Experimental necrotizing enterocolitis induces neuroinflammation in the neonatal brain

The brain of fetuses with congenital diaphragmatic hernia shows signs of hypoxic injury with loss of progenitor cells, neurons, and oligodendrocytes

Congenital diaphragmatic hernia (CDH) is a birth defect characterized by incomplete closure of the diaphragm, herniation of abdominal organs into the chest, and compression of the lungs and the heart. Besides complications related to pulmonary hypoplasia, 1 in 4 survivors develop neurodevelopmental impairment, whose etiology remains unclear. Using a fetal rat model of CDH, we demonstrated that the compression exerted by herniated organs on the mediastinal structures results in decreased brain perfusion on ultrafast ultrasound, cerebral hypoxia with compensatory angiogenesis, mature neuron and oligodendrocyte loss, and activated microglia. In CDH fetuses, apoptosis was prominent in the subventricular and subgranular zones, areas that are key for neurogenesis. We validated these findings in the autopsy samples of four human fetuses with CDH compared to age- and sex-matched controls. This study reveals the molecular mechanisms and cellular changes that occur in the brain of fetuses with CDH and creates opportunities for therapeutic targets.

A graded neonatal mouse model of necrotizing enterocolitis demonstrates that mild enterocolitis is sufficient to activate microglia and increase cerebral cytokine expression

Background

Necrotizing enterocolitis (NEC) is an inflammatory gastrointestinal process that afflicts approximately 10% of preterm infants born in the United States each year, with a mortality rate of 30%. NEC severity is graded using Bell's classification system, from stage I mild NEC to stage III severe NEC. Over half of NEC survivors present with neurodevelopmental impairment during adolescence, a long-term complication that is poorly understood but can occur even after mild NEC. Although multiple animal models exist, none allow the experimenter to control nor represent the gradient of symptom severities seen in NEC patients. We bridge this knowledge gap by developing a graded murine model of NEC and studying its relationship with neuroinflammation across a range of NEC severities.

Methods

Postnatal day 3 (P3) C57BL/6 mice were fed a formula containing different concentrations (0% control, 0.25%, 1%, 2%, and 3%) of dextran sodium sulfate (DSS). P3 mice were fed every 3 hours for 72-hours. We collected data on weight gain and behavior (activity, response, body color) during feeding. At the end of the experiment, we collected tissues (intestine, liver, plasma, brain) for immunohistochemistry, immunofluorescence, and cytokine and chemokine analysis.

Results

Throughout NEC induction, mice fed higher concentrations of DSS died sooner, lost weight faster, and became sick or lethargic earlier. Intestinal characteristics (dilation, color, friability) were worse in mice fed with higher DSS concentrations. Histology revealed small intestinal disarray among mice fed all DSS concentrations, while higher DSS concentrations resulted in reduced small intestinal cellular proliferation and increased hepatic and systemic inflammation. In the brain, IL-2, G-CSF, and CXCL1 concentrations increased with higher DSS concentrations. Although the number of neurons and microglia in the CA1 hippocampal region did not differ, microglial branching was significantly reduced in DSS-fed mice.

Conclusion

We characterize a novel graded model of NEC that recapitulates the full range of NEC severities. We show that mild NEC is sufficient to initiate neuroinflammation and microglia activation. This model will facilitate studies on the neurodevelopmental effects of NEC.

Neurodevelopmental outcomes of preterm with necrotizing enterocolitis: a systematic review and meta-analysis

While neonatal necrotising enterocolitis (NEC) is associated with high mortality rates in newborns, survivors can face long-term sequelae. However, the relationship between NEC and neurodevelopmental impairment (NDI) in preterm infants remains unclear. To explore the relationship between neonatal NEC and neurodevelopmental outcomes in preterm infants, we searched PubMed, EMBASE, and the Cochrane Library from their inception to February 2024 for relevant studies. Studies included were cohort or case-control studies reporting neurodevelopmental outcomes of NEC in preterm infants. Two independent investigators extracted data regarding brain damage and neurodevelopmental outcomes in these infants at a corrected age exceeding 12 months. Odds ratios (ORs) were pooled using a random effects model. We included 15 cohort studies and 18 case-control studies, encompassing 60,346 infants. Meta-analysis of unadjusted and adjusted ORs demonstrated a significant association between NEC and increased odds of NDI (OR 2.15, 95% CI 1.9-2.44; aOR 1.89, 95% CI 1.46-2.46). Regarding brain injury, pooled crude ORs indicated an association of NEC with severe intraventricular haemorrhage (IVH) (OR 1.42, 95% CI 1.06-1.92) and periventricular leucomalacia (PVL) (OR 2.55, 95% CI 1.76-3.69). When compared with conservatively treated NEC, surgical NEC potentially carries a higher risk of NDI (OR 1.78, 95% CI 1.09-2.93) and severe IVH (OR 1.57, 95% CI 1.20-2.06). However, the risk of PVL did not show a significant difference (OR 1.60, 95% CI 0.47-5.40).

CONCLUSIONS

 Our meta-analysis provides evidence suggesting an association between NEC and NDI. Additionally, the severity of intestinal lesions appears to correlate with a higher risk of NDI. Further high-quality studies with comprehensive adjustments for potential confounding factors are required to definitively establish whether the association with NDI is causal.

WHAT IS KNOWN

• NEC is a serious intestinal disease in the neonatal period with a high mortality rate, and surviving children may have digestive system sequelae. • Compared with non-NEC preterm infants, the reported incidences of brain injury and neurodevelopmental disorders in NEC preterm infants are not the same.

WHAT IS NEW

• The risk of neonatal brain injury and neurodevelopmental disorders in preterm infants with NEC is higher than that in non-NEC infants, and the risk of NDI in surgical NEC infants is higher than that in the conservative treatment group. • NEC may increase the risk of motor, cognitive, language development delays, and attention deficits in children.

Clinical and Growth Correlates of Retinopathy of Prematurity in Preterm Infants with Surgical Necrotizing Enterocolitis and Intestinal Perforation

OBJECTIVE

 This study aimed to identify the clinical and growth parameters associated with retinopathy of prematurity (ROP) in infants with necrotizing enterocolitis (NEC) and spontaneous ileal perforation (SIP).

STUDY DESIGN

 We conducted a retrospective cohort study that compared clinical data before and after NEC/SIP onset in neonates, categorizing by any ROP and severe ROP (type 1/2) status.

RESULTS

 The analysis included 109 infants with surgical NEC/SIP. Sixty infants (60/109, 55%) were diagnosed with any ROP, 32/109 (29.3%) infants (22% type 1 and 7.3% type 2) with severe ROP. On univariate analysis, those with severe ROP (32/109, 39.5%) were of lower median gestational age (GA, 23.8 weeks [23.4, 24.6] vs. 27.3 [26.3, 29.0], p < 0.001), lower median birth weight (625 g [512, 710] vs. 935 [700, 1,180], p < 0.001) and experienced higher exposure to clinical chorioamnionitis (22.6 vs. 2.13%, p < 0.006), and later median onset of ROP diagnosis (63.0 days [47.0, 77.2] vs. 29.0 [19.0, 41.0], p < 0.001), received Penrose drain placement more commonly (19 [59.4%] vs. 16 [34.0%], p = 0.04), retained less residual small bowel (70.0 cm [63.1, 90.8] vs. 90.8 [72.0, 101], p = 0.007) following surgery, were exposed to higher FiO2 7 days after birth (p = 0.001), received ventilation longer and exposed to higher FiO2 at 2 weeks (p < 0.05) following NEC and developed acute kidney injury (AKI) more often (25 [86.2%] vs. 20 [46.5%], p = 0.002) than those without ROP. Those with severe ROP had lower length, weight for length, and head circumference z scores. In an adjusted Firth's logistic regression, GA (adjusted odds ratio [aOR] = 0.51, 95% confidence interval [CI]: [0.35, 0.76]) and diagnosis at later age (aOR = 1.08, 95% CI: [1.03, 1.13]) was shown to be significantly associated with any ROP.

CONCLUSION

 Infants who develop severe ROP following surgical NEC/SIP are likely to be younger, smaller, have been exposed to more O2, develop AKI, and grow poorly compared with those did not develop severe ROP.

KEY POINTS

· Thirty percent of infants with NEC/SIP had severe ROP.. · Those with severe ROP had poor growth parameters before and after NEC/SIP.. · Risk factors based ROP prevention strategies are needed to have improved ophthalmic outcomes..

