Effectiveness of Bortezomib in a Patient With Acute Rejection Associated With an Elevation of Donor-Specific HLA Antibodies After Small-Bowel Transplantation: Case Report

Intestinal transplantation: Significance of immune responses

Intestinal allografts, with many resident immune cells and as a destination for circulating lymphocytes of the recipient, appear to be the most challenging solid organ transplants. The high incidence of acute rejection and frequent reports of fatal graft-versus-host disease (GvHD) after intestinal transplantation call for more research to describe the molecular mechanisms involved in the immunopathogenesis of post-transplant complications to define new therapeutic targets. In addition, according to the rapid development of immunosuppressive agents, it is time to consider novel therapeutic approaches in managing treatment-refractory patients with rejection or severe GvHD. Herein, the main immunological challenges before and after intestinal transplant including, brain-dead donor inflammation, acute rejection, antibody-mediated, and chronic rejections, as well as GvHD have been described. Besides, the new immune-based therapies used in experimental and clinical settings to improve tolerance toward intestinal allograft, and cases of operational tolerance have been reviewed.

Living Donor Intestinal Transplantation

This study explores intestinal transplantation (ITx) as a viable treatment option for intestinal failure (IF). Historical development, donor and recipient considerations, surgical techniques, immunosuppression, and outcomes, are reviewed with particular emphasis to the value of living donor ITx. The review highlights the evolution of ITx and emphasizes the ongoing need for patient-specific selection processes. In the realm of pediatric ITx, the article underlines the significance of early intervention to mitigate IF-related liver disease. Overall, it provides a comprehensive overview of this life-saving procedure.

B-Cell Induction Therapies in Intestinal Transplantation

Despite advancements in short-term outcomes since the inception of intestinal transplant, significant long-term graft failure persists. Early successes are attributed to the utilization of tacrolimus for maintenance therapy, coupled with T-cell modulating induction regimens, which effectively reduce the incidence of acute cellular rejection. However, the challenge of chronic allograft injury remains unresolved. There is increasing evidence indicating a correlation between donor-specific antibodies and the survival of visceral allografts. Strategies aimed at reducing the presence or load of these antibodies may potentially enhance long-term outcomes. Consequently, our focus is now turning toward B-cell induction therapies as a possible solution.

Small bowel transplant - novel indications and recent progress

INTRODUCTION

Advances in the management of intestinal failure have led to a reduction in the number of intestinal transplants. The number of bowel transplants has been mainly stable even though a slight increase has been observed in the last 5 years.

AREAS COVERED

Standard indication includes patients with a reasonable life expectancy. Recent progress can be deduced by the increased number of intestine transplants in adults: this is due to the continuous improvement of 1-year graft survival worldwide (without differences in 3- and 5-year) associated with better abdominal wall closure techniques. This review aims to provide an update on new indications and changes in trends of pediatric and adult intestine transplantation. This analysis, which stretches through the past 5 years, is based on a collection of related manuscripts from PubMed.

EXPERT COMMENTARY

Intestinal transplants should be solely intended for a group of individuals for whom indications for transplantation are clear and both medical and surgical rehabilitations have failed. Nevertheless, many protocols developed over the years have not yet solved the key question represented by the over-immunosuppression. Novel indications and recent progress in the bowel transplant field, minimal yet consistent, represent a pathway to be followed.

Immunosuppression Protocols in Intestinal and Multivisceral Transplantation-A Literature Review

BACKGROUND

Intestinal transplantation (IT) and multivisceral transplantation (MVT) are curative therapies for patients with intestinal failure and severe complications associated with total parenteral nutrition. High levels of immunosuppression are required to prevent acute cellular rejection (ACR) from the bowel. Studies regarding pre-treatment, induction, and post-transplant therapy have improved graft acceptance, reducing immunosuppression doses and infectious complications. However, the low rate of IT and MVT and the small number of specialized centers have resulted in a limited number of evidence-based immunosuppression protocols. We reviewed immunosuppression in IT and MVT to draw useful conclusions regarding the best protocol strategies for the induction, maintenance, and management of ACR.

METHODS

A review was performed using the PubMed database. Articles on immunosuppression protocols in IT and MVT that addressed graft rejection, infection, or survival, published between 2006 and 2022, were selected.

