Simultaneous Liver-Kidney Transplantation

Tolerogenic Nano-/Microparticle Vaccines for Immunotherapy

Autoimmune diseases, allergies, transplant rejections, generation of antidrug antibodies, and chronic inflammatory diseases have impacted a large group of people across the globe. Conventional treatments and therapies often use systemic or broad immunosuppression with serious efficacy and safety issues. Tolerogenic vaccines represent a concept that has been extended from their traditional immune-modulating function to induction of antigen-specific tolerance through the generation of regulatory T cells. Without impairing immune homeostasis, tolerogenic vaccines dampen inflammation and induce tolerogenic regulation. However, achieving the desired potency of tolerogenic vaccines as preventive and therapeutic modalities calls for precise manipulation of the immune microenvironment and control over the tolerogenic responses against the autoantigens, allergens, and/or alloantigens. Engineered nano-/microparticles possess desirable design features that can bolster targeted immune regulation and enhance the induction of antigen-specific tolerance. Thus, particle-based tolerogenic vaccines hold great promise in clinical translation for future treatment of aforementioned immune disorders. In this review, we highlight the main strategies to employ particles as exciting tolerogenic vaccines, with a focus on the particles' role in facilitating the induction of antigen-specific tolerance. We describe the particle design features that facilitate their usage and discuss the challenges and opportunities for designing next-generation particle-based tolerogenic vaccines with robust efficacy to promote antigen-specific tolerance for immunotherapy.

Simultaneous Liver-Kidney Transplantation

End-stage kidney disease (ESKD) after liver transplantation is associated with high morbidity and mortality. This increase in mortality can be offset by performing a kidney transplant at the time of the liver transplant in select cases. Accordingly, Margreiter and colleague; s performed the first simultaneous liver-kidney (SLK) transplant in 1983. The number of SLK transplants has increased by more than 300% since then. In 1990%, 1.7% of all liver transplants in the United States were SLK transplants which increased to 9.9% by 2016. This steep increase was likely due to the implementation of the model of end-stage liver disease (MELD) scoring system in 2002, which is heavily weighted by serum creatinine.

Developing simultaneous liver-kidney transplant medical eligibility criteria while providing a safety net: A 2-year review of the OPTN's allocation policy

The OPTN's simultaneous liver-kidney (SLK) allocation policy, implemented August 10, 2017, established medical eligibility criteria for adult SLK candidates and created Safety Net kidney allocation priority for liver-alone recipients with new/continued renal impairment. OPTN SLK and kidney after liver (KAL) data were analyzed (registrations as of December 31, 2019, transplants pre-policy [March 20, 2015-August 9, 2017] vs. post-policy [August 10, 2017-December 31, 2019]). Ninety-four percent of SLK registrations met eligibility criteria (99% CKD: 50% dialysis, 50% eGFR). SLK transplant volume decreased from a record 740 (2017) to 676 (2018, -9%), with a subsequent increase to 728 (2019, 1.6% below 2017 volume). For KAL listings within 1 year of liver transplant, waitlist mortality rates declined post-policy versus pre-policy (27 [95% CI = 20.6-34.7] vs. 16 [11.7-20.5]) while transplant rates increased fourfold (46 [32.2-60.0] vs. 197 [171.6-224.7]). There were 234 KAL transplants post-policy (94% Safety Net priority eligible), and no significant difference in 1-year patient/graft survival vs. kidney-alone (patient: 95.9% KAL, 97.0% kidney-alone [p = .39]; graft: 94.2% KAL, 94.6% kidney-alone [p = .81]). From pre- to post-policy, the proportion of all deceased donor kidney and liver transplants that were SLK decreased (kidney: 5.1% to 4.3%; liver: 9.7% to 8.7%). SLK policy implementation interrupted the longstanding rise in SLK transplants, while Safety Net priority directed kidneys to liver recipients in need with thus far minimal impact to posttransplant outcomes.

Current and Evolving Indications for Simultaneous Liver Kidney Transplantation

This review will discuss the etiologies of kidney disease in liver transplant candidates, provide a historical background of the prior evolution of simultaneous liver-kidney (SLK) transplant indications, discuss the current indications for SLK including Organ Procurement and Transplantation Network policies and Model for End Stage Liver Disease exception points, as well as provide an overview of the safety net kidney transplant policy. Finally, the authors explore unanswered questions and future research needed in SLK transplantation.

