Major endothelial damage markers identified from hemadsorption filters derived from treated patients with septic shock - endoplasmic reticulum stress and bikunin may play a role.

Introduction: In septic patients the damage of the endothelial barrier is decisive leading to circulatory septic shock with disseminated vascular coagulation, edema and multiorgan failure. Hemadsorption therapy leads to rapid resolution of clinical symptoms. We propose that the isolation of proteins adsorbed to hemadsorption devices contributes to the identification of mediators responsible for endothelial barrier dysfunction. Material and methods: Plasma materials enriched to hemadsorption filters (CytoSorb®) after therapy of patients in septic shock were fractionated and functionally characterized for their effect on cell integrity, viability, proliferation and ROS formation by human endothelial cells. Fractions were further studied for their contents of oxidized nucleic acids as well as peptides and proteins by mass spectrometry. Results: Individual fractions exhibited a strong effect on endothelial cell viability, the endothelial layer morphology, and ROS formation. Fractions with high amounts of DNA and oxidized DNA correlated with ROS formation in the target endothelium. In addition, defined proteins such as defensins (HNP-1), SAA1, CXCL7, and the peptide bikunin were linked to the strongest additive effects in endothelial damage. Conclusion: Our results indicate that hemadsorption is efficient to transiently remove strong endothelial damage mediators from the blood of patients with septic shock, which explains a rapid clinical improvement of inflammation and endothelial function. The current work indicates that a combination of stressors leads to the most detrimental effects. Oxidized ssDNA, likely derived from mitochondria, SAA1, the chemokine CXCL7 and the human neutrophil peptide alpha-defensin 1 (HNP-1) were unique for their significant negative effect on endothelial cell viability. However, the strongest damage effect occurred, when, bikunin - cleaved off from alpha-1-microglobulin was present in high relative amounts (>65%) of protein contents in the most active fraction. Thus, a relevant combination of stressors appears to be removed by hemadsorption therapy which results in fulminant and rapid, though only transient, clinical restitution.

Dysfunction of the renin-angiotensin-aldosterone system in human septic shock.

Sepsis and septic shock are global healthcare problems associated with mortality rates of up to 40% despite optimal standard-of-care therapy and constitute the primary cause of death in intensive care units worldwide. Circulating biomarkers of septic shock severity may represent a clinically relevant approach to individualize those patients at risk for worse outcomes early in the course of the disease, which may facilitate early and more precise interventions to improve the clinical course. However, currently used septic shock biomarkers, including lactate, may be non-specific and have variable impact on prognosis and/or disease management. Activation of the renin-angiotensin-aldosterone system (RAAS) is likely an early event in septic shock, and studies suggest that an elevated level of renin, the early and committed step in the RAAS cascade, is a better predictor of worse outcomes in septic shock, including mortality, than the current standard-of-care measure of lactate. Despite a robust increase in renin, other elements of the RAAS, including endogenous levels of Ang II, may fail to sufficiently increase to maintain blood pressure, tissue perfusion, and protective immune responses in septic shock patients. We review the current clinical literature regarding the dysfunction of the RAAS in septic shock and potential therapeutic approaches to improve clinical outcomes.

Administration of methylene blue in septic shock: pros and cons.

Septic shock typically requires the administration of vasopressors. Adrenergic agents remain the first choice, namely norepinephrine. However, their use to counteract life-threatening hypotension comes with potential adverse effects, so that non-adrenergic vasopressors may also be considered. The use of agents that act through different mechanisms may also provide an advantage. Nitric oxide (NO) is the main driver of the vasodilation that leads to hypotension in septic shock, so several agents have been tested to counteract its effects. The use of non-selective NO synthase inhibitors has been of questionable benefit. Methylene blue, an inhibitor of soluble guanylate cyclase, an important enzyme involved in the NO signaling pathway in the vascular smooth muscle cell, has also been proposed. However, more than 25 years since the first clinical evaluation of MB administration in septic shock, the safety and benefits of its use are still not fully established, and it should not be used routinely in clinical practice until further evidence of its efficacy is available.

Development of a rectally administrable Dnase1 to treat septic shock by targeting NETs.

