Adrenomedullin binding improves catecholamine responsiveness and kidney function in resuscitated murine septic shock

Bioactive adrenomedullin (bio-ADM) is associated with endothelial dysfunction in infants and children with complex congenital heart disease undergoing open-heart surgery on cardiopulmonary bypass

OBJECTIVES

Children with congenital heart disease (CHD) undergoing cardiac surgery on cardiopulmonary bypass (CPB) are at risk for systemic inflammation leading to endothelial dysfunction associated with increased morbidity. Bioactive adrenomedullin (bio-ADM) is a peptide regulating vascular tone and endothelial permeability. The aim of this study was to evaluate the dynamics of plasma bio-ADM in this patient cohort and its role in capillary leak.

METHODS

Plasma samples from 73 pediatric CHD patients were collected for bio-ADM measurement at five different timepoints (TP) in the pre-, intra-, and post-operative period. The primary endpoint was a net increase in bio-ADM levels after surgery on CPB. Secondary endpoints included association of bio-ADM levels with clinical signs for endothelial dysfunction.

RESULTS

Bio-ADM levels increased after surgery on CPB from pre-operative median of 12 pg/mL (IQR [interquartile range] 12.0-14.8 pg/mL) to a maximum post-operative median of 48.8 pg/mL (IQR 34.5-69.6 pg/mL, p<0.001). Bio-ADM concentrations correlated positively with post-operative volume balance, (r=0.341; p=0.005), increased demand for vasoactive medication (duration: r=0.415; p<0.001; quantity: TP3: r=0.415, p<0.001; TP4: r=0.414, p<0.001), and hydrocortisone treatment for vasoplegia (bio-ADM median [IQR]:129.1 [55.4-139.2] pg/mL vs. 37.9 [25.2-64.6] pg/mL; p=0.034). Patients who required pleural effusion drainage revealed higher bio-ADM levels compared to those who did not (median [IQR]: 66.4 [55.4-90.9] pg/mL vs. 40.2 [28.2-57.0] pg/mL; p<0.001).

CONCLUSIONS

Bio-ADM is elevated in children after cardiac surgery and higher levels correlate with clinical signs of capillary leakage. The peptide should be considered as biomarker for endothelial dysfunction and as potential therapeutic target in this indication.

Multi-Omics Endotypes in ICU Sepsis-Induced Immunosuppression

It is evident that the admission of some patients with sepsis and septic shock to hospitals is occurring late in their illness, which has contributed to the increase in poor outcomes and high fatalities worldwide across age groups. The current diagnostic and monitoring procedure relies on an inaccurate and often delayed identification by the clinician, who then decides the treatment upon interaction with the patient. Initiation of sepsis is accompanied by immune system paralysis following "cytokine storm". The unique immunological response of each patient is important to define in terms of subtyping for therapy. The immune system becomes activated in sepsis to produce interleukins, and endothelial cells express higher levels of adhesion molecules. The proportions of circulating immune cells change, reducing regulatory cells and increasing memory cells and killer cells, having long-term effects on the phenotype of CD8 T cells, HLA-DR, and dysregulation of microRNA. The current narrative review seeks to highlight the potential application of multi-omics data integration and immunological profiling at the single-cell level to define endotypes in sepsis and septic shock. The review will consider the parallels and immunoregulatory axis between cancer and immunosuppression, sepsis-induced cardiomyopathy, and endothelial damage. Second, the added value of transcriptomic-driven endotypes will be assessed through inferring regulatory interactions in recent clinical trials and studies reporting gene modular features that inform continuous metrics measuring clinical response in ICU, which can support the use of immunomodulating agents.

Proenkephalin A and bioactive adrenomedullin are useful for risk prognostication in cardiac surgery

Introduction

Various clinical scores have been developed to predict organ dysfunction and mortality in patients undergoing cardiac surgery, but outcome prediction may be inaccurate for some patient groups. Proenkephalin A (penKid) and bioactive adrenomedullin (bio-ADM) have emerged as promising biomarkers correlating with shock and organ dysfunction. This imposes the question of whether they can be used as prognostic biomarkers for risk stratification in the perioperative setting of cardiac surgery.

Methods

Patients undergoing cardiac surgery were prospectively enrolled in this observational study. PenKid and bio-ADM plasma levels, as well as markers evaluating inflammation and organ dysfunction, were measured at five perioperative time points from before the induction of anesthesia to up to 48 h postoperatively. Clinical data regarding organ dysfunction and patient outcomes were recorded during the intensive care unit (ICU)-stay with a special focus on acute kidney injury (AKI).

Results

In 136 patients undergoing cardiac surgery, the bio-ADM levels increased and the penKid levels decreased significantly over time. PenKid was associated with chronic kidney disease (CKD), the incidence of AKI, and renal replacement therapy (RRT). Bio-ADM was associated with lactate and the need for vasopressors. PenKid was useful to predict an ICU-length of stay (LOS)>1 day and added prognostic value to the European System for Cardiac Operative Risk Evaluation Score (EuroSCORE) II when measured after the end of cardiopulmonary bypass and 24 h after cardiac surgery. For bio-ADM, the same was true when measured 24 h after surgery. PenKid also added prognostic value to the EuroSCORE II for the combined outcome "ICU length of stay >1 day and in-hospital mortality."

Conclusion

The combination of preoperative EuroSCORE II and intraoperative measurement of penKid may be more useful to predict a prolonged ICU LOS and increased mortality than EuroSCORE II alone. Bio-ADM correlates with markers of shock. More research is encouraged for early risk stratification and validation of penKid and bio-ADM as a tool involved in clinical decisions, which may enable the early initiation of organ protective strategies.

Effects of enrichment strategies on outcome of adrecizumab treatment in septic shock: Post-hoc analyses of the phase II adrenomedullin and outcome in septic shock 2 trial

PURPOSE

Adrecizumab, a non-neutralizing antibody of adrenomedullin (ADM) was recently investigated regarding its potential to restore endothelial barrier function in septic shock patients with high plasma ADM levels. Circulating dipeptidyl peptidase 3 (cDPP3), a protease involved in the degradation of several cardiovascular mediators, represents another biological pathway strongly associated with outcome in septic shock, although unrelated to ADM. Therefore, the prognosis of patients with elevated cDPP3 may not be influenced by Adrecizumab. Also, time until initiation of treatment may influence efficacy.

OBJECTIVE

To evaluate effects of cDPP3-based enrichment on treatment efficacy of Adrecizumab.

MATERIALS AND METHODS

Post-hoc analysis of AdrenOSS-2, a phase-II, double-blind, randomized, placebo-controlled biomarker-guided trial of Adrecizumab.

RESULTS

Compared to the total study cohort [HR for 28-day mortality of 0.84 (95% CI 0.53;1.31), p = 0.439], therapeutic benefit of Adrecizumab tended to be more pronounced in the subgroup of 249 patients with low cDPP3 (<50 ng/mL); [HR of 0.61 (95% CI 0.34;1.08), p = 0.085]. Median duration to study drug infusion was 8.5 h. In the subgroup of 129 patients with cDPP3 <50 ng/mL and an early start of treatment (<8.5 h after septic shock diagnosis) HR for 28-day mortality vs. placebo was 0.49 (95% CI 0.21-1.18), p = 0.105. In multivariate interaction analyses corrected for baseline disease severity, both cDPP3, as well as the cDPP3 * treatment interaction term were associated with a reduced HR for 28-day mortality in the Adrecizumab treated group; p = 0.015 for cDPP3 in univariate analysis, p = 0.025 for the interaction term between cDPP3 and treatment group. In contrast, treatment timing was not significantly associated with 28-day mortality in multivariate interaction analyses.

