TRAINED IMMUNITY: A POTENTIAL APPROACH FOR IMPROVING HOST IMMUNITY IN NEONATAL SEPSIS.

ABSTRACT: Sepsis, a dysregulated host immune response to infection, is one of the leading causes of neonatal mortality worldwide. Improved understanding of the perinatal immune system is critical to improve therapies to both term and preterm neonates at increased risk of sepsis. Our narrative outlines the known and unknown aspects of the human immune system through both the immune tolerant in utero period and the rapidly changing antigen-rich period after birth. We will highlight the key differences in innate and adaptive immunity noted through these developmental stages and how the unique immune phenotype in early life contributes to the elevated risk of overwhelming infection and dysregulated immune responses to infection upon exposure to external antigens shortly after birth. Given an initial dependence on neonatal innate immune host responses, we will discuss the concept of innate immune memory, or "trained immunity," and describe several potential immune modulators, which show promise in altering the dysregulated immune response in newborns and improving resilience to sepsis.

Chronic Critical Illness Elicits a Unique Circulating Leukocyte Transcriptome in Sepsis Survivors.

Surgical sepsis has evolved into two major subpopulations: patients who rapidly recover, and those who develop chronic critical illness (CCI). Our primary aim was to determine whether CCI sepsis survivors manifest unique blood leukocyte transcriptomes in late sepsis that differ from transcriptomes among sepsis survivors with rapid recovery. In a prospective cohort study of surgical ICU patients, genome-wide expression analysis was conducted on total leukocytes in human whole blood collected on days 1 and 14 from sepsis survivors who rapidly recovered or developed CCI, defined as ICU length of stay ≥ 14 days with persistent organ dysfunction. Both sepsis patients who developed CCI and those who rapidly recovered exhibited marked changes in genome-wide expression at day 1 which remained abnormal through day 14. Although summary changes in gene expression were similar between CCI patients and subjects who rapidly recovered, CCI patients exhibited differential expression of 185 unique genes compared with rapid recovery patients at day 14 (p < 0.001). The transcriptomic patterns in sepsis survivors reveal an ongoing immune dyscrasia at the level of the blood leukocyte transcriptome, consistent with persistent inflammation and immune suppression. Furthermore, the findings highlight important genes that could compose a prognostic transcriptomic metric or serve as therapeutic targets among sepsis patients that develop CCI.

The impact of sarcopenia and acute muscle mass loss on long-term outcomes in critically ill patients with intra-abdominal sepsis.

BACKGROUND: Sarcopenia is a known risk factor for poor outcomes across many chronic diseases. The impact on outcomes of both pre-existing sarcopenia and acute muscle wasting (AMW) in acute critical illness caused by sepsis remain unclear. METHODS: We conducted a prospective longitudinal cohort study of critically ill patients with intra-abdominal sepsis utilizing abdominal computed tomography at sepsis onset to determine baseline skeletal muscle index (SMI). Biomarkers of inflammation and catabolism were measured through 28 days while hospitalized. We performed follow-up evaluations of strength and physical function at 3, 6, and 12 months, with interval CT analyses at 3 and 12 months to evaluate changes in muscle mass. Measured clinical outcomes included development of chronic critical illness (≥14 days in intensive care with persistent organ dysfunction), long-term functional status, and 1 year mortality. RESULTS: Among 47 sepsis patients enrolled (mean age 53 ± 14 years), half (n = 23; 49%) were sarcopenic at baseline. Overall, sepsis patients exhibited acute and persistent muscle wasting with an average 8% decrease in SMI from baseline at 3 months (P = 0.0008). Sarcopenic (SAR) and non-sarcopenic (NSAR) groups were similar in regards to age and comorbidity burden. SAR patients had greater acute physiologic derangement (APACHE II, 18 vs. 12.5), higher incidence of multiple organ failure (57% vs. 17%), longer hospital (21 vs. 12 days) and intensive care unit length of stays (13 vs. 4 days), and higher inpatient mortality (17% vs. 0%; all P < 0.05). Pre-existing SAR was a strong independent predictor of early death or developing chronic critical illness (odds ratio 11.87, 95% confidence interval CI 1.88-74.9; P = 0.009, area under the curve 0.880) and was associated with significantly higher risk of 1-year mortality (34.9% vs. 4.2%, p = 0.007). Lower baseline SMI was also predictive of poor functional status at 12 months (OR 0.89, 95% confidence interval 0.80-0.99; p = 0.039, area under the curve 0.867). Additionally, SAR patients had AMW with persistent muscle mass loss at 3 months that was associated with decreased health-related quality of life and SF-36 physical function domains (P < 0.05). Persistent AMW at 3 months was not predictive of mortality or poor functional status, with return to near-baseline muscle mass among sepsis survivors by 6 months. CONCLUSIONS: Critically ill patients have an acute and persistent loss of muscle mass after intra-abdominal sepsis, which is associated with decreased health-related quality of life and physical function at 3 months. However, pre-existing sarcopenia, rather than persistent acute muscle mass loss at 3 months after sepsis, is independently associated with poor long-term functional status and increased 1 year mortality.