Subventricular zone stem cell niche injury is associated with intestinal perforation in preterm infants and predicts future motor impairment

Brain injury is highly associated with preterm birth. Complications of prematurity, including spontaneous or necrotizing enterocolitis (NEC)-associated intestinal perforations, are linked to lifelong neurologic impairment, yet the mechanisms are poorly understood. Early diagnosis of preterm brain injuries remains a significant challenge. Here, we identified subventricular zone echogenicity (SVE) on cranial ultrasound in preterm infants following intestinal perforations. The development of SVE was significantly associated with motor impairment at 2 years. SVE was replicated in a neonatal mouse model of intestinal perforation. Examination of the murine echogenic subventricular zone (SVZ) revealed NLRP3-inflammasome assembly in multiciliated FoxJ1+ ependymal cells and a loss of the ependymal border in this postnatal stem cell niche. These data suggest a mechanism of preterm brain injury localized to the SVZ that has not been adequately considered. Ultrasound detection of SVE may serve as an early biomarker for neurodevelopmental impairment after inflammatory disease in preterm infants.

miR-375-3p targets YWHAB to attenuate intestine injury in neonatal necrotizing enterocolitis

PURPOSE

Necrotizing enterocolitis (NEC) is a significant contributor to neonatal mortality. This study aimed to investigate the role of high levels of miR-375-3p in breast milk in the development of NEC and elucidate its mechanism.

METHODS

Differential expression of miR-375-3p in the intestines of breast-fed and formula-fed mice was confirmed using real-time polymerase chain reaction (RT-PCR). NEC mice models were established, and intestinal injury was assessed using HE staining. RT-PCR and Western blot were conducted to examine the expression of miR-375-3p, tyrosine 3-monooxygenase/tryptophan 5-monooxygenase activation protein β (YWHAB), as well as the inflammatory in IEC-6 cells, and intestinal tissues obtained from NEC mice and patients. Flow cytometry and cell counting kit-8 (CCK-8) were employed to elucidate the impact of miR-375-3p and YWHAB on cell apoptosis and proliferation.

RESULTS

Breastfeeding increases miR-375-3p expression in the intestines. The expression of miR-375-3p in NEC intestinal tissues exhibited a significant decrease compared to the healthy group. Additionally, the expression of interleukin-6 (IL-6), interleukin-10 (IL-10), and tumor necrosis factor-α (TNF-α) was higher in the NEC group compared to the control group. Down-regulation of miR-375-3p inhibited IEC-6 cell proliferation, increased apoptosis, and elevated secretion of inflammatory factors. Bioinformatics revealed that YWHAB may be a target of miR-375-3p. RT-PCR and Western blot indicated a down-regulation of YWHAB expression in intestines of NEC patients and mice. Furthermore, YWHAB was found to be positively connected with miR-375-3p. Knockdown miR-375-3p down-regulated YWHAB expression in cells. Inhibition of YWHAB exhibited similar effects to miR-375-3p in IEC-6 cells. YWHAB plasmid partially reverse cellular functional impairment induced by miR-375-3p knockdown.

CONCLUSIONS

Breastfeeding elevated miR-375-3p expression in intestines in neonatal mice. MiR-375-3p leads to a decrease in apoptosis of intestinal epithelial cells, an increase in cell proliferation, and a concomitant reduction in the expression of inflammatory factors partly through targeting YWHAB.

Low-dose daily folic acid (400 μg) supplementation does not affect regulation of folate transporters found present throughout the terminal ileum and colon of humans: a randomized clinical trial

BACKGROUND

Folic acid supplementation during the periconceptional period reduces the risk of neural tube defects in infants, but concern over chronic folic acid exposure remains. An improved understanding of folate absorption may clarify potential risks. Folate transporters have been characterized in the small intestine, but less so in the colon of healthy, free-living humans. The impact of folic acid fortification or supplementation on regulation of these transporters along the intestinal tract is unknown.

OBJECTIVE

The objective was to characterize expression of folate transporters/receptor (FT/R) and folate hydrolase, glutamate carboxypeptidase II (GCPII), from the terminal ileum and throughout the colon of adults and assess the impact of supplemental folic acid.

METHODS

In this 16-wk open-labeled randomized clinical trial, adults consumed a low folic acid-containing diet, a folate-free multivitamin, and either a 400 μg folic acid supplement or no folic acid supplement. Dietary intakes and blood were assessed at baseline, 8 wk, and 16 wk (time of colonoscopy). Messenger RNA (mRNA) expression and protein expression of FT/R and GCPII were assessed in the terminal ileum, cecum, and ascending and descending colon.

RESULTS

Among 24 randomly assigned subjects, no differences in dietary folate intake or blood folate were observed at baseline. Mean ± SD red blood cell folate at 16 wk was 1765 ± 426 and 911 ± 242 nmol/L in the 400 and 0 μg folic acid group, respectively (P < 0.0001). Reduced folate carrier, proton-coupled folate transporter, and folate-receptor alpha expression were detected in the terminal ileum and colon, as were efflux transporters of breast cancer resistance protein and multidrug resistance protein-3. Other than a higher mRNA expression of FR-alpha and GCPII in the 400 μg supplement group in the ascending colon, no treatment differences were observed (P < 0.02).

CONCLUSIONS

Folate transporters are present throughout the terminal ileum and colon; there is little evidence that a low dose of folic acid supplementation affects colonic absorption. This trial was registered at clinicaltrials.gov as NCT03421483.

Clinical Correlates of Cerebellar Injury in Preterm Infants with Surgical Necrotizing Enterocolitis

Objective

Determine the risk factors of cerebellar injury in infants with surgical necrotizing enterocolitis (NEC).

Methods

Retrospective study compared clinical/pathological information between surgical NEC infants with and those without cerebellar injury.

Results

Infants with cerebellar injury (21/65, 32.3%) had significantly more hemorrhagic and the reparative lesions on the intestinal histopathology, had patent ductus arteriosus (PDA) more often, received red cell transfusion frequently, had blood culture positive sepsis and grew gram positive organisms more often and had cholestasis frequently following NEC than those without cerebellar injury. On multilogistic regression, the positive blood culture sepsis (OR 3.9, CI 1.1-13.7, p = 0.03), PDA (OR 4.5, CI 1.0-19.9, p = 0.04) and severe hemorrhage (grade 3-4)(OR 16.9, CI 2.1-135.5, p = 0.007) were independently associated with higher risk of cerebellar injury.

Conclusion

The cerebellar injury was most likely associated with positive blood culture sepsis following NEC, PDA, and severe hemorrhage lesions (grade 3-4) in infants with surgical NEC.

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.

Human milk oligosaccharides reduce necrotizing enterocolitis-induced neuroinflammation and cognitive impairment in mice

Necrotizing enterocolitis (NEC) is the leading cause of morbidity and mortality in premature infants. One of the most devastating complications of NEC is the development of NEC-induced brain injury, which manifests as impaired cognition that persists beyond infancy and which represents a proinflammatory activation of the gut-brain axis. Given that oral administration of the human milk oligosaccharides (HMOs) 2'-fucosyllactose (2'-FL) and 6'-sialyslactose (6'-SL) significantly reduced intestinal inflammation in mice, we hypothesized that oral administration of these HMOs would reduce NEC-induced brain injury and sought to determine the mechanisms involved. We now show that the administration of either 2'-FL or 6'-SL significantly attenuated NEC-induced brain injury, reversed myelin loss in the corpus callosum and midbrain of newborn mice, and prevented the impaired cognition observed in mice with NEC-induced brain injury. In seeking to define the mechanisms involved, 2'-FL or 6'-SL administration resulted in a restoration of the blood-brain barrier in newborn mice and also had a direct anti-inflammatory effect on the brain as revealed through the study of brain organoids. Metabolites of 2'-FL were detected in the infant mouse brain by nuclear magnetic resonance (NMR), whereas intact 2'-FL was not. Strikingly, the beneficial effects of 2'-FL or 6'-SL against NEC-induced brain injury required the release of the neurotrophic factor brain-derived neurotrophic factor (BDNF), as mice lacking BDNF were not protected by these HMOs from the development of NEC-induced brain injury. Taken in aggregate, these findings reveal that the HMOs 2'-FL and 6'-SL interrupt the gut-brain inflammatory axis and reduce the risk of NEC-induced brain injury.NEW & NOTEWORTHY This study reveals that the administration of human milk oligosaccharides, which are present in human breast milk, can interfere with the proinflammatory gut-brain axis and prevent neuroinflammation in the setting of necrotizing enterocolitis, a major intestinal disorder seen in premature infants.

Clinical and Growth Correlates of Retinopathy of Prematurity in Preterm infants with Surgical Necrotizing Enterocolitis and intestinal Perforation

Background

we sought to determine the clinical and growth parameters associated with retinopathy of prematurity (ROP) in infants with necrotizing enterocolitis (NEC) and spontaneous ileal perforation (SIP).

