DAMPs and NETs in Sepsis

Extracorporeal therapies in sepsis: a comprehensive review of the Selective Cytopheretic Device, Polymyxin B and Seraph cartridges

Sepsis, a dysregulated host response to infection, is a leading cause of morbidity and mortality in critically ill patients, despite advancements in antimicrobial therapies. Recent innovations in extracorporeal blood purification therapies, such as the Selective Cytopheretic Device (SCD), Polymyxin B Hemoperfusion Cartridge (PMX-HP), and Seraph 100 Microbind Affinity Blood Filter (Seraph), have demonstrated promising potential as adjuncts to conventional therapies. The SCD targets activated white blood cells, while PMX-HP binds endotoxins in Gram-negative sepsis. The Seraph targets a broad range of pathogens, including viruses, bacteria and fungi. Evidence from several clinical trials and observational studies indicate that these therapies can improve organ function, and potentially improve survival in patients with sepsis. Despite the strong pathophysiological rationale for using these devices in sepsis, conclusive evidence of their effectiveness remains limited. Multicenter randomized controlled trials are currently underway with each of these devices to establish their role in improving patient outcomes. Further research is needed to establish optimal protocols for their initiation, duration, and integration into standard sepsis management.

Unraveling the mechanisms of NINJ1-mediated plasma membrane rupture in lytic cell death and related diseases

Plasma membrane rupture (PMR), the ultimate event during lytic cell death, releases damage-associated molecular patterns (DAMPs) that trigger inflammation and immune responses in the development of various diseases. Recent years have witnessed significant advances in understanding the PMR mediated by ninjurin1 (NINJ1) in different lytic cell death processes. NINJ1 oligomerizes and ruptures the membrane in pyroptosis and other lytic cell death, participating in the pathogenesis of multiple diseases. Although the membrane-permeabilizing function of NINJ1 is well recognized, the role of NINJ1 in different types of lytic cell death and its impact on multiple disease processes have yet to be fully elucidated. This review summarizes the latest advances in the mechanisms of NINJ1-mediated PMR, discusses the membrane-inducing activity of NINJ1 in different lytic cell death, explains the implications of NINJ1 in lytic cell death-related diseases, and lists the inhibitory strategies for NINJ1. We expect to provide new insights into targeting NINJ1 to suppress lytic cell death for therapeutic benefit, which may become a new strategy to control inflammatory cell lysis-related diseases.

Neutrophil extracellular traps mediate pathophysiology of hepatic cells during liver injury

Neutrophil extracellular traps (NETs) are web-like, bactericidal structures produced by neutrophils and are composed principally of extracellular DNA, histones, elastase, and myeloperoxidase, among other components. NET formation is an innate immune response that is beneficial for pathogen killing and clearance. However, excessive NET formation and clearance defects can lead to inflammation and induce damage to host organs. NETs are also implicated in the development of noninfectious inflammatory disorders, such as liver injury in chronic liver diseases. The liver parenchyma contains hepatocytes, liver sinusoidal endothelial cells, Kupffer cells, and hepatic stellate cells. Each of these cells possesses unique structures and functions, and their interactions with NETs result in pathophysiological changes contributing to liver injury. This review updates the findings related to the modes of action and molecular mechanisms by which NETs modulate the pathophysiology of various hepatic cells and potentiate liver injury. The article also reviews the roles of NETs in hepatic ischemia reperfusion injury, hepatocellular carcinoma pathogenesis, and cancer metastasis. Last, we examine data to determine whether NETs induce crosstalk among various hepatic cells during liver injury and to identify future research directions.

Extracellular DNA and Deoxyribonuclease Activity as Potential Biomarkers of Inflammation in Multiple Sclerosis

Neuroinflammation plays a critical role in the pathophysiology of multiple sclerosis (MS), involving complex interactions between reactive oxygen species (ROS), cytokines, chemokines, and immune cells. Among these, neutrophils contribute to sustained inflammation through degranulation, ROS production, and the release of neutrophil extracellular traps (NETs). Extracellular DNA (ecDNA), a key component of NETs, may act as an autoantigen, promoting chronic inflammation and tissue damage. Additionally, impaired NETs and ecDNA degradation by deoxyribonucleases (DNases) may contribute to persistence of inflammation. The aim of the present study was to determine the levels of ecDNA and DNase activity in both blood plasma and cerebrospinal fluid (CSF) in newly diagnosed, treatment-naïve adult patients with relapsing-remitting MS and whether it correlates with disease severity and inflammatory activity in MS. Fifty-one treatment-naïve relapsing-remitting MS patients without disease-modifying therapy and 16 healthy controls (HC) were included in our study. Blood and CSF samples were analyzed for ecDNA, mitochondrial DNA (mtDNA) levels, and DNase activity. Correlations with inflammatory cytokines, oxidative stress, MRI lesion burden, and the expanded disability status scale (EDSS) were analyzed. MS patients exhibited significantly elevated ecDNA levels and reduced DNase activity in blood plasma compared to HC. EcDNA levels positively correlated with inflammatory cytokines, oxidative stress, and disease severity (EDSS). Furthermore, ecDNA and mtDNA levels in CSF positively correlated with inflammatory gadolinium-enhancing MRI lesions. Interestingly, no DNase activity was detected in CSF in both MS patients and HC. Our findings demonstrate that MS patients exhibit significantly elevated ecDNA levels and reduced DNase activity in blood plasma, which correlate with inflammatory cytokines, oxidative stress, and disease severity (EDSS). Additionally, increased ecDNA and mtDNA levels in CSF are associated with higher inflammatory activity, as reflected by gadolinium-enhancing MRI lesions. Considering the pro-inflammatory nature of ecDNA in perpetuating sterile inflammation, these results suggest a potential role of circulating nucleic acids in MS pathogenesis. Furthermore, impaired DNase activity may contribute to the persistence of ecDNA, potentially sustaining pro-inflammatory state in MS. Nevertheless, it remains unclear whether elevated ecDNA actively contributes to neuroinflammation or simply reflects ongoing immune activation. Further research is needed to elucidate the mechanisms underlying ecDNA release and degradation and its implications in MS progression.

Parkinson's Disease: The Neurodegenerative Enigma Under the "Undercurrent" of Endoplasmic Reticulum Stress

Parkinson's disease (PD), a prevalent neurodegenerative disorder, demonstrates the critical involvement of endoplasmic reticulum stress (ERS) in its pathogenesis. This review comprehensively examines the role and molecular mechanisms of ERS in PD. ERS represents a cellular stress response triggered by imbalances in endoplasmic reticulum (ER) homeostasis, induced by factors such as hypoxia and misfolded protein aggregation, which activate the unfolded protein response (UPR) through the inositol-requiring enzyme 1 (IRE1), protein kinase R-like endoplasmic reticulum kinase (PERK), and activating transcription factor 6 (ATF6) pathways. Clinical, animal model, and cellular studies have consistently demonstrated a strong association between PD and ERS. Abnormal expression of ERS-related molecules in PD patients' brains and cerebrospinal fluid (CSF) correlates with disease progression. In animal models (e.g., Drosophila and mice), ERS inhibition alleviates dopaminergic neuronal damage. Cellular experiments reveal that PD-mimicking pathological conditions induce ERS, while interactions between ERS and mitochondrial dysfunction promote neuronal apoptosis. Mechanistically, (1) pathological aggregation of α-synuclein (α-syn) and ERS mutually reinforce dopaminergic neuron damage; (2) leucine-rich repeat kinase 2 (LRRK2) gene mutations induce ERS through thrombospondin-1 (THBS1)/transforming growth factor beta 1 (TGF-β1) interactions; (3) molecules such as Parkin and PTEN-induced kinase 1 (PINK1) regulate ERS in PD. Furthermore, ERS interacts with mitochondrial dysfunction, oxidative stress, and neuroinflammation to exacerbate neuronal injury. Emerging therapeutic strategies show significant potential, including artificial intelligence (AI)-assisted drug design targeting ERS pathways and precision medicine approaches exploring non-pharmacological interventions such as personalized electroacupuncture. Future research should focus on elucidating ERS-related mechanisms and identifying novel therapeutic targets to develop more effective treatments for PD patients, ultimately improving their quality of life.

Relationships between schizophrenia and the alarmins interleukin-33 (IL-33), soluble receptor of interleukin-33 (sST2) and the ratio IL-33/sST2. A systematic review

Schizophrenia is a multi-aetiologic disease. Inflammation have recently been involved in its pathophysiology. Recent research suggests that inflammation may be a key factor in its pathophysiology. Alarmins, interleukin-33 (IL-33), its soluble receptor sST2 and the ratio IL-33/sST2, have been investigated as neuroinflammation biomarkers. However, data on alarmins in schizophrenia remain scarce and conflicting, with findings varying across studies. The aim of this systematic review consists of analysing the relationships between IL-33, its sST2 and the ratio IL-33/sST2 in schizophrenia. The authors follow the PRISMA recommendations. The keywords IL-33 OR interleukin-33 OR sST2 OR soluble ST2 OR IL-33/sST2 were intersected with the Boolean operator AND with the key words schizophrenia OR psychosis OR psychotic disorder. The search was carried out in PubMed/MEDLINE, EMBASE, PsycInfo, Scopus and Web of Science. Despite the initial search yielding 115 publications, only five studies met inclusion criteria, comprising 107 healthy controls (HC) and 267 patients, highlighting the limited data available. IL-33 and its sST2 were significantly increased in patients with an acute relapse compared to HC, while patients in clinical remission had levels comparable to those of HC. No consistent relationship was found between antipsychotic treatment and IL-33 or sST2 levels, raising questions about the influence of medication on these markers. The quality of evidence was low to moderate (10 ± 1, with an evidence level of 3 ± 0, according to the Oxford Centre for Evidence-Based Medicine criteria). This systematic review highlights the possibility that IL-33 and sST2 play a role in the pathophysiology of schizophrenia, particularly in relation to neuroinflammation and neuronal dysfunction. However, the controversial and inconsistent findings suggest the need for larger, well-controlled studies. Additionally, the lack of mechanistic insight into how these alarmins contribute to schizophrenia pathophysiology remains a critical gap. Understanding the impact of IL-33 and sST2 on neuroinflammatory pathways could provide new therapeutic targets. Future research should also explore whether these markers can aid in early diagnosis or monitoring treatment response.

