Remote ischemic conditioning counteracts the intestinal damage of necrotizing enterocolitis by improving intestinal microcirculation

Elucidating novel mechanism of action of spiperone for drug repurposing to prevent and treat murine colitis and sepsis

AIMS

While Ca2+ signaling plays a vital role in maintaining normal endothelial function and vascular activity, aberrant Ca2+ signaling in endothelial dysfunction is involved in the pathogenesis of inflammation. As a safe anti-psychotic drug to mobilize Ca2+ signaling, we repurposed spiperone as a potential drug for two intestinal epithelial injury related diseases, colitis and sepsis.

MATERIALS AND METHODS

Spiperone-induced vasorelaxation of human submucosal arterioles and mesenteric arterioles from wide-type and TRPV4 KO mice was determined by Mulvany-style wire myograph. The action of spiperone in HUVEC was tested by Ca2+ imaging and patch clamp, and its action on murine mesenteric arterioles was measured in vivo. LPS- and CLP-induced septic mice and DSS-induced colitic mice were used to examine the anti-inflammatory effects of spiperone.

KEY FINDINGS

Spiperone induced endothelium-dependent hyperpolarization (EDH)-mediated vasorelaxation of healthy arterioles with EC50 of ∼50 nM predominately via PLC/IP3/IP3R pathway to induce endoplasmic reticulum (ER) Ca2+ release and further to promote Ca2+ entry via TRPV4-constituted SOCE. In both LPS- and CLP-induced septic mice, spiperone effectively prevented and treated sepsis by reducing serum proinflammatory factors, alleviating multiple organ dysfunction, rescuing the impaired EDH-mediated vasorelaxation and improving murine survival rate. Similarly, spiperone could also protect against murine colitis.

SIGNIFICANCE

We reveal new action mode and mechanism of spiperone to induce EDH-mediated vasorelaxation of both human and murine arterioles to protect against colitis and sepsis by innovatively inducing PLC/IP3R/Ca2+ signaling rather than canonically antagonizing GPCR. Spiperone could be repurposed as a potential new drug for the prevention/treatment of colitis and sepsis.

Characteristics, progression, management, and outcomes of NEC: a retrospective cohort study

BACKGROUND

Necrotising enterocolitis (NEC) in preterm infants is associated with high morbidity and mortality. In most neonates, it is a progressive disease from medical NEC (mNEC) to surgical NEC (sNEC); however, in some, it presents as sNEC from onset.

OBJECTIVE

To evaluate the rate, the timing of progression, different surgical approaches, and outcomes of mNEC and sNEC in preterm neonates.

DESIGN

A retrospective cohort study of preterm infants with diagnosis of NEC between 2010 and 2020 was conducted. Data on clinical presentation, NEC progression, treatment received, different surgical approaches, resource utilization, and outcomes were abstracted. Infants were classified into 3 groups: mNEC, mNEC that progressed to sNEC, and sNEC at presentation.

RESULTS

Among 208 included infants with NEC, 109 (52%) were mNEC, 66 (32%) progressed from mNEC to sNEC, and 33 (16%) presented with sNEC. Gestational age, birth weight, and postnatal age at NEC were inversely associated with the development of sNEC. mNEC progressed to sNEC occurred after a median of 2.5 (IQR 1-4.25) days. Ninety (91%) of sNEC patients underwent interventions: peritoneal drain only in 19 (21%), laparotomy in 59 (66%), or both in 12 (13%). In comparison with mNEC, those with sNEC infants had longer duration on antibiotics, inotropes, respiratory support, length of stay, and time to reaching full enteral feeds; and were more likely to have recurrent NEC episodes, BPD, and mortality.

CONCLUSION

There is a high burden of illness for sNEC cases. Insight into the expected clinical course of sNEC patients can facilitate anticipatory management and provide a window of opportunity for timely interventions that may ameliorate the course of sNEC.

Metabolic disruption exacerbates intestinal damage during sleep deprivation by abolishing HIF1α-mediated repair

Sleep deprivation (SD) has been reported to induce intestinal damage by several mechanisms, yet its role in modulating epithelial repair remains unclear. In this study, we find that chronic SD leads to colonic damage through continuous hypoxia. However, HIF1α, which generally responds to hypoxia to modulate barrier integrity, was paradoxically dysregulated in the colon. Further investigation revealed that a metabolic disruption during SD causes accumulation of α-ketoglutarate in the colon. The excessive α-ketoglutarate degrades HIF1α protein through PHD2 (prolyl hydroxylase 2) to abolish the intestinal repair functions of HIF1α. Collectively, these findings provide insights into how SD can exacerbate intestinal damage by fine-tuning metabolism to abolish HIF1α-mediated repair.

Acute remote ischemic conditioning enhances (CD3+)- but not (FoxP3+)-T-cell invasion in the tumor center and increases IL 17 and TNF-alpha expression in a murine melanoma model

Introduction

Hypoxia can drive tumor progression, suppress anti-tumor immunity, and reduce the effectiveness of radiotherapy and chemotherapy. This study aimed to assess the impact of remote ischemic conditioning (RIC) on tumor oxygenation (sO2) and the anti-tumor immune response.

Material and methods

Fourteen B16-Ova tumor-bearing C57BL/6N mice received six 5-minute RIC cycles, while another fourteen underwent anesthesia only. Pimonidazole was administered 1.5 hours before sacrifice. Blood flow, sO2, and hemoglobin levels were measured in the non-ischemic hind limb and tumor. Tumor hypoxia was assessed using pimonidazole and CA IX immunohistochemistry, and T cell infiltration by CD3 and FoxP3 staining. Serum levels of 23 cytokines were analyzed using a multiplex immunoassay.

Results

Isoflurane anesthesia caused a slight intraindividual increase in blood flow (p = 0.07) and sO2 (p = 0.06) of the hind limb and a sole increase in tumor sO2 (p = 0.035), whereas RIC improved sO2 of the tumor in relation to the hind limb (p=0.03). The median of the tumor oxygen saturation reached 51.4% in the control group and 62.7% in the RIC group (p = 0.09), exhibiting a slight tendency towards better oxygenation in the RIC group. Pimonidazole (p=0.24) and CA IX hypoxia score (p=0.48) did not reveal statistically significant differences between the two groups. In RIC-treated tumors, the number of CD3 (p=0.006), but not FoxP3- positive cells (p = 0.84), in the tumor core was significantly higher compared to the control group. In the RIC group, the mean fluorescence intensity (MFI) of IL-17 was significantly higher (p=0.035), and TNF-α was trend-wise higher (p=0.063) compared to the control group.

Conclusion

Both isoflurane anesthesia and RIC have an impact on microcirculation. The application of RIC counteracted some of the effects of isoflurane, primarily in healthy tissue, and led to a significant improvement in relative tumor tissue oxygenation compared to the non-ischemic hind limb. RIC selectively enhanced immune infiltration within the tumor center, probably by previously activated tumor infiltrating T cells, while having no significant impact on T-regulatory cells. RIC appears to impact the cytokine profile, as indicated by elevated MFIs of TNF-α and IL-17.

GYY4137, as a slow-releasing H2S donor, ameliorates sodium deoxycholate-induced chronic intestinal barrier injury and gut microbiota dysbiosis

Introduction

Numerous studies have revealed that a long-term high-fat diet can raise intestinal deoxycholate acid concentration, which can harm intestinal mucosal barrier function in several ways. This study aims to verify the protective effect of GYY4137, as a slow-releasing H2S donor, on microbiome disturbance and the chronic injury of the intestinal mucosal barrier function caused by sodium deoxycholate.

Methods

Caco-2 monolayer and mouse models were treated with a relatively high concentration of sodium deoxycholate (1.0 mM and 0.2%, respectively) for longer periods (32 h and 12 weeks, respectively) to understand the effects of GYY4137 on sodium deoxycholate-induced chronic intestinal barrier dysfunction and its fundamental mechanisms.

Results

A relatively long period of sodium deoxycholate treatment can remarkably increase the intestinal barrier permeability, alter the distribution and expression of tight junction proteins and generate the production of pro-inflammatory cytokines (TNF-α and IL-1β) in the Caco-2 monolayers and mouse models. Moreover, it can activate the MLCK-P-MLC2 pathway in the Caco-2 monolayers, which was further confirmed using RNA sequencing. The body weight, intestinal barrier histological score, and TUNEL index of sodium deoxycholate-treated mice worsened. In addition, an induced microbiome imbalance was observed in these mice. The above variations can be reversed with the administration of GYY4137.

