Intestinal Allograft Rejection Research Articles

Comprehensive characterization of immunogenic cell death in acute myeloid leukemia revealing the association with prognosis and tumor immune microenvironment

BackgroundThis study aimed to explore the clinical significance of immunogenic cell death (ICD) in acute myeloid leukemia (AML) and its relationship with the tumor immune microenvironment characteristics. It also aimed to provide a potential perspective for bridging the pathogenesis of AML and immunological research, and to provide a theoretical basis for precise individualized treatment of AML patients.MethodsFirstly, we identified two subtypes associated with ICD by consensus clustering and explored the biological enrichment pathways, somatic mutations, and tumor microenvironment landscape between the ICD subtypes. Additionally, we developed and validated a prognostic model associated with ICD-related genes. Finally, we conducted a preliminary exploration of the construction of disease regulatory networks and prediction of small molecule drugs based on five signature genes.ResultsDifferentially expressed ICD-related genes can distinguish AML into subgroups with significant differences in clinical characteristics and survival prognosis. The relationship between the ICD- high subgroup and the immune microenvironment was tight, showing significant enrichment in immune-related pathways such as antibody production in the intestinal immune environment, allograft rejection, and Leishmaniasis infection. Additionally, the ICD- high subtype showed significant upregulation in a variety of immune cells such as B_cells, Macrophages_M2, Monocytes, and T_cells_CD4. We constructed a prognostic risk feature based on five signature genes (TNF, CXCR3, CD4, PIK3CA and CALR), and the time-dependent ROC curve confirmed the high accuracy in predicting the clinical outcomes.ConclusionThere is a strong close relationship between the ICD- high subgroup and the immune microenvironment. Immunogenicity-related genes have the potential to be a prognostic biomarker for AML.

Suppressor T helper type 17 cell responses in intestinal transplant recipients with allograft rejection

BackgroundIntestinal transplant (ITx) rejection is associated with memory T helper type 17 cell (Th17) infiltration of grafted tissues. Modulation of Th17 effector cell response is facilitated by T regulatory (Treg) cells, but a phenotypic characterization of this process is lacking in the context of allograft rejection. MethodsFlow cytometry was performed to examine the expression of surface receptors, cytokines, and transcription factors in Th17 and Treg cells in ITx control (n = 34) and rejection patients (n = 23). To elucidate key pathways guiding the rejection biology, we utilized RNA sequencing (RNAseq) and assessed epigenetic stability through pyrosequencing of the Treg-specific demethylated region (TSDR). ResultsWe found that intestinal allograft rejection is characterized by Treg cellular infiltrates, which are polarized toward Th17-type chemokine receptor, ROR-γt transcription factor expression, and cytokine production. These Treg cell subsets have maintained epigenetic stability, as defined by FoxP3-TSDR methylation status, but displayed upregulation of functional Treg and purinergic signaling genes by RNAseq analysis such as CD39, in keeping with suppressor Th17 properties. ConclusionWe show that ITx rejection is associated with increased polarized cells that express a Th17-like phenotype concurrent with regulatory purinergic markers.

Immunologic Complications and Graft Survival in Crohn's Disease and NOD2 Mutant Non-Crohn's Disease Adult Recipients Following Intestine Transplantation.

Background.Despite improved outcomes in the modern era of targeted immunotherapy, intestinal failure and chronic parenteral nutrition remains a significant burden for patients with Crohn’s disease (CD) worldwide. Transplantation is a key component of management when a patient with CD suffers from life-threatening complications of parenteral nutrition. Nucleotide-binding oligomerization domain 2 (NOD2) mutation is a risk factor for both development of CD and intestinal allograft rejection.Methods.A retrospective review of a prospectively maintained database of intestinal transplants at a single center from 2003 to 2015 was conducted. Eleven adult patients with CD were identified and were compared with 103 adult control recipients. A sub-analysis was performed comparing the 11 CD recipients to the 13 NOD2 mutant non-CD recipients.Results.Patient and allograft characteristics were similar between the CD and control recipients. Although overall rejection-free survival was not significantly different, patients with CD suffered from more frequent, earlier, and more severe rejection compared with control patients. The onset, severity, and frequency of rejection was comparable between patients with CD and NOD2 mutant non-CD patients. There was a trend toward lower 5-year allograft survival for CD compared with control recipients (33% versus 63.3%; P = 0.19) and NOD2 mutant non-CD recipients (33% versus 57.14%; P = 0.41).Conclusions.Patients with CD remain a challenging population in intestine transplantation, and NOD2 mutant non-CD patients appear to have a similar immunologic phenotype. These high-risk recipients may require specialized immunosuppression protocols and management at experienced transplant centers.

