Enteral nutrient deprivation in patients leads to a loss of intestinal epithelial barrier function

The Gut in Critical Illness

PURPOSE OF REVIEW

The purpose of this narrative review is to describe the mechanisms for gut dysfunction during critical illness, outline hypotheses of gut-derived inflammation, and identify nutrition and non-nutritional therapies that have direct and indirect effects on preserving both epithelial barrier function and gut microbiota during critical illness.

RECENT FINDINGS

Clinical and animal model studies have demonstrated that critical illness pathophysiology and interventions breach epithelial barrier function and convert a normally commensal gut microbiome into a pathobiome. As a result, the gut has been postulated to be the "motor" of critical illness and numerous hypotheses have been put forward to explain how it contributes to systemic inflammation and drives multiple organ failure. Strategies to ameliorate gut dysfunction have focused on maintaining gut barrier function and promoting gut microbiota commensalism. The trajectory of critical illness may be closely related to gut epithelial barrier function, the gut microbiome and interventions that may contribute towards a deleterious pathobiome with immune dysregulation.

Early Feeding in Critical Care - Where Are We Now?

The aim to avoid underfeeding has resulted in relative overfeeding of patients in the early phase of critical illness, worsening instead of improving outcomes. Negative randomised controlled trials have triggered mechanistic studies to investigate possible mechanisms explaining harm, allowing more scientific interpretation of many unexpected results during the last decades. Whereas individualized evidence-based approach to nutrition is still only rarely available, discussing and understanding of pathophysiological mechanisms should assist in decision-making in clinical practice. Further exploration of mechanisms of harm and benefit, as well as development of new technologies are needed to better plan future nutrition studies.

An Amino Acids and Dipeptide Injection Inhibits the TNF-α/HMGB1 Inflammatory Signaling Pathway to Reduce Pyroptosis and M1 Microglial Polarization in POCD Mice: the Gut to the Brain

Peripheral surgery-induced neural inflammation is a key pathogenic mechanism of postoperative cognitive dysfunction (POCD). However, the mechanism underlying neuroinflammation and associated neural injury remains elusive. Surgery itself can lead to gut damage, and the occurrence of POCD is accompanied by high levels of TNF-α in the serum and blood‒brain barrier (BBB) damage. Reductions in stress, inflammation and protein loss have been emphasized as strategies for enhanced recovery after surgery (ERAS). We designed an amino acids and dipeptide (AAD) formula for injection that could provide intestinal protection during surgery. Through the intraoperative infusion of AAD based on the ERAS concept, we aimed to explore the effect of AAD injection on POCD and its underlying mechanism from the gut to the brain. Here, we observed that AAD injection ameliorated neural injury in POCD, in addition to restoring the function of the intestinal barrier and BBB. We also found that TNF-α levels decreased in the ileum, blood and hippocampus. Intestinal barrier protectors and TNF-α inhibitors also alleviated neural damage. AAD injection treatment decreased HMGB1 production, pyroptosis, and M1 microglial polarization and increased M2 polarization. In vitro, AAD injection protected the impaired gut barrier and decreased TNF-α production, alleviating damage to the BBB by stimulating cytokine transport in the body. HMGB1 and Caspase-1 inhibitors decreased pyroptosis and M1 microglial polarization and increased M2 polarization to protect TNF-α-stimulated microglia in vitro. Collectively, these findings suggest that the gut barrier-TNF-α-BBB-HMGB1-Caspase-1 inflammasome-pyroptosis-M1 microglia pathway is a novel mechanism of POCD related to the gut-brain axis and that intraoperative AAD infusion is a potential treatment for POCD.

Reversing malnutrition and low muscle strength with targeted enteral feeding in patients awaiting liver transplant: A randomized controlled trial

BACKGROUND AND AIMS

Most patients with decompensated cirrhosis fail to meet their nutrition targets. The impact of nasogastric feeding (NGF) on malnutrition in cirrhosis remains unknown. This study aims to assess the impact of pretransplant NGF on pre-liver transplant and post-liver transplant outcomes.

APPROACH AND RESULTS

This single-center, prospective randomized controlled trial of 55 patients with severe malnutrition and low handgrip strength (HGS) compared a standard high-energy high-protein diet to diet plus supplemental nocturnal NGF while awaiting transplant. The primary outcome was a change in HGS. The median age was 58.5 years (IQR: 51.1-64), median MELD was 24 (20-28.5), and 32 (58%) patients were male. The median duration of NGF was 63.0 days (34.5-127), following which time the median between-group difference in HGS was 3.6 kg (95% CI: 1.7-5.2, p <0.001), an increase of 20% from baseline. Mid-upper-arm circumference, triceps skinfold, and immune function all increased significantly with NGF. Muscle and nutritional parameters continued to improve with increasing duration of feeding. NGF significantly increased daily energy intake between groups by 1285 kcal (95% CI: 860-1677) and protein intake by 51 g (95% CI: 32-71) (both p <0.001). All NGF patients met >100% of their measured nutritional requirements. Posttransplant clinical outcomes were similar between groups.

CONCLUSIONS

Targeted enteral feeding before liver transplant improves HGS, anthropometry, and immune function in severely malnourished patients with cirrhosis. These findings provide a strong rationale for early consideration of NGF to reverse malnutrition and improve muscle strength. Appropriately powered studies should explore whether NGF can also impact clinically relevant outcomes including pretransplant and posttransplant mortality.

Early versus delayed enteral nutrition in ICU patients with sepsis: a propensity score-matched analysis based on the MIMIC-IV database

Background

Early enteral nutrition (EN) is recommended for sepsis management, but its optimal timing and clinical benefits remain uncertain. This study evaluates whether early EN improves outcomes compared to delayed EN in patients with sepsis.

Methods

We analyzed data of septic patients from the MIMIC-IV 2.2 database, focusing on those in the Medical Intensive Care Unit (MICU) and Surgical Intensive Care Unit (SICU). Patients who initiated EN within 3 days were classified into the early EN group, while those who started EN between 3 and 7 days were classified into the delayed EN group. Propensity score matching was used to compare outcomes between the groups.

Results

Among 1,111 patients, 786 (70.7%) were in the early EN group and 325 (29.3%) were in the delayed EN group. Before propensity score matching, the early EN group demonstrated lower mortality (crude OR = 0.694; 95% CI: 0.514-0.936; p = 0.018) and shorter ICU stays (8.3 [5.2, 12.3] vs. 10.0 [7.5, 14.2] days; p < 0.001). After matching, no significant difference in mortality was observed. However, the early EN group had shorter ICU stays (8.3 [5.2, 12.4] vs. 10.1 [7.5, 14.2] days; p < 0.001) and a lower incidence of AKI stage 3 (49.3% vs. 55.5%; p = 0.030). Subgroup analysis revealed that early EN significantly reduced the 28-day mortality rate in sepsis patients with lactate levels ≤4 mmol/L, with an adjusted odds ratio (aOR) of 0.579 (95% CI: 0.361, 0.930; p = 0.024).

Conclusion

Early enteral nutrition may not significantly reduce overall mortality in sepsis patients but may shorten ICU stays and decrease the incidence of AKI stage 3. Further research is needed to identify specific patient characteristics that benefit most from early EN.

Gastrostomy Tubes: Indications, Types, and Care

Gastrostomy tube insertion has become a more common practice in pediatric patients. An increasing number of children both in health-care facilities and at home are relying on temporary or long-term enteral feeding. Gastrostomy tube placement can be accomplished by various methods and by a variety of specialists. Despite the overall safety of these procedures, both early and late complications can occur. It is important for pediatricians and pediatric subspecialists to be familiar with and aware of the indications, safety, and management of gastrostomies. This paper provides a comprehensive overview of the topic.

