Time- and segment-related changes of postresected intestine: a 4-dimensional model of intestinal adaptation

Nutrition and Intestinal Rehabilitation of Children With Short Bowel Syndrome: A Position Paper of the ESPGHAN Committee on Nutrition. Part 1: From Intestinal Resection to Home Discharge

Short bowel syndrome (SBS) is the leading cause of intestinal failure (IF) in children. The mainstay of treatment for IF is parenteral nutrition (PN). The aim of this position paper is to review the available evidence on managing SBS and to provide practical guidance to clinicians dealing with this condition. All members of the Nutrition Committee of the European Society for Paediatric Gastroenterology Hepatology and Nutrition (ESPGHAN) contributed to this position paper. Some renowned experts in the field joined the team to guide with their experience. A systematic literature search was performed from 2005 to May 2021 using PubMed, MEDLINE, and Cochrane Database of Systematic Reviews. In the absence of evidence, recommendations reflect the expert opinion of the authors. Literature on SBS mainly consists of retrospective single-center experience, thus most of the current papers and recommendations are based on expert opinion. All recommendations were voted on by the expert panel and reached >90% agreement. The first part of this position paper focuses on the physiological mechanism of intestinal adaptation after surgical resection. It subsequently provides some clinical practice recommendations for the primary management of children with SBS from surgical resection until discharged home on PN.

An Overview of Short-Bowel Syndrome in Pediatric Patients: Focus on Clinical Management and Prevention of Complications

Short-bowel syndrome (SBS) in pediatric age is defined as a malabsorptive state, resulting from congenital malformations, significant small intestine surgical resection or disease-associated loss of absorption. SBS is the leading cause of intestinal failure in children and the underlying cause in 50% of patients on home parental nutrition. It is a life-altering and life-threatening disease due to the inability of the residual intestinal function to maintain nutritional homeostasis of protein, fluid, electrolyte or micronutrient without parenteral or enteral supplementation. The use of parenteral nutrition (PN) has improved medical care in SBS, decreasing mortality and improving the overall prognosis. However, the long-term use of PN is associated with the incidence of many complications, including liver disease and catheter-associated malfunction and bloodstream infections (CRBSIs). This manuscript is a narrative review of the current available evidence on the management of SBS in the pediatric population, focusing on prognostic factors and outcome. The literature review showed that in recent years, the standardization of management has demonstrated to improve the quality of life in these complex patients. Moreover, the development of knowledge in clinical practice has led to a reduction in mortality and morbidity. Diagnostic and therapeutic decisions should be made by a multidisciplinary team that includes neonatologists, pediatric surgeons, gastroenterologists, pediatricians, nutritionists and nurses. A significant improvement in prognosis can occur through the careful monitoring of nutritional status, avoiding dependence on PN and favoring an early introduction of enteral nutrition, and through the prevention, diagnosis and aggressive treatment of CRSBIs and SIBO. Multicenter initiatives, such as research consortium or data registries, are mandatory in order to personalize the management of these patients, improve their quality of life and reduce the cost of care.

A Model of Short Bowel Syndrome in Rodents in a Long-Term Experiment

Simulation of short bowel syndrome (SBS) in experimental animals is of great interest for studies in translational medicine. The processes of intestinal adaptation are most often studied in rats aged 8-10 weeks with up to 70% resection the small bowel. In this case, the animals are euthanized in 2 weeks after the surgery; further development of the pathological process remains practically unexplored. In our experiment, a number of blood biochemical parameters and morphological signs of intestinal adaptation were assessed within 34 weeks after surgery. It was shown that after resection of 70% of the small bowel in rats (180±15 g), clinical symptoms are observed only during the first 2 weeks, however, the mortality in the group was observed throughout the entire period of the study in the absence of clear clinical signs. Morphological compensatory changes in the walls of the small intestine continued up to 34 weeks after resection, and their morphometry can be used to describe adaptation in the dynamics of the study.

Distal Small Bowel Resection Yields Enhanced Intestinal and Colonic Adaptation

BACKGROUND

Murine ileocecal resection (ICR) has been used to investigate intestinal adaptation. The established model often includes the sacrifice of significant length of the proximal colon. Here, we optimized a highly selective vascular approach to the ICR, with primary jejunal-colic anastomosis yielding maximal colonic preservation.

MATERIALS AND METHODS

Forty C57BL/6 mice underwent a highly vascularly selective ICR. The terminal branches of the ileocecal artery are isolated apart from the mesenteric branches supplying the small bowel to be resected. The distal 50% of small bowel and cecum are resected; a primary jejuno-colonic anastomosis is performed. Animals were sacrificed at postoperative weeks 2 (n = 10) and 10 (n = 29). Proximal 50% small bowel resection (SBR) with jejuno-ileal anastomosis was also performed for comparison.

RESULTS

The entire colon (with exception of the cecum) was preserved in 100% of animals. Ninety-seven percent of animals survived to postoperative week 10, and all exhibited structural adaptation in the remnant small intestine epithelium. Crypts deepened by 175%, and villi lengthened by 106%, versus 39% and 29% in the proximal SBR cohort, respectively. Colonic proliferation, structural adaptation, and functional adaptation (measured by p-histone 3, luminal-facing apical crypt border size, and sucrase isomaltase, respectively) were increased in ICR compared with proximal SBR.

