Immunomodulatory Effects of Mixed Hematopoietic Chimerism: Immune Tolerance in Canine Model of Lung Transplantation

Long-term survival after lung transplantation is limited by acute and chronic graft rejection. Induction of immune tolerance by first establishing mixed hematopoietic chimerism (MC) is a promising strategy to improve outcomes. In a preclinical canine model, stable MC was established in recipients after reduced-intensity conditioning and hematopoietic cell transplantation from a DLA-identical donor. Delayed lung transplantation was performed from the stem cell donor without pharmacological immunosuppression. Lung graft survival without loss of function was prolonged in chimeric (n = 5) vs. nonchimeric (n = 7) recipients (p ≤ 0.05, Fisher's test). There were histological changes consistent with low-grade rejection in 3/5 of the lung grafts in chimeric recipients at ≥1 year. Chimeric recipients after lung transplantation had a normal immune response to a T-dependent antigen. Compared to normal dogs, there were significant increases of CD4+INFγ+, CD4+IL-4+ and CD8+ INFγ+ T-cell subsets in the blood (p < 0.0001 for each of the three T-cell subsets). Markers for regulatory T-cell subsets including foxP3, IL10 and TGFβ were also increased in CD3+ T cells from the blood and peripheral tissues of chimeric recipients after lung transplantation. Establishing MC is immunomodulatory and observed changes were consistent with activation of both the effector and regulatory immune response.     

Living Donor Renal Transplantation Using Alemtuzumab Induction and Tacrolimus Monotherapy

Alemtuzumab was used as an induction agent in 205 renal transplant recipients undergoing 207 living donor renal transplants. All donor kidneys were recovered laparoscopically. Postoperatively, patients were treated with tacrolimus monotherapy, and immunosuppression was weaned when possible. Forty-seven recipients of living donor renal transplants prior to the induction era who received conventional triple drug immunosuppression without antibody induction served as historic controls. The mean follow-up was 493 days in the alemtuzumab group and 2101 days in the historic control group. Actuarial 1-year patient and graft survival were 98.6% and 98.1% in the alemtuzumab group, compared to 93.6% and 91.5% in the control group, respectively. The incidence of acute cellular rejection (ACR) at 1 year was 6.8% in the alemtuzumab group and 17.0% (p < 0.05) in the historic control group. Most (81.3%) episodes of ACR in the alemtuzumab group were Banff 1 (a or b) and were sensitive to steroid pulses for the treatment of rejection. There was no cytomegalovirus disease or infection. The incidence of delayed graft function was 0%, and the incidence of posttransplant insulin-dependent diabetes mellitus was 0.5%. This study represents the largest series to date of live donor renal transplant recipients undergoing alemtuzumab induction, and confirms the short-term safety and efficacy of this approach.     

Induction With Basiliximab in Renal Transplantation

Introduction

The use of monoclonal antibodies in renal transplantation for induction therapy has been associated with a marked reduction in acute rejection rates with an impact on graft and patient survivals.

Objective

We sought to evaluate the efficacy of renal transplant induction protocols using Basiliximab based on the rates of acute rejection episodes (ARE) and delayed graft function (DGF) of infectious complications in the first 6 months posttransplant, as well as patient and graft survivals.

Methods

We retrospectively evaluated all renal transplants performed between 2000 and 2008 that were primary grafts from cadaveric heart-beating donors, into recipients with a panel reactive antibody titer <5% and who were treated with an immunosuppression scheme based on cyclosporine, mycophenolate mofetil/mycophenolic acid plus corticosteroids, with (group 1) or without basiliximab (group 2).

Results

We enrolled 52 recipients in group 1 (induction with basiliximab) and 189 in group 2 (without basiliximab). The baseline characteristics were similar among the groups, except for time on dialysis which was longer in group 1 and the number of HLA matches, which was lower in group 1. The ARE rate was lower among group 1 (7.8% vs 27.8%; P = .001); rates of DGF and infectious complications were similar. There was no significant difference in graft and patient survivals.

Conclusion

In this study, induction with basiliximab was associated with a reduced rate rate of ARE, despite a lower number of HLA matches and a longer previous time on dialysis. The use of this induction modality was not associated with a greater rate of infectious complications.     