Severe Late-Onset Acute Cellular Rejection in a Pediatric Patient With Isolated Small Intestinal Transplant Rescued With Aggressive Immunosuppressive Approach: A Case Report

Small intestinal transplantation is performed for patients with intestinal failure who failed other surgical and medical treatment. It carries notable risks, including, but not limited to, acute and chronic cellular rejection and graft malfunction. Late severe acute intestinal allograft rejection is associated with increased risk of morbidity and mortality and, in the majority of cases, ends with total enterectomy. It usually results from subtherapeutic immunosuppression or nonadherence to medical treatment. We present the case of a 20-year-old patient who underwent isolated small bowel transplant for total intestinal Hirschsprung disease at age 7. Due to medication nonadherence, she developed severe late-onset acute cellular rejection manifested by high, bloody ostomy output and weight loss. Ileoscopy showed complete loss of normal intestinal anatomic landmarks and ulcerated mucosa. Graft biopsies showed ulceration and granulation tissue with severe architectural distortion consistent with severe intestinal graft rejection. She initially received intravenous corticosteroids and increased tacrolimus dose without significant improvement. Her immunosuppression was escalated to include infliximab and finally antithymocyte globulin. Graft enterectomy was considered repeatedly; however, clinical improvement was noted eventually with evidence of histologic improvement and salvage of the graft. The aggressive antirejection treatment was complicated by development of post-transplant lymphoproliferative disorder that resolved with reducing immunosuppression. Her graft function is currently maintained on tacrolimus, oral prednisone, and a periodic infliximab infusion. We conclude that a prompt and aggressive immunosuppressive approach significantly increases the chance of rescuing small bowel transplant rejection.

P1.57: Severe Late Onset Acute Cellular Rejection in a Pediatric Patient with isolated small intestinal transplant rescued with aggressive immunosuppressive approach

Introduction: Small intestinal transplantation has been the standard treatment modality for pediatric patient with intestinal failure who failed other surgical and medical treatment. At its current stage, it carries its own risks including but not limited to acute and chronic cellular rejection, graft malfunctions, development of PTLD, viral and bacterial infections. Acute cellular rejection of the intestinal graft is an important and major complication secondary to its rich lymphatic supply. It is usually results from sub therapeutic immunosuppression or non-adherence to medical management. The current management includes modifying the immunosuppression to achieve therapeutic level. Late severe acute intestinal allograft rejection is associated with increased risks of sepsis, bleeding and in the majority of cases with graft loss that ends up in graft enterectomy. We present a case of a 20 year old patient who underwent isolated small bowel transplant for complete intestinal Hirschsprung Disease at age 7 years old, but due to medication non-adherence developed severe late-onset acute cellular rejection manifested by large ostomy OP, fever, weight loss. Underwent ileoscopy on presentation that showed complete loss of normal anatomical intestinal landmarks, bleeding, and ulcerated mucosa. Graft biopsies showed ulceration and granulation tissue with severe architectural distortion, and rare residual consistent with severe intestinal graft rejection. She initially received pulse doses of Intravenous corticosteroids and increased dose of tacrolimus without significant improvement. Her immunosuppression plan was escalated to include infliximab and finally had Antithymocyte globulin (ATG). Graft enterectomy option was entertained frequently during the treatment course; however clinical improvement was noted with evidence of histological improvement and salvage of the graft. The aggressive anti-rejection treatment was complicated with the development of monomorphic, plasmacytoma (PTLD) that was managed with modifying her immunosuppression. Now her graft function is maintained on tacrolimus, oral prednisone, and routine Remicade infusion. Conclusion: 1-Small bowel graft rejection is associated with increased morbidity and mortality, increased risks of sepsis, bleeding and graft loss. 2-We believe that prompt and aggressive immunosuppressive approach significantly increases the chance of rescuing small bowel transplant rejection.

