Kidney transplant in pediatric gut transplant recipients - Technical challenges and outcomes.

BACKGROUND: There is limited data in the literature about pediatric kidney transplant (KT) following gut transplant (GT). The purpose of this study is to highlight the technical challenges and outcomes of KT in pediatric gut recipients who developed kidney failure (KF). METHODS: A retrospective single-center study of pediatric GT recipients from January 2000 to December 2019 was performed. In total, 14 (7%) out of 206 pediatric GT recipients developed KF and were listed for KT. Ten patients underwent kidney after gut transplant (KAGT), three patients underwent simultaneous kidney and re-do gut transplant (SKAGT), and one patient died on the KT waitlist. RESULTS: 1-, 5-, and 10-year kidney graft survival was 100%, 91%, and 78%, respectively. 1-, 5-, and 10-year GT graft survival was 100%, 77%, and 77%, respectively. 1-, 5-, and 10-year patient survival was 100%, 91%, and 91%, respectively. CONCLUSION: Despite the technical complexity, KAGT and SKAGT for pediatric GT recipients that develop KF can be performed with favorable outcomes.

Operational tolerance after intestine re-transplantation in childhood and immunological correlates. Case report and review.

BACKGROUND: Operational tolerance after retransplantation of the intestine has never been reported. PURPOSE: To two recently described intestine transplant recipients with operational tolerance, we now add a third. METHODS: Review of case record and immunological testing to confirm donor-specific hyporesponsiveness in multiple immune cell compartments. RESULTS: Re-transplanted with a multivisceral liver- and kidney-inclusive intestine allograft at age 12 years, this recipient self-discontinued immunosuppression 14 years after the retransplant and has been rejection free for 2 years thereafter. As in the two previous reports, immunological testing demonstrated decreased donor-specific inflammatory response of T-cytotoxic memory cells and B-cells, decreased presentation of donor antigen by B-cells and monocytes, absence of donor-specific anti-HLA antibodies, circulating FOXP3 + T-helper cells, and intact cellular and humoral immunity to cytomegalovirus and Epstein-Barr virus. Additionally, our recipient demonstrated enhanced donor-activation-induced apoptosis of alloreactive T-cytotoxic memory cells. CONCLUSIONS: Despite variable paths to tolerance which include graft versus host disease in two previous cases, and rejection-related loss of the primary isolated intestinal allograft in our recipient, the three cases with operational tolerance are bound by common themes: a relatively large donor antigenic load transmitted during intestine transplantation, and donor-specific hyporesponsiveness. Cell-based assays suggest enhanced donor-induced apoptosis of recipient T-cells and circulating T-regulatory cells as mechanistic links between antigenic load and donor-specific hyporesponsiveness.

Long-term outcomes of intestinal transplantation from donors aged under 1 year.

BACKGROUND: The aim of the study was to analyze the long-term outcomes of transplants utilizing ITx donors <1 year and to compare these results with older donors. METHODS: Between January 2007 and December 2019, the primary ITx donors in the Children's Hospital of Pittsburgh of UPMC were retrospectively reviewed. Short- and long-term outcomes of recipients receiving a deceased donor organ from donors <1 year were compared with those found in all other recipients. RESULTS: During the study period, there were 89 primary ITx donors, using 30 donors (33.7%) aged <1 year. The mean age of their recipients was 1.6 ± 0.7 (0.7-3.2) years. The 30 graft types were isolated intestine (n = 3, 10.0%), liver bowel (n = 20, 66.7%), and multivisceral (n = 7, 23.3%). Technical complications occurred in 12 (40.0%) recipients. Candidates transplanted with intestine allografts from donors <1 year of age had shorter wait times (p < .001), more liver-inclusive grafts (p < .001), and less donor-specific antibodies (DSA) (p = .014). During follow-up, the recipients had less graft loss (p = .018), and more remained alive with graft in place (p = .011). Among children transplanted with such donors, 3-year and graft survival rates were 86.7% and 82.9% compared to 62.8% and 49.9% in the cohort of donors >1 year (p = .032 and .011). CONCLUSIONS: Donor age <1 year was associated with improved graft survival. Optimal utilization of this population for toddler candidates would increase intestine availability, reduce time to transplantation, and potentially improve long-term outcome.

