Cardiac tissue model of immune-induced dysfunction reveals the role of free mitochondrial DNA and the therapeutic effects of exosomes

Despite tremendous progress in the development of mature heart-on-a-chip models, human cell-based models of myocardial inflammation are lacking. Here, we bioengineered a vascularized heart-on-a-chip with circulating immune cells to model severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-induced acute myocarditis. We observed hallmarks of coronavirus disease (COVID-19)-induced myocardial inflammation, as the presence of immune cells augmented the secretion of proinflammatory cytokines, triggered progressive impairment of contractile function, and altered intracellular calcium transients. An elevation of circulating cell-free mitochondrial DNA (ccf-mtDNA) was measured first in the heart-on-a-chip and then validated in COVID-19 patients with low left ventricular ejection fraction, demonstrating that mitochondrial damage is an important pathophysiological hallmark of inflammation-induced cardiac dysfunction. Leveraging this platform in the context of SARS-CoV-2-induced myocardial inflammation, we established that administration of endothelial cell-derived exosomes effectively rescued the contractile deficit, normalized calcium handling, elevated the contraction force, and reduced the ccf-mtDNA and cytokine release via Toll-like receptor-nuclear factor κB signaling axis.

Rack1-mediated ferroptosis affects hindgut development in rats with anorectal malformations: Spatial transcriptome insights

Anorectal malformation (ARM), a common congenital anomaly of the digestive tract, is a result of insufficient elongation of the urorectal septum. The cytoplasmic protein Receptor of Activated C-Kinase 1 (Rack1) is involved in embryonic neural development; however, its role in embryonic digestive tract development and ARM formation is unexplored. Our study explored the hindgut development and cell death mechanisms in ARM-affected rats using spatial transcriptome analysis. We induced ARM in rats by administering ethylenethiourea via gavage on gestational day (GD) 10. On GDs 14-16, embryos from both normal and ARM groups underwent spatial transcriptome sequencing, which identified key genes and signalling pathways. Rack1 exhibited significant interactions among differentially expressed genes on GDs 15 and 16. Reduced Rack1 expression in the ARM-affected hindgut, verified by Rack1 silencing in intestinal epithelial cells, led to increased P38 phosphorylation and activation of the MAPK signalling pathway. The suppression of this pathway downregulated Nqo1 and Gpx4 expression, resulting in elevated intracellular levels of ferrous ions, reactive oxygen species (ROS) and lipid peroxides. Downregulation of Gpx4 expression in the ARM hindgut, coupled with Rack1 co-localisation and consistent mitochondrial morphology, indicated ferroptosis. In summary, Rack1, acting as a hub gene, modulates ferrous ions, lipid peroxides, and ROS via the P38-MAPK/Nqo1/Gpx4 axis. This modulation induces ferroptosis in intestinal epithelial cells, potentially influencing hindgut development during ARM onset.

Human milk oligosaccharides promote intestinal epithelium regeneration independent of the microbiota during necrotizing enterocolitis

PURPOSE

Necrotizing enterocolitis (NEC) is a severe intestinal disease primarily affecting premature infants, marked by impaired epithelial regeneration. Breastfed infants are less susceptible to NEC than formula-fed ones, and human milk oligosaccharides (HMO) found in breast milk have prebiotic properties that can protect against NEC. However, it is unclear how HMOs influence intestinal epithelium regeneration in relation to the gut microbiota.

METHODS

Broad-spectrum antibiotics were administered to pregnant dams to reduce the microbiota in offspring. NEC was induced through administration of hyperosmolar formula, lipopolysaccharide, and hypoxia from postnatal days (p) 5-9. Intestinal epithelial organoids were derived from p9 mice. HMOs were isolated from human donor breast milk and then solubilized in the formula for each feed or culture media for organoids.

RESULTS

HMOs did not alter the microbiota profile in the presence of a normal or reduced microbiota. In the reduced microbiota, HMO treatment decreased NEC intestinal injury, and increased proliferation and stem cell activity. Additionally, in the complete absence of the microbiota, HMOs stimulated intestinal organoid growth.

CONCLUSION

This study demonstrates that HMOs promoted intestinal epithelial regeneration independent of the gut microbiota. These findings provide further insight into the various benefits HMOs may have in the protection against NEC.

Argon inhalation attenuates systemic inflammation and rescues lung architecture during experimental neonatal sepsis

PURPOSE

Neonatal sepsis is a systemic inflammatory infection common in premature infants and a leading cause of mortality. Argon is an emerging interest in the field of noble gas therapy. Neonates with severe sepsis are frequently mechanically ventilated creating an opportunity for inhalation therapy. We aimed to investigate argon inhalation as a novel experimental therapy in neonatal sepsis.

METHODS

Sepsis was established in C57BL/6 neonatal mice by a lipopolysaccharide intraperitoneal injection on postnatal day 9. Septic pup mice were exposed to room air as well as non-septic controls. In the argon group, septic pup mice were exposed to argon (70% Ar, 30% O2) for 6 h in a temperature-controlled environment.

RESULTS

At 6 h, survival was significantly enhanced when septic mice received argon compared to septic controls. Serum profiles of cytokine release were significantly attenuated as well as lung architecture restored.

CONCLUSIONS

Our findings suggest that argon inhalation as a novel treatment for neonatal sepsis, reducing mortality and counteracting the acute systemic inflammatory response in the blood and preserving the architecture of the lung. This research can contribute to a paradigm shift in the treatment and outcome of neonates with sepsis.

A novel mouse model of intestinal neuronal dysplasia: visualization of the enteric nervous system

PURPOSE

Intestinal neuronal dysplasia (IND) is a congenital anomaly affecting gastrointestinal neural innervation, but the pathogenesis remains unclear. The homozygous Ncx/Hox11L.1 knockout (Ncx-/-) mice exhibit megacolon and enteric ganglia anomalies, resembling IND phenotypes. Sox10-Venus transgenic mouse were used to visualize enteric neural crest cells in real time. This study aims to establish a novel mouse model of Sox10-Venus+/Ncx-/- mouse to study the pathogenesis of IND.

METHODS

Sox10-Venus+/Ncx-/- (Ncx-/-) (n = 8) mice and Sox10-Venus+/Ncx+/+ controls (control) (n = 8) were euthanized at 4-5 weeks old, and excised intestines were examined with fluorescence microscopy. Immunohistochemistry was performed on tissue sections with neural marker Tuj1.

RESULTS

Ncx-/- mice exhibited dilated cecum and small intestine. Body weight of Ncx-/- mice was lower with higher ratio of small intestine length relative to body weight. The neural network (Sox10-Venus) was observed along the intestine wall in Ncx-/- and control mice without staining. Ectopic and increased expression of Tuj1 was observed in both small intestine and proximal colon of Ncx-/- mice.

CONCLUSION

This study has established a reliable animal model that exhibits characteristics similar to patients with IND. This novel mouse model can allow the easy visualization of ENS in a time- and cost-effective way to study the pathogenesis of IND.

Comparison of conventional mechanical ventilation and high-frequency oscillatory ventilation in congenital diaphragmatic hernias: a systematic review and meta-analysis

Outcomes of conventional mechanical ventilation (CMV) and high-frequency oscillatory ventilation (HFOV) in patients with congenital diaphragmatic hernia (CDH) were compared through a systematic review and meta-analysis. Outcome measures included mortality and incidence of chronic lung disease (CLD). Odds ratio (OR) and 95% confidence interval (95%CI) were evaluated. Subgroup analyses were performed according to the strategy for applying HFOV in CDH patients. Group A: CMV was initially applied in all CDH patients, and HFOV was applied in unstable patients. Group B: chronologically analyzed. (CMV and HFOV era) Group C: CMV or HFOV was used as the initial MV. Of the 2199 abstracts screened, 15 full-text articles were analyzed. Regarding mortality, 16.7% (365/2180) and 32.8% (456/1389) patients died in CMV and HFOV, respectively (OR, 2.53; 95%CI 2.12-3.01). Subgroup analyses showed significantly worse, better, and equivalent mortality for HFOV than that for CMV in group A, B, and C, respectively. CLD occurred in 32.4% (399/1230) and 49.3% (369/749) patients in CMV and HFOV, respectively (OR, 2.37; 95%CI 1.93-2.90). The evidence from the literature is poor. Mortality and the incidence of CLD appear worse after HFOV in children with CDH. Cautious interpretation is needed due to the heterogeneity of each study.