DISCUSSION

In septic shock patients with high ADM levels, a further post-hoc enrichment strategy based on cDPP3 may indicate (with all the caveats to be considered for post-hoc subgroup analyses) that therapeutic efficacy is most pronounced in patients with lower cDPP3 levels.

Biomarkers for the Prediction and Judgement of Sepsis and Sepsis Complications: A Step towards precision medicine?

Sepsis and septic shock are a major public health concern and are still associated with high rates of morbidity and mortality. Whilst there is growing understanding of different phenotypes and endotypes of sepsis, all too often treatment strategies still only employ a “one-size-fits-all” approach. Biomarkers offer a unique opportunity to close this gap to more precise treatment approaches by providing insight into clinically hidden, yet complex, pathophysiology, or by individualizing treatment pathways. Predicting and evaluating systemic inflammation, sepsis or septic shock are essential to improve outcomes for these patients. Besides opportunities to improve patient care, employing biomarkers offers a unique opportunity to improve clinical research in patients with sepsis. The high rate of negative clinical trials in this field may partly be explained by a high degree of heterogeneity in patient cohorts and a lack of understanding of specific endotypes or phenotypes. Moving forward, biomarkers can support the selection of more homogeneous cohorts, thereby potentially improving study conditions of clinical trials. This may finally pave the way to a precision medicine approach to sepsis, septic shock and complication of sepsis in the future.

Regulation and Dysregulation of Endothelial Permeability during Systemic Inflammation

Systemic inflammation can be triggered by infection, surgery, trauma or burns. During systemic inflammation, an overshooting immune response induces tissue damage resulting in organ dysfunction and mortality. Endothelial cells make up the inner lining of all blood vessels and are critically involved in maintaining organ integrity by regulating tissue perfusion. Permeability of the endothelial monolayer is strictly controlled and highly organ-specific, forming continuous, fenestrated and discontinuous capillaries that orchestrate the extravasation of fluids, proteins and solutes to maintain organ homeostasis. In the physiological state, the endothelial barrier is maintained by the glycocalyx, extracellular matrix and intercellular junctions including adherens and tight junctions. As endothelial cells are constantly sensing and responding to the extracellular environment, their activation by inflammatory stimuli promotes a loss of endothelial barrier function, which has been identified as a hallmark of systemic inflammation, leading to tissue edema formation and hypotension and thus, is a key contributor to lethal outcomes. In this review, we provide a comprehensive summary of the major players, such as the angiopoietin-Tie2 signaling axis, adrenomedullin and vascular endothelial (VE-) cadherin, that substantially contribute to the regulation and dysregulation of endothelial permeability during systemic inflammation and elucidate treatment strategies targeting the preservation of vascular integrity.

Safety and tolerability of non-neutralizing adrenomedullin antibody adrecizumab (HAM8101) in septic shock patients: the AdrenOSS-2 phase 2a biomarker-guided trial

Purpose

Investigate safety and tolerability of adrecizumab, a humanized monoclonal adrenomedullin antibody, in septic shock patients with high adrenomedullin.

Methods

Phase-2a, double-blind, randomized, placebo-controlled biomarker-guided trial with a single infusion of adrecizumab (2 or 4 mg/kg b.w.) compared to placebo. Patients with adrenomedullin above 70 pg/mL, < 12 h of vasopressor start for septic shock were eligible. Randomization was 1:1:2. Primary safety (90-day mortality, treatment emergent adverse events (TEAE)) and tolerability (drug interruption, hemodynamics) endpoints were recorded. Efficacy endpoints included the Sepsis Support Index (SSI, reflecting ventilator- and shock-free days alive), change in Sequential-related Organ Failure Assessment (SOFA) and 28-day mortality.

Results

301 patients were enrolled (median time of 8.5 h after vasopressor start). Adrecizumab was well tolerated (one interruption, no hemodynamic alteration) with no differences in frequency and severity in TEAEs between treatment arms (TEAE of grade 3 or higher: 70.5% in the adrecizumab group and 71.1% in the placebo group) nor in 90-day mortality. Difference in change in SSI between adrecizumab and placebo was 0.72 (CI −1.93–0.49, p = 0.24). Among various secondary endpoints, delta SOFA score (defined as maximum versus minimum SOFA) was more pronounced in the adrecizumab combined group compared to placebo [difference at 0.76 (95% CI 0.18–1.35); p = 0.007]. 28-day mortality in the adrecizumab group was 23.9% and 27.7% in placebo with a hazard ratio of 0.84 (95% confidence interval 0.53–1.31, log-rank p = 0.44).

Conclusions

Overall, we successfully completed a randomized trial evaluating selecting patients for enrolment who had a disease-related biomarker. There were no overt signals of harm with using two doses of the adrenomedullin antibody adrecizumab; however, further randomized controlled trials are required to confirm efficacy and safety of this agent in septic shock patients.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00134-021-06537-5.

Circulating heart failure biomarkers beyond natriuretic peptides: review from the Biomarker Study Group of the Heart Failure Association (HFA), European Society of Cardiology (ESC)

New biomarkers are being evaluated for their ability to advance the management of patients with heart failure. Despite a large pool of interesting candidate biomarkers, besides natriuretic peptides virtually none have succeeded in being applied into the clinical setting. In this review, we examine the most promising emerging candidates for clinical assessment and management of patients with heart failure. We discuss high-sensitivity cardiac troponins (Tn), procalcitonin, novel kidney markers, soluble suppression of tumorigenicity 2 (sST2), galectin-3, growth differentiation factor-15 (GDF-15), cluster of differentiation 146 (CD146), neprilysin, adrenomedullin (ADM), and also discuss proteomics and genetic-based risk scores. We focused on guidance and assistance with daily clinical care decision-making. For each biomarker, analytical considerations are discussed, as well as performance regarding diagnosis and prognosis. Furthermore, we discuss potential implementation in clinical algorithms and in ongoing clinical trials.

Promotion of vascular integrity in sepsis through modulation of bioactive adrenomedullin and dipeptidyl peptidase 3

Sepsis represents one of the major medical challenges of the 21st century. Despite substantial improvements in the knowledge on pathophysiological mechanisms, this has so far not translated into novel adjuvant treatment strategies for sepsis. In sepsis, both vascular tone and vascular integrity are compromised, and contribute to the development of shock, which is strongly related to the development of organ dysfunction and mortality. In this review, we focus on dipeptidyl peptidase 3 (DPP3) and adrenomedullin (ADM), two molecules that act on the vasculature and are involved in the pathophysiology of sepsis and septic shock. DPP3 is an ubiquitous cytosolic enzyme involved in the degradation of several important signalling molecules essential for regulation of vascular tone, including angiotensin II. ADM is a key hormone involved in the regulation of vascular tone and endothelial barrier function. Previous studies have shown that circulating concentrations of both DPP3 and ADM are independently associated with the development of organ failure and adverse outcome in sepsis. We now discuss new evidence illustrating that these molecules indeed represent two distinct pathways involved in the development of septic shock. Recently, both ADM-enhancing therapies aimed at improving endothelial barrier function and vascular tone and DPP3-blocking therapies aimed at restoring systemic angiotensin responses have been shown to improve outcome in various preclinical sepsis models. Given the current lack of effective adjuvant therapies in sepsis, additional research on the therapeutic application of these peptides in humans is highly warranted.