Conclusion

This study demonstrates that GYY4137 ameliorates sodium deoxycholate-induced chronic intestinal barrier injury by restricting the MLCK-P-MLC2 pathway while elevating the expression level of tight junction proteins, anti-apoptosis and maintaining the microbiome's homeostasis.

Remote limb ischemic preconditioning alleviated spinal cord injury through inhibiting proinflammatory immune response and promoting the survival of spinal neurons

STUDY DESIGN

Experimental animal study.

OBJECTIVES

To investigate the protective effect of remote limb ischemia preconditioning (RLPreC) on traumatic spinal cord injury (SCI) and explore the underlying biological mechanisms using RNA sequencing.

SETTING

China Rehabilitation Science Institute; Beijing; China.

METHODS

spinal cord injury was induced in mice using a force of 0.7 N. RLPreC treatment was administered. Motor function, pain behavior, and gene expression were assessed.

RESULTS

RLPreC treatment significantly improved motor function and reduced pain-like behavior in SCI mice. RNA-Seq analysis identified 5247 differentially expressed genes (DEGs). GO analysis revealed enrichment of immune response, inflammatory signaling, and synaptic transmission pathways among these DEGs. KEGG analysis indicated suppression of inflammation and promotion of synapse-related pathways.

CONCLUSIONS

RLPreC is a promising therapeutic strategy for improving motor function and alleviating pain after traumatic SCI. RNA-Seq analysis provides insights into potential therapeutic targets and warrants further investigation.

Remote Ischemic Conditioning (RIC) Decreases the Incidence and Severity of Necrotizing Enterocolitis (NEC) - Validation in a Large Animal Model

BACKGROUND

Necrotizing enterocolitis (NEC) remains a devastating intestinal disease that affects 5-7% of preterm neonates. Remote ischemic conditioning (RIC) has been shown to protect against intestinal ischemia in rodents. We aimed to determine the efficacy of RIC in a large animal model of NEC.

METHODS

Using an established piglet model of NEC, preterm piglets of 103-107 days gestation (term = 115 days) were randomly assigned to receive RIC or serve as untreated controls. RIC was initiated at 24 h of life and consisted of 4 cycles of 4-min occlusion followed by reperfusion; cycles were repeated every 24 or 12 h for low frequency (LF) and high frequency (HF) groups, respectively. Piglets were monitored clinically for NEC which was confirmed postmortem using established anatomic and histologic scoring.

RESULTS

Eighty-six piglets were randomized into controls (N = 38), LF-RIC (n = 26) and HF-RIC (n = 22) groups. In contrast to the rodent models, in piglets LF-RIC (every 24 h) did not decrease the incidence of NEC compared to controls. However, HF-RIC (every 12 h) significantly reduced the incidence of NEC (OR = 0.13; 95% CI: 0.03, 0.55; p = 0.02) and resulted in a lower severity of NEC (p < 0.0001) compared to controls.

CONCLUSIONS

RIC offers protection against NEC in the piglet model only when administered more frequently than in rodents. Further studies are needed to define the optimum frequency of RIC for piglets that may translate to clinical use.

Strain- and sex-specific differences in intestinal microhemodynamics and gut microbiota composition

Background

Intestinal microcirculation is a critical interface for nutrient exchange and energy transfer, and is essential for maintaining physiological integrity. Our study aimed to elucidate the relationships among intestinal microhemodynamics, genetic background, sex, and microbial composition.

Methods

To dissect the microhemodynamic landscape of the BALB/c, C57BL/6J, and KM mouse strains, laser Doppler flowmetry paired with wavelet transform analysis was utilized to determine the amplitude of characteristic oscillatory patterns. Microbial consortia were profiled using 16S rRNA gene sequencing. To augment our investigation, a broad-spectrum antibiotic regimen was administered to these strains to evaluate the impact of gut microbiota depletion on intestinal microhemodynamics. Immunohistochemical analyses were used to quantify platelet endothelial cell adhesion molecule-1 (PECAM-1), estrogen receptor α (ESR1), and estrogen receptor β (ESR2) expression.

Results

Our findings revealed strain-dependent and sex-related disparities in microhemodynamic profiles and characteristic oscillatory behaviors. Significant differences in the gut microbiota contingent upon sex and genetic lineage were observed, with correlational analyses indicating an influence of the microbiota on microhemodynamic parameters. Following antibiotic treatment, distinct changes in blood perfusion levels and velocities were observed, including a reduction in female C57BL/6J mice and a general decrease in perfusion velocity. Enhanced erythrocyte aggregation and modulated endothelial function post-antibiotic treatment indicated that a systemic response to microbiota depletion impacted cardiac amplitude. Immunohistochemical data revealed strain-specific and sex-specific PECAM-1 and ESR1 expression patterns that aligned with observed intestinal microhemodynamic changes.

Conclusions

This study highlights the influence of both genetic and sex-specific factors on intestinal microhemodynamics and the gut microbiota in mice. These findings also emphasize a substantial correlation between intestinal microhemodynamics and the compositional dynamics of the gut bacterial community.

Prevention Strategies and Management of Necrotizing Enterocolitis

Necrotizing enterocolitis (NEC) is a serious intestinal disease which primarily affects preterm infants. The pathogenesis of NEC is multifactorial. Thus, it is complicated to study, prevent, and manage.

Purpose of Review

The purpose of this review is to provide a comprehensive summary of recent research and provide recommendations for the prevention and management of NEC. Currently, management is supportive and non-specific and long-term outcomes for surgical NEC are poor.

Recent Findings

The most important strategy to prevent NEC is to provide preterm infants with a human milk diet, minimize exposure to antibiotics and avoid medications that disturb the intestinal microbiome.

Summary

Strategies to optimize the infant's intestinal microbiome are critical, as disturbances in the intestinal microbiome composition are a major factor in the pathogenesis of this disease. Optimizing maternal health is also vital to prevent prematurity and neonatal morbidity. Ongoing research holds promise for the implementation of new diagnostic modalities, preventive strategies, and medical treatment options to improve outcomes for premature infants.

Attenuation of esophageal anastomotic stricture through remote ischemic conditioning in a rat model

Anastomotic stricture is a typical complication of esophageal atresia surgery. Remote ischemic conditioning (RIC) has demonstrated multiorgan benefits, however, its efficacy in the esophagus remains unclear. This study aimed to investigate whether applying RIC after esophageal resection and anastomosis in rats could attenuate esophageal stricture and improve inflammation. Sixty-five male Sprague-Dawley rats were categorized into the following groups: controls with no surgery, resection and anastomosis only, resection and anastomosis with RIC once, and resection and anastomosis with RIC twice. RIC included three cycles of hind-limb ischemia followed by reperfusion. Inflammatory markers associated with the interleukin 6/Janus kinase/ signal transducer and activator of transcription 3 (IL-6/JAK/STAT3) and tumor necrosis factor-alpha/nuclear factor-κB (TNF-α/NF-kB) signaling pathways were evaluated with RNA and protein works. The RIC groups showed significantly lower stricture rates, lower inflammatory markers levels than the resection and anastomosis-only group. The RIC groups had significantly lower IL-6 and TNFa levels than the resection and anastomosis-only group, confirming the inhibitory role of remote ischemic conditioning in the IL-6/JAK/STAT3 and TNF-α/NF-kB signaling pathways. RIC after esophageal resection and anastomosis can reduce the inflammatory response, improving strictures at the esophageal anastomosis site, to be a novel noninvasive intervention for reducing esophageal anastomotic strictures.

