Anatomical and physiological considerations in short bowel syndrome: Emphasis on intestinal adaptation and the role of enterohormones

Multi-omics analysis reveals Lactobacillus and Indolelactic acid involved in small intestinal adaptation of piglet with short bowel syndrome

BACKGROUND

Short bowel syndrome (SBS) is a condition characterized by malabsorption that occurs when a patient loses a significant amount of bowel length or function, often necessitating lifelong parenteral nutrition support. This study utilized multi-omics analysis to investigate alterations in gut microbiota, metabolism, and transcriptome during the progression of intestinal adaptation in SBS using a piglet model.

METHODS

We established a model of SBS in Bama mini piglets by performing a 75% jejunoileal resection. Fifteen piglets were randomized into EN, PN, and PN-SBS groups. Fecal samples were collected for 16 S rRNA gene-based microbiota analysis. Ileal mucosa and serum were collected for untargeted liquid chromatography-mass spectrometry. Transcriptomic analysis on ileal mucosa was performed.

RESULTS

The PN-SBS model was established in the newborn piglets. A significant decrease in species-level diversity was observed in piglets with SBS, accompanied by alterations in their microbiome compositions. The beneficial anaerobes from Bacillota and Bacteroidota were depleted while microorganisms from Verrucomicrobiota and Fusobacteriota were enriched in feces from SBS piglets. The dysregulation of metabolites and metabolic pathways was observed in the metabolic profiles of ileal mucosa and serum in SBS piglets. Indolelactic acid (ILA) levels were found to be reduced in the ileal mucosa and serum of SBS piglets. Transcriptomic analysis revealed an extensive functional alteration in SBS, primarily manifested as metabolic changes and intestinal proliferation. The multi-omics analysis revealed that the decreased abundance of Lactobacillus may result in a diminished production of their metabolite ILA, thereby influencing intestinal proliferation and anti-inflammatory responses.

CONCLUSION

Disrupted homeostasis of gut microbiota, metabolism, and transcriptome were reported in the SBS piglets. Multi-omics analysis demonstrated Lactobacillus and its metabolite ILA may be involved in small intestinal adaptation of SBS. These alterations may contribute to the proinflammatory state and the delay of intestinal adaptation in SBS, which in turn provide promising targets for therapies.

Updates in Intestinal Failure Management

Short bowel syndrome (SBS) is a malabsorptive condition resulting from reduced functional small intestinal length. SBS is closely related to intestinal failure (IF), defined as the reduction of functional intestinal mass below that which can sustain life, resulting in parenteral nutrition (PN) support for 60 days or greater within a consecutive 74-day period. IF frequently results from intestinal resection necessitated by such diseases as necrotizing enterocolitis in children and Crohn's disease in adults. Clinical manifestations of IF may include diarrhea, growth failure, bacterial overgrowth, and vitamin deficiencies. Nutritional rehabilitation is the cornerstone of IF management. Surgical interventions are aimed at preserving intestinal length and restoring continuity. Medical management involves individualized enteral and parenteral nutrition therapy, GLP-2 agonists (e.g., teduglutide) that promote mucosal growth, and drugs for symptom management such as antidiarrheals. Experimental therapies such as the use of devices to induce intestinal growth through distraction enterogenesis are under development for the treatment of IF. An interdisciplinary approach involving surgeons, gastroenterologists, dietitians, nurses, and social workers is crucial in the management of these complex patients. Ultimately, a combination of nutritional, medical, and surgical management may be necessary to improve clinical outcomes in patients with IF.

Reversal of Roux-en-Y Gastric Bypass: A Multi-Centric Analysis of Indications, Techniques, and Surgical Outcomes

BACKGROUND

Roux-en-Y gastric bypass may present long-term complications that require revisional surgery or even reversal to normal anatomy. Data on the indications, surgical technique, and outcomes of RYGB reversal remain scarce.

METHODS

We identified 48 cases of RYGB reversals with complete 90-day follow-up within a multi-centric international retrospective database of elective secondary bariatric surgery. The operations were performed between 2010 and 2024 in high-volume referral centers in Europe and USA. Data were collected on body weight, associated diseases, and on surgical outcomes up to 1-year postoperatively.

RESULTS

Patients were mainly female (81.3%) with a median age of 50 years (IQR 39-56). RYGB reversal was performed 7 years (median) after primary RYGB in patients with a BMI of 23.9 kg/m2 (IQR 20-27). Half of the patients underwent at least 1 bariatric revision before the reversal. Main indications for reversal were dumping syndrome (33.3%), excessive weight loss (29.2%), marginal ulcer (14.6%), malabsorption (12.5%), and abdominal pain (10.4%). Rate of conversion to open surgery was 8.3%, and the postoperative complications during the first year reached 50%, including 31.3% Clavien-Dindo grade I-II, 16.7% grade III-IV complications, and one death. At 1 year, the mean BMI of the cohort increased by 18% to 28.25 kg/m2; only 1 patient reached pre-RYGB BMI.