Maturational effect of leptin on CO2 chemosensitivity in newborn rats

BACKGROUND

Leptin augments central CO2 chemosensitivity and stabilizes breathing in adults. Premature infants have unstable breathing and low leptin levels. Leptin receptors are on CO2 sensitive neurons in the Nucleus Tractus Solitarius (NTS) and locus coeruleus (LC). We hypothesized that exogenous leptin improves hypercapnic respiratory response in newborn rats by improving central CO2 chemosensitivity.

METHODS

In rats at postnatal day (p)4 and p21, hyperoxic and hypercapnic ventilatory responses, and pSTAT and SOCS3 protein expression in the hypothalamus, NTS and LC were measured before and after treatment with exogenous leptin (6 µg/g).

RESULTS

Exogenous leptin increased the hypercapnic response in p21 but not in p4 rats (P ≤ 0.001). At p4, leptin increased pSTAT expression only in the LC, and SOCS3 expression in the NTS and LC; while at p21 pSTAT and SOCS3 levels were higher in the hypothalamus, NTS, and LC (P ≤ 0.05).

CONCLUSIONS

We describe the developmental profile of the effect of exogenous leptin on CO2 chemosensitivity. Exogenous leptin does not augment central CO2 sensitivity during the first week of life in newborn rats. The translational implication of these findings is that low plasma leptin levels in premature infants may not be contributing to respiratory instability.

IMPACT

Exogenous leptin does not augment CO2 sensitivity during the first week of life in newborn rats, similar to the developmental period when feeding behavior is resistant to leptin. Exogenous leptin increases CO2 chemosensitivity in newborn rats after the 3rd week of life and upregulates the expression of pSTAT and SOC3 in the hypothalamus, NTS and LC. Low plasma leptin levels in premature infants are unlikely contributors to respiratory instability via decreased CO2 sensitivity in premature infants. Thus, it is highly unlikely that exogenous leptin would alter this response.

Intestinal microRNAs and bacterial taxa in juvenile mice are associated, modifiable by allochthonous lactobacilli, and affect postnatal maturation

The interplay between the intestinal microbiota and host is critical to intestinal ontogeny and homeostasis. MicroRNAs (miRNAs) may be an underlying link. Intestinal miRNAs are microbiota-dependent and, when shed in the lumen, affect resident microorganisms. Yet, longitudinal relationships between intestinal tissue miRNAs, luminal miRNAs, and luminal microorganisms have not been elucidated, especially in early life. Here, we investigated the postnatal cecal miRNA and microbiota populations, their relationship, and their impact on intestinal maturation in specific pathogen-free mice; we also assessed if they can be modified by intervention with allochthonous probiotic lactobacilli. We report that cecal and cecal content miRNA and microbiota signatures are temporally regulated, correlated, and modifiable by probiotics with implications for intestinal maturation. These findings help understand causal relationships within the gut ecosystem and provide a basis for preventing and managing their alterations in diseases throughout life. IMPORTANCE The gut microbiota affects intestinal microRNA (miRNA) signatures and is modified by host-derived luminal miRNA. This suggests the existence of close miRNA-microbiota relationships that are critical to intestinal homeostasis. However, an integrative analysis of these relationships and their evolution during intestinal postnatal maturation is lacking. We provide a system-level longitudinal analysis of miRNA-microbiota networks in the intestine of mice at the weaning transition, including tissue and luminal miRNA and luminal microbiota. To address causality and move toward translational applications, we used allochthonous probiotic lactobacilli to modify these longitudinal relationships and showed that they are critical for intestinal maturation in early life. These findings contribute to understand mechanisms that underlie the maturation of the intestinal ecosystem and suggest that interventions aiming at maintaining, or restoring, homeostasis cannot prescind from considering relationships among its components.

Heart-on-a-chip model of immune-induced cardiac dysfunction reveals the role of free mitochondrial DNA and therapeutic effects of endothelial exosomes

Cardiovascular disease continues to take more human lives than all cancer combined, prompting the need for improved research models and treatment options. Despite a significant progress in development of mature heart-on-a-chip models of fibrosis and cardiomyopathies starting from induced pluripotent stem cells (iPSCs), human cell-based models of myocardial inflammation are lacking. Here, we bioengineered a vascularized heart-on-a-chip system with circulating immune cells to model SARS-CoV-2-induced acute myocarditis. Briefly, we observed hallmarks of COVID-19-induced myocardial inflammation in the heart-on-a-chip model, as the presence of immune cells augmented the expression levels of proinflammatory cytokines, triggered progressive impairment of contractile function and altered intracellular calcium transient activities. An elevation of circulating cell-free mitochondrial DNA (ccf-mtDNA) was measured first in the in vitro heart-on-a-chip model and then validated in COVID-19 patients with low left ventricular ejection fraction (LVEF), demonstrating that mitochondrial damage is an important pathophysiological hallmark of inflammation induced cardiac dysfunction. Leveraging this platform in the context of SARS-CoV-2 induced myocardial inflammation, we established that administration of human umbilical vein-derived EVs effectively rescued the contractile deficit, normalized intracellular calcium handling, elevated the contraction force and reduced the ccf- mtDNA and chemokine release via TLR-NF-kB signaling axis.

Association of new sonographic features with outcome in neonates with necrotizing enterocolitis

BACKGROUND

We have recently noted some sonographic features in necrotizing enterocolitis that have received little or no attention in the current literature. These include thickening of the mesentery, hyperechogenicity of intraluminal intestinal contents, abnormalities of the abdominal wall, and poor definition of the intestinal wall. It has been our impression that the above four sonographic findings are generally seen in neonates with more severe necrotizing enterocolitis and may be useful in predicting outcome.

OBJECTIVES

The aim of this study is, firstly, to review a large series of neonates, known to have clinical NEC, to document how frequently the above four sonographic features occur in neonates with necrotizing enterocolitis and, secondly, to determine whether they are predictive of outcome.

MATERIALS AND METHODS

We retrospectively analyzed the clinical, radiographic, sonographic, and surgical findings in neonates with necrotizing enterocolitis between 2018 and 2021. The neonates were categorized into two groups based on outcome. Group A included neonates with a favorable outcome defined as successful medical treatment with no surgical intervention. Group B included neonates with an unfavorable outcome defined as failed medical treatment requiring surgery (for acute complications or late strictures) or death because of necrotizing enterocolitis. The sonographic examinations were reviewed with attention to the features of mesenteric thickening, hyperechogenicity of intraluminal intestinal contents, abnormalities of the abdominal wall, and poor definition of the intestinal wall. We then determined the association of these four findings with the two groups.

RESULTS

We included 102 neonates with clinical necrotizing enterocolitis: 45 in group A and 57 in group B. Neonates in group B were born at a significantly earlier gestational age (median 25 weeks, range 22-38 weeks) and had a significantly lower birth weight (median 715.5 g, range 404-3120 g) than those in group A (median age 32 weeks, range 22-39 weeks, p = 0.003; median weight 1190 g, range 480-4500 g, p = 0.002). The four sonographic features were present in both study groups but with different frequency. More importantly, all four were statistically significantly more frequently present in neonates in group B compared to group A: (i) mesenteric thickening, A = 31 (69%), B = 52 (91%), p = 0.007; (ii) hyperechogenicity of intestinal contents, A = 16 (36%), B = 41 (72%), p = 0.0005; (iii) abnormalities of the abdominal wall, A = 11 (24%), B = 35 (61%), p = 0.0004; and (iv) poor definition of the intestinal wall, A = 7 (16%), B = 25 (44%), p = 0.005. Furthermore, the proportion of neonates with more than two signs was greater in group B compared to group A (Z test, p < 0.0001, 95% CI = 0.22-0.61).

CONCLUSION

The four new sonographic features described were found to occur statistically significantly more frequently in those neonates with an unfavorable outcome (group B) than in those with a favorable outcome (group A). The presence or absence of these signs should be included in the sonographic report to convey the radiologists concern regarding the severity of the disease in every neonate, suspected or known to have necrotizing enterocolitis, as the findings may impact further medical or surgical management.

Laparotomy versus Peritoneal Drainage as Primary Treatment for Surgical Necrotizing Enterocolitis or Spontaneous Intestinal Perforation in Preterm Neonates: A Systematic Review and Meta-Analysis

AIM

to systematically review and meta-analyze the impact on morbidity and mortality of peritoneal drainage (PD) compared to laparotomy (LAP) in preterm neonates with surgical NEC (sNEC) or spontaneous intestinal perforation (SIP).

