Molecular mechanisms and treatment responses of pulmonary fibrosis in severe COVID-19.

BACKGROUND: Coronavirus disease 2019 (COVID-19) patients can develop pulmonary fibrosis (PF), which is associated with impaired outcome. We assessed specific leukocytic transcriptome profiles associated with PF and the influence of early dexamethasone (DEXA) treatment on the clinical course of PF in critically ill COVID-19 patients. METHODS: We performed a pre-post design study in 191 COVID-19 patients admitted to the Intensive Care Unit (ICU) spanning two treatment cohorts: the pre-DEXA- (n = 67) and the DEXA-cohort (n = 124). PF was identified based on radiological findings, worsening of ventilatory parameters and elevated circulating PIIINP levels. Longitudinal transcriptome profiles of 52 pre-DEXA patients were determined using RNA sequencing. Effects of prednisone treatment on clinical fibrosis parameters and outcomes were analyzed between PF- and no-PF-patients within both cohorts. RESULTS: Transcriptome analyses revealed upregulation of inflammatory, coagulation and neutrophil extracellular trap-related pathways in PF-patients compared to no-PF patients. Key genes involved included PADI4, PDE4D, MMP8, CRISP3, and BCL2L15. Enrichment of several identified pathways was associated with impaired survival in a external cohort of patients with idiopathic pulmonary fibrosis. Following prednisone treatment, PF-related profiles reverted towards those observed in the no-PF-group. Likewise, PIIINP levels decreased significantly following prednisone treatment. PF incidence was 28% and 25% in the pre-DEXA- and DEXA-cohort, respectively (p = 0.61). ICU length-of-stay (pre-DEXA: 42 [29-49] vs. 18 [13-27] days, p < 0.001; DEXA: 42 [28-57] vs. 13 [7-24] days, p < 0.001) and mortality (pre-DEXA: 47% vs. 15%, p = 0.009; DEXA: 61% vs. 19%, p < 0.001) were higher in the PF-groups compared to the no-PF-groups within both cohorts. Early dexamethasone therapy did not influence these outcomes. CONCLUSIONS: ICU patients with COVID-19 who develop PF exhibit upregulated coagulation, inflammation, and neutrophil extracellular trap-related pathways as well as prolonged ICU length-of-stay and mortality. This study indicates that early dexamethasone treatment neither influences the incidence or clinical course of PF, nor clinical outcomes.

The gut microbiota composition has no predictive value for the endotoxin-induced immune response or development of endotoxin tolerance in humans invivo.

BACKGROUND: It is largely unknown whether the gut microbiome regulates immune responses in humans. We determined relationships between the microbiota composition and immunological phenotypes in 108 healthy volunteers, using 16S sequencing, an ex vivo monocyte challenge model, and an in vivo challenge model of systemic inflammation induced by lipopolysaccharide (LPS). RESULTS: Significant associations were observed between the microbiota composition and ex vivo monocytic cytokine responses induced by several stimuli, most notably IL-10 production induced by Pam3Cys, Pseudomonas aeruginosa and Candida albicans, although the explained variance was rather low (0.3-4.8%). Furthermore, a number of pairwise correlations between Blautia, Bacteroides and Prevotella genera and cytokine production induced by these stimuli were identified. LPS administration induced a profound transient in vivo inflammatory response. A second LPS challenge one week after the first resulted in a severely blunted response, reflecting endotoxin tolerance. However, no significant relationships between microbiota composition and in vivo parameters of inflammation or tolerance were found (explained variance ranging from 0.4 to 1.5%, ns). CONCLUSIONS: The gut microbiota composition explains a limited degree of variance in ex vivo monocytic cytokine responses to several pathogenic stimuli, but no relationships with the LPS-induced in vivo immune response or tolerance was observed.

The impact of ADRB2 polymorphisms on immune responses and norepinephrine-induced immunosuppression.

