Results of the Paris Program: Ten Years of Pediatric Intestinal Transplantation

Innovations in Immunosuppression for Intestinal Transplantation

It has been 57 years since the first intestinal transplant. An increased incidence of graft rejection has been described compared to other solid organ transplants due to high immunogenicity of the bowel, which in health allows the balance between of dietary antigen with defense against pathogens. Expanding clinical experience, knowledge of gastrointestinal physiology and immunology have progress post-transplant immunosuppressive drug regimens. Current regimes aim to find the window between prevention of rejection and the risk of infection (the leading cause of death) and malignancy. The ultimate aim is to achieve graft tolerance. In this review we discuss advances in mucosal immunology and technologies informing the development of new anti-rejection strategies with the hope of improved survival in the next generation of transplant recipients.

Current status of pediatric intestinal transplantation in the United States

PURPOSE OF REVIEW

The present review aims to describe in detail the characteristics, outcomes, and recent trends in the field of pediatric intestinal transplantation in the United States. It will examine the route cause and future implications of these developments. The review will draw from recent publications in the field, the Intestinal Transplant Registry, and contemporary data from large U.S. single centers.

RECENT FINDINGS

More than 1500 pediatric intestinal transplants have been performed in the United States since 1985, however, over the past decade there have been fewer than 50 transplants/year nationwide. This trend is largely a result of stagnant long-term ITx outcomes and advancements in intestinal rehabilitation programs. Nationally the overall 1-year and 5-year graft survival are 68 and 50% respectively, whereas certain high-volume centers have experienced significantly better results. Sepsis is the leading cause of death following pediatric ITx, whereas rejection is the leading cause of graft loss. Chronic kidney disease and posttransplant lymphoproliferative disorder are significant and relatively prevalent long-term complications. The majority of pediatric ITx recipients receive T-cell depleting induction agents and are on Tacrolimus-based immunosuppression. Most recipient are off parenteral nutrition, but may require supplemental tube feeds. Many pediatric ITx recipients require special education, and in certain domains some report lower health related quality of life.

SUMMARY

As intestinal rehabilitation has improved in the modern era, the volume of pediatric ITx in the United States has decreased. Although pediatric ITx results have room for improvement nationwide, successful outcomes have been reported at experienced American centers.

Beyond 10 years, with or without an intestinal graft: Present and future?

Long-term outcomes in children undergoing intestinal transplantation remain unclear. Seventy-one children underwent intestinal transplantation in our center from 1989 to 2007. We report on 10-year posttransplant outcomes with (group 1, n = 26) and without (group 2, n = 9) a functional graft. Ten-year patient and graft survival rates were 53% and 36%, respectively. Most patients were studying or working, one third having psychiatric disorders. All patients in group 1 were weaned off parenteral nutrition with mostly normal physical growth and subnormal energy absorption. Graft histology from 15 late biopsies showed minimal abnormality. However, micronutrient deficiencies and fat malabsorption were frequent; biliary complications occurred in 4 patients among the 17 who underwent liver transplantation; median renal clearance was 87 mL/min/1.73 m² . Four patients in group 1 experienced late acute rejection. Among the 9 patients in group 2, 4 died after 10 years and 2 developed significant liver fibrosis. Liver transplantation and the use of a 3-drug regimen including sirolimus or mycophenolate mofetil were associated with improved graft survival. Therefore, intestinal transplantation may enable a satisfactory digestive function in the long term. The prognosis of graft removal without retransplantation is better than expected. Regular monitoring of micronutrients, early psychological assessment, and use of sirolimus are recommended.

Pediatric intestinal transplantation: Analysis of the intestinal transplant registry

The ITR serves as an international database for centers around the world to contribute to current knowledge about intestinal transplant outcomes. Led by the IRTA and managed by the Terasaki Research Institute, the ITR collects data annually and uses these data to generate reports that guide management strategies and policy statements. The aim of this manuscript was to analyze outcomes specific to pediatric intestinal transplantation. Outcome data for children transplanted from 1985 to 2017 were analyzed and predictive factors assessed. A total of 2010 children received 2080 intestine containing allografts during this period. Overall, 1-year and 5-year patient and graft survival were 72.7%/66.1% and 57.2/48.8%, respectively. One-year conditional survival was most strongly associated with being a first-time transplant recipient and liver-inclusive grafts. Patient survival was most strongly associated with elective status of transplantation as compared with hospitalized status. Enteral autonomy following transplantation has continued to improve by era with colonic inclusion demonstrating additional incremental improvement in enteral autonomy and freedom from intravenous fluid. While PTLD and technical complications contribute less to graft loss than in earlier eras, rejection remains the largest contributor to long-term graft loss. Re-transplantation is linked with significantly worse conditional graft survival, and sepsis remains the largest contributor to patient death. Newer data elements are focusing on impact of donor variables, donor and recipient tissue typing, and impact of the development of de novo antibodies.

