Clinicopathologic features of post-transplant lymphoproliferative disorders arising after pediatric small bowel transplant.

Few studies examined the clinicopathologic features of PTLD arising in pediatric SBT patients. Particularly, the association between ATG and PTLD in this population has not been described. Retrospective review of 81 pediatric patient charts with SBT--isolated or in combination with other organs--showed a PTLD incidence of 11%, occurring more frequently in females (median age of four yr) and with clinically advanced disease. Monomorphic PTLD was the most common histological subtype. There was a significant difference in the use of ATG between patients who developed PTLD and those who did not (p < 0.01); a similar difference was seen with the use of sirolimus (p < 0.001). These results suggested a link between the combination of ATG and sirolimus and development of more clinically and histologically advanced PTLD; however, the risk of ATG by itself was not clear. EBV viral loads were higher in patients with PTLD, and median time between detection of EBV to PTLD diagnosis was three months. However, viral loads at the time of PTLD diagnosis were most often lower than at EBV detection, thereby raising questions on the correlation between decreasing viral genomes and risk of PTLD.

MicroRNA signature of intestinal acute cellular rejection in formalin-fixed paraffin-embedded mucosal biopsies.

Despite continuous improvement of immunosuppression, small bowel transplantation (SBT) is plagued by a high incidence of acute cellular rejection (ACR) that is frequently intractable. Therefore, there is a need to uncover novel insights that will lead to strategies to achieve better control of ACR. We hypothesized that particular miRNAs provide critical regulation of the intragraft immune response. The aim of our study was to identify miRNAs involved in intestinal ACR. We examined 26 small intestinal mucosal biopsies (AR/NR group; 15/11) obtained from recipients after SBT or multivisceral transplantation. We investigated the expression of 384 mature human miRNAs and 280 mRNAs associated with immune, inflammation and apoptosis processes. We identified differentially expressed 28 miRNAs and 58 mRNAs that characterized intestinal ACR. We found a strong positive correlation between the intragraft expression levels of three miRNAs (miR-142-3p, miR-886-3p and miR-132) and 17 mRNAs including CTLA4 and GZMB. We visualized these miRNAs within cells expressing CD3 and CD14 proteins in explanted intestinal allografts with severe ACR. Our data suggested that miRNAs have a critical role in the activation of infiltrating cells during intestinal ACR. These differences in miRNA expression patterns can be used to identify novel biomarkers and therapeutic targets for immunosuppressive agents.

Association between panel reactive antibodies and acute small bowel rejection: analysis of a series of 324 intestinal transplants.

INTRODUCTION: Panel reactive antibodies (PRA) to class I and II HLA molecules have been associated with acute kidney graft rejection, but their role in small bowel transplantation has not been characterized. METHODS: Since 1994, 324 SBT, alone or as multivisceral transplantation (MVT), have been performed in 286 patients. Routine and surveillance biopsies were performed to rule out or confirm acute rejection (AR), and PRA quantification was performed at varying intervals. We obtained data from 110 patients and 651 PRA measurements. While AR grade (mild to severe, grades 1-3) was determined by histopathological analysis, the status of no AR was determined also by clinical data. When biopsy samples or PRA measurements were frequent around an AR episode within periods of 7 days, the highest value was used. RESULTS: A comparison could be made between 259 instances in which there was a PRA measurement and simultaneous rejection evaluation. Positive PRA showed association with AR (P < 0.001). The positive and negative predictive values were 44% and 79%, respectively. No correlation was found in the severity of rejection. CONCLUSION: The presence of increased levels of PRA is a risk factor of rejection in small bowel transplantation. Alloantibody-mediated injury to the graft contributes frequently to acute rejection of small bowel, and it is associated with cell-mediated immunity in variable proportion.

Citrulline evaluation in bowel transplantation.

INTRODUCTION: The purpose of this study was to evaluate the correlation of plasma citrulline and rejection episodes in intestinal transplantation. METHODS: From January 2007 until present, we performed citrulline assays on our small bowel patients. We investigated the correlation of these assays with the rejection status of the patients. The rejection status of the graft was defined based on graft biopsies. RESULTS: Of 5195 citrulline samples, average serum citrulline levels decreased significantly when the patients presented a rejection episode. We found the following: no rejection, 17.38 microm/L; mild rejection, 13.05 microm/L; moderate rejection, 7.98 microm/L; and severe rejection, 6.05 microm/L. Our current emphasis is to determine the predictive power of citrulline with other biomarkers versus as a separate and isolated measurement. CONCLUSIONS: In our study, citrulline levels correlated significantly with the rejection status of the graft. Serial follow-up of the patients using this assay may alert us to the possibility of increased alloreactivity and rejection episodes.

Gene expression profiling of MicroRNAs in small-bowel transplantation paraffin-embedded mucosal biopsy tissue.

