Intestinal adaptation in short bowel syndrome

Serial transverse enteroplasty and nipple valve construction, two life saving techniques for patients with short bowel syndrome, a report of 5 cases

Background

Various abdominal pathologies end up with surgical resection of small intestine. When the small intestine remnant is too short for adequate fluid and micronutrients absorption, short bowel syndrome is diagnosed. The disabling condition needs a multidisciplinary approach to design parenteral nutrition, care for thrombotic, hepatic and infectious complications and gradually wean the patient from parenteral nutrition. Various surgical techniques have been introduced to increase absorptive mucosa and enhance the intestinal adaptation process. Serial transverse enteroplasty and nipple valve reconstruction are among the procedures, which will be discussed in the current article.

Case presentation

Herein, we presented 5 cases of short bowel syndrome as a consequence of abdominal laparotomies, patients were referred to our center to receive parenteral nutrition and to be prepared for the final autologous gastrointestinal reconstruction or intestinal transplantation, if indicated.

Conclusion

Patient’s age, performance status and bowel remnant length determines the appropriate technique for autologous gastrointestinal reconstruction. Serial transverse enteroplasty is designed to increase bowel’s length by creating zigzag patterns through dilated bowel loops. Presence of ileocecal valve is crucial to delay intestinal transit time and to prevent colonic bacterial transfer to ileum. Patient’s with ileocecal valve loss benefit from creating an artificial valve, namely, nipple valve.

The effect of pre-resection obesity on post-resection body composition after 75% small bowel resection in rats

In patients with short bowel syndrome, an elevated pre-resection Body Mass Index may be protective of post-resection body composition. We hypothesized that rats with diet-induced obesity would lose less lean body mass after undergoing massive small bowel resection compared to non-obese rats. Rats (CD IGS; age = 2 mo; N = 80) were randomly assigned to either a high-fat (obese rats) or a low-fat diet (non-obese rats), and fed ad lib for six months. Each diet group then was randomized to either underwent a 75% distal small bowel resection (massive resection) or small bowel transection with re-anastomosis (sham resection). All rats then were fed ad lib with an intermediate-fat diet (25% of total calories) for two months. Body weight and quantitative magnetic resonance-determined body composition were monitored. Preoperative body weight was 884 ± 95 versus 741 ± 75 g, and preoperative percent body fat was 35.8 ± 3.9 versus 24.9 ± 4.6%; high-fat vs. low fat diet, respectively (p < 0.0001); preoperative diet type had no effect on lean mass. Regarding total body weight, massive resection produced an 18% versus 5% decrease in high-fat versus low-fat rats respectively, while sham resection produced a 2% decrease vs. a 7% increase, respectively (p < 0.0001, preoperative vs. necropsy data). Sham resection had no effect on lean mass; after massive resection, both high-fat and low-fat rats lost lean mass, but these changes were not different between the latter two rat groups. The high-fat diet and low-fat diet induced obesity and marginal obesity, respectively. The massive resection produced greater weight loss in high-fat rats compared to low-fat rats. The type of dietary preconditioning had no effect on lean mass loss after massive resection. A protective effect of pre-existing obesity on lean mass after massive intestinal resection was not demonstrated.

Nutrition in Necrotizing Enterocolitis and Following Intestinal Resection

This review aims to discuss the role of nutrition and feeding practices in necrotizing enterocolitis (NEC), NEC prevention, and its complications, including surgical treatment. A thorough PubMed search was performed with a focus on meta-analyses and randomized controlled trials when available. There are several variables in nutrition and the feeding of preterm infants with the intention of preventing necrotizing enterocolitis (NEC). Starting feeds later rather than earlier, advancing feeds slowly and continuous feeds have not been shown to prevent NEC and breast milk remains the only effective prevention strategy. The lack of medical treatment options for NEC often leads to disease progression requiring surgical resection. Following resection, intestinal adaptation occurs, during which villi lengthen and crypts deepen to increase the functional capacity of remaining bowel. The effect of macronutrients on intestinal adaptation has been extensively studied in animal models. Clinically, the length and portion of intestine that is resected may lead to patients requiring parenteral nutrition, which is also reviewed here. There remain significant gaps in knowledge surrounding many of the nutritional aspects of NEC and more research is needed to determine optimal feeding approaches to prevent NEC, particularly in infants younger than 28 weeks and <1000 grams. Additional research is also needed to identify biomarkers reflecting intestinal recovery following NEC diagnosis individualize when feedings should be safely resumed for each patient.

Predictors of Intestinal Adaptation in Children

In children, short-bowel syndrome (SBS) accounts for two-thirds of the cases of intestinal failure, and motility disorders and congenital mucosal diarrheal disorders account for the remaining one-third. Children with SBS are supported primarily by parenteral nutrition, which is the single-most important therapy contributing to their improved prognosis. More than 90% of children with SBS who are cared for at experienced intestinal rehabilitation programs survive, and roughly 60% to 70% undergo intestinal adaptation and achieve full enteral autonomy. This article focuses on the predictors of pediatric intestinal adaptation and discusses the pathophysiology and clinical management of children with SBS.

