Experimental Human Endotoxemia Research Articles

Altered response to Toll-like receptor 4 activation in fibromyalgia: A low-dose, human experimental endotoxemia pilot study

In this pilot study, a human intravenous injection of low-dose endotoxin (lipopolysaccharide, LPS) model was used to test if fibromyalgia is associated with altered immune responses to Toll-like receptor 4 (TLR4) activation. Eight women with moderately-severe fibromyalgia and eight healthy women were administered LPS at 0.1 ng/kg in session one and 0.4 ng/kg in session two. Blood draws were collected hourly to characterize the immune response. The primary analytes of interest, leptin and fractalkine, were assayed via commercial radioimmunoassay and enzyme-linked immunosorbent assay kits, respectively. Exploratory analyses were performed on 20 secreted cytokine assays by multiplex cytokine panels, collected hourly. Exploratory analyses were also performed on testosterone, estrogen, and cortisol levels, collected hourly. Additionally, standard clinical complete blood counts with differential (CBC-D) were collected before LPS administration and at the end of the session. The fibromyalgia group demonstrated enhanced leptin and suppressed fractalkine responses to LPS administration. In the exploratory analyses, the fibromyalgia group showed a lower release of IFN-γ, CXCL10, IL-17A, and IL-12 and higher release of IL-15, TARC, MDC, and eotaxin than the healthy group. The results of this study suggest that fibromyalgia may involve an altered immune response to TLR4 activation.

Interactions between aspirin and ticagrelor during experimental human endotoxaemia

Abstract Introduction Dual antiplatelet therapy (DAPT) with aspirin 75-100mg once daily (OD) and the P2Y12 inhibitor ticagrelor is a standard treatment for acute coronary syndromes. De-escalating DAPT to ticagrelor monotherapy reduces bleeding risk yet appears to have minimal ischaemic penalty in most groups. The reason for this is unclear. P2Y12 inhibition can inhibit inflammatory processes relevant to atherothrombosis but aspirin may hypothetically counter these via platelet PGE2 inhibition. We studied the regimen-dependent effects of aspirin +/- ticagrelor in a human model of endotoxaemia. Endotoxin activates toll-like receptor 4, a key damage receptor in atherogenesis. Methods 72 healthy volunteers were randomised to receive either no aspirin or aspirin 20mg twice daily (BD), 75mg OD or 300mg OD for 10 days +/- a loading dose of ticagrelor on the last day prior to receiving intravenous endotoxin administration (2ng/kg). Blood was collected at 9 timepoints from 1h pre to 6h post endotoxin. Key cytokines and prostanoids in the blood/urine were measured by ELISA, platelet function by light transmittance aggregometry and platelet-leukocyte interaction by flow cytometry. Bleeding time was measured pre and 3h post endotoxin. After >5 weeks, in a 2nd period they received the same dose of aspirin as the 1st but received ticagrelor if they had not already, and vice versa, undergoing a 2nd endotoxin challenge at the end of the period. The primary endpoint was plasma tumour necrosis factor (TNF)-α. Results 72 participants were randomised (median 22.5yrs [range 18-59], 6F:66M). A total of 128 endotoxin challenges were performed. Endotoxaemia was associated with flu-like symptoms, pyrexia, tachycardia and relative hypotension but was safe. In those not receiving aspirin, plasma TNF-α was significantly lower when receiving ticagrelor vs. no ticagrelor, but in those receiving any dose of aspirin the significant effect of ticagrelor was abolished (Fig 1). All doses of aspirin fully suppressed arachidonic acid-induced PA with or without ticagrelor despite the thromboinflammatory stimulus of endotoxaemia (Fig 2A), and significantly augmented the inhibitory effect of ticagrelor on collagen-induced PA (2B). Aspirin 75mg OD and 300mg OD, but not 20mg BD, significantly prolonged bleeding time from baseline (2C). Ticagrelor significantly prolonged bleeding time in combination with any dose of aspirin or no aspirin. Aspirin dose-dependently inhibited PGE2 release. Conclusions All doses of aspirin tested prevented the ability of ticagrelor to significantly inhibit cytokine release during experimental endotoxaemia. Aspirin 20mg BD may offer improved bleeding risk with maintained antiplatelet effect compared to standard regimens. Where ticagrelor monotherapy is an option, dropping aspirin may allow ticagrelor to exert greater beneficial effect on inflammatory pathways relevant to atherothrombosis, potentially reducing ischaemic risk whilst also reducing bleeding risk.Figure 1Figure 2

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

BackgroundSepsis-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.MethodsTo 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.ResultsAlthough 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).ConclusionsCirculating 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.Graphical abstract

Atazanavir-induced unconjugated hyperbilirubinemia prevents vascular hyporeactivity during experimental human endotoxemia.