Traumatic brain injury from a peripheral axis perspective: Uncovering the roles of liver and adipose tissue in temperature regulation

Traumatic brain injury (TBI) is a major cause of death and disability worldwide. Most current treatments for TBI and other neurological disorders focus on the brain, often overlooking the significant contributions of peripheral organs to disease progression. Emerging evidence suggests that organs such as the liver and adipose tissue play crucial roles in TBI pathogenesis. The liver synthesizes lipids and proteins vital for brain function, while adipose tissue provides hormones and metabolites that influence brain activity. New research indicates that the liver and adipose tissue work in concert with the hypothalamus to regulate essential processes, such as body temperature, which become disrupted in TBI. Additionally, the brain-peripheral axis-a complex network of visceral nerve pathways, hormones, and metabolites-plays a bidirectional role in regulating brain plasticity and function. Understanding how TBI leads to dysregulation of the liver, adipose tissue, and other organs could unlock new therapeutic opportunities for treating TBI and related neurological disorders. The intricate autonomic network involving hypothalamic and enteric neurons, along with visceral nerve pathways and hormones, presents both pathological targets and therapeutic potential. We examine scientific evidence suggesting that correcting disturbances in systemic physiology could enhance the brain's capacity for healing. However, the interdependence of this autonomic network implies that treating dysfunction in one area may affect others. Therefore, we also explore the mechanisms by which diet and exercise can comprehensively impact the brain-peripheral axis, supporting the healing process. CHEMICAL COMPOUNDS: D-Fructose (PubChem CID 2723872); docosahexaenoic acid (PubChem CID 45934466); eicosapentaenoic acid (PubChem 5282847).

Neutrophil extracellular traps formation and autophagy in bongkrekic acid exposed human neutrophils

Bongkrekic acid (BKA), a less well-known foodborne toxin, has been implicated in numerous poisoning incidents. Recent studies suggest that BKA exerts an impact on the immune system, particularly on innate immunity. The release of neutrophil extracellular traps (NETs) is relatively a newly-discovered mechanism involving innate immunity. This study was designed to characterize and evaluate the effects of BKA on human NET formation. The co-localization of DNA, histones, and myeloperoxidase (MPO) was determined via immunostaining to confirm BKA-triggered NET formation in human neutrophils. NET quantification showed that NET formation induced by BKA was both time- and dose-dependent, and was associated with p38, ERK, PAD4 and P2X1 receptor. Moreover, immunostaining analysis observed that BKA triggered both NET formation and autophagy. Additionally, pharmacological experiments revealed that autophagy mediated BKA-triggered NET formation. Collectively, these insights offer a novel perspective on the effects of BKA exposure on host's innate immune response, and may shed new light on BKA poisoning. We call for further work to be conducted in this field to unravel the intricate mechanisms governing NET formation and autophagy in the context of BKA poisoning.

Effect of Neutrophil Elastase Inhibitor (Sivelestat Sodium) on Oxygenation in Patients with Sepsis-Induced Acute Respiratory Distress Syndrome

Objective

Neutrophil elastase (NE) plays an important role in the development of acute respiratory distress syndrome (ARDS). Sivelestat sodium, as a selective NE inhibitor, may improve the outcomes of patients with sepsis-induced ARDS in previous studies, but there is a lack of solid evidence. This trial aimed to evaluate the effect of sivelestat sodium on oxygenation in patients with sepsis-induced ARDS.

Methods

We conducted a multicenter, double-blind, randomized, placebo-controlled trial enrolling patients diagnosed with sepsis-induced ARDS admitted within 48 hours of the advent of symptoms. Patients were randomized in a 1:1 fashion to sivelestat or placebo. Trial drugs were administered as a 24-hour continuous intravenous infusion, for a minimum duration of 5 days and a maximum duration of 14 days. The primary outcome was the proportion of PaO2/FiO2 ratio improvement on Day 5 after randomization, defined by a greater than 50% improvement in PaO2/FiO2 compared with that on ICU admission or PaO2/FiO2 reached over 300 mmHg on Day 5.

Results

The study was stopped midway due to a potential between-group difference in mortality observed during the interim analysis. Overall, a total of 70 patients were randomized, of whom 34 were assigned to receive sivelestat sodium and 36 placebo. On day 5, 19/34 (55.9%) patients in the sivelestat group had PaO2/FiO2 ratio improvement compared with 7/36 (19.4%) patients in the placebo group (risk difference, 0.36; 95% CI, 0.14 to 0.56, p<0.001). The Kaplan-Meier curves showed a significantly improved 28-day survival rate in patients receiving sivelestat than those not (hazard ratio, 0.32; 95% CI, 0.11 to 0.95; p=0.041).

Conclusion

In patients with sepsis-induced ARDS, sivelestat sodium could improve oxygenation within the first five days and may be associated with decreased 28-day mortality.

The roles of neutrophils in cardiovascular diseases

The immune response plays a vital role in the development of cardiovascular diseases (CVDs). As a crucial component of the innate immune system, neutrophils are involved in the initial inflammatory response following cardiovascular injury, thereby inducing subsequent damage and promoting recovery. Neutrophils exert their functional effects in tissues through various mechanisms, including activation and the formation of neutrophil extracellular traps (NETs). Once activated, neutrophils are recruited to the site of injury, where they release inflammatory mediators and cytokines. This study discusses the main mechanisms associated with neutrophil activity and proposes potential new therapeutic targets. In this review, we systematically summarize the diverse phenotypes of neutrophils in disease regulatory mechanisms, different modes of cell death, and focus on the relevance of neutrophils to various CVDs, including atherosclerosis, acute coronary syndrome, myocardial ischemia/reperfusion injury, hypertension, atrial fibrillation, heart failure, and viral myocarditis. Finally, we also emphasize the preclinical/clinical translational significance of neutrophil-targeted strategies.

CIRP contributes to multiple organ damage in acute pancreatitis by increasing endothelial permeability

Acute pancreatitis can lead to systemic inflammation and multiple organ damage. Increased endothelial permeability is a hallmark of systemic inflammation. Several studies have demonstrated that cold-inducible RNA-binding protein (CIRP) functions as a proinflammatory factor in various diseases. However, its role in endothelial barrier dysfunction during acute pancreatitis remains unknown. To study this, acute pancreatitis was induced by two hourly intraperitoneal injections of 4.0 g/kg L-arginine in wild-type (WT) or CIRP knockout mice. Our results showed that CIRP levels in the pancreas, small intestine, lung, and liver were upregulated at 72 h after the induction of acute pancreatitis in WT mice. CIRP deficiency significantly attenuated tissue injury, edema, and extravasation of Evans blue in the pancreas, small intestine, lung, and liver at 72 h after L-arginine injection. Administration of C23, a specific antagonist of CIRP, at 2 h after the last injection of L-arginine also produced similar protective effects as CIRP knockout in mice. In vitro studies showed that recombinant CIRP caused a significant reduction in transcellular electric resistance in HUVEC monolayers. Immunocytochemical analysis of endothelial cells exposed to CIRP revealed an increased formation of actin stress fibers. VE-cadherin and β-catenin staining showed intercellular gaps were formed in CIRP-stimulated cells. Western blot analysis showed that CIRP induced SRC phosphorylation at TYR416. Exposure to the SRC inhibitor PP2 reduced CIRP-induced endothelial barrier dysfunction in HUVEC monolayers. In conclusion, blocking CIRP mitigates acute pancreatitis-induced multiple organ damage by alleviating endothelial hyperpermeability. Targeting CIRP may be a potential therapeutic option for acute pancreatitis.

Therapeutic potential of DNases in immunothrombosis: promising succor or uncertain future?

Sepsis, a life-threatening condition characterized by systemic inflammation and multiorgan dysfunction, is closely associated with the excessive formation of neutrophil extracellular traps (NETs) and the release of cell-free DNA. Both play a central role in sepsis progression, acting as major contributors to immunothrombosis and associated complications. Endogenous DNases play a pivotal role in degrading NETs and cell-free DNA, yet their activity is often dysregulated during thrombotic disease. Although exogenous DNase1 administration has shown potential in reducing NET burden and mitigating the detrimental effects of immunothrombosis, its therapeutic efficacy upon intravenous administration remains uncertain. The development of engineered DNase formulations and combination therapies may further enhance its therapeutic effectiveness by modifying its pharmacodynamic properties and avoiding the adverse effects associated with NET degradation, respectively. Although NETs are well-established targets of DNase1, it remains uncertain whether the positive effects of DNase1 on immunothrombosis are exclusively related to it's targeting of NETs or if other components contributing to immunothrombosis are also affected. This review examines the endogenous regulation of NETs in circulation and the therapeutic potential of DNases in immunothrombosis, underscoring the necessity for further investigation to optimize their clinical application.

