"Gut-feeling" or evidence-based approaches in the evaluation and treatment of human short-bowel syndrome

Schlafen 12 Interaction with SerpinB12 and Deubiquitylases Drives Human Enterocyte Differentiation

BACKGROUND/AIMS

Human enterocytic differentiation is altered during development, fasting, adaptation, and bariatric surgery, but its intracellular control remains unclear. We hypothesized that Schlafen 12 (SLFN12) regulates enterocyte differentiation.

METHODS

We used laser capture dissection of epithelium, qRT-PCR, and immunohistochemistry to evaluate SLFN12 expression in biopsies of control and fasting human duodenal mucosa, and viral overexpression and siRNA to trace the SLFN12 pathway in human Caco-2 and HIEC6 intestinal epithelial cells.

RESULTS

Fasting human duodenal mucosa expressed less SLFN12 mRNA and protein, accompanied by decreases in enterocytic markers like sucrase-isomaltase. SLFN12 overexpression increased Caco-2 sucrase-isomaltase promoter activity, mRNA, and protein independently of proliferation, and activated the SLFN12 putative promoter. SLFN12 coprecipitated Serpin B12 (SERPB12). An inactivating SLFN12 point mutation prevented both SERPB12 binding and sucrase-isomaltase induction. SERPB12 overexpression also induced sucrase-isomaltase, while reducing SERPB12 prevented the SLFN12 effect on sucrase-isomaltase. Sucrase-isomaltase induction by both SLFN12 and SERPB12 was attenuated by reducing UCHL5 or USP14, and blocked by reducing both. SERPB12 stimulated USP14 but not UCHL5 activity. SERPB12 coprecipitated USP14 but not UCHL5. Moreover, SLFN12 increased protein levels of the sucrase-isomaltase-promoter-binding transcription factor cdx2 without altering Cdx2 mRNA. This was prevented by reducing UCHL5 and USP14. We further validated this pathway in vitro and in vivo. SLFN12 or SERPB12 overexpression induced sucrase-isomaltase in human non-malignant HIEC-6 enterocytes.

CONCLUSIONS

SLFN12 regulates human enterocytic differentiation by a pathway involving SERPB12, the deubiquitylases, and Cdx2. This pathway may be targeted to manipulate human enterocytic differentiation in mucosal atrophy, short gut or obesity.

Intestinal permeability and effects of Lactobacillus rhamnosus therapy in children with short bowel syndrome

BACKGROUND

The present study was conducted to investigate the effects of Lactobacillus rhamnosus (also known as LGG) on intestinal permeability (IP) in children with short bowel syndrome (SBS).

PATIENTS AND METHODS

In a double-blind, placebo-controlled crossover clinical trial, baseline IP (ie, lactulose-to-mannitol ratio) was measured in subjects with SBS and healthy control subjects. Subjects with SBS received LGG or placebo for 4 weeks, followed by a 3-week washout before therapy was crossed over for another 4 weeks. IP, quantitative fecal cultures for Lactobacillus species (in colony-forming units [cfu] per gram of stool) and hydrogen breath test (HBT) were performed during LGG and placebo phases of therapy.

RESULTS

Twenty-one children (SBS, n = 9; control, n = 12) with a median age of 4.5 years (range 1.6-16.4 years) enrolled. Baseline IP measurements were similar in patients with SBS and control subjects: 0.08 +/- 0.06 (mean +/- SD) versus 0.07 +/- 0.05 (P = 1.0). IP was correlated with age in control subjects (r = -0.83, P = 0.001) but not among patients with SBS (r = -0.55, P = 0.16). Fecal colonization with Lactobacillus species did not differ during LGG versus placebo therapy (median 1.4 x 10(9) cfu/g [range 4.0 x 10(5) to 4.0 x 10(9) cfu/g] vs 6.0 x 10(9) cfu/g [1.0 x 10(3) to 1.0 x 10(10) cfu/g], respectively; P = 0.83). LGG therapy had no consistent effects on IP (P = 0.58) or its relationship with age (r = -0.40, P = 0.29), and was associated with conversion to positive HBT results in 1 subject.

CONCLUSIONS

In this sample of children with SBS, the IP was within normal limits but did not correlate with age. LGG therapy had no consistent effects on IP. These findings do not support empiric LGG therapy to enhance IP in children with SBS.