Adrecizumab: an investigational agent for the biomarker-guided treatment of sepsis

Introduction: Sepsis is a major health problem with a high incidence and mortality. ADM, a free-circulating peptide mainly expressed and secreted by vascular endothelial cells, shows vasodilatory properties and causes hypotension when present in higher concentrations during sepsis. Areas covered: Adrecizumab (ADZ) (HAM 8101) is a humanized targeted therapy directed against the N-terminus of adrenomedullin (ADM). ADZ inhibits excessive circulating sepsis-induced ADM and stimulates protective effects on the endothelial barrier, and decreases interstitial vasodilatory effects. ADZ demonstrated a promising safety profile in healthy subjects in phase I studies. According to these results, a phase II proof of concept study enrolling 300 septic patients is currently in course (NCT03085758). Expert opinion: ADZ is the first humanized antibody directed against ADM. The main interest of ADZ is its potential use as a 'biomarker-guided therapy' in septic patients with high circulating ADM. ADZ is increasingly seen as a potential adjunct therapy to restore endothelial function in septic shock. A positive pivotal phase III trial is indeed needed to convince the intensive care community to prescribe ADZ in septic shock patients. Further, it would be of interest to see whether ADZ might also benefit other critical diseases such as cardiogenic shock where endothelial dysfunction has also been described.

Adrenomedullin in Sepsis: Finally, a Friend or an Enemy?

Adrenomedullin (ADM) is a 52 amino acid containing free circulating vasoactive peptide hormone found to be active in various pathophysiological states including sepsis. High ADM levels at admission have been correlated with vasopressor requirements, organ dysfunction, and mortality in sepsis patients. ADM stimulation results in vasodilation and loss of vascular resistance in humans resulting in hypotension with the potential for negative impact in septic shock. However, in vitro human and animal experiments have shown that ADM decreases hyperpermeability and capillary leak, thus having an endothelial barrier stabilizing effect during septic shock. Adrenomedullin thus appears to be a double-edged weapon. This editorial critically reviews the article by Daga et al. who evaluated serum ADM as a prognostic marker to review the gender-related difference in mortality pattern, and also the correlation of ADM level to APACHE II and SOFA scores. The role of adrenomedullin in sepsis and the potential developments in the future have been discussed concisely. How to cite this article: Ajith Kumar AK. Adrenomedullin in Sepsis: Finally, a Friend or an Enemy? Indian J Crit Care Med 2020;24(12):1151-1153.

Vasopressor Therapy in the Intensive Care Unit

After fluid administration for vasodilatory shock, vasopressors are commonly infused. Causes of vasodilatory shock include septic shock, post-cardiovascular surgery, post-acute myocardial infarction, postsurgery, other causes of an intense systemic inflammatory response, and drug -associated anaphylaxis. Therapeutic vasopressors are hormones that activate receptors-adrenergic: α1, α2, β1, β2; angiotensin II: AG1, AG2; vasopressin: AVPR1a, AVPR1B, AVPR2; dopamine: DA1, DA2. Vasopressor choice and dose vary widely because of patient and physician practice heterogeneity. Vasopressor adverse effects are excessive vasoconstriction causing organ ischemia/infarction, hyperglycemia, hyperlactatemia, tachycardia, and tachyarrhythmias. To date, no randomized controlled trial (RCT) of vasopressors has shown a decreased 28-day mortality rate. There is a need for evidence regarding alternative vasopressors as first-line vasopressors. We emphasize that vasopressors should be administered simultaneously with fluid replacement to prevent and decrease duration of hypotension in shock with vasodilation. Norepinephrine is the first-choice vasopressor in septic and vasodilatory shock. Interventions that decrease norepinephrine dose (vasopressin, angiotensin II) have not decreased 28-day mortality significantly. In patients not responsive to norepinephrine, vasopressin or epinephrine may be added. Angiotensin II may be useful for rapid resuscitation of profoundly hypotensive patients. Inotropic agent(s) (e.g., dobutamine) may be needed if vasopressors decrease ventricular contractility. Dopamine has fallen to almost no-use recommendation because of adverse effects; angiotensin II is available clinically; there are potent vasopressors with scant literature (e.g., methylene blue); and the novel V1a agonist selepressin missed on its pivotal RCT primary outcome. In pediatric septic shock, vasopressors, epinephrine, and norepinephrine are recommended equally because there is no clear evidence that supports the use of one vasoactive agent. Dopamine is recommended when epinephrine or norepinephrine is not available. New strategies include perhaps patients will be started on several vasopressors with complementary mechanisms of action, patients may be selected for particular vasopressors according to predictive biomarkers, and novel vasopressors may emerge with fewer adverse effects.

The Effects of Genetic 3-Mercaptopyruvate Sulfurtransferase Deficiency in Murine Traumatic-Hemorrhagic Shock

INTRODUCTION

Hemorrhagic shock is a major cause of death after trauma. An additional blunt chest trauma independently contributes to mortality upon the development of an acute lung injury (ALI) by aggravating pathophysiological consequences of hemorrhagic shock. The maintenance of hydrogen sulfide availability is known to play an important role during hemorrhage and ALI. We therefore tested the impact of a genetic 3-mercaptopyruvate sulfurtransferase mutation (Δ3-MST) in a resuscitated murine model of traumatic-hemorrhagic shock.

METHODS

Anesthetized wild-type (WT) and Δ3-MST mice underwent hemorrhagic shock with/without blunt chest trauma. Hemorrhagic shock was implemented for 1 h followed by retransfusion of shed blood and intensive care therapy for 4 h, including lung-protective mechanical ventilation, fluid resuscitation, and noradrenaline titrated to maintain a mean arterial pressure at least 50 mmHg. Systemic hemodynamics, metabolism, and acid-base status were assessed together with lung mechanics and gas exchange. Postmortem tissue samples were analyzed for immunohistological protein expression and mitochondrial oxygen consumption.

RESULTS

3-MST-deficient mice showed similar results in parameters of hemodynamics, gas exchange, metabolism, acid base status, and survival compared with the respective WT controls. Renal albumin extravasation was increased in Δ3-MST mice during hemorrhagic shock, together with a decrease of LEAK respiration in heart tissue. In contrast, mitochondrial oxygen consumption in the uncoupled state was increased in kidney and liver tissue of Δ3-MST mice subjected to the combined trauma.

CONCLUSIONS

In summary, in a resuscitated murine model of traumatic-hemorrhagic shock, 3-MST deficiency had no physiologically relevant impact on hemodynamics and metabolism, which ultimately lead to unchanged mortality regardless of an additional blunt chest trauma.

In-Depth Characterization of the Effects of Cigarette Smoke Exposure on the Acute Trauma Response and Hemorrhage in Mice

INTRODUCTION

Hemorrhagic shock accounts for a large amount of trauma-related mortality. The severity of trauma can be further aggravated by an additional blunt chest trauma (TxT), which independently contributes to mortality upon the development of an acute lung injury (ALI). Besides, cigarette smoke (CS) exposure before TxT enhanced posttraumatic inflammation, thereby aggravating ALI. We therefore aimed to characterize the impact of an acute and/or chronic lung injury on organ dysfunction in a murine model of traumatic hemorrhagic shock (HS).

METHODS

After 3 weeks of CS exposure, anesthetized mice underwent HS with/without TxT. Hemorrhagic shock was implemented for 1 h followed by retransfusion of shed blood and intensive care therapy for 4 h including lung-protective mechanical ventilation, fluid resuscitation, and noradrenaline titrated to maintain mean arterial pressure ≥50 mmHg. Lung mechanics and gas exchange were assessed together with systemic hemodynamics, metabolism, and acid-base status. Postmortem blood and tissue samples were analyzed for cytokine and chemokine levels, protein expression, mitochondrial respiration, and histological changes.

RESULTS

CS exposure and HS alone coincided with increased inflammation, decreased whole blood sulfide concentrations, and decreased diaphragmatic mitochondrial respiration. CS-exposed mice, which were subjected to TxT and subsequent HS, showed hemodynamic instability, acute kidney injury, and high mortality.