RATIONALE: To evaluate whether common nonsynonymous variants [single-nucleotide polymorphisms (SNPs) or SNP haplotypes] in the ß2-adrenergic receptor render subjects more susceptible to norepinephrine-induced immunosuppression and whether they are associated with dysregulated ex vivo and in vivo inflammatory responses. METHODS: Peripheral blood mononuclear cells from healthy volunteers (main cohort: n = 106, secondary cohort: n = 408) were ex vivo stimulated with various stimuli and production of cytokines was assessed. Additionally, ex vivo modulation of cytokine production by norepinephrine was evaluated in the main cohort. Volunteers from the main cohort also underwent experimental endotoxemia (administration of 1 ng/kg lipopolysaccharide), during which in vivo plasma cytokine concentrations and clinical inflammatory parameters were measured. Subjects were genotyped, common SNPs in the ADRB2 gene were extracted (rs1042711, rs1042713, and rs1042714), and the presence of haplotypes was identified (CysGlyGln, CysArgGln, and ArgGlyGlu). RESULTS: In both cohorts, presence of ADRB2 SNPs or haplotypes was not associated with altered ex vivo cytokine responses. Norepinephrine attenuated production of the proinflammatory cytokines TNF and IL-6 [-26% (-22% to -30%) and -14% (-9% to -18%), respectively, both P < 0.0001] and enhanced release of the anti-inflammatory IL-10 [+9% (+3% to +15%), P = 0.003]. These effects were not modulated by the presence of ADRB2 SNPs or haplotypes (all P values >0.37). In addition, no influence of SNPs or haplotypes on in vivo cytokine concentrations or clinical inflammatory parameters was observed (P values >0.14). CONCLUSIONS: Common nonsynonymous variants in the ADRB2 gene influence neither ex vivo cytokine production or norepinephrine-mediated immunosuppression nor the systemic in vivo inflammatory response induced by lipopolysaccharide administration in healthy volunteers.

Relationships Between Systemic Inflammation, Intestinal Damage and Postoperative Organ Dysfunction in Adults Undergoing Low-Risk Cardiac Surgery.

BACKGROUND: Approximately half of patients who undergo cardiac surgery develop systemic inflammatory response syndrome. Extracorporeal circulation and intestinal injury may play a role in this inflammatory response, although their relative contributions remain elusive. Moreover, it is largely unknown to what extent these factors contribute to cardiac surgery-induced postoperative organ dysfunction. METHOD: In this secondary analysis, we measured circulating levels of the intestinal damage marker intestinal fatty acid binding protein (I-FABP) and of the inflammatory cytokines tumour necrosis factor (TNF)-α, interleukin (IL)-6, IL-8, IL-10, IL-1RA, monocyte chemoattractant protein (MCP)-1, macrophage inflammatory protein (MIP)-1α, and MIP-1ß in 180 patients undergoing on-pump cardiac surgery. The average Z-score of levels of the different cytokines was used as an integral measure of the cytokine response. Relationships between duration of extracorporeal circulation, extent of intestinal injury, inflammation, and postoperative organ dysfunction were explored. RESULTS: Plasma I-FABP levels increased during surgery, with peak levels observed at the end of cardiopulmonary bypass (CPB). Except for TNF-α, the levels of all cytokines increased during surgery, with peak levels observed either 2 (MCP-1, MIP-1α, and MIP-1ß), 4 (IL-6, IL-8, and IL-1RA) or 6 (IL-10) hours after the end of CPB. While the duration of CPB significantly correlated with cytokine Z-score (r=0.544, p<0.05), no relationship with I-FABP levels was found. Furthermore, no significant correlations between I-FABP and cytokine levels were observed. The duration of CPB correlated with a deterioration in postoperative kidney function (estimated glomerular filtration rate [eGFR]) and troponin levels. Cytokine Z-score was associated with postoperative troponin levels, fluid administration, inotropic score, pulmonary alveolar-arterial gradient on the first postoperative morning, and deterioration of kidney function (eGFR). I-FABP levels did not correlate with any of the cardiovascular, pulmonary, or renal parameters. CONCLUSIONS: In patients undergoing low-risk cardiac surgery, the duration of CPB represents an important determinant of the systemic cytokine response, whereas both the CPB duration and the systemic inflammatory response contribute to subsequent organ dysfunction. Intestinal damage does not appear to play a relevant role in the postoperative inflammatory response and development of postoperative organ dysfunction in these patients.

Ex vivo and in vitro Monocyte Responses Do Not Reflect in vivo Immune Responses and Tolerance.

Cytokine production by ex vivo (EV)-stimulated leukocytes is commonly used to gauge immune function and frequently proposed to guide immunomodulatory therapy. However, whether EV cytokine production capacity accurately reflects the in vivo (IV) immune status is largely unknown. We investigated relationships between EV monocyte cytokine responses and IV cytokine responses in a large cohort of healthy volunteers using a highly standardized IV model of short-lived LPS-induced systemic inflammation, which captures hallmarks of both hyperinflammation and immunological tolerance. Therefore, 110 healthy volunteers were intravenously challenged with 1 ng/kg LPS twice: on day 0 to determine the extent of the IV (hyper)inflammatory response and on day 7 to determine the degree of IV endotoxin tolerance. Baseline EV monocyte cytokine production capacity was assessed prior to LPS administration. Short-term and long-term EV tolerance was assessed in monocytes isolated 4 h and 7 days after LPS administration, respectively. No robust correlations were observed between baseline EV cytokine production capacity and IV cytokine responses following LPS administration. However, highly robust inverse correlations were observed between IV cytokine responses and EV cytokine responses of monocytes isolated 4 h after IV LPS administration. No correlations between IV and EV tolerance were found. In conclusion, attenuated EV cytokine production capacity reflects ongoing IV inflammation rather than immune suppression. Results of EV assays should be interpreted with caution at the risk of improper use of immuno-stimulatory drugs.

