Neonatal innate immunity to infectious agents

Metabolic trade-offs in Neonatal sepsis triggered by TLR4 and TLR1/2 ligands result in unique dysfunctions in neural breathing circuits

Neonatal sepsis remains one of the leading causes of mortality in newborns. Several brainstem-regulated physiological processes undergo disruption during neonatal sepsis. Mechanistic knowledge gaps exist at the interplay between metabolism and immune activation to brainstem neural circuits and pertinent physiological functions in neonates. To delineate this association, we induced systemic inflammation either by TLR4 (LPS) or TLR1/2 (PAM3CSK4) ligand administration in postnatal day 5 mice (PD5). Our findings show that LPS and PAM3CSK4 evoke substantial changes in respiration and metabolism. Physiological trade-offs led to hypometabolic-hypothermic responses due to LPS, but not PAM3CSK4, whereas to both TLR ligands blunted respiratory chemoreflexes. Neuroinflammatory pathways modulation in brainstem showed more robust effects in LPS than PAM3CSK4. Brainstem neurons, microglia, and astrocyte gene expression analyses showed unique responses to TLR ligands. PAM3CSK4 did not significantly modulate gene expression changes in GLAST-1 positive brainstem astrocytes. PD5 pups receiving PAM3CSK4 failed to maintain a prolonged metabolic state repression, which correlated to enhanced gasping latency and impaired autoresuscitation during anoxic chemoreflex challenges. In contrast, LPS administered pups showed no significant changes in anoxic chemoreflex. Electrophysiological studies from brainstem slices prepared from pups exposed to either TLR4 or PAM3CSK4 showed compromised transmission between preBötzinger complex and Hypoglossal as an exclusive response to the TLR1/2 ligand. Spatial gene expression analysis demonstrated a region-specific modulation of PAM3CSK4 within the raphe nucleus relative to other anatomical sites evaluated. Our findings suggest that metabolic changes due to inflammation might be a crucial tolerance mechanism for neonatal sepsis preserving neural control of breathing.

Specific interaction between Group B Streptococcus CC17 hypervirulent clone and phagocytes

Streptococcus agalactiae also named Group B Streptococcus (GBS) is the most significant pathogen causing invasive infections, such as bacteremia and meningitis, in neonates. Worldwide epidemiological studies have shown that a particular clonal complex (CC) of capsular serotype III, the CC17, is strongly associated with meningitis in neonates and is therefore, designated as the hypervirulent clone. Macrophages are a permissive niche for intracellular bacteria of all GBS clones. In this study, we deciphered the specific interaction of GBS CC17 strains with macrophages. Our study revealed that CC17 strains are phagocytosed at a higher rate than GBS non-CC17 strains by human monocytes and macrophages both in cellular models and in primary cells. CC17-enhanced phagocytosis is due to an initial enhanced-attachment step to macrophages mediated by the CC17-specific surface protein HvgA and the PI-2b pilus (Spb1). We showed that two different inhibitors of scavenger receptors (fucoidan and poly(I)) specifically inhibited CC17 adhesion and phagocytosis while not affecting those of non-CC17 strains. Once phagocytosed, both CC17 and non-CC17 strains remained in a LAMP-1 positive vacuole that ultimately fuses with lysosomes where they can survive at similar rates. Finally, both strains displayed a basal egress which occurs independently from actin and microtubule networks. Our findings provide new insights into the interplay between the hypervirulent GBS CC17 and major players of the host's innate immune response. This enhanced adhesion, leading to increased phagocytosis, could reflect a peculiar capacity of the CC17 lineage to subvert the host immune defenses, establish a niche for persistence or disseminate.

Life-threatening infections in human newborns: Reconciling age-specific vulnerability and interindividual variability

In humans, the interindividual variability of clinical outcome following exposure to a microorganism is immense, ranging from silent infection to life-threatening disease. Age-specific immune responses partially account for the high incidence of infection during the first 28 days of life and the related high mortality at population level. However, the occurrence of life-threatening disease in individual newborns remains unexplained. By contrast, inborn errors of immunity and their immune phenocopies are increasingly being discovered in children and adults with life-threatening viral, bacterial, mycobacterial and fungal infections. There is a need for convergence between the fields of neonatal immunology, with its in-depth population-wide characterization of newborn-specific immune responses, and clinical immunology, with its investigations of infections in patients at the cellular and molecular levels, to facilitate identification of the mechanisms of susceptibility to infection in individual newborns and the design of novel preventive and therapeutic strategies.

Young infants display heterogeneous serological responses and extensive but reversible transcriptional changes following initial immunizations

Infants necessitate vaccinations to prevent life-threatening infections. Our understanding of the infant immune responses to routine vaccines remains limited. We analyzed two cohorts of 2-month-old infants before vaccination, one week, and one-month post-vaccination. We report remarkable heterogeneity but limited antibody responses to the different antigens. Whole-blood transcriptome analysis in an initial cohort showed marked overexpression of interferon-stimulated genes (ISGs) and to a lesser extent of inflammation-genes at day 7, which normalized one month post-vaccination. Single-cell RNA sequencing in peripheral blood mononuclear cells from a second cohort identified at baseline a predominantly naive immune landscape including ISGhi cells. On day 7, increased expression of interferon-, inflammation-, and cytotoxicity-related genes were observed in most immune cells, that reverted one month post-vaccination, when a CD8+ ISGhi and cytotoxic cluster and B cells expanded. Antibody responses were associated with baseline frequencies of plasma cells, B-cells, and monocytes, and induction of ISGs at day 7.

Clinical value of procalcitonin-to-albumin ratio for identifying sepsis in neonates with pneumonia

BACKGROUND

It is possible that neonates with pneumonia also have unrecognized sepsis. Identifying sepsis in neonates with pneumonia may cause some trouble for clinicians. This study aimed to evaluate the clinical value of the procalcitonin-to-albumin ratio (PAR) in identifying sepsis in neonates with pneumonia.

METHODS

We retrospectively included 912 neonates with pneumonia from January 2016 to July 2021. Clinical and laboratory data were collected from electronic medical records. Among neonates with pneumonia, 561 neonates were diagnosed with sepsis, according to the International Pediatric Sepsis Consensus. Neonates were divided into a sepsis group and a pneumonia group. A multivariate logistic regression analysis was used to evaluate whether PAR was a potential independent indicator for identifying sepsis in neonates with pneumonia. Receiver operating characteristic (ROC) curve analysis was performed to evaluate the diagnostic value of PAR in sepsis.

RESULTS

Neonates with sepsis have a higher PAR (p < 0.001). Correlation analysis showed that PAR was positively correlated with the level of C-reactive protein (r = 0.446, p < 0.001). Multiple logistic regression analysis showed that PAR was an independent predictor of the presence of sepsis in neonates with pneumonia. ROC curve analysis revealed that PAR had good power in identifying sepsis in neonates with pneumonia (area under curve (AUC) = 0.72, 95% confidence interval (CI), 0.68-0.75, p < 0.001).

CONCLUSION

PAR can be used as a new biomarker to identify sepsis in neonates with pneumonia.

Associations between prenatal malaria exposure, maternal antibodies at birth, and malaria susceptibility during the first year of life in Burkina Faso

In this study, we investigated how different categories of prenatal malaria exposure (PME) influence levels of maternal antibodies in cord blood samples and the subsequent risk of malaria in early childhood in a birth cohort study (N = 661) nested within the COSMIC clinical trial (NCT01941264) in Burkina Faso. Plasmodium falciparum infections during pregnancy and infants' clinical malaria episodes detected during the first year of life were recorded. The levels of maternal IgG and IgG1-4 to 15 P. falciparum antigens were measured in cord blood by quantitative suspension array technology. Results showed a significant variation in the magnitude of maternal antibody levels in cord blood, depending on the PME category, with past placental malaria (PM) more frequently associated with significant increases of IgG and/or subclass levels across three groups of antigens defined as pre-erythrocytic, erythrocytic, and markers of PM, as compared to those from the cord of non-exposed control infants. High levels of antibodies to certain erythrocytic antigens (i.e., IgG to EBA140 and EBA175, IgG1 to EBA175 and MSP142, and IgG3 to EBA140 and MSP5) were independent predictors of protection from clinical malaria during the first year of life. By contrast, high levels of IgG, IgG1, and IgG2 to the VAR2CSA DBL1-2 and IgG4 to DBL3-4 were significantly associated with an increased risk of clinical malaria. These findings indicate that PME categories have different effects on the levels of maternal-derived antibodies to malaria antigens in children at birth, and this might drive heterogeneity to clinical malaria susceptibility in early childhood.