Long term outcomes of intestinal rehabilitation in children with neonatal very short bowel syndrome: Parenteral nutrition or intestinal transplantation

BACKGROUND & AIMS

Intestinal rehabilitation is the preferred treatment for children with short bowel syndrome (SBS) whatever the residual bowel length, and depends on the accurate management of long-term parenteral nutrition (PN). If nutritional failure develops, intestinal transplantation (ITx) should be discussed and may be life-saving. This study aimed to evaluate survival, PN dependency and nutritional status in children with neonatal very SBS on PN or after ITx, in order to define indications and timing of both treatments.

PATIENTS AND METHODS

This retrospective cross-sectional study enrolled 36 children with very SBS (<40 cm) who entered our intestinal rehabilitation program from 1987 to 2007.

RESULTS

All the children on long-term PN (n = 16) survived with a follow-up of 17 years (9-20). Six of them were eventually weaned off PN. Twenty children underwent ITx: eight children died (40%) 29 months (0-127) after Tx. The others 12 patients were weaned off PN 73 days (13-330) after Tx. Follow-up after transplantation was 14 years (6-28). Seven out of 8 (88%) patients with a history of gastroschisis required ITx. Patients who required ITx had longer stoma duration.

CONCLUSION

Survival rate of children with very short bowel was excellent if no life-threatening complications requiring transplantation developed. Gastroschisis and delayed ostomy closure are confirmed as risk factor for nutritional failure. Intestinal rehabilitation may allow a total weaning of PN before adulthood. A follow-up by a multidisciplinary team is necessary to avoid PN complications in order to minimize indications for ITx.

Intestinal transplantation: current improvements and perspectives

PURPOSE OF REVIEW

This review summarizes the most recent relevant knowledge in clinical practice in the field of intestinal transplantation.

RECENT FINDINGS

Three important factors that have allowed improving results during the last few years are reviewed here. The first relates to the development of a different approach to tackle the underlying cause of intestinal failure and to the patient's characteristics in terms of liver function, age, and body size. The second involves immune modulation and especially the immunosuppressive regimen at induction. The third refers to posttransplantation monitoring, in particular the diagnosis and treatment of intestinal graft rejection and lymphoproliferative disorders. Patient status and referral for intestinal transplantation remain debated. The Intestinal Transplant Registry and a report from an individual program have demonstrated the relationship between a patient's pretransplant status and outcome. Candidacy for intestinal transplantation was analysed in a European survey of home parenteral nutrition patients. Early referral and listing are important for successful outcomes after intestinal grafting.

SUMMARY

Patient management should include therapies adapted to each stage of intestinal failure based on a multidisciplinary approach in centers involving surgery, gastroenterology, parenteral nutrition expertise, home parenteral nutrition programs, and liver-intestinal transplantation experience. Timing for referral of patients in specialized centers remains a crucial issue.

Impacts of donor-specific anti-HLA antibodies and antibody-mediated rejection on outcomes after intestinal transplantation in children

AMR is a risk factor for graft failure after SBTx. We studied impact of DSAs and AMR in 22 children transplanted between 2008 and 2012 (11 isolated SBTx, 10 liver inclusive Tx, and one modified multivisceral Tx). Three patients never developed DSA, but DSAs were found in seven in the pre-Tx period and de novo post-Tx in 19 children. Pathology revealed cellular rejection (15/19), with vascular changes and C4d+. Patients were treated with IV immunoglobulins, plasmapheresis, and steroids. Rescue therapy included antithymocyte globulins, rituximab, eculizumab, and bortezomib. Pathology and graft function normalized in 13 patients, graft loss occurred in two, and death in seven. At the end of the follow-up, 15 children were alive (68%), 13 with functioning graft (59%). Prognosis factors for poor outcome after Tx were the presence of symptoms at AMR suspicion (P +.033). DSAs were often found following SBTx, mostly de novo. Resistant ACR or severe AMR is still difficult to differentiate, with a high need for immunosuppression in both. DSAs may precede development of severe disease and pathology features on the graft: relationship and correlation need to be better investigated with larger groups before and after Tx.

