The current state of intestine transplantation: indications, techniques, outcomes and challenges

Immune cell profiling in intestinal transplantation

Since the first published case study of human intestinal transplantation in 1967, there have been significant studies of intestinal transplant immunology in both animal models and humans. An improved understanding of the profiles of different immune cell subsets is critical for understanding their contributions to graft outcomes. While different studies have focused on the contribution of one or a few subsets to intestinal transplant, no study has integrated these data for a comprehensive overview of immune dynamics after intestinal transplant. Here, we provide a systematic review of the literature on different immune subsets and discuss their roles in intestinal transplant outcomes on multiple levels, focusing on chimerism and graft immune reconstitution, clonal alloreactivity, and cell phenotype. In Sections 1, 2 and 3, we lay out a shared framework for understanding intestinal transplant, focusing on the mechanisms of rejection or tolerance in the context of mucosal immunology and illustrate the unique role of the bidirectional graft-versus-host (GvH) and host-versus-graft (HvG) alloresponse. In Sections 4, 5 and 6, we further expand upon these concepts as we discuss the contribution of different cell subsets to intestinal transplant. An improved understanding of intestinal transplantation immunology will bring us closer to maximizing the potential of this important treatment.

Tolerance in intestinal transplantation

Intestinal transplantation (ITx) is highly immunogenic, resulting in the need for high levels of immunosuppression, with frequent complications along with high rejection rates. Tolerance induction would provide a solution to these limitations. Detailed studies of alloreactive T cell clones as well as multiparameter flow cytometry in the graft and peripheral tissues have provided evidence for several tolerance mechanisms that occur spontaneously following ITx, which might provide targets for further interventions. These include the frequent occurrence of macrochimerism and engraftment in the recipient bone marrow of donor hematopoietic stem and progenitor cells carried in the allograft. These phenomena are seen most frequently in recipients of multivisceral transplants and are associated with reduced rejection rates. They reflect powerful graft-vs-host responses that enter the peripheral lymphoid system and bone marrow after expanding within and emigrating from the allograft. Several mechanisms of tolerance that may result from this lymphohematopoietic graft-vs-host response are discussed. Transcriptional profiling in quiescent allografts reveals tolerization of pre-existing host-vs-graft-reactive T cells that enter the allograft mucosa and become tissue-resident memory cells. Dissection of the pathways driving and maintaining this tolerant tissue-resident state among donor-reactive T cells will allow controlled tolerance induction through specific therapeutic approaches.

Application of enzyme-linked immunosorbent assay to detect antimicrobial peptides in human intestinal lumen

Intestinal transplantation is the definitive treatment for intestinal failure. However, tissue rejection and graft-versus-host disease are relatively common complications, necessitating aggressive immunosuppression that can itself pose further complications. Tracking intraluminal markers in ileal effluent from standard ileostomies may present a noninvasive and sensitive way to detect developing pathology within the intestinal graft. This would be an improvement compared to current assessments, which are limited by poor sensitivity and specificity, contributing to under or over-immunosuppression, respectively, and by the need for invasive biopsies. Herein, we report an approach to reproducibly analyze ileal fluid obtained through stoma sampling for antimicrobial peptide/protein concentrations, reasoning that these molecules may provide an assessment of intestinal homeostasis and levels of intestinal inflammation over time. Concentrations of lysozyme (LYZ), myeloperoxidase (MPO), calprotectin (S100A8/A9) and β-defensin 2 (DEFB2) were assessed using adaptations of commercially available enzyme-linked immunosorbent assays (ELISAs). The concentration of α-defensin 5 (DEFA5) was assessed using a newly developed sandwich ELISA. Our data support that with proper preparation of ileal effluent specimens, precise and replicable determination of antimicrobial peptide/protein concentrations can be achieved for each of these target molecules via ELISA. This approach may prove to be reliable as a clinically useful assessment of intestinal homeostasis over time for patients with ileostomies.

Risk factors for renal dysfunction after isolated intestinal transplantation

INTRODUCTION

Kidney dysfunction is a known complication of intestinal transplantation; however, the rate of development and risk factors for chronic kidney disease (CKD) remain poorly defined.

METHODS

This was a single-center retrospective review of isolated adult intestinal allograft recipients from 2011 to 2019. Patients who died or experienced graft loss within 1-year or had a prior transplant were excluded. Estimated glomerular filtration rate (eGFR) was calculated using the CKD-EPI equation at 0-, 6- and 12-months post-transplant, and multivariable linear regression was performed to identify variables associated with adjusted eGFR at 1-year. Independent variables included age, ethnicity, BMI, history of diabetes/hypertension, vasopressor use, TPN and stoma days, urinary or bloodstream infections, intravenous contrast exposure, rejection, concomitant immunosuppression, and time above the therapeutic range of tacrolimus. Variables with a p < .1 in univariate analysis were considered for multivariable modeling.

RESULTS

Thirty-three patients were included with a mean age of 43.9 ± 13.0. A mean 42.3% decline in eGFR was observed at 1-year post-transplant, with 15.2% of patients developing new stage 4/5 CKD. Factors associated with a greater decline in adjusted eGFR in the univariate model included increasing age, decreased BMI, stoma days, and vasopressor use. In the adjusted multivariable model patient age (β = -.77, p < .01) and stoma days (β = -.06, p < .01) remained significant. Tacrolimus and sirolimus exposure were not associated with decline in eGFR at 1 year.

CONCLUSIONS

Renal dysfunction is common following intestinal transplantation. The need for stoma creation should be carefully considered, and reversal should be performed when feasible for renal protection.

Survival Benefit of Solid-Organ Transplantation: 10-Year Update

IMPORTANCE

Transplantation has transformed into a burgeoning field that is rapidly evolving to optimize organ distribution and survival outcomes. The years since 2012 (the last comprehensive study) have seen changes in transplantation, such as advances in immunotherapy and novel indices, that necessitate an updated analysis of survival benefit.

DESIGN

Our goal was to determine the survival benefit for solid-organ transplants in the United Network for Organ Sharing (UNOS) database for a three decade period and provide updates on advancements since 2012. Our retrospective analysis examined data containing U.S. patient records from September 1, 1987, to September 1, 2021.

RESULTS

We found that 3,430,272 life-years were saved over our transplant period (4.33 life-years saved per patient); kidney-1,998,492 life-years; liver -767,414; heart-435,312; lung-116,625; pancreas-kidney-123,463; pancreas-30,575; intestine-7901. After matching, 3,296,851 life-years were saved. Life-years saved and median survival increased for all organs between 2012 and 2021. Compared to 2012, median survival increased in kidney (from 12.4 to 14.76 years), liver (from 11.6 to 14.59), heart (9.5 to 11.73), lung (5.2 to 5.63), pancreas-kidney (from 14.5 to 16.88), pancreas (from 13.3 to 16.10). When compared to 2012, the percent transplanted increased in kidney, liver, heart, lung, and intestine, while pancreas-kidney and pancreas show decreased percent transplanted.

CONCLUSION

Our study underscores the tremendous survival benefits of solid organ transplantation (over 3.4 million life-years saved) and shows improvements since 2012. Our study also highlights areas of transplantation, notably pancreas transplants, that may necessitate reinvigorated attention.

Intestinal and Multivisceral Transplantation: Indications and Surgical Techniques

Intestinal transplantation and multivisceral transplantation are technically challenging and complex procedures mainly performed on patients with irreversible and non-medically manageable end-stage intestinal failure. Increasingly, other organs besides small intestines are included in the allograft for which the terms "composite intestinal transplantation" and "multivisceral transplantation" are used. Commonly, complex vascular reconstructions are used for these procedures. Knowledge of surgical anatomy hence is essential for accurate interpretation of postoperative imaging in these patients. This article reviews the indications and most common surgical techniques for intestinal and multivisceral transplantations.