Campath-1H Induction Plus Rapamycin Monotherapy for Renal Transplantation: Results of a Pilot Study

Campath-1H, an anti-CD52 monoclonal antibody, was used as induction therapy (40 mg i.v. total dose) in 29 primary human renal transplants, and the patients were maintained on rapamycin monotherapy (levels 8-15 ng/mL) post-transplant. Campath-1H profoundly depletes lymphocytes long-term and more transiently depletes B cells and monocytes. All patients are alive and well at 3-29 months of follow up. One graft was lost because of rejection. There have been no systemic infections and no malignancies. Eight of 29 patients have experienced rejection, which was successfully treated in seven of eight patients. Five of these patients had pathological evidence of a humoral component of their rejection. Seven of the 29 patients were converted to standard triple therapy on account of rejection. Rapamycin was generally well tolerated in that there were no significant wound-healing problems; two lymphoceles required surgical drainage; and most patients were treated with a lipid-lowering agent. Flow crossmatch testing post-transplant revealed evidence of alloantibody in two patients tested with previous combined cellular and humoral rejection. Biopsies have shown no chronic allograft nephropathy to date. In view of the relatively high incidence of early humoral rejection, we plan to modify the immunosuppressive regimen in subsequent pilot studies. This clinical trial provides insight into the use of Campath-1H induction in combination with rapamycin maintenance monotherapy.     

Comparison of Thymoglobulin and Grafalon as Induction Agents in Renal Transplantation: A Prospective Study

BackgroundInduction immunosuppression is used to reduce the incidence of acute rejection and prevent delayed graft function. The 2 rabbit anti-thymocyte globulins- thymoglobulin and Grafalon (ATG Fresenius) have been commonly used for induction immunosuppression and treatment of acute rejection in solid organ transplantation. There are very few studies comparing the efficacy and side effects of both the anti-thymocyte globulins therefore this prospective study comparing the 2 types of anti-thymocyte globulins would be of clinical interest.Patients and MethodsThis prospective single center study was conducted at Rabindranath Tagore International Institute of Cardiac Sciences, Kolkata, India from April 2019 to June 2020. Sixty-two ABO-compatible renal transplant recipients were included in the study. They were divided in 2 groups of 31 patients each. One group received thymoglobulin (3 mg/kg) and the second group received Grafalon (6 mg/kg). All patients were followed up for 12 months and the 2 groups were compared for incidence of rejections, infections, graft function, patient survival, and graft survival.ResultsThere was no significant difference in the incidence of rejections, infective episodes, graft function, posttransplant diabetes mellitus, graft survival and patient survival in thymoglobulin or Grafalon groups. The hematological parameters were similar in both groups at 7 days, 1 month, and 6 months of follow-up. The absolute lymphocyte count was significantly lower in the thymoglobulin group at 12 months posttransplant.ConclusionsThymoglobulin and Grafalon were found to be equivalent in terms of safety and efficacy in short term, with no difference in rejections, infections, graft survival, or patient survival.     

Induction of Tolerance in Solid Organ Transplantation: The Rationale to Develop Clinical Protocols in Liver Transplantation

Minimization or withdrawal of immunosuppressive treatments after organ transplantation represents a major objective for improving quality of life and long-term survival of grafted patients. Such a goal may be reached under some clinical conditions, particularly in liver transplantation, making these patients good candidates for tolerance trials. In this context in liver transplantation, the central questions are (1) how to promote the natural propensity of the liver graft to be accepted, (2) which type of immunosuppressive drug should be used for induction and maintenance, and (3) which biomarkers could be used to discriminate tolerant patients from those requiring long-term immunosuppression. Induction therapies using aggressive T-cell-depleting agents may favor graft acceptance. However, persistent and/or rapidly reemerging cell lines, such as memory-type cells or CD8⁺ T cells, could represent a significant barrier for induction of tolerance. The type of maintenance drugs also remains questionable. Calcineurin inhibitors may be eventually deleterious in the context of tolerance protocols, through inhibitory effects on regulatory T cells, that are not observed with rapamycin. In conclusion, significant efforts must be made to achieve reliable strategies for immunosuppression minimization or withdrawal after organ transplantation into the clinics.     