Pediatric small bowel transplantation

PURPOSE OF REVIEW

Intestine has become a transplantable organ due to the improvement in immunosuppressive drugs. The early referral to a reference unit is crucial in prognosis. There are still some pending issues like chronic rejection, the knowledge of the role of DSA development or early noninvasive detection of acute rejection.

RECENT FINDINGS

The appearance of tacrolimus and mTOR, and the use of induction therapy have marked a turning point with better graft and patient survival rates. The inclusion of the liver in the graft seems to have a protective effect. Surveillance of opportunistic infections has also contributed to improved results. Infection, post-transplant lymphoproliferative disease, rejection and GVHD have still a major role in survival; however, antibody-mediated rejection has gained increased attention.

SUMMARY

Parenteral nutrition remains the main therapeutic resource in the management of intestinal failure, but intestinal transplant is a therapeutic option when this therapy has failed. Finding the balanced immunosuppression that minimizes risk of rejection while preventing occurrence of complications like post-transplant lymphoproliferative disease or GVHD is an ongoing challenge. The current survival rates of intestinal transplantation are similar to other solid organ transplant.

Energy expenditure and growth failure after intestinal transplantation: A case report

We present a 12-yr-old boy who received a combined liver-pancreas small bowel transplantation at the age of two. The post-operative period was complicated by wound closure problems resulting in a large asymptomatic abdominal wall defect. Further follow-up was uneventful, with the exception of new onset growth failure not explained by extensive routine investigations. An indirect calorimetry was performed. The resting energy expenditure (REE) was significantly increased (126% of predicted), demanding a daily caloric intake of 123 kcal/kg body weight (normal for age: 80 kcal/kg). In the absence of classic reasons for increased REE, a thermal camera revealed increased dermal heat loss at the abdominal wall defect (estimated surplus in energy loss of at least 29 kcal/day: 10.4% of the elevated REE). In addition, we found lower total lung capacity due to impaired abdominal breathing. In the exploration of growth failure in children after (ITx), increased REE must be taken into account. Indirect calorimetry can serve as a valuable diagnostic tool for evaluating individual energy requirements and nutritional support. In this child, exaggerated heat loss through an aberrant abdominal wall could be a potential important contributor to the patient's increased energy requirements.

Intestinal transplant registry report: global activity and trends

The Registry has gathered information on intestine transplantation (IT) since 1985. During this time, individual centers have reported progress but small case volumes potentially limit the generalizability of this information. The present study was undertaken to examine recent global IT activity. Activity was assessed with descriptive statistics, Kaplan-Meier survival curves and a multiple variable analysis. Eighty-two programs reported 2887 transplants in 2699 patients. Regional practices and outcomes are now similar worldwide. Current actuarial patient survival rates are 76%, 56% and 43% at 1, 5 and 10 years, respectively. Rates of graft loss beyond 1 year have not improved. Grafts that included a colon segment had better function. Waiting at home for IT, the use of induction immune-suppression therapy, inclusion of a liver component and maintenance therapy with rapamycin were associated with better graft survival. Outcomes of IT have modestly improved over the past decade. Case volumes have recently declined. Identifying the root reasons for late graft loss is difficult due to the low case volumes at most centers. The high participation rate in the Registry provides unique opportunities to study these issues.

Intestinal absorption rate in children after small intestinal transplantation

BACKGROUND

Small bowel transplantation has now become a recognized treatment of irreversible, permanent, and subtotal intestinal failure.

OBJECTIVE

The aim of this study was to assess intestinal absorption at the time of weaning from parenteral nutrition in a series of children after intestinal transplantation.

DESIGN

Twenty-four children (age range: 14-115 mo) received intestinal transplantation, together with the liver in 6 children and the colon in 16 children. Parenteral nutrition was slowly tapered while increasing enteral tube feeding. The absorption rate was measured from a 3-d stool balance analysis performed a few days after the child had weaned from parenteral nutrition to exclusive enteral tube feeding. Results were analyzed according to the resting energy expenditure (REE; Schofield formula).