CONCLUSIONS

Chronic CS exposure per se had the strongest impact on inflammatory responses. The degree of inflammation was similar upon an additional TxT, however, mice presented with organ dysfunction and increased mortality rates. Hence, in mice the degree of inflammation may be dissociated from the severity of organ dysfunction or injury.

Immunotherapy in sepsis - brake or accelerate?

Sepsis, a life threating syndrome characterized by organ failure after infection, is the most common cause of death in hospitalized patients. The treatment of sepsis is generally supportive in nature, involving the administration of intravenous fluids, vasoactive substances and oxygen plus antibiotics to eliminate the pathogen. No drugs have been approved specifically for the treatment of sepsis, and clinical trials of potential therapies have failed to reduce mortality - suggesting that new approaches are needed. Abnormalities in the immune response elicited by the pathogen, ranging from excessive inflammation to immunosuppression, contribute to disease pathogenesis. Although hundreds of immunomodulatory agents are potentially available, it remains unclear which patient benefits from which immune therapy at a given time point. Results indicate the importance of personalized therapy, specifically the need to identify the type of intervention required by each individual patient at a given point in the disease process. To address this issue will require using biomarkers to stratify patients based on their individual immune status. This article reviews recent and ongoing clinical investigations using immunostimulatory or immunosuppressive therapies against sepsis including non-pharmacological and novel preclinical approaches.

Vasopressor therapy in critically ill patients with shock

BACKGROUND

Vasopressors are administered to critically ill patients with vasodilatory shock not responsive to volume resuscitation, and less often in cardiogenic shock, and hypovolemic shock.

OBJECTIVES

The objectives are to review safety and efficacy of vasopressors, pathophysiology, agents that decrease vasopressor dose, predictive biomarkers, β1-blockers, and directions for research.

METHODS

The quality of evidence was evaluated using Grading of Recommendations Assessment, Development, and Evaluation (GRADE).

RESULTS

Vasopressors bind adrenergic: α1, α2, β1, β2; vasopressin: AVPR1a, AVPR1B, AVPR2; angiotensin II: AG1, AG2; and dopamine: DA1, DA2 receptors inducing vasoconstriction. Vasopressor choice and dose vary because of patients and physician practice. Adverse effects include excessive vasoconstriction, organ ischemia, hyperglycemia, hyperlactatemia, tachycardia, and tachyarrhythmias. No randomized controlled trials of vasopressors showed a significant difference in 28-day mortality rate. Norepinephrine is the first-choice vasopressor in vasodilatory shock after adequate volume resuscitation. Some strategies that decrease norepinephrine dose (vasopressin, angiotensin II) have not decreased 28-day mortality while corticosteroids have decreased 28-day mortality significantly in some (two large trials) but not all trials. In norepinephrine-refractory patients, vasopressin or epinephrine may be added. A new vasopressor, angiotensin II, may be useful in profoundly hypotensive patients. Dobutamine may be added because vasopressors may decrease ventricular contractility. Dopamine is recommended only in bradycardic patients. There are potent vasopressors with limited evidence (e.g. methylene blue, metaraminol) and novel vasopressors in development (selepressin).

CONCLUSIONS

Norepinephrine is first choice followed by vasopressin or epinephrine. Angiotensin II and dopamine have limited indications. In future, predictive biomarkers may guide vasopressor selection and novel vasopressors may emerge.

Vasopressor therapy in critically ill patients with shock

BACKGROUND

Vasopressors are administered to critically ill patients with vasodilatory shock not responsive to volume resuscitation, and less often in cardiogenic shock, and hypovolemic shock.

OBJECTIVES

The objectives are to review safety and efficacy of vasopressors, pathophysiology, agents that decrease vasopressor dose, predictive biomarkers, β1-blockers, and directions for research.

METHODS

The quality of evidence was evaluated using Grading of Recommendations Assessment, Development, and Evaluation (GRADE).

RESULTS

Vasopressors bind adrenergic: α1, α2, β1, β2; vasopressin: AVPR1a, AVPR1B, AVPR2; angiotensin II: AG1, AG2; and dopamine: DA1, DA2 receptors inducing vasoconstriction. Vasopressor choice and dose vary because of patients and physician practice. Adverse effects include excessive vasoconstriction, organ ischemia, hyperglycemia, hyperlactatemia, tachycardia, and tachyarrhythmias. No randomized controlled trials of vasopressors showed a significant difference in 28-day mortality rate. Norepinephrine is the first-choice vasopressor in vasodilatory shock after adequate volume resuscitation. Some strategies that decrease norepinephrine dose (vasopressin, angiotensin II) have not decreased 28-day mortality while corticosteroids have decreased 28-day mortality significantly in some (two large trials) but not all trials. In norepinephrine-refractory patients, vasopressin or epinephrine may be added. A new vasopressor, angiotensin II, may be useful in profoundly hypotensive patients. Dobutamine may be added because vasopressors may decrease ventricular contractility. Dopamine is recommended only in bradycardic patients. There are potent vasopressors with limited evidence (e.g. methylene blue, metaraminol) and novel vasopressors in development (selepressin).

CONCLUSIONS

Norepinephrine is first choice followed by vasopressin or epinephrine. Angiotensin II and dopamine have limited indications. In future, predictive biomarkers may guide vasopressor selection and novel vasopressors may emerge.

Effects of the Humanized Anti-Adrenomedullin Antibody Adrecizumab (HAM8101) on Vascular Barrier Function and Survival in Rodent Models of Systemic Inflammation and Sepsis

PURPOSE

Adrenomedullin (ADM) is an important regulator of endothelial barrier function during sepsis. Administration of a murine antibody targeted against the N-terminus of ADM (HAM1101) resulted in improved outcome in models of murine sepsis. We studied the effects of a humanized form of this antibody (HAM8101, also known as Adrecizumab) on vascular barrier dysfunction and survival in rodent models of systemic inflammation and sepsis.

METHODS

Rats (n=48) received different dosages of HAM8101 or placebo (n = 8 per group), directly followed by administration of lipopolysaccharide (5 mg/kg). Twenty-four hours later, Evans Blue dye was administered to assess vascular leakage in kidney and liver tissue. Furthermore, mice (n = 24) were administered different dosages of HAM8101 or placebo (n = 6 per group), immediately followed by cecal ligation and puncture (CLP). Eighteen hours later, albumin, vascular endothelial growth factor (VEGF), and angiopoietin-1 were analyzed in the kidney. Finally, effects of single and repeated dose administration of HAM1101, HAM8101 and placebo on survival were assessed in CLP-induced murine sepsis (n = 60, n = 10 per group).

RESULTS

Dosages of 0.1 and 2.5 mg/kg HAM8101 attenuated renal albumin leakage in endotoxemic rats. Dosages of 0.1, 2.0, and 20 mg/kg HAM8101 reduced renal concentrations of albumin and the detrimental protein VEGF in septic mice, whereas concentrations of the protective protein angiopoietin-1 were augmented. Both single and repeated administration of both HAM1101 and HAM8101 resulted in improved survival during murine sepsis.

CONCLUSIONS

Pretreatment with the humanized anti-ADM antibody HAM8101 improved vascular barrier function and survival in rodent models of systemic inflammation and sepsis.

