Intrauterine growth restriction and the innate immune system in preterm infants of ≤32 weeks gestation

Intrauterine growth restriction in piglets modulates postnatal immune function and hepatic transcriptional responses independently of energy intake

Introduction: Insufficient prenatal nutrition can affect fetal development and lead to intrauterine growth restriction (IUGR). The aim of this study was to investigate hepatic transcriptional responses and innate immune function in piglets suffering from IUGR compared to normal-sized piglets at 3 days of age and explore whether the provision of an energy-rich supplement at birth could modulate these parameters. Methods: A total of 68 piglets were included in the study. Peripheral blood mononuclear cells were harvested for LPS stimulation, and organs were harvested post-mortem to quantify relative weights. Liver tissue was utilized for RNA sequencing coupled with gene-set enrichment analysis. Results: IUGR resulted in increased expression of genes such as PDK4 and substantial alterations in transcriptional pathways related to metabolic activity (e.g., citric acid and Krebs cycles), but these changes were equivalent in piglets given an energy-rich supplement or not. Transcriptomic analysis and serum biochemistry suggested altered glucose metabolism and a shift toward oxidation of fatty acids. IUGR piglets also exhibited suppression of genes related to innate immune function (e.g., CXCL12) and pathways related to cell proliferation (e.g., WNT and PDGF signaling). Moreover, they produced less IL-1β in response to LPS stimulation and had lower levels of blood eosinophils than normal-sized piglets. Discussion: Taken together, our results indicate that IUGR results in early-life alterations in metabolism and immunity that may not be easily restored by the provision of exogenous energy supplementation.

Association between prenatal socioeconomic disadvantage, adverse birth outcomes, and inflammatory response at birth

Prenatal socioeconomic disadvantage is associated with inflammation in mid- to late-life, yet whether a pro-inflammatory phenotype is present at birth and the role of adverse birth outcomes in this pathway remains unclear. We utilized data on prenatal socioeconomic disadvantage at the individual- (i.e., mother's and father's education level, insurance type, marital status, and Women, Infants, and Children benefit receipt) and census-tract level as well as preterm (< 37 weeks gestation) and small-for-gestational-age (SGA) (i.e., < 10th percentile of sex-specific birth weight for gestational age) birth status, and assessed inflammatory markers (i.e., C-reactive protein, serum amyloid p, haptoglobin, and α-2 macroglobulin) in archived neonatal bloodspots from a Michigan population-based cohort of 1000 neonates. Continuous latent variables measuring individual- and combined individual- and neighborhood-level prenatal socioeconomic disadvantage were constructed and latent profile analysis was used to create a categorical inflammatory response variable (high versus low) based on continuous inflammatory marker levels. Structural equation models were used to estimate the total and direct effect of prenatal socioeconomic disadvantage on the inflammatory response at birth as well as indirect effect via preterm or SGA birth (among term neonates only), adjusting for mother's age, race/ethnicity, body mass index, smoking status, comorbidities, and antibiotic use/infection as well as grandmother's education level. There was a statistically significant total effect of both individual- and combined individual- and neighborhood-level prenatal socioeconomic disadvantage on high inflammatory response among all neonates as well as among term neonates only, and a positive but not statistically significant direct effect in both groups. The indirect effects via preterm and SGA birth were both negative, but not statistically significant. Our findings suggest prenatal socioeconomic disadvantage contributes to elevated neonatal inflammatory response, but via pathways outside of these adverse birth outcomes.

Neonatal hematological parameters: the translational aspect of developmental hematopoiesis

Hematopoiesis is a process constantly evolving from fetal life through adulthood. Neonates present with qualitative and quantitative differences in hematological parameters compared to older children and adults, reflecting developmental changes in hematopoiesis correlated with gestational age. Such differences are more intense for preterm and small-for-gestational-age neonates or neonates with intrauterine growth restriction. This review article is aimed at describing the hematologic differences among neonatal subgroups and the major underlying pathogenic mechanisms. Issues that should be taken into account when interpreting neonatal hematological parameters are also highlighted.

Nomogram for predicting fulminant necrotizing enterocolitis

BACKGROUND

Fulminant necrotizing enterocolitis (FNEC) is the most serious subtype of NEC and has a high mortality rate and a high incidence of sequelae. Onset prediction can help in the establishment of a customized treatment strategy. This study aimed to develop and evaluate a predictive nomogram for FNEC.

METHODS

We conducted a retrospective observation to study the clinical data of neonates diagnosed with NEC (Bell stage ≥ IIB). Neonates were divided into the FNEC and NEC groups. A multivariate logistic regression model was used to construct the nomogram model. The performance of the nomogram was assessed using area under the curve, calibration analysis, and decision curve analysis.

RESULTS

A total of 206 neonate cases were included, among which 40 (19.4%) fulfilled the definition of FNEC. The identified predictors were assisted ventilation after NEC onset; shock at NEC onset; feeding volumes before NEC onset; neutrophil counts on the day of NEC onset; and neutrophil, lymphocyte, and monocyte counts on day 1 after NEC onset. The nomogram exhibited good discrimination, with an area under the receiver operating characteristic curve of 0.884 (95% CI 0.825-0.943). The predictive model was well calibrated. Decision curve analysis confirmed the clinical usefulness of this nomogram.

CONCLUSION

A nomogram with a potentially effective application was developed to facilitate the individualized prediction of FNEC, with the hope of providing further direction for the early diagnosis of FNEC and timing of intervention.

Mean Platelet Volume and Mean Platelet Volume/Platelet Count Ratio Are Predictors of Late-Onset Sepsis in Preterm Infants: A Case-Control Study

Objective: Our aim was to assess mean platelet volume (MPV) and mean platelet volume to platelet count ratio (MPR) in the setting of late-onset sepsis (LOS) and their association with the type of bacteria causing LOS. Study design: The MPV and MPR levels were obtained at the onset of LOS and then assessed in intra/inter group analyses in preterm infants. Results: Overall, 136 preterm infants were enrolled. The MPV and MPR levels were higher during a LOS event (P < 0.001). A MPV cutoff of >9.2 was related with a sensitivity of 63% and a specificity of 73% for predicting LOS (P < 0.001). A MPR cutoff of >0.15 was related with a sensitivity of 88% and a specificity of 63% for predicting gram negative LOS (P < 0.001). Conclusion: Elevated MPV values and MPR ratios may be helpful in assessing LOS.

