The Surviving Sepsis Campaign: Basic/Translational Science Research Priorities

How preclinical models help to improve outcome in cardiogenic shock

PURPOSE OF REVIEW

Preclinical experimentation of cardiogenic shock resuscitation on large animal models represents a powerful tool to decipher its complexity and improve its poor outcome, when small animal models are lacking external validation, and clinical investigation are limited due to technical and ethical constraints. This review illustrates the currently available preclinical models addressing reliably the physiopathology and hemodynamic phenotype of cardiogenic shock, highlighting on the opposite questionable translation based on low severity acute myocardial infarction (AMI) models.

RECENT FINDINGS

Three types of preclinical models replicate reliably AMI-related cardiogenic shock, either with coronary microembolization, coronary deoxygenated blood perfusion or double critical coronary sub-occlusion. These models overcame the pitfall of frequent periprocedural cardiac arrest and offer, to different extents, robust opportunities to investigate pharmacological and/or mechanical circulatory support therapeutic strategies, cardioprotective approaches improving heart recovery and mitigation of the systemic inflammatory reaction. They all came with their respective strengths and weaknesses, allowing the researcher to select the right preclinical model for the right clinical question.

SUMMARY

AMI-related cardiogenic shock preclinical models are now well established and should replace low severity AMI models. Technical and ethical constraints are not trivial, but this translational research is a key asset to build up meaningful future clinical investigations.

Psychedelic 25H-NBOMe attenuates post-sepsis depression in rats

Sepsis-associated encephalopathy, which manifests in severe cognitive and depressive symptoms, is directly linked to neuroinflammation. Our study investigates the efficacy of 25H-NBOMe, a phenethylamine, in alleviating these symptoms, potentially offering an innovative treatment for post-sepsis depression. Wistar rats, weighing between 250-300 g, were subjected to cecal ligation and puncture (CLP) surgery to induce sepsis. Depressive-like behaviors were assessed using the forced swim test (FST) on either day 7 or 14 post-surgery, to establish the presence of depressive symptoms. The impact of 25H-NBOMe treatment was then evaluated, focusing on the head-twitch response (HTR), performance in the FST, and GFAP expression in the prefrontal cortex. Treatment with 25H-NBOMe resulted in significant behavioral changes, demonstrated by decreased immobility and increased swimming times in the FST, along with a rise in the HTR. These outcomes indicate a reduction in depressive-like symptoms post-sepsis and the psychoactive effects of the compound. Furthermore, a notable decrease in GFAP expression in the study highlights the compound's impact on mitigating sepsis-induced astrogliosis. This study demonstrates the effectiveness of 25H-NBOMe, a psychedelic in the phenethylamine class, in treating post-sepsis depression and reducing astrogliosis. However, the psychedelic nature of 25H-NBOMe calls for further investigation into similar compounds with less psychoactive impact, crucial for advancing treatment options for neuropsychiatric symptoms following sepsis.

Surviving Sepsis Campaign Research Priorities 2023

OBJECTIVES

To identify research priorities in the management, epidemiology, outcome, and pathophysiology of sepsis and septic shock.

DESIGN

Shortly after publication of the most recent Surviving Sepsis Campaign Guidelines, the Surviving Sepsis Research Committee, a multiprofessional group of 16 international experts representing the European Society of Intensive Care Medicine and the Society of Critical Care Medicine, convened virtually and iteratively developed the article and recommendations, which represents an update from the 2018 Surviving Sepsis Campaign Research Priorities.

METHODS

Each task force member submitted five research questions on any sepsis-related subject. Committee members then independently ranked their top three priorities from the list generated. The highest rated clinical and basic science questions were developed into the current article.

RESULTS

A total of 81 questions were submitted. After merging similar questions, there were 34 clinical and ten basic science research questions submitted for voting. The five top clinical priorities were as follows: 1) what is the best strategy for screening and identification of patients with sepsis, and can predictive modeling assist in real-time recognition of sepsis? 2) what causes organ injury and dysfunction in sepsis, how should it be defined, and how can it be detected? 3) how should fluid resuscitation be individualized initially and beyond? 4) what is the best vasopressor approach for treating the different phases of septic shock? and 5) can a personalized/precision medicine approach identify optimal therapies to improve patient outcomes? The five top basic science priorities were as follows: 1) How can we improve animal models so that they more closely resemble sepsis in humans? 2) What outcome variables maximize correlations between human sepsis and animal models and are therefore most appropriate to use in both? 3) How does sepsis affect the brain, and how do sepsis-induced brain alterations contribute to organ dysfunction? How does sepsis affect interactions between neural, endocrine, and immune systems? 4) How does the microbiome affect sepsis pathobiology? 5) How do genetics and epigenetics influence the development of sepsis, the course of sepsis and the response to treatments for sepsis?

