Partial Enteral Nutrition Mitigated Ischemia/Reperfusion-Induced Damage of Rat Small Intestinal Barrier

EFFECTS OF HYPERBARIC OXYGEN THERAPY ON INTESTINAL ISCHEMIA-REPERFUSION AND ITS MECHANISM

ABSTRACT

Ischemia can cause reversible or irreversible cell or tissue damage, and reperfusion after ischemia not only has no therapeutic effect but also aggravates cell damage. Notably, gut tissue is highly susceptible to ischemia-reperfusion (IR) injury under many adverse health conditions. Intestinal IR (IIR) is an important pathophysiological process in critical clinical diseases. Therefore, it is necessary to identify better therapeutic methods for relieving intestinal ischemia and hypoxia. Hyperbaric oxygenation refers to the intermittent inhalation of 100% oxygen in an environment greater than 1 atm pressure, which can better increase the oxygen level in the tissue and change the inflammatory pathway. Currently, it can have a positive effect on hypoxia and ischemic diseases. Related studies have suggested that hyperbaric oxygen can significantly reduce ischemia-hypoxic injury to the brain, spinal cord, kidney, and myocardium. This article reviews the pathogenesis of IR and the current treatment measures, and further points out that hyperbaric oxygen has a better effect in IR. We found that not only improved hypoxia but also regulated IR induced injury in a certain way. From the perspective of clinical application, these changes and the application of hyperbaric oxygen therapy have important implications for treatment, especially IIR.

Association between oral nutrition and inflammation after intestinal transplantation

Intestinal transplantation (Itx) can be a life-saving treatment for certain patient populations, including those patients with intestinal failure (IF) who develop life-threatening complications due to the use of parenteral nutrition (PN). Most patients who have undergone Itx are eventually able to tolerate a full oral diet. However, little guidance or consensus exists regarding optimizing the specific components of an oral diet for Itx patients, including macronutrients, micronutrients and dietary patterns. While oral dietary prescriptions have moved to the forefront of primary and preventive care, this movement has yet to occur across the field of organ transplantation. Evidence to date points to the role of systemic chronic inflammation (SCI) in a wide variety of chronic diseases as well as post-transplant graft dysfunction. This review will discuss current trends in oral nutrition for Itx patients and also offer novel insights into nutritional management techniques that may help to decrease SCI and chronic disease risk as well as optimize graft function.

Nutrition in intestinal transplantation: centre stage or supporting act?

PURPOSE OF REVIEW

Intestinal transplantation (ITx), whether isolated or combined with other organs, is now a valid treatment option in some patients with chronic intestinal failure or extensive venous mesenteric thrombosis. The aim in these patients is not only to restore nutritional autonomy, but also to minimize the risk of complications, both short and long term. Despite parenteral nutrition playing a central part in the management of intestinal failure patients, there are little data about the perioperative and postoperative nutritional management of ITx patients, due to small patient populations per centre. In this review, we collected the scientific data available to date.

RECENT FINDINGS

In this review, we will bundle the limited scientific information about diet after intestinal and multivisceral transplantation combined with recommendations from our own clinical practice in 28 ITx patients in University Hospitals Leuven, Belgium. We will discuss the immediate preoperative period, surgical complications necessitating dietary interventions and the late postoperative phase in a stable outpatient transplant recipient.

SUMMARY

Although no specific research has been done in the field of ITx, we can extrapolate some findings from other solid organ transplants. Prehabilitation might prove to be of importance; Preserving kidney and liver function in the pretransplant period should be pursued. Transition from parenteral to enteral and oral nutrition can be complex due to inherent surgical procedures and possible complications. Ultimately, the goal is to give patients nutritional autonomy, while also minimizing the risk of foodborne infections by teaching patients well tolerated food practices.

The Low-density Lipoprotein Receptor-related Protein 6 Pathway in the Treatment of Intestinal Barrier Dysfunction Induced by Hypoxia and Intestinal Microbiota through the Wnt/β-catenin Pathway