METHODS

Medical databases were searched until June 2022 for studies comparing PD and LAP as primary surgical treatment of preterm neonates with sNEC or SIP. The primary outcome was survival during hospitalization; predefined secondary outcomes included need for parenteral nutrition at 90 days, time to reach full enteral feeds, need for subsequent laparotomy, duration of hospitalization and complications.

RESULTS

Three RCTs (N = 493) and 49 observational studies (N = 19,447) were included. No differences were found in the primary outcome for RCTs, but pooled observational data showed that, compared to LAP, infants with sNEC/SIP who underwent PD had lower survival [48 studies; N = 19,416; RR 0.85; 95% CI 0.79-0.90; GRADE: low]. Observational studies also showed that the subgroup of infants with sNEC had increased survival in the LAP group (30 studies; N = 9370; RR = 0.82; 95% CI 0.72-0.91; GRADE: low).

CONCLUSIONS

Compared to LAP, PD as primary surgical treatment for sNEC or SIP has similar survival rates when analyzing data from RCTs. PD was associated with lower survival rates in observational studies.

Bovine milk-derived exosomes attenuate NLRP3 inflammasome and NF-κB signaling in the lung during neonatal necrotizing enterocolitis

PURPOSE

Necrotizing enterocolitis (NEC), an inflammatory intestinal disease common in premature infants, has been associated with the development of lung damage. Toll-like receptor 4 has been shown to regulate inflammation in the NEC lungs, however, other important inflammatory mechanisms have not been thoroughly investigated. In addition, we reported that milk-derived exosomes were able to attenuate intestinal injury and inflammation in experimental NEC. This study aims to (i) investigate the role of the NLRP3 inflammasome and NF-κB pathway in regulating lung damage during experimental NEC; and (ii) evaluate the therapeutic potential of bovine milk exosomes in reducing lung inflammation and injury during NEC.

METHODS

NEC was induced by gavage feeding of hyperosmolar formula, hypoxia, and lipopolysaccharide administration in neonatal mice from postnatal days 5-9. Exosomes were obtained by ultracentrifugation of bovine milk and administered during each formula feed.

RESULTS

The lung of NEC pups showed increased inflammation, tissue damage, NLRP3 inflammasome expression, and NF-κB pathway activation, which were attenuated upon exosome administration.

CONCLUSION

Our findings suggest that the lung undergoes significant inflammation and injury following experimental NEC which are attenuated by bovine milk-derived exosomes. This emphasizes the therapeutic potential of exosomes not just on the intestine but also on the lung.

Remote ischemic conditioning in necrotizing enterocolitis

Necrotizing enterocolitis (NEC) is a devastating intestinal inflammatory disorder, most prevalent in premature infants, and associated with a high mortality rate that has remained unchanged in the past two decades. NEC is characterized by inflammation, ischemia, and impaired microcirculation in the intestine. Preclinical studies by our group have led to the discovery of remote ischemic conditioning (RIC) as a promising non-invasive intervention in protecting the intestine against ischemia-induced damage during early-stage NEC. RIC involves the administration of brief reversible cycles of ischemia and reperfusion in a limb (similar to taking standard blood pressure measurement) which activate endogenous protective signaling pathways that are conveyed to distant organs such as the intestine. RIC targets the intestinal microcirculation and by improving blood flow to the intestine, reduces the intestinal damage of experimental NEC and prolongs survival. A recent Phase I safety study by our group demonstrated that RIC was safe in preterm infants with NEC. A phase II feasibility randomized controlled trial involving 12 centers in 6 countries is currently underway, to investigate the feasibility of RIC as a treatment for early-stage NEC in preterm neonates. This review provides a brief background on RIC as a therapeutic strategy and summarizes the progression of RIC as a treatment for NEC from preclinical investigation to clinical evaluation.

Development of liver inflammatory injury in biliary atresia: from basic to clinical research

Biliary atresia (BA) is a severe cholangiopathy in infants. It is characterized by inflammatory fibro-obliteration of the intra- and extrahepatic bile ducts. Although the restoration of bile flow can be successful after Kasai operation, the rapid progression of liver fibrosis can continue, leading to cirrhosis. It is believed that the progression of liver fibrosis in BA is exacerbated by complicated mechanisms other than the consequence of bile duct obstruction. The fibrogenic cascade in BA liver can be divided into three stages, including liver inflammatory injury, myofibroblast activation, and fibrous scar formation. Recent studies have revealed that the activation of an immune response following bile duct injury plays an important role in promoting the inflammatory process, the releasing of inflammatory cytokines, and the development of fibrogenesis in BA liver. In this article, we summarized the evidence regarding liver inflammatory injury and the possible mechanisms that explain the rapid progression of liver fibrosis in BA.

Necrotizing enterocolitis: recent advances in treatment with translational potential

Necrotizing enterocolitis (NEC) is one of the most prevalent and devastating gastrointestinal disorders in neonates. Despite advances in neonatal care, the incidence and mortality due to NEC remain high, highlighting the need to devise novel treatments for this disease. There have been a number of recent advancements in therapeutic approaches for the treatment of NEC; these involve remote ischemic conditioning (RIC), stem cell therapy, breast milk components (human milk oligosaccharides, exosomes, lactoferrin), fecal microbiota transplantation, and immunotherapy. This review summarizes the most recent advances in NEC treatment currently underway as well as their applicability and associated challenges and limitations, with the aim to provide new insight into the paradigm of care for NEC worldwide.

A9 INTESTINAL ORGANOID TRANSPLANTATION REVERSED THE INTESTINAL EPITHELIUM DAMAGE IN EXPERIMENTAL NECROTIZING ENTEROCOLITIS

NOT PUBLISHED AT AUTHOR’S REQUEST

Elective Delivery versus Expectant Management for Gastroschisis: A Systematic Review and Meta-Analysis

INTRODUCTION

 The optimal timing of delivery for pregnancies complicated by prenatally diagnosed gastroschisis remains controversial. Therefore, the aim of this study was to find whether elective or expectant delivery is associated with improved neonatal outcome.

MATERIALS AND METHODS

 MEDLINE and Embase databases were searched for studies up to 2021 that reported timing of delivery for prenatally diagnosed gastroschisis. A systematic review and meta-analysis were then performed in group 1: moderately preterm (gestational age [GA]: 34-35 weeks) elective delivery versus expectant management after GA 34-35 weeks; and group 2: near-term (GA: 36-37 weeks) elective delivery versus expectant management after GA 36-37 weeks. The following clinical outcomes were evaluated: length of stay (LOS), total parenteral nutrition (TPN) days, bowel morbidity (atresia, perforation, and volvulus), sepsis, time of first feeding, short gut syndrome and respirator days, and mortality.

RESULTS

 Two randomized controlled trials (RCT)s and eight retrospective cohort studies were included, comprising 629 participants. Moderately preterm elective delivery failed to improve clinical outcomes. However, near-term elective delivery significantly reduced bowel morbidity (7.4 vs. 15.4%, relative risk = 0.37; 95% confidence interval [CI]: 0.18, 0.74; p = 0.005; I2 = 0%) and TPN days (mean difference =-13.44 days; 95% CI: -26.68, -0.20; p = 0.05; I2 = 45%) compared to expectant delivery. The mean LOS was 39.2 days after near-term delivery and 48.7 days in the expectant group (p = 0.06).

CONCLUSION

 Based on the data analyzed, near-term elective delivery (GA 36-37 weeks) appears to be the optimal timing for delivery of pregnancies complicated by gastroschisis as it is associated with less bowel morbidity and shorter TPN days. However, more RCTs are necessary to better validate these findings.

Family care reduces the incidence of neonatal sepsis: A systematic review and meta-analysis

Purpose

Family-involved care in the neonatal intensive care unit (NICU) helps to alleviate neonatal anxiety and promotes breastmilk intake, body growth and neurological development, but its effect on reducing the incidence of neonatal sepsis is not known. We conducted a systematic review and meta-analysis of randomized controlled trials (RCT) to evaluate whether neonates receiving family care have a lower incidence of neonatal sepsis compared to neonates receiving standard NICU care.

Methods

MEDLINE, Embase, Web of Science, and CENTRAL were searched for RCTs that compared preterm neonates receiving family care vs. standard NICU care. From 126 articles that were identified and screened, 34 full-text articles were assessed for eligibility, and 5 RCTs were included. The primary outcome was the development of sepsis. The RevMan 5.4 software was used to conduct the Meta-analysis.