Role of gut microbes in acute lung injury/acute respiratory distress syndrome

Acute lung injury (ALI) is an acute, diffuse inflammatory lung condition triggered by factors of severe infections, trauma, shock, burns, ischemia-reperfusion, and mechanical ventilation. It is primarily characterized by refractory hypoxemia and respiratory distress. The more severe form, acute respiratory distress syndrome (ARDS), can progress to multi-organ failure and has a high mortality rate. Despite extensive research, the exact pathogenesis of ALI and ARDS remains complex and not fully understood. Recent advancements in studying the gut microecology of patients have revealed the critical role that gut microbes play in ALI/ARDS onset and progression. While the exact mechanisms are still under investigation, evidence increasingly points to the influence of gut microbes and their metabolites on ALI/ARDS. This review aims to summarize the role of gut microbes and their metabolites in ALI/ARDS caused by various triggers. Moreover, it explores potential mechanisms and discusses how gut microbe-targeting interventions might offer new clinical strategies for the treatment of ALI/ARDS.

The gut microbiome and intestinal failure-associated liver disease

Intestinal failure-associated liver disease (IFALD) is a common hepatobiliary complication resulting from long-term parenteral nutrition (PN) in patients with intestinal failure. The spectrum of IFALD ranges from cholestasis, steatosis, portal fibrosis, to cirrhosis. Development of IFALD is a multifactorial process, in which gut dysbiosis plays a critical role in its initiation and progression in conjunction with increased intestinal permeability, activation of hepatic immune responses, and administration of lipid emulsion. Gut microbiota manipulation including pre/probiotics, fecal microbiota transplantation, and antibiotics has been studied in IFALD with varying success. In this review, we summarize current knowledge on the taxonomic and functional changes of gut microbiota in preclinical and clinical studies of IFALD. We also review the function of microbial metabolites and associated signalings in the context of IFALD. By providing microbiota-targeted interventions aiming to optimize PN-induced liver injury, our review provides perspectives for future basic and translational investigations in the field.

Nutrition support and clinical outcomes following allogeneic stem cell transplantation

Nutrition support is frequently required post allogeneic stem cell transplantation (SCT) and while there is some evidence on the benefits of enteral nutrition (EN), parenteral nutrition (PN) is widely used in practice. The study aimed to examine the impact of EN versus PN on early outcomes following SCT. All patients who underwent allogeneic SCT over 2.5 years were included in the analysis. Data was retrospectively collected on mode of nutrition support with clinical outcome data obtained from an existing database. Clinical outcomes were compared between groups by logistic, poisson and negative binomial regression, with adjustment for baseline confounders as appropriate. Patients who received EN then changed to PN had a longer length of hospital stay compared to those who received EN only (IR 1.24, 95% CI: 1.11-1.38, p < 0.001). Compared to those who received EN only, patients who received EN that changed to PN or PN only had a longer time to neutrophil engraftment (IR 1.11, 95% CI: 1.02-1.20, p = 0.016 and IR 1.16, 95% CI: 1.03-1.30, p = 0.017) and platelet engraftment (IR 1.20, 95% CI 1.08-1.33, p < 0.001 and IR 1.24, 95% CI 1.08-1.42, p = 0.002). Enteral nutrition should be first line nutritional support for patients undergoing allogeneic SCT.

Early versus delayed enteral nutrition in mechanically ventilated patients with circulatory shock: a nested cohort analysis of an international multicenter, pragmatic clinical trial

Introduction

Real-world evidence on the timing and efficacy of enteral nutrition (EN) practices in intensive care unit (ICU) patients with circulatory shock is limited. We hypothesized early EN (EEN), as compared to delayed EN (DEN), is associated with improved clinical outcomes in mechanically ventilated (MV) patients with circulatory shock.

Methods

We analyzed a dataset from an international, multicenter, pragmatic randomized clinical trial (RCT) evaluating protein dose in ICU patients. Data were collected from ICU admission, and EEN was defined as initiating < 48 h from ICU admission and DEN > 48 h. We identified MV patients in circulatory shock to evaluate the association between the timing of EN initiation and clinical outcomes. The regression analysis model controlled for age, mNUTRIC score, APACHE II score, sepsis, and Site.

Results

We included 626 patients, from 52 ICUs in 14 countries. Median age was 60 years [18–93], 55% had septic shock, 99% received norepinephrine alone, 91% received EN alone, and 50.3% were randomized to a usual protein dose. Forty-two percent of EEN patients had persistent organ dysfunction syndrome plus death at day 28, compared to 53% in the DEN group (p = 0.04). EEN was associated with more ICU-free days (9.3 ± 9.2 vs. 5.7 ± 7.9, p = 0.0002), more days alive and free of vasopressors (7.1 ± 3.1 vs. 6.3 ± 3.2, p = 0.007), and shorter duration of MV among survivors (9.8 ± 10.9 vs. 13.8 ± 14.5, p = 0.0002). This trend was no longer observed in the adjusted analysis. There were no differences in ICU/60-day mortality or feeding intolerance rates between groups.

Conclusion

In MV patients with circulatory shock, EEN, as compared to DEN, was associated with improved clinical outcomes, but no longer when adjusting for illness severity. RCTs comparing the efficacy of EEN to DEN in MV patients with circulatory shock are warranted.

The central and biodynamic role of gut microbiota in critically ill patients

Gut microbiota plays an essential role in health and disease. It is constantly evolving and in permanent communication with its host. The gut microbiota is increasingly seen as an organ, and its failure, reflected by dysbiosis, is seen as an organ failure associated with poor outcomes. Critically ill patients may have an altered gut microbiota, namely dysbiosis, with a severe reduction in "health-promoting" commensal intestinal bacteria (such as Firmicutes or Bacteroidetes) and an increase in potentially pathogenic bacteria (e.g. Proteobacteria). Many factors that occur in critically ill patients favour dysbiosis, such as medications or changes in nutrition patterns. Dysbiosis leads to several important effects, including changes in gut integrity and in the production of metabolites such as short-chain fatty acids and trimethylamine N-oxide. There is increasing evidence that gut microbiota and its alteration interact with other organs, highlighting the concept of the gut-organ axis. Thus, dysbiosis will affect other organs and could have an impact on the progression of critical diseases. Current knowledge is only a small part of what remains to be discovered. The precise role and contribution of the gut microbiota and its interactions with various organs is an intense and challenging research area that offers exciting opportunities for disease prevention, management and therapy, particularly in critical care where multi-organ failure is often the focus. This narrative review provides an overview of the normal composition of the gut microbiota, its functions, the mechanisms leading to dysbiosis, its consequences in an intensive care setting, and highlights the concept of the gut-organ axis.

Enteral feeding, even when the gut does not feel very good?

PURPOSE OF REVIEW

To summarize knowledge on the gut function in relation to enteral nutrition.

RECENT FINDINGS

The gut is certainly suffering during critical illness but our understanding of the exact mechanisms involved is limited. Physicians at bedside are lacking tools to identify how well or bad the gut is doing and whether the gut is responding adequately to critical illness. Sensing nutrition as a signal is important for the gut and microbiome. Enteral nutrition has beneficial effects for the gut perfusion and function. However, early full enteral nutrition in patients with shock was associated with an increased number of rare but serious complications.

SUMMARY

Whenever synthesizing knowledge in physiology and available evidence in critically ill, we suggest that enteral nutrition has beneficial effects but may turn harmful if provided too aggressively. Contraindications to enteral nutrition are listed in recent guidelines. For patients with gastrointestinal dysfunction but without these contraindications, we suggest considering early enteral nutrition as a signal to the gut and to the body rather than an energy and protein provision. With this rationale, we think that low dose of enteral nutrition could and probably should be provided also when the gut does not feel very good. Understanding the feedback from the gut in response to enteral nutrition would be important, however, monitoring tools are currently limited to clinical assessment only.