Five Hundred Patients With Gut Malrotation: Thirty Years of Experience With the Introduction of a New Surgical Procedure.

OBJECTIVES: Define clinical spectrum and long-term outcomes of gut malrotation. With new insights, an innovative procedure was introduced and predictive models were established. METHODS: Over 30-years, 500 patients were managed at 2 institutions. Of these, 274 (55%) were children at time of diagnosis. At referral, 204 (41%) patients suffered midgut-loss and the remaining 296 (59%) had intact gut with a wide range of digestive symptoms. With midgut-loss, 189 (93%) patients underwent surgery with gut transplantation in 174 (92%) including 16 of 31 (16%) who had autologous gut reconstruction. Ladd's procedure was documented in 192 (38%) patients with recurrent or de novo volvulus in 41 (21%). For 80 patients with disabling gastrointestinal symptoms, gut malrotation correction (GMC) surgery "Kareem's procedure" was offered with completion of the 270° embryonic counterclockwise-rotation, reversal of vascular-inversion, and fixation of mesenteric-attachments. Concomitant colonic dysmotility was observed in 25 (31%) patients. RESULTS: The cumulative risk of midgut-loss increased with volvulus, prematurity, gastroschisis, and intestinal atresia whereas reduced with Ladd's and increasing age. Transplant cumulative survival was 63% at 10-years and 54% at 20-years with best outcome among infants and liver-containing allografts. Autologous gut reconstruction achieved 78% and GMC had 100% 10-year survival. Ladd's was associated with 21% recurrent/de novo volvulus and worsening (P > 0.05) of the preoperative National Institute of Health patient-reported outcomes measurement information system gastrointestinal symptom scales. GMC significantly (P ≤ 0.001) improved all of the symptomatology domains with no technical complications or development of volvulus. GMC improved quality of life with restored nutritional autonomy (P < 0.0001) and daily activities (P < 0.0001). CONCLUSIONS: Gut malrotation is a clinicopathologic syndrome affecting all ages. The introduced herein definitive correction procedure is safe, effective, and easy to perform. Accordingly, the current standard of care practice should be redefined in this orphan population.

Metabolic Control and "Ideal" Outcomes in Liver Transplantation for Maple Syrup Urine Disease.

OBJECTIVES: To assess outcomes following liver transplantation for maple syrup urine disease by determining attainment and sustainability of metabolic control and apply an "ideal" outcome composite in long-term survivors. STUDY DESIGN: A single center, retrospective review collected clinical data including branched-chain amino acid (leucine, isoleucine, and valine) levels following liver transplant and determined achievement of an ideal long-term outcome profile of a first allograft stable on immunosuppression monotherapy, normal growth, and absence of common transplant-related sequelae. RESULTS: Of 77 patients meeting inclusion criteria identified, 23 were long-term (≥10-year) survivors and were additionally assessed for ideal outcome attainment. Patient and graft survival were 100% and 99%, respectively, and all patients were on an unrestricted protein intake diet. Although significant variation was noted in mean isoleucine (P < .01) and leucine (P < .05) levels postliver transplantation, no difference was seen in valine (P = .29) and overall clinical impact was likely negligible as metabolic stability was achieved and sustained beyond 3 years postliver transplantation and no metabolic crises were identified. Of 23 long-term survivors with available data, 9 (39%) achieved all composite metrics determined to define "ideal" outcomes in pediatric postliver transplantation populations. CONCLUSIONS: Liver transplant enables long-term metabolic stability for patients with maple syrup urine disease. A combination of experience and improvement in both pre- and postliver transplantation care has enabled excellent survival and minimal comorbidities following transplant.

Liver transplant for inherited metabolic disease among siblings.

