Norepinephrine Dysregulates the Immune Response and Compromises Host Defense during Sepsis

Angiotensin II-Real-Life Use and Literature Review

Angiotensin II is a recently introduced vasopressor, which has been available since 2017. The novelty and the relatively high cost of angiotensin II currently limit its broader application. It induces vasoconstriction by activating the renin-angiotensin-aldosterone system and is currently the sole vasopressor functioning through this pathway. Beyond vasoconstriction, angiotensin II also affects various other physiological processes. Current evidence supports its use in managing vasoplegic and cardiogenic shock in patients who are unresponsive to catecholamines and vasopressin. However, due to limited data, the optimal timing for initiating therapy with angiotensin II, strategies for combining it with other vasopressors, and strategies for its discontinuation remain unclear. Ongoing and planned studies aim to address some of these uncertainties. This article reviews the physiological and pathophysiological effects of angiotensin II, describes its pharmacology, and provides a narrative review of the current literature.

Blockade of sympathetic ganglia improves vascular dysfunction in septic shock

Sepsis/septic shock activates the sympathetic nervous system (SNS) to deal with the infection stress. However, an imbalanced or maladaptive response due to excessive or uncontrolled activation characterizes autonomic dysfunction. Our hypothesis was that reducing this excessive activation of the autonomic nervous system would impact positively in sepsis. Using ganglionic blockers as a pharmacological approach, the main aim of the present report was to assess the role of ganglionic transmission in the vascular dysfunction associated with sepsis.Sepsis was induced in rats by cecal ligation and puncture (CLP). One hour after CLP surgery, rats were treated subcutaneously with hexamethonium (15 mg/kg; ganglionic blocker), pentolinium (5 mg/kg; a blocker with a higher selectivity for sympathetic ganglia compared to hexamethonium), or vehicle (PBS). Basal blood pressure and the response to adrenergic agonists were evaluated at 6 and 24 h after CLP surgery. Reactivity to vasoconstrictors, nitric oxide (NO) synthase 2 (NOS-2) expression, IL-1 and TNF plasma levels, and density of α1 adrenergic receptors were evaluated in the aorta 24 h after CLP.Septic shock resulted in hypotension and hyporesponsiveness to norepinephrine and phenylephrine, increased plasma cytokine levels and NOS-2 expression in the aorta, and decreased α1 receptor density in the same vessel. Pentolinium but not hexamethonium recovered responsiveness and α1 adrenergic receptor density in the aorta. Both blockers normalized the in vivo response to vasoconstrictors, and reduced plasma IL-1 and NOx levels and NOS-2 expression in the aorta.Blockade of ganglionic sympathetic transmission reduced the vascular dysfunction in experimental sepsis. This beneficial effect seems to be, at least in part, due to the preservation of α1 adrenergic receptor density and to reduced NOS-2 expression and may lead to adjuvant ways to treat human sepsis.

Management of Sepsis in the First 24 Hours: Bundles of Care and Individualized Approach

Early diagnosis and prompt management are essential to enhance the outcomes of patients with sepsis and septic shock. Over the past two decades, evidence-based guidelines have guided appropriate treatment and recommended the implementation of a bundle strategy to deliver fundamental treatments within the initial hours of care. Shortly after its introduction, the implementation of a bundle strategy has led to a substantial decrease in mortality rates across various health care settings. The primary advantage of these bundles is their universality, making them applicable to all patients with sepsis. However, this same quality also represents their primary disadvantage as it fails to account for the significant heterogeneity within the septic patient population. Recently, the individualization of treatments included in the bundle has been suggested as a potential strategy for further improving the prognosis of patients with sepsis. New strategies for the early identification of microorganisms and their resistance patterns, advanced knowledge of antibiotic kinetics in critically ill patients, more conservative fluid therapy in specific patient populations, and early use of alternative vasopressors to catecholamines, as well as tailored source control based on patient conditions and site of infection, are potential approaches to personalize initial care for specific subgroups of patients. These innovative methodologies have the potential to improve the management of septic shock. However, their implementation in clinical practice should be guided by solid evidence. Therefore, it is imperative that future research evaluate the safety, efficacy, and cost-effectiveness of these strategies.

Beta-Blockers as an Immunologic and Autonomic Manipulator in Critically Ill Patients: A Review of the Recent Literature

The autonomic nervous system plays a key role in maintaining body hemostasis through both the sympathetic and parasympathetic nervous systems. Sympathetic overstimulation as a reflex to multiple pathologies, such as septic shock, brain injury, cardiogenic shock, and cardiac arrest, could be harmful and lead to autonomic and immunologic dysfunction. The continuous stimulation of the beta receptors on immune cells has an inhibitory effect on these cells and may lead to immunologic dysfunction through enhancing the production of anti-inflammatory cytokines, such as interleukin-10 (IL-10), and inhibiting the production of pro-inflammatory factors, such as interleukin-1B IL-1B and tissue necrotizing factor-alpha (TNF-alpha). Sympathetic overstimulation-induced autonomic dysfunction may also happen due to adrenergic receptor insensitivity or downregulation. Administering anti-adrenergic medication, such as beta-blockers, is a promising treatment to compensate against the undesired effects of adrenergic surge. Despite many misconceptions about beta-blockers, beta-blockers have shown a promising effect in decreasing mortality in patients with critical illness. In this review, we summarize the recently published articles that have discussed using beta-blockers as a promising treatment to decrease mortality in critically ill patients, such as patients with septic shock, traumatic brain injury, cardiogenic shock, acute decompensated heart failure, and electrical storm. We also discuss the potential pathophysiology of beta-blockers in various types of critical illness. More clinical trials are encouraged to evaluate the safety and effectiveness of beta-blockers in improving mortality among critically ill patients.

Therapeutically Fine-Tuning Autonomic Nervous System to Treat Sepsis: A New Perspective on the Immunomodulatory Effects of Acupuncture

Recent studies have highlighted the immunomodulatory effects of acupuncture on sepsis and proposed novel non-pharmacological or bioelectronic approaches to managing inflammatory illnesses. Establishing rules for selectively activating sympathetic or vagal nerve-mediated anti-inflammatory pathways using acupuncture has valuable clinical applications. Over the years, studies have revealed the segmental modulatory role of acupuncture in regulating visceral function by targeting the autonomic nervous system (ANS). In this review, we aim to summarize recent findings on acupuncture in treating sepsis, focusing on the underlying ANS mechanism, as well as the rules of acupoint specificity, intensity, frequency, and other parameters utilized in these studies. Mechanistically, the immunomodulatory properties of the sympathetic nervous system have been highlighted. Furthermore, we explore the immunotherapeutic benefits of acupuncture in treating sepsis. A better understanding of the immunoregulatory mechanism of sympathetic nervous system may offer novel approaches for the development of therapeutics to treat or prevent a variety of inflammatory diseases.

EFFECT OF STRATIFIED DOSE OF NOREPINEPHRINE ON CELLULAR IMMUNE RESPONSE IN PATIENTS WITH SEPTIC SHOCK AND THE CONSTRUCTION OF A PROGNOSTIC RISK MODEL

ABSTRACT

Objective: To explore the effect of a stratified dose of norepinephrine (NE) on cellular immune response in patients with septic shock, and to construct a prognostic model of septic shock. Methods: A total of 160 patients with septic shock (B group) and 58 patients with sepsis (A group) were given standard cluster therapy. Patients with septic shock were divided into four groups (B1-B4 groups: 0.01-0.2, 0.2-0.5, 0.5-1.0, and >1 μg/kg/min) according to the quartile method of the early (72 h) time-weighted average dose of NE and clinical application. The cellular immune indexes at 24 h (T0) and 4-7 days (T1) after admission were collected. The difference method was used to explore the effect of NE stratified dose on cellular immune effect in patients with septic shock. A multivariate COX proportional risk regression model was used to analyze the independent prognostic risk factors, and a prognostic risk model was constructed. Results: The differences of ΔIL-1β, ΔIL-6, ΔIL-10, absolute value difference of T lymphocyte (ΔCD3+/CD45+#) and Th helper T cell (ΔCD3+ CD4+/CD45+#), CD64 infection index difference, ΔmHLA-DR, regulatory T lymphocyte ratio difference (ΔTregs%) between group A, B1, B2, B3, and B4 were statistically significant ( P < 0.05). There was a nonlinear relation between the stratified dose of NE and ΔIL-6, ΔIL-10, ΔCD3+/CD45+#, ΔmHLA-DR%. The threshold periods of NE-induced proinflammatory and anti-inflammatory immune changes were 0.3-0.5 μg/kg/min. Multivariate COX model regression analysis showed that age, nutritional patterns, weighted average dose of norepinephrine, IL-6, absolute value of T lymphocytes, and mHLA-DR were independent risk factors affecting the prognosis of patients with septic shock ( P < 0.05). The prognostic risk model was constructed (AUC value = 0.813, 95% CI: 0.752-0.901). Conclusion: NE has a certain inhibitory effect on cellular immune function in patients with septic shock. A prognostic risk model was constructed with stronger prediction efficiency for the prognosis of patients with septic shock.

