Association of angiotensin II type 1 receptor-associated protein gene polymorphism with increased mortality in septic shock*:

Impaired angiotensin II signaling in septic shock

Recent years have seen a resurgence of interest for the renin-angiotensin-aldosterone system in critically ill patients. Emerging data suggest that this vital homeostatic system, which plays a crucial role in maintaining systemic and renal hemodynamics during stressful conditions, is altered in septic shock, ultimately leading to impaired angiotensin II-angiotensin II type 1 receptor signaling. Indeed, available evidence from both experimental models and human studies indicates that alterations in the renin-angiotensin-aldosterone system during septic shock can occur at three distinct levels: 1. Impaired generation of angiotensin II, possibly attributable to defects in angiotensin-converting enzyme activity; 2. Enhanced degradation of angiotensin II by peptidases; and/or 3. Unavailability of angiotensin II type 1 receptor due to internalization or reduced synthesis. These alterations can occur either independently or in combination, ultimately leading to an uncoupling between the renin-angiotensin-aldosterone system input and downstream angiotensin II type 1 receptor signaling. It remains unclear whether exogenous angiotensin II infusion can adequately address all these mechanisms, and additional interventions may be required. These observations open a new avenue of research and offer the potential for novel therapeutic strategies to improve patient prognosis. In the near future, a deeper understanding of renin-angiotensin-aldosterone system alterations in septic shock should help to decipher patients' phenotypes and to implement targeted interventions.

Adverse Clinical Effects Associated With Non-catecholamine Pharmacologic Agents for Treatment of Vasoplegic Syndrome in Adult Cardiac Surgery

Vasoplegic syndrome is a relatively common complication that can happen during and after major adult cardiac surgery. It is associated with a higher rate of complications, including postoperative renal failure, longer duration of mechanical ventilation, and intensive care unit stay, as well as increased mortality. The underlying pathophysiology of vasoplegic syndrome is that of profound vascular hyporesponsiveness, and involves a complex interplay among inflammatory cytokines, cellular surface receptors, and nitric oxide (NO) production. The pharmacotherapy approaches for the treatment of vasoplegia include medications that increase vascular smooth muscle contraction via increasing cytosolic calcium in myocytes, reduce the vascular effects of NO and inflammation, and increase the biosynthesis of and vascular response to norepinephrine. Clinical trials have demonstrated the clinical efficacy of non-catecholamine pharmacologic agents in the treatment of vasoplegic syndrome. With an increase in their use today, it is important for clinicians to understand the adverse clinical outcomes and patient risk profiles associated with these agents, which will allow better-tailored medical therapy.

Precision fluid and vasoactive drug therapy for critically ill patients

There are several clinical practice guidelines concerning the use of fluid and vasoactive drug therapies in critically ill adult patients, but the recommendations in these guidelines are often based on low-quality evidence. Further, some were compiled prior to the publication of landmark clinical trials, particularly in the comparison of balanced crystalloid and normal saline. An important consideration in the treatment of critically ill patients is the application of precision medicine to provide the most effective care to groups of patients most likely to benefit from the therapy. Although not currently widely integrated into these practice guidelines, the utility of precision medicine in critical illness is a recognized research priority for fluid and vasoactive therapy management. The purpose of this narrative review was to illustrate the evaluation and challenges of providing precision fluid and vasoactive therapies to adult critically ill patients. The review includes a discussion of important investigations published after the release of currently available clinical practice guidelines to provide insight into how recommendations and research priorities may change future guidelines and bedside care for critically ill patients.

Early administration of multiple vasopressors is associated with better survival in patients with sepsis: a propensity score-weighted study

BACKGROUND

The association between the timing of administration of multiple vasopressors and patient outcomes has not been investigated.

METHODS

This study used data from the MIMIC-IV database. Patients with sepsis who were administered two or more vasopressors were included. The principal exposure was the last norepinephrine dose when adding a second vasopressor. The cohort was divided into early (last norepinephrine dose < 0.25 μg/kg/min) and normal (last norepinephrine dose ≥ 0.25 μg/kg/min) groups. The primary outcome was 28-day mortality. Multivariable Cox analyses, propensity score matching, stabilized inverse probability of treatment weighting (sIPTW), and restricted cubic spline (RCS) curves were used.