RESULTS

A total of 690 articles were selected. Two researchers applied the inclusion and exclusion criteria and selected 14 articles independently. For induction, thymoglobulin, alemtuzumab, and basiliximab are the most frequently used immunosuppressants for induction. Classic maintenance therapy consists of a combination of corticosteroids and tacrolimus. Methylprednisolone with an increased tacrolimus dose is used most frequently to manage ACR. Depending on the receptor response, such as thymoglobulin, infliximab, adalimumab, or bortezomib, other immunosuppressants should be considered.

CONCLUSIONS

There have been great advances in IT and TMV immunosuppression. We conclude that the gold standard immunosuppressive protocol is triple therapy, comprising induction with thymoglobulin, maintenance with steroids for a few months, and tacrolimus and mycophenolate therapy. Innovative approaches for treating intestinal rejection episodes with more appropriate drugs, such as infliximab, adalimumab, or bortezomib, are necessary.

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.

Update on immunosuppressive strategies in intestinal transplantation

PURPOSE OF REVIEW

The intestine is the most immunologically complex solid organ allograft with the greatest risk of both rejection and graft-versus-host disease (GVHD). High levels of immunosuppression are required, further increasing morbidity. Due to low volume of transplants and few centers with experience, there is paucity of evidence-based, standardized, and effective therapeutic regimens. We herein review the most recent data about immunosuppression, focusing on novel and emerging therapies.

RECENT FINDINGS

Recent data are moving the field toward increasing use of basilixumab and consideration of alemtuzumab for induction and inclusion of mammalian target of rapamycin inhibitors and antimetabolites for maintenance. For rejection, we highlight novel roles for tumor necrosis factor-α inhibition, α4β7 integrin inhibition, microbiome modulation, desensitization protocols, and tolerance induction strategies. We also highlight emerging novel therapies for GVHD, especially the promising role of Janus kinase inhibition.

SUMMARY

New insights into immune pathways associated with rejection and GVHD in intestinal allografts have led to an evolution of therapies from broad-based immunosuppression to more targeted strategies that hold promise for reducing morbidity from infection, rejection, and GVHD. These should be the focus of further study to facilitate their widespread use.

Chronic Rejection After Intestinal Transplant: Where Are We in Order to Avert It?

Chronic rejection affects the long-term survival of all solid organ transplants and, among intestinal allografts, occurs in up to 10% of the recipients. The insidious clinical evolution of the chronic allograft enteropathy, the absence of noninvasive biomarkers, and the late endoscopic findings delay its diagnosis. No pharmacological approach has been proven effective, and allograft removal nowadays still represents the only available therapy. The inclusion of the liver in the visceral allograft appears to be the only intervention affecting the development of chronic rejection, as revealed by large-center studies and registry reports. A significant body of evidence emerged from the experimental setting and provided essential knowledge on the complex mechanisms behind the development of chronic allograft enteropathy. More recently, donor-specific antibodies have been suggested as an early, key element in the natural history of chronic allograft enteropathy and several novel approaches, tackling the antibody-mediated graft injury, have gained acceptance in clinical settings and are believed to impact on chronic rejection. The inclusion of a liver allograft is advocated when re-transplanting a sensitized recipient, due to its protective effect against humoral immunity. Multicenter trials are required to understand and tackle chronic rejection, and find the therapeutic answer to this clinical dilemma.

Intestinal transplantation: a review

PURPOSE OF REVIEW

The purpose of this article is to review the existing literature on the current indications, surgical techniques, immunosuppressive therapy and outcomes following intestinal transplantation (ITx).

RECENT FINDINGS

Over recent years, ITx has become a more common operation with approximately 2500 procedures carried out worldwide by 2014. It is reserved for patients with intestinal failure and who have developed complications of home parenteral nutrition or who have a high risk of dying from their underlying disease. Recent advances such as the improvement in survival rates, not only for isolated small bowel transplants but also following inclusion of a liver graft in combined liver-small bowel transplant, and the utility of citrulline as a noninvasive biomarker to appreciate acute rejection herald an exciting shift in the field of ITx.

SUMMARY

With advancements in immunosuppressive drugs, induction regimens, standardization of surgical techniques and improved postoperative care, survival is increasing. In due course, it will most likely become as good as remaining on home parenteral nutrition and as such could become a viable first-line option.