Frequency of HLA-DR+CD38hi T cells identifies and quantifies T-cell activation in hemophagocytic lymphohistiocytosis, hyperinflammation, and immune regulatory disorders.

BACKGROUND: Quantifying T-cell activation is essential for the diagnosis and evaluation of treatment response in various hyperinflammatory and immune regulatory disorders, including hemophagocytic lymphohistiocytosis. Plasma soluble IL-2 receptor (sIL-2R) is a well-established biomarker for evaluating systemic T-cell activation. However, the limited availability of sIL-2R testing could result in delayed diagnosis. Furthermore, high sIL-2R levels may not always reflect T-cell activation. OBJECTIVES: To address these limitations, this study investigated whether cell surface markers of T-cell activation, HLA-DR, and CD38, as assessed by flow cytometry, could be used to quantify systemic T-cell activation in a variety of inflammatory disease states and examine its correlation with sIL-2R levels. METHODS: Results for sIL-2R, CXCL9, and ferritin assays were obtained from patient's medical records. Frequency of HLA-DR+CD38high(hi) T-cells was assessed in different T-cell subsets using flow cytometry. RESULTS: In this study's cohort, activation in total CD8+ T (r = 0.65; P < .0001) and CD4+ (r = 0.42; P < .0001) T-cell subsets significantly correlated with plasma sIL-2R levels. At the disease onset, the frequency of HLA-DR+CD38hi T cells in CD8+ T (r = 0.65, P < .0001) and CD4+ T (r = 0.77; P < .0001) effector memory (TEM) compartments correlated strongly with sIL-2R levels. Evaluation of T-cell activation markers in follow-up samples also revealed a positive correlation for both CD4+ TEM and CD8+ TEM activation with sIL-2R levels; thus, attesting its utility in initial diagnosis and in evaluating treatment response. The frequency of HLA-DR+CD38hi T-cells in the CD8+ TEM compartment also correlated with plasma CXCL9 (r = 0.42; P = .0120) and ferritin levels (r = 0.32; P = .0037). CONCLUSIONS: This study demonstrates that flow cytometry-based direct T-cell activation assessed by HLA-DR+CD38hi T cells accurately quantifies T-cell activation and strongly correlates with sIL-2R levels across a spectrum of hyperinflammatory and immune dysregulation disorders.

Development and Validation of a Model for Endotracheal Intubation and Mechanical Ventilation Prediction in PICU Patients.

OBJECTIVES: To develop and externally validate an intubation prediction model for children admitted to a PICU using objective and routinely available data from the electronic medical records (EMRs). DESIGN: Retrospective observational cohort study. SETTING: Two PICUs within the same healthcare system: an academic, quaternary care center (36 beds) and a community, tertiary care center (56 beds). PATIENTS: Children younger than 18 years old admitted to a PICU between 2010 and 2022. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Clinical data was extracted from the EMR. PICU stays with at least one mechanical ventilation event (≥ 24 hr) occurring within a window of 1-7 days after hospital admission were included in the study. Of 13,208 PICU stays in the derivation PICU cohort, 1,175 (8.90%) had an intubation event. In the validation cohort, there were 1,165 of 17,841 stays (6.53%) with an intubation event. We trained a Categorical Boosting (CatBoost) model using vital signs, laboratory tests, demographic data, medications, organ dysfunction scores, and other patient characteristics to predict the need of intubation and mechanical ventilation using a 24-hour window of data within their hospital stay. We compared the CatBoost model to an extreme gradient boost, random forest, and a logistic regression model. The area under the receiving operating characteristic curve for the derivation cohort and the validation cohort was 0.88 (95% CI, 0.88-0.89) and 0.92 (95% CI, 0.91-0.92), respectively. CONCLUSIONS: We developed and externally validated an interpretable machine learning prediction model that improves on conventional clinical criteria to predict the need for intubation in children hospitalized in a PICU using information readily available in the EMR. Implementation of our model may help clinicians optimize the timing of endotracheal intubation and better allocate respiratory and nursing staff to care for mechanically ventilated children.