AIMS: Neutrophil extracellular trap (NET), which is formed by DNA threads, induces septic shock by aggravating systemic inflammation. An intravenous administration of deoxyribonuclease is regarded as a compelling modality for treating septic shock. However, alternative routes should be chosen when cutaneous veins are all collapsed due to hypotension. In this study, we genetically engineered this enzyme to develop a rectal suppository formulation to treat septic shock. MAIN METHODS: Dnase1 was mutated at two amino acid residues to increase its stability in the blood and fused with a cell-penetrating peptide CR8 to increase its absorption through the rectal mucosa, which is designated AR-CR8. The life-saving effect of AR-CR8 was evaluated in a LPS-induced shock mouse model. KEY FINDINGS: AR-CR8 was shown to remove NETs effectively in human neutrophils. When AR-CR8 was administered to the mouse rectum, the deoxyribonuclease activity in the mouse serum was significantly increased. In the LPS-induced shock model, 90 % of the control mice died over 72 h after LPS injection. In contrast, the rectal administration of AR-CR8 showed a mortality rate of 30 % by 72 h after LPS injection. The Log-rank test revealed that the survival rate is significantly higher in the AR-CR8 group. The NET markers in the mouse serum were enhanced by LPS, and significantly downregulated in the AR-CR8 group. These results suggest that AR-CR8 ameliorates LPS-induced shock by degrading NETs. SIGNIFICANCE: The engineered DNASE1 could be developed as a rectal suppository formulation to treat septic shock urgently at out-of-hospital places where no syringe is available.

PD-L1 Blockade Improves Survival in Sepsis by Reversing Monocyte Dysfunction and Immune Disorder.

Monocyte dysfunction is critical to sepsis-induced immunosuppression. Programmed death ligand-1 (PD-L1) has shown a close relationship with inflammatory disorder among animal models and patients. We aimed to investigate the potential beneficial immunologic mechanisms of anti-PD-L1 on monocyte dysfunction of mice with sepsis. Firstly, we assessed the potential association between PD-L1 expression on monocyte subsets and sepsis severity as well as 28-day mortality. In this study, 52 septic patients, 28 septic shock patients, and 40 healthy controls were enrolled and their peripheral whole blood was examined by flow cytometry. Then, cecal ligation and puncture (CLP) were performed for establishing the mouse sepsis model. Subsequently, effects of anti-PD-L1 antibody on monocyte subset, major histocompatibility complex II (MHC II) expression, cytokine production, and survival were investigated. PD-L1 expression on the classical monocytes (CD14 + + CD16 -) was significantly upregulated among septic shock patients and the 28-day death group than non-septic shock group and 28-day survival group (P < 0.05). Compared to septic mice, anti-PD-L1-treated mice had significantly elevated percentages of major histocompatibility complex (MHC) II on peripheral Ly6chi monocyte at 24 h after CLP. Our results showed that the anti-PD-L1 antibody markedly decreased the level of serum inflammatory cytokines interleukin (IL)-6, tumor necrosis factor (TNF)-α, and IL-10 in sepsis mice at 24 h, 48 h, and 72 h, respectively (P < 0.05). The survival rate of CLP mice was significantly improved by anti-PD-L1 antibody treatment. Classical monocytes with high expression of PD-L1 were thought to be connected with sepsis progression. The PD-L1 blockade protects from sepsis, at least partially by inhibiting the reversal of monocyte dysfunction.

Immunosuppressive effects of circulating bile acids in human endotoxemia and septic shock: patients with liver failure are at risk.