Analysis of Outcomes in Adolescents and Young Adults With Pilonidal Disease.

Purpose: Numerous definitive surgical techniques exist for the treatment of pilonidal disease with varied recurrence rates and wound complications. Due to the wide array of techniques and lack of consensus on the best approach, we proposed to study our experience treating pilonidal disease in adolescents and young adults. Methods: A retrospective analysis was conducted of patients 10-24 years old treated at a tertiary medical center from 2011 to 2016. Data including demographics, management, and outcomes were collected and analyzed. Primary outcome was recurrence of disease. Results: One hundred and thirty three patients with pilonidal disease underwent operative management. Fifty one percent underwent primary closure and 49% healed by secondary intention with no significant difference in recurrence rates (primary 18%, secondary 11%; p = 0.3245). Secondary healing patients had significantly lower wound complication rates (primary 51%, secondary 23%; p = 0.0012). After accounting for sex, race, weight, and operative technique, age was predictive of disease recurrence with an adjusted odds ratio (OR) of 0.706 (0.560-0.888; p = 0.003). Age and sex were both predictive of wound complications. Older patients had decreased risk of wound complication (adjusted OR 0.806, 95% CI 0.684-0.951; p = 0.0105), and male patients had increased risk of wound complication (adjusted OR 2.902, 95% CI 1.001-8.409; p = 0.0497). Conclusion: In summary, there is no significant difference in the recurrence rates between operative techniques for pilonidal disease. Older patients have decreased risk of recurrence following intervention. Wound complication rates are lower in patients undergoing secondary healing, though this may be better explained by differences in age and sex. Additional research investigating newer, minimally-invasive techniques needs to be pursued.

Septic Stability? Gut Microbiota in Young Adult Mice Maintains Overall Stability After Sepsis Compared to Old Adult Mice.

BACKGROUND: Older adults have worse outcomes after sepsis than young adults. Additionally, alterations of the gut microbiota have been demonstrated to contribute to sepsis-related mortality. We sought to determine if there were alterations in the gut microbiota with a novel sepsis model in old adult mice, which enter a state of persistent inflammation, immunosuppression, and catabolism (PICS), as compared with young adult mice, which recover with the sepsis model. METHODS: Mixed sex old (∼20 mo) and young (∼4 mo) C57Bl/6J mice underwent cecal ligation and puncture with daily chronic stress (CLP+DCS) and were compared with naive age-matched controls. Mice were sacrificed at CLP+DCS day 7 and feces collected for bacterial DNA isolation. The V3-V4 hypervariable region was amplified, 16S rRNA gene sequencing performed, and cohorts compared. α-Diversity was assessed using Chao1 and Shannon indices using rarefied counts, and ß-diversity was assessed using Bray-Curtis dissimilarity. RESULTS: Naive old adult mice had significantly different α and ß-diversity compared with naive adult young adult mice. After CLP+DCS, there was a significant shift in the α and ß-diversity (FDR = 0.03 for both) of old adult mice (naive vs. CLP+DCS). However, no significant shift was displayed in the microbiota of young mice that underwent CLP+DCS in regards to α-diversity (FDR = 0.052) and ß-diversity (FDR = 0.12), demonstrating a greater overall stability of their microbiota at 7 days despite the septic insult. The taxonomic changes in old mice undergoing CLP+DCS were dominated by decreased abundance of the order Clostridiales and genera Oscillospira. CONCLUSION: Young adult mice maintain an overall microbiome stability 7 days after CLP+DCS after compared with old adult mice. The lack of microbiome stability could contribute to PICS and worse long-term outcomes in older adult sepsis survivors. Further studies are warranted to elucidate mechanistic pathways and potential therapeutics.

