Perinatal infection, inflammation, preterm birth, and brain injury: A review with proposals for future investigations

Computational Approaches for Predicting Preterm Birth and Newborn Outcomes

Preterm birth (PTB) and its associated morbidities are a leading cause of infant mortality and morbidity. Accurate predictive models and a better biological understanding of PTB-associated morbidities are critical in reducing their adverse effects. Increasing availability of multimodal high-dimensional data sets with concurrent advances in artificial intelligence (AI) have created a rich opportunity to gain novel insights into PTB, a clinically complex and multifactorial disease. Here, the authors review the use of AI to analyze 3 modes of data: electronic health records, biological omics, and social determinants of health metrics.

Impact of Maternal Environment and Inflammation on Fetal Neurodevelopment

During intrauterine life, external stimuli including maternal nutrition, lifestyle, socioeconomic conditions, anxiety, stress, and air pollution can significantly impact fetal development. The human brain structures begin to form in the early weeks of gestation and continue to grow and mature throughout pregnancy. This review aims to assess, based on the latest research, the impact of environmental factors on fetal and neonatal brain development, showing that oxidative stress and inflammation are implied as a common factor for most of the stressors. Environmental insults can induce a maternal inflammatory state and modify nutrient supply to the fetus, possibly through epigenetic mechanisms, leading to significant consequences for brain morphogenesis and neurological outcomes. These risk factors are often synergic and mutually reinforcing. Fetal growth restriction and preterm birth represent paradigms of intrauterine reduced nutrient supply and inflammation, respectively. These mechanisms can lead to an increase in free radicals and, consequently, oxidative stress, with well-known adverse effects on the offspring's neurodevelopment. Therefore, a healthy intrauterine environment is a critical factor in supporting normal fetal brain development. Hence, healthcare professionals and clinicians should implement effective interventions to prevent and reduce modifiable risk factors associated with an increased inflammatory state and decreased nutrient supply during pregnancy.

Akt/mTOR Pathway Agonist SC79 Inhibits Autophagy and Apoptosis of Oligodendrocyte Precursor Cells Associated with Neonatal White Matter Dysplasia

White matter dysplasia (WMD) in preterm infants due to intrauterine inflammation is caused by excessive apoptosis of oligodendrocyte precursor cells (OPCs). In recent years, studies have found that excessive autophagy and apoptosis are highly interconnected and important in infection and inflammatory diseases in general. Therefore, in this study, we aimed to confirm whether regulation of autophagy by using the Akt phosphorylation agonist SC79 can inhibit abnormal apoptosis of OPCs and promote myelin maturation and white matter development in neonatal rats with WMD. We investigated the effect of inflammation on oligodendrocyte development in P0 neonatal rats by intracerebellar injection of LPS, and collected brain tissue at P2 and P5. Immunohistochemical and immunofluorescence staining were used to evaluate white matter damage, while immunofluorescence staining, terminal deoxynucleotidyl transferase dUTP nick end labeling analysis (TUNEL), and western blotting were used to evaluate autophagy and apoptosis. First, we observed that white matter development was arrested and white matter fiber maturation was impaired in LPS-inflicted pups compared with those in the sham-operated group. Second, treatment with SC79 reduced the levels of LC3II, caspase 3, caspase 9, and Bax/Bcl-2 and increased the levels of p62, p-Akt, and p-mTOR in the brain tissue of neonatal rats. Finally, SC79 treatment inhibited OPC apoptosis by increasing the binding of Beclin 1 to Bcl-2, which promoted OPC differentiation and maturation. However, the opposite results were observed after rapamycin administration. Taken together, our results suggest that SC79 can inhibit the abnormal apoptosis of OPCs caused by excessive autophagy through the Akt/mTOR pathway and that SC79 is a potential therapeutic agent for WMD in preterm infants.

Antenatal Magnesium Sulfate Benefits Female Preterm Infants but Results in Poor Male Outcomes

Magnesium sulfate (MagSul) is used clinically to prevent eclamptic seizures during pregnancy and as a tocolytic for preterm labor. More recently, it has been implicated as offering neural protection in utero for at-risk infants. However, evidence is mixed. Some studies found that MagSul reduced the incidence of cerebral palsy (CP) but did not improve other measures of neurologic function. Others did not find any improvement in outcomes. Inconsistencies in the literature may reflect the fact that sex effects are largely ignored, despite evidence that MagSul shows sex effects in animal models of neonatal brain injury. The current study used retrospective infant data to assess differences in developmental outcomes as a function of sex and MagSul treatment. We found that on 18-month neurodevelopmental cognitive and language measures, preterm males treated with MagSul (n = 209) had significantly worse scores than their untreated counterparts (n = 135; p < 0.05). Female preterm infants treated with MagSul (n = 220), on the other hand, showed a cognitive benefit relative to untreated females (n = 123; p < 0.05). No significant effects of MagSul were seen among females on language (p > 0.05). These results have tremendous implications for risk-benefit considerations in the ongoing use of MagSul and may explain why benefits have been hard to identify in clinical trials when sex is not considered.