RESULTS

Overall, 1,437 patients who received multiple vasopressors were included. Patients in the early group had lower 28-day mortality (HR: 0.76; 95% CI: 0.65-0.89; p < 0.001) than those in the single group, with similar results in the propensity score-matched (HR: 0.80; 95% CI: 0.68-0.94; p = 0.006) and sIPTW (HR: 0.75; 95% CI: 0.63-0.88; p < 0.001) cohorts. RCS curves showed that the risk of 28-day mortality increased as the last norepinephrine dose increased.

CONCLUSIONS

The timing of secondary vasopressor administration is strongly associated with the outcomes of patients with sepsis.

VASOPRESSOR-RESISTANT HYPOTENSION, COMBINATION VASOPRESSOR THERAPY, AND SHOCK PHENOTYPES IN CRITICALLY ILL ADULTS WITH VASODILATORY SHOCK

ABSTRACT

Objective: To examine the risk factors, resource utilization, and 1-year mortality associated with vasopressor-resistant hypotension (VRH) compared with vasopressor-sensitive hypotension (VSH) among critically ill adults with vasodilatory shock. We also examined whether combination vasopressor therapy and patient phenotype were associated with mortality. Design: Retrospective cohort study. Setting: Eight medical-surgical intensive care units at the University of Pittsburgh Medical Center, Pittsburgh, PA. Patients : Critically ill patients with vasodilatory shock admitted between July 2000 and October 2008. Interventions : None. Measurements and Main Results: Vasopressor-resistant hypotension was defined as those requiring greater than 0.2 μg/kg per minute of norepinephrine equivalent dose of vasopressor consecutively for more than 6 h, and VSH was defined as patients requiring ≤0.2 μg/kg per minute to maintain MAP between 55 and 70 mm Hg after adequate fluid resuscitation. Of 5,313 patients with vasodilatory shock, 1,291 patients (24.3%) developed VRH. Compared with VSH, VRH was associated with increased risk of acute kidney injury (72.7% vs. 65.0%; P < 0.001), use of kidney replacement therapy (26.0% vs. 11.0%; P < 0.001), longer median (interquartile range [IQR]) intensive care unit length of stay (10 [IQR, 4.0-20.0] vs. 6 [IQR, 3.0-13.0] days; P < 0.001), and increased 1-year mortality (64.7% vs. 34.8%; P < 0.001). Vasopressor-resistant hypotension was associated with increased odds of risk-adjusted mortality (adjusted odds ratio [aOR], 2.93; 95% confidence interval [CI], 2.52-3.40; P < 0.001). When compared with monotherapy, combination vasopressor therapy with two (aOR, 0.91; 95% CI, 0.78-1.06) and three or more vasopressors was not associated with lower mortality (aOR, 0.93; 95% CI, 0.68-1.27). Using a finite mixture model, we identified four unique phenotypes of patient clusters that differed with respect to demographics, severity of illness, processes of care, vasopressor use, and outcomes. Conclusions: Among critically ill patients with vasodilatory shock, VRH compared with VSH is associated with increased resource utilization and long-term risk of death. However, combination vasopressor therapy was not associated with lower risk of death. We identified four unique phenotypes of patient clusters that require further validation.

Vasopressor Choice and Timing in Vasodilatory Shock

This article is one of ten reviews selected from the Annual Update in Intensive Care and Emergency Medicine 2022. Other selected articles can be found online at https://www.biomedcentral.com/collections/annualupdate2022 . Further information about the Annual Update in Intensive Care and Emergency Medicine is available from https://link.springer.com/bookseries/8901 .

Study protocol for a multicentre, prospective cohort study of the association of angiotensin II type 1 receptor blockers on outcomes of coronavirus infection

INTRODUCTION

The COVID-19 epidemic grows and there are clinical trials of antivirals. There is an opportunity to complement these trials with investigation of angiotensin II type 1 receptor blockers (ARBs) because an ARB (losartan) was effective in murine influenza pneumonia.