Results

The metanalysis, based on 5 RCTs demonstrated that neonates receiving family-involved care had significantly lower incidence of sepsis (12.0% vs. 16.3%), increased body weight, and reduced length of hospital stay compared to those receiving standard NICU care.

Conclusion

This study suggests that family-involved care in NICU can (i) reduce the incidence of neonatal sepsis, (ii) improve growth, and (iii) reduce the length of hospital stay. This study highlights the need for evaluating whether family-involved care improves other neonatal outcomes.

Remote ischaemic conditioning in necrotising enterocolitis: a phase I feasibility and safety study

OBJECTIVE

Remote ischaemic conditioning (RIC) improves the outcome of experimental necrotising enterocolitis (NEC) by preserving intestinal microcirculation. The feasibility and safety of RIC in preterm infants with NEC are unknown. The study aimed to assess the feasibility and safety of RIC in preterm infants with suspected or confirmed NEC.

DESIGN

Phase I non-randomised pilot study conducted in three steps: step A to determine the safe duration of limb ischaemia (up to 4 min); step B to assess the safety of 4 repeated cycles of ischaemia-reperfusion at the maximum tolerated duration of ischaemia determined in step A; step C to assess the safety of applying 4 cycles of ischaemia-reperfusion on two consecutive days.

SETTING

Level III neonatal intensive care unit, The Hospital for Sick Children (Toronto, Canada).

PATIENTS

Fifteen preterm infants born between 22 and 33 weeks gestational age.

INTERVENTION

Four cycles of ischaemia (varying duration) applied to the limb via a manual sphygmomanometer, followed by reperfusion (4 min) and rest (5 min), repeated on two consecutive days.

OUTCOMES

The primary outcomes were (1) feasibility defined as RIC being performed as planned in the protocol, and (2) safety defined as perfusion returning to baseline within 4 min after cuff deflation.

RESULTS

Four cycles/day of limb ischaemia (4 min) followed by reperfusion (4 min) and a 5 min gap, repeated on two consecutive days was feasible and safe in all neonates with suspected or confirmed NEC.

CONCLUSIONS

This study is pivotal for designing a future randomised controlled trial to assess the efficacy of RIC in preterm infants with NEC.

TRIAL REGISTRATION NUMBER

NCT03860701.

Gut microbiota promotes stem cell differentiation through macrophage and mesenchymal niches in early postnatal development

Intestinal stem cell maturation and development coincide with gut microbiota exposure after birth. Here, we investigated how early life microbial exposure, and disruption of this process, impacts the intestinal stem cell niche and development. Single-cell transcriptional analysis revealed impaired stem cell differentiation into Paneth cells and macrophage specification upon antibiotic treatment in early life. Mouse genetic and organoid co-culture experiments demonstrated that a CD206+ subset of intestinal macrophages secreted Wnt ligands, which maintained the mesenchymal niche cells important for Paneth cell differentiation. Antibiotics and reduced numbers of Paneth cells are associated with the deadly infant disease, necrotizing enterocolitis (NEC). We showed that colonization with Lactobacillus or transfer of CD206+ macrophages promoted Paneth cell differentiation and reduced NEC severity. Together, our work defines the gut microbiota-mediated regulation of stem cell niches during early postnatal development.

Intestinal atresia and necrotizing enterocolitis: Embryology and anatomy

The primitive gut originates at week 3 of gestation from the endoderm, with posterior incorporation of the remaining embryo layers. Wnt, Notch and TLR4 pathways have been shown to play central roles in the correct development of the intestine. The classical hypothesis for intestinal atresia development consists of failure in bowel recanalization or a vascular accident with secondary bowel reabsorption. These have been challenged due to the high frequency of associated malformations, and furthermore, with the discovery of molecular pathways and genes involved in bowel formation and correlated defects producing atresia. Necrotizing enterocolitis (NEC) has a multifactorial pathogenesis with prematurity being the most important risk factor; therefore, bowel immaturity plays a central role in NEC. Some of the same molecular pathways involved in gut maturation have been found to correlate with the predisposition of the immature bowel to develop the pathological findings seen in NEC.

Hirschsprung-Associated Enterocolitis: Transformative Research from Bench to Bedside

Hirschsprung disease (HSCR) is a congenital disease that is characterized by the absence of intrinsic ganglion cells in the submucosal and myenteric plexuses of the distal colon and is the most common cause of congenital intestinal obstruction. Hirschsprung-associated enterocolitis (HAEC) is a life-threatening complication of HSCR, which can occur either before or after surgical resection of the aganglionic bowel. Even though HAEC is a leading cause of death in HSCR patients, its etiology and pathophysiology remain poorly understood. Various factors have been associated with HAEC, including the mucus barrier, microbiota, immune function, obstruction of the colon, and genetic variations. In this review, we examine our current mouse model of HAEC and how it informs our understanding of the disease. We also describe current emerging research that highlights the potential future of HAEC treatment.

Human breast milk-derived exosomes protect against intestinal ischemia and reperfusion injury in neonatal rats

BACKGROUND

Intestinal ischemia and reperfusion (IR) injury like that seen in midgut volvulus can be life-threatening in the pediatric population. Human breast milk-derived exosomes (HMDEs) can prevent intestinal inflammation in experimental necrotizing enterocolitis and other intestinal diseases. The aim of this study is to investigate the effects of HMDEs on intestinal damage related to IR injury.

METHODS

Exosomes were isolated from human breast milk by ultracentrifugation then confirmed by Nanoparticle tracking analysis and detection of exosome membrane markers. 2-weeks old Sprague Dawley rats were randomly divided into 4 groups: a) Sham (n = 8) with laparotomy alone, b) Sham with HMDEs administration by gavage (n = 8), c) Intestinal IR injury (n = 8) by occlusion of the superior mesenteric artery (SMA) for 30 min followed by reperfusion, and d) Intestinal IR by SMA occlusion with HMDEs administration by gavage (n = 8). Six hours after laparotomy, animals were euthanized, and the ilea (10 cm to cecum) were harvested. Mucosal injury was scored histologically. The intestines were further examined for inflammatory cytokine TNFα, and epithelial proliferation marker Ki67.

RESULTS

Compared to sham, the small intestine of IR rats had more intestinal damage, increased expression of inflammatory cytokine TNFα and decreased intestinal proliferation. HMDEs significantly counteracted all these changes.

CONCLUSIONS

Human breast milk-derived exosomes protect the intestine against damage by IR injury. This beneficial effect is associated with decreased intestinal inflammation and enhanced epithelial proliferation. This study implicates the potential novel application of HMDEs in preventing intestinal damage in infants with intestinal IR injury.

Extra-Pleural Pneumonectomy (EPP) in Children and Adults with Locally Advanced Sarcoma: A CanSaRCC Study

Simple Summary

Extra-pleural pneumonectomy (EPP) involves the removal of the parietal and visceral pleura, ipsilateral lungs, pericardium, and hemi diaphragm. In patients with advanced sarcoma in the pleura, EPP is often the only option for local control. The aim of our study was to review our institutional experience with EPP. Of ten patients in our study, five were alive without disease at last follow-up after multi-modality therapy including EPP. Two patients had local recurrence and died of progressive disease. One patient died of brain metastasis, one patient died of radiation induced sarcoma, and one patient died of surgical complications. Our results suggest that EPP is a feasible option for patients when used in combination with chemotherapy and radiation. Moreover, high-volume cancer centers should discuss the use of EPP during tumor board discussion.

Abstract

Sarcoma can present as locally advanced disease involving pleura for which extra-pleural pneumonectomy (EPP) may be the only surgical option to ensure adequate local control. Data were collected on patients who underwent EPP between January 2009 and August 2021 at Princess Margret Hospital and SickKids (Toronto) using the CanSaRCC (Canadian Sarcoma Research and Clinical Collaboration). Ten patients with locally advanced sarcoma involving the pleura, aged 4 to 59 years (median 19.5 years) underwent EPP. Nine (90%) received pre-operative chemotherapy and eight (80%) achieved an R0 resection. Hemithoracic radiation was administered preoperatively (n = 6, 60%) or postoperatively (n = 4, 40%). Five (50%) patients were alive without disease at last follow-up (median 34.2 months) and time from EPP to last FU was median 29.2 months (range 2.2–87.5). Two patients (20%) had local recurrence, 4.3 and 5.8 months from EPP, and both died from progressive disease, 13.1 and 8.2 months from EPP, respectively. One patient died from brain metastasis (17 months), one died from radiation associated osteosarcoma (66 months), and one died from surgical complications (heart failure from constrictive pericarditis). EPP offers a feasible and life-prolonging surgical consideration for patients with locally advanced sarcoma involving the pleura in combination with chemotherapy and radiation. Consequently, EPP should be considered during multi-disciplinary tumor board discussions at high-volume centers.

