Minimal Immunosuppression Research Articles

Immunosuppression Minimization In Kidney Transplant Recipients with Transplant Excellence Based on the TruGraf Test

Immunosuppression Minimization In Kidney Transplant Recipients with Transplant Excellence Based on the TruGraf Test

The current state of tolerance induction in vascularized composite allotransplantation.

Significant advancements have been made in the field of vascularized composite allotransplantation (VCA); however, like solid organ transplantation, bypassing the recipient's immune response remains a significant obstacle to long-term allograft survival. Therefore, strategies to overcome acute and chronic rejection and minimize immunosuppressive therapy are crucial for the future of VCA. This review highlights recent attempts to induce tolerance in VCA and discusses key findings through a clinical lens. Promising VCA tolerance protocols are being investigated, with five recent studies illustrating various successes. These preclinical approaches demonstrate a correlation between the presence of donor-derived T cells and VCA tolerance, the importance of using clinically available reagents within preclinical protocols, and the ability to induce sustained tolerance through nonmyeloablative methods. Furthermore, environmental factors, such as NB-UVB light are being investigated for their immunomodulation properties and may influence VCA graft rejection. To widen the scope of VCA, minimization of immunosuppression is needed. Overall, tolerance induction protocols should have a low-toxicity level, minimally invasive induction therapies, and utilize short-term immunosuppressive medications. By examining the milestones of recent studies, researchers can gain new technical approaches to immune modulation and make data-driven amendments to tolerance protocols in preparation for clinical translation.

Human leukocyte antigen compatibility and incidence of donor-specific antibodies in pediatric liver transplant recipients.

Antibody-mediated rejection following liver transplantation (LT) has been increasingly recognized, particularly with respect to the emergence of de novo donor-specific antibodies (DSAs) and their impact on graft longevity. While substantial evidence for adult populations exists, research focusing on pediatric LT outcomes remains limited. To investigate the prevalence of human leukocyte antigen (HLA) mismatches and DSA and evaluate their association with rejection episodes after pediatric LT. A cohort of pediatric LT recipients underwent HLA testing at Santa Casa de Porto Alegre, Brazil, between December 2013 and December 2023. Only patients who survived for > 30 days after LT with at least one DSA analysis were included. DSA classes I and II and cross-matches were analyzed. The presence of de novo DSA (dnDSA) was evaluated at least 3 months after LT using the Luminex® single antigen bead method, with a positive reaction threshold set at 1000 MFI. Rejection episodes were confirmed by liver biopsy. Overall, 67 transplanted children were analyzed; 61 received grafts from living donors, 85% of whom were related to recipients. Pre-transplant DSA (class I or II) was detected in 28.3% of patients, and dnDSA was detected in 48.4%. The median time to DSA detection after LT was 19.7 [interquartile range (IQR): 4.3-35.6] months. Biopsy-proven rejection occurred in 13 patients at follow-up, with C4d positivity observed in 5/13 Liver biopsies. The median time to rejection was 7.8 (IQR: 5.7-12.8) months. The presence of dnDSA was significantly associated with rejection (36% vs 3%, P < 0.001). The rejection-free survival rates at 12 and 24 months were 76% vs 100% and 58% vs 95% for patients with dnDSA anti-DQ vs those without, respectively. Our findings highlight the importance of incorporating DSA assessment into pre- and post-transplantation protocols for pediatric LT recipients. Future implications may include immunosuppression minimization strategies based on this analysis in pediatric LT recipients.

Epstein-Barr Virus-Associated Smooth Muscle Tumor After Kidney Transplantation: A French Multicenter Retrospective Study.