METHODS AND ANALYSIS

Our innovative design includes: ARBs; alignment with the WHO Ordinal Scale (primary endpoint) to align with other COVID-19 trials; joint longitudinal analysis; and predictive biomarkers (angiotensins I, 1-7, II and ACE1 and ACE2). Our hypothesis is: ARBs decrease the need for hospitalisation, severity (need for ventilation, vasopressors, extracorporeal membrane oxygenation or renal replacement therapy) or mortality of hospitalised COVID-19 infected adults. Our two-pronged multicentre pragmatic observational cohort study examines safety and effectiveness of ARBs in (1) hospitalised adult patients with COVID-19 and (2) out-patients already on or not on ARBs. The primary outcome will be evaluated by ordinal logistic regression and main secondary outcomes by both joint longitudinal modelling analyses. We will compare rates of hospitalisation of ARB-exposed versus not ARB-exposed patients. We will also determine whether continuing ARBs or not decreases the primary outcome. Based on published COVID-19 cohorts, assuming 15% of patients are ARB-exposed, a total sample size of 497 patients can detect a proportional OR of 0.5 (alpha=0.05, 80% power) comparing WHO scale of ARB-exposed versus non-ARB-exposed patients.

ETHICS AND DISSEMINATION

This study has core institution approval (UBC Providence Healthcare Research Ethics Board) and site institution approvals (Health Research Ethics Board, University of Alberta; Comite d'etique de la recerche, CHU Sainte Justine (for McGill University and University of Sherbrook); Conjoint Health Research Ethics Board, University of Calgary; Queen's University Health Sciences & Affiliated Hospitals Research Ethics Board; Research Ethics Board, Sunnybrook Health Sciences Centre; Veritas Independent Research Board (for Humber River Hospital); Mount Sinai Hospital Research Ethics Board; Unity Health Toronto Research Ethics Board, St. Michael's Hospital). Results will be disseminated by peer-review publication and social media releases.

TRIAL REGISTRATION NUMBER

NCT04510623.

Vasopressor Therapy in the Intensive Care Unit

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

Roles of angiotensin II as vasopressor in vasodilatory shock

Shock is an acute condition of circulatory failure resulting in life-threatening organ dysfunction, high morbidity and high mortality. Current management includes fluid and catecholamine therapy to maintain adequate mean arterial pressure and organ perfusion. Norepinephrine is recommended as first-line vasopressor, but other agents are available. Angiotensin II is an alternative potent vasoconstrictor without chronotropic or inotropic properties. Several studies, including a large randomized controlled trial have demonstrated its ability to increase blood pressure with catecholamine-sparing effects. Angiotensin II was consequently approved by the US FDA in 2017 and the EU in 2019 as an add-on vasopressor in vasodilatory shock. This review aims to discuss its basic pharmacology, clinical efficacy, safety and future perspectives.

Vasopressor therapy in critically ill patients with shock

BACKGROUND

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

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Vasopressor therapy in critically ill patients with shock

BACKGROUND

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

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Outcomes in Patients with Vasodilatory Shock and Renal Replacement Therapy Treated with Intravenous Angiotensin II

Supplemental Digital Content is available in the text.

Objective:

Acute kidney injury requiring renal replacement therapy in severe vasodilatory shock is associated with an unfavorable prognosis. Angiotensin II treatment may help these patients by potentially restoring renal function without decreasing intrarenal oxygenation. We analyzed the impact of angiotensin II on the outcomes of acute kidney injury requiring renal replacement therapy.

Design:

Post hoc analysis of the Angiotensin II for the Treatment of High-Output Shock 3 trial.

Setting:

ICUs.

Patients:

Patients with acute kidney injury treated with renal replacement therapy at initiation of angiotensin II or placebo (n = 45 and n = 60, respectively).

Interventions:

IV angiotensin II or placebo.

Measurements and Main Results:

Primary end point: survival through day 28; secondary outcomes included renal recovery through day 7 and increase in mean arterial pressure from baseline of ≥ 10 mm Hg or increase to ≥ 75 mm Hg at hour 3. Survival rates through day 28 were 53% (95% CI, 38%–67%) and 30% (95% CI, 19%–41%) in patients treated with angiotensin II and placebo (p = 0.012), respectively. By day 7, 38% (95% CI, 25%–54%) of angiotensin II patients discontinued RRT versus 15% (95% CI, 8%–27%) placebo (p = 0.007). Mean arterial pressure response was achieved in 53% (95% CI, 38%–68%) and 22% (95% CI, 12%–34%) of patients treated with angiotensin II and placebo (p = 0.001), respectively.