Single-Cell RNA-seq of Human Myeloid-Derived Suppressor Cells in Late Sepsis Reveals Multiple Subsets With Unique Transcriptional Responses: A Pilot Study.

BACKGROUND: Increased circulating myeloid-derived suppressor cells (MDSCs) are independently associated with poor long-term clinical outcomes in sepsis. Studies implicate subsets of MDSCs having unique roles in lymphocyte suppression; however, characterization of these cells after sepsis remains incomplete. We performed a pilot study to determine the transcriptomic landscape in MDSC subsets in sepsis using single-cell RNAseq (scRNA-seq). METHODS: A mixture of whole blood myeloid-enriched and Ficoll-enriched PBMCs from two late septic patients on post-sepsis day 21 and two control subjects underwent Cellular Indexing of Transcriptomes and Epitopes by Sequencing (CITE-seq). RESULTS: We successfully identified the three MDSC subset clusters-granulocytic (G-), monocytic (M-), and early (E-) MDSCs. Sepsis was associated with a greater relative expansion of G-MDSCs versus M-MDSCs at 21 days as compared to control subjects. Genomic analysis between septic patients and control subjects revealed cell-specific and common differential expression of genes in both G-MDSC and M-MDSC subsets. Many of the common genes have previously been associated with MDSC proliferation and immunosuppressive function. Interestingly, there was no differential expression of several genes demonstrated in the literature to be vital to immunosuppression in cancer-induced MDSC. CONCLUSION: This pilot study successfully demonstrated that MDSCs maintain a transcriptomic profile that is immunosuppressive in late sepsis. Interestingly, the landscape in chronic critical illness is partially dependent on the original septic insult. Preliminary data would also indicate immunosuppressive MDSCs from late sepsis patients appear to have a somewhat unique transcriptome from cancer and/or other inflammatory diseases.

Aluminum Adjuvant Improves Survival Via NLRP3 Inflammasome and Myeloid Non-Granulocytic Cells in a Murine Model of Neonatal Sepsis.

ABSTRACT: Neonatal sepsis leads to significant morbidity and mortality with the highest risk of death occurring in preterm (<37 weeks) and low birth weight (<2,500 g) infants. The neonatal immune system is developmentally immature with well-described defects in innate and adaptive immune responses. Immune adjuvants used to enhance the vaccine response have emerged as potential therapeutic options, stimulating non-specific immunity and preventing sepsis mortality. Aluminum salts ("alum") have been used as immune adjuvants for over a century, but their mechanism of action remains poorly understood. This study aims to identify potential mechanisms by which pretreatment with alum induces host protective immunity to polymicrobial sepsis in neonatal mice. Utilizing genetic and cell-depletion studies, we demonstrate here that the prophylactic administration of aluminum adjuvants in neonatal mice improves sepsis survival via activation of the nucleotide oligomerization domain-like receptor family, pyrin-domain-containing 3 inflammasome and dendritic cell activation. Furthermore, this beneficial effect is dependent on myeloid, non-granulocytic Gr1-positive cells, and MyD88-signaling pathway activation. These findings suggest a promising therapeutic role for aluminum-based vaccine adjuvants to prevent development of neonatal sepsis and improve mortality in this highly vulnerable population.

Transcriptomic responses from improved murine sepsis models can better mimic human surgical sepsis.

