Immunological Defects in Neonatal Sepsis and Potential Therapeutic Approaches

Coarctation of the Aorta and Late-Onset Sepsis With Supraventricular Tachycardia: A Clinical Case Review

We report a case of an 11-day-old male infant who presented to our hospital with complaints of breathing difficulty and cough for two days prior to admission. The child had a seizure post-admission which was controlled with phenobarbitone. The child was connected to a mechanical ventilator. The baby also had persistent tachycardia, which upon doing an electrocardiogram (ECG) led to a diagnosis of supraventricular tachycardia (SVT). Additional investigations revealed the existence of late-onset sepsis (LOS), which was treated with appropriate antibiotics. In view of weak femoral pulses with normal brachial pulses, a diagnosis of coarctation of the aorta (CoA) was entertained. The diagnosis was confirmed by an echocardiogram, and the baby was transferred to a higher-level medical center for surgical correction. Regrettably, the baby succumbed to heart failure and shock on the 12th day of life. This case highlights the infrequency of CoA accompanied by SVT. The case delves into the challenges of diagnosing the condition, the necessary medical interventions, and the unforeseen complications that must be considered to reduce mortality in such circumstances.

Myocardial performance imaging for the early identification of cardiac dysfunction in neonates with sepsis

PURPOSE

The assessment of cardiac performance in septic new-borns is crucial for detecting hemodynamic instability and predicting outcome. The aim of the study is to assess myocardial performance in neonates with sepsis for the early identification of cardiac dysfunction.

PATIENTS AND METHODS

A case control study was carried out from September 2022 to May 2023 at the Neonatal Intensive care unit, Kasturba Medical College, Manipal. A total of 68 neonates were included in the study, with 33 females and 35 males. The study population was further subdivided into 3 groups namely preterm septic neonates (n = 21), term septic neonates (n = 10) and non-septic healthy controls (n = 37). The cardiac structure and function were assessed using conventional method, Tissue Doppler imaging (Sm) and speckle tracking echocardiography (GLS). The study was approved by the Institutional Ethics Committee at Kasturba Medical College, Manipal (approval number IEC: 90/2022). The CTRI registration number for the study is CTRI/2022/09/045437 and was approved on September 12, 2022. Prior to the neonate's enrolment, informed consent was obtained from their mothers or legal guardians.

RESULTS

Out of the total 68 neonates, 31 were cases and 37 were controls which included 33 females and 35 males. LV systolic function was not statistically significant between cases and controls. E/A ratio of the mitral valve was significantly lower in septic newborns than in healthy neonates. (1.01 ± 0.35 vs 1.18 ± 0.31, p < 0.05) preterm neonates showed significantly lower Lateral E' and RV E' velocities than term neonates. TAPSE was significantly lower in septic preterm neonates. (8.61 ± 1.28 vs. 10.7 ± 2.11, p < 0.05) No significant difference was noted in the Myocardial Performance Index between septic neonates and healthy neonates. LV Global Longitudinal Strain was slightly lower in preterm septic neonates than in term neonates with sepsis.

CONCLUSION

Septic newborns are associated with LV diastolic dysfunction, RV systolic dysfunction and substantially higher pulmonary systolic pressures.

Predictive Role of NLR, dNLR, PLR, NLPR, and Other Laboratory Markers in Diagnosing SIRS in Premature Newborns

BACKGROUND

Premature newborns are at a significant risk for Systemic Inflammatory Response Syndrome SIRS, a condition associated with high morbidity and mortality. This study aimed to evaluate the predictive and diagnostic capability of laboratory markers like Neutrophil to Lymphocyte Ratio (NLR), derived Neutrophil to Lymphocyte Ratio (dNLR), Platelet-to-Lymphocyte Ratio (PLR), and Neutrophil-to-Lymphocyte-to-Platelet Ratio (NLPR) in diagnosing SIRS in premature newborns.

METHODS

Premature newborns with and without SIRS were evaluated in a prospective design during a one-year period. Among 136 newborns, early and 72 h post-birth analyses were performed.

RESULTS

At 24 h, NLR's cutoff value was 8.69, yielding sensitivity and specificity rates of 52.77% and 83.47% (p = 0.0429), respectively. The dNLR showed a cutoff of 5.61, with corresponding rates of 63.27% and 84.15% (p = 0.0011), PLR had a cutoff of 408.75, with rates of 51.89% and 80.22% (p = 0.1026), and NLPR displayed a cutoff of 0.24, with rates of 75.85% and 86.70% (p = 0.0002). At 72 h, notable sensitivity and specificity improvements were observed, particularly with NLPR having a cutoff of 0.17, showing sensitivity of 77.74% and specificity of 95.18% (p < 0.0001). NLR above the cutoff indicated a 33% increase in SIRS risk, with a hazard ratio (HR)of 1.33. The dNLR was associated with a twofold increase in risk (HR 2.04). NLPR demonstrated a significant, over threefold increase in SIRS risk (HR 3.56), underscoring its strong predictive and diagnostic value for SIRS development.

CONCLUSION

Integrating these findings into clinical practice could enhance neonatal care by facilitating the early identification and management of SIRS, potentially improving outcomes for this vulnerable population.

Circulating bacterial peptides and linked metabolomic signatures are indicative of early mortality in pediatric cirrhosis

BACKGROUND

Patients with pediatric cirrhosis-sepsis (PC-S) attain early mortality. Plasma bacterial composition, the cognate metabolites, and their contribution to the deterioration of patients with PC-S to early mortality are unknown. We aimed to delineate the plasma metaproteome-metabolome landscape and identify molecular indicators capable of segregating patients with PC-S predisposed to early mortality in plasma, and we further validated the selected metabolite panel in paired 1-drop blood samples using untargeted metaproteomics-metabolomics by UHPLC-HRMS followed by validation using machine-learning algorithms.

METHODS

We enrolled 160 patients with liver diseases (cirrhosis-sepsis/nonsepsis [n=110] and noncirrhosis [n=50]) and performed untargeted metaproteomics-metabolomics on a training cohort of 110 patients (Cirrhosis-Sepsis/Nonsepsis, n=70 and noncirrhosis, n=40). The candidate predictors were validated on 2 test cohorts-T1 (plasma test cohort) and T2 (1-drop blood test cohort). Both T1 and T2 had 120 patients each, of which 70 were from the training cohort.

RESULTS

Increased levels of tryptophan metabolites and Salmonella enterica and Escherichia coli-associated peptides segregated patients with cirrhosis. Increased levels of deoxyribose-1-phosphate, N5-citryl-d-ornithine, and Herbinix hemicellulolytic and Leifsonia xyli segregated patients with PC-S. MMCN-based integration analysis of WMCNA-WMpCNA identified key microbial-metabolic modules linked to PC-S nonsurvivors. Increased Indican, Staphylobillin, glucose-6-phosphate, 2-octenoylcarnitine, palmitic acid, and guanidoacetic acid along with L. xyli, Mycoplasma genitalium, and Hungateiclostridium thermocellum segregated PC-S nonsurvivors and superseded the liver disease severity indices with high accuracy, sensitivity, and specificity for mortality prediction using random forest machine-learning algorithm.

CONCLUSIONS

Our study reveals a novel metabolite signature panel capable of segregating patients with PC-S predisposed to early mortality using as low as 1-drop blood.

Herpes virus entry mediator signaling blockade produces mortality in neonatal sepsis through induced cardiac dysfunction

Introduction

Sepsis remains a major source of morbidity and mortality in neonates, and characterization of immune regulation in the neonatal septic response remains limited. HVEM is a checkpoint regulator which can both stimulate or inhibit immune responses and demonstrates altered expression after sepsis. We hypothesized that signaling via HVEM would be essential for the neonatal response to sepsis, and that therefore blockade of this pathway would improve survival to septic challenge.

Methods

To explore this, neonatal mice were treated with cecal slurry (CS), CS with Anti-HVEM antibody (CS-Ab) or CS with isotype (CS-IT) and followed for 7-day survival. Mice from all treatment groups had thymus, lung, kidney and peritoneal fluid harvested, weighed, and stained for histologic evaluation, and changes in cardiac function were assessed with echocardiography.