RESULTS

All children were weaned from parenteral nutrition between 31 and 85 d posttransplantation. Median intakes were as follows: energy, 107 kcal · kg(-1) · d(-1) (range: 79-168 kcal · kg(-1) · d(-1)); lipids, 39 kcal · kg(-1) · d(-1) (range: 20-70 kcal · kg(-1) · d(-1)); and nitrogen, 17 kcal · kg(-1) · d(-1) (range: 11-27 kcal · kg(-1) · d(-1)). Median daily stool output was 998 mL/d (range: 220-2025 mL/d). Median absorption rates were 88% (range: 75-96%) for energy, 82% (range: 55-98%) for lipids, and 77% (range: 61-88%) for nitrogen. The ratios for ingested energy to REE and absorbed energy to REE were 2.2 (range: 1.6-3.6) and 1.8 (range: 1.3-3.3), respectively.

CONCLUSION

These data indicate a suboptimal intestinal graft absorption capacity with fat malabsorption, which necessitates energy intakes of at least twice the REE.

Post-transplant critical care outcomes for pediatric multivisceral and intestinal transplant patients

This study reviews the post-operative management of pediatric intestinal transplant patients at a single center with reporting of standard PICU benchmarks for quality of care. It is a retrospective, descriptive, chart review describing our institution's experience between 2006 and 2010. Twenty patients were included. Median age at transplant was 1.6 yr. Median length of PICU stay was 12 days. Median ventilation time was two days. Median time for continuous sedation infusion was two days, with median continuous pain medication infusion of three days. All patients were placed on parental nutrition and started on enteral feedings between days 3 and 4. Forty percent of patients required hemodynamic support. Only 35% of patients required insulin therapy. Diuretics were frequently used in this patient population. There were no episodes of early rejection. The survival rate to PICU discharge was 95%. Our institution's experience over the past four yr has been very successful with a short duration of mechanical ventilation, limited use of pain and sedation drips, early initiation of enteral feedings, minimal hemodynamic support, and a low mortality rate to PICU discharge despite a preponderance of complex MVTx recipients.

Inclusion of the colon in intestinal transplantation

PURPOSE OF REVIEW

Inclusion of the colon as a component of an intestinal graft has evolved over the past two decades. Initially thought to be hazardous and abandoned by many centers, colon inclusion has now proven to be an integral component of the intestinal transplant graft.The purpose of this review is to summarize the history of colon inclusion, the physiology of the colon, surgical techniques of colon inclusion, and outcome data.

RECENT FINDINGS

Recent studies at centers of excellence report the efficacy and safety of colon inclusion in intestinal transplantation. Quality-of-life indicators, stool patterns, fecal continence, and parenteral nutrition weaning were noted to be improved in recipients of colonic inclusion. Complex intestinal transplant case series were reported with no adverse effects of colon inclusion.

SUMMARY

Colon inclusion provides a necessary function in intestinal transplantation by taking advantages of its physiologic functions of water absorption, residue breakdown, and storage. Current clinical evidence supports the efficacy of selective and cautious use of the colon in intestinal transplantation.

Intractable diarrhea with tufting enteropathy: a favorable outcome is possible

BACKGROUND AND OBJECTIVE

Tufting enteropathy (TE) is a congenital abnormality of intestinal mucosa development characterized by severe intestinal failure requiring parenteral nutrition (PN) and, in some cases, small bowel transplantation. A few patients have had a more favorable outcome. The objective of this study was to evaluate possible correlations between histological lesion severity in duodenal biopsies and clinical outcomes in children with TE.

PATIENTS AND METHODS

We retrospectively reviewed the records of patients diagnosed with TE between 1993 and 2003 at our institution based on intractable neonatal-onset diarrhea with prolonged dependence on PN and duodenal biopsy findings of villous atrophy, epithelial dysplasia with enterocyte dedifferentiation and disorganization (tufting) of the surface epithelium, and crypt abnormalities. The histological lesions were assessed semiquantitatively and compared with the clinical outcomes including dependence on PN.

RESULTS

Seven children, all from consanguineous parents, were studied for a median of 6.5 years. Three were permanently weaned off PN and experienced normal growth without nutritional assistance. Initial biopsies in all 3 children showed severe diffuse histological lesions. At weaning off PN, 2 of these 3 patients had persistent, although less diffuse, histological lesions.