Surgical Management of Pediatric Inguinal Hernia: A Systematic Review and Guideline from the European Pediatric Surgeons' Association Evidence and Guideline Committee

INTRODUCTION

 Inguinal hernia repair represents the most common operation in childhood; however, consensus about the optimal management is lacking. Hence, recommendations for clinical practice are needed. This study assesses the available evidence and compiles recommendations on pediatric inguinal hernia.

MATERIALS AND METHODS

 The European Pediatric Surgeons' Association Evidence and Guideline Committee addressed six questions on pediatric inguinal hernia repair with the following topics: (1) open versus laparoscopic repair, (2) extraperitoneal versus transperitoneal repair, (3) contralateral exploration, (4) surgical timing, (5) anesthesia technique in preterm infants, and (6) operation urgency in girls with irreducible ovarian hernia. Systematic literature searches were performed using PubMed, MEDLINE, Embase (Ovid), and The Cochrane Library. Reviews and meta-analyses were conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) statement.

RESULTS

 Seventy-two out of 5,173 articles were included, 27 in the meta-analyses. Laparoscopic repair shortens bilateral operation time compared with open repair. In preterm infants, hernia repair after neonatal intensive care unit (NICU)/hospital discharge is associated with less respiratory difficulties and recurrences, regional anesthesia is associated with a decrease of postoperative apnea and pain. The review regarding operation urgency for irreducible ovarian hernia gained insufficient evidence of low quality.

CONCLUSION

 Laparoscopic repair may be beneficial for children with bilateral hernia and preterm infants may benefit using regional anesthesia and postponing surgery. However, no definite superiority was found and available evidence was of moderate-to-low quality. Evidence for other topics was less conclusive. For the optimal management of inguinal hernia repair, a tailored approach is recommended taking into account the local facilities, resources, and expertise of the medical team involved.

P399 SVILUPPO DI SINDROME DA IMMUNODEFICIENZA ACQUISITA DOPO SOMMINISTRAZIONE DI VASCCINO ANTI–SARAS–COV2

Il SARS–CoV2 è trasmesso tra gli umani attraverso particelle respiratorie e l’infezione può determinare un largo spettro di manifestazioni cliniche. Precedenti studi hanno dimostrato il ruolo centrale dell’immunità cellulo–mediata nel limitare la gravità delle infezioni da virus respiratori. I linfociti T–helper CD4+ sono coinvolti in funzioni di coordinazione e regolazione dell’immunità anti–virale: determinano lo sviluppo di anticorpi neutralizzanti ad alta affinità e la differenziazione dei centri germinali a cellule B in cellule della memoria secernenti anticorpi con lunga vita. Nessun dubbio sul ruolo cruciale della risposta a cellule T durante l’infezione da SARS–CoV2 o dopo la vaccinazione. Descriviamo il caso di un paziente di 39 anni, vaccinato con ChAdOx1–S. Dopo due settimane il paziente accusava dispnea e febbricola. Il test molecolare per SARS–CoV2 era negativo; agli esami ematici la PCR era aumentata. La TC del torace escludeva embolia polmonare e rivelava pattern a vetro smerigliato bilaterale, come da flogisi. All‘ecocardiogramma i parametri erano nella norma. L’ECG mostrava tachicardia sinusale. Il paziente veniva dimesso dal PS con terapia cortisonica. Una settimana dopo i sintomi peggiooravano. Una nuova TC torace mostrava difetti di opacizzazione di rami secondari dell’arteria polmonare ed aspetto bilaterale a vetro smerigliato. Si iniziava terapia con EBPM ed antibiotici a largo spettro. Il test molecolare e la sierologia per SARS–CoV2 erano negativi. Negativi i test per Mycoplasma, Chlamydia, Legionella e CMV DNA. L’emocromo mostrava ridotti linfociti (6,8%) con neutrofilia relativa (90,4%), ma normale valore dei bianchi. La TC–HR mostrava aspetto “crazy paving” bilaterale suggestivo per infezione virale o micotica (pattern come da infezione da Pneumocystis Jiroveci). Il test per HIV aveva esito positivo; alla tipizzazione linfocitaria ridotti i livelli di linfociti T–Helper (CD3+/CD4+) e rapporto CD3+/CD4+ 0%. Per il rapido deterioramento del quadro clinico il paziente veniva trasferito in terapia intensiva. Dopo 30 giorni dalla diagnosi di AIDS il paziente giungeva ad exitus. Il ruolo dei linfociti T nello sviluppo di anticorpi neutralizzanti e di cellule della memoria durante l’infezione da SARS–CoV2 è la chiave nella strategia di vaccinazione per ridurre il dilagare della pandemia, tuttavia nel nostro paziente questo meccanismo non ha funzionato rivelando il deficit del suo sistema immunitario da una latente infezione da HIV.

P335 AORTIC VALVE INFECTIVE ENDOCARDITIS COMPLICATED BY SUPERIOR MESENTERIC ARTERY ACUTE TROMBOSIS

The infective endocarditis (IE) has a significant impact on mortality rate in the first year after diagnosis, despite the improvements in early diagnosis and therapy. Embolic complications cause worsening of patient’s prognosis and they occur in the 20–50% of cases, with a risk of new embolic events after the initiation of antibiotic therapy rated between 6 and 12%. Echocardiographic characterization of vegetation has an important role in the definition of the embolization risk, it is documented that vegetation with dimension more than 10 mm are at higher risk. Several characteristic of the patient (diabetes, previous embolization, atrial fibrillation) determine the increase of the embolization risk, as well as the initiation of antibiotic therapy. We describe the case of a 64 y.o. man with chronic coronary syndrome (previous PCI) and previous Bentall–De Bono intervention for ascending aorta aneurysm. Patient was under anticoagulant therapy with DOAC due to atrial fibrillation. He was admitted to the emergency department for intermittent fever during the last three months, dyspnea and fatigue. Blood test showed neutrophilic leukocytosis and increased value of inflammatory markers. Transthoracic echography revealed an hyperechoic image on the ventricular side of the aortic prosthesis. The diagnosis of infective endocarditis was confirmed with transesophageal echocardiography, and empiric antibiotic therapy was initiated. Cardiac surgeon suggested follow up and new evaluation after three weeks of therapy. Clinical course was complicated by acute abdomen. The CT exam revealed dilation of a distal tract of superior mesenteric artery (maximum axial diameter was 10 mm) associated with distal thrombosis extended for 6 mm. The transthoracic echocardiogram showed absence of the vegetation on aortic prosthesis previous documented. Therapy with intravenous infusion of unfractionated heparin was administrated for three weeks, but the control TC showed persistence of the thrombotic occlusion of superior mesenteric artery so the case was discussed with Vascular Surgery team. They decided to treat patient with embolization and aneurysmectomy surgery (cultures were negative). This clinical case demonstrates that embolic complication of infective endocarditis, even on proper antbiotic therapy and close monitorization, are unpredictable and can cause the worsening of patient’s clinical course.

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.

Structure-Function Relationships of Human Milk Oligosaccharides on the Intestinal Epithelial Transcriptome in Caco-2 Cells and a Murine Model of Necrotizing Enterocolitis

SCOPE

Necrotizing enterocolitis (NEC) is a devastating gastrointestinal emergency affecting preterm infants. Breastmilk protects against NEC, partly due to human milk oligosaccharides (HMOs). HMO compositions are highly diverse, and it is unclear if anti-NEC properties are specific to carbohydrate motifs. Here, this study compares intestinal epithelial transcriptomes of five synthetic HMOs (sHMOs) and examines structure-function relationships of HMOs on intestinal signaling.