Results

Mortality was significantly higher for CS-Ab mice (72.2%) than for CS-IT mice (22.2%). CS resulted in dysregulated alveolar remodeling, but CS-Ab lungs demonstrated significantly less dysfunctional alveolar remodeling than CS alone (MCL 121.0 CS vs. 87.6 CS-Ab), as well as increased renal tubular vacuolization. No morphologic differences in alveolar septation or thymic karyorrhexis were found between CS-Ab and CS-IT. CS-Ab pups exhibited a marked decrease in heart rate (390.3 Sh vs. 342.1 CS-Ab), stroke volume (13.08 CS-IT vs. 8.83 CS-Ab) and ultimately cardiac output (4.90 Sh vs. 3.02 CS-Ab) as well as a significant increase in ejection fraction (73.74 Sh vs. 83.75 CS-Ab) and cardiac strain (40.74 Sh vs. 51.16 CS-Ab) as compared to CS-IT or Sham animals.

Discussion

While receptor ligation of aspects of HVEM signaling, via antibody blockade, appears to mitigate aspects of lung injury and thymic involution, stimulatory signaling via HVEM still seems to be necessary for vascular and hemodynamic resilience and overall neonatal mouse survival in response to this experimental polymicrobial septic insult. This dissonance in the activity of anti-HVEM neutralizing antibody in neonatal animals speaks to the differences in how septic cardiac dysfunction should be considered and approached in the neonatal population.

Factors Associated With Culture-proven Neonatal Sepsis and Resistance to First-line Antibiotics in Indonesia

BACKGROUND

Neonatal sepsis is one of the leading causes of neonatal morbidity and mortality in low- and middle-income countries. Blood culture positivity rates and antibiotic resistance pattern of neonatal sepsis differs across various regions. This study aims to identify clinical cofactors associated with blood culture-proven neonatal sepsis and in vitro resistance to first-line antibiotics (ampicillin and gentamicin) from cases originating in a tertiary healthcare center in Surabaya, Indonesia.

METHODS

A retrospective cohort study was conducted from January 2020 to August 2022 by utilizing secondary data collected from standardized electronic medical records. Microbiologic characteristics and associated factors were statistically analyzed using multivariable logistic regression.

RESULTS

Across 266 neonatal sepsis cases, 46.9% were culture-proven and 79.2% of confirmed sepsis were resistant to first-line antibiotics. The most common isolated pathogen is Klebsiella pneumoniae , followed by coagulase-negative Staphylococci , Acinetobacter baumannii and Enterobacter cloacae . Extremely preterm delivery [adjusted odds ratio (aOR): 5.813; 95% confidence interval (CI): 1.70-19.91] and late-onset sepsis (aOR: 9.165; 95% CI: 5.12-16.40) were associated with culture-proven neonatal sepsis. Increased odds of resistance to first-line antibiotics were identified in extremely preterm (<28 weeks) or very-preterm delivery (28 to <32 weeks) (aOR: 50.80; 95% CI: 1.66-1554.21 and aOR: 45.679; 95% CI: 3.22-647.46, respectively), cesarean section (aOR: 4.149; 95% CI: 1.04-16.53) and an absence of antenatal corticosteroid use (aOR: 0.233; 95% CI: 0.07-0.76).

CONCLUSIONS

The association between clinical cofactors with culture-proven sepsis and antibiotic resistance emphasizes the importance for clinicians to adjust empirical antibiotic regimens based on the local antibiogram and resource availability.

Incidence of infant Gram-negative invasive bacterial infections in England, 2011-2019: an observational study using population-wide surveillance data

OBJECTIVE

Invasive bacterial infections account for an estimated 15% of infant deaths worldwide. We aimed to estimate the incidence and trends in invasive bacterial infections in infants caused by Gram-negative pathogens in England during 2011-2019.

METHODS

Laboratory-confirmed invasive bacterial infections in infants (<1 year old) were identified in the UK Health Security Agency national laboratory surveillance data from April 2011 to March 2019. Polymicrobial infections were defined as two or more bacterial species from the same normally sterile sample site. Early-onset infections were defined as <7 days from birth and late-onset as ≥7 days (neonates 7-28 days; infants ≥29 days). Trend analyses were carried out using Poisson (for episodes/incidence) and beta (for proportions) regression.

RESULTS

The annual incidence of invasive bacterial infections increased by 35.9%, from 189.8 to 258.0 cases per 100 000 live births (p<0.001). Late-onset infections in both neonates and infants increased substantially over the study period (p<0.001), whereas early-onset infections increased slightly (p=0.002). Escherichia coli was the most common Gram-negative pathogen isolated and accounted for 27.2% of the overall rise in Gram-negative infant disease incidence. Polymicrobial infections almost doubled, increasing from 29.2 to 57.7 per 100 000 live births (p<0.001), and mostly involved two species (81.3%, 1604/1974 episodes).

CONCLUSIONS

The incidence of Gram-negative invasive bacterial infections in infants increased between 2011/2012 and 2018/2019 in England, driven mainly by an increase in late-onset infections. Further work is required to elucidate the risk factors and drivers of this increased incidence so that opportunities for prevention can be identified.

Special Issue "Recent Advances in Neonatal Sepsis"

Perinatal medicine and neonatology have seen significant advancements in recent decades [...].

Dual inhibition of complement C5 and CD14 attenuates inflammation in a cord blood model

BACKGROUND

Escherichia coli and Group B streptococci (GBS) are the main causes of neonatal early-onset sepsis (EOS). Despite antibiotic therapy, EOS is associated with high morbidity and mortality. Dual inhibition of complement C5 and the Toll-like receptor co-factor CD14 has in animal studies been a promising novel therapy for sepsis.

METHODS

Whole blood was collected from the umbilical cord after caesarean section (n = 30). Blood was anti-coagulated with lepirudin. C5 inhibitor (eculizumab) and anti-CD14 was added 8 min prior to, or 15 and 30 min after adding E. coli or GBS. Total bacterial incubation time was 120 min (n = 16) and 240 min (n = 14). Cytokines and the terminal complement complex (TCC) were measured using multiplex technology and ELISA.

RESULTS

Dual inhibition significantly attenuated TCC formation by 25-79% when adding inhibitors with up to 30 min delay in both E. coli- and GBS-induced inflammation. TNF, IL-6 and IL-8 plasma concentration were significantly reduced by 28-87% in E. coli-induced inflammation when adding inhibitors with up to 30 min delay. The dual inhibition did not significantly reduce TNF, IL-6 and IL-8 plasma concentration in GBS-induced inflammation.

CONCLUSION

Dual inhibition of C5 and CD14 holds promise as a potential future treatment for severe neonatal EOS.

IMPACT

Neonatal sepsis can cause severe host inflammation with high morbidity and mortality, but there are still no effective adjunctive immunologic interventions available. Adding CD14 and complement C5 inhibitors up to 30 min after incubation of E. coli or Group B streptococci in a human umbilical cord blood model significantly reduced complement activation and cytokine release. Dual inhibition of C5 and CD14 is a potential future therapy to modulate systemic inflammation in severe cases of neonatal sepsis.

Hematological changes in neonatal mice with phlebotomy-induced anemia

BACKGROUND

Anemia is a nearly universal diagnosis in preterm infants, caused by phlebotomy, and exacerbated by the underlying erythropoietic immaturity. Newborn infants are exposed to the unique stressor of fetal-to-neonatal transition, which requires significant adaptation ex utero. Accordingly, the preterm infant's response to anemia may alter the ability to confront underlying illness. This study utilized our preclinical mouse model of phlebotomy-induced anemia (PIA) to comprehensively investigate associated hematological changes.

METHODS

C57BL/6 mice were subjected to timed phlebotomy between postnatal days 2--10 to induce severe anemia. Complete blood counts were determined by the Sysmex XT-2000iV analyzer.

RESULTS

Anemic pups showed a gradual reduction of RBC and hemoglobin (Hb) and increased reticulocyte (RET) counts and red cell distribution width (RDW), however, with reduced RET-Hb from postnatal day (P) of 4 onwards. Elevated levels of high fluorescent RET and immature reticulocyte fraction (IRF) were noted in anemic mouse pups, but low and medium fluorescent RET were reduced. Also, the reduction of mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), and mean corpuscular hemoglobin concentration (MCHC) were noted in anemic pups. No changes were seen in lymphocytes, but monocytes and neutrophils were significantly elevated from P4-P6.