Conclusions:

In patients with acute kidney injury requiring renal replacement therapy at study drug initiation, 28-day survival and mean arterial pressure response were higher, and rate of renal replacement therapy liberation was greater in the angiotensin II group versus the placebo group. These findings suggest that patients with vasodilatory shock and acute kidney injury requiring renal replacement therapy may preferentially benefit from angiotensin II.

Broad spectrum vasopressors: a new approach to the initial management of septic shock?

The mainstay of hemodynamic treatment of septic shock is fluid resuscitation followed by vasopressors where fluids alone are insufficient to achieve target blood pressure. Norepinephrine, a catecholamine, is the first-line vasopressor used worldwide but given that all routinely used catecholamines target the same adrenergic receptors, many clinicians may add a non-catecholamine vasopressor where refractory hypotension due to septic shock is present. However, the timing of this additional intervention is variable. This decision is based on three key factors: availability, familiarity, and safety profile. In our opinion, further consideration should be potential vasopressor response because following appropriate volume resuscitation, the response to different vasopressor classes is neither uniform nor predictable. Critically ill patients who are non-responders to high-dose catecholamines have a dismal outcome. Similarly, patients have a variable response to non-catecholamine agents including vasopressin and angiotensin II: but where patients exhibit a blood pressure response the outcomes are improved over non-responders. This variable responsiveness to vasopressors is similar to the clinical approach of anti-microbial sensitivity. In this commentary, the authors propose the concept of “broad spectrum vasopressors” wherein patients with septic shock are started on multiple vasopressors with a different mechanism of action simultaneously while the vasopressor sensitivity is assessed. Once the vasopressor sensitivities are assessed, then the vasopressors are ‘de-escalated’ accordingly. We believe that this concept may offer a new approach to the treatment of septic shock.

Hydrocortisone in Vasodilatory Shock

Vasodilatory shock is the most common type of circulatory shock in critically ill patients; sepsis the predominant cause. Steroid use in septic shock gained favor in the 1970s; however, studies of high-dose steroids demonstrated excess morbidity and mortality. Lower dosage steroid use was driven by trials demonstrating improved hemodynamic status and the possibility of relative adrenal insufficiency; however, divergent results led to uncertainty about hydrocortisone treatment. Two recent trials are likely to reinforce the role of steroids in septic shock and change the recommendation in future clinical practice guidelines. Future work could include elucidating mechanisms of shock reversal, interaction of hydrocortisone with other agents, identifying steroid responsiveness using biochemical or gene signatures, and clarifying the role of fludrocortisone.

Pathophysiology of Septic Shock

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

Identification of key pathogenic genes of sepsis based on the Gene Expression Omnibus database

Sepsis is a life-threatening condition in which an uncontrolled inflammatory host response is triggered. The exact pathogenesis of sepsis remains unclear. The aim of the present study was to identify key genes that may aid in the diagnosis and treatment of sepsis. mRNA expression data from blood samples taken from patients with sepsis and healthy individuals was downloaded from the Gene Expression Omnibus database and differentially expressed genes (DEGs) between the two groups were identified. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis, and protein-protein interaction (PPI) network construction, was performed to investigate the function of the identified DEGs. Furthermore, for validation of these results, the expression levels of several DEGs were analyzed by reverse transcription quantitative-polymerase chain reaction (RT-qPCR) in three patients with sepsis and three healthy blood samples to support the results obtained from the bioinformatics analysis. Receiver operating characteristic analyses were also used to analyze the diagnostic ability of the identified DEGs for sepsis. The results demonstrated that a total of 4,402 DEGs, including 1,960 upregulated and 2,442 downregulated genes, were identified between patients with sepsis and healthy individuals. KEGG pathway analysis revealed that 39 DEGs were significantly enriched in toll-like receptor signaling pathways. The top 20 upregulated and downregulated DEGs were used to construct the PPI network. Hub genes with high degrees, including interleukin 1 receptor-associated kinase 3 (IRAK3), S100 calcium-binding protein (S100)A8, angiotensin II receptor-associated protein (AGTRAP) and S100A9, were demonstrated to be associated sepsis. Furthermore, RT-qPCR results demonstrated that IRAK3, adrenomedullin (ADM), arachidonate 5-lipoxygenase (ALOX5), matrix metallopeptidase 9 (MMP9) and S100A8 were significantly upregulated, while ectonucleoside triphosphate diphosphohydrolase 1 (ENTPD1) was upregulated but not significantly, in blood samples from patients with sepsis compared with healthy individuals, which was consistent with bioinformatics analysis results. Therefore, AGTRAP, IRAK3, ADM, ALOX5, MMP9, S100A8 and ENTPD1 were identified to have potential diagnostic value in sepsis. In conclusion, dysregulated levels of the AGTRAP, IRAK3, ADM, ALOX5, MMP9, S100A8 and ENTPD1 genes may be involved in sepsis pathophysiology and may be utilized as potential diagnostic biomarkers or therapeutic targets.