BACKGROUND: The molecular mechanisms and regulation of immune-mediated rejection of organ allografts remains unclear. Recent studies have reported that small non-coding RNAs, microRNAs (miRNAs) play a critical role in the immune system via modulation of transcription and translation. PURPOSE: We hypothesized that particular miRNAs provide regulation of an ensuing intragraft immune effector response. The aim of our study was to detect miRNAs involved in acute cellular rejection (AR) in human small intestinal allografts. MATERIALS: We examined 12 small intestinal mucosal biopsies (AR, 7 cases, all grade 2 or 3) and non-rejecting (NR) allografts (5 cases, all grade 0) obtained from recipients after small bowel or multivisceral transplantation. RNA was isolated from the formalin-fixed paraffin-embedded (FFPE) biopsy samples and transcribed to cDNA. After preamplification we utilized a PCR based TaqMan Low Density Array (TLDA) containing 365 mature human miRNAs. Relative quantification was done based on pooled normal intestine using a comparative Ct method. RESULTS: We identified 62 miRNA upregulated genes in small bowels with ACR, and 35 were downregulated. Forty-two miRNA genes were upregulated in non-ACR small bowel biopsy samples (grade IND), and 45 were downregulated. The relative fold change ratio of ACR to non-ACR was calculated, and 50 upregulated and 8 downregulated miRNAs were detected as significant. Several interesting miRNAs will be evaluated further from this preliminary study. Our data suggests that intragraft miRNAs are potentially involved in the activation of a host alloimmune response to donor. These miRNAs may serve as targets for appropriate intervention and may be useful to monitor the allograft status.

International grading scheme for acute cellular rejection in small-bowel transplantation: single-center experience.

A standardized grading scheme for the assessment of acute cellular rejection (ACR) in small-intestine transplantation was proposed in 2003 at the Eighth International Small Intestinal Transplantation Symposium. We have implemented the current grading scheme for ACR in small-bowel transplantation since October 2003. The pathologic diagnoses of those small-intestine biopsy samples, including ACR grade and other supplementary findings were evaluated. A total of 3484 small intestine biopsy samples from 155 patients were available for evaluation in this study. Frequency of grades 0, indeterminate, 1, 2, and 3 acute cellular rejection was 33.9%, 49.1%, 12.6%, 3.7%, and 0.8%, respectively. Duration of ACR episode strongly correlated with grade of ACR episode (P < .001). Other supplementary findings included acute vascular rejection component, 2.2%; increase in lymphoplasmacytic infiltrate in lamina propria, 15.7%; mucosal fibrosis, 0.4%; and regenerative changes, 0.3%. Our data substantiate that this grading system is reliable and useful for clinical decision making in bowel transplantation. We suggest that an assessment and quantification of supplementary findings be considered a component of the International Pathology Grading Scheme.

Mycophenolate mofetil-related gastrointestinal mucosal injury in multivisceral transplantation.

Mycophenolate mofetil (MMF) has become an important and commonly used drug for maintenance immunosuppression therapy in recipients of all types of organ transplants. The drug is an antimetabolite that blocks the de novo pathway of purine synthesis. Although it selectively inhibits B- and T-lymphocyte proliferation, enterocytes are partially susceptible to MMF. One of the main limitations of this drug is gastrointestinal toxicity, with diarrhea the most frequently reported adverse effect. Most studies of MMF-associated gastrointestinal toxicity have been performed in patients with solid-organ transplants, although no data on changes related to MMF toxicity in bowel allografts have been published in the English literature. We evaluated mucosal intestinal biopsy tissue from patients with multivisceral transplants receiving MMF therapy. Our objective was to find morphologic changes that might be attributed to MMF toxicity, as well as changes that could differentiate MMF toxicity from acute rejection. Examination of the surface epithelium, lamina propria, and crypts in this small group of patients showed no specific changes that could be associated with MMF toxicity. Changes such as graft-vs-host disease or inflammatory bowel disease described in previous studies of solid-organ transplantation were not observed. Larger studies and the use of special stains and new markers might be necessary to characterize possible patterns of MMF toxicity and their differences from acute rejection.

Immediate antibody-mediated (hyperacute) rejection in small-bowel transplantation and relationship to cross-match status and donor-specific C4d-binding antibodies: case report.

BACKGROUND: The role of preformed donor-specific antibodies (DSAs) as a barrier to isolated intestinal transplantation (ITx) remains ambiguous; thus, a positive cross-match has not been a contraindication to ITx. OBJECTIVE: To report the case of a patient with Crohn's disease who underwent ITx and developed immediate antibody-mediated rejection on reperfusion of the allograft. METHODS: Percent reactive antibody testing was performed using pretransplantation serum samples and at transplantation using bead-based assays (Luminex, Luminex Corp, Austin, Tex) and flow cytometry solid-phase assays (FlowPRA single-antigen beads (One Lambda, Inc, Canoga Park, Calif). Serologic tests, flow cytometry cross-matching, and flow cytometry assays of C4d-binding serum antibodies were also performed. Histologic and immunofluorescent analysis of biopsy specimens was performed. RESULTS: HLA typing revealed no sharing of class I or II antigens between donor and recipient. Pretransplantation donor-specific antibodies (DSA) were present at transplantation. Cross-matching (performed during surgery) was positive for class I and II by serologic testing and flow cytometry. After reperfusion, the graft immediately developed severe ischemic injury and arteritis on mucosal biopsy specimens, with immunoglobulin deposition. The DSA C4d binding antibodies were also present. After intense immunosuppression and plasmapheresis, the graft and the biopsy histologic findings showed marked improvement (day 2). By day 7 posttransplantation, patient and graft status were stable. The patient has remained clinically stable for more than a year after transplantation. CONCLUSIONS: Pretransplant DSA in ITx can be a risk factor for immediate (hyperacute) but potentially reversible antibody-mediated rejection. Thus, pretransplantation DSA and cross-match results are critical components to be considered in patients awaiting or undergoing ITx.