Protective Effects of a Hydrogen-Rich Preservation Solution in a Canine Lung Transplantation Model

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Pretransplantation Oral Glucose Tolerance Test Can Prevent Posttransplant Diabetes Mellitus After Renal Transplantation: Preliminary Study

Posttransplant diabetes mellitus (PTDM) adversely affects renal graft and patient survival. Fasting plasma glucose (FPG) alone underestimates diagnosis of glucose metabolism disorders (GMD) detected using the oral glucose tolerance test (OGTT-75). Prediabetes including impaired fasting glucose (IFG): 100 to 125 mg/dL (5.6–6.9 mmol/L) and impaired glucose tolerance (IGT): 140 to 199 mg/dL (7.8–11 mmol/L) 2 hours post 75-g OGTT in the pretransplant period can have a connection with the occurrence of PTDM after renal transplantation (RTx).The aim of our study was to assess the benefit of performing OGTT-75 in dialyzed chronic kidney disease (stage 5) patients on the waiting list for kidney transplantation as a useful tool to prevent PTDM.

Renal Transplantation by Automatic Anastomotic Device in a Porcine Model

Automatic vascular staplers for vascular anastomoses in kidney transplantation may dramatically reduce the operative time and, in particular, warm ischemia time, thus increasing the outcome of transplantation. Ten pigs underwent kidney auto‐transplantation by automatic anastomotic device. Kidneys were collected by laparotomy with selective ligations at the renal hilum and perfused with cold storage solution. To overcome the shortage in length of renal hilum, a tract of the internal jugular vein was harvested to increase the length of the vessels. The anastomoses were totally performed by the use of the anastomotic device. On 10 kidney transplants, nine were successful and no complications occurred. Renal resistive indexes showed a slight increase in the immediate postoperative period returning normal at 10 days of follow‐up. We demonstrated the possibility to perform renal vascular anastomoses by means of an automatic anastomotic device. This instrument developed for coronary bypass surgery by virtue of the small caliber of the vessels could be adopted on a larger scale for renal transplantation. The reduced warm ischemia time needed for anastomosis may help to achieve a better outcome for the graft and expand the pool of marginal donors in renal transplantation.     

Adoptive Transfer of Renal Allograft Tolerance in a Large Animal Model

Our recent studies in an inbred swine model demonstrated that both peripheral and intra‐graft regulatory cells were required for the adoptive transfer of tolerance to a second, naïve donor‐matched kidney. Here, we have asked whether both peripheral and intra‐graft regulatory elements are required for adoptive transfer of tolerance when only a long‐term tolerant (LTT) kidney is transplanted. Nine highly‐inbred swine underwent a tolerance‐inducing regimen to prepare LTT kidney grafts which were then transplanted to histocompatible recipients, with or without the peripheral cell populations required for adoptive transfer of tolerance to a naïve kidney. In contrast to our previous studies, tolerance of the LTT kidney transplants alone was achieved without transfer of additional peripheral cells and without strategies to increase the number/potency of regulatory T cells in the donor. This tolerance was systemic, since most subsequent, donor‐matched challenge kidney grafts were accepted. These results confirm the presence of a potent tolerance‐inducing and/or tolerance‐maintaining cell population within LTT renal allografts. They suggest further that additional peripheral tolerance mechanisms, required for adoptive transfer of tolerance to a naïve donor‐matched kidney, depend on peripheral cells that, if not transferred with the LTT kidney, require time to develop in the adoptive host.     

Pancreas Transplantation in the Rat Using Lee's Technique: A Reliable Model in Experimental Microsurgery

Numerous unresolved problems, both technical and immunological, in pancreas transplantation stimulate experimental studies. Dogs have been routinely used in experimental studies but today rats are more commonly used. However, pancreas transplantation in the rat presents complex technical problems and requires a good knowledge of microsurgical techniques. In 1983 Squifflet undertook an experimental study aimed at evaluating the technical aspects of pancreas transplantation in the rat and calculating the success rates using different methods. The comparison of four methods revealed to our surprise that 100% of the rats operated on using Lee's technique had complications, with a 0% survival rate. In our study we report our experience using Lee's technique which we had the opportunity of mastering directly under the supervision of Professor Lee. We performed 100 pancreas transplantations using Lee's technique and divided our study in two phases. In the first phase we performed 70 pancreas transplantations and overall survival, after I week, was 42 rats (60%). In the second phase on 30 rats diabetes was induced by administering 70 mg/kg of streptozotocin. These 30 diabetic rats underwent pancreas transplantation and overall survival, after I week, was 25 (83.3%). We believe that our successful survival rates could probably be explained by the close collaboration between Lee and our department. Moreover, we noted the importance of constant training in obtaining better results, and in our opinion Lee's technique of pancreas transplantation is a reliable experimental model which can be used to resolve problems linked to pancreas transplantation.     