Growing experience of surgical gut rehabilitation: essential role in the management of gut failure in adult patients

PURPOSE OF REVIEW

With the inherent therapeutic limitations of gut transplantation, the concept of surgical gut rehabilitation was introduced to restore nutritional autonomy in pediatric patients. With favorable outcomes in these young patients, there has been increasing interest in the applicability of gut rehabilitative surgery to a growing population of adults with gut failure due to various etiologies. We aim to review the current status of surgical gut rehabilitation for adult gut failure patients in the era of multidisciplinary gut rehabilitation and transplantation.

RECENT FINDINGS

Indications for surgical gut rehabilitation have been gradually expanding, with gut failure after bariatric surgery recently added. Serial transverse enteroplasty (STEP) has been used with favorable outcomes in adult patients, including those with intrinsic intestinal disease. Autologous gut reconstruction (AGR) is the most frequently used surgical rehabilitative method; its outcome is further improved with conjunctive use of bowel lengthening and enterocyte growth factor as a part of comprehensive gut rehabilitation.

SUMMARY

Accumulated experiences have validated the efficacy of gut rehabilitation for survival, nutritional autonomy, and quality of life in adults with gut failure of various etiology. Further progress is expected with growing experience around the world.

Multidrug-resistant Klebsiella Pneumoniae Infection Led to Resection of the Graft in a Small Bowel Transplant Recipient: A Case Report and Review of the Literature

BACKGROUND

Infection due to multidrug-resistant Klebsiella pneumoniae is a common cause of graft resection after small bowel transplantation. We report a failed case in which the intestinal graft was resected 18 days after the operation due to postoperative infection with multidrug-resistant K pneumoniae and a literature review of other common causes of small bowel transplantation failure have been reported.

METHODS

A female, 29 years of age, underwent partial living small bowel transplantation for short bowel syndrome. After the operation, the patient was infected with multidrug-resistant K pneumoniae, even though various anti-infective regimens were employed. It further developed into sepsis and disseminated into intravascular coagulation, leading to exfoliation and necrosis of the intestinal mucosa. Finally, the intestinal graft had to be resected to save the patient's life.

RESULTS

Multidrug-resistant K pneumoniae infection often affects the biological function of intestinal grafts and can even lead to necrosis. Other common causes of failure, including postoperative infection, rejection, post-transplantation lymphoproliferative disorder, graft-vs-host disease, surgical complications, and other related diseases, were also discussed throughout the literature review.

CONCLUSIONS

Pathogenesis due to diverse and interrelated factors makes the survival of intestinal allografts a great challenge. Therefore, only by fully understanding and mastering the common causes of surgical failure can the success rate of small bowel transplantation be effectively improved.

Overview of Physical, Neurocognitive, and Psychosocial Outcomes in Pediatric Intestinal Failure and Transplantation

PURPOSE OF REVIEW

Intestinal failure and transplantation may significantly impact physical, neurocognitive, and psychosocial development in pediatric patients. Currently, there is a paucity of literature on the effects of intestinal failure and transplantation on these aspects of development. This article will review the current literature and discuss the short and long-term impacts as well as interventions to improve clinical outcomes in children with intestinal failure or those undergoing transplantation.

RECENT FINDINGS

Psychological disorders, neurodevelopmental delay, and social maladaptation are frequently encountered in this patient population. While the main focus is often on medical management, equal emphasis should be placed on other aspects of development such as increasing social support and improving school performance. The transition to adulthood also presents many obstacles for patients and healthcare providers should anticipate challenges such as childbirth, employment, and raising a family. The pre-operative, perioperative, and post-operative periods all represent opportunities for medical intervention. Frequent monitoring of physical, psychosocial, and neurocognitive status helps to improve clinical outcomes and long-term quality of life. Future research should emphasize continued development of multidisciplinary programs and specialized services to help address the physical and psychosocial needs of children with intestinal failure as well as transplant recipients.

Severe congenital diarrhea secondary to tufting enteropathy. Case report

Introduction: Tufting enteropathy is a rare cause of congenital diarrhea in neonates. It is characterized by the abnormal distribution of epithelial adhesion molecules, which causes enterocytes to shed into the lumen, forming the characteristic tufts. Case presentation: A 15-day-old female neonate was taken by her parents to the emergency department of a tertiary care hospital due to diarrheal stools she had been experiencing since birth. The patient presented with dehydration, abnormal weight loss, metabolic acidosis, and acute kidney failure. She received treatment with alizapride, loperamide, zinc sulfate, and probiotics, but after 75 days of treatment she was still symptomatic. An upper tract endoscopy and colonoscopy were performed, finding flattening of the villi and lymphoid cells in the lamina propria. However, the symptoms persisted, and she died at the age of ten months. A post-mortem exome sequencing reported tufting enteropathy. Conclusions. When congenital diarrhea is present, tufting enteropathy should be considered. An early molecular study would allow to evaluate the possibility of performing an intestinal transplant or modifying the treatment to meet the patient’s palliative care needs.

Emerging Concepts of Tissue-resident Memory T Cells in Transplantation

In this review, we summarize and discuss recent advances in understanding the characteristics of tissue-resident memory T cells (TRMs) in the context of solid organ transplantation (SOT). We first introduce the traditionally understood noncirculating features of TRMs and the key phenotypic markers that define this population, then provide a detailed discussion of emerging concepts on the recirculation and plasticity of TRM in mice and humans. We comment on the potential heterogeneity of transient, temporary resident, and permanent resident T cells and potential interchangeable phenotypes between TRM and effector T cells in nonlymphoid tissues. We review the literature on the distribution of TRM in human nonlymphoid organs and association of clinical outcomes in different types of SOT, including intestine, lung, liver, kidney, and heart. We focus on both tissue-specific and organ-shared features of donor- and recipient-derived TRMs after transplantation whenever applicable. Studies with comprehensive sample collection, including longitudinal and cross-sectional controls, and applied advanced techniques such as multicolor flow cytometry to distinguish donor and recipient TRMs, bulk, and single-cell T-cell receptor sequencing to track clonotypes and define transcriptome profiles, and functional readouts to define alloreactivity and proinflammatory/anti-inflammatory activities are emphasized. We also discuss important findings on the tissue-resident features of regulatory αβ T cells and unconventional γδ T cells after transplantation. Understanding of TRM in SOT is a rapidly growing field that urges future studies to address unresolved questions regarding their heterogeneity, plasticity, longevity, alloreactivity, and roles in rejection and tolerance.

High Throughput Human T Cell Receptor Sequencing: A New Window Into Repertoire Establishment and Alloreactivity

Recent advances in high throughput sequencing (HTS) of T cell receptors (TCRs) and in transcriptomic analysis, particularly at the single cell level, have opened the door to a new level of understanding of human immunology and immune-related diseases. In this article, we discuss the use of HTS of TCRs to discern the factors controlling human T cell repertoire development and how this approach can be used in combination with human immune system (HIS) mouse models to understand human repertoire selection in an unprecedented manner. An exceptionally high proportion of human T cells has alloreactive potential, which can best be understood as a consequence of the processes governing thymic selection. High throughput TCR sequencing has allowed assessment of the development, magnitude and nature of the human alloresponse at a new level and has provided a tool for tracking the fate of pre-transplant-defined donor- and host-reactive TCRs following transplantation. New insights into human allograft rejection and tolerance obtained with this method in combination with single cell transcriptional analyses are reviewed here.