Identification of Early Biomarkers of Mortality in COVID-19 Hospitalized Patients: A LASSO-Based Cox and Logistic Approach

This study aimed to identify possible early biomarkers of mortality among clinical and biochemical parameters, iron metabolism parameters, and cytokines detected within 24 h from admission in hospitalized COVID-19 patients. We enrolled 80 hospitalized patients (40 survivors and 40 non-survivors) with COVID-19 pneumonia and acute respiratory failure. The median time from the onset of COVID-19 symptoms to hospital admission was lower in non-survivors than survivors (p < 0.05). Respiratory failure, expressed as the ratio of arterial oxygen partial pressure to the fraction of inspired oxygen (P/F), was more severe in non-survivors than survivors (p < 0.0001). Comorbidities were similar in both groups. Among biochemical parameters and cytokines, eGFR and interleukin (IL)-1β were found to be significantly lower (p < 0.05), while LDH, IL-10, and IL-8 were significantly higher in non-survivors than in survivors (p < 0.0005, p < 0.05 and p < 0.005, respectively). Among other parameters, LDH values distribution showed the most significant difference between study groups (p < 0.0001). LASSO feature selection combined with Cox proportional hazards and logistic regression models was applied to identify features distinguishing between survivors and non-survivors. Both approaches highlighted LDH as the strongest predictor, with IL-22 and creatinine emerging in the Cox model, while IL-10, eGFR, and creatinine were influential in the logistic model (AUC = 0.744 for Cox, 0.723 for logistic regression). In a similar manner, we applied linear regression for predicting LDH levels, identifying the P/F ratio as the top predictor, followed by IL-10 and eGFR (NRMSE = 0.128). Collectively, these findings underscore LDH's critical role in mortality prediction, with P/F and IL-10 as key determinants of LDH increases in this Italian COVID-19 cohort.

Role of platelets and NETs in arterial thrombosis

Arterial thrombosis is one of the main causes of mortality and mortality worldwide. Platelets are effectively targeted by antithrombotic strategies. However, current antiplatelet agents are often associated with a bleeding risk and single antiplatelet agent may not completely prevent thrombosis. Platelets, neutrophils, and neutrophil extracellular traps (NETs) have been found to play crucial synergistic roles in the pathological process of arterial thrombosis in recent years. Platelets play a key regulatory role in the formation of NETs, and NETs can enhance platelet aggregation and activation, further aggravating the process of arterial thrombosis. Targeting the interaction mechanisms of platelets and NETs may provide a promising approach to better prevent arterial thrombosis. This review highlights the current insight in the interaction of platelets and neutrophil-forming NETs and their mechanisms involved in the process of arterial thrombosis. Finally, we discuss the potential of interventions targeting platelets and NETs to treat arterial thrombosis.

High-dose radiation induces dendritic cells maturation by promoting immunogenic cell death in nasopharyngeal carcinoma

Aim and background

Due to the radiosensitivity and deep anatomical location of nasopharyngeal carcinoma (NPC), radiotherapy serves as the cornerstone of standardized treatment for this malignancy. Beyond its cytotoxic effects, radiotherapy can serve as an immunological adjuvant by inducing immunogenic cell death (ICD). Dendritic cells (DCs), as potent antigen-presenting cells, play a critical role in tumor immunotherapy, but their exact role in the ICD process of NPC remains unclear. The effects of high-dose radiation (≥2 Gy) on DCs and the type of immune response it elicits in NPC have not been fully elucidated.

Methods

An in vitro study was conducted to assess whether ICD of NPC 5-8F cells induced by high-dose radiation could regulate the immune response of DCs. Specifically, the maturation and antigen-presenting capacity of DCs were evaluated following co-culture with NPC cells exposed to high-dose radiation.

Results

High-dose radiation was found to induce ICD in NPC 5-8F cells, as evidenced by increased pro-inflammatory factor levels and reduced anti-inflammatory factor levels in the cell culture supernatant. Co-culture with NPC cells exposed to high-dose radiation for 15 minutes significantly enhanced the expression of surface molecules on DCs, promoting their immune sensitization.

Conclusion

High-dose radiation-induced apoptosis of NPC 5-8F cells is a form of ICD, which plays an important role in regulating DC immune function. These findings provide insight into the immunomodulatory effects of radiotherapy in NPC and its potential to enhance tumor immunotherapy through DC activation.

Pulmozyme Ameliorates LPS-Induced Lung Fibrosis but Provokes Residual Inflammation by Modulating Cell-Free DNA Composition and Controlling Neutrophil Phenotype

Pulmonary fibrosis, a chronic progressive lung disorder, can be the result of previous acute inflammation-associated lung injury and involves a wide variety of inflammatory cells, causing the deposition of extracellular matrix (ECM) components in the lungs. Such lung injury is often associated with excessive neutrophil function and the formation of DNA networks in the lungs, which are also some of the most important factors for fibrosis development. Acute lung injury with subsequent fibrosis was initiated in C57Bl/6 mice by a single intranasal (i.n.) administration of LPS. Starting from day 14, human recombinant DNase I in the form of Pulmozyme for topical administration was instilled i.n. twice a week at a dose of 50 U/mouse. Cell-free DNA (cfDNA), DNase activity, and cell content were analyzed in blood serum and bronchoalveolar lavage fluid (BALF). Inflammatory and fibrotic changes in lung tissue were evaluated by histological analysis. The gene expression profile in spleen-derived neutrophils was analyzed by RT-qPCR. We demonstrated that Pulmozyme significantly reduced connective tissue expansion in the lungs. However, despite the reliable antifibrotic effect, complete resolution of inflammation in the respiratory system of mice treated with Pulmozyme was not achieved, possibly due to enhanced granulocyte recruitment and changes in the nuclear/mitochondrial cfDNA balance in the BALF. Moreover, Pulmozyme introduction caused the enrichment of the spleen-derived neutrophil population by those with an unusual phenotype, combining pro-inflammatory and anti-inflammatory features, which can also maintain lung inflammation. Pulmozyme can be considered a promising drug for lung fibrosis management; however, the therapy may be accompanied by residual inflammation.

Dysregulation of neutrophil in sepsis: recent insights and advances

Sepsis remains the leading cause of death in intensive care units. Despite newer antimicrobial and supportive therapies, specific treatments are still lacking. Neutrophils are pivotal components of the effector phase of the host immune defense against pathogens and play a crucial role in the control of infections under normal circumstances. In addition to its anti-infective effects, the dysregulation and overactivation of neutrophils may lead to severe inflammation or tissue damage and are potential mechanisms for poor prognosis in sepsis. This review focuses on recent advancements in the understanding of the functional status of neutrophils across various pathological stages of sepsis to explore the mechanisms by which neutrophils participate in sepsis progression and provide insights for the treatment of sepsis by targeting neutrophils.

Repeated positron emission tomography tracing neutrophil elastase in a porcine intensive-care sepsis model

BACKGROUND

Neutrophil granulocytes are important parts of the defence against bacterial infections. Their action is a two-edged sword, the mediators killing the intruding bacteria are at the same time causing tissue damage. Neutrophil activation is part of the dysregulated immune response to infection defining sepsis and neutrophil elastase is one of the powerful proteases causing both effects and damage. Inhibition of neutrophil elastase has been tried in sepsis and ARDS, so far with inconclusive results.

METHODS

We used positron emission tomography (PET) combined with computed tomography (CT) and the selective and specific neutrophil elastase inhibitor PET-tracer [11C]GW457427 ([11C]NES), in an intensive care unit porcine Escherichia coli sepsis model with the primary aim to visualise the biodistribution of neutrophil elastase in the initial acute phase of the septic reaction. Repeated PET-CT investigations were performed before and after induction of sepsis.

RESULTS

At baseline [11C]NES uptake was found in the bone marrow, spleen and liver. The uptake in the bone marrow was markedly increased two hours into the sepsis, whereas in spleen and liver the uptake was not as markedly changed compared to baseline. At 4 h after the sepsis induction [11C]NES in the bone marrow decreased while the uptake increased in the spleen, liver and lungs.

CONCLUSION

The neutrophil elastase PET-tracer [11C]NES is a novel and unique instrument to study the acute innate neutrophil immune response in sepsis and associated vital organ failure. We here present images and quantitative data of the neutrophil elastase distribution the first hours of acute experimental sepsis. Surprisingly, a pronounced increase of neutrophil elastase was found in the bone marrow 2 h into the sepsis reaction followed at 4 h by increase in the liver, spleen and lungs and a concomitant reduction of the tracer uptake in bone marrow.

Fate and long-lasting therapeutic effects of mesenchymal stromal/stem-like cells: mechanistic insights

A large body of evidence suggests that mesenchymal stromal cells (MSCs) are able to respond rapidly to the cytokine milieu following systemic infusion. This encounter has the potential to dictate their therapeutic efficacy (also referred to as licensing). MSCs are able to rapidly react to cellular damage by migrating to the inflamed tissue and ultimately modifying the inflammatory microenvironment. However, the limited use of MSCs in clinical practice can be attributed to a lack of understanding of the fate of MSCs in patients after administration and long term MSC-derived therapeutic activity. While the known physiological effectors of viable MSCs make a relative contribution, an innate property of MSCs as a therapeutic agent is their caspase-dependent cell death. These mechanisms may be involving the functional reprogramming of myeloid phagocytes via efferocytosis, the process by which apoptotic bodies (ABs) are identified for engulfment by both specialized and non-specialized phagocytic cells. Recent studies have provided evidence that the uptake of ABs with a distinct genetic component can induce changes in gene expression through the process of epigenetic remodeling. This phenomenon, known as 'trained immunity', has a significant impact on immunometabolism processes. It is hypothesized that the diversity of recipient cells within the inflammatory stroma adjacent to MSCs may potentially serve as a biomarker for predicting the clinical outcome of MSC treatment, while also contributing to the variable outcomes observed with MSC-based therapies. Therefore, the long-term reconstructive process of MSCs may potentially be mediated by MSC apoptosis and subsequent phagocyte-mediated efferocytosis.