Our study is to explore the key molecular of Low-density lipoprotein receptor-related protein 6 (LRP6) and the related Wnt/β-catenin pathway regulated by LRP6 during the intestinal barrier dysfunction. Colorectal protein profile analysis showed that LRP6 expression was decreased in dextran sulfate sodium (DSS)-induced colitis mice, and mice received fecal bacteria transplantation from stroke patients. Mice with intestinal hypoxia and intestinal epithelial cells cultured in hypoxia showed decreased expression of LRP6. Overexpression of LPR6 or its N-terminus rescued the Wnt/β-catenin signaling pathway which was inhibited by hypoxia and endoplasmic reticulum stress. In mice overexpressing of LRP6, the expression of β-catenin and DKK1 increased, Bcl2 decreased, and Bax increased. Mice with LRP6 knockout showed an opposite trend, and the expression of Claudin2, Occludin and ZO-1 decreased. Two drugs, curcumin and auranofin could alleviate intestinal barrier damage in DSS-induced colitis mice by targeting LRP-6. Therefore, gut microbiota dysbiosis and hypoxia can inhibit the LRP6 and Wnt/β-catenin pathway, and drugs targeting LRP6 can protect the intestinal barrier.

Data-Independent Acquisition-Based Mass Spectrometry (DIA-MS) for Quantitative Analysis of Human Intestinal Ischemia/Reperfusion

Intestinal ischemia-reperfusion (II/R) injury is a complex pathologic process, which is of great significance to unravel the underlying mechanisms and pathophysiology. Our study represented a comprehensive proteomic analysis in the human intestine with ischemia-reperfusion injury. The proteomics analysis measured a total of 5,230 proteins, and 417 differently expressed proteins (DEPs) were identified between II/R and control samples. GO and KEGG analysis demonstrated that the 290 upregulated DEPs in II/R were significantly involved in immune-related biological process and tight junction, focal adhesion, and cAMP signaling pathway, whereas the 127 downregulated DEPs in II/R were enriched in lipid metabolic process and metabolic pathway. Furthermore, we screened out 20 hub proteins from the protein-protein interaction (PPI) network according to the degree of connectivity, and six clusters were identified. Combined with the result of KEGG analysis, 6 from the 20 hub proteins, ACTB, CAV1, FLNA, MYLK, ACTN1, and MYL9, were identified as the key proteins in the progress of II/R injury. According to the previous studies, FLNA and MYL9 were selected as the novel disease-related proteins for the first time. In conclusion, this study extended our understanding of the alteration in the human intestine during ischemia and reperfusion and highlighted the potential role of FLNA and MYL9 in the progress of II/R injury, which need to be further studied.

The Pathology and Physiology of Ileostomy

An ileostomy is a surgery that is commonly performed to protect low pelvic anastomoses or prevent high-risk anastomotic leakages. However, various postoperative complications remain of major concern. After an ileostomy, the distal intestinal segment is left open for an extended period and is in a non-functional state. Consequently, the intestinal mucosa, smooth muscle, and microbiota undergo significant changes that are closely related to postoperative recovery and complications. A systematic description of these changes is necessary to understand the relationship among them and take more effective measures for postoperative intervention.

Comparison of the effects of different calorie amounts of enteral nutrition in hypercatabolism associated with ghrelin-POMC in endotoxemic rats

Background

Hypercatabolism often occurs in critically ill patients, and it increases infection rates and mortality in these patients. Enteral nutrition (EN) is commonly used in case of hypercatabolism. However, the effect of amount of calories in EN on hypercatabolism remains unexplored.

Objective

Here, we compared the effect of low-calorie, medium-calorie and high-calorie EN on hypercatabolism in the acute phase of endotoxemia, which is associated with gastrointestinal hormones and hypothalamic neuropeptide proopiomelanocortin (POMC).

Methods

Overall 84 adult male Sprague–Dawley rats were used for research. A set of rats were divided into 5 groups, Control (NS) and lipopolysaccharide (LPS) groups were fed a standard chow diet; LPS + L (LPS + 40 kcal/kg/day EN), LPS + M (LPS + 80 kcal/kg/day EN) and LPS + H (LPS + 120 kcal/kg/day EN) groups received EN through a gastric tube for 3 days. Another set of rats were used for parallel control experiment and divided into 5 groups: NS + F (saline + fasting) and LPS + F (LPS + fasting) groups were given no food, NS + L (saline + 40 kcal/kg/day EN), NS + M (saline + 80 kcal/kg/day EN) and NS + H (saline + 120 kcal/kg/day EN) groups received EN through a gastric tube for 3 days. Hypercatabolism was evaluated by assessing skeletal muscle protein synthesis and atrophy, insulin resistance, and corticosterone levels. Moreover, serum inflammatory factors, gastrointestinal hormones, hypothalamic ghrelin, growth hormone secretagogue receptor-1α, hypothalamic neuropeptide, and intestinal injury indicators were detected.