Characterization of Slow Wave Activity in Ex-vivo Porcine Small Intestine Segments

The motility of the gut is central to digestion and is coordinated, in part, by bioelectrical events known as slow waves. While the nature of these events is well defined in-vivo, the temporal response of ex-vivo gastrointestinal myoelectrical activity without perfusion is poorly understood. To achieve a fundamental understanding of ex-vivo electrophysiology, slow wave activity was measured from excised porcine intestinal segments and characterized over time. In this study, slow wave frequencies and amplitudes, along with the duration of sustained activity were quantified. Slow wave amplitudes and frequencies decreased from initial values of 46 ± 34 µV and 9.6 ± 5.9 cpm to electrical quiescence over a period of 12.2 ± 2.3 minutes. Mean slow wave amplitude and frequency uniformly declined before electrical quiescence was reached. This study demonstrated the successful acquisition of gastrointestinal myoelectrical activity in excised tissue segments without perfusion. Key slow wave characteristics may contribute to future diagnostics, transplantations and treatments for motility disorders.Clinical Relevance- The ability to characterize excised slow wave activity in organs lacking perfusion will be a critical advancement in developing clinical solutions. Findings will assist in establishing the efficacy of bioelectrical activity in excised tissue samples for organ transplantation. In addition, the ex-vivo setting can be used to represent compromised electrophysiological states to evaluate novel therapies.

Vascular reconstruction of segmental intestinal grafts using autologous internal iliac vessels

Background

The aim of this study was to assess whether the autologous internal iliac artery and vein could be used as an interpositional graft for vascular reconstruction in segmental intestinal allografts and autografts.

Methods

Thirty-four intestinal transplants (19 living-related allografts and 15 autografts) were conducted in our programs between January 2011 and January 2019. Patient characteristics, type of vascular reconstruction, and post-operative complications were reviewed.

Results

There were 20 males and 14 females with a median age of 35 years. Of 34 grafts, 22 (64.7%) (11 allografts and 11 autografts) were revascularized using the autologous internal iliac artery and vein for reconstruction. Vascular reconstruction on the back table took 21 ± 6 min to complete. Both total operative time and cold ischemia time tended to be longer in the vascular-reconstruction group than in the direct-anastomosis group (530 ± 226 vs 440 ± 116 and 159 ± 49 vs 125 ± 66 min, respectively), but these differences were not significant. The incidence of vascular thrombosis tended to be higher in the direct-anastomosis group than in the vascular-reconstruction group (16.7% vs 0%, P = 0.118). At a median follow-up of 36.9 months, no stenosis or pseudoaneurysms developed. In 19 allografts, acute rejection occurred in 4 (21.1%) and chronic rejection occurred in 1 (5.2%).

Conclusions

Our results indicate that the use of an autologous internal iliac interposition graft greatly facilitates intestinal graft implantation and minimizes the risk of vascular complications.

Biliary and duodenal complications after « en bloc» liver-small bowel transplantation in children. A single center cohort study

BACKGROUND

The technique of « en bloc» liver and small bowel transplantation (L-BT) spares a biliary anastomosis, but does not protect against biliary complications. We analyze biliary and duodenal complications (BDC) in our pediatric series.

METHODS

Between 1994 and 2020, 54 L-BT were performed in 53 children. The procurement technique included in situ vascular dissection and pancreatic reduction to the head until 2009 (group A). Thereafter, the whole pancreas was recovered (group B).

RESULTS

Nine BDCs occurred in 8/53 (15%) patients (7 in group A and 1 in group B): leak of the donor's duodenal stump (2), stenosis of the extra-pancreatic bile duct (5), and intra-pancreatic bile duct stenosis (2). Median delay for diagnosis of stricture was 8 months (4-168). Interventional radiology was successful in one child only, the others required reoperations. Two patients died, of biliary cirrhosis or cholangitis, 15-month and 12-year post-L-BT. One was listed and liver re-transplanted 13 years post-L-BT. At last follow-up, two patients only had normal liver tests and ultrasound.

CONCLUSION

BDC after L-BT can cause severe morbidities. Pancreatic reduction might increase this risk. Early surgical complications or chronic pancreatic rejection might be co-factors. Early diagnosis and treatment are key to the long-term prognosis.

Optical coherence tomography of small intestine allograft biopsies using a handheld surgical probe

SIGNIFICANCE

The current gold standard for monitoring small intestinal transplant (IT) rejection is endoscopic visual assessment and biopsy of suspicious lesions; however, these lesions are only superficially visualized by endoscopy. Invasive biopsies provide a coarse sampling of tissue health without depicting the true presence and extent of any pathology. Optical coherence tomography (OCT) presents a potential alternative approach with significant advantages over traditional white-light endoscopy.

AIM

The aim of our investigation was to evaluate OCT performance in distinguishing clinically relevant morphological features associated with IT graft failure.

APPROACH

OCT was applied to evaluate the small bowel tissues of two rhesus macaques that had undergone IT of the ileum. The traditional assessment from routine histological observation was compared with OCT captured using a handheld surgical probe during the days post-transplant and subsequently was compared with histophaology.

RESULTS

The reported OCT system was capable of identifying major biological landmarks in healthy intestinal tissue. Following IT, one nonhuman primate (NHP) model suffered a severe graft ischemia, and the second NHP graft failed due to acute cellular rejection. OCT images show visual evidence of correspondence with histological signs of IT rejection.

CONCLUSIONS

Results suggest that OCT imaging has significant potential to reveal morphological changes associated with IT rejection and to improve patient outcomes overall.

Cost-effectiveness of Intestinal Transplantation Compared to Parenteral Nutrition in Adults

BACKGROUND

Intestinal transplantation (ITx) is the most expensive abdominal organ transplant. Detailed studies about exact costs and cost-effectiveness compared to home parenteral nutrition (HPN) therapy in chronic intestinal failure are lacking. The aim is to provide an in-depth analysis of ITx costs and evaluate cost-effectiveness compared to HPN.

METHODS

To calculate costs before and after ITx, costs were analyzed in 12 adult patients. To calculate the costs of patients with uncomplicated chronic intestinal failure, 28 adults, stable HPN patients were studied. Total costs including surgery, admissions, diagnostics, HPN therapy, medication, and ambulatory care were included. Median (range) costs are given.

RESULTS

Costs before ITx were €69 160 (€60 682-90 891) in year 2, and €104 146 (€83 854-186 412) in year 1. After ITx, costs were €172 133 (€122 483-351 407) in the 1st year, €40 619 (€3905-113 154) in the 2nd year, and dropped to €15 743 (€4408-138 906) in the 3rd year. In stable HPN patients, the costs were €83 402 (€35 364-169 146) in the 1st year, €70 945 (€31 955-117 913) in the 2nd year, and stabilized to €60 242 (€29 161-238 136) in the 3rd year.

CONCLUSIONS

ITx, although initially very expensive, is cost-effective compared to HPN in adults by year 4, and cost-saving by year 5.

Intestinal Transplantation at a Single Institution in Japan

BACKGROUND

This study aimed to compare the clinical outcomes of intestinal transplantation (ITX) between 2 groups by using medications for induction treatment and assess the utility of the current protocol.

METHODS

From 2003 to 2020, 11 patients underwent ITX. Recipients were classified into 2 groups: group IL-2Ra (interleukin-2 receptor antagonist therapy, n = 6) and ATG (rabbit antithymocyte globulin therapy, n = 5). We conducted a retrospective review of patient and graft survival rates and the postoperative course.

RESULTS

The 1-, 5-, and 10-year patient and graft survival rates of the 11 primary grafts in the 11 recipients were 100%, 88.9%, 62.2% and 90.0%, 78.8%, 56.3%, respectively. The median duration of follow-up for the IL-2Ra and ATG groups was 197.3 and 87.3 months, respectively. The 1-, 5-, and 10-year patient survival rates were 100%, 83.3%, 50% and 100%, 100%, 100% for the IL-2Ra and ATG groups, respectively (P = .25) and 83.3%, 66.7%, 33.3% and 100%, 100%, 100% for graft survival in the IL-2Ra and ATG groups, respectively (P = .08). The incidence of moderate and severe acute rejection was 100% and 20% in the IL-2Ra and ATG groups, respectively (P = .02). The 1- and 5-year moderate and severe rejection-free survival rates were 33.3%, 0% and 80%, 80% in the IL-2Ra and ATG groups, respectively (P = .04).