Functional immunophenotyping of blood neutrophils identifies novel endotypes of viral response in preschool children with recurrent wheezing.

BACKGROUND: Preschool children with recurrent wheezing are heterogeneous, with differing responses to respiratory viral infections. Although neutrophils are crucial for host defense, their function has not been studied in this population. OBJECTIVE: We performed functional immunophenotyping on isolated blood neutrophils from 52 preschool children with recurrent wheezing (aeroallergen sensitization, n = 16; no sensitization, n = 36). METHODS: Blood neutrophils were purified and cultured overnight with polyinosinic:polycytidylic acid [poly(I:C)] as a viral analog stimulus. Neutrophils underwent next-generation sequencing with Reactome pathway analysis and were analyzed for cytokine secretion, apoptosis, myeloperoxidase, and extracellular DNA release. CD14+ monocytes were also exposed to neutrophil culture supernatant and analyzed for markers of M1 and M2 activation. RESULTS: A total of 495 genes, related largely to the innate immune system and neutrophil degranulation, were differently expressed in children with versus without aeroallergen sensitization. Functional experiments identified more neutrophil degranulation and extracellular trap formation (ie, more myeloperoxidase and extracellular DNA) and less neutrophil proinflammatory cytokine secretion in children with aeroallergen sensitization. Neutrophils also shifted CD14+ monocytes to a more anti-inflammatory (ie, M2) phenotype in sensitized children and a more proinflammatory (ie, M1) phenotype in nonsensitized children. Although both groups experienced viral exacerbations, annualized exacerbation rates prompting unscheduled health care were also higher in children without aeroallergen sensitization after enrollment. CONCLUSIONS: Systemic neutrophil responses to viral infection differ by allergic phenotype and may be less effective in preschool children without allergic inflammation. Further studies of neutrophil function are needed in this population, which often has less favorable therapeutic responses to inhaled corticosteroids and other therapies directed at type 2-high inflammation.

Social determinants of health influence preschool and caregiver experiences during symptoms and exacerbations of wheezing.

BACKGROUND: Social determinants of health have been inadequately studied in preschool children with wheezing and their caregivers but may influence the care received. OBJECTIVE: To evaluate the symptom and exacerbation experiences of wheezing preschool children and their caregivers, stratified by risk of social vulnerability, over 1 year of longitudinal follow-up. METHODS: A total of 79 caregivers and their preschool children with recurrent wheezing and at least 1 exacerbation in the previous year were stratified by a composite measure of social vulnerability into "low" (N = 19), "intermediate" (N = 27), and "high" (N = 33) risk groups. Outcome measures at the follow-up visits included child respiratory symptom scores, asthma control, caregiver-reported outcome measures of mental and social health, exacerbations, and health care utilization. The severity of exacerbations reflected by symptom scores and albuterol use and exacerbation-related caregiver quality of life were also assessed. RESULTS: Preschool children at high risk of social vulnerability had greater day-to-day symptom severity and more severe symptoms during acute exacerbations. High-risk caregivers were also distinguished by lower general life satisfaction at all visits and lower global and emotional quality of life during acute exacerbations which did not improve with exacerbation resolution. Rates of exacerbation or emergency department visits did not differ, but intermediate- and high-risk families were significantly less likely to seek unscheduled outpatient care. CONCLUSION: Social determinants of health influence wheezing outcomes in preschool children and their caregivers. These findings argue for routine assessment of social determinants of health during medical encounters and tailored interventions in high-risk families to promote health equity and improve respiratory outcomes.

Prognostic and predictive value of endothelial dysfunction biomarkers in sepsis-associated acute kidney injury: risk-stratified analysis from a prospective observational cohort of pediatric septic shock.

