Successful treatment of acute kidney allograft rejection using extracorporeal photopheresis in the context of post-transplant lymphoproliferative diseases: three successive cases.

We reported 3 kidney transplant patients with PTLD who developed mixed AR following IS treatment minimization. AR episodes were treated with extracorporeal photopheresis (ECP), methylprednisolone and IVIG. In all patients, graft function improved under ECP and stabilized in the long term. These observations suggest that ECP is safe and efficient for treatment of AR in the context of PTLD.

Overexpression of miR-223 Promotes Tolerogenic Properties of Dendritic Cells Involved in Heart Transplantation Tolerance by Targeting Irak1.

Dendritic cells (DCs) are key mediators of transplant rejection. Numerous factors have been identified that regulate transplant immunopathology by modulating the function of DCs. Among these, microRNAs (miRNAs), small non-coding RNA molecules, have received much attention. The miRNA miR-223 is very highly expressed and tightly regulated in hematopoietic cells. It plays an important role in modulating the immune response by regulating neutrophils and macrophages, and its dysregulation contributes to multiple types of immune diseases. However, the role of miR-223 in immune rejection is unclear. Here, we observed expression of miR-223 in patients and mice who had undergone heart transplantation and found that it increased in the serum of both, and also in DCs from the spleens of recipient mice, although it was unchanged in splenic T cells. We also found that miR-223 expression decreased in lipopolysaccharide-stimulated DCs. Increasing the level of miR-223 in DCs promoted polarization of DCs toward a tolerogenic phenotype, which indicates that miR-223 can attenuate activation and maturation of DCs. MiR-223 effectively induced regulatory T cells (Tregs) by inhibiting the function of antigen-presenting DCs. In addition, we identified Irak1 as a miR-223 target gene and an essential regulator of DC maturation. In mouse allogeneic heterotopic heart transplantation models, grafts survived longer and suffered less immune cell infiltration in mice with miR-223-overexpressing immature (im)DCs. In the miR-223-overexpressing imDC recipients, T cells from spleen differentiated into Tregs, and the level of IL-10 in heart grafts was markedly higher than that in the control group. In conclusion, miR-223 regulates the function of DCs via Irak1, differentiation of T cells into Tregs, and secretion of IL-10, thereby suppressing allogeneic heart graft rejection.

Impact of Sex in the Efficacy of Perioperative Desensitization Procedures in Heart Transplantation: A Retrospective Cohort Study.

Background: Sensitized patients, i.e. recipients with preformed donor-specific HLA antibodies (pfDSA), are at high-risk of developing antibody-mediated rejections (AMR) and dying after heart transplantation (HTx). Perioperative desensitization procedures are associated with better outcomes but can cause sensitization, which may influence their efficacy. Methods: In sensitized patients (pfDSA>1000 mean immunofluorescence (MFI) units), we assessed the effect of perioperative desensitization by comparing treated patients to a historical control cohort. Multivariable survival analyses were performed on the time to main outcome, a composite of death and biopsy-proven AMR with 5-year follow-up. Results: The study included 68 patients: 31 control and 37 treated patients. There was no difference in preoperative variables between the two groups, including cumulative pfDSA [4026 (1788;8725) vs 4560 (3162;13392) MFI units, p=0.28]. The cause of sensitization was pregnancy in 24/68, 35.3%, transfusion in 61/68, 89.7%, and previous HTx in 4/68, 5.9% patients. Multivariable analysis yielded significant protective association between desensitization and events (adjusted (adj.) hazard ratio (HR)=0.44 (95% confidence interval (95CI)=0.25-0.79), p=0.006) and deleterious association between cumulative pfDSA and events [per 1000-MFI increase, adj.HR=1.028 (1.002-1.053), p=0.031]. There was a sex-difference in the efficacy of desensitization: in men (n=35), the benefit was significant [unadj.HR=0.33 (95CI=0.14-0.78); p=0.01], but not in women (n=33) [unadj.HR=0.52 (0.23-1.17), p=0.11]. In terms of the number of patients treated, in men, 2.1 of patients that were treated prevented 1 event, while in women, 3.1 required treatment to prevent 1 event. Conclusion: Perioperative desensitization was associated with fewer AMR and deaths after HTx, and efficacy was more pronounced in men than women.

Donor Recipient Chimeric Cells Induce Chimerism and Extend Survival of Vascularized Composite Allografts.

