Effect of Rabbit Antithymocyte Globulin on Acute and Chronic Active Antibody-Mediated Rejection After Kidney Transplantation

Drug delivery strategies for local immunomodulation in transplantation: Bridging the translational gap

Drug delivery strategies for local immunomodulation hold tremendous promise compared to current clinical gold-standard systemic immunosuppression as they could improve the benefit to risk ratio of life-saving or life-enhancing transplants. Such strategies have facilitated prolonged graft survival in animal models at lower drug doses while minimizing off-target effects. Despite the promising outcomes in preclinical animal studies, progression of these strategies to clinical trials has faced challenges. A comprehensive understanding of the translational barriers is a critical first step towards clinical validation of effective immunomodulatory drug delivery protocols proven for safety and tolerability in pre-clinical animal models. This review overviews the current state-of-the-art in local immunomodulatory strategies for transplantation and outlines the key challenges hindering their clinical translation.

Burden of neutropenia and leukopenia among adult kidney transplant recipients: A systematic literature review of observational studies

BACKGROUND

Leukopenia and neutropenia (L/N) may affect treatment decisions, potentially resulting in poor clinical and economic outcomes among kidney transplant recipients (KTRs). The burden of L/N is poorly quantified systematically. This systematic literature review aimed to summarize the incidence of, risk factors for, and clinical and economic outcomes associated with L/N post-KT.

METHODS

We systematically searched MEDLINE, Embase, and the Cochrane Library (from database inception-June 14, 2021) and conferences (past 3 years) to identify observational studies examining epidemiology, risk factors, or outcomes associated with L/N among adult KTRs.

RESULTS

Of 2081 records, 82 studies met inclusion criteria. Seventy-three studies reported the epidemiology of L/N post-KT. Pooled incidence of neutropenia, defined as absolute neutrophil counts (ANC) <1000/μl, ranged from 13% to 48% within 1-year post-transplant; ANC <500/μl ranged from 15% to 20%. Leukopenia, defined as white blood cell counts <3500/μl, was 19% to 83%. Eleven studies reported independent risk factors associated with L/N post-KT. D+/R- cytomegalovirus status, mycophenolic acid (MPA), and tacrolimus use were the most consistent risk factors across studies. Fourteen studies reported L/N-associated clinical outcomes. We noted a trend toward a positive association between neutropenia and acute rejection/opportunistic infections. Mixed findings were noted on the association between L/N and graft failure or mortality. Dosage modifications of valganciclovir, MPA, cotrimoxazole, and anti-thymoglobulin and the need for granulocyte colony-stimulating factor (G-CSF) use were common with L/N.

CONCLUSION

Findings suggest post-transplant L/N were common and associated with frequent modifications of immunosuppressive agents, requiring G-CSF use, and rejection or opportunistic infections. Findings highlight the need for interventions to reduce risk of L/N post-KT.

Emerging local immunomodulatory strategies to circumvent systemic immunosuppression in cell transplantation

INTRODUCTION

Cell transplantation is a promising curative therapeutic strategy whereby impaired organ functions can be restored without the need for whole organ transplantation. A key challenge in allotransplantation is the requirement for life-long systemic immunosuppression to prevent rejection, which is associated with serious adverse effects such as increased risk of opportunistic infections and the development of neoplasms. This challenge underscores the urgent need for novel strategies to prevent graft rejection while abrogating toxicity-associated adverse events.

AREAS COVERED

We review recent advances in immunoengineering strategies for localized immunomodulation that aim to support allograft function and provide immune tolerance in a safe and effective manner.

EXPERT OPINION

Immunoengineering strategies are tailored approaches for achieving immunomodulation of the transplant microenvironment. Biomaterials can be adapted for localized and controlled release of immunomodulatory agents, decreasing the effective dose threshold and frequency of administration. The future of transplant rejection management lies in the shift from systemic to local immunomodulation with suppression of effector and activation of regulatory T cells, to promote immune tolerance.

Clinical effect of rabbit anti-thymocyte globulin for chronic active antibody-mediated rejection after kidney transplantation

Chronic active antibody-mediated rejection (CAAMR) is a frequent cause of late graft loss. However, effective treatment for CAAMR after kidney transplantation has not yet been established. Here, we present the case of a kidney transplant recipient who recovered from CAAMR after administration of rabbit anti-thymocyte globulin. A 61-year-old man underwent ABO-compatible living-donor kidney transplantation for end-stage kidney disease; the kidney was donated by his wife. Five years after the transplant, the patient's serum creatinine level and urine protein-to-creatinine ratio increased. He was subsequently diagnosed with CAAMR based on the kidney allograft biopsy and the presence of donor-specific human leukocyte antigen antibodies. Rabbit anti-thymocyte globulin treatment was administered following steroid pulse therapy. Subsequently, his serum creatinine levels and urine protein to creatinine ratio improved. There was also an improvement in the pathological findings seen on biopsy and the mean fluorescence intensity of donor-specific antibodies. In conclusion, this report describes the case of a kidney transplant recipient who developed CAAMR, treated using rabbit anti-thymocyte globulin. This strategy might be a viable treatment option for CAAMR after a kidney transplant.