Ileostomy for steroid-resistant acute graft-versus-host disease of the gastrointestinal tract

Steroid-resistant acute graft-versus-host disease (GVHD) of the gastrointestinal tract associates with important morbidity and mortality. While high-dose steroids are the established first-line therapy in GVHD, no second-line therapy is generally accepted. In this analysis of 65 consecutive patients with severe, steroid-resistant, intestinal GVHD (92% stage 4), additional ileostomy surgery significantly reduced overall mortality (hazard ratio 0.54; 95% confidence interval, 0.36-0.81; p = 0.003) compared to conventional GVHD therapy. Median overall survival was 16 months in the ileostomy cohort compared to 4 months in the conventional therapy cohort. In the ileostomy cohort, both infectious- and GVHD-associated mortality were reduced (40% versus 77%). Significantly declined fecal volumes (p = 0.001) after surgery provide evidence of intestinal adaptation following ileostomy. Correlative studies indicated ileostomy-induced immune-modulation with a > 50% decrease of activated T cells (p = 0.04) and an increase in regulatory T cells. The observed alterations of the patients' gut microbiota may also contribute to ileostomy's therapeutic effect. These data show that ileostomy induced significant clinical responses in patients with steroid-resistant GVHD along with a reduction of pro-inflammatory immune cells and changes of the intestinal microbiota. Ileostomy is a treatment option for steroid-resistant acute GVHD of the gastrointestinal tract that needs further validation in a prospective clinical trial.

Enteral nutrition in pediatric intestinal failure: does initial feeding impact on intestinal adaptation?

Primary IF can be due to impaired gut length or impaired gut function; short bowel syndrome (SBS) is the leading cause of IF. In IF patients complete enteral starvation should be avoided whenever possible and enteral/oral nutrition (EN/ON) should be employed at the maximum tolerated amount in each phase of the clinical evolution of IF. Intraluminal nutrients have stimulatory effects on epithelial cells and on trophism that enhance intestinal adaptation. Areas covered: Evidence for nutritional interventions in pediatric IF is limited and of poor quality. Clinical practice in SBS feeding are more 'experience-based' rather than 'evidence-based' and this dearth of clinical evidence is partly due to the rarity of this condition. This review updates knowledge concerning the impact of the initial diet with EN/ON in neonatal onset SBS in the process of bowel adaption. Expert commentary: Human milk resulted the preferred starting diet and it is generally combined with amino-acids (AAs) in Northern America and with hydrolyzed proteins (HFs) in Europe; polymeric diet is rarely employed. HFs were not more effective than AAs in promoting intestinal adaptation.

Marked stem/progenitor cell expansion occurs early after murine ileostomy: a new model

BACKGROUND

Improving treatment for short bowel syndrome requires a better understanding of how intestinal adaptation is affected by factors like mechanoluminal stimulation. We hypothesized that in mice, luminal diversion via an ileostomy would drive adaptive changes similar to those seen in human intestine after diversion while offering the opportunity to study the immediate events after resection that precede intestinal adaptation.

MATERIALS AND METHODS

With Institutional Animal Care and Use Committee approval, a distal ileostomy with a long distal Hartman's was created in 9- to 14-week-old C57/B6 mice (n = 8). Control mice only had a midline laparotomy without stoma formation (n = 5). A rim of tissue from the proximal stoma was resected as a historical control for the proximal segment. Postoperatively, mice received a high-protein liquid diet and water ad libitum. On day 3, tissue from both the proximal and distal limbs were collected for histologic and RNA analysis. Morphometric measures, immunofluorescent antigen detection, and RNA expression were compared with Student paired t-tests with a P value < 0.05 considered significant.

RESULTS

At 3 d, survival for mice with an ileostomy was 87% and average weight loss was 12.5% of initial weight compared to 6.05% for control mice. Compared to the distal limb, the proximal limb in mice with an ileostomy demonstrated significantly taller villi with deeper and wider crypts. The proximal limb also had decreased expression of intestinal stem cell markers lgr5, bmi1, sox9, and ascl2. Fewer goblet and enteroendocrine cells per hemivillus were also noted in the proximal limb. In control mice, none of these measures were significant between proximal and distal ileum except for villus height.

CONCLUSIONS

This new murine ileostomy model allows study of intestinal adaptation without intestinal anastomosis, which can be technically challenging and morbid.

Intestinal Failure in Children

Children with intestinal failure have had improved survival, particularly those with extreme short bowel syndrome, over the last 10-15 y. This has been attributed to better understanding of the pathophysiology of intestinal failure, improvement in line care, recognition of the importance of a team approach as well as the progress of intestinal transplant as a viable option. Parenteral nutrition remains the cornerstone for the continual survival of these patients. This review will cover contemporary approaches to intestinal failure including post surgical approaches, non-transplant surgery, dietetic and medication approaches during the adaptation process, considerations for home parenteral nutrition and latest in intestinal transplantation.

Intestinal Failure: Adaptation, Rehabilitation, and Transplantation

Intestinal failure (IF) is a state in which the nutritional demands are not met by the gastrointestinal absorptive surface. A majority of IF cases are associated with short-bowel syndrome, which is a result of malabsorption after significant intestinal resection for numerous reasons, some of which include Crohn's disease, vascular thrombosis, and radiation enteritis. IF can also be caused by obstruction, dysmotility, and congenital defects. Recognition and management of IF can be challenging, given the complex nature of this condition. This review discusses the management of IF with a focus on intestinal rehabilitation, parenteral nutrition, and transplantation.