Inhibition of circulating dipeptidyl-peptidase 3 by procizumab in experimental septic shock reduces catecholamine exposure and myocardial injury

BACKGROUND

Dipeptidyl peptidase 3 (DPP3) is a ubiquitous cytosolic enzyme released into the bloodstream after tissue injury, that can degrade angiotensin II. High concentrations of circulating DPP3 (cDPP3) have been associated with worse outcomes during sepsis. The aim of this study was to assess the effect of Procizumab (PCZ), a monoclonal antibody that neutralizes cDPP3, in an experimental model of septic shock.

METHODS

In this randomized, open-label, controlled study, 16 anesthetized and mechanically ventilated pigs with peritonitis were randomized to receive PCZ or standard treatment when the mean arterial pressure (MAP) dropped below 50 mmHg. Resuscitation with fluids, antimicrobial therapy, peritoneal lavage, and norepinephrine was initiated one hour later to maintain MAP between 65-75 mmHg for 12 h. Hemodynamic variables, tissue oxygenation indices, and measures of organ failure and myocardial injury were collected. Organ blood flow was assessed using isotopic assessment (99mtechnetium albumin). cDPP3 activity, equilibrium analysis of the renin-angiotensin system and circulating catecholamines were measured. Tissue mRNA expression of interleukin-6 and downregulation of adrenergic and angiotensin receptors were assessed on vascular and myocardial samples.

RESULTS

PCZ-treated animals had reduced cDPP3 levels and required less norepinephrine and fluid than septic control animals for similar organ perfusion and regional blood flow. PCZ-treated animals had less myocardial injury, and higher PaO2/FiO2 ratios. PCZ was associated with lower circulating catecholamine levels; higher circulating angiotensin II and higher angiotensin II receptor type 1 myocardial protein expression, and with lower myocardial and radial artery mRNA interleukin-6 expression.

CONCLUSIONS

In an experimental model of septic shock, PCZ administration was associated with reduced fluid and catecholamine requirements, less myocardial injury and cardiovascular inflammation, along with preserved angiotensin II signaling.

Hemodynamic Support in Sepsis

This review discusses recent evidence in managing sepsis-induced hemodynamic alterations and how it can be integrated with previous knowledge for actionable interventions in adult patients.

EARLY FLUID PLUS NOREPINEPHRINE RESUSCITATION DIMINISHES KIDNEY HYPOPERFUSION AND INFLAMMATION IN SEPTIC NEWBORN PIGS

ABSTRACT

Sepsis is the most frequent risk factor for acute kidney injury (AKI) in critically ill infants. Sepsis-induced dysregulation of kidney microcirculation in newborns is unresolved. The objective of this study was to use the translational swine model to evaluate changes in kidney function during the early phase of sepsis in newborns and the impact of fluid plus norepinephrine resuscitation. Newborn pigs (3-7-day-old) were allocated randomly to three groups: 1) sham, 2) sepsis (cecal ligation and puncture) without subsequent resuscitation, and 3) sepsis with lactated Ringer plus norepinephrine resuscitation. All animals underwent standard anesthesia and mechanical ventilation. Cardiac output and glomerular filtration rate were measured noninvasively. Mean arterial pressure, total renal blood flow, cortical perfusion, medullary perfusion, and medullary tissue oxygen tension (mtPO 2 ) were determined for 12 h. Cecal ligation and puncture decreased mean arterial pressure and cardiac output by more than 50%, with a proportional increase in renal vascular resistance and a 60-80% reduction in renal blood flow, cortical perfusion, medullary perfusion, and mtPO 2 compared to sham. Cecal ligation and puncture also decreased glomerular filtration rate by ~79% and increased AKI biomarkers. Isolated foci of tubular necrosis were observed in the septic piglets. Except for mtPO 2 , changes in all these parameters were ameliorated in resuscitated piglets. Resuscitation also attenuated sepsis-induced increases in the levels of plasma C-reactive protein, proinflammatory cytokines, lactate dehydrogenase, alanine transaminase, aspartate aminotransferase, and renal NLRP3 inflammasome. These data suggest that newborn pigs subjected to cecal ligation and puncture develop hypodynamic septic AKI. Early implementation of resuscitation lessens the degree of inflammation, AKI, and liver injury.

Methylene blue in sepsis and septic shock: a systematic review and meta-analysis

Background

Methylene blue is an interesting approach in reducing fluid overload and vasoactive drug administration in vasodilatory shock. The inhibition of guanylate cyclase induced by methylene blue infusion reduces nitric oxide production and improves vasoconstriction. This systematic review and meta-analysis aimed to assess the effects of methylene blue administration compared to placebo on the hemodynamic status and clinical outcomes in patients with sepsis and septic shock.

Methods

The authors specifically included randomized controlled trials that compared the use of methylene blue with placebo in adult patients with sepsis and septic shock. The outcomes were length of intensive care unit stay, hemodynamic parameters [vasopressor use], and days on mechanical ventilation. We also evaluated the abnormal levels of methemoglobinemia. This systematic review and meta-analysis were recorded in PROSPERO with the ID CRD42023423470.

Results

During the initial search, a total of 1,014 records were identified, out of which 393 were duplicates. Fourteen citations were selected for detailed reading, and three were selected for inclusion. The studies enrolled 141 patients, with 70 of them in the methylene blue group and 71 of them in the control group. Methylene blue treatment was associated with a lower length of intensive care unit stay (MD -1.58; 95%CI -2.97, -0.20; I2 = 25%; p = 0.03), decreased days on mechanical ventilation (MD -0.72; 95%CI -1.26, -0.17; I2 = 0%; p = 0.010), and a shorter time to vasopressor discontinuation (MD -31.49; 95%CI -46.02, -16.96; I2 = 0%; p < 0.0001). No association was found with methemoglobinemia.

Conclusion

Administering methylene blue to patients with sepsis and septic shock leads to reduced time to vasopressor discontinuation, length of intensive care unit stay, and days on mechanical ventilation.

Systematic review registration

https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42023423470, CRD42023423470.

Circulating Dipeptidyl Peptidase 3 Modulates Systemic and Renal Hemodynamics Through Cleavage of Angiotensin Peptides

BACKGROUND

High circulating DPP3 (dipeptidyl peptidase 3) has been associated with poor prognosis in critically ill patients with circulatory failure. In such situation, DPP3 could play a pathological role, putatively via an excessive angiotensin peptides cleavage. Our objective was to investigate the hemodynamics changes induced by DPP3 in mice and the relation between the observed effects and renin-angiotensin system modulation.

METHODS

Ten-week-old male C57Bl/6J mice were subjected to intravenous injection of purified human DPP3 or an anti-DPP3 antibody (procizumab). Invasive blood pressure and renal blood flow were monitored throughout the experiments. Circulating angiotensin peptides and catecholamines were measured and receptor blocking experiment performed to investigate the underlying mechanisms.

RESULTS

DPP3 administration significantly increased renal blood flow, while blood pressure was minimally affected. Conversely, procizumab led to significantly decreased renal blood flow. Angiotensin peptides measurement and an AT1R (angiotensin II receptor type 1) blockade experiment using valsartan demonstrated that the renovascular effect induced by DPP3 is due to reduced AT1R activation via decreased concentrations of circulating angiotensin II, III, and IV. Measurements of circulating catecholamines and an adrenergic receptor blockade by labetalol demonstrated a concomitant catecholamines release that explains blood pressure maintenance upon DPP3 administration.

CONCLUSIONS

High circulating DPP3 increases renal blood flow due to reduced AT1R activation via decreased concentrations of circulating angiotensin peptides while blood pressure is maintained by concomitant endogenous catecholamines release.

Antibiotics, Sedatives, and Catecholamines Further Compromise Sepsis-Induced Immune Suppression in Peripheral Blood Mononuclear Cells

OBJECTIVES

We hypothesized that the immunosuppressive effects associated with antibiotics, sedatives, and catecholamines amplify sepsis-associated immune suppression through mitochondrial dysfunction, and there is a cumulative effect when used in combination. We thus sought to determine the impact of the exemplar drugs ciprofloxacin, propofol, and norepinephrine, used alone and in combination, at clinically relevant concentrations, on the ex vivo functionality of peripheral blood mononuclear cells (PBMCs) drawn from healthy, infected, and septic individuals.

DESIGN

In vitro/ex vivo investigation.

SETTING

University laboratory.

SUBJECTS

Healthy volunteers, infected (nonseptic) patients in the emergency department, and septic ICU patients.

INTERVENTIONS

PBMCs were isolated from these subjects and treated with ciprofloxacin (100 µg/mL), propofol (50 µg/mL), norepinephrine (10 µg/mL), or all three drugs combined, with and without lipopolysaccharide (100 ng/mL) for 6 or 24 hours. Comparison was made between study groups and against untreated cells. Measurements were made of cell viability, cytokine production, phagocytosis, human leukocyte antigen-DR (HLA-DR) status, mitochondrial membrane potential, mitochondrial reactive oxygen species production, and oxygen consumption. Gene expression in immune and metabolic pathways was investigated in PBMCs sampled from healthy volunteers coincubated with septic serum.