The Impact of Heat Stress on Immune Status of Dairy Cattle and Strategies to Ameliorate the Negative Effects

Heat stress (HS) is well known to influence animal health and livestock productivity negatively. Heat stress is a multi-billion-dollar global problem. It impairs animal performance during summer when animals are exposed to high ambient temperatures, direct and indirect solar radiations, and humidity. While significant developments have been achieved over the last few decades to mitigate the negative impact of HS, such as physical modification of the environment to protect the animals from direct heat, HS remains a significant challenge for the dairy industry compromising dairy cattle health and welfare. In such a scenario, it is essential to have a thorough understanding of how the immune system of dairy cattle responds to HS and identify the variable responses among the animals. This understanding could help to identify heat-resilient dairy animals for breeding and may lead to the development of climate resilient breeds in the future to support sustainable dairy cattle production. There are sufficient data demonstrating the impact of increased temperature and humidity on endocrine responses to HS in dairy cattle, especially changes in concentration of hormones like prolactin and cortisol, which also provide an indication of the likely im-pact on the immune system. In this paper, we review the recent research on the impact of HS on immunity of calves during early life to adult lactating and dry cows. Additionally, different strategies for amelioration of negative effects of HS have been presented.

Preterm infants at low risk for early-onset sepsis differ in early fecal microbiome assembly

Antibiotics are administered near-universally to very low birth weight (VLBW) infants after birth for suspected early-onset sepsis (EOS). We previously identified a phenotypic group of VLBW infants, referred to as low-risk for EOS (LRE), whose risk of EOS is low enough to avoid routine antibiotic initiation. In this cohort study, we compared 18 such infants with 30 infants categorized as non-LRE to determine if the lower risk of pathogen transmission at birth is accompanied by differences in microbiome acquisition and development. We did shotgun metagenomic sequencing of 361 fecal samples obtained serially. LRE infants had a higher human-to-bacterial DNA ratio than non-LRE infants in fecal samples on days 1-3 after birth, confirming lower bacterial acquisition among LRE infants. The microbial diversity and composition in samples from days 4-7 differed between the groups with a predominance of Staphylococcus epidermidis in LRE infants and Enterobacteriaceae sp. in non-LRE infants. Compositional differences were congruent with the distribution of virulence factors and antibiotic resistant genes. After the first week, the overall composition was similar, but changes in relative abundance for several taxa with increasing age differed between groups. Of the nine late-onset bacteremia episodes, eight occurred in non-LRE infants. Species isolated from the blood culture was detected in the pre-antibiotic fecal samples of the infant for all episodes, though these species were also found in infants without bacteremia. In conclusion, LRE infants present a distinct pattern of microbiome development that is aligned with their low risk for EOS. Further investigation to determine the impact of these differences on later outcomes such as late-onset bacteremia is warranted.

Birth Weight < 3rd Percentile Prediction Using Additional Biochemical Markers-The Uric Acid Level and Angiogenesis Markers (sFlt-1, PlGF)-An Exploratory Study

(1) Aim: Ultrasound is the gold standard for assessing fetal growth disorders. The relationship between high sFlt-1/PlGF scores and LBW (low birth weight) was described. In this study, we attempted to assess whether uric acid could be used as a secondary marker in estimating the pregnancy risk associated with LBW. (2) Material and methods: 665 pregnant women with a suspected or confirmed form of placental insufficiency were enrolled. In each of the patients, sFlt-1 and PlGF and uric acid levels were determined. Patients were divided into two groups according to birth weight below and above the third percentile for the given gestational age with the criteria of the neonatal definition of FGR (fetal growth restriction). (3) Results: A significant negative correlation between neonatal birth weight and the uric acid level across the entire study group was observed. We found a significant negative correlation between neonatal birth weight and the uric acid level with birth weights < 3rd percentile. (4) Conclusions: There is a significant link between the uric acid concentration and LBW in the group with placental insufficiency. Uric acid can improve the prediction of LBW. An algorithm for LBW prognosis that makes use of biophysical (ultrasound) and biochemical (uric acid level, angiogenesis markers) parameters yields better results than using these parameters separately from each other.

Serial Measurement of Interleukin-6 Enhances Chance to Exclude Early-Onset Sepsis in Very Preterm Infants

The aim of this retrospective study was to evaluate the reliability of peak interleukin-6 (IL-6) level within 24 hours after delivery as a predictor for early-onset sepsis (EOS) in very preterm neonates. Interleukin-6 was assessed at 2 hours and at 12 to 24 hours after delivery. The highest level was considered a peak value. The definition of EOS was based on positive blood culture and clinical signs of infection or negative blood culture, clinical signs of infection, and C-reactive protein >10 mg/L. Among 445 enrolled infants, 53 developed EOS. A peak IL-6 level of more than 200 ng/L had a sensitivity of 89% and specificity of 77% for the presence of EOS. The negative predictive value was 98%. Receiver operating characteristics curve had area under the curve of 0.92. Peak IL-6 is a reliable marker of systemic inflammatory response and might be useful to exclude EOS within the first 24 hours.

Comparative Analysis of Gene Expression Profiles in the Adipose Tissue of Obese Adult Mice With Rapid Infantile Growth After Undernourishment In Utero

Rapid infantile growth (RG) markedly increases the risk of obesity and metabolic disorders in adulthood, particularly among neonates born small. To elucidate the molecular mechanisms by which RG following undernourishment in utero (UN) contributes to the deterioration of adult fat deposition, we developed a UN mouse model using maternal energy restriction, followed by RG achieved by adjustments to 4 pups per litter soon after birth. A high-fat diet (HFD) was fed to weaned pups treated or not (Veh) with tauroursodeoxycholic acid (TU). UN-RG pups showed the deterioration of diet-induced obesity and fat deposition, which was ameliorated by TU. We performed a microarray analysis of epididymal adipose tissue and two gene enrichment analyses (NN-Veh vs UN-RD-Veh and UN-RG-Veh vs UN-RG-TU). The results obtained identified 4 common gene ontologies (GO) terms of inflammatory pathways. In addition to the inflammatory characteristics of 4 GO terms, the results of heatmap and principal component analyses of the representative genes from 4 GO terms, genes of interest (GOI; Saa3, Ubd, S100a8, Hpx, Casp1, Agt, Ptgs2) selected from the 4 GO terms, and immunohistochemistry of macrophages collectively suggested the critical involvement of inflammation in the regulation of fat deposition in the responses to UN and TU. Therefore, the present results support the 'Developmental Origins of Metaflammation', the last word of which was recently proposed by the concept of metabolic disorders induced by low-grade systemic inflammation.