Parthanatos initiated by ROS-induced DNA damage is involved in intestinal epithelial injury during necrotizing enterocolitis

Necrotizing enterocolitis (NEC) involves intestinal epithelial damage and inflammatory response and is associated with high morbidity and mortality in infants. To improve therapeutic prospects, elucidating underlying molecular mechanisms of intestinal epithelial damage during NEC is of the essence. Poly (ADP-ribose) polymerase 1 (PARP1)-dependent parthanatos is a programmed inflammatory cell death. In the present study, the presence of parthanatos-associated proteins PARP1 and poly (ADP-ribose) (PAR), along with high expression of DNA damage-associated biomarkers, 8-hydroxy-2'-deoxyguanosine (8-OHdG) and phosphorylation of histone H2AX (γH2AX), were discovered in the intestinal tissues of NEC infants. Additionally, the upregulated expression of PARP1 and PAR in NEC intestinal tissues correlated distinctly with clinical indices indicative of NEC incidence and severity. Furthermore, we demonstrated that inhibiting the expression of parthanatos-associated proteins, by either pharmacological blockage using 3-aminobenzamide (3-AB), an inhibitor of PARP1, or genetic knockout using Parp1-deficient mice, resulted in substantial improvements in both histopathological severity scores associated with intestinal injury and inflammatory reactions. Moreover, in an in vitro NEC model, reactive oxygen species (ROS)-induced DNA damage promoted the formation of PAR and nuclear translocation of apoptosis-inducing factor (AIF), thus activating PARP1-dependent parthanatos in Caco-2 cells and human intestinal organoids. Our work verifies a previously unexplored role for parthanatos in intestinal epithelial damage during NEC and suggests that inhibition of parthanatos may serve as a potential therapeutic strategy for intervention of NEC.

Effects of remote ischemic preconditioning on early markers of intestinal injury in experimental hemorrhage in rats

The maintenance of intestinal integrity and barrier function under conditions of restricted oxygen availability is crucial to avoid bacterial translocation and local inflammation. Both lead to secondary diseases after hemorrhagic shock and might increase morbidity and mortality after surviving the initial event. Monitoring of the intestinal integrity especially in the early course of critical illness remains challenging. Since microcirculation and mitochondrial respiration are main components of the terminal stretch of tissue oxygenation, the evaluation of microcirculatory and mitochondrial variables could identify tissues at risk during hypoxic challenges, indicate an increase of intestinal injury, and improve our understanding of regional pathophysiology during acute hemorrhage. Furthermore, improving intestinal microcirculation or mitochondrial respiration, e.g. by remote ischemic preconditioning (RIPC) that was reported to exert a sufficient tissue protection in various tissues and was linked to mediators with vasoactive properties could maintain intestinal integrity. In this study, postcapillary oxygen saturation (µHbO2), microvascular flow index (MFI) and plasmatic D-lactate concentration revealed to be early markers of intestinal injury in a rodent model of experimental hemorrhagic shock. Mitochondrial function was not impaired in this experimental model of acute hemorrhage. Remote ischemic preconditioning (RIPC) failed to improve intestinal microcirculation and intestinal damage during hemorrhagic shock.

Scattered Crypt Intestinal Epithelial Cell Apoptosis Induces Necrotizing Enterocolitis Via Intricate Mechanisms

BACKGROUND & AIMS

Necrotizing enterocolitis (NEC) is a life-threatening disease affecting mostly the ileum of preemies. Intestinal epithelial cell (IEC) apoptosis contributes to NEC pathogenesis. However, how scattered crypt IEC apoptosis leads to NEC with excessive villus epithelial necrosis remains unclear.

METHODS

A novel triple-transgenic mouse model, namely, 3xTg-iAPcIEC (inducible apoptosis phenotype in crypt-IEC), was developed to induce IEC-specific overexpression of Fasl transgene using doxycycline (Dox)-inducible tetO-rtTA system and villin-cre technology. The 3-days-old neonatal 3xTg-iAPcIEC mice and their littermate controls were subcutaneously (s.c.) challenged with a single dose of Dox. Intestinal tissues were processed at different time points to examine scattered crypt IEC apoptosis-mediated NEC development. Gene knockout technology, antibody-mediated cell depletion, and antibiotic-facilitated Gram-positive bacteria depletion were used to study mechanisms.

RESULTS

Treatment of 3xTg-iAPcIEC mouse pups with Dox induces scattered crypt IEC apoptosis followed by crypt inflammation and excessive villous necrosis resembling NEC. This progression correlated with elevated Ifng, Rip3, CD8+ T cells, and Gram-positive bacteria in the ileum. Mechanistically, IFN-γ and RIP3-activated signals mediate the effect of scattered crypt IEC apoptosis on the induction of intestinal crypt inflammation and villous necrosis. Meanwhile, pathophysiological events of CD8+ T cell infiltration and dysbiosis with Gram-positive bacteria primarily contribute to excessive villous inflammation and necrosis. Notably, blocking any of these events protects against NEC development in 3xTg-iAPcIEC mouse pups, underlining their central roles in NEC pathogenesis.

CONCLUSIONS

Scattered crypt IEC apoptosis induces NEC in mouse pups via IFN-γ, RIP3, CD8+ T cells, and Gram-positive bacteria-mediated comprehensive pathophysiological events. Our findings may advance knowledge in the prevention and treatment of NEC.

Development of an artificial intelligence-based multimodal model for assisting in the diagnosis of necrotizing enterocolitis in newborns: a retrospective study

Objective

The purpose of this study is to develop a multimodal model based on artificial intelligence to assist clinical doctors in the early diagnosis of necrotizing enterocolitis in newborns.

Methods

This study is a retrospective study that collected the initial laboratory test results and abdominal x-ray image data of newborns (non-NEC, NEC) admitted to our hospital from January 2022 to January 2024.A multimodal model was developed to differentiate multimodal data, trained on the training dataset, and evaluated on the validation dataset. The interpretability was enhanced by incorporating the Gradient-weighted Class Activation Mapping (GradCAM) analysis to analyze the attention mechanism of the multimodal model, and finally compared and evaluated with clinical doctors on external datasets.

Results

The dataset constructed in this study included 11,016 laboratory examination data from 408 children and 408 image data. When applied to the validation dataset, the area under the curve was 0.91, and the accuracy was 0.94. The GradCAM analysis shows that the model's attention is focused on the fixed dilatation of the intestinal folds, intestinal wall edema, interintestinal gas, and portal venous gas. External validation demonstrated that the multimodal model had comparable accuracy to pediatric doctors with ten years of clinical experience in identification.

Conclusion

The multimodal model we developed can assist doctors in early and accurate diagnosis of NEC, providing a new approach for assisting diagnosis in underdeveloped medical areas.

Transcriptomic analysis of the effect of remote ischaemic conditioning in an animal model of necrotising enterocolitis

Necrotising enterocolitis (NEC) has a complex pathophysiology but the common end-point is ischaemia reperfusion injury (IRI) and intestinal necrosis. We have previously reported that RIC significantly reduces the intestinal injury in a rat model of NEC. Here we describe the changes in intestinal mRNA occurring in the intestine of animals exposed to IRI, both with and without RIC. Related rat-pups were randomly assigned to four groups: SHAM, IRI only, RIC only and RIC + IRI. IRI animals, underwent 40 min of intestinal ischaemia, and 90 min of reperfusion. Animals that underwent RIC had three cycles of 5 min of alternating ischaemia/reperfusion by means of a ligature applied to the hind limb. Samples from the terminal ileum were immediately stored in RNA-preserving media for later next generation sequencing and transciptome analysis using R v 3.6.1. Differential expression testing showed that 868 genes differentially expressed in animals exposed to RIC alone compared to SHAM and 135 in the IRI and RIC group compared to IRI alone. Comparison between these two sets showed that 25 genes were differentially expressed in both groups. Pro-inflammatory molecules: NF-ĸβ2, Cxcl1, SOD2 and Map3k8 all show reduced expression in response to RIC. Targeted gene analysis revealed increased expression in PI3K which is part of the so-called RISK-pathway which is a key part of the protective mechanisms of RIC in the heart. Overall, this transcriptomic analysis shows that RIC provides a protective effect to the intestine via anti-inflammatory pathways. This could be particularly relevant to treating and preventing NEC.

More than nutrition: Therapeutic potential and mechanism of human milk oligosaccharides against necrotizing enterocolitis

Human milk is the most valuable source of nutrition for infants. The structure and function of human milk oligosaccharides (HMOs), which are key components of human milk, have long been attracting particular research interest. Several recent studies have found HMOs to be efficacious in the prevention and treatment of necrotizing enterocolitis (NEC). Additionally, they could be developed in the future as non-invasive predictive markers for NEC. Based on previous findings and the well-defined functions of HMOs, we summarize potential protective mechanisms of HMOs against neonatal NEC, which include: modulating signal receptor function, promoting intestinal epithelial cell proliferation, reducing apoptosis, restoring intestinal blood perfusion, regulating microbial prosperity, and alleviating intestinal inflammation. HMOs supplementation has been demonstrated to be protective against NEC in both animal studies and clinical observations. This calls for mass production and use of HMOs in infant formula, necessitating more research into the safety of industrially produced HMOs and the appropriate dosage in infant formula.