Results

Low-calorie EN effectively increased serum and hypothalamic ghrelin possibly due to slight intestinal barrier damage, thereby decreasing hypothalamic POMC expression; consequently, it alleviated rat insulin resistance, reduced blood cortisol levels and muscle atrophy, and improved the survival rate of rats in the acute phase of endotoxemia. Interestingly, with an increase in calories in enteral nutrition, the aforementioned effects did not increase.

Conclusions

Low-calorie EN could effectively increase gastrointestinal hormone ghrelin by reducing intestinal damage and suppressing POMC expression to ameliorate hypercatabolism when compared with medium-calorie and high-calorie EN. Therefore Low-calorie EN may be preferred for providing EN in the acute stage of endotoxemia.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12986-022-00663-7.

Intestinal ischemic reperfusion injury: Recommended rats model and comprehensive review for protective strategies

Intestinal ischemic reperfusion injury (IIRI) is a life-threatening condition with high morbidity and mortality in the clinic. IIRI was induced by intestinal ischemic diseases such as, small bowel transplantation, aortic aneurysm surgery, and strangulated hernias. Although related mechanisms have not been fully elucidated, during the last decade, researches have demonstrated that many factors are crucial in the pathological process, including oxidative stress (OS), epithelial barrier function disorder, and so on. Rats model, as the most applied animal IIRI model, provides specific targets for researches and therapeutic strategies. Moreover, various treatment strategies such as, anti-oxidative stress, anti-apoptosis, and anti-inflammation, have shown promising effects in alleviating IIRI. However, current researches cannot solve the clinical problems of IIRI, and specific treatment strategies are still needed to be exploited. This review focuses on a recommended experimental IIRI rat model and understanding of the involved mechanisms such as, OS, gut bacteria translocation, apoptosis, and necroptosis, aim at providing novel ideas for therapeutic strategies of IIRI.

Hydrogen-rich saline protects intestinal epithelial tight junction barrier in rats with intestinal ischemia-reperfusion injury by inhibiting endoplasmic reticulum stress-induced apoptosis pathway

AIM

To investigate the effects of hydrogen-rich saline (HRS) on intestinal epithelial tight junction (TJ) barrier in rats with intestinal ischemia-reperfusion injury (IIRI).

MATERIALS AND METHODS

Thirty-two healthy male Sprague-Dawley (SD) rats were randomly divided into four groups (n = 8 each): Sham group, I/R group, HRS group and 4-PBA group. After 45 min of ischemia and 6 h of reperfusion, the rats were sacrificed to collect serum and ileum for detection. Hematoxylin and eosin (H&E) staining was used to observe the morphology of small intestine. The serum expression levels of intestinal fatty acid binding protein (IFABP), tumor necrosis factor-α (TNF-α), and interleukin-1β (IL-1β) were determined by enzyme linked immunosorbent assay (ELISA). Imunohistochemistry, immunofluorescence and Western blot were used to detect key proteins in intestinal epithelial TJs, ERS, and ERS-induced apoptosis, including occludin, zonula occludens-1 (ZO-1), glucose-regulated protein 78 (GRP78), X-box binding protein-1 (XBP1), C/EBP-homologous protein (CHOP) and caspase-3. Data was presented as mean ± SEM and compared using one-way ANOVA. A p-value <0.05 was considered significant.

RESULTS

Compared with rats in the I/R group, the Chiu score of ileum damage in the HRS group and 4-PBA group were lower. The levels of serum IFABP, TNF-α, and IL-1β were statistically significant among the groups. Increased expression of TJ proteins occludin and ZO-1 by reducing various parameters of ERS and ERS-induced apoptosis evidenced by down-regulation of the protein levels of GRP78, XBP1, CHOP and caspase-3 were shown in the HRS and 4-PBA groups.

CONCLUSION

HRS had potential protective effects on intestinal barrier in IIRI rats. This study suggested that inhibition of excessive ERS and ERS-induced apoptosis by HRS may reduce intestinal epithelial cells damage and maintain the integrity of intestinal epithelial TJ barrier in rats with IIRI.

