sepsis

Sepsis is defined as “life-threatening organ dysfunction caused by a dysregulated host response to infection”. Contrary to the older definitions, the current one not only focuses on inflammation, but points to systemic disturbances in homeostasis, including metabolism. Sepsis leads to sepsis-induced dysfunction and mitochondrial damage, which is suggested as a major cause of cell metabolism disorders in these patients. The changes affect the metabolism of all macronutrients. The metabolism of all macronutrients is altered. A characteristic change in carbohydrate metabolism is the intensification of glycolysis, which in combination with the failure of entering pyruvate to the tricarboxylic acid cycle increases the formation of lactate. Sepsis also affects lipid metabolism—lipolysis in adipose tissue is upregulated, which leads to an increase in the level of fatty acids and triglycerides in the blood. At the same time, their use is disturbed, which may result in the accumulation of lipids and their toxic metabolites. Changes in the metabolism of ketone bodies and amino acids have also been described. Metabolic disorders in sepsis are an important area of research, both for their potential role as a target for future therapies (metabolic resuscitation) and for optimizing the current treatment, such as clinical nutrition.

The Surviving Sepsis Campaign: Basic/Translational Science Research Priorities

Objectives:

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

Data Sources:

Original paper, search of the literature.

Study Selection:

By several members of the original task force with specific expertise in basic/translational science.

Data Extraction:

None.

Data Synthesis:

None.

Conclusions:

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

Splenectomy provides protective effects against CLP-induced sepsis by reducing TRegs and PD-1/PD-L1 expression

The role of the spleen in sepsis is still controversial. Therefore, we investigated the effect of the spleen on sepsis-induced immune dysfunction in C57BL/6 mice subjected to caecal ligation and puncture (CLP). Changes in different immune cells and apoptotic cells in the spleen and peripheral blood were observed 4, 24 and 48 h after CLP. Then, we determined that 48 h following CLP was the most significant period of immunosuppression. Next, we divided the mice into four groups: control, CLP, CLP + spx (splenectomy 48 h after CLP) and spx + CLP (splenectomy surgery two weeks before CLP). Compared with the CLP mice, the CLP + spx and spx + CLP mice had improved survival rates and organ injuries, increased expression of inflammatory factors, a decreased proportion of regulatory T cells (Tregs), and reduced expression of the genes involved in the programmed cell death 1 and its ligand 1 (PD1-PDL1) pathway in immune cells and T-cell immunoglobulin-mucin domain 3 (Tim 3) and Galectin9 in the liver and lungs after 72 h in late-phase sepsis. In addition, the expression of PD-1 was significantly reduced in T cells in spx + CLP mice, and the expression of PD-L1 in myeloid-derived suppressor cells (MDSCs) was reduced in the CLP + spx group, especially in macrophages. These findings suggested that splenectomy could protect septic mice from exhaustion of immune cells by reducing the proliferation of Treg cells and expression of the PD-1/PD-L1 axis in immune cells during the immunosuppressive stage of sepsis. Splenectomy could also reduce liver and lung injuries possibly via the Tim 3 and/or Galectin-9 axis. The spleen is an important regulator of the occurrence and development of sepsis, which provides a new perspective to improve the prognosis of sepsis by regulating the spleen.

The diversity and coexistence of extracellular mitochondria in circulation: A friend or foe of the immune system

The diversity and coexistence of extracellular mitochondria may have a key role in the maintenance of health and progression of disease. Studies report that active mitochondria can be found physiologically outside of cells and circulating in the blood without inducing an inflammatory response. In addition, inactive or harmed mitochondria have been recognized as activators of immune cells, as they play an essential role in diseases characterized by the metabolic deregulation of these cells, such as sepsis. In this review we analyze key aspects regarding the existence of a diversity of extracellular mitochondria, their coexistence in body fluids and their effects on various immune cells. Additionally, we introduce models of how extracellular mitochondria could be interacting to maintain health and affect disease prognosis. Unwrapped mitochondria (freeMitos) can exist as viable, active, inactive or harmed organelles. Mitochondria can also be found wrapped in a membrane (wrappedMitos) that may differ depending on the cell of origin. Mitochondrial fragments can also be present in various body fluids as DAMPs, as mtDNA enclosed in vesicles or as circulating-cell-free mtDNA (ccf-mtDNA). Interestingly, the great quantity of evidence regarding the levels of ccf-mtDNA and their correlation with aging and disease allows for the identification of the diversity, but not type, of extracellular mitochondria. The existence of a diversity of mitochondria and their effects on immune cells opens a new concept in the biomedical field towards the understanding of health, the progression of disease and the development of mitochondria as therapeutic agents.

