Steroid pretreatment of organ donors does not impact on early rejection and long-term kidney allograft survival: Results from a multicenter randomized, controlled trial

Innate immune modulation in transplantation: mechanisms, challenges, and opportunities

Organ transplantation is characterized by a sequence of steps that involve operative trauma, organ preservation, and ischemia-reperfusion injury in the transplant recipient. During this process, the release of damage-associated molecular patterns (DAMPs) promotes the activation of innate immune cells via engagement of the toll-like receptor (TLR) system, the complement system, and coagulation cascade. Different classes of effector responses are then carried out by specialized populations of macrophages, dendritic cells, and T and B lymphocytes; these play a central role in the orchestration and regulation of the inflammatory response and modulation of the ensuing adaptive immune response to transplant allografts. Organ function and rejection of human allografts have traditionally been studied through the lens of adaptive immunity; however, an increasing body of work has provided a more comprehensive picture of the pivotal role of innate regulation of adaptive immune responses in transplant and the potential therapeutic implications. Herein we review literature that examines the repercussions of inflammatory injury to transplantable organs. We highlight novel concepts in the pathophysiology and mechanisms involved in innate control of adaptive immunity and rejection. Furthermore, we discuss existing evidence on novel therapies aimed at innate immunomodulation and how this could be harnessed in the transplant setting.

Current status of glucocorticoid usage in solid organ transplantation

Glucocorticoids (GCs) have been the mainstay of immunosuppressive therapy in solid organ transplantation (SOT) for decades, due to their potent effects on innate immunity and tissue protective effects. However, some SOT centers are reluctant to administer GCs long-term because of the various related side effects. This review summarizes the advantages and disadvantages of GCs in SOT. PubMed and Scopus databases were searched from 2011 to April 2021 using search syntaxes covering “transplantation” and “glucocorticoids”. GCs are used in transplant recipients, transplant donors, and organ perfusate solution to improve transplant outcomes. In SOT recipients, GCs are administered as induction and maintenance immunosuppressive therapy. GCs are also the cornerstone to treat acute antibody- and T-cell-mediated rejections. Addition of GCs to organ perfusate solution and pretreatment of transplant donors with GCs are recommended by some guidelines and protocols, to reduce ischemia-reperfusion injury peri-transplant. GCs with low bioavailability and high potency for GC receptors, such as budesonide, nanoparticle-mediated targeted delivery of GCs to specific organs, and combination use of dexamethasone with inducers of immune-regulatory cells, are new methods of GC application in SOT patients to reduce side effects or induce immune-tolerance instead of immunosuppression. Various side effects involving different non-targeted organs/tissues, such as bone, cardiovascular, neuromuscular, skin and gastrointestinal tract, have been noted for GCs. There are also potential drug-drug interactions for GCs in SOT patients.

Steroid pretreatment of deceased donors and liver allograft function - Ten years follow-up of a blinded randomized placebo controlled trial

BACKGROUND

Within the last decade numerous attempts have been reported in order to expand the donor pool and alleviate organ shortage in the setting of liver transplantation. Aim of this blinded randomized controlled trial was to evaluate the effect of donor steroid pretreatment on outcomes after liver transplantation.

METHODS

We performed an international, multi-center double-blinded randomized placebo controlled trial. Donors received 1000 mg methylprednisone or placebo before organ procurement. Primary endpoint were patient and graft survival. Secondary end points were rate of BPAR and liver functions trajectories after transplantation. Follow up was 10 years.

RESULTS

There was no effect of steroid pretreatment vs. placebo on overall patient survival (50% vs. 46%, p = n.s.) as well as graft survival (47% vs. 51%, p= n.s.). Further donor steroid pretreatment did not alter the rate of biopsy proven acute rejections (34% steroid group vs. 36% placebo, p = n.s.). Evaluating short term and long term graft function, steroid pretreatment had minor effect on immediate liver function trajectories within the first 2 weeks after transplantation. This was not seen in long-term follow up.

CONCLUSION

In conclusion we found no evidence that donor steroid pretreatment translates in improved outcomes after liver transplantation.