CONCLUSIONS

ATG significantly suppressed moderate and severe acute rejection compared with IL-2Ra, thereby showing better short- and mid-term rejection-free survival rates. Additional clinical experience is needed to determine the optimal regimen for the management of ITX recipients.

Quality of life in long term survivors of pediatric intestinal transplantation compared with liver transplantation and home parenteral nutrition: A prospective single-center pilot study

Health-related quality of life (HRQOL) after intestinal transplantation (IT) is important, as many psychological troubles have been reported in these patients on the long term. Our aim was to assess and compare HRQOL of patients after IT to patients after liver transplantation (LT) or on home parenteral nutrition (HPN) for intestinal failure. A cross-sectional study included patients and their parents between 10 and 18 years of age, on HPN for more than 2 years, or who underwent IT or LT, with a graft survival longer than 2 years. Quality of life was explored by Child Health Questionnaire. Thirteen children-parents dyads after IT, 10 after LT, and eight children on HPN completed the survey. Patients were a median age of 14 years old, a median of 10 years post-transplantation or on HPN. Patients after IT scored lower than patients after LT or on HPN in "social limitations due to behavioral difficulties" and in "behavior." They scored higher than those on HPN in "global health." Parents of children after IT scored lower than those after LT in many domains. No relevant correlation with clinical data was found. Our study showed the multi-level impact of IT on quality of life of patients and their parents. It highlights the importance of a regular psychological follow-up for patients, but also of a psychological support for families. Helping the patients to overcome the difficulties at adolescence may improve their mental health in adulthood.

Lymphohematopoietic graft-versus-host responses promote mixed chimerism in patients receiving intestinal transplantation

In humans receiving intestinal transplantation (ITx), long-term multilineage blood chimerism often develops. Donor T cell macrochimerism (≥4%) frequently occurs without graft-versus-host disease (GVHD) and is associated with reduced rejection. Here we demonstrate that patients with macrochimerism had high graft-versus-host (GvH) to host-versus-graft (HvG) T cell clonal ratios in their allografts. These GvH clones entered the circulation, where their peak levels were associated with declines in HvG clones early after transplant, suggesting that GvH reactions may contribute to chimerism and control HvG responses without causing GVHD. Consistently, donor-derived T cells, including GvH clones, and CD34+ hematopoietic stem and progenitor cells (HSPCs) were simultaneously detected in the recipients' BM more than 100 days after transplant. Individual GvH clones appeared in ileal mucosa or PBMCs before detection in recipient BM, consistent with an intestinal mucosal origin, where donor GvH-reactive T cells expanded early upon entry of recipient APCs into the graft. These results, combined with cytotoxic single-cell transcriptional profiles of donor T cells in recipient BM, suggest that tissue-resident GvH-reactive donor T cells migrated into the recipient circulation and BM, where they destroyed recipient hematopoietic cells through cytolytic effector functions and promoted engraftment of graft-derived HSPCs that maintain chimerism. These mechanisms suggest an approach to achieving intestinal allograft tolerance.

Tacrolimus time-in-therapeutic range is associated with freedom from acute rejection and graft failure following intestinal transplantation

BACKGROUND

Trough-adjusted tacrolimus is commonly prescribed following intestinal transplantation to prevent allograft rejection. Despite established practice, there remains limited direct evidence linking tacrolimus levels with improved clinical outcomes.

METHODS

This was a single-center review of all adult non-liver containing intestinal allograft recipients from 2011 to 2018. Patients received lymphocyte depleting induction and maintenance immunosuppression consisting of tacrolimus and a corticosteroid taper. Tacrolimus time-in-therapeutic range (TAC-TTR) was calculated for all patients from the date of transplant until 1-year post-transplant using Rosendaal's method. Cox-Proportional hazards modeling was utilized to assess freedom from acute rejection and graft failure stratified by TAC-TTR quartile.

RESULTS

47 patients were included in the review. Mean TAC-TTR for the cohort was 30.2% ± 11.4. Fifteen episodes of acute rejection were observed, 8 of which were severe. Patients in the highest TAC-TTR quartile >36% had a lower incidence of acute rejection and graft failure relative to patients with a TAC-TTR <20%. Cox-Proportional hazards modeling found a 10% decrease in TAC-TTR was associated with an increased hazard for acute rejection (2.03), severe acute rejection (2.19), and graft loss (3.33).

CONCLUSION

The results of this study suggest that decreasing TAC-TTR is a risk factor for both acute rejection as well as intestinal allograft failure.

Non-HLA AT1R antibodies are highly prevalent after pediatric intestinal transplantation

The role of angiotensin II type-1 receptor (AT1R) antibodies in intestinal transplantation (ITx) is unclear. The aims were 1) to identify the prevalence of AT1R antibodies in pediatric ITx, compared to pediatric intestinal failure (IF), and 2) to determine whether AT1R antibodies were associated with graft dysfunction. 46 serum samples from 25 ITx patients (3 isolated ITx, 22 liver-inclusive ITx) were collected during routine visits >6 months apart and during episodes of graft dysfunction as a result of infectious enteritis or rejection. For comparison, samples were collected from 7 IF control patients. AT1R antibodies were considered positive for levels >17 U/mL. The median (range) AT1R antibody level for ITx patients was 40.0 U/mL (7.2-40.0), compared to 7.0 U/mL (5.7-40.0) for IF patients (p = .02). There was a trend toward higher prevalence of AT1R antibodies in ITx compared with IF patients (68% versus 29%, p = .09). Among ITx patients, the prevalence of AT1R antibodies was not different between periods of active graft dysfunction and normal health (83% versus 67%, p = .31). For 16 patients with >2 samples, AT1R antibodies remained positive in 67% cases, developed in 14% cases, disappeared in 10% cases, and remained negative in 10% cases. The changes in AT1R antibodies did not correlate with de/sensitizing events. This is the first study of AT1R antibodies in pediatric ITx. AT1R antibodies are highly prevalent after ITx and may be triggered by immune activation associated with the transplant. However, their pathogenicity and clinical utility remain in question.

Late graft loss after intestinal transplantation

PURPOSE OF REVIEW

Despite improvement in short-term outcomes after intestinal transplantation in the last 20 years, long-term rates of graft attrition and patient survival remain unchanged, with worse outcomes compared with other solid organ transplants. This review investigates the multiple causes of late graft loss, including chronic rejection, infection, graft-versus-host disease, posttransplant lymphoproliferative disorder and postsurgical complications.

RECENT FINDINGS

New insights into immunology of the intestine and evolution of immunosuppression, as well as review of current persistent causes of late graft loss, shed light on findings that may help improve long-term intestinal allograft survival.

SUMMARY

Although intestinal transplantation remains a life-saving intervention with significant advancements since its inception, further understanding of mechanisms of injury is needed to improve long-term outcomes and prevent late intestinal graft loss.

Surveillance of Rejection After Intestinal Transplantation Using an Image Enhanced Endoscopy "VENCH" Scoring System

BACKGROUND

Graft rejection after intestinal transplantation remains challenging. We aimed to use endoscopy for rejection prediction.

MATERIALS AND METHODS

Patients ≥7 years old who underwent intestinal transplantation between November 2016 and September 2019 were prospectively enrolled. Magnifying endoscopy under narrow-band imaging was performed through ileostomy. Endoscopic findings were reported as five components (each graded from 0-2): "V" (villi appearance), "E" (erythema), "N" (capillary network), "C" (crypt widening), and "H" (heterogeneity). The correlation between histological severity and endoscopic score was analyzed.