CONCLUSIONS

PIA in mouse pups is associated with hematological changes that may be exacerbating factors in neonatal diseases.

IMPACT

Anemia is common and often severe in premature infants. Investigation of hematological parameters in settings of preclinical anemia may be an index of therapeutic strategies. Preclinical model evaluating the effects of neonatal anemia on the remainder of complete blood count. Detailed time kinetic phlebotomy-induced anemic mice enable us to study the impact on developmental delays in erythropoiesis and possible strategic intervention. Hematological effects of severe anemia in mice might provide insight on how best to investigate anemia in preterm infants.

Induction of Trained Immunity Protects Neonatal Mice Against Microbial Sepsis by Boosting Both the Inflammatory Response and Antimicrobial Activity

Background

Neonates are susceptible to a wide range of microbial infection and at a high risk to develop severe sepsis and septic shock. Emerged evidence has shown that induction of trained immunity triggers a much stronger inflammatory response in adult monocytes/macrophages, thereby conferring protection against microbial infection.

Methods

This study was carried out to examine whether trained immunity is inducible and exerts its protection against microbial sepsis in neonates.

Results

Induction of trained immunity by Bacillus Calmette-Guerin (BCG) plus bacterial lipoprotein (BLP) protected neonatal mice against cecal slurry peritonitis-induced polymicrobial sepsis, and this protection is associated with elevated circulating inflammatory cytokines, increased neutrophil recruitment, and accelerated bacterial clearance. In vitro stimulation of neonatal murine macrophages with BCG+BLP augmented both inflammatory response and antimicrobial activity. Notably, BCG+BLP stimulation resulted in epigenetic remodeling characterized by histone modifications with enhanced H3K4me3, H3K27Ac, and suppressed H3K9me3 at the promoters of the targeted inflammatory and antimicrobial genes. Critically, BCG+BLP stimulation led to a shift in cellular metabolism with increased glycolysis, which is the prerequisite for subsequent BCG+BLP-triggered epigenetic reprogramming and augmented inflammatory response and antimicrobial capacity.

Conclusion

These results illustrate that BCG+BLP induces trained immunity in neonates, thereby protecting against microbial infection by boosting both inflammatory and antimicrobial responses.

Neonatal Antibiotic Treatment Can Affect Stool Pattern and Oral Tolerance in Preterm Infants

Preterm neonates are at high risk of infectious and inflammatory diseases which require antibiotic treatment. Antibiotics influence neonatal gut microbiome development, and intestinal dysbiosis has been associated with delayed gastrointestinal transit. Neonates who take less time to pass meconium have a better tolerance to enteral feeding. We analyzed the effect of neonatal antibiotic treatment on the stool pattern and oral tolerance in 106 preterm infants < 33 weeks gestational age. Neonates were classified in 3 groups according to neonatal antibiotic (ABT) treatment days: no antibiotics, 3−7 d ABT, and ≥8 d ABT. Preterm infants from the ≥8 d ABT group took longer to pass meconium and to start green and yellow stools, took longer to reach 100 and 150 mL/kg/day, and reached reduced volumes in enteral feeds at day of life 14 and 28 than infants from no ABT and 3−7 d ABT groups. Multiple linear regression models showed that neonatal antibiotic treatment, birth weight, invasive mechanical ventilation, surfactant, enteral feeding start day, neonatal parenteral nutrition, and neonatal fasting days are associated with the stool pattern and oral tolerance in preterm infants.

Admission Outcome and Antimicrobial Resistance Pattern of Bacterial Isolates among Neonates with Suspected Sepsis in Neonatal Intensive Care Unit at Dessie Comprehensive Specialized Hospital, Dessie, Northeastern Ethiopia

Background

Neonatal sepsis is a major cause of morbidity and mortality globally. The aim of this study was to assess admission outcome and antimicrobial susceptibility pattern of bacterial isolates among neonates with suspected sepsis at the Dessie Comprehensive specialized Hospital (DCSH), Northeastern Ethiopia.

Method

Cross-sectional study was conducted from August 2017 to March 2018. Two hundred forty-six neonates were recruited, and each patient's blood specimen was collected aseptically using bottle containing Brain Heart Infusion for blood culture. Both clinical and laboratory data such as bacterial culture growth and antimicrobial susceptibility pattern were collected from the neonate; clinical data from the mothers were also included. Antimicrobial susceptibility testing was performed using Kirby-Bauer disk diffusion method. The data were analyzed using SPSS version 20.

Results

Bacteria were identified from 67 (27.2%) blood cultures. The predominant pathogen was Escherichia coli (35.8%) followed by Staphylococcus aureus (26.8%), and Coagulase Negative Staphylococcus (CoNS) (19.4%). The isolated bacteria showed resistance to Ampicillin 55 (82%), third-generation Cephalosporins 21 (58.3%) and other tested antimicrobials. Overall, 68.6% bacterial isolates demonstrated Multidrug resistance (MDR) and total registered mortality rate was 12/246 (4.8%). Both neonatal factors such as neonatal temperature, septic umbilicus and utilization of indwelling medical device during delivery; and maternal factors such as age, antenatal urinary tract infection (UTI), mode of delivery and prolonged rupture of membrane (PROM) had shown statistically significant association with bacterial sepsis.

Conclusion

The rate of bacterial growth was found to be high; E. coli and S. aureus were the predominant organisms. Both maternal and neonatal related data were strong predictors for bacterial infection of the neonate. Therefore, improving infrastructures for screening of bacteremia as well as active surveillance in clinical setting needed to ensure proper empirical therapy.

Global DNA hypomethylation and the expression profile of DNA methyltransferase genes in late-onset neonatal sepsis

Aim: Infectious organisms tend to cause DNA methylation changes. Thus, this paper aims to study global DNA methylation and the expression of DNA methyltransferase (DNMT) genes in late-onset neonatal sepsis (LONS). Methods: Global and Alu DNA methylation and expression levels of DNMT were performed using 5mc ELISA, methylation-specific PCR and quantitative real-time-PCR, respectively for LONS and controls. Results: Significant hypomethylation of global DNA and Alu DNA methylation and lower expression of DNMT1 and DNMT3a were observed in LONS compared with controls. Receiver operating characteristic analysis of global and Alu DNA methylation showed good discrimination for the identification of LONS. Conclusion: The hypomethylation of global DNA and Alu elements is evident in neonates with LONS. This may be clinically useful for the prognosis of LONS.

Neonatal Sepsis and Hemostasis

Neonatal sepsis is considered critical for a significant increase in neonatal morbidity and mortality among hospitalized neonates. Neonatal sepsis, in most cases, coexists with coagulopathy, which can prove to be life-threatening. Complex molecular and cellular systems are involved in the cross-talk between inflammation and hemostasis during sepsis. Disturbances in the regulating systems of the vascular endothelium, and platelet–endothelial and platelet–neutrophil interactions play a pivotal role in both inflammation and coagulation. This complex process is poorly understood in neonates. In addition to the developmental maturation of hemostasis and the immune response in neonatal sepsis, a cellular model of hemostasis during sepsis should be taken into account. This review focused on the molecular and cellular mechanisms underlying inflammation and hemostasis during neonatal sepsis, taking the developmental immune response and developmental hemostasis into account in order to provide future diagnostic approaches to be applied in everyday clinical settings. Regarding the diagnostic modalities, we briefly provide the limitations of the currently used conventional coagulation assays, focusing on viscoelastic tests and platelet flow cytometry.

MicroRNA Expression in Neonates with Late-onset Sepsis - A Cross-sectional Comparative Study

BACKGROUND

Neonatal sepsis is a major health concern among neonates with higher morbidity and mortality rate. Studies have recently speculated the importance of differential expression of circulating mature micro-RNAs (miRNAs) which could serve as diagnostic as well as prognostic markers for risk of mortality in neonatal sepsis. This study aimed to analyze the expression pattern and to assess the diagnostic/prognostic value of miRNAs miR-21, miR-29a miR-31, miR-146a, and miR-155 in late-onset neonatal sepsis.