Outcome measures in solid organ donor management research: a systematic review

AIM

We systematically reviewed published outcome measures across randomised controlled trials (RCTs) of donor management interventions.

METHODS

The systematic review was conducted in accordance with recommendations by the Cochrane Handbook and Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement. We searched MEDLINE, Embase, CENTRAL, Web of Science, and trial databases from 1980 to February 2021 for RCTs of donor management interventions.

RESULTS

Twenty-two RCTs (n=3432 donors) were included in our analysis. Fourteen RCTs (63.6%) reported a primary outcome relating to a single organ only. Eight RCTs primarily focused on aspects of donor optimisation in critical care. Thyroid hormones and methylprednisolone were the most commonly evaluated interventions (five and four studies, respectively). Only two studies, focusing on single organs (e.g. kidney), evaluated outcomes relating to other organs. The majority of studies evaluated physiological or biomarker-related outcomes. No study evaluated recipient health-related quality of life. Only one study sought consent from potential organ recipients.

CONCLUSIONS

The majority of RCTs evaluating donor management interventions only assessed single-organ outcomes or effects on donor stability in critical care. There is a need for an evaluation of patient-centred recipient outcomes and standardisation and reporting of outcome measures for future donor management RCTs.

Renal Delivery of Pharmacologic Agents During Machine Perfusion to Prevent Ischaemia-Reperfusion Injury: From Murine Model to Clinical Trials

Donor organ shortage still remains a serious obstacle for the access of wait-list patients to kidney transplantation, the best treatment for End-Stage Kidney Disease (ESKD). To expand the number of transplants, the use of lower quality organs from older ECD or DCD donors has become an established routine but at the price of increased incidence of Primary Non-Function, Delay Graft Function and lower-long term graft survival. In the last years, several improvements have been made in the field of renal transplantation from surgical procedure to preservation strategies. To improve renal outcomes, research has focused on development of innovative and dynamic preservation techniques, in order to assess graft function and promote regeneration by pharmacological intervention before transplantation. This review provides an overview of the current knowledge of these new preservation strategies by machine perfusions and pharmacological interventions at different timing possibilities: in the organ donor, ex-vivo during perfusion machine reconditioning or after implementation in the recipient. We will report therapies as anti-oxidant and anti-inflammatory agents, senolytics agents, complement inhibitors, HDL, siRNA and H2S supplementation. Renal delivery of pharmacologic agents during preservation state provides a window of opportunity to treat the organ in an isolated manner and a crucial route of administration. Even if few studies have been reported of transplantation after ex-vivo drugs administration, targeting the biological pathway associated to kidney failure (i.e. oxidative stress, complement system, fibrosis) might be a promising therapeutic strategy to improve the quality of various donor organs and expand organ availability.

Perioperative Perfusion of Allografts with Anti-Human T-lymphocyte Globulin Does Not Improve Outcome Post Liver Transplantation-A Randomized Placebo-Controlled Trial

Due to the lack of suitable organs transplant surgeons have to accept unfavorable extended criteria donor (ECD) organs. Recently, we demonstrated that the perfusion of kidney organs with anti-human T-lymphocyte globulin (ATLG) prior to transplantation ameliorates ischemia-reperfusion injury (IRI). Here, we report on the results of perioperative ATLG perfusion in a randomized, single-blinded, placebo-controlled, feasibility trial (RCT) involving 30 liver recipients (LTx). Organs were randomly assigned for perfusion with ATLG/Grafalon^® (AP) (n = 16) or saline only (control perfusion = CP) (n = 14) prior to implantation. The primary endpoint was defined as graft function reflected by aspartate transaminase (AST) values at day 7 post-transplantation (post-tx). With respect to the primary endpoint, no significant differences in AST levels were shown in the intervention group at day 7 (AP: 53.0 ± 21.3 mg/dL, CP: 59.7 ± 59.2 mg/dL, p = 0.686). Similarly, exploratory analysis of secondary clinical outcomes (e.g., patient survival) and treatment-specific adverse events revealed no differences between the study groups. Among liver transplant recipients, pre-operative organ perfusion with ATLG did not improve short-term outcomes, compared to those who received placebo perfusion. However, ATLG perfusion of liver grafts was proven to be a safe procedure without the occurrence of relevant adverse events.