Liver transplantation is a successful option for inherited metabolic disease yet little is published on the outcome among siblings. We report outcomes of siblings who have undergone liver transplantation for metabolic disease in a single program. Seventy-one siblings (35 males) from 33 individual families underwent liver transplantation since 1982. Outcomes were compared over three consecutive eras. Twenty-eight families had two siblings, four had three siblings, and one had four siblings. In half of families where dates of listing were known, siblings were listed simultaneously. Mean (SD) age at listing for the oldest and second sibling was 13.2 (7.1) and 9.8 (5.7) years, respectively (p < .01). In 18/33 families, the oldest sibling underwent transplantation first. Mean (SD) age at transplant fell from the oldest to second sibling from 12.9 (7.2) to 9.5 (6.3) years, respectively (p < .001). Ten-year patient survival was 83.5% which improved over the eras: era 1 (1982-1994) 65.0%, era 2 (1995-2007) 87.5%, and era 3 (2008-2019) 93.8%: p < .03. Sex, age at transplant, order of transplant, and presence of structural liver disease did not significantly impact survival. When siblings undergo liver transplant for inherited metabolic disease, later siblings are listed and transplanted at a significantly younger age.

CD154-expressing CMV-specific T cells associate with freedom from DNAemia and may be protective in seronegative recipients after liver or intestine transplantation.

Cell-mediated immunity to CMV, if known, could improve antiviral drug therapy in at-risk children and young adults with LT and IT. Host immunity has been measured with CMV-specific T cells, which express IFNγ, but not those which express CD154, a possible substitute for IFNγ. CMV-specific CD154+ T cells and their subsets were measured with flow cytometry after stimulating PBL from recipient blood samples with an overlapping peptide mix of CMV-pp65 antigen for up to 6 hours. CMV-specific CD154+ T cells co-expressed IFNγ in PBL from three healthy adults and averaged 3.8% (95% CI 3.2%-4.4%) in 40 healthy adults. CMV-specific T cells were significantly lower in 19 CMV DNAemic LT or IT recipients, compared with 126 non-DNAemic recipients, 1.3% (95% CI 0.8-1.7) vs 4.1 (95% CI 3.6-4.6, P < .001). All T-cell subsets demonstrated similar between-group differences. In logistic regression analysis of 46 training set samples, 12 with DNAemia, all obtained between days 0 and 60 from transplant, CMV-specific T-cell frequencies ≥1.7% predicted freedom from DNAemia with NPV of 93%. Sensitivity, specificity, and PPV were 83%, 74%, and 53%, respectively. Test performance was replicated in 99 validation samples. In 32 of 46 training set samples, all from seronegative recipients, one of 19 recipients with CMV-specific T-cell frequencies ≥1.7% experienced DNAemia, compared with 8 of 13 recipients with frequencies <1.7% (P = .001). CMV-specific CD154+ T cells are associated with freedom from DNAemia after LT and IT. Among seronegative recipients, CMV-specific T cells may protect against the development of CMV DNAemia.

Management of Five Hundred Patients With Gut Failure at a Single Center: Surgical Innovation Versus Transplantation With a Novel Predictive Model.

OBJECTIVE(S): To define the evolving role of integrative surgical management including transplantation for patients gut failure (GF). METHODS: A total of 500 patients with total parenteral nutrition-dependent catastrophic and chronic GF were referred for surgical intervention particularly transplantation and comprised the study population. With a mean age of 45 ±â€Š17 years, 477 (95%) were adults and 23 (5%) were children. Management strategy was guided by clinical status, splanchnic organ functions, anatomy of residual gut, and cause of GF. Surgery was performed in 462 (92%) patients and 38 (8%) continued medical treatment. Definitive autologous gut reconstruction (AGR) was achievable in 378 (82%), primary transplant in 42 (9%), and AGR followed by transplant in 42 (9%). The 84 transplant recipients received 94 allografts; 67 (71%) liver-free and 27 (29%) liver-contained. The 420 AGR patients received a total of 790 reconstructive and remodeling procedures including primary reconstruction, interposition alimentary-conduits, intestinal/colonic lengthening, and reductive/decompressive surgery. Glucagon-like peptide-2 was used in 17 patients. RESULTS: Overall patient survival was 86% at 1-year and 68% at 5-years with restored nutritional autonomy (RNA) in 63% and 78%, respectively. Surgery achieved a 5-year survival of 70% with 82% RNA. AGR achieved better long-term survival and transplantation better (P = 0.03) re-established nutritional autonomy. Both AGR and transplant were cost effective and quality of life better improved after AGR. A model to predict RNA after AGR was developed computing anatomy of reconstructed gut, total parenteral nutrition requirements, cause of GF, and serum bilirubin. CONCLUSIONS: Surgical integration is an effective management strategy for GF. Further progress is foreseen with the herein-described novel techniques and established RNA predictive model.