Historically, murine models of inflammation in biomedical research have been shown to minimally correlate with genomic expression patterns from blood leukocytes in humans. In 2019, our laboratory reported an improved surgical sepsis model of cecal ligation and puncture (CLP) that provides additional daily chronic stress (DCS), as well as adhering to the Minimum Quality Threshold in Pre-Clinical Sepsis Studies (MQTiPSS) guidelines. This model phenotypically recapitulates the persistent inflammation, immunosuppression, and catabolism syndrome observed in adult human surgical sepsis survivors. Whether these phenotypic similarities between septic humans and mice are replicated at the circulating blood leukocyte transcriptome has not been demonstrated. Our analysis, in contrast with previous findings, demonstrated that genome-wide expression in our new murine model more closely approximated human surgical sepsis patients, particularly in the more chronic phases of sepsis. Importantly, our new model of murine surgical sepsis with chronic stress did not reflect well gene expression patterns from humans with community-acquired sepsis. Our work indicates that improved preclinical murine sepsis modeling can better replicate both the phenotypic and transcriptomic responses to surgical sepsis, but cannot be extrapolated to other sepsis etiologies. Importantly, these improved models can be a useful adjunct to human-focused and artificial intelligence-based forms of research in order to improve septic patients' morbidity and mortality.

Abdominal sepsis patients have a high incidence of chronic critical illness with dismal long-term outcomes.

BACKGROUND: As hospital sepsis mortality has decreased, more surgical ICU survivors are progressing into chronic critical illness (CCI). This study documents the incidence of CCI and long-term outcomes of patients with abdominal sepsis. We hypothesized that patients developing CCI would have biomarker evidence of immune and metabolic derangement, with a high incidence of poor 1-year outcomes. METHODS: Review of abdominal sepsis patients entered in a prospective longitudinal study of surgical ICU sepsis. RESULTS: Of the 144 study patients, only 6% died early, 37% developed CCI (defined as ICU days ≥14 with organ dysfunction) and 57% were classified rapid recovery (RAP). Compared to RAP, CCI patients a) were older (66 vs 58), males who were sicker at baseline (Charlson Comorbidity Index 4 vs 2), b) had persistently elevated biomarkers of dysregulated immunity/metabolism (IL-6, IL-8, sPDL-1, GLP1), c) experienced more secondary infections (4.9 vs 2.3) and organ failure (Denver MOF frequency 40 vs 1%), d) were much more likely to have poor dispositions (85 vs 22%) with severe persistent disabilities by Zubrod Score and e) had a notably higher 1-year mortality of 42% (all p < 0.05). CONCLUSION: Over 1/3rd surgical ICU patients treated for abdominal sepsis progress into CCI and experience dismal long-term outcomes.

Identification of Unique mRNA and miRNA Expression Patterns in Bone Marrow Hematopoietic Stem and Progenitor Cells After Trauma in Older Adults.

Older adults have significantly worse morbidity and mortality after severe trauma than younger cohorts. The competency of the innate immune response decreases with advancing age, especially after an inflammatory insult. Subsequent poor outcomes after trauma are caused in part by dysfunctional leukocytes derived from the host's hematopoietic stem and progenitor cells (HSPCs). Our objective was to analyze the bone marrow (BM) HSPC transcriptomic [mRNA and microRNA (miR)] responses to trauma in older and younger adults. BM was collected intraoperatively <9 days after initial injury from trauma patients with non-mild injury [ISS ≥ 9] or with shock (lactate ≥ 2, base deficit ≥ 5, MAP ≤ 65) who underwent operative fixation of a pelvic or long bone fracture. Samples were also analyzed based on age (<55 years and ≥55 years), ISS score and transfusion in the first 24 h, and compared to age/sex-matched controls from non-cancer elective hip replacement or purchased healthy younger adult human BM aspirates. mRNA and miR expression patterns were calculated from lineage-negative enriched HSPCs. 924 genes were differentially expressed in older trauma subjects vs. age/sex-matched controls, while 654 genes were differentially expressed in younger subjects vs. age/sex-matched control. Only 68 transcriptomic changes were shared between the two groups. Subsequent analysis revealed upregulation of transcriptomic pathways related to quantity, function, differentiation, and proliferation of HSPCs in only the younger cohort. miR expression differences were also identified, many of which were associated with cell cycle regulation. In summary, differences in the BM HSPC mRNA and miR expression were identified between older and younger adult trauma subjects. These differences in gene and miR expression were related to pathways involved in HSPC production and differentiation. These differences could potentially explain why older adult patients have a suboptimal hematopoietic response to trauma. Although immunomodulation of HSPCs may be a necessary consideration to promote host protective immunity after host injury, the age related differences further highlight that patients may require an age-defined medical approach with interventions that are specific to their transcriptomic and biologic response. Also, targeting the older adult miRs may be possible for interventions in this patient population.