Epidemiological and molecular characterization of Coxsackievirus A6 causing hand, foot, and mouth disease in the Philippines, 2012-2017

Coxsackievirus A6 (CVA6) is emerging as the dominant serotype among enteroviruses (EVs) responsible for hand, foot, and mouth disease (HFMD) outbreaks in multiple countries. However, details regarding this serotype in the Philippines are limited. In this study, we investigated the epidemiological and molecular characteristics of laboratory-confirmed CVA6 HFMD cases in the Philippines between 2012 and 2017. Data collected from case report forms submitted to the National Reference Laboratory for Poliovirus and other Enteroviruses were used to determine the distribution and clinical findings of laboratory-confirmed CVA6 HFMD. Phylogenetic analyses of the complete viral protein 1 (VP1) and partial 3D polymerase (3Dpol) gene sequences were performed to determine the genotype and recombinant (RF) form of the selected samples. An increase in the detection rate of CVA6 among enterovirus-positive HFMD cases was observed from 61.9% (140/226) in 2012 to 88.1% (482/587) in 2017, with most cases coming from the Luzon island group. Among the detected cases, the majority were children, with a median age of 2 years old (interquartile range: 1.17-3.40). Respiratory-related morbidities were the commonly reported complications (7.9%; 72/907). Based on the VP1 and 3Dpol gene sequence analysis, the CVA6 strains in this study were classified as genotype D3b and RF-A group, respectively. This study elucidated that CVA6 was the most prevalent enterovirus serotype causing HFMD in the Philippines in 2012-2017, with genotype D3b/RF-A circulating within this period. This study highlights the importance of viral surveillance and molecular epidemiological analysis to broaden our understanding of HFMD in the Philippines.

Sex Differences in the Frequencies of B and T Cell Subpopulations of Human Cord Blood

Cord blood represents a link between intrauterine and early extrauterine development. Cord blood cells map an important time frame in human immune imprinting processes. It is unknown whether the sex of the newborn affects the lymphocyte subpopulations in the cord blood. Nine B and twenty-one T cell subpopulations were characterized using flow cytometry in human cord blood from sixteen male and twenty-one female newborns, respectively. Except for transitional B cells and naïve B cells, frequencies of B cell counts across all subsets was higher in the cord blood of male newborns than in female newborns. The frequency of naïve thymus-negative Th cells was significantly higher in male cord blood, whereas the remaining T cell subpopulations showed a higher count in the cord blood of female newborns. Our study is the first revealing sex differences in the B and T cell subpopulations of human cord blood. These results indicate that sex might have a higher impact for the developing immune system, urging the need to expand research in this area.

Clinical manifestations and disease severity of SARS-CoV-2 infection among infants in Canada

Background

There are limited data on outcomes of SARS-CoV-2 infection among infants (<1 year of age). In the absence of approved vaccines for infants, understanding characteristics associated with hospitalization and severe disease from COVID-19 in this age group will help inform clinical management and public health interventions. The objective of this study was to describe the clinical manifestations, disease severity, and characteristics associated with hospitalization among infants infected with the initial strains of SARS-CoV-2.

Methods

This is a national, prospective study of infants with SARS-CoV-2 from April 8^th 2020 to May 31^st 2021 using the infrastructure of the Canadian Paediatric Surveillance Program. Infants <1 year of age with microbiologically confirmed SARS-CoV-2 infection from both inpatients and outpatients seen in clinics and emergency departments were included. Cases were classified as either: 1) Non-hospitalized patient with SARS-CoV-2 infection; 2) COVID-19-related hospitalization; or 3) non-COVID-19-related hospitalization (e.g., incidentally detected SARS-CoV-2). Case severity was defined as asymptomatic, outpatient care, mild (inpatient care), moderate or severe disease. Multivariable logistic regression was performed to identify characteristics associated with hospitalization.

Results

A total of 531 cases were reported, including 332 (62.5%) non-hospitalized and 199 (37.5%) hospitalized infants. Among hospitalized infants, 141 of 199 infants (70.9%) were admitted because of COVID-19-related illness, and 58 (29.1%) were admitted for reasons other than acute COVID-19. Amongst all cases with SARS-CoV-2 infection, the most common presenting symptoms included fever (66.5%), coryza (47.1%), cough (37.3%) and decreased oral intake (25.0%). In our main analysis, infants with a comorbid condition had higher odds of hospitalization compared to infants with no comorbid conditions (aOR = 4.53, 2.06–9.97), and infants <1 month had higher odds of hospitalization then infants aged 1–3 months (aOR = 3.78, 1.97–7.26). In total, 20 infants (3.8%) met criteria for severe disease.

Conclusions

We describe one of the largest cohorts of infants with SARS-CoV-2 infection. Overall, severe COVID-19 in this age group was found to be uncommon. Comorbid conditions and younger age were associated with COVID-19-related hospitalization amongst infants.

Use of Antibiotics in Preterm Newborns

Due to complex maturational and physiological changes that characterize neonates and affect their response to pharmacological treatments, neonatal pharmacology is different from children and adults and deserves particular attention. Although preterms are usually considered part of the neonatal population, they have physiological and pharmacological hallmarks different from full-terms and, therefore, need specific considerations. Antibiotics are widely used among preterms. In fact, during their stay in neonatal intensive care units (NICUs), invasive procedures, including central catheters for parental nutrition and ventilators for respiratory support, are often sources of microbes and require antimicrobial treatments. Unfortunately, the majority of drugs administered to neonates are off-label due to the lack of clinical studies conducted on this special population. In fact, physiological and ethical concerns represent a huge limit in performing pharmacokinetic (PK) studies on these subjects, since they limit the number and volume of blood sampling. Therapeutic drug monitoring (TDM) is a useful tool that allows dose adjustments aiming to fit plasma concentrations within the therapeutic range and to reach specific drug target attainment. In this review of the last ten years’ literature, we performed Pubmed research aiming to summarize the PK aspects for the most used antibiotics in preterms.

Neurodevelopmental outcomes of infants born to mothers with SARS-CoV-2 infections during pregnancy: a national prospective study in Kuwait

BACKGROUND

An increasing proportion of women are infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) during pregnancy. Intrauterine viral infections induce an increase in the levels of proinflammatory cytokines, which inhibit the proliferation of neuronal precursor cells and stimulate oligodendrocyte cell death, leading to abnormal neurodevelopment. Whether a maternal cytokine storm can affect neonatal brain development is unclear. The objective of the present study was to assess neurodevelopmental outcomes in neonates born to mothers with SARS-CoV-2 infections during pregnancy.

METHODS

In this prospective cohort study, the neurodevelopmental status of infants (N = 298) born to women with SARS-CoV-2 infections during pregnancy was assessed at 10-12 months post-discharge using the Ages and Stages Questionnaire, 3rd edition (ASQ-3). The ASQ-3 scores were classified into developmental delays (cutoff scores ≤ 2 standard deviations (SDs) below the population mean) and no delays (scores > 2 SDs above the population mean).

RESULTS

The majority (90%) of the infants born to mothers with SARS-CoV-2 infections during pregnancy had favorable outcomes and only 10% showed developmental delays. Two of the 298 infants tested positive for SARS-CoV-2, and both had normal ASQ-3 scores. The majority of the pregnant women had SARS-CoV-2 infections during their third trimester. The risk of developmental delays among infants was higher in those whose mothers had SARS-CoV-2 infections during the first (P = 0.039) and second trimesters (P = 0.001) than in those whose mothers had SARS-CoV-2 infections during the third trimester.

CONCLUSION

The neurodevelopmental outcomes of infants born to mothers with SARS-CoV-2 infections seem favorable. However, more studies with larger sample sizes and longer follow-up periods are required.

Safety of primary immunization with a DTwP-HBV/Hib vaccine in healthy infants: a prospective, open-label, interventional, phase IV clinical study

OBJECTIVE

This study aimed to assess the safety of a fully liquid DTwP-HBV/Hib pentavalent vaccine (Eupenta^TM) based on the occurrence of adverse events (AEs) following vaccination.

METHODS

This was a prospective, open-label, single-arm, interventional phase IV study. A single intramuscular injection of the study vaccine was administered to infants at approximately 6, 10, and 14 weeks of age, and an end-of-study follow-up visit was scheduled at 18 weeks. Safety data, including immediate reactions, solicited AEs, unsolicited AEs, vital signs, and physical examination findings were collected.