Methods

Retrospective cohort study comparing clinical information before and following NEC/SIP onset in neonates with and without severe ROP (Type 1 and 2).

Results

Those with severe ROP (32/109, 39.5%) had lower GA, BW, chorioamnionitis, later median onset of ROP diagnosis and received Penrose drain and had higher AKI, poor weight z scores, poor linear growth, longer duration of ventilation and higher FIo2 than those without ROP following NEC/SIP. The GA and diagnosis at later age remained significant for any ROP on multi regression modelling.

Conclusion

The surgical NEC/SIP infants with severe ROP were more likely to be younger, smaller, had AKI, had higher oxygen exposure and poor weight gain and linear growth than those without severe ROP.

Stem cells as a therapeutic avenue for active and long-term complications of Necrotizing Enterocolitis

Necrotizing enterocolitis (NEC) is a devastating neonatal intestinal disease associated with significant morbidity and mortality. Although decades of research have been dedicated to understanding the pathogenesis of NEC and developing therapies, it remains the leading cause of death among neonatal gastrointestinal diseases. Mesenchymal stem cells (MSCs) have garnered significant interest recently as potential therapeutic agents for the treatment of NEC. They have been shown to rescue intestinal injury and reduce the incidence and severity of NEC in various preclinical animal studies. MSCs and MSC-derived organoids and tissue engineered small intestine (TESI) have shown potential for the treatment of long-term sequela of NEC such as short bowel syndrome, neurodevelopmental delay, and chronic lung disease. Although the advances made in the use of MSCs are promising, further research is needed prior to the widespread use of these cells for the treatment of NEC.

Gut Microbiome-Brain Axis as an Explanation for the Risk of Poor Neurodevelopment Outcome in Preterm Infants with Necrotizing Enterocolitis

Necrotizing Enterocolitis (NEC) is characterized by an inflammation of intestinal tissue that primarily affects premature infants. It is the most common and devastating gastrointestinal morbidity of prematurity, but beyond intestinal morbidity, this condition has also been associated with an increased risk of neurodevelopmental delays that persist beyond infancy. Prematurity, enteral feeding, bacterial colonization, and prolonged exposure to antibiotics are all risk factors that predispose preterm infants to NEC. Interestingly, these factors are all also associated with the gut microbiome. However, whether or not there is a connection between the microbiome and the risk of neurodevelopmental delays in infants after NEC is still an emerging area of research. Furthermore, how microbes in the gut could impact a distant organ such as the brain is also poorly understood. In this review, we discuss the current understanding of NEC and the role of the gut microbiome-brain axis in neurodevelopmental outcomes after NEC. Understanding the potential role of the microbiome in neurodevelopmental outcomes is important as the microbiome is modifiable and thus offers the hope of improved therapeutic options. We highlight the progress and limitations in this field. Insights into the gut microbiome-brain axis may offer potential therapeutic approaches to improve the long-term outcomes of premature infants.

Harnessing the therapeutic potential of the stem cell secretome in neonatal diseases

Preterm birth and intrapartum related complications account for a substantial amount of mortality and morbidity in the neonatal period despite significant advancements in neonatal-perinatal care. Currently, there is a noticeable lack of curative or preventative therapies available for any of the most common complications of prematurity including bronchopulmonary dysplasia, necrotizing enterocolitis, intraventricular hemorrhage, periventricular leukomalacia and retinopathy of prematurity or hypoxic-ischemic encephalopathy, the main cause of perinatal brain injury in term infants. Mesenchymal stem/stromal cell-derived therapy has been an active area of investigation for the past decade and has demonstrated encouraging results in multiple experimental models of neonatal disease. It is now widely acknowledged that mesenchymal stem/stromal cells exert their therapeutic effects via their secretome, with the principal vector identified as extracellular vesicles. This review will focus on summarizing the current literature and investigations on mesenchymal stem/stromal cell-derived extracellular vesicles as a treatment for neonatal diseases and examine the considerations to their application in the clinical setting.

Early laparoscopic-assisted surgery is associated with decreased post-operative inflammation and intestinal strictures in infants with necrotizing enterocolitis

INTRODUCTION

In 2015, a protocol including early laparoscopy-assisted surgery in the treatment of necrotizing enterocolitis (NEC) was implemented at our institution. Carbon dioxide insufflation during laparoscopy may have an anti-inflammatory effect. We aimed to compare post-operative outcome after early laparoscopy-assisted surgery and classical laparotomy for NEC.

MATERIAL AND METHODS

Charts of premature infants undergoing surgery for NEC (2012-2021) were reviewed. Cases operated by early laparoscopy-assisted surgery (2015-2021) were compared to infants operated for NEC between 2012 and 2015 (laparotomy-NEC). Outcomes were post-operative CRP, need for reintervention, mortality, and the occurrence of post-NEC intestinal strictures. CRP was measured on the day of surgery (POD-0), 2 days (POD-2), and 7 days after surgery (POD-7). Data were compared using contingency tables for categorical variables and Student t-test or Mann-Whitney test for continuous variables.

RESULTS

Infants with NEC operated by early laparoscopy (n = 48) and laparotomy (n = 29) were similar in terms of perforation (60% vs 58%, p = 0.99) and POD-0 CRP (139 vs 124 mg/L, p = 0.94). Delay between first signs of NEC and surgery was shorter in the laparoscopy group (3 vs 6 days, p = 0.004). Early laparoscopy was associated with a lower CRP on POD-2 (108 vs 170, p = 0.005) and POD-7 (37 vs 68, p = 0.002), as well as a lower rate of post-operative intestinal stricture (34% vs 61%, p = 0.04).

CONCLUSIONS

In addition to being safe and feasible in premature infants, early laparoscopic-assisted surgery was associated with decreased NEC-related post-operative inflammation and strictures. A prospective, randomized study is needed in order to evaluate short and long-term effects of laparoscopy in infants with NEC.

LEVEL OF EVIDENCE

Level III.

Role of gut-brain axis in neurodevelopmental impairment of necrotizing enterocolitis

Necrotizing enterocolitis (NEC) is a common gastrointestinal disease of preterm infants with high morbidity and mortality. In survivors of NEC, one of the leading causes of long-term morbidity is the development of severe neurocognitive injury. The exact pathogenesis of neurodevelopmental delay in NEC remains unknown, but microbiota is considered to have dramatic effects on the development and function of the host brain via the gut-brain axis. In this review, we discuss the characteristics of microbiota of NEC, the impaired neurological outcomes, and the role of the complex interplay between the intestinal microbiota and brain to influence neurodevelopment in NEC. The increasing knowledge of microbial-host interactions has the potential to generate novel therapies for manipulating brain development in the future.

Understanding the Role of Oxidative Stress, Neuroinflammation and Abnormal Myelination in Excessive Aggression Associated with Depression: Recent Input from Mechanistic Studies

Aggression and deficient cognitive control problems are widespread in psychiatric disorders, including major depressive disorder (MDD). These abnormalities are known to contribute significantly to the accompanying functional impairment and the global burden of disease. Progress in the development of targeted treatments of excessive aggression and accompanying symptoms has been limited, and there exists a major unmet need to develop more efficacious treatments for depressed patients. Due to the complex nature and the clinical heterogeneity of MDD and the lack of precise knowledge regarding its pathophysiology, effective management is challenging. Nonetheless, the aetiology and pathophysiology of MDD has been the subject of extensive research and there is a vast body of the latest literature that points to new mechanisms for this disorder. Here, we overview the key mechanisms, which include neuroinflammation, oxidative stress, insulin receptor signalling and abnormal myelination. We discuss the hypotheses that have been proposed to unify these processes, as many of these pathways are integrated for the neurobiology of MDD. We also describe the current translational approaches in modelling depression, including the recent advances in stress models of MDD, and emerging novel therapies, including novel approaches to management of excessive aggression, such as anti-diabetic drugs, antioxidant treatment and herbal compositions.

Astaxanthin Alleviates Inflammatory Response in Neonatal Necrotizing Enterocolitis Rats by Regulating NOD2/TLR4 Pathway

Background

Necrotizing enterocolitis (NEC) is often associated with exaggerated activation of inflammatory response. Astaxanthin has been shown in studies to have a positive and advantageous effect on anti-inflammatory response. Hence, it is of great significance to study the protective effect of astaxanthin in NEC disease and its molecular mechanism.

Objective

The present study was to investigate whether astaxanthin attenuates NEC rats and to explore its potential mechanism. Material and Methods. Hematoxylin-eosin staining was used to observe the pathological change of the intestinal tissue in NEC rats. Subsequently, we determined the anti-oxidative stress, anti-apoptosis, and anti-inflammation in astaxanthin with enzyme-linked immunosorbent assay kits, TUNEL staining, western blot, and immunohistochemistry assay. Furthermore, we added nucleotide-binding oligomerization domain 2 (NOD2) inhibitor to certify the molecular pathway of the astaxanthin in NEC rats.