The parallel paradigm between intestinal transplant inflammation and inflammatory bowel disease.

A significant shift in our understanding of the molecular and cellular basis for inflammatory bowel disease (IBD) mirrors research that has been ongoing in intestinal transplantation. The blurring of lines between these two disease states creates an avenue into potential therapeutic interventions which take advantage of these molecular similarities. Traditional knowledge of T-cell involvement in IBD has expanded to highlight the role of T helper 17 (Th17) cells as key effector cells. A similar role has been demonstrated in cellular rejection of intestinal allografts. Genetic polymorphism related to the propagation and function of Th17 cells has been found to confer significant risk of developing autoimmune conditions. Interleukin-23, a cytokine identified as crucial to the expansion of Th17 cells, has become a validated molecular target in psoriatic arthritis and IBD, and could become a target for intestinal transplant therapies. Intestinal transplant rejection and IBD share a similar phenotype, especially as it relates to key effector cells and gene polymorphisms. Improvements in our understanding of the immune-pathogenesis of IBD, as well as molecular targeting exploiting that knowledge, provide a potential route to improve outcomes for intestinal transplant patients.

Mucosal Macrophage Accumulation is an Early Event in Exfoliative Rejection of Intestinal Allografts

Background: Despite potent induction immunosuppression, remains to be a major problem after intestine/multivisceral transplantation, and carries high mortality. Mechanistic studies to understand early exfoliative rejection (EER) are required to improve graft and patient survival. Methods: Mucosal biopsies from 12 patients with EER were studied. Biopsies prior to and during rejection episodes were stained for CD163 (macrophage marker), CD4 and CD8. Mucosal biopsies from intestine transplant recipients in the absence of rejection served as controls. Biopsies non-transplant terminal ileum and colon were stained to ascertain normal patterns of cellular distribution. Grafts explanted after EER were studied in 3 patients. Cellular infiltrate was graded by two blinded pathologists as absent (0), minimal (1+), moderate (2+) and extensive (3+). Results: There was an increase in the number of macrophages (1+ in 7; 2+ in 4, and 3+ in 9) in 9(75%) patients with EER (Figure 1). Macrophage accumulation was present even in biopsies that did not show the requisite 6 apoptosis per 10 crypts required for diagnosis of rejection. No biopsy from control patients or intestine allografts without rejection showed an increase in mucosal macrophages. The majority of biopsies from patients with EER showed normal (35, 64%) and decreased (14, 25%) cellular infiltration with CD4+ cells, whereas 11% biopsies showed a mild increase (1+). Similarly, the majority of biopsies (49, 89%) showed a normal or decreased number of CD8+ cells whereas 11% showed an increase. All explants showed an (100%). Almost all explants showed absence of macrophages, absent or decreased CD4+ cells and normal or slightly increased number of CD8+ cells. Conclusions: 1) Mucosal accumulation of macrophages is an early event in development EER, which are present even in the absence of sufficient crypt apoptotic activity. 2) The absence of macrophages in the explants, may suggest that these cells are the cause (effector cells) rather than the effect (scavenger cells) in this setting. 3) Increased macrophages combined with an absence or decrease of CD4 and CD8 cells in rejection biopsies suggests that current therapeutic regimens are effective against T cells but not macrophages.FigureH & E, CD4, CD8 and CD163 staining (left to right) in transplant intestine biopsies prior to EER (top row), EER (second row), without rejection (third row) and non-transplant intestine biopsies (bottom row), x200.

