Operational tolerance after pediatric composite liver-pancreas-intestine transplantation following severe graft-versus-host disease

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.

Chimerism-Mediated Tolerance in Intestinal Transplantation

In this review, the authors outlined concepts and strategies to achieve immune tolerance through inducing hematopoietic chimerism after solid organ transplantation and introduced challenges and opportunities in harnessing two-way alloresponses to improve outcomes after intestinal transplantation (ITx). Next, the authors discussed the dynamics and phenotypes of peripheral blood and intestinal graft T-cell subset chimerism and their association with outcomes. The authors also summarized studies on other types of immune cells after ITx and their potential participation in chimerism-mediated tolerance. The authors further discussed strategies and future directions to promote chimerism-associated tolerance after ITx to overcome rejection and minimize immunosuppression.

Intestinal transplantation: an update

PURPOSE OF REVIEW

The role of intestinal transplant has expanded in recent years and is no longer only considered for patients with no other options remaining. 5 year survival in high-volume centres is over 80% for certain graft types. The aim of this review is to update the audience on the current state of intestinal transplant, with a focus on recent medical and surgical advances.

RECENT FINDINGS

There has been a greater understanding of the interplay and balance of host and graft immune responses, which may facilitate individualized immunosuppression. Some centres are now performing 'no-stoma' transplants, with preliminary data showing no adverse effects from this strategy and other surgical advances have lessened the physiological insult of the transplant operation. Earlier referrals are encouraged by transplant centres, such that vascular access or liver disease has not progressed too much to increase the technical and physiological challenge of the procedure.

SUMMARY

Clinicians should consider intestinal transplant as a viable option for patients with intestinal failure, benign unresectable abdominal tumours or acute abdominal catastrophes.

Operational tolerance after intestine re-transplantation in childhood and immunological correlates. Case report and review

BACKGROUND

Operational tolerance after retransplantation of the intestine has never been reported.

PURPOSE

To two recently described intestine transplant recipients with operational tolerance, we now add a third.

METHODS

Review of case record and immunological testing to confirm donor-specific hyporesponsiveness in multiple immune cell compartments.

RESULTS

Re-transplanted with a multivisceral liver- and kidney-inclusive intestine allograft at age 12 years, this recipient self-discontinued immunosuppression 14 years after the retransplant and has been rejection free for 2 years thereafter. As in the two previous reports, immunological testing demonstrated decreased donor-specific inflammatory response of T-cytotoxic memory cells and B-cells, decreased presentation of donor antigen by B-cells and monocytes, absence of donor-specific anti-HLA antibodies, circulating FOXP3 + T-helper cells, and intact cellular and humoral immunity to cytomegalovirus and Epstein-Barr virus. Additionally, our recipient demonstrated enhanced donor-activation-induced apoptosis of alloreactive T-cytotoxic memory cells.

CONCLUSIONS

Despite variable paths to tolerance which include graft versus host disease in two previous cases, and rejection-related loss of the primary isolated intestinal allograft in our recipient, the three cases with operational tolerance are bound by common themes: a relatively large donor antigenic load transmitted during intestine transplantation, and donor-specific hyporesponsiveness. Cell-based assays suggest enhanced donor-induced apoptosis of recipient T-cells and circulating T-regulatory cells as mechanistic links between antigenic load and donor-specific hyporesponsiveness.