CONCLUSIONS

Progressive weaning off PN is possible in some children with TE. In our experience, this favorable outcome was not predicted by histological lesion severity, although the lesions improved in some patients. New biomarkers for identifying the histological lesions and predicting the outcome would be useful.

Effect of recombinant human growth hormone on intestinal absorption and body composition in children with short bowel syndrome

This prospective study aimed to establish the effect of recombinant human growth hormone (rhGH) on intestinal function in children with short bowel syndrome (SBS). Eight children with neonatal SBS were included. All were dependent on parenteral nutrition (PN) for >3 years (range, 3.8-11.6 years), with PN providing >50% of recommended dietary allowance for age (range, 50%-65%). The subjects received rhGH (Humatrope) 0.13 mg/kg/d subcutaneously over a 12-week period. The follow-up was continued over a 12-month period after rhGH discontinuation. Clinical and biological assessments were performed at baseline, at the end of the treatment period, and 12 months after the end of treatment. No side effects related to rhGH were observed. PN requirements were decreased in all children during the course of rhGH treatment. Between baseline and the end of treatment, significant increases were observed in concentrations (mean ± standard deviation) of serum insulin-like growth factor 1 (103.1 ± 49.9 µg/L vs 153.5 ± 82.2 µg/L; P < .01), serum insulin-like growth factor-binding protein 3 (1.7 ± 0.6 mg/L vs 2.5 ± 0.9 mg/L; P < .001), and plasma citrulline (16.5 ± 14.8 µmol/L vs 25.2 ± 18.3 µmol/L; P < .05). A median 54% increase in enteral intake (range, 10%-244%) was observed (P < .001) and net energy balance improved significantly (P < .002). It was necessary for 6 children to be maintained on PN or restarted after discontinuation of rhGH treatment, and they remained on PN until the end of the follow-up period. A 12-week high-dose rhGH treatment allowed patients to decrease PN, but only 2 patients could be definitively weaned from PN. Indications and cost-effectiveness of rhGH treatment for SBS pediatric patients need further evaluation.

Pretransplant predictors of survival after intestinal transplantation: analysis of a single-center experience of more than 100 transplants

INTRODUCTION

Outcomes after intestinal transplantation (ITx) have steadily improved. There are few studies that assess factors associated with these enhanced results. The purpose of this study was to examine peri-ITx variables and survival.

METHODS

A review of a prospectively maintained database was undertaken and included all patients undergoing ITx from 1991 to 2010. The study endpoints were patient and graft survival. Data collection included 44 variables. Survival was computed using Kaplan-Meier methods. Univariate analysis was conducted (log-rank test) with significance set at P less than or equal to 0.20. Multivariate analysis of significant variables was conducted using model reduction by backward elimination variable selection method with significance set at P less than 0.05.

RESULTS

Eighty-eight patients received 106 ITx. The majority of recipients were male, Latino, and children. The leading causes of intestinal and liver failure were gastroschisis and parenteral nutrition. Grafts transplanted were isolated intestine (24%), liver-intestine (62%), and multivisceral (14%). Overall 1- and 5-year patient and graft survival were 80% and 65%, and 74% and 64%, respectively. Significant univariate survival predictors were weight less than 20 kg, children, liver-inclusive allograft, panel reactive antibody less than 20%, absence of donor-specific antibody, negative crossmatch, warm ischemia time less than 60 min, absence of recipient splenectomy, interleukin-2 receptor antagonist induction, and era. Significant multivariate survival predictors were absence of donor-specific antibody, absence of recipient splenectomy, and liver-inclusive graft type.

CONCLUSION

This large, single-center ITx experience confirms a marked improvement in outcome over time. Several important factors were associated with survival, and these factors can potentially be adjusted before ITx. These findings should refocus future efforts on strategies to improve treatment and prevent graft loss.