Dichloroacetate reverses sepsis-induced hepatic metabolic dysfunction

Metabolic reprogramming between resistance and tolerance occurs within the immune system in response to sepsis. While metabolic tissues such as the liver are subjected to damage during sepsis, how their metabolic and energy reprogramming ensures survival is unclear. Employing comprehensive metabolomic, lipidomic, and transcriptional profiling in a mouse model of sepsis, we show that hepatocyte lipid metabolism, mitochondrial tricarboxylic acid (TCA) energetics, and redox balance are significantly reprogrammed after cecal ligation and puncture (CLP). We identify increases in TCA cycle metabolites citrate, cis-aconitate, and itaconate with reduced fumarate and triglyceride accumulation in septic hepatocytes. Transcriptomic analysis of liver tissue supports and extends the hepatocyte findings. Strikingly, the administration of the pyruvate dehydrogenase kinase (PDK) inhibitor dichloroacetate reverses dysregulated hepatocyte metabolism and mitochondrial dysfunction. In summary, our data indicate that sepsis promotes hepatic metabolic dysfunction and that targeting the mitochondrial PDC/PDK energy homeostat rebalances transcriptional and metabolic manifestations of sepsis within the liver.

Sepsis impairs the propagation of cortical spreading depression in rats and this effect is prevented by antioxidant extract

Sepsis is a clinical syndrome with high morbidity and mortality. It is characterized by acute inflammatory response and oxidative stress, which is implicated in cerebral dysfunction. Murici (Byrsonimacrassifolia (L.) Kunth) is a fruit rich in antioxidant compounds, which could be an alternative to prevent damage to tissues induced by sepsis . Here, we evaluated the effects of sepsis on the propagation of cortical spreading depression (CSD) and oxidative stress, and tested the action of murici antioxidant extract in prevention against the effect of sepsis. Male Wistar rats (90-210 days, n = 40) were previously supplemented, orogastrically, with murici extract (150 mg/kg/day or 300 mg/kg/day), or an equivalent volume of the vehicle solution, for fifteen days. Then the animals were subjected to experimental sepsis through cecal ligation and perforation (CLP). Subsequently, CSD recordings were obtained and brain oxidative stress was evaluated. Sepsis decelerated CSD and increased the malondialdehyde (MDA) levels in the brain cortex of the animals. In contrast, septic rats that had been previously supplemented with murici antioxidant extract in doses of 150 and 300 mg/kg/day showed an increase in CSD propagation velocity, low levels of MDA and GSH/GSSG ratio and an increase of superoxide dismutase (SOD) activity, regardless of the dose tested. Our results demonstrate that sepsis affects brain excitability and that this effect can be prevented by murici antioxidant extract. The effects of sepsis and/or murici extract on CSD may be due to the oxidative state of the brain.

Effect of Interleukin-36β on Activating Autophagy of CD4+CD25+ Regulatory T cells and Its Immune Regulation in Sepsis

BACKGROUND

CD4+CD25+ regulatory T cells (Tregs) play an essential role in sepsis-induced immunosuppression. How, the effects of interleukin 36 (IL-36) cytokines on CD4+CD25+ Tregs and their underlying mechanism(s) in sepsis remain unknown.

METHODS

Our study was designed to investigate the impacts of IL-36 cytokines on murine CD4+CD25+ Tregs in presence of lipopolysaccharide (LPS) and in a mouse model of sepsis induced by cecal ligation and puncture (CLP). IL-36-activated autophagy was evaluated by autophagy markers, autophagosome formation, and autophagic flux.

RESULTS

IL-36α, IL-36β, and IL-36γ were expressed in murine CD4+CD25+ Tregs. Stimulation of CD4+CD25+ Tregs with LPS markedly up-regulated the expression of these cytokines, particularly IL-36β. IL-36β strongly suppressed CD4+CD25+ Tregs under LPS stimulation and in septic mice challenged with CLP, resulting in the amplification of T-helper 1 response and the proliferation of effector T cells. Mechanistic studies revealed that IL-36β triggered autophagy of CD4+CD25+ Tregs. These effects were significantly attenuated in the presence of the autophagy inhibitor 3-methyladenine or Beclin1 knockdown. In addition, early IL-36β administration reduced the mortality rate in mice subjected to CLP. Depletion of CD4+CD25+ Tregs before the onset of sepsis obviously abrogated IL-36β-mediated protection against sepsis.

CONCLUSIONS

These findings suggest that IL-36β diminishes the immunosuppressive activity of CD4+CD25+ Tregs by activating the autophagic process, thereby contributing to improvement of the host immune response and prognosis in sepsis.