CONCLUSIONS

Knowledge advances in multiple clinical domains have been incorporated in progressive iterations of the Surviving Sepsis Campaign guidelines, allowing for evidence-based recommendations for short- and long-term management of sepsis. However, the strength of existing evidence is modest with significant knowledge gaps and mortality from sepsis remains high. The priorities identified represent a roadmap for research in sepsis and septic shock.

Tissue-specific reprogramming of glutamine metabolism maintains tolerance to sepsis

Reprogramming metabolism is of great therapeutic interest for reducing morbidity and mortality during sepsis-induced critical illness. Disappointing results from randomized controlled trials targeting glutamine and antioxidant metabolism in patients with sepsis have begged a deeper understanding of the tissue-specific metabolic response to sepsis. The current study sought to fill this gap. We analyzed skeletal muscle transcriptomics of critically ill patients, versus elective surgical controls, which revealed reduced expression of genes involved in mitochondrial metabolism and electron transport, with increases in glutathione cycling, glutamine, branched chain, and aromatic amino acid transport. We then performed untargeted metabolomics and 13C isotope tracing to analyze systemic and tissue specific metabolic phenotyping in a murine polymicrobial sepsis model. We found an increased number of correlations between the metabolomes of liver, kidney, and spleen, with loss of correlations between the heart and quadriceps and all other organs, pointing to a shared metabolic signature within vital abdominal organs, and unique metabolic signatures for muscles during sepsis. A lowered GSH:GSSG and elevated AMP:ATP ratio in the liver underlie the significant upregulation of isotopically labeled glutamine's contribution to TCA cycle anaplerosis and glutamine-derived glutathione biosynthesis; meanwhile, the skeletal muscle and spleen were the only organs where glutamine's contribution to the TCA cycle was significantly suppressed. These results highlight tissue-specific mitochondrial reprogramming to support liver energetic demands and antioxidant synthesis, rather than global mitochondrial dysfunction, as a metabolic consequence of sepsis.

Sustained Perturbation of Metabolism and Metabolic Subphenotypes Are Associated With Mortality and Protein Markers of the Host Response

Perturbed host metabolism is increasingly recognized as a pillar of sepsis pathogenesis, yet the dynamic alterations in metabolism and its relationship to other components of the host response remain incompletely understood. We sought to identify the early host-metabolic response in patients with septic shock and to explore biophysiological phenotyping and differences in clinical outcomes among metabolic subgroups.

DESIGN

We measured serum metabolites and proteins reflective of the host-immune and endothelial response in patients with septic shock.

SETTING

We considered patients from the placebo arm of a completed phase II, randomized controlled trial conducted at 16 U.S. medical centers. Serum was collected at baseline (within 24 hr of the identification of septic shock), 24-hour, and 48-hour postenrollment. Linear mixed models were built to assess the early trajectory of protein analytes and metabolites stratified by 28-day mortality status. Unsupervised clustering of baseline metabolomics data was conducted to identify subgroups of patients.

PATIENTS

Patients with vasopressor-dependent septic shock and moderate organ dysfunction that were enrolled in the placebo arm of a clinical trial.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Fifty-one metabolites and 10 protein analytes were measured longitudinally in 72 patients with septic shock. In the 30 patients (41.7%) who died prior to 28 days, systemic concentrations of acylcarnitines and interleukin (IL)-8 were elevated at baseline and persisted at T24 and T48 throughout early resuscitation. Concentrations of pyruvate, IL-6, tumor necrosis factor-α, and angiopoietin-2 decreased at a slower rate in patients who died. Two groups emerged from clustering of baseline metabolites. Group 1 was characterized by higher levels of acylcarnitines, greater organ dysfunction at baseline and postresuscitation (p < 0.05), and greater mortality over 1 year (p < 0.001).

CONCLUSIONS

Among patients with septic shock, nonsurvivors exhibited a more profound and persistent dysregulation in protein analytes attributable to neutrophil activation and disruption of mitochondrial-related metabolism than survivors.