BACKGROUND: Sepsis-induced immunosuppression is a frequent cause of opportunistic infections and death in critically ill patients. A better understanding of the underlying mechanisms is needed to develop targeted therapies. Circulating bile acids with immunosuppressive effects were recently identified in critically ill patients. These bile acids activate the monocyte G-protein coupled receptor TGR5, thereby inducing profound innate immune dysfunction. Whether these mechanisms contribute to immunosuppression and disease severity in sepsis is unknown. The aim of this study was to determine if immunosuppressive bile acids are present in endotoxemia and septic shock and, if so, which patients are particularly at risk. METHODS: To induce experimental endotoxemia in humans, ten healthy volunteers received 2 ng/kg E. coli lipopolysaccharide (LPS). Circulating bile acids were profiled before and after LPS administration. Furthermore, 48 patients with early (shock onset within < 24 h) and severe septic shock (norepinephrine dose > 0.4 µg/kg/min) and 48 healthy age- and sex-matched controls were analyzed for circulating bile acids. To screen for immunosuppressive effects of circulating bile acids, the capability to induce TGR5 activation was computed for each individual bile acid profile by a recently published formula. RESULTS: Although experimental endotoxemia as well as septic shock led to significant increases in total bile acids compared to controls, this increase was mild in most cases. By contrast, there was a marked and significant increase in circulating bile acids in septic shock patients with severe liver failure compared to healthy controls (61.8 µmol/L vs. 2.8 µmol/L, p = 0.0016). Circulating bile acids in these patients were capable to induce immunosuppression, as indicated by a significant increase in TGR5 activation by circulating bile acids (20.4% in severe liver failure vs. 2.8% in healthy controls, p = 0.0139). CONCLUSIONS: Circulating bile acids capable of inducing immunosuppression are present in septic shock patients with severe liver failure. Future studies should examine whether modulation of bile acid metabolism can improve the clinical course and outcome of sepsis in these patients.

Gene Co-Expression Networks Offer New Perspectives on Sepsis Pathophysiology.

Sepsis is among the most common causes of death in intensive care units. Septic shock is a type of circulatory shock that shows signs and symptoms that are similar to non-septic shock. Despite the impact of shock on patients and the economic burden, knowledge of the pathophysiology of septic shock is scarce. In this context, weighted gene co-expression network analysis can help to elucidate the molecular mechanisms of this condition. The gene expression dataset used in this study was downloaded from the Gene Expression Omnibus, which contains 80 patients with septic shock, 33 patients with non-septic shock, and 15 healthy controls. Our novel analysis revealed five gene modules specific for patients with septic shock and three specific gene modules for patients with non-septic shock. Interestingly, genes related to septic shock were mainly involved in the immune system and endothelial cells, while genes related to non-septic shock were primarily associated with endothelial cells. Together, the results revealed the specificity of the genes related to the immune system in septic shock. The novel approach developed here showed its potential to identify critical pathways for the occurrence and progression of these conditions while offering new treatment strategies and effective therapies.

Loss of TRIM24 promotes IL-10 expression via CBP/p300-dependent IFNß1 transcription during macrophage activation.

BACKGROUND: As an anti-inflammatory cytokine, interleukin 10 (IL-10) plays a vital role in preventing inflammatory and autoimmune pathologies while also maintaining immune homeostasis. IL-10 production in macrophages is tightly regulated by multiple pathways. TRIM24, a member of the Transcriptional Intermediary Factor 1 (TIF1) family, contributes to antiviral immunity and macrophage M2 polarization. However, the role of TRIM24 in regulating IL-10 expression and its involvement in endotoxic shock remains unclear. METHODS: In vitro, bone marrow derived macrophages cultured with GM-CSF or M-CSF were stimulated with LPS (100ng/ml). Murine models of endotoxic shock were established by challenging the mice with different dose of LPS (i.p). RTPCR, RNA sequencing, ELISA and hematoxylin and eosin staining were performed to elucidate the role and mechanisms of TRIM24 in endotoxic shock. RESULTS: The expression of TRIM24 is downregulated in LPS-stimulated bone marrow-derived macrophages (BMDMs). Loss of TRIM24 boosted IL-10 expression during the late stage of LPS-stimulation in macrophages. RNA-seq analysis revealed the upregulation of IFNß1, an upstream regulator of IL-10, in TRIM24 knockout macrophages. Treatment with C646, a CBP/p300 inhibitor, diminished the difference in both IFNß1 and IL-10 expression between TRIM24 knockout and control macrophages. Loss of TRIM24 provided protection against LPS-induced endotoxic shock in mice. CONCLUSION: Our results demonstrated that inhibiting TRIM24 promoted the expression of IFNß1 and IL-10 during macrophage activation, therefore protecting mice from endotoxic shock. This study offers novel insights into the regulatory role of TRIM24 in IL-10 expression, making it a potentially attractive therapeutic target for inflammatory diseases.