Inflammation-induced free radical release is important in the pathogenesis of several diseases, including atherosclerosis and sepsis. Heme oxygenase (HO) breaks down heme into carbon monoxide, iron, and biliverdin. Biliverdin IXα is directly converted to bilirubin by biliverdin reductase. Unconjugated bilirubin is a powerful antioxidant, and elevated levels have beneficial effects in preclinical models and human cardiovascular disease. However, its impact during acute inflammation in humans is unknown. In the present study, we investigated the impact of atazanavir-induced (unconjugated) hyperbilirubinemia on antioxidant capacity, inflammation, and vascular dysfunction in human experimental endotoxemia. Following double-blinded four-day treatment with atazanavir 2dd300 mg (or placebo), twenty healthy male volunteers received 2 ng/kg Escherichia coli lipopolysaccharide intravenously. Blood was drawn to determine the bilirubin levels, antioxidant capacity, and cytokine response. It was demonstrated that following atazanavir treatment, total bilirubin concentrations increased to maximum values of 4.67 (95%CI 3.91-5.59) compared to 0.82 (95%CI 0.64-1.07) mg/dL in the control group (p<0.01). Furthermore, the anti-oxidant capacity, as measured by the ferric-reducing ability of plasma (FRAP), was significantly increased with 36% in hyperbilirubinemia subjects (p<0.0001), and FRAP concentrations correlated strongly to bilirubin concentrations (R2=0.77, p<0.001). Hyperbilirubinemia attenuated the release of interleukin-10 from 377 (95%CI 233-609) to 219 (95%CI 152-318) pg/mL (p=0.01), whereas the release of pro-inflammatory cytokines remained unaltered. In vitro, in the absence of hyperbilirubinemia, atazanavir did not influence lipopolysaccharide-induced cytokine release in a whole blood assay. Vascular function was assessed using forearm venous occlusion plethysmography after intra-arterial infusion of acetylcholine and nitroglycerin. Hyperbilirubinemia completely prevented the LPS-associated blunted vascular response to acetylcholine and nitroglycerin. Atazanavir-induced hyperbilirubinemia increases antioxidant capacity, attenuates interleukin-10 release, and prevents vascular hyporesponsiveness during human systemic inflammation elicited by experimental endotoxemia. http://clinicaltrials.gov, identifier NCT00916448.

CytoSorb hemoperfusion markedly attenuates circulating cytokine concentrations during systemic inflammation in humans in vivo

BackgroundThe CytoSorb hemoadsorption device has been demonstrated to be capable of clearing inflammatory cytokines, but has not yet been shown to attenuate plasma cytokine concentrations. We investigated the effects of CytoSorb hemoperfusion on plasma levels of various cytokines using the repeated human experimental endotoxemia model, a highly standardized and reproducible human in vivo model of systemic inflammation and immunological tolerance induced by administration of bacterial lipopolysaccharide (LPS).MethodsTwenty-four healthy male volunteers (age 18–35) were intravenously challenged with LPS (a bolus of 1 ng/kg followed by continuous infusion of 0.5 ng/kg/hr for three hours) twice: on day 0 to quantify the initial cytokine response and on day 7 to quantify the degree of endotoxin tolerance. Subjects either received CytoSorb hemoperfusion during the first LPS challenge (CytoSorb group), or no intervention (control group). Plasma cytokine concentrations and clearance rates were determined serially. This study was registered at ClinicalTrials.gov (NCT04643639, date of registration November 24th 2020).ResultsLPS administration led to a profound increase in plasma cytokine concentrations during both LPS challenge days. Compared to the control group, significantly lower plasma levels of tumor necrosis factor (TNF, − 58%, p < 0.0001), interleukin (IL)-6 ( − 71%, p = 0.003), IL-8 ( − 48%, p = 0.02) and IL-10 ( − 26%, p = 0.03) were observed in the CytoSorb group during the first LPS challenge. No differences in cytokine responses were observed during the second LPS challenge.ConclusionsCytoSorb hemoperfusion effectively attenuates circulating cytokine concentrations during systemic inflammation in humans in vivo, whereas it does not affect long-term immune function. Therefore, CytoSorb therapy may be of benefit in conditions characterized by excessive cytokine release.