The Clinical Presentation and Immunology of Viral Pneumonia and Implications for Management of Coronavirus Disease 2019.

This review will briefly examine the clinical presentation and important immunology of viral pneumonia with a focus on severe acute respiratory syndrome coronavirus 2 (coronavirus disease 2019). DATA SOURCES STUDY SELECTION DATA EXTRACTION AND DATA SYNTHESIS: The most relevant, original and review literature were assessed for inclusion in this review. Sources included the Centers for Disease Control and Prevention, World Health Organization, and PubMed. CONCLUSIONS: Pneumonia is a leading cause of hospitalization and death worldwide, with viral etiologies being very common. Given the rapidly emerging pandemic associated with the novel severe acute respiratory syndrome coronavirus 2 causing coronavirus disease 2019, it is important to review the clinical presentation and immunologic changes associated with viral pneumonia. Symptoms of viral pneumonia include common respiratory tract infection symptoms of cough, fever, and shortness of breath. Immunologic changes include up-regulation of airway pro-inflammatory cytokines and pathogen- and damage-associated molecular patterns contributing to cytokine and genomic changes. Coronavirus disease 2019 clinical presentation is typical of viral pneumonia with an increased prevalence of early pulmonary infiltrates and lymphopenia. Principles of early coronavirus disease 2019 management and isolation as well as potential therapeutic approaches to the emerging pandemic are discussed.

Phenotypic heterogeneity by site of infection in surgical sepsis: a prospective longitudinal study.

BACKGROUND: The role of site of infection in sepsis has been poorly characterized. Additionally, sepsis epidemiology has evolved. Early mortality has decreased, but many survivors now progress into chronic critical illness (CCI). This study sought to determine if there were significant differences in the host response and current epidemiology of surgical sepsis categorized by site of infection. STUDY DESIGN: This is a longitudinal study of surgical sepsis patients characterized by baseline predisposition, insult characteristics, serial biomarkers, hospital outcomes, and long-term outcomes. Patients were categorized into five anatomic sites of infection. RESULTS: The 316 study patients were predominantly Caucasian; half were male, with a mean age of 62 years, high comorbidity burden, and low 30-day mortality (10%). The primary sites were abdominal (44%), pulmonary (19%), skin/soft tissue (S/ST, 17%), genitourinary (GU, 12%), and vascular (7%). Most abdominal infections were present on admission and required source control. Comparatively, they had more prolonged proinflammation, immunosuppression, and persistent organ dysfunction. Their long-term outcome was poor with 37% CCI (defined as > 14 in ICU with organ dysfunction), 49% poor discharge dispositions, and 30% 1-year mortality. Most pulmonary infections were hospital-acquired pneumonia. They had similar protracted proinflammation and organ dysfunction, but immunosuppression normalized. Long-term outcomes are similarly poor (54% CCI, 47% poor disposition, 32% 1-year mortality). S/ST and GU infections occurred in younger patients with fewer comorbidities, less perturbed immune responses, and faster resolution of organ dysfunction. Comparatively, S/ST had better long-term outcomes (23% CCI, 39% poor disposition, 13% 1-year mortality) and GU had the best (10% CCI, 20% poor disposition, 10% 1-year mortality). Vascular sepsis patients were older males, with more comorbidities. Proinflammation was blunted with baseline immunosuppression and organ dysfunction that persisted. They had the worst long-term outcomes (38% CCI, 67% poor disposition, 57% 1-year mortality). CONCLUSION: There are notable differences in baseline predisposition, host responses, and clinical outcomes by site of infection in surgical sepsis. While previous studies have focused on differences in hospital mortality, this study provides unique insights into the host response and long-term outcomes associated with different sites of infection.

Outcomes After Prehospital Endotracheal Intubation in Suburban/Rural Pediatric Trauma.