Gut-Lung Crosstalk in Sepsis-Induced Acute Lung Injury

Acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) are common acute and severe cases of the respiratory system with complicated pathogenesis and high mortality. Sepsis is the leading indirect cause of ALI/ARDS in the intensive care unit (ICU). The pathogenesis of septic ALI/ARDS is complex and multifactorial. In the development of sepsis, the disruption of the intestinal barrier function, the alteration of gut microbiota, and the translocation of the intestinal microbiome can lead to systemic and local inflammatory responses, which further alter the immune homeostasis in the systemic environment. Disruption of homeostasis may promote and propagate septic ALI/ARDS. In turn, when ALI occurs, elevated levels of inflammatory cytokines and the shift of the lung microbiome may lead to the dysregulation of the intestinal microbiome and the disruption of the intestinal mucosal barrier. Thus, the interaction between the lung and the gut can initiate and potentiate sepsis-induced ALI/ARDS. The gut–lung crosstalk may be a promising potential target for intervention. This article reviews the underlying mechanism of gut-lung crosstalk in septic ALI/ARDS.

Gastrointestinal manifestations and possible mechanisms of COVID-19 in different periods

Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, has become a pandemic worldwide. Although COVID-19 mainly affects the respiratory system, gastrointestinal (GI) manifestations have been frequently reported in such cases, even as initial symptoms. There have been several studies on different GI manifestations in patients with mild and severe disease or in remission. In this review article we summarized different GI manifestations of COVID-19 at various disease stages and the possible mechanisms based on published literatures, as well as the significance of GI manifestations in systemic inflammatory injury.

Fiber in the ICU: Should it Be a Regular Part of Feeding?

PURPOSE OF REVIEW

To highlight the controversy of fiber use in the current critical care nutrition guidelines; review the effect of fiber on the gut microbiota in the critically ill; and examine the data on fiber and outcomes in the intensive care setting.

RECENT FINDINGS

Fiber is increasingly recognized as a necessary component of colonic health and nutrition support. In critical illness there is a shift toward gut dysbiosis and immune dysregulation. Through fermentation and the generation of short-chain fatty acids, fiber has a role in maintaining intestinal homeostasis, immune function, and supporting commensal bacteria. In contrast to fermentable fiber, recent animal models suggest that non-fermentable fiber can also favorably alter intestinal homeostasis in a mechanism distinct from short chain fatty acids. In the critically ill, RCTs and meta-analyses suggest that soluble and mixed fiber supplemented enteral nutrition can reduce diarrhea and is well tolerated. Based on limited data, there may be benefits in reducing length of hospital stay, certain infections, and glucose metabolism. Nonetheless, the role of fiber enriched nutrition in critically ill patients is controversial as evident in the conflicting guidelines. Despite shortcomings in the literature, soluble and mixed fiber supplemented enteral nutrition is safe and beneficial in most hemodynamically stable intensive care patients. More research is necessary to determine optimal fiber composition.

Opportunities and Challenges for Gut Microbiota in Acute Leukemia

Acute leukemia (AL) is a highly heterogeneous hematologic malignancy, and although great progress has been made in the treatment of AL with allogeneic hematopoietic stem cell transplantation (Allo-HSCT) and new targeted drugs, problems such as infection and GVHD in AL treatment are still serious. How to reduce the incidence of AL, improve its prognosis and reduce the side effects of treatment is a crucial issue. The gut microbiota plays an important role in regulating disease progression, pathogen colonization, and immune responses. This article reviews recent advances in the gut microbiota and AL pathogenesis, infection, treatment and its role in allo-HSCT.

A clinical approach to acute mesenteric ischemia

PURPOSE OF REVIEW

To summarize current evidence on acute mesenteric ischemia (AMI) in critically ill patients, addressing pathophysiology, definition, diagnosis and management.

RECENT FINDINGS

A few recent studies showed that a multidiscipliary approach in specialized centers can improve the outcome of AMI. Such approach incorporates current knowledge in pathophysiology, early diagnosis with triphasic computed tomography (CT)-angiography, immediate endovascular or surgical restoration of mesenteric perfusion, and damage control surgery if transmural bowel infarction is present. No specific biomarkers are available to detect early mucosal injury in clinical setting. Nonocclusive mesenteric ischemia presents particular challenges, as the diagnosis based on CT-findings as well as vascular management is more difficult; some recent evidence suggests a possible role of potentially treatable stenosis of superior mesenteric artery and beneficial effect of vasodilator therapy (intravenous or local intra-arterial). Medical management of AMI is supportive, including aiming of euvolemia and balanced systemic oxygen demand/delivery. Enteral nutrition should be withheld during ongoing ischemia-reperfusion injury and be started at low rate after revascularization of the (remaining) bowel is convincingly achieved.

SUMMARY

Clinical suspicion leading to tri-phasic CT-angiography is a mainstay for diagnosis. Diagnosis of nonocclusive mesenteric ischemia and early intestinal injury remains challenging. Multidisciplinary team effort may improve the outcome of AMI.

Nutrition in the Neurocritical Care Unit: a New Frontier

PURPOSE OF REVIEW

This review presents the most current recommendations for providing nutrition to the neurocritical care population. This includes updates on initiation of feeding, immunonutrition, and metabolic substrates including ketogenic diet, cerebral microdialysis (CMD) monitoring, and the microbiome.

RECENT FINDINGS

Little evidence exists to support differences in feeding practices among the neurocritical care population. New areas of interest with limited data include use of immunonutrition, pre/probiotics for microbiome manipulation, ketogenic diet, and use of CMD catheters for substrate utilization monitoring.

SUMMARY

Acute neurologic injury incites a cascade of adrenergic and neuroendocrine events resulting in a pro-inflammatory and hypercatabolic state, which is associated with an increase in morbidity and mortality. Nutritional support provides substrates to mitigate the damaging effects of hypermetabolism. Despite this practice, studies on feeding delivery outcomes remain inconsistent. Guidelines suggest use of early enteral nutrition using standard polymeric formulas. Population heterogeneity, variability in interventions, complexities of the metabolic and inflammatory responses, and paucity of nutrition research in patients requiring neurocritical care have led to controversies in the field. It is imperative that more pragmatic and reproducible research be conducted to better understand underlying pathophysiology and develop interventions that may improve outcomes.

Nutritional Management of Acute Pancreatitis

Acute pancreatitis (AP) remains among the most common gastrointestinal disorders leading to hospital admission. Optimizing nutritional support and maintaining gut function is instrumental in recovery of patients with AP. Enteral nutrition remains one of the only interventions with demonstrated mortality benefit in AP largely through preservation of gut function, serving to preserve the gut barrier as means to mitigate immune dysregulation and systemic inflammation inherent to AP. Practice variation remains in timing, route, and composition of nutritional support. This review highlights contemporary evidence regarding optimal nutritional support in AP and provides recommendations for management in line with current consensus opinions.

[Intestine morphology and microbiocenosis changes in critically ill patients in neurosurgery]

In recent years, the effect of critical conditions on intestine and the role of such changes in maintenance and progression of systemic disorders are of particular attention. This issue is relevant in critically ill neurosurgical patients too. Intestine morphology and microbiome changes in these patients represent a wide field for researches in intensive care and prevention of secondary damage to other organs and systems. This review ensures a current approach to the problem of intestine morphology and microbiome changes in critically ill neurosurgical patients. We reviewed the data from clinical studies and experiments reproducing a critical condition in animals. Most publications are indexed in the PubMed, e-library, Google Scholar databases. We also analyzed the data from NEJM, JAMA, Lancet, Critical Care and other issues. The manuscript contains an overview of 44 foreign and 13 domestic references; over 50% of researches were published within the past 5 years. Searching depth was over 50 years.