RESULTS

Ninety-nine endoscopic biopsies from three female and one male patient were analyzed. The mean ± SD age was of 41.25±13.77 (range 29-58) years. Three short bowel syndrome patients after multiple intestinal resections and one with chronic intestinal pseudo-obstruction were indicated for intestinal transplantation. Sensitivity, specificity, and accuracy of V, E, N, C, and H scores for predicting rejection were 97.4%, 45.9%, 65.7%; 94.7%, 70.5%, 79.8%; 97.4%, 52.5%, 69.7%; 94.7%, 54.1%, 69.7%; and 97.4%, 62.3%, 75.8%, respectively. Pearson's correlation coefficients between total and individual V, E, N, C, H scores and histological rejection were 0.79, 0.64, 0.70, 0.71, 0.73, and 0.66, respectively (P < .001). To predict mild and moderate/severe rejection, total scores more than 4 and 6 had the sensitivity/specificity of 87.50%/57.38% and 96.67%/85.25%, respectively (area under the ROC 0.791 and 0.987).

CONCLUSION

Endoscopic VENCH scoring is promising for predicting rejection after IT. More studies are warranted to validate such results. (ClinicalTrials.gov number, NCT03616548.).

Hydrogel-based 3D bioprints repair rat small intestine injuries and integrate into native intestinal tissue

3D Printing has become a mainstay of industry, with several applications in the medical field. One area that could benefit from 3D printing is intestinal failure due to injury or genetic malformations. We bioprinted cylindrical tubes from rat vascular cells that were sized to form biopatches. 2 mm enterotomies were made in the small intestine of male Sprague-Dawley rats, and sealed with biopatches. These intestinal segments were connected to an ex vivo perfusion device that provided independent extraluminal and intraluminal perfusion. The fluorescence signal of fluorescein isothiocyanate (FITC)-inulin in the intraluminal perfusate, a non-absorbable fluorescent marker of intestinal integrity, was measured every 15 min over 90 min, and used to assess the integrity of the segments under both continuous perfusion and alternate-flow perfusion. Enterotomies were made an inch away from the ileocecal junction in male Wistar rats and sealed with biopatches. The animals were monitored daily and euthanized at post-operative days 7, 14, 21, and 30. Blinded histopathological analysis was conducted to compare the patch segments to native intestine. Biopatch-sealed intestinal segments withstood both continuous and pulsatile flow rates without leakage of FITC-inulin above the control baseline. 21 of 26 animals survived with normal activity, weight gain, and stool output. Histopathology of the explanted segments showed progressive villi and crypt formation over the enterotomies, with complete restoration of the epithelium by 30 days. This study presents a novel application of 3D bioprinting to develop a universal repair patch that can seal lesions in vivo, and fully integrate into the native intestine.

Case report: Total enterectomy following complete small bowel ischaemia in the post-peritonectomy setting

•

Small bowel resection following total ischaemia is feasible post-peritonectomy.

•

VAC dressing and skin grafting was beneficial following wound dehiscence.

•

Small bowel transplant is a potential means to avoid complications of long-term TPN.

Introduction

This report presents the rare case of a patient with complete bowel ischaemia following parastomal hernia, leading to total bowel resection, with consideration of post-operative complications and wound management.

Presentation of case

A 59 year old female was found to have complete small bowel ischaemia on exploratory laparatomy, on a background of recurrent appendiceal adenomucinosis, for which she had received previous peritonectomy, cholecystectomy, total colectomy, and partial small bowel resection. The patient was managed with total enterectomy and post-operative total parenteral nutrition.

Discussion

Total enterectomy represents a significant challenge in the postperitonectomy setting, including consideration of wound management with the empty abdomen, and the potential of small bowel transplant in management.

Conclusion

Resection of the small bowel following total small bowel ischaemia is feasible in the post-peritonectomy setting, given appropriate post-operative care and wound management. However, long-term survival remains challenging, especially without small bowel transplant.

HTK-N: Modified Histidine-Tryptophan-Ketoglutarate Solution-A Promising New Tool in Solid Organ Preservation

To ameliorate ischemia-induced graft injury, optimal organ preservation remains a critical hallmark event in solid organ transplantation. Although numerous preservation solutions are in use, they still have functional limitations. Here, we present a concise review of a modified Histidine-Tryptophan-Ketoglutarate (HTK) solution, named HTK-N. Its composition differs from standard HTK solution, carrying larger antioxidative capacity and providing inherent toxicity as well as improved tolerance to cold aiming to attenuate cold storage injury in organ transplantation. The amino acids glycine, alanine and arginine were supplemented, N-acetyl-histidine partially replaced histidine, and aspartate and lactobionate substituted chloride. Several in vitro studies confirmed the superiority of HTK-N in comparison to HTK, being tested in vivo in animal models for liver, kidney, pancreas, small bowel, heart and lung transplantation to adjust ingredients for required conditions, as well as to determine its innocuousness, applicability and potential advantages. HTK-N solution has proven to be advantageous especially in the preservation of liver and heart grafts in vivo and in vitro. Thus, ongoing clinical trials and further studies in large animal models and consequently in humans are inevitable to show its ability minimizing ischemia-induced graft injury in the sequel of organ transplantation.

Human Small Intestine Transplantation: Segmental Susceptibility to Ischemia Using Different Preservation Solutions and Conditions

BACKGROUND AND AIMS

Among all transplanted abdominal organs, the small intestine is one of the most ischemia sensitive. Appropriate graft selection, procurement, and preservation are crucial for optimum graft and patient survival. We evaluated ischemic damage in human small intestine grafts under different hypothermic preservation conditions (cold static and continuous perfusion) and solutions: histidine-tryptophan-ketoglutarate (HTK) and University of Wisconsin (UW).

METHODS

Fourteen small intestinal grafts were procured from deceased donors. HTK and UW were used for the vascular perfusion at the cross clamp, and UW, HTK, or Ringer Lactate were used for the luminal flush at the back table. Therefore, part of the same harvested intestine was stored in cold static storage and in continuous perfusion preservation (with intestinal perfusion unit) simultaneously. Histological samples were collected from the jejunum and ileum at different time points and different preservation conditions. The samples were collected before the initiation of cold storage (T0), after 8 hours of cold static (ST8), or after 8 hours of continuous perfusion preservation (PT8) (n = 161 samples). Blinded histological evaluation was conducted and ischemic damage was determined using the Park/Chiu scale.

RESULTS

The ileum had less ischemic damage than the jejunum, regardless of using static or continuous perfusion preservation. There was no significantly ischemic damage difference between intestinal grafts flushed and perfused with UW or HTK.

CONCLUSION

The jejunum is more susceptible to ischemic injury than the ileum. UW and HTK are equivalent to preserve intestinal graft. This suggests that selective transplantation of ileum could reduce ischemia-related postoperative complications.

Immunologic Complications and Graft Survival in Crohn's Disease and NOD2 Mutant Non-Crohn's Disease Adult Recipients Following Intestine Transplantation

Despite improved outcomes in the modern era of targeted immunotherapy, intestinal failure and chronic parenteral nutrition remains a significant burden for patients with Crohn’s disease (CD) worldwide. Transplantation is a key component of management when a patient with CD suffers from life-threatening complications of parenteral nutrition. Nucleotide-binding oligomerization domain 2 (NOD2) mutation is a risk factor for both development of CD and intestinal allograft rejection.

Short Bowel Syndrome in an Infant

Short bowel syndrome (SBS) is a malabsorptive state that may occur either after surgical bowel resection or as the result of congenital bowel anomalies. SBS can incur significant morbidity and mortality including intestinal failure, cholestasis, sepsis, and death. For patients with SBS, management involves a multidisciplinary approach that begins with neonatology, pediatric surgery, nutritionists, pharmacists, and nurses in the NICU and also includes the transition to an intestinal rehabilitation program. The aim of this review is to provide the neonatologist with an overview of the common causes of neonatal SBS, anticipated nutritional deficiencies, complications associated with SBS, and the surgical and medical management of SBS to assist in counseling affected families.