The Mechanisms of Sepsis Induced Coagulation Dysfunction and Its Treatment

Sepsis is a critical condition characterized by organ dysfunction due to a dysregulated response to infection that poses significant global health challenges. Coagulation dysfunction is nearly ubiquitous among sepsis patients. Its mechanisms involve platelet activation, coagulation cascade activation, inflammatory reaction imbalances, immune dysregulation, mitochondrial damage, neuroendocrine network disruptions, and endoplasmic reticulum (ER) stress. These factors not only interact but also exacerbate one another, leading to severe organ dysfunction. This review illustrates the mechanisms of sepsis-induced coagulopathy, with a focus on tissue factor activation, endothelial glycocalyx damage, and the release of neutrophil extracellular traps (NETs), all of which are potential targets for therapeutic interventions.

Impact of antiplatelets, anticoagulants and cyclic nucleotide stimulators on neutrophil extracellular traps (NETs) and inflammatory markers during COVID-19

While the association between coronavirus disease-19 (COVID-19) and neutrophils extracellular traps (NETs) is recognized, uncertainties remain regarding its precise onset, timing of resolution and target therapy. To assess changes in inflammatory and NET markers during the first week of COVID-19 hospitalization, and the association with disease severity. "In vitro" experiments investigated the effect of antiplatelets, anticoagulants, and cyclic nucleotide stimulators on NETs release. Prospective cohort study, changes in interleukin (IL)-6, IL-8, IL-17, TNF-α, RANTES, PF4, and citrullinated-H3 (citH3) levels within each outcome group was evaluated using ANOVA. Differences between moderately ill, critically ill, and non-survivors were determined using Kruskal-Wallis and logistic regression. Healthy neutrophils were stimulated with phorbol-12-myristate-13-acetate (PMA) or COVID-19 sera and treated with unfractionated heparin (UFH), low molecular weight heparin (LMWH), aspirin (ASA), ticagrelor, cinaciguat, sildenafil, and milrinone. The proportion of NETosis was assessed using IncuCyte Cell Imager. Of the 125 patients, 40.8% had moderate COVID-19, 40.8% had critical COVID-19 but recovered, and 18.4% died. From admission to hospitalization day 8, IL-6 levels decreased in moderately and critically ill, but not in non-survivors, while citH3 levels increased in critically ill and non-survivors. IL-6, IL-8, and TNF-α levels were associated with critical and fatal COVID-19. The release of NETs by neutrophils stimulated with PMA or COVID-19 sera was decreased in the presence of ASA, UFH, LMWH and cyclic nucleotide stimulators in a dose-dependent manner. In the first week of hospitalization, NET markers rose later than inflammatory markers in severe COVID-19 cases. Cyclic nucleotide stimulators, ASA and heparin may emerge as treatment approaches as they may modulate NETosis.

Screening and Identification of Neutrophil Extracellular Trap-related Diagnostic Biomarkers for Pediatric Sepsis by Machine Learning

Neutrophil extracellular trap (NET) is released by neutrophils to trap invading pathogens and can lead to dysregulation of immune responses and disease pathogenesis. However, systematic evaluation of NET-related genes (NETRGs) for the diagnosis of pediatric sepsis is still lacking. Three datasets were taken from the Gene Expression Omnibus (GEO) database: GSE13904, GSE26378, and GSE26440. After NETRGs and differentially expressed genes (DEGs) were identified in the GSE26378 dataset, crucial genes were identified by using LASSO regression analysis and random forest analysis on the genes that overlapped in both DEGs and NETRGs. These crucial genes were then employed to build a diagnostic model. The diagnostic model's effectiveness in identifying pediatric sepsis across the three datasets was confirmed through receiver operating characteristic curve (ROC) analysis. In addition, clinical pediatric sepsis samples were collected to measure the expression levels of important genes and evaluate the diagnostic model's performance using qRT-PCR in identifying pediatric sepsis in actual clinical samples. Next, using the CIBERSORT database, the relationship between invading immune cells and diagnostic markers was investigated in more detail. Lastly, to evaluate NET formation, we measured myeloperoxidase (MPO)-DNA complex levels using ELISA. A group of five important genes (MME, BST1, S100A12, FCAR, and ALPL) were found among the 13 DEGs associated with NET formation and used to create a diagnostic model for pediatric sepsis. Across all three cohorts, the sepsis group had consistently elevated expression levels of these five critical genes as compared to the normal group. Area under the curve (AUC) values of 1, 0.932, and 0.966 indicate that the diagnostic model performed exceptionally well in terms of diagnosis. Notably, when applied to the clinical samples, the diagnostic model also showed good diagnostic capacity with an AUC of 0.898, outperforming the effectiveness of traditional inflammatory markers such as PCT, CRP, WBC, and NEU%. Lastly, we discovered that children with high ratings for sepsis also had higher MPO-DNA complex levels. In conclusion, the creation and verification of a five-NETRGs diagnostic model for pediatric sepsis performs better than established markers of inflammation.

Klebsiella pneumoniae induces dose-dependent shock, organ dysfunction, and coagulopathy in a nonhuman primate critical care model

Nonhuman primate models that closely emulate the disease course, pathogenesis, and supportive care provided to human patients in the modern intensive care unit with bacterial sepsis are urgently needed to study pathogenesis and assess novel therapies. We therefore developed a non-human primate model of septic shock that includes supportive care akin to a modern intensive care unit. In this study, we characterized pathogen kinetics and evaluated the physiologic, immunologic, and pathologic responses in this model of septic shock induced by the clinically relevant pathogen Klebsiella pneumoniae across a three-log dose range. We observed dose-dependent bacteremia and circulating levels of Klebsiella pneumoniae DNA and endotoxin. Tachycardia and hypotension occurred in all animals and the study endpoint occurred in 8 of 12 animals that were euthanized. The infused bacterial dose was significantly associated with the severity of renal insufficiency and coagulopathy. Neutrophil activation evidenced by increased CD11b expression, decreased CD62L expression, and increased circulating levels of myeloperoxidase, lactoferrin, and neutrophil extracellular traps; monocyte activation evidenced by increased circulating levels of interleukin-6, tumor necrosis factor-alpha, granulocyte-macrophage colony-stimulating factor, and monocyte chemotactic protein-1; and endothelial activation evidenced by increased circulating levels of syndecan-1 and angiopoietin-II were all consistent with human sepsis. Our model provides an opportunity to study pathogenesis and investigate novel therapeutics for the treatment of bacterial sepsis in the setting of modern supportive care.IMPORTANCEThere is currently a disconnect between the efficacy of sepsis therapies in pre-clinical animal models and human clinical trials. Therefore, developing nonhuman primate models that closely mimic human sepsis pathogenesis to study novel host-targeted therapeutics is a priority. In this study, we developed a model of septic shock with a clinically relevant bacteria (Klebsiella pneumoniae) that provides standard supportive care including mechanical ventilation, invasive hemodynamic monitoring, volume resuscitation, vasopressors, antibiotics, and steroids. In a dose-dependent manner, we observed that this model closely emulates the hemodynamic, end-organ dysfunction, and cellular and soluble responses associated with human sepsis. This validated model provides a unique opportunity to study the pathogenesis of acute septic shock and evaluate host-directed therapeutics in a large animal model that closely emulates the modern-day intensive care unit and supportive critical care.

Utilizing integrated bioinformatics and machine learning approaches to elucidate biomarkers linking sepsis to purine metabolism-associated genes

Sepsis, characterized as a systemic inflammatory response triggered by pathogen invasion, represents a continuum that may progress from mild systemic infection to severe sepsis, potentially culminating in septic shock and multiple organ dysfunction syndrome. A pivotal element in the pathogenesis and progression of sepsis involves the significant disruption of oncological metabolic networks, where cells within the pathological milieu exhibit metabolic functions that diverge from their healthy counterparts. Among these, purine metabolism plays a crucial role in nucleic acid synthesis. However, the contribution of Purine Metabolism Genes (PMGs) to the defense mechanisms against sepsis remains inadequately explored. Leveraging bioinformatics, this study aimed to identify and substantiate potential PMGs implicated in sepsis. The approach encompassed a differential expression analysis across a pool of 75 candidate PMGs. Gene Set Enrichment Analysis (GSEA) and Gene Set Variation Analysis (GSVA) were employed to assess the biological significance and pathways associated with these genes. Additionally, Lasso regression and Support Vector Machine-Recursive Feature Elimination (SVM-RFE) methodologies were implemented to identify key hub genes and evaluate the diagnostic potential of nine selected PMGs in sepsis identification. The study also examined the correlation between these hub PMGs and related genes, with validation conducted through expression level analysis using the GSE13904 and GSE65682 datasets. The study identified twelve PMGs correlated with sepsis, namely AK9, ENTPD3, NUDT16, GMPR2, PKM, RRM2B, POLR2J, POLE3, ADCY3, ADCY4, ADSSL1, and AMPD1. Functional analysis revealed their involvement in critical processes such as purine nucleotide and ribose phosphate metabolism. The diagnostic capability of these PMGs to effectively differentiate sepsis cases underscored their potential as biomarkers. This research elucidates twelve PMGs associated with sepsis, providing valuable insights into novel biomarkers for this condition and facilitating the monitoring of its progression. These findings highlight the significance of purine metabolism in sepsis pathogenesis and open avenues for further investigation into therapeutic targets.