Small Bowel Resection Increases Paracellular Gut Barrier Permeability via Alterations of Tight Junction Complexes Mediated by Intestinal TLR4

BACKGROUND

Short bowel syndrome resulting from small bowel resection (SBR) is associated with significant morbidity and mortality. Many adverse sequelae including steatohepatitis and bacterial overgrowth are thought to be related to increased bacterial translocation, suggesting alterations in gut permeability. We hypothesized that after intestinal resection, the intestinal barrier is altered via toll-like receptor 4 (TLR4) signaling at the intestinal level.

METHODS

B6 and intestinal-specific TLR4 knockout (iTLR4 KO) mice underwent 50% SBR or sham operation. Transcellular permeability was evaluated by measuring goblet cell associated antigen passages via two-photon microscopy. Fluorimetry and electron microscopy evaluation of tight junctions (TJ) were used to assess paracellular permeability. In parallel experiments, single-cell RNA sequencing measured expression of intestinal integral TJ proteins. Western blot and immunohistochemistry confirmed the results of the single-cell RNA sequencing.

RESULTS

There were similar number of goblet cell associated antigen passages after both SBR and sham operation (4.5 versus 5.0, P > 0.05). Fluorescein isothiocyanate-dextran uptake into the serum after massive SBR was significantly increased compared with sham mice (2.13 ± 0.39 ng/μL versus 1.62 ± 0.23 ng/μL, P < 0.001). SBR mice demonstrated obscured TJ complexes on electron microscopy. Single-cell RNA sequencing revealed a decrease in TJ protein occludin (21%) after SBR (P < 0.05), confirmed with immunostaining and western blot analysis. The KO of iTLR4 mitigated the alterations in permeability after SBR.

CONCLUSIONS

Permeability after SBR is increased via changes at the paracellular level. However, these alterations were prevented in iTLR4 mice. These findings suggest potential protein targets for restoring the intestinal barrier and obviating the adverse sequelae of short bowel syndrome.

Site-specific contribution of Toll-like receptor 4 to intestinal homeostasis and inflammatory disease

Toll-like receptor 4 (TLR4) is a highly conserved protein of innate immunity, responsible for the regulation and maintenance of homeostasis, as well as immune recognition of external and internal ligands. TLR4 is expressed on a variety of cell types throughout the gastrointestinal tract, including on epithelial and immune cell populations. In a healthy state, epithelial cell expression of TLR4 greatly assists in homeostasis by shaping the host microbiome, promoting immunoglobulin A production, and regulating follicle-associated epithelium permeability. In contrast, immune cell expression of TLR4 in healthy states is primarily centred on the maturation of dendritic cells in response to stimuli, as well as adequately priming the adaptive immune system to fight infection and promote immune memory. Hence, in a healthy state, there is a clear distinction in the site-specific roles of TLR4 expression. Similarly, recent research has indicated the importance of site-specific TLR4 expression in inflammation and disease, particularly the impact of epithelial-specific TLR4 on disease progression. However, the majority of evidence still remains ambiguous for cell-specific observations, with many studies failing to provide the distinction of epithelial versus immune cell expression of TLR4, preventing specific mechanistic insight and greatly impacting the translation of results. The following review provides a critical overview of the current understanding of site-specific TLR4 activity and its contribution to intestinal/immune homeostasis and inflammatory diseases.

Nutrition Support and the Gastrointestinal Microbiota: A Systematic Review

BACKGROUND

Low microbial diversity or altered microbiota composition is associated with many disease states. In the treatment of many conditions, enteral (EN) or parenteral (PN) nutrition is frequently required.

OBJECTIVE

This systematic review aimed to identify and evaluate the evidence of the effect of EN vs PN on the gastrointestinal microbiota.

METHOD

A comprehensive systematic literature search of 5 databases was completed to review studies published until February 2020. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines were utilized in completion of the review with the Academy of Nutrition and Dietetics quality criteria checklist and Grading of Recommendations Assessment, Development and Evaluation to evaluate the included studies. The review was registered on PROSPERO (CRD42018091328). Studies were eligible for inclusion if participants were older than 3 years, patients received either EN, PN or both, with some patients receiving each mode of nutrition support. The main outcome was any assessment of the gastrointestinal microbiota, including diversity or taxa abundance.

RESULTS

Eleven articles (n = 367 patients) met the inclusion criteria and were evaluated. Seven studies (n = 237) reported greater abundance of Proteobacteria with the provision of PN compared to EN; 6 studies (n = 172) reported lower Firmicutes and 5 studies (n = 155) lower Bacteroidetes. In 7 studies (n = 282), microbial diversity was lower with provision of PN than EN. The Grading of Recommendations Assessment, Development and Evaluation certainty of evidence was very low.

CONCLUSIONS

Provision of PN may lead to greater abundance of Proteobacteria and reduced microbial diversity; however, there is limited literature on this topic and additional research is warranted to improve understanding of the impact of EN vs PN on the microbiota.

Microbiota-based approaches to mitigate infectious complications of intensive chemotherapy in patients with acute leukemia

Despite advances in antimicrobial treatments, infection remains a common complication of intensive chemotherapy in patients with acute leukemia. It has become progressively apparent that the current antimicrobial focus has shortcomings that result from disruption of the commensal microbial communities of the gut. These effects, collectively known as dysbiosis, have been increasingly associated worldwide with growing complications such as Clostridioides difficile infection, systemic infections, and antibiotic resistance. A revision of the current practice is overdue. Several innovative concepts have been proposed and tested in animal models and humans, with the overarching goal of preventing damage to the microbiota and facilitating its recovery. In this review, we discuss these approaches, examine critical knowledge gaps, and explore how they may be filled in future research.

Percutaneous endoscopic gastrostomy – Too often? Too late? Who are the right patients for gastrostomy?

Percutaneous endoscopic gastrostomy is an established method to provide nutrition to patients with restricted oral uptake of fluids and calories. Here, we review the methods, indications and complications of this procedure. While gastrostomy can be safely and easily performed during gastroscopy, the right patients and timing for this intervention are not always chosen. Especially in patients with dementia, the indication for and timing of gastrostomies are often improper. In this patient group, clear data for enteral nutrition are lacking; however, some evidence suggests that patients with advanced dementia do not benefit, whereas patients with mild to moderate dementia might benefit from early enteral nutrition. Additionally, other patient groups with temporary or permanent restriction of oral uptake might be a useful target population for early enteral nutrition to maintain mobilization and muscle strength. We plead for a coordinated study program for these patient groups to identify suitable patients and the best timing for tube implantation.

Novel Strategies to Prevent Total Parenteral Nutrition-Induced Gut and Liver Inflammation, and Adverse Metabolic Outcomes

Total parenteral nutrition (TPN) is a life-saving therapy administered to millions of patients. However, it is associated with significant adverse effects, namely liver injury, risk of infections, and metabolic derangements. In this review, the underlying causes of TPN-associated adverse effects, specifically gut atrophy, dysbiosis of the intestinal microbiome, leakage of the epithelial barrier with bacterial invasion, and inflammation are first described. The role of the bile acid receptors farnesoid X receptor and Takeda G protein-coupled receptor, of pleiotropic hormones, and growth factors is highlighted, and the mechanisms of insulin resistance, namely the lack of insulinotropic and insulinomimetic signaling of gut-originating incretins as well as the potentially toxicity of phytosterols and pro-inflammatory fatty acids mainly released from soybean oil-based lipid emulsions, are discussed. Finally, novel approaches in the design of next generation lipid delivery systems are proposed. Propositions include modifying the physicochemical properties of lipid emulsions, the use of lipid emulsions generated from sustainable oils with favorable ratios of anti-inflammatory n-3 to pro-inflammatory n-6 fatty acids, beneficial adjuncts to TPN, and concomitant pharmacotherapies to mitigate TPN-associated adverse effects.