Adult zebrafish intestine resection: a novel model of short bowel syndrome, adaptation, and intestinal stem cell regeneration

Loss of significant intestinal length from congenital anomaly or disease may lead to short bowel syndrome (SBS); intestinal failure may be partially offset by a gain in epithelial surface area, termed adaptation. Current in vivo models of SBS are costly and technically challenging. Operative times and survival rates have slowed extension to transgenic models. We created a new reproducible in vivo model of SBS in zebrafish, a tractable vertebrate model, to facilitate investigation of the mechanisms of intestinal adaptation. Proximal intestinal diversion at segment 1 (S1, equivalent to jejunum) was performed in adult male zebrafish. SBS fish emptied distal intestinal contents via stoma as in the human disease. After 2 wk, S1 was dilated compared with controls and villus ridges had increased complexity, contributing to greater villus epithelial perimeter. The number of intervillus pockets, the intestinal stem cell zone of the zebrafish increased and contained a higher number of bromodeoxyuridine (BrdU)-labeled cells after 2 wk of SBS. Egf receptor and a subset of its ligands, also drivers of adaptation, were upregulated in SBS fish. Igf has been reported as a driver of intestinal adaptation in other animal models, and SBS fish exposed to a pharmacological inhibitor of the Igf receptor failed to demonstrate signs of intestinal adaptation, such as increased inner epithelial perimeter and BrdU incorporation. We describe a technically feasible model of human SBS in the zebrafish, a faster and less expensive tool to investigate intestinal stem cell plasticity as well as the mechanisms that drive intestinal adaptation.

Essential role of angiotensin receptors in the modulation of intestinal epithelial cell apoptosis

BACKGROUND AND AIM

We have previously shown that angiotensin II (ANGII) plays an important role in the regulation of the apoptosis of intestinal epithelial cells (IECs). In this study, we investigated the pathway by which ANGII modulates apoptosis of the IECs.

METHODS

Epithelial cells (HT-29) were cultured; the ANGII receptor type-1 (AT1R) inhibitor (Losartan) and ANGII receptor type-2 (AT2R) inhibitor (PD123319) were used separately to block the ANGII receptor. Flow cytometry was used to detect the apoptosis of the IECs. In the in vivo study, Sprague-Dawley rats were divided into 4 groups: sham group, which received a ileum transection (n = 6); sham + angiotensin-converting enzyme inhibitor (ACE-I) group, which received a ileum transection, and lavage with ACE-I (enalaprilat 2 mg · kg⁻¹ day⁻¹) (n = 6); short bowel syndrome (SBS) group, which received a 70% mid-intestinal resection (n = 6); and SBS + ACE-I group, which received a 70% mid-intestinal resection, and lavage with enalaprilat (2 mg · kg⁻¹ day⁻¹) (n = 6). Sampling was done 10 days after surgery. The expression of ANGII receptors Bax and Bcl-2 was detected with immunofluorescence, real-time-polymerase chain reaction, and Western blot methods.

RESULTS

Massive small bowel resection led to a significant increase in epithelial cells apoptosis, and the addition of ACE-I to SBS rat significantly attenuated this increase in apoptosis. AT1R expression on intestinal mucosa surface decreased after small bowel resection. Pretreatment with the AT1R antagonist Losartan significantly attenuated the increase of epithelial cell apoptosis caused by ANGII administration. Moreover, the Bcl-2/Bax ratio was found to be increased in cells pretreated with Losartan, which indicates a proapoptotic role of AT1R in cultured HT-29 cell lines.

CONCLUSIONS

These findings suggest that ANGII plays an important role in the regulation of apoptosis of the IECs. AT1R may be of crucial importance for the modulation of intestinal EC apoptosis.

Inhibition of ACE activity contributes to the intestinal structural compensation in a massive intestinal resection rat model

BACKGROUND

Intestinal adaptation in short bowel syndrome (SBS) consists of increased epithelial cells (ECs) proliferation as well as apoptosis. Angiotensin-converting enzyme (ACE) has been shown to regulate ECs apoptosis. In this study, we investigated the effect of ACE inhibition on intestinal adaptation after small bowel resection (SBR) in a rat model.

METHODS

Sprague-Dawley rats were used and were divided into four groups: (1) Sham group received an ileum transection (n = 6); (2) Sham + ACE-I group received an ileum transaction and lavage with ACE inhibitor (ACE-I, enalaprilat, 2 mg/kg/day) (n = 6); (3) SBS group received a 70 % mid-intestinal resection (n = 6); (4) SBS + ACE-I group received a 70 % mid-intestinal resection and lavage with enalaprilat (2 mg/kg/day) (n = 6). Sampling was done 10 days after surgery. ECs apoptosis was studied by TUNEL staining. ACE, angiotensin II (ANGII) receptor type 1 (AT1R) and receptor type 2 (AT2R) expressions were detected with RT-PCR and immunofluorescent confocal microscopy.

RESULTS

SBR leads to significant intestinal hypertrophy. The addition of ACE-I to SBS rat resulted in a significant decline in ECs apoptosis. ACE mRNA expression was significantly elevated after SBS creation (0.24 ± 0.07 vs. 0.42 ± 0.11), and ACE-I administration further increased mucosal ACE mRNA expression (0.54 ± 0.12). Interestingly, AT1R mRNA expression showed a significant decline in the SBS group compared to Sham levels, and ACE-I administration increased AT1R mRNA expression to Sham levels. No significant difference in AT2R mRNA expression was found between Sham and SBS group.