Therapeutic targeting of neuroinflammation in methamphetamine use disorder

Methamphetamine (METH) is a highly addictive illicit psychostimulant with a significant annual fatality rate. Emerging studies highlight its role in neuroinflammation and a range of neurological disorders. This review examines the current landscape of potential drug targets for managing neuroinflammation in METH use disorders (MUDs), with a particular focus on the rationale behind targeting Toll-like receptor 4 (TLR4), the NLR family pyrin domain containing 3 (NLRP3) inflammasome, and other promising targets. Given the multifactorial neurological effects of METH, including cognitive impairment and neurodegeneration, addressing METH-induced neuroinflammation has shown considerable promise in partially mitigating the damaging effects on the central nervous system and improving behavioral outcomes. This article provides an overview of the existing understanding while charting a promising path forward for developing innovative MUD treatments, focusing on neuroinflammation as a therapeutic target. Targeting neuroinflammation in METH-induced neurological disorders shows significant promise in mitigating cognitive impairment and neurodegeneration, offering a potential therapeutic strategy for improving outcomes in MUD. While challenges remain in optimizing treatments, ongoing research into combination therapies, novel drug delivery systems, and neuroprotective agents suggests a positive outlook for more effective interventions.

TLR4 Inhibition Attenuated LPS-Induced Proinflammatory Signaling and Cytokine Release in Mouse Hearts and Cardiomyocytes

BACKGROUND

Sepsis is associated with myocardial injury and early mortality. The innate immune receptor Toll-like receptor 4 (TLR4) can recognize pathogen-associated-molecular-patterns (PAMPs) and damage-associated molecular patterns (DAMPs); the latter are released during tissue injury. We hypothesized that TLR4 inhibition reduces proinflammatory signaling and cytokine release in: (1) LPS or Escherichia coli-treated isolated mouse heart; (2) LPS-treated mouse primary adult cardiomyocytes; and (3) the isolated heart during ischemia-reperfusion.

METHODS

Isolated C57BL/6N male mouse hearts were perfused for 120 min, with either LPS, E. coli, with and without CLI-095 (TLR4 inhibitor). Primary adult mouse cardiomyocytes were treated with LPS or LPS + CLI-095. Isolated hearts, exposed to 35 min of global ischemia, were treated with either vehicle or CLI-095 during reperfusion. Infarct size was quantified by triphenyltetrazolium staining. Cytokine expression was analyzed with ELISA, western blot analysis, and qPCR.

RESULTS

In isolated hearts, E. coli increased the expression of proinflammatory cytokines (IL-6 and CXCL2), which was not attenuated with TLR4 inhibition. TLR4 inhibition reduced expression (p = 0.004) and release of IL-6 (p < 0.0001) in LPS-exposed isolated hearts. LPS activated the nuclear-factor κ-light-chain-enhancer of activated B cells signaling pathway (NF-κB) in primary adult cardiomyocytes. Moreover, TLR4 inhibition reduced LPS-induced mRNA expression and release of IL-6 in primary adult cardiomyocytes. Isolated hearts treated with CLI-095 during reperfusion after ischemia (induced DAMPs release) showed reduced infarct size (39 ± 17% to 26 ± 8%, p = 0.034) and decreased IL-6 release (p = 0.006).

CONCLUSION

Inhibition of TLR4 reduced proinflammatory signaling and cytokine release in LPS-treated and ischemia-reperfused isolated mouse hearts and in primary adult murine cardiomyocytes.

Important Role of Mitochondrial Dysfunction in Immune Triggering and Inflammatory Response in Rheumatoid Arthritis

Rheumatoid arthritis (RA) is an inflammatory autoimmune disease, primarily characterized by chronic symmetric synovial inflammation and erosive bone destruction.Mitochondria, the primary site of cellular energy production, play a crucial role in energy metabolism and possess homeostatic regulation capabilities. Mitochondrial function influences the differentiation, activation, and survival of both immune and non-immune cells involved in RA pathogenesis. If the organism experiences hypoxia, genetic predisposition, and oxidative stress, it leads to mitochondrial dysfunction, which further affects immune cell energy metabolism, synovial cell proliferation, apoptosis, and inflammatory signaling, causing the onset and progression of RA; and, mitochondrial regulation is becoming increasingly important in the treatment of RA.In this review, we examine the structure and function of mitochondria, analyze the potential causes of mitochondrial dysfunction in RA, and focus on the mechanisms by which mitochondrial dysfunction triggers chronic inflammation and immune disorders in RA. We also explore the effects of mitochondrial dysfunction on RA immune cells and osteoblasts, emphasizing its key role in the immune response and inflammatory processes in RA. Furthermore, we discuss potential biological processes that regulate mitochondrial homeostasis, which are of great importance for the prevention and treatment of RA.

Immunologic role of macrophages in sepsis-induced acute liver injury

Sepsis-induced acute liver injury (SALI), a manifestation of sepsis multi-organ dysfunction syndrome, is associated with poor prognosis and high mortality. The diversity and plasticity of liver macrophage subpopulations explain their different functional responses in different liver diseases. Kupffer macrophages, liver capsular macrophages, and monocyte-derived macrophages are involved in pathogen recognition and clearance and in the regulation of inflammatory responses, exacerbating the progression of SALI through different pathways of pyroptosis, ferroptosis, and autophagy. Concurrently, they play an important role in maintaining hepatic homeostasis and in the injury and repair processes of SALI. Other macrophages are recruited to diseased tissues under pathological conditions and are polarized into various phenotypes (mainly M1 and M2 types) under the influence of signaling molecules, transcription factors, and metabolic reprogramming, thereby exerting different roles and functions. This review provides an overview of the immune role of macrophages in SALI and discusses the multiple roles of macrophages in liver injury and repair to provide a reference for future studies.

Tumor metastasis and recurrence: The role of perioperative NETosis

Although surgical resection of tumor mass remains the mainstay of curative therapeutic management for solid tumors, accumulating studies suggest that these procedures promote tumor recurrence and metastasis. Regarded as the first immune cells to fight against infectious or inflammatory insults from surgery, neutrophils along with their ability of neutrophil extracellular traps (NETs) production has attracted much attention. A growing body of evidence suggests that NETs promote cancer metastasis by stimulating various stages, including local invasion, colonization, and growth. Therefore, we discussed the mechanism of NETosis induced by surgical stress and tumor cells, and the contribution of NETs on tumor metastasis: aid in the tumor cell migration and proliferation, evasion of immune surveillance, circulating tumor cell adhesion and establishment of a metastatic niche. Lastly, we summarized existing NET-targeting interventions, offering recent insights into potential targets for clinical intervention.

The role of neutrophil extracellular traps in Crohn's disease

Crohn's disease (CD) is an idiopathic and chronic inflammation of the gastrointestinal (GI) tract. The underlying pathogenesis of CD is multifaceted, with complex interactions between genetic predisposition, environmental triggers, and abnormalities within the immune system. Neutrophil extracellular traps (NETs) have gained significant attention as a novel component in the pathogenesis of CD. NETs are intricate structures fashioned from DNA, histones, and granule proteins, and are actively released by neutrophils to entangle and eliminate pathogenic microbes. This review article delves into the intricate role of NETs in the pathogenesis of CD. We examine how NETs may serve as a pivotal mechanism for the recruitment of immune cells to the site of inflammation. NETs are known to influence the function of epithelial cells, which line the GI tract, potentially contributing to the structural integrity and barrier dysfunction observed in CD. NETs stimulate inflammation, a hallmark of the disease, by releasing pro-inflammatory molecules and activating immune cells. We also investigate the promising therapeutic potential of targeting NETs in CD. By intercepting the formation or function of NETs, it may be possible to mitigate the chronic inflammation, reduce tissue damage, and alleviate the symptoms associated with CD. Strategies to inhibit NET formation, such as the use of DNase I and approaches to disrupt NET-mediated signaling pathways, are discussed in CD therapeutics. Understanding the detailed mechanisms of NETs is crucial for the development of targeted treatments that could potentially revolutionize the management of CD.

Could P2X7 receptor be a potencial target in neonatal sepsis?

The United Nations Inter-Agency Group for Child Mortality Estimation (UNIGME) estimates that every year 2.5 million neonates die in their first month of life, accounting for nearly one-half of deaths in children under 5 years of age. Neonatal sepsis is the third leading cause of neonatal mortality. The worldwide burden of bacterial sepsis is expected to increase in the next decades due to the lack of effective molecular therapies to replace the administration of antibiotics whose efficacy is compromised by the emergence of resistant strains. In addition, prolonged exposure to antibiotics can have negative effects by increasing the risk of infection by other organisms. With the global burden of sepsis increasing and no vaccine nor other therapeutic approaches proved efficient, the World Health Organization (WHO) stresses the need for new therapeutic targets for sepsis treatment and infection prevention (WHO, A73/32). In response to this unresolved clinical issue, the P2X7 receptor (P2X7R), a key component of the inflammatory cascade, has emerged as a potential target for treating inflammatory/infection diseases. Indeed numerous studies have demonstrated the relevance of the purinergic system as a pharmacological target in addressing immune-mediated inflammatory diseases by regulating immunity, inflammation, and organ function. In this review, we analyze key features of sepsis immunopathophysiology focusing in neonatal sepsis and on how the immunomodulatory role of P2X7R could be a potential pharmacological target for reducing the burden of neonatal sepsis.