BACKGROUND: Trauma is the leading cause of death in pediatric patients over 1 y of age. Controversy exists regarding prehospital airway management for these patients, with some studies suggesting that endotracheal intubation in the field or at a referring hospital is associated with increased mortality and complication rate. These studies were largely performed at urban centers, and it is unclear whether the results apply to suburban/rural networks with longer transport times and more stops at referring hospitals. The purpose of this study is to evaluate differential outcomes in pediatric trauma patients who underwent endotracheal intubation at the scene of injury, referring hospital, or pediatric trauma center in a predominantly rural/suburban setting. MATERIALS AND METHODS: A retrospective review was performed evaluating trauma patients age 18 y or younger at a single institution over 10 y (2004-2014). Patients were selected who underwent endotracheal intubation and were classified based on location of intubation (scene, referring hospital, or trauma center). Fischer's exact test and t-tests were performed for comparison. Univariate and multivariate regression analyses were performed. RESULTS: 288 patients were identified. 155 (53.8%) were intubated at the scene of injury, 55 (19.1%) at a referring hospital, and 72 (25%) at the trauma center. Overall mortality was 21.9%, which was highest in the scene intubation group (29.7%) compared with the referring hospital (20%) and trauma center (5.6%) groups (P < 0.01). Patients intubated at the scene had higher Injury Severity Scores and lower Glasgow Coma Scale scores (P < 0.01). Duration of intubation was lowest in the trauma center group (P < 0.01). Complication rate was highest in the referring hospital group (P < 0.05). Multivariate analysis revealed that age, injury severity, and neurologic status were the key drivers of mortality rather than location of intubation. CONCLUSIONS: Mortality and duration of intubation were lowest in trauma patients intubated at a pediatric trauma center. However, location of intubation was not a significant independent predictor of mortality or complications on multivariate analysis, suggesting that age, injury severity, and neurologic status are the main indicators of prognosis in severe pediatric trauma.

Persistently increased cell-free DNA concentrations only modestly contribute to outcome and host response in sepsis survivors with chronic critical illness.

BACKGROUND: Although early survival from sepsis has improved with timely resuscitation and source control, survivors frequently experience persistent inflammation and develop chronic critical illness. We examined whether increased copy number of endogenous alarmins, mitochondrial DNA, and nuclear DNA are associated with the early "genomic storm" in blood leukocytes and the development of chronic critical illness in hospitalized patients with surgical sepsis. METHODS: A prospective, observational, cohort study of critically ill septic patients was performed at a United States tertiary health care center. Blood samples were obtained at multiple time points after the onset of sepsis. Droplet Digital polymerase chain reaction (Bio-Rad Laboratories, Hercules, CA) was performed to quantify RHO (nuclear DNA) and MT-CO2 (mitochondrial DNA) copies in plasma. Leukocyte transcriptomic expression of 63 genes was also measured in whole blood. RESULTS: We enrolled 112 patients with surgical sepsis. Two experienced early death, 69 recovered rapidly, and 41 developed chronic critical illness. Both mitochondrial DNA and nuclear DNA copy number were increased in all sepsis survivors, but early nuclear DNA, and not mitochondrial DNA, copy number was further increased in patients who developed chronic critical illness. Cell-free DNA copy number was associated with in-hospital but not long-term (180-day and 365-day) mortality and were only weakly correlated with leukocyte transcriptomics. CONCLUSION: Increased cell-free DNA copy number persists in survivors of sepsis but is not strongly associated with leukocyte transcriptomics. Nuclear DNA but not mitochondrial DNA copy number is associated with adverse, short-term, clinical trajectories and outcomes.

Predicting Morbidity and Mortality in Neonates Born With Gastroschisis.