CONCLUSION

These results offer further insight into the role of ACE on intestinal mucosal remolding after massive bowel resection. ACE-I may be beneficial to SBS patients via a reduction of the apoptotic rate, thus facilitating the degree of adaptation.

Apoptosis: why and how does it occur in biology?

The literature on apoptosis has grown tremendously in recent years, and the mechanisms that are involved in this programmed cell death pathway have been enlightened. It is now known that apoptosis takes place starting from early development to adult stage for the homeostasis of multicellular organisms, during disease development and in response to different stimuli in many different systems. In this review, we attempted to summarize the current knowledge on the circumstances and the mechanisms that lead to induction of apoptosis, while going over the molecular details of the modulator and mediators of apoptosis as well as drawing the lines between programmed and non-programmed cell death pathways. The review will particularly focus on Bcl-2 family proteins, the role of different caspases in the process of apoptosis, and their inhibitors as well as the importance of apoptosis during different disease states. Understanding the molecular mechanisms involved in apoptosis better will make a big impact on human diseases, particularly cancer, and its management in the clinics.

Proteomic analysis of the intestinal adaptation response reveals altered expression of fatty acid binding proteins following massive small bowel resection

Intestinal adaptation in response to the loss of the small intestine is essential to restore enteral autonomy in patients who have undergone massive small bowel resection (MSBR). In a proportion of patients, intestinal function is not restored, resulting in chronic intestinal failure (IF). Early referral of such patients for transplant provides the best prognosis; however, the molecular mechanisms underlying intestinal adaptation remain elusive and there is currently no convenient marker to predict whether patients will develop IF. We have investigated the adaptation response in a well-characterized porcine model of intestinal adaptation. 2D DIGE analysis of ileal epithelium from piglets recovering from massive small bowel resection (MSBR) identified over 60 proteins that changed specifically in MSBR animals relative to nonoperational or sham-operated controls. Three fatty acid binding proteins (L-FABP, FABP-6, and I-FABP) showed changes in MSBR animals. The expression changes and localization of each FABP were validated by immunoblotting and immunohistochemical analysis. FABP expression changes in MSBR animals occurred concurrently with altered triglyceride and bile acid metabolism as well as weight gain. The observed FABP expression changes in the ileal epithelium occur as part of the intestinal adaptation response and could provide a clinically useful marker to evaluate adaptation following MSBR.

Leptin affects intestinal epithelial cell turnover in correlation with leptin receptor expression along the villus-crypt axis after massive small bowel resection in a rat

In this study, we examine the responsiveness of intestinal epithelial cell turnover to leptin (LEP) in correlation with leptin receptor (LEPr) expression along the villus-crypt axis in a rat with short bowel syndrome (SBS). Adult rats underwent either a 75% intestinal resection or a transection. SBS-LEP rats underwent bowel resection and were treated with LEP starting from the fourth postoperative day. Parameters of intestinal adaptation, enterocyte proliferation, and enterocyte apoptosis were determined at sacrifice. RT-PCR technique was used to determine Bax and Bcl-2 gene expression in ileal mucosa. Villus tips, lateral villi, and crypts were separated using laser capture microdissection. LEPr expression for each compartment was assessed by quantitative real-time PCR (Taqman). Treatment with LEP significantly stimulated all parameters of adaptation. LEPr expression in crypts significantly increased in SBS rats (vs Sham rats) and was accompanied by a significant increase in enterocyte proliferation and decreased apoptosis after LEP administration. A significant increase in LEPr expression at the tip of the villus in SBS rats was accompanied by decreased cell apoptosis. In conclusion LEP accelerated enterocyte turnover and stimulated intestinal adaptation. The effect of LEP on enterocyte proliferation and enterocyte apoptosis correlated with receptor expression along the villus-crypt axis.

Modulation of mouse intestinal epithelial cell turnover in the absence of angiotensin converting enzyme

Angiotensin converting enzyme (ACE) has been shown to be involved in regulation of apoptosis in nonintestinal tissues. This study examined the role of ACE in the modulation of intestinal adaptation utilizing ACE knockout mice (ACE-/-). A 60% small bowel resection (SBR) was used, since this model results in a significant increase in intestinal epithelial cell (EC) apoptosis as well as proliferation. Baseline villus height, crypt depth, and intestinal EC proliferation were higher, and EC apoptosis rates were lower in ACE-/- compared with ACE+/+ mice. After SBR, EC apoptosis rates remained significantly lower in ACE-/- compared with ACE+/+ mice. Furthermore, villus height and crypt depth after SBR continued to be higher in ACE-/- mice. The finding of a lower bax-to-bcl-2 protein ratio in ACE-/- mice may account for reduced EC apoptotic rates after SBR in ACE-/- compared with ACE+/+ mice. The baseline higher rate of EC proliferation in ACE-/- compared with ACE+/+ mice may be due to an increase in the expression of several EC growth factor receptors. In conclusion, ACE appears to have an important role in the modulation of intestinal EC apoptosis and proliferation and suggests that the presence of ACE in the intestinal epithelium has a critical role in guiding epithelial cell adaptive response.