Vascular Effects of Adrenomedullin and the Anti-Adrenomedullin Antibody Adrecizumab in Sepsis

Sepsis remains a major scientific and medical challenge, for which, apart from significant refinements in supportive therapy, treatment has barely changed over the last few decades. During sepsis, both vascular tone and vascular integrity are compromised, and contribute to the development of shock. The free circulating peptide adrenomedullin (ADM) is involved in the regulation of the endothelial barrier function and tone of blood vessels. Several animal studies have shown that ADM administration improves outcome of sepsis. However, in higher dosages, ADM administration may cause hypotension, limiting its clinical applicability. Moreover, ADM has a very short half-life and easily adheres to surfaces, further hampering its clinical use. The non-neutralizing anti-ADM antibody Adrecizumab (HAM8101) which causes a long-lasting increase of plasma ADM has shown promising results in animal models of systemic inflammation and sepsis; it reduced inflammation, attenuated vascular leakage, and improved hemodynamics, kidney function, and survival. Combined with an excellent safety profile derived from animal and phase I human studies, Adrecizumab represents a promising candidate drug for the adjunctive treatment of sepsis. In this review, we first provide a brief overview of the currently available data on the role of adrenomedullin in sepsis and describe its effects on endothelial barrier function and vasodilation. Furthermore, we provide a novel hypothesis concerning the mechanisms of action through which Adrecizumab may exert its beneficial effects in sepsis.

Adrecizumab, a non-neutralizing anti-adrenomedullin antibody, improves haemodynamics and attenuates myocardial oxidative stress in septic rats

Background

Sepsis still represents a major health issue, with persistent high morbidity and mortality rates. Cardiovascular dysfunction occurs frequently during sepsis. Adrenomedullin has been identified as a key mediator in vascular tone regulation. A non-neutralizing anti-adrenomedullin antibody, Adrecizumab, may improve haemodynamic dysfunction during caecal ligation and puncture-induced septic shock in a murine model. Our objective was to determine the role of Adrecizumab on haemodynamics in a rat model of sepsis.

Methods

For the induction of sepsis, caecal ligation and puncture were performed in Wistar male rats. Single blinded administration of Adrecizumab (2 mg/kg) or placebo was injected i.v. 24 h after the surgery, and norepinephrine was infused as the standard of care. There were > 7 animals per group. Invasive blood pressure and cardiac function (by echocardiography) were assessed until 3 h after Adrecizumab injection.

Results

A single therapeutic injection of Adrecizumab in septic rats induced rapid haemodynamic benefits with an increase in systolic blood pressure in septic-Adrecizumab rats versus untreated-septic rats (p = 0.049). The shortening fraction did not differ between the untreated-septic and septic-Adrecizumab groups. However, cardiac output increased during the 3 h after a single dose of Adrecizumab compared to untreated septic rats (p = 0.006). A single dose of Adrecizumab resulted in similar haemodynamics to the continuous administration of norepinephrine.

Three hours after a single injection of Adrecizumab, there was no change in the inflammatory phenotype (TNFα, IL-10) in the hearts of the septic rats. By contrast, 3 h after a single Adrecizumab injection, free-radical production decreased in the hearts of septic-Adrecizumab vs untreated septic rats (p < 0.05).

Conclusions

In a rat model of sepsis, a single therapeutic injection of Adrecizumab rapidly restored haemodynamic parameters and blunted myocardial oxidative stress. Currently, a proof-of-concept and dose-finding phase II trial (Adrenoss-2) is ongoing in patients with septic shock and elevated concentrations of circulating bio-adrenomedullin.

Electronic supplementary material

The online version of this article (10.1186/s40635-019-0255-0) contains supplementary material, which is available to authorized users.

Preclinical safety evaluation of the adrenomedullin-binding antibody Adrecizumab in rodents, dogs and non-human primates

Adrenomedullin (ADM) is a vasoactive peptide in sepsis. The non-neutralizing ADM-binding antibody Adrecizumab improved outcome in animal models of systemic inflammation and sepsis. Herein, we evaluated the preclinical safety of Adrecizumab in various animal species. First, Wistar rats received vehicle, 100, 200 or 400 mg/kg/day of Adrecizumab intravenously (n = 20 each) on days 1, 4, 8 and 14. An additional set of rats received vehicle or 400 mg/kg/day (n = 10 each) on the same days and were followed for 42 days. For toxicokinetics, satellite animals received vehicle (n = 6), 100, 200, or 400 mg/kg/day Adrecizumab intravenously (n = 18 each). A hemodynamic study was performed in Beagle dogs (n = 3) receiving vehicle (day 1), 2 mg/kg (day 3), 10 mg/kg (day 5), 50 mg/kg (day 8) and 10 mg/kg Adrecizumab intravenously (day 29). In final experiments, cynomolgus monkeys received vehicle, 25, 50 or 100 mg/kg/day Adrecizumab intravenously (n = 6 each) on days 1, 4, 8 and 14. Additional groups of monkeys received vehicle or 100 mg/kg/day Adrecizumab intravenously (n = 4 each) on the same days and were followed for 42 days. No mortality or moribund conditions occurred and no toxicologically relevant effects were attributed to Adrecizumab. Adrecizumab significantly increased circulating concentrations of its target peptide ADM, consistent with previous studies and mechanistically relevant. Toxicokinetic analyses showed immediate and dose-dependent peak concentrations, slow elimination and no gender differences. In conclusion, intravenous, repeated administration of high doses of Adrecizumab appeared well-tolerated across species. These results pave the way for further investigation of Adrecizumab in humans (intended dose of 2 mg/kg).

A double-blind, placebo-controlled, randomised, multicentre, proof-of-concept and dose-finding phase II clinical trial to investigate the safety, tolerability and efficacy of adrecizumab in patients with septic shock and elevated adrenomedullin concentration (AdrenOSS-2)

INTRODUCTION

Sepsis remains a major health problem with an increasing incidence, high morbidity and high mortality. Apart from treatment with antibiotics and organ support, no approved specific adjunct therapies currently exist. Adrenomedullin (ADM) is a vasoactive peptide. High plasma concentrations of ADM correlate with worse outcome in sepsis patients. Preclinical work with the non-neutralising ADM-binding antibody adrecizumab showed promising effects in animal models of septic shock, including improved vascular barrier function, reduced vasopressor demand and organ dysfunction and increased survival. Therapeutic use of adrecizumab may therefore improve outcome in critically ill patients with septic shock and high ADM plasma concentrations. Phase I studies in healthy volunteers did not reveal any safety concerns. In this biomarker-guided trial, the safety and efficacy of adrecizumab will be investigated in patients with septic shock.

METHODS AND ANALYSIS

We describe a phase II, randomised, double-blind, placebo-controlled, biomarker-guided, proof-of-concept and dose-finding clinical trial in patients with early septic shock and high concentration of circulating ADM. A total of 300 patients will be enrolled at approximately 30 sites within the European Union. Patients are randomised to receive active treatment (2 and 4 mg/kg adrecizumab) or placebo, in a 1:1:2 ratio. Patient selection is guided by clinical parameters, and biomarker-guided by measurement of circulating biologically active ADM concentration at admission. Primary endpoint is safety and tolerability of adrecizumab over a 90-day period. A key secondary endpoint is the Sepsis Severity Index over a 14-day period.

ETHICS AND DISSEMINATION

This study is approved by relevant institutional review boards/independent ethics committees and is conducted in accordance with the ethical principles of the Declaration of Helsinki, the European Medicines Agency guidelines of Good Clinical Practice and all other applicable regulations. Results of this study will be published in a peer-reviewed scientific journal.

TRIAL REGISTRATION NUMBER

NCT03085758; Pre-results.

Safety, tolerability and pharmacokinetics/pharmacodynamics of the adrenomedullin antibody adrecizumab in a first-in-human study and during experimental human endotoxaemia in healthy subjects

AIMS

Adrenomedullin (ADM) is an important regulator of endothelial barrier function and vascular tone, and may represent a novel treatment target in sepsis. The non-neutralizing ADM antibody adrecizumab has shown promising results in preclinical sepsis models. In the present study, we investigated the safety, tolerability and pharmacokinetics (PK)/pharmacodynamics of adrecizumab in a first-in-man study and in a second study during experimental human endotoxaemia.