The surviving sepsis campaign: basic/translational science research priorities

Objectives

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

Data sources

Original paper, search of the literature.

Study selection

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

Conclusions

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

Phagocytosis-Inflammation Crosstalk in Sepsis: New Avenues for Therapeutic Intervention

Phagocytosis is a complex process by which cells within most organ systems remove pathogens and cell debris. Phagocytosis is usually followed by inflammatory pathway activation, which promotes pathogen elimination and inhibits pathogen growth. Delayed pathogen elimination is the first step in sepsis development and a key factor in sepsis resolution. Phagocytosis thus has an important role during sepsis and likely contributes to all of its clinical stages. However, only a few studies have specifically explored and characterized phagocytic activity during sepsis. Here, we describe the phagocytic processes that occur as part of the immune response preceding sepsis onset and identify the elements of phagocytosis that might constitute a predictive marker of sepsis outcomes. First, we detail the key features of phagocytosis, including the main receptors and signaling hallmarks associated with different phagocytic processes. We then discuss how the initial events of phagosome formation and cytoskeletal remodeling might be associated with known sepsis features, such as a cytokine-driven hyperinflammatory response and immunosuppression. Finally, we highlight the unresolved mechanisms of sepsis development and progression and the need for cross-disciplinary approaches to link the clinical complexity of the disease with basic cellular and molecular mechanisms.

Does Helium Pneumoperitoneum Reduce the Hyperinflammatory Response in Septic Animals during Laparoscopy?

Background/Aim. An exacerbated reaction to peritoneal infection and attendant surgical procedures is characterized by an intense hyperinflammatory state, the magnitude of which is proportional to the severity of tissue injury. Laparoscopy generates lower levels of tissue damage compared with open surgery and should induce less pronounced immune responses. The aim of this study was to determine whether laparoscopy assisted by helium rather than carbon dioxide pneumoperitoneum would induce an attenuated inflammatory state in septic animals. Materials and Methods. Thirty-two Wistar rats were divided randomly into four equal groups, two of which were submitted to carbon dioxide or helium pneumoperitoneum-assisted laparoscopic cecal ligation and puncture (CLP) induced sepsis and subsequent abdominal lavage. Two control groups were submitted to identical laparoscopic procedures with carbon dioxide or helium as insufflator gas but without CLP. After 24 hours, serum levels of tumor necrosis factor alpha (TNF-α), interleukins 1 and 6 (IL-1 and IL-6, respectively), and cortisol were determined.

GTS-21 ameliorates polymicrobial sepsis-induced hepatic injury by modulating autophagy through α7nAchRs in mice

BACKGROUND

Previous studies showed that GTS-21, a selective alpha 7 nAchR agonist, can trigger anti-inflammatory effects and improve the survival of septic animals. However, whether GTS-21 affects autophagy responses remains unclear. Here, we tested the hypothesis that GTS-21 ameliorates sepsis-induced hepatic injury by modulating autophagy in mice.

METHOD

C57BL/6 male mice were randomly separated and categorized into four groups: the sham group, and CLP group subjected to caecal ligation and puncture (CLP, a model of polymicrobial sepsis). The CLP + GTS-21 group was administered GTS-21 immediately after CLP challenge. α-Bungarotoxin (an alpha 7 nAchR antagonist) was injected before CLP was performed, and then, after CLP challenge, GTS-21 was administered to α-BGT + CLP + GTS-21 group. The hepatic tissue and blood samples were harvested 6 h after the operation.

RESULTS

CLP challenge increased TNF-α and IL-6 production, and hepatic enzyme alanine aminotransferase and aspartate transaminase levels. CLP also elevated the expression of hepatic LC3-II, sequestosome-1/p62, Atg7 and Atg5. The administration of GTS-21 inhibited pro-inflammatory cytokine production and hepatic enzymatic marker expression, promoted the expression of LC3-II, Atg7, Atg5, and decreased the expression of p62, which could be reversed by α-BGT treatment.

CONCLUSION

Our findings suggested that α7nAchR is involved in diminishing hepatic damage by inhibiting inflammatory responses and improving autophagy in mice with polymicrobial sepsis.

Post-sepsis syndrome - an evolving entity that afflicts survivors of sepsis

BACKGROUND

The sequelae of sepsis were once thought to be independent of sepsis itself and assumed to be either comorbid to sick patients or complications of critical illness. Recent studies have reported consistent patterns of functional disabilities in sepsis survivors that can last from months to years after symptoms of active sepsis had resolved. BODY: Post-sepsis syndrome is an emerging pathological entity that has garnered significant interest amongst clinicians and researchers over the last two decades. It is marked by a significantly increased risk of death and a poor health-related quality of life associated with a constellation of long-term effects that persist following the patient's bout with sepsis. These include neurocognitive impairment, functional disability, psychological deficits, and worsening medical conditions.

