Age-associated decrease in de novo donor-specific antibodies in renal transplant recipients reflects changing humoral immunity

The Clinical Utility of Post-Transplant Monitoring of Donor-Specific Antibodies in Stable Renal Transplant Recipients: A Consensus Report With Guideline Statements for Clinical Practice

Solid phase immunoassays improved the detection and determination of the antigen-specificity of donor-specific antibodies (DSA) to human leukocyte antigens (HLA). The widespread use of SPI in kidney transplantation also introduced new clinical dilemmas, such as whether patients should be monitored for DSA pre- or post-transplantation. Pretransplant screening through SPI has become standard practice and DSA are readily determined in case of suspected rejection. However, DSA monitoring in recipients with stable graft function has not been universally established as standard of care. This may be related to uncertainty regarding the clinical utility of DSA monitoring as a screening tool. This consensus report aims to appraise the clinical utility of DSA monitoring in recipients without overt signs of graft dysfunction, using the Wilson & Junger criteria for assessing the validity of a screening practice. To assess the evidence on DSA monitoring, the European Society for Organ Transplantation (ESOT) convened a dedicated workgroup, comprised of experts in transplantation nephrology and immunology, to review relevant literature. Guidelines and statements were developed during a consensus conference by Delphi methodology that took place in person in November 2022 in Prague. The findings and recommendations of the workgroup on subclinical DSA monitoring are presented in this article.

Children Are Not Small Adults: Similarities and Differences in Renal Transplantation Between Adults and Pediatrics

Kidney transplantation is the treatment of choice for all patients with end-stage kidney disease, including pediatric patients. Graft survival in pediatrics was lagging behind adults, but now is comparable with the adult cohort. Although many of the protocols have been adopted from adults, there are issues unique to pediatrics that one should be aware of to take care of this population. These issues include recipient size consideration, increased incidence of viral infections, problems related to growth, common occurrence of underlying urological issues, and psychosocial issues. This article addresses the similarities and differences in renal transplantation, from preparing a patient for transplant, the transplant process, to post-transplant complications.

The aging of the immune system and its implications for transplantation

By the last third of life, most mammals, including humans, exhibit a decline in immune cell numbers, immune organ structure, and immune defense of the organism, commonly known as immunosenescence. This decline leads to clinical manifestations of increased susceptibility to infections, particularly those caused by emerging and reemerging microorganisms, which can reach staggering levels-infection with SARS-CoV-2 has been 270-fold more lethal to older adults over 80 years of age, compared to their 18-39-year-old counterparts. However, while this would be expected to be beneficial to situations where hyporeactivity of the immune system may be desirable, this is not always the case. Here, we discuss the cellular and molecular underpinnings of immunosenescence as they pertain to outcomes of solid organ and hematopoietic transplantation.

Role of therapeutic plasma exchange in acute humoral rejection patients undergoing live-related renal transplantation: A single-center experience

BACKGROUND AND AIM:

Renal transplantation (RT) is the most successful and ideal renal replacement therapy for end-stage renal disease patients. Renal allograft rejection has always been one of the major barriers in successful RT. Our aim was to report the role of therapeutic plasma exchange (TPE) in acute humoral rejection (AHR) patients who underwent live-related RT (LRRT) and their renal allograft outcome at our center.

MATERIALS AND METHODS:

A prospective observational study was conducted from July 1, 2014, to December 31, 2016. Patients with biopsy-proven AHR and treated with TPE along with other lines of treatment after undergoing LRRT were included in the study. ABO-incompatible individuals, pediatric patients, and patients undergoing second transplants were excluded from the study. Clinical history, donor and graft details, management, and patient and graft survival were noted.