Case-control study on the interplay between immunoparalysis and delirium after cardiac surgery.

BACKGROUND: Delirium occurs frequently following cardiothoracic surgery, and infectious disease is an important risk factor for delirium. Surgery and cardiopulmonary bypass induce suppression of the immune response known as immunoparalysis. We aimed to investigate whether delirious patients had more pronounced immunoparalysis following cardiothoracic surgery than patients without delirium, to explain this delirium-infection association. METHODS: A prospective matched case-control study was performed in two university hospitals. Cytokine production (tumor necrosis factor (TNF)-α, interleukin (IL)-6, IL-8 and IL-10) of ex vivo lipopolysaccharide (LPS)-stimulated whole blood was analyzed in on-pump cardiothoracic surgery patients preoperatively, and at 5 timepoints up to 3 days after cardiothoracic surgery. Delirium was assessed by trained staff using two validated delirium scales and chart review. RESULTS: A total of 89 patients were screened of whom 14 delirious and 52 non-delirious patients were included. Ex vivo-stimulated production of TNF-α, IL-6, IL-8, and IL-10 was severely suppressed following cardiothoracic surgery compared to pre-surgery. Postoperative release of cytokines in non-delirious patients was attenuated by 84% [IQR: 13-93] for TNF-α, 95% [IQR: 78-98] for IL-6, and 69% [IQR: 55-81] for IL-10. The attenuation in ex vivo-stimulated production of these cytokines was not significantly different in patients with delirium compared to non-delirious patients (p > 0.10 for all cytokines). CONCLUSIONS: The post-operative attenuation of ex vivo-stimulated production of pro- and anti-inflammatory cytokines was comparable between patients that developed delirium and those who remained delirium-free after on-pump cardiothoracic surgery. This finding suggests that immunoparalysis is not more common in cardiothoracic surgery patients with delirium compared to those without.

Systemic inflammation down-regulates glyoxalase-1 expression: an experimental study in healthy males.

BACKGROUND: Hypoxia and inflammation are hallmarks of critical illness, related to multiple organ failure. A possible mechanism leading to multiple organ failure is hypoxia- or inflammation-induced down-regulation of the detoxifying glyoxalase system that clears dicarbonyl stress. The dicarbonyl methylglyoxal (MGO) is a highly reactive agent produced by metabolic pathways such as anaerobic glycolysis and gluconeogenesis. MGO leads to protein damage and ultimately multi-organ failure. Whether detoxification of MGO into D-lactate by glyoxalase functions appropriately under conditions of hypoxia and inflammation is largely unknown. We investigated the effect of inflammation and hypoxia on the MGO pathway in humans in vivo. METHODS: After prehydration with glucose 2.5% solution, ten healthy males were exposed to hypoxia (arterial saturation 80-85%) for 3.5 h using an air-tight respiratory helmet, ten males to experimental endotoxemia (LPS 2 ng/kg i.v.), ten males to LPS+hypoxia and ten males to none of these interventions (control group). Serial blood samples were drawn, and glyoxalase-1 mRNA expression, MGO, methylglyoxal-derived hydroimidazolone-1 (MG-H1), D-lactate and L-lactate levels, were measured serially. RESULTS: Glyoxalase-1 mRNA expression decreased in the LPS (ß (95%CI); -0.87 (-1.24; -0.50) and the LPS+hypoxia groups; -0.78 (-1.07; -0.48) (P<0.001). MGO was equal between groups, whereas MG-H1 increased over time in the control group only (P=0.003). D-Lactate was increased in all four groups. L-Lactate was increased in all groups, except in the control group. CONCLUSION: Systemic inflammation downregulates glyoxalase-1 mRNA expression in humans. This is a possible mechanism leading to cell damage and multi-organ failure in critical illness with potential for intervention.

Safety and Efficacy of Human Chorionic Gonadotropin Hormone-Derivative EA-230 in Cardiac Surgery Patients: A Randomized Double-Blind Placebo-Controlled Study.