Cell-free DNA predicts all-cause mortality of sepsis-induced acute kidney injury

Background Sepsis-induced acute kidney injury (S-AKI) is a common complication in critically ill patients. Therefore, reliable biomarkers for predicting S-AKI outcomes are necessary. Serum cell-free DNA (cfDNA) is a circulating extracellular DNA fragment used as a noninvasive screening tool for many diseases, including sepsis. This study aimed to investigate the prognostic value of cfDNA in S-AKI patients and its relationship with some other parameters.Methods A total of 89 S-AKI patients admitted to the intensive care unit (ICU) from June 2021 to December 2021 were enrolled in this study. The patients were categorized into the low cfDNA group (< 855 ng/ml) and high cfDNA group (≥ 855 ng/ml) and were followed up for three months. CfDNA was extracted from serum and quantified using Quant-iT PicoGreen dsDNA Reagent.Results Overall survival was significantly lower in the high cfDNA group than in the low cfDNA group (Log-Rank p = 0.012). Univariate Cox proportional hazard model showed that cfDNA was significantly associated with all-cause mortality (HR [hazard ratio] 2.505, 95% CI [95% confidence interval] 1.184-5.298, p = 0.016). Also, serum cfDNA was a significant risk factor for all-cause mortality after adjusting for covariates (HR 2.191, 95% CI 1.017-4.721, p = 0.045). Moreover, cfDNA was positively correlated with several baseline parameters, including serum creatine, aspartate aminotransferase, alanine aminotransferase, prothrombin time, and International Normalized Ratio.Conclusion High serum cfDNA level is associated with higher mortality among the S-AKI population, indicating that cfDNA is a valuable biomarker for S-AKI prognosis.

Risk factors for mortality in patients with sepsis on extracorporeal membrane oxygenation and/or continuous renal replacement therapy: a retrospective cohort study based on MIMIC-IV database

OBJECTIVE

This study aimed to identify risk factors for mortality in septic patients undergoing extracorporeal membrane oxygenation (ECMO) and/or continuous renal replacement therapy (CRRT).

METHODS

Data from the MIMIC-IV database were retrospectively reviewed for 24,502 septic patients treated with ECMO or CRRT between 2008 and 2019. After applying inclusion and exclusion criteria, 70 patients receiving ECMO, 513 receiving CRRT, and 22 receiving both were included in the final analysis. Univariate and multivariate stepwise Cox regression analyses were performed to identify independent risk factors for mortality. Model performance was assessed using receiver operating characteristic (ROC) curve analysis. We also provided model-agnostic explanations for each Cox regression model.

RESULTS

For septic patients on ECMO, prothrombin time (per 1-s increase, HR 1.037, 95% CI 1.007-1.068, p = .015) was the key independent risk factor. For septic patients undergoing CRRT, SOFA score (per one-point increase, HR 1.100, 95% CI 1.055-1.147, p < .001) was the most significant factor. For septic patients requiring both ECMO and CRRT, prior history of hypertension (HR 4.342, 95% CI 1.332-14.153, p = .015) was the sole independent risk factor. ROC analysis showed satisfactory model performance (AUC > 0.75).

CONCLUSION

For septic patients requiring ECMO, prothrombin time was the key independent risk factor. For those needing CRRT, SOFA score was the most significant independent risk factor. Prior history of hypertension was the primary independent risk factor for septic patients needing both CRRT and ECMO.

Sepsis-Induced Endothelial Dysfunction: Permeability and Regulated Cell Death

Sepsis is a life-threatening organ dysfunction caused by a dysregulated host response to infection. Endothelial cells (ECs) are an important cell type typically affected in sepsis, resulting in compromised barrier function and various forms of regulated cell death (RCD). However, the precise mechanisms underlying sepsis-induced EC damage remain unclear. This review summarizes the recent research progress on factors and mechanisms that may affect the permeability and RCD of ECs under septic conditions, including glycocalyx, damage-associated molecular patterns, and various forms of RCD in ECs, such as apoptosis, pyroptosis, ferroptosis, and autophagy. This review offers important insights into the underlying mechanisms of endothelial dysfunction in sepsis, aiming to contribute to developing small-molecule targeted clinical therapies.

Exosomes as novel biomarkers in sepsis and sepsis related organ failure

Sepsis, a severe and life-threatening condition arising from a dysfunctional host response to infection, presents considerable challenges to the health care system and is characterized by high mortality rates and substantial economic costs. Exosomes have garnered attention as potential diagnostic markers because of their capacity to mirror the pathophysiological milieu of sepsis. This discourse reviews the progression of sepsis classification from Sepsis 1.0 to Sepsis 3.0, highlighting the imperative for sensitive and specific biomarkers to facilitate timely diagnosis and optimize patient outcomes. Existing biomarkers, such as procalcitonin (PCT) and C-reactive protein (CRP), exhibit certain limitations, thereby prompting the quest for more dependable diagnostic indicators. Exosomal cargoes, which encompass proteins and miRNAs, present a trove of biomarker candidates, attributable to their stability, pervasive presence, and indicative nature of the disease status. The potential of exosomal biomarkers in the identification of sepsis-induced organ damage, including cardiomyopathy, acute kidney injury, and acute lung injury, is emphasized, as they provide real-time insights into cardiac and renal impairments. Despite promising prospects, hurdles persist in the standardization of exosome extraction and the need for extensive clinical trials to validate their efficacy. The combination of biomarker development and sophisticated exosome detection techniques represents a pioneering strategy in the realm of sepsis diagnosis and management, underscoring the significance of further research and clinical validation.

In response to bacteria, neutrophils release extracellular vesicles capable of initiating thrombin generation through DNA-dependent and independent pathways

Neutrophils release extracellular vesicles, and some subsets of neutrophil-derived extracellular vesicles are procoagulant. In response to Staphylococcus aureus, neutrophils produce extracellular vesicles that associate electrostatically with neutrophil extracellular traps. DNA in neutrophil extracellular traps is procoagulant, but whether neutrophil extracellular vesicles produced during bacterial challenge have similar activity is unknown. Given that extracellular vesicle activity is agonist and cell-type dependent and coagulation contributes to sepsis, we hypothesized that sepsis-causing bacteria increase production of neutrophil-derived extracellular vesicles, as well as extracellular vesicle-associated DNA, and intact extracellular vesicles and DNA cause coagulation. We recovered extracellular vesicles from neutrophils challenged with S. aureus, Staphylococcus epidermidis, Escherichia coli, and Pseudomonas aeruginosa and measured associated DNA and procoagulant activity. Extracellular vesicles from S. aureus-challenged neutrophils, which were previously characterized, displayed dose-dependent procoagulant activity as measured by thrombin generation in platelet-poor plasma. Extracellular vesicle lysis and DNase treatment reduced thrombin generation by 90% and 37%, respectively. S. epidermidis, E. coli, and P. aeruginosa also increased extracellular vesicle production and extracellular vesicle-associated extracellular DNA, and these extracellular vesicles were also procoagulant. Compared to spontaneously released extracellular vesicles, which demonstrated some ability to amplify factor XII-dependent coagulation in the presence of an activator, only extracellular vesicles produced in response to bacteria could initiate the pathway. S. aureus and S. epidermidis extracellular vesicles had more surface-associated DNA than E. coli and P. aeruginosa extracellular vesicles, and S. aureus and S. epidermidis extracellular vesicles contributed to initiation and amplification of thrombin generation in a DNA-dependent manner. However, DNA on E. coli or P. aeruginosa extracellular vesicles played no role, suggesting that neutrophils release procoagulant extracellular vesicles, which can activate the coagulation cascade through both DNA-dependent and independent mechanisms.

Neutrophil extracellular traps formation is associated with postoperative complications in congenital cardiac surgery

BACKGROUNDS

Pediatric patients with congenital heart disease (CHD) often require surgical repair using cardiopulmonary bypass. Despite advancements, mortality and complication rates remain significant.

METHODS & RESULTS

We prospectively examined 101 patients undergoing congenital cardiac surgery, identifying a mortality rate of 4.0% and a complication rate of 31.6%. Neonates and infants exhibited multiple complications more frequently. Prolonged bypass time was significantly associated with complications, with each additional 30 min increasing the odds by 1.46 times (95% CI 1.01-2.10, p = 0.042). We further investigated the involvement of damage-associated molecular pattern (DAMP) molecules by proteomics and ELISA. Plasma levels of DAMPs, including histones and high mobility group box 1 (HMGB1), were significantly elevated in the complication group. As these molecules target Toll-like receptor (TLR)2 and TLR4, mRNA expression of TLR2 and TLR4 in neutrophils was upregulated in the complication group. In vitro and in vivo analyses demonstrated that histones and HMGB1 induced the formation of neutrophil extracellular traps (NETs). This finding aligned with greater NETs formation observed at the end of CPB and during the postoperative period in neonates and infants who developed postoperative complications.

CONCLUSION

Targeting NETs and associated DAMPs may provide a novel therapeutic approach to mitigate complications in this patient population.

