Investigations relating to the induction of immunological tolerance through spleen transplantation in miniature swine

The ultimate goal in transplantation is to achieve donor-specific immunological tolerance. The induction of tolerance would result in the long-term survival of a transplanted organ without the need for continuous immunosuppressive therapy, thus avoiding its many attendant risks and complications. In this dissertation, spleen transplantation will be investigated as a method to induce immunological tolerance. In the literature, there is evidence for a tolerogenic effect of spleen transplantation in rodents. However, the relevance of this phenomenon remained to be demonstrated in large animal models and in humans. To investigate whether the approach of spleen transplantation would be clinically applicable, we developed a model in pigs. The Massachusetts General Hospital miniature swine model was chosen, based on the fact that the Major Histocompatibility Complex (MHC) is well-defined, enabling clinically-relevant donor-recipient combinations to be investigated. During the last 30 years, considerable experience in transplantation immunology has been gained in this model. In miniature swine, a transplanted spleen (a highly immunogenic organ) is rejected when no immunosuppressive therapy is given. However, even in the presence of a full MHC-mismatch between donor and recipient, the transplanted spleen is accepted when a short course of cyclosporine is administered with pre-transplant low-dose whole body (100cGy) and thymic (700cGy) irradiation. After successful spleen transplantation, mixed hematopoietic cell chimerism is induced in the blood and lymphoid organs of the recipient. Donor cells migrate from the spleen to recipient lymph nodes, thymus, and bone marrow, in the absence of graft-versus-host-disease. Meanwhile, the donor spleen is repopulated with recipient cells. Creating a state of mixed chimerism is known to be a highly-effective means of inducing immunological tolerance. When the spleen is successfully transplanted, the recipient demonstrates donor-specific T cell tolerance in vitro. After discontinuation of immunosuppression, T cells remain unresponsive to donor antigen (on CML and MLR). Regulatory T cells are detected in the circulation of the recipient, and suppress naïve T cell responses in a donor- specific manner. Thus, the recipient remains immunocompetent. We investigated whether in vivo donor-specific tolerance develops. In pigs tolerized by spleen transplantation, donor-specific kidneys survived for many months without exogenous immunosuppression, while in control pigs (without spleen transplants) the grafts were rejected within 2 weeks. The fact that donor cells engrafted in recipient bone marrow suggests that hematopoietic stem cells were present in the donor spleen. W

Post-transplantation encapsulating peritoneal sclerosis without inflammation or radiological abnormalities

Background: Post-transplantation encapsulating peritoneal sclerosis (EPS) causing bowel obstruction has been identified as a serious complication after kidney transplantation in patients previously treated with peritoneal dialysis. Systemic inflammation and abnormalities on an abdominal computed tomography (CT) scan are important hallmarks of EPS. To our knowledge, this is the first report of a case being diagnosed with late-onset post-transplantation EPS without systemic inflammation or abnormalities on a CT scan which could only be diagnosed by laparotomy. Case presentation. A 59-year old female presented because of symptoms of bowel obstruction 33 months after kidney transplantation. The patient had a 26-month history of peritoneal dialysis before her first kidney transplantation and was treated with peritoneal dialysis for 4 years before undergoing a second kidney transplantation. Physical examination was unremarkable and laboratory tests showed no signs of systemic inflammation (C-reactive protein <1 mg/L). An abdominal CT scan did not reveal any abnormalities fitting the diagnosis of EPS, except a "feces sign". Given the severity of the progressive symptoms, a diagnostic laparotomy was performed, visualizing a classical EPS. Total peritonectomy and enterolysis were performed, leading to restoration of peristalsis. Conclusion: EPS may occur several years after kidney transplantation in the absence of inflammation and typical radiological abnormalities. Obtaining a diagnosis of post-transplantation EPS is challenging, however, a low threshold for surgical exploration in case of high clinical suspicion and negative findings on the CT scan is mandatory

Systematic Surgical Assessment of Deceased-Donor Kidneys as a Predictor of Short-Term Transplant Outcomes