Intestinal intraepithelial lymphocyte derived angiotensin converting enzyme modulates epithelial cell apoptosis

BACKGROUND & AIMS

Intestinal adaptation in short bowel syndrome (SBS) consists of increased epithelial cell (EC) proliferation as well as apoptosis. Previous microarray analyses of intraepithelial lymphocytes (IEL) gene expression after SBS showed an increased expression of angiotensin converting enzyme (ACE). Because ACE has been shown to promote alveolar EC apoptosis, we examined if IEL-derived ACE plays a role in intestinal EC apoptosis.

METHODS

Mice underwent either a 70% mid-intestinal resection (SBS group) or a transection (Sham group) and were studied at 7 days. ACE expression was measured, and ACE inhibition (ACE-I, enalaprilat) was used to assess ACE function.

RESULTS

IEL-derived ACE was significantly elevated in SBS mice. The addition of an ACE-I to SBS mice resulted in a significant decline in EC apoptosis. To address a possible mechanism, tumor necrosis factor alpha (TNF-alpha) mRNA expression was measured. TNF-alpha was significantly increased in SBS mice, and decreased with ACE-I. Interestingly, ACE-I was not able to decrease EC apoptosis in TNF-alpha knockout mice.

CONCLUSIONS

This study shows a previously undescribed expression of ACE by IEL. SBS was associated with an increase in IEL-derived ACE. ACE appears to be associated with an up-regulation of intestinal EC apoptosis. ACE-I significantly decreased EC apoptosis.

Short bowel syndrome

Treatment of short bowel syndrome (SBS) is often a difficult endeavor due to the high variability among patients with SBS in regard to remaining anatomical structure and functional capacity. Research efforts to substantiate the use of existing therapies in the treatment of SBS are ongoing, with newer developments yet to be fully explored. Current therapy for SBS begins with the implementation of a modified diet based on the presence or absence of the colon. Patients with difficulty ingesting enough nutrients and fluids for weight maintenance and fluid balance may benefit from nocturnal enteral nutrition and hydration. Those with inadequate absorptive capacity despite maximization of oral and enteral intake will need parenteral nutrition (PN) or hydration. Medications, including antisecretory agents, antidiarrheals, pancreatic enzymes, bile acid sequestrants, and antibiotics, often are useful in abating symptoms commonly associated with SBS. Growth factors, including recombinant human growth hormone and glucagon-like peptide 2, may be trialed to stimulate intestinal adaptation and enhance absorption in PN-dependent SBS patients. The gradual refinement of surgical procedures for SBS, including small bowel transplantation, has led to improved outcomes, and early referral of SBS patients to centers of excellence will optimize care.

Biodistribution of the radiophamarceutical sodium pertechnetate (Na99mTcO4) after massive small bowel resection in rats

PURPOSE: To evaluate the biodistribution of sodium pertecnetate (Na99mTcO4) in organs and tissues, the morphometry of remnant intestinal mucosa and ponderal evolution in rats subjected to massive resection of the small intestine. METHODS: Twenty-one Wistar rats were randomly divided into three groups of 7 animals each. The short bowel (SB) group was subjected to massive resection of the small intestine; the control group (C) rats were not operated on, and soft intestinal handling was performed in sham rats. The animals were weighed weekly. On the 30th postoperative day, 0.l mL of Na99mTcO4, with mean activity of 0.66 MBq was injected intravenously into the orbital plexus. After 30 minutes, the rats were killed with an overdose of anesthetic, and fragments of the liver, spleen, pancreas, stomach, duodenum, small intestine, thyroid, lung, heart, kidney, bladder, muscle, femur and brain were harvested. The biopsies were washed with 0.9% NaCl.,The radioactivity was counted using Gama Counter WizardTM 1470, PerkinElmer. The percentage of radioactivity per gram of tissue (%ATI/g) was calculated. Biopsies of the remaining jejunum were analysed by HE staining to obtain mucosal thickness. Analysis of variance (ANOVA) and the Tukey test for multiple comparisons were used, considering p<0.05 as significant. RESULTS: There were no significant differences in %ATI/g of the Na99mTcO4 in the organs of the groups studied (p>0.05). An increase in the weight of the SB rats was observed after the second postoperative week. The jejunal mucosal thickness of the SB rats was significantly greater than that of C and sham rats (p<0.05). CONCLUSION: In rats with experimentally-produced short bowel syndrome, an adaptive response by the intestinal mucosa reduced weight loss. The biodistribution of Na99mTcO4 was not affected by massive intestinal resection, suggesting that short bowel syndrome is not the cause of misleading interpretation, if an examination using this radiopharmaceutical is indicated.