Gastrointestinal dysfunction in the critically ill: a systematic scoping review and research agenda proposed by the Section of Metabolism, Endocrinology and Nutrition of the European Society of Intensive Care Medicine

BACKGROUND

Gastrointestinal (GI) dysfunction is frequent in the critically ill but can be overlooked as a result of the lack of standardization of the diagnostic and therapeutic approaches. We aimed to develop a research agenda for GI dysfunction for future research. We systematically reviewed the current knowledge on a broad range of subtopics from a specific viewpoint of GI dysfunction, highlighting the remaining areas of uncertainty and suggesting future studies.

METHODS

This systematic scoping review and research agenda was conducted following successive steps: (1) identify clinically important subtopics within the field of GI function which warrant further research; (2) systematically review the literature for each subtopic using PubMed, CENTRAL and Cochrane Database of Systematic Reviews; (3) summarize evidence for each subtopic; (4) identify areas of uncertainty; (5) formulate and refine study proposals that address these subtopics; and (6) prioritize study proposals via sequential voting rounds.

RESULTS

Five major themes were identified: (1) monitoring, (2) associations between GI function and outcome, (3) GI function and nutrition, (4) management of GI dysfunction and (5) pathophysiological mechanisms. Searches on 17 subtopics were performed and evidence summarized. Several areas of uncertainty were identified, six of them needing consensus process. Study proposals ranked among the first ten included: prevention and management of diarrhoea; management of upper and lower feeding intolerance, including indications for post-pyloric feeding and opioid antagonists; acute gastrointestinal injury grading as a bedside tool; the role of intra-abdominal hypertension in the development and monitoring of GI dysfunction and in the development of non-occlusive mesenteric ischaemia; and the effect of proton pump inhibitors on the microbiome in critical illness.

CONCLUSIONS

Current evidence on GI dysfunction is scarce, partially due to the lack of precise definitions. The use of core sets of monitoring and outcomes are required to improve the consistency of future studies. We propose several areas for consensus process and outline future study projects.

Acute Pancreatitis: Exploring Nutrition Implications

Diseases of the pancreas vary by type, etiology, pathophysiology, and outcomes. One of the principle therapeutic considerations in all types of pancreatic diseases is nutrition. This review will consider acute pancreatitis (AP). Choice of patient, type and composition of nutrition, and timing of initiation will be discussed as components for achieving the maximum benefits of nutrition therapy in AP. The paradigm of nutrition therapy in AP has shifted to early enteral and/or oral nutrition based on disease severity to help mitigate the underlying inflammatory cascade of events leading to AP, beginning with anatomic and functional intestinal changes. Additionally, newer research investigating the inflammatory changes that instigate, maintain, and propagate AP will be discussed in terms of the nutrition effects on systemic inflammation. Nutrition therapy can mitigate the inflammatory changes in the intestinal tract and help with intestinal motility, bacterial overgrowth and translocation. It can help maintain intestinal bacterial composition and abundance similar to predisease levels. This review will also discuss the changes in the intestinal microbiome and effects of probiotics in AP.

Central line associated blood stream infections in gastroschisis patients: A nationwide database analysis of risks, outcomes, and disparities

PURPOSE

The aim of this study was to determine the risk of central line associated blood-stream infections (CLABSI) in neonatal gastroschisis patients, risk factors, outcomes, and financial implications.

METHODS

The 2016 Healthcare Cost and Utilization Project (HCUP)'s kid's inpatient database (KID), a national database of pediatric inpatient admissions across the United States, was used to obtain a large sample of gastroschisis admissions. Incidence of CLABSI in the gastroschisis patient population was compared to the incidence of CLABSI in the database. To further study the factors influencing CLABSI in gastroschisis, demographic and clinical features of patients were analyzed. Categorical variables were analyzed using Fisher's exact test or Pearson's chi-squared test. Odds ratios (OR) with 95% confidence intervals (CI) for variables found to have significance (p < 0.05) were calculated.

FINDINGS

Incidence of CLABSI in this database for pediatric inpatients was 4449 out of 298,862 central line insertions [1.48%] and was 81 out of 2032 [3.9%] (OR 2.83, 95% CI 2.26-3.54, p < 0.001) in the gastroschisis cohort. African American neonates had a significantly higher risk of CLABSI with gastroschisis. Prematurity and low birth-weight in gastroschisis were protective from CLABSI, along with patients from suburban areas or admitted in the Southern USA. Average costs were greater in gastroschisis patients with CLABSI, increasing from $281,779 to $421,970 (p = 0.008). The average length of stay increased from 31 days to 38 days with a CLABSI (p < 0.001).

CONCLUSIONS

In gastroschisis patients, CLABSI incidence is high and adds great morbidity and expense. For uncertain reasons, premature and low birth weight babies appear to be protected.

LEVEL OF EVIDENCE

Level III.

The Importance of the Microbiome in Critically Ill Patients: Role of Nutrition

Critically ill patients have an alteration in the microbiome in which it becomes a disease-promoting pathobiome. It is characterized by lower bacterial diversity, loss of commensal phyla, like Firmicutes and Bacteroidetes, and a domination of pathogens belonging to the Proteobacteria phylum. Although these alterations are multicausal, many of the treatments administered to these patients, like antibiotics, play a significant role. Critically ill patients also have a hyperpermeable gut barrier and dysregulation of the inflammatory response that favor the development of the pathobiome, translocation of pathogens, and facilitate the emergence of sepsis. In order to restore the homeostasis of the microbiome, several nutritional strategies have been evaluated with the aim to improve the management of critically ill patients. Importantly, enteral nutrition has proven to be more efficient in promoting the homeostasis of the gut microbiome compared to parenteral nutrition. Several nutritional therapies, including prebiotics, probiotics, synbiotics, and fecal microbiota transplantation, are currently being used, showing variable results, possibly due to the unevenness of clinical trial conditions and the fact that the beneficial effects of probiotics are specific to particular species or even strains. Thus, it is of great importance to better understand the mechanisms by which nutrition and supplement therapies can heal the microbiome in critically ill patients in order to finally implement them in clinical practice with optimal safety and efficacy.

Pilot study investigating the effect of enteral and parenteral nutrition on the gastrointestinal microbiome post-allogeneic transplantation

Nutrition support is frequently required post-allogeneic haematopoietic progenitor cell transplantation (HPCT); however, the impact of mode of feeding on the gastrointestinal microbiome has not been explored. This study aimed to determine if there is a difference in the microbiome between patients receiving enteral nutrition (EN) and parenteral nutrition (PN) post-allogeneic HPCT. Twenty-three patients received either early EN or PN when required. Stool samples were collected at 30 days post-transplant and analysed with shotgun metagenomic sequencing. There was no difference in microbial diversity between patients who received predominantly EN (n = 13) vs. PN (n = 10) however patients who received predominantly EN had greater abundance of Faecalibacterium (P < 0·001) and ruminococcus E bromii (P = 0·026). Patients who had minimal oral intake for a longer duration during provision of nutrition support had a different overall microbial profile (P = 0·044), lower microbial diversity (P = 0·004) and lower abundance of faecalibacterium prausnitzii_C (P = 0·030) and Blautia (P = 0·007) compared to patients with greater oral intake. Lower microbial diversity was found in patients who received additional beta lactam antibiotics (P = 0·042) or had a longer length of hospital stay (P = 0·019). Post-HPCT oral intake should be encouraged to maintain microbiota diversity and, if nutrition support is required, EN may promote a more optimal microbiota profile.