This study evaluated the efficacy of donor recipient chimeric cell (DRCC) therapy created by fusion of donor and recipient derived bone marrow cells (BMC) in chimerism and tolerance induction in a rat vascularized composite allograft (VCA) model. Twenty-four VCA (groin flaps) from MHC-mismatched ACI (RT1a) donors were transplanted to Lewis (RT1l) recipients. Rats were randomly divided into (n = 6/group): Group 1-untreated controls, Groups 2-7-day immunosuppression controls, Group 3-DRCC, and Group 4-DRCC with 7-day anti-αßTCR monoclonal antibody and cyclosporine A protocol. DRCC created by polyethylene glycol-mediated fusion of ACI and Lewis BMC were cultured and transplanted (2-4 × 106) to VCA recipients via intraosseous delivery route. Flow cytometry assessed peripheral blood chimerism while fluorescent microscopy and PCR tested the presence of DRCC in the recipient's blood, bone marrow (BM), and lymphoid organs at the study endpoint (VCA rejection). No complications were observed after DRCC intraosseous delivery. Group 4 presented the longest average VCA survival (79.3 ± 30.9 days) followed by Group 2 (53.3 ± 13.6 days), Group 3 (18 ± 7.5 days), and Group 1 (8.5 ± 1 days). The highest chimerism level was detected in Group 4 (57.9 ± 6.2%) at day 7 post-transplant. The chimerism declined at day 21 post-transplant and remained at 10% level during the entire follow-up period. Single dose of DRCC therapy induced long-term multilineage chimerism and extended VCA survival. DRCC introduces a novel concept of customized donor-recipient cell-based therapy supporting solid organ and VCA transplants.

Regulatory T cells induce transplant immune tolerance.

Organ transplantation is the preferred treatment option for end-stage organ failure. Although immunosuppressants are effective for preventing the occurrence of acute rejection, they also cause a series of side effects in transplant recipients. To improve the quality of patient survival, a new therapeutic strategy that has fewer side effects than current immunosuppressive regimens and can induce allograft immune tolerance and effectively prevent transplant rejection is needed. In this context, regulatory T cells (Tregs) are considered to be promising research targets. With the increasing understanding of the immunomodulatory role of Tregs, the use of Treg-based cellular therapies has shifted from prevention/treatment of autoimmune diseases to clinical trials for organ transplantation. This review describes the phenotype and in vitro expansion of Tregs and the mechanisms by which they exert immunomodulatory effects in transplantation immunity, highlights recent clinical trial data on Treg-based cellular therapies in transplantation, and describes future directions and limitations.

Early critical cortical infarction by anti-angiotensin II type 1 receptor antibody: A case report and literature review.

RATIONALE: Anti-angiotensin II type 1 receptor antibodies (AT1R-Abs) have been demonstrated to increase the risk of antibody-mediated rejection. We report a case of AT1R-Ab mediated rejection which caused early critical cortical infarction. PATIENT CONCERNS: A 52-year-old man with end-stage kidney disease underwent preemptive kidney transplantation (KT) from his wife. He had no immunologic risk except ABO incompatibility. Proper desensitization treatment were applied prior to KT. On postoperative day 1, he showed stable clinical course with adequate urine output, but there was no decrease in serum creatinine level and imaging studies showed hypoperfusion in the transplanted kidney. DIAGNOSES: Allograft biopsy revealed total cortical infarction with severe necrotizing vasculitis, but the medullary area was preserved. Serum AT1R-Ab concentration was elevated from 10.9 U/mL before KT to 19.1 U/mL on 7 days after KT. INTERVENTIONS: He was treated with plasmapheresis, intravenous immunoglobulin, rituximab, high-dose methylprednisolone, and bortezomib. OUTCOMES: The treatment showed a partial response, and he was discharged with 7.3 mg/dL creatinine level. At 4 months, his creatinine plateaued at 5.5 mg/dL and AT1R-Ab decreased to 3.6 U/mL. LESSONS: This case highlights the risk of early active antibody-mediated rejection by preformed AT1R-Ab, suggesting its ability to exhibit atypical histopathologic findings, such as total cortical infarction.

The Role of Regulatory Myeloid Cell Therapy in Renal Allograft Rejection.

Kidney transplantation is a primary therapy for end-stage renal disease (ESRD) all the time. But it does not mean that we have fully unraveling the mystery of kidney transplantation and confer every patient favorable prognosis. Immune rejection has always been a stumbling block when we try to increase the success rate of kidney transplantation and improve long-term outcomes. Even if the immune rejection is effectively controlled in acute phase, there is a high possibility that the immune response mediated by chronically activated antibodies will trigger chronic rejection and ultimately lead to graft failure. At present, immunosuppressive agent prepared chemically is mainly used to prevent acute or chronic rejection, but it failed to increase the long-term survival rate of allografts or reduce the incidence of chronic rejection after acute rejection, and is accompanied by many adverse reactions. Therefore, many studies have begun to use immune cells to regulate the immune response in order to control allograft rejection. This article will focus on the latest study and prospects of more popular regulatory myeloid cells in the direction of renal transplantation immunotherapy and introduce their respective progress from experimental research to clinical research.