Increase of phosphatidylethanolamine N-methyltransferase activity in the small bowel brush-border membrane after massive intestinal distal resection in rats

Phosphatidylcholine plays an important role for the structure and function of the cell membrane, and its synthesis from phosphatidylethanolamine is catalyzed by phosphatidylethanolamine N-methyltransferase (PEMT). This study investigates changes in PEMT activity in the intestinal brush border membrane after extensive distal enterectomy (60%) in 40 Wistar rats. Four groups, each of 10 rats, were killed immediately after surgery (day 0) and on the 7th, 14th and 28th day postoperatively. Samples from jejunum were collected for histomorphometry and PEMT activity was determined by measuring the incorporation of [(3)H]-methyl groups from S-adenosyl-L-(methyl-(3)H)-methionine into phospholipids. Enterectomy induced 30%, 48% and 21% increases in the jejunum villus cell population, and 32%, 81%, and 32% in the crypt cell population at postoperative days 7, 14, and 28, respectively. PEMT activity increased 41% at day 14, suggesting functional differentiation, remaining at this level until day 28, when a reduction in the epithelial cell population was observed, thus indicating that adaptation was completed. The observed increase in PEMT-specific activity in the residual intestine suggests that extensive enterectomy stimulates the synthesis of phosphatidylcholine by the PEMT-controlled pathway.

Hyaluronic acid based materials for intestine tissue engineering: a morphological and biochemical study of cell-material interaction

A wide number of gastro-intestinal disorders are associated with structural alterations of this district leading to an impaired gastrointestinal function. The study of cell material interactions represents one of the major issues for the development of tissue engineering purposes. Benzyl esters of hyaluronic acid are promising materials because they exhibit good tissue compatibility and are available in various configurations. In this work they have been studied for the possible application of intestinal cell growth and functioning. The preliminary investigation on the morphologic and biochemistry data obtained by monitoring the growth and differentiation of intestinal epithelial cells on two hyaluronic acid benzyl esters is reported. Two types of materials structures were studied: a three dimensional matrix and a macroporous flat sheet membrane. Caco-2 cell line was used: these cells undergo spontaneous enterocytic differentiation after several days in culture. The differentiation status of these cells grown on different materials was used as a parameter of biocompatibility and cell functioning. The status of cell growth and differentiation was monitored by studying cell morphology using scanning electron microscopy. The results obtained were confirmed by biochemical determinations. Although both the configurations of the two polymers exhibited good compatibility with respect to intestinal cells, only the flat sheet membrane proved to induce cell differentiation, leading us to the conclusion that it is a promising substrate for the proposed application.

Stimulation of colonic mucosal growth associated with oxidized redox status in rats

Limited data in animal models suggest that colonic mucosa undergoes adaptive growth following massive small bowel resection (SBR). In vitro data suggest that intestinal cell growth is regulated by reactive oxygen species and redox couples [e.g., glutathione (GSH)/glutathione disulfide (GSSG) and cysteine (Cys)/cystine (CySS) redox]. We investigated the effects of SBR and alterations in redox on colonic growth indexes in rats after either small bowel transection (TX) or 80% midjejunoileal resection (RX). Rats were pair fed +/- blockade of endogenous GSH synthesis with buthionine sulfoximine (BSO). Indexes of colonic growth, proliferation, and apoptosis and GSH/GSSG and Cys/CySS redox potentials (E(h)) were determined. RX significantly increased colonic crypt depth, number of cells per crypt, and epithelial cell proliferation [crypt cell bromodeoxyuridine (BrdU) incorporation]. Administration of BSO markedly decreased colonic mucosal GSH, GSSG, and Cys concentrations in both TX and RX groups, with a resultant oxidation of GSH/GSSG and Cys/CySS E(h). BSO did not alter colonic crypt cell apoptosis but significantly increased all colonic mucosal growth indexes (crypt depth, cells/crypt, and BrdU incorporation) in both TX and RX groups in a time- and dose-dependent manner. BSO significantly decreased plasma GSH and GSSG, oxidized GSH/GSSG E(h), and increased plasma Cys and CySS concentrations. Collectively, these data provide in vivo evidence indicating that oxidized colonic mucosal redox status stimulates colonic mucosal growth in rats. The data also suggest that GSH is required to maintain normal colonic and plasma Cys/CySS homeostasis in these animal models.

Gene expression in the adapting small bowel after massive small bowel resection

BACKGROUND

Intestinal adaptation occurs in the residual bowel following the loss or resection of a proportion of the small bowel. The purpose of the adaptive response is to return absorptive and digestive properties to near normal levels. This study employed a rat model of massive small bowel resection (MSBR) to study the adaptive response in the residual terminal ileum and the jejunum. The time points were chosen to reflect changes in gene expression early on in the response, because these are the genes that alter to initiate and maximize the response observed during adaptation.

METHODS

Sprague Dawley rats underwent an 80% resection. Differential display polymerase chain reaction (DD-PCR) analysis was performed on mRNA extracted from the remnant ileum and jejunum 0, 1, 2, 4, and 7 days post-MSBR.

RESULTS

DD-PCR identified 11 genes that were possibly regulated following MSBR. Genes confirmed to be regulated were 16S ribosomal RNA, lymphocyte antigen 6 (LY6)-like molecule, Krüppel-like factor-3 (KLF-3), G-protein-binding protein (CRFG), system A transporter 2 (SAT2), and an intestine-specific gene (similar to mKIAA0493).

CONCLUSIONS

DD-PCR analysis showed regulation of a number of genes not previously known to be involved in adaptation after MSBR or previously characterized in the intestine. These genes may be important in bringing about the complement of changes seen during the adaptive response.

Extensive small bowel resection in dogs and cats: 20 cases (1998–2004)

OBJECTIVE

To determine outcome in dogs and cats that underwent extensive (ie, > 50%) resection of the small intestine and identify factors associated with outcome.