CONCLUSION

Although RYGB is a theoretically reversible procedure, normal anatomy is re-established only in selected cases which are refractory to medical therapy and often also to revisional bariatric surgery. RYGB reversals entail high morbidity, while the extent of recurrent weight gain at 1-year post-reversal seems to allow patients to remain below the threshold of severe obesity.

Current Status of Chronic Intestinal Failure Management in Adults

BACKGROUND

Chronic intestinal failure (CIF) is a heterogeneous disease that affects pediatric and adult populations worldwide and requires complex multidisciplinary management. In recent years, many advances in intravenous supplementation support, surgical techniques, pharmacological management, and intestinal transplants have been published. Based on these advances, international societies have published multiple recommendations and guidelines for the management of these patients. The purpose of this paper is to show the differences that currently exist between the recommendations (ideal life) and the experiences published by different programs around the world.

METHODS

A review of the literature in PubMed from 1980 to 2024 was carried out using the following terms: intestinal failure, CIF, home parenteral nutrition, short bowel syndrome, chronic intestinal pseudo-obstruction, intestinal transplant, enterohormones, and glucagon-like peptide-2.

CONCLUSIONS

There is a difference between what is recommended in the guidelines and consensus and what is applied in real life. Most of the world's countries are not able to offer all of the steps needed to treat this pathology. The development of cooperative networks between countries is necessary to ensure access to comprehensive treatment for most patients on all continents, but especially in low-income countries.

Does Microbiome Matter in Chronic Intestinal Failure Due to Type 1 Short Bowel Syndrome in Adults?

The exact microbiome composition and function of patients with Short Bowel Syndrome (SBS) and Chronic Intestinal Failure (CIF) are still unknown. Patients with type I SBS-CIF (end-jejunostomy/ileostomy) are little represented in available studies. The aim of this study is to evaluate the microbiome characteristics of adult type 1 SBS-CIF patients according to their clinical features. Fecal microbiota was studied by amplicon-based sequencing and volatile organic compounds (VOCs) were assessed by solid-phase microextraction and gas chromatography-mass spectrometry. A total of 44 adult type 1 SBS-CIF patients were enrolled. At the family level, Lactobacillaceae (38% of the relative frequency) and Streptococcaceae (24%) were predominant; at the genus level, Streptococcus (38% of the relative frequency) and Lactobacillus (24%) were the dominant amplicon sequence variants (ASVs). Patients with increased stomal output showed higher ASVs for Lactobacillus (Rho = +0.38; p = 0.010), which was confirmed after adjusting for small bowel length (OR = 1.04; 95% CI 1.01-1.07, p = 0.023). Hyperphagia was associated with higher concentrations of short-chain fatty acid (SCFA) esters, such as butanoic acid ethyl ester (p = 0.005) and hexanoic acid ethyl ester (p = 0.004). Dietary fiber intake was directly correlated with most VOCs. Hyperphagia was associated with dietary fiber, after adjusting for small bowel length (OR = 1.35; 95% CI 1.01-1.81; p = 0.040). In type 1 SBS-CIF patients, a greater frequency of Lactobacilli was associated with increased stomal outputs, while increased fiber intake and concentrations of SCFA esters were associated with hyperphagia. These results might have implications for clinical practice.

Metabolic and Nutritional Issues after Lower Digestive Tract Surgery: The Important Role of the Dietitian in a Multidisciplinary Setting

Many patients undergo small bowel and colon surgery for reasons related to malignancy, inflammatory bowel disease (IBD), mesenteric ischemia, and other benign conditions, including post-operative adhesions, hernias, trauma, volvulus, or diverticula. Some patients arrive in the operating theatre severely malnourished due to an underlying disease, while others develop complications (e.g., anastomotic leaks, abscesses, or strictures) that induce a systemic inflammatory response that can increase their energy and protein requirements. Finally, anatomical and functional changes resulting from surgery can affect either nutritional status due to malabsorption or nutritional support (NS) pathways. The dietitian providing NS to these patients needs to understand the pathophysiology underlying these sequelae and collaborate with other professionals, including surgeons, internists, nurses, and pharmacists. The aim of this review is to provide an overview of the nutritional and metabolic consequences of different types of lower gastrointestinal surgery and the role of the dietitian in providing comprehensive patient care. This article reviews the effects of small bowel resection on macronutrient and micronutrient absorption, the effects of colectomies (e.g., ileocolectomy, low anterior resection, abdominoperineal resection, and proctocolectomy) that require special dietary considerations, nutritional considerations specific to ostomized patients, and clinical practice guidelines for caregivers of patients who have undergone a surgery for local and systemic complications of IBD. Finally, we highlight the valuable contribution of the dietitian in the challenging management of short bowel syndrome and intestinal failure.

