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Intestinal transplantation in children has evolved with more isolated small intestine transplants being performed compared to combined liver-intestine transplants. Consequently, surgical techniques have changed, frequently requiring the use of vascular homografts of small caliber to revascularize the isolated small intestine, the impact of which on outcomes is unknown. Among 106 pediatric intestine and multivisceral transplants performed at our center since 2003, 33 recipients of an isolated small intestine graft were included in this study. Outcome parameters were thrombotic complications, graft, and patient survival. A total of 29 of 33 (87.9%) patients required arterial and/or venous homografts from the same donor, mainly iliac or carotid artery and iliac or innominate vein, respectively (donor's median age 1.1 years [2 months to 23 years], median weight 10 kg [14.7-48.5]). Post-transplant, there were three acute arterial homograft thromboses and one venous thrombosis resulting in two peri-operative graft salvages and two graft losses. Three of four thromboses occurred in patients with primary hypercoagulable state, including the two graft losses. Overall, at a median of 4.1 years (1-10.2) from transplant, 29 of 33 (88%) patients are alive with 26 of 33 (79%) functioning grafts. The procurement of intact, size-matched donor vessels and the management of effective post-transplant anticoagulation are critical., (© 2018 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Acute small intestinal allograft rejection presents clinically as an abrupt increase in ileal fluid output in the absence of extensive inflammation. We questioned whether acute intestinal rejection might be accompanied by a disturbance of normal intestinal stem cell differentiation. We examined the intestinal epithelial secretory cell lineage among patients experiencing early rejection before and during rejection as well as following corrective therapy. Lineage-specific progenitors were identified by their expression of stage-specific transcription factors. Progenitors of the enteroendocrine cell (EEC) expressing neurogenin-3 (NEUROG3) were found to be disproportionately reduced in numbers, along with their more mature EEC derivatives expressing neuro D; the enteric hormone PYY was the most profoundly depleted of all the EEC products evaluated. No change in the numbers of goblet or Paneth cells was observed. Steroid treatment resulted in resolution of clinical symptoms, restoration of normal patterns of EEC differentiation and recovery of normal levels of enteric hormones. Acute intestinal rejection is associated with a loss of certain subtypes of EEC, most profoundly, those expressing PYY. Deficiency of the mature EECs appears to occur as a consequence of a mechanism that depletes NEUROG3 EEC progenitors. Our study highlights the dynamics of the EEC lineage during acute intestinal rejection.

Human calicivirus (HuCV), a common cause of mild gastroenteritis in the general population, produces a prolonged diarrheal illness in pediatric recipients of small intestinal transplant (IT). By use of reverse-transcription polymerase chain reaction to detect the viral RNA polymerase gene in stool and tissue from gastrointestinal biopsies, 5 pediatric IT recipients with high-volume diarrhea were diagnosed with HuCV enteritis. Histopathologic findings of biopsies obtained at different gastrointestinal sites were studied retrospectively to identify characteristic features of HuCV enteritis and to distinguish these changes from rejection. Controls were 8 pediatric IT recipients with high-volume diarrhea but negative HuCV reverse-transcription polymerase chain reaction assays during the same time period. All HuCV biopsies showed increased mononuclear infiltrates in the lamina propria and villous blunting. Reactive disarray of surface epithelial cells and increased apoptosis in the surface epithelium and superficial lamina propria were characteristic features (in 4/5 patients). Increased glandular apoptosis was also present in 3/5 patients. Findings were more pronounced in jejunal allograft than ileal allograft, and were present in both graft and native bowel. In comparison with the control group, the architectural changes, surface epithelial reactive changes, and superficial apoptosis were characteristic of HuCV enteritis, while the presence of glandular apoptosis was a feature shared with cases of mild acute cellular rejection HuCV may cause severe allograft dysfunction after pediatric IT. Calicivirus infection has clinical and histological features that overlap with allograft rejection. Knowledge of the characteristic histologic features of HuCV enteritis aids in differential diagnosis.