OBJECTIVES: To determine the safety and efficacy of human chorionic gonadotropin hormone-derivative EA-230 in cardiac surgery patients. Cardiac surgery induces systemic inflammation and may impair renal function, affecting patient outcome. EA-230 exerted immunomodulatory and renoprotective effects in preclinical models and was safe and showed efficacy in phase I and II human studies. DESIGN: Double-blinded, placebo-controlled, randomized study. SETTING: Collaboration of the Cardiothoracic Surgery, Anesthesiology, and the Intensive Care departments of a tertiary hospital in the Netherlands. PATIENTS: One hundred eighty patients undergoing an on-pump coronary artery bypass procedure with or without concomitant valve surgery. INTERVENTIONS: Ninety mg/kg/hr EA-230 or placebo administered during surgery. MEASUREMENTS AND MAIN RESULTS: During the study, no safety concerns emerged. EA-230 did not modulate interleukin-6 plasma concentrations (area under the curve 2,730 pg/mL × hr [1,968-3,760] vs 2,680 pg/mL × hr [2,090-3,570] for EA-230 and placebo group, respectively; p = 0.80). Glomerular filtration rate increased following surgery (mean ± sem increase in the EA-230 vs placebo groups: glomerular filtration rateiohexol measured using iohexol plasma clearance: 19 ± 2 vs 16 ± 2 mL/min/1.73 m2; p = 0.13 and estimated glomerular filtration rate with the Modification of Diet in Renal Disease equation using creatinine: 6 ± 1 vs 2 ± 1 mL/min/1.73 m2; p = 0.01). The "injury" stage of the Risk, Injury, Failure, Loss of kidney function, and End-stage kidney disease criteria for acute kidney injury was 7% in the EA-230 group versus 18% in the placebo group (p = 0.07). In addition, EA-230-treated patients had a less positive fluid balance compared with placebo-treated patients (217 ± 108 vs 605 ± 103 mL; p = 0.01), while the use of vasoactive agents was similar in both groups (p = 0.39). Finally, hospital length of stay was shorter in EA-230 treated patients (8 d [7-11] vs 10 d [8-12]; p = 0.001). Efficacy results were more pronounced in patients that had longer duration of surgery and thus longer duration of study drug infusion. CONCLUSIONS: EA-230 was safe in patients undergoing on-pump cardiac surgery. It did not modulate interleukin-6 plasma concentrations but appeared to exert beneficial renal and cardiovascular effects and shortened in-hospital length of stay.

Disease severity-specific neutrophil signatures in blood transcriptomes stratify COVID-19 patients.

BACKGROUND: The SARS-CoV-2 pandemic is currently leading to increasing numbers of COVID-19 patients all over the world. Clinical presentations range from asymptomatic, mild respiratory tract infection, to severe cases with acute respiratory distress syndrome, respiratory failure, and death. Reports on a dysregulated immune system in the severe cases call for a better characterization and understanding of the changes in the immune system. METHODS: In order to dissect COVID-19-driven immune host responses, we performed RNA-seq of whole blood cell transcriptomes and granulocyte preparations from mild and severe COVID-19 patients and analyzed the data using a combination of conventional and data-driven co-expression analysis. Additionally, publicly available data was used to show the distinction from COVID-19 to other diseases. Reverse drug target prediction was used to identify known or novel drug candidates based on finding from data-driven findings. RESULTS: Here, we profiled whole blood transcriptomes of 39 COVID-19 patients and 10 control donors enabling a data-driven stratification based on molecular phenotype. Neutrophil activation-associated signatures were prominently enriched in severe patient groups, which was corroborated in whole blood transcriptomes from an independent second cohort of 30 as well as in granulocyte samples from a third cohort of 16 COVID-19 patients (44 samples). Comparison of COVID-19 blood transcriptomes with those of a collection of over 3100 samples derived from 12 different viral infections, inflammatory diseases, and independent control samples revealed highly specific transcriptome signatures for COVID-19. Further, stratified transcriptomes predicted patient subgroup-specific drug candidates targeting the dysregulated systemic immune response of the host. CONCLUSIONS: Our study provides novel insights in the distinct molecular subgroups or phenotypes that are not simply explained by clinical parameters. We show that whole blood transcriptomes are extremely informative for COVID-19 since they capture granulocytes which are major drivers of disease severity.

Phenylephrine impairs host defence mechanisms to infection: a combined laboratory study in mice and translational human study.

