International Grading Scheme for Acute Cellular Rejection in Small-Bowel Transplantation: Single-Center Experience

Tailoring of apoptotic bodies for diagnostic and therapeutic applications:advances, challenges, and prospects

Apoptotic bodies (ABs) are extracellular vesicles released during apoptosis and possess diverse biological activities. Initially, ABs were regarded as garbage bags with the main function of apoptotic cell clearance. Recent research has found that ABs carry and deliver various biological agents and are taken by surrounding and distant cells, affecting cell functions and behavior. ABs-mediated intercellular communications are involved in various physiological processes including anti-inflammation and tissue regeneration as well as the pathogenesis of a variety of diseases including cancer, cardiovascular diseases, neurodegeneration, and inflammatory diseases. ABs in biological fluids can be used as a window of altered cellular and tissue states which can be applied in the diagnosis and prognosis of various diseases. The structural and constituent versatility of ABs provides flexibility for tailoring ABs according to disease diagnostic and therapeutic needs. An in-depth understanding of ABs' constituents and biological functions is mandatory for the effective tailoring of ABs including modification of bio membrane and cargo constituents. ABs' tailoring approaches including physical, chemical, biological, and genetic have been proposed for bench-to-bed translation in disease diagnosis, prognosis, and therapy. This review summarizes the updates on ABs tailoring approaches, discusses the existing challenges, and speculates the prospects for effective diagnostic and therapeutic applications.

Clinicopathologic Characterization of Lymphocytic Colitis in the Pediatric Population

BACKGROUND

Lymphocytic colitis (LC) in the pediatric population has been associated with immune dysregulation.

METHODS

Single-center retrospective study of pediatric LC.

RESULTS

50 patients (35 female, 70%) with a median age of 12 years at diagnosis (interquartile range: 5.7-15.8) of LC were identified. At presentation, 11 patients (22%) had malnutrition, 16 (32%) had a known underlying immune dysregulation, 4 (8%) had celiac disease (CD), and none had a diagnosis of inflammatory bowel disease. The most common medications prior to diagnosis were non-steroidal anti-inflammatory drugs, proton pump inhibitor, and selective serotonin reuptake inhibitors (10% each). Colonic biopsies showed a median number of intraepithelial lymphocytes (IELs)/100 epithelial cells of 48 (range: 25-85), and only 10% of cases had neutrophilic cryptitis. Upper gastrointestinal tract findings included lymphocytic esophagitis (4%), and duodenal IELs without and with villous blunting (9% each) (n: 47). Ten patients (23%) had increased IELs in the terminal ileum (n: 43). Treatments including 5-ASA, budesonide, prednisone, and gluten-free diet improved symptoms in <50% of patients (n: 42), and all follow-up colonoscopies showed persistent LC (n: 13).

CONCLUSION

Our study supports the association of LC with immune-mediated conditions, most commonly celiac disease. Symptomatic improvement was seen in <50% of patients with none of the patients with repeat colonoscopy showing histologic improvement.

Experimental and In Silico Analysis of TEM β-Lactamase Adaptive Evolution

Multiple mutations often have non-additive (epistatic) phenotypic effects. Epistasis is of fundamental biological relevance but is not well understood mechanistically. Adaptive evolution, i.e., the evolution of new biochemical activities, is rich in epistatic interactions. To better understand the principles underlying epistasis during genetic adaptation, we studied the evolution of TEM-1 β-lactamase variants exhibiting cefotaxime resistance. We report the collection of a library of 487 observed evolutionary trajectories for TEM-1 and determine the epistasis status based on cefotaxime resistance phenotype for 206 combinations of 2-3 TEM-1 mutations involving 17 positions under adaptive selective pressure. Gain-of-function (GOF) mutations are gatekeepers for adaptation. To see if GOF phenotypes can be inferred based solely on sequence data, we calculated the enrichment of GOF mutations in the different categories of epistatic pairs. Our results suggest that this is possible because GOF mutations are particularly enriched in sign and reciprocal sign epistasis, which leave a major imprint on the sequence space accessible to evolution. We also used FoldX to explore the relationship between thermodynamic stability and epistasis. We found that mutations in observed evolutionary trajectories tend to destabilize the folded structure of the protein, albeit their cumulative effects are consistently below the protein's free energy of folding. The destabilizing effect is stronger for epistatic pairs, suggesting that modest or local alterations in folding stability can modulate catalysis. Finally, we report a significant relationship between epistasis and the degree to which two protein positions are structurally and dynamically coupled, even in the absence of ligand.