Infant Formula Based on Milk Fat Affects Immune Development in Both Normal Birthweight and Fetal Growth Restricted Neonatal Piglets

Infant formulas offer an alternative to breast milk for both normal birth weight (NBW) and immunocompromised intrauterine growth restricted (IUGR) infants. Although the lipid fraction in formulas is often derived from vegetable oils, it is unclear if this alters immunological outcomes relative to milk fats or whether these effects differ between IUGR and NBW infants. We hypothesized that replacing vegetable oil with bovine milk fat in infant formula would improve immune development in IUGR and NBW neonates. Two-day old piglets were selected (NBW, n = 18, IUGR, n = 18) and each group of animals were fed formula based on either vegetable oil (VEG) or bovine milk fat (MILK). Animals were reared until day 23/24 and systemic immune parameters were evaluated. Milk-fat feeding decreased blood neutrophil counts and improved neutrophil function while transiently reducing leucocytes’ expression of genes related to adaptive and innate immunity as well as energy metabolism, following in vitro stimulation by live Staphylococcus epidermidis (whole blood, 2 h). However, there were only a few interactions between milk-fat type and birthweight status. Thus, piglets fed milk-fat-based formula had improved neutrophil maturation and suppressed pro-inflammatory responses, compared to those fed vegetable-oil-based formula.

The Acute Hepatic NF-κB-Mediated Proinflammatory Response to Endotoxemia Is Attenuated in Intrauterine Growth-Restricted Newborn Mice

Intrauterine growth restriction (IUGR) is a relevant predictor for higher rates of neonatal sepsis worldwide and is associated with an impaired neonatal immunity and lower immune cell counts. During the perinatal period, the liver is a key immunological organ responsible for the nuclear factor kappa B (NF-κB)-mediated innate immune response to inflammatory stimuli, but whether this role is affected by IUGR is unknown. Herein, we hypothesized that the newborn liver adapts to calorie-restriction IUGR by inducing changes in the NF-κB signaling transcriptome, leading to an attenuated acute proinflammatory response to intraperitoneal lipopolysaccharide (LPS). We first assessed the hepatic gene expression of key NF-κB factors in the IUGR and normally grown (NG) newborn mice. Real-time quantitative PCR (RT-qPCR) analysis revealed an upregulation of both IκB proteins genes (Nfkbia and Nfkbib) and the NF-κB subunit Nfkb1 in IUGR vs. NG. We next measured the LPS-induced hepatic expression of acute proinflammatory genes (Ccl3, Cxcl1, Il1b, Il6, and Tnf) and observed that the IUGR liver produced an attenuated acute proinflammatory cytokine gene response (Il1b and Tnf) to LPS in IUGR vs. unexposed (CTR). Consistent with these results, LPS-exposed hepatic tumor necrosis factor alpha (TNF-α) protein concentrations were lower in IUGR vs. LPS-exposed NG and did not differ from IUGR CTR. Sex differences at the transcriptome level were observed in the IUGR male vs. female. Our results demonstrate that IUGR induces key modifications in the NF-κB transcriptomic machinery in the newborn that compromised the acute proinflammatory cytokine gene and protein response to LPS. Our results bring novel insights in understanding how the IUGR newborn is immunocompromised due to fundamental changes in NF-κB key factors.

Gestational Age-Specific Complete Blood Count Signatures in Necrotizing Enterocolitis

Objective: Necrotizing enterocolitis (NEC) is characterized by peripheral cell abnormalities, yet few studies have analyzed the complete blood count (CBC) specifically by gestational age (GA). Our objective was to describe GA-specific immune abnormalities in NEC through a comprehensive analysis of the CBC differential. Methods: Using a cohort of 246 infants (177 cases, 69 controls) admitted to neonatal intensive care units at a single institution, we retrospectively analyzed CBCs around illness onset in NEC cases compared with controls. Cases included surgical NEC (S-NEC, 34.5%) and medical NEC (M-NEC, 65.5%). Infants were divided into those born at GA <33 and ≥33 weeks. Differences in CBC values were described as absolute and percent changes at NEC onset from baseline and at antibiotic completion after NEC. We used machine learning algorithms based on the CBC at NEC to generate predictive models for diagnosis. Results: At NEC onset, there was an acute drop in monocytes and lymphocytes along with a rise in bands in S-NEC infants born <33 weeks compared with M-NEC. In comparison, both M-NEC and S-NEC ≥33 weeks had a percent drop in neutrophils at diagnosis compared with controls. At antibiotic completion, monocytes in S-NEC <33 weeks significantly rose compared with M-NEC, yet for S-NEC ≥33 weeks, bands significantly dropped compared with M-NEC. Predictive modeling was able to accurately predict S-NEC from M-NEC and controls. Conclusion: There are discrete leukocyte patterns in NEC based on GA. The CBC at diagnosis may be useful in identifying patients who will require surgery.

Impaired Neonatal Immunity and Infection Resistance Following Fetal Growth Restriction in Preterm Pigs

Background: Infants born preterm or small for gestational age (SGA, due to fetal growth restriction) both show an increased risk of neonatal infection. However, it remains unclear how the co-occurrence of preterm birth and SGA may affect neonatal immunity and infection risk. We hypothesized that fetal growth restricted (FGR) preterm newborns possess impaired immune competence and increased susceptibility to systemic infection and sepsis, relative to corresponding normal birth weight (NBW) newborns.

Methods: Using preterm pigs as a model for preterm infants, gene expression in lipopolysaccharide (LPS) stimulated cord blood was compared between NBW and FGR (lowest 25% birth weight percentile) preterm pigs. Next, clinical responses to a systemic Staphylococcus epidermidis (SE) challenge were investigated in newborn FGR and NBW preterm pigs. Finally, occurrence of spontaneous infections were investigated in 9 d-old FGR and NBW preterm pigs, with or without neonatal antibiotics treatment.

Results: At birth, preterm FGR piglets showed diminished ex vivo cord blood responses to LPS for genes related to both innate and adaptive immunity, and also more severe septic responses following SE infection (e.g., higher blood lactate, decreased blood pH, neutrophil and platelet counts, relative to NBW pigs). After 9 d, FGR pigs had higher incidence and severity of spontaneous infections (e.g., higher bacterial densities in the bone marrow), increased regulatory T cell numbers, reduced neutrophil phagocytosis capacity, and impaired ex vivo blood gene responses to LPS, especially when receiving neonatal antibiotics.