Advantages and methodological considerations of experimental endotoxemia in humans – Towards a standardized procedure for its application in PNI

Advantages and methodological considerations of experimental endotoxemia in humans – Towards a standardized procedure for its application in PNI

Wearable Patch Heart Rate Variability Is an Early Marker of Systemic Inflammation During Experimental Human Endotoxemia.

Early diagnosis and treatment can reduce the risk of organ failure and mortality in systemic inflammatory conditions. Heart rate variability (HRV) has potential for early identification of the onset of systemic inflammation, as it may detect changes in sympathetic nervous system activity resulting from the developing inflammatory response before clinical signs appear. With the use of new methodologies, we investigated the onset and kinetics of HRV changes as well as several inflammatory parameters and symptoms during experimental human endotoxemia, a model of systemic inflammation in humans in vivo. Healthy volunteers were intravenously administered LPS (n = 15) or placebo (n = 15). HRV was determined using a wireless wearable device, and parameters low to high frequency (LF:HF) ratio, root mean square of the successive differences (RMSSD), and standard deviation of normal-to-normal R-R intervals (SDNN)were calculated through 1-min-rolling 6-min windows. Plasma cytokine levels and flu-like symptoms and vital signs were serially assessed. The increase in LF:HF ratio, reflecting sympathetic predominance, was more pronounced in the LPS group compared to the placebo group, with the difference becoming statistically significant 65 min following LPS administration (1.63 [1.42-1.83] vs. 1.28 [1.11-1.44], P = 0.005). Significant between-group differences in RMSSD and SDNN were observed from 127 to 140 min post-LPS administration onwards, respectively. Plasma cytokine levels showed significant between-group differences staring 60 min post-LPS. For symptom score, heart rate, temperature, and diastolic blood pressure, significant differences compared with the placebo group were observed at 90, 118, 120, and 124 min post-LPS, respectively. In a controlled human model of systemic inflammation, elevations in the LF:HF ratio followed very shortly after elevations in plasma cytokine levels and preceded onset of flu-like symptoms and alterations in vital signs. HRV may represent a promising non-invasive tool for early detection of a developing systemic inflammatory response.

Human in vivo neuroimaging to detect reprogramming of the cerebral immune response following repeated systemic inflammation

Despite increasing evidence that immune training within the brain may affect the clinical course of neuropsychiatric diseases, data on cerebral immune tolerance are scarce. This study in healthy volunteers examined the trajectory of the immune response systemically and within the brain following repeated lipopolysaccharide (LPS) challenges. Five young males underwent experimental human endotoxemia (intravenous administration of 2 ng/kg LPS) twice with a 7-day interval. The systemic immune response was assessed by measuring plasma cytokine levels. Four positron emission tomography (PET) examinations, using the translocator protein (TSPO) ligand 18F-DPA-714, were performed in each participant, to assess brain immune cell activation prior to and 5 hours after both LPS challenges. The first LPS challenge caused a profound systemic inflammatory response and resulted in a 53% [95%CI 36–71%] increase in global cerebral 18F-DPA-714 binding (p < 0.0001). Six days after the first challenge, 18F-DPA-714 binding had returned to baseline levels (p = 0.399). While the second LPS challenge resulted in a less pronounced systemic inflammatory response (i.e. 77 ± 14% decrease in IL-6 compared to the first challenge), cerebral inflammation was not attenuated, but decreased below baseline, illustrated by a diffuse reduction of cerebral 18F-DPA-714 binding (-38% [95%CI -47 to -28%], p < 0.0001). Our findings constitute evidence for in vivo immunological reprogramming in the brain following a second inflammatory insult in healthy volunteers, which could represent a neuroprotective mechanism. These results pave the way for further studies on immunotolerance in the brain in patients with systemic inflammation-induced cerebral dysfunction.