Background: Short-term kidney graft dysfunction is correlated with complications and it is associated with a decreased long-term survival; therefore, a scoring system to predict short-term renal transplant outcomes is warranted. Aim: The aim of this study is to quantify the impression of the organ procurement surgeon in correlation with the following kidney transplant outcomes: immediate graft function (IGF), delayed graft function (DGF), and primary nonfunction (PNF). Results are compared to factors associated with the 1-year outcome. Methods: A regional prospective pilot study was performed using deceased-donor organ assessment forms to be filled out by procurement surgeons after procurement. Data were gathered on kidney temperature, perfusion, anatomy, atherosclerosis, and overall quality. Results: Included were 90 donors who donated 178 kidneys, 166 of which were transplanted. Variables that were significantly more prevalent in the DGF-or-PNF group (n = 65) are: large kidney size (length, p = 0.008; width, p = 0.036), poor perfusion quality (p = 0.037), lower diuresis (p = 0.039), fewer hypotensive episodes (p = 0.003), and donation-after-circulatory-death donors (p = 0.017). Multivariable analysis showed that perfusion quality and kidney width significantly predicted the short-term outcome. However multivariable analysis of long-term outcomes showed that the first measured donor creatinine, kidney donor risk index, IGF vs. DGF+PNG, and kidney length predicted outcomes. Conclusions: Results show that short-term graft function and 1-year graft function indeed are influenced by different variables. DGF and PNF occur more frequently in kidneys with poor perfusion and in larger kidneys. A plausible explanation for this is that these kidneys might be insufficiently washed out, or even congested, which may predispose to DGF. These kidneys would probably benefit most from reconditioning strategies, such as machine perfusion. A scoring system including these variables might aid in decision-making towards allocation and potential reconditioning strategies

Dietary restriction and fasting arrest B and T cell development and increase mature B and T cell numbers in bone marrow

Dietary restriction (DR) delays ageing and extends life span. Both long- and short-term DR, as well as short-term fasting provide robust protection against many "neuronal and surgery related damaging phenomena" such as Parkinson's disease and ischemia-reperfusion injury. The exact mechanism behind this phenomenon has not yet been elucidated. Its antiinflammatory actions prompted us to thoroughly investigate the consequences of DR and fasting on B and T cell compartments in primary and secondary lymphoid organs of male C57Bl/6 mice. In BM we found that DR and fasting cause a decrease in the total B cell population and arrest early B cell development, while increasing the number of recirculating mature B cells. In the fasting group, a significant reduction in peripheral B cell counts was observed in both spleen and mesenteric lymph nodes (mLN). Thymopoiesis was arrested significantly at double negative DN2 stage due to fasting, whereas DR resulted in a partial arrest of thymocyte development at the DN4 stage. Mature CD3+ T cell populations were increased in BM and decreased in both spleen and mLN. Thus, DR arrests B cell development in the BM but increases the number of recirculating mature B cells. DR also arrests maturation of T cells in thymus, resulting in depletion of mature T cells from spleen and mLN while recruiting them to the BM. The functional relevance in relation to protection against organ damage needs to be determined

Attitudes among transplant professionals regarding shifting paradigms in eligibility criteria for live kidney donation

Background The transplant community increasingly accepts extended criteria live kidney donors, however, great (geographical) differences are present in policies regarding the acceptance of these donors, and guidelines do not offer clarity. The aim of this survey was to reveal these differences and to get an insight in both centre policies as well as personal beliefs of transplant professionals. Methods An online survey was sent to 1128 ESOT-members. Questions were included about several extended donor criteria; overweight/obesity, older age, vascular multiplicity, minors as donors and comorbidities; hypertension, impaired fasting glucose, kidney stones, malignancies and renal cysts. Comparisons were made between transplant centres of three regions in Europe and between Europe and other countries worldwide. Results 331 questionnaires were completed by professionals from 55 countries. Significant differences exist between regions in Europe in acceptance of donors with several extended criteria. Median refusal rate for potential live donors is 15%. Furthermore, differences are seen regarding pre-operative work-up, both in specialists who perform screening as in preoperative imaging. Conclusions Remarkably, 23.4% of transplant professionals sometimes deviate from their centre policy, resulting in more or less comparable personal beliefs regarding extended criteria. Variety is seen, proving the need for a standardized approach in selection, preferably evidence based

Global Kidney Exchange: opportunity or exploitation? An ELPAT/ESOT appraisal

This paper addresses ethical, legal, and psychosocial aspects of Global Kidney Exchange (GKE). Concerns have been raised that GKE violates the nonpayment principle, exploits donors in low- and middle-income countries, and detracts from the aim of self-sufficiency. We review the arguments for and against GKE. We argue that while some concerns about GKE are justified based on the available evidence, others are speculative and do not apply exclusively to GKE but to living donation more generally. We posit that concerns can be mitigated by implementing safeguards, by developing minimum quality criteria and by establishing an international committee that independently monitors and evaluates GKE’s procedures and outcomes. Several questions remain however that warrant further clarificati

