Managing transplant rejection in the elderly: the benefits of less aggressive immunosuppressive regimens

Immunological discrepancy in aged mice facilitates skin allograft survival

More and more aged people are undergoing organ transplantation. Understanding aging effects on immunity will be helpful for post-transplantation care and adjustment of immunosuppressants for aged recipients. A mouse model, using C3H mice as donors and aged/young C57BL/10J mice as recipients, was employed to study aging effects on immunity. The results showed that frequency of myeloid-derived suppressor cells (MDSC) and level of TGF-β was higher in aged mice than in young mice (4.4 ± 1.4% versus 1.6 ± 1.1%, p = 0.026 for MDSC; 21.04 ± 3.91 ng/ml versus 15.26 ± 5.01 ng/ml, p = 0.026 for TGF-β). In vivo, skin allograft survived longer on the aged than on young mice (19.7 ± 5.2 days versus 11.9 ± 4.1 days, p = 0.005). When entinostat was applied to block MDSC, the survival of skin allografts on aged mice was shorten to 13.5 ± 4.7 days which was not different from the survival on young mice (p = 0.359). In conclusion, allogeneic immunity was different in aged from young mice in high frequency of MDSC and high serum level of TGF-β. Blocking the function of MDSC reversed the low immunity in aged mice and caused skin allograft rejection similar to young recipients.

Diabetes Mellitus Following Renal Transplantation: Clinical and Pharmacological Considerations for the Elderly Patient

Post-transplant diabetes mellitus occurs in 30-50% of cases during the first year post-renal transplantation. It is associated with increased morbidity, mortality and healthcare costs. Risk factors include age and specific immunosuppression regimens. At the same time, renal transplantation is increasingly indicated in elderly (aged >65 years) patients as this proportion of older patients in the prevalent dialysis population has increased. The immune system and β cells undergo senescence and this impacts on the risk for developing post-transplant diabetes and our ability to prevent such development. It may, however, be possible to identify patients at risk of developing post-transplant diabetes, enabling treatment protocols that prevent or reduce the impact of post-transplant diabetes. Much work remains to be completed in this area and is facilitated by the growing base of knowledge regarding the pathophysiology of post-transplant diabetes. Should post-transplant diabetes develop, there are a range of treatment options available. There is increasing interest in using newer agents, although their safety and efficacy in transplant recipients remains to be conclusively established.

Are Octogenarians With End-Stage Renal Disease Candidates for Renal Transplantation?

BACKGROUND

Elderly patients are the fastest-growing group in need of renal transplantation. This study puts focus on renal transplant recipients in their 80th year or longer at time of engraftment. Is there evidence to support an absolute upper age limit for renal transplantation?

METHODS

Recipients in their 80th year or longer, transplanted between 1983 and 2015, were included. Data were retrieved from the Norwegian Renal Registry in the end of October 2015. Graft and patient survivals were compared with recipients aged 70 to 79 years at transplantation.

RESULTS

Forty-seven patients older than 79 years were transplanted in the defined period. Median age 80.1 years, 81% were men. Median time on dialysis before transplantation was 18.5 months. All patients received an allograft from a deceased donor (median donor age, 61.8 years). In the death-censored graft survival model, there was no statistical difference between the groups. We found improved patient and graft survivals after introduction of mycophenolate mofetil and induction with basiliximab. Patients transplanted before 2000 had increased risk of death compared with those transplanted after 2000 (hazard ratio, 3.2; 95% confidence interval, 1.2-8.7). Median uncensored graft survival for patients transplanted after the year 2000 was 5.0 year (95% confidence interval, 2.4-7.6). Median patient survival was 5.0 years (3.1-6.9) and 5-year patient survival was 55%.

CONCLUSIONS

Age by itself should not be an absolute contraindication against renal transplantation. An estimated 5-year survival rate of 55% post-engraftment for an 80-year-old patient is in our opinion more than acceptable.

Pharmacokinetics and pharmacodynamics of immunosuppressive drugs in elderly kidney transplant recipients

Elderly patients are a fast growing population among transplant recipients over the past decades. Both the innate and adaptive immune reactivity decrease with age, which is believed to contribute to the decreased incidence of acute rejection and increased infectious death rate in elderly transplant recipients. In contrast to recipient age, donor age is associated with a higher incidence of acute rejection. Pharmacokinetic studies in renal transplant recipients show that CNI troughs are >5% higher in elderly compared to younger patients given the same dose normalized by body weight. This may impact the starting dose of tacrolimus and cyclosporine. Possibly in elderly patients the intracellular (in lymphocyte) concentrations are relatively high in relation to the whole blood concentration, resulting in a stronger pharmacodynamic effect at the same whole blood trough concentration. For cyclosporine this has been shown, but it is not clear if the same is true for other immunosuppressive drugs. Pharmacodynamic studies have compared the inhibition of target enzymes, or more downstream effects of immunosuppressive drugs, in younger and older patients. Measurement of nuclear factor of activated T-cell (NFAT)-regulated gene expression (RGE), a pharmacodynamic read-out of CNI, is a promising biomarker of immunosuppression. Low levels of NFAT RGE are associated with increased risk of infection and non-melanoma skin cancer in elderly patients. Clinical trials to evaluate the safety and efficacy of immunosuppression regimens in this specific patient population, which is underrepresented in published trials, are lacking. More studies in elderly patients are needed to investigate the impact of age on the pharmacokinetics or pharmacodynamics of immunosuppressive drugs, and to decide on the optimal regimen and target levels for elderly transplant recipients.