Donor pretreatment and machine perfusion: current views

PURPOSE OF REVIEW

To summarise recently published studies of donor pretreatment and machine perfusion strategies in kidney transplantation.

RECENT FINDINGS

The sparsity of donor pretreatment trials has resulted in the re-analysis of already existing data, and RCTs are urgently needed to reinvigorate this aspect of donor research. Uncontrolled donation after circulatory death kidney transplantation has the highest risk of delayed graft function and graft failure, and recent studies have reported that normothermic regional perfusion improves graft function and survival in this setting. Hypothermic machine perfusion reduces delayed graft function following deceased donor kidney transplantation across donor types but unanswered questions still remain regarding its use. The use of oxygenated hypothermic machine perfusion appears to improve graft function in controlled donation after circulatory death mediated by a reduction in acute rejection. Ex-situ normothermic perfusion is emerging and while technically challenging it may facilitate the delivery of pretreatments.

SUMMARY

RCTs are urgently needed to reinvigorate research into donor pretreatment and to establish the place of specific preservation techniques in deceased donor kidney transplantation.

Renal Procurement: Techniques for Optimizing the Quality of the Graft in the Cadaveric Setting

PURPOSE OF REVIEW

Kidney transplantation is the best treatment for end-stage renal disease. However, due to organ shortage, suboptimal grafts are increasingly being used.

RECENT FINDINGS

We carried out a review on the methods and techniques of organ optimization in the cadaveric setting. Donor care is the first link in a chain of care. Right after brain death, there is a set of changes, of which hormonal and hemodynamic changes are the most relevant. Several studies have been conducted to determine which drugs to administer, although in most cases, the results are not definitive. The main goal seems rather achieve a set of biochemical and hemodynamic objectives. The ischemia-reperfusion injury is a critical factor for kidney damage in transplantation. One of the ways found to deal with this type of injury is preconditioning. Local and remote ischemic preconditioning has been studied for various organs, but studies on the kidney are scarce. A new promising area is pharmacological preconditioning, which is taking its first steps. Main surgical techniques were established in the late twentieth century. Some minor new features have been introduced to deal with anatomical variations or the emergence of donation after circulatory death. Finally, after harvesting, it is necessary to ensure the best conditions for the kidneys until the time of transplantation. Much has evolved since static cold preservation, but the best preservation conditions are yet to be determined. Conservation in the cold has come to be questioned, and great results have appeared at temperatures closer to physiological.

Steroid pretreatment of organ donors does not impact on early rejection and long-term kidney allograft survival: Results from a multicenter randomized, controlled trial

Steroid pretreatment of deceased donors reduces inflammation in allografts and is recommended by organ procurement guidelines. The impact on long-term graft outcome, however, remains elusive. In this multicenter randomized controlled trial, 306 deceased donors providing organs for 455 renal transplant recipients were randomized to 1000 mg of methylprednisolone or placebo prior to organ procurement (ISRCTN78828338). The incidence of biopsy-confirmed rejection (Banff>1) at 3 months was 23 (10%) in the steroid group and 26 (12%) in the placebo group (P = .468). Five-year functional graft survival was 84% and 82% for the steroid group and placebo group, respectively (P-value = .941). The hazard ratio of functional graft loss was 0.90 (95% confidence interval 0.57-1.42, P = .638) for steroid vs placebo in a multivariate Cox model. We did not observe effect modification by any of the predictors of graft survival and treatment modality. A robust sandwich estimate was used to account for paired grafts of some donors. The mean estimated GFR at 5 years was 47 mL/min per 1.73 m² in the steroid group and 48 mL/min per 1.73 m² in the placebo group (P = .756). We conclude that steroid pretreatment does not impact on long-term graft survival. In a donor population with higher risk of delayed graft function, however, repetitive and higher doses of steroid treatment may result in different findings.