Epstein-Barr virus (EBV) is a herpesvirus linked to nine different human tumors and lymphoproliferative disorders. Immunosuppression promotes EBV-driven malignancies. The most frequent EBV-induced malignancies are lymphomas and nasopharyngeal carcinoma. By promoting smooth muscle proliferation, EBV can induce EBV-associated smooth muscle tumors (EBV-SMT). EBV-SMT is a rare oncological entity for which no current guideline for diagnosis or management exists. Data on posttransplant EBV-SMT (PT-SMT) are scarce in kidney transplant recipients. We conducted a national multicentric retrospective study and collected cases among transplantation centers in France. Kidney transplant recipients experiencing histologically proven PT-SMT were included. We collected data on demographic characteristics of patient, history of kidney transplantation, history of PT-SMT, evolution of graft function, and patient survival. Eight patients were included. The median age at PT-SMT diagnosis was 31 years (range 6.5-40). PT-SMT occurred after a median delay of 37.8 months after transplantation (range 6-175). PT-SMT management consisted in immunosuppressive regimen minimization in all patients. Introduction of mTOR inhibitors was performed in two patients. Four patients (50%) needed chemotherapy. Surgical resection was performed in four patients. At last follow-up after PT-SMT diagnosis (median 33 months (range 17-132)), five patients were considered in complete remission, and two patients had died. Two patients experienced graft rejection; two resumed dialysis (25%). All patients with available data presented with impaired graft function at last follow-up. PT-SMT is a subacute and progressive disease during kidney transplantation. Even if the risk of developing PT-SMT is low in kidney transplant recipients (0.07% in our cohort), PT-SMT is associated with significant graft loss, possibly due to reduced immunosuppression. Developing guidelines could help transplantation teams better manage these patients.

Late Treatment With Autologous Expanded Regulatory T-cell Therapy After Alemtuzumab Induction Is Safe and Facilitates Immunosuppression Minimization in Living Donor Renal Transplantation.

The TWO Study (Transplantation Without Overimmunosuppression) aimed to investigate a novel approach to regulatory T-cell (Treg) therapy in renal transplant patients, using a delayed infusion protocol at 6 mo posttransplant to promote a Treg-skewed lymphocyte repopulation after alemtuzumab induction. We hypothesized that this would allow safe weaning of immunosuppression to tacrolimus alone. The COVID-19 pandemic led to the suspension of alemtuzumab use, and therefore, we report the unique cohort of 7 patients who underwent the original randomized controlled trial protocol. This study presents a unique insight into Treg therapy combined with alemtuzumab and is therefore an important proof of concept for studies in other diseases that are considering lymphodepletion. Living donor kidney transplant recipients were randomized to receive autologous polyclonal Treg at week 26 posttransplantation, coupled with weaning doses of tacrolimus, (Treg therapy arm) or standard immunosuppression alone (tacrolimus and mycophenolate mofetil). Primary outcomes were patient survival and rejection-free survival. Successful cell manufacturing and cryopreservation until the 6-mo infusion were achieved. Patient and transplant survival was 100%. Acute rejection-free survival was 100% in the Treg-treated group at 18 mo after transplantation. Although alemtuzumab caused a profound depletion of all lymphocytes, including Treg, after cell therapy infusion, there was a transient increase in peripheral Treg numbers. The study establishes that delayed autologous Treg therapy is both feasible and safe, even 12 mo after cell production. The findings present a new treatment protocol for Treg therapy, potentially expanding its applications to other indications.

The Effects of Sustained Immunosuppression Withdrawal After Liver Transplantation on Metabolic Syndrome.

Liver transplant (LT) recipients often experience adverse effects of immunosuppressive (IS) drugs, especially on metabolic profiles. Selected LT recipients can achieve successful IS withdrawal; however, its effects on metabolic syndrome (MS) are unknown. This is a retrospective single-center study investigating the incidence and/or regression of MS in 75 selected LT recipients who were previously enrolled in prospective IS withdrawal trials between 1999 and 2017. Patients who were transplanted due to nonalcoholic steatohepatitis/metabolic-associated fatty liver disease were excluded, as well as those with a follow-up <3 y after IS weaning. Forty-four patients (58.7%) achieved sustained withdrawal or minimization of immunosuppression (WMIS) and 31 patients (41.3%) required reintroduction of immunosuppression (no-WMIS). Among LT recipients who were metabolically healthy (n = 52, 69.3%) before the start of IS weaning, there was a significantly lower rate of de novo MS in WMIS patients compared with no-WMIS patients after 5 y (8.3% and 47.8%, respectively, P = 0.034). Of 23 LT recipients (30.7%) who had MS at the time of commencing IS withdrawal, complete regression of MS was observed in 47.1% of WMIS patients and in none (0%) of the no-WMIS patients after 5 y (P = 0.054). Furthermore, individual components of MS were better controlled in IS-weaned patients, such as arterial hypertension and abnormal serum lipids. Achievement of sustained IS withdrawal reduces the incidence of de novo MS development in metabolically healthy patients and increases the likelihood of MS regression in patients with established MS. The foreseeable long-term beneficial effects of these favorable metabolic changes on morbidity and mortality of LT recipients require further investigation.