BACKGROUND: Sepsis-associated acute kidney injury (SA-AKI) is associated with high morbidity, with no current therapies available beyond continuous renal replacement therapy (CRRT). Systemic inflammation and endothelial dysfunction are key drivers of SA-AKI. We sought to measure differences between endothelial dysfunction markers among children with and without SA-AKI, test whether this association varied across inflammatory biomarker-based risk strata, and develop prediction models to identify those at highest risk of SA-AKI. METHODS: Secondary analyses of prospective observational cohort of pediatric septic shock. Primary outcome of interest was the presence of ≥ Stage II KDIGO SA-AKI on day 3 based on serum creatinine (D3 SA-AKI SCr). Biomarkers including those prospectively validated to predict pediatric sepsis mortality (PERSEVERE-II) were measured in Day 1 (D1) serum. Multivariable regression was used to test the independent association between endothelial markers and D3 SA-AKI SCr. We conducted risk-stratified analyses and developed prediction models using Classification and Regression Tree (CART), to estimate risk of D3 SA-AKI among prespecified subgroups based on PERSEVERE-II risk. RESULTS: A total of 414 patients were included in the derivation cohort. Patients with D3 SA-AKI SCr had worse clinical outcomes including 28-day mortality and need for CRRT. Serum soluble thrombomodulin (sTM), Angiopoietin-2 (Angpt-2), and Tie-2 were independently associated with D3 SA-AKI SCr. Further, Tie-2 and Angpt-2/Tie-2 ratios were influenced by the interaction between D3 SA-AKI SCr and risk strata. Logistic regression demonstrated models predictive of D3 SA-AKI risk performed optimally among patients with high- or intermediate-PERSEVERE-II risk strata. A 6 terminal node CART model restricted to this subgroup of patients had an area under the receiver operating characteristic curve (AUROC) 0.90 and 0.77 upon tenfold cross-validation in the derivation cohort to distinguish those with and without D3 SA-AKI SCr and high specificity. The newly derived model performed modestly in a unique set of patients (n = 224), 84 of whom were deemed high- or intermediate-PERSEVERE-II risk, to distinguish those patients with high versus low risk of D3 SA-AKI SCr. CONCLUSIONS: Endothelial dysfunction biomarkers are independently associated with risk of severe SA-AKI. Pending validation, incorporation of endothelial biomarkers may facilitate prognostic and predictive enrichment for selection of therapeutics in future clinical trials among critically ill children.

Detrimental effects of PCSK9 loss-of-function in the pediatric host response to sepsis are mediated through independent influence on Angiopoietin-1.

BACKGROUND: Sepsis is associated with significant mortality. Yet, there are no efficacious therapies beyond antibiotics. PCSK9 loss-of-function (LOF) and inhibition, through enhanced low-density lipoprotein receptor (LDLR) mediated endotoxin clearance, holds promise as a potential therapeutic approach among adults. In contrast, we have previously demonstrated higher mortality in the juvenile host. Given the potential pleiotropic effects of PCSK9 on the endothelium, beyond canonical effects on serum lipoproteins, both of which may influence sepsis outcomes, we sought to test the influence of PCSK9 LOF genotype on endothelial dysfunction. METHODS: Secondary analyses of a prospective observational cohort of pediatric septic shock. Genetic variants of PCSK9 and LDLR genes, serum PCSK9, and lipoprotein concentrations were determined previously. Endothelial dysfunction markers were measured in day 1 serum. We conducted multivariable linear regression to test the influence of PCSK9 LOF genotype on endothelial markers, adjusted for age, complicated course, and low- and high-density lipoproteins (LDL and HDL). Causal mediation analyses to test impact of select endothelial markers on the association between PCSK9 LOF genotype and mortality. Juvenile Pcsk9 null and wildtype mice were subject to cecal slurry sepsis and endothelial markers were quantified. RESULTS: A total of 474 patients were included. PCSK9 LOF was associated with several markers of endothelial dysfunction, with strengthening of associations after exclusion of those homozygous for the rs688 LDLR variant that renders it insensitive to PCSK9. Serum PCSK9 was not correlated with endothelial dysfunction. PCSK9 LOF influenced concentrations of Angiopoietin-1 (Angpt-1) upon adjusting for potential confounders including lipoprotein concentrations, with false discovery adjusted p value of 0.042 and 0.013 for models that included LDL and HDL, respectively. Causal mediation analysis demonstrated that the effect of PCSK9 LOF on mortality was mediated by Angpt-1 (p = 0.0008). Murine data corroborated these results with lower Angpt-1 and higher soluble thrombomodulin among knockout mice with sepsis relative to the wildtype. CONCLUSIONS: We present genetic and biomarker association data that suggest a potential direct role of the PCSK9-LDLR pathway on Angpt-1 in the developing host with septic shock and warrant external validation. Further, mechanistic studies on the role of PCSK9-LDLR pathway on vascular homeostasis may lead to the development of pediatric-specific sepsis therapies.