CD8+ T cells in brain injury and neurodegeneration

The interaction between the peripheral immune system and the brain is increasingly being recognized as an important layer of neuroimmune regulation and plays vital roles in brain homeostasis as well as neurological disorders. As an important population of T-cell lymphocytes, the roles of CD8+ T cells in infectious diseases and tumor immunity have been well established. Recently, increasing number of complex functions of CD8+ T cells in brain disorders have been revealed. However, an advanced summary and discussion of the functions and mechanisms of CD8+ T cells in brain injury and neurodegeneration are still lacking. Here, we described the differentiation and function of CD8+ T cells, reviewed the involvement of CD8+ T cells in the regulation of brain injury including stroke and traumatic brain injury and neurodegenerative diseases, such as Alzheimer's disease (AD) and Parkinson's disease (PD), and discussed therapeutic prospects and future study goals. Understanding these processes will promote the investigation of T-cell immunity in brain disorders and provide new intervention strategies for the treatment of brain injury and neurodegeneration.

Outcomes to 5 years of outborn versus inborn infants <32 weeks in Western Australia: a cohort study of infants born between 2005 and 2018

OBJECTIVE

We compared mortality and morbidity of inborn versus outborn very preterm infants <32 weeks' gestation in Western Australia (WA) between 2005 and 2018.

DESIGN

Retrospective cohort study.

PATIENTS

Infants <32 weeks' gestation who were born in WA.

MAIN OUTCOME MEASURES

Mortality was assessed as death before discharge home from the tertiary neonatal intensive care unit. Short-term morbidities included combined brain injury (intracranial haemorrhage grade ≥3 and cystic periventricular leukomalacia) and other major neonatal outcomes. Developmental assessments at age 2, 3 and 5 years were evaluated. We performed multivariable logistic regression analysis of outborn status on outcomes, controlling for gestational age, birth weight z-score, sex and multiple birth.

RESULTS

A total of 4974 infants were born in WA between 22 and 32 weeks' gestation between 2005 and 2018 of which 4237 (89.6%) were inborn and 443 (10.4%) were outborn. Overall mortality to discharge was higher in outborn infants (20.5% (91/443) vs 7.4% (314/4237); adjusted OR (aOR) 2.44, 95% CI 1.60 to 3.70, p<0.001). Outborn infants had higher rates of combined brain injury than those inborn (10.7% (41/384) vs 6.0% (246/4115); aOR 1.98, 95% CI 1.37 to 2.86), p<0.001). No difference in up to 5-year developmental measures was detected. Follow-up data were available for 65% of outborn and 79% of inborn infants.

CONCLUSIONS

Outborn preterm infants <32 weeks in WA had increased odds of mortality and combined brain injury than those inborn. Developmental outcomes up to 5 years were similar between groups. Loss to follow-up may have impacted the long-term comparison.

Role of the gut-microbiota-metabolite-brain axis in the pathogenesis of preterm brain injury

Brain injury, a common complication in preterm infants, includes the destruction of the key structural and functional connections of the brain and causes neurodevelopmental disorders; it has high morbidity and mortality rates. The exact mechanism underlying brain injury in preterm infants is unclear. Intestinal flora plays a vital role in brain development and the maturation of the immune system in infants; however, detailed understanding of the gut microbiota-metabolite-brain axis in preterm infants is lacking. In this review, we summarise the key mechanisms by which the intestinal microbiota contribute to neurodevelopment and brain injury in preterm infants, with special emphasis on the influence of microorganisms and their metabolites on the regulation of neurocognitive development and neurodevelopmental risks related to preterm birth, infection and neonatal necrotising enterocolitis (NEC). This review provides support for the development and application of novel therapeutic strategies, including probiotics, prebiotics, synbiotics, and faecal bacteria transplantation targeting at brain injury in preterm infants.

Melatonin as a Therapy for Preterm Brain Injury: What Is the Evidence?