BACKGROUND: Immunosuppression after surgery is associated with postoperative complications, mediated in part by catecholamines that exert anti-inflammatory effects via the ß-adrenergic receptor. Phenylephrine, generally regarded as a selective α-adrenergic agonist, is frequently used to treat perioperative hypotension. However, phenylephrine may impair host defence through ß-adrenergic affinity. METHODS: Human leukocytes were stimulated with lipopolysaccharide (LPS) in the presence or absence of phenylephrine and α- and ß-adrenergic antagonists. C57BL/6J male mice received continuous infusion of phenylephrine (30-50 µg kg-1 min-1 i.v.) or saline via micro-osmotic pumps, before LPS administration (5 mg kg-1 i.v.) or caecal ligation and puncture (CLP). Twenty healthy males were randomised to a 5 h infusion of phenylephrine (0.5 µg kg-1 min-1) or saline before receiving LPS (2 ng kg-1 i.v.). RESULTS: In vitro, phenylephrine enhanced LPS-induced production of the anti-inflammatory cytokine interleukin (IL)-10 (maximum augmentation of 93%) while attenuating the release of pro-inflammatory mediators. These effects were reversed by pre-incubation with ß-antagonists, but not α-antagonists. Plasma IL-10 levels were higher in LPS-challenged mice infused with phenylephrine, whereas pro-inflammatory mediators were reduced. Phenylephrine infusion increased bacterial counts after CLP in peritoneal fluid (+42%, P=0.0069), spleen (+59%, P=0.04), and liver (+35%, P=0.09). In healthy volunteers, phenylephrine enhanced the LPS-induced IL-10 response (+76%, P=0.0008) while attenuating plasma concentrations of pro-inflammatory mediators including IL-8 (-15%, P=0.03). CONCLUSIONS: Phenylephrine exerts potent anti-inflammatory effects, possibly involving the ß-adrenoreceptor. Phenylephrine promotes bacterial outgrowth after surgical peritonitis. Phenylephrine may therefore compromise host defence in surgical patients and increase susceptibility towards infection. CLINICAL TRIAL REGISTRATION: NCT02675868 (Clinicaltrials.gov).

Norepinephrine Dysregulates the Immune Response and Compromises Host Defense during Sepsis.

Rationale: Sepsis is characterized by a dysregulated immune response to infection. Norepinephrine, the cornerstone vasopressor used in septic shock, may contribute to immune dysregulation and impact host defense.Objectives: To investigate effects of norepinephrine and the alternative vasopressor vasopressin on the immune response and host defense.Methods: Leukocytes from six to nine donors were stimulated in the presence or absence of norepinephrine and vasopressin. A total of 190 C57BL/6J mice received a continuous infusion of norepinephrine or vasopressin via microosmotic pumps and were challenged with LPS or underwent cecal ligation and puncture. Thirty healthy volunteers were randomized to a 5-hour infusion of norepinephrine, vasopressin, or saline and intravenously challenged with LPS. The relationship between the norepinephrine infusion rate and the use of ß-blockers and plasma cytokines was assessed in 195 patients with septic shock.Measurements and Main Results: Norepinephrine attenuated the production of proinflammatory mediators and reactive oxygen species and augmented antiinflammatory IL-10 production both in vitro and in LPS-challenged mice. Norepinephrine infusion during cecal ligation and puncture resulted in increased bacterial dissemination to the spleen, liver, and blood. In LPS-challenged volunteers, norepinephrine enhanced plasma IL-10 concentrations and attenuated the release of the proinflammatory cytokine IFN-γ-induced protein 10. Vasopressin exerted no immunomodulatory effects across these experimental setups. In patients, higher norepinephrine infusion rates were correlated with a more antiinflammatory cytokine balance, whereas ß-blocker use was associated with a more proinflammatory cytokine balance.Conclusions: Norepinephrine dysregulates the immune response in mice and humans and compromises host defense. Therefore, it may significantly contribute to sepsis-induced immunoparalysis, whereas vasopressin does not have untoward immunologic effects.

Frontline Science: Endotoxin-induced immunotolerance is associated with loss of monocyte metabolic plasticity and reduction of oxidative burst.

Secondary infections are a major complication of sepsis and associated with a compromised immune state, called sepsis-induced immunoparalysis. Molecular mechanisms causing immunoparalysis remain unclear; however, changes in cellular metabolism of leukocytes have been linked to immunoparalysis. We investigated the relation of metabolic changes to antimicrobial monocyte functions in endotoxin-induced immunotolerance, as a model for sepsis-induced immunoparalysis. In this study, immunotolerance was induced in healthy males by intravenous endotoxin (2 ng/kg, derived from Escherichia coli O:113) administration. Before and after induction of immunotolerance, circulating CD14+ monocytes were isolated and assessed for antimicrobial functions, including cytokine production, oxidative burst, and microbial (Candida albicans) killing capacity, as well metabolic responses to ex vivo stimulation. Next, the effects of altered cellular metabolism on monocyte functions were validated in vitro. Ex vivo lipopolysaccharide stimulation induced an extensive rewiring of metabolism in naive monocytes. In contrast, endotoxin-induced immunotolerant monocytes showed no metabolic plasticity, as they were unable to adapt their metabolism or mount cytokine and oxidative responses. Validation experiments showed that modulation of metabolic pathways, affected by immunotolerance, influenced monocyte cytokine production, oxidative burst, and microbial (C. albicans) killing in naive monocytes. Collectively, these data demonstrate that immunotolerant monocytes are characterized by a loss of metabolic plasticity and these metabolic defects impact antimicrobial monocyte immune functions. Further, these findings support that the changed cellular metabolism of immunotolerant monocytes might reveal novel therapeutic targets to reverse sepsis-induced immunoparalysis.