RESULTS

In all, 3000 subjects were enrolled and received at least one dose of the study vaccine. Of these, 2717 (90.6%) experienced at least one AE, most considered related to the study vaccine. Immediate reactions, solicited and unsolicited AEs were respectively identified in 224 (7.5%), 2,652 (88.4%), and 1,099 (36.6%) subjects. The most prevalent solicited and unsolicited AEs comprised pain/tenderness and upper respiratory tract infection, respectively. Most AEs were mildly or moderately severe. Forty-one (1.4%) subjects had at least one serious AE (SAE); of these, two (0.1%) had two SAEs each, considered related to the study vaccine. Six (0.2%) subjects died due to unsolicited AEs, none of which were considered related to the study vaccine. No AEs were reported at the end-of-study follow-up visit.

CONCLUSIONS

The study vaccine administered to infants at 6, 10, and 14 weeks of age had a safety profile similar to that reported in a previous clinical study, and did not result in an increased risk of AEs known to be associated with DTwP-based vaccines or previously unrecognized SAEs.

Genome-wide association, prediction and heritability in bacteria with application to Streptococcus pneumoniae

Whole-genome sequencing has facilitated genome-wide analyses of association, prediction and heritability in many organisms. However, such analyses in bacteria are still in their infancy, being limited by difficulties including genome plasticity and strong population structure. Here we propose a suite of methods including linear mixed models, elastic net and LD-score regression, adapted to bacterial traits using innovations such as frequency-based allele coding, both insertion/deletion and nucleotide testing and heritability partitioning. We compare and validate our methods against the current state-of-art using simulations, and analyse three phenotypes of the major human pathogen Streptococcus pneumoniae, including the first analyses of minimum inhibitory concentrations (MIC) for penicillin and ceftriaxone. We show that the MIC traits are highly heritable with high prediction accuracy, explained by many genetic associations under good population structure control. In ceftriaxone MIC, this is surprising because none of the isolates are resistant as per the inhibition zone criteria. We estimate that half of the heritability of penicillin MIC is explained by a known drug-resistance region, which also contributes a quarter of the ceftriaxone MIC heritability. For the within-host carriage duration phenotype, no associations were observed, but the moderate heritability and prediction accuracy indicate a moderately polygenic trait.

Clinical Value of Prognostic Nutritional Index in Prediction of the Presence and Severity of Neonatal Sepsis

Purpose

The prognostic nutritional index (PNI) is a common indicator of nutritional and inflammatory status and is associated with various diseases such as cancer, cardiovascular diseases and infectious diseases. However, to date, no study has concentrated on the role of PNI in assessing and predicting the presence and severity of neonatal sepsis. Therefore, the present study aimed to explore the association of the PNI with the presence and severity of neonatal sepsis.

Materials and Methods

A total of 1196 neonates with suspected sepsis were enrolled in this study and their complete clinical and laboratory data were collected. PNI was calculated as serum albumin (g/L) + 5 × total lymphocyte count (10⁹/L). Multivariate logistic regression analysis was performed to identify the risk factors for the presence and severity of neonatal sepsis. Receiver operating characteristic (ROC) curve analysis was performed to evaluate the predictive value of PNI. All statistical analyses were performed using the statistical package SPSS 24.0.

Results

PNI was lower in neonates with sepsis and decreased significantly with the severity of sepsis. The correlation analysis demonstrated that the PNI was negatively correlated with the levels of the inflammatory marker procalcitonin (PCT) and C-reactive protein (CRP), and the length of hospital stay. Multivariate logistic regression analysis revealed that the PNI was independently and inversely associated with the presence and severity of neonatal sepsis. The area under the ROC curve of the PNI was 0.64 (95% confidence interval (CI): 0.61–0.67, P < 0.001) for severe sepsis and 0.69 (95% CI: 0.60–0.78, P < 0.001) for septic shock. In addition, our data revealed that PNI was also independently correlated with the length of hospital stay.

Conclusion

PNI is an independent predictor for the presence and severity of neonatal sepsis.

Influenza: Toward understanding the immune response in the young

Annually influenza causes a global epidemic resulting in 290,000 to 650,000 deaths and extracts a massive toll on healthcare and the economy. Infants and children are more susceptible to infection and have more severe symptoms than adults likely mitigated by differences in their innate and adaptive immune responses. While it is unclear the exact mechanisms with which the young combat influenza, it is increasingly understood that their immune responses differ from adults. Specifically, underproduction of IFN-γ and IL-12 by the innate immune system likely hampers viral clearance while upregulation of IL-6 may create excessive damaging inflammation. The infant's adaptive immune system preferentially utilizes the Th-2 response that has been tied to γδ T cells and their production of IL-17, which may be less advantageous than the adult Th-1 response for antiviral immunity. This differential immune response of the young is considered to serve as a unique evolutionary adaptation such that they preferentially respond to infection broadly rather than a pathogen-specific one generated by adults. This unique function of the young immune system is temporally, and possibly mechanistically, tied to the microbiota, as they both develop in coordination early in life. Additional research into the relationship between the developing microbiota and the immune system is needed to develop therapies effective at combating influenza in the youngest and most vulnerable of our population.

Maternal-fetal immunologic response to SARS-CoV-2 infection in a symptomatic vulnerable population: A prospective cohort

BACKGROUND

COVID-19 disproportionally affects pregnant women and their newborn, yet little is known about the variables that modulate the maternal-fetal immune response to infection.

METHODS

We prospectively studied socioeconomic, biologic and clinical factors affecting humoral immunity in 87 unvaccinated pregnant women admitted to hospital in the Buenos Aires metropolitan area for symptoms consistent with COVID-19 disease.

RESULTS

The number of days between symptom onset and childbirth predicted maternal and newborn virus Spike protein Receptor Binding Domain (RBD)-specific IgG. These findings suggest newborns may benefit less when mothers deliver soon after COVID-19 infection. Similarly, a longer time between symptom onset and birth predicted higher in utero transfer of maternal IgG and its concentration in cord blood. Older gestational ages at birth were associated with lower maternal IgG: cord blood IgG ratios. Eighty seven percent of women with confirmed SARS-CoV-2 infection developed RBD-specific IgA responses in breast milk within 96 h of childbirth. IgA was not significantly associated with time from infection but correlated with maternal serum IgG and placental transfer.

CONCLUSIONS

These results demonstrate the combined role of biologic, clinical and socioeconomic variables associated with maternal SARS-CoV-2 RBD-specific antibodies and supports early vaccination strategies for COVID-19 in socioeconomically vulnerable pregnant women.

Vaccine exposure during pregnancy among privately and publicly insured women in the United States, 2016-2018

BACKGROUND

Vaccine use during pregnancy affects maternal and infant health. Many women do not receive vaccines recommended during pregnancy; conversely, inadvertent exposure to vaccines contraindicated or not recommended during pregnancy may occur. We assessed exposure to two recommended vaccines and two vaccines not recommended during pregnancy among privately and Medicaid-insured women in the United States.

METHODS

This study includes a retrospective cohort of pregnancies in women aged 12-55 years resulting in live birth, spontaneous abortion, or stillbirth identified in the IBM® MarketScan® Commercial, Blue Health Intelligence® (BHI®) Commercial, and IBM MarketScan Multi-State Medicaid Databases from August 1, 2016, to December 31, 2018. Gestational age at vaccination was determined using a validated algorithm. We examined vaccines (1) recommended by the Centers for Disease Control and Prevention Advisory Committee on Immunization Practices (ACIP) (tetanus, diphtheria, and acellular pertussis [Tdap]; inactivated influenza) and (2) not recommended (human papillomavirus [HPV]) or contraindicated (measles, mumps, and rubella [MMR]).

RESULTS

We identified 496,771 (MarketScan Commercial), 858,961 (BHI), and 289,573 (MarketScan Medicaid) pregnancies (approximately 75% aged 20-34 years). Across these three databases, 52.1%, 50.3%, and 31.3% of pregnancies, respectively, received Tdap, most often at a gestational age of 28 weeks, and influenza vaccination occurred in 32.1%, 30.8%, and 18.0% of pregnancies, respectively. HPV vaccination occurred in < 0.2% of pregnancies, mostly in the first trimester among women aged 12-19 years, and MMR was administered in < 0.1% of pregnancies. Use of other contraindicated vaccines per ACIP (e.g., varicella, live attenuated influenza) was rare.

CONCLUSION

Maternal vaccination with ACIP-recommended vaccines was suboptimal among privately and Medicaid-insured patients, with lower vaccination coverage among Medicaid-insured pregnancies than their privately insured counterparts. Inadvertent exposure to contraindicated vaccines during pregnancy was rare. This study evaluated only vaccinations reimbursed among insured populations and may have limited generalizability to uninsured populations.