Radiation-induced eCIRP impairs macrophage bacterial phagocytosis

Macrophages are essential immune cells for host defense against bacterial pathogens after radiation injury. However, the role of macrophage phagocytosis in infection following radiation injury remains poorly examined. Extracellular cold-inducible RNA-binding protein is a damage-associated molecular pattern that dysregulates host immune system responses such as phagocytosis. We hypothesized that radiation-induced extracellular cold-inducible RNA-binding protein release impairs macrophage phagocytosis of bacteria. Adult healthy mice were exposed to 6.5 Gy total body irradiation. Primary peritoneal macrophages isolated from adult healthy mice were exposed to 6.5 Gy radiation. Extracellular cold-inducible RNA-binding protein-neutralizing monoclonal antibody was added to the cell culture prior to irradiation. Bacterial phagocytosis by peritoneal macrophages was assessed using pHrodo Green-labeled Escherichia coli 7 d after irradiation ex vivo and in vitro. Bacterial phagocytosis was also assessed after treatment with recombinant murine cold-inducible RNA-binding protein. Rac1 and ARP2 protein expression in cell lysates and extracellular cold-inducible RNA-binding protein levels in the peritoneal lavage were assessed by western blotting. Bacterial phagocytosis by peritoneal macrophages was significantly decreased after irradiation compared with controls ex vivo and in vitro. Rac1 and ARP2 expression in the peritoneal macrophages were downregulated after total body irradiation. Total body irradiation significantly increased extracellular cold-inducible RNA-binding protein levels in the peritoneal cavity. Recombinant murine cold-inducible RNA-binding protein significantly decreased bacterial phagocytosis in a dose-dependent manner. Extracellular cold-inducible RNA-binding protein monoclonal antibody restored bacterial phagocytosis by peritoneal macrophages after irradiation. Ionizing radiation exposure impairs bacterial phagocytosis by macrophages after irradiation. Neutralization of extracellular cold-inducible RNA-binding protein restores the phagocytic ability of macrophages after irradiation. Our findings elucidate a novel mechanism of immune dysfunction and provide a potential new therapeutic approach for limiting infection after radiation injury.

Molecular basis of sepsis: A New insight into the role of mitochondrial DNA as a damage-associated molecular pattern

Sepsis remains a critical challenge in the field of medicine, claiming countless lives each year. Despite significant advances in medical science, the molecular mechanisms underlying sepsis pathogenesis remain elusive. Understanding molecular sequelae is gaining deeper insights into the roles played by various damage-associated molecular patterns (DAMPs) and pathogen-associated molecular patterns (PAMPs) in disease pathogenesis. Among the known DAMPs, circulating cell-free mitochondrial DNA (mtDNA) garners increasing attention as a key player in the immune response during sepsis and other diseases. Mounting evidence highlights numerous connections between circulating cell-free mtDNA and inflammation, a pivotal state of sepsis, characterized by heightened inflammatory activity. In this review, we aim to provide an overview of the molecular basis of sepsis, particularly emphasizing the role of circulating cell-free mtDNA as a DAMP. We discuss the mechanisms of mtDNA release, its interaction with pattern recognition receptors (PRRs), and the subsequent immunological responses that contribute to sepsis progression. Furthermore, we discuss the forms of cell-free mtDNA; detection techniques of circulating cell-free mtDNA in various biological fluids; and the diagnostic, prognostic, and therapeutic implications offering insights into the potential for innovative interventions in sepsis management.

Combination Immunotherapy With Radiotherapy in Non-Small Cell Lung Cancer: A Review of Evidence

BACKGROUND

Radiotherapy plays a fundamental role in the treatment of patients with all stages of non-small-cell lung cancer (NSCLC). The emergence of immune checkpoint inhibitors (ICIs) has transformed the standard of care in these patients. The use of ICIs is increasingly utilized in the definitive setting as an adjunct to chemoradiotherapy or surgery and remains a vital component in the treatment of metastatic disease. Despite improvements in patient survival, the use of immunotherapy as monotherapy has shown limited overall response rates with susceptibility to resistance. Radiotherapy has been identified as a viable option to enhance the response rate to ICI and improve outcomes in NSCLC.

METHODS

We queried the English PubMed database utilizing variably combined search items including "radiation," "chemoradiation," "immune checkpoint," "immunotherapy," "stereotactic body radiotherapy," and "non-small-cell lung". We additionally searched various acceptable alternative terms for similar keywords such as "radiotherapy" in place of "radiation." These results were subsequently curated for relevance and impact on current treatment paradigms.

RESULTS

In this review, we discuss preclinical and clinical studies relating to combinatorial use of immunotherapy and radiation in NSCLC. These studies are presented in the context of early-stage, operable stage III, unresectable stage III, and metastatic disease. The majority of the data illustrate promising results regarding the additive or synergistic effects of radiation and immunotherapy with a suggestion that the timing of these treatment modalities is crucial to optimizing outcomes.

CONCLUSION

While there is now evidence regarding the favorable interplay between radiation and immunotherapy in NSCLC, there remain multiple unanswered questions which are expected to be addressed in ongoing clinical trials.

Novel nomogram for the prediction of sepsis-induced coagulopathy in the PICU: A multicentre retrospective study

INTRODUCTION

Sepsis-induced coagulopathy (SIC) is a severe complication of sepsis, characterized by poor prognosis and high mortality. However, the predictors of SIC in pediatric patients have yet to be identified. Our aim was to develop a user-friendly and efficient nomogram for predicting SIC in sepsis patients admitted to the pediatric intensive care unit (PICU).

MATERIALS AND METHODS

We screened 948 sepsis patients admitted to the PICU in three hospitals located in Shandong, China. Least absolute shrinkage and selector operation (LASSO) regression was used in the training cohort for variable selection and regularization. The selected variables were utilized to construct a nomogram for predicting the risk of SIC among sepsis patients admitted to the PICU.

RESULTS

Overall, SIC was observed in 324 (40.3 %) patients. The morbidity of SIC in sepsis patients is associated with age, fibrinogen, prothrombin time, C-reactive protein, lactate and the pediatric sequential organ failure assessment score. We developed a nomogram for the early identification of SIC in the training cohort (area under the curve [AUC] 0.869, 95 % confidence interval [CI] 0.830-0.907, sensitivity 75.7 %, specificity 84.8 %) and validation cohorts (validation cohort 1: AUC 0.854, 95 % CI 0.805-0.903, sensitivity 72.0 %, specificity 86.9 %; validation cohort 2: AUC 0.853, 95 % CI 0.796-0.910, sensitivity 70.1 %, specificity 87.8 %). The calibration plots of the nomogram demonstrated a high level of concordance in the SIC probabilities between the observed and predicted values.

CONCLUSIONS

The novel nomogram showed excellent predictive performance for the morbidity of SIC among sepsis patients admitted to the PICU, potentially assisting healthcare professionals in early identification and intervention for SIC.

Analyzing the Role of Specific Damage-Associated Molecular Patterns-Related Genes in Osteoarthritis and Investigating the Association between β-Amyloid and Apolipoprotein E Isoforms

INTRODUCTION

Osteoarthritis (OA) is a prevalent chronic joint disorder. It is characterized by an immune response that maintains a low level of inflammation throughout its progression. During OA, cartilage degradation leads to the release of damage-associated molecular patterns (DAMPs), which intensify the inflammatory response. β-Amyloid is a well-recognized DAMP in OA, can interact with APOE isoforms.

METHODS

This study identified DAMPs-related genes in OA using bioinformatics techniques. Additionally, we examined the expression levels of β-amyloid and apolipoprotein E (ApoE) isoforms by enzyme-linked immunosorbent assay.

RESULTS

We identified 10 key genes by machine learning techniques. Immune infiltration analysis revealed upregulation of various immune cell types in OA cartilage, underscoring the critical role of inflammation in OA pathogenesis. In the validation study, elevated serum levels of β-amyloid in knee osteoarthritis (KOA) patients were confirmed, showing positive correlations with ApoE2 and ApoE4. Notably, ApoE3 was identified as an independent protective factor against KOA.

CONCLUSION

In this bioinformatics analysis, we identified the DAMPs-related genes of KOA and explored their potential functions and regulatory networks. The high expression of β-amyloid in KOA was confirmed by experiments, and the correlation between β-amyloid and ApoE2, ApoE4 in KOA was revealed for the first time, this provides a new way to explore the pathogenesis of KOA and to study the therapeutic targets of KOA.

LncRNA-mRNA co-expression analysis reveals aquaporin-9-promoted neutrophil extracellular trap formation and inflammatory activation in sepsis

Sepsis is a life-threatening condition caused by an excessive inflammatory response to an infection. However, the precise regulatory mechanism of sepsis remains unclear. Using a strand-specific RNA-sequencing, we identified 115 hub differentially expressed long noncoding RNAs (lncRNAs) and 443 mRNAs in septic patients, primarily participated in crucial pathways including neutrophil extracellular trap (NET) formation and toll-like receptor signaling. Notably, NETs related gene aquaporin-9 (AQP9) and its associated lncRNAs exhibited significant upregulation in septic neutrophils. Functional experiments revealed AQP9 interacts with its lncRNAs to augment the formation of neutrophil NETs. In murine sepsis models, AQP9 inhibition with phloretin reduced proinflammatory cytokine production and lung damage. These findings provide crucial insights into the regulatory role of AQP9 in sepsis, unraveling its interaction with associated lncRNAs in transmitting downstream signals, holding promise in informing the development of novel therapeutic strategies aimed at ameliorating the debilitating effects of sepsis.