RESULTS:

Of the 1608 patients who underwent LRRT, 49 (37 males, 76%; 12 females, 24%; mean age 39.5 ± 13.3 years) had biopsy-proven AHR (3.04%) and were treated with TPE. A total of 281 TPEs were performed with an average of 5.7 TPE/patient (range 2–12). Of the 49 patients, 38 patients (78%) with favorable response underwent 213 (75.8%) TPEs (average of 5.6 TPE/patient; range: 2–12), whereas 11 patients (22%) with unfavorable response underwent 68 (24.2%) TPEs (average of 6.2 TPE/patient; range: 3–8). Blood urea (P = 0.012) and serum creatinine (P = 0.038) levels at the time of rejection were significant predictors of response to TPE therapy. The average length of stay in our study population was 33 ± 22 days. Six months posttransplant, the patient and graft survival were 93.3% and 89.5%, whereas at 12 months, they were 89.3% and 81.5%, respectively.

CONCLUSION:

TPE is a safe and effective adjunct therapy for treating AHR patients.

Immunosuppression Considerations for Older Kidney Transplant Recipients

PURPOSE OF REVIEW

While kidney transplantation improves the long-term survival of the majority of patients with end-stage kidney disease (ESKD), age-related immune dysfunction and associated comorbidities make older transplant recipients more susceptible to complications related to immunosuppression. In this review, we discuss appropriate management of immunosuppressive agents in older adults to minimize adverse events, avoid acute rejection, and maximize patient and graft survival.

RECENT FINDINGS

Physiological changes associated with senescence can impact drug metabolism and increase the risk of posttransplant infection and malignancy. Clinical trials assessing the safety and efficacy of immunosuppressive agents in older adults are lacking. Recent findings from U.S. transplant registry-based studies suggest that risk-adjusted death-censored graft failure is higher among older patients who received antimetabolite avoidance, mammalian target of rapamycin inhibitor (mTORi)-based, and cyclosporine-based regimens. Observational data suggest that risk-adjusted mortality may be increased in older patients who receive mTORi-based and cyclosporine-based regimens but lower in those managed with T-cell induction and maintenance steroid avoidance/withdrawal.

SUMMARY

Tailored immunosuppression management to improve patient and graft survival in older transplant recipients is an important goal of personalized medicine. Lower intensity immunosuppression, such as steroid-sparing regimens, appear beneficial whereas mTORi- and cyclosporine-based maintenance are associated with greater potential for adverse effects. Prospective clinical trials to assess the safety and efficacy of immunosuppression agents in older recipients are urgently needed.

Complement Components in the Diagnosis and Treatment after Kidney Transplantation-Is There a Missing Link?

Currently, kidney transplantation is widely accepted as the renal replacement therapy allowing for the best quality of life and longest survival of patients developing end-stage renal disease. However, chronic transplant rejection, recurrence of previous kidney disease or newly acquired conditions, or immunosuppressive drug toxicity often lead to a deterioration of kidney allograft function over time. Complement components play an important role in the pathogenesis of kidney allograft impairment. Most studies on the role of complement in kidney graft function focus on humoral rejection; however, complement has also been associated with cell mediated rejection, post-transplant thrombotic microangiopathy, the recurrence of several glomerulopathies in the transplanted kidney, and transplant tolerance. Better understanding of the complement involvement in the transplanted kidney damage has led to the development of novel therapies that inhibit complement components and improve graft survival. The analysis of functional complotypes, based on the genotype of both graft recipient and donor, may become a valuable tool for assessing the risk of acute transplant rejection. The review summarizes current knowledge on the pathomechanisms of complement activation following kidney transplantation and the resulting diagnostic and therapeutic possibilities.

Impact of Recipient Age on Outcomes After Pancreas Transplantation

BACKGROUND

Few reports have provided the ages of pancreas transplant recipients. The aim of this study was to determine whether recipient age affects survival of pancreatic grafts after transplantation.

METHODS

We analyzed 73 patients who had undergone pancreas transplantation at our institution from August 2001 to March 2020 and assessed the effects of recipient age on pancreas graft survival within 5 years after pancreas transplantation.