CONCLUSION

This "post-sepsis syndrome" has been the subject of active preclinical and clinical research providing new mechanistic insights and approaches linked to survivor well-being. Here we review important aspects of these research efforts and goals of care for patients who survive sepsis.

A longitudinal study highlights shared aspects of the transcriptomic response to cardiogenic and septic shock

Background

Septic shock (SS) and cardiogenic shock (CS) are two types of circulatory shock with a different etiology. Several studies have described the molecular alterations in SS patients, whereas the molecular factors involved in CS have been poorly investigated. We aimed to assess in the whole blood of CS and SS patients, using septic patients without shock (SC) as controls, transcriptomic modifications that occur over 1 week after ICU admission and are common to the two types of shock.

Methods

We performed whole blood RNA sequencing in 21 SS, 11 CS, and 5 SC. In shock patients, blood samples were collected within 16 h from ICU admission (T1), 48 h after ICU admission (T2), and at day 7 or before discharge (T3). In controls, blood samples were available at T1 and T2. Gene expression changes over time have been studied in CS, SS, and SC separately with a paired analysis. Genes with p value < 0.01 (Benjamini-Hochberg multiple test correction) were defined differentially expressed (DEGs). We used gene set enrichment analysis (GSEA) to identify the biological processes and transcriptional regulators significantly enriched in both types of shock.

Results

In both CS and SS patients, GO terms of inflammatory response and pattern recognition receptors (PRRs) were downregulated following ICU admission, whereas gene sets of DNA replication were upregulated. At the gene level, we observed that alarmins, interleukin receptors, PRRs, inflammasome, and DNA replication genes significantly changed their expression in CS and SS, but not in SC. Analysis of transcription factor targets showed in both CS and SS patients, an enrichment of CCAAT-enhancer-binding protein beta (CEBPB) targets in genes downregulated over time and an enrichment of E2F targets in genes with an increasing expression trend.

Conclusions

This pilot study supports, within the limits of a small sample size, the role of alarmins, PRRs, DNA replication, and immunoglobulins in the pathophysiology of circulatory shock, either in the presence of infection or not. We hypothesize that these genes could be potential targets of therapeutic interventions in CS and SS.

Trial registration

ClinicalTrials.gov, NCT02141607. Registered 19 May 2014.

Low-dose Dexamethasone Increases Autophagy in Cerebral Cortical Neurons of Juvenile Rats with Sepsis Associated Encephalopathy

Studies have shown that a certain dose of dexamethasone can improve the survival rate of patients with sepsis, and in sepsis associated encephalopathy (SAE), autophagy plays a regulatory role in brain function. Here, we proved for the first time that small-dose dexamethasone (SdDex) can regulate the autophagy of cerebral cortex neurons in SAE rats and plays a protective role. Cortical neurons were cultured in vitro in a septic microenvironment and a sepsis rat model was established. The small-dose dexamethasone (SdDex) or high-dose dexamethasone (HdDex) was used to intervene in neurons or SAE rats. Through fluorescence microscopy and western blot analysis, the expressions of microtubule-associated protein 1 light chain 3 (LC3), p62/sequestosome1 (p62/SQSTM1), mammalian target of rapamycin (mTOR) signaling pathway related proteins, and apoptosis-related proteins were detected. Theresultsshowthat compared with those in SAE rats, the cortical pathological changes in SAE rats treated with SdDex were improved, and damaged substances were encapsulated and degraded by autophagosomes in neurons. Additionally, similar to neurons in vitro, cortical autophagy was further activated and the mTOR signaling pathway was inhibited. After HdDex treatment, the mTOR signaling pathway in cortex is inhibited, but further activation of autophagy is not obvious, the cortical pathological changes were further worsened and the ultrastructure of neurons was disturbed. Furthermore, the HdDex group exhibited the most obvious apoptosis. SdDex can regulate autophagy of cortical neurons by inhibiting the mTOR signaling pathway and plays a protective role. Brain damage induced by HdDex may be related to the activation of apoptosis.

Surviving Sepsis Campaign: Research Priorities for Sepsis and Septic Shock

OBJECTIVE

To identify research priorities in the management, epidemiology, outcome and underlying causes of sepsis and septic shock.