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.

Chronic remote ischemic conditioning treatment in patients with chronic stable angina (EARLY-MYO-CSA): a randomized, controlled proof-of-concept trial

BACKGROUND

Chronic remote ischemic conditioning (CRIC) has been shown to improve myocardial ischemia in experimental animal studies; however, its effectiveness in patients with chronic stable angina (CSA) has not been investigated. We conducted a proof-of-concept study to investigate the efficacy and safety of a six-month CRIC treatment in patients with CSA.

METHODS

The EARLY-MYO-CSA trial was a prospective, randomized, controlled trial evaluating the CRIC treatment in patients with CSA with persistent angina pectoris despite receiving ≥ 3-month guideline-recommended optimal medical therapy. The CRIC and control groups received CRIC (at 200 mmHg) or sham CRIC (at 60 mmHg) intervention for 6 months, respectively. The primary endpoint was the 6-month change of myocardial flow reserve (MFR) on single-photon emission computed tomography. The secondary endpoints were changes in rest and stress myocardial blood flow (MBF), angina severity according to the Canadian Cardiovascular Society (CCS) classification, the Seattle Angina Questionnaire (SAQ), and a 6-min walk test (6-MWT).

RESULTS

Among 220 randomized CSA patients, 208 (105 in the CRIC group, and 103 in the control group) completed the treatment and endpoint assessments. The mean change in MFR was significantly greater in the CRIC group than in the control group (0.27 ± 0.38 vs. - 0.04 ± 0.25; P < 0.001). MFR increased from 1.33 ± 0.48 at baseline to 1.61 ± 0.53 (P < 0.001) in the CRIC group; however, a similar increase was not seen in the control group (1.35 ± 0.45 at baseline and 1.31 ± 0.44 at follow-up, P = 0.757). CRIC treatment, when compared with controls, demonstrated improvements in angina symptoms assessed by CCS classification (60.0% vs. 14.6%, P < 0.001), all SAQ dimensions scores (P < 0.001), and 6-MWT distances (440 [400-523] vs. 420 [330-475] m, P = 0.016). The incidence of major adverse cardiovascular events was similar between the groups.

CONCLUSIONS

CSA patients benefit from 6-month CRIC treatment with improvements in MFR, angina symptoms, and exercise performance. This treatment is well-tolerated and can be recommended for symptom relief in this clinical population.

TRIAL REGISTRATION

[chictr.org.cn], identifier [ChiCTR2000038649].

The severity of NEC is ameliorated by prostaglandin E2 through regulating intestinal microcirculation

Prostaglandin E2 (PGE2) is implicated in intestinal inflammation and intestinal blood flow regulation with a paradoxical effect on the pathogenesis of necrotizing enterocolitis (NEC), which is not yet well understood. In the current study, we found that PGE2, EP4, and COX-2 varied at different distances from the most damaged area in the terminal ileum obtained from human infants with NEC. PGE2 administration alleviated the phenotype of experimental NEC and the intestinal microvascular features in experimental NEC, but this phenomenon was inhibited by eNOS depletion, suggesting that PGE2 promoted intestinal microcirculatory perfusion through eNOS. Furthermore, PGE2 administration increased the VEGF content in MIMECs under TNFα stress and promoted MIMEC proliferation. This response to PGE2 was involved in eNOS phosphorylation and nitric oxide (NO) production and was blocked by the EP4 antagonist in vitro, suggesting that targeting the PGE2-EP4-eNOS axis might be a potential clinical and therapeutic strategy for NEC treatment. The study is reported in accordance with ARRIVE guidelines ( https://arriveguidelines.org ).

Endothelial FOXC1 and FOXC2 promote intestinal regeneration after ischemia-reperfusion injury

Intestinal ischemia underlies several clinical conditions and can result in the loss of the intestinal mucosal barrier. Ischemia-induced damage to the intestinal epithelium is repaired by stimulation of intestinal stem cells (ISCs), and paracrine signaling from the vascular niche regulates intestinal regeneration. Here, we identify FOXC1 and FOXC2 as essential regulators of paracrine signaling in intestinal regeneration after ischemia-reperfusion (I/R) injury. Vascular endothelial cell (EC)- and lymphatic EC (LEC)-specific deletions of Foxc1, Foxc2, or both in mice worsen I/R-induced intestinal damage by causing defects in vascular regrowth, expression of chemokine CXCL12 and Wnt activator R-spondin 3 (RSPO3) in blood ECs (BECs) and LECs, respectively, and activation of Wnt signaling in ISCs. Both FOXC1 and FOXC2 directly bind to regulatory elements of the CXCL12 and RSPO3 loci in BECs and LECs, respectively. Treatment with CXCL12 and RSPO3 rescues the I/R-induced intestinal damage in EC- and LEC-Foxc mutant mice, respectively. This study provides evidence that FOXC1 and FOXC2 are required for intestinal regeneration by stimulating paracrine CXCL12 and Wnt signaling.

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.

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.

Single-cell atlas of the human neonatal small intestine affected by necrotizing enterocolitis

Necrotizing enterocolitis (NEC) is a gastrointestinal complication of premature infants with high rates of morbidity and mortality. A comprehensive view of the cellular changes and aberrant interactions that underlie NEC is lacking. This study aimed at filling in this gap. We combine single-cell RNA sequencing (scRNAseq), T-cell receptor beta (TCRβ) analysis, bulk transcriptomics, and imaging to characterize cell identities, interactions, and zonal changes in NEC. We find an abundance of proinflammatory macrophages, fibroblasts, endothelial cells as well as T cells that exhibit increased TCRβ clonal expansion. Villus tip epithelial cells are reduced in NEC and the remaining epithelial cells up-regulate proinflammatory genes. We establish a detailed map of aberrant epithelial-mesenchymal-immune interactions that are associated with inflammation in NEC mucosa. Our analyses highlight the cellular dysregulations of NEC-associated intestinal tissue and identify potential targets for biomarker discovery and therapeutics.

Effect of remote ischemic preconditioning on postoperative gastrointestinal function in patients undergoing laparoscopic colorectal cancer resection

PURPOSE

Patients undergoing laparoscopic colorectal cancer resection have a high incidence of postoperative gastrointestinal dysfunction (POGD). Remote ischemic preconditioning (RIPC) is an organ protection measure. The study investigated the effect of RIPC on postoperative gastrointestinal function.

METHODS

In this single-center, prospective, double-blinded, randomized, parallel-controlled trial, 100 patients undergoing elective laparoscopic colorectal cancer resection were randomly assigned in a 1:1 ratio to receive RIPC or sham RIPC (control). Three cycles of 5-min ischemia/5-min reperfusion induced by a blood pressure cuff placed on the right upper arm served as RIPC stimulus. Patients were followed up continuously for 7 days after surgery. The I-FEED score was used to evaluate the patient's gastrointestinal function after the surgery. The primary outcome of the study was the I-FEED score on POD3. Secondary outcomes include the daily I-FEED scores, the highest I-FEED score, the incidence of POGD, the changes in I-FABP and the inflammatory markers (IL-6 and TNF-α), and the time to first postoperative flatus.

RESULTS

A total of 100 patients were enrolled in the study, of which 13 patients were excluded. Finally, 87 patients were included in the analysis, 44 patients in the RIPC group and 43 patients in the sham-RIPC group. Patients assigned to the RIPC group had a lower I-FEED score on POD3 compared with the sham-RIPC group (mean difference 0.86; 95% CI: 0.06 to 1.65; P = 0.035). And patients in the RIPC group were also associated with a lower I-FEED score on POD4 vs the sham-RIPC group (mean difference 0.81; 95% CI: 0.03 to 1.60; P = 0.043). Compared with the sham-RIPC group, the incidence of POGD within 7 days after surgery was lower in the RIPC group (P = 0.040). At T₁, T₂, and T₃ time points, inflammatory factors and I-FABP were considerably less in the RIPC group compared to the sham-RIPC group. The time to the first flatus and the first feces was similar in both groups.

CONCLUSION

RIPC reduced I-FEED scores, decreased the incidence of postoperative gastrointestinal dysfunction, and lowered concentrations of I-FABP and inflammatory factors.