Vedolizumab for the Treatment of Refractory Severe Rejection in Intestinal Transplantation

Introduction: Acute cellular rejection (ACR) is a continuous challenge in intestinal transplantation despite the advent of potent immunosuppressive drugs. Most of the traditional drugs used to treat ACR destroy specific cell lines with important systemic side effects. Migration of the activated recipient lymphocytes (T Cells) to the mucosal surface can trigger ACR in intestinal transplant. It has been demonstrated in a murine model of intestinal transplantation that during ACR allografts are infiltrate by large numbers of α4β7 T cells and the treatment with a blocking antibody specific for β7 significantly reduces the cellular infiltrate and inhibits ACR.[1] Vedolizumab is a humanized monoclonal antibody that binds specifically to the α4β7 integrin, inhibiting T lymphocytes from binding to adhesion molecules (MAdCAM-1), which are expressed mainly in the small bowel and colon. Consequently, vedolizumab can be considered a specific intestinal immunosuppressant, making it especially attractive in intestinal transplantion. Vedolizumab could provide specific down-modulation of the mucosal inflammatory response that is characteristic of IBD and allograft intestinal rejection, thereby allowing re-establishment of homeostasis in the intestinal immune system. Methods: Our group is reporting, to the best of our knowledge, the first report of using Vedolizumab for the treatment of severe ACR in intestinal transplantation. Results: 25 years old, female, with history of Crohn’s disease received an intestinal and colon transplant. After 6 months of follow up patient started missing clinical appointments and presenting undetectable immunosuppressant levels. Eleven months after the transplant patient presented to the ER critically ill. Scope with biopsy was performed showing severely inflamed mucosa, absence of villi, diffuse bleeding and ulcers. All the viral studies were negative. Alemtuzumab 30 mg X 2, Rituximab and steroids were given. After 2 weeks without improvement of symptoms another endoscopic evaluation was performed. Areas of moderate to severe erythematous mucosa without villi, severe friability and active bleeding was found. Patient was over-immunosuppressed and we opted to treat with Vedolizumab (x3). After 10 days from the first dose, a new scope was performed showing regeneration of villi, improved friability and no active bleeding. New scopes showed continuosly improvement of the mucosa followed by resolution of symptoms. PN was weaned and patient was discharged without parenteral support. Conclusions: Vedolizumab was successfully used to rescue a patient with severe rejection after failure of other therapies. It acts specifically in the intestinal mucosa with a much safer side-effect profile. More studies are necessary but it may become an excellent choice to treat or prevent rejection in intestinal transplantation. Reference: 1. Kellersmann R, et al. Monoclonal antibody against beta7 integrins, but not beta7 deficiency, attenuates intestinal allograft rejection in mice. Transplantation 2002 Nov 15;74(9):1327–34

An integrated understanding of the immunology of allograft inflammation.

The purpose of this review is to summarize recent advances in our understanding of the complex immunology of intestinal transplantation and allograft rejection. Recent findings highlight the importance of the intestinal microbiome for intestinal homeostasis and the role of newly discovered innate lymphoid cells in intestinal transplantation. In addition, the role of host antimicrobial Th17 responses in the pathogenesis of inflammatory bowel diseases and intestinal allograft rejection has been further elucidated. Research on the complex immune system of the intestine has continued to reveal more intricacies and connections with each study performed, making treatment of intestinal transplant patients more multifaceted. The interaction, communication, and relationships between areas such as the microbiome, innate lymphoid cells, and Th17 cells reveal possible targets for therapy and further areas requiring ongoing research.