Liver Inflammation Relates to Decreased Canalicular Bile Transporter Expression in Pediatric Onset Intestinal Failure

OBJECTIVE

Although liver disease is a major complication of parenteral nutrition (PN) for intestinal failure (IF), its pathogenesis remains unclear. We investigated potential molecular mechanisms of liver injury in pediatric onset IF.

METHODS

Liver expression of canalicular phospholipid (ABCB4), bile acid (ABCB11), and sterol (ABCG5/8) transporters, their upstream regulators LXR and FXR as well as pro-inflammatory cytokines interleukin-6 (IL6) and tumor necrosis factor (TNF) were investigated among patients with IF [age median 3.8 (IQR 1.2 to 11)] in relation to biochemical and histologic liver injury, PN, serum plant sterols, fibroblast growth factor 19, and α-tocopherol.

RESULTS

Patients receiving PN currently (n = 18) showed more advanced liver injury than patients after weaning off PN (n = 30). Histologic portal inflammation strongly segregated PN-dependent (44%) from weaned off patients (3%, P = 0.001) and coupled with progression of cholestasis and liver fibrosis. Patients with portal inflammation demonstrated markedly induced liver RNA expression of IL6 and TNF, repression of FXR and its canalicular bile transporter target gene RNA expression, including ABCB4 and ABCB11 as well as decreased protein expression of ABCB11 and ABCB4. Furthermore, upregulation of LXR and ABCG5/8 RNA expression was suppressed in patients with portal inflammation. Current PN, increased serum levels of plant sterols stigmasterol, avenasterol, and sitosterol along with serum citrulline, a marker of enterocyte mass, predicted portal inflammation.

CONCLUSIONS

In pediatric onset IF, current PN delivery synergistically with intestinal compromise promote liver inflammation, which associates with progression of biochemical and histologic liver injury, while reducing expression of canalicular bile transporters.

Leaky gut: mechanisms, measurement and clinical implications in humans

The objectives of this review on 'leaky gut' for clinicians are to discuss the components of the intestinal barrier, the diverse measurements of intestinal permeability, their perturbation in non-inflammatory 'stressed states' and the impact of treatment with dietary factors. Information on 'healthy' or 'leaky' gut in the public domain requires confirmation before endorsing dietary exclusions, replacement with non-irritating foods (such as fermented foods) or use of supplements to repair the damage. The intestinal barrier includes surface mucus, epithelial layer and immune defences. Epithelial permeability results from increased paracellular transport, apoptosis or transcellular permeability. Barrier function can be tested in vivo using orally administered probe molecules or in vitro using mucosal biopsies from humans, exposing the colonic mucosa from rats or mice or cell layers to extracts of colonic mucosa or stool from human patients. Assessment of intestinal barrier requires measurements beyond the epithelial layer. 'Stress' disorders such as endurance exercise, non-steroidal anti-inflammatory drugs administration, pregnancy and surfactants (such as bile acids and dietary factors such as emulsifiers) increase permeability. Dietary factors can reverse intestinal leakiness and mucosal damage in the 'stress' disorders. Whereas inflammatory or ulcerating intestinal diseases result in leaky gut, no such disease can be cured by simply normalising intestinal barrier function. It is still unproven that restoring barrier function can ameliorate clinical manifestations in GI or systemic diseases. Clinicians should be aware of the potential of barrier dysfunction in GI diseases and of the barrier as a target for future therapy.

Longitudinal changes in the gut microbiome of infants on total parenteral nutrition

BACKGROUND

Animal studies suggest that total parenteral nutrition (TPN) may alter bacterial colonization of the intestinal tract and contribute to complications. Progressive changes in gut microbiome of infants receiving TPN are not well understood.

METHODS

Infants with and without TPN/soy lipid were enrolled in a prospective, longitudinal study. Weekly fecal samples were obtained for the first 4 weeks of life. High throughput pyrosequencing of 16S rDNA was used for compositional analysis of the gut microbiome.

RESULTS

47 infants were eligible for analyses, 25 infants received TPN, and 22 infants did not (control). Although similar between TPN and control groups in the first week, fecal bacterial alpha diversity was significantly lower in the TPN group compared to controls at week 4 (Shannon index 1.0 vs 1.5, P-value = 0.03). The TPN group had significantly lower Bacteroidetes and higher Verrucomicrobia abundance compared to controls (P-values < 0.05), and these differences became more pronounced over time. At the genus level, TPN was associated with lower abundance of Bacteroides and Bifidobacterium in all weeks.

CONCLUSIONS

TPN is associated with significant loss of biodiversity and alterations in the pattern of gut microbial colonization of infants over time. TPN-associated dysbiosis may predispose infants to adverse NICU outcomes.

Modified enhanced recovery after surgery protocols are beneficial for postoperative recovery for patients undergoing emergency surgery for obstructive colorectal cancer: A propensity score matching analysis

Enhanced recovery after surgery (ERAS) is acknowledged to reduce perioperative stress in several surgical diseases. Here, we investigated whether modified ERAS is associated with beneficial effects in the setting of emergency colorectal surgery.We retrospectively evaluated the medical records of 839 consecutive patients with obstructive colorectal cancer undergoing surgical intervention at 4 institutes. Among them, 356 cases were managed with a multidisciplinary team approach to care (modified ERAS protocols), and the remaining 483 cases were treated based on traditional protocols. According to modified ERAS or traditional care, propensity score (PS) matching was performed to adjust biases in patient selection. The primary outcome was gastrointestinal function recovery. Secondary outcomes included postoperative complications and length of hospital stay.Modified ERAS was associated with postoperative gastrointestinal function recovery, including time to first flatus (P = .002), first defecation (P = .008), and prolonged ileus (P = .016). According to the Clavien-Dindo classification, fewer total episodes of grade II or higher postoperative complications were observed in patients cared for with modified ERAS than in patients with traditional care (P = .002). Median (interquartile range) postoperative hospital stay in the modified ERAS group was 6 (3-22) days versus 9 (7-27) days in the traditional care group (P < .001). Furthermore, the interval from operation to postoperative chemotherapy (d) was significantly shorter in the modified ERAS group (35.6 ± 11.5 vs 47.6 ± 23.8, P < .001).The modified ERAS was safe and associated with clinical benefits, including fast recovery of bowel function, reduced postoperative complications, and shorter hospital stay for patients with obstructive colorectal cancer.

Association Between Low Plasma Level of Citrulline Before Allogeneic Hematopoietic Cell Transplantation and Severe Gastrointestinal Graft vs Host Disease

BACKGROUND & AIMS

The gastrointestinal form of acute graft vs host disease increases morbidity and mortality following allogeneic hematopoietic cell transplantation. Plasma levels of citrulline, a non-proteinogenic amino acid, indicate functional enterocyte mass. We measured citrulline in patients before allogeneic hematopoietic cell transplantation and investigated its association with incidence and severity of gastrointestinal graft vs host disease.