Technique and outcome of domino liver transplantation from patients with maple syrup urine disease: Expanding the donor pool for live donor liver transplantation.

AIM/BACKGROUND: Domino liver transplantation (DLT) using liver allografts from patients with metabolic disorders enhances organ utilization. Short- and long-term course and outcome of these patients can impact the decision to offer this procedure to patients, especially those with diseases that can potentially be cured with liver transplant. We reviewed the outcomes of DLT from maple syrup urine disease (MSUD) patients in our large academic pediatric and adult transplant program. METHODS: All patients receiving DLT were analyzed retrospectively with a minimum of one-year follow-up period for patient and donor characteristics, early and late postoperative complications and patient and graft survival with their MSUD donors in terms of age, weight, MELD/PELD scores, cold ischemia time, postoperative leucine levels, and peak ALT (alanine aminotransferase) levels during the first 48 postoperative hours. RESULTS: Between 2006 and May 2019, 21 patients underwent domino liver transplantation with live donor allografts from MSUD patients. Four patients transplanted for different metabolic diseases are focus of a separate report. Seventeen patients with minimum one-year follow-up period are reported herein. The indications were primary sclerosing cholangitis (PSC, n = 4), congenital hepatic fibrosis (CHF, n = 2), alpha-1 antitrypsin deficiency (A-1 ATD, n = 2), progressive familial intrahepatic cholestasis (PFIC, n = 2), cystic fibrosis (n = 1), primary biliary cirrhosis (PBC, n = 1), neonatal hepatitis (n = 1), embryonal sarcoma (n = 1), Caroli disease (n = 1), hepatocellular carcinoma (HCC, n = 1), and chronic rejection after liver transplantations for PSC (n = 1). All patients and grafts survived at median follow-up of 6.4 years (range 1.2-12.9 years). Median domino recipient age was 16.2 years (range 0.6-64.6 years) and median MSUD recipient age was 17.6 years (range 4.8-32.1 years). There were no vascular complications during the early postoperative period, one patient had portal vein thrombosis 3 years after DLT and a meso-Rex bypass was successfully performed. Small for size syndrome (SFSS) occurred in reduced left lobe DLT recipient and was managed successfully with conservative management. Biliary stricture developed in 2 patients and was resolved by stenting. Comparison between DLT and MSUD recipients' peak postoperative ALT results and PELD/MELD scores showed lower levels in DLT group (P-value <.05). CONCLUSIONS: Patient and graft survival in DLT from MSUD donors was excellent at short- and long-term follow-up. Metabolic functions have been normal in all recipients on a normal unrestricted protein diet. Ischemia preservation injury based on peak ALT was significantly decreased in DLT recipients. Domino transplantation from pediatric and adult recipients with selected metabolic diseases should be increasingly considered as an excellent option and alternative to deceased donor transplantation, thereby expanding the living donor pool. This, to date, is the largest world experience in DLT utilizing livers from patients with MSUD.

Current status of graft-versus-host disease after intestinal transplantation.