Elucidating vulnerability to inflammation-induced hyperalgesia: Predictors of increased musculoskeletal pain sensitivity during experimental endotoxemia

Despite broad clinical implications, the mechanisms linking inflammation and pain remain incompletely understood. Using human experimental endotoxemia as a translational model of systemic inflammation, we aimed to elucidate putative vulnerability factors of inflammation-induced musculoskeletal hyperalgesia.We pooled data from three published randomized controlled trials, resulting in a sample of N = 98 healthy volunteers who received either low-dose endotoxin (lipopolysaccharide) or vehicle (saline) intravenously. As measure of musculoskeletal pain sensitivity, pressure pain thresholds (PPTs) were assessed at baseline and 3 h post injection with a handheld algometer for the low back (erector spinae muscle), calf (gastrocnemius muscle), and shoulder region (deltoid muscle). Implementing multiple regression models, we tested the contribution of putative vulnerability factors on musculoskeletal hyperalgesia during systemic inflammation, including acute changes in pro-inflammatory cytokines, state anxiety and mood, as well as pre-existing symptoms of anxiety and depression.Endotoxin application led to significant increases in plasma cytokines, state anxiety, and negative mood, and significantly decreased PPTs for all muscle groups. Regression models revealed that greater M. erector spinae PPT changes were predicted by higher HADS-anxiety scores. Higher TNF-α concentration emerged as predictor for M. gastrocnemius PPT changes, and more pronounced TNF-α increase and higher HADS-anxiety were predictive for M. deltoideus PPTs. HADS scores emerged as predictor for a mean PPT score (computed across all body sites).Together, our results indicate that musculoskeletal hyperalgesia during systemic inflammation is related to pro-inflammatory cytokines, specifically TNF-α. Importantly, subclinical anxiety symptoms (even though in a low and normal range in this cohort of healthy volunteers) may contribute to inflammation-induced hyperalgesia, making individuals more vulnerable to the detrimental effects of systemic inflammation.

Effect of Vasopressors on the Macro- and Microcirculation During Systemic Inflammation in Humans In Vivo

Comparing the effects of different vasopressors in septic shock patients is hampered by high heterogeneity and the fact that current guidelines dictate the use of norepinephrine. Herein, we studied the effects of three vasopressor agents, norepinephrine, phenylephrine, and vasopressin, on the macro- and microcirculation during experimental human endotoxemia, a standardized, controlled model of systemic inflammation in humans in vivo. We performed a randomized controlled study in which 40 healthy male volunteers were assigned to a 5-h infusion of either 0.05 μg/kg/min norepinephrine (n = 10), 0.5 μg/kg/min phenylephrine (n = 10), 0.04 IU/min vasopressin (n = 10), or saline (n = 10), starting 1 h before intravenous administration of 2 ng/kg lipopolysaccharide (LPS). The macrocirculation was monitored using arterial catheter-derived parameters with additional blood pressure waveform contour analysis (PCA) until 4.5 h following LPS administration. Sublingual microcirculatory density and flow were assessed using a handheld video microscope until 6 h post-LPS. LPS administration affected all macrocirculatory and microcirculatory parameters. The LPS-induced decrease in blood pressure and systemic vascular resistance (SVR) was refractory to low-dose norepinephrine and phenylephrine, and to a lesser extent, to vasopressin. Only vasopressin exerted effects on PCA parameters compared with placebo, by mitigating the LPS-induced decrease in diastolic blood pressure by stabilizing SVR and cardiac output. The endotoxemia-induced decreased indices of microvascular flow and density were not influenced by vasopressor therapy. In a highly controlled model of systemic inflammation in humans in vivo, a 5-h infusion of various vasopressors revealed distinctive effects on macrohemodynamic variables without affecting the sublingual microcirculation.

Long-Term Effects of Experimental Human Endotoxemia on Immune Cell Function: Similarities and Differences With Sepsis.

