Renal Transplant Immunosuppression Impairs Natural Killer Cell Function In Vitro and In Vivo

Background: Despite an increasing awareness of the importance of innate immunity, the roles of natural killer (NK) cells in transplant rejection and antiviral and cancer immunity during immunosuppression have not been clearly defined. Methods: To address this issue we have developed a quantitative assay of NK cell function that can be used on clinical samples and have studied the influence of immunosuppression on NK cell function. NK cell degranulation and intracellular interferon (IFN)-c production were determined by flow cytometry of peripheral blood samples. Results: Overnight ex vivo treatment of peripheral blood cells from healthy controls with ciclosporin or tacrolimus inhibited NK cell degranulation and IFN-c production in a dose-dependent manner. A similar impairment of function was seen in NK cells from patients treated in vivo with calcineurin inhibitors. In the early post-transplant period, there was a variable reduction of NK cell counts after treatment with alemtuzumab and basiliximab. Conclusions: The functional inhibition of NK cells in early transplant patients coincides with the period of maximum susceptibility to viral infections. The ability to assay NK cell function in clinical samples allows assessment of the impact of immunosuppressio

Nouvelles stratégies immunosuppressives en transplantation

International audienceImmunosuppressive agents have enabled the rise of allogenic renal transplantation in the last 50 years. However, several issues remain to be solved. Calcineurin inhibitors, the cornerstone of immunosuppressive strategies, are associated with nephrotoxicity. Immunosuppressive regimens currently used do not specifically target the allo-immune response and thus favor cancers and infections. Most immunosuppressive agents target T cell activation and are not efficient enough to prevent allo-immunization in the long term. Finally, antibody mediated rejections favored by the emergence of anti-human leukocyte antigen donor specific antibodies strongly affect allograft survival. There are few validated treatments for antibody-mediated rejection (plasma exchange, intravenous immunoglobulin). The research of new maintenance long-term immunosuppressive agents focuses on costimulation blockade (lymphocyte activation). Agents inhibiting CD40-CD40 ligand interaction may enable a good control of both T and B cells responses. Anti-CD28 antibodies may promote regulatory T cells. Agents targeting this costimulation pathways are currently evaluated in clinical trials. Immunosuppressive agents for ABMR treatment are scarce since anti-CD20 agent rituximab and proteasome inhibitor bortezomib have failed to demonstrate an interest in ABMR. New drugs focusing on antibodies removal (Imlifidase), B cell and plasmablasts activation (anti-IL-6/IL-6R, anti-CD38…) and complement inhibition are in the pipeline, with the challenge of their evaluation in such an heterogeneous pathology. Lastly, innovative therapeutic strategies to enable transplant tolerance are being developed, based on stem cell transplantation, mesenchymal cells or regulatory cells.e développement d’agents immunosuppresseurs a permis l’essor de la transplantation rénale depuis 50 ans. Les inhibiteurs de calcineurine, à la base des stratégies immunosuppressives actuelles, sont associés à une néphrotoxicité importante. Ces traitements ne sont pas spécifiques de la réponse allo-immune et sont associés à un risque majoré d’infections et de cancers. Enfin, les traitements utilisés ciblent principalement les lymphocytes T et ne préviennent pas suffisamment le développement des anticorps anti-HLA, associés aux rejets médiés par les anticorps et cause majeure de perte des transplants au long cours. Le développement de nouveau traitements immunosuppresseurs reste donc un enjeu majeur en transplantation. Une voie prometteuse de développement de nouveaux immunosuppresseurs est le blocage de la costimulation (activation lymphocytaire). Les agents inhibant l’interaction CD40-CD40 ligands permettraient de contrôler à la fois la réponse allogénique T et B. Les anticorps anti-CD28 permettraient le développement de cellules T régulatrices. Plusieurs essais cliniques évaluant ces différents agents sont en cours. Les traitements validés en cas de rejet médié par les anticorps sont peu nombreux (échanges plasmatiques, immunoglobulines intraveineuses). Les traitements en cours de développement reposent sur l’élimination des anticorps (Imlifidase), l’inhibition de l’activation des lymphocytes B et des plasmocytes (anti-IL-6/IL-6R, anti-CD38…), l’inhibition du complément. Leur validation est rendue difficile par l’hétérogénéité des phénotypes de ce type de rejets. Enfin, des stratégies thérapeutiques innovantes afin d’obtenir une tolérance du transplant sont en cours de développement, basées sur la thérapie cellulaire (greffe de cellules souches, cellules mésenchymateuses, cellules régulatrices)