Coadministration of Anti-Viral Monoclonal Antibodies With Routine Pediatric Vaccines and Implications for Nirsevimab Use: A White Paper

Routine childhood vaccinations are key for the protection of children from a variety of serious and potentially fatal diseases. Current pediatric vaccine schedules mainly cover active vaccines. Active vaccination in infants is a highly effective approach against several infectious diseases; however, thus far, for some important viral pathogens, including respiratory syncytial virus (RSV), vaccine development and license by healthcare authorities have not been accomplished. Nirsevimab is a human-derived, highly potent monoclonal antibody (mAb) with an extended half-life for RSV prophylaxis in all infants. In this manuscript, we consider the potential implications for the introduction of an anti-viral mAb, such as nirsevimab, into the routine pediatric vaccine schedule, as well as considerations for coadministration. Specifically, we present evidence on the general mechanism of action of anti-viral mAbs and experience with palivizumab, the only approved mAb for the prevention of RSV infection in preterm infants, infants with chronic lung disease of prematurity and certain infants with hemodynamically significant heart disease. Palivizumab has been used for over two decades in infants who also receive routine vaccinations without any alerts concerning the safety and efficacy of coadministration. Immunization guidelines (Advisory Committee on Immunization Practices, Joint Committee on Vaccination and Immunization, National Advisory Committee on Immunization, Centers for Disease Control and Prevention, American Academy of Pediatrics, The Association of the Scientific Medical Societies in Germany) support coadministration of palivizumab with routine pediatric vaccines, noting that immunobiologics, such as palivizumab, do not interfere with the immune response to licensed live or inactivated active vaccines. Based on the mechanism of action of the new generation of anti-viral mAbs, such as nirsevimab, which is highly specific targeting viral antigenic sites, it is unlikely that it could interfere with the immune response to other vaccines. Taken together, we anticipate that nirsevimab could be concomitantly administered to infants with routine pediatric vaccines during the same clinic visit.

Premature birth: topics in physiology and pharmacological characteristics

OBJECTIVE

To review the main physiological and pharmacological changes related to prematurity, to promote the evidence-based clinical practice.

METHODS

This is a narrative review whose research was carried out in the ScienceDirect and Medline databases via PubMed, searching for articles in any language from January 2000 to February 2020.

RESULTS

Premature newborns are born before completing the maturation process that prepares them for extrauterine life, which occurs especially in the last weeks of pregnancy. Therefore, they have their own characteristics in development. Several physiological peculiarities stand out, such as disturbances in glucose regulation, adrenal function, thermoregulation, immunity, in addition to changes in liver, renal and respiratory functions. Pharmacological aspects were also highlighted, involving pharmacokinetics and pharmacodynamics.

CONCLUSIONS

Despite the recent advances in prematurity, it is still an area with many uncertainties, since several changes occur quickly and there are ethical issues that make studies difficult. Thus, it is clear that the therapeutic management of premature infants is still very much based on clinical practice.

Factors That Influence Infant Immunity and Vaccine Responses

The neonatal period and early infancy are times of increased vulnerability to infection. The immune system of infants undergoes rapid changes and a number of factors can influence the maturation and function of the early infant immune system, amongst these factors are maternal infections and immunity. Infants who are HIV-exposed, but uninfected show important immune alterations, which are likely to be associated with the increased morbidity and mortality observed in these infants. Maternally derived antibodies are crucial in early life to protect infants from infection during the time when their own immune system is becoming more experienced and fully mature. However, maternal antibodies can also interfere with the infant's own antibody responses to primary vaccination. Preterm infants are particularly vulnerable to infection, having not had the opportunity to benefit from the transplacental transfer of maternal antibodies in late pregnancy. In addition, further differences have been observed in the innate and adaptive immune system between preterm and term infants. Here, we focus on maternal influences on the infant immune system, using HIV and maternal vaccination as examples and finish by considering how prematurity impacts infant immune responses to vaccination.

Clinical characteristics of severe neonatal enterovirus infection: a systematic review

Background

Enterovirus (EV) is a common cause of infection in neonates. Neonates are at high risk of enterovirus infection with serious clinical manifestations and high lethality. This review systematically summarized the clinical characteristics of neonates with severe enteroviral infection to provide evidence for the identification and treatment of severe neonatal EV infection.

Methods

PubMed, Embase, and Web of Science were searched for original studies on neonates with severe EV infections from January 1, 2000, to November 27, 2020. Two reviewers independently screened the literature, extracted the data, and performed a descriptive analysis.

Results

In total, 66 articles with 237 cases of severe neonatal enterovirus infection were included. All neonates developed severe complications. Among them, 46.0% neonates had hepatitis or coagulopathy, 37.1% had myocarditis, 11.0% had meningoencephalitis, and 5.9% had other complications such as hemophagocytic lymphohistiocytosis and pulmonary hemorrhage. The lethality rate of neonates with severe infection was 30.4%. The highest lethality rate was 38.6%, which was observed in neonates with myocarditis. In 70.5% neonates, the age at the onset of symptoms was less than 7 days. Coxsackievirus B infection was seen in 52.3% neonates. The most common symptoms included temperature abnormalities (127, 53.6%), rash (88, 37.1%), poor feeding (58, 24.5%), and respiratory symptoms (52, 21.9%). The main treatment included transfusion of empirical antibiotics (127, 53.6%), blood components (100, 42.2%), intravenous immunoglobulin (IVIG; 97, 40.9%), mechanical ventilation (51, 21.5%), and extracorporeal membrane oxygenation (ECMO; 43, 18.1%). Additionally, antiviral medications pleconaril (14, 5.9%) and pocapavir (3, 1.3%) were administered.

Conclusions

Lethality was high in neonates with severe enterovirus infection, especially in those complicated with myocarditis. The most common symptoms included temperature abnormalities, rash, and poor feeding. The chief supportive treatment consisted of transfusion of blood components, mechanical ventilation, and ECMO. Empirical antibiotics and IVIG were widely used. Antiviral medications included pocapavir and pleconaril; however, more clinical evidence regarding their efficacy is needed.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12887-021-02599-y.

Cord Blood-Based Approach to Assess Candidate Vaccine Adjuvants Designed for Neonates and Infants

Neonates and infants are particularly susceptible to infections, for which outcomes tend to be severe. Vaccination is a key strategy for preventing infectious diseases, but the protective immunity achieved through vaccination typically is weaker in infants than in healthy adults. One possible explanation for the poor acquisition of vaccine-induced immunity in infants is that their innate immune response, represented by toll-like receptors, is immature. The current system for developing pediatric vaccines relies on the confirmation of their safety and effectiveness in studies involving the use of mature animals or adult humans. However, creating vaccines for neonates and infants requires an understanding of their uniquely immature innate immunity. Here we review current knowledge regarding the innate immune system of neonates and infants and challenges in developing vaccine adjuvants for those children through analyses of cord blood.

R848 or influenza virus can induce potent innate immune responses in the lungs of neonatal mice

Innate immune responses are important to protect the neonatal lung, which becomes exposed to commensal and pathogenic microorganisms immediately after birth, at a time when both the lung and the adaptive immune system are still developing. How immune cells in the neonatal lung respond to innate immune stimuli, including toll-like receptor (TLR) agonists, or viruses, is currently unclear. To address this, adult and neonatal mice were intranasally administered with various innate immune stimuli, respiratory syncytial virus (RSV) or influenza virus and cytokine and chemokine levels were quantified. The neonatal lungs responded weakly to RSV and most stimuli but more strongly than adult mice to R848 and influenza virus, both of which activate TLR7 and the inflammasome. Notably, neonatal lungs also contained higher levels of cAMP, a secondary messenger produced following adenosine receptor signaling, than adult lungs and increased responsiveness to R848 was observed in adult mice when adenosine was coadministered. Our data suggest that the neonatal lung may respond preferentially to stimuli that coactivate TLR7 and the inflammasome and that these responses may be amplified by extracellular adenosine. Improved understanding of regulation of immune responses in the neonatal lung can inform the development of vaccine adjuvants for the young.