A humanized IL-2 mutein expands Tregs and prolongs transplant survival in preclinical models.

Long-term organ transplant survival remains suboptimal, and life-long immunosuppression predisposes transplant recipients to an increased risk of infection, malignancy, and kidney toxicity. Promoting the regulatory arm of the immune system by expanding Tregs may allow immunosuppression minimization and improve long-term graft outcomes. While low-dose IL-2 treatment can expand Tregs, it has a short half-life and off-target expansion of NK and effector T cells, limiting its clinical applicability. Here, we designed a humanized mutein IL-2 with high Treg selectivity and a prolonged half-life due to the fusion of an Fc domain, which we termed mIL-2. We showed selective and sustainable Treg expansion by mIL-2 in 2 murine models of skin transplantation. This expansion led to donor-specific tolerance through robust increases in polyclonal and antigen-specific Tregs, along with enhanced Treg-suppressive function. We also showed that Treg expansion by mIL-2 could overcome the failure of calcineurin inhibitors or costimulation blockade to prolong the survival of major-mismatched skin grafts. Validating its translational potential, mIL-2 induced a selective and sustainable in vivo Treg expansion in cynomolgus monkeys and showed selectivity for human Tregs in vitro and in a humanized mouse model. This work demonstrated that mIL-2 can enhance immune regulation and promote long-term allograft survival, potentially minimizing immunosuppression.

Elevated Plasma CXCL8 Concentrations in Significant Fibrosis but Not in Subclinical Rejection After Adult Liver Transplantation

Background. The noninvasive detection of subclinical graft injury including subclinical T cell–mediated rejection (subTCMR) is one of the unresolved challenges after liver transplantation. Recently, serum C-X-C motif chemokine ligand 8 (CXCL8) was proposed as a highly accurate marker of subTCMR in pediatric liver transplant recipients. We aimed to evaluate the accuracy of the quantification of this chemokine for predicting subTCMR in adult liver transplant recipients, as well as its capacity to classify patients who could benefit from immunosuppression reduction. Methods. Plasma CXCL8 concentrations were measured retrospectively in a prospectively collected cohort of adult liver transplant recipients with well-characterized histologic phenotypes. Results. In total, 78 patients were included. Median plasma CXCL8 concentrations did not differ (P = 0.24) between patients without histological evidence of rejection (3.6 [0.4–22.0] pg/mL), subTCMR (11.5 [0.4–41.0] pg/mL), clinical TCMR (9.4 [0.4–40.5] pg/mL), and other etiologies of graft injury (8.7 [0.4–31.2] pg/mL). Likewise, plasma CXCL8 concentrations did not discriminate between patients within and outside histologic criteria for immunosuppression reduction that were proposed by the 2016 Banff Working Group on Liver Allograft Pathology (cutoff: 10.9 pg/mL, sensitivity: 0.48, and specificity: 0.79). Furthermore, weak correlation was found between plasma CXCL8 and alanine aminotransferase and aspartate aminotransferase (Spearman ρ = 0.18 and 0.25). Patients with significant fibrosis (17.8 [0.4–40.5] pg/mL) showed higher plasma CXCL8 concentrations than patients without fibrosis (8.2 [0.4–41.0] pg/mL; P = 0.05). Conclusions. Plasma CXCL8 concentrations are not predictive of subclinical graft injury or of histological criteria for the minimization of immunosuppression in adult liver transplant recipients.