Conclusion: FGR at preterm birth is associated with poor immune competence, impaired infection resistance, and greater sepsis susceptibility in the immediate postnatal period. Our results may explain the increased morbidity and mortality of SGA preterm infants and highlight the need for clinical vigilance for this highly sensitive subgroup of preterm neonates.

SEPSIS project: a protocol for studying biomarkers of neonatal sepsis and immune responses of infants in a malaria-endemic region

INTRODUCTION

Neonatal sepsis outreaches all causes of neonatal mortality worldwide and remains a major societal burden in low and middle income countries. In addition to limited resources, endemic morbidities, such as malaria and prematurity, predispose neonates and infants to invasive infection by altering neonatal immune response to pathogens. Nevertheless, thoughtful epidemiological, diagnostic and immunological evaluation of neonatal sepsis and the impact of gestational malaria have never been performed.

METHODS AND ANALYSIS

A prospective longitudinal multicentre follow-up of 580 infants from birth to 3 months of age in urban and suburban Benin will be performed. At delivery, and every other week, all children will be examined and clinically evaluated for occurrence of sepsis. At delivery, cord blood systematic analysis of selected plasma and transcriptomic biomarkers (procalcitonin, interleukin (IL)-6, IL-10, IP10, CD74 and CX3CR1) associated with sepsis pathophysiology will be evaluated in all live births as well as during the follow-up, and when sepsis will be suspected. In addition, whole blood response to selected innate stimuli and extensive peripheral blood mononuclear cells phenotypic characterisation will be performed. Reference intervals specific to sub-Saharan neonates will be determined from this cohort and biomarkers performances for neonatal sepsis diagnosis and prognosis tested.

ETHICS AND DISSEMINATION

Ethical approval has been obtained from the Comité d'Ethique de la Recherche - Institut des Sciences Biomédicales Appliquées (CER-ISBA 85 - 5 April 2016, extended on 3 February 2017). Results will be disseminated through international presentations at scientific meetings and publications in peer-reviewed journals.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov registration number: NCT03780712.

Heat Stress Impacts Immune Status in Cows Across the Life Cycle

Heat stress has a myriad of effects on dairy cattle across the life cycle. Whereas, the most commonly recognized impacts are associated with production responses, emerging evidence indicates that heat stress profoundly alters the immune response of calves and cows, from the prenatal stage through lactation. For example, in utero heat stress reduces passive immune transfer regardless of colostrum source, relative to normothermic conditions in late gestation. Dry cows exposed to heat stress have lower immunoglobulin responses to ovalbumin vaccination, but this effect dissipates with cooling following parturition. Conversely, cows under heat stress when dry exhibit carryover effects on the innate arm of the immune system in early lactation. In this paper we review the effects of heat stress throughout the life cycle of the dairy cow, with particular emphasis on the impact of heat stress during late gestation on the cow and the developing fetus, both before and after parturition. In addition, the impact of altered immune status under heat stress on other physiological systems, especially those supporting milk production, are considered. Finally, management interventions to prevent and reverse the effect of heat stress are presented.

Altered immune system in offspring of rat maternal vertical sleeve gastrectomy

Obesity in women results in reduced fertility and increased complications during pregnancy. Vertical sleeve gastrectomy (VSG) effectively reduces weight, type 2 diabetes, and dyslipidemia, but is also associated with preterm and small-for-gestational age births. The mechanism by which VSG influences fetal development remains unknown. Here we hypothesize that previously reported immune changes during rat VSG pregnancy are reflected long term in the immune system of the offspring. Offspring of VSG and sham dams were evaluated at postnatal day (PND) 21 and PND60. At PND21, VSG pups have lower numbers of circulating B lymphocytes compared with sham pups (P < 0.05) and have lower transcription of lymphocyte marker Ptprc (P < 0.01) in the spleen, while other lymphocyte populations measured are not different. Total plasma IgG is higher (P < 0.01) and C-reactive protein is lower (P < 0.05) in VSG offspring compared with sham offspring at PND21. The central nervous system of VSG pups is also affected at PND21, having higher expression of Il1b mRNA (P < 0.05) and higher immunoreactivity of microglia marker, IBA1, in the hypothalamus. At PND60, the immune-hematological differences are not present; however, mRNA expression of Il1b is elevated (P < 0.001) in the spleen of VSG offspring along with markers of T cells. These data suggest that the immune system of VSG offspring is compromised early in life, but rebounds after weaning and may even become hyperactive. Future work is needed to determine whether the immune system of VSG offspring is capable of mounting a proper defense and whether other aspects of development are affected.

Growth Restriction and Systemic Immune Development in Preterm Piglets

Background: Many preterm infants are born with growth restriction (GR) following maternal or fetal complications before birth. Such infants may continue to grow slowly after birth, regardless of birth weight (BW), due to morbidities related to their immature organs. Severe GR increases the susceptibility to infections, but it is not clear if this is a consequence of impaired systemic immunity or other factors, such as prolonged hospital stay or poor mucosal barrier function. Using preterm pigs as models for preterm infants, we hypothesized that moderate GR, exerting limited clinical effects, does not influence systemic immune development.

Methods: Preterm pigs were delivered by cesarean section and fed bovine milk diets until 19 d. Piglets with fetal growth restriction (F-GR, the lowest 25% of BW, n = 27, excluding those with BW <350 g) and postnatal growth restriction (P-GR, the lowest 25% of postnatal growth rate, n = 24) were compared with their corresponding controls (F-CON, n = 92, and P-CON, n = 85, respectively). Organ weights were determined and blood collected for assessment of clinical status (blood chemistry and hematology). For a subgroup (n = 58), in depth analyses of neutrophil function, T cell counts, plasma cytokine levels, and leucocyte gene expression were performed.

Results: For F-GR pigs, adrenal gland weight was increased and bone mineral content decreased at 19 d. Total leucocyte levels were lower at birth and interleukin-10 levels increased at d 8–10. In P-GR pigs, total leucocyte, neutrophil, monocyte, and eosinophil counts along with helper T cell fractions were elevated at 8–19 d of age, while the fraction of neutrophils with phagocytic capacity was reduced. Diarrhea and all remaining organ weights, blood chemistry, and immune variables were not affected by F-GR or P-GR.

Conclusion: Moderate GR before and after preterm birth has limited effect on systemic immune development in preterm pigs, despite marginal effects on immune cell populations, adrenocortical function, and body composition. Similar responses may be observed for preterm infants with moderate fetal and postnatal growth restriction.