Outcomes of en bloc simultaneous liver-kidney transplantation compared to the traditional technique

Simultaneous liver-kidney transplantation (SLKT) is indicated for patients with end-stage liver disease (ESLD) and concurrent renal insufficiency. En bloc SLKT is an alternative to traditional separate implantations, but studies comparing the two techniques are limited. The en bloc technique maintains renal outflow via donor infrahepatic vena cava and inflow via anastomosis of donor renal artery to donor splenic artery. Comparison of recipients of en bloc (n = 17) vs traditional (n = 17) SLKT between 2013 and 2017 was performed. Recipient demographics and comorbidities were similar. More recipients of traditional SLKT were dialysis dependent (82.4% vs 41.2%, P = .01) with lower baseline pretransplant eGFR (14 vs 18, P = .01). En bloc SLKT was associated with shorter kidney cold ischemia time (341 vs 533 minutes, P < .01) and operative time (374 vs 511 minutes, P < .01). Two en bloc patients underwent reoperation for kidney allograft inflow issues due to kinking and renal steal. Early kidney allograft dysfunction (23.5% in both groups), 1-year kidney graft survival (88.2% vs 82.4%, P = 1.0), and posttransplantation eGFR were similar between groups. In our experience, the en bloc SLKT technique is safe and feasible, with comparable outcomes to the traditional method.

Liver Transplantation

The field of liver transplantation has changed since the MELD scoring system became the most widely used donor allocation tool. Due to the MELD-based allocation system, sicker patients with higher MELD scores are being transplanted. Persistent organ donor shortages remain a challenging issue, and as a result, the wait-list mortality is a persistent problem for most of the regions. This chapter focuses on deceased donor and live donor liver transplantation in patients with complications of portal hypertension. Special attention will also be placed on donor-recipient matching, perioperative management of transplant patients, and the impact of hepatic hemodynamics on transplantation.

Liver Transplantation Followed by Renal Transplantation on Extracorporeal Membrane Oxygenation: A Case Report

We report the case of a 68-year-old woman with end-stage liver disease and end-stage renal disease scheduled for simultaneous liver and kidney transplant. Intraoperatively, she became hemodynamically unstable during her liver transplant surgery, and her renal transplant had to be postponed. On the following day, she required extracorporeal membrane oxygenation and ABIOMED Impella support for managing her severe cardiovascular decompensation. At the same time, the renal transplant was conducted to use the donor kidney already allocated for this patient. The patient was successfully managed postoperatively in the cardiothoracic intensive care unit and was discharged after 2 months. This case is unique because there are no similar cases previously reported in which renal transplantation was performed with extracorporeal membrane oxygenation and Impella support following cardiogenic shock after a liver transplant.

Use of Polymeric Nanoparticle Platform Targeting the Liver To Induce Treg-Mediated Antigen-Specific Immune Tolerance in a Pulmonary Allergen Sensitization Model

Nanoparticles (NPs) can be used to accomplish antigen-specific immune tolerance in allergic and autoimmune disease. The available options for custom-designing tolerogenic NPs include the use of nanocarriers that introduce antigens into natural tolerogenic environments, such as the liver, where antigen presentation promotes tolerance to self- or foreign antigens. Here, we demonstrate the engineering of a biodegradable polymeric poly(lactic- co-glycolic acid) (PLGA) nanocarrier for the selective delivery of the murine allergen, ovalbumin (OVA), to the liver. This was accomplished by developing a series of NPs in the 200-300 nm size range as well as decorating particle surfaces with ligands that target scavenger and mannose receptors on liver sinusoidal endothelial cells (LSECs). LSECs represent a major antigen-presenting cell type in the liver capable of generating regulatory T-cells (Tregs).  In vitro exposure of LSECs to NPOVA induced abundant TGF-β, IL-4, and IL-10 production, which was further increased by surface ligands. Animal experiments showed that, in the chosen size range, NPOVA was almost exclusively delivered to the liver, where the colocalization of fluorescent-labeled particles with LSECs could be seen to increase by surface ligand decoration. Moreover, prophylactic treatment with NPOVA in OVA-sensitized and challenged animals (aerosolized inhalation) could be seen to significantly suppress anti-OVA IgE responses, airway eosinophilia, and TH2 cytokine production in the bronchoalveolar lavage fluid. The suppression of allergic airway inflammation was further enhanced by attachment of surface ligands, particularly for particles decorated with the ApoB peptide, which induced high levels of TGF-β production in the lung along with the appearance of Foxp3+ Tregs. The ApoB-peptide-coated NPs could also interfere in allergic airway inflammation when delivered postsensitization. The significance of these findings is that liver and LSEC targeting PLGA NPs could be used for therapy of allergic airway disease, in addition to the potential of using their tolerogenic effects for other disease applications.