Results

Astaxanthin improved the pathological changes of the intestinal tissues. It restrained inflammation, oxidative stress, and protected cells from apoptosis in the intestinal tissue and serum of the NEC rats. Moreover, astaxanthin enhanced NOD2, whereas it suppressed toll-like receptor 4 (TLR4), nuclear factor-κB (NF-κB) pathway-related proteins. Apart from that, the NOD2 inhibitor offset the protective effect of the astaxanthin towards the NEC rats.

Conclusion

The present study indicated that astaxanthin alleviated oxidative stress, inflammatory response, and apoptosis in NEC rats by enhancing NOD2 and inhibiting TLR4 pathway.

Clinical impact of analgesic-sedative agents and peri-operative clinical status on white matter brain injury in preterm infants following surgical NEC

BACKGROUND

The potential influence of exposure to analgesic-sedative agents (ASA) before, during, and after surgical NEC and peri-operative clinical status on white matter injury (WMI) in preterm infants has not been fully defined, and a comprehensive evaluation may inform future research and clinical interventions.

METHODS

A retrospective study comparing ASA exposure before/during /after surgical NEC and peri-operative clinical status in neonates with and without WMI.

RESULTS

Infants with any WMI (grade 2-4, n = 36/67, 53.7%) had a higher number of surgical procedures receiving ASA (5 [IQR: 3, 8] vs. 3 [2, 4]; p = 0.002) and had a longer duration of hypotension during their first (48.0 hours [26.0, 48.0] vs. 15.5 [6, 48]; p = 0.009) and second surgery (20 hours [0, 48h] vs. 0 [0, 22]; p = 0.017), received more hydrocortisone (35% vs.13.3%,p = 0.04) than those without any WMI. There were no differences in fentanyl/morphine/midazolam exposure before/during/after the NEC onset in the two groups.Infants with severe WMI (19/67, 28.3%, grade 3/4) had a higher incidence of AKI (P = 0.004), surgical morbidity (p = 0.047), more surgical procedures (6.5 [3, 10] vs. 4 [2, 5]; p = 0.012), and received higher mean fentanyl doses(p = 0.03) from birth until NEC onset than those without severe WMI. The univariate associations between these factors and severe WMI remained insignificant after multivariable logistic regression.

CONCLUSION

Infants with WMI had more surgical procedures receiving ASA and had a longer duration of hypotension during surgeries. A large multicenter prospective study is needed to understand the full impact of ASA.

Gut-Brain cross talk: The pathogenesis of neurodevelopmental impairment in necrotizing enterocolitis

Necrotizing enterocolitis (NEC) is a devastating condition of multi-factorial origin that affects the intestine of premature infants and results in high morbidity and mortality. Infants that survive contend with several long-term sequelae including neurodevelopmental impairment (NDI)-which encompasses cognitive and psychosocial deficits as well as motor, vision, and hearing impairment. Alterations in the gut-brain axis (GBA) homeostasis have been implicated in the pathogenesis of NEC and the development of NDI. The crosstalk along the GBA suggests that microbial dysbiosis and subsequent bowel injury can initiate systemic inflammation which is followed by pathogenic signaling cascades with multiple pathways that ultimately lead to the brain. These signals reach the brain and activate an inflammatory cascade in the brain resulting in white matter injury, impaired myelination, delayed head growth, and eventual downstream NDI. The purpose of this review is to summarize the NDI seen in NEC, discuss what is known about the GBA, explore the relationship between the GBA and perinatal brain injury in the setting of NEC, and finally, highlight the existing research into possible therapies to help prevent these deleterious outcomes.

Clinical impact of severe acute kidney injury on post-operative and brain injury outcomes in preterm infants following surgical necrotizing enterocolitis

BACKGROUND

To evaluate post-operative outcomes and white matter injury (WMI) using brain MRI at term equivalent in neonates with and without severe acute kidney injury (AKI) following surgical necrotizing enterocolitis (NEC).

METHODS

A retrospective cohort study comparing neonates with severe (Stage 2/3) vs. other (no AKI/Stage 1) AKI using KDIGO classification with multivariable models assessing this association in the context of multiple systemic comorbidities.

RESULTS

Of 103 neonates with surgical NEC, 60 (58%) had severe AKI. Those with severe AKI had lower birth weight (BW; 715 vs. 950 g; p = .023), more frequently treated with indomethacin (18.3 vs. 2.4%); p = .014), higher CRP levels at 24 h after NEC onset (14.4 [6.4-19.8] vs. 4.8 [1.6-13.4]; p = .005), higher presence of cholestasis (73.3 vs. 51.2%); p = .023), later age of NEC onset (14 vs. 7 d); p = .004), longer length of bowel resected (14.9 vs. 4.3 cm); p = .011), longer post-operative ileus days (14 vs. 9 d); p < .001), longer post-operative days at starting enteral feedings (15 vs. 10 d; p < .001), longer days of attainment of full enteral feedings (75 vs. 44.5 d; p = .008) and longer length of stay (140.5 vs. 94 d; p = .028) compared to those without severe AKI. Compared to infants without AKI by serum creatinine, those with AKI had significantly more cases of white matter abnormality (WMA; 90 vs. 36.6%; p < .001) and retinopathy of prematurity (63.9 vs. 35.3%; p = .017). In addition, the presence of AKI Stage 2 and 3 by serum creatinine was independently associated with higher odds of sustaining severe WMI level on an ordinal scale (OR = 6.2; 95% CI = (1.1-35.5); p = .041).

CONCLUSIONS

Neonates with severe AKI following surgical NEC were more likely to experience longer post-operative morbidity and higher WMI by MRI at term.

Mesenchymal Stromal/Stem Cell Extracellular Vesicles and Perinatal Injury: One Formula for Many Diseases

Over the past decades, substantial advances in neonatal medical care have increased the survival of extremely premature infants. However, there continues to be significant morbidity associated with preterm birth with common complications including bronchopulmonary dysplasia (BPD), necrotizing enterocolitis (NEC), neuronal injury such as intraventricular hemorrhage (IVH) or hypoxic ischemic encephalopathy (HIE), as well as retinopathy of prematurity (ROP). Common developmental immune and inflammatory pathways underlie the pathophysiology of such complications providing the opportunity for multisystem therapeutic approaches. To date, no single therapy has proven to be effective enough to prevent or treat the sequelae of prematurity. In the past decade mesenchymal stem/stromal cell (MSC)-based therapeutic approaches have shown promising results in numerous experimental models of neonatal diseases. It is now accepted that the therapeutic potential of MSCs is comprised of their secretome, and several studies have recognized the small extracellular vesicles (sEVs) as the paracrine vector. Herein, we review the current literature on the MSC-EVs as potential therapeutic agents in neonatal diseases and comment on the progress and challenges of their translation to the clinical setting.

CXCL1/CXCR2 is involved in white matter injury in neonatal rats via the gut–brain axis

Background

This study aimed to investigate whether CXCL1/CXCR2 mediates intestinal injury or white matter injury by delivering inflammatory mediators through the gut–brain regulation axis.

Methods

Neonatal SD rats, regardless of sex, were administered 3% dextran sulfate sodium via intragastric administration at different time points to construct necrotizing enterocolitis (NEC) models. Meanwhile, hypoxia and ischemia were induced in 3 day-old SD rats to construct hypoxic–ischemic brain injury (HIBI) and NEC + HIBI models, without gender discrimination. Hematoxylin–eosin staining was used to observe pathological changes in neonatal rat intestinal and brain tissues. Western blotting detected CXCL1 and CXCR2 expression in NEC, HIBI, and NEC + HIBI rat intestinal and brain tissues.

Results

Compared with normal rats, pathological damage to periventricular white matter was observed in the NEC group. In addition to the increased mortality, the histopathological scores also indicated significant increases in brain and intestinal tissue damage in both HIBI and NEC + HIBI rats. Western blotting results suggested that CXCL1 and CXCR2 expression levels were upregulated to varying degrees in the intestinal and brain tissues of NEC, HIBI, and NEC + HIBI neonatal rats compared to that in the normal group. Compared with the HIBI group, the expression of CXCL1 and CXCR2 continued to increase in NEC + HIBI rats at different time points.

Conclusions

CXCL1/CXCR2 may be involved in white matter injury in neonatal rats by delivering intestinal inflammatory mediators through the gut–brain axis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12868-022-00749-1.

Pathologically impaired periventricular white matter was observed in NEC neonatal rats.