Global trend and future landscape of intestinal microcirculation research from 2000 to 2021: A scientometric study

BACKGROUND

The intestinal microcirculation functions in food absorption and metabolic substance exchanges. Accumulating evidence indicates that intestinal microcirculatory dysfunction is a significant source of multiple gastrointestinal diseases. To date, there has not been a scientometric analysis of intestinal microcirculatory research.

AIM

To investigate the current status, development trends, and frontiers of intestinal microcirculatory research based on bibliometric analysis.

METHODS

VOSviewer and CiteSpace 6.1.R2 were used to identify the overall characteristics and knowledge map of intestinal microcirculatory research based on the core literature published from 2000 to 2021 in the Web of Science database. The characteristics of each article, country of origin, institution, journal, cocitations, and other information were analyzed and visualized.

RESULTS

There were 1364 publications enrolled in the bibliometric analysis, exhibiting an upward trend from 2000 to 2021 with increased participation worldwide. The United States and Dalhousie University took the lead among countries and institutions, respectively. Shock was the most prolific journal, and Nature Reviews Microbiology Clinical had the most citations. The topical hotspots and frontiers in intestinal microcirculatory research were centered on the pathological processes of functional impairment of intestinal microvessels, diverse intestinal illnesses, and clinical treatment.

CONCLUSION

Our study highlights insights into trends of the published research on the intestinal microcirculation and offers serviceable guidance to researchers by summarizing the prolific areas in intestinal disease research to date.

Does protocol miconazole administration improve mortality and morbidity on surgical necrotizing enterocolitis?

PURPOSE

Our previous clinical pilot study reported that miconazole (MCZ) prevented morbidity from surgical necrotizing enterocolitis (NEC). The present study re-investigated this effect in a long-term cohort over 20 years.

METHODS

We conducted a retrospective cohort study from April 1998 to March 2020. A total of 1169 extremely low-birth-weight infants (ELBWIs) admitted to our neonatal intensive care unit, including 45 with NEC (3.8%), underwent surgery. Since 2002, protocol MCZ administration for 3 weeks has been applied for neonates born before 26 weeks' gestation or weighing under 1000 g. We compared the background characteristics and clinical outcomes between patients with and without MCZ administration.

RESULTS

The morbidity rate decreased after applying the MCZ protocol, but no improvement in mortality was seen. A propensity score-matched analysis indicated that treated patients by MCZ showed a delay in developing surgical NEC by 12 days. The MCZ protocol also helped increase body weight at surgery. Prophylactic MCZ administration did not improve the neurological development of the language-social and postural-motor domains in the surgical NEC patients. But cognitive-adaptive domain caught up by a chronological age of 3 years old.

CONCLUSIONS

Revising the protocol to extend the dosing period may improve the outcomes of surgical NEC after the onset.

Intravital imaging of immune responses in intestinal inflammation

To date, many kinds of immune cells have been identified, but their precise roles in intestinal immunity remain unclear. Understanding the in vivo behavior of these immune cells and their function in gastrointestinal inflammation, including colitis, inflammatory bowel disease, ischemia-reperfusion injury, and neutrophil extracellular traps, is critical for gastrointestinal research to proceed to the next step. Additionally, understanding the immune responses involved in gastrointestinal tumors and tissue repair is becoming increasingly important for the elucidation of disease mechanisms that have been unknown. In recent years, the application of intravital microscopy in gastrointestinal research has provided novel insights into the mechanisms of intestine-specific events including innate and adaptive immunities. In this review, we focus on the emerging role of intravital imaging in gastrointestinal research and describe how to observe the intestines and immune cells using intravital microscopy. Additionally, we outline novel findings obtained by this new technique.

Necrotizing Enterocolitis: The Role of Hypoxia, Gut Microbiome, and Microbial Metabolites

Necrotizing enterocolitis (NEC) is a life-threatening disease that predominantly affects very low birth weight preterm infants. Development of NEC in preterm infants is accompanied by high mortality. Surgical treatment of NEC can be complicated by short bowel syndrome, intestinal failure, parenteral nutrition-associated liver disease, and neurodevelopmental delay. Issues surrounding pathogenesis, prevention, and treatment of NEC remain unclear. This review summarizes data on prenatal risk factors for NEC, the role of pre-eclampsia, and intrauterine growth retardation in the pathogenesis of NEC. The role of hypoxia in NEC is discussed. Recent data on the role of the intestinal microbiome in the development of NEC, and features of the metabolome that can serve as potential biomarkers, are presented. The Pseudomonadota phylum is known to be associated with NEC in preterm neonates, and the role of other bacteria and their metabolites in NEC pathogenesis is also discussed. The most promising approaches for preventing and treating NEC are summarized.

CCL3 aggravates intestinal damage in NEC by promoting macrophage chemotaxis and M1 macrophage polarization

BACKGROUND

NEC is a life-threatening gastrointestinal disease in neonates, the pathogenesis of which remains poorly understood.

METHODS

CCL3 levels in intestinal tissue of mice were measured and analyzed. HE staining was used to assess pathological changes in intestinal tissue. FCM was used to detect the proportion and phenotype of macrophages. RNA-seq and RT-PCR were used to evaluate the effect of CCL3 on macrophages.

RESULTS

CCL3 was highly expressed in the intestinal tissues of mice with NEC and induced macrophage infiltration. Transcriptome data showed that CCL3 strongly induced a transition in the phenotype of macrophages into a proinflammatory one. Mechanistically, in vivo experiments confirmed that CCL3 induced M1 macrophage polarization in NEC intestinal tissue, thereby aggravating inflammatory injury of intestinal tissue, which was alleviated by anti-CCL3 treatment. In addition, in vitro experiments showed that CCL3 significantly enhances the expression of M1-related genes in both PMφ and BMDM while inhibiting the expression of M2-related genes, which was also alleviated by anti-CCl3 treatment.

CONCLUSIONS

Our data elucidated the involvement of CCL3 in the pathogenesis of NEC, in which upregulated CCL3 expression exacerbated inflammatory intestinal damage by regulating macrophage chemotaxis and M1 phenotype polarization, suggesting that blocking CCL3 may be a potential strategy for effective intervention in NEC.

IMPACT

Our study represents an important conceptual advancement that CCL3 may be one of the key culprits of intestinal tissue damage in patients with NEC. CCL3 aggravates inflammatory intestinal injury and intestinal mucosal barrier imbalance by regulating the chemotaxis, polarization, and function of macrophages. Blocking CCL3 significantly reduced NEC-mediated intestinal injury, suggesting a new potential therapeutic strategy.

Remote ischaemic pre-conditioning reduces intestinal ischaemia reperfusion injury in a newborn rat

OBJECTIVE

Remote ischaemic conditioning (RIC) has been shown to reduce ischaemia-reperfusion injury(IRI) in multiple organ systems. IRI is seen in multiple bowel pathologies in the newborn, including NEC. We investigated the potential of RIC as a novel therapy for various intestinal pathologies in the newborn.

METHODS

We used an established intestinal IRI model in rat pups which results in similar intestinal injury to necrotising enterocolitis (NEC). Animals were randomly allocated to IRI only(n = 14), IRI + RIC(n = 13) or sham laparotomy(n = 10). The macroscopic extent of intestinal injury is reported as a percentage of total small bowel. Injury severity was measured using Chiu-Park scoring. Neutrophil infiltration/activation was assayed by myeloperoxidase activity. Immunohistochemistry was used to assess the expression of hypoxia-inducible factor alpha (HIF-1α). Data are median (interquartile range).

RESULTS

Animals that underwent RIC showed a decreased extent of macroscopic injury from 100%(85-100%) in the IRI only group to 58%(15-84%, p = 0.003) in the IRI + RIC group. Microscopic injury score was significantly lower in animals that underwent RIC compared to IRI alone (3.5[1.25-5] vs 5.5[4-6], p = 0.014). Intestinal myeloperoxidase activity in animals exposed to IRI was 3.4 mU/mg of tissue (2.5-3.7) and 2.1 mU/mg(1.5-2.8) in the IRI + RIC group(p = 0.047). HIF-1α expression showed a non-significant trend towards reduced expression in the IRI + RIC group.

CONCLUSIONS

RIC reduces the extent and severity of bowel injury in this animal model, supporting the hypothesis that RIC has therapeutic potential for intestinal diseases in the newborn.

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.