Sepsis is the cause of more than 5.3 million deaths per year, and novel immunotherapeutic strategies are highly warranted. Human models that mirror sepsis immunology are instrumental to this aim. The response to endotoxin in humans during the first 24 h captures many hallmarks of the inflammatory response observed in sepsis. However, the long-term immunologic effects of human experimental endotoxemia have been sparsely studied and could be determinant for the use of this model in sepsis therapy research. In the present work, we studied the immune-composition of healthy subjects challenged with endotoxin (1 ng/kg) 4 h, 2 days, and 20 days post administration by flow cytometry to study the effects on innate and adaptive immune system, and compared it with the immune-composition in patients during the first 9 days after onset of septic shock. We found several differences and similarities between these groups. Experimental endotoxemia resulted in an increase in absolute numbers of intermediate monocytes, which also displayed lower human leucocyte antigen expression 20 days post endotoxin. These changes differed with those observed in septic shock patients. Another long-term effect of experimental endotoxemia was elevated numbers of effector CD8 cells and an increased percentage of proliferating and cytokine expressing CD8 cells, and these phenomena were also present in sepsis patients. In conclusion, despite considerable differences, experimental endotoxemia captures several long-term aspects of sepsis immunology, specifically the behavior of CD8 T cells, which may eventually aid the development of new therapies for sepsis patients.

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

AimsEA‐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.MethodsIn 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).ResultsEA‐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 ‐1β, 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).ConclusionAdministration of EA‐230 is safe and results in attenuation of the systemic inflammatory response in humans.

B-cell dynamics during experimental endotoxemia in humans.

Recently, B cells with regulatory functions suppressing T-cell immunity were identified. Inflammation in the context of sepsis is characterized by a profound immune dysfunction increasing the patient’s risk for additional infections. The impact of endotoxemia on B-cell dynamics, regulatory B cells (Breg) and its contribution to immune dysfunction is unknown. It is the aim of the present study to characterize the dynamics of the B-cell compartment and Breg in an experimental human endotoxemia model.In this randomized placebo-controlled cross-over study, 20 healthy males received an intravenous injection of endotoxin (Escherichia coli lipopolysaccharide, LPS, 0.8 ng/kg body weight) or placebo (saline 0.9%) on two otherwise identical study days. B cells were analyzed by flow cytometry at baseline and repeatedly up to 72 h after endotoxin/placebo injection.Absolute CD19+ B cells counts showed a significant decrease 3 h after endotoxin injection. Memory B cells were partially depleted from the circulation; the total number of Breg was significantly diminished 3 h after LPS challenge. Production of anti-inflammatory interleukin (IL)-10 (IL-10) by Breg was unaltered after LPS challenge. Systemic B-cell activating factor (BAFF) levels were significantly increased with a maximum after 24 h and remained increased up to 72 h post-injection.Endotoxemia causes a transient depletion of memory B cells and Breg from the circulation. However, the functional capacity of B cells to produce IL-10 is not impaired.

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

To investigate immunostimulatory effects of acetylsalicylic acid during experimental human endotoxemia and in sepsis patients. Double-blind, randomized, placebo-controlled study in healthy volunteers and ex vivo stimulation experiments using monocytes of septic patients. Intensive care research unit of an university hospital. Thirty healthy male volunteers and four sepsis patients. 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. 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. 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.

The Safety, Tolerability, and Effects on the Systemic Inflammatory Response and Renal Function of the Human Chorionic Gonadotropin Hormone-Derivative EA-230 Following On-Pump Cardiac Surgery (The EASI Study): Protocol for a Randomized, Double-Blind, Placebo-Controlled Phase 2 Study.

