Understanding clinical and biological heterogeneity to advance precision medicine in paediatric acute respiratory distress syndrome

Paediatric acute respiratory distress syndrome (PARDS) is a heterogeneous clinical syndrome that is associated with high rates of mortality and long-term morbidity. Factors that distinguish PARDS from adult acute respiratory distress syndrome (ARDS) include changes in developmental stage and lung maturation with age, precipitating factors, and comorbidities. No specific treatment is available for PARDS and management is largely supportive, but methods to identify patients who would benefit from specific ventilation strategies or ancillary treatments, such as prone positioning, are needed. Understanding of the clinical and biological heterogeneity of PARDS, and of differences in clinical features and clinical course, pathobiology, response to treatment, and outcomes between PARDS and adult ARDS, will be key to the development of novel preventive and therapeutic strategies and a precision medicine approach to care. Studies in which clinical, biomarker, and transcriptomic data, as well as informatics, are used to unpack the biological and phenotypic heterogeneity of PARDS, and implementation of methods to better identify patients with PARDS, including methods to rapidly identify subphenotypes and endotypes at the point of care, will drive progress on the path to precision medicine.</p

Prospective clinical testing and experimental validation of the Pediatric Sepsis Biomarker Risk Model

Sepsis remains a major public health problem with no major therapeutic advances over the last several decades. The clinical and biological heterogeneity of sepsis have limited success of potential new therapies. Accordingly, there is considerable interest in developing a precision medicine approach to inform more rational development, testing, and targeting of new therapies. We previously developed the Pediatric Sepsis Biomarker Risk Model (PERSEVERE) to estimate mortality risk and proposed its use as a prognostic enrichment tool in sepsis clinical trials; prognostic enrichment selects patients based on mortality risk independent of treatment. Here, we show that PERSEVERE has excellent performance in a diverse cohort of children with septic shock with potential for use as a predictive enrichment strategy; predictive enrichment selects patients based on likely response to treatment. We demonstrate that the PERSEVERE biomarkers are reliably associated with mortality in mice challenged with experimental sepsis, thus providing an opportunity to test precision medicine strategies in the preclinical setting. Using this model, we tested two clinically feasible therapeutic strategies, guided by the PERSEVERE-based enrichment, and found that mice identified as high risk for mortality had a greater bacterial burden and could be rescued by higher doses of antibiotics. The association between higher pathogen burden and higher mortality risk was corroborated among critically ill children with septic shock. This bedside to bench to bedside approach provides proof of principle for PERSEVERE-guided application of precision medicine in sepsis

Executive Summary of the Second International Guidelines for the Diagnosis and Management of Pediatric Acute Respiratory Distress Syndrome (PALICC-2)

OBJECTIVES: We sought to update our 2015 work in the Second Pediatric Acute Lung Injury Consensus Conference (PALICC-2) guidelines for the diagnosis and management of pediatric acute respiratory distress syndrome (PARDS), considering new evidence and topic areas that were not previously addressed. DESIGN: International consensus conference series involving 52 multidisciplinary international content experts in PARDS and four methodology experts from 15 countries, using consensus conference methodology, and implementation science. SETTING: Not applicable. PATIENTS: Patients with or at risk for PARDS. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Eleven subgroups conducted systematic or scoping reviews addressing 11 topic areas: 1) definition, incidence, and epidemiology; 2) pathobiology, severity, and risk stratification; 3) ventilatory support; 4) pulmonary-specific ancillary treatment; 5) nonpulmonary treatment; 6) monitoring; 7) noninvasive respiratory support; 8) extracorporeal support; 9) morbidity and long-term outcomes; 10) clinical informatics and data science; and 11) resource-limited settings. The search included MEDLINE, EMBASE, and CINAHL Complete (EBSCOhost) and was updated in March 2022. Grading of Recommendations, Assessment, Development, and Evaluation methodology was used to summarize evidence and develop the recommendations, which were discussed and voted on by all PALICC-2 experts. There were 146 recommendations and statements, including: 34 recommendations for clinical practice; 112 consensus-based statements with 18 on PARDS definition, 55 on good practice, seven on policy, and 32 on research. All recommendations and statements had agreement greater than 80%. CONCLUSIONS: PALICC-2 recommendations and consensus-based statements should facilitate the implementation and adherence to the best clinical practice in patients with PARDS. These results will also inform the development of future programs of research that are crucially needed to provide stronger evidence to guide the pediatric critical care teams managing these patients.</p

Differential expression of the Nrf2-linked genes in pediatric septic shock.