A potential pathogenic hypoxia-related gene HK2 in necrotizing enterocolitis (NEC) of newborns

Background

Necrotizing enterocolitis (NEC) is a disastrous gastrointestinal disease of newborns, and the mortality rate of infants with NEC is approximately 20%-30%. The exploration of pathogenic targets of NEC will be conducive to timely diagnosis of NEC.

Methods

The whole transcriptome RNA sequencing was performed on NEC samples to reveal the expression of lncRNAs, circRNAs, miRNAs and mRNAs. Using differential expression analysis, cross analysis, target prediction, enrichment analysis, the pathogenic ceRNA network and target was found.

Results

Preliminarily, 281 DEmRNAs, 21 DEmiRNAs, 253 DElncRNAs and 207 DEcircRNAs were identified in NEC samples compared with controls. After target prediction and cross analyses, a key ceRNA regulatory network was built including 2 lncRNAs, 4 circRNAs, 2 miRNAs and 20 mRNAs. These 20 mRNAs were significantly enriched in many carbohydrate metabolism related pathways. After cross analysis of hypoxia-, carbohydrate metabolism-related genes, and 20 core genes, one gene HK2 was finally obtained. Dendritic cells activated were significantly differentially infiltrated and negatively correlated with HK2 expression in NEC samples.

Conclusions

The promising pathogenic hypoxia-related gene HK2 has been firstly identified in NEC, which might also involve in the carbohydrate metabolism in NEC.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12887-022-03664-w.

Lymphatic microcirculation profile in the progression of hypertension in spontaneously hypertensive rats

OBJECTIVE

The contractile behavior of collecting lymphatic vessels occurs in essential hypertension in response to homeostasis, suggesting a possible role for microcirculation. We aimed to clarify the nature of the lymphatic microcirculation profile in spontaneously hypertensive rats (SHRs) and normotensive controls.

METHODS

The vasomotion of collecting lymphatic vessels in eight- and thirteen-week-old SHRs and age-matched Wistar-Kyoto rats (WKYs, n = 4 per group) was visualized by intravital video and VasTrack. The lymphatic vasomotion profile (frequency and amplitude) and contractile parameters (contraction fraction and total contractility activity index) were compared. Plasma nitrite/nitrate levels were assessed by the Griess reaction, and plasma endothelin-1 was measured by enzyme-linked immunosorbent assay.

RESULTS

WKYs and SHRs differed in the vasomotion of collecting lymphatic vessels. Both eight- and thirteen-week-old WKYs revealed a high-amplitude pumping pattern, whereas a low-amplitude pattern was observed in SHRs. Moreover, compared with age-matched WKYs, SHRs exhibited deteriorated output and reflux capability and lost the ability to regulate collecting lymphatic vasomotion. Additionally, the chemistry complements the microcirculatory lymphatic profile as demonstrated by an increase in plasma nitrite, nitrate, and endothelin-1 in SHRs. ET-1 inhibitor meliorated the lymphatic contractile capability in SHRs partially through regulating frequency of lymphatic vasomotion.

CONCLUSIONS

We used an intravital lymphatic imaging system to observe that SHRs exhibit an impaired collecting lymphatic vasomotion profile and deteriorated contractility and reflux.

In vivo phenotyping of the microvasculature in necrotizing enterocolitis with multicontrast optical imaging

OBJECTIVE

Necrotizing enterocolitis (NEC) is the most prevalent gastrointestinal emergency in premature infants and is characterized by a dysfunctional gut microcirculation. Therefore, there is a dire need for in vivo methods to characterize NEC-induced changes in the structure and function of the gut microcirculation, that is, its vascular phenotype. Since in vivo gut imaging methods are often slow and employ a single-contrast mechanism, we developed a rapid multicontrast imaging technique and a novel analyses pipeline for phenotyping the gut microcirculation.

METHODS

Using an experimental NEC model, we acquired in vivo images of the gut microvasculature and blood flow over a 5000 × 7000 μm² field of view at 5 μm resolution via the following two endogenous contrast mechanisms: intrinsic optical signals and laser speckles. Next, we transformed intestinal images into rectilinear "flat maps," and delineated 1A/V gut microvessels and their perfusion territories as "intestinal vascular units" (IVUs). Employing IVUs, we quantified and visualized NEC-induced changes to the gut vascular phenotype.

RESULTS

In vivo imaging required 60-100 s per animal. Relative to the healthy gut, NEC intestines showed a significant overall decrease (i.e. 64-72%) in perfusion, accompanied by vasoconstriction (i.e. 9-12%) and a reduction in perfusion entropy (19%)within sections of the vascular bed.

CONCLUSIONS

Multicontrast imaging coupled with IVU-based in vivo vascular phenotyping is a powerful new tool for elucidating NEC pathogenesis.

Neonatal multiple organ failure after perinatal asphyxia

Perinatal asphyxia is an event with far-reaching consequences that can lead not only to the development of neonatal encephalopathy, but also to multiple organ failure (MOF). This ailment may result from the redistribution of blood flow, which would preserve the perfusion of vital organs such as the heart, brain and adrenal glands at the expense of other organs. The objective of the study was to determine the incidence and aetiopathogenesis of failure in the organs most frequently involved in neonatal MOF following perinatal asphyxia. We conducted a systematic literature search in the PubMed, Scopus and Cochrane Library databases using the MeSH terms (ischemia AND hypoxia AND multiorgan dysfunction AND neonat*), (asphyxia AND multiorgan dysfunction AND neonat*) and (liver/kidney/digestive OR gastrointestinal/heart injury AND ischemia AND hypoxia AND neonat*). We selected clinical and preclinical studies published after 2000 and excluded case series, letters to the editor, cohort studies without comparison groups and abstracts. In this study, we found that MOF associated with perinatal asphyxia is a frequent phenomenon with a relevant impact on neonatal morbidity and mortality, as it can cause changes not only in the kidney, liver and gastrointestinal tract, but also cardiomyopathy if the ailment is protracted or severe.

Bench to bedside - new insights into the pathogenesis of necrotizing enterocolitis

Necrotizing enterocolitis (NEC) is the leading cause of death and disability from gastrointestinal disease in premature infants. Recent discoveries have shed light on a unifying theorem to explain the pathogenesis of NEC, suggesting that specific treatments might finally be forthcoming. A variety of experiments have highlighted how the interaction between bacterial signalling receptors on the premature intestine and an abnormal gut microbiota incites a pro-inflammatory response in the intestinal mucosa and its underlying endothelium that leads to NEC. Central amongst the bacterial signalling receptors implicated in NEC development is the lipopolysaccharide receptor Toll-like receptor 4 (TLR4), which is expressed at higher levels in the premature gut than in the full-term gut. The high prenatal intestinal expression of TLR4 reflects the role of TLR4 in the regulation of normal gut development, and supports additional studies indicating that NEC develops in response to signalling events that occur in utero. This Review provides new evidence explaining the pathogenesis of NEC, explores new findings indicating that NEC development has origins before birth, and discusses future questions and opportunities for discovery in this field.

Remote ischemic conditioning causes CD4 T cells shift towards reduced cell-mediated inflammation

PURPOSE

Necrotizing enterocolitis (NEC) is a gastrointestinal disease in neonates that is associated with immune-mediated intestinal inflammation. Remote ischemic conditioning (RIC) applied to a limb has been shown to be protective against experimental NEC. In this study, we explore the immune cell-mediated response involved in NEC and the immunomodulatory effects of RIC in an experimental mouse model of the disease.

METHODS

NEC was induced in C57BL/6 mice (ethical approval #58119) pups on postnatal day5 (p5) using gavage hyperosmolar formula, lipopolysaccharide, and hypoxia. RIC consisted of 4 cycles of 5 min ischemia followed by 5 min reperfusion of the right hindlimb during NEC induction on p6 and p8. Breastfed mice were used as control. The mice were sacrificed on p9, with ileal tissue evaluated for inflammatory cytokines and by characterization of T-cell populations.

RESULTS

NEC mice had increased number of CD4⁺ cells indicating an accumulation of T-cells in the mesenchyme of the NEC ileum. Compared to control, NEC pups had upregulated expression pro-inflammatory cytokines (GATA3, IFNγ, IL1β, IL6, IL17, IL22, and TNFα) and reduced anti-inflammatory cytokine (TGFβ). In NEC, there was also a shift in the balance of Treg/Th17 cells towards Th17. Compared to NEC alone, RIC during the course of NEC resulted in reduction of pro-inflammatory cytokines (GATA3, IFNγ, IL1β, IL6, IL17, IL22, and TNFα), increase in anti-inflammatory cytokine TGFβ and concomitant shift back of Th17 cells towards Treg cells.