METHODS

We performed a retrospective study with 191 patients (69 women, 122 men; median age of 52 years) who underwent allogeneic hematopoietic cell transplantation for hematological malignancies at a tertiary center of France from January 2013 through April 2015. Levels of citrulline in plasma samples collected 30 days before graft infusion were measured by high performance liquid chromatography with tandem mass spectrometry. We assigned patients to groups with a high level of citrulline (>26 μmol/L) or low level of citrulline (≤26 μmol/L). The primary outcomes were difference between groups in incidence of stage 2-4 gastrointestinal graft vs host disease, death without hematological disease relapse (non-relapse mortality), relapse of the hematological disease, and overall survival through 2 years after transplantation.

RESULTS

Ninety-six patients (50%) developed acute graft vs host disease and 37 (19%) developed a gastrointestinal form. Among patients with gastrointestinal involvement, 33 patients (89%) had stage 2-4 gastrointestinal graft vs host disease. In univariable analysis, low level of citrulline associated with higher cumulative incidence of stage 2-4 gastrointestinal graft vs host disease, non-relapse mortality, and shorter overall survival. In multivariable analysis, low level of citrulline was the only risk factor independently associated with stage 2-4 gastrointestinal graft vs host disease (hazard ratio, 3.06; 95% CI, 1.37-6.85; P = .007); it also associated with increased non-relapse mortality (hazard ratio, 2.29; 95% CI, 1.24-4.22; P = .008).

CONCLUSIONS

In a retrospective study with 191 patients, we associated a low plasma level of citrulline before allogeneic hematopoietic cell transplantation with a higher risk for stage 2-4 gastrointestinal graft vs host disease and non-relapse mortality. This marker might be used to manage patients before allogeneic hematopoietic cell transplantation.

Macrophage-derived IL-1β/NF-κB signaling mediates parenteral nutrition-associated cholestasis

In infants intolerant of enteral feeding because of intestinal disease, parenteral nutrition may be associated with cholestasis, which can progress to end-stage liver disease. Here we show the function of hepatic macrophages and phytosterols in parenteral nutrition-associated cholestasis (PNAC) pathogenesis using a mouse model that recapitulates the human pathophysiology and combines intestinal injury with parenteral nutrition. We combine genetic, molecular, and pharmacological approaches to identify an essential function of hepatic macrophages and IL-1β in PNAC. Pharmacological antagonism of  IL-1 signaling or genetic deficiency in CCR2, caspase-1 and caspase-11, or IL-1 receptor (which binds both IL-1α and IL-1β) prevents PNAC in mice. IL-1β increases hepatocyte NF-κB signaling, which interferes with farnesoid X receptor and liver X receptor bonding to respective promoters of canalicular bile and sterol transporter genes (Abcc2, Abcb11, and Abcg5/8), resulting in transcriptional suppression and subsequent cholestasis. Thus, hepatic macrophages, IL-1β, or NF-κB may be targets for restoring bile and sterol transport to treat PNAC.

Infection in central venous catheter led by parenteral nutrition of tumor patients

With the wide application of parenteral nutrition (PN) and central venous catheter (CVC) in tumor patients, the relative infection led by CVC has become a common and troublesome hospital infection in clinics. During infusion, PN fluid forms a high-sugar and high-fat microenvironment around CVC, facilitating the adhesion, growth, and diffusion of pathogenic bacteria. This condition forms a bacterial biofilm (BF) consisting of one or several kinds of pathogenic bacteria. Upon formation of the film, pathogens in the BF can resist antibacterial drugs and immune cells, causing repeated infections of bacteria or fungi and endangering the lives of patients. In this article, we summarize the applications of PN, characteristics of CVC infection in tumor patients, mixed BF, and related research methods to provide reference for studies of mixed BF infection of CVC.

The impact of early enteral nutrition on pediatric patients undergoing gastrointestinal anastomosis a propensity score matching analysis

This study was conducted to assess the clinical advantages of early enteral nutrition (EEN) in pediatric patients who underwent surgery with gastrointestinal (GI) anastomosis.EEN has been associated with clinical benefits in various aspect of surgical intervention, including GI function recovery and postoperative complications reduction. Evaluable data documenting clinical advantages with EEN for pediatric patients after surgery with GI anastomosis are limited.We retrospectively reviewed the medical records of 575 pediatric patients undergoing surgical intervention with GI anastomosis. Among them, 278 cases were managed with EEN and the remaining cases were set as late enteral nutrition (LEN) group. Propensity score (PS) matching was conducted to adjust biases in patient selection. Enteral feeding related complications were evaluated with symptoms, including serum electrolyte abnormalities, abdominal distention, abdominal cramps, and diarrhea. Clinical outcomes, including GI function recovery, postoperative complications, length of hospital stay, and postoperative follow-up, were assessed according to EEN or LEN.Following PS matching, the baseline variables of the 2 groups were more comparable. There were no differences in the incidence of enteral feeding-related complications. EEN was associated with postoperative GI function recovery, including time to first defecation (3.1 ± 1.4 days for EEN vs 3.8 ± 1.0 days for LEN, risk ratio [RR], 0.62; 95% confidence interval [CI] 0.43-1.08, P = .042). A lower total episodes of complication, including infectious complications and major complications were noted in patients with EEN than in patients with LEN (117 [45.9%] vs 137 [53.7%]; OR, 0.73, 95% CI 0.52-1.03, P = .046). Mean postoperative length of stay in the EEN group was 7.4 ± 1.8 days versus 9.2 ± 1.4 days in the LEN group (P = .007). Furthermore, the incidence of adhesive small bowel obstruction was lower for patients with laxative administration compared with control, but no significant difference was attained (P = .092)EEN was safe and associated with clinical benefits, including shorten hospital stay, and reduced overall postoperative complications on pediatric patients undergoing GI anastomosis.

Enteral Nutrients and Gastrointestinal Physiology

The gastrointestinal (GI) tract is a highly efficient organ system with specialized structures to facilitate digestion and absorption of nutrients to meet the body's needs. The presence of nutrients in the GI tract supports optimal structure and function, stimulates regulatory hormones, and supports the microbiota, the population of microorganisms residing in the GI tract. A lack of enteral nutrition (EN) results in impaired GI integrity and serious patient complications, making EN a priority. Normal GI physiology is reviewed, and the regulatory impact of luminal nutrients on GI function is discussed.

Partial enteral nutrition increases intestinal sIgA levels in mice undergoing parenteral nutrition in a dose-dependent manner

BACKGROUND AND AIMS

Partial enteral nutrition (PEN) protects parenteral nutrition (PN) induced gut mucosal immunity impairment. However, the gastrointestinal function of most patients with PN is too poor to tolerate full dosage of PEN and no guidelines recommend PEN dose. We aimed to identify an optimal PEN dose and to understand the protective mechanism.

METHODS

Mice were assigned to groups with total parenteral nutrition (TPN), total enteral nutrition (TEN), or various degrees of PEN with PN. Additionally, AS1517499 was used to inhibit STAT6. Five days after treatment, secretory immunoglobulin A (sIgA) levels of luminal washing fluid and JAK1-STAT6 signalling in ileum tissue of different groups were assessed.

RESULTS

We found that TPN lowered luminal sIgA and down-regulated pIgR, phosphorylated JAK1 and STAT6, IL-4 and IL-13 as well relative to TEN. Moreover, 40% EN were lowest dose that reversed these detrimental consequences of PN to an equivalent level as TEN. The rescue of pIgR and luminal sIgA expression was decreased when the JAK1-STAT6 pathway was inhibited.

CONCLUSION

We conclude that 40% EN is the optimal PEN dose that reverses PN-induced impairment of gut mucosal immunity. Additionally, we hypothesise that this benefit involves activation of the JAK1-STAT6 pathway.