Hypoxic-ischemic brain injury can also lead to intestinal inflammation.

CXCL1 and CXCR2 were significantly upregulated in intestinal and brain tissues in NEC, HIBI, and NEC+HIBI rats compared to the normal group.

Compared with the HIBI group, CXCL1 and CXCR2 expression continued to increase in NEC+HIBI rats.

Mortality and neurodevelopmental outcomes of infants with spontaneous intestinal perforation: a systematic review and meta-analysis

BACKGROUND

There is limited information about the mortality and neurodevelopmental outcomes of very preterm infants (<32 weeks) with spontaneous intestinal perforation (SIP).

OBJECTIVE

To explore the association between SIP and neurodevelopmental outcomes and mortality in very preterm infants.

DATA SOURCES

Medline, EMBASE, Cochrane Library, EMCARE and MedNar.

STUDY SELECTION

Databases were searched until September 2021. Studies comparing outcomes of 'SIP' versus 'no SIP or necrotising enterocolitis (NEC)' were included.

DATA EXTRACTION

Neurodevelopmental outcomes at ≥1 year corrected age were extracted as the main outcome measure. Data were pooled separately for adjusted and unadjusted ORs using the random-effects model. The evidence level was assessed using the GRADE (Grading of Recommendations, Assessments, Development and Evaluations) framework.

RESULTS

Eighteen cohort studies (13 606 infants) were included. Meta-analysis of unadjusted ORs showed that SIP was significantly associated with increased odds of mortality, cerebral palsy, composite outcome of death or disability, visual impairment and hearing impairment. However, pooling of adjusted ORs (aOR) found significant associations only for mortality (aOR (95% CI) 2.27 (2.07 to 2.49); I²: 0%; four studies (n=10 695)), severe disability (aOR (95% CI) 2.06 (1.38 to 3.08); I²: 0%; two studies (n=321)) and composite outcome of 'death or disability' (aOR (95% CI) 2.18 (1.55 to 3.06); I²: 0%; two studies (n=321)). The level of evidence was 'low' or 'very low'.

LIMITATIONS

Lack of information on aORs from many studies.

CONCLUSIONS

SIP in very preterm infants is associated with higher odds of mortality, severe disability, and death or disability.

A hydrogen-sulfide derivative of mesalamine reduces the severity of intestinal and lung injury in necrotizing enterocolitis through endothelial nitric oxide synthase

Necrotizing enterocolitis (NEC) remains a devastating disease that affects preterm infants. Hydrogen sulfide (H2S) donors have been shown to reduce the severity of NEC, but the optimal compound has yet to be identified. We hypothesized that oral H2S-Mesalamine (ATB-429) would improve outcomes in experimental NEC, and its benefits would be dependent on endothelial nitric oxide synthase (eNOS) pathways. NEC was induced in 5-day-old wild-type (WT) and eNOS knockout (eNOSKO) pups by formula feeding and stress. Four groups were studied in both WT and eNOSKO mice: 1) breastfed controls, 2) NEC, 3) NEC + 50 mg/kg mesalamine, and 4) NEC + 130 mg/kg ATB-429. Mesalamine and ATB-429 doses were equimolar. Pups were monitored for sickness scores and perfusion to the gut was measured by Laser Doppler Imaging (LDI). After euthanasia of the pups, intestine and lung were hematoxylin and eosin-stained and scored for injury in a blind fashion. TLR4 expression was quantified by Western blot and IL-6 expression by ELISA. P < 0.05 was significant. Both WT and eNOSKO breastfed controls underwent normal development and demonstrated milder intestinal and pulmonary injury compared with NEC groups. For the WT groups, ATB-429 significantly improved weight gain, reduced clinical sickness score, and improved perfusion compared with the NEC group. In addition, WT ATB-429 pups had a significantly milder intestinal and pulmonary histologic injury when compared with NEC. ATB-429 attenuated the increase in TLR4 and IL-6 expression in the intestine. When the experiment was repeated in eNOSKO pups, ATB-429 offered no benefit in weight gain, sickness scores, perfusion, intestinal injury, pulmonary injury, or decreasing intestinal inflammatory markers. An H2S derivative of mesalamine improves outcomes in experimental NEC. Protective effects appear to be mediated through eNOS. Further research is warranted to explore whether ATB-429 may be an effective oral therapy to combat NEC.

PGC-1α activity and mitochondrial dysfunction in preterm infants

Extremely low gestational age neonates (ELGANs) are born in a relatively hyperoxic environment with weak antioxidant defenses, placing them at high risk for mitochondrial dysfunction affecting multiple organ systems including the nervous, respiratory, ocular, and gastrointestinal systems. The brain and lungs are highly affected by mitochondrial dysfunction and dysregulation in the neonate, causing white matter injury (WMI) and bronchopulmonary dysplasia (BPD), respectively. Adequate mitochondrial function is important in providing sufficient energy for organ development as it relates to alveolarization and axonal myelination and decreasing oxidative stress via reactive oxygen species (ROS) and reactive nitrogen species (RNS) detoxification. Peroxisome proliferator-activated receptor gamma coactivator-1 alpha (PGC-1α) is a master regulator of mitochondrial biogenesis and function. Since mitochondrial dysfunction is at the root of WMI and BPD pathobiology, exploring therapies that can regulate PGC-1α activity may be beneficial. This review article describes several promising therapeutic agents that can mitigate mitochondrial dysfunction through direct and indirect activation and upregulation of the PGC-1α pathway. Metformin, resveratrol, omega 3 fatty acids, montelukast, L-citrulline, and adiponectin are promising candidates that require further pre-clinical and clinical studies to understand their efficacy in decreasing the burden of disease from WMI and BPD in preterm infants.

Neurologic consequences of neonatal necrotizing enterocolitis

Necrotizing enterocolitis (NEC) is a severe gastrointestinal disease of the premature infant with high mortality and morbidity. Children who survive NEC have been shown to demonstrate neurodevelopmental delay, with significantly worse outcomes than from prematurity alone. The pathways leading to NEC-associated neurological impairments remain unclear, limiting the development of preventative and protective strategies. This review aims to summarize the existing clinical and experimental studies related to NEC-associated brain injury. We describe the current epidemiology of NEC, reported long-term neurodevelopmental outcomes among survivors, and proposed pathogenesis of brain injury in NEC. Highlighted are the potential connections between hypoxia-ischemia, nutrition, infection, gut inflammation, and the developing brain in NEC.

Brain injury in preterm infants with surgical necrotizing enterocolitis: clinical and bowel pathological correlates

BACKGROUND

The objective of this study was to determine the risk factors and outcomes of white matter brain injury (WMBI) on magnetic resonance imaging (MRI) at term-equivalent age in infants with surgical necrotizing enterocolitis (NEC).

METHODS

This retrospective study compared clinical/pathological information between infants with and those without WMBI.

RESULTS

Out of 69 infants with surgical NEC, 17 (24.6%) had mild WMBI, 13 (18.8%) had moderate WMBI, and six (8.7%) had severe WMBI on the brain MRI. Several clinical factors (gestational age, more red blood cell (RBC) transfusions before NEC onset, pneumoperitoneum, earlier NEC onset age, postoperative ileus, acute kidney injury (AKI) by serum creatinine, postnatal steroids, hospital stay) and histopathological findings (necrosis, hemorrhage) had univariate associations with WMBI. Associations with RBC transfusion (odds ratio (OR) 23.6 [95% confidence interval (CI): 4.73-117.97]; p = 0.0001), age at NEC onset (OR 0.30 [95%CI: 0.11-0.84]; p = 0.021), necrosis (OR 0.10 [95%CI: 0.01-0.90]; p = 0.040), and bowel hemorrhage (OR 7.79 [95%CI: 2.19-27.72]; p = 0.002) persisted in multivariable association with grade 3-4 WMBI. The infants with WMBI had lower mean motor, cognitive, language scores, and higher ophthalmic morbidity at 2 years of age.

CONCLUSIONS

The WMBI was most likely associated with earlier NEC onset, higher RBC transfusions, and less necrosis and greater hemorrhage lesions on intestinal pathology in preterm infants with surgical NEC.

IMPACT

In preterm infants with surgical NEC, brain MRI showed injury in the white matter in 52%, gray matter in 10%, and cerebellar region in 30%. Preterm infants with severe WMBI (grade 3-4) had less necrosis and greater hemorrhagic lesions on histopathology of the bowel. Preterm infants with WMBI were more likely to have a more severe postoperative course, AKI, and longer length of hospitalization. Neuroprotective strategies to prevent brain injury in preterm infants with surgical NEC are needed with the goal of improving the neurodevelopmental outcomes.