Biopsy is the only means to identify intestinal graft rejection. Plasma citrulline (P-Cit) has been proposed as a marker for rejection after intestinal transplant (IT), but normative data is lacking. We analyzed P-Cit in IT recipients without rejection or other histological abnormalities. In 40 patients, P-Cit was measured with a Beckman amino acid analyzer within 24 h of protocol or clinically indicated endoscopic biopsy procured > 6 and < 360 days post-IT. Measurements included for analysis corresponded to normal (or minimally abnormal) biopsies that remained so for 7 days. These criteria were met by 145 samples from 10 adults and 14 children. Overall mean P-Cit (nmol/mL) was 34.0 +/- 19.9. Mean P-Cit was 22.2 +/- 13.2 between 6 and 30 days post-IT, 34.9 +/- 17.2 (p = 0.001) between 30 and 60 days, 43.6 +/- 15.8 between 60 and 90 days (p = 0.001), then stable until the end of the first year. Plasma citrulline was lower in 13 patients with body surface area (BSA) < or = 1 m2 vs. 11 patients with BSA > or = 1.1 m2 (p = 0.0001). Plasma citrulline increased linearly during the first 120 days in both BSA groups (r = 0.573 and r = 0.512; p = 0.0001). Within 3 months after IT, variations in P-Cit based on body size and postop interval should be considered when evaluating the need for histological confirmation of graft dysfunction.

Background: The purpose of this study was to determine the prevalence of adenoviral infection in pediatric small bowel transplantation (SBT) recipients, examine risk factors for progression to histologic disease, and examine the impact of adenovirus on outcome., Methods: Beginning in July 2000, all SBT recipients had viral cultures for adenovirus, cytomegalovirus (CMV), and herpes simplex virus (HSV) obtained routinely during graft biopsies. The medical records were retrospectively reviewed for frequency and site of viral culture, types and doses of immunosuppressive drugs, episodes of rejection, histology of allograft biopsies, and other infections. Adenoviral isolates were typed by polymerase chain reaction and type-specific neutralization assays., Results: All 14 SBT recipients who met enrollment criteria had evidence of adenoviral infection (intestinal graft, 13; liver graft, 1). Eight of 14 developed histologic disease with identifiable adenoviral intranuclear inclusions. In contrast, CMV enteritis was identified in only one patient, who subsequently also developed adenoviral disease. No other viruses were detected. Adenoviral cultures were first positive within 30 days of transplant in nine. Patients with histologic disease were more likely than those without to have received intensive corticosteroid therapy (P<0.007), had virus isolated from more than one site (P=0.03), and had persistent positive cultures (P<0.01)., Conclusions: Adenovirus was commonly isolated from children undergoing intestinal transplantation. Progression to disease may be associated with more intensive immunosuppressive therapy and inability to clear virus.

Intestinal transplantation is now an accepted therapy for intestinal failure when parenteral nutrition therapy cannot be tolerated. During the past year, evidence has been provided indicating that neither stomach nor colon need to be included in the transplant, even if a primary motility disorder is the indication for surgery. The liver should be included in the composite allograft when there are clinical indications of portal hypertension resulting from parenteral nutrition associated cholestasis. When liver disease develops, operations intended to improve gut function should be avoided in preference of early listing for transplantation. During the past year, initial attempts at adult to child intestinal transplantation were carried out with some success; reduction in the diameter of the adult donor bowel may not be uniformly necessary. New immunosuppressive therapies have been employed recently, but few have been subjected to peer review. Experimental models have clarified the pathology, if not the immunobiology, of chronic intestinal allograft rejection and the ability of the liver to promote tolerance of a cotransplanted intestinal allograft. Treatment of posttransplant lymphoproliferative disease has been augmented by the use of anti-CD 20 antibody that targets Epstein-Barr virus infected B-cells for destruction with high specificity.

Background: Small bowel bacterial overgrowth is a common complication of short bowel syndrome, and although it is often controlled with antimicrobial therapy, alternative strategies may occasionally be needed., Methods: Six patients with bacterial overgrowth are described, who did not respond to antimicrobial therapy and required additional medical or surgical measures to control the overgrowth., Results: Recalcitrant bacterial overgrowth was successfully treated with periodic small bowel irrigation with a balanced hypertonic electrolyte solution, colonic flushes, encouraging frequent stooling, intestinal lengthening procedure, or probiotic therapy with Lactobacillus plantarum 299V and Lactobacillus GG., Conclusions: Small bowel bacterial overgrowth should be aggressively evaluated in patients with short bowel syndrome who are not progressing in a normal manner. Inadequate or incomplete response to antibiotic therapy is common, and several additional treatment possibilities are available.