Despite significant improvements in survival following preterm birth in recent years, the neurodevelopmental burden of prematurity, with its long-term cognitive and behavioral consequences, remains a significant challenge in neonatology. Neuroprotective treatment options to improve neurodevelopmental outcomes in preterm infants are therefore urgently needed. Alleviating inflammatory and oxidative stress (OS), melatonin might modify important triggers of preterm brain injury, a complex combination of destructive and developmental abnormalities termed encephalopathy of prematurity (EoP). Preliminary data also suggests that melatonin has a direct neurotrophic impact, emphasizing its therapeutic potential with a favorable safety profile in the preterm setting. The current review outlines the most important pathomechanisms underlying preterm brain injury and correlates them with melatonin's neuroprotective potential, while underlining significant pharmacokinetic/pharmacodynamic uncertainties that need to be addressed in future studies.

White matter injury detection based on preterm infant cranial ultrasound images

Introduction

White matter injury (WMI) is now the major disease that seriously affects the quality of life of preterm infants and causes cerebral palsy of children, which also causes periventricular leuko-malacia (PVL) in severe cases. The study aimed to develop a method based on cranial ultrasound images to evaluate the risk of WMI.

Methods

This study proposed an ultrasound radiomics diagnostic system to predict the WMI risk. A multi-task deep learning model was used to segment white matter and predict the WMI risk simultaneously. In total, 158 preterm infants with 807 cranial ultrasound images were enrolled. WMI occurred in 32preterm infants (20.3%, 32/158).

Results

Ultrasound radiomics diagnostic system implemented a great result with AUC of 0.845 in the testing set. Meanwhile, multi-task deep learning model preformed a promising result both in segmentation of white matter with a Dice coefficient of 0.78 and prediction of WMI risk with AUC of 0.863 in the testing cohort.

Discussion

In this study, we presented a data-driven diagnostic system for white matter injury in preterm infants. The system combined multi-task deep learning and traditional radiomics features to achieve automatic detection of white matter regions on the one hand, and design a fusion strategy of deep learning features and manual radiomics features on the other hand to obtain stable and efficient diagnostic performance.

Neonatal prophylactic antibiotics after preterm birth affect plasma proteome and immune development in pigs

BACKGROUND

Most preterm infants receive antibiotics to prevent serious infections shortly after birth. However, prolonged antibiotic treatment predisposes to gut dysbiosis and late-onset sepsis. Using preterm pigs as model, we hypothesized that neonatal prophylactic antibiotics impair systemic immune development beyond the days of antibiotic treatment.

METHODS

Preterm pigs (90% gestation) were fed formula for 9 days, treated with sterile water (CON) or enteral antibiotics from day 1 to 4. On days 5 and 9, blood was collected for haematology, in vitro LPS stimulation, and plasma proteomics.

RESULTS

Antibiotic treatment altered the abundance of 21 and 47 plasma proteins on days 5 and 9, representing 6.6% and 14.8% of the total annotated proteins, respectively. Most antibiotics-induced proteome changes related to complement cascade, neutrophil degranulation, and acute phase responses. Neutrophil and lymphocyte counts were higher in antibiotics-treated pigs on day 5 but did not change from days 5-9, in contrast to increasing cell counts in CON. The antibiotics treatment suppressed TNF-alpha and IL-10 responses to in vitro LPS challenge on day 5, 7 and 9.

CONCLUSION

Few days of antibiotics treatment following preterm birth alter the plasma proteome and inhibit systemic immune development, even beyond the days of treatment.

IMPACT

1. Neonatal prophylactic antibiotics alter the plasma proteome and suppress systemic immune development in preterm pigs 2. The effects of prophylactic antibiotics last beyond the days of treatment. 3. Neonatal antibiotics treatment for compromised human newborns may predispose to longer-term risks of impaired immunity and infections.

[Protective effect of breviscapine against brain injury induced by intrauterine inflammation in preterm rats and its mechanism]

OBJECTIVES

To study the protective effect of breviscapine against brain injury induced by intrauterine inflammation in preterm rats and its mechanism.

METHODS

A preterm rat model of brain injury caused by intrauterine inflammation was prepared by intraperitoneal injections of lipopolysaccharide in pregnant rats. The pregnant rats and preterm rats were respectively randomly divided into 5 groups: control, model, low-dose breviscapine (45 mg/kg), high-dose breviscapine (90 mg/kg), and high-dose breviscapine (90 mg/kg)+ML385 [a nuclear factor erythroid 2-related factor 2 (Nrf2) inhibitor, 30 mg/kg] (n=10 each). The number and body weight of the live offspring rats were measured for each group. Hematoxylin-eosin staining was used to observe the pathological morphology of the uterus and placenta of pregnant rats and the pathological morphology of the brain tissue of offspring rats. Immunofluorescent staining was used to measure the co-expression of ionized calcium binding adaptor molecule-1 (IBA-1) and nucleotide-binding oligomerization domain-like receptor protein 3 (NLRP3) in the cerebral cortex of offspring rats. ELISA was used to measure the levels of interleukin-6 (IL-6), interleukin-8 (IL-8), and interleukin-1β (IL-1β) in the brain tissue of offspring rats. Western blotting was used to measure the expression of Nrf2 pathway-related proteins in the brain tissue of offspring rats.