MEASUREMENTS AND RESULTS

Coincubation with each of the drugs reduced cytokine production and phagocytosis in PBMCs isolated from septic patients, and healthy volunteers coincubated with septic serum. No effect was seen on HLA-DR surface expression. No cumulative effects were seen with the drug combination. Sepsis-induced changes in gene expression and mitochondrial functionality were not further affected by addition of any of the drugs.

CONCLUSION

Drugs commonly used in critical care lead to significant immune dysfunction ex vivo and enhance sepsis-associated immunosuppression. Further studies are required to identify underlying mechanisms and potential impact on patient outcomes.

Non-conventional immunomodulation in the management of sepsis

Sepsis remains a critical global health issue, demanding novel therapeutic strategies. Traditional immunomodulation treatments such as corticosteroids, specific modifiers of cytokines, complement or coagulation, growth factors or immunoglobulins, have so far fallen short. Meanwhile the number of studies investigating non-conventional immunomodulatory strategies is expanding. This review provides an overview of adjunctive treatments with herbal-based medicine, immunonutrition, vasopressors, sedative treatments and targeted temperature management, used to modulate the immune response in patients with sepsis. Herbal-based medicine, notably within traditional Chinese medicine, shows promise. Xuebijing injection and Shenfu injection exhibit anti-inflammatory and immune-modulatory effects, and the potential to lower 28-day mortality in sepsis. Selenium supplementation has been reported to reduce the occurrence of ventilator-associated pneumonia among sepsis patients, but study results are conflicting. Likewise, the immune-suppressive effects of omega-3 fatty acids have been associated with improved clinical outcomes in sepsis. The immunomodulating properties of supportive treatments also gain interest. Vasopressors like norepinephrine exhibit dual dosage-dependent roles, potentially promoting both pro- and anti-inflammatory effects. Dexmedetomidine, a sedative, demonstrates anti-inflammatory properties, reducing sepsis mortality rates in some studies. Temperature management, particularly maintaining higher body temperature, has also been associated with improved outcomes in small scale human trials. In conclusion, emerging non-conventional immunomodulatory approaches, including herbal medicine, immunonutrition, and targeted supportive therapies, hold potential for sepsis treatment, but their possible implementation into everyday clinical practice necessitates further research and stringent clinical validation in different settings.

[The Immune System of the Critically Ill Patient]

Critically ill patients often experience a dysregulated immune response, leading to immune dysfunction. Sepsis, trauma, severe infections, and certain medical conditions can trigger a state of systemic inflammation, known as the cytokine storm. This hyperactive immune response can cause collateral damage to healthy tissues and organs, exacerbating the patient's condition. On the other hand, some critically ill patients may suffer from immune paralysis which can increase the risk of nosocomial infections.Fever is an evolutionary adaptation that evolved as an effective defense mechanism to fight invading pathogens. By raising body temperature, fever enhances the immune response, inhibits pathogen growth, promotes recovery, and aids in the formation of immune memory. Understanding the role of fever in the context of immune defense is crucial for optimizing medical interventions and supporting the body's natural ability to combat infections.Future Directions: Advancements in immunology research and technology hold promise for better understanding the immune system's complexities in critically ill patients. Personalized medicine approaches may be developed to tailor therapies to individual patients based on their immune profile, optimizing treatment outcomes. Based on recent studies prognostic parameters such as lymphocyte count, IL-10 concentration and mHLA-DR expression can be used to stratify the immunological response pattern in septic patients.Conclusion: The immune system's response in critically ill patients is a multifaceted process, involving intricate interactions between various immune cells, cytokines, and organs. Striking the delicate balance between immune activation and suppression remains a significant challenge in clinical practice. Continued research and therapeutic innovations are vital to improve patient outcomes and reduce the burden of critical illness on healthcare systems.

13C-Metabolic flux analysis detected a hyperoxemia-induced reduction of tricarboxylic acid cycle metabolism in granulocytes during two models of porcine acute subdural hematoma and hemorrhagic shock

Introduction

Supplementation with increased inspired oxygen fractions has been suggested to alleviate the harmful effects of tissue hypoxia during hemorrhagic shock (HS) and traumatic brain injury. However, the utility of therapeutic hyperoxia in critical care is disputed to this day as controversial evidence is available regarding its efficacy. Furthermore, in contrast to its hypoxic counterpart, the effect of hyperoxia on the metabolism of circulating immune cells remains ambiguous. Both stimulating and detrimental effects are possible; the former by providing necessary oxygen supply, the latter by generation of excessive amounts of reactive oxygen species (ROS). To uncover the potential impact of increased oxygen fractions on circulating immune cells during intensive care, we have performed a 13C-metabolic flux analysis (MFA) on PBMCs and granulocytes isolated from two long-term, resuscitated models of combined acute subdural hematoma (ASDH) and HS in pigs with and without cardiovascular comorbidity.

Methods

Swine underwent resuscitation after 2 h of ASDH and HS up to a maximum of 48 h after HS. Animals received normoxemia (PaO2 = 80 - 120 mmHg) or targeted hyperoxemia (PaO2 = 200 - 250 mmHg for 24 h after treatment initiation, thereafter PaO2 as in the control group). Blood was drawn at time points T1 = after instrumentation, T2 = 24 h post ASDH and HS, and T3 = 48 h post ASDH and HS. PBMCs and granulocytes were isolated from whole blood to perform electron spin resonance spectroscopy, high resolution respirometry and 13C-MFA. For the latter, we utilized a parallel tracer approach with 1,2-13C2 glucose, U-13C glucose, and U-13C glutamine, which covered essential pathways of glucose and glutamine metabolism and supplied redundant data for robust Bayesian estimation. Gas chromatography-mass spectrometry further provided multiple fragments of metabolites which yielded additional labeling information. We obtained precise estimations of the fluxes, their joint credibility intervals, and their relations, and characterized common metabolic patterns with principal component analysis (PCA).

Results

13C-MFA indicated a hyperoxia-mediated reduction in tricarboxylic acid (TCA) cycle activity in circulating granulocytes which encompassed fluxes of glutamine uptake, TCA cycle, and oxaloacetate/aspartate supply for biosynthetic processes. We further detected elevated superoxide levels in the swine strain characterized by a hypercholesterolemic phenotype. PCA revealed cell type-specific behavioral patterns of metabolic adaptation in response to ASDH and HS that acted irrespective of swine strains or treatment group.

Conclusion

In a model of resuscitated porcine ASDH and HS, we saw that ventilation with increased inspiratory O2 concentrations (PaO2 = 200 - 250 mmHg for 24 h after treatment initiation) did not impact mitochondrial respiration of PBMCs or granulocytes. However, Bayesian 13C-MFA results indicated a reduction in TCA cycle activity in granulocytes compared to cells exposed to normoxemia in the same time period. This change in metabolism did not seem to affect granulocytes' ability to perform phagocytosis or produce superoxide radicals.

Uncovering hub genes in sepsis through bioinformatics analysis

In-depth studies on the mechanisms of pathogenesis of sepsis and diagnostic biomarkers in the early stages may be the key to developing individualized and effective treatment strategies. This study aimed to identify sepsis-related hub genes and evaluate their diagnostic reliability. The gene expression profiles of GSE4607 and GSE131761 were obtained from the Gene Expression Omnibus. Differentially co-expressed genes between the sepsis and control groups were screened. Single-sample gene set enrichment analysis and gene set variation analysis were performed to investigate the biological functions of the hub genes. A receiver operating characteristic curve was used to evaluate diagnostic value. Datasets GSE154918 and GSE185263 were used as external validation datasets to verify the reliability of the hub genes. Four differentially co-expressed genes, FAM89A, FFAR3, G0S2, and FGF13, were extracted using a weighted gene co-expression network analysis and differential gene expression analysis methods. These 4 genes were upregulated in the sepsis group and were distinct from those in the controls. Moreover, the receiver operating characteristic curves of the 4 genes exhibited considerable diagnostic value in discriminating septic blood samples from those of the non-septic control group. The reliability and consistency of these 4 genes were externally validated. Single-sample gene set enrichment analysis and gene set variation analysis analyses indicated that the 4 hub genes were significantly correlated with the regulation of immunity and metabolism in sepsis. The identified FAM89A, FFAR3, G0S2, and FGF13 genes may help elucidate the molecular mechanisms underlying sepsis and drive the introduction of new biomarkers to advance diagnosis and treatment.

Neutralization of extracellular histones by sodium-Β-O-methyl cellobioside sulfate in septic shock

BACKGROUND

Extracellular histones have been associated with severity and outcome in sepsis. The aim of the present study was to assess the effects of sodium-β-O-Methyl cellobioside sulfate (mCBS), a histone-neutralizing polyanion, on the severity and outcome of sepsis in an experimental model.