A randomized double-blind, placebo-controlled clinical phase IIa trial on safety, immunomodulatory effects and pharmacokinetics of EA-230 during experimental human endotoxaemia.

AIMS: EA-230 is a human chorionic gonadotropin hormone-derived linear tetrapeptide, developed for the treatment of systemic inflammation-related disorders. EA-230 has shown promising immunomodulatory and tissue-protective effects in animals and an excellent safety profile in human phase I studies that we performed. The present phase IIa study follows-up on these results by investigating the safety, efficacy and pharmacokinetics of EA-230 under systemic inflammatory conditions induced by experimental human endotoxaemia. METHODS: In this randomized, double blind, placebo-controlled phase IIa study, systemic inflammation was induced by intravenous administration of Escherichia coli-derived lipopolysaccharide (LPS). At t = 0 hours, 36 healthy male volunteers received 2 ng/kg LPS, followed by a 2-hour continuous infusion of EA-230 (15, 45 and 90 mg/kg/h, n = 8 per group) or placebo (n = 12). RESULTS: EA-230 was well tolerated and showed a favourable safety profile. Treatment with the highest dose of EA-230 resulted in a significant attenuation of the LPS-induced increase in plasma levels of inflammatory mediators interleukin (IL)-6, IL-8, IL-1 receptor antagonist, monocyte chemoattractant protein-1, macrophage inflammatory proteins-1α and -1ß, and vascular cell adhesion protein-1 (% reduction of 48, 28, 33, 28, 14, 16 and 19 respectively, p < .01), and reduced fever (peak decrease from 1.8 ± 0.1°C to 1.3 ± 0.2°C, P < .05) and symptom scores (peak decrease from 7.4 ± 1.0 to 4.0 ± 1.2 points, P < .05). EA-230 exhibited a very short elimination half-life and a large volume of distribution in the highest dosage group (geometric mean and 95% confidence interval: 0.17 [0.12-0.24] hours and 2.2 [1.3-3.8] L/kg, respectively). CONCLUSION: Administration of EA-230 is safe and results in attenuation of the systemic inflammatory response in humans.

Comparison of different lots of endotoxin and evaluation of in vivo potency over time in the experimental human endotoxemia model.

The experimental human endotoxemia model is used to study the systemic inflammatory response in vivo. The previously used lot of endotoxin, which was used for over a decade, is no longer approved for human use and a new Good Manufacturing Practices-grade batch has become available. We compared the inflammatory response induced by either bolus or continuous administration of either the previously used lot #1188844 or new lots of endotoxin (#94332B1 and #94332B4). Compared with lot #1188844, bolus administration of lot #94332B1 induced a more pronounced systemic inflammatory response including higher plasma levels of pro-inflammatory cytokines and more pronounced clinical signs of inflammation. In contrast, continuous infusion of lot #94332B4 resulted in a slightly less pronounced inflammatory response compared with lot #1188844. Furthermore, we evaluated whether lot #1188844 displayed in vivo potency loss by reviewing inflammatory parameters obtained from 17 endotoxemia studies performed in our centre between 2007 and 2016. Despite inter-study variability in endotoxemia-induced effects on temperature, heart rate, symptoms, and leukocyte counts, the magnitude of these effects did not decrease over time. In conclusion, although all lots of endotoxin induce a pronounced inflammatory response, the magnitude differs between lots. We observed no potency loss of endotoxin over time.

Treatment With Acetylsalicylic Acid Reverses Endotoxin Tolerance in Humans In Vivo: A Randomized Placebo-Controlled Study.