METHODS

A cross-sectional comparative study was conducted including 42 healthy controls and 42 neonates with late-onset neonatal sepsis. SYBR green-based miScript RT-PCR assay was used for the expression analysis and the comparative Ct method 2-delta (Ct) method was used for relative quantification of the candidate miRNAs in plasma. Significantly higher expression of miR-21 and miR-155 and lower expression of miR-29a and miR-146a was observed in cases compared to control except miR-31. In subgroups analysis, miR-21(p = .03) showed a significant difference between pre-term and term neonates and miR-31 (p = .01) and miR-155 (p = .03) showed a significant difference between low-birth-weight and normal-birth-weight neonates. miR-146a showed significantly lower expression in the non-survivor group compared to the survivor group (p = .005). A receiver operating characteristic curve (ROC) analysis of miR-21 and miR-29a (0.829 and 0.787 AUC of ROC curves) showed good discrimination for the identification of sepsis from non-sepsis neonates.

CONCLUSION

The current study shows evidence of differential expression of miRNAs in neonatal sepsis and this altered expression of candidate miRNAs could be involved in immune dysregulation, thus leading to sepsis-related severity in newborns.

Protective Role of an Initial Low-Dose Septic Challenge against Lethal Sepsis in Neonatal Mice: A Pilot Study

Neonatal sepsis is characterized by systemic bacterial invasion followed by a massive inflammatory response. At present, no therapeutic strategy has been found that significantly reduces the mortality of neonatal sepsis. We aimed to investigate the protective role of an initial low-dose septic challenge for the prevention of subsequent lethal sepsis in a mouse model. A stock cecal slurry (CS) solution was prepared from adult ceca. The LD83 (1.5 mg CS/g) was used for all animals. An initial challenge of normal saline (NS) or 0.5 mg CS/g (non-lethal dose) was administered at four days of age, then 1.5 mg CS/g was administered intraperitoneally at seven days of age (72 h post-initial challenge), and survival was monitored. Initial exposure to NS (n = 10) resulted in 90% mortality following exposure to the LD83 CS dose in contrast to an initial exposure to CS (n = 16), which significantly decreased mortality to 6% (p < 0.0001), reduced blood bacterial counts, attenuated inflammatory responses, and suppressed lipid mediators. Initial exposure to a non-lethal CS dose prior to exposure to a lethal CS dose significantly reduces sepsis mortality, a protective effect that might be mediated by modulating abnormal systemic inflammatory responses.

Clinical and immunological aspects of microRNAs in neonatal sepsis

Neonatal sepsis constitutes a highly relevant public health challenge and is the most common cause of infant morbidity and mortality worldwide. Recent studies have demonstrated that during infection epigenetic changes may occur leading to reprogramming of gene expression. Post-transcriptional regulation by short non-coding RNAs (e.g., microRNAs) have recently acquired special relevance because of their role in the regulation of the pathophysiology of sepsis and their potential clinical use as biomarkers. ~22-nucleotide of microRNAs are not only involved in regulating multiple relevant cellular and molecular functions, such as immune cell function and inflammatory response, but have also been proposed as good candidates as biomarkers in sepsis. Nevertheless, establishing clinical practice guidelines based on microRNA patterns as biomarkers for diagnosis and prognosis in neonatal sepsis has yet to be achieved. Given their differential expression across tissues in neonates, the release of specific microRNAs to blood and their expression pattern can differ compared to sepsis in adult patients. Further in-depth research is necessary to fully understand the biological relevance of microRNAs and assess their potential use in clinical settings. This review provides a general overview of microRNAs, their structure, function and biogenesis before exploring their potential clinical interest as diagnostic and prognostic biomarkers of neonatal sepsis. An important part of the review is focused on immune and inflammatory aspects of selected microRNAs that may become biomarkers for clinical use and therapeutic intervention.

Sex- and Gender-Dependent Differences in Clinical and Preclinical Sepsis

ABSTRACT

In this mini-review we provide an overview of sex- and gender-dependent issues in both clinical and preclinical sepsis. The increasing recognition for the need to account for sex and gender in biomedical research brings a unique set of challenges and requires researchers to adopt best practices when conducting and communicating sex- and gender-based research. This may be of particular importance in sepsis, given the potential contribution of sex bias in the failures of translational sepsis research in adults and neonates. Clinical evidence of sex-dependent differences in sepsis is equivocal. Since clinical studies are limited to observational data and confounded by a multitude of factors, preclinical studies provide a unique opportunity to investigate sex differences in a controlled, experimental environment. Numerous preclinical studies have suggested that females may experience favorable outcomes in comparison with males. The underlying mechanistic evidence for sex-dependent differences in sepsis and other models of shock (e.g., trauma-hemorrhage) largely centers around the beneficial effects of estrogen. Other mechanisms such as the immunosuppressive role of testosterone and X-linked mosaicism are also thought to contribute to observed sex- and gender-dependent differences in sepsis. Significant knowledge gaps still exist in this field. Future investigations can address these gaps through careful consideration of sex and gender in clinical studies, and the use of clinically accurate preclinical models that reflect sex differences. A better understanding of sex-and gender-dependent differences may serve to increase translational research success.

The Effect of Neonatal Sepsis on Risk of Autism Diagnosis

OBJECTIVE

 The study aimed to examine the association between neonatal sepsis and autism risk among children and whether the risk varied with the timing of exposure, child's sex, and race/ethnicity.

STUDY DESIGN

 We conducted a retrospective cohort study using electronic health records (EHR) extracted from Kaiser Permanente Southern California Health Care System. Mother-child dyads were constructed by linking records of children born to member mothers and continuing to receive care through the system during the follow-up period with those of their biological mothers (n = 469,789). Clinical health records were used to define neonatal sepsis. Diagnosis of autism was made by medical specialists. Potential confounders included maternal sociodemographic factors, obstetrical history, child's age, sex, race/ethnicity, and maternal and child medical history. Incident rates and adjusted hazard ratios (aHR) were used to estimate the associations.

RESULTS

 Compared with children without the diagnosis of autism, children with the condition were more likely to be from Asian/Pacific Islander descent and male sex. Exposed children showed higher rates of autism as compared with unexposed children (3.43 vs. 1.73 per 1,000 person-years, aHR: 1.67-95% confidence interval [CI]: 1.39-2.00). Both preterm (aHR: 1.47; 95% CI: 1.09-1.98) and term (aHR: 1.63; 95% CI: 1.29-2.06) births were associated with increased risk for autism. Although the magnitude of the HRs and incidence ratios for neonatal sepsis to increase autism risk varied between race ethnicities, neonatal sepsis was associated with significantly increased likelihood of autism diagnosis for all race-ethic groups except for Asian/Pacific Islanders. Although neonatal sepsis was associated with significantly increased autism risk for both boys and girls, incident rates and HR point estimates suggested that the effect may be stronger in girls.

CONCLUSION

 Neonatal sepsis is associated with increased risk of autism diagnosis in preterm- and term-born children. The association was significant for both girls and boys and all race ethnicities except for Asian-Pacific Islanders.

KEY POINTS

· Neonatal sepsis is associated with increased risk of autism diagnosis.. · The association was significant in preterm- and term-born children.. · The association was significant for all race/ethnicities except for Asian-Pacific Islanders..

Exploring Clinically-Relevant Experimental Models of Neonatal Shock and Necrotizing Enterocolitis

Neonatal shock and necrotizing enterocolitis (NEC) are leading causes of morbidity and mortality in premature infants. NEC is a life-threatening gastrointestinal illness, the precise etiology of which is not well understood, but is characterized by an immaturity of the intestinal barrier, altered function of the adaptive immune system, and intestinal dysbiosis. The complexities of NEC and shock in the neonatal population necessitate relevant clinical modeling using newborn animals that mimic the disease in human neonates to better elucidate the pathogenesis and provide an opportunity for the discovery of potential therapeutics. A wide variety of animal species-including rats, mice, piglets, and primates-have been used in developing experimental models of neonatal diseases such as NEC and shock. This review aims to highlight the immunologic differences in neonates compared with adults and provide an assessment of the advantages and drawbacks of established animal models of both NEC and shock using enteral or intraperitoneal induction of bacterial pathogens. The selection of a model has benefits unique to each type of animal species and provides individual opportunities for the development of targeted therapies. This review discusses the clinical and physiologic relevance of animal models and the insight they contribute to the complexities of the specific neonatal diseases: NEC and shock.