RESULTS

Pathological injury was found in the uterus, and placenta tissue of the pregnant rats and the brain tissue of the offspring rats, and severe microglia pyroptosis occurred in the cerebral cortex of the offspring rats in the model group. Compared with the control group, the model group had significant reductions in the number and body weight of the live offspring rats and the protein expression levels of Nrf2 and heme oxygenase-1 (HO-1) in the brain tissue of the offspring rats (P<0.05), but significant increases in the relative fluorescence intensity of the co-expression of IBA-1 and NLRP3, the levels of the inflammatory factors IL-6, IL-8, and IL-1β, and the protein expression levels of NLRP3 and caspase-1 in the brain tissue of the offspring rats (P<0.05). Compared with the model group, the breviscapine administration groups showed alleviated pathological injury of the uterus and placenta tissue of the pregnant rats and the brain tissue of the offspring rats, significant increases in the number and body weight of the live offspring rats and the protein expression levels of Nrf2 and HO-1 in the brain tissue of the offspring rats (P<0.05), and significant reductions in the relative fluorescence intensity of the co-expression of IBA-1 and NLRP3, the levels of the inflammatory factors IL-6, IL-8, and IL-1β, and the protein expression levels of NLRP3 and caspase-1 in the brain tissue of the offspring rats (P<0.05). The high-dose breviscapine group had a significantly better effect than the low-dose breviscapine (P<0.05). ML385 significantly inhibited the intervention effect of high-dose breviscapine (P<0.05).

CONCLUSIONS

Breviscapine can inhibit inflammatory response in brain tissue of preterm rats caused by intrauterine inflammation by activating the Nrf2 pathway, and it can also inhibit microglial pyroptosis and alleviate brain injury.

Omics approaches: interactions at the maternal-fetal interface and origins of child health and disease

Immunoperinatology is an emerging field. Transdisciplinary efforts by physicians, physician-scientists, basic science researchers, and computational biologists have made substantial advancements by identifying unique immunologic signatures of specific diseases, discovering innovative preventative or treatment strategies, and establishing foundations for individualized neonatal intensive care of the most vulnerable neonates. In this review, we summarize the immunobiology and immunopathology of pregnancy, highlight omics approaches to study the maternal-fetal interface, and their contributions to pregnancy health. We examined the importance of transdisciplinary, multiomic (such as genomics, transcriptomics, proteomics, metabolomics, and immunomics) and machine-learning strategies in unraveling the mechanisms of adverse pregnancy, neonatal, and childhood outcomes and how they can guide the development of novel therapies to improve maternal and neonatal health. IMPACT: Discuss immunoperinatology research from the lens of omics and machine-learning approaches. Identify opportunities for omics-based approaches to delineate infection/inflammation-associated maternal, neonatal, and later life adverse outcomes (e.g., histologic chorioamnionitis [HCA]).

The Patent Ductus Arteriosus in Extremely Preterm Neonates Is More than a Hemodynamic Challenge: New Molecular Insights

Complications to preterm birth are numerous, including the presence of a patent ductus arteriosus (PDA). The biological understanding of the PDA is sparse and treatment remains controversial. Herein, we speculate whether the PDA is more than a cardiovascular imbalance, and may be a marker in response to immature core molecular and physiological processes driven by biological systems, such as inflammation. To achieve a new biological understanding of the PDA, we performed echocardiography and collected plasma samples on day 3 of life in 53 consecutively born neonates with a gestational age at birth below 28 completed weeks. The proteome of these samples was analyzed by mass spectrometry (nanoLC-MS/MS) and immunoassay of 17 cytokines and chemokines. We found differences in 21 proteins and 8 cytokines between neonates with a large PDA (>1.5 mm) compared to neonates without a PDA. Amongst others, we found increased levels of angiotensinogen, periostin, pro-inflammatory associations, including interleukin (IL)-1β and IL-8, and anti-inflammatory associations, including IL-1RA and IL-10. Levels of complement factors C8 and carboxypeptidases were decreased. Our findings associate the PDA with the renin-angiotensin-aldosterone system and immune- and complement systems, indicating that PDA goes beyond the persistence of a fetal circulatory connection of the great vessels.