METHODS AND RESULTS

This study interrogates the transcriptome of Caco-2Bbe1 cells in response to five synthetic HMOs (sHMOs) using RNA sequencing: 2'-fucosyllactose (2'-FL), 3-fucosyllactose (3FL), 6'-siallyllactose (6'-SL), lacto-N-tetraose (LNT), lacto-N-neotetraose (LNnT). Protection against intestinal barrier dysfunction and inflammation occurred in an HMO-dependent manner. Each sHMO exerts a unique set of host transcriptome changes and modulated unique signaling pathways. There is clustering between HMOs bearing similar side chains, with little overlap in gene regulation which is shared by all sHMOs. Interestingly, most sHMOs protect pups against NEC, exerting divergent mechanisms on intestinal cell morphology and inflammation.

CONCLUSIONS

These results demonstrate that while structurally distinct HMOs impact intestinal physiology, their mechanisms of action differ. This finding establishes the first structure-function relationship of HMOs in the context of intestinal cell signaling responses and offers a functional framework by which to screen and design HMO-like compounds.

Treatment of necrotizing enterocolitis by conditioned medium derived from human amniotic fluid stem cells

Purpose

Necrotizing enterocolitis (NEC) is one of the most distressing gastrointestinal emergencies affecting neonates. Amniotic fluid stem cells (AFSC) improve intestinal injury and survival in experimental NEC but are difficult to administer. In this study, we evaluated whether conditioned medium (CM) derived from human AFSC have protective effects.

Methods

Three groups of C57BL/6 mice were studied: (i) breast-fed mice as control; (ii) experimental NEC mice receiving PBS; and (iii) experimental NEC mice receiving CM. NEC was induced between post-natal days P5 through P9 via: (A) gavage feeding of hyperosmolar formula four-time a day; (B) 10 minutes hypoxia prior to feeds; and (C) lipopolysaccharide administration on P6 and P7. Intra-peritoneal injections of either PBS or CM were given on P6 and P7. All mice were sacrificed on P9 and terminal ileum were harvested for analyses.

Results

CM treatment increased survival and reduced intestinal damage, decreased mucosal inflammation (IL-6; TNF-α), neutrophil infiltration (MPO), and apoptosis (CC3), and also restored angiogenesis (VEGF) in the ileum. Additionally, CM treated mice had increased levels of epithelial proliferation (Ki67) and stem cell activity (Olfm4; Lgr5) compared to NEC+PBS mice, showing restored intestinal regeneration and recovery during NEC induction. CM proteomic analysis of CM content identified peptides that regulated immune and stem cell activity.

Conclusions

CM derived from human AFSC administered in experimental NEC exhibited various benefits including reduced intestinal injury and inflammation, increased enterocyte proliferation, and restored intestinal stem cell activity. This study provides the scientific basis for the use of CM derived from AFSC in neonates with NEC.

Meso-Rex bypass versus portosystemic shunt for the management of extrahepatic portal vein obstruction in children: systematic review and meta-analysis

PURPOSE

Extrahepatic portal vein obstruction (EHPVO) is a major cause of non-cirrhotic portal hypertension in children. Surgical procedures for EHPVO include portosystemic shunts (PSS) and meso-Rex bypass (MRB). We conducted a systematic review and meta-analysis to compare the effectiveness of MRB versus PSS in EHPVO patients.

METHODS

A systematic literature search was performed using four databases. Articles reporting EHPVO and comparing patients who received MRB and PSS were included in the analysis.

RESULTS

We retrieved 851 papers, of which five observational studies met the inclusion criteria. There was no difference in shunt complications, mortality, or gastrointestinal bleeding after surgery between MRB and PSS in the meta-analysis. MRB had increased shunt complications compared with PSS in the non-comparative studies. MRB had a potential advantage over PSS in long-term prognosis in one comparative study. Overall, the quality of the evidence was low.

CONCLUSIONS

Based on available data, our meta-analysis indicates that MRB does not increase shunt complications, mortality, or gastrointestinal bleeding after surgery. The present study did not reveal superiority for either MRB or PSS. The paucity of well conducted trials in this area justifies future multicenter studies and studies that examine long-term outcomes.

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.

Surgical site infection after open and laparoscopic surgery in children: a systematic review and meta-analysis

Surgical site infections (SSIs) are the most common healthcare-associated infections in patients undergoing surgery. Various randomised control trials (RCTs) indicate that laparoscopic procedures can be associated with better outcomes compared to open procedures. However, how open versus laparoscopic approaches compare across various paediatric procedures with respect to SSI rate remains poorly defined. In this review, we examined RCTs that directly compare SSI rates after open versus laparoscopic operations for appendicitis, gastro-esophageal reflux, inguinal hernia, and pyloric stenosis. MEDLINE, Embase, and Web of Science were searched for RCTs comparing four types of open versus laparoscopic operations in children. The operations included appendectomy, fundoplication for gastro-esophageal reflux, inguinal hernia repair, or pyloromyotomy. 364 records were identified and screened, 54 full-text articles were assessed for eligibility, and 17 RCTs were included in the analysis. SSI rate was the primary outcome. Operative time and length of stay (LOS) were the secondary outcomes. A meta-analysis was conducted using RevMan 5.4 software. Laparoscopic appendectomy had a lower SSI rate than open appendectomy (odds ratio of 2.22 [1.19, 4.15] p = 0.01). Laparoscopic fundoplication for gastro-esophageal reflux, inguinal hernia repair, or pyloromyotomy for pyloric stenosis were not associated with lower SSI rate compared to open surgery. Operative time was shorter in open fundoplication (- 71.22 min [- 89.79,  - 52.65] p < 0.00001) than laparoscopic fundoplication. There was no significant difference in operative time of any of the other procedures. There was no significant difference in LOS between open and laparoscopic procedures for all types of operations analysed. Based on the findings of this review, it is recommended to utilise the laparoscopic approach over the open approach to reduce SSI risk in paediatric appendectomy.

Intestinal epithelial tight junctions and permeability can be rescued through the regulation of endoplasmic reticulum stress by amniotic fluid stem cells during necrotizing enterocolitis

Necrotizing enterocolitis (NEC) is one of the most severe gastrointestinal diseases affecting premature infants. It has been shown that NEC is associated with disrupted intestinal barrier and dysregulated endoplasmic reticulum (ER)-stress response. It has also been shown that stem cells derived from amniotic fluid (AFSC) rescued intestinal injury in experimental NEC. Herein, we hypothesized that the beneficial effects of AFSC in the injured intestine are due to the restoration of intestinal barrier function. We evaluated intestinal barrier function using an ex vivo intestinal organoid model of NEC. We found that AFSC restored the expression and localization of tight junction proteins in intestinal organoids, and subsequently decreased epithelial permeability. AFSC rescued tight junction expression by inducing a protective ER stress response that prevents epithelial cell apoptosis in injured intestinal organoids. Finally, we validated these results in our experimental mouse model of NEC and confirmed that AFSC induced sustained ER stress and prevented intestinal apoptosis. This response led to the restoration of tight junction expression and localization, which subsequently reduced intestinal permeability in NEC pups. These findings confirm that intestinal barrier function is disrupted during NEC intestinal injury, and further demonstrate the disruption can be reversed by the administration of AFSC through the activation of the ER stress pathway. This study provides insight into the pathogenesis of NEC and highlights potential therapeutic targets for the treatment of NEC.

Nitroxide spin labels and EPR spectroscopy: A powerful association for protein dynamics studies

Site-Directed Spin Labelling (SDSL) technique is based on the attachment of a paramagnetic label onto a specific position of a protein (or other bio-molecules) and the subsequent study by Electron Paramagnetic Resonance (EPR) spectroscopy. In particular, continuous-wave EPR (cw-EPR) spectra can detect the local conformational dynamics for proteins under various conditions. Moreover, pulse-EPR experiments on doubly spin-labelled proteins allow measuring distances between spin centres in the 1.5-8 nm range, providing information about structures and functions. This review focuses on SDSL-EPR spectroscopy as a structural biology tool to investigate proteins using nitroxide labels. The versatility of this spectroscopic approach for protein structural characterization has been demonstrated through the choice of recent studies. The main aim is to provide a general overview of the technique, particularly for non-experts, to spread the applicability of this technique in various fields of structural biology.

Live Intravital Intestine with Blood Flow Visualization in Neonatal Mice Using Two-photon Laser Scanning Microscopy

This protocol describes a novel technique to investigate the microcirculation dynamics underlying the pathology in the small intestine of neonatal mice using two-photon laser-scanning microscopy (TPLSM). Recent technological advances in multi-photon microscopy allow intravital analysis of different organs such as the liver, brain and intestine. Despite these advances, live visualization and analysis of the small intestine in neonatal rodents remain technically challenging. We herein provide a detailed description of a novel method to capture high resolution and stable images of the small intestine in neonatal mice as early as postnatal day 0. This imaging technique allows a comprehensive understanding of the development and blood flow dynamics in small intestine microcirculation.