BackgroundThe cardiac surgery–induced systemic inflammatory response may induce postoperative hemodynamic instability and impairment of renal function. EA-230, a linear tetrapeptide (A-Q-G-V), is derived from the beta chain of the human chorionic gonadotropin pregnancy hormone. It has shown immunomodulatory and renoprotective effects in several animal models of systemic inflammation. In phase 1 and phase 2a studies, these immunomodulatory effects were confirmed during human experimental endotoxemia, and EA-230 was found to have an excellent safety profile.ObjectiveThe objective of this first in-patient study is to test the safety and tolerability as well as the immunomodulatory and renoprotective effects of EA-230 in a proof-of-principle design in patients with systemic inflammation following on-pump cardiac surgery.MethodsWe describe a prospective, randomized, double-blind, placebo-controlled study in which 180 elective patients undergoing on-pump coronary artery bypass grafting, with or without concomitant valve surgery, are enrolled. Patients will be randomized in a 1:1 ratio and will receive either EA-230 (90 mg/kg/hour) or a placebo. These will be infused at the start of the surgical procedure until the end of the use of the cardiopulmonary bypass. The primary focus of this first-in-patient study will be on safety and tolerability of EA-230. The primary efficacy end point is the modulation of the inflammatory response by EA-230 quantified as the change in interleukin-6 plasma concentrations after surgery. The key secondary end point is the effect of EA-230 on renal function. The study will be conducted in 2 parts to enable an interim safety analysis by an independent data monitoring committee at a sample size of 60. An adaptive design is used to reassess statistical power halfway through the study.ResultsThis study has been approved by the independent competent authority and ethics committee and will be conducted in accordance with the ethical principles of the Declaration of Helsinki, guidelines of Good Clinical Practice, and European Directive 2001/20/CE regarding the conduct of clinical trials. Results of this study will be submitted for publication in a peer-reviewed scientific journal. Enrollment of this study commenced in July 2016, and results are expected at the end of 2018.ConclusionsThis adaptive phase 2 clinical study is designed to test the safety and tolerability of EA-230 in patients undergoing cardiac surgery. In addition, efficacy end points focused on the effect of the systemic inflammatory response and renal function are investigated.Trial RegistrationClinicalTrials.gov NCT03145220; https://clinicaltrials.gov/ct2/show/NCT03145220 (Archived by WebCite at http://www.webcitation.org/74JPh8GNN)International Registered Report Identifier (IRRID)DERR1-10.2196/11441

Dynamic Cerebral Autoregulation and Critical Closing Pressure in Experimental Human Endotoxemia and Sepsis Patients

Background: To investigate the influence of systemic inflammation on dynamic cerebral autoregulation and vascular tone during experimental human endotoxemia and sepsis. Methods: Healthy volunteers received 3 h continuous infusion of LPS (c-LPS, 4 ng/kg, n = 11, Clinicaltrials.gov NCT02922673) or a bolus of LPS (b-LPS, 2 ng/kg, n = 8, Clinicaltrials.gov NCT02675868) and 10 sepsis patients were studied. Mean arterial pressure (MAP) and cerebral blood flow velocity (CBFV) were monitored simultaneously. Cerebral autoregulation was analysed by transfer function analysis (TFA). Critical closing pressure (CrCP) was estimated as a measure of cerebral vascular tone. Results: c-LPS resulted in a more pronounced and prolonged plasma cytokine response compared with b-LPS. MAP decreased from 89 ± 3 to 75 ± 2 mmHg (p < 0.05) and from 91 ± 2 to 77 ± 3 mmHg (p < 0.001) in the c-LPS and b-LPS groups, respectively. MAP in sepsis patients was 65 ± 4 mmHg. TFA in both LPS groups showed no significant changes over time in coherence, gain and phase. Phase in sepsis patients was lower compared with both LPS groups (7 (2 to 33) [median (interquartile range)] in sepsis versus 57 (36 to 74) in the c-LPS (p = 0.02) and 53 (43 to 64) degrees in the b-LPS group (p = 0.01)). CrCP decreased from 49 ± 2 to 41 ± 2 mmHg (p = 0.16) in the c-LPS and from 50 ± 2 to 42 ± 2 mmHg in the b-LPS group (p < 0.01), and was 36 ± 2 mmHg in sepsis patients. Conclusions: Dynamic cerebral autoregulation is impaired in sepsis patients, but remains intact during experimental human endotoxemia. CrCP decreased during endotoxemia and was low in sepsis, reflecting decreased vascular tone. This indicates activation of a cerebrovascular adaptive process, also during experimental endotoxemia with intact cerebral autoregulation. Trial Registration: Clinicaltrials.gov NCT02922673 and Clinicaltrials.gov NCT02675868

Does Human Experimental Endotoxemia Impact Negative Cognitions Related to the Self?