Outcomes of children with life-threatening status asthmaticus requiring isoflurane therapy and extracorporeal life support.

BACKGROUND: Severe, refractory asthma is a life-threatening emergency that may be treated with isoflurane and extracorporeal life support. The objective of this study was to describe the clinical response to isoflurane and outcomes after discharge of children who received isoflurane and/or extracorporeal life-support for near-fatal asthma. METHODS: This was a retrospective descriptive study using electronic medical record data from two pediatric intensive care units within a single healthcare system in Atlanta, GA. RESULTS: Forty-five children received isoflurane, and 14 children received extracorporeal life support, 9 without a trial of isoflurane. Hypercarbia and acidosis improved within four hours of starting isoflurane. Four children died during the index admission for asthma. Twenty-seven percent had a change in Functional Status Score of three or more points from baseline to PICU discharge. Patients had median percent predicted FEV1 and FEV1/FVC ratios pre- and post-bronchodilator values below normal pediatric values. CONCLUSION: Children who received isoflurane and/or ECLS had a high frequency of previous PICU admission and intubation. Improvement in ventilation and acidosis occurred within the first four hours of starting isoflurane. Children who required isoflurane or ECLS may develop long-lasting deficits in their functional status. Children with near-fatal asthma are a high-risk group and require improved follow-up in the year following PICU discharge.

Pathobiology, Severity, and Risk Stratification of Pediatric Acute Respiratory Distress Syndrome: From the Second Pediatric Acute Lung Injury Consensus Conference.

OBJECTIVES: To review the literature for studies published in children on the pathobiology, severity, and risk stratification of pediatric acute respiratory distress syndrome (PARDS) with the intent of guiding current medical practice and identifying important areas for future research related to severity and risk stratification. DATA SOURCES: Electronic searches of PubMed and Embase were conducted from 2013 to March 2022 by using a combination of medical subject heading terms and text words to capture the pathobiology, severity, and comorbidities of PARDS. STUDY SELECTION: We included studies of critically ill patients with PARDS that related to the severity and risk stratification of PARDS using characteristics other than the oxygenation defect. Studies using animal models, adult only, and studies with 10 or fewer children were excluded from our review. DATA EXTRACTION: Title/abstract review, full-text review, and data extraction using a standardized data collection form. DATA SYNTHESIS: The Grading of Recommendations Assessment, Development, and Evaluation approach was used to identify and summarize relevant evidence and develop recommendations for clinical practice. There were 192 studies identified for full-text extraction to address the relevant Patient/Intervention/Comparator/Outcome questions. One clinical recommendation was generated related to the use of dead space fraction for risk stratification. In addition, six research statements were generated about the impact of age on acute respiratory distress syndrome pathobiology and outcomes, addressing PARDS heterogeneity using biomarkers to identify subphenotypes and endotypes, and use of standardized ventilator, physiologic, and nonpulmonary organ failure measurements for future research. CONCLUSIONS: Based on an extensive literature review, we propose clinical management and research recommendations related to characterization and risk stratification of PARDS severity.