METHODS

This randomized placebo-controlled experimental study was performed in 24 mechanically ventilated female sheep. Sepsis was induced by fecal peritonitis. Animals were randomized to three groups: control, early treatment, and late treatment (n = 8 each). mCBS was given as a bolus (1 mg/kg) followed by a continuous infusion (1 mg/kg/h) just after sepsis induction in the early treatment group, and 4 h later in the late treatment group. Fluid administration and antimicrobial therapy were initiated 4 h T4 after feces injection, peritoneal lavage performed, and a norepinephrine infusion titrated to maintain mean arterial pressure (MAP) between 65-75 mmHg. The experiment was blinded and lasted maximum 24 h.

RESULTS

During the first 4 h, MAP remained > 65 mmHg in the early treatment group but decreased significantly in the others (p < 0.01 for interaction, median value at T4: (79 [70-90] mmHg for early treatment, 57 [70-90] mmHg for late treatment, and 55 [49-60] mmHg for the control group). mCBS-treated animals required significantly less norepinephrine to maintain MAP than controls (p < 0.01 for interaction) and had lower creatinine (p < 0.01), lactate (p < 0.01), and interleukin-6 (p < 0.01) levels, associated with reduced changes in H3.1 nucleosome levels (p = 0.02). Early treatment was associated with lower norepinephrine requirements than later treatment. Two control animals died; all the mCBS-treated animals survived.

CONCLUSIONS

Neutralization of extracellular histones with mCBS was associated with reduced norepinephrine requirements, improved tissue perfusion, less renal dysfunction, and lower circulating IL-6 in experimental septic shock and may represent a new therapeutic approach to be tested in clinical trials.

Impact of norepinephrine on immunity and oxidative metabolism in sepsis

Sepsis is a major health problem in the United States (US), constituting a leading contributor to mortality among critically ill patients. Despite advances in treatment the underlying pathophysiology of sepsis remains elusive. Reactive oxygen species (ROS) have a significant role in antimicrobial host defense and inflammation and its dysregulation leads to maladaptive responses because of excessive inflammation. There is growing evidence for crosstalk between the central nervous system and the immune system in response to infection. The hypothalamic-pituitary and adrenal axis and the sympathetic nervous system are the two major pathways that mediate this interaction. Epinephrine (Epi) and norepinephrine (NE), respectively are the effectors of these interactions. Upon stimulation, NE is released from sympathetic nerve terminals locally within lymphoid organs and activate adrenoreceptors expressed on immune cells. Similarly, epinephrine secreted from the adrenal gland which is released systemically also exerts influence on immune cells. However, understanding the specific impact of neuroimmunity is still in its infancy. In this review, we focus on the sympathetic nervous system, specifically the role the neurotransmitter norepinephrine has on immune cells. Norepinephrine has been shown to modulate immune cell responses leading to increased anti-inflammatory and blunting of pro-inflammatory effects. Furthermore, there is evidence to suggest that norepinephrine is involved in regulating oxidative metabolism in immune cells. This review attempts to summarize the known effects of norepinephrine on immune cell response and oxidative metabolism in response to infection.

INITIATION TIMING OF VASOPRESSOR IN PATIENTS WITH SEPTIC SHOCK: A SYSTEMATIC REVIEW AND META-ANALYSIS

ABSTRACT

Background: Vasopressor plays a crucial role in septic shock. However, the time for vasopressor initiation remains controversial. We conducted a systematic review and meta-analysis to explore its initiation timing for septic shock patients. Methods: PubMed, Cochrane Library, Embase, and Web of Sciences were searched from inception to July 12, 2023, for relevant studies. Primary outcome was short-term mortality. Meta-analysis was performed using Stata 15.0. Results: Twenty-three studies were assessed, including 2 randomized controlled trials and 21 cohort studies. The early group resulted in lower short-term mortality than the late group (OR [95% CI] = 0.775 [0.673 to 0.893], P = 0.000, I2 = 67.8%). The significance existed in the norepinephrine and vasopressin in subgroup analysis. No significant difference was considered in the association between each hour's vasopressor delay and mortality (OR [95% CI] = 1.02 [0.99 to 1.051], P = 0.195, I2 = 57.5%). The early group had an earlier achievement of target MAP ( P < 0.001), shorter vasopressor use duration ( P < 0.001), lower serum lactate level at 24 h ( P = 0.003), lower incidence of kidney injury ( P = 0.001), renal replacement therapy use ( P = 0.022), and longer ventilation-free days to 28 days ( P < 0.001). Conclusions: Early initiation of vasopressor (1-6 h within septic shock onset) would be more beneficial to septic shock patients. The conclusion needs to be further validated by more well-designed randomized controlled trials.

Optimizing Vasopressin Use and Initiation Timing in Septic Shock: A Narrative Review

TOPIC IMPORTANCE

This review discusses the rationale for vasopressin use, summarizes the results of clinical trials evaluating vasopressin, and focuses on the timing of vasopressin initiation to provide clinicians guidance for optimal adjunctive vasopressin initiation in patients with septic shock.

REVIEW FINDINGS

Patients with septic shock require vasoactive agents to restore adequate tissue perfusion. After norepinephrine, vasopressin is the suggested second-line adjunctive agent in patients with persistent inadequate mean arterial pressure. Vasopressin use in practice is heterogeneous likely because of inconsistent clinical trial findings, the lack of specific recommendations for when it should be used, and the high drug acquisition cost. Despite these limitations, vasopressin has demonstrated price inelastic demand, and its use in the United States has continued to increase. However, questions remain regarding optimal vasopressin use in patients with septic shock, particularly regarding patient selection and the timing of vasopressin initiation.

SUMMARY

Experimental studies evaluating the initiation timing of vasopressin in patients with septic shock are limited, and recent observational studies have revealed an association between vasopressin initiation at lower norepinephrine-equivalent doses or lower lactate concentrations and lower mortality.

Vasopressin in Sepsis and Other Shock States: State of the Art

This review of the use of vasopressin aims to be comprehensive and highly practical, based on the available scientific evidence and our extensive clinical experience with the drug. It summarizes controversies about vasopressin use in septic shock and other vasodilatory states. Vasopressin is a natural hormone with powerful vasoconstrictive effects and is responsible for the regulation of plasma osmolality by maintaining fluid homeostasis. Septic shock is defined by the need for vasopressors to correct hypotension and lactic acidosis secondary to infection, with a high mortality rate. The Surviving Sepsis Campaign guidelines recommend vasopressin as a second-line vasopressor, added to norepinephrine. However, these guidelines do not address specific debates surrounding the use of vasopressin in real-world clinical practice.

Stress circuitry: mechanisms behind nervous and immune system communication that influence behavior

Inflammatory processes are increased by stress and contribute to the pathology of mood disorders. Stress is thought to primarily induce inflammation through peripheral and central noradrenergic neurotransmission. In healthy individuals, these pro-inflammatory effects are countered by glucocorticoid signaling, which is also activated by stress. In chronically stressed individuals, the anti-inflammatory effects of glucocorticoids are impaired, allowing pro-inflammatory effects to go unchecked. Mechanisms underlying this glucocorticoid resistance are well understood, but the precise circuits and molecular mechanisms by which stress increases inflammation are not as well known. In this narrative review, we summarize the mechanisms by which chronic stress increases inflammation and contributes to the onset and development of stress-related mood disorders. We focus on the neural substrates and molecular mechanisms, especially those regulated by noradrenergic signaling, that increase inflammatory processes in stressed individuals. We also discuss key knowledge gaps in our understanding of the communication between nervous and immune systems during stress and considerations for future therapeutic strategies. Here we highlight the mechanisms by which noradrenergic signaling contributes to inflammatory processes during stress and how this inflammation can contribute to the pathology of stress-related mood disorders. Understanding the mechanisms underlying crosstalk between the nervous and immune systems may lead to novel therapeutic strategies for mood disorders and/or provide important considerations for treating immune-related diseases in individuals suffering from stress-related disorders.

Sepsis-Induced Acute Lung Injury Is Alleviated by Small Molecules from Dietary Plants via Pyroptosis Modulation

Sepsis-induced acute respiratory distress syndrome (ARDS) has high morbidity and mortality, and it has three major pathogeneses, namely alveolar-capillary barrier destruction, elevated gut permeability, and reduced neutrophil extracellular traps (NETS), all of which are pyroptosis-involved. Due to limitations of current agents like adverse reaction superposition, inevitable drug resistance, and relatively heavier financial burden, naturally extracted small-molecule compounds have a broad market even though chemically modified drugs have straightforward efficacy. Despite increased understanding of the molecular biology and mechanism underlying sepsis-induced ARDS, there are no specific reviews concerning how small molecules from dietary plants alleviate sepsis-induced acute lung injury (ALI) via regulating pyroptotic cell death. Herein, we traced and reviewed the molecular underpinnings of sepsis-induced ALI with a focus on small-molecule compounds from dietary plants, the top three categories of which are respectively flavonoids and flavone, terpenoids, and polyphenol and phenolic acids, and how they rescued septic ALI by restraining pyroptosis.