OBJECTIVE: To investigate immunostimulatory effects of acetylsalicylic acid during experimental human endotoxemia and in sepsis patients. DESIGN: Double-blind, randomized, placebo-controlled study in healthy volunteers and ex vivo stimulation experiments using monocytes of septic patients. SETTING: Intensive care research unit of an university hospital. SUBJECTS: Thirty healthy male volunteers and four sepsis patients. INTERVENTIONS: Healthy volunteers were challenged IV with endotoxin twice, at a 1-week interval, with each challenge consisting of a bolus of 1 ng/kg followed by continuous administration of 1 ng/kg/hr during 3 hours. Volunteers were randomized to acetylsalicylic acid prophylaxis (80 mg acetylsalicylic acid daily for a 14-d period, starting 7 d before the first endotoxin challenge), acetylsalicylic acid treatment (80 mg acetylsalicylic acid daily for the 7-d period in-between both endotoxin challenges), or the control group (receiving placebo). Furthermore, monocytes of sepsis patients were incubated with acetylsalicylic acid preexposed platelets and were subsequently stimulated with endotoxin. MEASUREMENTS AND MAIN RESULTS: Acetylsalicylic acid prophylaxis enhanced plasma tumor necrosis factor-α concentrations upon the first endotoxin challenge by 50% compared with the control group (p = 0.02) but did not modulate cytokine responses during the second endotoxin challenge. In contrast, acetylsalicylic acid treatment resulted in enhanced plasma levels of tumor necrosis factor-α (+53%; p = 0.02), interleukin-6 (+91%; p = 0.03), and interleukin-8 (+42%; p = 0.02) upon the second challenge, whereas plasma levels of the key antiinflammatory cytokine interleukin-10 were attenuated (-40%; p = 0.003). This proinflammatory phenotype in the acetylsalicylic acid treatment group was accompanied by a decrease in urinary prostaglandin E metabolite levels (-27% ± 7%; p = 0.01). Ex vivo exposure of platelets to acetylsalicylic acid increased production of tumor necrosis factor-α (+66%) and decreased production of interleukin-10 (-23%) by monocytes of sepsis patients. CONCLUSIONS: Treatment, but not prophylaxis, with low-dose acetylsalicylic acid, partially reverses endotoxin tolerance in humans in vivo by shifting response toward a proinflammatory phenotype. This acetylsalicylic acid-induced proinflammatory shift was also observed in septic monocytes, signifying that patients suffering from sepsis-induced immunoparalysis might benefit from initiating acetylsalicylic acid treatment.

Cleaved N-terminal histone tails distinguish between NADPH oxidase (NOX)-dependent and NOX-independent pathways of neutrophil extracellular trap formation.

OBJECTIVES: Neutrophil extracellular traps (NETs) act in various rheumatic diseases. Although NET formation was originally described as a nicotinamide adenine dinucleotide phosphate (NADPH) oxidase (NOX)-dependent pathway, it appears that there are also NOX-independent pathways of NET release. Currently, no tools are available that can discriminate between both NET-forming pathways. We aimed to develop a serological method allowing the discrimination between NETs generated through NOX-dependent or NOX-independent pathways. METHODS: Histones from in vitro generated NOX-dependent and NOX-independent NETs were characterised with a panel of lupus-derived antibodies against N-terminal histone tails using immunofluorescence microscopy, western blot and ELISA. NETs in patients with NET-associated diseases, that is, rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), psoriatic arthritis (PsA) and sepsis, were characterised in sandwich ELISAs employing antibodies against myeloperoxidase (MPO) and N-terminal histone tails as detecting and capturing antibodies, respectively. Functional responses of endothelial cells to NOX-dependent and NOX-independent NETs were assessed as well. RESULTS: Neutrophil elastase cleaves the N-terminal tails of core histones during NOX-dependent, but not during NOX-independent NET formation. Consequently, the detection of MPO-histone complexes with antibodies against N-terminal histone tails allows discrimination between NETs formed through a NOX-dependent or NOX-independent manner. Characterisation of in vivo circulating NETs revealed the presence of NOX-independent NETs in RA, SLE and sepsis, but NOX-dependent NETs in PsA. NOX-independent NETs displayed an increased capacity to activate endothelial cells when compared with NOX-dependent NETs. CONCLUSIONS: These results indicate heterogeneity in NET-forming pathways in vivo and highlight the need for disease-specific strategies to prevent NET-mediated pathology.

Short-Term Hypoxia Dampens Inflammation in vivo via Enhanced Adenosine Release and Adenosine 2B Receptor Stimulation.

Hypoxia and inflammation are closely intertwined phenomena. Critically ill patients often suffer from systemic inflammatory conditions and concurrently experience short-lived hypoxia. We evaluated the effects of short-term hypoxia on systemic inflammation, and show that it potently attenuates pro-inflammatory cytokine responses during murine endotoxemia. These effects are independent of hypoxia-inducible factors (HIFs), but involve augmented adenosine levels, in turn resulting in an adenosine 2B receptor-mediated post-transcriptional increase of interleukin (IL)-10 production. We translated our findings to humans using the experimental endotoxemia model, where short-term hypoxia resulted in enhanced plasma concentrations of adenosine, augmentation of endotoxin-induced circulating IL-10 levels, and concurrent attenuation of the pro-inflammatory cytokine response. Again, HIFs were shown not to be involved. Taken together, we demonstrate that short-term hypoxia dampens the systemic pro-inflammatory cytokine response through enhanced purinergic signaling in mice and men. These effects may contribute to outcome and provide leads for immunomodulatory treatment strategies for critically ill patients.

Temporal biomarker profiles and their association with ICU acquired delirium: a cohort study.