Intestinal transplantation in children: a review of immunotherapy regimens

This review summarizes the outcomes and known adverse effects of current immunosuppression strategies in use in pediatric intestinal transplantation. Intestinal transplantation has evolved from an experimental therapy to a highly successful treatment for children with intestinal failure who have complications with total parenteral nutrition. Because of continued success with intestinal transplantation over the past decade, the focus of clinicians and researchers is shifting from short-term patient survival to optimizing long-term outcomes. Current 5-year patient and graft survival rates after intestinal transplantation are 58% and 40%, respectively, in the US; single centers have reported nearly 80% patient and 60% graft survival rates at 5 years. The immunosuppression strategy in intestinal transplantation includes a tacrolimus-based regimen, usually in conjunction with an antibody induction therapy such as rabbit-antithymocyte globulin, interleukin-2 receptor antagonists, or alemtuzumab. The use of these immunosuppressive regimens, along with improved medical and surgical care, has contributed significantly toward improved outcomes. Optimization of post-transplant immunosuppression strategies to reduce adverse effects while minimizing acute and chronic graft rejection is a strong clinical and research focus.

Role of the colon in short bowel syndrome and intestinal transplantation

Colon is a crucial partner for small intestinal adaptation and function in patients who underwent extensive small intestinal resection or transplantation. This short review deals with the different properties and roles of the colon in these settings, involving fluid and electrolytes absorption, absorption of medium-chain triglycerides, and production of short-chain fatty acids for malabsorbed energy salvage. The colon may adapt after small intestinal resection, whereas it hosts the most important part of the intestinal microbiota, which plays a crucial role in intestinal function and health. Also, colon may be responsible for D-lactic acidosis as well, as it can be injured by noninfectious colitis. Finally, the relevance of a simultaneous colon grafting is discussed as it is occasionally considered in specific patients requiring intestinal transplantation.

Intestinal transplantation for total intestinal aganglionosis: a series of 12 consecutive children

BACKGROUND

Management of patients with total intestinal aganglionosis (TIA) is a medical challenge because of their dependency on parenteral nutrition (PN). Intestinal transplantation (ITx) represents the only alternative treatment for patients with irreversible intestinal failure for achieving intestinal autonomy.

METHODS

Among 66 patients who underwent ITx in our center, 12 had TIA. They received either isolated ITx (n = 4) or liver-ITx (LITx, n = 8) after 10 to 144 months of total PN. All grafts included the right colon.

RESULTS

After a median follow-up of 57 months, the survival rate was 62.5% in the LITx group and 100% in the ITx patients. The graft survival rate was 62.5% in the LITx group and 75% in the ITx group. All the surviving patients were fully weaned from total PN, after a median of 57 days. Pull through of the colon allograft was carried out in all patients. Fecal continence is normal in all but one of the surviving children.

CONCLUSION

These results suggest that ITx with colon grafting should be the preferred therapeutic option in TIA. Early referral to a transplantation center after diagnosis of TIA is critical to prevent PN-related cirrhosis and thereby to permit ITx, which is associated with a good survival rate.

Pediatric intestinal and multivisceral transplantation: a new challenge for the pediatric intensivist

INTRODUCTION

With increasing survival rates, intestinal transplantation (ITx) and multivisceral transplantation have reached the mainstream of medical care. Pediatric candidates for ITx often suffer from severe multisystem impairments that pose challenges to the medical team. These patients frequently require intensive care preoperatively and have unique intensive care needs postoperatively.

METHODS

We reviewed the literature on intensive care of pediatric intestinal transplantation as well as our own experience. This review is not aimed only at pediatric intensivists from ITx centers; these patients frequently require ICU care at other institutions.

RESULTS

Preoperative management focuses on optimization of organ function, minimizing ventilator-induced lung injury, preventing excessive edema yet maintaining adequate organ perfusion, preventing and controlling sepsis and bleeding from varices at enterocutaneous interfaces, and optimizing nutritional support. The goal is to extend life in stable condition to the point of transplantation. Postoperative care focuses on optimizing perfusion of the mesenteric circulation by maintaining intravascular volume, minimizing hypercoagulability, and providing adequate oxygen delivery. Careful monitoring of the stoma and its output and correction of electrolyte imbalances that may require renal replacement therapy is critical, as are monitoring for and aggressively treating infections, which often present with only subtle clinical clues. Signs of intestinal rejection may be non-specific, and early differentiation from other causes of intestinal dysfunction is important. Understanding of the expanding armamentarium of immunosuppressive agents and their side-effects is required.

CONCLUSIONS

As outcomes of ITx improve, transplant teams accept patients with higher pre-operative morbidity and at higher risk for complications. Many ITx patients would benefit from earlier referral for transplant evaluation before severe liver disease, recurrent central venous catheter-related sepsis and venous thromboses develop.