METHODS

Forty-eight healthy male volunteers were enrolled in two randomized, double-blind, placebo-controlled phase I studies. In both studies, subjects received placebo or one of three doses of adrecizumab (n = 6 per group). In the second study, a bolus of 1 ng kg-1 endotoxin was followed by infusion of 1 ng kg-1 h-1 endotoxin for 3 h to induce systemic inflammation, and the study medication infusion started 1 h after endotoxin bolus administration.

RESULTS

Adrecizumab showed an excellent safety profile in both studies. PK analyses showed proportional increases in the maximum plasma concentration of adrecizumab with increasing doses, a small volume of distribution, a low clearance rate and a terminal half-life of ~14 days. adrecizumab elicited a pronounced increase in plasma ADM levels, whereas levels of mid-regional pro-adrenomedullin remained unchanged, indicating that de novo synthesis of ADM was not influenced. In the second study, no effects of adrecizumab on cytokine clearance were observed, whereas endotoxin-induced flu-like symptoms resolved more rapidly.

CONCLUSIONS

Administration of adrecizumab is safe and well tolerated in humans, both in the absence and presence of systemic inflammation. These findings pave the way for further investigation of adrecizumab in sepsis patients.

Pathophysiology of Septic Shock

Fundamental features of septic shock are vasodilation, increased permeability, hypovolemia, and ventricular dysfunction. Vasodilation owing to increased nitric oxide and prostaglandins is treated with vasopressors (norepinephrine first). Increased permeability relates to several pathways (Slit/Robo4, vascular endothelial growth factor, angiopoietin 1 and 2/Tie2 pathway, sphingosine-1-phosphate, and heparin-binding protein), some of which are targets for therapies. Hypovolemia is common and crystalloid is recommended for fluid resuscitation. Cardiomyocyte-inflammatory interactions decrease contractility and dobutamine is recommended to increase cardiac output. There is benefit in decreasing heart rate in selected patients with esmolol. Ivabradine is a novel agent for heart rate reduction without decreasing contractility.

Mr-Proadm Elevation Upon Icu Admission Predicts the Outcome of Septic Patients and is Correlated with Upcoming Fluid Overload

BACKGROUND

Among septic patients admitted to the intensive care unit (ICU), early recognition of those with the highest risk of death is of paramount importance. We evaluated the prognostic value of Procalcitonin (PCT), mid regional-proadrenomedullin (MR-proADM), copeptine and CT-proendothelin 1 (CT-ProET 1) concentrations.

METHODS

This was a prospective cohort study, which included 173 septic patient admitted to one ICU. Blood samples for biomarker measurements were obtained upon admission and on day 5. The predictive value of each biomarker regarding the risk of death at day 28 was assessed. The fluid balance was evaluated from admission to day 5.

RESULTS

All cause ICU mortality was 36.4%. All the biomarkers except CT-ProET-1 were significantly more elevated in the non-survivors than in the survivors upon day 1. This was especially true for MR-proADM (8.6 [5.9] vs. 4.4 [3.9] nmol/L; P < 0.0001) and for the CT-proET-1/MR-proADM ratio (52.9 [22.4] vs. 31.3 [26.6] arbitrary units; P < 0.0001). The best AUROCC values on day 1 were obtained with MR-ProADM and the CT-proET-1/MR-proADM ratio as well (0.75 [0.67-0.85] and 0.82 [0.75-0.89]; 95% CI, respectively). An improved accuracy was achieved on day 5. Moreover, MR-ProADM baseline levels and fluid balance over the 5-day period following ICU admission were strongly correlated (Rho = 0.41; P < 0.001).

CONCLUSIONS

In patients admitted to the ICU with sepsis, MR-ProADM on admission was the best predictor of short-term clinical outcome if compared with others. This could be related to its ability to predict fluid sequestration.

Vasoplegia treatments: the past, the present, and the future

Vasoplegia is a ubiquitous phenomenon in all advanced shock states, including septic, cardiogenic, hemorrhagic, and anaphylactic shock. Its pathophysiology is complex, involving various mechanisms in vascular smooth muscle cells such as G protein-coupled receptor desensitization (adrenoceptors, vasopressin 1 receptors, angiotensin type 1 receptors), alteration of second messenger pathways, critical illness-related corticosteroid insufficiency, and increased production of nitric oxide. This review, based on a critical appraisal of the literature, discusses the main current treatments and future approaches. Our improved understanding of these mechanisms is progressively changing our therapeutic approach to vasoplegia from a standardized to a personalized multimodal treatment with the prescription of several vasopressors. While norepinephrine is confirmed as first line therapy for the treatment of vasoplegia, the latest Surviving Sepsis Campaign guidelines also consider that the best therapeutic management of vascular hyporesponsiveness to vasopressors could be a combination of multiple vasopressors, including norepinephrine and early prescription of vasopressin. This new approach is seemingly justified by the need to limit adrenoceptor desensitization as well as sympathetic overactivation given its subsequent deleterious impacts on hemodynamics and inflammation. Finally, based on new pathophysiological data, two potential drugs, selepressin and angiotensin II, are currently being evaluated.

Role of the Purinergic Receptor P2XR4 After Blunt Chest Trauma in Cigarette Smoke-Exposed Mice

Both acute and chronic lung injury are associated with up-regulation of the pulmonary expression of the purinergic receptors P2XR4 and P2XR7. Genetic deletion or blockade of P2XR7 attenuated pulmonary hyperinflammation, but simultaneous P2XR4 up-regulation compensated for P2XR7 deletion. Therefore, we tested the hypothesis whether genetic P2XR4 deletion would attenuate the pulmonary inflammatory response and thereby improve organ function after blunt chest trauma in mice with and without pretraumatic cigarette smoke (CS) exposure.After 3 weeks to 4 weeks of exposure to CS, anesthetized wildtype or P2XR4 mice (n = 32) underwent a blast wave-induced blunt chest trauma followed by 4 h of lung-protective mechanical ventilation, fluid resuscitation, and noradrenaline support to maintain mean arterial pressure >55 mm Hg. Hemodynamics, lung mechanics, gas exchange, and acid-base status were measured together with blood and tissue cytokine and chemokine concentrations, heme oxygenase-1, B-cell lymphoma-extra large (Bcl-xL), endogenous nuclear factor-κB inhibitor (IκBα) expression, nitrotyrosine formation, purinergic receptor expression, and histological scoring.Despite a significant increase in the histopathology score in both CS-exposed groups, neither CS exposure nor P2XR4 deletion had any significant effect on post-traumatic pulmonary function and inflammatory response. However, P2XR4 deletion was associated with attenuated impairment of glucose homeostasis and acid-base-status after CS exposure and chest trauma.In conclusion, genetic P2XR4 deletion failed to attenuate the acute post-traumatic pulmonary inflammatory response. The improved glucose homeostasis and acid-base-status after CS exposure in the P2XR4 group was possibly due to less alveolar hypoxia-induced right ventricular remodeling resulting in preserved liver metabolic capacity.