Enhanced Mouse Susceptibility to Endotoxin Shock after Plasmodium yoelii Infection Is Correlated with Increased Serum Levels of Lipopolysaccharide Soluble Receptors.

Sepsis is a common disease in sub-Saharan Africa and Asia, where malaria is also prevalent. To determine whether Plasmodium infection might enhance susceptibility to endotoxin shock, we used a mouse model of lipopolysaccharide (LPS) administration. Our results indicated that Plasmodium yoelii infection in mice strongly enhanced the susceptibility of the host to develop endotoxin shock. This increased susceptibility to endotoxin shock was correlated with a synergistic effect of Plasmodium and LPS on the secretion of Tumor Necrosis Factor (TNF). TNF contributed mostly to lethality after the dual challenge since neutralization with an anti-TNF antibody provided protection from death. Plasmodium infection also induced an enhancement of the serum levels of LPS soluble ligands, sCD14 and Lipopolysaccharide Binding Protein. In this regard, our data confirm that Plasmodium infection can profoundly modify responses to secondary bacteria challenges, resulting in dysregulated cytokine expression and pathological effects. If confirmed in humans, LPS soluble receptors might serve as markers of susceptibility to septic shock.

The Protective Effects of Goitrin on LPS-Induced Septic Shock in C57BL/6J Mice via Caspase-11 Non-Canonical Inflammasome Inhibition.

Septic shock is defined as a subset of sepsis, which is associated with a considerably high mortality risk. The caspase-11 non-canonical inflammasome is sensed and activated by intracellular lipopolysaccharide (LPS) leading to pyroptosis, it plays a critical role in septic shock. However, there are few known drugs that can control caspase-11 non-canonical inflammasome activation. We report here that goitrin, an alkaloid from Radix Isatidis, shows protective effects in LPS-induced septic shock and significant inhibitory effect in caspase-11 non-canonical inflammasome pathway. Male C57BL/6J were injected intraperitoneally with LPS (20 mg/kg) to induce experimental septic shock. The results demonstrated that the survival rates of mice pretreated with goitrin or Toll-like receptor 4 (TLR4) inhibitor TKA-242 increased, and LPS-induced hypothermia and lung damage improved by inhibiting inflammatory response. Elucidating the detailed mechanism, we surprisingly found goitrin is really different from TAK-242, it independent of the TLR4 signal activation, but significantly inhibited the activation of caspase-11 non-canonical inflammasome, including cleaved caspase-11 and N-terminal fragment of gasdermin D (GSDMD-NT). Furthermore, with a nonlethal dose of the TLR3 agonist poly(I:C)-primed and subsequently challenged with LPS to induce caspase-11-mediated lethal septic shock, the efficacy of goitrin had been verified. Those results revealed the effect of goitrin in protective against LPS-induced septic shock via inhibiting caspase-11 non-canonical inflammasome, which provided a new therapeutic strategy for clinical treatment of septic shock.

Characterization of a novel LTA/LPS-binding antimicrobial and anti-inflammatory temporin peptide from the skin of Fejervary limnocharis (Anura: Ranidae).

Septic shock caused by Gram-positive bacteria continues to be a major cause of morbidity and mortality in intensive care units globally. Most Temporins are excellent growth inhibitors of gram-positive bacteria and candidates for developing antimicrobial treatments due to their biological action and small molecular weight. In this study, a novel Temporin peptide from the skin of Fejervarya limnocharis frog, named as Temporin-FL, was characterized. Temporin-FL was found to adopt typical α-helical conformation in SDS solution and to exhibit selective antibacterial activity against Gram-positive bacteria through a membrane destruction mechanism. Accordingly, Temporin-FL showed protective effects against Staphylococcus aureus-induced sepsis in mice. Finally, Temporin-FL was demonstrated to exert anti-inflammatory effects by neutralizing the action of LPS/LTA and by inhibiting MAPK pathway activation. Therefore, Temporin-FL represents a novel candidate for moleculartherapy of Gram-positive bacterial sepsis.