Correlations between ACE single nucleotide polymorphisms and prognosis of patients with septic shock

The aim of the present study is to investigate association between septic shock (SS) and angiotensin I-converting enzyme (ACE) single nucleotide polymorphisms (SNPs). From October 2009 to December 2016, 238 SS patients and 242 healthy individuals were selected for our study. ACE activity was detected, ACE rs4291 and rs4646994 polymorphisms were detected using PCR-restriction fragment length polymorphism (PCR-RFLP). The Kaplan–Meier survival curve was employed to evaluate the association between ACE SNPs and patients’ survival and univariate and multivariate analyses to estimate risk factors for SS. ACE activity in the case group was increased in comparison with the control group. Allele and genotype frequencies of rs4291 and rs4646994 were different between the case and control groups. The TT genotype frequency of the rs4291 polymorphisms and the DD genotype of the rs4646994 polymorphisms of the case group were higher than those in the control group. The AT and TT genotypes indicated a significant elevation of ACE activity than the AA genotype, while a significant decline was found in the DI and II genotypes in comparison with the DI genotype. Patients with TT or DD genotypes had increased fatality rate within 7 and 30 days when compared with those with non-TT or non-DD genotypes. Lower sepsis-related organ failure assessment (SOFA) scores, rs4291, serum ACE and rs4646994 were all considered as risky factors for SS patients. The study demonstrates that TT genotype of rs4291 or DD genotype of rs4646994 may be indicative of a higher risk of SS and a poorer prognosis in SS patients.

Sepsis: frontiers in diagnosis, resuscitation and antibiotic therapy

Sepsis is a major growing global burden and a major challenge to intensive care clinicians, researchers, guideline committee members and policy makers, because of its high and increasing incidence and great pathophysiological, molecular, genetic and clinical complexity. In spite of recent progress, short-term mortality remains high and there is growing evidence of long-term morbidity and increased long-term mortality in survivors of sepsis both in developed and developing countries. Further improvement in the care of patients with sepsis will impact upon global health. In this narrative review, invited experts describe the expected challenges and progress to be made in the near future. We focus on diagnosis, resuscitation (fluids, vasopressors, inotropes, blood transfusion and hemodynamic targets) and infection (antibiotics and infection biomarkers), as these areas are key, if initial management and subsequent outcomes are to be improved in patients with sepsis.

Genomics and pharmacogenomics of sepsis: so close and yet so far

Sapru et al. show in this issue of Critical Care that variants of thrombomodulin and the endothelial protein C receptor, but not protein C, are associated with mortality and organ dysfunction (ventilation-free and organ failure-free days) in ARDS. Hundreds of gene variants have been found prognostic in sepsis. However, none of these prognostic genomic biomarkers are used clinically. Predictive biomarker discovery (pharmacogenomics) usually follows a candidate gene approach, utilizing knowledge of drug pathways. Pharmacogenomics could be applied to enhance efficacy and safety of drugs used for treatment of sepsis (e.g., norepinephrine, epinephrine, vasopressin, and corticosteroids). Pharmacogenomics can enhance drug development in sepsis, which is very important because there is no approved drug for sepsis. Pharmacogenomics biomarkers must pass three milestones: scientific, regulatory, and commercial. Huge challenges remain but great opportunities for pharmacogenomics of sepsis are on the horizon.