INTRODUCTION: Experimental data from animal models of sepsis support a role for a transcription factor, nuclear erythroid-related factor 2 p45-related factor 2 (Nrf2), as a master regulator of antioxidant and detoxifying genes and intermediary metabolism during stress. Prior analysis of a pediatric septic shock transcriptomic database showed that the Nrf2 response is a top 5 upregulated signaling pathway in early pediatric septic shock. METHODS: We conducted a focused analysis of 267 Nrf2-linked genes using a multicenter, genome-wide expression database of 180 children with septic shock 10 years of age or younger and 53 healthy controls. The analysis involved RNA isolated from whole blood within 24 h of pediatric intensive care unit admission for septic shock and a false discovery rate of 5 %. We compared differentially expressed genes from (1) patients with septic shock and healthy controls and (2) across validated gene expression-based subclasses of pediatric septic shock (endotypes A and B) using several bioinformatic methods. RESULTS: We found upregulation of 123 Nrf2-linked genes in children with septic shock. The top gene network represented by these genes contained primarily enzymes with oxidoreductase activity involved in cellular lipid metabolism that were highly connected to the peroxisome proliferator activated receptor and the retinoic acid receptor families. Endotype A, which had higher organ failure burden and mortality, exhibited a greater downregulation of Nrf2-linked genes than endotype B, with 92 genes differentially regulated between endotypes. CONCLUSIONS: Our findings indicate that Nrf2-linked genes may contribute to alterations in oxidative signaling and intermediary metabolism in pediatric septic shock

Targeting Tat Inhibitors in the Assembly of Human Immunodeficiency Virus Type 1 Transcription Complexes▿ †

Human immunodeficiency virus type 1 (HIV-1) transcription is regulated by the viral Tat protein, which relieves a block to elongation by recruiting an elongation factor, P-TEFb, to the viral promoter. Here, we report the discovery of potent Tat inhibitors that utilize a localization signal to target a dominant negative protein to its site of action. Fusing the Tat activation domain to some splicing factors, particularly to the Arg-Ser (RS) domain of U2AF65, creates Tat inhibitors that localize to subnuclear speckles, sites where pre-mRNA processing factors are stored for assembly into transcription complexes. A U2AF65 fusion named T-RS interacts with the nonphosphorylated C-terminal domain of RNA polymerase II (RNAP II) via its RS domain and is loaded into RNAP II holoenzyme complexes. T-RS is recruited efficiently to the HIV-1 promoter in a TAR-independent manner before RNAP II hyperphosphorylation but not to cellular promoters. The “preloading” of T-RS into HIV-1 preinitiation complexes prevents the entry of active Tat molecules, leaving the complexes in an elongation-incompetent state and effectively suppressing HIV-1 replication. The ability to deliver inhibitors to transcription complexes through the use of targeting/localization signals may provide new avenues for designing viral and transcription inhibitors

Hexosylceramides and Glycerophosphatidylcholine GPC(36:1) Increase in Multi-Organ Dysfunction Syndrome Patients with Pediatric Intensive Care Unit Admission over 8-Day Hospitalization