Atypical malignancies after intestinal transplantation in children: A European single-centre experience

BACKGROUND

Post-transplant malignancies, that is, lymphomas, are a recognized complication in intestinal transplant recipients but are mostly secondary to EBV infection. There is an increased risk for malignancies in unusual sites in intestinal transplant recipients as compared to other solid organ transplants and the general population.

OBJECTIVE

To evaluate the incidence, course, and outcome of unusual malignancies in children after ITx.

METHODS

Retrospective analysis of children who underwent ITx for primary digestive disorders at Birmingham Children's Hospital between January 1989 and December 2017.

RESULTS

Ninety-eight intestinal transplants were performed in 90 children (49 males and 41 females) with an underlying primary digestive disorder. Median age was 2.7 years (0.6-16.2), and median weight was 14.5 kg (5.7-53.2) at the time of transplant. Within this cohort, we identified four cases of unusual malignancies at rare sites of presentation. One patient developed cerebral PTLD, two patients were diagnosed with SMT, located at the stomal orifice and in cervicothoracic paravertebral area, respectively, and the last patient developed a retroperitoneal angiosarcoma. Unfortunately, the overall patient outcome was poor in all but one child with SMT, who currently survives with cytotoxic T-cell therapy.

CONCLUSION

Unusual malignancies can occur in approximately 5% of children following ITx. A high index of suspicion is required for a timely diagnosis and adequate treatment.

Medawar's Paradox and Immune Mechanisms of Fetomaternal Tolerance

Brazilian-born British biologist Dr. Peter Medawar played an integral role in developing the concepts of immunologic rejection and tolerance, which led to him receiving the Nobel Prize "for the discovery of acquired immunologic tolerance" and eventually made organ transplantation a reality. However, at the time of his early work in tolerance, a paradox to his theories was brought to his attention; how was pregnancy possible? Pregnancy resembles organ transplantation in that the fetus, possessing paternal antigens, is a semi-allogeneic graft that can survive without immunosuppression for 9 months. To answer this question, Medawar proposed three hypotheses of how a mother supports her fetus in utero, now known as "Medawar's Paradox." The mechanisms that govern fetomaternal tolerance are still incompletely understood but may provide critical insight into how to achieve immune tolerance in organ transplantation. Here, we review current understanding of the immune factors responsible for fetomaternal tolerance during pregnancy and discuss the potential implications for advances in transplantation science.

Association of More Intensive Induction With Less Acute Rejection Following Intestinal Transplantation: Results of 445 Consecutive Cases From a Single Center

BACKGROUND

In intestinal transplantation, acute cellular rejection (ACR) remains a significant challenge to achieving long-term graft survival. It is still not clear which are the most important prognostic factors.

METHODS

We performed a Cox multivariable analysis of the hazard rates of developing any ACR, severe ACR, and cause-specific graft loss during the first 60 months posttransplant among 445 consecutive intestinal transplant recipients at our institution since 1994. Of particular interest was to determine the prognostic influence of induction type: rabbit antithymocyte globulin (rATG; 2 mg/kg × 5)/rituximab (150 mg/m × 1; begun in 2013), alemtuzumab (2001-2011), and less intensive forms.

RESULTS

First ACR and severe ACR occurred in 61.3% (273/445) and 22.2% (99/445) of cases. The following 3 multivariable predictors were associated with significantly lower hazard rates of developing ACR and severe ACR: transplant type modified multivisceral or full multivisceral (P = 0.0009 and P < 0.000001), rATG/rituximab induction (P < 0.000001 and P < 0.01), and alemtuzumab induction (P = 0.004 and P = 0.07). For both ACR and severe ACR, the protective effects of rATG/rituximab and alemtuzumab were highly significant (P ≤ 0.000005 for ACR; P ≤ 0.01 for severe ACR) but only during the first 24 days posttransplant (when the ACR hazard rate was at its peak). The prognostic effects of rATG/rituximab and alemtuzumab on ACR/severe ACR disappeared beyond 24 days posttransplant (ie, nonproportional hazards). While significant protective effects of both rATG/rituximab and alemtuzumab existed during the first 6 months posttransplant for the hazard rate of graft loss-due-to-rejection (P = 0.01 and P = 0.003), rATG/rituximab was additionally associated with a consistently lower hazard rate of graft loss-due-to-infection (P = 0.003). All significant effects remained after controlling for the propensity-to-be-transplanted since 2013.

CONCLUSIONS

More intensive induction was associated with a significant lowering of ACR risk, particularly during the early posttransplant period.

Intra-abdominal infections among adult intestinal and multivisceral transplant recipients in the 2-year post-operative period

BACKGROUND

Intestinal and multivisceral transplantations are treatment options for patients with intestinal failure. Transplantation is often complicated by abdominal and/or bloodstream infections in the post-operative period.

METHODS

A retrospective chart review of all adults who underwent intestinal or multivisceral transplantation at our institution from 2003 to 2015 was performed. Data were collected for 2 years post transplant.

RESULTS

A total of 106 intestinal or multivisceral transplants were performed in 103 patients. The median age at the time of transplant was 44 (IQR: 34-52) with 55% (n = 58) male and 45% (n = 48) female. There were 46 (43%) intra-abdominal infections post transplant among the 103 patients, and six transplant recipients (13%) developed concurrent bloodstream infections. The median time to first intra-abdominal infection was 23 days (IQR: 10-48). For those with organisms isolated in culture, forty-seven percent of the isolates were gram negative, 39% gram positive, 7% anaerobes, and 7% yeast. The most common isolates were enterococci at 28%, E. coli at 14%, and Klebsiella spp at 13%. Sixty-three percent of the enterococci were vancomycin-resistant enterococci (VRE), and 22% of the gram-negative isolates were extended spectrum beta-lactamases (ESBLs). Patients with intra-abdominal infections had longer hospital post-transplant length of stays at a median of 35 days (IQR: 25-48) vs 23 days (IQR: 17-33) for those without infections, P = .0012. There was no difference in all-cause mortality in patients with or without intra-abdominal infections, P = .654.

CONCLUSIONS

Intra-abdominal infections are common in intestinal or multivisceral transplant recipients, but despite this complication, we found no increased risk of mortality. These transplant recipients are also at risk for infection with drug-resistant organisms.

Indications of Intestinal Transplantation

"The intestinal transplantation is reserved for patients with life-threatening complications of permanent intestinal failure or underlying gastrointestinal disease. The choice of the allograft for a particular patient depends on several factors and the presence of concurrent organ failure, and availability of the donor organs, and specialized care. Combined liver and intestinal transplant allows for patients who have parenteral nutrition-associated liver disease a possibility of improved quality of life and nutrition as well as survival. Intestinal transplantation has made giant strides over the past few decades to the present era where current graft survivals are comparable with other solid organ transplants."

Integrated Counts of Carbohydrate-Active Protein Domains as Metabolic Readouts to Distinguish Probiotic Biology and Human Fecal Metagenomes

Bowel microbiota is a "metaorgan" of metabolisms on which quantitative readouts must be performed before interventions can be introduced and evaluated. The study of the effects of probiotic Clostridium butyricum MIYAIRI 588 (CBM588) on intestine transplantees indicated an increased percentage of the "other glycan degradation" pathway in 16S-rRNA-inferred metagenomes. To verify the prediction, a scoring system of carbohydrate metabolisms derived from shotgun metagenomes was developed using hidden Markov models. A significant correlation (R = 0.9, p < 0.015) between both modalities was demonstrated. An independent validation revealed a strong complementarity (R = -0.97, p < 0.002) between the scores and the abundance of "glycogen degradation" in bacteria communities. On applying the system to bacteria genomes, CBM588 had only 1 match and ranked higher than the other 8 bacteria evaluated. The gram-stain properties were significantly correlated to the scores (p < 5 × 10^-4). The distributions of the scored protein domains indicated that CBM588 had a considerably higher (p < 10^-5) proportion of carbohydrate-binding modules than other bacteria, which suggested the superior ability of CBM588 to access carbohydrates as a metabolic driver to the bowel microbiome. These results demonstrated the use of integrated counts of protein domains as a feasible readout for metabolic potential within bacteria genomes and human metagenomes.