A76 COMBINING TOFACITINIB AND USTEKINUMAB FOR REFRACTORY ULCERATIVE COLITIS: A CASE REPORT

Abstract Background The paradigm for Inflammatory Bowel Disease (IBD) management has shifted towards prioritizing remission of inflammation over symptom control, emphasizing sustained, corticosteroid-free remission at the clinical, endoscopic, and histologic levels. The shift is due to the recognition that uncontrolled inflammation often causes morbidity; after one year of biological therapy, 40% of patients still experience persistent disease activity. Several approaches have been proposed to address this challenge, including drug level monitoring, dosage titration, antibody screening, and, as a last resort, surgical intervention. Emerging limited studies suggest the potential efficacy of combining two biological agents or a biological agent with small molecules in IBD, contrasting the efficacy and safety concerns encountered with their use in rheumatological diseases. Aims To describe a case of successful combination therapy with Tofacitinib and Ustekinumab in refractory Ulcerative Colitis with a review of the current literature. Methods This case describes a 35-year-old male patient with severe Ulcerative Colitis refractory to 5-ASA, Azathioprine, Infliximab with Methotrexate, Vedolizumab, Ustekinumab and Tofacitinib. His disease persisted with primary treatment failures requiring hospital admissions and rescuing with parenteral steroids. He was switched back to Ustekinumab with minimal symptom improvement but required repeated steroid courses to achieve control. After deliberations, Tofacitinib was added. This combination achieved remission of his symptoms and inflammatory markers, mainly guided by fecal calprotectin (from 3728 µg/g to 46 µg/g), as well as endoscopic and histologic remission. He is being weaned off the oral budesonide he had been on to augment his response. Results After 4 years of combination therapy, he remains in remission with no adverse events or infections. Reassuringly, Janus Kinase inhibitors (i.e., Tofacitinib) have a short half-life, allowing prompt discontinuation if indicated, especially in the event of infection. Furthermore, biologics such as Vedolizumab, Ustekinumab, and Risankizumab offer minimal systemic immunosuppression and do not appear to raise the risk of infection. Apart from safety concerns and limited data on the use of combination therapy, significant economic implications exist. However, the attainability of cheaper generic forms of small molecules (e.g., Tofacitinib roughly costs a quarter of the brand price in Ontario, Canada) adds another advantage to their combination use. Conclusions Combination therapy with biologics and small molecules is a potential consideration for treating severe or refractory Ulcerative Colitis or IBD. To bridge the knowledge gap regarding combination therapies in IBD, further studies are needed on efficacy, safety, long-term effects, and economic impact. Funding Agencies None

Detrimental impact of immunosuppressive burden on clinical course in patients with Cytomegalovirus infection after liver transplantation.

Cytomegalovirus (CMV)-infection and reactivation remain a relevant complication after liver transplantation (LT). The recipient and donor serum CMV-IgG-status has been established for risk stratification when choosing various pharmaceutical regimens for CMV-prophylaxis in the last two decades. However, factors influencing course of CMV-infection in LT remain largely unknown. In this study, the impact of immunosuppressive regimen was examined in a large cohort of patients. All patients that underwent primary LT between 2006 and 2018 at the Charité-Universitaetsmedizin, Berlin, were included. Clinical course as well as histological and laboratory findings of patients were analyzed our prospectively maintained database. Univariate and multivariate regression analysis for impact of variables on CMV-occurrence was conducted, and survival was examined using Kaplan-Meier analysis. Overall, 867 patients were included in the final analysis. CMV-infection was diagnosed in 325 (37.5%) patients after transplantation. Significantly improved overall survival was observed in these patients (Log rank=0.03). As shown by correlation and regression tree classification and regression tree analysis, the recipient/donor CMV-IgG-status with either positivity had the largest influence on CMV-occurrence. Analysis of immunosuppressive burden did not reveal statistical impact on CMV-infection, but statistically significant inverse correlation of cumulative tacrolimus trough levels and survival was found (Log rank<.001). Multivariate analysis confirmed these findings (p=.02). CMV-infection remains of clinical importance after LT. Undergone CMV-infection of either recipient or donor requires prophylactic treatment. Additionally, we found a highly significant, dosage-dependent impact of immunosuppression (IS) on long-term outcomes for these patients, underlying the importance of minimization of IS in liver transplant recipients.

Immunosuppression minimization is safe and associated with good long-term success in pediatric recipients of liver transplant.

Immunosuppression reduction after liver transplant is an important strategy to mitigate long-term medication side effects. We describe our center's experience with immunosuppression minimization to once-daily calcineurin inhibitor dosing. Success was defined as continuing daily calcineurin inhibitor monotherapy with normal transaminases and no rejection. We performed a retrospective review of eligible children who received a liver transplant between 2009 and 2016, had a surveillance biopsy, and were on twice-daily calcineurin inhibitor monotherapy. Twenty-eight of 51 eligible patients were minimized to daily calcineurin inhibitor with goal 12-hour trough detectable. Nineteen patients (68%) had 1-year success, and 17 (61%) had long-term success at a median follow-up of 5.0 years (interquartile range (IQR): 2.9-6.6). Minimization failure occurred at a median of 0.6 years (IQR: 0.3-1.0) after dose reduction. Patients with long-term success had lower aspartate aminotransferase levels prior to minimization compared to those who failed with a median of 28.0IU/L (IQR: 20.5-32.0) versus 32.0IU/L (IQR: 30.0-37.0), p = 0.047. The long-term success group demonstrated a trend toward greater recipients of liver transplant from living donors (53% vs. 18%, p = 0.07). At the time of the last follow-up at a median of 5.0 years (IQR: 2.9-6.1) after surveillance biopsy, most (73%) patients who failed had returned to twice-daily calcineurin inhibitor monotherapy, all had liver enzymes <2 times the upper limit of normal, and there were no patient deaths or graft losses. In conclusion, immunosuppression minimization is safe in pediatric recipients of liver transplant and should be considered to reduce long-term medication side effects and improve patient quality of life. Future studies are necessary to follow long-term outcomes and develop biomarkers to predict minimization success.