A47 SYNTHETIC HUMAN MILK OLIGOSACCHARIDES PREVENT EXPERIMENTAL NECROTIZING ENTEROCOLITIS VIA DIVERGENT TRANSCRIPTOMIC RESPONSES

Background

Breastmilk reduces the risk of necrotizing enterocolitis (NEC) in preterm infants, but the bioactive components mediating this effect are not well understood. Human milk oligosaccharides (HMOs) reduce NEC both in humans and in relevant animal models. However, it is unclear if there are functional differences between individual oligosaccharides.

Aims

The objective of this study was to compare the intestinal transcriptome responses of individual HMOs using complementary in vitro and in vivo models of NEC.

Methods

RNA sequencing was performed on Caco-2Bbe1 gut epithelial cells after exposure to commercially-purified 2’-fucosyllactose (2’FL), 3-fucosyllactose, 6’-siallyllactose, lacto-N-tetraose (LNT) or lacto-N-neotetraose for 24hr at 37°C for 24 h (n=3). Signaling pathways were analyzed in murine- and human-derived NEC enteroids by qPCR. To validate these findings, five-day-old mouse pups were orally gavaged formula with or without individual HMOs, followed by NEC induction with hypoxia (5% O2, 95% N2) and lipopolysaccharide (4 mg/kg/day). Coded ileal sections (n=6–7/group) were analyzed for mucosal injury by histology, immune fluorescence, immunohistochemistry, and gene expression via qPCR.

Results

The HMO transcriptome clustered into divergent functional categories including metabolic process, protein processing and responses to external stimuli. Each synthetic HMO induced a unique transcriptome and exhibited varying effects on the intestinal epithelial functions and biological pathways. This was confirmed in the murine model of NEC, as both LNT and 2FL mitigated NEC injury with comparable recovery of intestinal cell proliferation (Ki67) and expression of stem cells (Lgr5+). Both qPCR and immunofluorescence staining showed differences between 2FL- and LNT-fed pups in host inflammatory and immune responses.

Conclusions

This study demonstrates that synthetic HMOs ameliorate intestinal injury in experimental NEC. However, the mechanisms by which individual oligosaccharides act on the intestine differ, suggesting that single synthetic HMOs may not fully recapitulate the benefits of pooled HMOs. Future studies will further delineate structure-function relationships of synthetic HMOs on host intestinal innate and adaptive immune responses.

Funding Agencies

CIHRFerring Canada Medical Student Research grant

Hepatic oxidative injury: role of mitochondrial dysfunction in necrotizing enterocolitis

PURPOSE

Necrotizing enterocolitis (NEC) is a severe neonatal gastrointestinal disease that can cause damage to remote organs. Previous studies have shown that inflammatory and oxidative injury occur in the liver during NEC. Mitochondrial DNA (mtDNA) plays an important role in hepatic injuries of many other diseases. We aimed to investigate the mechanism of mitochondrial dysfunction in hepatic oxidative injury during NEC.

METHODS

NEC was induced in C57BL/6 mice (approval: 44032) by hypoxia, gavage feeding with hyperosmolar formula, and lipopolysaccharide administration from postnatal days 5 to 9 (n = 15). Two additional groups with hypoxia only (n = 10) and hypoxia and hyperosmolar formula (n = 13) were also examined. Breastfed pups were used as control (n = 15). Liver was harvested on postnatal day 9. Gene expressions of mtDNA markers cytochrome c oxidase subunit 3 (COX3), cytochrome b (CYTB) and NADH-ubiquinone oxidoreductase chain 1 (ND1) were measured by real-time qPCR. Mitochondrial morphology marker HSP60 and oxidative stress marker NRF2 were detected by immunofluorescence staining and compared between NEC and control. Data were presented as mean ± SD and compared using Student's t test; p < 0.05 was considered significant.

RESULTS

Gene expression of mtDNA markers (COX3, CYTB, and ND1) were significantly decreased in the liver of NEC mice relative to control, hypoxia alone, and hypoxia with hyperosmolar formula. Immunofluorescence showed depletion of HSP60 indicating decreased mitochondria in NEC liver relative to control. Furthermore, a higher protein expression of NRF2 was observed indicating higher oxidative stress in NEC liver relative to control.

CONCLUSIONS

Intestinal injury in experimental NEC leads to a systemic inflammatory response affecting the liver. Hepatic oxidative injury in NEC is characterized by decreased mitochondria and mtDNA depletion. This study provides insight into the mechanism of liver injury in NEC.

Early enteral feeding after intestinal anastomosis in children: a systematic review and meta-analysis of randomized controlled trials

PURPOSE

Delayed enteral feeding (DEF) contributes to postoperative complications among children undergoing intestinal surgery. Various recent studies indicate the benefits of early enteral nutrition after intestinal surgery in adults. This systematic review and meta-analysis evaluates whether early enteral feeding (EEF) is beneficial in children who underwent intestinal anastomosis.

METHODS

MEDLINE, PubMed, the Cochrane Library, and Web of Science databases were searched for RCTs that addressed the effect of EEF in children (younger than 18 years old) undergoing intestinal anastomosis. EEF was defined as starting enteral feeding before the 3rd postoperative day. Studies were selected based on predetermined inclusion and exclusion criteria. A meta-analysis was performed using RevMan 5.3 to estimate odds ratios (ORs) or mean differences (MDs) with 95% confidence intervals (CIs).

RESULTS

Four RCT studies met the inclusion criteria, comprising 97 cases with EEF and 89 cases with DEF. Enteral feeding started significantly earlier in the EEF group compared to the DEF group (MD = - 2.80; 95% CI - 3.11 to - 2.49; p < 0.00001). Postoperative anastomotic leak rate was unchanged between EEF and DEF groups (OR = 0.86; 95% CI 0.17-4.46; p = 0.86). The EEF group had a shorter length of hospital stay (MD = - 3.38; 95% CI - 4.29 to - 2.48; p < 0.00001), earlier time to bowel movement return (MD = - 0.57; 95% CI - 0.79 to - 0.35; p < 0.00001), lower incidence of surgical infection (OR = 0.27; 95% CI 0.08-0.90; p = 0.03), and faster tolerance of full enteral feeding (MD = - 2.00; 95% CI - 3.01 to - 2.79; p < 0.00001). Incidence of fever (OR = 0.37; 95% CI 0.10-1.31; p = 0.12), emesis, and abdominal distention (OR = 0.63; 95% CI 0.13-3.16; p = 0.58) were not different between the two groups.

CONCLUSIONS

Early enteral feeding after intestinal anastomosis in children does not increase the risk of postoperative anastomotic leak, fever, emesis, and abdominal distention. However, early enteral feeding is beneficial as it promotes the return of bowel function, reduces the length of hospital stay and the incidence of surgical infection in comparison to delayed enteral feeding.

Doppler ultrasound assessment of splanchnic perfusion and heart rate for the detection of necrotizing enterocolitis

PURPOSE

Monitoring disease progression is crucial to improve the outcome of necrotizing enterocolitis (NEC). A previous study indicates that intestinal wall flow velocity was reduced in NEC pups from the initial stages of the disease. This study aims to investigate whether splanchnic perfusion via the superior mesenteric artery (SMA) (i) is altered during NEC development and (ii) can be used as a monitoring tool to assess disease progression.

METHODS

NEC was induced in C57BL/6 mice via gavage feeding of formula, hypoxia, and oral lipopolysaccharide, from postnatal day 5 (P5) to P9 (AUP: 32,238). Breastfed littermates served as controls. Doppler ultrasound (U/S) of bowel loops was performed daily. Intestinal wall perfusion was calculated as average flow velocity (mm/s) of multiple abdominal regions. Groups were compared using one-way ANOVA.

RESULTS

The SMA flow velocity was not altered during the initial stage of NEC development, but become significantly reduced at P8 when the intestinal disease was more advanced. These changes occurred concomitantly with an increase in heart rate.

CONCLUSIONS

NEC is associated with intestinal hypo-perfusion at the periphery and flow in the SMA is reduced during the later stages of disease indicating the presence of intestinal epithelium damage. This study contributes to understanding NEC pathophysiology and illustrates the value of Doppler U/S in monitoring disease progression.