Evaluating the diagnostic value of zoom endoscopic surveillance compared to routine biopsy after intestinal transplantation

BACKGROUND

After intestinal transplantation, close allograft monitoring especially during the early postoperative period is crucial since the intestine is a highly immunogenic organ. Current protocols are based on endoscopic and histologic examination with the latter one being linked to the risk of bleeding and perforation.

AIMS

Evaluation of the diagnostic value of endoscopy utilizing magnification to predict acute cellular rejection compared to routine allograft biopsies.

METHODS

Fourteen patients underwent the protocol with longitudinal zoom endoscopic and histological graft monitoring during the first year after transplantation. The intestinal mucosa was analyzed during endoscopy utilizing the SASAKI score while a minimum of two biopsies were taken during each examination. A new graduation of severity for acute cellular rejection based on the findings of the SASAKI score is established.

RESULTS

Endoscopic findings of 385 examinations and more than 1000 intestinal allograft biopsies were analyzed. A total of 7 acute cellular rejection episodes in 6/14 patients occurred. Allograft endoscopy was able to diagnose ACR with a sensitivity of 76% and a specificity of 82%.

CONCLUSIONS

Our results will be critical for refining protocols for allograft monitoring after intestinal transplantation thus paving the way towards less invasive measures.

CD4+ T cells persist for years in the human small intestine and display a TH1 cytokine profile

Studies in mice and humans have shown that CD8⁺ T cell immunosurveillance in non-lymphoid tissues is dominated by resident populations. Whether CD4⁺ T cells use the same strategies to survey peripheral tissues is less clear. Here, examining the turnover of CD4⁺ T cells in transplanted duodenum in humans, we demonstrate that the majority of CD4⁺ T cells were still donor-derived one year after transplantation. In contrast to memory CD4⁺ T cells in peripheral blood, intestinal CD4⁺ T_RM cells expressed CD69 and CD161, but only a minor fraction expressed CD103. Functionally, intestinal CD4⁺ T_RM cells were very potent cytokine producers; the vast majority being polyfunctional T_H1 cells, whereas a minor fraction produced IL-17. Interestingly, a fraction of intestinal CD4⁺ T cells produced granzyme-B and perforin after activation. Together, we show that the intestinal CD4⁺ T-cell compartment is dominated by resident populations that survive for more than 1 year. This finding is of high relevance for the development of oral vaccines and therapies for diseases in the gut.

Grant monitoring after intestinal transplantation

PURPOSE OF REVIEW

The current review aims to describe in detail the most common practices utilized to monitor graft function in intestinal transplant (ITx) recipients. In addition, to discussing the role of endoscopy and stool studies it will examine the use of other potential biomarkers which have been utilized. Data will be discussed from contemporary publications in the field, the Intestinal Transplant Registry as well as detailed data from a large, ITx single-center.

RECENT FINDINGS

Significant improvements have been made in early outcomes following ITx, yet long-term survival remains challenged by infection and rejection, both of which can present with diarrhea. While endoscopy and stool studies are the gold-standard for graft monitoring, calprotectin, citrulline, measurements of immunoreactivity and donor-specific antibodies have been investigated in the field and are herein reviewed.

SUMMARY

Despite a number of tests which are currently available for monitoring ITx recipients, a strong need exists for improved noninvasive, timely and accurate biomarkers to help improve ITx graft and patient survival.

Surveillance of Rejection After Intestinal Transplantation Using an Image Enhanced Endoscopy "VENCH" Scoring System

BACKGROUND

Graft rejection after intestinal transplantation remains challenging. We aimed to use endoscopy for rejection prediction.