Evaluation of c4d deposition and circulating antibody in small bowel transplantation

Antibody-mediated rejection (AMR) consensus criteria are defined in kidney and heart transplantation by histological changes, circulating donor-specific antibody (DSA), and C4d deposition in affected tissue. AMR consensus criteria are not yet identified in small bowel transplantation (SBTx). We investigated those three criteria in 12 children undergoing SBTx, including one retransplantation and four combined liver-SBTx (SBTx), with a follow-up of 12 days to 2 years. All biopsies (91) were evaluated with a standardized grading scheme for acute rejection (AR), vascular lesions and C4d expression. Sera were obtained at day 0 and during the follow-up. C4d was expressed in 37% of biopsies with or without AR, but in 50% of biopsies with severe vascular lesions. In addition, vascular lesions were always associated with AR and a poor outcome. All children with AR (grade 2 or 3) observed before the third month died or lost the graft. DSA were never found in any studied sera. We found no evidence that C4d deposition was of any clinical relevance to the outcome of SBTx. However, the grading of vascular lesions may constitute a useful marker to identify AR that is potentially resistant to standard treatment, and for which an alternative therapy should be considered.

Future horizons in the treatment of enteric neuropathies

Enteric neuropathies comprise a vast and disparate array of congenital and acquired disorders of the enteric nervous system (ENS), reflecting both the complexity of its neuronal composition and the many interactions that modulate its function. Although present therapeutic strategies, largely limited to surgery and the provision of artificial nutrition, have transformed the early survival and life of sufferers, levels of morbidity and mortality remain unacceptably high. This highlights the need to develop new treatments for enteric neuropathies. In the last decade, the tremendous advances in molecular biology and genetics have significantly enhanced our understanding of ENS development and function. Coupled with equivalent progress in the fields of pharmacology and stem-cell biology, this has led to the identification of novel tools and targets for therapy, which either aim to optimise the function of the intrinsic ENS or replace/replenish components of an inadequate or dysfunctional ENS. This article reviews current work on a number of these interventions with a particular focus on the use of ENS stem cells as potential therapeutic tools for enteric neuropathies.

Intestinal epithelial dysplasia (tufting enteropathy)

Intestinal epithelial dysplasia (IED), also known as tufting enteropathy, is a congenital enteropathy presenting with early-onset severe intractable diarrhea causing sometimes irreversible intestinal failure. To date, no epidemiological data are available, however, the prevalence can be estimated at around 1/50,000-100,000 live births in Western Europe. The prevalence seems higher in areas with high degree of consanguinity and in patients of Arabic origin. Infants develop within the first days after birth a watery diarrhea persistent in spite of bowel rest and parenteral nutrition. Some infants are reported to have associated choanal rectal or esophageal atresia. IED is thought to be related to abnormal enterocytes development and/or differentiation. Nonspecific punctuated keratitis was reported in more than 60% of patients. Histology shows various degree of villous atrophy, with low or without mononuclear cell infiltration of the lamina propria but specific histological abnormalities involving the epithelium with disorganization of surface enterocytes with focal crowding, resembling tufts. Several associated specific features were reported, including abnormal deposition of laminin and heparan sulfate proteoglycan (HSPG) in the basement membrane, increased expression of desmoglein and ultrastructural changes in the desmosomes, and abnormal distribution of alpha2beta1 integrin adhesion molecules. One model of transgenic mice in which the gene encoding the transcription factor Elf3 is disrupted have morphologic features resembling IED. Parental consanguinity and/or affected siblings suggest an autosomal recessive transmission but the causative gene(s) have not been yet identified making prenatal diagnosis unavailable. Some infants have a milder phenotype than others but in most patients, the severity of the intestinal malabsorption even with enteral feeding make them totally dependent on daily long-term parenteral nutrition with a subsequent risk of complications. IED becomes an indication for intestinal transplantation, while timing of referral for it is crucial before the onset of severe complications.