Longitudinal NMR Based Serum Metabolomics to Track the Potential Serum Biomarkers of Septic Shock.

Background: Septic shock, with a prolonged hospital stay, has the highest mortality rate worldwide. There is a need for better management of the disease, which requires time-dependent analysis of alteration occurring in the disease condition and subsequent planning of treatment strategies to curb mortality. Objective: The study aims to identify early metabolic signatures associated with septic shock before treatment and post-treatment. It also entails the progression of patients towards recovery, which clinicians could use to analyze treatment efficacy. Methods: The study was performed on 157 serum samples of patients with septic shock. We performed metabolomic, univariate, and multivariate statistics to identify the significant metabolite signature of patients prior to treatment and during treatment by collecting serum samples on the day I, day III, and day V of treatment. Results: We identified metabotypes of patients before treatment and post-treatment. The study showed time-dependent metabolite alteration in ketone bodies, amino acids, choline, and NAG in patients undergoing treatment. Conclusion: This study illustrates the metabolite's journey in septic shock and during treatment, which may be of prospective assistance to clinicians to monitor therapeutics.

Corticosteroid-binding globulin (CBG): spatiotemporal distribution of cortisol in sepsis.

Corticosteroid-binding globulin (CBG) is a 50-60 kDa circulating glycoprotein with high affinity for cortisol. CBG is adapted for sepsis; its cortisol binding is reduced reversibly by pyrexia and acidaemia, and reduced irreversibly by neutrophil elastase (NE) cleavage, converting high cortisol-binding affinity CBG to a low affinity form. These characteristics allow for the targeted delivery of immunomodulatory cortisol to tissues at the time and body site where cortisol is required in sepsis and septic shock. In addition, high titer inflammatory cytokines in sepsis suppress CBG hepatic synthesis, increasing the serum free cortisol fraction. Recent clinical studies have highlighted the importance of CBG in septic shock, with CBG deficiency independently associated with mortality.

Long Noncoding RNA U90926 Is Induced in Activated Macrophages, Is Protective in Endotoxic Shock, and Encodes a Novel Secreted Protein.

Thousands of long noncoding RNAs are encoded in mammalian genomes, yet most remain uncharacterized. In this study, we functionally characterized a mouse long noncoding RNA named U90926. Analysis of U90926 RNA levels revealed minimal expression across multiple tissues at steady state. However, the expression of this gene was highly induced in macrophages and dendritic cells by TLR activation, in a p38 MAPK- and MyD88-dependent manner. To study the function of U90926, we generated U90926-deficient (U9-KO) mice. Surprisingly, we found minimal effects of U90926 deficiency in cultured macrophages. Given the lack of macrophage-intrinsic effect, we investigated the subcellular localization of U90926 transcript and its protein-coding potential. We found that U90926 RNA localizes to the cytosol, associates with ribosomes, and contains an open reading frame that encodes a novel glycosylated protein (termed U9-ORF), which is secreted from the cell. An in vivo model of endotoxic shock revealed that, in comparison with wild type mice, U9-KO mice exhibited increased sickness responses and mortality. Mechanistically, serum levels of IL-6 were elevated in U9-KO mice, and IL-6 neutralization improved endotoxemia outcomes in U9-KO mice. Taken together, these results suggest that U90926 expression is protective during endotoxic shock, potentially mediated by the paracrine and/or endocrine actions of the novel U9-ORF protein secreted by activated myeloid cells.

Metabolic fingerprint of patients showing responsiveness to treatment of septic shock in intensive care unit.

OBJECTIVE: An early metabolic signature associated with the responsiveness to treatment can be useful in the better management of septic shock patients. This would help clinicians in designing personalized treatment protocols for patients showing non-responsiveness to treatment. METHODS: We analyzed the serum on Day 1 (n = 60), Day 3 (n = 47), and Day 5 (n = 26) of patients with septic shock under treatment using NMR-based metabolomics. Partial least square discriminant analysis (PLS-DA) was performed to generate the list of metabolites that can be identified as potential disease biomarkers having statistical significance (that is, metabolites that had a VIP score > 1, and p value < 0.05, False discovery rate (FDR) < 0.05). RESULTS: Common significant metabolites amongst the three time points were obtained that distinguished the patients being responsive (R) and non-responsive (NR) to treatments, namely 3 hydroxybutyrate, lactate, and phenylalanine which were lower, whereas glutamate and choline higher in patients showing responsiveness. DISCUSSION: The study gave these metabolic signatures identifying patients' responsiveness to treatment. The results of the study will aid in the development of targeted therapy for ICU patients.