CONCLUSION

In experimental NEC, remote ischemic conditioning reduces the production of pro-inflammatory markers and increases the production of anti-inflammatory markers. In addition, during NEC, RIC reverses the imbalance of Treg/Th17 providing support for its effect on cell-mediated inflammation. RIC is a non-invasive physical maneuver that can have a significant beneficial effect in reducing the inflammation seen in NEC.

Remote ischemic conditioning in necrotizing enterocolitis: study protocol of a multi-center phase II feasibility randomized controlled trial

PURPOSE

Remote ischemic conditioning (RIC) is a maneuver involving brief cycles of ischemia reperfusion in an individual's limb. In the early stage of experimental NEC, RIC decreased intestinal injury and prolonged survival by counteracting the derangements in intestinal microcirculation. A single-center phase I study demonstrated that the performance of RIC was safe in neonates with NEC. The aim of this phase II RCT was to evaluate the safety and feasibility of RIC, to identify challenges in recruitment, retainment, and to inform a phase III RCT to evaluate efficacy.

METHODS

RIC will be performed by trained research personnel and will consist of four cycles of limb ischemia (4-min via cuff inflation) followed by reperfusion (4-min via cuff deflation), repeated on two consecutive days post randomization. The primary endpoint of this RCT is feasibility and acceptability of recruiting and randomizing neonates within 24 h from NEC diagnosis as well as masking and completing the RIC intervention.

RESULTS

We created a novel international consortium for this trial and created a consensus on the diagnostic criteria for NEC and protocol for the trial. The phase II multicenter-masked feasibility RCT will be conducted at 12 centers in Canada, USA, Sweden, The Netherlands, UK, and Spain. The inclusion criteria are: gestational age < 33 weeks, weight ≥ 750 g, NEC receiving medical treatment, and diagnosis established within previous 24 h. Neonates will be randomized to RIC (intervention) or no-RIC (control) and will continue to receive standard management of NEC. We expect to recruit and randomize 40% of eligible patients in the collaborating centers (78 patients; 39/arm) in 30 months. Bayesian methods will be used to combine uninformative prior distributions with the corresponding observed proportions from this trial to determine posterior distributions for parameters of feasibility.

CONCLUSIONS

The newly established NEC consortium has generated novel data on NEC diagnosis and defined the feasibility parameters for the introduction of a novel treatment in NEC. This phase II RCT will inform a future phase III RCT to evaluate the efficacy and safety of RIC in early-stage NEC.

Advances in our understanding of the molecular pathogenesis of necrotizing enterocolitis

Necrotizing enterocolitis (NEC) is a multifactorial and complex disease. Our knowledge of the cellular and genetic basis of NEC have expanded considerably as new molecular mechanisms have been identified. This article will focus on the current understanding of the molecular pathogenesis of NEC with a focus on the inflammatory, immune, infectious, and genetic mechanisms that drive disease development.

Cellular Immune Signal Exchange From Ischemic Stroke to Intestinal Lesions Through Brain-Gut Axis

As a vital pivot for the human circulatory system, the brain-gut axis is now being considered as an important channel for many of the small immune molecules’ transductions, including interleukins, interferons, neurotransmitters, peptides, and the chemokines penetrating the mesentery and blood brain barrier (BBB) during the development of an ischemic stroke (IS). Hypoxia-ischemia contributes to pituitary and neurofunctional disorders by interfering with the molecular signal release and communication then providing feedback to the gut. Suffering from such a disease on a long-term basis may cause the peripheral system’s homeostasis to become imbalanced, and it can also lead to multiple intestinal complications such as gut microbiota dysbiosis (GMD), inflammatory bowel disease (IBD), necrotizing enterocolitis (NEC), and even the tumorigenesis of colorectal carcinoma (CRC). Correspondingly, these complications will deteriorate the cerebral infarctions and, in patients suffering with IS, it can even ruin the brain’s immune system. This review summarized recent studies on abnormal immunological signal exchange mediated polarization subtype changes, in both macrophages and microglial cells as well as T-lymphocytes. How gut complications modulate the immune signal transduction from the brain are also elucidated and analyzed. The conclusions drawn in this review could provide guidance and novel strategies to benefit remedies for both IS and relative gut lesions from immune-prophylaxis and immunotherapy aspects.

Prediction of necrotizing enterocolitis in very low birth weight infants by superior mesenteric artery ultrasound of postnatal day 1: A nested prospective study

BACKGROUND

Necrotizing enterocolitis (NEC) is a devastating intestinal complication that occurs mainly in very-low-birth-weight infants (VLBWI). The study's aim was to investigate the possibility of early prediction of NEC on postnatal day 1 based on superior mesenteric artery (SMA) doppler ultrasonograpy.

METHODS

A prospective, observational, nested case control study (ChiCTR1900026197) was conducted to enroll VLBWIs (birth weight <1,500 grams) between October 2019 and September 2021. Doppler ultrasound measurement was done during the first 12 h of life and before first feeding. Infants developing NEC (stage II or III) subsequently were included in NEC group and infants spare of NEC were included in control group.

RESULTS

370 VLBWIs were enrolled (30 NEC cases). Among the ultrasound parameters, S/D was significantly higher in the NEC group (OR: 2.081, 95% CI: 1.411-3.069, P = 0.000). The area under the receiver operating curve (AUROC) following the Logistic regression was 0.704 (95% CI: 0.566-0.842, P = 0.001). The sensitivity of S/D for predicting NEC was 52.2% and the specificity was 92.7%. The critical value of S/D was 6.944 and Youden index was 0.449. Preplanned subgroup analysis confirmed that NEC infants of different stages were characterized by different SMA bloodstream. Small for gestational age (SGA) might be a confounding factor affecting intestinal bloodflow. And infants with delayed initiation or slow advancement of feeding exhibited characteristic intestinal perfusion.

CONCLUSIONS

In VLBWI, early SMA ultrasound shows the potential to predict NEC. It is reasonable to speculate that SMA bloodstream is related to intestinal structural and functional integrity.

Amniotic fluid stem cell administration can prevent epithelial injury from necrotizing enterocolitis

BACKGROUND

Stem cell therapy has been proven to rescue intestinal injury and stimulate intestinal regeneration in necrotizing enterocolitis (NEC). Specifically, stem cells derived from amniotic fluid (AFSCs) and mesenchymal stem cells (MSCs) derived from bone marrow have shown promising results in the treatment of experimental NEC. This study aims to examine the effects of AFSCs and MSCs on the prevention of intestinal injury during experimental NEC.

METHODS

Supernatants from AFSC and MSC cultures were collected to perform proteomic analysis. Prior to NEC induction, mice received intraperitoneal injections of phosphate-buffered saline (PBS), 2 × 10⁶ AFSCs, or 2 × 10⁶ MSCs.

RESULTS

We found that AFSCs grew faster than MSCs. Proteomic analysis indicated that AFSCs are primarily involved in cell development and growth, while MSCs are involved in immune regulation. Administering AFSCs before NEC induction decreased NEC severity and mucosal inflammation. Intestinal proliferation and endogenous stem cell activation were increased after AFSC administration. However, administering MSCs before NEC induction had no beneficial effects.

CONCLUSIONS

This study demonstrated that AFSCs and MSCs have different protein release profiles. AFSCs can potentially be used as a preventative strategy for neonates at risk of NEC, while MSCs cannot be used.

IMPACT

AFSCs and MSCs have distinct protein secretory profiles, and AFSCs are primarily involved in cell development and growth, while MSCs are involved in immune regulation. AFSCs are unique in transiently enhancing healthy intestinal epithelial cell growth, which offers protection against the development of experimental NEC. The prevention of NEC via the administration of AFSCs should be evaluated in infants at great risk of developing NEC or in infants with early signs of NEC.

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.

Ischemic perconditioning on mesenteric ischemia/reperfusion injury in rats

Purpose:

To evaluate if the perconditioning affects the antioxidant capacity in mesenteric ischemia and reperfusion injury.