DNA Methylation Analysis to Unravel Altered Genetic Pathways Underlying Early Onset and Late Onset Neonatal Sepsis. A Pilot Study

Background: Neonatal sepsis is a systemic condition widely affecting preterm infants and characterized by pro-inflammatory and anti-inflammatory responses. However, its pathophysiology is not yet fully understood. Epigenetics regulates the immune system, and its alteration leads to the impaired immune response underlying sepsis. DNA methylation may contribute to sepsis-induced immunosuppression which, if persistent, will cause long-term adverse effects in neonates.

Objective: To analyze the methylome of preterm infants in order to determine whether there are DNA methylation marks that may shed light on the pathophysiology of neonatal sepsis.

Design: Prospective observational cohort study performed in the neonatal intensive care unit (NICU) of a tertiary care center.

Patients: Eligible infants were premature ≤32 weeks admitted to the NICU with clinical suspicion of sepsis. The methylome analysis was performed in DNA from blood using Infinium Human Methylation EPIC microarrays to uncover methylation marks.

Results: Methylation differential analysis revealed an alteration of methylation levels in genomic regions involved in inflammatory pathways which participate in both the innate and the adaptive immune response. Moreover, differences between early and late onset sepsis as compared to normal controls were assessed.

Conclusions: DNA methylation marks can serve as a biomarker for neonatal sepsis and even contribute to differentiating between early and late onset sepsis.

Cecal Slurry Injection in Neonatal and Adult Mice

Studying the pathophysiology of sepsis still requires animal models, and the mouse remains the most commonly used species. Here we discuss the "cecal slurry" (CS) model of polymicrobial, peritoneal sepsis and compare and contrast it to other commonly used methods. Among the different murine models of sepsis, cecal ligation and puncture (CLP), and not the CS, is often considered the "gold standard" to induce polymicrobial sepsis in laboratory animals. CLP is a well-described model involving a simple surgical procedure that closely mimics the clinical course of intra-abdominal sepsis. However, CLP may not be an option for experiments involving newborn pups, where the cecum is indistinguishable from small bowel, where differences in microbiome content may affect the experiment, or where surgical procedures/anesthesia exposure needs to be limited. An important alternative method is the CS model, involving the intraperitoneal injection of cecal contents from a donor animal into the peritoneal cavity of a recipient animal to induce polymicrobial sepsis. Furthermore, CS is an effective alternative model of intraperitoneal polymicrobial sepsis in adult mice and can now be considered the "gold standard" for experiments in neonatal mice.

Stratified Management for Bacterial Infections in Late Preterm and Term Neonates: Current Strategies and Future Opportunities Toward Precision Medicine

Bacterial infections remain a major cause of morbidity and mortality in the neonatal period. Therefore, many neonates, including late preterm and term neonates, are exposed to antibiotics in the first weeks of life. Data on the importance of inter-individual differences and disease signatures are accumulating. Differences that may potentially influence treatment requirement and success rate. However, currently, many neonates are treated following a "one size fits all" approach, based on general protocols and standard antibiotic treatment regimens. Precision medicine has emerged in the last years and is perceived as a new, holistic, way of stratifying patients based on large-scale data including patient characteristics and disease specific features. Specific to sepsis, differences in disease susceptibility, disease severity, immune response and pharmacokinetics and -dynamics can be used for the development of treatment algorithms helping clinicians decide when and how to treat a specific patient or a specific subpopulation. In this review, we highlight the current and future developments that could allow transition to a more precise manner of antibiotic treatment in late preterm and term neonates, and propose a research agenda toward precision medicine for neonatal bacterial infections.

Can a Presepsin (Scd14-St) Obtained from Tracheal Aspirate Be a Biomarker for Early- Onset Neonatal Sepsis

In absence of clear clinical signs and clear definition, neonatal sepsis is still one of the major cause of morbidity and mortality. Most researchs in past time was directional on finding new biomarkers with greater sensitivity and specificity in detection of neonatal sepsis. The aim of our study was to investigate if presepsin obtained from tracheal asprate in intubated newborns, can be a novel biomarker of systemic bacterial infection. Our ‘’case control’’ study included 60 newborns, 11 with suspected neonatal sepsis. Tracheal aspirate for examination was taken in the usual toilets, in aseptic conditions, by lavage with 2 ml of 0.9% NaCl in Mucus suction set. In the same day were mesured presepsin (blood), CRP, PCT, leukocytes and neutrophyls, as well as blood culture. Our research showed higher levels for PCT and presepsin (blood) in septic newborns, as well as in newborns with clinical signs of SIRS. Presepsin obtained from a tracheal aspirate had high score for septic newborns. As the coefficients of simple linear correlation showed, there was quantitative agreement between presepsin (blood) with presepsin (tracheal aspirate)- increase in the value of one leads to an increase in other. In conjunction with an already validated markers of infection, presepsin obtained from tracheal aspirate cam be turned on in diagnostic procedures.

Targeting the eCIRP/TREM-1 interaction with a small molecule inhibitor improves cardiac dysfunction in neonatal sepsis

Background

Neonatal sepsis and the associated myocardial dysfunction remain a leading cause of infant mortality. Extracellular cold-inducible RNA-binding protein (eCIRP) acts as a ligand of triggering receptor expressed on myeloid cells-1 (TREM-1). M3 is a small CIRP-derived peptide that inhibits the eCIRP/TREM-1 interaction. We hypothesize that the eCIRP/TREM-1 interaction in cardiomyocytes contributes to sepsis-induced cardiac dysfunction in neonatal sepsis, while M3 is cardioprotective.

Methods

Serum was collected from neonates in the Neonatal Intensive Care Unit (NICU). 5–7-day old C57BL/6 mouse pups were used in this study. Primary murine neonatal cardiomyocytes were stimulated with recombinant murine (rm) CIRP with M3. TREM-1 mRNA and supernatant cytokine levels were assayed. Mitochondrial oxidative stress, ROS, and membrane potential were assayed. Neonatal mice were injected with rmCIRP and speckle-tracking echocardiography was conducted to measure cardiac strain. Sepsis was induced by i.p. cecal slurry. Mouse pups were treated with M3 or vehicle. After 16 h, echocardiography was performed followed by euthanasia for tissue analysis. A 7-day survival study was conducted.

Results

Serum eCIRP levels were elevated in septic human neonates. rmCIRP stimulation of cardiomyocytes increased TREM-1 gene expression. Stimulation of cardiomyocytes with rmCIRP upregulated TNF-α and IL-6 in the supernatants, while this upregulation was inhibited by M3. Stimulation of cardiomyocytes with rmCIRP resulted in a reduction in mitochondrial membrane potential (MMP) while M3 treatment returned MMP to near baseline. rmCIRP caused mitochondrial calcium overload; this was inhibited by M3. rmCIRP injection impaired longitudinal and radial cardiac strain. Sepsis resulted in cardiac dysfunction with a reduction in cardiac output and left ventricular end diastolic diameter. Both were improved by M3 treatment. Treatment with M3 attenuated serum, cardiac, and pulmonary levels of pro-inflammatory cytokines compared to vehicle-treated septic neonates. M3 dramatically increased sepsis survival.

Conclusions

Inhibition of eCIRP/TREM-1 interaction with M3 is cardioprotective, decreases inflammation, and improves survival in neonatal sepsis.

Trial registration Retrospectively registered.

miRNA-23b as a biomarker of culture-positive neonatal sepsis

BACKGROUND

Neonatal sepsis remains an important cause of morbidity and mortality. The ability to quickly and accurately diagnose neonatal sepsis based on clinical assessments and laboratory blood tests remains difficult, where haemoculture is the gold standard for detecting bacterial sepsis in blood culture. It is also very difficult to study because neonatal samples are lacking.