Separating the wheat from the chaff: Making sense of Treg heterogeneity for better adoptive cellular therapy.

Regulatory T (Treg) cells are essential for immunological tolerance and can be used to suppress unwanted or excessive immune responses through adoptive cellular therapy. It is increasingly clear that many subsets of Treg cells exist, which have different functions and reside in different locations. Treg cell therapies may benefit from tailoring the selected subset to the tissue that must be protected as well as to characteristics of the immune response that must be suppressed, but little attention is given to this topic in current therapies. Here, we will discuss how three major axes of heterogeneity can be discerned among the Treg cell population, which determine function and lineage fidelity. A first axis relates to the developmental route, as Treg cells can be generated from immature T cells in the thymus or from already mature Tconv cells in the immunological periphery. Heterogeneity furthermore stems from activation history (naïve or effector) and location (lymphoid or peripheral tissues). Each of these axes bestows specific properties on Treg cells, which are further refined by additional processes leading to yet further variation. A critical aspect impacting on Treg cell heterogeneity is TCR specificity, which determines when and where Treg cells are generated as well as where they exhibit their effector functions. We will discuss the implications of this heterogeneity and the role of the TCR for the design of next generation adoptive cellular therapy with Treg cells.

Regulatory Cell Therapy in Organ Transplantation: Achievements and Open Questions.

The effective development of innovative surgical applications and immunosuppressive agents have improved remarkable advancements in solid organ transplantation. Despite these improvements led to prevent acute rejection and to promote short-term graft survival, the toxicity of long-term immunosuppression regiments has been associated to organ failure or chronic graft rejection. The graft acceptance is determined by the balance between the regulatory and the alloreactive arm of the immune system. Hence, enhance regulatory cells leading to immune tolerance would be the solution to improve long-term allograft survival which, by reducing the overall immunosuppression, will provide transplanted patients with a better quality of life. Regulatory T cells (Tregs), and regulatory myeloid cells (MRCs), including regulatory macrophages and tolerogenic dendritic cells, are promising cell populations for restoring tolerance. Thus, in the last decade efforts have been dedicated to apply regulatory cell-based therapy to improve the successful rate of organ transplantation and to promote allogeneic tolerance. More recently, this approach has been translated into clinical application. The aim of this review is to summarize and discuss results on regulatory cell-based strategies, focusing on Tregs and MRCs, in terms of safety, feasibility, and efficacy in clinical studies of organ transplantation.

Liver and kidney transplantation in polycystic liver and kidney disease. / Trasplante hepático y renal en la enfermedad poliquística hepatorrenal.

OBJECTIVE: To evaluate the results of isolated liver and combined liver and kidney transplantation in a retrospective series of 32 patients with hepatorenal liver and kidney disease. MATERIALS AND METHODS: A retrospective observational study that enrolled patients with polycystic liver disease (PLD) and polycystic liver and kidney disease (PLKD) who were evaluated for transplantation between January 1999 and December 2019 at Hospital Clínic de Barcelona [Clinical Hospital of Barcelona]. RESULTS: We included a total of 53 patients enrolled, 32 (60.3%) had indication for transplantation, of which 12 received a single liver transplant and 20 received a double liver and kidney transplant. The mean age was 52 years and 83.9% of the recipients were women. The main indication for liver transplantation was disabling symptomatic hepatomegaly (93.5%). Among the postoperative complications, in the combined liver and kidney transplant group, hepatic artery thrombosis in one case and renal artery thrombosis in other were detected. In both groups there was one case of inferior vena cava lesion. Three patients presented acute cellular rejection responding to corticosteroids and one presented humoral rejection which was treated with plasmapheresis. During the follow-up period of 80 (27-121) months, the liver transplant survival rate was 100% and the kidney transplant survival rate was 90%. Two patients in the combined liver and kidney transplant group died (one due to cardiovascular causes and the other due to intestinal adenocarcinoma). CONCLUSIONS: Isolated liver transplantation or combined liver and kidney transplantation in selected patients with polycystic disease yields excellent results, with few complications, very good transplant survival and excellent patient survival (93.8%).