Phosphorylation of insulin receptor substrates (IRS-1 and IRS-2) is attenuated following cecal ligation and puncture in mice

BACKGROUND

Sepsis is characterized as an insulin resistant state. However, the effects of sepsis on insulin's signal transduction pathway are unknown. The molecular activity driving insulin signaling is controlled by tyrosine phosphorylation of the insulin receptor β-subunit (IRβ) and of insulin receptor substrate molecules (IRS) -1 and IRS-2.

HYPOTHESIS

Cecal ligation and puncture (CLP) attenuates IRβ, IRS-1 and IRS-2 phosphorylation.

METHODS

IACUC-approved studies conformed to ARRIVE guidelines. CLP was performed on C57BL/6 mice; separate cohorts received intraperitoneal insulin at baseline (T0) or at 23 or 47 h. post-CLP, 1 h before mice were euthanized. We measured levels of (1) glucose and insulin in serum, (2) IRβ, IRS-1 and IRS-2 in skeletal muscle and liver homogenate and (3) phospho-Irβ (pIRβ) in liver and skeletal muscle, phospho-IRS-1 (pIRS-1) in skeletal muscle and pIRS-2 in liver. Statistical significance was determined using ANOVA with Sidak's post-hoc correction.

RESULTS

CLP did not affect the concentrations of IRβ, IRS-1or IRS-2 in muscle or liver homogenate or of IRS-1 in liver. Muscle IRS-1 concentration at 48 h. post-CLP was higher than at T0. Post-CLP pIRS-1 levels in muscle and pIRβ and pIRS-2 levels in liver were indistinguishable from T0 levels. At 48 h. post-CLP pIRβ levels in muscle were higher than at T0. Following insulin administration, the relative abundance of pIRβ in muscle and liver at T0 and at both post-CLP time points was significantly higher than abundance in untreated controls. In T0 controls, the relative abundance of pIRS-1 in muscle and of pIRS-2 in liver following insulin administration was higher than in untreated mice. However, at both post-CLP time points, the relative abundance of pIRS-1 in muscle and of pIRS-2 in liver following insulin administration was not distinguishable from the abundance in untreated mice at the same time point. Serum glucose concentration was significantly lower than T0 at 24 h., but not 48 h., post-CLP. Glucose concentration was lower following insulin administration to T0 mice but not in post-CLP animals. Serum insulin levels were significantly higher than baseline at both post-CLP time points.

CONCLUSIONS

CLP impaired insulin-induced tyrosine phosphorylation of both IRS-1 in muscle and IRS-2 in liver. These findings suggest that the molecular mechanism underlying CLP-induced insulin resistance involves impaired IRS-1/IRS-2 phosphorylation.

The Eight Unanswered and Answered Questions about the Use of Vasopressors in Septic Shock

Septic shock is mainly characterized-in addition to hypovolemia-by vasoplegia as a consequence of a release of inflammatory mediators. Systemic vasodilatation due to depressed vascular tone results in arterial hypotension, which induces or worsens organ hypoperfusion. Accordingly, vasopressor therapy is mandatory to correct hypotension and to reverse organ perfusion due to hypotension. Currently, two vasopressors are recommended to be used, norepinephrine and vasopressin. Norepinephrine, an α₁-agonist agent, is the first-line vasopressor. Vasopressin is suggested to be added to norepinephrine in cases of inadequate mean arterial pressure instead of escalating the doses of norepinephrine. However, some questions about the bedside use of these vasopressors remain. Some of these questions have been well answered, some of them not clearly addressed, and some others not yet answered. Regarding norepinephrine, we firstly reviewed the arguments in favor of the choice of norepinephrine as a first-line vasopressor. Secondly, we detailed the arguments found in the recent literature in favor of an early introduction of norepinephrine. Thirdly, we reviewed the literature referring to the issue of titrating the doses of norepinephrine using an individualized resuscitation target, and finally, we addressed the issue of escalation of doses in case of refractory shock, a remaining unanswered question. For vasopressin, we reviewed the rationale for adding vasopressin to norepinephrine. Then, we discussed the optimal time for vasopressin administration. Subsequently, we addressed the issue of the optimal vasopressin dose, and finally we discussed the best strategy to wean these two vasopressors when combined.

Traumatic brain injury stimulates sympathetic tone-mediated bone marrow myelopoiesis to favor fracture healing

Traumatic brain injury (TBI) accelerates fracture healing, but the underlying mechanism remains largely unknown. Accumulating evidence indicates that the central nervous system (CNS) plays a pivotal role in regulating immune system and skeletal homeostasis. However, the impact of CNS injury on hematopoiesis commitment was overlooked. Here, we found that the dramatically elevated sympathetic tone accompanied with TBI-accelerated fracture healing; chemical sympathectomy blocks TBI-induced fracture healing. TBI-induced hypersensitivity of adrenergic signaling promotes the proliferation of bone marrow hematopoietic stem cells (HSCs) and swiftly skews HSCs toward anti-inflammation myeloid cells within 14 days, which favor fracture healing. Knockout of β3- or β2-adrenergic receptor (AR) eliminate TBI-mediated anti-inflammation macrophage expansion and TBI-accelerated fracture healing. RNA sequencing of bone marrow cells revealed that Adrb2 and Adrb3 maintain proliferation and commitment of immune cells. Importantly, flow cytometry confirmed that deletion of β2-AR inhibits M2 polarization of macrophages at 7th day and 14th day; and TBI-induced HSCs proliferation was impaired in β3-AR knockout mice. Moreover, β3- and β2-AR agonists synergistically promote infiltration of M2 macrophages in callus and accelerate bone healing process. Thus, we conclude that TBI accelerates bone formation during early stage of fracture healing process by shaping the anti-inflammation environment in the bone marrow. These results implicate that the adrenergic signals could serve as potential targets for fracture management.

The role of hormones in sepsis: an integrated overview with a focus on mitochondrial and immune cell dysfunction

Sepsis is a dysregulated host response to infection that results in life-threatening organ dysfunction. Virtually every body system can be affected by this syndrome to greater or lesser extents. Gene transcription and downstream pathways are either up- or downregulated, albeit with considerable fluctuation over the course of the patient's illness. This multi-system complexity contributes to a pathophysiology that remains to be fully elucidated. Consequentially, little progress has been made to date in developing new outcome-improving therapeutics. Endocrine alterations are well characterised in sepsis with variations in circulating blood levels and/or receptor resistance. However, little attention has been paid to an integrated view of how these hormonal changes impact upon the development of organ dysfunction and recovery. Here, we present a narrative review describing the impact of the altered endocrine system on mitochondrial dysfunction and immune suppression, two interlinked and key aspects of sepsis pathophysiology.

Norepinephrine dose, lactate or heart rate: what impacts prognosis in sepsis and septic shock? Results from a prospective, monocentric registry

OBJECTIVE

The study comprehensively investigates the prognostic value of norepinephrine (NE) dose, lactate and heart rate in patients with sepsis and septic shock.

BACKGROUND

Limited data regarding the prognostic value of NE dose, lactate and heart rate in patients meeting the sepsis-3 criteria is available.

METHODS

Consecutive patients with sepsis and septic shock from 2019 to 2021 were included. The prognostic value of NE dose, lactate and heart rate was tested for 30-day all-cause mortality. Statistical analyses included univariable t-tests, Spearman's correlations, C-statistics, Kaplan-Meier analyses, as well as one-factorial repeated measures analysis of variance (ANOVA) and Cox proportional regression analyses.

RESULTS

339 patients with sepsis or septic shock were included. With an area under the curve (AUC) of up to 0.638 and 0.685, NE dose and lactate revealed moderate prognostic accuracy for 30-day all-cause mortality, whereas heart rate was not associated with prognosis. Very high NE doses (i.e. > 1.0 mcg/kg/min) (HR = 2.938; 95% CI 1.933 - 4.464; p = .001) and lactate levels (i.e. ≥ 4 mmol/l) (HR = 2.963; 95% CI 2.095 - 4.191; p = .001) on admission were associated with highest risk of death. Finally, increasing NE doses and lactate levels from day 1 to 3 indicated increased risk of death, which was consistent after multivariable adjustment.

CONCLUSION

Both very high NE doses and lactate levels - but not heart rate - were associated with increased risk of 30-d all-cause mortality in patients with sepsis and septic shock.

Gut microbe-derived milnacipran enhances tolerance to gut ischemia/reperfusion injury

There are significant differences in the susceptibility of populations to intestinal ischemia/reperfusion (I/R), but the underlying mechanisms remain elusive. Here, we show that mice exhibit significant differences in susceptibility to I/R-induced enterogenic sepsis. Notably, the milnacipran (MC) content in the enterogenic-sepsis-tolerant mice is significantly higher. We also reveal that the pre-operative fecal MC content in cardiopulmonary bypass patients, including those with intestinal I/R injury, is associated with susceptibility to post-operative gastrointestinal injury. We reveal that MC attenuates mouse I/R injury in wild-type mice but not in intestinal epithelial aryl hydrocarbon receptor (AHR) gene conditional knockout mice (AHR^flox/flox) or IL-22 gene deletion mice (IL-22^-/-). Collectively, our results suggest that gut microbiota affects susceptibility to I/R-induced enterogenic sepsis and that gut microbiota-derived MC plays a pivotal role in tolerance to intestinal I/R in an AHR/ILC3/IL-22 signaling-dependent manner, revealing the pathological mechanism, potential prevention and treatment drugs, and treatment strategies for intestinal I/R.