Preparing for Life: Plasma Proteome Changes and Immune System Development During the First Week of Human Life

Neonates have heightened susceptibility to infections. The biological mechanisms are incompletely understood but thought to be related to age-specific adaptations in immunity due to resource constraints during immune system development and growth. We present here an extended analysis of our proteomics study of peripheral blood-plasma from a study of healthy full-term newborns delivered vaginally, collected at the day of birth and on day of life (DOL) 1, 3, or 7, to cover the first week of life. The plasma proteome was characterized by LC-MS using our established 96-well plate format plasma proteomics platform. We found increasing acute phase proteins and a reduction of respective inhibitors on DOL1. Focusing on the complement system, we found increased plasma concentrations of all major components of the classical complement pathway and the membrane attack complex (MAC) from birth onward, except C7 which seems to have near adult levels at birth. In contrast, components of the lectin and alternative complement pathways mainly decreased. A comparison to whole blood messenger RNA (mRNA) levels enabled characterization of mRNA and protein levels in parallel, and for 23 of the 30 monitored complement proteins, the whole blood transcript information by itself was not reflective of the plasma protein levels or dynamics during the first week of life. Analysis of immunoglobulin (Ig) mRNA and protein levels revealed that IgM levels and synthesis increased, while the plasma concentrations of maternally transferred IgG1-4 decreased in accordance with their in vivo half-lives. The neonatal plasma ratio of IgG1 to IgG2-4 was increased compared to adult values, demonstrating a highly efficient IgG1 transplacental transfer process. Partial compensation for maternal IgG degradation was achieved by endogenous synthesis of the IgG1 subtype which increased with DOL. The findings were validated in a geographically distinct cohort, demonstrating a consistent developmental trajectory of the newborn's immune system over the first week of human life across continents. Our findings indicate that the classical complement pathway is central for newborn immunity and our approach to characterize the plasma proteome in parallel with the transcriptome will provide crucial insight in immune ontogeny and inform new approaches to prevent and treat diseases.

Protocol for a prospective cohort study: Prevention of Transmissions by Effective Colonisation Tracking in Neonates (PROTECT-Neo)

INTRODUCTION

Transmissions of opportunistic bacterial pathogens between neonates increase the risk of infections with negative repercussions, including higher mortality, morbidity and permanent disabilities. The probability of transmissions between patients is contingent on a set of intrinsic (patient-related) and extrinsic (ward-related) risk factors that are not clearly quantified. It is the dual objective of the Prevention of Transmissions by Effective Colonisation Tracking-Neo study to determine the density of transmission events in a level III neonatal intensive care unit (NICU) and to identify risk factors that may be causally associated with transmission events.

METHODS AND ANALYSIS

A full cohort of patients treated in a 17-bed level III NICU will be prospectively followed and transmission events between two or more patients will be documented. A transmission event occurs when isogenic isolates from two different patients can be identified. Isolates will be obtained by routine weekly screening. Isogenicity will be determined by whole-genome sequencing. During the study, relevant intrinsic and extrinsic risk factors will be recorded. Specimen and data will be collected for 1 year. We postulate that transmission density increases during episodes when demand for intensive care cannot be met by existing staff, and that threshold dynamics have a bearing on cohorting and hand hygiene performance. Poisson logistic regression, proportional hazard and multilevel competing risk models will be used to estimate the effect of explanatory variables.

ETHICS AND DISSEMINATION

This study has been approved by the local ethics committee (study ID 287/18). The results will be published in peer-reviewed medical journals, communicated to participants, the general public and all relevant stakeholders.

TRIAL REGISTRATION NUMBER

The German Clinical Trials Registry (DRKS00017733); Pre-results.

Transcriptional profiling of lung macrophages identifies a predictive signature for inflammatory lung disease in preterm infants

Lung macrophages mature after birth, placing newborn infants, particularly those born preterm, within a unique window of susceptibility to disease. We hypothesized that in preterm infants, lung macrophage immaturity contributes to the development of bronchopulmonary dysplasia (BPD), the most common serious complication of prematurity. By measuring changes in lung macrophage gene expression in preterm patients at risk of BPD, we show here that patients eventually developing BPD had higher inflammatory mediator expression even on the first day of life. Surprisingly, the ex vivo response to LPS was similar across all samples. Our analysis did however uncover macrophage signature genes whose expression increased in the first week of life specifically in patients resilient to disease. We propose that these changes describe the dynamics of human lung macrophage differentiation. Our study therefore provides new mechanistic insight into both neonatal lung disease and human developmental immunology.

Comparative Analysis of Global Gene Expression and Complement Components Levels in Umbilical Cord Blood from Preterm and Term Neonates: Implications for Significant Downregulation of Immune Response Pathways related to Prematurity

Background: Preterm birth is the most frequent cause of neonatal death, but its aetiology remains unclear. It has been suggested that the imbalance of immunological mechanisms responsible for maintaining pregnancy is contributing to preterm birth pathogenesis. We aimed to investigate global gene expression and the levels of several complement system components in umbilical cord blood samples from preterm neonates and compare them to term newborns. We sought to examine how differentially expressed genes could affect various immune-related pathways that are believed to be crucial factors in preterm birth. Material and methods: We enrolled 27 preterm infants (<37 weeks GA) and 52 term infants (>37 weeks GA), from which umbilical cord blood samples were collected. From these samples, peripheral blood mononuclear cells were isolated and subsequent RNA isolation was performed. We used Affymetrix Human Gene 2.1 ST Array Strip for microarray experiment and DAVID resources for bioinformatics analysis of the obtained data. Concentrations of C2, C3a, C5/C5a, C9, FactorD, Properdin were measured in umbilical cord blood plasma samples using multiplex fluorescent bead-based immunoassays using Luminex technology. Results: The levels of C3a and C5/5a were significantly elevated in preterm neonates compared to term babies, whereas C9 concentration was evidently increased in term infants. The expression of 250 genes was upregulated at least 2-fold and 3781 genes were downregulated at least 2-fold in preterm neonates in comparison with term infants. Functional annotation analysis revealed that in preterm infants in comparison to term babies there was a significant downregulation of genes encoding several Toll-like receptors, interleukins and genes involved in major signalling pathways (e.g. NF-κB, MAPK, TNF, Notch, JAK) and vital cellular processes (e.g. intracellular signal transduction, protein ubiquitination, protein transport, RNA splicing, DNA-templated transcription). Conclusions: Preterm birth results in immediate and long-term complications. Our results indicate that infants born prematurely show significant differences in complement components concentration and a downregulation of over 3,000 genes, involved mainly in various immune-related pathways, including innate immune response, phagocytosis and TLR function, when compared to full-term babies. Further studies on larger cohorts are needed to elucidate the role of immunity in prematurity.

Lysyl-tRNA Synthetase from Pseudomonas aeruginosa: Characterization and Identification of Inhibitory Compounds

Pseudomonas aeruginosa is an opportunistic pathogen that causes nosocomial infections and has highly developed systems for acquiring resistance against numerous antibiotics. The gene (lysS) encoding P. aeruginosa lysyl-tRNA synthetase (LysRS) was cloned and overexpressed, and the resulting protein was purified to 98% homogeneity. LysRS was kinetically evaluated, and the Km values for the interaction with lysine, adenosine triphosphate (ATP), and tRNALys were determined to be 45.5, 627, and 3.3 µM, respectively. The kcatobs values were calculated to be 13, 22.8, and 0.35 s-1, resulting in kcatobs/KM values of 0.29, 0.036, and 0.11 s-1µM-1, respectively. Using scintillation proximity assay technology, natural product and synthetic compound libraries were screened to identify inhibitors of function of the enzyme. Three compounds (BM01D09, BT06F11, and BT08F04) were identified with inhibitory activity against LysRS. The IC50 values were 17, 30, and 27 µM for each compound, respectively. The minimum inhibitory concentrations were determined against a panel of clinically important pathogens. All three compounds were observed to inhibit the growth of gram-positive organisms with a bacteriostatic mode of action. However, two compounds (BT06F11 and BT08F04) were bactericidal against cultures of gram-negative bacteria. When tested against human cell cultures, BT06F11 was not toxic at any concentration tested, and BM01D09 was toxic only at elevated levels. However, BT08F04 displayed a CC50 of 61 µg/mL. In studies of the mechanism of inhibition, BM01D09 inhibited LysRS activity by competing with ATP for binding, and BT08F04 was competitive with ATP and uncompetitive with the amino acid. BT06F11 inhibited LysRS activity by a mechanism other than substrate competition.