BACKGROUND: Neuroinflammation is thought to play an important role in the pathogenesis of ICU-acquired delirium, but the association between inflammatory and brain-specific proteins and ICU delirium is poor. We investigated whether or not serial determinations of markers may improve this association. METHODS: Critically ill patients with a high risk of ICU delirium and with an ICU length of stay of at least 6 days were included in the study. Blood was drawn on days 1, 2, 4 and 6 after ICU admission and analyzed for different markers of inflammation and several brain proteins. Differences in courses over time prior to and following the onset of delirium and absolute differences over time were analyzed in patients with and without delirium using repeated measurement analysis of variance. In addition, a cross-sectional analysis of levels of these markers before the first onset of delirium was performed. RESULTS: Fifty patients were included in this study. In the longitudinal analysis, there were no differences in the levels of any of the markers immediately prior to and following the onset of delirium, but overall, median levels of adiponectin (9019 (IQR 5776-15,442) vs. 6148 (IQR 4447-8742) ng/ml, p = 0.05) were significantly higher in patients with delirium compared to patients without delirium. In the cross-sectional analysis, median levels of the brain protein Tau (90 (IQR 46-224) vs. 31 (IQR 31-52) pg/ml, p = 0.009) and the ratio Tau/amyloid ß1-42 (1.42 ((IQR 0.9-2.57) vs. 0.68 (IQR 0.54-0.96), p = 0.003) were significantly higher in patients with hypoactive delirium compared to patients without. Levels of neopterin (111 (IQR 37-111) vs. 29 (IQR 16-64) mmol/l, p = 0.004) and IL-10 (28 (IQR 12-39) vs. 9 (IQR 4-12) pg/ml, p = 0.001) were significantly higher in patients with hypoactive delirium compared to patients with mixed-type delirium. CONCLUSIONS: While there are differences in markers (adiponectin and several brain proteins) between patients with and without delirium, the development of delirium is not preceded by a change in the biomarker profile of inflammatory markers or brain proteins. Patients with hypoactive delirium account for the observed differences in biomarkers. TRIAL REGISTRATION: ClinicalTrials.gov, NCT 01274819 . Registered on 12 January 2011.

Increased Plasma Levels of Danger-Associated Molecular Patterns Are Associated With Immune Suppression and Postoperative Infections in Patients Undergoing Cytoreductive Surgery and Hyperthermic Intraperitoneal Chemotherapy.

Introduction: Danger-associated molecular patterns (DAMPs) can elicit immune responses and may subsequently induce an immune-suppressed state. Previous work showed that increased plasma levels of DAMPs are associated with immune suppression and increased susceptibility toward infections in trauma patients. Like trauma, major surgical procedures, such as cytoreductive surgery (CRS) combined with hyperthermic intraperitoneal chemotherapy (HIPEC), are also thought to cause profound DAMP release. Furthermore, the incidence of postoperative infections in these patients, ranging from 10 to 36%, is very high compared to that observed in patients undergoing other major surgical procedures. We hypothesized that the double hit of surgical trauma (CRS) in combination with HIPEC causes excessive DAMP release, which in turn contributes to the development of immune suppression. To investigate this, we assessed DAMP release in patients undergoing CRS-HIPEC, and investigated its relationship with immune suppression and postoperative infections. Methods: In 20 patients undergoing CRS-HIPEC, blood was obtained at five time points: just before surgery (baseline), after CRS, after HIPEC, at ICU admission, and 1 day after surgery. Circulating levels of DAMPs [heat shock protein (HSP)70, high mobility group box (HMGB)1, S100A12, S100A8/S100A9, nuclear (n)DNA, mitochondrial (mt)DNA, lactate dehydrogenase (LDH), a marker of unscheduled cell death], and cytokines [tumor necrosis factor (TNF)α, IL-6, IL-8, IL-10, macrophage inflammatory protein (MIP)-1α, MIP-1ß, and MCP-1] were measured. The extent of immune suppression was determined by measuring HLA-DR gene expression and ex vivo leukocytic cytokine production capacity. Results: Plasma levels of DAMPs (maximum fold increases of HSP70: 2.1 [1.5-2.8], HMGB1: 5.9 [3.2-9.8], S100A8/S100A9: 3.6 [1.8-5.6], S100A12: 2.6 [1.8-4.3], nDNA 3.9 [1.0-10.8], LDH 1.7 [1.2-2.5]), and all measured cytokines increased profoundly following CRS-HIPEC. Evidence of immune suppression was already apparent during the procedure, illustrated by a decrease of HLA-DR expression compared with baseline (0.5-fold [0.3-0.9]) and diminished ex vivo pro-inflammatory cytokine production capacity. The increase in HMGB1 levels correlated with the decrease in HLA-DR expression (r = -0.46, p = 0.04), and peak HMGB1 concentrations were significantly higher in the five patients who went on to develop a postoperative infection (p = 0.04). Conclusion: CRS-HIPEC is associated with profound DAMP release and immune suppression, and plasma HMGB1 levels are related with the occurrence of postoperative infections in these patients.