Early adjunctive methylene blue in patients with septic shock: a randomized controlled trial

PURPOSE

Methylene blue (MB) has been tested as a rescue therapy for patients with refractory septic shock. However, there is a lack of evidence on MB as an adjuvant therapy, its' optimal timing, dosing and safety profile. We aimed to assess whether early adjunctive MB can reduce time to vasopressor discontinuation in patients with septic shock.

METHODS

In this single-center randomized controlled trial, we assigned patients with septic shock according to Sepsis-3 criteria to MB or placebo. Primary outcome was time to vasopressor discontinuation at 28 days. Secondary outcomes included vasopressor-free days at 28 days, days on mechanical ventilator, length of stay in ICU and hospital, and mortality at 28 days.

RESULTS

Among 91 randomized patients, forty-five were assigned to MB and 46 to placebo. The MB group had a shorter time to vasopressor discontinuation (69 h [IQR 59-83] vs 94 h [IQR 74-141]; p < 0.001), one more day of vasopressor-free days at day 28 (p = 0.008), a shorter ICU length of stay by 1.5 days (p = 0.039) and shorter hospital length of stay by 2.7 days (p = 0.027) compared to patients in the control group. Days on mechanical ventilator and mortality were similar. There were no serious adverse effects related to MB administration.

CONCLUSION

In patients with septic shock, MB initiated within 24 h reduced time to vasopressor discontinuation and increased vasopressor-free days at 28 days. It also reduced length of stay in ICU and hospital without adverse effects. Our study supports further research regarding MB in larger randomized clinical trials. Trial registration ClinicalTrials.gov registration number NCT04446871 , June 25, 2020, retrospectively registered.

Angiotensin 1-7 in an experimental septic shock model

BACKGROUND

Alterations in the renin-angiotensin system have been implicated in the pathophysiology of septic shock. In particular, angiotensin 1-7 (Ang-(1-7)), an anti-inflammatory heptapeptide, has been hypothesized to have beneficial effects. The aim of the present study was to test the effects of Ang-(1-7) infusion on the development and severity of septic shock.

METHODS

This randomized, open-label, controlled study was performed in 14 anesthetized and mechanically ventilated sheep. Immediately after sepsis induction by bacterial peritonitis, animals received either Ang-(1-7) (n = 7) or placebo (n = 7) intravenously. Fluid resuscitation, antimicrobial therapy, and peritoneal lavage were initiated 4 h after sepsis induction. Norepinephrine administration was titrated to maintain mean arterial pressure (MAP) between 65 and 75 mmHg.

RESULTS

There were no differences in baseline characteristics between groups. Septic shock was prevented in 6 of the 7 animals in the Ang-(1-7) group at the end of the 24-h period. Fluid balance and MAP were similar in the two groups; however, MAP was achieved with a mean norepinephrine dose of 0.4 μg/kg/min in the Ang-(1-7) group compared to 4.3 μg/kg/min in the control group. Heart rate and cardiac output index were lower in the Ang (1-7) than in the control group, as were plasma interleukin-6 levels, and creatinine levels. Platelet count and PaO2/FiO2 ratio were higher in the Ang-(1-7) group. Mean arterial lactate at the end of the experiment was 1.6 mmol/L in the Ang-(1-7) group compared to 7.4 mmol/L in the control group.

CONCLUSIONS

In this experimental septic shock model, early Ang-(1-7) infusion prevented the development of septic shock, reduced norepinephrine requirements, limited interleukine-6 increase and prevented renal dysfunction.

Vasopressin Response and Clinical Trajectory in Septic Shock Patients

BACKGROUND

In septic shock, vasopressors aim to improve tissue perfusion and prevent persistent organ dysfunction, a characteristic of chronic critical illness (CCI). Adjunctive vasopressin is often used to decrease catecholamine dosage, but the association of vasopressin response with subsequent patient outcomes is unclear. We hypothesized vasopressin response is associated with favorable clinical trajectory.

METHODS

We included patients with septic shock receiving vasopressin as a catecholamine adjunct in this retrospective cohort study. We defined vasopressin response as a lowering of the catecholamine dose required to maintain mean arterial pressure ≥65 mm Hg, 6 h after vasopressin initiation. Clinical trajectories were adjudicated as early death (ED; death before day 14), CCI (ICU stay ≥14 days with persistent organ dysfunction), or rapid recovery (RR; not meeting ED or CCI criteria). Trajectories were placed on an ordinal scale with ED the worst outcome, CCI next, and RR the best outcome. The association of vasopressin response with clinical trajectory was assessed with multivariable ordinal logistic regression.

RESULTS

In total 938 patients were included; 426 (45.4%) were vasopressin responders. The most frequent trajectory was ED (49.8%), 29.7% developed CCI, and 20.5% had rapid recovery. In survivors to ICU day 14 (those without ED), 59.2% had CCI and 40.8% experienced RR. Compared with vasopressin non-responders, vasopressin responders less frequently experienced ED (42.5% vs. 55.9%) and more frequently experienced RR (24.6% vs. 17.0%; P < 0.01). After controlling for confounders, vasopressin response was independently associated with higher odds of developing a better clinical trajectory (OR 1.63; 95% CI 1.26-2.10). Medical patients most frequently developed ED and survivors more commonly developed CCI than RR; surgical patients developed the three trajectories with similar frequency (P < 0.01).

CONCLUSIONS

Vasopressin responsive status was associated with improved clinical trajectory in septic shock patients. Early vasopressin response is a potential novel prognostic marker for short-term clinical trajectory.

Norepinephrine May Exacerbate Septic Acute Kidney Injury: A Narrative Review

Sepsis, the most serious complication of infection, occurs when a cascade of potentially life-threatening inflammatory responses is triggered. Potentially life-threatening septic shock is a complication of sepsis that occurs when hemodynamic instability occurs. Septic shock may cause organ failure, most commonly involving the kidneys. The pathophysiology and hemodynamic mechanisms of acute kidney injury in the case of sepsis or septic shock remain to be elucidated, but previous studies have suggested multiple possible mechanisms or the interplay of multiple mechanisms. Norepinephrine is used as the first-line vasopressor in the management of septic shock. Studies have reported different hemodynamic effects of norepinephrine on renal circulation, with some suggesting that it could possibly exacerbate acute kidney injury caused by septic shock. This narrative review briefly covers the updates on sepsis and septic shock regarding definitions, statistics, diagnosis, and management, with an explanation of the putative pathophysiological mechanisms and hemodynamic changes, as well as updated evidence. Sepsis-associated acute kidney injury remains a major burden on the healthcare system. This review aims to improve the real-world clinical understanding of the possible adverse outcomes of norepinephrine use in sepsis-associated acute kidney injury.

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

RATIONALE

To evaluate whether common nonsynonymous variants [single-nucleotide polymorphisms (SNPs) or SNP haplotypes] in the β2-adrenergic receptor render subjects more susceptible to norepinephrine-induced immunosuppression and whether they are associated with dysregulated ex vivo and in vivo inflammatory responses.

METHODS

Peripheral blood mononuclear cells from healthy volunteers (main cohort: n = 106, secondary cohort: n = 408) were ex vivo stimulated with various stimuli and production of cytokines was assessed. Additionally, ex vivo modulation of cytokine production by norepinephrine was evaluated in the main cohort. Volunteers from the main cohort also underwent experimental endotoxemia (administration of 1 ng/kg lipopolysaccharide), during which in vivo plasma cytokine concentrations and clinical inflammatory parameters were measured. Subjects were genotyped, common SNPs in the ADRB2 gene were extracted (rs1042711, rs1042713, and rs1042714), and the presence of haplotypes was identified (CysGlyGln, CysArgGln, and ArgGlyGlu).

RESULTS

In both cohorts, presence of ADRB2 SNPs or haplotypes was not associated with altered ex vivo cytokine responses. Norepinephrine attenuated production of the proinflammatory cytokines TNF and IL-6 [-26% (-22% to -30%) and -14% (-9% to -18%), respectively, both P < 0.0001] and enhanced release of the anti-inflammatory IL-10 [+9% (+3% to +15%), P = 0.003]. These effects were not modulated by the presence of ADRB2 SNPs or haplotypes (all P values >0.37). In addition, no influence of SNPs or haplotypes on in vivo cytokine concentrations or clinical inflammatory parameters was observed (P values >0.14).

CONCLUSIONS

Common nonsynonymous variants in the ADRB2 gene influence neither ex vivo cytokine production or norepinephrine-mediated immunosuppression nor the systemic in vivo inflammatory response induced by lipopolysaccharide administration in healthy volunteers.

