Two Years’ Experience of Acute Rejection Monitoring of Intestinal Transplant Recipients by Real-Time PCR Assessment of Granzyme B and Perforin Up-Regulation: Considerations on Diagnostic Accuracy

Graft assessment for acute rejection after intestinal transplantation: current status and future perspective

Intestinal transplantation has since its inception evolved as a lifesaving treatment option for patients with irreversible intestinal failure who can no longer be sustained on parenteral nutrition. Improvement in short-term survival after transplantation has also justified the expansion of treatment indications. Unfortunately, success is somewhat limited by a plateau observed in long-term survival. The reason for this sub-optimal long-term result experienced in this cohort may in part be attributed to the intestinal graft with the lymphoid content it carries inflicting the host with multiple complications where acute cellular rejection is one of the most common causes for graft loss. Graft monitoring is for this reason of paramount importance and detection of rejection at an early stage essential to enable early instigation of treatment and successful reversal of the pathology. Due to the challenges in diagnosing acute rejection with a noninvasive marker we are still limited to a surveillance protocol using endoscopy and biopsies for the diagnosis of rejection. The purpose of our paper is to review the adequacy of different methods in monitoring the graft for acute rejection using biomarkers, endoscopy and imaging. In conclusion, the evidence base continues to support the use of histology for the diagnosis of acute rejection. The role of biomarkers are still debatable, although markers such as calprotectin might be beneficial in excluding an ongoing process.

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.

[Plasma citrulline concentration as a biomarker of intestinal function in short bowel syndrome and in intestinal transplant]

INTRODUCTION

Citrulline is a non-essential amino acid produced solely in the enterocyte. The aim of this study was to analyse the role of serum citrulline as a biomarker of enterocyte load in children with intestinal failure due to short bowel syndrome (SBS) and its relationship to enteral adaptation.

MATERIAL AND METHODS

Plasma citrulline concentration was determined by chromatography (normal value>15 μmol/L) in 57 patients (age 0.5-18 years) admitted to our Intestinal Rehabilitation Unit with intestinal failure. Those who were dehydrated, with renal insufficiency, or other conditions able to modify the results were excluded. Patients were divided into 4 groups: group i: SBS totally dependent on parenteral nutrition (PN); group ii: SBS under mixed enteral-parenteral nutrition; group iii: IF weaned from PN after a rehabilitation period; group iv: small bowel transplanted patients weaned from PN and taking a normal diet.

RESULTS

The mean ± SD plasma citrulline values were: group i (n=15): 7.1 ± 4.1; group ii (n=11): 15.8 ± 8.9; group iii (n=13): 20.6 ± 7.5; group iv (n=25): 28.8 ± 10.1. Values were significantly lower in group i in comparison with groups ii-iii-iv (P<.001), and in group ii in comparison with groups iii-iv (P<.001). A low citrulline was associated with remnant small bowel length (P<.001, r=0.85). In group iv citrulline levels decreased >50% in 3 patients who developed moderate-severe rejection, and in one patient who developed viral enteritis.

CONCLUSIONS

1. Plasma citrulline could be a sensitive and specific biomarker of the residual functional enterocyte load. 2. It is related to enteral feeding tolerance. 3. Its prognostic value in the process of intestinal adaptation and as a rejection marker in small bowel transplanted patients needs to be confirmed.

Endoscopic evaluation of small intestine transplant grafts

BACKGROUND

The management of small bowel transplantation is unique because signs of rejection can be obtained visually by endoscopy. The aim of this study was to evaluate the accuracy of endoscopic appearance in assessing histologic evidence of acute cellular rejection (ACR).

METHODS

Endoscopies were performed in 66 asymptomatic "surveillance" small bowel transplant recipients and 71 symptomatic recipients from a single center. For surveillance patients, 125 ileoscopies were performed to collect 590 biopsies, and for the symptomatic group, 229 ileoscopies and jejunoscopies were conducted to obtain 434 biopsies.