METHODS

Forty-eight newborns suspected of sepsis admitted to the Neonatology Department of the Mother-Child Specialized Hospital of Tlemcen. From each newborn, a minimum of 1-2 ml of blood was drawn by standard sterile procedures for blood culture. The miRNA-23b level in haemoculture was evaluated by RT-qPCR.

RESULTS

miR-23b levels increased in premature and full-term newborns in early onset sepsis (p < 0.001 and p < 0.005 respectively), but lowered in late onset sepsis in full-term neonates (p < 0.05) compared to the respective negative controls. miR-23b levels also increased in late sepsis in the negative versus early sepsis negative controls (p < 0.05). miR-23b levels significantly lowered in the newborns who died from both sepsis types (p < 0.0001 and p < 0.05 respectively). In early sepsis, miR-23b and death strongly and negatively correlated (correlation coefficient = - 0.96, p = 0.0019). In late sepsis, miRNA-23b and number of survivors (correlation coefficient = 0.70, p = 0.506) positively correlated.

CONCLUSIONS

Lowering miR-23b levels is an important factor that favours sepsis development, which would confirm their vital protective role, and strongly suggest that they act as a good marker in molecular diagnosis and patient monitoring.

Preterm neonatal immunology at the intestinal interface

Fetal and neonatal development represents a critical window for setting a path toward health throughout life. In this review, we focus on intestinal immunity, how it develops, and its implications for subsequent neonatal diseases. We discuss maternal nutritional and environmental exposures that dictate outcomes for the developing fetus. Although still controversial, there is evidence in support of an in utero microbiome. Specific well-intentioned and routine applications of antibiotics, steroids, and surgical interventions implemented before, during, and after birth skew the neonate towards pro-inflammatory dysbiosis. Shortly after birth, a consortium of maternal and environmentally derived bacteria, through cross-talk with the developing host immune system, takes center stage in developing or disrupting immune homeostasis at the intestinal interface. We also examine subsequent immunological cross-talks, which involve neonatal myeloid and lymphoid responses, and their potential impacts on health and disease such as necrotizing enterocolitis and sepsis, especially critical disease entities for the infant born preterm.

Antibiotic prescribing in neonatal sepsis: an Australian nationwide survey

OBJECTIVE

To evaluate quality and variation in antibiotic prescribing for neonatal sepsis.

DESIGN

We analysed prescribing in hospitalised neonates using the National Antimicrobial Prescribing Survey in Australian neonates from 1 January 2014 to 31 December 2018.

SETTING

Data from antibiotic point prevalence surveys performed in hospitals, ranging from rural hospitals to tertiary paediatric and maternity hospitals within Australia.

PATIENTS

Admitted neonates <28 days of age from participating hospitals.

MAIN OUTCOME MEASURES

Variation and appropriateness in prescribing for neonatal sepsis and variation in dosing for gentamicin and benzylpenicillin across hospitals.

RESULTS

A total of 415 prescriptions among 214 neonates from 39 different hospitals were included. The majority of prescriptions (342, 82.4%) were for neonates <7 days of age. The most commonly prescribed antibiotics were gentamicin and benzylpenicillin, with 323 (77.8%) prescriptions. Dosing variability was substantial, with doses ranging from 2 to 8 mg/kg for gentamicin (median 5 mg/kg, IQR 4-5) and from 45 to 72 mg/kg for benzylpenicillin (median 60 mg/kg, IQR 50-60), although only 13 (3.2%) and 19 (4.6%) prescriptions were locally assessed as inappropriate or non-compliant with guidelines, respectively. At time of audit, 22% of antibiotics had been given for more than 48 hours and 9% more than 72 hours, although microbiologically confirmed infection was documented in only nine (4.2%) neonates.

CONCLUSIONS

Prescribing for neonatal sepsis was dominated by use of benzylpenicillin and gentamicin with substantial variation in dosing. A small minority had culture-confirmed infection. Efforts to standardise antibiotic dosing and duration for suspected neonatal sepsis are recommended.

Advantages and Limitations of the Neonatal Immune System

During early post-natal life, neonates must adjust to the transition from the sheltered intra-uterine environment to the microbe-laden external world, wherein they encounter a constellation of antigens and the colonization by the microbiome. At this vulnerable stage, neonatal immune responses are considered immature and present significant differences to those of adults. Pertinent to innate immunity, functional and quantitative deficiencies in antigen-presenting cells and phagocytes are often documented. Exposure to environmental antigens and microbial colonization is associated with epigenetic immune cell reprogramming and activation of effector and regulatory mechanisms that ensure age-depended immune system maturation and prevention of tissue damage. Moreover, neonatal innate immune memory has emerged as a critical mechanism providing protection against infectious agents. Still, in neonates, inexperience to antigenic exposure, along with enhancement of tissue-protective immunosuppressive mechanisms are often associated with severe immunopathological conditions, including sepsis and neurodevelopmental disorders. Despite significant advances in the field, adequate vaccination in newborns is still in its infancy due to elemental restrictions associated also with defective immune responses. In this review, we provide an overview of neonatal innate immune cells, highlighting phenotypic and functional disparities with their adult counterparts. We also discuss the effects of epigenetic modifications and microbial colonization on the regulation of neonatal immunity. A recent update on mechanisms underlying dysregulated neonatal innate immunity and linked infectious and neurodevelopmental diseases is provided. Understanding of the mechanisms that augment innate immune responsiveness in neonates may facilitate the development of improved vaccination protocols that can protect against pathogens and organ damage.

C23, an oligopeptide derived from cold-inducible RNA-binding protein, suppresses inflammation and reduces lung injury in neonatal sepsis

INTRODUCTION

Neonatal sepsis remains a leading cause of infant mortality. Cold-inducible RNA binding protein (CIRP) is an inflammatory mediator that induces TNF-α production in macrophages. C23 is a CIRP-derived peptide that blocks CIRP from binding its receptor. We therefore hypothesized that treatment with C23 reduces systemic inflammation and protects the lungs in neonatal sepsis.

METHODS

Sepsis was induced in C56BL/6 mouse pups (5-7 days) by intraperitoneal injection of adult cecal slurry (0.525 mg/g body weight, LD₁₀₀). One hour later pups received retroorbital injection of C23 (8 mg/kg) or vehicle (normal saline). Ten hours after sepsis induction, blood and tissues were collected for analysis.

RESULTS

C23 treatment resulted in a 58% and 69% reduction in serum levels of proinflammatory cytokines IL-6 and IL-1β, respectively, and a 40% and 45% reduction of AST and LDH, as compared to vehicle-treated septic pups. In the lungs, C23 treatment reduced expression of cytokines IL-6 and IL-1β by 78% and 74%. In addition, the mRNA level of neutrophil chemoattractants KC and MIP-2 was reduced by 84% and 74%, respectively. These results corresponded to a reduction in histologic lung injury score. Vehicle-treated pups scored 0.49 ± 0.19, while C23 treatment reduced scores to 0.29 ± 0.12 (p < 0.05; Max = 1). Apoptosis in the lungs, measured by TUNEL assay, was also decreased by 53% with C23 treatment (p < 0.05).

CONCLUSIONS

Inhibition of CIRP with C23 treatment is protective in septic neonatal mice as demonstrated by reduced inflammatory markers systemically and in the lung. Therefore, C23 has promising therapeutic potential in treatment of neonatal sepsis.

LEVEL OF EVIDENCE

Level I.

Super-Low Dose Lipopolysaccharide Dysregulates Neutrophil Migratory Decision-Making

Neutrophils are the first responders to infection and play a pivotal role in many inflammatory diseases, including sepsis. Recent studies have shown that lipopolysaccharide (LPS), a classical pattern recognition molecule, dynamically programs innate immune responses. In this study, we show that pre-treatment with super-low levels of LPS [1 ng/mL] significantly dysregulate neutrophil migratory phenotypes, including spontaneous migration and altering neutrophil decision-making. To quantify neutrophil migratory decision-making with single-cell resolution, we developed a novel microfluidic competitive chemotaxis-chip (μC³) that exposes cells in a central channel to competing chemoattractant gradients. In this reductionist approach, we use two chemoattractants: a pro-resolution (N-Formyl-Met-Leu-Phe, fMLP) and pro-inflammatory (Leukotriene B₄, LTB₄) chemoattractant to model how a neutrophil makes a decision to move toward an end target chemoattractant (e.g., bacterial infection) vs. an intermediary chemoattractant (e.g., inflammatory signal). We demonstrate that naïve neutrophils migrate toward the primary end target signal in higher percentages than toward the secondary intermediary signal. As expected, we found that training with high dose LPS [100 ng/mL] influences a higher percentage of neutrophils to migrate toward the end target signal, while reducing the percentage of neutrophils that migrate toward the intermediary signal. Surprisingly, super-low dose LPS [1 ng/mL] significantly changes the ratios of migrating cells and an increased percentage of cells migrate toward the intermediary signal. Significantly, there was also an increase in the numbers of spontaneously migrating neutrophils after treatment with super-low dose LPS. These results shed light onto the directional migratory decision-making of neutrophils exposed to inflammatory training signals. Understanding these mechanisms may lead to the development of pro-resolution therapies that correct the neutrophil compass and reduce off-target organ damage.