Short Bowel Syndrome

Purpose of Review

Short gut syndrome is life-altering and life-threatening disease resulting most often from massive small bowel resection. Recent advances in understanding of the perturbed physiology in these patients have translated into improved care and outcomes. This paper seeks to review the advances of care in SBS patients.

Recent Findings

Anatomic considerations still predominate the early care of SBS patients, including aggressive preservation of bowel and documentation of remnant bowel length and quality. Intestinal adaptation is the process by which remnant bowel changes to fit the physiologic needs of the patient. Grossly, the bowel dilates and elongates to increase intestinal weight and protein content. Architectural changes are noted, such as villus lengthening and deepening of crypts. In addition, gene expression changes occur that function to maximize nutrient uptake and fluid preservation. Management is aimed at understanding these physiologic changes and augmenting them whenever possible in an effort to gain enteral autonomy. Complication mitigation is key, including avoidance of catheter complications, bloodstream infections, cholestasis, and nutrient deficiencies.

Summary

Multidisciplinary teams working together towards intestinal rehabilitation have shown improved outcomes. Today's practioner needs a current understanding of the ever-evolving care of these patients in order to promote enteral autonomy, recognize complications, and counsel patients and families appropriately.

Review article: diagnosis and management of intestinal failure-associated liver disease in adults

BACKGROUND

Hepatic disturbances in the context of intestinal failure and parenteral nutrition (PN) are frequently encountered and carry a significant burden of morbidity and sometimes mortality. The term intestinal failure-associated liver disease (IFALD) refers to liver injury due to intestinal failure and associated PN, in the absence of another evident cause of liver disease, encompassing a spectrum of conditions from deranged liver enzymes, steatosis/ steatohepatitis, cholestasis as well as progressive fibrosis, cirrhosis and end-stage liver disease.

AIMS

To present an up to date perspective on the diagnosis/definition, aetiologies and subsequent management of IFALD and to explore future consideration for the condition, including pharmacological therapies RESULTS: In adults using long-term PN for benign chronic intestinal failure, 1%-4% of all deaths are attributed to IFALD. The aetiology of IFALD is multifactorial and can be broadly divided into nutritional factors (eg lipid emulsion type) and patient-related factors (eg remaining bowel anatomy). Given its multifaceted aetiology, the management of IFALD requires clinicians to investigate a number of factors simultaneously. Patients with progressive liver disease should be considered for combined liver-intestine transplantation, although multivisceral grafts have a worse prognosis. However, there is no established non-invasive method to identify progressive IFALD such that liver biopsy, where appropriate, remains the gold standard.

CONCLUSION

A widely accepted definition of IFALD would aid in diagnosis, monitoring and subsequent management. Management can be complex with a number of factors to consider. In the future, dedicated pharmacological interventions may become more prominent in the management of IFALD.

Intra-abdominal infections in solid organ transplant recipients: Guidelines from the American Society of Transplantation Infectious Diseases Community of Practice

This new guideline from the AST IDCOP reviews intra-abdominal infections (IAIs), which cause substantial morbidity and mortality among abdominal SOT recipients. Each transplant type carries unique risks for IAI, though peritonitis occurs in all abdominal transplant recipients. Biliary infections, bilomas, and intra-abdominal and intrahepatic abscesses are common after liver transplantation and are associated with the type of biliary anastomosis, the presence of vascular thrombosis or ischemia, and biliary leaks or strictures. IAIs after kidney transplantation include renal and perinephric abscesses and graft-site candidiasis, which is uncommon but may require allograft nephrectomy. Among pancreas transplant recipients, duodenal anastomotic leaks can have catastrophic consequences, and polymicrobial abscesses can lead to graft loss and death. Intestinal transplant recipients are at the highest risk for sepsis, infection due to multidrug-resistant organisms, and death from IAI, as the transplanted intestine is a contaminated, highly immunological, pathogen-rich organ. Source control and antibiotics are the cornerstone of the management of IAIs. Empiric antimicrobial regimens should be tailored to local susceptibility patterns and pathogens with which the patient is known to be colonized, with subsequent optimization once the results of cultures are reported.

One-year Incidence of Infection in Pediatric Intestine Transplantation

BACKGROUND

This study reports the infection rate, location of infection and pathogen causing bacterial, fungal or viral infections in intestine transplant recipients at a pediatric transplant center.

METHODS

Records from a pediatric center were reviewed for patients receiving an intestine transplant. Positive cultures and pathology reports were used to diagnose bacterial, fungal and viral infections and also to determine location and infectious agent. Risk for infection was assessed based on liver or colon inclusion, and immunosuppression induction, as part of the intestine transplant.

RESULTS

During the study period, 52 intestine transplants were performed on 46 patients. Bacterial, fungal and viral infection rates were 90%, 25% and 75%, respectively. Enterococcus spp. (non-vancomycin-resistant enterococci) were the most common pathogens and were isolated from 52% of patients. Non-vancomycin-resistant enterococci was present in 12% of transplant recipients. Candida spp. were the most common fungal pathogens (23% of patients). Respiratory viral infections were common (44%), and Cytomegalovirus infection rate was 17%. Common sites of infection were bloodstream, urinary and upper respiratory tract. Colon and liver inclusion in the transplant graft was not associated with increased risk of infection, nor was addition of rituximab to the immunosuppression induction protocol.

CONCLUSIONS

Postintestine transplant infections are ubiquitous in the pediatric population, including high rates of infection from bacterial, viral and fungal sources. Inclusion of the liver and/or colon as a component of the transplant graft did not appear to greatly impact the infectious risk. Adding rituximab to the immunosuppression induction protocol did not impact on infectious risk.

Donor-Specific Antibodies in Pediatric Intestinal and Multivisceral Transplantation: The Role of Liver and Human Leukocyte Antigen Mismatching

Rejection is one of the most important drawbacks for graft and patient survival in intestinal and multivisceral transplantation. However, there is no consensus on the diagnostic criteria for humoral rejection, and the literature about the role of donor-specific antibodies (DSA) on allograft outcome and the risk factors that contribute to their development is scant with contradictory results. The present study analyzes the role of DSA exclusively in a pediatric cohort of 43 transplants. Among our patients, 11.6% showed preformed DSA, but they did not correlate with more rejection or less allograft survival. Having previous transplants was the main sensitization factor with an odds ratio (OR) = 44.85 (P = 0.001). In total, 16.3% of recipients developed de novo donor-specific antibodies (dnDSA), mostly directed against human leukocyte antigen (HLA) class II, polyspecific and complement fixing. Additionally, the presence of dnDSA had a deleterious effect on graft rejection (hazard ratio [HR] = 11.00; P = 0.01) and survival (HR = 66.52; P < 0.001) in an observational period of 5 years after transplantation. The inclusion of the liver emerged as the main protective factor against dnDSA development with an OR = 0.07 (P = 0.007). The analysis of HLA compatibility at the serological and epitope level with the computational tools HLAMatchmaker and PIRCHE revealed no association between HLA mismatching and dnDSA. In conclusion, this study performed in pediatric recipients shows the deleterious effect of dnDSA on intestinal transplantation supported by the complement-fixing activity observed. Additionally, the liver inclusion in the allografts showed to be a protective factor against dnDSA generation.