RESULTS

The sensitivity and specificity of endoscopic visualization in detecting ACR was 50% and 91.5% for the surveillance group and 43% and 67% for the symptomatic patients. In surveillance, visual impression alone would have missed three cases of moderate and no cases of severe ACR, whereas in the symptomatic group, visual inspection alone would have missed 20 cases of moderate ACR, and findings from visual inspection of the chimney were normal in 55% of cases with proximal ACR. However, chimney biopsy was generally representative of biopsy findings in the proximal graft but would have missed moderate to severe rejection in three patients (1%). In a subset of 23 endoscopies, zoom endoscopy did not improve visual discrimination. The only complication was a biopsy-related non-life-threatening bleed.

CONCLUSIONS

In symptomatic patients, visual inspection detected all cases of severe rejection but would have missed patients with early readily treatable rejection and thus making biopsy mandatory in clinical practice. Our results support the current practice of ileoscopic biopsy alone for graft surveillance in asymptomatic patients.

Present prospects and future perspectives of intestinal and multivisceral transplantation

PURPOSE OF REVIEW

This article reviews the most current indications, technical aspects and results of intestinal and multivisceral transplantation.

RECENT FINDINGS

The introduction of induction therapy in the past 8 years, combined with advancements on surgical technique and clinical management, was vital for the improvement in patient and graft survival.

SUMMARY

Intestinal transplantation is now a viable option for patients with intestinal failure who have failed parenteral nutrition. The improvement in the survival of intestinal and multivisceral transplant recipients has extended its use to selected patients with neoplastic disease, extensive splanchnic thrombosis and abdominal catastrophes.

Induced liver allograft immunological tolerance in rats by intramuscular injection of recombinant adeno-associated virus-human cytotoxic T-lymphocyte-associated antigen-4 immunoglobulin (rAAV-hCTLA4Ig)

Induction of liver allograft immunological tolerance was performed in rats by intramuscular injection of recombinant adeno-associated virus-human cytotoxic T-lymphocyte-associated antigen-4 immunoglobulin (rAAV-hCTLA4Ig). Dark Agouti and Lewis rats were liver allograft donors and recipients, respectively, in four groups: (A) syngeneic control, (B) blank control, (C) rAAV-enhanced green fluorescent protein negative control, (D) rAAV-hCTLA4Ig. Gene transfers occurred 6 weeks before transplantation. Group D had a significantly longer liver graft survival time (> 100 days) than groups B (11.9 +/- 1.3 days) and C (11.6 +/- 1.1 days). Groups B and C showed severe rejection responses and large amounts of CD4(+) and CD8(+) T-lymphocyte infiltration, while only a mild response and few T-lymphocytes were observed in group D. There were no significant differences in interleukin-2 and interferon-gamma levels in liver grafts between groups D and C, but there were significant decreases in granzyme B and lymphotoxin beta levels in group D compared with group C. It is concluded that immunological tolerance to liver allograft could be achieved by gene transfer of rAAV-hCTLA4Ig through intramuscular injection.

Treatment of intestinal failure: intestinal transplantation

Over the past 15 years, intestinal transplantation for the treatment of intestinal failure has changed from a desperate last-ditch effort into a standard therapy for which a good outcome is expected. Patient survival after intestinal transplantation has improved in the past 3-5 years and now approaches that of other solid organ allograft recipients, including liver and kidney, and is similar to survival on permanent therapy with parenteral nutrition. Complications are more common and often more severe during the initial hospitalization period after intestinal transplantation than they are after transplantation of other solid organs. After intestinal transplantation the initial hospitalization period is, therefore, usually 3-8 weeks long. Nearly all patients discharged after intestinal transplantation have good allograft function and have been weaned from total parenteral nutrition. The cost of the initial hospitalization period is one to two times the cost of permanent total parenteral nutrition for 1 year, which means that, in most cases, intestinal transplantation is cost-saving within 2 years of transplantation. In addition, quality of life after intestinal transplantation, as determined by standardized quality of life measures, is good or normal.