Evaluation of the Induction of Cell-Mediated Immunity Against Candida albicans in a Model of Cutaneous Infection in Newborn 0-Day-Old Mice

Candida albicans is a commensal fungus of the skin and mucous membranes in humans, but it is also responsible for mucocutaneous and systemic infections in immunocompromised patients like low birth weight neonates and premature newborns. The epicutaneous application of C. albicans is widely used to study the immune response against this pathogen in adult mice models. However, the immune response of newborns against infections caused by the genus Candida is poorly understood. In order to mimic premature human infection, we developed a model of C. albicans epicutaneous infection in newborn mice. We found that yeasts were able to colonize while the pseudohyphae invaded the epidermis. Recruitment of polymorphonuclear and mononuclear cells at the infection zone was observed. Fungal invasion, fungal burden and cellular infiltration displayed a time- and dose-dependent response. Interestingly, newborn mice were able to control C. albicans primary infection. Finally, we showed that the epicutaneous infection of C. albicans in newborn mice at birth results in the induction of cell-mediated immunity as evinced by delayed-type hypersensitivity assays.

The development of pain circuits and unique effects of neonatal injury

Pain is a necessary sensation that prevents further tissue damage, but can be debilitating and detrimental in daily life under chronic conditions. Neuronal activity strongly regulates the maturation of the somatosensory system, and aberrant sensory input caused by injury or inflammation during critical periods of early postnatal development can have prolonged, detrimental effects on pain processing. This review will outline the maturation of neuronal circuits responsible for the transmission of nociceptive signals and the generation of pain sensation-involving peripheral sensory neurons, the spinal cord dorsal horn, and brain-in addition to the influences of the neuroimmune system on somatosensation. This summary will also highlight the unique effects of neonatal tissue injury on the maturation of these systems and subsequent consequences for adult somatosensation. Ultimately, this review emphasizes the need to account for age as an independent variable in basic and clinical pain research, and importantly, to consider the distinct qualities of the pediatric population when designing novel strategies for pain management.

Trends, determinants, and newborn mortality related to thermal care and umbilical cord care practices in South Asia

BACKGROUND

Although child mortality has decreased over the last several decades, neonatal mortality has declined less substantially. In South Asia, neonatal deaths account for the majority of all under-five deaths, calling for further study on newborn care practices. We assessed five key practices: immediate drying and wrapping, delayed bathing, immediate skin-to-skin contact after birth, cutting the umbilical cord with a clean instrument, and substances placed on the cord.

METHODS

Using data from Demographic and Health Surveys conducted in Bangladesh, India, and Nepal between 2005 and 2016, we examined trends in coverage of key practices and used multivariable logistic regression to analyze predictors of thermal care and hygienic cord care practices and their associations with neonatal mortality among home births. The analysis excluded deaths on the first day of life to ensure that the exposure to newborn care practices would have preceded the outcome. Given limited neonatal mortality events in Bangladesh and Nepal, we pooled data from these countries.

RESULTS

We found that antenatal care and skilled birth attendance was associated with an increase in the odds of infants' receipt of the recommended practices among home births. Hygienic cord care was significantly associated with newborn survival. After controlling for other known predictors of newborn mortality in Bangladesh and Nepal, antiseptic cord care was associated with an 80% reduction in the odds of dying compared with dry cord care. As expected, skilled care during pregnancy and birth was also associated with newborn survival. Missing responses regarding care practices were common for newborns that died, suggesting that recall or report of details surrounding the traumatic event of a loss of a child may be incomplete.

CONCLUSIONS

This study highlights the importance of maternal and newborn care and services for newborn survival in South Asia, particularly antenatal care, skilled birth attendance, and antiseptic cord care.

Association between Neonatal Whole Blood Iron Content and Cytokines, Adipokines, and Other Immune Response Proteins

(1) Background: High iron associates with inflammation and type 1 diabetes (T1D). Iron is essential not only for neonatal development but also for infectious microorganisms. The neonatal immune system is immature, and innate immunity prevails before immunocompetence develops. (2) Methods: In 398 newborns from the Danish Newborn Screening Biobank, we examined if whole blood iron (WB-Iron) content were associated with cytokines, adipokines, C-reactive protein (CRP), and mannose-binding lectin (MBL) in non-infected healthy neonates, and if these associations differed in newborns who later developed T1D (cases) (n = 199). WB-Iron was quantified using laser ablation inductively coupled plasma mass spectrometry on the neonatal dried blood spots. For each analyte, the relative change (RC) in the mean level was modeled by robust log-normal regression. (3) Results: A one unit increase in neonatal WB-Iron was associated with a 38% decrease in mean interleukin (IL)-6 levels (0.62; 95% CI: 0.40–0.95, p = 0.03), and a 37% decrease in mean MBL levels (0.63; 95% CI: 0.41–0.95, p = 0.03), but was not statistically significant after correction for multiple testing. (4) Conclusions: In summary, we found that higher neonatal WB-iron content was inversely associated with IL-6 and MBL, which may increase susceptibility to infections.

Effect of betamethasone, indomethacin and fenoterol on neonatal and maternal mononuclear cells stimulated with Escherichia coli

Despite considerable progress in the field of perinatal care, infectious diseases, especially when caused by gram negative bacteria, remain a major reason for neonatal morbidity and mortality. Notably infants born prematurely and those with very low birth weight are at risk due to their immature and deficient immune system and their prolonged hospitalization which promotes nosocomial infections. In case of impending preterm birth, betamethasone is given to induce lung maturation and tocolytic agents like indomethacin or fenoterol are administered to suppress premature labor. The aim of this study was to analyze the effects of these drugs on the immune system of mothers and neonates. Therefore, mononuclear cells from cord blood and peripheral maternal blood were stimulated with Escherichia coli and incubated with betamethasone, indomethacin and fenoterol. Subsequently the effect of the treatment on cytokine production was determined. Betamethasone alone and in combination with tocolytic agents inhibited the production of pro- and anti-inflammatory cytokines. Not only does betamethasone dampen the immune response by reducing the production of cytokines, it also has a variety of other detrimental short- and long-term effects on the neonate. In conclusion we would recommend using biological markers to determine if premature labor actually leads to preterm birth and subsequently administer betamethasone only to mothers giving birth prematurely.

Characterisation of morphological differences in well-differentiated nasal epithelial cell cultures from preterm and term infants at birth and one-year

BACKGROUND

Innate immune responses of airway epithelium are important defences against respiratory pathogens and allergens. Newborn infants are at greater risk of severe respiratory infections compared to older infants, while premature infants are at greater risk than full term infants. However, very little is known regarding human neonatal airway epithelium immune responses and whether age-related morphological and/or innate immune changes contribute to the development of airway disease.

METHODS

We collected nasal epithelial cells from 41 newborn infants (23 term, 18 preterm) within 5 days of birth. Repeat sampling was achieved for 24 infants (13 term, 11 preterm) at a median age of 12.5 months. Morphologically- and physiologically-authentic well-differentiated primary paediatric nasal epithelial cell (WD-PNEC) cultures were generated and characterised using light microscopy and immunofluorescence.

RESULTS

WD-PNEC cultures were established for 15/23 (65%) term and 13/18 (72%) preterm samples at birth, and 9/13 (69%) term and 8/11 (73%) preterm samples at one-year. Newborn and infant WD-PNEC cultures demonstrated extensive cilia coverage, mucous production and tight junction integrity. Newborn WD-PNECs took significantly longer to reach full differentiation and were noted to have much greater proportions of goblet cells compared to one-year repeat WD-PNECs. No differences were evident in ciliated/goblet cell proportions between term- and preterm-derived WD-PNECs at birth or one-year old.

CONCLUSION

We describe the successful generation of newborn-derived WD-PNEC cultures and their revival from frozen. We also compared the characteristics of WD-PNECs derived from infants born at term with those born prematurely at birth and at one-year-old. The development of WD-PNEC cultures from newborn infants provides a powerful and exciting opportunity to study the development of airway epithelium morphology, physiology, and innate immune responses to environmental or infectious insults from birth.

Modulation of innate immune responses at birth by prenatal malaria exposure and association with malaria risk during the first year of life

BACKGROUND

Factors driving inter-individual differences in immune responses upon different types of prenatal malaria exposure (PME) and subsequent risk of malaria in infancy remain poorly understood. In this study, we examined the impact of four types of PME (i.e., maternal peripheral infection and placental acute, chronic, and past infections) on both spontaneous and toll-like receptors (TLRs)-mediated cytokine production in cord blood and how these innate immune responses modulate the risk of malaria during the first year of life.

METHODS

We conducted a birth cohort study of 313 mother-child pairs nested within the COSMIC clinical trial (NCT01941264), which was assessing malaria preventive interventions during pregnancy in Burkina Faso. Malaria infections during pregnancy and infants' clinical malaria episodes detected during the first year of life were recorded. Supernatant concentrations of 30 cytokines, chemokines, and growth factors induced by stimulation of cord blood with agonists of TLRs 3, 7/8, and 9 were measured by quantitative suspension array technology. Crude concentrations and ratios of TLR-mediated cytokine responses relative to background control were analyzed.