Association between glial fibrillary acidic protein, glial-derived neurotrophic factor, and fatty acid-binding protein-2 at birth in the incidence of necrotizing enterocolitis in preterm infants

BACKGROUND

This study aimed to analyze the relationship between glial fibrillary acidic protein (GFAP), glial-derived neurotrophic factor (GDNF), and fatty acid-binding protein-2 (FABP-2) in preterm infants on the incidence of NEC.

METHODS

Preterm infants with a birth weight <1,500 g and gestational age <34 weeks were included in this study. Biomarker examination was performed using the umbilical vein blood at birth (first sample). Biomarker examination was repeated if the infant developed symptoms of NEC using peripheral vein blood (second sample). Infants were observed for 14 days. If NEC did not exist, a biomarker examination was performed at 14 days.

RESULTS

This study included 30 preterm infants, nine infants experienced NEC. The values of GFAP, GDNF, and FABP-2 (median and range) in the group with NEC were higher than those in the group without NEC in both the first samples {GFAP [1.40 (0.20-6.50) vs. 0.30 (0.10-1.30) P = 0.014], GDNF [2.84 (1.05-14.11) vs. 1.56 (1.07-3.48) P = 0.050], and FABP-2 [621.70 (278.40-2,207.00) vs. 294.20 (211.40-597.50) P = 0.002]} and second samples {GFAP [2.40 (0.30-3.10) vs. 0.30 (0.10-0.60) P = 0.003], GDNF [2.99 (0.56-10.30) vs. 1.46 (0.85-2.24) P = 0.019], and FABP-2 [646.8 (179.20-1,571.00) vs. 314.90 (184.70-521.60) P = 0.040]}. In infants with NEC, the median values of GFAP [2.40 (0.30-3.10) vs. 1.40 (0.20-6.50) P = 0.767], GDNF [2.99 (0.56-10.30) vs. 2.84 (1.05-14.11) P = 0.859], and FABP-2 [646.80 (179.20-1,571.00) vs. 621.70 (278.40-2,207.00) P = 0.953] in the second sample were higher than those in the first sample. Logistic regression demonstrated that GFAP at birth (Odds Ratio [OR] = 15.629, 95% Confidence Interval [CI] = 1.697-143.906, P = 0.015) and FABP-2 levels at birth (OR = 1.008, 95% CI = 1.001-1.015, P = 0.033) were significantly associated with an increased risk of NEC.

CONCLUSION

Increased GFAP, GDNF, and FABP-2 at birth are associated with NEC occurrence within two weeks of birth. These findings suggest that early-onset NEC is associated with intestinal injury that occurs during the perinatal or even prenatal period.

Amniotic fluid stem cells: A novel treatment for necrotizing enterocolitis

Necrotizing enterocolitis (NEC) is a gastrointestinal disease frequently prevalent in premature neonates. Despite advances in research, there is a lack of accurate, early diagnoses of NEC and the current therapeutic approaches remain exhausted and disappointing. In this review, we have taken a close look at the regenerative medical literature available in the context of NEC treatment. Stem cells from amniotic fluid (AFSC) administration may have the greatest protective and restorative effects on NEC. This review summarizes the potential protection and restoration AFSCs have on NEC-induced intestinal injury while comparing various components within AFSCs like conditioned medium (CM) and extracellular vesicles (EVs). In addition to therapeutic interventions that focus on targeting intestinal epithelial damage and regeneration, a novel discovery that AFSCs act in a Wnt-dependent manner provides insight into this mechanism of protection. Finally, we have highlighted the most important aspects that remain unknown that should be considered to guide future research on the translational application of AFSC-based therapy. We hope that this will be a beneficial frame of reference for the guidance of future studies and towards the clinical application of AFSC and/or its derivatives as a treatment against NEC.

Low technology, mild controlled hypothermia for necrotizing enterocolitis treatment: an initiative to improve healthcare to preterm neonates

Necrotizing enterocolitis (NEC) treatment remains unchanged for years. Data suggest that mild controlled hypothermia could potentially improve NEC outcomes. Our units presented unfavourable outcomes on NEC. The aim was to assess our experience with low technology, mild controlled hypothermia on NEC outcomes, and improve preterm infants' healthcare. This was a single-center quality improvement study with retrospective cohort design at the neonatal intensive care unit in the university hospital. Forty-three preterm infants with NEC (Modified Bell's Stage II/III) were included: 19 in the control group (2015-2018) and 24 in the hypothermia group (2018-2020). The control group received standard treatment (fasting, abdominal decompression, and broad-spectrum antibiotics). The hypothermia group underwent cooling to 35.5 °C for 48 h after NEC diagnosis, along with conventional treatment. The primary outcomes are intestinal perforation, need for surgery, duration of parenteral nutrition, death, and extensive resection of the small intestine. There was no statistical difference in the NEC score. The hypothermia group required less surgery (aRR 0.40; 95% CI 0.19-0.85), presented less bowel perforation (aRR 0.39; 95% CI 0.18; 0.83), had a shorter duration of parenteral nutrition (aHR 5.28; 95% CI 1.88-14.89), did not need extensive intestinal resection, (0 vs 15.7%), and did not experience any deaths (0 vs 31.6%).Conclusions: In our experience, low technology, mild controlled hypothermia was feasible, not related to adverse effects, and effective treatment for NEC Modified Bell's Stage II/III. It avoided surgery, bowel perforation, and extensive intestinal resection; reduced mortality; and shortened parenteral nutrition duration. What is Known: • New approaches have been proposed to avoid enterocolitis incidence; however, the treatment of enterocolitis stage 2 has been the same for decades, and unfavourable outcomes remain despite conventional management. • Studies suggest that hypothermia can be an alternative to enterocolitis treatment. What is New: • Mild controlled hypothermia can be an additional practice to treat enterocolitis stage 2, is feasible, and is not related to adverse effects to preterm infants. • It can decrease surgery needs, duration of parenteral nutrition, and death and avoids extensive intestinal resection in preterm infants.

Endoplasmic reticulum stress in the acute intestinal epithelial injury of necrotizing enterocolitis

Endoplasmic reticulum (ER) is a dynamic organelle that has many functions including protein synthesis, lipid synthesis, and calcium metabolism. Any perturbation in the ER such as accumulation of unfolded or misfolded proteins in the ER lumen causes ER stress. ER stress has been implicated in many intestinal inflammatory diseases. However, the role of ER stress in acute intestinal epithelial injuries such as necrotizing enterocolitis in preterm neonates, remains incompletely understood. In this review, we introduce ER structure, functions and summarize the intracellular signaling pathways involved in unfolded protein response (UPR), a survival mechanism in which cells exert an adaptive function to restore homeostasis in the ER. However, intense and prolonged ER stress induces apoptotic response which results in apoptotic cell death. We also discuss and highlight recent advances that have improved our understanding of the molecular mechanisms that regulate the ER stress in acute intestinal epithelial injuries such as necrotizing enterocolitis (NEC). We focus on the role of ER stress in influencing gut homeostasis in the neonatal period and on the potential therapeutic interventions to alleviate ER stress-induced cell death in NEC.

Necrotizing enterocolitis induces T lymphocyte-mediated injury in the developing mammalian brain

Necrotizing enterocolitis (NEC) causes acute intestinal necrosis in premature infants and is associated with severe neurological impairment. In NEC, Toll-like receptor 4 is activated in the intestinal epithelium, and NEC-associated brain injury is characterized by microglial activation and white matter loss through mechanisms that remain unclear. We now show that the brains of mice and humans with NEC contained CD4⁺ T lymphocytes that were required for the development of brain injury. Inhibition of T lymphocyte influx into the brains of neonatal mice with NEC reduced inflammation and prevented myelin loss. Adoptive intracerebroventricular delivery of gut T lymphocytes from mice with NEC into Rag1 ^-/- recipient mice lacking CD4⁺ T cells resulted in brain injury. Brain organoids derived from mice with or without NEC and from human neuronal progenitor cells revealed that IFN-γ release by CD4⁺ T lymphocytes induced microglial activation and myelin loss in the organoids. IFN-γ knockdown in CD4⁺ T cells derived from mice with NEC abrogated the induction of NEC-associated brain injury after adoptive transfer to naïve Rag1 ^-/- recipient mice. T cell receptor sequencing revealed that NEC mouse brain-derived T lymphocytes shared homology with gut T lymphocytes from NEC mice. Intraperitoneal injection of NEC gut-derived CD4⁺ T lymphocytes into naïve Rag1 ^-/- recipient mice induced brain injury, suggesting that gut-derived T lymphocytes could mediate neuroinflammation in NEC. These findings indicate that NEC-associated brain injury may be induced by gut-derived IFN-γ-releasing CD4⁺ T cells, suggesting that early management of intestinal inflammation in children with NEC could improve neurological outcomes.