Pyruvate Dehydrogenase Kinase 2 Accelerates Endotoxin Shock by Promoting Mitogen-Activated Protein Kinase Activation.

Endotoxin shock remains one of the major causes of mortality worldwide. Pyruvate dehydrogenase kinase (PDK) 2 is an important regulatory enzyme involved in glucose metabolism. The purpose of this study was to determine the regulatory effect of PDK2 on LPS-induced endotoxin shock and explore the mechanisms in vivo and in vitro. Here, we showed that PDK2 contributed to Toll-like receptor (TLR)-mediated inflammation. Lipopolysaccharide (LPS) activation of TLR4 pathways resulted in PDK2 upregulation in macrophages and dendritic cells (DCs). PDK2 overexpression enhanced TLR4 signaling pathway activation, whereas downregulating PDK2 expression inhibited TLR4 signaling pathway activation. Pharmacological inhibition of PDK2 significantly decreased the mortality rate and alleviated pathological injury in the lungs and livers of LPS-challenged mice, while significantly suppressing proinflammatory cytokine production. Thus, we confirmed that PDK2 is involved in LPS-induced endotoxin shock by modulating TLR4-mitogen-activated protein kinase signaling and inducing the production of proinflammatory cytokines in macrophages and DCs. Our findings highlight the importance of PDK2 as a novel target to treat septic shock.

Inhibition of Netosis with PAD Inhibitor Attenuates Endotoxin Shock Induced Systemic Inflammation.

Neutrophils play a pivotal role in innate immunity by releasing neutrophils extracellular traps (NETs). Excessive NETs are detrimental to the local tissue and further exacerbate inflammation. Protein arginine deiminases (PAD) mediate histone citrullination and NET formation that, in turn, exacerbate endotoxin shock damages. In this study, we further investigated the molecular mechanism underlying PAD and NETs in endotoxic stress in mice. The control group mice were injected with solvent, the LPS endotoxic shock group mice were intraperitoneally injected with LPS at 35 mg/kg only, while the LPS and PAD inhibitor YW3-56 treatment group mice were injected with YW3-56 at 10 mg/kg prior to the LPS injection. YW3-56 significantly prolonged the survival time of the LPS-treated mice. NETs, cfDNA, and inflammatory factors were detected by ELISA in serum, paitoneal cavity, and lung at 24 h after LPS administration. Lung injuries were detected by immunostaining, and lung tissue transcriptomes were analyzed by RNA-seq at 24 h after LPS administration. We found that YW3-56 altered neutrophil tissue homeostasis, inhibited NET formation, and significantly decreased cytokines (IL-6, TNFα and IL-1ß) levels, cytokines gene expression, and lung tissue injury. In summary, NET formation inhibition offers a new avenue to manage inflammatory damages under endotoxic stress.

Hepcidin discriminates sepsis from other critical illness at admission to intensive care.

Initial differential diagnosis and prognosis for patients admitted to intensive care with suspected sepsis remain arduous. Hepcidin has emerged as a potential biomarker for sepsis. Here we report data on the relevance of levels of hepcidin versus other biomarkers as a diagnostic and prognostic tool for sepsis. 164 adult patients admitted to the intensive care unit (ICU) within 24 h upon arrival to the hospital were included. Blood samples collected daily for seven consecutive days and hepcidin levels, heparin binding protein (HBP) levels and standard biomarkers were determined. Blood cultures were initiated at inclusion. Clinical scores were evaluated daily and mortality after 28- and 180-days was recorded. One hundred of the patients were found to fulfil the criteria for sepsis whereas 64 did not. Hepcidin levels at admission were significantly higher in the septic than in the non-septic patients. In septic patients hepcidin levels declined significantly already at 24 h followed by a steady decline. A significant negative correlation was observed between hepcidin levels and SAPS 3 in patients with sepsis. Hepcidin levels at inclusion were significantly higher among septic patients that survived 180-days and predicted mortality. Our data show that hepcidin levels are indicative of sepsis in patients admitted to the ICU and has a prognostic value for mortality.