A role of inflammatory processes in the pathophysiology of depression is increasingly recognized. Experimental endotoxemia offers an established model to induce transient systemic inflammation in healthy humans, and has been proposed as an experimental paradigm of depression. Indeed, different symptoms of depression can be observed during experimental endotoxemia, including negative mood or dysthymia as key symptoms of depression. Hopelessness and low self-esteem constitute common cognitive symptoms in depression, but have not been specifically assessed during endotoxemia. Thus, we pooled data from healthy volunteers who received low-dose endotoxin (i.e., 0.4 or 0.8 ng/kg lipopolysaccharide, LPS) or placebo in three randomized, controlled studies to investigate the effects of LPS on cognitive schemata related to depression. Validated questionnaires were used to assess self-esteem, hopelessness and the vulnerability factor intolerance of uncertainty after intravenous injection of LPS or placebo. Plasma tumor necrosis factor (TNF)-α and interleukin (IL)-6 were repeatedly assessed, along with self-reported mood. Because not all questionnaires were available from primary studies, data were analyzed in two separate data sets: In data set 1, self-esteem and intolerance of uncertainty were assessed in N = 87 healthy volunteers, who randomly received either 0.4 or 0.8 ng/kg LPS or placebo. In data set 2, hopelessness was measured in N = 59 volunteers who randomly received either LPS (0.8 ng/kg) or placebo. In both data sets, LPS-application led to significant increases in TNF-α and IL-6, reflecting systemic inflammation. Positive mood was significantly decreased in response to LPS, in line with inflammation-induced mood impairment. General self-esteem, intolerance of uncertainty and hopelessness did not differ between LPS- and placebo groups, suggesting that these negative cognitive schemata are not responsive to acute LPS-induced systemic inflammation. Interestingly, LPS-treated volunteers reported significantly lower body-related self-esteem, which was associated with increased TNF-α concentration. Thus, certain aspects of self-esteem related to physical attractiveness and sportiness were reduced. It is conceivable that this effect is primarily related to physical sickness symptoms and reduced physical ability during experimental endotoxemia. With respect to cognitive symptoms of depression, it is conceivable that LPS affects cognitive processes, but not negative cognitive schemata, which are rather based on learning and repeated experiences.

Inhibition of Protease-Activated Receptor (PAR1) Reduces Activation of the Endothelium, Coagulation, Fibrinolysis and Inflammation during Human Endotoxemia.

The protease-activated receptor-1 (PAR-1) is critically involved in the co-activation of coagulation and inflammatory responses. Vorapaxar is a reversible, orally active, low molecular weight, competitive antagonist of PAR-1.We investigated the effects of PAR-1 inhibition by vorapaxar on the inflammatory response, the activation of coagulation, fibrinolysis and endothelium during experimental endotoxemia. In this randomized, double blind, crossover trial, 16 healthy volunteers received a bolus infusion of 2 ng/kg lipopolysaccharide (LPS) ± placebo/vorapaxar with a washout period of 8 weeks. Vorapaxar dosing was guided by thrombin receptor-activating peptide-6-induced whole blood aggregometry. Participants received 10 mg vorapaxar or placebo as an initial dose and, depending on the aggregometry, potentially an additional 10 mg. Goal was > 80% inhibition of aggregation compared with baseline. Vorapaxar significantly reduced the LPS-induced increase in pro-thrombin fragments F1 + 2 by a median of 27% (quartiles: 11-49%), thrombin-anti-thrombin concentrations by 22% (-3 to 46%) and plasmin-anti-plasmin levels by 38% (23-53%). PAR-1 inhibition dampened peak concentrations of tumour necrosis factor -α, interleukin-6 and consequently C-reactive protein by 66% (-11-71%), 50% (15-79%) and 23% (16-38%), respectively. Vorapaxar decreased maximum von Willebrand factor levels by 29% (26-51%) and soluble E-selectin concentrations by 30% (25-38%) after LPS infusion. PAR-1 inhibition did not affect thrombomodulin, soluble P-selectin and platelet factor-4 concentrations.PAR-1 inhibition significantly reduced the activation of coagulation, fibrinolysis, the inflammatory response and endothelial activation during experimental human endotoxemia.

Pro-Inflammatory Th1 and Th17 Cells Are Suppressed During Human Experimental Endotoxemia Whereas Anti-Inflammatory IL-10 Producing T-Cells Are Unaffected.