The insulin-like growth factor binding proteins (IGFBPs) act to modulate the growth and differentiation of the gastrointestinal mucosa by regulating cellular responses to the important mitogens, the insulin-like growth factors (IGFs). The transplanted small bowel must maintain the normal growth factor interrelationships and signaling pathways despite the potential of host rejection. Ostomy effluent of patients after small bowel or combined liver/small bowel transplantation was assayed for IGFBPs to investigate the effect of rejection on the IGF-IGFBP axis. Seventeen patients were studied over an 18-month period. The transplanted small bowel produced no measurable IGFBPs in the ostomy effluent under normal circumstances. However, when rejection was taking place the ostomy effluent was found to have measurable IGFBP levels in 6 of 12 episodes, the 6 episodes occurring in 6 different patients. Mostly, the IGFBPs present did not exhibit a serum-like pattern indicating the secretion of IGFBPs into the effluent was not the result of loss of mucosal barrier integrity. There were no statistically significant differences in protein content of the ostomy fluids in the presence or absence of rejection. Our results suggest that the gastrointestinal IGF axis is altered during some instances of transplanted small bowel rejection, with increased secretion of IGFBPs.

Following intestinal transplantation, we have found that recovery from severe rejection may be difficult to identify. In this study we sought to ascertain whether concurrent determination of mucosal disaccharidase activities and histologic assessment improves the accuracy of diagnosis of rejection. Histologic changes were graded blindly using a standard set of diagnostic criteria, and these changes were compared over time to maltase, sucrase, lactase, and palatinase activities in four pediatric patients under treatment for severe rejection. The histologic criteria, which included magnitude of enterocyte loss, degree of granulation tissue, severity of villus atrophy, and frequency of apoptosis and cryptitis, were found to correlate with one another over time irrespective of outcome (r = 0.72 to r = 0.85). Enzyme activities were also correlated with each other over time (r = 0.64 to r = 0.80). However, the correlation between histologic diagnosis and enzyme activity was weaker (r = -0.48 to r = -0.57). Furthermore, neither histologic nor enzyme evaluation early in the course of rejection predicted ultimate clinical outcome. The results of this investigation show that determination of mucosal disaccharidase activity provides no additional useful information concerning efficacy of anti-rejection therapy as compared to histologic analysis alone.

Children who have undergone liver transplantation may develop chronic diarrhea for a number of reasons. Three children who underwent liver transplantation for liver failure, all of whom had had previous biliary and intestinal surgeries and whose postoperative course was marked by signs and symptoms of intestinal malabsorption including chronic diarrhea, are described. Duodenal aspirates showed a panoply of bacterial species, and duodenal histology featured villus atrophy in two: one associated with luminal gram-positive cocci and another with acute and chronic duodenitis. Oral antibiotics cleared the symptoms. Small bowel bacterial overgrowth may need to be considered in children with chronic diarrhea after liver transplantation, especially when previous intestinal surgery has taken place. Long-term antibiotic therapy may be required to effectively eradicate the offending organisms to suppress symptoms.

Patients undergoing massive small bowel resection for a variety of conditions develop severe nutrient malabsorption which gradually improves through mucosal hyperplasia in the remaining small intestine. Following massive small bowel resection, patients are generally fed elemental diets, often containing high concentrations of medium-chain triglycerides. We evaluated the effect of high percentage medium-chain triglyceride feeding on mucosal adaptation following massive small bowel resection in rats. Twenty 150-g Sprague-Dawley rats were subjected to 60% jejunoileal resection. Another 20 animals received sham operations. One-half of each group were fed a diet containing 83% of the fat as medium-chain triglycerides, the remainder were fed a diet containing 40% medium-chain triglycerides. Animals were pair-fed for 2 wk and subsequently killed. The remaining bowel was removed and unidirectional glucose and leucine uptake were measured using isolated sacs. Mucosal wet weight, protein, and sucrase content were determined. Animals fed medium-chain triglycerides demonstrated decreased mucosal weight in the proximal bowel, decreased mucosal sucrase activity in the proximal bowel, and decreased mucosal leucine uptake in the distal bowel. While medium-chain triglycerides offer an advantage to patients with short bowel syndrome because they are easily absorbed, they may not stimulate the same degree of mucosal adaptation following resection as long-chain triglyceride feedings.