Minimization of Transplant Immunosuppression: An Elusive Goal.

Minimization of Transplant Immunosuppression: An Elusive Goal.

Balancing immunosuppression in pediatric liver transplantation: Playing the long game.

The overarching goal in the care of pediatric liver transplant recipients is to optimize allograft and patient health. Balancing immunosuppression to maintain allograft health while avoiding medication side effects is essential for long-term survival and optimal quality of life in pediatric liver transplant recipients. Utilizing precision medicine to personalize immunosuppression, which includes minimization and withdrawal, is core to this effort. The unique anatomy and physiology of the liver make it more tolerant to immune-mediated injury and a more favorable organ for immunosuppression minimization and withdrawal. However, several challenges exist. Standard biochemical values and histologic features may not reliably predict allograft health after a reduction in immunosuppression. Additionally, biochemical values alone do not reliably identify which patients can successfully develop operational tolerance, as there may be occult allograft injury despite normal liver enzymes. Finally, the durability of tolerance after successful reduction in immunosuppression remains uncertain over time. Innovative tools show promise in circumventing these challenges, but more research is needed to determine actual clinical utility. While immunosuppression-free transplant may not be a current reality for most pediatric liver transplant recipients, strategies to safely minimize immunosuppression without compromising allograft health are within reach. Each liver allograft and recipient pair requires a different degree of immune modulation, and through a structured process of minimization and withdrawal, immunosuppression can indeed be tailored in a precise, personalized way to optimize outcomes. This review focuses on the progress that has been made to individualize immunosuppression in pediatric liver transplantation to ensure optimal allograft and recipient health.

Investigation of saccadic eye movement abnormalities in children with HIV/AIDS on HAART

Reading is a complex psychological task that involves rapid movements of both eyes in the same direction (saccades) from one word to the next, or, occasionally, backwards to previously encountered text. Eye movement provides a sensitive window into cognitive processing during reading and reading skills are associated with various eye movement parameters, total number of saccades and saccadic amplitudes. This is due to the knowledge that brain areas compromised by HIV infection also control saccadic eye movements. The aim of this study was to investigate the relationship between saccadic eye movements in children with HIV/AIDS on Highly Active Antiretroviral Therapy (HAART). With a descriptive cross-sectional design, 128 conveniently accessed male and female participants of ages 6 years to 13 years 11 months had their saccadic eye movements evaluated. The tool used to screen for saccadic eye movement abnormalities was a numerical reading test called the Development Eye Movement (DEM) test. Descriptive and inferential statistics was developed using SAS. Seventy-eight percent (78%) of participants had minimal immunosuppression and 65% had undetectable viral loads. The DEM test classified participants into four Behaviour Types based on their performances in this timed reading test. Ninety-three percent (93%) had vertical times and 92% had horizontal times that were outside of the specified test norms. The Behaviour Types revealed that 53% had automaticity problems (Type 3), 22% had both eye movement and automaticity problems (Type 4), 8% had no problems (Type 1) and only 3% had eye movement problems (Type 2). The association between the viral load with Behaviour Types (p=0.2) and the CD4 count against the behaviour types (p=0.17) were not statistically significant, hence no relationship could be established. More than half of the sample population manifested automaticity problems. What could not be determined was whether the automaticity problems found in this population were related to the neurocognitive functioning or neurodevelopmental delays which are known to exist in children with HIV/AIDS despite being on HAART, or if it was due to other factors. No relationship could be established between the Behaviour Types specified in the DEM test and the HIV biomarkers despite the DEM performances being largely outside of the standardised norms.