MATERIALS AND METHODS

Patients ≥7 years old who underwent intestinal transplantation between November 2016 and September 2019 were prospectively enrolled. Magnifying endoscopy under narrow-band imaging was performed through ileostomy. Endoscopic findings were reported as five components (each graded from 0-2): "V" (villi appearance), "E" (erythema), "N" (capillary network), "C" (crypt widening), and "H" (heterogeneity). The correlation between histological severity and endoscopic score was analyzed.

RESULTS

Ninety-nine endoscopic biopsies from three female and one male patient were analyzed. The mean ± SD age was of 41.25±13.77 (range 29-58) years. Three short bowel syndrome patients after multiple intestinal resections and one with chronic intestinal pseudo-obstruction were indicated for intestinal transplantation. Sensitivity, specificity, and accuracy of V, E, N, C, and H scores for predicting rejection were 97.4%, 45.9%, 65.7%; 94.7%, 70.5%, 79.8%; 97.4%, 52.5%, 69.7%; 94.7%, 54.1%, 69.7%; and 97.4%, 62.3%, 75.8%, respectively. Pearson's correlation coefficients between total and individual V, E, N, C, H scores and histological rejection were 0.79, 0.64, 0.70, 0.71, 0.73, and 0.66, respectively (P < .001). To predict mild and moderate/severe rejection, total scores more than 4 and 6 had the sensitivity/specificity of 87.50%/57.38% and 96.67%/85.25%, respectively (area under the ROC 0.791 and 0.987).

CONCLUSION

Endoscopic VENCH scoring is promising for predicting rejection after IT. More studies are warranted to validate such results. (ClinicalTrials.gov number, NCT03616548.).

Resident memory CD8 T cells persist for years in human small intestine

Bartolomé-Casado et al. demonstrate that human gut contains large numbers of resident memory CD8 T cells that survive for years. Intestinal CD8 Trm cells have a clonally expanded immune repertoire that is stable over time and exhibit enhanced protective capabilities.

Resident memory CD8 T (Trm) cells have been shown to provide effective protective responses in the small intestine (SI) in mice. A better understanding of the generation and persistence of SI CD8 Trm cells in humans may have implications for intestinal immune-mediated diseases and vaccine development. Analyzing normal and transplanted human SI, we demonstrated that the majority of SI CD8 T cells were bona fide CD8 Trm cells that survived for >1 yr in the graft. Intraepithelial and lamina propria CD8 Trm cells showed a high clonal overlap and a repertoire dominated by expanded clones, conserved both spatially in the intestine and over time. Functionally, lamina propria CD8 Trm cells were potent cytokine producers, exhibiting a polyfunctional (IFN-γ⁺ IL-2⁺ TNF-α⁺) profile, and efficiently expressed cytotoxic mediators after stimulation. These results suggest that SI CD8 Trm cells could be relevant targets for future oral vaccines and therapeutic strategies for gut disorders.

Transcriptional profiling reveals monocyte-related macrophages phenotypically resembling DC in human intestine

The tissue dendritic cell (DC) compartment is heterogeneous, and the ontogeny and functional specialization of human tissue conventional DC (cDC) subsets and their relationship with monocytes is unresolved. Here we identify monocyte-related CSF1R⁺Flt3^- antigen presenting cells (APCs) that constitute about half of the cells classically defined as SIRPα⁺ DCs in the steady-state human small intestine. CSF1R⁺Flt3^- APCs express calprotectin and very low levels of CD14, are transcriptionally related to monocyte-derived cells, and accumulate during inflammation. CSF1R⁺Flt3^- APCs show typical macrophage characteristics functionally distinct from their Flt3⁺ cDC counterparts: under steady-state conditions they excel at antigen uptake, have a lower migratory potential, and are inefficient activators of naïve T cells. These results have important implications for the understanding of the ontogenetic and functional heterogeneity within human tissue DCs and their relation to the monocyte lineage.