TNFAIP2 Inhibits Early TNFα-Induced NF-x03BA;B Signaling and Decreases Survival in Septic Shock Patients

During septic shock, tumor necrosis factor alpha (TNFα) is an early response gene and induces a plethora of genes and signaling pathways. To identify robust signals in genes reliably upregulated by TNFα, we first measured microarray gene expression in vitro and searched methodologically comparable, publicly available data sets to identify concordant signals. Using tag single-nucleotide polymorphisms in the genes common to all data sets, we identified a genetic variant of the TNFAIP2 gene, rs8126, associated with decreased 28-day survival and increased organ dysfunction in an adult cohort in the Vasopressin and Septic Shock Trial. Similar to this cohort, we found that an association with rs8126 and increased organ dysfunction is replicated in a second cohort of septic shock patients in the St. Paul's Hospital Intensive Care Unit. We found that TNFAIP2 inhibits NF-x03BA;B activity, impacting the downstream cytokine interleukin (IL)-8. The minor G allele of TNFAIP2 rs8126 resulted in greater TNFAIP2 expression, decreased IL-8 production and was associated with decreased survival in patients experiencing septic shock. These data suggest that TNFAIP2 is a novel inhibitor of NF-x03BA;B that acts as an autoinhibitor of the TNFα response during septic shock.

A functional synonymous coding variant in the IL1RN gene is associated with survival in septic shock

RATIONALE

Death from infection is a highly heritable trait, yet there are few genetic variants with known mechanism influencing survival during septic shock.

OBJECTIVES

We hypothesized that a synonymous coding variant in the IL-1 receptor antagonist gene (IL1RN), rs315952, previously associated with reduced risk for acute respiratory distress syndrome, would be functional and associate with improved survival in septic shock.

METHODS

We used a human endotoxin (LPS) model of evoked inflammatory stress to measure plasma IL-1 receptor antagonist (IL1RA) following low-dose Food and Drug Administration-grade LPS injection (1 ng/kg) in 294 human volunteers. RNA sequencing of adipose tissue pre- and post-LPS was used to test for allelic imbalance at rs315952. In the Vasopressin and Septic Shock Trial cohort, we performed a genetic association study for survival, mortality, and organ failure-free days.

MEASUREMENTS AND MAIN RESULTS

Adipose tissue displayed significant allelic imbalance favoring the rs315952C allele in subjects of European ancestry. Consistent with this, carriers of rs315952C had slightly higher plasma IL1RA at baseline (0.039) and higher evoked IL1RA post-LPS (0.011). In the Vasopressin and Septic Shock Trial cohort, rs315952C associated with improved survival (P = 0.028), decreased adjusted 90-day mortality (P = 0.044), and faster resolution of shock (P = 0.029).

CONCLUSIONS

In European ancestry subjects, the IL1RN variant rs315952C is preferentially transcribed and associated with increased evoked plasma IL1RA and with improved survival from septic shock. It may be that genetically determined IL1RA levels influence survival from septic shock.

Beyond single-nucleotide polymorphisms: genetics, genomics, and other 'omic approaches to acute respiratory distress syndrome

This article summarizes the contributions of high-throughput genomic, proteomic, metabolomic, and gene expression investigations to the understanding of inherited or acquired risk for acute respiratory distress syndrome (ARDS). Although not yet widely applied to a complex trait like ARDS, these techniques are now routinely used to study a variety of disease states. Omic applications hold great promise for identifying novel factors that may contribute to ARDS pathophysiology or may be appropriate for further development as biomarkers or surrogates in clinical studies. Opportunities and challenges of different techniques are discussed, and examples of successful applications in non-ARDS fields are used to illustrate the potential use of each technique.

A pilot study of angiotensin converting enzyme (ACE) genotype and return of spontaneous circulation following out-of-hospital cardiac arrest

Objective

In the last few years the genetic influence on health and disease outcome has become more apparent. The ACE genotype appears to play a significant role in the pathophysiology of several disease processes. This pilot study aims at showing the feasibility to examine the genetic influence of the ACE genotype on return of spontaneous circulation (ROSC) in out-of-hospital cardiac arrest (OHCA).