CONCLUSIONS

Highly selective isolation of the cecal vasculature allows for greater colon preservation and yields enhanced remnant intestine epithelial adaptation. ICR is also associated with greater colonic adaptation and unique plasticity toward an intestinal phenotype. These findings underscore major differences between resection sites and offer insights into the critical adaptive mechanisms in response to massive intestinal loss.

Digestive enzyme expression in the large intestine of children with short bowel syndrome in a late stage of adaptation

BACKGROUND AND AIMS

Intestinal adaptation in short bowel syndrome (SBS) includes morphologic processes and functional mechanisms. This study investigated whether digestive enzyme expression in the duodenum and colon is upregulated in SBS patients.

METHOD

Sucrase-isomaltase (SI), lactase-phlorizin hydrolase (LPH), and neutral Aminopeptidase N (ApN) were analyzed in duodenal and colonic biopsies from nine SBS patients in a late stage of adaptation as well as healthy and disease controls by immunoelectron microscopy (IEM), Western blots, and enzyme activities. Furthermore, proliferation rates and intestinal microbiota were analyzed in the mucosal specimen.

RESULTS

We found significantly increased amounts of SI, LPH, and ApN in colonocytes in most SBS patients with large variation and strongest effect for SI and ApN. Digestive enzyme expression was only partially elevated in duodenal enterocytes due to a low proliferation level measured by Ki-67 staining. Microbiome analysis revealed high amounts of Lactobacillus resp. low amounts of Proteobacteria in SBS patients with preservation of colon and ileocecal valve. Colonic expression was associated with a better clinical course in single cases.

CONCLUSION

In SBS patients disaccharidases and peptidases can be upregulated in the colon. Stimulation of this colonic intestinalization process by drugs, nutrients, and pre- or probiotics might offer better therapeutic approaches.

Prevention and Treatment of Intestinal Failure-Associated Liver Disease in Children

Intestinal failure-associated liver disease (IFALD) is a threatening complication for children on long-term parenteral nutrition because of intestinal failure. When progressive and intractable, it may jeopardize intestinal rehabilitation and lead to combined liver and intestinal transplantation. The institution of dedicated intestinal failure centers has dramatically decreased the incidence of such complication. IFALD may rapidly fade away if very early management aimed at preventing progression to end-stage liver disease is provided. In this review, we address the etiology and risk factors of IFALD in order to introduce pillars of prevention (nutritional management and catheter-related infections control). The latest evidence of therapeutic strategies, such as medical and surgical treatments, is also discussed.

Effect of proximal versus distal 50% enterectomy on nutritional parameters in rats preconditioned with a high-fat diet or regular chow

Obesity may protect against the nutritional consequences of short bowel syndrome. We hypothesized that rats preconditioned with an obesogenic diet would have better outcomes after surgical induction of short bowel syndrome compared to rats on regular chow. Rats were fed a high-fat diet or regular rat chow for six months, and then underwent 50% proximal, 50% distal, or sham enterectomy. Food intake, weight, and body composition were monitored before and for 4 weeks after surgery. The high-fat diet consistently produced obesity (>25% body fat). All procedures induced weight loss, but there was no discernable difference between resection vs. sham resection. Rats on the high-fat diet had a greater post-resection loss of body fat compared to rats on chow (36 vs. 26 g, respectively). There was a nonsignificant trend of less lean mass loss in the former compared to the latter rats (16 vs. 33 g, respectively). Enterectomy moderated serum ghrelin, GIP, PPY, insulin, and leptin. Intestinal adaptation was not different between obese vs. non-obese rats. Rats preconditioned with the high-fat diet may have had better retention of lean body mass after a surgical procedure compared to rats on chow. The effect of 50% enterectomy was less than expected.

Short bowel syndrome and small bowel transplantation

PURPOSE OF REVIEW

The purpose of this review is to provide an update of recent advances in the areas of short bowel syndrome (SBS) and small bowel transplantation (SBT).

RECENT FINDINGS

Recent reports from two of the largest multicenter randomized, controlled trials in patients with SBS support the safety and efficacy of teduglutide as an aid to parenteral nutrition weaning. In well selected SBS patients, outcomes as diverse as survival, macronutrient absorption and parenteral nutrition weaning are improved after autologous gastrointestinal reconstructive surgery. SBT is no longer considered investigational and given improved outcomes noted in recent reports, indications for transplantation are expanding. Although SBT early survival rates are approaching those of other organ allografts, long-term graft survival remains suboptimal.

SUMMARY

Recently available trophic factors hold promise as aids in restoring freedom from parenteral nutrition support; however, their long-term benefits, preferred timing of administration in relation to the onset of SBS, optimal patient selection for use, duration of treatment and cost effectiveness require further study. Despite recent evidence of improved early survival after SBT, more dedicated research is needed to design more effective strategies to better tolerize small bowel grafts, prevent rejection and, ultimately, improve long-term outcomes. Reserved for well selected patients, autologous gastrointestinal reconstruction should be considered complementary and not antagonistic to SBT.