Neuroendocrine Differentiation of Lung Cancer Cells Impairs the Activation of Antitumor Cytotoxic Responses in Mice

Lung cancer has the highest mortality among all types of cancer; during its development, cells can acquire neural and endocrine properties that affect tumor progression by releasing several factors, some acting as immunomodulators. Neuroendocrine phenotype correlates with invasiveness, metastasis, and low survival rates. This work evaluated the effect of neuroendocrine differentiation of adenocarcinoma on the mouse immune system. A549 cells were treated with FSK (forskolin) and IBMX (3-Isobutyl-1-methylxanthine) for 96 h to induce neuroendocrine differentiation (NED). Systemic effects were assessed by determining changes in circulating cytokines and immune cells of BALB/c mice immunized with PBS, undifferentiated A549 cells, or neuroendocrine A549_NED cells. A549 cells increased circulating monocytes, while CD4⁺CD8^- and CD4⁺CD8⁺ T cells increased in mice immunized with neuroendocrine cells. IL-2 and IL-10 increased in mice that received untreated A549 cells, suggesting that the immune system mounts a regulated response against adenocarcinoma, which did not occur with A549_NED cells. Cocultures demonstrated the cytotoxic capacity of PBMCs when confronted with A549 cells, while in the presence of neuroendocrine cells they not only were unable to show cytolytic activity, but also lost viability. Neuroendocrine differentiation seems to mount less of an immune response when injected in mice, which may contribute to the poor prognosis of cancer patients affected by this pathology.

Ageing and the Autonomic Nervous System

The vertebrate nervous system is divided into central (CNS) and peripheral (PNS) components. In turn, the PNS is divided into the autonomic (ANS) and enteric (ENS) nervous systems. Ageing implicates time-related changes to anatomy and physiology in reducing organismal fitness. In the case of the CNS, there exists substantial experimental evidence of the effects of age on individual neuronal and glial function. Although many such changes have yet to be experimentally observed in the PNS, there is considerable evidence of the role of ageing in the decline of ANS function over time. As such, this chapter will argue that the ANS constitutes a paradigm for the physiological consequences of ageing, as well as for their clinical implications.

Dopamine and norepinephrine are embracing their immune side and so should we

While the history of neuroimmunology is long, the explicit study of neuroimmune communication, and particularly the role of catecholamines in neuroimmunity, is still emerging. Recent studies have shown that catecholamines, norepinephrine, epinephrine, and dopamine, are central to multiple complex mechanisms regulating immune function. These studies show that catecholamines can be released from both the nervous system and directly from immune cells, mediating both autocrine and paracrine signaling. This commentary highlights the importance of catecholaminergic immunomodulation and discusses new considerations needed to study the role of catecholamines in immune homeostasis to best leverage their contribution to disease processes for the development of new therapeutic approaches.

Altered neutrophil-to-lymphocyte ratio in sepsis secondary to canine parvoviral enteritis treated with and without an immunomodulator in puppies

Neutrophil-to-lymphocyte ratio (NLR) is a cheap and easy-to-obtain biomarker that mirrors the balance between innate and adaptive immunity. Cortisol and catecholamines have been identified as major drivers of NLR. High cortisol levels increase neutrophils while simultaneously decreasing lymphocyte counts. Likewise, endogenous catecholamines may cause leukocytosis and lymphopenia. Thus, NLR allows us to monitor patient severity in conditions such as sepsis. Twenty-six puppies with sepsis secondary to canine parvoviral enteritis were treated with and without an immunomodulator. Our group determined the NLR and the plasmatic cortisol levels by chemiluminescence, and norepinephrine (NE) and epinephrine (E) by HPLC during the first 72 h of clinical follow-up. Our results showed that at admission puppies presented an NLR value of 1.8, cortisol of 314.9 nmol/L, NE 3.7, and E 3.3 pmol/mL. Both treatments decreased admission NLR values after 24 h of treatment. However, only the puppies treated with the immunomodulator (I) remained without significant changes in NLR (0.7-1.4) compared to the CT group, and that showed a significant difference (P < 0.01) in their NLR value (0.4-4.6). In addition, we found significant differences in the slope values between the admission and final values of NLR (P < 0.005), cortisol (P < 0.02), and E (P < 0.05) between treatments. Then, our data suggest that the immunomodulator positively affects the number of lymphocytes and neutrophils involved in NLR as well as major drivers like cortisol and epinephrine, which is reflected in clinical parameters and survival.

Epidemiology, Management, and Outcomes of Sepsis in ICUs among Countries of Differing National Wealth across Asia

Rationale: Directly comparative data on sepsis epidemiology and sepsis bundle implementation in countries of differing national wealth remain sparse. Objectives: To evaluate across countries/regions of differing income status in Asia 1) the prevalence, causes, and outcomes of sepsis as a reason for ICU admission and 2) sepsis bundle (antibiotic administration, blood culture, and lactate measurement) compliance and its association with hospital mortality. Methods: A prospective point prevalence study was conducted among 386 adult ICUs from 22 Asian countries/regions. Adult ICU participants admitted for sepsis on four separate days (representing the seasons of 2019) were recruited. Measurements and Main Results: The overall prevalence of sepsis in ICUs was 22.4% (20.9%, 24.5%, and 21.3% in low-income countries/regions [LICs]/lower middle-income countries/regions [LMICs], upper middle-income countries/regions, and high-income countries/regions [HICs], respectively; P < 0.001). Patients were younger and had lower severity of illness in LICs/LMICs. Hospital mortality was 32.6% and marginally significantly higher in LICs/LMICs than HICs on multivariable generalized mixed model analysis (adjusted odds ratio, 1.84; 95% confidence interval, 1.00-3.37; P = 0.049). Sepsis bundle compliance was 21.5% at 1 hour (26.0%, 22.1%, and 16.2% in LICs/LMICs, upper middle-income countries/regions, and HICs, respectively; P < 0.001) and 36.6% at 3 hours (39.3%, 32.8%, and 38.5%, respectively; P = 0.001). Delaying antibiotic administration beyond 3 hours was the only element independently associated with increased mortality (adjusted odds ratio, 2.53; 95% confidence interval, 2.07-3.08; P < 0.001). Conclusions: Sepsis is a common cause of admission to Asian ICUs. Mortality remains high and is higher in LICs/LMICs after controlling for confounders. Sepsis bundle compliance remains low. Delaying antibiotic administration beyond 3 hours from diagnosis is associated with increased mortality. Clinical trial registered with www.ctri.nic.in (CTRI/2019/01/016898).

Vasoplegic Syndrome after Cardiopulmonary Bypass in Cardiovascular Surgery: Pathophysiology and Management in Critical Care

Vasoplegic syndrome (VS) is a common complication following cardiovascular surgery with cardiopulmonary bypass (CPB), and its incidence varies from 5 to 44%. It is defined as a distributive form of shock due to a significant drop in vascular resistance after CPB. Risk factors of VS include heart failure with low ejection fraction, renal failure, pre-operative use of angiotensin-converting enzyme inhibitors, prolonged aortic cross-clamp and left ventricular assist device surgery. The pathophysiology of VS after CPB is multi-factorial. Surgical trauma, exposure to the elements of the CPB circuit and ischemia-reperfusion promote a systemic inflammatory response with the release of cytokines (IL-1β, IL-6, IL-8, and TNF-α) with vasodilating properties, both direct and indirect through the expression of inducible nitric oxide (NO) synthase. The resulting increase in NO production fosters a decrease in vascular resistance and a reduced responsiveness to vasopressor agents. Further mechanisms of vasodilation include the lowering of plasma vasopressin, the desensitization of adrenergic receptors, and the activation of ATP-dependent potassium (KATP) channels. Patients developing VS experience more complications and have increased mortality. Management includes primarily fluid resuscitation and conventional vasopressors (catecholamines and vasopressin), while alternative vasopressors (angiotensin 2, methylene blue, hydroxocobalamin) and anti-inflammatory strategies (corticosteroids) may be used as a rescue therapy in deteriorating patients, albeit with insufficient evidence to provide any strong recommendation. In this review, we present an update of the pathophysiological mechanisms of vasoplegic syndrome complicating CPB and discuss available therapeutic options.

Silencing of Salmonella typhimurium Pathogenesis: Atenolol Acquires Efficient Anti-Virulence Activities

The targeting of bacterial virulence is proposed as a promising approach to overcoming the bacterial resistance development to antibiotics. Salmonella enterica is one of the most important gut pathogens that cause a wide diversity of local and systemic illnesses. The Salmonella virulence is controlled by interplayed systems namely Quorum sensing (QS) and type three secretion system (T3SS). Furthermore, the Salmonella spy on the host cell via sensing the adrenergic hormones enhancing its virulence. The current study explores the possible anti-virulence activities of β-adrenoreceptor blocker atenolol against S. enterica serovar Typhimurium in vitro, in silico, and in vivo. The present findings revealed a significant atenolol ability to diminish the S. typhimurium biofilm formation, invasion into HeLa cells, and intracellular replication inside macrophages. Atenolol significantly downregulated the encoding genes of the T3SS-type II, QS receptor Lux analogs sdiA, and norepinephrine membranal sensors qseC and qseE. Moreover, atenolol significantly protected mice against S. typhimurium. For testing the possible mechanisms for atenolol anti-virulence activities, an in silico molecular docking study was conducted to assess the atenolol binding ability to QS receptor SdiA and norepinephrine membranal sensors QseC. Atenolol showed the ability to compete on the S. typhimurium targets. In conclusion, atenolol is a promising anti-virulence candidate to alleviate the S. typhimurium pathogenesis by targeting its QS and T3SS systems besides diminishing the eavesdropping on the host cells.