Methods

We performed a prospective observational study of all OHCAs of presumed cardiac origin in a well-defined population. We collected prehospital blood samples for the determination of ACE genotype and used this information together with Utstein template parameters in a multivariable analysis to examine the relationship between ROSC and ACE genotype.

Results

We collect blood samples in 156 of 361 patients with OHCA of presumed cardiac origin, 127 samples were analysed (mean age 67 years, 86% male, 79% witnessed OHCA, 80% bystander CPR, 62% had a shockable rhythm, ROSC 77%). Distribution of the ACE gene polymorphisms: insertion polymorphism (II) n=22, 17%, insertion/deletion polymorphism (ID) n=66, 52% and deletion polymorphism (DD) n=39, 31%. We found no significant association between ACE II vs ACE DD/DI and ROSC (OR 1.72; CI 0.52 to 5.73; p=0.38). Other ACE genotype groupings (II/ID vs DD or II vs DD) did not change the overall finding of lack of impact of ACE genotype on ROSC.

Conclusions

This pilot study did not indicate a significant association between ACE gene polymorphism and ROSC. However, it has demonstrated that prehospital genetic studies including blood sampling are feasible and ethically acceptable.

The meta-genome of sepsis: host genetics, pathogens and the acute immune response

Severe infection and the patient response constitute sepsis. Here, we review the meta-genome (patient genetics, pathogen communities and host response) and its impact upon the outcome of severe sepsis. Patient genetics, both predisposition for infection and the subsequent response to infection are reviewed. The pathogen is discussed with particular emphasis upon the modern era of microbiome analysis and nucleic acid diagnostics. Finally, we discuss the host clinical and immune responses and present new data to suggest that the immune response is the key to understanding sepsis and improving a death rate of nearly 30%.

Noncanonical Nuclear Factor Kappa B (NF-κB) Signaling and Potential for Therapeutics in Sepsis

NF-κB signaling plays a central role in the pathophysiology of severe sepsis and septic shock. Despite tremendous and missed efforts, novel therapeutics for severe sepsis and septic shock are still needed. Many drugs have been designed to target the canonical NF-κB signaling pathway with limited success, potentially due to the nonspecificity of the drugs for other kinases and the interaction of canonical signaling with other pathways. Here, we review the canonical and noncanonical signaling pathways of NF-κB, the cross talk and negative regulation of the two pathways, and the potential for therapeutics arising from the noncanonical NF-κB pathway in relation to the pathophysiology of septic shock.

The effect of endogenous angiotensin II on alveolar fluid clearance in rats with acute lung injury

BACKGROUND

In acute lung injury (ALI), angiotensin II (Ang II) plays a vital role in the stimulation of pulmonary permeability edema formation through the angiotensin type 1 (AT1) receptor. The effect of Ang II on alveolar fluid clearance (AFC) in ALI remains unknown.

METHODS

Sprague Dawley rats were anesthetized and intratracheally injected with 1 mg⁄kg lipopolysaccharide (LPS), while control rats received saline. The AT1 receptor antagonist ZD7155 was injected intraperitoneally (10 mg⁄kg) 30 min before LPS administration. The lungs were isolated for AFC measurement, and alpha-epithelial sodium channel (ENaC) messenger RNA and protein expression were detected by reverse-transcription polymerase chain reaction and Western blot.

RESULTS

LPS-induced ALI caused an increase in Ang II levels in plasma and lung tissue but a decrease in AFC. The time course of Ang II levels paralleled that of AFC. Pretreatment with ZD7155 prevented ALI-induced reduction of AFC. ZD7155 also reversed the ALI-induced reduction of beta-ENaC and gamma-ENaC levels, and further decreased alpha-ENaC levels.

CONCLUSIONS

These findings suggest that endogenous Ang II inhibits AFC and dysregulates ENaC expression via AT1 receptors, which contribute to alveolar filling and pulmonary edema in LPS-induced ALI.

Genetic susceptibility to non-necrotizing erysipelas/cellulitis

BACKGROUND

Bacterial non-necrotizing erysipelas and cellulitis are often recurring, diffusely spreading infections of the skin and subcutaneous tissues caused most commonly by streptococci. Host genetic factors influence infection susceptibility but no extensive studies on the genetic determinants of human erysipelas exist.