BACKGROUND: Gastroschisis is an increasingly common congenital abdominal wall defect. Due to advances in neonatal critical care and early surgical management, mortality from gastroschisis and associated complications has decreased to less than 10% in most series. However, it has been recognized that the outcome of gastroschisis has a spectrum and that the disorder affects a heterogeneous cohort of neonates. The goal of this study is to predict morbidity and mortality in neonates with gastroschisis using clinically relevant variables. METHODS: A multicenter, retrospective observational study of neonates born with gastroschisis was conducted. Neonatal characteristics and outcomes were collected and compared. Prediction of morbidity and mortality was performed using multivariate clinical models. RESULTS: Five hundred and sixty-six neonates with gastroschisis were identified. Overall survival was 95%. Median hospital length of stay was 37 d. Sepsis was diagnosed in 107 neonates. Days on parenteral nutrition and mechanical ventilation were considerable with a median of 27 and 5 d, respectively. Complex gastroschisis (atresia, perforation, volvulus), preterm delivery (<37 wk), and very low birth weight (<1500 g) were associated with worse clinical outcomes including increased sepsis, short bowel syndrome, parenteral nutrition days, and length of stay. The composite metric of birth weight, Apgar score at 5 min, and complex gastroschisis was able to successfully predict mortality (area under the curve, 0.81). CONCLUSIONS: Clinical variables can be used in gastroschisis to distinguish those who will survive from nonsurvivors. Although these findings need to be validated in other large multicenter data sets, this prognostic score may aid practitioners in the identification and management of at-risk neonates.

Immediate versus silo closure for gastroschisis: Results of a large multicenter study.

BACKGROUND/PURPOSE: The optimal method to repair gastroschisis defects continues to be debated. The two primary methods are immediate closure (IC) or silo placement (SP). The purpose of this study was to compare outcomes between each approach using a multicenter retrospective analysis. We hypothesized that patients undergoing SP for ≤5 days would have largely equivalent outcomes compared to IC patients. METHODS: Gastroschisis patient data were collected over a 7-year period. The cohort was separated into IC and SP groups. The SP group was further stratified based on time to closure (≤5 days, 6-10 days, >10 days). Characteristics and outcomes were compared between groups. Multivariate logistic regression was also performed. RESULTS: 566 neonates with gastroschisis were identified including 224 patients in the IC group and 337 patients in the SP group. Among SP patients, 130 were closed within 5 days, 140 in 6-10 days, and 57 in >10 days. There were no significant differences in mortality, sepsis, readmission, or days to full enteral feeds between IC patients and SP patients who had a silo ≤5 days. IC patients had a significantly higher incidence of ventral hernias. Multivariate analysis revealed time to closure as a significant independent predictor of length of stay, ventilator duration, time to full enteral feeds, and TPN duration. CONCLUSIONS: Our data show largely equivalent outcomes between patients who undergo immediate closure and those who have silos ≤5 days. We propose that closure within 5 days avoids many of the risks commonly attributed to delay in closure. LEVEL OF EVIDENCE: Level II retrospective study.

Myeloid-derived suppressor cell function and epigenetic expression evolves over time after surgical sepsis.

BACKGROUND: Sepsis is an increasingly significant challenge throughout the world as one of the major causes of patient morbidity and mortality. Central to the host immunologic response to sepsis is the increase in circulating myeloid-derived suppressor cells (MDSCs), which have been demonstrated to be present and independently associated with poor long-term clinical outcomes. MDSCs are plastic cells and potentially modifiable, particularly through epigenetic interventions. The objective of this study was to determine how the suppressive phenotype of MDSCs evolves after sepsis in surgical ICU patients, as well as to identify epigenetic differences in MDSCs that may explain these changes. METHODS: Circulating MDSCs from 267 survivors of surgical sepsis were phenotyped at various intervals over 6 weeks, and highly enriched MDSCs from 23 of these samples were co-cultured with CD3/CD28-stimulated autologous T cells. microRNA expression from enriched MDSCs was also identified. RESULTS: We observed that MDSC numbers remain significantly elevated in hospitalized sepsis survivors for at least 6 weeks after their infection. However, only MDSCs obtained at and beyond 14 days post-sepsis significantly suppressed T lymphocyte proliferation and IL-2 production. These same MDSCs displayed unique epigenetic (miRNA) expression patterns compared to earlier time points. CONCLUSIONS: We conclude that in sepsis survivors, immature myeloid cell numbers are increased but the immune suppressive function specific to MDSCs develops over time, and this is associated with a specific epigenome. These findings may explain the chronic and persistent immune suppression seen in these subjects.