Cecal necroptosis triggers lethal cardiac dysfunction in TNF-induced severe SIRS

Tumor necrosis factor (TNF) induces systemic inflammatory response syndrome (SIRS), and severe SIRS can serve as a model for studying animal death caused by organ failure. Through strategic cecectomy, we demonstrate that necroptosis in the cecum initiates the death process in TNF-treated mice, but it is not the direct cause of death. Instead, we show that it is the cardiac dysfunction downstream of cecum damage that ultimately leads to the death of TNF-treated mice. By in vivo and ex vivo physiological analyses, we reveal that TNF and the damage-associated molecular patterns (DAMPs) released from necroptotic cecal cells jointly target cardiac endothelial cells, triggering caspase-8 activation and subsequent cardiac endothelial damage. Cardiac endothelial damage is a primary cause of the deterioration of diastolic function in the heart of TNF-treated mice. Our research provides insights into the pathophysiological process of TNF-induced lethality.

Uncovering lipid dynamics in Staphylococcus aureus osteomyelitis using multimodal imaging mass spectrometry

Osteomyelitis occurs when Staphylococcus aureus invades the bone microenvironment, resulting in a bone marrow abscess with a spatially defined architecture of cells and biomolecules. Imaging mass spectrometry and microscopy are tools that can be employed to interrogate the lipidome of S. aureus-infected murine femurs and reveal metabolic and signaling consequences of infection. Here, nearly 250 lipids were spatially mapped to healthy and infection-associated morphological features throughout the femur, establishing composition profiles for tissue types. Ether lipids and arachidonoyl lipids were altered between cells and tissue structures in abscesses, suggesting their roles in abscess formation and inflammatory signaling. Sterols, triglycerides, bis(monoacylglycero)phosphates, and gangliosides possessed ring-like distributions throughout the abscess, suggesting a hypothesized dysregulation of lipid metabolism in a population of cells that cannot be discerned with traditional microscopy. These data provide insight into the signaling function and metabolism of cells in the fibrotic border of abscesses, likely characteristic of lipid-laden macrophages.

How Do ROS Induce NETosis? Oxidative DNA Damage, DNA Repair, and Chromatin Decondensation

Neutrophil extracellular traps (NETs) are intricate, DNA-based, web-like structures adorned with cytotoxic proteins. They play a crucial role in antimicrobial defense but are also implicated in autoimmune diseases and tissue injury. The process of NET formation, known as NETosis, is a regulated cell death mechanism that involves the release of these structures and is unique to neutrophils. NETosis is heavily dependent on the production of reactive oxygen species (ROS), which can be generated either through NADPH oxidase (NOX) or mitochondrial pathways, leading to NOX-dependent or NOX-independent NETosis, respectively. Recent research has revealed an intricate interplay between ROS production, DNA repair, and NET formation in different contexts. UV radiation can trigger a combined process of NETosis and apoptosis, known as apoNETosis, driven by mitochondrial ROS and DNA repair. Similarly, in calcium ionophore-induced NETosis, both ROS and DNA repair are key components, but only play a partial role. In the case of bacterial infections, the early stages of DNA repair are pivotal. Interestingly, in serum-free conditions, spontaneous NETosis occurs through NOX-derived ROS, with early-stage DNA repair inhibition halting the process, while late-stage inhibition increases it. The intricate balance between DNA repair processes and ROS production appears to be a critical factor in regulating NET formation, with different pathways being activated depending on the nature of the stimulus. These findings not only deepen our understanding of the mechanisms behind NETosis but also suggest potential therapeutic targets for conditions where NETs contribute to disease pathology.

Glycyrrhizin inhibits LPS-induced neutrophil-like release of NETs

OBJECTIVE

To investigate the regulatory effect of glycyrrhizin (GL) on the release of neutrophil extracellular traps (NETs) from neutrophils in sepsis.

METHODS

HL-60 cells were induced to differentiate into neutrophil-like dHL-60 cells to establish a neutrophil-like sepsis model. Expression levels of high-mobility group box 1 (HMGB1), citrullinated histone H3 (Cit-H3), and Toll-like receptor 9 (TLR9) were assessed by Western blotting. Free DNA, a component of NETs, was quantified using a fluorescence microplate reader. Cellular immunofluorescence analysis was used to detect the expression of the key NETs protein, Cit-H3.

RESULTS

dHL-60 cells stimulated with 200 ng/ml LPS exhibited the highest expression of Cit-H3. The neutrophil-like sepsis model showed significantly increased levels of Cit-H3 and HMGB1. GL intervention significantly reduced the expression levels of HMGB1 and Cit-H3 and decreased the free DNA level. These findings suggest that GL decreases HMGB1 expression and NET release in the neutrophil-like sepsis model. TLR9 expression was significantly elevated in the sepsis model. Exogenous recombinant human HMGB1 protein further increased TLR9 expression, while GL inhibited this increase.

CONCLUSION

GL may inhibit NET release in sepsis through the HMGB1/TLR9 pathway.

CE9A215 (inotodiol), a lanostane-type oxysterol, mitigates LPS-induced sepsis through multifaceted mechanisms

Dysregulated host response against infection triggers sepsis that leads to multiple organ dysfunction due to uncontrolled inflammatory responses. Despite marked progress in understanding of sepsis, numerous clinical trials for treatment of sepsis have proven daunting and a new therapeutic approach is highly needed. CE9A215 (inotodiol), a fungal secondary metabolite, has been researched for its pharmacological activities and has shown potent anti-allergic effects. In this study, we evaluated the anti-inflammatory activities of CE9A215 upon lipopolysaccharide (LPS) stimulation in vivo and in vitro for the first time. CE9A215 decreased the production of interleukin (IL)-6, tumor necrosis factor alpha (TNF-α), and IL-1β in a concentration-dependent manner in LPS-stimulated RAW264.7 cells. Intriguingly, in human mast cell line LUVA, CE9A215 significantly lowered IL-4 and IL-10, and this effect could be beneficial for the clearance of bacterial infection. In addition, administration of CE9A215 improved the survival rate of LPS-stimulated mice and inhibited the pro-inflammatory cytokines, IL-6, TNF-α, and IL-1β in blood. Moreover, CE9A215 enhanced the expression levels of plasma phospholipid transfer protein (PLTP), apolipoprotein E (ApoE), and ATP-binding cassette transporter (ABCA1) in LPS-stimulated RAW246.7 cells. Liver PLTP level increased significantly in the CE9A215-administered group compared with the control group, which implies that CE9A215 promotes LPS clearance and neutralization by reverse transport of LPS by increasing the expressions of PLTP, ApoE, and ABCA1. Our results highlight CE9A215's potential as a novel therapeutic option for the treatment of sepsis.

Targeting neutrophils extracellular traps, a promising anti-thrombotic therapy for natural products from traditional Chinese herbal medicine

Thrombi are the main cause of vascular occlusion and contribute significantly to cardiovascular events and death. Neutrophils extracellular traps (NETs)-induced thrombosis plays a vital role in thrombotic complications and it takes the main responsibility for the resistance of fibrinolysis. However, the conventional anti-thrombotic therapies are inadequate to treat NETs-induced thrombotic complications but carry a high risk of bleeding. Consequently, increased attention has shifted towards exploring novel anti-thrombotic treatments targeting NETs. Interestingly, accumulating evidences prove that natural products from traditional Chinese herbal medicines have a great potential to mitigate thrombosis through inhibiting generous NETs formation and degrading excessive NETs. In this review, we elaborated the formation and degradation of NETs and highlighted its pivotal role in immunothrombosis through interactions with platelets and coagulation factors. Since available anti-thrombotic drugs targeting NETs are deficient, we further summarized the natural products and compounds from traditional Chinese herbal medicines which exert effective actions on regulating NETs formation and also have anti-thrombotic effects. Our findings underscore the diverse effects of natural products in targeting NETs, including relieving inflammation and oxidative stress of neutrophils, inhibiting neutrophils activation and DNA efflux, suppressing granule proteins release, reducing histones and promoting DNA degradation. This review aims to highlight the significance of natural medicines in anti-thrombotic therapies through targeting NETs and to lay a groundwork for developing novel anti-thrombotic agents from traditional Chinese herbal medicines.

Mechanisms of the septic heart: From inflammatory response to myocardial edema

Sepsis-induced myocardial dysfunction (SIMD), also known as sepsis-induced cardiomyopathy (SICM), is linked to significantly increased mortality. Despite its clinical importance, effective therapies for SIMD remain elusive, largely due to an incomplete understanding of its pathogenesis. Over the past five decades, research involving both animal models and human studies has highlighted several pathogenic mechanisms of SICM, yet many aspects remain unexplored. Initially thought to be primarily driven by inflammatory cytokines, current research indicates that these alone are insufficient for the development of cardiac dysfunction. Recent studies have brought attention to additional mechanisms, including excessive nitric oxide production, mitochondrial dysfunction, and disturbances in calcium homeostasis, as contributing factors in SICM. Emerging clinical evidence has highlighted the significant role of myocardial edema in the pathogenesis of SICM, particularly its association with cardiac remodeling in septic shock patients. This review synthesizes our current understanding of SIMD/SICM, focusing on myocardial edema's contribution to cardiac dysfunction and the critical role of the bradykinin receptor B1 (B1R) in altering myocardial microvascular permeability, a potential key player in myocardial edema development during sepsis. Additionally, this review briefly summarizes existing therapeutic strategies and their challenges and explores future research directions. It emphasizes the need for a deeper understanding of SICM to develop more effective treatments.