Reduction of Warm Ischemia Using a Thermal Barrier Bag in Kidney Transplantation: Study in a Pig Model

BackgroundWith recent advances in surgical technologies, minimally invasive endoscopic and robot-assisted surgical procedures have been introduced. However, prolonged warm ischemic time of the kidneys remains a concern after the organ is removed from a donor and during transplantation into a recipient. We developed a Thermal Barrier Bag (TBB) to prevent warm ischemia during transplantation. To confirm the effectiveness of the TBB, adenosine triphosphate (ATP) activity in the kidney was measured during an ex vivo warming test. An ischemia model porcine kidney was also used as the donor kidney and placed into the TBB; thereafter, the change in temperature at the time of transplantation was examined.Main FindingsThe purse-like design of the TBB efficiently suppressed heat conduction. A simulation was conducted that allowed the calculation of organ heat transfer condition. In the ex vivo experiment, temperature increases were suppressed in the group whose kidneys were placed in the TBB (30 minutes after transplantation: with TBB = 30°C, without TBB = 35°C). ATP measurements showed that the residual rate was substantially higher in the TBB group (P = .056). Moreover, a temperature suppression effect was demonstrated during the renal transplantation experiment (30 minutes after transplantation: with TBB = 27°C, without TBB = 31°C).ConclusionThe ex vivo warming experiment demonstrated that use of TBB slows down the rate of ATP decay in fresh kidneys. In addition, when an ischemic model porcine kidney was placed into the TBB and the temperature change at the time of transplantation was measured, an in vivo temperature-suppressing effect was observed.     

Induction With Basiliximab Plus Thymoglobulin Is Effective and Safe in Old-for-Old Renal Transplantation: Six-Month Results of a Prospective Clinical Study

Old-for-old renal transplantation is becoming more frequent, but the optimal immunosuppressive regimens for this transplant population are still unclear. The aim of this pilot prospective study was to evaluate the efficacy and safety of the combination of basiliximab with a short course of low-dose thymoglobulin induction therapy among a group of patients receiving kidneys from donors >60 years (OLD), compared with those receiving organs from donors <60 years (YNG). Forty-six consecutive deceased donor kidney transplant patients received induction therapy with a combination of basiliximab (20 mg IV on days 0 and 4) and thymoglobulin (200 mg total dose IV on days 0-3). As maintenance immunosuppression starting on day 4, patients received a low dose of calcineurin inhibitor and steroids. Demographic characteristics at baseline were not significantly different between the 2 groups. At 6 months, patient survival, graft survival, and acute rejection rates were similar between the YNG and OLD groups: 100% and 95%, 96% and 95%, and 8% and 0%, respectively. Patients in the OLD group showed higher serum creatinine concentrations (YNG 1.5 ± 0.3 vs OLD 1.9 ± 0.3 mg/dL; P = .0002) but not proteinuria (YNG 0.11 ± 0.11 vs OLD 0.15 ± 0.14 g/24 h; P = ns). No significant difference was evident between the 2 groups regarding infectious, hematologic, or posttransplantation lymphoproliferative disorder complications. This study showed that a combination of basiliximab and a short course of low-dose thymoglobulin provided effective and safe immunosuppression, in old-for-old renal transplantation, with good renal function without an increased risk of posttransplantation infectious or hematologic complications.     

Is There Any Role for Antithymocyte Induction in Renal Transplantation?

The use of an antibody induction agent in kidney transplantation lowers the risk of an acute rejection episode and may improve graft outcomes. Antithymocyte globulin (ATG) is the most commonly used antibody induction agent for kidney transplantation in the United States, despite its significant side effect profile and cost compared to the interleukin-2 receptor antagonists (IL2-RA). Our review suggests the IL2-RA are safe and well tolerated, and provide equal clinical benefit to ATG at a lower cost. We propose that there is insufficient evidence to justify the use of ATG induction in kidney transplantation.