Antibody-mediated rejection in pediatric small bowel transplantation: Capillaritis is a major determinant of C4d positivity in intestinal transplant biopsies

The diagnostic criteria for antibody-mediated rejection (ABMR) after small bowel transplantation (SBT) are not clearly defined, although the presence of donor-specific antibodies (DSAs) has been reported to be deleterious for graft survival. We aimed to determine the incidence and prognostic value of DSAs and C4d in pediatric SBT and to identify the histopathologic features associated with C4d positivity. We studied all intestinal biopsies (IBx) obtained in the first year posttransplantation (N = 345) in a prospective cohort of 23 children. DSAs and their capacity to fix C1q were identified by using Luminex technology. Eighteen patients (78%) had DSAs, and 9 had the capacity to fix C1q. Seventy-eight IBx (22.6%) were C4d positive. The independent determinants of C4d positivity were capillaritis grades 2 and 3 (odds ratio [OR] 4.02, P = .047 and OR 5.17, P = .003, respectively), mucosal erosion/ulceration (OR 2.8, P = .019), lamina propria inflammation grades 1 and 2/3 (OR 1.95, P = .043 and OR 3.1, P = .016, respectively), and chorion edema (OR 2.16, P = .028). Complement-fixing DSAs and repeated C4d-positive IBx were associated with poor outcome (P = .021 and P = .001, respectively). Our results support that capillaritis should be considered as a feature of ABMR in SBT and identify C1q-fixing DSAs and repeated C4d positivity as potential markers of poor outcome.

Outcomes of Adult Intestinal Transplant Recipients Requiring Dialysis and Renal Transplantation

Supplemental digital content is available in the text.

Background

Data on dialysis and renal transplantation (RT) after intestinal transplantation (IT) are sparse. Whether changes in immunosuppression and surgical techniques have modified these outcomes is unknown.

Methods

Two hundred eighty-eight adult intestinal transplants performed between 1990 and 2014 at the University of Pittsburgh were analyzed for incidence, risk factors and outcomes after dialysis and RT. Cohort was divided into 3 eras based on immunosuppression and surgical technique (1990-1994, 1995-2001, and 2001-2014). Receiving RT, or dialysis for 90 days or longer was considered as end-stage renal disease (ESRD).

Results

During a median follow-up of 5.7 years, 71 (24.7%) patients required dialysis, 38 (13.2%) required long-term dialysis and 17 (6%) received RT after IT. One-, 3-, and 5-year ESRD risk was 2%, 7%, and 14%, respectively. No significant era-based differences were noted. Higher baseline creatinine (hazard ratio [HR], 3.40 per unit increase, P < 0.01) and use of liver containing grafts (HR, 2.01; P = 0.04) had an increased ESRD risk. Median patient survival after dialysis initiation was 6 months, with a 3-year survival of 21%. Any dialysis (HR, 12.74; 95% CI 8.46-19.20; P < 0.01) and ESRD (HR, 9.53; 95% CI, 5.87-15.49; P < 0.01) had higher mortality after adjusting for covariates. For renal after IT, 1- and 3-year kidney and patient survivals were 70% and 49%, respectively. All graft losses were from death with a functioning graft, primarily related to infectious complications (55%).

Conclusions

In intestinal transplant recipients, renal failure requiring dialysis or RT is high and is associated with increased mortality. Additionally, the outcomes for kidney after IT are suboptimal due to death with a functioning graft.

Comparable outcomes in intestinal retransplantation: Single-center cohort study

BACKGROUND

Graft loss in intestinal transplantation (ITx) is close to 25% in the first year and 50% at 5-year post-transplantation. Although technically and immunologically challenging, intestinal retransplantation is now the 4th most common indication for ITx.

METHODS

The aim of this study was to review and compare the outcomes of intestinal retransplantation with primary ITx, which included isolated ITx, modified multivisceral transplantation (mMVTx), and full MVTx, between 2003 and 2014 at Indiana University.

RESULTS

Of 218 ITx, 18 (8.3%) were retransplantation. Causes of graft loss were rejection(78%), pancreatitis (11%), and severe intestine dismotility (11%). MVTx (16/18, 89%) was the preferred retransplantation option. In 7 (39%) patients, graftectomy was performed between primary and intestinal retransplantation. Median interval between primary ITx and retransplantation was 421 days. Although patient and graft survival rates at 1 year, 3 years, and 5 years were comparable between primary and retransplants, the number of retransplants was limited in the follow-up after post-transplant year 3.

CONCLUSIONS

We identified that timing of retransplantation, graftectomy prior to retransplant allowing an immunosuppression free state, inclusion of the liver, and preserved renal function are important factors in the consideration of intestinal retransplantation. Immunological aspects remain challenging in the decision making and for short- and long-term outcomes.

Prophylactic rtPA in the Prevention of Line-associated Thrombosis and Infection in Short Bowel Syndrome

BACKGROUND

Central venous access devices (CVADs) are essential for total parenteral nutrition administration in patients with short bowel syndrome (SBS). They are, however, fraught with complications including infection and venous thromboembolism (VTE), which increases associated morbidity and mortality in this population. There is evidence linking the development of CVAD-associated thrombosis and line-related infection. Thus, it has been postulated that prevention of catheter-related clot formation could minimize the risk of infection originating from the catheter. Recombinant tissue plasminogen activator (rtPA, alteplase), lyses clots by binding plasmin-bound fibrin in a clot and cleaving plasminogen to plasmin; moreover, it is widely used to clear occluded CVADs.

METHODS

Prophylactic rtPA lock therapy in children with SBS was evaluated as a single site pilot study to minimize line-associated VTE, infection, need for line replacement, and hospitalization at the Children's Hospital of Pittsburgh of University of Pittsburgh Medical Center. rtPA lock therapy was administered by parents/caregivers on a weekly basis over a 6-month time period in place of heparin lock therapy. Comparisons were made between line-associated complications in the cohort in the 6 months before study versus during the study period.

RESULTS

Six out of 8 subjects completed the study over a 1-year time period. As a group, subjects experienced a significant decrease in the number of line-associated bloodstream infections from a mean of 1.9 infections in the 6 months before the study to a mean of 0.5 infections (P = 0.025). There was no change in the need for line replacement amongst subjects while on study. The primary outcome of VTE was not found in the cohort, and it is unclear whether rtPA lock therapy contributed to the lack of thrombosis development. Given the success of rtPA in this pilot study in reducing bloodstream infections, further investigation or rtPA lock therapy in patients with SBS is warranted.

Paneth and intestinal stem cells preserve their functional integrity during worsening of acute cellular rejection in small bowel transplantation

Graft survival after small bowel transplantation remains impaired due to acute cellular rejection (ACR), the leading cause of graft loss. Although it was shown that the number of enteroendocrine progenitor cells in intestinal crypts was reduced during mild ACR, no results of Paneth and intestinal stem cells localized at the crypt bottom have been shown so far. Therefore, we wanted to elucidate integrity and functionality of the Paneth and stem cells during different degrees of ACR, and to assess whether these cells are the primary targets of the rejection process. We compared biopsies from ITx patients with no, mild, or moderate ACR by immunohistochemistry and quantitative PCR. Our results show that numbers of Paneth and stem cells remain constant in all study groups, whereas the transit-amplifying zone is the most impaired zone during ACR. We detected an unchanged level of antimicrobial peptides in Paneth cells and similar numbers of Ki-67⁺ IL-22R⁺ stem cells revealing cell functionality in moderate ACR samples. We conclude that Paneth and stem cells are not primary target cells during ACR. IL-22R⁺ Ki-67⁺ stem cells might be an interesting target cell population for protection and regeneration of the epithelial monolayer during/after a severe ACR in ITx patients.