DESIGN

A consensus committee of 16 international experts representing the European Society of Intensive Care Medicine and Society of Critical Care Medicine was convened at the annual meetings of both societies. Subgroups had teleconference and electronic-based discussion. The entire committee iteratively developed the entire document and recommendations.

METHODS

Each committee member independently gave their top five priorities for sepsis research. A total of 88 suggestions (Supplemental Table 1, Supplemental Digital Content 2, http://links.lww.com/CCM/D636) were grouped into categories by the committee co-chairs, leading to the formation of seven subgroups: infection, fluids and vasoactive agents, adjunctive therapy, administration/epidemiology, scoring/identification, post-intensive care unit, and basic/translational science. Each subgroup had teleconferences to go over each priority followed by formal voting within each subgroup. The entire committee also voted on top priorities across all subgroups except for basic/translational science.

RESULTS

The Surviving Sepsis Research Committee provides 26 priorities for sepsis and septic shock. Of these, the top six clinical priorities were identified and include the following questions: 1) can targeted/personalized/precision medicine approaches determine which therapies will work for which patients at which times?; 2) what are ideal endpoints for volume resuscitation and how should volume resuscitation be titrated?; 3) should rapid diagnostic tests be implemented in clinical practice?; 4) should empiric antibiotic combination therapy be used in sepsis or septic shock?; 5) what are the predictors of sepsis long-term morbidity and mortality?; and 6) what information identifies organ dysfunction?

CONCLUSIONS

While the Surviving Sepsis Campaign guidelines give multiple recommendations on the treatment of sepsis, significant knowledge gaps remain, both in bedside issues directly applicable to clinicians, as well as understanding the fundamental mechanisms underlying the development and progression of sepsis. The priorities identified represent a roadmap for research in sepsis and septic shock.

Prompt Administration of Antibiotics and Fluids in the Treatment of Sepsis: A Murine Trial

OBJECTIVES

Sepsis, the acute organ dysfunction caused by a dysregulated host response to infection, poses a serious public health burden. Current management includes early detection, initiation of antibiotics and fluids, and source control as necessary. Although observational data suggest that delays of even a few hours in the initiation of antibiotics or IV fluids is associated with survival, these findings are controversial. There are no randomized data in humans, and prior animal studies studied time from experimental manipulation, not from the onset of clinical features of sepsis. Using a recently developed murine cecal ligation and puncture model that precisely monitors physiologic deterioration, we hypothesize that incremental hourly delays in the first dose of antibiotics, in the first bolus of fluid resuscitation, or a combination of the two at a clinically relevant point of physiologic deterioration during polymicrobial sepsis will shorten survival.

DESIGN

Randomized laboratory animal experimental trial.

SETTING

University basic science laboratory.

SUBJECTS

Male C57BL/6J, female C57BL/6J, aged (40-50 wk old) male C57BL/6J, and BALB/C mice.

INTERVENTIONS

Mice (n = 200) underwent biotelemetry-enhanced cecal ligation and puncture and were randomized after meeting validated criteria for acute physiologic deterioration. Treatment groups consisted of a single dose of imipenem/cilastatin, a single bolus of 30 mL/kg fluid resuscitation, or a combination of the two. Mice were allocated to receive treatment at the time of meeting deterioration criteria, after a 2-hour delay or after a 4-hour delay.

MEASUREMENTS AND MAIN RESULTS

Hourly delays in the initiation of antibiotic therapy led to progressively shortened survival in our model (p < 0.001). The addition of fluid resuscitation was unable to rescue animals, which received treatment 4 hours after meeting enrollment criteria. Systemic inflammation was increased, and host physiology was increasingly deranged with hourly delays to antibiotics.

CONCLUSIONS

We conclude that antibiotic therapy is highly time sensitive, and efforts should be made to deliver this critical therapy as early as possible in sepsis, perhaps extending into the first point of medical contact outside the hospital.

The Role of Autophagy in Sepsis: Protection and Injury to Organs

Sepsis is a systemic inflammatory disease with infection, and autophagy has been shown to play an important role in sepsis. This review summarizes the main regulatory mechanisms of autophagy in sepsis and its latest research. Recent studies have shown that autophagy can regulate innate immune processes and acquired immune processes, and the regulation of autophagy in different immune cells is different. Mitophagy can select damaged mitochondria and remove it to deal with oxidative stress damage. The process of mitophagy is regulated by other factors. Non-coding RNA is also an important factor in the regulation of autophagy. In addition, more and more studies in recent years have shown that autophagy plays different roles in different organs. It tends to be protective in the lungs, heart, kidneys, and brain, and tends to be damaging in skeletal muscle. We also mentioned that some drugs can regulate autophagy. The process of modulating autophagy through drug intervention appears to be a new potential hope for the treatment of sepsis.