Inflammation in the neonatal period and intrauterine growth restriction aggravate bronchopulmonary dysplasia

BACKGROUND

To investigate the hematological features of infants with bronchopulmonary dysplasia (BPD) and their relationships with clinical severity.

METHODS

This prospective observational study enrolled 73 BPD patients from a total of 331 infants with a birth weight of <1500 g from 2005 to 2013. The clinical severity of BPD was defined by the duration of oxygen supplementation and positive pressure ventilation (PPV) in line with the diagnostic criteria of BPD. The hematological status and cytokine levels were surveyed from blood samples at birth and at 2 and 4 weeks of life.

RESULTS

Thirty-four (46.6%) cases were classified as "moderate-to-severe" BPD. Small-for-gestational-age (SGA) was associated with the severity of BPD (OR: 5.05; 95% CI: 1.45 to 17.2). The CRP level at 2 weeks (partial regression coefficient [rc]: 21.8; 4.01 to 39.7) and the neutrophil count at 4 weeks (0.005; 0.001 to 0.007) were positively correlated with the oxygenation period. The PPV period was found to be correlated with the CRP level at 2 weeks (27.2; 14.9 to 39.5), and the neutrophil count (0.003; 0.001 to 0.004) at 4 weeks.

CONCLUSION

The aggravation of BPD was associated with both SGA at birth and inflammation during neonatal period.

Risk factors and complications of small for gestational age

Objective:

The objective of this study was to find out the maternal risk factors and perinatal complications in small for gestational age (SGA) newborns.

Methods:

A total of 181 SGA cases and 1299 cases of appropriate for gestational age (AGA) with the same gestational age between January 2015 and December 2016 were enrolled in Linyi People’s Hospital, China. The risk factors were analyzed and the frequencies of perinatal complications were compared between the two groups.

Results:

The frequencies of maternal risk factors such as pregnancy-induced hypertension, abnormal placenta and twins in the SGA group were significantly higher than that in the AGA group (P<0.05). The incidence of hyperbilirubinemia and hypoglycemia in the perinatal period was also higher in the SGA newborns group (P<0.05), while there were no significant differences in the incidence of pneumonia, apnea, septicemia, intracranial hemorrhage, neonatal asphyxia, congenital malformations, hypoxic-ischemic encephalopathy, respiratory distress syndrome and necrotizing enterocolitis between the two groups.

Conclusions:

SGA can cause perinatal complications including neonatal hypoglycemia and hyperbilirubinemia. It is necessary to strengthen the perinatal monitoring and antenatal care to reduce SGA and the perinatal complications of SGA.

Single-Cell Analysis Identifies Thymic Maturation Delay in Growth-Restricted Neonatal Mice

Fetal growth restriction (FGR) causes a wide variety of defects in the neonate which can lead to increased risk of heart disease, diabetes, anxiety and other disorders later in life. However, the effect of FGR on the immune system, is poorly understood. We used a well-characterized mouse model of FGR in which placental Igf-2 production is lost due to deletion of the placental specific Igf-2 P₀ promotor. The thymi in such animals were reduced in mass with a ~70% reduction in cellularity. We used single cell RNA sequencing (Drop-Seq) to analyze 7,264 thymus cells collected at postnatal day 6. We identified considerable heterogeneity among the Cd8/Cd4 double positive cells with one subcluster showing marked upregulation of transcripts encoding a sub-set of proteins that contribute to the surface of the ribosome. The cells from the FGR animals were underrepresented in this cluster. Furthermore, the distribution of cells from the FGR animals was skewed with a higher proportion of immature double negative cells and fewer mature T-cells. Cell cycle regulator transcripts also varied across clusters. The T-cell deficit in FGR mice persisted into adulthood, even when body and organ weights approached normal levels due to catch-up growth. This finding complements the altered immunity found in growth restricted human infants. This reduction in T-cellularity may have implications for adult immunity, adding to the list of adult conditions in which the in utero environment is a contributory factor.

The Microbiome and Preterm Birth: A Change in Paradigm with Profound Implications for Pathophysiologic Concepts and Novel Therapeutic Strategies

Preterm birth poses a global challenge with a continuously increasing disease burden during the last decades. Advances in understanding the etiopathogenesis did not lead to a reduction of prematurely born infants so far. A balanced development of the host microbiome in early life is key for the maturation of the immune system and many other physiological functions. With the tremendous progress in new diagnostic possibilities, the contribution of microbiota changes to preterm birth and the acute and long-term sequelae of prematurity have come into the research focus. This review summarizes the latest advances in the understanding of microbiomes in the amniotic cavity and the female lower genital tract and how changes in microbiota structures contribute to preterm delivery. The exhibition of these highly vulnerable infants to the hostile environment in the neonatal intensive care unit necessarily entails the rapid colonization with a nonbalanced microbiome in a situation where the organism is still very prone and at an early stage of development. The global research efforts to decipher pathologic changes will pave the way to new pre- and postnatal therapeutic concepts.

Mannose-binding lectin and mannose-binding protein-associated serine protease 2 levels and infection in very-low-birth-weight infants

OBJECTIVE

The aim of this study was to explore the role of the lectin pathway in neonatal sepsis through the study of MBL and MASP2 levels and their relationship with infection in a cohort of very-low-birth-weight infants (VLBWI).

METHODS

MBL and MASP2 were measured in plasma samples of n = 89 VLBWI using ELISA and correlated with clinical parameters. MBL plasma levels were aligned with genotyping data of mbl2 exon 1 polymorphisms, rs1800450, rs1800451, and rs5030737.

RESULTS

MBL levels were clearly determined by MBL genotype, i.e., AA individuals had tenfold higher MBL levels than AO individuals. MBL and MASP2 levels did not correlate with gestational age, apart from MASP2 levels on day 7. During the first 21 days of life, we noted a gradual increase in both MBL and MASP2 levels. On day 7 of life, MASP2 levels in infants developing late-onset sepsis measured before the onset of symptoms were found to be lower, as compared to non-LOS infants.

CONCLUSIONS

In our cohort of VLBWI, MBL levels were genetically determined, but not associated with gestational age or sepsis in the first 21 days of life. Lower MASP2 levels on day 7 may indicate increased risk for late-onset infection.