Immunosuppression regimen modification during COVID-19 infection in kidney transplant recipients

BackgroundCOVID-19 pandemic had tremendously affected all the aspects of human life during the past 3 years. In this study, we focused on kidney transplant patients' course from the COVID-19 diagnosis, immunosuppressive medication modification, hospitalization, and COVID-19 complications and how the COVID-19 infection affected the kidney and patients' quality of life during the hospitalization and after the discharge. Material and methodA retrospective analysis of a prospectively collected database of all kidney transplants adult patients who had a positive COVID-19 PCR from 1 January 2020 to 30 December 2022, and had a history of kidney transplant at the SUNY Upstate Medical Hospital was done to identify the cases. Results188 patients met the inclusion criteria and were included in the study. Based on the immunosuppressive regimen modification during COVID-19 infection, patients divided into two groups; in 143 (76%) patients, the immunosuppressive medication was reduced, and in 45 (24%) of patients, the immunosuppressive regimen continued as before during the COVID-19 infection. The mean time from the transplant to the diagnosis of COVID-19 was 67 months in the group we reduced the IM regimen, and 77 months in the group without changes in IM regimen. The mean recipients' age was 50.7 ± 12.9 years in the group we reduced the IM regimen, and 51.8 ± 16.4 years in the group without changes in IM regimen (P = 0.64). The vaccination rate against COVID-19 with at least 2 doses of either the CDC recommended Moderna or Pfizer vaccines was 80.2% in the group we reduced the IM regimen, and 84.8% in the group without changes in IM regimen (P = 0.55). The hospitalization rate due to COVID-19 related symptoms was 22.4% % in the group we reduced the IM regimen, and 35.5% in the group without changes in IM regimen (P = 0.12). However, the ICU admission rate was higher in the group we reduced the IM regimen, but the difference was not significant (26.5% Vs.6.25%, P = 0.12). 6 episodes of biopsy-proven rejection in the group with IM reduction was observed, which were 3 episodes of acute antibody-mediated rejections (ABMR) and 3 episodes of acute T-Cell-mediated rejections (TCMR), and 3 episodes in the group without any change in IM regimen, which were 2 episodes of ABMR and 1 episode of TCMR (P = 0.51). No significant difference was mentioned in the eGFR and serum creatinine after the comparison between the groups after 12 months of follow up.124 patients responded to the post-COVID-19 questionnaires and were included in the data analysis. The response rate was 66%. Fatigue and exertion were the most reported symptom with a 43.9% prevalence. ConclusionsWe found that immunosuppressive regimen minimization did not impact the kidney function in the long-term and it might be a helpful strategy to minimize the effect of COVID-19 infection on patients' condition during the hospital stay. With all the treatments, vaccinations, and precautions, still some patients did not achieve the complete recovery compared to their pre-COVID-19 health status. Fatigue was the main reported symptom amongst all the reported symptoms.

Equivalents of the neutrophil-to-lymphocyte ratio of circulating pool of stem and immature hematopoietic cells for assessing liver transplant status

Objective: to study the applicability of the neutrophil-to-lymphocyte ratio (NLR) for monitoring recipient status and for possible minimization of maintenance immunosuppression in the long-term period after liver transplantation (LT).Materials and methods. Blood samples of 19 recipients with satisfactory graft function were examined by flow cytofluorometry at various time periods after LT using hematopoietic stem cell markers CD133, their CD31 derivatives, and alpha-fetoprotein (AFP), compared with the conventional NLR.Results. The use of NLR equivalents with CD133 and CD31 to assess liver transplant status is due to their high representation in liver tissue. Their values change in the long-term posttransplant period (from 1.5 to 6–7 years following LT) ≈20-fold and in different directions, but only when measuring their commissural to the liver cell fractions bearing the AFP marker.Conclusion. In contrast to the conventional NLR, maintenance of the lowest level of CD31 AFP, an NLR «equivalent», achieved at 1.5 years after LT, can be considered a criterion for the success of immunosuppressive therapy in the long-term post-LT period. The developed technique can be used to decide on whether to reduce or discontinue medication-assisted prophylaxis of graft rejection.