International Liver Transplantation Society Consensus Statement on Immunosuppression in Liver Transplant Recipients

Effective immunosupression management is central to achieving optimal outcomes in liver transplant recipients. Current immunosuppression regimens and agents are highly effective in minimizing graft loss due to acute and chronic rejection but can also produce a substantial array of toxicities. The utilization of immunosuppression varies widely, contributing to the wide disparities in posttransplant outcomes reported between transplant centers. The International Liver Transplantation Society (ILTS) convened a consensus conference, comprised of a global panel of expert hepatologists, transplant surgeons, nephrologists, and pharmacologists to review the literature and experience pertaining to immunosuppression management to develop guidelines on key aspects of immunosuppression. The consensus findings and recommendations of the ILTS Consensus guidelines on immunosuppression in liver transplant recipients are presented in this article.

Liver alone or simultaneous liver-kidney transplant? Pretransplant chronic kidney disease and post-transplant outcome - a retrospective study

The new Organ Procurement and Transplant Network/United Organ Sharing Network (OPTN/UNOS) simultaneous liver-kidney transplant (SLK) policy has been implemented. The aim of this study was to review liver transplant outcomes utilizing the new SLK policy. Liver transplant alone (LTA) and SLK patients between 2009 and 2015 were reviewed. Graft survival and post-transplant kidney function were investigated among LTA patients meeting the chronic kidney disease (CKD) criteria of the new policy (LTA-CKD group). To validate our findings, we reviewed and applied our analysis to the OPTN/UNOS registry. A total of 535 patients were eligible from our series. The LTA-CKD group (n = 27) showed worse 1-year graft survival, compared with the SLK group (n = 44), but not significant (81% vs. 93%, P = 0.15). The LTA-CKD group significantly increased a risk of post-transplant dialysis (odds ratio = 5.59 [95% CI = 1.27-24.7], P = 0.02 [Ref. normal kidney function]). Post-transplant dialysis was an independent risk factor for graft loss (hazard ratio = 7.25, 95% CI = 3.3-15.91, P < 0.001 [Ref. SLK]). In the validation analysis based on the OPTN/UNOS registry, the hazard of 1-year-graft loss in the LTA-CKD group (n = 751) was 34.8% higher than the SLK group (n = 2856) (hazard ratio = 1.348, 95% CI = 1.157-1.572, P < 0.001). Indicating SLK for patients who meet the CKD criteria may significantly improve transplant outcomes.

Environmental peer pressure: CD4+ T cell help in tolerance and transplantation

The liver participates in a multitude of metabolic functions that are critical for sustaining human life. Despite constant encounters with antigenic-rich intestinal blood, oxidative stress, and metabolic intermediates, there is no appreciable immune response. Interestingly, patients undergoing orthotopic liver transplantation benefit from a high rate of graft acceptance in comparison to other solid organ transplant recipients. In fact, cotransplantation of a donor liver in tandem with a rejection-prone graft increases the likelihood of graft acceptance. A variety of players may account for this phenomenon including the interaction of intrahepatic antigen-presenting cells with CD4⁺ T cells and the preferential induction of forkhead box P3 (Foxp3) expression on CD4⁺ T cells following injurious stimuli. Ineffective insult management can cause chronic liver disease, which manifests systemically as the following: antibody-mediated disorders, ineffective antiviral and antibacterial immunity, and gastrointestinal disorders. These sequelae sharing the requirement of CD4⁺ T cell help to coordinate aberrant immune responses. In this review, we will focus on CD4⁺ T cell help due to the shared requirements in hepatic tolerance and coordination of extrahepatic immune responses. Overall, intrahepatic deviations from steady state can have deleterious systemic immune outcomes and highlight the liver's remarkable capacity to maintain a balance between tolerance and inflammatory response while simultaneously being inundated with a panoply of antigenic stimuli. Liver Transplantation 24 89-97 2018 AASLD.

En Bloc Liver Kidney Transplantation Using Donor Splenic Artery as Inflow to the Kidney: Report of Two Cases

The number of simultaneous liver-kidney transplants has been increasing. This surgery is associated with an increased risk of complications, longer duration of surgery and longer ischemia time for the renal allograft. Two patients listed for liver-kidney transplant at our center underwent en bloc combined liver-kidney transplantation using donor splenic artery as inflow. Patient 1 previously underwent cardiac catheterization that was complicated by a bleeding pseudoaneurysm of the right external iliac artery that required endovascular stenting of the external iliac artery and embolization of the inferior epigastric artery. Patient 2 was on vasopressor support and continuous renal replacement therapy at the time of transplant. In this paper, we described a novel technique of en bloc liver-kidney transplant with simultaneous reperfusion of both allografts using the donor splenic artery for renal inflow. This technique is useful for decreasing cold ischemia time and total operative time by simultaneous reperfusion of both allografts. It is a useful technical variant that can be used in patients with severe disease of the iliac arteries.