Coupled regulation of interleukin-12 receptor beta-1 of CD8+ central memory and CCR7-negative memory T cells in an early alloimmunity in liver transplant recipients

Advantage of tacrolimus/mycophenolate mofetil regimen for cytotoxic T cell-mediated defence and its inhibition by additive steroid administration in high-risk liver transplant recipients

Our previous work revealed that the recipients with the highest pre-existing numbers of CD8(+) effector T cells (TE ) [hyperparathyroidism (HPT)E recipients] occupied approximately 30% of adult transplant recipients performed in our hospital. HPTE recipients demonstrated very poor clinical outcome compared with the remaining 70% of recipients with the lowest pre-existing TE (LPTE recipient). This study aimed to clarify the best combined immunosuppressive regimen related to function of cytotoxic T lymphocytes (CTLs) for HPTE recipients. Eighty-one HPTE recipients were classified into three types, according to the immunosuppressive regimens: type 1, tacrolimus (Tac)/glucocorticoid (GC); type 2, Tac/mycophenolate mofetil (MMF)/GC; and type 3, Tac/MMF. Frequencies of severe infection, rejection and hospital death were the highest in types 1 and 2, whereas the lowest occurred in type 3. The survival rate in type 3 was the highest (100%) during follow-up until post-operative day 2000. Regarding the immunological mechanism, in type 1 TE perforin and interferon (IFN)-γ were generated through the self-renewal of CD8(+) central memory T cells (TCM ), but decreased in the early post-transplant period due to marked down-regulation of interleukin (IL)-12 receptor beta-1 of TCM. In type 2, the self-renewal TCM did not develop, and the effector function could not be increased. In type 3, in contrast, the effectors and cytotoxicity were correlated inversely with IL-12Rβ1(+) TCM levels, and increased at the highest level around the pre-transplant levels of IL-12Rβ1(+) TCM . However, the immunological advantage of Tac/MMF therapy was inhibited strongly by additive steroid administration.

Early coupled up-regulation of interleukin-12 receptor beta-1 in CD8+ central memory and effector T cells for better clinical outcomes in liver transplant recipients

This study aimed to investigate the role of initial priming of interleukin (IL)-12 receptor beta-1 in CD8(+) central memory T cells (initial IL-12RTCM priming) and CCR7-negative subsets (CNS) in effector cell expansion and clinical outcome after living donor liver transplantation (LDLT). One hundred and six patients who underwent LDLT were classified into the following three groups according to hierarchical clustering of CD8(+) CD45 isoforms before LDLT: I, naive-dominant; II, effector memory-dominant; and III, effector-dominant. The pre-existing CD8(+) effector cells (TE ) and activated immune status increased progressively from group I to group II to group III. Groups I, II and III received tacrolimus (Tac)/glucocorticoid (GC) regimens. Eighteen group III recipients received Tac/mycophenolate mofetil (MMF) and were defined as group IV. Initial IL-12RTCM priming was slightly, moderately and markedly decreased in droups I, II, and III, respectively. Initial priming of IL-12Rβ1 in CNS was decreased markedly in the three groups with marked decreases of TE , perforin and interferon (IFN)-γ; all parameters were restored by up-regulation of IL-12Rβ1(+) TCM through the self-renewal of TCM . The lag time required until coupled up-regulation of IL-12Rβ1 of TCM and CNS to above baseline was 12, 20 and 32 days in groups I, II and III, respectively. Inferior clinical outcomes were associated with increasing lag time. In contrast, the initial priming of IL-12Rβ1 in TCM and CNS remained above baseline in group IV due to MMF-mediated increase of IL-12Rβ1. Early coupled up-regulation of TCM and CNS leads to efficient TE differentiation and optimal clinical outcomes.

Current status of organ transplantation in Japan

To overcome severe donor shortage, Japanese doctors over the years have developed innovative strategies to maximize organs transplanted per brain death donor and expanded the donor pool using living donors. They also used living and marginal organs and drastically improved living donor lung, liver, pancreas and kidney transplantations. Moreover, they initiated ABO blood type incompatible liver transplantation advancements and succeeded in overcoming the blood type barrier in kidney and liver transplantations. Similar efforts are underway for pancreas transplantation. Furthermore, Japanese doctors have developed a nonaggressive step to achieve immunosuppression following organ transplantation by carefully monitoring donor-specific hyporesponsiveness and infectious immunostatus. However, the institution of amendments to allocation systems and the intensification of efforts to decrease living donor morbidity and to increase the number of brain death donors have remained important issues needing attention. Overall, the strategies Japan has adopted to overcome donor shortage can provide useful insights on how to increase organ transplantations.

Initial burst of viremia related to CD8 effector memory T cells after living donor liver transplantation in hepatitis C virus-infected recipients

The post-transplant immune responses, viremia, and allograft histology after living donor liver transplantation were studied in 39 hepatitis C virus (HCV)-infected recipients. The recipients were classified into the following groups according to a hierarchical clustering of their preoperative CD8CD45 T-cell isoforms: group I, naive-dominant; group II, effector memory-dominant; and group III, effector-dominant. Plasma HCV-RNA rapidly increased and then peaked as an initial burst around postoperative day (POD) 25 in group I, on POD 40 in group II, and on POD 55 in group III. The initial burst of viremia was suppressed by the high expression of CD8+CD28-CD27- subsets. The progression of fibrosis > or =F2 was significantly more frequent for those patients with the highest viremia levels. Moreover, the initial T-cell immune response became less important throughout time, and new immune responses emerged after 2 months that modified the host-virus interaction. It is suggested that the interferon (IFN)-alpha/ribavirin therapy starting 2 months may be an effective option and now is undertaken.