DESIGN

Retrospective case series.

ANIMALS

13 dogs and 7 cats.

PROCEDURE

Medical records were reviewed, and follow-up information was obtained.

RESULTS

In all 7 cats and in 8 of the 13 dogs, extensive intestinal resection was performed because of a foreign body. Mean+/-SD estimated percentage of intestine that was removed was 68+/-14% (range, 50% to 90%). Two dogs were euthanized 3 days after surgery because of dehiscence of the surgical site and development of septic peritonitis; 1 dog died of acute respiratory distress syndrome 5 days after surgery. The remaining 10 dogs and 7 cats were discharged from the hospital, and follow-up information was available for 15 of the 17. Median survival time was 828 days, and 12 of the 15 animals for which long-term follow-up information was available had good outcomes. However, none of the factors examined, including percentage of intestine resected, were significantly associated with outcome.

CONCLUSIONS AND CLINICAL RELEVANCE

Most dogs and cats that underwent extensive resection of the small intestine had a good outcome. The amount of intestine resected was not associated with outcome. These data may be useful in providing prognostic information in cases of extensive small intestinal resection.

Influence of the site of small bowel resection on intestinal epithelial cell apoptosis

Massive small bowel resection (SBR) results in a significant increase in intestinal epithelial cell (EC) proliferation as well as apoptosis. Because the site of SBR (proximal (P) vs. distal (D)) affects the degree of intestinal adaptation, we hypothesized that different rates of EC apoptosis would also be found between P-SBR and D-SBR models. Wild-type C57BL/6J mice underwent: (1) 60% P-SBR, (2) 60% D-SBR, or (3) SHAM-operation (transaction-reanastomosis) at the mid-gut point. Mice were sacrificed after 7 days. EC apoptosis was measured by TUNEL staining. EC-related apoptotic gene expression including intrinsic and extrinsic pathways was measured with reverse transcriptase-polymerase chain reaction. Bcl-2 and bax protein expression were analyzed by Western immunoblotting. Both models of SBR led to significant increases in villus height and crypt depth; however, the morphologic adaptation was significantly higher after P-SBR compared to D-SBR (P<0.01). Both models of SBR led to significant increases in enterocyte apoptotic rates compared to respective sham levels; however, apoptotic rates were 2.5-fold higher in ileal compared to jejunal segments (P<0.01). P-SBR led to significant increases in bax (pro-apoptotic) and Fas expression, whereas D-SBR resulted in a significant increase in TNF-alpha expression (P<0.01). EC apoptosis seems to be an important component of intestinal adaptation. The significant difference in EC apoptotic rates between proximal and distal intestinal segments appeared to be due to utilization of different mechanisms of action.

Intestinal adaptation after massive intestinal resection

Patients with short bowel syndrome require long term parenteral nutrition support. However, after massive intestinal resection the intestine undergoes adaptation and nutritional autonomy may be obtained. Given that the complications of parenteral nutrition may be life threatening or result in treatment failure and the need for intestinal transplantation, a more attractive option is to wean patients off nutrition support by optimising the adaptive process. The article examines the evidence that after extensive small bowel resection adaptation occurs in humans and focuses on the factors that influence adaptation and the strategies that have been used to optimise this process. The review is based on an English language Medline search with secondary references obtained from key articles. There is evidence that adaptation occurs in humans. Adaptation is a complex process that results in response to nutrient and non-nutrient stimuli. Successful and reproducible strategies to improve adaptation remain elusive despite an abundance of experimental data. Nevertheless given the low patient survival and quality of life associated with other treatments for irreversible intestinal failure it is imperative that clinical research continues into the optimisation of the adaptation.

Intestinal adaptation after massive intestinal resection

Patients with short bowel syndrome require long term parenteral nutrition support. However, after massive intestinal resection the intestine undergoes adaptation and nutritional autonomy may be obtained. Given that the complications of parenteral nutrition may be life threatening or result in treatment failure and the need for intestinal transplantation, a more attractive option is to wean patients off nutrition support by optimising the adaptive process. The article examines the evidence that after extensive small bowel resection adaptation occurs in humans and focuses on the factors that influence adaptation and the strategies that have been used to optimise this process. The review is based on an English language Medline search with secondary references obtained from key articles. There is evidence that adaptation occurs in humans. Adaptation is a complex process that results in response to nutrient and non-nutrient stimuli. Successful and reproducible strategies to improve adaptation remain elusive despite an abundance of experimental data. Nevertheless given the low patient survival and quality of life associated with other treatments for irreversible intestinal failure it is imperative that clinical research continues into the optimisation of the adaptation.