Neonatal and Long-Term Consequences of Fetal Growth Restriction

BACKGROUND

Fetal Growth Restriction (FGR) is one of the most common noxious antenatal conditions in humans, inducing a substantial proportion of preterm delivery and leading to a significant increase in perinatal mortality, neurological handicaps and chronic diseases in adulthood. This review summarizes the current knowledge about the postnatal consequences of FGR, with a particular emphasis on the long-term consequences on respiratory, cardiovascular and neurological structures and functions.

RESULT AND CONCLUSION

FGR represents a global health challenge, and efforts are urgently needed to improve our understanding of the critical factors leading to FGR and subsequent insults to the developing organs.

Minocycline-Suppression of Early Peripheral Inflammation Reduces Hypoxia-Induced Neonatal Brain Injury

While extensive studies report that neonatal hypoxia-ischemia (HI) induces long-term cognitive impairment via inflammatory responses in the brain, little is known about the role of early peripheral inflammation response in HI injury. Here we used a neonatal hypoxia rodent model by subjecting postnatal day 0 (P0d) rat pups to systemic hypoxia (3.5 h), a condition that is commonly seen in clinic neonates, Then, an initial dose of minocycline (45 mg/kg) was injected intraperitoneally (i.p.) 2 h after the hypoxia exposure ended, followed by half dosage (22.5 mg/kg) minocycline treatment for next 6 consecutive days daily. Saline was injected as vehicle control. To examine how early peripheral inflammation responded to hypoxia and whether this peripheral inflammation response was associated to cognitive deficits. We found that neonatal hypoxia significantly increased leukocytes not only in blood, but also increased the monocytes in central nervous system (CNS), indicated by presence of C-C chemokine receptor type 2 (CCR2⁺)/CD11b⁺CD45⁺ positive cells and CCR2 protein expression level. The early onset of peripheral inflammation response was followed by a late onset of brain inflammation that was demonstrated by level of cytokine IL-1β and ionized calcium binding adapter molecule 1(Iba-1; activated microglial cell marker). Interrupted blood-brain barrier (BBB), hypomyelination and learning and memory deficits were seen after hypoxia. Interestingly, the cognitive function was highly correlated with hypoxia-induced leukocyte response. Notably, administration of minocycline even after the onset of hypoxia significantly suppressed leukocyte-mediated inflammation as well as brain inflammation, demonstrating neuroprotection in systemic hypoxia-induced brain damage. Our data provided new insights that systemic hypoxia induces cognitive dysfunction, which involves the leukocyte-mediated peripheral inflammation response.

RNA Sequencing Exposes Adaptive and Immune Responses to Intrauterine Growth Restriction in Fetal Sheep Islets

The risk of type 2 diabetes is increased in children and adults who exhibited fetal growth restriction. Placental insufficiency and intrauterine growth restriction (IUGR) are common obstetrical complications associated with fetal hypoglycemia and hypoxia that reduce the β-cell mass and insulin secretion. In the present study, we have defined the underlying mechanisms of reduced growth and proliferation, impaired metabolism, and defective insulin secretion previously established as complications in islets from IUGR fetuses. In an IUGR sheep model that recapitulates human IUGR, high-throughput RNA sequencing showed the transcriptome of islets isolated from IUGR and control sheep fetuses and identified the transcripts that underlie β-cell dysfunction. Functional analysis expanded mechanisms involved in reduced proliferation and dysregulated metabolism that include specific cell cycle regulators and growth factors and mitochondrial, antioxidant, and exocytotic genes. These data also identified immune responses, wnt signaling, adaptive stress responses, and the proteasome as mechanisms of β-cell dysfunction. The reduction of immune-related gene expression did not reflect a change in macrophage density within IUGR islets. The present study reports the islet transcriptome in fetal sheep and established processes that limit insulin secretion and β-cell growth in fetuses with IUGR, which could explain the susceptibility to premature islet failure in adulthood. Islet dysfunction formed by intrauterine growth restriction increases the risk for diabetes.

Plasma metabolomics indicates metabolic perturbations in low birth weight piglets supplemented with arginine

Large profit losses in the swine industry can be attributed to morbidity and mortality of piglets before weaning, especially in the low birth weight (LBW) piglet. Recent evidence suggests sow's milk contains insufficient concentrations of Arg to support optimal growth and health of piglets. Therefore, our objective was to assess global metabolomic profiles and the potential for Arg supplementation to promote growth of LBW (≤0.9 kg BW) and average birth weight (ABW; 1.3 to 1.5 kg BW) piglets. Piglets were selected in littermate pairs at processing to receive either Arg or an isonitrogenous control (Ala) and weighed daily to assess growth rate, and blood was collected at approximately 16 d of age for metabolomics analysis. In terms of growth, LBW and ABW piglets supplemented with Arg weighed 22.3 and 12.7% less, respectively, at d 16 compared with Ala-supplemented piglets of the same birth weight group. Overall, differences ( < 0.05) were observed among treatments for metabolic pathways involving energy (i.e., tricarboxylic acid cycle intermediates), AA, nucleotides, and fatty acids. Increased nucleotide turnover, indicative of an increase in DNA damage and cell death, was particularly noted in the LBW piglet. However, Arg supplementation reduced these effects to levels comparable to those observed in ABW piglets. Moreover, changes in glucose metabolism suggested a compromised ability to extract energy from dietary sources may have occurred in the LBW piglet, but these effects were partially recovered by Arg supplementation. We conclude that a reduction in the growth potential of LBW piglets may be associated with alterations in multiple metabolic pathways, and further reduction due to Arg supplementation may have resulted from perturbations in multiple metabolic pathways.

Developmental origins of inflammatory and immune diseases

Epidemiological and experimental animal studies show that suboptimal environments in fetal and neonatal life exert a profound influence on physiological function and risk of diseases in adult life. The concepts of the 'developmental programming' and Developmental Origins of Health and Diseases (DOHaD) have become well accepted and have been applied across almost all fields of medicine. Adverse intrauterine environments may have programming effects on the crucial functions of the immune system during critical periods of fetal development, which can permanently alter the immune function of offspring. Immune dysfunction may in turn lead offspring to be susceptible to inflammatory and immune diseases in adulthood. These facts suggest that inflammatory and immune disorders might have developmental origins. In recent years, inflammatory and immune disorders have become a growing health problem worldwide. However, there is no systematic report in the literature on the developmental origins of inflammatory and immune diseases and the potential mechanisms involved. Here, we review the impacts of adverse intrauterine environments on the immune function in offspring. This review shows the results from human and different animal species and highlights the underlying mechanisms, including damaged development of cells in the thymus, helper T cell 1/helper T cell 2 balance disturbance, abnormal epigenetic modification, effects of maternal glucocorticoid overexposure on fetal lymphocytes and effects of the fetal hypothalamic-pituitary-adrenal axis on the immune system. Although the phenomena have already been clearly implicated in epidemiologic and experimental studies, new studies investigating the mechanisms of these effects may provide new avenues for exploiting these pathways for disease prevention.