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.

Integrated PERSEVERE and endothelial biomarker risk model predicts death and persistent MODS in pediatric septic shock: a secondary analysis of a prospective observational study.

BACKGROUND: Multiple organ dysfunction syndrome (MODS) is a critical driver of sepsis morbidity and mortality in children. Early identification of those at risk of death and persistent organ dysfunctions is necessary to enrich patients for future trials of sepsis therapeutics. Here, we sought to integrate endothelial and PERSEVERE biomarkers to estimate the composite risk of death or organ dysfunctions on day 7 of septic shock. METHODS: We measured endothelial dysfunction markers from day 1 serum among those with existing PERSEVERE data. TreeNet® classification model was derived incorporating 22 clinical and biological variables to estimate risk. Based on relative variable importance, a simplified 6-biomarker model was developed thereafter. RESULTS: Among 502 patients, 49 patients died before day 7 and 124 patients had persistence of MODS on day 7 of septic shock. Area under the receiver operator characteristic curve (AUROC) for the newly derived PERSEVEREnce model to predict death or day 7 MODS was 0.93 (0.91-0.95) with a summary AUROC of 0.80 (0.76-0.84) upon tenfold cross-validation. The simplified model, based on IL-8, HSP70, ICAM-1, Angpt2/Tie2, Angpt2/Angpt1, and Thrombomodulin, performed similarly. Interaction between variables-ICAM-1 with IL-8 and Thrombomodulin with Angpt2/Angpt1-contributed to the models' predictive capabilities. Model performance varied when estimating risk of individual organ dysfunctions with AUROCS ranging from 0.91 to 0.97 and 0.68 to 0.89 in training and test sets, respectively. CONCLUSIONS: The newly derived PERSEVEREnce biomarker model reliably estimates risk of death or persistent organ dysfunctions on day 7 of septic shock. If validated, this tool can be used for prognostic enrichment in future pediatric trials of sepsis therapeutics.

Geospatial Analysis of Social Determinants of Health Identifies Neighborhood Hot Spots Associated With Pediatric Intensive Care Use for Acute Respiratory Failure Requiring Mechanical Ventilation.

OBJECTIVES: Poverty, racial bias, and disparities are linked to adverse health outcomes for children in the United States. The social vulnerability and child opportunity indices are composite measures of the social, economic, education, health, and environmental qualities that affect human health for every U.S. census tract. Composite measures of social vulnerability and child opportunity were compared for neighborhood hot spots, where PICU admissions for acute respiratory failure requiring invasive mechanical ventilation were at the 90th percentile or greater per 1,000 children, versus non-hot spots. DESIGN: Population-based ecological study. SETTING: Two urban free-standing children's hospital PICUs consisting of a 36-bed quaternary academic and a 56-bed tertiary community center, in Atlanta, GA. PATIENTS: Mechanically ventilated children who were 17 years of age or younger with a geocodable Georgia residential address admitted to a PICU for at least 1 day. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Residential addresses were geocoded and spatially joined to census tracts. Composite measures of social vulnerability and childhood opportunity, PICU readmission rates, and hospital length of stay were compared between neighborhood hot spots versus non-hot spots. There were 340 of 3,514 children (9.7%) who lived within a hot spot. Hot spots were associated with a higher (worse) composite social vulnerability index ranking, reflecting differences in socioeconomic status, household composition and disability, and housing type and transportation. Hot spots also had a lower (worse) composite childhood opportunity index percentile ranking, reflecting differences in the education, health and environment, and social and economic domains. Higher social vulnerability and lower childhood opportunity were not associated with readmission rates but were associated with longer total median duration of hospital days per 1,000 children in a census tract. CONCLUSIONS: Social determinants of health identified by geospatial analyses are associated with acute respiratory failure requiring invasive mechanical ventilation in critically ill children. Interventions addressing the neighborhood social vulnerability and child opportunity are needed to decrease disparities in intensive care admissions for acute respiratory failure requiring mechanical ventilation.