PURPOSE OF REVIEW: Over the past decades, visceral transplantation has become the standard of care for patients with irreversible intestinal failure who suffer complications of total parenteral nutrition (TPN). Graft-versus-host disease (GVHD) after solid organ transplantation is a rare but often fatal complication with high mortality. GVHD after intestinal transplantation, given the large lymphoid content of the graft, is more frequent compared with other solid organs. It is a complex condition that may have varied clinical presentations. The therapy of GVHD is multifactorial and has evolved with visceral transplantation. RECENT FINDINGS: In recent large series of intestinal transplantation performed in centers around the world, GVHD remained an important cause of death (40-70%). Advances in immunology and current treatment options come from the hematopoietic stem-cell transplantation (HSCT) experience given the high prevalence of GVHD in that patient population. Therapeutic options for GVHD are based on disease classification, overall grading, organs involved, and associated symptoms. SUMMARY: Graft-versus-host disease (GVHD) is a serious complication that can occur after solid organ and allogenic HSCT. Intestinal or multivisceral transplantation have the highest incidence of GVHD among all solid organ transplants with very high mortality rates. Increased risk of GVHD is present after multivisceral and liver-included transplants compared with isolated intestinal transplant. Visceral transplantation is the all-encompassing term used for transplant that includes small bowel. It includes isolated small bowel transplant, small bowel/pancreas transplant, liver/small bowel/ pancreas transplant, stomach/pancreas/small bowel (modified multivisceral transplant), and stomach/liver/pancreas/small bowel (multivisceral). Each of these may or may not include the colon as part of the allograft. Steroids remain the first line of treatment along with modulation of the primary immunosuppression. Steroid-refractory patients remain a challenge and, to date, no consensus has been achieved for a single agent second-line therapy. Successful outcome depends on early diagnosis and prompt treatment.

Myeloid-derived suppressor cells increase and inhibit donor-reactive T cell responses to graft intestinal epithelium in intestinal transplant patients.

Recent advances in immunosuppressive regimens have decreased acute cellular rejection (ACR) rates and improved intestinal and multivisceral transplant (ITx) recipient survival. We investigated the role of myeloid-derived suppressor cells (MDSCs) in ITx. We identified MDSCs as CD33+ CD11b+ lineage(CD3/CD56/CD19)- HLA-DR-/low cells with 3 subsets, CD14- CD15- (e-MDSCs), CD14+ CD15- (M-MDSCs), and CD14- CD15+ (PMN-MDSCs), in peripheral blood mononuclear cells (PBMCs) and mononuclear cells in the grafted intestinal mucosa. Total MDSC numbers increased in PBMCs after ITx; among MDSC subsets, M-MDSC numbers were maintained at a high level after 2 months post ITx. The MDSC numbers decreased in ITx recipients with ACR. MDSC numbers were positively correlated with serum interleukin (IL)-6 levels and the glucocorticoid administration index. IL-6 and methylprednisolone enhanced the differentiation of bone marrow cells to MDSCs in vitro. M-MDSCs and e-MDSCs expressed CCR1, -2, and -3; e-MDSCs and PMN-MDSCs expressed CXCR2; and intestinal grafts expressed the corresponding chemokine ligands after ITx. Of note, the percentage of MDSCs among intestinal mucosal CD45+ cells increased after ITx. A novel in vitro assay demonstrated that MDSCs suppressed donor-reactive T cell-mediated destruction of donor intestinal epithelial organoids. Taken together, our results suggest that MDSCs accumulate in the recipient PBMCs and the grafted intestinal mucosa in ITx, and may regulate ACR.

Generation of multiciliated cells in functional airway epithelia from human induced pluripotent stem cells.

Despite therapeutic advancement, pulmonary disease still remains a major cause of morbidity and mortality around the world. Opportunities to study human lung disease either in vivo or in vitro are currently limited. Using induced pluripotent stem cells (iPSCs), we generated mature multiciliated cells in a functional airway epithelium. Robust multiciliogenesis occurred when notch signaling was inhibited and was confirmed by (i) the assembly of multiple pericentrin-stained centrioles at the apical surface, (ii) expression of transcription factor forkhead box protein J1, and (iii) presence of multiple acetylated tubulin-labeled cilia projections in individual cells. Clara, goblet, and basal cells were all present, confirming the generation of a complete polarized epithelial-cell layer. Additionally, cAMP-activated and cystic fibrosis transmembrane regulator inhibitor 172-sensitive cystic fibrosis transmembrane regulator currents were recorded in isolated epithelial cells. Our report demonstrating the generation of mature multiciliated cells in respiratory epithelium from iPSCs is a significant advance toward modeling a number of human respiratory diseases in vitro.