Mortality and morbidity risks vary with birth weight standard deviation score in growth restricted extremely preterm infants

OBJECTIVE

To assess whether the mortality and morbidity risks vary with birth weight standard deviation score (BWSDS) in growth restricted extremely preterm infants.

STUDY DESIGN

This was a multicenter retrospective cohort study using the database of the Neonatal Research Network of Japan and including 9149 infants born between 2003 and 2010 at <28 weeks gestation. According to the BWSDSs, the infants were classified as: <-2.0, -2.0 to -1.5, -1.5 to -1.0, -1.0 to -0.5, and ≥-0.5. Infants with BWSDS≥-0.5 were defined as non-growth restricted group.

RESULTS

After adjusting for covariates, the risks of mortality and some morbidities were different among the BWSDS groups. Compared with non-growth restricted group, the adjusted odds ratio (aOR) for mortality [aOR, 1.69; 95% confidence interval (CI), 1.35-2.12] and chronic lung disease (CLD) (aOR, 1.28; 95% CI, 1.07-1.54) were higher among the infants with BWSDS -1.5 to <-1.0. The aOR for severe retinopathy of prematurity (ROP) (aOR, 1.36; 95% CI, 1.09-1.71) and sepsis (aOR, 1.72; 95% CI, 1.32-2.24) were higher among the infants with BWSDS -2.0 to <-1.5. The aOR for necrotizing enterocolitis (NEC) (aOR, 2.41; 95% CI, 1.64-3.55) was increased at a BWSDS<-2.0.

CONCLUSION

Being growth restricted extremely preterm infants confer additional risks for mortality and morbidities such as CLD, ROP, sepsis and NEC, and these risks may vary with BWSDS.

Nucleated red blood cells as marker for an increased risk of unfavorable outcome and mortality in very low birth weight infants

BACKGROUND

Nucleated red blood cells (NRBC) are normoblastic cells that failed to extrude their nuclei before exiting from bone marrow or liver. While NRBC are frequently found in umbilical cord blood after fetal distress, NRBC counts drop rapidly after birth.

AIMS

To determine the predictive value of the NRBC count during the first 120h after birth as marker for later risk of unfavorable outcome in very preterm infants.

STUDY DESIGN

This cohort study investigated the association between absolute count of NRBC on admission (day 1), the mean NRBC count between day 2 to 5, and outcome (mortality or the composite outcome of mortality and severe morbidity).

RESULTS

438 infants with a gestational age<32weeks and a birth weight<1500g were included within a five-year period, of whom 46 patients died and 65 suffered from severe morbidity. Nonsurvivors had significantly higher NRBC counts between day 2 and 5, as compared to survivors. This finding was observed in infants both appropriate and small for gestational age. An increase of 10/nL of the mean NRBC count on postnatal day 2 to 5 had an odds ratio for mortality of 6.95 (95% CI 2.21-21.86) and an odds ratio for the composite outcome mortality and severe morbidity of 3.43 (95% CI 1.43-8.24). The optimal cut-off value for prediction of death was NRBC >2/nL with a sensitivity of 85% and a specificity of 75%.

CONCLUSIONS

Elevation of NRBC on postnatal day 2 to 5 is an independent predictor of mortality in preterm infants.

Underweight full-term Indian neonates show differences in umbilical cord blood leukocyte phenotype: a cross-sectional study

BACKGROUND

While infections are a major cause of neonatal mortality in India even in full-term neonates, this is an especial problem in the large proportion (~20%) of neonates born underweight (or small-for-gestational-age; SGA). One potential contributory factor for this susceptibility is the possibility that immune system maturation may be affected along with intrauterine growth retardation.

METHODS

In order to examine the possibility that differences in immune status may underlie the susceptibility of SGA neonates to infections, we enumerated the frequencies and concentrations of 22 leukocyte subset populations as well as IgM and IgA levels in umbilical cord blood from full-term SGA neonates and compared them with values from normal-weight (or appropriate-for-gestational-age; AGA) full-term neonates. We eliminated most SGA-associated risk factors in the exclusion criteria so as to ensure that AGA-SGA differences, if any, would be more likely to be associated with the underweight status itself.

RESULTS

An analysis of 502 such samples, including 50 from SGA neonates, showed that SGA neonates have significantly fewer plasmacytoid dendritic cells (pDCs), a higher myeloid DC (mDC) to pDC ratio, more natural killer (NK) cells, and higher IgM levels in cord blood in comparison with AGA neonates. Other differences were also observed such as tendencies to lower CD4:CD8 ratios and greater prominence of inflammatory monocytes, mDCs and neutrophils, but while some of them had substantial differences, they did not quite reach the standard level of statistical significance.

CONCLUSIONS

These differences in cellular lineages of the immune system possibly reflect stress responses in utero associated with growth restriction. Increased susceptibility to infections may thus be linked to complex immune system dysregulation rather than simply retarded immune system maturation.

Foetal Doppler abnormality is associated with increased risk of sepsis and necrotising enterocolitis in preterm infants

AIM

Fetoplacental Doppler abnormalities have been associated with increased neonatal mortality and morbidity. This study evaluated the associations between prenatal Doppler assessments and neonatal mortality and morbidity in premature infants born small for gestational age or after pre-eclampsia.

METHODS

This was a population-based study of infants born alive at 22(0) -33(6) weeks of gestation, a birthweight <10th percentile for gestational age and/or maternal pre-eclampsia. Doppler assessments of the umbilical artery, middle cerebral artery and ductus venosus were evaluated in 127, 125 and 95 cases, respectively. Circulatory compromise was defined as absent or reversed end-diastolic velocity in the umbilical artery (AREDF), middle cerebral artery pulsatility index <2.5 percentile for gestational age and ductus venosus pulsatility index for veins >97.5 percentile.

RESULTS

AREDF was present in 28% of the infants. This was associated with increased frequencies of neonatal sepsis and necrotising enterocolitis after adjusting for gestational age. Abnormal ductus venosus pulsatility index for veins was associated with increased risk of neonatal sepsis, but only in combination with AREDF. These associations were only present when gestational age was <28 weeks.