[Pathophysiology of septic shock]

Sepsis and septic shock result from an inadequate host response to an infection, which causes organ dysfunction. The progression of this condition is manifested by the occurrence of successive clinical stages, resulting from the systemic inflammatory response secondary to the activation of different inflammatory mediators, leading to organ dysfunction. There is a high burden of evidence on the role of endotoxin in the pathogenesis of sepsis and its crucial role in triggering the inflammatory response in sepsis caused by gram-negative bacteria. The coagulation cascade activation in sepsis patients is part of the host's adaptive immune response to infection. The endothelium is the main target in sepsis, which is metabolically active and can.

Surviving Sepsis Campaign: Research Opportunities for Infection and Blood Purification Therapies

Patients with infection can develop sepsis, and their mortality can be high. An important aspect in the treatment of sepsis is adequate management of the infection.

Plasma Metabolites in Early Sepsis Identify Distinct Clusters Defined by Plasma Lipids

Supplemental Digital Content is available in the text.

OBJECTIVES:

Unbiased global metabolomic profiling has not been used to identify distinct subclasses in patients with early sepsis and sepsis-associated acute respiratory distress syndrome. In this study, we examined whether the plasma metabolome reflects systemic illness in early sepsis and in acute respiratory distress syndrome.

DESIGN:

Plasma metabolites were measured in subjects with early sepsis.

SETTING:

Patients were admitted from the emergency department to the ICU in a plasma sample collected within 24 hours of ICU admission. Metabolic profiling of 970 metabolites was performed by Metabolon (Durham, NC). Hierarchical clustering and partial least squares discriminant clustering were used to identify distinct clusters among patients with early sepsis and sepsis-associated acute respiratory distress syndrome.

INTERVENTIONS:

None.

MEASUREMENTS AND MAIN RESULTS:

Among critically ill patients with early sepsis (n = 197), three metabolically distinct subgroups were identified, with metabolic subtype driven by plasma lipids. Group 1, with 45 subjects (23% of cohort), had increased 60-day mortality (odds ratio, 2; 95% CI, 0.99–4.0; p = 0.04 for group 1 vs all others). This group also had higher rates of vasopressor-dependent shock, acute kidney injury, and met Berlin acute respiratory distress syndrome criteria more often (all p < 0.05). Conversely, metabolic group 3, with 76 subjects (39% of cohort), had the lowest risk of 60-day mortality (odds ratio, 0.44; 95% CI, 0.22–0.86; p = 0.01) and lower rates of organ dysfunction as reflected in a lower Simplified Acute Physiology Score II (p < 0.001). In contrast, global metabolomic profiling did not separate patient with early sepsis with moderate-to-severe acute respiratory distress syndrome (n = 78) from those with sepsis without acute respiratory distress syndrome (n = 75).

CONCLUSIONS:

Plasma metabolomic profiling in patients with early sepsis identified three metabolically distinct groups that were characterized by different plasma lipid profiles, distinct clinical phenotypes, and 60-day mortality. Plasma metabolites did not distinguish patients with early sepsis who developed acute respiratory distress syndrome from those who did not.

The Surviving Sepsis Campaign: Research Priorities for Coronavirus Disease 2019 in Critical Illness

OBJECTIVES

To identify research priorities in the management, pathophysiology, and host response of coronavirus disease 2019 in critically ill patients.

DESIGN

The Surviving Sepsis Research Committee, a multiprofessional group of 17 international experts representing the European Society of Intensive Care Medicine and Society of Critical Care Medicine, was virtually convened during the coronavirus disease 2019 pandemic. The committee iteratively developed the recommendations and subsequent document.

METHODS

Each committee member submitted a list of what they believed were the most important priorities for coronavirus disease 2019 research. The entire committee voted on 58 submitted questions to determine top priorities for coronavirus disease 2019 research.

RESULTS

The Surviving Sepsis Research Committee provides 13 priorities for coronavirus disease 2019. Of these, the top six priorities were identified and include the following questions: 1) Should the approach to ventilator management differ from the standard approach in patients with acute hypoxic respiratory failure?, 2) Can the host response be modulated for therapeutic benefit?, 3) What specific cells are directly targeted by severe acute respiratory syndrome coronavirus 2, and how do these cells respond?, 4) Can early data be used to predict outcomes of coronavirus disease 2019 and, by extension, to guide therapies?, 5) What is the role of prone positioning and noninvasive ventilation in nonventilated patients with coronavirus disease?, and 6) Which interventions are best to use for viral load modulation and when should they be given?

CONCLUSIONS

Although knowledge of both biology and treatment has increased exponentially in the first year of the coronavirus disease 2019 pandemic, significant knowledge gaps remain. The research priorities identified represent a roadmap for investigation in coronavirus disease 2019.