Glycero- and sphingo-lipids are important in plasma membrane structure, caloric storage and signaling. An un-targeted lipidomics approach for a cohort of critically ill pediatric intensive care unit (PICU) patients undergoing multi-organ dysfunction syndrome (MODS) was compared to sedation controls. After IRB approval, patients meeting the criteria for MODS were screened, consented (n = 24), and blood samples were collected from the PICU at HDVCH, Michigan; eight patients needed veno-arterial extracorporeal membrane oxygenation (VA ECMO). Sedation controls were presenting for routine sedation (n = 4). Plasma lipid profiles were determined by nano-electrospray (nESI) direct infusion high resolution/accurate mass spectrometry (MS) and tandem mass spectrometry (MS/MS). Biostatistics analysis was performed using R v 3.6.0. Sixty-one patient samples over three time points revealed a ceramide metabolite, hexosylceramide (Hex-Cer) was high across all time points (mean 1.63–3.19%; vs. controls 0.22%). Fourteen species statistically differentiated from sedation controls (p-value ≤ 0.05); sphingomyelin (SM) [SM(d18:1/23:0), SM(d18:1/22:0), SM(d18:1/23:1), SM(d18:1/21:0), SM(d18:1/24:0)]; and glycerophosphotidylcholine (GPC) [GPC(36:01), GPC(18:00), GPC(O:34:02), GPC(18:02), GPC(38:05), GPC(O:34:03), GPC(16:00), GPC(40:05), GPC(O:36:03)]. Hex-Cer has been shown to be involved in viral infection and may be at play during acute illness. GPC(36:01) was elevated in all MODS patients at all time points and is associated with inflammation and brain injury

Risk Factors Leading to Failed Procedural Sedation in Children Outside the Operating Room