κ-opioid receptor agonists may alleviate intestinal damage in cardiopulmonary bypass rats by inhibiting the NF-κB/HIF-1α pathway

The aims of the present study were to investigate the protective effect of a κ-opioid receptor (KOR) agonist on intestinal barrier dysfunction in rats during cardiopulmonary bypass (CPB), as well as to examine the role of NF-κB and the transcription factor hypoxia-inducible factor-1α (HIF-1α) signaling pathway in the regulatory mechanism. A total of 50 rats were randomly divided into five groups, with 10 rats in each group: Sham surgery group (group Sham), CPB surgery group (group CPB), KOR agonist + CPB (group K), KOR agonist + specific KOR antagonist + CBP (group NK) and KOR agonist + NF-κB pathway specific inhibitor + CPB (group NF). Intestinal microcirculation was evaluated to determine intestinal barrier dysfunction in rats following CPB surgery. Hematoxylin and eosin (H&E) staining was used to observe intestinal tissue injury in the rats. ELISA was used to detect the inflammatory factors interleukin (IL)-1β, IL-6, IL10 and tumor necrosis factor-α, and the oxidative stress factors superoxidase dismutase, malondialdehyde and nitric oxide in serum. In addition, ELISA was used to investigate the serum levels of the intestinal damage markers D-lactic acid, diamine oxidase and intestinal fatty acid-binding protein. Western blotting was used to investigate the protein expression levels of tight junction proteins zonula occludens-1 and claudin-1. Furthermore, immunohistochemistry was used to examine intestinal injuries and western blotting was used to detect expression levels of NF-κB/HIF-1α signaling pathway-related proteins. H&E staining results suggested that the KOR agonist alleviated intestinal damage in the CPB model rats. This effect was reversed by the addition of a KOR antagonist. Further investigation of inflammatory and oxidative stress factors using ELISA revealed that the KOR agonist reduced the inflammatory and oxidative stress responses in the intestinal tissues of the CPB model rats. The ELISA results of intestinal damage markers and western blotting results of tight junction protein expression suggested that KOR agonist treatment may alleviate intestinal injury in CPB model rats. In addition, the western blotting and immunohistochemistry results suggested that KOR agonists may decrease the expression levels of NF-κB, p65 and HIF-1α in CPB. Collectively, the present results suggested that KOR agonists are able to ameliorate the intestinal barrier dysfunction in rats undergoing CPB by inhibiting the expression levels of NF-κB/HIF-1α signaling pathway-related proteins.

A Comparison of Gastric and Jejunal Feeding in Hypercatabolism Associated With Hypothalamic AMPK-Autophagy-POMC in Endotoxemic Rats

BACKGROUND

Hypercatabolism is associated with increased infectious rates and mortality in critically ill patients. Enteral nutrition (EN) is usually used to counteract hypercatabolism. However, the impact of different routes of EN on hypercatabolism remains unknown. Here, we compared the impact of gastric feeding (GF) and jejunal feeding (JF) on gastrointestinal hormones and hypercatabolism, which is associated with hypothalamic adenosine 5'-monophosphate-activated protein kinase (AMPK)-autophagy-proopiomelanocortin (POMC).

METHODS

Sixty adult male Sprague-Dawley rats were divided into 5 groups: Sham and lipopolysaccharide (LPS) groups fed a standard chow diet, a pair-fed group that was a subset of saline-treated rats pair-fed with the LPS group, and LPS + JF and LPS + GF groups (received EN via jejunal and gastric tube, respectively, for 3 days [100 kcal/kg/d]). Hypercatabolism was measured by insulin resistance, muscle protein synthesis, and atrophy. Serum gastrointestinal hormones, hypothalamic ghrelin, growth hormone secretagogue receptor-1α (GHS-R1α), and AMPK-autophagy-POMC markers were also detected.

RESULTS

GF increased serum total, acylated, desacylated, and hypothalamic ghrelin and decreased glucagon-like peptide-1 (GLP-1). But no effect on pancreatic polypeptide (PYY) and hypothalamic GHS-R1α was observed. JF showed no effect on hypothalamic ghrelin, GHS-R1α, and serum total, acylated, and desacylated ghrelin and even further aggravated GLP-1 and PYY. GF could effectively augment hypothalamic AMPK-autophagy-POMC and hypercatabolism. However, JF showed no effect on hypothalamic AMPK-autophagy-POMC and hypercatabolism.

CONCLUSIONS

GF could activate hypothalamic AMPK-autophagy and suppress POMC expression via gastrointestinal hormones to ameliorate hypercatabolism compared with JF, which suggested that GF may be the preferred route of EN in endotoxemic rats.

Changes of plasma acetylcholine and inflammatory markers in critically ill patients during early enteral nutrition: A prospective observational study

BACKGROUND

Acetylcholine (Ach) is the key anti-inflammatory transmitter in the cholinergic anti-inflammatory pathway. In this study, critically ill patients treated with early enteral nutrition (EEN) were observed to explore whether EEN affected Ach levels and inflammation.