CONCLUSION

AREDF was associated with increased neonatal morbidity in premature infants born small for gestational age or after pre-eclampsia.

Neurodevelopmental impairment in preterm infants with late-onset infection: not only in extremely preterm infants

Late-onset infection is known to increase the risk of neurodevelopmental impairment in infants born extremely preterm. However, little data is available regarding infants born moderately preterm. The aim of this study was to determine whether late-onset infection in moderately preterm infants (<35 weeks of gestation) was associated with a non-optimal neurodevelopmental outcome at 2 years of age. We analyzed a regional, population-based cohort of infants (LIFT cohort) between January 2003 and December 2009, and we used a propensity score method to reduce bias. Among the 4,618 preterm infants assessed at 2 years, 618 had acquired late-onset infection (13.4 %), and 764 had a non-optimal outcome (16.5 %). The rate of non-optimal outcomes was significantly higher in preterm infants with late-onset infection, irrespective of subgroups of gestational age and birth weight Z-score. After adjusting for the propensity score, the relationship between late-onset infection and non-optimal neurodevelopmental outcome at 2 years among infants born before 35 weeks of gestation remained significant (aOR = 1.3; 95 % CI 1.01-1.7; p = .04).

CONCLUSION

Late-onset infection is associated with poor neurological outcome at 2 years of age among infants born moderately preterm before and after adjustment for the propensity score.

Differential expression of antimicrobial polypeptides in cord blood samples of preterm and term infants

AIM

To determine levels of antimicrobial polypeptides (AMP) in cord blood of term and preterm neonates and to investigate influencing factors.

METHODS

In a single-centre study, n = 139 preterm infants and n = 36 term infants were included. AMP levels were analysed in supernatants of whole cord blood cultures with a standardised concentration of 5 × 10(6) white blood cells/mL via enzyme-linked immunosorbent assay (ELISA).

RESULTS

Lactoferrin, human neutrophil peptides (HNP) 1-3 and bacterial permeability-increasing protein (BPI) expression in cord blood of preterm infants were influenced by the cause of preterm delivery, that is increased levels in infants with clinical amniotic infection. AMP levels also weakly correlated with white blood cell and neutrophil count at birth. In the whole cohort, no association between gestational age or birthweight with AMP levels was found. In the subgroup of infants without clinical amniotic infection (n = 77 preterm infants, n = 36 healthy term infants), we noted a weak correlation between gestational age and lactoferrin, calprotectin and HNP1-3 levels. In addition to that, we observed higher levels of lactoferrin and HNP1-3 in large-for-gestational-age infants.

CONCLUSION

Our study confirms that several factors influence cord blood AMP levels which underlines the difficulties of using AMP levels as biomarkers of immunological response.

Risk for late-onset blood-culture proven sepsis in very-low-birth weight infants born small for gestational age: a large multicenter study from the German Neonatal Network

BACKGROUND

It was the aim of this study to assess whether very-low-birth-weight (VLBW) infants born small for gestational age (SGA; birth weight less than 10th percentile) are at increased risk for late-onset sepsis.

METHODS

This was a prospective, multicenter study of the German Neonatal Network including VLBW infants from 23 to < 32 weeks post menstrual age born 2009-2011. Outcomes were compared between VLBW infants born SGA (birth weight less than tenth percentile according to gestational age and gender) and non-SGA infants. The main outcome measure was at least 1 episode of late-onset sepsis defined as blood-culture-confirmed clinical sepsis occurring at ≥ 72 hours of age.

RESULTS

5886 VLBW infants were included. In SGA infants (n = 692), an increased incidence of late-onset sepsis was noted compared with non-SGA infants (20.1% vs. 14.3 %, P < 0.001). This difference was only observed among infants with a gestational age of 27 to < 32 weeks and attributed to sepsis episodes with coagulase-negative staphylococci (12.8% vs. 8.3%, P < 0.001). Different treatment modalities (eg more frequent use of central venous lines) and longer duration of invasive therapies (parenteral nutrition, mechanical ventilation, hospitalization) may account for the increased sepsis risk with coagulase-negative staphylococci in our SGA cohort. In a multivariate logistic regression analysis, higher gestational age [per week; odds ratio (OR): 0.75, 95% confidence interval (CI): 0.72-0.78, P< 0.0001], treatment with antenatal steroids (OR: 0.7, 95% CI: 0.53-0.92, P = 0.01), German descendance (OR: 0.76, 95% CI: 0.63-0.91, P = 0.003) and prophylaxis with glycopeptide antibiotics (OR: 0.64, 95% CI: 0.47-0.87, P = 0.005) were shown to be protective against late-onset sepsis. In contrast, longer duration of parenteral nutrition (per day; OR: 1.016, 95% CI: 1.011-1.021, P < 0.0001) and SGA were found to be risk factors (OR: 1.31, 95% CI: 1.02-1.68, P= 0.03).

CONCLUSIONS

SGA contributes to the risk of late-onset sepsis in VLBW infants. Future studies are needed to investigate the underlying pathophysiology to guide individualized preventive measures in this vulnerable subgroup.

Hierarchical maturation of innate immune defences in very preterm neonates

BACKGROUND

Preterm neonates are highly vulnerable to infection.

OBJECTIVES

To investigate the developmental contribution of prematurity, chorioamnionitis and antenatal corticosteroids (ANS) on the maturation of neonatal microbial pathogen recognition responses.

METHODS

Using standardized protocols, we assayed multiple inflammatory cytokine responses (IL-1β, IL-6, TNF-α and IL-12/23p40) to three prototypic Toll-like receptor (TLR) agonists, i.e. TLR4 (lipopolysaccharide), TLR5 (flagellin) and TLR7/8 (R848), and to the non-TLR retinoic acid-inducible gene I (RIG-I)-like receptor agonist, in cord blood mononuclear cells from neonates born before 33 weeks of gestation and at term.

RESULTS

TLR responses develop asynchronously in preterm neonates, whereby responses to TLR7/8 were more mature and were followed by the development of TLR4 responses, which were also heterogeneous. Responses to TLR5 were weakest and most immature. Maturity in TLR responses was not influenced by sex. Overall, we detected no significant contribution of ANS and chorioamnionitis to the developmental attenuation of either TLR or RIG-I responses.

CONCLUSIONS

The maturation of anti-microbial responses in neonates born early in gestation follows an asynchronous developmental hierarchy independently of an exposure to chorioamnionitis and ANS. Our data provide an immunological basis for the predominance of specific microbial infections in this age group.