Multimodality tumor control and living donor transplantation for unresectable hepatocellular carcinoma.

Liver transplantation (LT) is an acceptable mode of treatment for selected patients with unresectable hepatocellular carcinoma (HCC). However, due to the scarcity of cadaveric donor organs, it is considered desirable for patients to opt for living donor liver transplantation (LDLT) or, for those not being transplanted soon, to have some form of tumor control therapy. Such an approach in our program is analyzed and reported. At our institution, 42 LTs were performed between October 1999 and April 2003. Of these, 18 recipients (15 men, 3 women) had 27 HCC. The average number and size of HCC was 1.59 (1 to 4) and 2.31 (0.2 to 6.5) cm, respectively. Thirteen (72%) patients were transplanted primarily for the HCC, whereas five (28%) others were incidental HCC cases. Seven patients (5 LRLT, 2 cadaveric LT) were transplanted soon after listing, and thus did not require tumor control therapy. Six patients waited for 11 (6 to 19) months before LT. Three patients underwent microwave coagulation therapy, and one had additional alcohol injections. One patient received the novel PIAF (cisplatin, interferon, adriamycin, and 5-FU) chemotherapy regimen followed by selective internal irradiation (SIR) treatment. One patient received conformal radiation therapy and another received SIR treatment before LT. Besides 2 postoperative deaths, the remaining 16 patients have been well, with a mean follow-up of 20.4 (3.6 to 41.2) months. In conclusion, for patients with unresectable HCC, in areas with poor cadaveric donor rate, living donation should be the first option. If a suitable live donor is not available, aggressive multimodality therapy is recommended while waiting for cadaveric LT.

The longest survivor and first potential cure of an advanced cholangiocarcinoma by ex vivo resection and autotransplantation: a case report and review of the literature.

Bismuth type IV hilar cholangiocarcinoma (CC) carries a poor prognosis; however, ex vivo liver resection and autotransplantation (Atx) is theoretically a treatment option. There are only five previously reported cases of this procedure for hilar CC in the English literature, and most of them died early in the postoperative period. The only reported survivor died of tumor recurrence at 13 months. We are reporting a patient who has survived for 17 months without any sign of tumor recurrence. This probably represents the world's first cure for CC using this technique. This patient is a 26-year-old woman with a Bismuth Type IV CC. Portal vein involvement at the confluence was shown on angiogram, and in situ resection was deemed impossible. Ex vivo resection of segments five, six, seven, eight, and part of segment four was performed followed by a partial liver Atx. The pathology specimen demonstrated CC with clear margins. MRI and CT examinations done over the subsequent 17 months showed no evidence of recurrence. In conclusion ex vivo liver resection and Atx can be a viable option for cure among highly selected patients with CC.

Short-term complications of central line placement in children with the human immunodeficiency virus.

PURPOSE: The aim of this study was to characterize the perioperative complications of central venous catheter placement in children infected with human immunodeficiency virus (HIV) METHODS: A retrospective chart review was conducted of all central venous catheters placed by the surgical service into HIV-infected children from 1988 to 1998 at a large urban children's hospital. Complications occurring within 1 month of catheter placement were analyzed for several host and environmental factors. RESULTS: Forty HIV-positive patients underwent 60 central venous access procedures. Thirty-two of the patients were severely immunosuppressed. Eight catheter placements (13%) resulted in perioperative complications, including hemorrhage (n = 2), site infection (n = 2), catheter sepsis (n = 2), thrombotic occlusion (n = 1), and a pleural effusion secondary to catheter malposition (n = 1). Only 3 patients required catheter removal. There was no significant relationship between either hemophilia or thrombocytopenia and perioperative hemorrhage. No significant relationship was found between infectious complications and preoperative white blood cell count, absolute neutrophil count, CD4% and CD4#, suggesting that a patient's compromised immune status should not be considered a contraindication to central venous catheter placement. CONCLUSION: The complication rate of central venous catheter placement into HIV-infected children is low (<15%), but is still higher than that of the general pediatric population. With careful preoperative preparation this procedure can be performed safely, even in patients with advanced HIV disease. J Pediatr Surg 36:1777-1780.