Adrenomedullin and Adrenomedullin-Targeted Therapy As Treatment Strategies Relevant for Sepsis

Sepsis remains a major medical challenge, for which, apart from improvements in supportive care, treatment has not relevantly changed over the last few decades. Vasodilation and vascular leakage play a pivotal role in the development of septic shock, with vascular leakage being caused by disrupted endothelial integrity. Adrenomedullin (ADM), a free circulating peptide involved in regulation of endothelial barrier function and vascular tone, is implicated in the pathophysiology of sepsis. ADM levels are increased during sepsis, and correlate with extent of vasodilation, as well as with disease severity and mortality. In vitro and preclinical in vivo data show that administration of ADM exerts anti-inflammatory, antimicrobial, and protective effects on endothelial barrier function during sepsis, but other work suggests that it may also decrease blood pressure, which could be detrimental for patients with septic shock. Work has been carried out to negate ADMs putative negative effects, while preserving or even potentiating its beneficial actions. Preclinical studies have demonstrated that the use of antibodies that bind to the N-terminus of ADM results in an overall increase of circulating ADM levels and improves sepsis outcome. Similar beneficial effects were obtained using coadministration of ADM and ADM-binding protein-1. It is hypothesized that the mechanism behind the beneficial effects of ADM binding involves prolongation of its half-life and a shift of ADM from the interstitium to the circulation. This in turn results in increased ADM activity in the blood compartment, where it exerts beneficial endothelial barrier-stabilizing effects, whereas its detrimental vasodilatory effects in the interstitium are reduced. Up till now, in vivo data on ADM-targeted treatments in humans are lacking; however, the first study in septic patients with an N-terminus antibody (Adrecizumab) is currently being conducted.

Association of Kidney Tissue Barrier Disrupture and Renal Dysfunction in Resuscitated Murine Septic Shock

Septic shock-related kidney failure is characterized by almost normal morphological appearance upon pathological examination. Endothelial barrier disrupture has been suggested to be of crucial importance for septic shock-induced organ dysfunction. Therefore, in murine resuscitated cecal ligation and puncture (CLP)-induced septic shock, we tested the hypothesis whether there is a direct relationship between the kidney endothelial barrier injury and renal dysfunction. Anesthetized mice underwent CLP, and 15 h later, were anesthetized again and surgically instrumented for a 5-h period of intensive care comprising lung-protective mechanical ventilation, fluid resuscitation, continuous i.v. norepinephrine to maintain target hemodynamics, and measurement of creatinine clearance (CrCl). Animals were stratified according to low or high CrCl. Nitrotyrosine formation, expression of the inducible isoform of the nitric oxide synthase, and blood cytokine (tumor necrosis factor, interleukin-6, interleukin-10) and chemokine (monocyte chemoattractant protein-1, keratinocyte-derived chemokine) levels were significantly higher in animals with low CrCl. When plotted against CrCl and neutrophil gelatinase-associated lipocalin levels, extravascular albumin accumulation, and tissue expression of the vascular endothelial growth factor and angiopoietin-1 showed significant mathematical relationships related to kidney (dys)function. Preservation of the constitutive expression of the hydrogen sulfide producing enzyme cystathione-γ-lyase was associated with maintenance of organ function. The direct quantitative relation between microvascular leakage and kidney (dys)function may provide a missing link between near-normal tissue morphology and septic shock-related renal failure, thus further highlighting the important role of vascular integrity in septic shock-related renal failure.

Impact of hyperglycemia on cystathionine-γ-lyase expression during resuscitated murine septic shock

BACKGROUND

Cystathionine-γ-lyase (CSE) was shown to have a regulatory role in glucose metabolism. Circulatory shock can induce metabolic stress, thereby leading to hyperglycemia and mitochondrial dysfunction. In vitro data suggest an effect of high glucose on CSE expression. Therefore, the aim of this study was to investigate the effects of hyperglycemia on CSE expression in resuscitated murine septic shock.

METHODS

Normo- (80-150 mg/dl) and hyperglycemic (>200 mg/dl) male C57/BL6J mice (n = 5-6 per group) underwent cecal ligation and puncture (CLP)-induced polymicrobial sepsis or sham procedure (n = 6 per group) and, 15 h afterwards, were anesthetized again, surgically instrumented and received intensive care treatment, including antibiotics, lung protective mechanical ventilation, circulatory support, and intravenous (i.v.) glucose infusion (50% as stable-isotope labeled 1,2,3,4,5,6-13C6 glucose). Blood and breath gas were sampled hourly to quantify parameters of glucose metabolism. 5 h later, mice were sacrificed and organs were harvested. The liver mitochondrial respiratory activity was determined via high resolution respirometry; CSE, peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC1α), and adipocyte differentiation-related protein (ADRP) expression was immunohistochemically investigated.

RESULTS

In sepsis combined with hyperglycemia the least CSE and PGC1α expression could be detected, along with reduced mitochondrial respiratory activity, and enhanced ADRP expression, a marker of lipid droplet formation, in the liver. A novel in vivo finding is the CSE translocation from the cytosol to the nucleus triggered by metabolic stress.

CONCLUSIONS

A relationship between CSE and glucose metabolism was established, which, when dysregulated, may contribute to fatty liver disease and hepatic steatosis.

Regulation of endothelial and epithelial barrier functions by peptide hormones of the adrenomedullin family

The correct regulation of tissue barriers is of utmost importance for health. Barrier dysfunction accompanies inflammatory disorders and, if not controlled properly, can contribute to the development of chronic diseases. Tissue barriers are formed by monolayers of epithelial cells that separate organs from their environment, and endothelial cells that cover the vasculature, thus separating the blood stream from underlying tissues. Cells within the monolayers are connected by intercellular junctions that are linked by adaptor molecules to the cytoskeleton, and the regulation of these interactions is critical for the maintenance of tissue barriers. Many endogenous and exogenous molecules are known to regulate barrier functions in both ways. Proinflammatory cytokines weaken the barrier, whereas anti-inflammatory mediators stabilize barriers. Adrenomedullin (ADM) and intermedin (IMD) are endogenous peptide hormones of the same family that are produced and secreted by many cell types during physiologic and pathologic conditions. They activate certain G-protein-coupled receptor complexes to regulate many cellular processes such as cytokine production, actin dynamics and junction stability. In this review, we summarize current knowledge about the barrier-stabilizing effects of ADM and IMD in health and disease.

Adrenomedullin and endothelin-1 are associated with myocardial injury and death in septic shock patients

Background

Adrenomedullin and endothelin-1 are hormones with opposing effects on the cardiovascular system. Adrenomedullin acts as a vasodilator and seems to be important for the initiation and continuation of the hyperdynamic circulatory response in sepsis. Endothelin-1 is a vasoconstrictor and has been linked to decreased cardiac performance. Few studies have studied the relationship between adrenomedullin and endothelin-1, and morbidity and mortality in septic shock patients. High-sensitivity troponin T (hsTNT) is normally used to diagnose acute cardiac injury but is also prognostic for outcome in intensive care. We investigated the relationship between mid-regional pro-adrenomedullin (MR-proADM), C-terminal pro-endothelin-1 (CT-proET-1), and myocardial injury, measured using transthoracic echocardiography and hsTNT in septic shock patients. We were also interested in the development of different biomarkers throughout the ICU stay, and how early measurements were related to mortality. Further, we assessed if a positive biomarker panel, consisting of MR-proADM, CT-proET-1, and hsTNT changed the odds for mortality.

Methods

A cohort of 53 consecutive patients with septic shock had their levels of MR-proADM, CT-proET-1, hsTNT, and left ventricular systolic functions prospectively measured over 7 days. The relationship between day 1 levels of MR-proADM/CT-proET-1 and myocardial injury was studied. We also investigated the relationship between biomarkers and early (7-day) and later (28-day) mortality. Likelihood ratios, and pretest and posttest odds for mortality were calculated.

Results

Levels of MR-proADM and CT-proET-1 were significantly higher among patients with myocardial injury and were correlated with left ventricular systolic dysfunction. MR-proADM and hsTNT were significantly higher among 7-day and 28-day non-survivors. CT-proET-1 was also significantly higher among 28-day but not 7-day non-survivors. A positive biomarker panel consisting of the three biomarkers increased the odds for mortality 13-fold to 20-fold.

Conclusions

MR-proADM and CT-proET-1 are associated with myocardial injury. A biomarker panel combining MR-proADM, CT-proET-1, and hsTNT increases the odds ratio for death, and may improve currently available scoring systems in critical care.