A Randomized Clinical Trial of Anti-IL-6 Antibody Clazakizumab in Late Antibody-Mediated Kidney Transplant Rejection.

BACKGROUND: Late antibody-mediated rejection (ABMR) is a leading cause of transplant failure. Blocking IL-6 has been proposed as a promising therapeutic strategy. METHODS: We performed a phase 2 randomized pilot trial to evaluate the safety (primary endpoint) and efficacy (secondary endpoint analysis) of the anti-IL-6 antibody clazakizumab in late ABMR. The trial included 20 kidney transplant recipients with donor-specific, antibody-positive ABMR ≥365 days post-transplantation. Patients were randomized 1:1 to receive 25 mg clazakizumab or placebo (4-weekly subcutaneous injections) for 12 weeks (part A), followed by a 40-week open-label extension (part B), during which time all participants received clazakizumab. RESULTS: Five (25%) patients under active treatment developed serious infectious events, and two (10%) developed diverticular disease complications, leading to trial withdrawal. Those receiving clazakizumab displayed significantly decreased donor-specific antibodies and, on prolonged treatment, modulated rejection-related gene-expression patterns. In 18 patients, allograft biopsies after 51 weeks revealed a negative molecular ABMR score in seven (38.9%), disappearance of capillary C4d deposits in five (27.8%), and resolution of morphologic ABMR activity in four (22.2%). Although proteinuria remained stable, the mean eGFR decline during part A was slower with clazakizumab compared with placebo (-0.96; 95% confidence interval [95% CI], -1.96 to 0.03 versus -2.43; 95% CI, -3.40 to -1.46 ml/min per 1.73 m2 per month, respectively, P=0.04). During part B, the slope of eGFR decline for patients who were switched from placebo to clazakizumab improved and no longer differed significantly from patients initially allocated to clazakizumab. CONCLUSIONS: Although safety data indicate the need for careful patient selection and monitoring, our preliminary efficacy results suggest a potentially beneficial effect of clazakizumab on ABMR activity and progression.

Long Term Outcomes of Endovascular Therapy for Failing Distal Bypass Vein Grafts.

OBJECTIVE: Although distal bypass using vein has been established with acceptable outcomes for chronic limb threatening ischaemia (CLTI), the major issue affecting long term outcomes is vein graft disease. This study aimed to analyse the peri-procedural results and long term outcomes of endovascular therapy (EVT) for failing vein grafts after distal bypass. METHODS: A retrospective analysis of 113 failing vein grafts (94 patients, 113 limbs) after distal bypass between 2009 and 2019 at the study hospital. RESULTS: The mean age was 74 ± 9 years and 72% of the patients were men. Of the 113 grafts, 54 grafts (48%) were detected in asymptomatic patients, 41 grafts (36%) in patients with recurrent ulcer or gangrene, and 18 grafts (16%) in patients with rest pain. The failing grafts were treated by low pressure long inflation balloon angioplasty with a mean balloon size of 3.0 ± 0.8 mm. The mean procedural time was 60 ± 29 min and procedural success was 98% (111 grafts). During the mean follow up period of 34 months, EVT was performed a median frequency of two times (range 1-11 times). The primary and assisted primary patency of the EVT revised grafts were 41% and 80% at one year, 34% and 68% at three years, 31% and 58% at five years, respectively. Of 41 limbs with recurrent ulcer or gangrene, the wound healed in 34 limbs (85%). The complete healing rate was 71% at three months and 84% at 12 months. Eight patients required major amputation, and the freedom from major amputation rate was 96% at one year and 80% at five years. CONCLUSION: Long term outcomes including patency, wound healing rate, and amputation free survival after EVT for failing vein grafts were acceptable. EVT could be a viable alternative to surgical revascularisation in patients with a failing distal bypass graft for CLTI.

The Impact of Inadequate ("AX") Transbronchial Biopsies on Post-lung Transplant CLAD or Death.