Metabolomics of Human Intestinal Transplant Rejection

Surveillance endoscopy with biopsy is the standard method to monitor intestinal transplant recipients but it is invasive, costly and prone to sampling error. Early noninvasive biomarkers of intestinal rejection are needed. In this pilot study we applied metabolomics to characterize the metabolomic profile of intestinal allograft rejection. Fifty-six samples of ileostomy fluid or stool from 11 rejection and 45 nonrejection episodes were analyzed by ultraperformance liquid chromatography in conjunction with Quadrupole time-of-flight mass spectrometry (UPLC-QTOFMS). The data were acquired in duplicate for each sample in positive ionization mode and preprocessed using XCMS (Scripps) followed by multivariate data analysis. We detected a total of 2541 metabolites in the positive ionization mode (mass 50-850 Daltons). A significant interclass separation was found between rejection and nonrejection. The proinflammatory mediator leukotriene E4 was the metabolite with the highest fold change in the rejection group compared to nonrejection. Water-soluble vitamins B2, B5, B6, and taurocholate were also detected with high fold change in rejection. The metabolomic profile of rejection was more heterogeneous than nonrejection. Although larger studies are needed, metabolomics appears to be a promising tool to characterize the pathophysiologic mechanisms involved in intestinal allograft rejection and potentially to identify noninvasive biomarkers.

Innate immunity in the small intestine

This article reviews the most recent publications on innate immunity in the small intestine. We will go over the innate immune receptors that act as sensors of microbial presence or cell injury, Paneth cells as the main epithelial cell type that secrete antimicrobial peptides, and mucosal production of immunoglobulin A (IgA). In addition, we will give an update on examples of imbalance of the innate immune response resulting in clinical disease with the most relevant example being Crohn's disease. Toll-like receptors (TLRs) are involved in B-cell homing to the intestine, rejection of small intestinal allografts, and recruitment of mast cells. The TLR adaptor Toll/interleukin-1 receptor domain-containing adapter-inducing interferon-β is necessary to activate innate immunity after Yersinia enterocolitica infection. Moreover, MyD88 is required to keep the intestinal microbiota under control and physically separated from the epithelium, and RegIIIγ is responsible for the bacterial segregation from the lining epithelial cells. In Crohn's disease, ATG16L1 T300A variant promotes a proinflammatory response; and miR-196 downregulates a protective immunity-related GTPase family M protein (IRGM) polymorphism leading to impaired clearance of adherent Escherichia coli in the intestine. The intestine is continuously exposed to dietary and microbial antigens. The host has to maintain intestinal homeostasis to keep the commensal and pathogenic bacteria under control. Some of the mechanisms to do so are by expression of innate immune receptors, production of antimicrobial peptides, secretion of IgA, or autophagy of intracellular bacteria. Unfortunately, in some cases the innate immune response fails to protect the host and chronic inflammation, transplant rejection, or other disorders may occur.

Natural Killer Group 2 Member D Cell Recruitment Driven by Major Histocompatibility Complex Class I Chain–Related Antigens A and B: A Possible Mechanism During Acute Intestinal Allograft Rejection in the Mouse

Intestinal allograft rejection occurs frequently despite potent T-cell depletion protocols. We investigated the interaction of major histocompatibility complex class I chain–related antigens A and B (MICA/B; a ligand for natural killer [NK] cells) and NK group 2 member D (NKG2D) cells as an alternative mechanism for acute rejection (AR) of the intestinal graft. Heterotopic intestinal allotransplantation was performed from BalbC to C57Bl mice. Samples of grafted and native intestine were obtained at days 1, 3, 6, and 8 after transplantation (n = 4–6). We performed immunostaining for MICA/B and NKG2D. Moderate AR with increased crypt apoptosis was observed at day 6 and advanced AR with crypt destruction and mucosal sloughing was present by day 8. Low MICA/B levels were observed in grafted and native intestines on day 1. MICA/B expression gradually increased in the grafts during AR but not in the native intestines. The up-regulation was found mostly in the crypts. NKG2D+ cell counts that increased in the graft colocalized with MICA/B. The increase was most prominent in the crypt and villus. Together, these results suggest that MICA/B up-regulation and its subsequent interaction with the NK cells may represent an important link between innate and adaptive immune responses early after intestinal transplantation.