Optimal target blood pressure in elderly with septic shock (OPTPRESS) trial: study protocol for a randomized controlled trial

Background

Hemodynamic stabilization is a core component in the resuscitation of septic shock. However, the optimal target blood pressure remains debatable. Previous randomized controlled trials suggested that uniformly adopting a target mean arterial pressure (MAP) higher than 65 mmHg for all adult septic shock patients would not be beneficial; however, it has also been proposed that higher target MAP may be beneficial for elderly patients, especially those with arteriosclerosis.

Methods

A multicenter, pragmatic single-blind randomized controlled trial will be conducted to compare target MAP of 80–85 mmHg (high-target) and 65–70 mmHg (control) in the resuscitation of septic shock patients admitted to 28 hospitals in Japan. Patients with septic shock aged ≥65 years are randomly assigned to the high-target or control groups. The target MAP shall be maintained for 72 h after randomization or until vasopressors are no longer needed to improve patients’ condition. To minimize the adverse effects related to catecholamines, if norepinephrine dose of ≥ 0.1 μg/kg/min is needed to maintain the target MAP, vasopressin will be initiated. Other therapeutic approaches, including fluid administration, hydrocortisone use, and antibiotic choice, will be determined by the physician in charge based on the latest clinical guidelines. The primary outcome is all-cause mortality at 90 days after randomization.

Discussion

The result of this trial will provide great insight on the resuscitation strategy for septic shock in the era of global aged society. Also, it will provide the better understanding on the importance of individualized treatment strategy in hemodynamic management in critically ill patients.

Trial registration

UMIN Clinical Trials Registry; UMIN000041775. Registered 13 September 2020.

Systemic immune responses after ischemic stroke: From the center to the periphery

Ischemic stroke is a leading cause of disability and death. It imposes a heavy economic burden on individuals, families and society. The mortality rate of ischemic stroke has decreased with the help of thrombolytic drug therapy and intravascular intervention. However, the nerve damage caused by ischemia-reperfusion is long-lasting and followed by multiple organ dysfunction. In this process, the immune responses manifested by systemic inflammatory responses play an important role. It begins with neuroinflammation following ischemic stroke. The large number of inflammatory cells released after activation of immune cells in the lesion area, along with the deactivated neuroendocrine and autonomic nervous systems, link the center with the periphery. With the activation of systemic immunity and the emergence of immunosuppression, peripheral organs become the second “battlefield” of the immune response after ischemic stroke and gradually become dysfunctional and lead to an adverse prognosis. The purpose of this review was to describe the systemic immune responses after ischemic stroke. We hope to provide new ideas for future research and clinical treatments to improve patient outcomes and quality of life.

Myocardial effects of angiotensin II compared to norepinephrine in an animal model of septic shock

BACKGROUND

Angiotensin II is one of the vasopressors available for use in septic shock. However, its effects on the septic myocardium remain unclear. The aim of the study was to compare the effects of angiotensin II and norepinephrine on cardiac function and myocardial oxygen consumption, inflammation and injury in experimental septic shock.

METHODS

This randomized, open-label, controlled study was performed in 20 anesthetized and mechanically ventilated pigs. Septic shock was induced by fecal peritonitis in 16 animals, and four pigs served as shams. Resuscitation with fluids, antimicrobial therapy and abdominal drainage was initiated one hour after the onset of septic shock. Septic pigs were randomly allocated to receive one of the two drugs to maintain mean arterial pressure between 65 and 75 mmHg for 8 h.

RESULTS

There were no differences in MAP, cardiac output, heart rate, fluid balance or tissue perfusion indices in the two treatment groups but myocardial oxygen consumption was greater in the norepinephrine-treated animals. Myocardial mRNA expression of interleukin-6, interleukin-6 receptor, interleukin-1 alpha, and interleukin-1 beta was higher in the norepinephrine than in the angiotensin II group.

CONCLUSIONS

In septic shock, angiotensin II administration is associated with a similar level of cardiovascular resuscitation and less myocardial oxygen consumption, and inflammation compared to norepinephrine.

Angiotensin II enhances bacterial clearance via myeloid signaling in a murine sepsis model

Sepsis, defined as organ dysfunction caused by a dysregulated host-response to infection, is characterized by immunosuppression. The vasopressor norepinephrine is widely used to treat low blood pressure in sepsis but exacerbates immunosuppression. An alternative vasopressor is angiotensin-II, a peptide hormone of the renin-angiotensin system (RAS), which displays complex immunomodulatory properties that remain unexplored in severe infection. In a murine cecal ligation and puncture (CLP) model of sepsis, we found alterations in the surface levels of RAS proteins on innate leukocytes in peritoneum and spleen. Angiotensin-II treatment induced biphasic, angiotensin-II type 1 receptor (AT1R)-dependent modulation of the systemic inflammatory response and decreased bacterial counts in both the blood and peritoneal compartments, which did not occur with norepinephrine treatment. The effect of angiotensin-II was preserved when treatment was delivered remote from the primary site of infection. At an independent laboratory, angiotensin-II treatment was compared in LysM-Cre AT1aR-/- (Myeloid-AT1a-) mice, which selectively do not express AT1R on myeloid-derived leukocytes, and littermate controls (Myeloid-AT1a+). Angiotensin-II treatment significantly reduced post-CLP bacteremia in Myeloid-AT1a+ mice but not in Myeloid-AT1a- mice, indicating that the AT1R-dependent effect of angiotensin-II on bacterial clearance was mediated through myeloid-lineage cells. Ex vivo, angiotensin-II increased post-CLP monocyte phagocytosis and ROS production after lipopolysaccharide stimulation. These data identify a mechanism by which angiotensin-II enhances the myeloid innate immune response during severe systemic infection and highlight a potential role for angiotensin-II to augment immune responses in sepsis.

The effect of continuous intravenous norepinephrine infusion on systemic hemodynamics in a telemetrically-monitored mouse model of sepsis

Sepsis, a life-threatening organ dysfunction, results from dysregulated host responses to infection and still has a high incidence and mortality. Although administration of vasopressors to treat septic shock is standard of care, the benefits are not well established. We evaluated the effect of continuous intravenous norepinephrine infusion in a septic cecal ligation and puncture (CLP) mouse model, evaluating systemic hemodynamics and body temperature post-hoc. CLP surgery significantly decreased mean arterial blood pressure (MAP), heart rate, and body temperature within six hours. Continuous norepinephrine infusion (NE+, n = 12) started at the time of CLP surgery significantly increased MAP at 24 and 30 hours and heart rate at 6, 18, 24, and 30 hours after CLP vs CLP alone (NE-, n = 12). However, addition of norepinephrine did not improve survival rate (NE+ n = 34, NE- n = 31). Early (6 hours or earlier, when the animal became visibly sick) MAP did not predict 7-day mortality. However, heart rates at 3 and at 6 hours after CLP/norepinephrine (NE+) were highly predictive of mortality, as also been found in one clinical study. We conclude that limited hemodynamic support can be provided in a mouse sepsis model. We propose that heart rate can be used to stratify severity of illness in rodent preclinical studies of sepsis therapeutics.

Modulation of Neuroendocrine and Immunological Biomarkers Following Rehabilitation in Sarcopenic Patients

This study aimed to investigate if rehabilitation could down-regulated sarcopenia-associated inflammation by modulating the crosstalk between the neuroendocrine and immune systems, with the aim of ameliorating quality of life of sarcopenic subjects. A total of 60 sarcopenic patients (49 females and 11 males; median age 74.5, interquartile range 71–79), undergoing a personalized rehabilitation program, have been recruited and subjected to: (1) functional and physical evaluation (Short Physical Performance Battery (SPPB), Barthel Index and Tinetti Test); (2) pro-inflammatory IL-1β, TNF-α, IL-6, IL-18, and anti-inflammatory IL-10 cytokines plasmatic level measures; and (3) norepinephrine, epinephrine, dopamine, and serotonin neurotransmitter level evaluation at time of enrollment (T0) and once rehabilitation was concluded (1 month, T1). Rehabilitation combined a balance and strength training program with two daily sessions that were fine-tuned and personalized according to the ability of the patient. The results showed a significant increase at T1 in the plasmatic levels of IL-10 (p = 0.018) and of norepinephrine (p = 0.016)), whereas the concentration of IL-18 was significantly reduced (p = 0.012). Notably, changes in norepinephrine were positively correlated with clinical improvements (Tinetti and Barthel scores, p ≤ 0.0001; SPPB scores, p = 0.0002). These results show that efficient rehabilitation induces a reduction of inflammation, suggesting that this effect could be mediated by a modulation of the neuro-immune axis that results in an increase of norepinephrine.