Impact of Dietary Protein on the Management of Pediatric Short Bowel Syndrome

Essential amino acids (AAs) play a key role in stimulating intestinal adaptation after massive small gut resection. The nutritional effect of dietary amino acids during intestinal regrowth has received considerable attention in recent years. This review explores the significance of dietary amino acids in the nutritional management of infants and children with intestinal failure and short bowel syndrome (SBS) as reported in the medical literature over the last three decades. A literature search was conducted using electronic databases. Breast milk emerged as the first-line enteral regimen recommended for infants with SBS. Hydrolyzed formulas (HFs) or amino acid formulas (AAFs) are recommended when breast milk is not available or if the infant cannot tolerate whole protein milk. The superiority of AAFs over HFs has never been demonstrated. Although glutamine (GLN) is the main fuel for enterocytes, GLN supplementation in infants with SBS showed no difference in the child's dependence upon parenteral nutrition (PN). Circulating citrulline is considered a major determinant of survival and nutritional prognosis of SBS patients. Early enteral nutrition and dietary supplementation of AAs following bowel resection in children are essential for the development of intestinal adaptation, thereby eliminating the need for PN.

Effects of Treatment with Liraglutide Early after Surgical Intervention on Clinical Outcomes in Patients with Short Bowel Syndrome: A Pilot Observational "Real-Life" Study

Liraglutide, a glucagon-like peptide-1 agonist, has been shown to have beneficial effects on fecal output in short bowel syndrome (SBS) by small human studies. Its potential effects early after gut resection are not known. In this pilot observational study, we described the 1- and 6-month liraglutide effects in 19 adult patients with a new SBS diagnosis within 1 month after surgical resection. Stomal/fecal and urinary outcomes, serum/urinary electrolytes, and body composition were assessed. Both within-group differences and between-group comparisons with 20 SBS patients refusing liraglutide treatment were evaluated. The main liraglutide-related side effect was mild nausea, except in one patient, who experienced severe nausea/vomiting. The median ostomy/fecal output was significantly reduced by -550 mL/day after 6 months of treatment (vs. -200 mL/day in untreated, p = 0.04). The number of patients reaching a ≥20% output reduction was 10/19 (52.6%) treated vs. 3/20 (15.0%) untreated patients (p = 0.013) at 1 month and 12/19 (63.2%) vs. 6/20 (30.0%) (p = 0.038) at 6 months, respectively. Participants with a clinically relevant output reduction at 6 months had a significantly lower baseline weight and BMI. Energy parenteral supply significantly decreased, while infused volumes, oral energy, and fluid intakes slightly decreased, though not significantly. This pilot study supports liraglutide benefits in ostomy/fecal output early after surgical gut resection in SBS patients, particularly in those with lower baseline weight values.

Altered fecal microbiome and metabolome profiles in rat models of short bowel syndrome

INTRODUCTION

Short bowel syndrome (SBS) is featured by impaired nutrients and fluids absorption due to massive small intestine resection. Gut dysbiosis has been implicated in SBS, this study aimed to characterize the metagenomic and metabolomic profiles of SBS and identify potential therapeutic targets.

METHODS

Fecal samples from SBS and Sham rats (n = 8 per group) were collected for high-throughput metagenomic sequencing. Fecal metabolomics was measured by untargeted liquid chromatography-mass spectrometry.

RESULTS

We found that the species-level α-diversity significantly decreased in SBS rats, accompanied by altered microbiome compositions. The beneficial anaerobes from Firmicutes and Bacteroidetes were depleted while microorganisms from Lactobacillus, Escherichia, Enterococcus, and Streptococcus were enriched in faces from SBS rats. LEfSe analysis identified 17 microbial species and 38 KEGG modules that were remarkably distinct between SBS and Sham rats. In total, 1,577 metabolites with known chemical identity were detected from all samples, among them, 276 metabolites were down-regulated and 224 metabolites were up-regulated in SBS group. The typical signatures of SBS fecal metabolome comprised reduced short-chain fatty acids and products of amino acid metabolism (indole derivatives and p-cresol), as well as altered bile acid spectrum. We revealed 215 robust associations between representative differentially abundant microbial species and metabolites, the species with the same changing trend tended to have a similar correlation with some certain metabolites.

CONCLUSION

The fecal microbiome and metabolome significantly altered in SBS. Our findings may lay the foundation for developing new strategies to facilitate intestinal adaptation in SBS patients.