METHODS

One hundred thirteen patients were included in this prospective observational study. All patients were provided the early enteral nutrition protocol 24-48 h after admission to the intensive care unit (ICU). Blood samples were collected, and the plasma levels of Ach, cholecystokinin (CCK), and inflammatory markers (tumour necrosis factor alpha (TNF-α), interleukin 1beta (IL1-β), and IL6) were measured on Days 0, 1, 3, 5, and 7. Nutritional intervention data were recorded within one week, including the number of patients receiving nutrition, the number of days nutrition was provided, the caloric intake and protein intake, feeding intolerance and prokinetic drug administration. Other collected data included the sequential organ failure assessment score (SOFA score), the Acute Physiology and Chronic Health Evaluation (APACHE) II score, the use of mechanical ventilation (the number of patients and the duration), use of vasoactive drugs and the number of renal replacement treatments (RRT) received by each patient during their ICU stay. The primary outcome was 28-day mortality. Additionally, we analysed the correlation between plasma Ach levels and inflammation, as well as the correlation between plasma Ach and CCK levels. Moreover, a multivariate regression analysis was performed to examine the independent effects of different variables on 28-day mortality and Ach levels.

RESULTS

The overall 28-day mortality was 28.3% (32/113). Eighty-two patients tolerated enteral nutrition. Compared with Day 0 15.6 (2.8) nmol/l, the plasma Ach level was significantly increased on Day 3 18.6 (6.7) nmol/l, Day 5 19.3 (6.2) nmol/l and Day 7 19.7 (4.3) nmol/l (p < .001). Compared with Day 0176.2 (50.4) pg/ml, the plasma TNF-α level was significantly decreased on Day 3144.0 (77.4) pg/ml, Day 5127.3 (51.8) pg/ml and Day 7111.4 (42.5) pg/ml (p < .05). Compared with Day 0, the plasma IL1-β level was significantly decreased on Day 7 (p < .05). The plasma IL6 level was significantly decreased on Day 5 and Day 7 (p < .05) compared with Day 0. Compared with Day 0, the plasma CCK level was significantly increased on Day 3, 5 and 7 (p < .001). The correlation analysis revealed negative correlations between Ach levels and inflammation (p < .001), and a positive correlation between CCK and Ach levels (r = 0.775, p < .001). A comparison of patients who did or did not tolerate EEN revealed significant differences in the plasma levels of Ach, TNF-α, IL6 and CCK (p < .05). Significant differences in plasma levels of Ach, TNF-α, IL1-β, IL6 and CCK were observed between 28-day survivors and non-survivors (p < .05). The multivariate logistic regression analysis identified vasopressor support, RRT, the administration of EEN, SOFA score, APACHE II score at ICU admission and plasma Ach levels as independent determinants of 28-day mortality. Additionally, the multivariate linear regression analysis identified EEN, plasma lactate, mechanical ventilation, the SOFA score and plasma CCK levels as independent determinants of plasma Ach levels.

CONCLUSIONS

The administration of EEN to critically ill patients contributed to the increased plasma Ach levels and decreased inflammatory markers. The effect of EEN on Ach levels is partially attributed to the increase in CCK levels. Elevated plasma Ach levels indicate a better prognosis. Clinical trials identifier: NCT03612206.

DNase-1 Treatment Exerts Protective Effects in a Rat Model of Intestinal Ischemia-Reperfusion Injury

A growing number of studies have recently revealed a potential role for neutrophil extracellular traps (NETs) in the development of inflammation, coagulation and cell death. Deleterious consequences of NETs have been identified in ischemia-reperfusion (I/R)-induced organ damage, thrombosis and sepsis. And exogenous DNase-I has been suggested as a therapeutic strategy to attenuate ischemia-reperfusion (I/R) injuries in the kidney, brain and myocardium. Herein, we designed a study to investigate whether NETs contribute to the pathogenesis of intestinal I/R injury and evaluated the therapeutic value of DNase-1 in a rat model of intestinal I/R injury. In this rat model of intestinal I/R injury, we found that extracellular DNA was readily detectable in rat serum after 1 h of ischemia and 2 h of reperfusion. Treatment with DNase-1 significantly reduced the inflammatory response, restored intestinal barrier integrity and increased the expression of tight junction proteins. Our results indicate the existence of NETs in I/R-challenged intestinal tissues and firstly provide more evidence that DNase-1 may be an effective treatment for attenuating intestinal I/R injury.