Sepsis is one of the leading causes of the deaths in hospitals. During sepsis, patients are exposed to endotoxemia, which may contribute to the dysregulation of the immune system frequently observed in sepsis. This dysregulation leads to impaired pro-inflammatory responses and may increase the risk for secondary infections in sepsis. The experimental human endotoxemia model is widely used as a model system to study the acute effects of endotoxemia. Under physiological circumstances, the immune system is tightly regulated. Effector T-cells exert pro-inflammatory function and are restrained by regulatory T-cells (Tregs), which modulate pro-inflammatory effector responses. Endotoxemia may induce inadequate Treg activity or render effector T-cells dysfunctional. It was the aim of the study to investigate effector T-cell and Treg responses in an experimental human endotoxemia model. In a cross-over designed placebo-controlled study, 20 healthy male volunteers received an intravenous injection of either lipopolysaccharide (LPS) (0.8 ng/kg body weight) or a placebo (saline 0.9%). CD3+ T-cells, CD4+ T-cells, CD8+ T-cells, and intracellular cytokine profiles were measured with flow cytometry at baseline and at repeated points after LPS/placebo injection. Complete blood cell counts were obtained with an automated hematology analyzer and cytokines were quantified by ELISA. Circulating neutrophils were significantly increased 2 h after LPS injection (p < 0.001) while absolute number of CD3+ T-cells, CD4+ T-cells, and CD8+ T-cells decreased (p < 0.001). Effector T-helper-cells (THs) showed a significant-but transient-decrease of pro-inflammatory IFNγ, interleukin (IL)-2, TNFα, and IL-17A production after LPS injection (p < 0.001). In contrast, the frequency of Treg and the capacity to produce IL-10 were unchanged (p = 0.21). Effector THs fail to produce pro-inflammatory Th1-/Th17-associated cytokines after LPS challenge. In contrast, IL-10 production by Treg is not affected. Thus, endotoxemia-induced suppression of pro-inflammatory THs might be considered as a contributing factor to immunoparalysis in sepsis.

Vasopressors Do Not Influence Cerebral Critical Closing Pressure During Systemic Inflammation Evoked by Experimental Endotoxemia and Sepsis in Humans.

The aim of this study was to investigate the effects of different vasopressors on the cerebral vasculature during experimental human endotoxemia and sepsis. We used the critical closing pressure (CrCP) as a measure of cerebral vascular tone. We performed a prospective pilot study, at the intensive care department (ICU) of a tertiary care university hospital in the Netherlands, in 40 healthy male subjects during experimental human endotoxemia (administration of bacterial lipopolysaccharide [LPS]) and in 10 patients with severe sepsis or septic shock.Subjects in the endotoxemia study were randomized to receive a 5 h infusion of either 0.05 μg/kg/min noradrenaline (n = 10, "LPS-nor"), 0.5 μg/kg/min phenylephrine (n = 10, "LPS-phenyl"), 0.04 IU/min vasopressin (n = 10, "LPS-AVP"), or saline (n = 10, "LPS-placebo") starting 1 h before intravenous administration of 2 ng/kg LPS. In patients with sepsis, fluid resuscitation and vasopressor use was at the discretion of the medical team, aiming at normovolemia and a mean arterial pressure (MAP) > 65 mm Hg, using noradrenaline.The mean flow velocity in the middle cerebral artery (MFVMCA) was measured by transcranial Doppler (TCD) with simultaneously recording of heart rate, arterial blood pressure, respiratory rate, and oxygen saturation. CrCP was estimated using the cerebrovascular impedance model. The CrCP decreased in the LPS-placebo group from 52.6 [46.6-55.5] mm Hg at baseline to 44.1 [41.2-51.3] mm Hg at 270 min post-LPS (P = 0.03). Infusion of phenylephrine increased the CrCP in the period before LPS administration from 46.9 [38.8-53.4] to 53.8 [52.9-60.2] mm Hg (P = 0.02), but after LPS administration, a similar decrease was observed compared with the LPS-placebo group. Noradrenaline or vasopressin prior to LPS did not affect the CrCP. The decrease in CrCP after LPS bolus was similar in all treatment groups. The CrCP in the sepsis patients equaled 35.7 [34.4-42.0] mm Hg, and was lower compared with that in the LPS-placebo subjects from baseline until 90 min after LPS (P < 0.01). Experimental human endotoxemia results in a decreased CrCP due to a loss of vascular resistance of the arterial bed. Vasopressors did not prevent this decrease in CrCP. Findings in patients with sepsis are comparable to those found in subjects after LPS administration.Patients with sepsis, despite treatment with vasopressors, have a risk for low cerebral blood flow and ischemia.