Venous-arterial CO2 to arterial-venous O2 content ratio in different shock types and correlation with hypoxia indicators.

Introduction: Shock is a generalized form of acute circulatory failure characterized by low tissue perfusion. If not recognized early, it highly increases patient morbidity and mortality. Central venous-arterial CO2 (Carbon dioxide) to arterial-central venous O2 (Oxygen) content ratio (Pcv-aCO2/Ca-cvO2) has been used for the early prediction of anaerobic metabolism in septic shock patients. However, knowledge about the usability of this ratio in cardiogenic shock is scarce. Materials and Methods: We retrospectively collected the data of patients admitted to our 18-bed intensive care unit (Haga Hospital, Department of Intensive Care, The Hague, The Netherlands) with a diagnosis of septic shock or cardiogenic shock in 2018. All patients who had undergone Swan-Ganz or Pulse index Continuous Cardiac Output device insertion were included in the study. The hemodynamic variables were recorded both at ICU admission and during catheterization. Result: Forty-six (n= 46) patients with a mean age of 62 ± 13 years and 52% female gender were enrolled in the study. The Acute Physiology and Chronic Health Evaluation IV (APACHE IV) score was 96 ± 39. Twenty-four patients had septic shock, and twenty-two were diagnosed with cardiogenic shock. Although Pcv-aCO2 (Central venous-arterial CO2) and ScvO2 (Central venous oxygen) were not found different between the cardiogenic and septic shock groups, the Pcv-aCO2/Ca-cvO2 ratio was significantly lower in patients with cardiogenic shock (p= 0.035). The Pcv-aCO2/Ca-cvO2 ratio had a weak correlation with ScvO2 (r= 0.21, p= 0.040). Pcv-aCO2 and ScvO2 showed negative lower moderate correlation (r= -0.40, p= 0.030). Twenty patients [nine (19%) with cardiogenic shock, and eleven (23%) with septic shock] died during their ICU or hospital stay. Although Ca-cvO2, Pcv-aCO2, and ScvO2 were not associated with mortality, a higher Pcv-aCO2/Ca-cvO2 ratio was associated with increased mortality (p= 0.035). Conclusions: The Pcv-aCO2/Ca-cvO2 ratio is a valuable hypoxia indicator in states of shock. However, cutoff levels should be identified for different shock types.

NETosis and Nucleosome Biomarkers in Septic Shock and Critical COVID-19 Patients: An Observational Study.

Background: Neutrophil extracellular traps' (NETs') formation is a mechanism of defense that neutrophils deploy as an alternative to phagocytosis, to constrain the spread of microorganisms. Aim: The aim was to evaluate biomarkers of NETs' formation in a patient cohort admitted to intensive care unit (ICU) due to infection. Methods: Forty-six septic shock patients, 22 critical COVID-19 patients and 48 matched control subjects were recruited. Intact nucleosomes containing histone 3.1 (Nu.H3.1), or citrullinated histone H3R8 (Nu.Cit-H3R8), free citrullinated histone (Cit-H3), neutrophil elastase (NE) and myeloperoxidase (MPO) were measured. Results: Significant differences in Nu.H3.1 and NE levels were observed between septic shock and critical COVID-19 subjects as well as with controls (p-values < 0.05). The normalization of nucleosome levels according to the neutrophil count improved the discrimination between septic shock and critical COVID-19 patients. The ratio of Nu.Cit-H3R8 to Nu.H3.1 allowed the determination of nucleosome citrullination degree, presumably by PAD4. Conclusions: H3.1 and Cit-H3R8 nucleosomes appear to be interesting markers of global cell death and neutrophil activation when combined. Nu.H3.1 permits the evaluation of disease severity and differs between septic shock and critical COVID-19 patients, reflecting two distinct potential pathological processes in these conditions.