Blunt Chest Trauma in Mice after Cigarette Smoke-Exposure: Effects of Mechanical Ventilation with 100% O2

Cigarette smoking (CS) aggravates post-traumatic acute lung injury and increases ventilator-induced lung injury due to more severe tissue inflammation and apoptosis. Hyper-inflammation after chest trauma is due to the physical damage, the drop in alveolar PO₂, and the consecutive hypoxemia and tissue hypoxia. Therefore, we tested the hypotheses that 1) CS exposure prior to blunt chest trauma causes more severe post-traumatic inflammation and thereby aggravates lung injury, and that 2) hyperoxia may attenuate this effect. Immediately after blast wave-induced blunt chest trauma, mice (n=32) with or without 3-4 weeks of CS exposure underwent 4 hours of pressure-controlled, thoraco-pulmonary compliance-titrated, lung-protective mechanical ventilation with air or 100 % O₂. Hemodynamics, lung mechanics, gas exchange, and acid-base status were measured together with blood and tissue cytokine and chemokine concentrations, heme oxygenase-1 (HO-1), activated caspase-3, and hypoxia-inducible factor 1-α (HIF-1α) expression, nuclear factor-κB (NF-κB) activation, nitrotyrosine formation, purinergic receptor 2X₄ (P2XR₄) and 2X₇ (P2XR₇) expression, and histological scoring. CS exposure prior to chest trauma lead to higher pulmonary compliance and lower PaO₂ and Horovitz-index, associated with increased tissue IL-18 and blood MCP-1 concentrations, a 2-4-fold higher inflammatory cell infiltration, and more pronounced alveolar membrane thickening. This effect coincided with increased activated caspase-3, nitrotyrosine, P2XR₄, and P2XR₇ expression, NF-κB activation, and reduced HIF-1α expression. Hyperoxia did not further affect lung mechanics, gas exchange, pulmonary and systemic cytokine and chemokine concentrations, or histological scoring, except for some patchy alveolar edema in CS exposed mice. However, hyperoxia attenuated tissue HIF-1α, nitrotyrosine, P2XR₇, and P2XR₄ expression, while it increased HO-1 formation in CS exposed mice. Overall, CS exposure aggravated post-traumatic inflammation, nitrosative stress and thereby organ dysfunction and injury; short-term, lung-protective, hyperoxic mechanical ventilation have no major beneficial effect despite attenuation of nitrosative stress, possibly due to compensation of by regional alveolar hypoxia and/or consecutive hypoxemia, resulting in down-regulation of HIF-1α expression.

Failure of renal biomarkers to predict worsening renal function in high-risk patients presenting with oliguria

PURPOSE

Oliguria is a common symptom in critically ill patients and puts patients in a high risk category for further worsening renal function (WRF). We performed this study to explore the predictive value of biomarkers to predict WRF in oliguric intensive care unit (ICU) patients.

PATIENTS AND METHODS

Single-center prospective observational study. ICU patients were included when they presented a first episode of oliguria. Plasma and urine biomarkers were measured: plasma and urine neutrophil gelatinase-associated lipocalin (pNGAL and uNGAL), urine α1-microglobulin, urine γ-glutamyl transferase, urine indices of tubular function, cystatin C, C terminal fragment of pro-arginine vasopressin (CT-ProAVP), and proadrenomedullin (MR-ProADM).

RESULTS

One hundred eleven patients formed the cohort, of whom 41 [corrected] had worsening renal function. Simplified Acute Physiology Score (SAPS) II was 41 (31-51). WRF was associated with increased mortality (hazard ratio 8.65 [95 % confidence interval (CI) 3.0-24.9], p = 0.0002). pNGAL, MR-ProADM, and cystatin C had the best odds ratio and area under the receiver-operating characteristic curve (AUC-ROC: 0.83 [0.75-0.9], 0.82 [0.71-0.91], and 0.83 [0.74-0.90]), but not different from serum creatinine (Screat, 0.80 [0.70-0.88]). A clinical model that included age, sepsis, SAPS II, and Screat had AUC-ROC of 0.79 [0.69-0.87]; inclusion of pNGAL increased the AUC-ROC to 0.86 (p = 0.03). The category-free net reclassification index improved with pNGAL (total net reclassification index for events to higher risk 61 % and nonevents to lower 82 %).

CONCLUSIONS

All episodes of oliguria do not carry the same risk. No biomarker further improved prediction of WRF compared with Screat in this selected cohort of patients at increased risk defined by oliguria.

Adrenomedullin: a vasodilator to treat sepsis?

Adrenomedullin is a vasodilatory polypeptide with pleiotropic effects secreted by various organs. Adrenomedullin is produced first as a prepropeptide, and then cleaved into mature adrenomedullin and mid-regional proadrenomedullin. Whereas levels of the latter have been shown to correlate with severity of sepsis and carry prognostic value, adrenomedullin plays a role in vascular tone homeostasis. In the previous issue of Critical Care, the infusion of exogenous adrenomedullin is suggested to protect against increased lung endothelial permeability and end-organ dysfunction in a model of pneumococcal pneumonia in mechanically ventilated mice, possibly by stabilizing vascular endothelia. Since adrenomedullin is a strong vasodilatory molecule, further studies are needed to evaluate its potential as a future treatment of sepsis.

Effects of glycemic control on glucose utilization and mitochondrial respiration during resuscitated murine septic shock

Background

This study aims to test the hypothesis whether lowering glycemia improves mitochondrial function and thereby attenuates apoptotic cell death during resuscitated murine septic shock.

Methods

Immediately and 6 h after cecal ligation and puncture (CLP), mice randomly received either vehicle or the anti-diabetic drug EMD008 (100 μg · g^-1). At 15 h post CLP, mice were anesthetized, mechanically ventilated, instrumented and rendered normo- or hyperglycemic (target glycemia 100 ± 20 and 180 ± 50 mg · dL^-1, respectively) by infusing stable, non-radioactive isotope-labeled ¹³C₆-glucose. Target hemodynamics was achieved by colloid fluid resuscitation and continuous i.v. noradrenaline, and mechanical ventilation was titrated according to blood gases and pulmonary compliance measurements. Gluconeogenesis and glucose oxidation were derived from blood and expiratory glucose and ¹³CO₂ isotope enrichments, respectively; mathematical modeling allowed analyzing isotope data for glucose uptake as a function of glycemia. Postmortem liver tissue was analyzed for HO-1, AMPK, caspase-3, and Bax (western blotting) expression as well as for mitochondrial respiratory activity (high-resolution respirometry).

Results

Hyperglycemia lowered mitochondrial respiratory capacity; EMD008 treatment was associated with increased mitochondrial respiration. Hyperglycemia decreased AMPK phosphorylation, and EMD008 attenuated both this effect as well as the expression of activated caspase-3 and Bax. During hyperglycemia EMD008 increased HO-1 expression. During hyperglycemia, maximal mitochondrial oxidative phosphorylation rate was directly related to HO-1 expression, while it was unrelated to AMPK activation. According to the mathematical modeling, EMD008 increased the slope of glucose uptake plotted as a function of glycemia.

Conclusions

During resuscitated, polymicrobial, murine septic shock, glycemic control either by reducing glucose infusion rates or EMD008 improved glucose uptake and thereby liver tissue mitochondrial respiratory activity. EMD008 effects were more pronounced during hyperglycemia and coincided with attenuated markers of apoptosis. The effects of glucose control were at least in part due to the up-regulation of HO-1 and activation of AMPK.

Electronic supplementary material

The online version of this article (doi:10.1186/2197-425X-2-19) contains supplementary material, which is available to authorized users.