The microbiome and the immune system in critical illness.

PURPOSE OF REVIEW: Although the gut microbiome plays a crucial role in the maintenance of health, it is hypothesized to drive morbidity and mortality in critically ill patients. This review describes the relationship between the gut microbiome and the immune system in critical illness. RECENT FINDINGS: The gut microbiome is converted to a pathobiome in the ICU, characterized by decreased microbial diversity and pathogen predominance. These changes are induced by a pathologic microenvironment and are further exacerbated by common medical treatments initiated in the ICU. The conversion of the microbiome to a pathobiome has direct consequences on the regulation of inflammation and immunity by loss of beneficial host responses and initiation of maladaptive changes that can further propagate critical illness. SUMMARY: The gut microbiome is dramatically altered in the ICU. In light of constant crosstalk between the microbiome and the host immune system, the pathobiome may play a key mechanistic role in driving a maladaptive response in critically ill patients. The pathobiome represents a potential therapeutic target in the management of critical illness whereby restoration of a healthier microbiome may directly alter the host inflammatory response, which could lead to improved patient outcomes.

PERSEVERE Biomarkers Predict Severe Acute Kidney Injury and Renal Recovery in Pediatric Septic Shock.

Rationale: Acute kidney injury (AKI), a common complication of sepsis, is associated with substantial morbidity and mortality and lacks definitive disease-modifying therapy. Early, reliable identification of at-risk patients is important for targeted implementation of renal protective measures. The updated Pediatric Sepsis Biomarker Risk Model (PERSEVERE-II) is a validated, multibiomarker prognostic enrichment strategy to estimate baseline mortality risk in pediatric septic shock.Objectives: To assess the association between PERSEVERE-II mortality probability and the development of severe, sepsis-associated AKI on Day 3 (D3 SA-AKI) in pediatric septic shock.Methods: We performed secondary analysis of a prospective observational study of children with septic shock in whom the PERSEVERE biomarkers were measured to assign a PERSEVERE-II baseline mortality risk.Measurements and Main Results: Among 379 patients, 65 (17%) developed severe D3 SA-AKI. The proportion of patients developing severe D3 SA-AKI increased directly with increasing PERSEVERE-II risk category, and increasing PERSEVERE-II mortality probability was independently associated with increased odds of severe D3 SA-AKI after adjustment for age and illness severity (odds ratio, 1.4; 95% confidence interval, 1.2-1.7; P < 0.001). Similar associations were found between increasing PERSEVERE-II mortality probability and the need for renal replacement therapy. Lower PERSEVERE-II mortality probability was independently associated with increased odds of renal recovery among patients with early AKI. A newly derived model incorporating the PERSEVERE biomarkers and Day 1 AKI status predicted severe D3 SA-AKI with an area under the received operating characteristic curve of 0.95 (95% confidence interval, 0.92-0.98).Conclusions: Among children with septic shock, the PERSEVERE biomarkers predict severe D3 SA-AKI and identify patients with early AKI who are likely to recover.

TGF-ß1 Suppresses the Type I IFN Response and Induces Mitochondrial Dysfunction in Alveolar Macrophages.

TGF-ß1 is a pleiotropic cytokine with an established role in fibrosis; however, the immunosuppressive effects of TGF-ß1 are less characterized. Elevated levels of TGF-ß1 are found in patients with acute and chronic lung diseases, and the underlying disease processes are exacerbated by respiratory viral infections. The alveolar macrophage is the first line of cellular defense against respiratory viral infections, and its response to infections is dependent on environmental cues. Using the mouse alveolar macrophage line, MH-S, and human CD14+ monocyte-derived macrophages, we examined the effects of TGF-ß1 on the type I IFN antiviral response, macrophage polarization, and mitochondrial bioenergetics following a challenge with human respiratory syncytial virus (RSV). Our results showed that TGF-ß1 treatment of macrophages decreased the antiviral and proinflammatory response, and suppressed basal, maximal, spare mitochondrial respiration, and mitochondrial ATP production. Challenge with RSV following TGF-ß1 treatment further exacerbated mitochondrial dysfunction. The TGF-ß1 and TGF-ß1+RSV-treated macrophages had a higher frequency of apoptosis and diminished phagocytic capacity, potentially through mitochondrial stress. Disruption of TGF-ß1 signaling or rescue of mitochondrial respiration may be novel therapeutically targetable pathways to improve macrophage function and prevent secondary bacterial infections that complicate viral respiratory infections.