Transcriptional and functional profiling defines human small intestinal macrophage subsets

Macrophages (Mfs) are instrumental in maintaining immune homeostasis in the intestine, yet studies on the origin and heterogeneity of human intestinal Mfs are scarce. Here, we identified four distinct Mf subpopulations in human small intestine (SI). Assessment of their turnover in duodenal transplants revealed that all Mf subsets were completely replaced over time; Mf1 and Mf2, phenotypically similar to peripheral blood monocytes (PBMos), were largely replaced within 3 wk, whereas two subsets with features of mature Mfs, Mf3 and Mf4, exhibited significantly slower replacement. Mf3 and Mf4 localized differently in SI; Mf3 formed a dense network in mucosal lamina propria, whereas Mf4 was enriched in submucosa. Transcriptional analysis showed that all Mf subsets were markedly distinct from PBMos and dendritic cells. Compared with PBMos, Mf subpopulations showed reduced responsiveness to proinflammatory stimuli but were proficient at endocytosis of particulate and soluble material. These data provide a comprehensive analysis of human SI Mf population and suggest a precursor-progeny relationship with PBMos.

5-gene differential expression predicts stability of human intestinal allografts

In intestinal allografts, endoscopy and histology detect the injury once changes in the bowel wall architecture have occurred. We aimed to identify a molecular signature that could predict early deterioration, within histologically indistinguishable biopsies with "minimal changes" (MC) pathology. Sixty biopsies from 12 adult recipients were longitudinally taken during 8years post-transplant. They were classified as either stable (STA) or non-stable (NSTA) according to the prospectively recorded number, frequency and severity of rejection events of the allograft. In a discovery set of MC samples analyzed by RNA-Seq, 816 genes were differentially expressed in STA vs NSTA biopsies. A group of 5 genes (ADH1C, SLC39A4, CYP4F2, OPTN and PDZK1) correctly classified all NSTA biopsies in the discovery set and all STA biopsies from an independent set. These results were validated by qPCR in a new group of MC biopsies. Based on a logistic regression model, a cutoff of 0.28 predicted the probability of being a NSTA biopsy with 85% sensitivity and 69% specificity. In conclusion, by analyzing MC samples early after transplantation, the expression of a 5-gene set may predict the evolution of the bowel allograft. This prognostic biomarker may be of help to personalize care of the intestinal transplant recipient.

Impacts of donor-specific anti-HLA antibodies and antibody-mediated rejection on outcomes after intestinal transplantation in children

AMR is a risk factor for graft failure after SBTx. We studied impact of DSAs and AMR in 22 children transplanted between 2008 and 2012 (11 isolated SBTx, 10 liver inclusive Tx, and one modified multivisceral Tx). Three patients never developed DSA, but DSAs were found in seven in the pre-Tx period and de novo post-Tx in 19 children. Pathology revealed cellular rejection (15/19), with vascular changes and C4d+. Patients were treated with IV immunoglobulins, plasmapheresis, and steroids. Rescue therapy included antithymocyte globulins, rituximab, eculizumab, and bortezomib. Pathology and graft function normalized in 13 patients, graft loss occurred in two, and death in seven. At the end of the follow-up, 15 children were alive (68%), 13 with functioning graft (59%). Prognosis factors for poor outcome after Tx were the presence of symptoms at AMR suspicion (P +.033). DSAs were often found following SBTx, mostly de novo. Resistant ACR or severe AMR is still difficult to differentiate, with a high need for immunosuppression in both. DSAs may precede development of severe disease and pathology features on the graft: relationship and correlation need to be better investigated with larger groups before and after Tx.