Autologous Reconstruction and Visceral Transplantation for Management of Patients With Gut Failure After Bariatric Surgery: 20 Years of Experience.

OBJECTIVE: Bariatric surgery (BS) is currently the most effective treatment for severe obesity. However, these weight loss procedures may result in the development of gut failure (GF) with the need for total parenteral nutrition (TPN). This retrospective study is the first to address the anatomic and functional spectrum of BS-associated GF with innovative surgical modalities to restore gut function. METHODS: Over 2 decades, 1500 adults with GF were referred with history of BS in 142 (9%). Of these, 131 (92%) were evaluated and received multidisciplinary care. GF was due to catastrophic gut loss (Type-I, 42%), technical complications (Type-II, 33%), and dysfunctional syndromes (Type-III, 25%). Primary bariatric procedures were malabsorptive (5%), restrictive (19%), and combined (76%). TPN duration ranged from 2 to 252 months. RESULTS: Restorative surgery was performed in 116 (89%) patients with utilization of visceral transplantation as a rescue therapy in 23 (20%). With a total of 317 surgical procedures, 198 (62%) were autologous reconstructions; 88 (44%) foregut, 100 (51%) midgut, and 10 (5%) hindgut. An interposition alimentary conduit was used in 7 (6%) patients. Reversal of BS was indicated in 84 (72%) and intestinal lengthening was required in 10 (9%). Cumulative patient survival was 96% at 1 year, 84% at 5 years, and 72% at 15 years. Nutritional autonomy was restored in 83% of current survivors with persistence or relapse of obesity in 23%. CONCLUSIONS: GF is a rare but serious life-threatening complication after BS. Successful outcome is achievable with comprehensive management, including reconstructive surgery and visceral transplantation.

Enhanced Donor Antigen Presentation by B Cells Predicts Acute Cellular Rejection and Late Outcomes After Transplantation.

Background: Enhanced B-cell presentation of donor alloantigen relative to presentation of HLA-mismatched reference alloantigen is associated with acute cellular rejection (ACR), when expressed as a ratio called the antigen presenting index (API) in an exploratory cohort of liver and intestine transplant (LT and IT) recipients. Methods: To test clinical performance, we measured the API using the previously described 6-h assay in 84 LT and 54 IT recipients with median age 3.3 y (0.05-23.96). Recipients experiencing ACR within 60 d after testing were termed rejectors. Results: We first confirmed that B-cell uptake and presentation of alloantigen induced and thus reflected the alloresponse of T-helper cells, which were incubated without and with cytochalasin and primaquine to inhibit antigen uptake and presentation, respectively. Transplant recipients included 76 males and 62 females. Rejectors were tested at median 3.6 d before diagnosis. The API was higher among rejectors compared with nonrejectors (2.2 ±â€…0.2 versus 0.6 ±â€…0.04, P value = 1.7E-09). In logistic regression and receiver-operating-characteristic analysis, API ≥1.1 achieved sensitivity, specificity, and positive and negative predictive values for predicting ACR in 99 training set samples. Corresponding metrics ranged from 80% to 88% in 32 independent posttransplant samples, and 73% to 100% in 20 independent pretransplant samples. In time-to-event analysis, API ≥1.1 predicted higher incidence of late donor-specific anti-HLA antibodies after API measurements in LT recipients (P = 0.011) and graft loss in IT recipients (P = 0.008), compared with recipients with API <1.1, respectively. Conclusions: Enhanced donor antigen presentation by circulating B cells predicts rejection after liver or intestine transplantation as well as higher incidence of DSA and graft loss late after transplantation.

The First Collective Examination of Immunosuppressive Practices Among American Intestinal Transplant Centers.