Therapeutic Plasma Exchange in Children With Thrombocytopenia-Associated Multiple Organ Failure: The Thrombocytopenia-Associated Multiple Organ Failure Network Prospective Experience.

OBJECTIVE: The objective was to compare the resolution of organ dysfunction, 28-day mortality, and biochemical markers in children with thrombocytopenia-associated multiple organ failure who received therapeutic plasma exchange versus no therapeutic plasma exchange. DESIGN: Observational longitudinal cohort study. SETTING: Nine U.S. PICUs. PATIENTS: Eighty-one children with sepsis-induced thrombocytopenia-associated multiple organ failure. INTERVENTIONS: Therapeutic plasma exchange. MEASUREMENTS AND MAIN RESULTS: Adjusted relative risk for 28-day mortality was modeled using standard multivariate regression with propensity score weighting to reduce covariate confounding. Change from baseline Pediatric Logistic Organ Dysfunction scores between therapeutic plasma exchange and no therapeutic plasma exchange differed in temporal pattern during the first week (p = 0.009). By day 4, mean Pediatric Logistic Organ Dysfunction score declined by 7.9 points (95% CI, -10.8 to -5.1) in the therapeutic plasma exchange-treated group compared with no change with no therapeutic plasma exchange. Use of therapeutic plasma exchange was associated with reduced 28-day mortality by multivariate analysis (adjusted relative risk, 0.45; 95% CI, 0.23-0.90; p = 0.02) and by propensity score weighting (adjusted relative risk, 0.46; 95% CI, 0.22-0.97; p = 0.04). CONCLUSIONS: Therapeutic plasma exchange use in thrombocytopenia-associated multiple organ failure was associated with a decrease in organ dysfunction. After accounting for several risk factors, 28-day all-cause mortality was lower in children treated with therapeutic plasma exchange compared with those receiving no therapeutic plasma exchange. A multicenter randomized clinical trial is necessary to determine a causal relationship.

Endotype Transitions During the Acute Phase of Pediatric Septic Shock Reflect Changing Risk and Treatment Response.

OBJECTIVE: We previously identified septic shock endotypes A and B based on 100 genes reflecting adaptive immunity and glucocorticoid receptor signaling. The endotypes differ with respect to outcome and corticosteroid responsiveness. We determined whether endotypes change during the initial 3 days of illness, and whether changes are associated with outcomes. DESIGN: Observational cohort study including existing and newly enrolled participants. SETTING: Multiple PICUs. PATIENTS: Children with septic shock. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: We measured the 100 endotyping genes at day 1 and day 3 of illness in 375 patients. We determined if endotype assignment changes over time, and whether changing endotype is associated with corticosteroid response and outcomes. We used multivariable logistic regression to adjust for illness severity, age, and comorbidity burden. Among the 132 subjects assigned to endotype A on day 1, 56 (42%) transitioned to endotype B by day 3. Among 243 subjects assigned to endotype B on day 1, 77 (32%) transitioned to endotype A by day 3. Assignment to endotype A on day 1 was associated with increased odds of mortality. This risk was modified by the subsequent day 3 endotype assignment. Corticosteroids were associated with increased risk of mortality among subjects who persisted as endotype A. CONCLUSIONS: A substantial proportion of children with septic shock transition endotypes during the acute phase of illness. The risk of poor outcome and the response to corticosteroids change with changes in endotype assignment. Patients persisting as endotype A are at highest risk of poor outcomes.