Vascular Endothelium in Neonatal Sepsis: Basic Mechanisms and Translational Opportunities

Neonatal sepsis remains a major health issue worldwide, especially for low-birth weight and premature infants, with a high risk of death and devastating sequelae. Apart from antibiotics and supportive care, there is an unmet need for adjunctive treatments to improve the outcomes of neonatal sepsis. Strong and long-standing research on adult patients has shown that vascular endothelium is a key player in the pathophysiology of sepsis and sepsis-associated organ failure, through a direct interaction with pathogens, leukocytes, platelets, and the effect of soluble circulating mediators, in part produced by endothelial cells themselves. Despite abundant evidence that the neonatal immune response to sepsis is distinct from that of adults, comparable knowledge on neonatal vascular endothelium is much more limited. Neonatal endothelial cells express lower amounts of adhesion molecules compared to adult ones, and present a reduced capacity to neutralize reactive oxygen species. Conversely, available evidence on biomarkers of endothelial damage in neonates is not as robust as in adult patients, and endothelium-targeted therapeutic opportunities for neonatal sepsis are almost unexplored. Here, we summarize current knowledge on the structure of neonatal vascular endothelium, its interactions with neonatal immune system and possible endothelium-targeted diagnostic and therapeutic tools for neonatal sepsis. Furthermore, we outline areas of basic and translational research worthy of further study, to shed light on the role of vascular endothelium in the context of neonatal sepsis.

Regulatory role of miRNA-26a in neonatal sepsis

The present study aimed to investigate the expression of microRNA (miRNA) 26a in blood mononuclear cells and serum in neonatal sepsis, as well as its role in the disease pathogenesis. In total 28 cases of neonatal sepsis were included in the study. The mRNA expression levels of miRNA-26a and interleukin (IL)-6 in the blood mononuclear cells and serum samples were detected by reverse transcription-quantitative polymerase chain reaction. The protein expression of IL-6 was detected by western blot analysis and ELISA. The in vitro septic environment was simulated by lipopolysaccharide (LPS) in THP-1 cells, and the expression of miRNA-26a and IL-6 were determined. Interaction between miRNA-26a and IL-6 was confirmed by a dual-luciferase reporter assay. Compared with the control group, the mRNA and protein expression levels of IL-6 in the blood mononuclear cells and serum samples from the neonates with sepsis were significantly elevated, while the expression of miRNA-26a was significantly decreased. In addition, similar results were observed in the LPS-induced septic models in THP-1 cells. Furthermore, the results of the dual-luciferase reporter assay demonstrated that IL-6 was the direct target of miRNA-26a. The expression of IL-6 was significantly upregulated in the blood mononuclear cells and serum in neonatal sepsis, which may be associated with the downregulation of miRNA-26a. miRNA-26a may regulate the disease pathogenesis and immune responses.

Polarized Entry of Human Parechoviruses in the Airway Epithelium

Human parechoviruses (HPeVs), a poorly studied genus within the Picornaviridae family, are classified into 19 genotypes of which HPeV1 and HPeV3 are the most often detected. HPeV1 VP1 C terminus contains an arginine-glycine-aspartic acid (RGD) motif and has been shown to depend on the host cell surface αV integrins (αV ITGs) and heparan sulfate (HS) for entry. HPeV3 lacks this motif and the receptors remain unknown. HPeVs can be detected in patient nasopharyngeal and stool samples, and infection is presumed to occur after respiratory or gastro-intestinal transmission. HPeV pathogenesis is poorly understood as there are no animal models and previous studies have been conducted in immortalized monolayer cell cultures which do not adequately represent the characteristics of human tissues. To bridge this gap, we determined the polarity of infection, replication kinetics, and cell tropism of HPeV1 and HPeV3 in the well-differentiated human airway epithelial (HAE) model. We found the HAE cultures to be permissive for HPeVs. Both HPeV genotypes infected the HAE preferentially from the basolateral surface while the progeny virus was shed toward the apical side. Confocal microscopy revealed the target cell type to be the p63⁺ basal cells for both viruses, αV ITG and HS blocking had no effect on the replication of either virus, and transcriptional profiling suggested that HPeV3 infection induced stronger immune activation than HPeV1. Genotype-specific host responses may contribute to the differences in pathogenesis and clinical outcomes associated with HPeV1 and HPeV3.

Etiologic and Pathogenic Perinatal Factors for the Development of Intrauterine Infections in Newborns (Review)

For many decades, the world community’s efforts have been aimed at reducing the neonatal and infant mortality from intrauterine infections. In 1990, the United Nations and the World Health Organization set out the priority of decreasing children mortality by 2015 году. In spite of impressive success in newborn treatment, mortality due to sepsis decreases slowly; when survive, postnatal children develop central nervous system impairments of different level of severity. In the recent decade, new data have emerged concerning the methods of intrauterine infections prophylaxis, diagnosis, and treatment. The purpose of the review is to present data concerning specifics of pregnancy course when infections develop, contemporary diagnostic methods including studies of interleukins, placenta morphology, allelic genes, and to reflect the current approach to the treatment of intrauterine infections in newborns. 

Impact of toll-like receptor 4 stimulation on human neonatal neutrophil spontaneous migration, transcriptomics, and cytokine production

Neonates rely on their innate immune system, and neutrophils in particular, to recognize and combat life-threatening bacterial infections. Pretreatment with lipopolysaccharide (LPS), a toll-like receptor (TLR) 4 agonist, improves survival to polymicrobial sepsis in neonatal mice by enhancing neutrophil recruitment. To understand the response of human neonatal neutrophils to TLR4 stimulation, ex vivo spontaneous neutrophil migration, neutrophil transcriptomics, and cytokine production in the presence and absence of LPS were measured directly from whole blood of adults, term neonates, and preterm neonates. Spontaneous neutrophil migration was measured on novel microfluidic devices with time-lapse imaging for 10 h. Genome-wide neutrophil transcriptomics and plasma cytokine concentrations were also determined. Preterm neonates had significantly fewer spontaneously migrating neutrophils at baseline, and both term and preterm neonates had decreased neutrophil velocity, compared to adults. In the presence of LPS stimulation, the number of spontaneously migrating neutrophils was reduced in preterm neonates compared to term neonates and adults. Neutrophil velocity was not significantly different among groups with LPS stimulation. Preterm neonates upregulated expression of genes associated with the recruitment and response of neutrophils following LPS stimulation, but failed to upregulate the expression of genes associated with antimicrobial and antiviral responses. Plasma levels of IL-1β, IL-6, IL-8, MIP-1α, and TNF-α increased in response to LPS stimulation in all groups, but IL-10 was increased only in term and preterm neonates. In conclusion, age-specific changes in spontaneous neutrophil migration counts are not affected by LPS despite changes in gene expression and cytokine production.

KEY MESSAGES

Preterm neonates have reduced spontaneous neutrophil migration compared to term neonates and adults in the absence and presence of TLR4 stimulation. Preterm and term neonates have reduced neutrophil velocities compared to adults in the absence of TLR4 stimulation but no difference in the presence of TLR4 stimulation. Unique transcriptomic response to TLR4 stimulation is observed in neutrophils from preterm neonates, term neonates, and adults. TLR4 stimulation produces an age-specific cytokine response.