Outcomes among CMV-mismatched and highly sensitized kidney transplants recipients who develop neutropenia

Limited data exist on the incidence and clinical outcomes of neutropenia among kidney transplant recipients. Our study included 572 adults who received a kidney transplant at the University of California, San Francisco Medical Center between 2012 and 2018, and were CMV-mismatched or had a PRA ≥ 80%. Recipients with HIV, Hepatitis B and C, and primary non-function were excluded. Participants were followed for at least one year after transplantation. Neutropenia was defined as absolute neutrophil count < 1000 cells/μL. Cox proportional hazards regression models using neutropenia as a time-varying predictor were used to determine the risk of mycophenolic acid and valganciclovir changes, rejection, hospitalizations and use of granulocyte colony stimulating factor. Models were adjusted for demographics and transplant characteristics. Mean follow-up was 3.7 (SD, 1.8) years. The mean age of the cohort was 50.4 (13.1) years, and 57.5% were female. A total of 208 (36.3%) participants had neutropenia. Neutropenia was associated with an increased risk of valganciclovir or MPA dose reductions or discontinuations [adjusted hazard ratio, aHR: 7.78, 95% CI: 4.73- 12.81], rejection [aHR 2.00, 95% CI: 1.10-3.64] and hospitalizations [aHR 3.32, 95% CI: 2.12-5.19]. Neutropenia occurs frequently after kidney transplantation and leads to more medication changes and adverse clinical outcomes. This article is protected by copyright. All rights reserved.

Treatment of Chronic Active Antibody-mediated Rejection With Pulse Steroids, IVIG, With or Without Rituximab is Associated With Increased Risk of Pneumonia

Background.

The risk of infection associated with specific treatments of chronic active antibody-mediated rejection (cAMR) after kidney transplantation remains unknown.

Methods.

This was a single-center study of kidney transplant recipients treated with pulse steroids, intravenous immunoglobulin (IVIG) ± rituximab for biopsy-confirmed cAMR. The control group consisted of age- and race-matched patients who underwent donor-specific antibody-based protocol biopsies but had no rejection. We collected data on BK virus (BKV), cytomegalovirus (CMV), urinary tract infection (UTI), and pneumonia postbiopsy.

Results.

There were 49 patients in each group. In those with cAMR, 21 (43%) were treated with steroids, IVIG, and rituximab; the remaining received steroids and IVIG only. The risk of graft failure was greater in the cAMR group [22 (45%) vs. 3 (6%), P < 0.001]. Kaplan-Meier analyses demonstrated a significantly greater risk of pneumonia in the cAMR group (P = 0.02). This was confirmed by multivariable Cox regression analyses [Hazard ratio (HR) = 6.04, P = 0.027, 95% CI, 1.22-29.75]. None of the patients with pneumonia were affected by opportunistic pathogens. Additionally, the risk of CMV, UTI, and BKV was not increased. Rituximab was not independently associated with any of the infections studied.

Conclusions.

Treatment of cAMR, but not rituximab, was associated with a 6-fold increased risk of pneumonia. Additional studies are needed to determine the safety and efficacy of prolonged antimicrobial prophylaxis and monitoring strategies, including for hypogammaglobulinemia, to reduce the risk of pneumonia following the treatment of cAMR.

Tailored immunosuppression after kidney transplantation - a single center real-life experience

Background

Kidney allograft survival continuously improved with introduction of novel immunosuppressants. However, also immunologically challenging transplants (blood group incompatibility and sensitized recipients) increase. Between 2006 and 2008, a new tailored immunosuppression scheme for kidney transplantation was implemented at the University Hospital in Zurich, together with an ABO-incompatible transplant program and systematic pre- and posttransplant anti-human leukocyte antigen (HLA) antibody screening by Luminex technology. This study retrospectively evaluated the results of this tailored immunosuppression approach with a particular focus on immunologically higher risk transplants.

Methods

A total of 204 consecutive kidney transplantations were analyzed, of whom 14 were ABO-incompatible and 35 recipients were donor-specific anti-HLA antibodies (DSA) positive, but complement-dependent cytotoxicity crossmatch (CDC-XM) negative. We analyzed patient and graft survival, acute rejection rates and infectious complications in ABO-compatible versus -incompatible and in DSA positive versus negative patients and compared those with a historical control group.

Results

Overall patient, death-censored allograft survival and non-death-censored allograft survival at 4 years were 92, 91 and 87%, respectively. We found that (1) there were no differences between ABO-compatible and -incompatible and between DSA positive and DSA negative patients concerning acute rejection rate and graft survival; (2) compared with the historical control group there was a significant decrease of acute rejection rates in sensitized patients who received an induction with thymoglobulin; (3) there was no increased rate of infection among the patients who received induction with thymoglobulin compared to no induction therapy.

Conclusions

We observed excellent overall mid-term patient and graft survival rates with our tailored immunosuppression approach. Induction with thymoglobulin was efficient and safe in keeping rejection rates low in DSA positive patients with a negative CDC-XM.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12882-020-02137-5.

COVID-19 pneumonia in kidney transplant recipients: Focus on immunosuppression management

Background

The coronavirus disease of 2019, also known as COVID‐19, has been declared a global pandemic. Significant controversies exist regarding treatment modalities for this novel disease, especially in immunocompromised patients. Experience with management of COVID‐19 in kidney transplant recipients is scarce; effects of this virus on immunosuppressed individuals are not well understood.

Methods

We identified 30 renal transplant recipients with confirmed COVID‐19 pneumonia who were admitted to inpatient between March 2020 and April 2020. All patients received a 5‐day course of hydroxychloroquine and azithromycin; half of the patients received methylprednisolone. During hospitalization, calcineurin inhibitors and antimetabolites were held; prednisone was continued.

Results

Clinical presentation of flu‐like symptoms was similar to those in the general population. Hyponatremia, lymphopenia, acute kidney injury, and elevated inflammatory markers were common. Over the course of follow‐up, 23 have been discharged home with a functioning allograft and in stable condition; 4 experienced acute kidney injury requiring renal replacement therapy; 7 patients were intubated, and 6 expired. The mortality rate in our cohort was 20%.

Conclusion

Our findings described the characteristics and outcomes of this highly fatal illness in a multi‐ethnic kidney transplant cohort, with insights on immunosuppression management that could further our understanding of this unique disease in immunocompromised populations.