Comparison of Graft Survival Between Full-Thickness and Lamellar Pig-to-Monkey Corneal Xenotransplantation from the Same Genetically Engineered Pig Model with Minimal Immunosuppression

The graft survival rate of full-thickness corneal xenotransplantation (XTP) with minimal immunosuppression in genetically engineered pigs is unknown, whereas lamellar corneal XTP shows satisfactory results. We compared graft survival between full-thickness and lamellar transplantations in the same genetically engineered pig. Six pig-to-monkey corneal transplantations were performed on 3 transgenic pigs. Two corneas harvested from 1 pig were transplanted into 2 monkeys using full-thickness and lamellar corneal xenotransplantation. The transgenic donor pigs used were α1,3-galactosyltransferase gene-knockout+membrane cofactor protein (GTKO+CD46) in one recipient and GTKO+CD46+ thrombomodulin (TBM) in the other. The graft survival time for GTKO+CD46 XTP was 28 days. With the addition of TBM, the survival differences between lamellar and full-thickness XTP were 98 days versus 14 days and >463 days (ongoing) versus 21 days, respectively. An excessive number of inflammatory cells was observed in failed grafts, but none were in the recipient's stromal bed. Unlike full-thickness corneal XTP, lamellar xenocorneal transplantation does not exhibit surgical complications, such as retrocorneal membrane or anterior synechia. The graft survival of lamellar XTP in this study was not as good as in our previous experiments, although the survival period was superior to that of full-thickness XTP. The difference in graft survival based on transgenic type is not definitive. Further studies using transgenic pigs and minimal immunosuppression need to focus on improving graft survival of lamellar XTP and using a larger sample size to determine the potential of full-thickness corneal XTP.

Combination of everolimus and low-dose tacrolimus controls histological liver allograft injury as sufficiently as high-dose tacrolimus.

The combination of everolimus (EVR) and low-dose tacrolimus (lowTAC) prevents T cell-mediated rejection of liver grafts as sufficiently as high-dose tacrolimus (highTAC) and mycophenolate, but is associated with a preserved kidney function within the first years after orthotopic liver transplantation (OLT). However, none of the available studies assessed the histological pattern of graft injury or fibrosis in surveillance biopsies (svLbx). All svLbx taken under at least one month of stable immunosuppression with either EVR (aim 3-8 ng/ml) combined with lowTAC (aim 3-5 ng/ml) or highTAC (aim 5-8 ng/ml) combined with mycophenolate (500-1500 mg/day) within the first three to four years after OLT at our center were included. Patients who were switched to EVR because of insufficient control of alloreactivity were excluded. Reasons for switches to EVR were mainly malignancies before or after OLT, or chronic kidney injury. We were able to include 20 svLbx with EVR/lowTAC and 49 with highTAC/mycophenolate. Both groups had similar liver enzymes and similar kidney function. The EVR/lowTAC group exhibited lower TAC trough levels at svLbx (4.4 vs. 6.6 ng/ml; p<.001) in comparison to highTAC/mycophenolate. Histological graft injury quantified by the rejection activity index and hepatitis activity index (Ishak), as well as fibrosis were not significantly different between the EVR/lowTAC and highTAC/mycophenolate groups. Likewise, subclinical TCMR, histological criteria justifying immunosuppression minimization, and steatosis had equal prevalence in both regimens. Immunosuppression was adjusted according to the svLbx findings. Immunosuppression regimens had similarly low rates of rejection after immunosuppression reduction, when relevant graft injury was absent in the biopsy. In conclusion, EVR/lowTAC seems to control alloreactivity and histological graft injury as sufficiently as highTAC/mycophenolate within the first 3-4 years after OLT.

Research Highlights.

Research Highlights.

Treg Therapy for the Induction of Immune Tolerance in Transplantation-Not Lost in Translation?

The clinical success of solid organ transplantation is still limited by the insufficiency of immunosuppressive regimens to control chronic rejection and late graft loss. Moreover, serious side effects caused by chronic immunosuppressive treatment increase morbidity and mortality in transplant patients. Regulatory T cells (Tregs) have proven to be efficient in the induction of allograft tolerance and prolongation of graft survival in numerous preclinical models, and treatment has now moved to the clinics. The results of the first Treg-based clinical trials seem promising, proving the feasibility and safety of Treg therapy in clinical organ transplantation. However, many questions regarding Treg phenotype, optimum dosage, antigen-specificity, adjunct immunosuppressants and efficacy remain open. This review summarizes the results of the first Treg-based clinical trials for tolerance induction in solid organ transplantation and recapitulates what we have learnt so far and which questions need to be resolved before Treg therapy can become part of daily clinical practice. In addition, we discuss new strategies being developed for induction of donor-specific tolerance in solid organ transplantation with the clinical aims of prolonged graft survival and minimization of immunosuppression.