Management of intestinal failure

Intestinal failure (IF) occurs when the body is unable to sustain its energy and fluid requirements without support, due to loss of functional small bowel. Prolonged IF is seen after large intestinal resection and described as short bowel syndrome (SBS). The hallmark of the management is parental nutrition (PN), which is costly and may be associated with the well-recognized problems of parental nutrition associated liver disease (PNALD) and line related sepsis. Cessation of PN at the earliest possible stage is desirable but for this enteral autonomy has to be achieved first. Intestinal adaptation occurs when the remaining gut goes through morphological changes increasing its absorptive capacity. Factors such as intraluminal nutrients, gastrointestinal secretions and hormones facilitate adaptation. Enteral feeds are a potent stimulant to adaptation and should be started as soon as the clinical situation permits. Some drugs are thought to increase intestinal adaptation. These include glutamine, growth hormone and glucagon like peptide- 2, but there is a paucity of pediatric data to guide their use. In some cases surgical bowel lengthening procedures can be performed to increase the absorptive surface area. An isolated liver transplantation may be required if the liver has sustained irreversible damage but intestinal autonomy seems achievable. When prolonged PN is either unsustainable or associated with unacceptable side effects, small bowel transplantation should be considered as a treatment option.

Factors Influencing Outcome After Intestinal Transplantation in Children

We evaluated 131 patients (6 months-14 years) who experienced 21 deaths before listing, 11 continuing on the waiting list, 38 well on home parenteral nutrition, 6 off parenteral nutrition and 59 transplanted (20 girls) aged 2.5 to 15 years, (18 >7 years). They received cadaveric isolated intestine (ITx, n = 31) or liver-small bowel (LITx, n = 32), including right colon (n = 43; 23 LITx) for short bowel (n = 19), enteropathy (n = 20), Hirschsprung (n = 14), or pseudo-obstruction (n = 6). Treatment included tacrolimus, steroids, azathioprine, or interleukin-2 blockers. After 6 months to 10.5 years, the patient and graft survivals were 75% and 54%. Sixteen patients (10 LITx) died within 3 months from surgery (n = 3), bacterial (n = 5) or fungal (n = 6) sepsis, or posttransplant lymphoproliferative disorder (n = 2). Rejection occurred in 27 patients, including 10 steroid-resistant episodes requiring antilymphoglobulins. The grafts were removed due to uncontrolled rejection in seven ITx recipients. Surgical complications were observed in 38 recipients (25 LSBTx) within 2 months, including bacterial (n = 22) or fungal (n = 11) sepsis, cytomegalovirus disease (n=12), adenovirus (n = 11), or posttransplant lymphoproliferative disorder (n = 12). Forty-two children (19 LSBTx) are alive. Weaning from parenteral nutrition was achieved after 42 days (median). Factors related to death or graft loss were pre-Tx surgery (P < .01), pseudo-obstruction (P < .01), age over 7 years (P < .03), fungal sepsis (P < .03), steroid resistant rejection (P < .05), hospitalized versus home patient (P < .01), and retransplantation (P < .05). Colon transplant did not affect the outcome. Interleukin-2 blockers improved isolated ITx (P < .05). Early referral and close monitoring of intestinal failure and related disorders are mandatory to achieve successful ITx.

Short bowel syndrome and intestinal transplantation in children

PURPOSE OF REVIEW

This review summarizes recent knowledge and clinical practice for pediatric patients suffering extensive intestinal resection causing short bowel syndrome. This condition requires the use of parenteral nutrition, as long as intestinal failure persists, and may be, in some selected cases, an indication for intestinal transplantation.

RECENT FINDINGS

Biological evaluation of intestinal failure is becoming possible with the use of plasma citrulline as a marker of intestinal mass. Few epidemiological data are available; some indicate an increased incidence of short bowel syndrome-related gastroschisis and persistent high incidence of necrotizing enterocolitis. Morbidity and mortality data in pediatric patients with short bowel syndrome are limited, while long-term outcome is better documented from recently reported cohorts. Non-transplant surgery is one of the best options for patients with unadapted short bowel syndrome. Isolated liver transplantation may be avoided. The use of trophic factors for enhancing mucosal hyperplasia still remains disappointing.

SUMMARY

The management should include therapies adapted to each stage of intestinal failure, based on a multidisciplinary approach in centers involving pediatric surgery, pediatric gastroenterology, parenteral nutrition expertise, home-parenteral nutrition program, and liver-intestinal transplantation experience. If managed appropriately, the prognosis of short bowel syndrome is excellent, with limited indications for intestinal and/or liver transplantation. Timing for patient referral in specialized centers remains an issue.