Background: Unlike other solid organs, no standardized treatment algorithms exist for intestinal transplantation (ITx). We established a consortium of American ITx centers to evaluate current practices. Methods: All American centers performing ITx during the past 3 y were invited to participate. As a consortium, we generated questions to evaluate and collect data from each institution. The data were compiled and analyzed. Results: Ten centers participated, performing 211 ITx during the past 3 y (range, 3-46; mean 21.1). Induction regimens varied widely. Thymoglobulin was the most common, used in the plurality of patients (85/211; 40.3%), but there was no consensus regimen. Similarly, regimens for the treatment of acute cellular rejection, antibody-mediated rejection, and graft-versus-host disease varied significantly between centers. We also evaluated differences in maintenance immunosuppression protocols, desensitization regimens, mammalian target of rapamycin use, antimetabolite use, and posttransplantation surveillance practices. Maintenance tacrolimus levels, stoma presence, and scoping frequency were not associated with differences in rejection events. Definitive association between treatments and outcomes, including graft and patient survival, was not the intention of this initial collaboration and is prevented by the lack of patient-level data and the presence of confounders. However, we identified trends regarding rejection episodes after various induction strategies that require further investigation in our subsequent collaborations. Conclusions: This initial collaboration reveals the extreme heterogeneity of practices among American ITx centers. Future collaboration will explore patient-level data, stratified by age and transplant type (isolated intestine versus multivisceral), to explore the association between treatment regimens and outcomes.

Impaired Cellular and Antibody immunity after COVID-19 in Chronically Immunosuppressed Transplant Recipients.

Assessment of cellular immunity to the SARS-CoV-2 coronavirus is of great interest in chronically immunosuppressed transplant recipients (Tr), who are predisposed to infections and vaccination failures. We evaluated CD154-expressing T-cells induced by spike (S) antigenic peptides in 204 subjects-103 COVID-19 patients and 101 healthy unexposed subjects. S-reactive CD154+T-cell frequencies were a) higher in 42 healthy unexposed Tr who were sampled pre-pandemic, compared with healthy NT (p=0.02), b) lower in Tr COVID-19 patients compared with healthy Tr (p<0.0001) and were accompanied by lower S-reactive B-cell frequencies (p<0.05), c) lower in Tr with severe COVID-19 (p<0.0001), or COVID-19 requiring hospitalization (p<0.05), compared with healthy Tr. Among Tr with COVID-19, cytomegalovirus co-infection occurred in 34%; further, incidence of anti-receptor-binding-domain IgG (p=0.011) was lower compared with NT COVID-19 patients. Healthy unexposed Tr exhibit pre-existing T-cell immunity to SARS-CoV-2. COVID-19 impairs anti-S T-cell and antibody and predisposes to CMV co-infection in transplant recipients.

Systems biology approach to transplant tolerance: proof of concept experiments using RNA interference (RNAi) to knock down hub genes in Jurkat and HeLa cells in vitro.

BACKGROUND: Systems biology is gaining importance in studying complex systems such as the functional interconnections of human genes [1]. To investigate the molecular interactions involved in T cell immune responses, we used databases of physical gene-gene interactions to constructed molecular interaction networks (interconnections) with R language algorithms. This helped to identify highly interconnected "hub" genes AT(1)P5C1, IL6ST, PRKCZ, MYC, FOS, JUN, and MAPK1. We hypothesized that suppression of these hub genes in the gene network would result in significant phenotypic effects on T cells and examined this in vitro. The molecular interaction networks were then analyzed and visualized with Cytoscape. MATERIALS AND METHODS: Jurkat and HeLa cells were transfected with siRNA for the selected hub genes. Cell proliferation was measured using ATP luminescence and BrdU labeling, which were measured 36, 72, and 96 h after activation. RESULTS: Following T cell stimulation, we found a significant decrease in ATP production (P < 0.05) when the hub genes ATP5C1 and PRKCZ were knocked down using siRNA transfection, whereas no difference in ATP production was observed in siRNA transfected HeLa cells. However, HeLa cells showed a significant (P < 0.05) decrease in cell proliferation when the genes MAPK1, IL6ST, ATP5C1, JUN, and FOS were knocked down. CONCLUSION: In both Jurkat and HeLa cells, targeted gene knockdown using siRNA showed decreased cell proliferation and ATP production in both Jurkat and HeLa cells. However, Jurkat T cells and HELA cells use different hub genes to regulate activation responses. This experiment provides proof of principle of applying siRNA knockdown of T cell hub genes to evaluate their proliferative capacity and ATP production. This novel concept outlines a systems biology approach to identify hub genes for targeted therapeutics.