Long-term coordinated microstructural disruptions of the developing neocortex and subcortical white matter after early postnatal systemic inflammation

Severe postnatal systemic infection is highly associated with persistent disturbances in brain development and neurobehavioral outcomes in survivors of preterm birth. However, the contribution of less severe but prolonged postnatal infection and inflammation to such disturbances is unclear. Further, the ability of modern imaging techniques to detect the underlying changes in cellular microstructure of the brain in these infants remains to be validated. We used high-field ex-vivo MRI, neurohistopathology, and behavioral tests in newborn rats to demonstrate that prolonged postnatal systemic inflammation causes subtle, persisting disturbances in brain development, with neurodevelopmental delays and mild motor impairments. Diffusion-tensor MRI and neurite orientation dispersion and density imaging (NODDI) revealed delayed maturation of neocortical and subcortical white matter microstructure. Analysis of pyramidal neurons showed that the cortical deficits involved impaired dendritic arborization and spine formation. Analysis of oligodendrocytes showed that the white matter deficits involved impaired oligodendrocyte maturation and axonal myelination. These findings indicate that prolonged postnatal inflammation, without severe infection, may critically contribute to the diffuse spectrum of brain pathology and subtle long-term disability in preterm infants, with a cellular mechanism involving oligodendrocyte and neuronal dysmaturation. NODDI may be useful for clinical detection of these microstructural deficits.

Blockage of NLRP3 inflammasome activation ameliorates acute inflammatory injury and long-term cognitive impairment induced by necrotizing enterocolitis in mice

Background

Necrotizing enterocolitis (NEC) is an inflammatory gastrointestinal disease in premature neonates with high mortality and morbidity, while the underlining mechanism of intestinal injury and profound neurological dysfunction remains unclear. Here, we aimed to investigate the involvement of NLPR3 inflammasome activation in NEC-related enterocolitis and neuroinflammation, especially long-term cognitive impairment, meanwhile, explore the protective effect of NLRP3 inhibitor MCC950 on NEC in mice.

Methods

NLRP3 inflammasome activation in the intestine and brain was assessed in the NEC mouse model, and NLRP3 inhibitor MCC950 was administrated during the development of NEC. Survival rate, histopathological injury of the intestine and brain, and expression of mature IL-1β and other pro-inflammatory cytokines were analyzed. Long-term cognitive impairment was evaluated by behavioral test.

Results

The expression of NLRP3 and mature IL-1β in the intestine and brain was greatly upregulated in NEC mice compared to the controls. MCC950 treatment efficiently improved NEC survival rate, reduced intestinal and brain inflammation, and ameliorated the severity of pathological damage in both organs. Additionally, in vivo blockage of NLRP3 inflammasome with MCC950 in early life of NEC pups potently protected against NEC-associated long-term cognitive impairment.

Conclusions

Our findings suggest that NLRP3 inflammasome activation participates in NEC-induced intestinal and brain injury, and early intervention with NLRP3 inhibitor may provide beneficial therapeutic effect on NEC infants.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12974-021-02111-4.

Nesfatin-1 ameliorates oxidative bowel injury in rats with necrotizing enterocolitis: The role of the microbiota composition and claudin-3 expression

BACKGROUND AND PURPOSE

Ongoing high mortality due to necrotizing enterocolitis (NEC) necessitates the investigation of novel treatments to improve the outcome of the affected newborns. The aim was to elucidate the potential therapeutic impact of the nesfatin-1, a peptide with anti-inflammatory and anti-apoptotic effects in several inflammatory processes, on NEC-induced newborn rats.

MATERIALS AND METHODS

Sprague-Dawley pups were separated from their mothers, fed with a hyperosmolar formula and exposed to hypoxia, while control pups had no intervention. NEC-induced pups received saline or nesfatin-1 (0.2 μg/kg/day) for 3 days, while some nesfatin-1 treated pups were injected with capsaicin (50 μg/g) for the chemical ablation of afferent neurons. On the 4th day, clinical state and macroscopic gut assessments were made. In intestines, immunohistochemical staining of cycloxygenase-2 (COX-2), nuclear factor (NF)-κB-p65 (RelA), vascular endothelial growth factor (VEGF), claudin-3 and zonula occludens-1 (ZO-1) were performed, while gene expressions of COX-2, occludin, claudin-3, NF-κB-p65 (RelA) and VEGF were determined using q-PCR. In fecal samples, relative abundance of bacteria was quantified by q-PCR. Biochemical evaluation of oxidant/antioxidant parameters was performed in both intestinal and cerebral tissues.

RESULTS

Claudin-3 and ZO-1 immunoreactivity scores were significantly elevated in the nesfatin-1 treated control pups. Nesfatin-1 reduced NEC-induced high macroscopic and clinical scores, inhibited NF-κB-65 pathway and maintained the balance of oxidant/antioxidant systems. NEC increased the abundance of Proteobacteria with a concomitant reduction in Actinobacteria and Bacteroidetes, while nesfatin-1 treatment reversed these alterations. Modulatory effects of nesfatin-1 on microbiota and oxidative injury were partially reversed by capsaicin. Immunohistochemistry demonstrated that nesfatin-1 abolished NEC-induced reduction in claudin-3. Gene expressions of COX-2, NF-κB, occludin and claudin-3 were elevated in saline-treated NEC pups, while these up-regulated mRNA levels were not further altered in nesfatin-1-treated NEC pups.

CONCLUSION

Nesfatin-1 could be regarded as a potential preventive agent for the treatment of NEC.

Effect of Sargassum fusiforme polysaccharide on apoptosis and its possible mechanism in human erythroleukemia cells

This study aimed to investigate the effects of Sargassum fusiforme polysaccharide (SFPS I, II, and III) on the apoptosis and regulation of human erythroleukemia (HEL) cells. The effect of different doses of SFPS on HEL cell growth was detected using the Cell Counting Kit-8 method, and apoptosis was detected by Hoechst staining. Cell cycle distribution and apoptosis were detected using flow cytometry. Expression of the cell cycle gene, p53, antiapoptotic genes, Bcl-xL and Bcl-2, and pro-apoptotic genes, Bax, Bad, and Caspase-3, as well as the expression of the corresponding proteins, were detected using real-time quantitative polymerase chain reaction (qPCR) and Western blot. The results showed that SFPS II and III decreased HEL cell viability and induced HEL cell apoptosis. Different concentrations of SFPS (I, II, and III) were detected that induced much less toxic effect in normal human embryonic lung (MRC-5) cells, and SFPS I increased cell proliferation, indicating its favorable selectivity towards cancer cells. The mechanism by which SFPS induced apoptosis was also found to be related to the induction of cell cycle arrest in the G0/G1 phase and the increased expression of apoptosis-related genes and proteins. We concluded that SFPS induces HEL cell apoptosis, possibly via activation of the Caspase pathway, providing the theoretical basis for the development of SFPS-based anti-tumor drug products.

Cerebral Autoregulation in Sick Infants: Current Insights

Cerebrovascular autoregulation is the ability to maintain stable cerebral blood flow within a range of cerebral perfusion pressures. When cerebral perfusion pressure is outside the limits of effective autoregulation, the brain is subjected to hypoperfusion or hyperperfusion, which may cause vascular injury, hemorrhage, and/or hypoxic white matter injury. Infants born preterm, after fetal growth restriction, with congenital heart disease, or with hypoxic-ischemic encephalopathy are susceptible to a failure of cerebral autoregulation. Bedside assessment of cerebrovascular autoregulation would offer the opportunity to prevent brain injury. Clinicians need to know which patient populations and circumstances are associated with impaired/absent cerebral autoregulation.

COVID-19 in pregnancy: Placental and neonatal involvement

Since December 2019, severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) has caused over 12 million infections and more than 550 000 deaths.¹ Morbidity and mortality appear partly due to host inflammatory response.² Despite rapid, global research, the effect of SARS‐CoV‐2 on the developing fetus remains unclear. Case reports indicate that vertical transmission is uncommon; however, there is evidence that placental and fetal infection can occur.^3‐7 Placentas from infected patients show inflammatory, thrombotic, and vascular changes that have been found in other inflammatory conditions.^8,9 This suggests that the inflammatory nature of SARS‐CoV‐2 infection during pregnancy could cause adverse obstetric and neonatal events. Exposure to intrauterine inflammation and placental changes could also potentially result in long‐term, multisystemic defects in exposed infants. This review will summarize the known literature on the placenta in SARS‐CoV‐2 infection, evidence of vertical transmission, and possible outcomes of prenatal exposure to the virus.

