Infectious complications after multivisceral transplantation in adults

Intestinal Transplant Immunology and Intestinal Graft Rejection: From Basic Mechanisms to Potential Biomarkers

Intestinal transplantation (ITx) remains a lifesaving option for patients suffering from irreversible intestinal failure and complications from total parenteral nutrition. Since its inception, it became obvious that intestinal grafts are highly immunogenic, due to their high lymphoid load, the abundance in epithelial cells and constant exposure to external antigens and microbiota. This combination of factors and several redundant effector pathways makes ITx immunobiology unique. To this complex immunologic situation, which leads to the highest rate of rejection among solid organs (>40%), there is added the lack of reliable non-invasive biomarkers, which would allow for frequent, convenient and reliable rejection surveillance. Numerous assays, of which several were previously used in inflammatory bowel disease, have been tested after ITx, but none have shown sufficient sensibility and/or specificity to be used alone for diagnosing acute rejection. Herein, we review and integrate the mechanistic aspects of graft rejection with the current knowledge of ITx immunobiology and summarize the quest for a noninvasive biomarker of rejection.

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.

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.

Liver-inclusive intestinal transplantation results in decreased alloimmune-mediated rejection but increased infection

Background and aims

A co-transplanted liver allograft has been thought to protect other organs from rejection-mediated injury; however, detailed analyses of co-transplanted liver on intestinal allograft outcomes have not been conducted to date. The aim of the study was to compare immune-mediated injury, causes of graft failure and clinical outcomes between recipients who underwent either a liver-inclusive intestinal transplant (LITx) or liver-exclusive intestinal transplant (LETx).

Methods

Between May 2000 and May 2010, 212 adult patients undergoing LITx (n =76) and LETx (n =136) were included. LITx underwent either liver combined intestinal or full multivisceral transplantation. LETx underwent either isolated intestinal or modified multivisceral transplantation.

Results

During 44.9 ± 31.4 months of follow-up, death-censored intestinal graft survival was significantly higher for LITx than LETx (96.9%, 93.2% and 89.9% vs 91.4%, 69.3% and 60.0% at 1, 3 and 5 years; p =0.0001). Incidence of graft loss due to rejection was higher in LETx than in LITx (30.9% vs 6.6%; p <0.0001), while infection was the leading cause of graft loss due to patient death in LITx (25.0% vs 5.1%; p <0.0001). Despite similar immunosuppression, the average number (0.87 vs 1.42, p =0.02) and severity of acute cellular rejection episode (severe grade: 7.9% vs 21.3%; p =0.01) were lower in LITx than in LETx. Incidence of acute antibody-mediated rejection was also significantly lower in LITx than in LETx (3.6% vs 15.2%; p =0.03). Incidence of chronic rejection was reduced in LITx (3.9% vs 24.3%; p =0.0002).

Conclusions

Intestinal allografts with a liver component appear to decrease risk of rejection but increase risk of infection. Our findings emphasize that LITx has characteristic immunologic and clinical features. Lower immunosuppression may need to be considered for patients who undergo LITx to attenuate increased risk of infection.

A radiologist's guide to small bowel and multivisceral transplantation

This review will describe the indications for the various small bowel containing transplants. The importance of early referral will be highlighted. Radiologists play a central role in assessing these complex patients prior to transplantation. Furthermore, in the postoperative period, radiologists play an important part in diagnosing and treating complications.

Mycotic aneurysms of the abdominal aorta due to Listeria monocytogenes

INTRODUCTION

Infected abdominal aortic aneurysms (AAAs) can present insidiously with non-specific symptoms or they may present as ruptured AAA in the classical manner.

PRESENTATION OF CASE

We report two cases of mycotic AAA with Listeria monocytogenes. One patient presented with a ruptured aneurysm, while the other patient had a symptomatic non-ruptured presentation with computer tomography (CT) angiogram demonstrating peri-aortic inflammatory change of a rapidly expanding aneurysm. Both patients were treated with excision of the infected tissue and inlay prosthetic surgical repair as well as long term antibiotics.

DISCUSSION

Arterial aneurysms caused by L. monocytogenes are rare. Risk factors include immunosuppression, infective endocarditis, intravenous drug use and septicaemia. Listeria infections should be discussed with the Health Protection Agency and local microbiologists due to their ubiquity.

CONCLUSION

Abdominal aortic aneurysm due to L. monocytogenes is best managed via surgical resection in combination with long term antimicrobial therapy. The role of endovascular exclusion is unclear.

Intestinal and multivisceral transplantation immunosuppression protocols--literature review

INTRODUCTION

Currently the most used techniques for small bowel transplant are isolated intestinal transplantation, multivisceral transplantation (MVT), and modified multivisceral transplantation. One important factor is early diagnosis of acute cellular rejection (ACR). In addition, improvements in immunosuppression have recently reduced the number and enhanced treatment of ACR episodes, enabling graft recovery.

OBJECTIVE

We analyzed immunosuppression protocols of leading transplantation centers in the last 5 years.