Gene expression and morphological changes in the intestinal mucosa associated with increased permeability induced by short-term fasting in chickens

Short-term fasting for 4.5 and 9 hr has been demonstrated to increase intestinal permeability (IP) in chickens. This study aimed to investigate the effects of 0, 4.5, 9 and 19.5 hr fasting on intestinal gene expression and villus-crypt architecture of enterocytes in jejunal and ileal samples. On day 38, Ross-308 male birds were fasted according to their group and then euthanised. Two separate intestinal sections (each 2 cm long, jejunum and ileum) were collected. One section was utilised for villus height and crypt depth measurements. The second section was snap-frozen in liquid nitrogen for quantitative polymerase chain reaction (qPCR) analysis of tight junction proteins (TJP) including claudin-1, claudin-3, occludin, zonula occludens (ZO-1, ZO-2), junctional adhesion molecules (JAM) and E-cadherin. Additionally genes involved in enterocyte protection including glucagon-like peptide (GLP-2), heat-shock protein (HSP-70), intestinal alkaline phosphatase (IAP), mammalian target of rapamycin (mTOR), toll-like receptors (TLR-4), mucin (MUC-2), cluster differentiation (CD-36) and fatty acid-binding protein (FABP-6) were also analysed. Normally distributed data were analysed using one-way analysis of variance ANOVA. Other data were analysed by non-parametric one-way ANOVA. Villus height and crypt depth were increased (p < .05) only in the ileum after fasting for 4.5 and 9 hr compared with non-fasting group. mRNA expression of claudin-3 was significantly reduced in the ileum of birds fasted for 9 and 19.5 hr, suggesting a role in IP modulation. However, all other TJP genes examined were not statistically different from control. Nevertheless, ileal FABP-6 of all fasted groups was significantly reduced, which could possibly be due to reduced bile acid production during fasting.

Duodenal Disaccharidase Activities During and After Weaning off Parenteral Nutrition in Pediatric Intestinal Failure

OBJECTIVES

Data on factors affecting absorptive function in children with intestinal failure (IF) are sparse. We evaluated duodenal disaccharidase activities and inflammation in relation to parenteral nutrition (PN) and intestinal resection in pediatric onset IF.

METHODS

Disaccharidase (maltase, sucrase, and lactase) activities and histologic inflammation were evaluated from duodenal biopsies in 58 patients during PN (n = 23) or full enteral nutrition (n = 40) and in 43 matched controls. The first and the last postresection biopsies were analyzed separately after 4.3 (1.2-9.7) years and 6.5 (2.3-12.4) years, respectively.

RESULTS

During PN, maltase and sucrase activities were 1.6-fold lower and mucosal inflammation more frequent (22% vs 3%) when compared to matched controls (P < 0.05 for both). In patients on full enteral nutrition, activities of maltase and sucrase were significantly higher than that in patients receiving PN and comparable to those of matched controls. Postresection time correlated positively (r = 0.448 and r = 0.369) and percentage length of the remaining small intestine inversely (r = -0.337 and r = -0.407) with maltase and sucrase activity in patients on full enteral nutrition (P < 0.05 for all), whereas proportional length of remaining colon correlated positively with maltase and lactase activity (r = 0.424-0.544, P < 0.05) in patients receiving PN.

CONCLUSIONS

In children with IF, PN dependency associated with decreased duodenal maltase and sucrase activities and mucosal inflammation, which may disturb intestinal absorptive function. Localization and extent of intestinal resection and post-resection time correlated with duodenal disaccharidase activities.

Prolonged Absence of Mechanoluminal Stimulation in Human Intestine Alters the Transcriptome and Intestinal Stem Cell Niche

BACKGROUND & AIMS

For patients with short-bowel syndrome, intestinal adaptation is required to achieve enteral independence. Although adaptation has been studied extensively in animal models, little is known about this process in human intestine. We hypothesized that analysis of matched specimens with and without luminal flow could identify new potential therapeutic pathways.

METHODS

Fifteen paired human ileum samples were collected from children aged 2-20 months during ileostomy-reversal surgery after short-segment intestinal resection and diversion. The segment exposed to enteral feeding was denoted as fed, and the diverted segment was labeled as unfed. Morphometrics and cell differentiation were compared histologically. RNA Sequencing and Gene Ontology Enrichment Analysis identified over-represented and under-represented pathways. Immunofluorescence staining and Western blot evaluated proteins of interest. Paired data were compared with 1-tailed Wilcoxon rank-sum tests with a P value less than .05 considered significant.

RESULTS

Unfed ileum contained shorter villi, shallower crypts, and fewer Paneth cells. Genes up-regulated by the absence of mechanoluminal stimulation were involved in digestion, metabolism, and transport. Messenger RNA expression of LGR5 was significantly higher in unfed intestine, accompanied by increased levels of phosphorylated signal transducer and activator of transcription 3 protein, and CCND1 and C-MYC messenger RNA. However, decreased proliferation and fewer LGR5+, OLFM4+, and SOX9+ intestinal stem cells (ISCs) were observed in unfed ileum.

CONCLUSIONS

Even with sufficient systemic caloric intake, human ileum responds to the chronic absence of mechanoluminal stimulation by up-regulating brush-border enzymes, transporters, structural genes, and ISC genes LGR5 and ASCL2. These data suggest that unfed intestine is primed to replenish the ISC population upon re-introduction of enteral feeding. Therefore, the elucidation of pathways involved in these processes may provide therapeutic targets for patients with intestinal failure. RNA sequencing data are available at Gene Expression Omnibus series GSE82147.

Intestinal T lymphocyte homing is associated with gastric emptying and epithelial barrier function in critically ill: a prospective observational study

Background

Impaired gastric emptying is common in critically ill patients. Intestinal dysmotility, a major cause of feed intolerance, may foster infectious complications due to mucosal barrier disruption. However, little is known about gut-directed immune activation, intestinal barrier function and its association with impaired gastric emptying in critically ill patients at ICU admission.

Methods

We conducted a prospective observational study at two tertiary care medical ICUs. Fifty consecutive patients needing invasive mechanical ventilation were recruited within 24 h of ICU admission, prior to any nutritional support. The acute physiology and chronic health evaluation (APACHE) II score, the sequential organ failure assessment (SOFA) score and the multiple organ dysfunction score (MODS) were used to assess illness severity and multiple organ dysfunction. Gastric emptying was assessed by paracetamol absorption test. Peripheral blood mononuclear cells were freshly isolated and cultured for 24 h, and TNF-α, IL-1β and IL-10 measured in cell culture supernatants and in serum by ELISA. The intestinal epithelial barrier was assessed, quantifying serum concentrations of intestinal fatty acid binding protein (I-FABP), ileal bile-acid binding protein (I-BABP) and zonulin-1 by ELISA. Small bowel homing T lymphocytes (CD4+ α4β7 + CCR9+) were analyzed by flow cytometry. The Mann-Whitney test and Spearman correlation were used in statistical evaluation.

Results

CD4 + α4β7 + CCR9+ T lymphocytes were inversely correlated with gastric emptying. Patients with delayed gastric emptying at ICU admission (n = 35) had significantly higher serum and PBMC-induced TNF-α and IL-1β and increased intestinal barrier disruption reflected by higher I-FABP, I-BABP and zonulin-1. Patients who died in the ICU had significantly impaired gastric empting at admission compared to ICU survivors. No differences were observed in APACHE II, SOFA or MODS in patients with delayed gastric emptying compared to patients with normal gastric emptying.

Conclusions

Exaggerated CD4 + α4β7 + CCR9+ T lymphocyte homing with increased pro-inflammatory cytokine release and intestinal epithelial barrier disruption are associated with delayed gastric emptying. This is not simply due to differences in overall severity of illness at ICU admission and may represent a pathophysiological mechanism of gut-directed immune activation leading to impaired barrier function in the critically ill.