Hope on the horizon: promising novel therapies for necrotizing enterocolitis

Necrotizing enterocolitis (NEC) remains among the most common and devastating diseases in neonates. Despite advances in neonatal clinical care, specific treatment strategies and diagnostic modalities remain lacking. As a result, morbidity and mortality remain high. Improved understanding of the pathogenesis of NEC has the potential for improved therapeutics. Some of the areas of research leading to promising discoveries include inhibition of Toll-like receptor signaling, modulation of vascular endothelial growth factor signal pathways, defining metabolomic alterations in NEC to discover potential biomarkers, probing for genetic predispositions to NEC susceptibility, determining mechanistic relations between anemia and NEC, and microflora modulation through the use of probiotics. All of these areas may represent novel promising approaches to the prevention and treatment of NEC. This review will focus on these current and possible therapeutic perspectives.

Neurodevelopmental impairment in necrotising enterocolitis survivors: systematic review and meta-analysis

AIM

To determine (1) the incidence of neurodevelopmental impairment (NDI) in necrotising enterocolitis (NEC), (2) the impact of NEC severity on NDI in these babies and (3) the cerebral lesions found in babies with NEC.

METHODS

Systematic review: three independent investigators searched for studies reporting infants with NDI and a history of NEC (PubMed, Medline, Cochrane Collaboration, Scopus). Meta-analysis: using RevMan V.5.3, we compared NDI incidence and type of cerebral lesions between NEC infants versus preterm infants and infants with medical vs surgical NEC.

RESULTS

Of 10 674 abstracts screened, 203 full-text articles were examined. In 31 studies (n=2403 infants with NEC), NDI incidence was 40% (IQR 28%-64%) and was higher in infants with surgically treated NEC (43%) compared with medically managed NEC (27%, p<0.00001). The most common NDI in NEC was cerebral palsy (18%). Cerebral lesions: intraventricular haemorrhage (IVH) was more common in NEC babies (26%) compared with preterm infants (18%; p<0.0001). There was no difference in IVH incidence between infants with surgical NEC (25%) and those treated medically (20%; p=0.4). The incidence of periventricular leukomalacia (PVL) was significantly increased in infants with NEC (11%) compared with preterm infants (5%; p<0.00001).

CONCLUSIONS

This study shows that a large proportion of NEC survivors has NDI. NEC babies are at higher risk of developing IVH and/or PVL than babies with prematurity alone. The degree of NDI seems to correlate to the severity of gut damage, with a worse status in infants with surgical NEC compared with those with medical NEC.

TRIAL REGISTRATION NUMBER

CRD42019120522.

Exposure to nonylphenol in early life increases pro-inflammatory cytokines in the prefrontal cortex: Involvement of gut-brain communication

A growing body of evidence indicates that exposure to nonylphenol (NP), a typical persistent organic pollutant (POP), in early life results in the impairment of the central nervous system (CNS), but the underlying mechanism still remains to be elucidated. High levels of pro-inflammatory cytokines in the brain have been implicated in the CNS damages. The animal model of exposure to NP in early life was established by maternal gavage during the pregnancy and lactation in the present study. We found that exposure to NP in early life increased the levels of pro-inflammatory cytokines in the rat prefrontal cortex. Interestingly, the levels of pro-inflammatory cytokines in the intestine as well as in the serum were also increased by NP exposure. Furthermore, the increased permeability of intestinal barrier and blood-brain barrier (BBB), two critical barriers in the gut to brain communication, was observed in the rats exposed to NP in early lives. The decreased expression of zonula occludens-1 (ZO-1) and claudin-1 (CLDN-1), tight junction proteins (TJs) that responsible for maintaining the permeability of intestinal barrier and BBB, was found, which may underlie these increases in permeability. Taken together, these results suggested that the disturbed gut-brain communication may contribute to the increased levels of pro-inflammatory cytokines in the prefrontal cortex caused by NP exposure in early life.

Calcium/calmodulin-dependent protein kinase IV signaling pathway is upregulated in experimental necrotizing enterocolitis

PURPOSE

Activation of calcium/calmodulin-dependent protein kinase IV (CaMKIV) has been shown to increase intestinal injury and inhibit epithelial cell proliferation in dextran sulfate sodium (DSS)-induced colitis mice. However, the role of CaMKIV in necrotizing enterocolitis (NEC) is unknown. We aimed to study the expression and activation of CaMKIV in experimental NEC.

METHODS

Following ethical approval, NEC (n = 10) was induced in C57BL/6 mouse pups by hypoxia, gavage hyperosmolar formula feeding and lipopolysaccharide from postnatal days P5 to 9. Breastfed pups served as control (n = 10). Mouse pups were sacrificed on P9 and the terminal ileum was harvested. Gene NEC injury was scored blindly by three independent investigators. CaMKIV, CREM and IL17 gene expression, and CaMKIV and pCaMKIV protein expression were assessed. The data were compared using Mann-Whitney U test. P < 0.05 was considered significant.

RESULTS

Intestinal injury was induced in the NEC mice and confirmed by histological scoring and inflammatory cytokine IL6. CaMKIV and its downstream target genes of CREM and IL17 were significantly elevated in NEC mice relative to control. Similarly, phosphorylated-CaMKIV (pCaMKIV), the active form of CaMKIV, was more notably expressed in the NEC ileal tissue relative to control ileal tissue. Elevated pCaMKIV protein expression was also confirmed by western blot.

CONCLUSION

CaMKIV expression and activation are upregulated in experimental NEC suggesting a potential contributing factor in the pathogenesis of NEC.

Premature birth, homeostatic plasticity and respiratory consequences of inflammation

Infants who are born premature can have persistent apnea beyond term gestation, reemergence of apnea associated with inflammation during infancy, increased risk of sudden unexplained death, and sleep disorder breathing during infancy and childhood. The autonomic nervous system, particularly the central neural networks that control breathing and peripheral and central chemoreceptors and mechanoreceptors that modulate the activity of the central respiratory network, are rapidly developing during the last trimester (22-37 weeks gestation) of fetal life. With advances in neonatology, in well-resourced, developed countries, infants born as young as 23 weeks gestation can survive. Thus, a substantial part of maturation of central and peripheral systems that control breathing occurs ex-utero in infants born at the limit of viability. The balance of excitatory and inhibitory influences dictates the ultimate output from the central respiratory network. We propose in this review that simply being born early in the last trimester can trigger homeostatic plasticity within the respiratory network tipping the balance toward inhibition that persists in infancy. We discuss the intersection of premature birth, homeostatic plasticity and biological mechanisms leading to respiratory depression during inflammation in former premature infants.

The role of the gut microbiome in mediating neurotoxic outcomes to PCB exposure

A series of complex physiological processes underlie the development of the microbiota, gut, and brain in early life, which together communicate via the microbiota-gut-brain axis to maintain health and homeostasis. Disruption of these processes can lead to dysbiosis of the microbiota, pathophysiology of the gut and behavioral deficits including depression, anxiety and cognitive deficits. Environmental exposures, particularly in early life, can interfere with development and impact these pathways. This review will focus on the role of the microbiome and the gut in neurodevelopment and neurodegeneration as well as the impacts of environmental exposures, particularly to the neurotoxicant polychlorinated biphenyls (PCBs), given that the gut serves as the primary exposure route. There exists extensive research on the importance of the microbiome in the developing brain and connections with autism spectrum disorder (ASD) and increasing links being established between the microbiome and development of Alzheimer's disease (AD) in the elderly. Finally, we will speculate on the mechanisms through which PCBs can induce dysbiosis and dysregulate physiology of the gut and brain.

Extracellular Vesicles as a Potential Therapy for Neonatal Conditions: State of the Art and Challenges in Clinical Translation

Despite advances in intensive care, several neonatal conditions typically due to prematurity affect vital organs and are associated with high mortality and long-term morbidities. Current treatment strategies for these babies are only partially successful or are effective only in selected patients. Regenerative medicine has been shown to be a promising option for these conditions at an experimental level, but still warrants further exploration for the development of optimal treatment. Although stem cell-based therapy has emerged as a treatment option, studies have shown that it is associated with potential risks and hazards, especially in the fragile population of babies. Recently, extracellular vesicles (EVs) have emerged as an attractive therapeutic alternative that holds great regenerative potential and is cell-free. EVs are nanosized particles endogenously produced by cells that mediate intercellular communication through the transfer of their cargo. Currently, EVs are garnering considerable attention as they are the key effectors of stem cell paracrine signaling and can epigenetically regulate target cell genes through the release of RNA species, such as microRNA. Herein, we review the emerging literature on the therapeutic potential of EVs derived from different sources for the treatment of neonatal conditions that affect the brain, retinas, spine, lungs, and intestines and discuss the challenges for the translation of EVs into clinical practice.