BACKGROUND: Procuring a good quality transbronchial-biopsy sample is essential for diagnosing acute cellular rejection after lung transplantation (LT). Insufficient transbronchial-biopsy samples are graded "AX." We hypothesized that AX samples may be associated with a higher risk for chronic lung allograft dysfunction (CLAD) or death/retransplant, through a potential anatomic or physiologic underlying pulmonary process or because of undiagnosed acute cellular rejection episodes. METHODS: We conducted a single-center, retrospective, cohort study drawn from all consecutive adult, first, bilateral LT between 1999 and 2015. We reviewed all biopsies obtained within the first year posttransplant and compared outcomes of patients with ≥1 AX to patients with no AX. Association of any AX or percent AX with time to CLAD or death/retransplant was assessed using Cox Proportional Hazards models. RESULTS: The cohort consisted of 809 patients with a median of 6 (interquartile range 5-6) biopsies and 16.7% (interquartile range 0-25) AX samples within the first year posttransplant. Four hundred thirty-nine (54.3%) subjects had ≥1 AX sample obtained within the time period. Median time to CLAD or death/retransplant, from 1 year posttransplant, was 761 (320, 1587) and 1200 (662, 2308) days, respectively. In the multivariable analysis, there was no difference in risk for CLAD (hazard ratio = 1.05, 95% confidence interval, 0.87-1.28, P = 0.60), or death/retransplant (hazard ratio = 1.14, 95% confidence interval, 0.92-1.42, P = 0.24) between patients with ≥1 AX biopsy versus none. Among subjects with ≥1 AX, having >50% AX biopsies was not associated with outcome. CONCLUSIONS: This is the first study to demonstrate that AX biopsies are not associated with an increased risk of CLAD or death/retransplant after LT and may not require to repeat the biopsy.

Early surveillance biopsy utilization and management of pediatric renal allograft acute T cell-mediated rejection in Canadian centers: Observations from the PROBE multicenter cohort study.

BACKGROUND: Early TCMR surveillance with protocol kidney biopsy is used differentially among pediatric kidney transplant centers. Little has been reported about actual center-based differences, and this variability may influence TCMR ascertainment, treatment, and monitoring more broadly. METHODS: Data from the PROBE multicenter study were used to identify patients from centers conducting ESB or LSIB. ESB was defined as >50% of patients having at least 1 surveillance biopsy in the first 9 months. Patients were compared for number of biopsies, rejection episodes, treatment, and follow-up monitoring. RESULTS: A total of 261 biopsies were performed on 97 patients over 1-2 years of follow-up. A total of 228 (87%) of biopsies were performed in ESB centers. Compared to LSIB centers, ESB centers had 7-fold more episodes of TCMR diagnosed on any biopsy [0.8 ± 1.2 vs 0.1 ± 0.4; P < .001] and a 3-fold higher rate from indication biopsies [0.3 ± 0.9 vs 0.1 ± 0.3; P = .04]. The proportion of rejection treatment varied based on severity: Banff borderline i1t1 (40%);>i1t1 and < Banff 1A (86%); and ≥ Banff 1A (100%). Biopsies for follow-up were performed after treatment in 80% of cases (n = 28) of rejection almost exclusively at ESB centers, with 17 (61%) showing persistence of TCMR (≥i1t1). CONCLUSIONS: Practice variation exists across Canadian pediatric renal transplant centers with ESB centers identifying more episodes of rejection. Additionally, treatment of Banff borderline is not universal and varies with severity regardless of center type. Lastly, follow-up biopsies are performed inconsistently and invariably show persistence of rejection.

Variation in immunosuppression practices among pediatric liver transplant centers-Society of Pediatric Liver Transplantation survey results.

BACKGROUND: Variation in IS exists among pediatric liver transplant centers. While individual centers may publish their practice paradigms, current data on practices as a whole are lacking. This study sought to ascertain the IS protocols of pediatric liver transplant centers within the SPLIT to better understand variability and similarities among peer institutions. METHODS: A 27-item questionnaire was developed within the SPLIT Quality Improvement and Clinical Care Committee. The survey collected data regarding center demographics, IS practices, and treatment of acute cellular rejection. RESULTS: Twenty-eight (64%) SPLIT centers responded with 22 (79%) centers performing more than 10 transplants per year and 17 (61%) following more than 100 post-transplant recipients. All centers use a written protocol, and 25 (89%) have a dedicated transplant pharmacist/PharmD. Twenty-five (89%) centers use steroids for induction alone or in combination with thymoglobulin/interleukin-2 antibodies. All centers use tacrolimus for initial maintenance therapy. Most centers have specialized protocols for ABO-incompatible transplants, recipients with renal dysfunction, autoimmune liver diseases, and liver tumors. Treatment of rejection varied but was associated with escalation in IS. CONCLUSION: IS practices among pediatric liver transplant centers are similar including the use of written protocols, pharmacy involvement, steroids for induction, tacrolimus as initial IS, tacrolimus reduction/delay for renal dysfunction, and escalation of IS with rejection severity. However, other IS practices show wide variability including treatment for ABO-incompatible grafts and presumed rejection. This study serves as a foundation to guide prospective research linking IS practice to outcomes to determine best practice.