Epidermal growth factor and bombesin act synergistically to support intestinal adaptation in rats with massive small bowel resection

Intestinal adaptation is the most important event in short bowel syndrome following a massive small bowel resection. Effects of various growth factors and their synergism have been well documented in intestinal adaptation. This study aimed to compare the effect of two different trophic agents, epidermal growth factor (EGF) and bombesin (BBS), on intestinal adaptation following massive intestinal resection. Sprague-Dawley male rats were assigned to one of four groups after a 75% small bowel resection. Either EGF (90 microg/kg), BBS (10 microg/kg), EGF+BBS, or bovine serum albumin (BSA) were injected subcutaneously three times a day. The animals were killed 10 days after the operation. Weight loss and morphologic parameters such as mucosal thickness, villus height, crypt depth, villus-to-crypt ratio, and muscularis propria height were measured. In the EGF+BBS group, mucosal thickness was found to be significantly increased compared with the other study groups (p<0.05). Similarly, villus height was significantly increased only in the EGF+BBS group (p<0.05). In the BBS group, both villus height and mucosal thickness showed a slight increase, but the values were not statistically significant compared with the vehicle-treated group. There were no significant differences in any of the remaining parameters between the groups. The results of this study indicate that the gut hormones EGF and BBS act synergistically in facilitating the adaptive response of the remnant ileum to massive intestinal resection.

The effects of long-term total parenteral nutrition on gut mucosal immunity in children with short bowel syndrome: a systematic review

BACKGROUND: Short bowel syndrome (SBS) is defined as the malabsorptive state that often follows massive resection of the small intestine. Most cases originate in the newborn period and result from congenital anomalies. It is associated with a high morbidity, is potentially lethal and often requires months, sometimes years, in the hospital and home on total parenteral nutrition (TPN). Long-term survival without parenteral nutrition depends upon establishing enteral nutrition and the process of intestinal adaptation through which the remaining small bowel gradually increases its absorptive capacity. The purpose of this article is to perform a descriptive systematic review of the published articles on the effects of TPN on the intestinal immune system investigating whether long-term TPN induces bacterial translocation, decreases secretory immunoglobulin A (S-IgA), impairs intestinal immunity, and changes mucosal architecture in children with SBS. METHODS: The databases of OVID, such as MEDLINE and CINAHL, Cochran Library, and Evidence-Based Medicine were searched for articles published from 1990 to 2001. Search terms were total parenteral nutrition, children, bacterial translocation, small bowel syndrome, short gut syndrome, intestinal immunity, gut permeability, sepsis, hyperglycemia, immunonutrition, glutamine, enteral tube feeding, and systematic reviews. The goal was to include all clinical studies conducted in children directly addressing the effects of TPN on gut immunity. RESULTS: A total of 13 studies were identified. These 13 studies included a total of 414 infants and children between the ages approximately 4 months to 17 years old, and 16 healthy adults as controls; and they varied in design and were conducted in several disciplines. The results were integrated into common themes. Five themes were identified: 1) sepsis, 2) impaired immune functions: In vitro studies, 3) mortality, 4) villous atrophy, 5) duration of dependency on TPN after bowel resection. CONCLUSION: Based on this exhaustive literature review, there is no direct evidence suggesting that TPN promotes bacterial overgrowth, impairs neutrophil functions, inhibits blood's bactericidal effect, causes villous atrophy, or causes to death in human model.The hypothesis relating negative effects of TPN on gut immunity remains attractive, but unproven. Enteral nutrition is cheaper, but no safer than TPN. Based on the current evidence, TPN seems to be safe and a life saving solution.

Surgical therapy for short bowel syndrome

Patients with short bowel syndrome (SBS) suffer tremendous morbidity secondary to prolonged hospitalization and chronic parenteral nutrition (TPN). Overall, the majority of infants will adapt and ultimately become independent of TPN, but this process may require many months or years. Reasons for continued TPN dependency include bowel dysmotility, bacterial overgrowth, insufficient adaptation, or very short bowel length. It is this subpopulation of patients who may benefit from surgical procedures that optimize intestinal adaptation and increase the mucosal absorptive surface area. The goal of this review article is to summarize the process of intestinal adaptation and then to outline the surgical principles and techniques available to surgeons who treat this complicated group of patients.