Inflammatory and Comorbid Features of Children Admitted to a PICU for Status Asthmaticus.

OBJECTIVES: To determine risk factors associated with admission to a PICU with or without endotracheal intubation for an asthma exacerbation. We hypothesized that children with critical and near-fatal asthma would have distinguishing clinical features but varying degrees of asthma severity and measures of type 2 inflammation. DESIGN: Retrospective analysis of prospectively collected data of children with asthma recruited into outpatient asthma clinical research studies at Emory University between 2004 and 2015. SETTING: Large, free-standing academic quaternary care children's hospital in Atlanta, GA. PATIENTS: Children 6-18 years old with physician-diagnosed and confirmed asthma. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: A total of 579 children were analyzed with 170 children (29.4%) being admitted to the PICU for an asthma exacerbation in their lifetime. Of these 170 children with a history of critical asthma, 24.1% were classified as having mild-to-moderate asthma, and 83 of 170 children (48.8%) had been intubated and experienced near-fatal asthma. Multiple logistic regression was used to identify risk factors associated with increased odds of PICU admission with or without endotracheal intubation. Hospitalization within the prior 12 months of survey (odds ratio, 8.19; 95% CI, 4.83-13.89), a history of pneumonia (odds ratio, 2.56; 95% CI, 1.52-4.29), having a designation of increased chronic asthma severity on high-dose inhaled corticosteroids (odds ratio, 2.76; 95% CI, 1.62-4.70), having a father with asthma (odds ratio, 2.15; 95% CI, 1.23-3.76), living in a region with a higher burden of poverty (odds ratio, 1.28; 95% CI, 1.02-1.61), and being of black race (odds ratio, 2.01; 95% CI, 1.05-3.84) were all associated with increased odds of PICU admission with or without intubation. CONCLUSIONS: Our findings suggest that there are factors associated with critical and near-fatal asthma, distinct from the chronic asthma severity designations, that should be the focus of future investigation.

Reducing Childhood Admissions to the PICU for Poisoning (ReCAP2) by Predicting Unnecessary PICU Admissions After Acute Intoxication.

OBJECTIVE: To derive and validate clinical prediction models to identify children at low risk of clinically significant intoxications for whom intensive care admission is unnecessary. DESIGN: Retrospective review of data in the National Poison Data Systems from 2011 to 2014 and Georgia Poison Center cases from July to December 2016. SETTING: United States PICUs and poison centers participating in the American Association of Poison Control Centers from 2011 to 2016. PATIENTS: Children 18 years and younger admitted to a United States PICU following an acute intoxication. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: The primary study outcome was the occurrence of clinically significant intoxications defined a priori as organ system-based clinical effects that require intensive care monitoring and interventions. We analyzed 70,364 cases. Derivation (n = 42,240; 60%) and validation cohorts (n = 28,124; 40%) were randomly selected from the eligible population and had similar distributions of clinical effects and PICU interventions. PICU interventions were performed in 1,835 children (14.1%) younger than 6 years, in 374 children (15.4%) 6-12 years, and in 4,446 children (16.5%) 13 years and older. We developed highly predictive models with an area under the receiver operating characteristic curve of 0.834 (< 6 yr), 0.771 (6-12 yr), and 0.786 (≥13 yr), respectively. For predicted probabilities of less than or equal to 0.10 in the validation cohorts, the negative predictive values were 95.4% (< 6 yr), 94.9% (6-12 yr), and 95.1% (≥ 13 yr). An additional 700 patients from the Georgia Poison Center were used to validate the model and would have reduced PICU admission by 31.4% (n = 110). CONCLUSIONS: These validated models identified children at very low risk of clinically significant intoxications for whom pediatric intensive care admission can be avoided. Application of this model using Georgia Poison Center data could have resulted in a 30% reduction in PICU admissions following intoxication.