RESULTS

The cutoff value for recipient age established by receiver operating characteristic curve was 35 years. The pancreas graft survival rate of recipients aged 35 years or younger (1, 3, and 5 years: 72.9%, 41.7%, and 41.7%, respectively) was significantly lower than that of recipients aged over 35 years (1, 3, and 5 years: 93.2%, 88.4%, and 88.4%, respectively). Multivariate Cox hazard regression analysis showed that recipient age 35 years or younger (hazard ratio = 3.60; 95% confidence interval, 1.04-12.50; P = .044) and solitary pancreas transplantation (hazard ratio = 10.72; 95% confidence interval, 2.72-42.28; P < .001) were significant risk factors for pancreas graft loss within 5 years.

CONCLUSION

Our data suggest that younger recipient age is a risk factor for pancreas graft loss after transplantation.

Transplantation of Kidneys From Hepatitis C Virus-Infected Donors to Hepatitis C Virus-Negative Recipients: One-Year Kidney Allograft Outcomes

RATIONALE & OBJECTIVE

Transplant centers in the United States are increasingly willing to transplant kidneys from hepatitis C virus (HCV)-infected (HCV⁺) donors into HCV^- recipients. We studied the association between donor HCV infection status and kidney allograft function and posttransplantation allograft biopsy findings.

STUDY DESIGN

Retrospective cohort study.

SETTING & PARTICIPANTS

We examined 65 HCV^- recipients who received a kidney from a HCV⁺ donor and 59 HCV^- recipients who received a kidney from a HCV^- donor during 2018 at a single transplant center.

EXPOSURE

Predictor(s) of donor infection with HCV.

OUTCOMES

Kidney allograft function and allograft biopsy findings during the first year following transplantation.

ANALYTICAL APPROACH

We compared estimated glomerular filtration rate (eGFR), findings on for-cause and surveillance protocol biopsies, development of de novo donor-specific antibodies (DSAs), and patient and allograft outcomes during the first year following transplantation between recipients of HCV⁺ and HCV^- kidneys. We used linear regression to estimate the independent association between allograft function and HCV viremic status of the kidney donor.

RESULTS

The mean age of recipients was 52 ± 11 (SD) years, 43% were female, 19% and 80% of recipients were White and Black, respectively. Baseline characteristics were similar between the HCV⁺ and HCV^- groups. There were no statistically significant differences between the HCV⁺ and HCV^- groups in delayed graft function rates (12% vs 8%, respectively); eGFRs at 3, 6, 9, and 12 months post-transplantation; proportions of patients with cellular rejection (6% vs 7%, respectively); and proportions with antibody-mediated rejection (7% vs 10%, respectively) or de novo DSAs (31% vs 20%, respectively). HCV viremic status was not associated with eGFR at 3, 6, 9, or 12 months.

LIMITATIONS

Generalizability from a single-center study and small sample size was limited.

CONCLUSIONS

Recipients of kidneys from donors infected with HCV had similar kidney allograft function and probability of rejection in the first year after transplantation compared to those who received kidneys from donors without HCV infection.

Transplanting the Elderly: Mandatory Age- and Minimal Histocompatibility Matching

Worldwide over 40% of patients receiving renal replacement therapy (RRT) are aged 65 years or older, a number that is still increasing. Renal transplantation is the preferred RRT, providing substantial survival benefit over those remaining on dialysis, including the elderly. Only 3% of patients aged 65 years or older accepted on the waiting list actually received a kidney transplant offer within the Eurotransplant allocation region. To increase the chance for elderly to receive a timely kidney transplant, the Eurotransplant Senior Program was introduced. The ESP supports local allocation of older kidneys to older donors in order to decrease cold ischemia time, while disregarding former exchange principles based on matching for HLA antigens. As a consequence, more elderly received a kidney transplant and a relative higher incidence of acute rejection resulted in additional courses of high steroids and/or depleting antibody therapy. Since death with a functioning graft due to infections is the dominant reason of graft loss in elderly, more intense clinical immunosuppression to prevent or treat acute rejection is not a very attractive option. Therefore in elderly kidney transplant candidates, we advocate reintroduction of minimal histocompatibility criteria (i.e., HLA-DR matching) followed by age-matching with mandatory local/regional allocation to also facilitate short cold ischemia.