RESULTS

Spontaneous production of innate immune biomarkers was significantly reduced in cord blood of infants exposed to malaria, with variation among PME groups, as compared to those from the non-exposed control group. However, following TLR7/8 stimulation, which showed higher induction of cytokines/chemokines/growth factors than TLRs 3 and 9, cord blood cells of infants with evidence of past placental malaria were hyper-responsive in comparison to those of infants not-exposed. In addition, certain biomarkers, which levels were significantly modified depending on the PME category, were independent predictors of either malaria risk (GM-CSF TLR7/8 crude) or protection (IL-12 TLR7/8 ratio and IP-10 TLR3 crude, IL-1RA TLR7/8 ratio) during the first year of life.

CONCLUSIONS

These findings indicate that past placental malaria has a profound effect on fetal immune system and that the differential alterations of innate immune responses by PME categories might drive heterogeneity between individuals to clinical malaria susceptibility during the first year of life.

Postnatal changes in epigenetic modifications of neutrophils of foals are associated with increased ROS function and regulation of neutrophil function

Neonates of all species, including foals, are highly susceptible to infection, and neutrophils play a crucial role in innate immunity to infection. Evidence exists that neutrophils of neonatal foals are functionally deficient during the first weeks of life, including expression of cytokine genes such as IFNG. We hypothesized that postnatal epigenetic changes were likely to regulate the observed age-related changes in foal neutrophils. Using ChIP-Seq, we identified significant differences in trimethylated histone H3 lysine 4, an epigenetic modification associated with active promoters and enhancers, in neutrophils in foals at 30 days of age relative to 1 day of age. These chromatin changes were associated with genes implicated in immune responses and were consistent with age-related changes in neutrophil functional responses including ROS generation and IFN expression. Postnatal changes in epigenetic modifications suggest that environmentally-mediated cues help to promote maturation of neutrophil functional responses. Elucidating the environmental triggers and their signaling pathways could provide a means for improving innate immune responses of neonates to improve their ability to combat infectious diseases.

Epidemiology and Immune Pathogenesis of Viral Sepsis

Sepsis is a life-threatening organ dysfunction caused by a dysregulated host response to infection. Sepsis can be caused by a broad range of pathogens; however, bacterial infections represent the majority of sepsis cases. Up to 42% of sepsis presentations are culture negative, suggesting a non-bacterial cause. Despite this, diagnosis of viral sepsis remains very rare. Almost any virus can cause sepsis in vulnerable patients (e.g., neonates, infants, and other immunosuppressed groups). The prevalence of viral sepsis is not known, nor is there enough information to make an accurate estimate. The initial standard of care for all cases of sepsis, even those that are subsequently proven to be culture negative, is the immediate use of broad-spectrum antibiotics. In the absence of definite diagnostic criteria for viral sepsis, or at least to exclude bacterial sepsis, this inevitably leads to unnecessary antimicrobial use, with associated consequences for antimicrobial resistance, effects on the host microbiome and excess healthcare costs. It is important to understand non-bacterial causes of sepsis so that inappropriate treatment can be minimised, and appropriate treatments can be developed to improve outcomes. In this review, we summarise what is known about viral sepsis, its most common causes, and how the immune responses to severe viral infections can contribute to sepsis. We also discuss strategies to improve our understanding of viral sepsis, and ways we can integrate this new information into effective treatment.

Effect of Pasteurella multocida Soluble Antigen Stimulation on the In Vitro Response of Peripheral Blood Mononuclear Cells of Holstein Calves

The expressions of cytokines mRNA, including interleukin-4 (IL-4), interleukin- 17A (IL-17A) and interferon-gamma (IFN-γ), their master regulatory transcription factors, and signal transducers and activator of transcription (STAT) stimulated in vitro with Pasteurella (P.) multocida soluble antigen were examined in peripheral blood mononuclear cells (PBMC) from Holstein calves. The healthy Holstein calves were divided into three groups; 2 weeks old (2W Group, N=8), 6 weeks old (6W Group, N=8), and 10 weeks old (10W Group, N=8). PBMC were stimulated in vitro by soluble antigen of P. multocida. There were significantly lower expressions of IFN-γ, IL-4, and STAT-6 mRNA of PBMC stimulated with P. multocida soluble antigen in the 2W Group compared to that in the 10W Group. Expression of IL-17A and IFN-γ in PBMC stimulated with P. multocida soluble antigen were significantly higher compared with the PBMC without stimulation in the 6W groups. The results of the present study demonstrated that 2W old calves had decreased cytokine expression of PBMC when in vitro stimulated with P. multocida soluble antigen in vitro.

CD8+ T Cells Prevent Lethality from Neonatal Murine Roseolovirus Infection

A recently described mouse homolog of the human roseoloviruses, murine roseolovirus (MRV), causes loss of peripheral and thymic CD4+ cells during neonatal infection of BALB/c mice. Despite significant disruptions to the normal adaptive immune response, infected BALB/c mice reproducibly recover from infection, consistent with prior studies on a related virus, mouse thymic virus. In this article, we show that, in contrast to published studies on mouse thymic virus, MRV appears to robustly infect neonatal C57BL/6 (B6) mice, causing severe depletion of thymocytes and peripheral T cells. Moreover, B6 mice recovered from infection. We investigated the mechanism of thymocyte and T cell loss, determining that the major thymocyte subsets were infected with MRV; however, CD4+ and CD4+CD8- T cells showed increased apoptosis during infection. We found that CD8+ T cells populated MRV-infected thymi. These CD8+ T cells expressed markers of activation, had restricted TCR repertoire, and accumulated intracellular effector proteins, consistent with a cytotoxic lymphocyte phenotype and suggesting their involvement in viral clearance. Indeed, absence of CD8+ T cells prevented recovery from MRV infection and led to lethality in infected animals, whereas B cell-deficient mice showed CD4+ T cell loss but recovered from infection without lethality. Thus, these results demonstrate that CD8+ T cells are required for protective immunity against a naturally occurring murine pathogen that infects the thymus and establish a novel infection model for MRV in B6 mice, providing the foundation for detailed future studies on MRV with the availability of innumerable mutant mice on the B6 background.

Infectious crystalline keratopathy

Infectious crystalline keratopathy was first reported by Gorovoy and colleagues in 1983 when they identified bacteria colonizing a cornea after a penetrating keratoplasty. Subsequent cases have elaborated on the organisms responsible and the management outcomes. Patients present with a white or gray branching opacity originating from an epithelial defect, commonly after a penetrating keratoplasty. Local immunosuppression contributes to the quiescent nature and the limited inflammatory response associated with infectious crystalline keratopathy. Diagnosis of the infective pathogens may be difficult, with a corneal scraping often being too superficial to obtain an adequate specimen. A biofilm is present that advantages microorganism survival, reduces antibiotic bioavailability, and inhibits diagnostic microbial detection. Treatment begins with topical antimicrobials, initially broad spectrum and then targeted to microorganism sensitivity. Adjunctive therapies to enhance the efficacy of treatment include disruption of the microorganism biofilm by laser, intrastromal antibiotics, and keratectomy. In recalcitrant cases, or where corneal scarring ensues, corneal transplantation is required.

Ventriculoperitoneal shunts in neonates: a retrospective study of outcomes with antibiotic-impregnated catheters and a modified peri-operative antibiotic protocol

BACKGROUND

CSF infection is a significant complication of ventriculoperitoneal (VP) shunts and results in prolonged hospital stay, developmental delay and decreased quality of life. To decrease the high rates of neonatal VP shunt infections, an updated clinical guideline that included the use of antibiotic-impregnated shunts and a revised peri-operative antibiotic protocol was introduced in our neonatal unit. In this study, we evaluated the efficacy of these new guidelines in reducing the CSF shunt infection rates.

METHODS

A retrospective cohort study of neonates (≤28 days) who had VP shunt insertions in our unit.

RESULTS

24 neonates in the first epoch received plain silastic shunt catheters (Feb 2002-April 2007), and 23 in the second epoch (August 2007-July 2015) received AIS catheters and a revised perioperative antibiotic protocol. Patient demographics were similar between both cohorts. Shunt related CSF infections were reduced in epoch 2 (2/23, 8.7%) compared to epoch 1 (5/24, 20.8%), but the results were not statistically significant (OR 0.36 (0.063-2.090); p = 0.256). Amongst neonates that needed VP shunt revision due to any cause, the median time interval between insertion to revision was significantly later in epoch 2 (epoch 1, 48 days (3-99); epoch 2, 148 days (20-396); p = 0.013).