Methods:

Twenty-one Wistar rats were assigned into three groups, as follows: Sham, IR and rPER. The animals were subjected to mesenteric ischemia for 30 min. rPER consisted of three cycles of 5-min hindlimb ischemia followed by 5 min hindlimb perfusion at the same time to mesenteric ischemic period. After 5 minutes, blood and 5 cm of terminal ileum were harvested for thiobarbituric acid reactive substances (TBARS) and Trolox equivalent antioxidant capacity (TEAC) measurement.

Results:

rPER technique was able to reduce intestinal tissue TBARS levels (p<0.0001), but no statistic difference was observed in blood levels between groups, although it was verified similar results in rPER and Sham group. rPER technique also enhanced TEAC levels in both blood (p = 0.0314) and intestinal tissue (p = 0.0139), compared to IR group.

Conclusions:

rPER appears as the most promising technique to avoid IR injury. This technique reduced TBARS levels in blood and intestinal tissue and promoted the maintenance of antioxidant defense in mesenteric acute injury.

Effects of different ischemic preconditioning strategies on physiological and cellular mechanisms of intestinal ischemia/reperfusion injury: Implication from an isolated perfused rat small intestine model

Background

Intestinal ischemia/reperfusion (I/R)-injury often results in sepsis and organ failure and is of major importance in the clinic. A potential strategy to reduce I/R-injury is the application of ischemic preconditioning (IPC) during which repeated, brief episodes of I/R are applied. The aim of this study was to evaluate physiological and cellular effects of intestinal I/R-injury and to compare the influence of in-vivo IPC (iIPC) with ex-vivo IPC (eIPC), in which blood derived factors and nerval regulations are excluded.

Methods

Using an established perfused rat intestine model, effects of iIPC and eIPC on physiological as well as cellular mechanisms of I/R-injury (60 min hypoxia, 30 min reperfusion) were investigated. iIPC was applied by three reversible occlusions of the mesenteric artery in-vivo for 5 min followed by 5 min of reperfusion before isolating the small intestine, eIPC was induced by stopping the vascular perfusion ex-vivo 3 times for 5 min followed by 5 min of reperfusion after isolation of the intestine. Study groups (each N = 8–9 animals) were: iIPC, eIPC, I/R (iIPC group), I/R (eIPC group), iIPC+I/R, eIPC+I/R, no intervention/control (iIPC group), no intervention/control (eIPC group). Tissue morphology/damage, metabolic functions, fluid shifts and barrier permeability were evaluated. Cellular mechanisms were investigated using signaling arrays.

Results

I/R-injury decreased intestinal galactose uptake (iIPC group: p<0.001), increased vascular perfusion pressure (iIPC group: p<0.001; eIPC group: p<0.01) and attenuated venous flow (iIPC group: p<0.05) while lactate-to-pyruvate ratio (iIPC group, eIPC group: p<0.001), luminal flow (iIPC group: p<0.001; eIPC group: p<0.05), goblet cell ratio (iIPC group, eIPC group: p<0.001) and apoptosis (iIPC group, eIPC group: p<0.05) were all increased. Application of iIPC prior to I/R increased vascular galactose uptake (P<0.05) while eIPC had no significant impact on parameters of I/R-injury. On cellular level, I/R-injury resulted in a reduction of the phosphorylation of several MAPK signaling molecules. Application of iIPC prior to I/R increased phosphorylation of JNK2 and p38δ while eIPC enhanced CREB and GSK-3α/β phosphorylation.

Conclusion

Intestinal I/R-injury is associated with major physiological and cellular changes. However, the overall influence of the two different IPC strategies on the acute phase of intestinal I/R-injury is rather limited.

Recombinant angiopoietin-like protein 4 attenuates intestinal barrier structure and function injury after ischemia/reperfusion

BACKGROUND

Intestinal barrier breakdown, a frequent complication of intestinal ischemia-reperfusion (I/R) including dysfunction and the structure changes of the intestine, is characterized by a loss of tight junction and enhanced permeability of the intestinal barrier and increased mortality. To develop effective and novel therapeutics is important for the improvement of outcome of patients with intestinal barrier deterioration. Recombinant human angiopoietin-like protein 4 (rhANGPTL4) is reported to protect the blood-brain barrier when administered exogenously, and endogenous ANGPTL4 deficiency deteriorates radiation-induced intestinal injury.

AIM

To identify whether rhANGPTL4 may protect intestinal barrier breakdown induced by I/R.

METHODS

Intestinal I/R injury was elicited through clamping the superior mesenteric artery for 60 min followed by 240 min reperfusion. Intestinal epithelial (Caco-2) cells and human umbilical vein endothelial cells were challenged by hypoxia/ reoxygenation to mimic I/R in vitro.

RESULTS

Indicators including fluorescein isothiocyanate-conjugated dextran (4 kilodaltons; FD-4) clearance, ratio of phosphorylated myosin light chain/total myosin light chain, myosin light chain kinase and loss of zonula occludens-1, claudin-2 and VE-cadherin were significantly increased after intestinal I/R or cell hypoxia/reoxygenation. rhANGPTL4 treatment significantly reversed these indicators, which were associated with inhibiting the inflammatory and oxidative cascade, excessive activation of cellular autophagy and apoptosis and improvement of survival rate. Similar results were observed in vitro when cells were challenged by hypoxia/reoxygenation, whereas rhANGPTL4 reversed the indicators close to normal level in Caco-2 cells and human umbilical vein endothelial cells significantly.

CONCLUSION

rhANGPTL4 can function as a protective agent against intestinal injury induced by intestinal I/R and improve survival via maintenance of intestinal barrier structure and functions.

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.

Stem cells and exosomes: promising candidates for necrotizing enterocolitis therapy

Necrotizing enterocolitis (NEC) is a devastating disease predominately affecting neonates. Despite therapeutic advances, NEC remains the leading cause of mortality due to gastrointestinal conditions in neonates. Stem cells have been exploited in various diseases, and the application of different types of stem cells in the NEC therapy is explored in the past decade. However, stem cell transplantation possesses several deficiencies, and exosomes are considered potent alternatives. Exosomes, especially those derived from stem cells and breast milk, demonstrate beneficial effects for NEC both in vivo and in vitro and emerge as promising options for clinical practice. In this review, the function and therapeutic effects of stem cells and exosomes for NEC are investigated and summarized, which provide insights for the development and application of novel therapeutic strategies in pediatric diseases. Further elucidation of mechanisms, improvement in preparation, bioengineering, and administration, as well as rigorous clinical trials are warranted.

Cardioprotection by remote ischemic conditioning is transferable by plasma and mediated by extracellular vesicles

BACKGROUND

Remote ischemic conditioning (RIC) by brief periods of limb ischemia and reperfusion protects against ischemia-reperfusion injury. We studied the cardioprotective role of extracellular vesicles (EV)s released into the circulation after RIC and EV accumulation in injured myocardium.

METHODS

We used plasma from healthy human volunteers before and after RIC (pre-PLA and post-PLA) to evaluate the transferability of RIC. Pre- and post-RIC plasma samples were separated into an EV enriched fraction (pre-EV + and post-EV +) and an EV poor fraction (pre-EV- and post-EV-) by size exclusion chromatography. Small non-coding RNAs from pre-EV + and post-EV + were purified and profiled by NanoString Technology. Infarct size was compared in Sprague-Dawley rat hearts perfused with isolated plasma and fractions in a Langendorff model. In addition, fluorescently labeled EVs were used to assess homing in an in vivo rat model. (ClinicalTrials.gov, number: NCT03380663) RESULTS: Post-PLA reduced infarct size by 15% points compared with Pre-PLA (55 ± 4% (n = 7) vs 70 ± 6% (n = 8), p = 0.03). Post-EV + reduced infarct size by 16% points compared with pre-EV + (53 ± 15% (n = 13) vs 68 ± 12% (n = 14), p = 0.03). Post-EV- did not affect infarct size compared to pre-EV- (64 ± 3% (n = 15) and 68 ± 10% (n = 16), p > 0.99). Three miRNAs (miR-16-5p, miR-144-3p and miR-451a) that target the mTOR pathway were significantly up-regulated in the post-EV + group. Labelled EVs accumulated more intensely in the infarct area than in sham hearts.

CONCLUSION

Cardioprotection by RIC can be mediated by circulating EVs that accumulate in injured myocardium. The underlying mechanism involves modulation of EV miRNA that may promote cell survival during reperfusion.