Objectives: Deep sedation enables effective performance of imaging or procedures in children, but failed sedation still occurs. We desired to determine the factors that were associated with failed sedation in children receiving deep sedation by a dedicated nonanesthesia sedation service and hypothesized that the presence of an upper respiratory infection (URI) and/ or other risk factors would increase the probability of failing sedation. Results: Seven of the 13 predictors were significantly associated with failed sedation; these are as follows: (1) URI (P = 0.008); (2) congenital heart disease (P = 0.021); (3) obstructive sleep apnea (OSA)/snoring (P G 0.001); (4) the American Society of Anesthesiologists (ASA) class of above II (P G 0.001); (5) obesity (P G 0.001); (6) increased weight (P G 0.001); and (7) older age (P G 0.001). Sex, prematurity, asthma, gastroesophageal reflux, and cerebral palsy/developmental delay were not associated with failure. Pulmonary hypertension was not able to be assessed because only 1 patient with pulmonary hypertension was sedated. A forward stepwise regression identified 5 variables that could be considered useful predictors of failed sedation, which are as follows: Key Words: procedural sedation, upper respiratory tract infection, obstructive sleep apnea, snoring, failed sedation, risk factors, obesity (Pediatr Emer Care 2014;30: 381Y387) T he use of procedural sedation and sedation services has become the standard of care to enable effective completion of many pediatric imaging studies and procedures. Through the use of anesthetics such as propofol, the inability to complete a study due to adverse respiratory events or other complications of sedation, defined as a failed sedation, is uncommon. 1 Specifically, a failed sedation results in wasted time for parents, patients, and the sedation service, potential exposure of patients to adverse events, and increased costs. Improved prediction of patients who are likely to fail sedation could potentially increase the safety and efficiency of pediatric procedural sedation provided outside the operating room. A paucity of data exists on risk factors associated with failed pediatric procedural sedation, and little in the literature addresses the role of a recent or current upper respiratory infection (URI) that plays in a failed sedation. Most of the studies report on risk factors associated with respiratory complications of children undergoing general anesthesia in an operating room. 2Y7 These studies have shown conflicting results with regard to whether a URI is associated with adverse respiratory events such as laryngospasm, bronchospasm, oxygen desaturation, and upper airway obstruction. Most studies, however, conclude that a URI, use of an endotracheal tube, a history of snoring, and passive smoking contribute to respiratory complications during general anesthesia. A single study included pediatric procedural sedation data. However, it is not comparable with the typical outpatient sedation population because of the differences in anesthetic use. METHODS Study Population We conducted a retrospective chart review, approved by the institutional review board, of patients requiring sedation for magnetic resonance imaging (MRI), computed tomographic (CT), nuclear medicine scans, and brief procedures (including auditory brainstem response [ABR] tests, lumbar punctures, peripherally inserted central catheter [PICC] line placements, and renal biopsies) at Children&apos;s Healthcare of Atlanta at Egleston and at a freestanding radiology facility managed by Children&apos;s at Eggleston. Children&apos;s Healthcare of Atlanta at Egleston is a quaternary care, free-standing children&apos;s hospital in Atlanta, Ga, that provides inpatient and outpatient procedural sedation to approximately 3500 pediatric patients per year. Sedation services are provided by sedation physicians trained in pediatric intensive care, pediatric emergency medicine, or anesthesiology. Almost all patients in the service receive intravenous propofol by bolus dose for induction and maintenance with propofol infusion for the duration of the imaging study or procedure. Sedation service records were reviewed from January 2007 to December 2011 to identify all patients who received sedation. If the imaging or procedure was not completed because of adverse events or complications, this was defined as a failed sedation. For comparison, a convenience sample of all patients successfully receiving sedation during January to February 2009 was obtained. Successful sedation was defined as completion of imaging or procedure in a sedated patient without requirement for rescheduling or general anesthesia. This large sample was identified to allow statistically relevant comparison with the total failed sedation group. The period during winter months was also selected to increase the likelihood of patients with URIs or respiratory symptoms within the group of successful sedations. Patients were included in this study from the ages of birth to 21 years. Characteristics of patients compiled included age, sex, weight, American Society of Anesthesiologists (ASA) class, and history of prematurity. Presence of asthma, current URI, gastroesophageal reflux (GER), cerebral palsy/developmental delay (CP/DD), obstructive sleep apnea (OSA)/snoring, congenital heart disease, or pulmonary hypertension (PHTN) were obtained from a standardized presedation history and physical evaluation form. Heights were not obtained on any of the patients and thus did not allow for the calculation of a body mass index as an objective measure of obesity. Obesity was defined as a weight greater than the 95th percentile for sex and age based on the Centers for Disease Control and Prevention growth curves. 9 Procedure start and end times, type of procedure or imaging study, medications administered, complications experienced, and interventions performed during sedation were all obtained from a standard anesthesia record that was scanned into an electronic medical record. Patients who had an ASA class IV status were excluded from review because of the severity of illness. The complications listed in Sample Size and Power We conservatively estimated that 0.6% of all sedations are unable to be completed. Given approximately 3500 sedations per year, during the period of 4 years, we estimated that approximately 84 failed sedations could be identified from our retrospective chart review. In addition, we estimated that approximately 25% of children undergoing sedation have symptoms of a URI. Power was calculated using a 2-sided z test with pooled variance and significance level of 0.05. In addition, the test assumes that the proportion of cases with URI is 0.25 under the null hypothesis and 0.40 under the alternative hypothesis. Based on the previously mentioned assumptions, group sample sizes of 84 cases and 528 controls achieve 80% power to detect an odds ratio (OR) of 2.0. Sedation Protocol The Children&apos;s Sedation Service follows protocols and procedures in accordance with the American Academy of Pediatrics Guidelines for Sedation. 10Y12 The final choice of sedation medication for each patient is at the discretion of the sedation service physician; however, most physicians used propofol. The sedation protocols and practice patterns of physicians in the Children&apos;s Sedation Service at Egleston have been published. 10 For MRIs, end-tidal carbon dioxide monitoring using a nasal prong apparatus was routinely used, but these values and trends were not tracked in this study. If sedation was inadequate, additional propofol boluses were given to achieve the desired level of sedation and the maintenance infusion dosage was increased at the discretion of the sedation physician. Once the procedure was completed, the infusion was discontinued, and the patients were monitored until complete recovery criteria were met using the Aldrete score. 14 Statistical Analysis Patients with an ASA class I and II physical status were grouped together for the purposes of data analysis. The goal of analysis was to determine patient characteristics and comorbidities associated with increased odds of failed sedation. To accomplish this, univariate analysis of each potential risk factor was performed to determine if there was an association between the covariate and the outcome failed sedation. This was accomplished by performing W 2 tests of association for categorical variables and 2-sample t tests for continuous variables. Based on the results from the univariate analysis, a set of potential predictors was identified that were significantly associated with failed sedation and could be further analyzed for possible interactions with one another using multivariate logistic regression models. A forward-stepwise logistic regression technique was used to determine a subset of variables that were associated with increased odds of failed sedation. A significance level of 0.2 was required to allow the variable to enter the model, and a significance level of 0.1 was required for the variable to stay in the model. Two and three-way interactions were added to the model but were removed if not statistically significant. The Hosmer and Lemeshow goodness-of-fit test was used to assess the fit of the final model. RESULTS Summary of Sample Eighty-three failed procedural sedations were identified between January 2007 and December 2011. Five hundred twentythree patients with successful sedations were identified in the comparison group. Summary of Failed Sedation