METHOD

We reviewed papers published in PubMed from major multivisceral and intestinal transplantation centers from 2006 to 2010 in adult recipients. The 211 adults transplanted in seven centers were divided into three groups according to the immunosuppression protocol used: protocol 1: daclizumab induction with tacrolimus and steroid maintenance; protocol 2: alemtuzumab and tacrolimus; and protocol 3: thymoglobulin and rituximab and tacrolimus.

RESULTS

Protocol 2 showed the lowest rate of ACR (34%). Protocols 1 and 3 displayed 54% and 48% ACR rates; respectively. However, protocol 1 patients developed only mild ACR, whereas those in protocols 2 and 3 developed moderate ACR in 26.3% and 11.7%, and severe ACR in 7.9% and 47% of cases, respectively. The infection rate was considerably lower in protocol 3 (7.4%). Protocols 1 and 2 showed infection rates of 62.5% and 52%, respectively. One-year patient survival rates were 70%, 79% and 81%, respectively. Three-year patient survival rates were 62%, 56%, and 78% for protocols 1, 2 and 3, respectively.

CONCLUSION

Protocol 2 was the strongest immunosuppressive regimen capable of reducing ACR rates when compared with the other protocols, but the strong effect resulted in high infection rate that impacts 1-year patient survival. Protocol 3 seems to be the best available one balancing ACR and infection rates.

Six-month incidence of bloodstream infections in intestinal transplant patients

BACKGROUND

Intestinal transplantation has emerged as an established treatment for life-threatening intestinal failure. The most common complication and cause of death is infection. Risk of infection is highest during the first 6 months, as a consequence of maximal immunosuppression, greater than that required for any other organ allograft.

METHODS

We performed a retrospective chart review of all (56) adult and pediatric (<18 years) small bowel transplant patients at our institution between November 2003 and July 2007, and analyzed the 6-month post-transplant incidence of bloodstream infections (BSIs). We evaluated multiple risk factors, including inclusion of a colon or liver, total bilirubin >5, surgical complications, and acute rejection.

RESULTS

A BSI developed in 34 of the 56 patients, with a total of 85 BSI episodes. Of these BSI episodes, 65.9% were due to gram-positive organisms, 34.1% gram-negative organisms, and 2.4% due to fungi. The most common isolates were Enterococcus species, Enterobacter species, Klebsiella species, and coagulase-negative staphylococci. Inclusion of the liver and/or a preoperative bilirubin >5 mg/dL appeared to increase the incidence of BSI (P = 0.0483 and 0.0005, respectively). Acute rejection and colonic inclusion did not appear to affect the incidence of BSI (P = 0.9419 and 0.8248, respectively). The BSI incidence was higher in children (P = 0.0058).

CONCLUSIONS

BSIs are a common complication of intestinal transplantation. Risk factors include age <18, inclusion of the liver, and pre-transplant bilirubin >5. Acute rejection and colon inclusion do not appear to be associated with increased BSI risk.

Combined en bloc liver/pancreas transplantation in two different patients

Combined en bloc liver/pancreas transplantation (CLPT) was used primarily in the treatment of otherwise non-resectable upper abdominal malignancy. In fact, a more appropriate indication is in patients with liver disease and insulin-dependent diabetes mellitus (IDDM). Here, we report on two successful cases of CLPT at our hospital. One was a patient with non-resectable advanced liver cancer. The recipient survived for 23 mo and finally died of recurrent tumor. The other was a patient with severe biliary complication after orthotopic liver transplantation and preoperative IDDM. We performed CLPT with a modified surgical technique of preserving the native pancreas. He is currently liver-disease- and insulin-free more than 27 mo post-transplant. Based on our experience in two cases of abdominal cluster transplantation, we describe the technical details of CLPT and a modification of the surgical procedure.

Utilization of donors who have suffered cardiopulmonary arrest and resuscitation in intestinal transplantation

BACKGROUND

Cardiopulmonary resuscitation (CPR) of a person destined to become an organ donor has been associated with overall poor donor quality, especially for the intestinal donor, as splanchnic vasoconstriction that is intended to preserve coronary and cerebral blood flow may result in clinically relevant intestinal ischemia. Outcomes of recipients who receive intestine grafts that have suffered CPR are unknown. We sought to analyze our clinical experience in using intestinal grafts from donors who suffered cardiopulmonary arrest and resuscitation and to evaluate the outcome of recipients of organs coming from resuscitated donors when compared with recipients of nonresuscitated donors.

METHODS

We retrospectively analyzed the donor and recipient charts of all of our intestinal transplants with regard to the performance of donor CPR.

RESULTS

Sixty-seven intestinal transplants were performed in 65 patients from November 2003 to December 2007. Twelve donors (18%) were identified as having suffered cardiac arrest and subsequent CPR. Mean duration of CPR was 19.3+/-12.7 min. Terminal laboratory profiles of CPR donors and non-CPR donors were similar. Of the 12 resuscitated grafts, two were used for multivisceral, one for a modified multivisceral, seven for liver-intestine, and two for isolated intestinal transplant. There were no significant differences in outcome parameters such as operative time, blood use, ventilation days, length of stay, time to enteral independence, rejection, enteric bacteremia, and survival between the 12 resuscitated grafts and the 55 nonresuscitated grafts.

CONCLUSION

A donor history of cardiac arrest should not automatically exclude the use of the intestine graft for transplantation.