Hypertrophic osteoarthropathy in intestinal transplant recipients

We report 3 patients with periosteal new bone formation consistent with hypertrophic osteoarthropathy (HOA), in the context of intestinal allograft rejection. Patient 1 developed thick periosteal new bone formation of the right arm during a prolonged episode of intestinal acute cellular rejection (ACR) 2 months posttransplant. Patient 2 developed ankle pain and swelling during an episode of severe ACR. Plain films showed periosteal new bone formation of the left ankle. In patient 3, the right wrist became swollen during an episode of moderate ACR, whereas plain films demonstrated mild periosteal reaction. Patients 2 and 3 had resolution of their symptoms once the ACR resolved with treatment. This is the first case series of HOA occurring in association with intestinal ACR. We speculate that an immune-mediated process is responsible for the bone disease. Further inquiry will help establish if HOA is related to transplant status, intestinal inflammation, or allograft rejection in general.

Acute Rejection of Small Intestine Allografts Is Associated With Increased Expression of Toll-like Receptors

Although outcomes after intestinal transplantation have steadily improved owing to advances in immunosuppressive therapy, operative techniques, and postoperative medical management, rejection of the intestinal allograft continues to be a major clinical problem and constitutes the primary reason for graft loss. Although the adaptive immune system has been the major focus of investigation regarding regulation of rejection of the intestinal allograft, the role of the innate immune system has recently become of increased interest. We hypothesized that microbial products of the microflora associated with the intestinal allograft may engage the Toll-like receptor pathway of the innate immune system to potentiate alloimmune responses and rejection of the allograft. To investigate this, we established a murine model for orthotopic intestinal transplantation and allograft rejection. Using this model, we show that the expression of Toll-like receptor 2 is increased 50-fold and the expression of Toll-like receptor 4 is increased 200-fold during rejection of the allograft. We then performed survival studies that showed increased survival of mice, which had the Toll-like receptor knocked out. These preliminary studies suggest an important role for in innate immune system in acute rejection of the small intestinal allografts, and as such represents an emerging and promising area of investigation.

954 Carbohydrate Digestion in Congenital Sucrase Isomaltase Deficient and Recurrent Abdominal Pain Children Assesed by 13C- Starch Breath Test

BACKGROUND: Intestinal allograft rejection is a severe complication in small bowel transplantation. Identifying involved pathogenetic mechanisms might make it possible to predict or even prevent rejection and intestinal graft failure. Rejection resembles Crohn's disease (CD) clinically and histopathologically. We investigated the role of CD-associated genetic loci, including NOD2 variants in rejection and graftfailure. METHODS: 99 recipients and 71 donors from the University of Nebraska Medical Center, USA were genotyped for three NOD2 variants and single nucleotide polymorphisms in IBD5, ATG16L1, IRGM, MST1, IL23R, STAT3 and JAK2. Genotypes were related to clinical outcomes rejection, graftfailure and patient-survival using Kaplan-Meier curves and log-rank analysis. RESULTS: Only the MST1 riskallele was more frequent in recipients compared to donors (30,8% and 20,4%, p=0,032). For the other loci, including NOD2, allelic distribution was equal within the two groups. No single locus was significantly associated with rejection, graftfailure or patientsurvival. There is no significant difference in clinical endpoints whether the recipient has a low or high number of risk alleles. Individuals receiving a donorgraft with ≤5 riskalleles in total, have decreased rejection-free survival compared to ≥6 riskalleles (p=0,040), but increased patient three-year survival (mortality: 4/19 and 16/29, p=0,016). CONCLUSIONS: In this relatively large cohort, we could not confirm the association of NOD2, with rejection and graftfailure. Furthermore we found no association of seven other CD-loci with clinical endpoints. However, patients receiving a donorgraft with six or more risk alleles have decreased three-year survival, but -surprisinglyincreased rejection-free survival.