Intestinal rehabilitation and the short bowel syndrome: part 2

The management of patients with intestinal failure due to short bowel syndrome is complex, requiring a comprehensive approach that frequently necessitates long-term, if not life-long, use of parenteral nutrition. Despite tremendous advances in the provision of parenteral nutrition over the past three decades, which have allowed significant improvements in the survival and quality of life of these patients, this mode of nutritional support carries with it significant risks to the patient, is very costly, and ultimately, does not attempt to improve the function of the remaining bowel. Intestinal rehabilitation refers to the process of restoring enteral autonomy, and thus, allowing freedom from parenteral nutrition, usually by means of dietary, medical, and occasionally, surgical strategies. While recent investigations have focused on the use of trophic substances to increase the absorptive function of the remaining gut, whether intestinal rehabilitation occurs as a consequence of enhanced bowel adaptation or is simply a result of an optimized, comprehensive approach to the care of these patients remains unclear. In Part 1 of this review, we provided an overview of short bowel syndrome and pathophysiological considerations related to the remaining bowel anatomy in these patients. We also reviewed intestinal adaptation and factors that may enhance the adaptive process, focusing on evidence derived from animal studies. In Part 2, relevant data on the development of intestinal adaptation in humans are reviewed as is the general management of short bowel syndrome. Lastly, the potential benefits of a multidisciplinary intestinal rehabilitation program in the care of these patients are also discussed.

Effects of bowel rehabilitation and combined trophic therapy on intestinal adaptation in short bowel patients

AIM: To evaluate the effects of bowel rehabilitation and combined trophic therapy on intestinal adaptation in short bowel patients.

METHODS: Thirty-eight patients with severe short-bowel syndrome (SBS) were employed in the present study, whose average length of jejunum-ileum was 35.8 ± 21.2 cm. The TPN treatment was initiated early to attain positive nitrogen balance and prevent severe weight loss. The TPN composition was designated to be individualized and altered when necessary. Enteral feeding was given as soon as possible after resection and increased gradually. Meals were distributed throughout the day. Eight patients received treatment of growth hormone (0.14 mg/kg•d) and glutamine (0.3 g/kg•d) for 3 wk. D-xylose test, ¹⁵N-Gly trace test and ¹³C-palmitic acid breath test were done to determine the patients' absorption capability.

RESULTS: Thirty-three patients maintained well body weight and serum albumin concentration. The average time of follow-up for 33 survival patients was 5.9 ± 4.3 years. Twenty-two patients weaned from TPN with an average TPN time of 9.5 ± 6.6 mo. Two patients, whose whole small bowel, ascending and transverse colon were resected received home TPN. An other 9 patients received parenteral or enteral nutritional support partly as well as oral diet. Three week rhGH + GLN therapy increased nutrients absorption but the effects were transient.

CONCLUSION: By rehabilitation therapy, most short bowel patients could wean from parenteral nutrition. Dietary manipulation is an integral part of the treatment of SBS. Treatment with growth hormone and glutamine may increase nutrients absorption but the effects are not sustained beyond the treatment period.

Role of specific amino acids in nutritional support

Attempts have been made over the past decade to evaluate the role of specific amino acids in the nutritional support of surgical patients. Particular attention has been paid to the branched-chain amino acids, glutamine, and a collection of compounds that have been referred to as 'immunonutrients'. The present review provides an overview of the rationale behind the use of these nutrients and reviews information about their role in patients undergoing surgery. In general, although the use of immunonutrients enhances the nutritional status of patients, and although a number of clinical trials have claimed clinical advantages, there are still doubts about their clinical utility and concerns about their high cost.

Gene alteration of intestinal intraepithelial lymphocytes in response to massive small bowel resection

BACKGROUND

The intestinal adaptive response [increased epithelial cell (EC) proliferation and apoptosis] after massive small bowel resection (SBR) is partially controlled by intraepithelial lymphocytes (IEL). To identify IEL factors contributing to EC adaptation post-SBR we utilized microarray assays.

METHODS

Mice underwent a 70% SBR (SBR1w/SBR4w) or sham operation (Sham1w/Sham4w). After 1 or 4 weeks (1w, 4w) small bowel was harvested, and IEL isolated. Determination of the EC-proliferation rate used BrdU incorporation, and of the EC-apoptotic rate used Annexin V staining. Affymetrix system microarrays (12,491 genes) were performed to examine IEL-mRNA expression. Results were considered significant if fold-change (FC) between groups was >2 and P<0.05 (F-test), or FC>3 and 0.05> P >0.01, or FC>4 and P>0.05. Significant genes were confirmed by conventional RT-PCR.

RESULTS

The SBR EC-proliferation rate increased significantly in both 1w and 4w groups compared to Sham: SBR1w 0.24+/-0.07 vs. Sham1w 0.12+/-0.02 (P=0.03); SBR4w 0.35+/-0.04 vs. Sham4w 0.19+/-0.02 ( P<0.01). The EC-apoptotic rate was unchanged in the 1w group, but significantly differed from controls after 4 weeks: SBR4w 39.92+/-6.78 vs. Sham4w 12.56+/-6.44 ( P<0.01). Microarray results were analyzed to identify potential growth-modifying IEL genes. The following were identified (function in parenthesis; A, apoptosis; P, proliferation): lipocalin 2 (promotes A), angiotensin converting enzyme (increases A), Rap2 interacting protein (reduces A, promotes P), amphiregulin (promotes P) and leucine-rich-alpha2-glycoprotein (promotes A, reduces P). Based on RT-PCR results these genes showed significant changes between groups. The increase in ACE at 1w preceded the observed apoptotic changes. The alterations in lipocalin 2, Rap2 and amphiregulin at 4w coincided with the marked changes in growth and apoptosis in the SBR mice.

CONCLUSIONS

IEL undergo temporal changes after SBR. These findings provide profound insight into potential IEL-dependent regulation of EC homeostasis post-SBR.