α-Mangostin suppresses NLRP3 inflammasome activation via promoting autophagy in LPS-stimulated murine macrophages and protects against CLP-induced sepsis in mice

BACKGROUND

The major mechanism of sepsis is immunosuppression caused by host response dysfunction. It has been found that α-Mangostin (α-M) is a potential candidate as a treatment for multiple inflammatory and immune disorders. To date, the role of α-M in host response during sepsis remains unexplored.

METHODS AND RESULTS

Herein, we examined the effect of α-M on macrophages-mediated host response in the presence of lipopolysaccharide (LPS), and the vital organ function, inflammatory response, and survival rate in septic mice. In murine peritoneal macrophages, α-M induced autophagy and then inhibited LPS-stimulated NLRP3 inflammasome activation, as well as interleukin-1β (IL-1β) production. Moreover, α-M improved phagocytosis and killing of macrophages, and increased M2 macrophages numbers after LPS stimulation. Furthermore, in vivo experiment suggested that α-M reduced serum levels of tumor necrosis factor-α (TNF-α), interferon-γ (IFN-γ), IL-1β, alanine transaminase (ALT), aspartate transaminase (AST), and creatinine (Cr), whilst increased that of interleukin-10 (IL-10) in caecal ligation and puncture (CLP) mice.

CONCLUSION

Taken together, these findings showed that α-M-mediated macrophages autophagy contributed to NLRP3 inflammasome inactivation and α-M exerted organ protection in septic mice.

Integrating molecular pathogenesis and clinical translation in sepsis-induced acute respiratory distress syndrome

Sepsis-induced acute respiratory distress syndrome (ARDS) has high morbidity and mortality and arises after lung infection or infection at extrapulmonary sites. An aberrant host response to infection leads to disruption of the pulmonary alveolar-capillary barrier, resulting in lung injury characterized by hypoxemia, inflammation, and noncardiogenic pulmonary edema. Despite increased understanding of the molecular biology underlying sepsis-induced ARDS, there are no targeted pharmacologic therapies for this devastating condition. Here, we review the molecular underpinnings of sepsis-induced ARDS with a focus on relevant clinical and translational studies that point toward novel therapeutic strategies.

Viral Sepsis in Children

Sepsis in children is typically presumed to be bacterial in origin until proven otherwise, but frequently bacterial cultures ultimately return negative. Although viruses may be important causative agents of culture-negative sepsis worldwide, the incidence, disease burden and mortality of viral-induced sepsis is poorly elucidated. Consideration of viral sepsis is critical as its recognition carries implications on appropriate use of antibacterial agents, infection control measures, and, in some cases, specific, time-sensitive antiviral therapies. This review outlines our current understanding of viral sepsis in children and addresses its epidemiology and pathophysiology, including pathogen-host interaction during active infection. Clinical manifestation, diagnostic testing, and management options unique to viral infections will be outlined.

Metabolic Flexibility as an Adaptation to Energy Resources and Requirements in Health and Disease

The ability to efficiently adapt metabolism by substrate sensing, trafficking, storage, and utilization, dependent on availability and requirement, is known as metabolic flexibility. In this review, we discuss the breadth and depth of metabolic flexibility and its impact on health and disease. Metabolic flexibility is essential to maintain energy homeostasis in times of either caloric excess or caloric restriction, and in times of either low or high energy demand, such as during exercise. The liver, adipose tissue, and muscle govern systemic metabolic flexibility and manage nutrient sensing, uptake, transport, storage, and expenditure by communication via endocrine cues. At a molecular level, metabolic flexibility relies on the configuration of metabolic pathways, which are regulated by key metabolic enzymes and transcription factors, many of which interact closely with the mitochondria. Disrupted metabolic flexibility, or metabolic inflexibility, however, is associated with many pathological conditions including metabolic syndrome, type 2 diabetes mellitus, and cancer. Multiple factors such as dietary composition and feeding frequency, exercise training, and use of pharmacological compounds, influence metabolic flexibility and will be discussed here. Last, we outline important advances in metabolic flexibility research and discuss medical horizons and translational aspects.

Surviving sepsis campaign: research priorities for sepsis and septic shock

Objective

To identify research priorities in the management, epidemiology, outcome and underlying causes of sepsis and septic shock.

Design

A consensus committee of 16 international experts representing the European Society of Intensive Care Medicine and Society of Critical Care Medicine was convened at the annual meetings of both societies. Subgroups had teleconference and electronic-based discussion. The entire committee iteratively developed the entire document and recommendations.