Fasting breath hydrogen concentration in short bowel syndrome patients with colon incontinuity before and after antibiotic therapy

OBJECTIVE

Nutrition success in short bowel syndrome (SBS) depends on the intake nutrients and the intestinal absorption capacity. An evaluation of energy expenditure and oxidation of substrate can be obtained with indirect calorimetry by measuring O(2) and CO(2) in the respiration. Elevated colonic fermentation can occur in SBS, producing H(2) and CO(2), which can also be eliminated through respiration and as a consequence affect the results from indirect calorimetry. The objective of this study was to determine the fasting breath H(2) concentration and alterations before and after antibiotic therapy in patients with severe SBS with colon in continuity.

METHODS

The study was conducted in two phases. In phase 1, the fasting breath H(2) concentrations were measured in 10 patients with severe SBS with colon incontinuity and a control group of 10 healthy volunteers. In phase 2, the fasting breath H(2) concentrations were re-evaluated after treatment for 7 d with antibiotics in six patients with high rates of H(2). The analyses were performed with a gas chromatograph (microanalyzer DP; Quintron Instruments, Milwaukee, WI, USA), with results of breath hydrogen and methane concentration expressed in parts per million (ppm).

RESULTS

In phase 1, the levels of fasting breath H(2) were higher in the patients with severe SBS with colon incontinuity than in the healthy controls (32.00 +/- 17.77 versus 5.30 +/- 3.31 ppm; P < 0.001), with 7 of 10 patients presenting levels of H(2) above the normal rate (12 ppm). The presence of an ileocecal valve did not modify the results significantly. In phase 2, all six patients treated with antibiotics presented normalization in the levels of fasting breath H(2) (from 43.50 +/- 6.90 ppm to 1.33 +/- 1.03 ppm; P < 0.001) and concomitant improvement in the gastrointestinal symptoms.

CONCLUSIONS

In relation to the healthy controls, patients with SBS with colon incontinuity presented higher levels of fasting breath H(2). Antibiotic therapy normalized the levels of fasting breath H(2) and improved the gastrointestinal symptoms. We suggest that the breath H(2) test may be performed routinely in patients with SBS to diagnose elevated intestinal fermentation, prevent errors in the interpretation of the indirect calorimetry, and treat eventual associated gastrointestinal symptoms.

Methods used to study intestinal nutrient transport: past and present

BACKGROUND

Vitally important to the future of surgical care is the study of nutrition and nutrient uptake. Advances in this field of research have become increasingly dependent upon the disciplines of immunology, histology, and molecular biology. The fusion of these sciences has deepened our insight into the relationship between molecular structure and physiologic function. The ability to apply new technologies to this endeavor will enable the surgeon-investigator to further widen our understanding of nutrient transport.

MATERIALS AND METHODS

Medline and current literature review.

RESULTS AND CONCLUSIONS

We summarize many of the methods used to measure the uptake of nutrients by the intestinal epithelium, providing a historical perspective.

Update on management and treatment of short gut

Management of patients with short-bowel syndrome represents a formidable challenge. Aggressive treatment including nutritional care and anticipation of potential complications and rapid treatment of complications enhance outcome. New therapies offer the promise of significantly improving morbidity and mortality. Intestinal transplant is appropriate for infants who would otherwise die from liver disease, recurrent sepsis, or lack of venous access.

Short bowel syndrome in infants and children: an overview

Short bowel syndrome is a spectrum of malnutrition resulting from inadequate bowel length. In infant and pediatric patients, the most common causes are necrotizing enterocolitis, abdominal wall defects, jejunal ileal atresia, and mid gut volvulus. There appear to be regional variations in etiology. Since the publication of Wilmore's classic monograph in 1972, there have been significant improvements in monitoring and nutritional support. In the modern era, survival rate ranges from 80% to 94%, and the presence or absence the ileal cecal valve appears to not impact on mortality rate, but does significantly affect the length of time on total parenteral nutrition TPN. The most common morbidities remain sepsis, both central line related and bacterial overgrowth, and TPN cholestasis. Long-term recovery of these children often is remarkably normal, but there is a 10% to 15% incidence of neurologic and developmental defects. The clinical and ethical considerations around the care of infants with 20 to 40 cm of residual bowel remains controversial, as does the place of intestinal transplantation, especially in patients developing gut failure in infancy. Perioperative surgical decision making plays a critical role in the long-term outcome of these patients. This chapter presents an overview of the current status of care and outcome in this difficult population; these topics are further expanded in subsequent chapters.