Preclinical Efficacy and Immunological Safety of FR104, an Antagonist Anti-CD28 Monovalent Fab′ Antibody

International audienceAntagonist anti-CD28 antibodies prevent T cell cos-timulation and differentiate from CTLA4Ig since they cannot block CTLA-4 and PDL-1 coinhibitory signals. They demonstrated efficacy in suppressing effector T cells while enhancing regulatory T cells function and immune tolerance. However, anti-CD28 antibodies devoid of immunotoxicity and with a good pharma-cokinetic profile have not yet been developed. Here, we describe FR104, a novel humanized pegylated anti-CD28 Fab antibody fragment presenting a long elimination half-life in monkeys. In vitro, FR104 failed to induce human T cell proliferation and cytokines secretion, even in the presence of anti-CD3 antibodies or when cross-linked with secondary antibodies. Furthermore , in humanized NOD/SCID mice adoptively transferred with human PBMC, whereas superagonist and divalent antibodies elicited rapid cytokines secretion and human T cell activation, FR104 did not. These humanized mice developed a florid graft-versus-host disease, which was prevented by administration of FR104 in a CTLA4-dependent manner. Interestingly, administration of high doses of CTLA4-Ig was ineffective to prevent GVHD, whereas administration of low doses was partially effective. In conclusion, we demonstrated that FR104 is devoid of agonist activity on human T cells and thus compatible with a clinical development that might lead to higher therapeutic indexes, by sparing CTLA-4, as compared to CD80/CD86 antagonists

Novel Organ Perfusion and Preservation Strategies in Controlled Donation After Circulatory Death in Pancreas and Kidney Transplantation

International audienceBackground. Kidney and pancreatic transplants from controlled donation after circulatory death donors are vulnerable to ischemia-reperfusion injuries. In this context of transplant shortage, there is a need to optimize the function of these transplants and to develop novel perfusion and preservation strategies in controlled donation after circulatory death in kidney and pancreatic transplants. In Situ Perfusion and Preservation Strategies. In situ regional normothermic perfusion improves the outcome of kidney transplants from controlled donation after circulatory death and provides equivalent results for the kidney from brain-dead donors. In situ regional normothermic perfusion is under investigation for pancreatic transplants. Ex Situ Perfusion and Preservation Strategies. Perfusion on hypothermic machine perfusion is highly recommended for the kidney from controlled donation after cardiac death. Hypothermic oxygenated perfusion machine decreases the rate of graft rejection and graft failure in kidney transplantation. Ex situ normothermic perfusion is an easy way to assess renal function. In the future, kidney transplants could benefit from drug therapy during ex situ normothermic perfusion. In pancreas transplantation, hypothermic machine perfusion and ex situ normothermic perfusion present encouraging results in preclinical studies

What is the evidence for oxygenation during kidney preservation for transplantation in 2021? A scoping review

International audiencePurpose: The main objective of static cold storage is to reduce cellular metabolic demands to extend the period of ischaemia prior to transplantation. Hypothermia does not halt metabolism and the absence of oxygen causes a cellular shift toward anaerobic respiratory pathways. There is emerging evidence that the introduction of oxygenation during organ preservation may help ameliorate the degree of ischaemia reperfusion injury and improve post-transplantation outcomes. This review aims to appraise and summarise all published literature that utilises oxygenation to improve kidney preservation for purposes of transplantation.Methods: We performed a scoping review of the literature using the bibliographic databases Embase and MEDLINE. The final date for searches was 20 March 2021. All research studies included were those that reported oxygen delivery during kidney preservation as well as providing a description of the oxygenation technique.Results: 17 human and 48 animal studies met the inclusion criteria. The oxygen delivery methods investigated included hypothermic oxygenated machine perfusion (HOPE), oxygen carriers, two-layer method, venous systemic persufflation, hyperbaric oxygenation, normothermic machine perfusion and sub-normothermic machine perfusion. The COMPARE trial was the only study carried out with the most methodological robustness being a randomised, double blind, controlled, phase III trial that investigated the efficacy of HOPE versus HMP.Conclusion: A variety of studies reflect the evolution of oxygenation with useful lessons and encouraging outcomes. The first in human studies investigating HOPE and oxygen carriers are most robustly investigated strategies for oxygenation during kidney preservation and are, therefore, the best clinical references