Becoming an academic pediatric surgeon scientist in Canada

Pediatric surgeon scientists in Canada and broadly North America occupy a unique role balancing both clinical practice and surgical research. The path to becoming an academic pediatric surgeon scientist is one that is lengthy but highly rewarding. There are excellent opportunities for young surgeons to become academic pediatric surgeons represented by the Doctor of Medicine (MD) / Doctor of Philosophy (PhD) and the Surgeon Scientist Training Programs (SSTP). Meeting the demands for clinical practice often takes precedence over research training in healthcare, leading to a potential shortage of academic pediatric surgeons in Canada and North America. This shortage often leads to increased reliance on international research collaborations and imported talent to continue to advance the field. Protecting the research academic time is essential to a fruitful progression in academic pediatric surgery.

Human amniotic fluid stem cells attenuate cholangiocyte apoptosis in a bile duct injury model of liver ductal organoids

PURPOSE

Biliary atresia (BA) is a fibro-obliterative cholangiopathy that involves both extrahepatic and intrahepatic bile ducts in infants. Cholangiocyte apoptosis has an influence on the fibrogenesis process of bile ducts and the progression of liver fibrosis in BA. Human amniotic fluid stem cells (hAFSCs) are multipotent cells that have ability to inhibit cell apoptosis. We aimed to investigate whether hAFSCs have the potential to attenuate cholangiocyte apoptosis and injury induced fibrogenic response in our ex vivo bile duct injury model of liver ductal organoids.

METHODS

The anti-apoptotic effect of hAFSCs was tested in the acetaminophen-induced injury model of neonatal mouse liver ductal organoids (AUP #42681) by using direct and indirect co-culture systems. Cell apoptosis and proliferation were evaluated by immunofluorescent staining. Expression of fibrogenic cytokines was analyzed by RT-qPCR. Data were compared using one-way ANOVA with post hoc test.

RESULTS

In our injury model, liver ductal organoids that were treated with hAFSCs in both direct and indirect co-culture systems had a significantly smaller number of apoptotic cholangiocytes and decreased expression of fibrogenic cytokines, transforming growth factor beta-1 (TGF-β1) and platelet-derived growth factor-BB (PDGF-BB). Moreover, hAFSCs increased cholangiocyte proliferation in injured organoids.

CONCLUSION

hAFSCs have the ability to protect the organoids from injury by decreasing cholangiocyte apoptosis and promoting cholangiocyte proliferation. This protective ability of hAFSCs leads to inhibition of the fibrogenic response in the injured organoids. hAFSCs have high therapeutic potential to attenuate liver fibrogenesis in cholangiopathic diseases such as BA.

A novel model of injured liver ductal organoids to investigate cholangiocyte apoptosis with relevance to biliary atresia

PURPOSE

The fibrogenic process in cholangiopathic diseases such as biliary atresia (BA) involves bile duct injury and apoptosis of cholangiocytes, which leads to the progression of liver fibrosis into liver cirrhosis and can result in end-staged liver disease. Recent advances in the development of organoids or mini-organ structures have allowed us to create an ex vivo injury model of the bile duct that mimics bile duct injury in BA. The aim of this experimental study was to develop a novel model of injured intrahepatic cholangiocytes as this can be relevant to BA. Our new model is important for studying the pathophysiological response of bile ducts to injury and the role of cholangiocytes in initiating the fibrogenic cascade. In addition, it has the potential to be used as a tool for developing new treatment strategies for BA.

METHODS

Liver ductal organoids were generated from the liver of healthy neonatal mouse pups. Intrahepatic bile duct fragments were isolated and cultured in Matrigel dome. Injury was induced in the organoids by administration of acetaminophen in culture medium. The organoids were then evaluated for fibrogenic cytokines expression, cell apoptosis marker and cell proliferation marker.

RESULTS

Organoids generated from intrahepatic bile duct fragments organized themselves into single-layer epithelial spheroids with lumen on the inside mimicking in vivo bile ducts. After 24-h exposure to acetaminophen, cholangiocytes in the organoids responded to the injury by increasing expression of fibrogenic cytokines, transforming growth factor beta-1 (TGF-β1) and platelet-derived growth factor-BB (PDGF-BB). This fibrogenic response of injured organoids was associated with increased cholangiocyte apoptosis and decreased cholangiocyte proliferation.

CONCLUSION

To our knowledge this is the first description of cholangiocyte injury in the organoids derived from intrahepatic bile ducts. Our injury model demonstrated that cholangiocyte apoptosis and its fibrogenic response may play a role in initiation of the fibrogenic process in cholangiopathic diseases such as BA. These findings are important for the development of novel therapy to reduce cholangiocyte apoptosis and to halt the early fibrogenic cascade in liver fibrogenesis. This novel injury model can prove very valuable for future research in biliary atresia.

The effect of pre- and post-remote ischemic conditioning reduces the injury associated with intestinal ischemia/reperfusion

PURPOSE

Midgut volvulus is associated with intestinal ischemia/reperfusion (IR) injury and can progress to severe intestinal damage. Remote ischemic conditioning (RIC) reduces IR-induced injury in distant organs. The aim of this study was to investigate whether RIC protects the intestine from IR injury.

METHODS

We investigated intestinal IR injury in 3 weeks old SD rats. Animals underwent: (i) sham laparotomy, (ii) intestinal IR injury, (iii) intestinal IR + RIC during ischemia, or (iv) intestinal IR + RIC after reperfusion. Intestinal IR injury was achieved by 45 min occlusion of superior mesenteric artery followed by de-occlusion. RIC was administered via four cycles of 5 min of hind limb ischemia followed by 5 min reperfusion. Animals were sacrificed 24 h after surgery and the ileum was harvested for evaluation.

RESULTS

Intestinal injury was present after IR. However, this injury was reduced in both IR + RIC groups. Expression of inflammatory cytokine IL6 was lower in IR + RIC groups compared to IR alone. Carbonyl protein was also significantly lower in IR + RIC compared to IR, indicating lower oxidative stress in both IR + RIC groups.

CONCLUSION

Remote ischemic conditioning attenuated intestinal injury, inflammation, and oxidative stress in experimental intestinal ischemia/reperfusion injury. Remote ischemic conditioning may be useful in children with midgut volvulus to reduce the intestinal injury.

LEVEL OF EVIDENCE

Experimental study.

TYPE OF STUDY

Animal experiment.

Multiparametric MR imaging of the prostate at 1.5-T without endorectal coil using an 8 channel pelvic phased array: Is it still a viable option?

INTRODUCTION

The purpose of our work was to evaluate the feasibility of prostate multiparametric MR imaging at 1.5-T without endorectal coil using an 8 channel pelvic phased array coil.

MATERIAL AND METHODS

A total of 154 patients who underwent mp-MRI were retrospectively included. Patients received a standardized mp-MRI, compliant with 2012 European Society of Uro-Radiology guidelines, with 1·5 T magnetic field strength and an 8 channel pelvic phased-array coil. Two blinded readers graded the image quality of mp-MRI on a three-point scale and they scored the prostate lesions according to PI-RADS v2. All PI-RADS of 4 or 5 underwent biopsy. A third radiologist and a pathologist verified the correspondence between the MRI images and the results of the biopsy.

RESULTS

64 (41.6%) patients showed a Pi-rads of 4 or 5. At biopsy, 79.7% showed a Gleason score ≥7, 12.5% showed a Gleason score of 6 and 7.8% showed a negative biopsy. In the group of Pi-rads ≤ 3, 12 patients underwent a biopsy with the following results: negative biopsy in 33.3%, atypical Small Acinar Proliferation in 16.7%, prostatic intraepithelial neoplasia in 25% and indolent PCa 25%. Mp-MRI in the identification of clinically significant cancer provided a low percentage of false positive (7.8%) while in 79.7% of cases it was capable to detect clinically significant prostate cancer. In 92.2% of patients mp-MRI identified a prostate cancer with a Gleason score ≥6. The inter-reader agreement was excellent in defining both the quality of the examination and the PI-RADS category (k = 0.83 and k = 0.70, respectively).

CONCLUSIONS

mp-MRI at 1.5-T without endorectal coil using an 8 channel phased array is an appropriate tool for early detection of clinically significant prostate cancer.

IMPLICATIONS FOR PRACTICE

8 channel pelvic phased array is still an appropriate tool for early detection of clinically significant prostate cancer and for obtaining a reduction in overdiagnosis of indolent PCa.