Impaired T-cell and antibody immunity after COVID-19 infection in chronically immunosuppressed transplant recipients.

Assessment of T-cell immunity to the COVID-19 coronavirus requires reliable assays and is of great interest, given the uncertain longevity of the antibody response. Some recent reports have used immunodominant spike (S) antigenic peptides and anti-CD28 co-stimulation in varying combinations to assess T-cell immunity to SARS-CoV-2. These assays may cause T-cell hyperstimulation and could overestimate antiviral immunity in chronically immunosuppressed transplant recipients, who are predisposed to infections and vaccination failures. Here, we evaluate CD154-expressing T-cells induced by unselected S antigenic peptides in 204 subjects-103 COVID-19 patients and 101 healthy unexposed subjects. Subjects included 72 transplanted and 130 non-transplanted subjects. S-reactive CD154+T-cells co-express and can thus substitute for IFNγ (n=3). Assay reproducibility in a variety of conditions was acceptable with coefficient of variation of 2-10.6%. S-reactive CD154+T-cell frequencies were a) higher in 42 healthy unexposed transplant recipients who were sampled pre-pandemic, compared with 59 healthy non-transplanted subjects (p=0.02), b) lower in Tr COVID-19 patients compared with healthy transplant patients (p<0.0001), c) lower in Tr patients with severe COVID-19 (p<0.0001), or COVID-19 requiring hospitalization (p<0.05), compared with healthy Tr recipients. S-reactive T-cells were not significantly different between the various COVID-19 disease categories in NT recipients. Among transplant recipients with COVID-19, cytomegalovirus co-infection occurred in 34%; further, CMV-specific T-cells (p<0.001) and incidence of anti-receptor-binding-domain IgG (p=0.011) were lower compared with non-transplanted COVID-19 patients. Healthy unexposed transplant recipients exhibit pre-existing T-cell immunity to SARS-CoV-2. COVID-19 infection leads to impaired T-cell and antibody responses to SARS-CoV-2 and increased risk of CMV co-infection in transplant recipients.

Domino liver transplantation for select metabolic disorders: Expanding the living donor pool.

Domino liver transplantation (DLT) involves transplanting liver from a patient with metabolic disease into a patient with end-stage liver disease with the expectation that the recipient will not develop the metabolic syndrome or the recurrent syndrome will have minimal affect. The domino donor gets a deceased donor or a segment of live-donor liver through the deceased donor organ allocation system. Waitlist mortality for the domino recipient exceeds morbidity associated with getting the donor disease. Between 2015 and 2017, four patients with three metabolic disorders at UPMC Children's Hospital of Pittsburgh underwent DLT with domino allografts from maple syrup urine disease (MSUD) patients. These included patients with propionic acidemia (PA) (n = 1), Crigler-Najjar (CN) syndrome type-1 (n = 2), and carbamoyl phosphate synthetase deficiency (CPSD) (n = 1). Mean follow-up was 1.6 years (range 1.1-2.1 years). Total bilirubin levels normalized postoperatively in both CN patients and they maintain normal allograft function. The PA patient had normal to minimal elevations of isoleucine and leucine, and no other abnormalities on low protein diet supplemented with a low methionine and valine free formula. No metabolic crises have occurred. The patient with CPSD takes normal baby food. No elevation in ammonia levels have been observed in any of the patients. DLT for a select group of metabolic diseases alleviated the recipients of their metabolic defect with minimal evidence of transferrable-branched chain amino acid elevations or clinical MSUD despite increased protein intake. DLT using allografts with MSUD expands the live donor liver pool and should be considered for select metabolic diseases that may have a different enzymatic deficiency.

Improvements in intestine transplantation.

Transplantation of the intestine in children has presented significant challenges even as it has become a standard to treat nutritional failure due to short gut syndrome. These challenges have been addressed in part by significant improvements in short and long-term care. Noteworthy enhancements include reduced need for intestine transplantation, drug-sparing immunosuppressive regimens, immune monitoring, and improved surveillance and management of PTLD and non-adherence.