Pancreas Transplantation After Liver Transplantation: A Case Report

Our aim was to describe the clinical indications, surgical technique, and clinical outcomes of a pancreas transplantation, performed 4 years after liver transplantation, as treatment for new-onset, uncontrolled diabetes mellitus in a 53-year-old man. Liver transplantation was performed for end-stage liver disease secondary to hepatitis B virus infection and hepatocellular carcinoma. The patient had no history of diabetes prior to the liver transplantation. The decision to proceed with a pancreas transplantation was made when the patient's blood sugar levels could not be normalized despite insulin doses >100 IU/d. A modified cadaveric transplantation technique was used, with the recipient's inferior vena cava dissected for anastomosis with the portal vein of the graft, using a diamond-shaped patch procedure. Moreover, the right common iliac artery was anastomosed with a Y-graft in the pancreas graft, and the duodenum remnant of the graft was anastomosed to the recipient's duodenum using a side-to-side procedure. The 6-month postoperative follow-up included repeated endoscopic biopsy of the graft duodenum, with no evidence of thrombosis or rejection of the graft, with glucose level within normal limits without requirement for diabetic drugs. To our knowledge, this is the first reported case of pancreas transplantation after liver transplantation.

Antibody-secreting plasma cells persist for decades in human intestine

Plasma cells (PCs) produce antibodies that mediate immunity after infection or vaccination. In contrast to PCs in the bone marrow, PCs in the gut have been considered short lived. In this study, we studied PC dynamics in the human small intestine by cell-turnover analysis in organ transplants and by retrospective cell birth dating measuring carbon-14 in genomic DNA. We identified three distinct PC subsets: a CD19⁺ PC subset was dynamically exchanged, whereas of two CD19^- PC subsets, CD45⁺ PCs exhibited little and CD45^- PCs no replacement and had a median age of 11 and 22 yr, respectively. Accumulation of CD45^- PCs during ageing and the presence of rotavirus-specific clones entirely within the CD19^- PC subsets support selection and maintenance of protective PCs for life in human intestine.

Inferior Vena Cava-Duodenal Drainage in Pancreas Alone Transplantation for Chronic Pancreatitis: A Case Report

Enteric drainage has been the main trend in solitary pancreas transplantation. Compared with bladder drainage, it does not cause metabolic or urologic complications, but there is no way to perform immunologic monitoring, except by graft pancreas biopsy. Additionally, although portal drainage of the graft vein is considered physiological drainage, it has more of a risk for surgical complications. To overcome these disadvantages, we successfully performed inferior vena cava (IVC)-duodenal drainage in pancreas alone transplantation. A 44-year-old man underwent pancreas alone transplantation. He had insulin-dependent diabetes because of chronic pancreatitis, thus he had taken a pancreatic enzyme. After right-sided medial visceral rotation, the IVC was dissected for anastomosis with a graft portal vein. The right common iliac artery was anastomosed with a Y-graft in the pancreas graft. The graft duodenum was anastomosed with recipient duodenum using the side-to-side manner. Postoperatively, he underwent protocol biopsies of the graft duodenum through endoscopy two times. There was no evidence of graft thrombosis or rejection. He had a normal glucose level without any diabetic drugs, and he required no pancreatic enzyme for digestion. The IVC-duodenum drainage procedure was a feasible method for preventing thrombosis and providing an opportunity for direct graft monitoring through endoscopy.

Allograft biopsy findings in patients with small bowel transplantation

In this study, we sought to determine the incidence of post-transplant complications including acute cellular rejection (ACR), infection, and post-transplant lymphoproliferative disease (PTLD) in mucosal allograft biopsies in patients with small bowel transplant at our institution. We retrospectively reviewed pathology reports from 5675 small bowel allograft biopsies from 99 patients and analyzed the following: indications for biopsy, frequency and grade of ACR, the presence of infectious agents, results of workup for potential PTLD, results of C4d immunohistochemistry (IHC), features of chronic mucosal injury, and findings in concurrent native bowel biopsies. Findings from 42 allograft resection specimens were also correlated with prior biopsy findings. Indeterminate, mild, moderate, and severe ACR were seen in 276 (4.9%), 409 (7.2%), 100 (1.8%), and 207 (3.6%) of biopsies, respectively. Although ACR may show histologic overlap with mycophenolate mofetil toxicity, we found the analysis of concurrent native bowel biopsies to be helpful in this distinction. Adenovirus was the most common infectious agent seen (11%), and we routinely performed adenovirus IHC on biopsies. Eighteen patients (18%) developed PTLD, 83% of which were EBV associated, but only 28% of PTLD cases were diagnosed on mucosal allograft biopsies. C4d IHC did not correlate with the presence of donor-specific antibodies in limited cases.