Methods

Each committee member independently gave their top five priorities for sepsis research. A total of 88 suggestions (ESM 1 - supplemental table 1) were grouped into categories by the committee co-chairs, leading to the formation of seven subgroups: infection, fluids and vasoactive agents, adjunctive therapy, administration/epidemiology, scoring/identification, post-intensive care unit, and basic/translational science. Each subgroup had teleconferences to go over each priority followed by formal voting within each subgroup. The entire committee also voted on top priorities across all subgroups except for basic/translational science.

Results

The Surviving Sepsis Research Committee provides 26 priorities for sepsis and septic shock. Of these, the top six clinical priorities were identified and include the following questions: (1) can targeted/personalized/precision medicine approaches determine which therapies will work for which patients at which times?; (2) what are ideal endpoints for volume resuscitation and how should volume resuscitation be titrated?; (3) should rapid diagnostic tests be implemented in clinical practice?; (4) should empiric antibiotic combination therapy be used in sepsis or septic shock?; (5) what are the predictors of sepsis long-term morbidity and mortality?; and (6) what information identifies organ dysfunction?

Conclusions

While the Surviving Sepsis Campaign guidelines give multiple recommendations on the treatment of sepsis, significant knowledge gaps remain, both in bedside issues directly applicable to clinicians, as well as understanding the fundamental mechanisms underlying the development and progression of sepsis. The priorities identified represent a roadmap for research in sepsis and septic shock.

Electronic supplementary material

The online version of this article (10.1007/s00134-018-5175-z) contains supplementary material, which is available to authorized users.

Similar Metabolic, Innate Immunity, and Adipokine Profiles in Adult and Pediatric Sepsis Versus Systemic Inflammatory Response Syndrome-A Pilot Study

OBJECTIVES

To examine whether the septic profiles of heat shock protein 72, heat shock protein 90α, resistin, adiponectin, oxygen consumption, CO2 production, energy expenditure, and metabolic pattern, along with illness severity, nutritional, and inflammatory indices, differ between adult and pediatric patients compared with systemic inflammatory response syndrome and healthy controls. To evaluate whether these biomolecules may discriminate sepsis from systemic inflammatory response syndrome in adult and pediatric patients.

DESIGN

Prospective cohort study.

SETTING

University ICU and PICU.

PATIENTS

Seventy-eight adults (sepsis/23; systemic inflammatory response syndrome/23; healthy controls/33), 67 children (sepsis/18; systemic inflammatory response syndrome/23; controls/27), mechanically ventilated.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Flow cytometry determined mean fluorescence intensity for monocyte or neutrophil heat shock protein expression. Resistin, adiponectin, and extracellular heat shock proteins were measured using enzyme-linked immunosorbent assay; energy expenditure by E-COVX (GE Healthcare). Genomic DNA was extracted with PureLink Genomic DNA kit (Invitrogen, Carlsbad, CA) to detect heat shock protein 72 single nucleotide polymorphisms. Similarly, in adult and pediatric patients, Acute Physiology and Chronic Evaluation-II/Acute Physiology and Pediatric Risk of Mortality-III, Simplified Acute Physiology Score-III, C-reactive protein, lactate, and resistin were higher and myocardial contractility, monocyte heat shock protein 72, oxygen consumption, CO2 production, energy expenditure, metabolic pattern, glucose, and albumin lower in sepsis compared with systemic inflammatory response syndrome or controls (p < 0.05). For discriminating sepsis from systemic inflammatory response syndrome, resistin, extracellular heat shock protein 90α, and lactate achieved a receiver operating characteristic curve greater than 0.80 in children and greater than 0.75 in adults (p < 0.05). In both, adults and children, genotype heat shock protein 72 analysis did not disclose any diagnosis or mortality group differences regarding either rs6457452 or rs1061581 haplotypes.

CONCLUSIONS

Sepsis presents with similar profiles in adult and pediatric patients, characterized by enhanced inflammatory hormonal response and by repressed innate immunity, metabolism, and myocardial contractility. These features early distinguish sepsis from systemic inflammatory response syndrome across all age groups.