Outgrowing the Immaturity Myth: The Cost of Defending From Neonatal Infectious Disease

Newborns suffer high rates of mortality due to infectious disease-this has been generally regarded to be the result of an "immature" immune system with a diminished disease-fighting capacity. However, the immaturity dogma fails to explain (i) greater pro-inflammatory responses than adults in vivo and (ii) the ability of neonates to survive a significantly higher blood pathogen burden than of adults. To reconcile the apparent contradiction of clinical susceptibility to disease and the host immune response findings when contrasting newborn to adult, it will be essential to capture the entirety of available host-defense strategies at the newborn's disposal. Adults focus heavily on the disease resistance approach: pathogen reduction and elimination. Newborn hyperactive innate immunity, sensitivity to immunopathology, and the energetic requirements of growth and development (immune and energy costs), however, preclude them from having an adult-like resistance response. Instead, newborns also may avail themselves of disease tolerance (minimizing immunopathology without reducing pathogen load), as a disease tolerance approach provides a counterbalance to the dangers of a heightened innate immunity and has lower-associated immune costs. Further, disease tolerance allows for the establishment of a commensal bacterial community without mounting an unnecessarily dangerous immune resistance response. Since disease tolerance has its own associated costs (immune suppression leading to unchecked pathogen proliferation), it is the maintenance of homeostasis between disease tolerance and disease resistance that is critical to safe and effective defense against infections in early life. This paradigm is consistent with nearly all of the existing evidence.

Hongteng decoction combined with antibiotic therapy for treatment of periappendiceal abscess: Therapeutic effect and possible immune mechanism

AIM

To evaluate the therapeutic effect of combined Hongteng decoction and antibiotic therapy in the treatment of periappendiceal abscess and to explore the possible immune mechanism.

METHODS

Sixty-eight patients with periappendiceal abscess treated at the Department of General Surgery of Beilun District People's Hospital between January 2014 and April 2017 were randomly divided into two groups to receive either routine antibiotic therapy alone (n = 31) or combined Hongteng decoction and routine antibiotic therapy (n = 37). Time to disappearance of symptoms and signs, length of hospital stay, the rate of periappendiceal abscess disappearance 10 d after treatment, and the rate of percutaneous puncture and catheter drainage were compared between the two groups. Serum levels of Interleukin-6 (IL-6), IL-10, and tumor necrosis factor α (TNF-α) were assessed by enzyme-linked immunosorbent assay before treatment and 4 d and 8 d after treatment.

RESULTS

Time to disappearance of symptoms and signs and length of hospital stay in the combination group were significantly shorter than those in the routine antibiotic group (P < 0.05). The rate of periappendiceal abscess disappearance 10 d after treatment in the combination group was significantly higher than that in the routine antibiotic group (91.89% vs 70.97%, P < 0.05). The rate of percutaneous puncture and catheter drainage in the combination group was significantly lower than that in the routine antibiotic group (5.41% vs 22.58%, P < 0.05). The levels of IL-6 and TNF-α in both groups after treatment were significantly lower than those before treatment (P < 0.01), and these levels at 4 d and 8 d after treatment were significantly lower in the combination group than in the routine antibiotic group (P < 0.05). The level of IL-10 at 8 d after treatment in the routine antibiotic group was significantly higher than that before treatment and that in the combination group at the same time point (P < 0.05).

CONCLUSION

The combination of Hongteng decoction and antibiotic therapy can effectively promote the absorption of abscess, shorten hospital stay, and result in a significant therapeutic effect by reducing the serum levels of IL-6 and TNF-α in patients with periappendiceal abscess.

Neutrophil chemotaxis and transcriptomics in term and preterm neonates

Neutrophils play a crucial role in combating life-threatening bacterial infections in neonates. Previous studies investigating neonatal cell function have been limited because of restricted volume sampling. Here, using novel microfluidic approaches, we provide the first description of neutrophil chemotaxis and transcriptomics from whole blood of human term and preterm neonates, as well as young adults. Ex vivo percent cell migration, neutrophil velocity, and directionality to N-formylmethionyl-leucyl-phenylalanine were measured from whole blood using time-lapse imaging of microfluidic chemotaxis. Genome-wide expression was also evaluated in CD66b⁺ cells using microfluidic capture devices. Neutrophils from preterm neonates migrated in fewer numbers compared to term neonates (preterm 12.3%, term 30.5%, P = 0.008) and at a reduced velocity compared to young adults (preterm 10.1 μm/min, adult 12.7 μm/min, P = 0.003). Despite fewer neutrophils migrating at slower velocities, neutrophil directionality from preterm neonates was comparable to adults and term neonates. 3607 genes were differentially expressed among the 3 groups (P < 0.001). Differences in gene expression between neutrophils from preterm and term neonates were consistent with reduced pathogen recognition and antimicrobial activity but not neutrophil migration, by preterm neonates. In summary, preterm neonates have significant disturbances in neutrophil chemotaxis compared to term neonates and adults, and these differences in phenotype appear at the transcriptional level to target inflammatory pathways in general, rather than in neutrophil migration and chemotaxis.

Program Cell Death Receptor-1-Mediated Invariant Natural Killer T-Cell Control of Peritoneal Macrophage Modulates Survival in Neonatal Sepsis

We have shown that invariant natural killer T (iNKT) cells mediate sepsis-induced end-organ changes and immune responses, including macrophage bacterial phagocytosis, a finding regulated by the check point protein program cell death receptor-1 (PD-1). Furthermore, PD-1 mediates mortality in both adult and neonatal murine sepsis as well as in surgical patients. Given our previous findings, we hypothesize that iNKT cells will also modulate neonatal sepsis survival, and that this effect is regulated in part through PD-1. We utilized a polymicrobial intra-peritoneal cecal slurry (CS) sepsis model in wild type (WT), iNKT^−/− or PD-1^−/− 5–7 day old neonatal pups. Typically, tissues were harvested at 24 h for various bioassays/histology and, in some cases, survival was assessed for up to 7 days. Interestingly, similar to what we recently reported for PD-1^−/− mice following CS, iNKT^−/−-deficient animals exhibit a markedly improved survival vs. WT. Histologically, minor alterations in liver architectural, which were noted in WT pups, were attenuated in both iNKT^−/− and PD-1^−/− pups. Following CS, PECAM-1 expression was unchanged in the WT pups but increased in both iNKT^−/− and PD-1^−/− pups. In WT, following CS the emergence of a Ly6C^low subpopulation was noted among the influxed peritoneal macrophage population. Conversely, within iNKT^−/− pups, there were fewer peritoneal macrophages and a greater percentage of Ly6C^high macrophages. We show not only a key role for iNKT cells in affecting end-organ damage as well as alterations in phagocytes phenotypes in neonatal sepsis but that this iNKT cell mediated effect is driven by the central checkpoint protein PD-1.

Impact of Early-Life Exposures to Infections, Antibiotics, and Vaccines on Perinatal and Long-term Health and Disease

Essentially, all neonates are exposed to infections, antibiotics, or vaccines early in their lives. This is especially true for those neonates born underweight or premature. In contrast to septic adults and children who are at an increased risk for subsequent infections, exposure to infection during the neonatal period is not associated with an increased risk of subsequent infection and may be paradoxically associated with reductions in late-onset sepsis (LOS) in the most premature infants. Perinatal inflammation is also associated with a decreased incidence of asthma and atopy later in life. Conversely, septic neonates are at increased risk of impaired long-term neurodevelopment. While the positive effects of antibiotics in the setting of infection are irrefutable, prolonged administration of broad-spectrum, empiric antibiotics in neonates without documented infection is associated with increased risk of LOS, necrotizing enterocolitis, or death. Vaccines provide a unique opportunity to prevent infection-associated disease; unfortunately, vaccinations have been largely unsuccessful when administered in the first month of life with the exception of vaccines against hepatitis B and tuberculosis. Future vaccines will require the use of novel adjuvants to overcome this challenge. This review describes the influence of infections, antibiotics, and vaccines during the first days of life, as well as the influence on future health and disease. We will also discuss potential immunomodulating therapies, which may serve to train the preterm immune system and reduce subsequent infectious burden without subjecting neonates to the risks accompanied by virulent pathogens.