953 Tryptophan Hydroxylase Gene Variants and IBS Symptoms

BACKGROUND: Intestinal allograft rejection is a severe complication in small bowel transplantation. Identifying involved pathogenetic mechanisms might make it possible to predict or even prevent rejection and intestinal graft failure. Rejection resembles Crohn's disease (CD) clinically and histopathologically. We investigated the role of CD-associated genetic loci, including NOD2 variants in rejection and graftfailure. METHODS: 99 recipients and 71 donors from the University of Nebraska Medical Center, USA were genotyped for three NOD2 variants and single nucleotide polymorphisms in IBD5, ATG16L1, IRGM, MST1, IL23R, STAT3 and JAK2. Genotypes were related to clinical outcomes rejection, graftfailure and patient-survival using Kaplan-Meier curves and log-rank analysis. RESULTS: Only the MST1 riskallele was more frequent in recipients compared to donors (30,8% and 20,4%, p=0,032). For the other loci, including NOD2, allelic distribution was equal within the two groups. No single locus was significantly associated with rejection, graftfailure or patientsurvival. There is no significant difference in clinical endpoints whether the recipient has a low or high number of risk alleles. Individuals receiving a donorgraft with ≤5 riskalleles in total, have decreased rejection-free survival compared to ≥6 riskalleles (p=0,040), but increased patient three-year survival (mortality: 4/19 and 16/29, p=0,016). CONCLUSIONS: In this relatively large cohort, we could not confirm the association of NOD2, with rejection and graftfailure. Furthermore we found no association of seven other CD-loci with clinical endpoints. However, patients receiving a donorgraft with six or more risk alleles have decreased three-year survival, but -surprisinglyincreased rejection-free survival.

Rejection Reversibly Alters Enteroendocrine Cell Renewal in the Transplanted Small Intestine

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.

ADAP deficiency combined with costimulation blockade synergistically protects intestinal allografts

Adhesion and degranulation promoting adapter protein (ADAP) plays an important role in T cell activation. ADAP deficiency was recently found to prolong heart graft survival in mice. We investigated the role of ADAP in intestinal transplantation and the synergistic effect of ADAP deficiency and Costimulation blockade (CB). T cell proliferation and cytotoxic T lymphocyte (CTL) activity were determined. MHC mismatched intestinal allografts was transplanted heterotopically. Anti-CD40L antibody was applied to the recipient. Upon stimulation with allogenic dendritic cells (DC), ADAP-deficient (ADAP-/-) T cells displayed impaired proliferative responses compared with that of wild-type (WT) T cells. In contrast, the CTL activity in ADAP-/- mice was comparable with that of WT mice. Rejection of intestinal allografts was ameliorated, but not prevented in ADAP-/- mice. Although CB alone was not sufficient to mitigate the rejection, the combination of CB and ADAP deficiency profoundly inhibited rejection. This was accompanied by less infiltration and activation of host lymphocytes in the gut-associated lymphoid tissue of intestinal allografts. ADAP deficiency combined with CB protected the intestinal allografts synergistically. ADAP could be a novel target in the induction phase of the immune responses in organ transplantation.

Correlation of Motility and Neuronal Integrity with a Focus on the Grade of Intestinal Allograft Rejection

Intestinal graft motility after small bowel transplantation (SBT) is poorly characterized. The aim of this study was to compare motor patterns with myenteric neuronal cell population as a parameter of graft viability at various degrees of acute cellular rejection (ACR). Three grades of ACR were achieved in orthotopic allografts. Syngeneic transplants and allografts with immunosuppression served as controls. Motor activities were recorded using strain gauge force transducers and analyzed visually. Quantifications of myenteric neurons in whole mounts of intestinal grafts were used to evaluate neuronal population. A typical migrating motor complex (MMC) was found in syngeneic and allogenic transplants with immunosuppression. A high prevalence of discrete clustered contractions (DCC) and nonpropagating contractions (NPC) without MMC was seen in moderately and severely rejected allografts. Neuronal cell loss in the allografts, which could be one of the causes of motor dysfunction, was noted in moderate rejection (19.3%) and progressed until severe rejection (60.1%). Monitoring motility patterns in SBT could be an effective tool for assessing intestinal rejection. Allograft dysmotility, such as absence of MMC and high prevalence of DCC or NPC, could be useful markers of progression of acute rejection and help guide treatment decisions.

NOD2-expressing bone marrow-derived cells appear to regulate epithelial innate immunity of the transplanted human small intestine

Background:Intestinal allograft rejection resembles Crohn’s disease clinically and pathologically. An understanding of its mechanism could impact this life-saving procedure, as well as provide insight into the pathophysiology of inflammatory bowel...