Apigenin Alleviates Endotoxin-Induced Myocardial Toxicity by Modulating Inflammation, Oxidative Stress, and Autophagy

Apigenin, a component in daily diets, demonstrates antioxidant and anti-inflammatory properties. Here, we intended to explore the mechanism of apigenin-mediated endotoxin-induced myocardial injury and its role in the interplay among inflammation, oxidative stress, and autophagy. In our lipopolysaccharide- (LPS-) induced myocardial injury model, apigenin ameliorated cardiac injury (lactate dehydrogenase (LDH) and creatine kinase (CK)), cell death (TUNEL staining, DNA fragmentation, and PARP activity), and tissue damage (cardiac troponin I (cTnI) and cardiac myosin light chain-1 (cMLC1)) and improved cardiac function (ejection fraction (EF) and end diastolic left ventricular inner dimension (LVID)). Apigenin also alleviated endotoxin-induced myocardial injury by modulating oxidative stress (nitrotyrosine and protein carbonyl) and inflammatory cytokines (TNF-α, IL-1β, MIP-1α, and MIP-2) along with their master regulator NFκB. Apigenin modulated redox homeostasis, and its anti-inflammatory role might be associated with its ability to control autophagy. Autophagy (determined by LAMP1, ATG5, and p62), its transcriptional regulator transcription factor EB (TFEB), and downstream target genes including vacuolar protein sorting-associated protein 11 (Vps11) and microtubule-associated proteins 1A/1B light chain 3B (Map1lc3) were modulated by apigenin. Thus, our study demonstrated that apigenin may lead to potential development of new target in sepsis treatment or other myocardial oxidative and/or inflammation-induced injuries.

Improved survival after induction of sepsis by cecal slurry in PD-1 knockout murine neonates

BACKGROUND

Sepsis and the ensuing immune dysfunction continue to be major contributors to neonatal morbidity and mortality. Neonatal sepsis also is associated with profound immune dysfunction. We have recently identified a role for a family of coinhibitory molecules that are altered in murine sepsis and in critically ill adult patients, which may be a target for development of novel therapies. There is, however, a paucity of data pertaining to the role of coinhibitory checkpoint proteins in the control and modulation of neonatal sepsis.

METHODS

The cecal slurry model consists of harvesting the cecal content of an adult, wild-type, male mouse and combining it with 5% dextrose to create a cecal slurry with a concentration of 80 mg/mL (LD₇₀ at 7 days). Neonatal mice (5-7 days of age) underwent intraperitoneal injection of the cecal slurry or 0.9% saline for the sham procedure. Wild-type (C57BL/6) or PD-1^-/- mice were used; a 7-day survival study was undertaken. Cytometric bead array was used for cytokine expression. Blood and peritoneal fluid was cultured for bacterial burden. Flow cytometry was used to assess the peritoneal cavity cell populations.

RESULTS

There was no mortality after the sham procedure in either wild-type or PD-1^-/- pups. PD-1 markedly affected sepsis survival with significantly improved survival in the PD-1^-/- pups (40% vs 80%; P < .01). This survival improvement was not associated with any difference in bacterial clearance. The bacterial burden was equivalent between wild-type and PD-1^-/- pups at 24 hours after cecal slurry. However, PD-1^-/- pups did display an increased circulating cytokine response to the cecal slurry compared with wild type, with increased expression of IL-6, IL-10, and TNF-α levels. Within the peritoneal cavity, sepsis induced an influx of neutrophils, a finding that was increased in PD-1^-/- pups. Although the T-cell response was unaffected by PD-1, it was noted that cecal slurry induced a loss of peritoneal B cells in WT, while the peritoneal B-cell population was preserved in PD-1^-/- pups.

CONCLUSION

Our data suggest that the checkpoint protein, PD-1, plays an important role in controlling the immune response to sepsis in the neonate, ultimately affecting sepsis-related mortality in this neonatal murine model of sepsis. Akin to adult studies, these data further emphasize the potential therapeutic target for PD-1 across a spectrum of septic patients.

[What is your diagnosis? (Cutaneous leishmaniasis)]

Neutrophils are the most abundant, short lived, and terminally differentiated leukocytes with distinct tiers of arsenals to counter pathogens. Neutrophils were traditionally considered transcriptionally inactive cells, but recent researches in the field led to a paradigm shift in neutrophil biology and revealed subpopulation heterogeneity, and functions pivotal to immunity and inflammation. Furthermore, recent unfolding of metabolic plasticity in neutrophils has challenged the long-standing concept of their sole dependence on glycolytic pathway. Metabolic adaptations and distinct regulations have been identified which are critical for neutrophil differentiation and functions. The metabolic reprogramming of neutrophils by inflammatory mediators or during pathologies such as sepsis, diabetes, glucose-6-phosphate dehydrogenase deficiency, glycogen storage diseases (GSDs), systemic lupus erythematosus (SLE), rheumatoid arthritis, and cancer are now being explored. In this review, we discuss recent developments in understanding of the metabolic regulation, that may provide clues for better management and newer therapeutic opportunities for neutrophil centric immuno-deficiencies and inflammatory disorders.