Bioenergetic Crisis in ICU-Acquired Weakness Gene Signatures Was Associated With Sepsis-Related Mortality: A Brief Report

OBJECTIVES:. To investigate the relationship between ICU-acquired weakness (ICUAW) signatures and sepsis-related mortality using gene expression from the blood within 24 hours of sepsis onset. DESIGN:. Observational study using differential gene expression analysis. SETTING:. Publicly available gene expression profile GSE54514, single-center medical and surgical ICU. PATIENTS:. Patients with primary bacteremia- and respiratory-triggered sepsis including 8 nonsurvivors and 13 survivors who were 18 years old and older and admitted to ICU. MEASUREMENTS AND MAIN RESULTS:. Among validated 526 ICUAW gene signatures, differential gene expression analysis controlling for age identified 38 significantly expressed genes between nonsurvivors and survivors. Functional enrichment analysis of differentially expressed ICUAW genes identified impaired cadherin binding, sarcomere formation, and energy metabolism among nonsurvivors. CONCLUSIONS:. Our findings demonstrated a biological association between sepsis-related mortality and ICUAW signatures in the early phase of sepsis. Defects in energy metabolism and muscle fiber formation were associated with sepsis-related mortality

Comparison of Glutathione, Cysteine, and their Redox Potentials in the Plasma of Critically Ill and Healthy Children

Background: Oxidative stress (OS) is known to play a role in critical illness due to an imbalance in reactive oxygen species (ROS) and reactive nitrogen species (RNS) and the body’s ability to detoxify pro-oxidants using small molecule anti-oxidants and anti-oxidant enzymes.Objective: To compare the concentrations of plasma redox metabolites and redox potentials for the Cys/CySS and GSH/GSSG thiol/disulfide pairs in critically ill children with healthy control children.Methods: We performed a prospective clinical observational study of children ages ≤ 18 years and weight ≥ 6 kg who were hospitalized between January 2010 and April 2012 in a 30 bed multidisciplinary medical-surgical pediatric intensive care unit (PICU). We measured the plasma concentrations of Cys, CySS, GSH, and GSSG within the first 24 hours of PICU arrival, and we calculated the redox potential for the Cys/CySS (Eh Cys/CySS) and GSH/GSSG (Eh GSH/GSSG) thiol/disulfide pairs in the plasma of 61 critically ill children and 16 healthy control children.Results: Critically ill children have less Cys (p = 0.009), less CySS (p = 0.011), less Total Cys ([Cys] + 2[CySS], p = 0.01), more GSSG (p < 0.001), and more oxidized Eh GSH/GSSG (p < 0.001) compared to healthy children.Conclusions: Our results demonstrate that in the presence of pediatric critical illness, the Total Cys/CySS thiol pool decreases while GSH is likely one component of the cellular redox system that reduces CySS back to Cys thus maintaining Eh Cys/CySS. The Total Cys pool is more abundant than the Total GSH pool in the plasma of children. Further investigation is needed to elucidate the differences in redox potentials in subgroups of critically ill children, and to determine whether differences in redox metabolite concentrations and redox potentials correlate with severity of critical illness and clinical outcomes