Intestine and multivisceral transplantation: current status and future directions

Intestinal failure and associated parenteral nutrition-induced liver failure cause significant morbidity, mortality, and health care burden. Intestine transplantation is now considered to be the standard of care in patients with intestinal failure who fail intestinal rehabilitation. Intestinal failure-associated liver disease is an important sequela of intestinal failure, caused by parenteral lipids, requiring simultaneous liver-intestine transplant. Lipid minimization and, in recent years, the emergence of fish oil-based lipid emulsions have been shown to reverse parenteral nutrition-associated hyperbilirubinemia, but not fibrosis. Significant progress in surgical techniques and immunosuppression has led to improved outcomes after intestine transplantation. Intestine in varying combination with liver, stomach, and pancreas, also referred to as multivisceral transplantation, is performed for patients with intestinal failure along with liver disease, surgical abdominal catastrophes, neuroendocrine and slow-growing tumors, and complete portomesenteric thrombosis with cirrhosis of the liver. Although acute and chronic rejection are major problems, long-term survivors have excellent quality of life and remain free of parenteral nutrition.

Micronutrient deficiencies in pediatric and young adult intestinal transplant patients

Intestinal transplant recipients are at risk of micronutrient deficiency due to the slow process of post-transplant adaptation. Another contributing factor is calcineurin inhibitor-induced renal tubular dysfunction. Patients are typically supplemented with micronutrients during PN; however, the risk of deficiency may persist even after a successful transition to FEN. The goal was to determine the prevalence of, and associated risk factors for, iron, zinc, magnesium, phosphorus, selenium, copper, folate, and vitamins A, D, E, and B12 deficiency in pediatric intestinal transplant recipients after successful transition to FEN. A retrospective review of prospectively collected data from children who underwent intestinal transplantation at Cincinnati Children's Hospital Medical Center was done. Deficiencies of various micronutrients were defined using the hospital reference values. Twenty-one intestinal transplant recipients, aged one to 23 yr, who were successfully transitioned to FEN were included in the study. The prevalence of micronutrient deficiency was 95.2%. The common deficient micronutrients were iron (94.7%) and magnesium (90.5%). Age ≤ 10 yr (p = 0.002) and tube feeding (p = 0.02) were significant risk factors for micronutrient deficiencies. Pediatric intestinal transplant recipients have a high risk of micronutrient and mineral deficiencies. These deficiencies were more common among younger patients and those who received jejunal feeding.

Small-Bowel Allograft Biopsies in the Management of Small-Intestinal and Multivisceral Transplant Recipients: Histopathologic Review and Clinical Correlations

Context.—Intestinal transplant has become a standard treatment option in the management of patients with irreversible intestinal failure. The histologic evaluation of small-bowel allograft biopsy specimens plays a central role in assessing the integrity of the graft. It is essential for the management of acute cellular and chronic rejection; detection of infections, particularly with respect to specific viruses (cytomegalovirus, adenovirus, Epstein-Barr virus); and immunosuppression-related lymphoproliferative disease.

Objective.—To provide a comprehensive review of the literature and illustrate key histologic findings in small-bowel biopsy specimen evaluation of patients with small-bowel or multivisceral transplants.

Data Sources.—Literature review using PubMed (US National Library of Medicine) and data obtained from national and international transplant registries in addition to case material at Columbia University, Presbyterian Hospital, and Mount Sinai Medical Center, New York, New York.

Conclusions.—Key to the success of small-bowel transplantation and multivisceral transplantation are the close monitoring and appropriate clinical management of patients in the posttransplant period, requiring coordinated input from all members of the transplant team with the integration of clinical, laboratory, and histopathologic parameters.