IL-21 receptor antagonist inhibits differentiation of B cells toward plasmablasts upon alloantigen stimulation

Interaction between T follicular helper (Tfh) cells and B cells is complex and involves various pathways, including the production of IL-21 by the Tfh cells. Secretion of IL-21 results in B cell differentiation toward immunoglobulin-producing plasmablasts. In patients after kidney transplantation, the formation of alloantibodies produced by donor antigen-activated B cells are a major cause of organ failure. In this allogeneic response, the role of IL-21-producing Tfh cells that regulate B cell differentiation is unknown. Here, we tested, in an alloantigen-driven setting, whether Tfh cell help signals control B cell differentiation with its dependency on IL-21. Pre-transplantation patient PBMCs were sorted into pure CD4posCXCR5pos Tfh cells and CD19posCD27pos memory B cells and stimulated with donor antigen in the presence or absence of an IL-21 receptor (IL-21R) antagonist (αIL-21R). Donor antigen stimulation initiated expression of the activation markers inducible co-stimulator (ICOS) and programmed death 1 (PD-1) on Tfh cells and a shift toward a mixed Tfh2 and Tfh17 phenotype. The memory B cells underwent class switch recombination and differentiated toward IgM- and IgG-producing plasmablasts. In the presence of αIL-21R, a dose-dependent inhibition of STAT3 phosphorylation was measured in both T and B cells. Blockade of the IL-21R did not have an effect on PD-1 and ICOS expression on Tfh cells but significantly inhibited B cell differentiation. The proportion of plasmablasts decreased by 78% in the presence of αIL-21R. Moreover, s

Mannan-binding lectin is involved in the protection against renal ischemia/ reperfusion injury by dietary restriction

Preoperative fasting and dietary restriction offer robust protection against renal ischemia/ reperfusion injury (I/RI) in mice.We recently showed that Mannan-binding lectin (MBL), the initiator of the lectin pathway of complement activation, plays a pivotal role in renal I/RI. Based on these findings, we investigated the effect of short-term DR (30% reduction of total food intake) or three days of water only fasting on MBL in 10-12 weeks old male C57/Bl6 mice. Both dietary regimens significantly reduce the circulating levels of MBL as well as its mRNA expression in liver, the sole production site of MBL. Reconstitution of MBL abolished the protection afforded by dietary restriction, whereas in the fasting group the protection persisted. These data show that modulation of MBL is involved in the protection against renal I/RI induced by dietary restriction, and suggest that the mechanisms of protection induced by dietary restriction and fasting may be different. Copyright

Remote ischaemic conditioning and early changes in plasma creatinine as markers of one year kidney graft function-A follow-up of the CONTEXT study

BACKGROUND: Ischaemia-reperfusion injury in kidney transplantation leads to delayed graft function (DGF), which is associated with reduced long term graft function. Remote ischaemic conditioning (RIC) improved early kidney graft function in a porcine model of donation after brain death and was associated with improved long-term cardiac outcome after myocardial ischaemia. This randomised, double-blinded trial evaluated the effect of RIC on kidney graft outcome in the first year, and examined the predictive value of a new measure of initial kidney graft function, i.e. the estimated time to a 50% reduction in plasma creatinine post-transplantation (tCr50). METHODS: A total of 225 patients undergoing deceased donor kidney transplantation were randomised to RIC or a sham procedure performed prior to kidney reperfusion. Up to four repetitive cycles of five minutes of leg ischaemia and five minutes of reperfusion were given. GFR, plasma creatinine, cystatin C and neutrophil gelatinase associated lipocalin (NGAL) were measured at three and twelve months and estimated GFR was calculated using four different equations. Other secondary outcomes were identified from patient files. RESULTS: RIC did not affect GFR or other outcomes when compared to the sham procedure at three or twelve months. tCr50 correlated with one year graft function (p<0.0001 for both mGFR and eGFR estimates). In contrast, DGF i.e. "need of dialysis the first week" did not correlate significantly with one year GFR. CONCLUSION: RIC during deceased donor kidney transplantation did not improve one year outcome. However, t