METHODS

We performed genome-wide linkage with the 10,000 variant Human Mapping Array (HMA10K) array on 52 Finnish families with multiple erysipelas cases followed by microsatellite fine mapping of suggestive linkage peaks. A scan with the HMA250K array was subsequently performed with a subset of cases and controls.

RESULTS

Significant linkage was found at 9q34 (nonparametric multipoint linkage score (NPL(all)) 3.84, p=0.026), which is syntenic to a quantitative trait locus for susceptibility to group A streptococci infections on chromosome 2 in mouse. Sequencing of candidate genes in the 9q34 region did not conclusively associate any to erysipelas/cellulitis susceptibility. Suggestive linkage (NPL(all)>3.0) was found at three loci: 3q22-24, 21q22, and 22q13. A subsequent denser genome scan with the HMA250K array supported the 3q22 locus, in which several SNPs in the promoter of AGTR1 (Angiotensin II receptor type I) suggestively associated with erysipelas/cellulitis susceptibility.

CONCLUSIONS

Specific host genetic factors may cause erysipelas/cellulitis susceptibility in humans.

Phosphatidylinositol transfer protein, cytoplasmic 1 (PITPNC1) binds and transfers phosphatidic acid

Phosphatidylinositol transfer proteins (PITPs) are versatile proteins required for signal transduction and membrane traffic. The best characterized mammalian PITPs are the Class I PITPs, PITPα (PITPNA) and PITPβ (PITPNB), which are single domain proteins with a hydrophobic cavity that binds a phosphatidylinositol (PI) or phosphatidylcholine molecule. In this study, we report the lipid binding properties of an uncharacterized soluble PITP, phosphatidylinositol transfer protein, cytoplasmic 1 (PITPNC1) (alternative name, RdgBβ), of the Class II family. We show that the lipid binding properties of this protein are distinct to Class I PITPs because, besides PI, RdgBβ binds and transfers phosphatidic acid (PA) but hardly binds phosphatidylcholine. RdgBβ when purified from Escherichia coli is preloaded with PA and phosphatidylglycerol. When RdgBβ was incubated with permeabilized HL60 cells, phosphatidylglycerol was released, and PA and PI were now incorporated into RdgBβ. After an increase in PA levels following activation of endogenous phospholipase D or after addition of bacterial phospholipase D, binding of PA to RdgBβ was greater at the expense of PI binding. We propose that RdgBβ, when containing PA, regulates an effector protein or can facilitate lipid transfer between membrane compartments.

Regulation of alveolar fluid clearance and ENaC expression in lung by exogenous angiotensin II

Angiotensin II (Ang II) has been demonstrated as a pro-inflammatory effect in acute lung injury, but studies of the effect of Ang II on the formation of pulmonary edema and alveolar filling remains unclear. Therefore, in this study the regulation of alveolar fluid clearance (AFC) and the expression of epithelial sodium channel (ENaC) by exogenous Ang II was verified. SD rats were anesthetized and were given Ang II with increasing doses (1, 10 and 100 μg/kg per min) via osmotic minipumps, whereas control rats received only saline vehicle. AT1 receptor antagonist ZD7155 (10 mg/kg) and inhibitor of cAMP degeneration rolipram (1 mg/kg) were injected intraperitoneally 30 min before administration of Ang II. The lungs were isolated for measurement of alveolar fluid clearance. The mRNA and protein expression of ENaC were detected by RT-PCR and Western blot. Exposure to higher doses of Ang II reduced AFC in a dose-dependent manner and resulted in a non-coordinate regulation of α-ENaC vs. the regulation of β- and γ-ENaC, however Ang II type 1 (AT1) receptor antagonist ZD7155 prevented the Ang II-induced inhibition of fluid clearance and dysregulation of ENaC expression. In addition, exposure to inhibitor of cAMP degradation rolipram blunted the Ang II-induced inhibition of fluid clearance. These results indicate that through activation of AT(1) receptor, exogenous Ang II promotes pulmonary edema and alveolar filling by inhibition of alveolar fluid clearance via downregulation of cAMP level and dysregulation of ENaC expression.