CONCLUSIONS

AIS catheters and a 48-hour perioperative antibiotic regimen may be beneficial in neonatal hydrocephalus. Adequately powered RCTs in the neonatal population are needed to confirm these findings.

The Helicobacter pylori type IV secretion system promotes IL-8 synthesis in a model of pediatric airway epithelium via p38 MAP kinase

Epidemiologic studies have reported an inverse relationship between childhood Helicobacter pylori infection and development of allergic asthma. Because lung epithelium plays an important role in allergic asthma pathogenesis, we hypothesized that H. pylori may directly influence airway epithelial cell innate immune function, particularly in early childhood. To test our hypothesis, we established an in vitro H. pylori infection model using primary tracheobronchial epithelial cell cultures derived from infant, juvenile and adult rhesus monkeys. Airway epithelial cell cultures were infected with wild-type or cag pathogenicity island mutant H. pylori strains, followed by evaluation of IL-8 and IL-6 protein synthesis. We found that H. pylori primarily increased IL-8 synthesis in a MOI and age-dependent fashion, with a greater than 4-fold induction in infant versus adult cultures. H. pylori-induced IL-8 synthesis in infant and juvenile cultures was significantly reduced by cag pathogenicity island mutants, indicating a requirement for the type IV secretion system. Although peptidoglycan recognition of nucleotide binding oligomerization domain-containing protein 1 (NOD1) and NF-kappaB have been implicated as key cytokine signaling molecules for H. pylori infection in gastric epithelium, NOD1 (ML130) or NF-kappaB (JSH-23) inhibitors minimally affected IL-8 synthesis in airway epithelial cell cultures following H. pylori infection. In contrast, inhibition of the p38 MAP kinase pathway (SB203580) resulted in almost complete suppression of H. pylori-induced IL-8 synthesis. Collectively, these results indicate that H. pylori can preferentially elicit IL-8 synthesis in a model of pediatric airway epithelium using the type IV secretion system via p38 MAP kinase.

The molecular signature of murine T cell homeostatic proliferation reveals both inflammatory and immune inhibition patterns

T lymphocyte homeostatic proliferation, driven by the engagement of T cell antigen receptor with self-peptide/major histocompatibility complexes, and signaling through the common γ-chain-containing cytokine receptors, is critical for the maintenance of the T cell compartment and is regulated by the Fas death receptor (Fas, CD95). In the absence of Fas, Fas-deficient lymphoproliferation spontaneous mutation (lpr) mice accumulate homeostatically expanded T cells. The functional consequences of sequential rounds of homeostatic expansion are not well defined. We thus examined the gene expression profiles of murine wild-type and Fas-deficient lpr CD8+ T cell subsets that have undergone different amounts of homeostatic proliferation as defined by their level of CD44 expression, and the CD4-CD8-TCRαβ+ T cell subset that results from extensive homeostatic expansion of CD8+ T cells. Our studies show that recurrent T cell homeostatic proliferation results in global gene expression changes, including the progressive upregulation of both cytolytic proteins such as Fas-Ligand and granzyme B as well as inhibitory proteins such as programmed cell death protein 1 (PD-1) and lymphocyte activating 3 (Lag3). These findings provide an explanation for how augmented T cell homeostatic expansion could lead to the frequently observed clinical paradox of simultaneous autoinflammatory and immunodeficiency syndromes and provide further insight into the regulatory programs that control chronically stimulated T cells.

Genome-wide identification of lineage and locus specific variation associated with pneumococcal carriage duration

Streptococcus pneumoniae is a leading cause of invasive disease in infants, especially in low-income settings. Asymptomatic carriage in the nasopharynx is a prerequisite for disease, but variability in its duration is currently only understood at the serotype level. Here we developed a model to calculate the duration of carriage episodes from longitudinal swab data, and combined these results with whole genome sequence data. We estimated that pneumococcal genomic variation accounted for 63% of the phenotype variation, whereas the host traits considered here (age and previous carriage) accounted for less than 5%. We further partitioned this heritability into both lineage and locus effects, and quantified the amount attributable to the largest sources of variation in carriage duration: serotype (17%), drug-resistance (9%) and other significant locus effects (7%). A pan-genome-wide association study identified prophage sequences as being associated with decreased carriage duration independent of serotype, potentially by disruption of the competence mechanism. These findings support theoretical models of pneumococcal competition and antibiotic resistance.

Intracellular DNA sensing pathway of cGAS-cGAMP is decreased in human newborns and young children

Newborns are highly susceptible to DNA virus infections, which may result from the characteristics of neonatal innate immune systems. Here we analyzed for the first time the development of innate immune sensing and signaling of intracellular DNA virus infection in human newborns and young children. Both mRNA and protein expression of cGAS, an intracellular DNA sensor, were shown to be significantly reduced in neonatal peripheral blood mononuclear cells (PBMCs). In addition, cGAS expression in neonatal PBMCs could be induced upon herpes simplex virus type 1 (HSV-1) or interferon-α (IFNα) stimulation. Furthermore, production of the second messenger cGAMP and activation of the transcriptional factor IRF3 was severely decreased in neonatal cord blood mononuclear cells (CBMCs) or PBMCs compared with adults. In contrast, the downstream signaling STING-TBK1-IRF3 appeared to be functional in neonatal PBMCs, as demonstrated by the fact that IRF3 phosphorylation and IFNβ production in these cells could be activated by cGAMP. Intriguingly, decreased expression of cGAS in neonatal cells can be rescued by DNA demethylation, with concomitant enhancement in IFNβ induction by HSV-1. Thus, cGAS restoration or STING stimulation by small molecules during infancy might improve the age-dependent susceptibility to DNA virus infection.

Potential biomarkers for effective screening of neonatal sepsis infections: An overview

Neonatal sepsis, a clinical disorder developed by bacterial blood stream infections (BSI) in neonates, is one of the serious global public health problems that must be addressed. More than one million of the estimated global newborn deaths per year are occurred due to severe infections. The genesis of the infection is divided into early-onset sepsis (EOS) and late-onset sepsis (LOS) of the disease. The clinical complications of neonatal sepsis may be associated with bronchopulmonary dysplasia, ductus arteriosus and necrotizing enterocolitis. The clinical diagnosis and treatment of neonatal sepsis is highly complicated. Over the past few years distinct biomarkers have been identified. Most widely used biomarkers are C-reactive protein, Procalcitonin (PCT) and Serum amyloid A (SAA). Until recently, many potential biomarkers including Cell Surface antigens and Bacterial surface antigens and genetic biomarkers are being investigated. Protein biomarkers, cytokines and chemokines are getting much interest for identification of neonatal sepsis infection.

Umbilical cord-care practices in low- and middle-income countries: a systematic review

Background

Neonatal sepsis is the third leading cause of deaths for infants in their first month of life. The newly cut umbilical cord can be a pathway for bacteria that can cause newborn sepsis and death. Optimal umbilical cord care practices for newborns and during the first week of life, especially in settings with poor hygiene, has the potential to avoid these preventable neonatal deaths. The purpose of this review of cord care practices is to assist in the development of behavior-change strategies to support introduction of novel cord-care regimens, particularly 7.1% chlorhexidine digluconate for umbilical cord care.

Methods

We searched domestic and international databases for articles that were published in English between January 1, 2000, and August 24, 2016. We found 321 articles and reviewed 65 full-text articles using standardized inclusion criteria. The primary criteria for inclusion was a description of substances applied to the umbilical cord stump in the days following birth.

Results

We included 46 articles in this review of umbilical cord-care practices. Articles included data from 15 low- and middle-income countries in sub-Saharan Africa (8 countries), Asia (5 countries), North Africa (1 country), and Latin America and the Caribbean (1 country). Findings from this review suggest that documentation of cord-care practices is not consistent throughout low- and middle-income countries, yet existing literature depicts a firm tradition of umbilical cord care in every culture. Cord-care practices vary by country and by regions or cultural groups within a country and employ a wide range of substances. The desire to promote healing and hasten cord separation are the underlying beliefs related to application of substances to the umbilical cord. The frequency of application of the substance (either the number of days or the number of times per day the substance was applied), and source and cost of products used is not well-characterized.

Conclusions

This desire to actively care for the umbilical cord of a newborn—as noted in the variety of cord care practices and beliefs identified in this review—points toward the need to contextualize any behavior change approach to align with the local culture.

Electronic supplementary material

The online version of this article (doi:10.1186/s12884-017-1250-7) contains supplementary material, which is available to authorized users.