Translational Research ～The Role of Nuclear Protein-Histone H1in Transplantation and Regeneration Immunobiology

• Main Authors: Li-WenHsu, 許麗文
• Other Authors: Shu-Hui Chen
• Format: Others
• Language: en_US
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/67895704646099378692

博士 === 國立成功大學 === 化學系碩博士班 === 101 === In solid organ transplantation, rejection is inevitable and must be treated with long-term immunosuppressive agents, such as tacrolimus (FK506) and cyclosporine A (CsA), which cause deleterious side effects. However, it is unethical to randomly terminate immunosuppressive therapy, which leads to allograft failure. The development of safer and more effective immunosuppressants would result in further improvement of organ transplantation. Allograft tolerance can be observed almost exclusively in clinical and experimental liver transplantation compared to other organ transplantation. In a rat model of orthotopic liver transplantation (OLT), recipient serum after OLT (post-OLT serum) has been reported to have immunosuppressive activity and contribute to overcome allograft rejection. However, the molecular identities of immunosuppressive factors, which are in the early stage of post-OLT, remain elusive. We previously demonstrated that liver allograft tolerance is associated with the immunosuppressive activity of anti-histone H1 antibody (Ab) induced in the serum of liver transplantation. I have been researching the effect of histone H1 and its Ab on individual immune responsible cells such as DCs, T cells, NK cells and adipose-derived stem cells (ASCs). Especially, cross-talk among T cells, ASCs and DCs is currently being paid attention. Therefore, the specific aims of this study focus here upon the significance of histone H1 and its Ab in transplantation immunology and regeneration immunobiology. Firstly, the mechanisms underlying the immunosuppressive activity by anti-histone H1 Ab was explored in immune responsible cells including DCs, T-cells, LAK cells, and NK cells. The addition of anti-histone H1 Ab to Concanavalin A (ConA) blast inhibited the proliferation of 5-(6)-carboxy-fluorescein succinimidyl ester (CFSE)-labeled lymphocytes without toxicity but increased the population of CD4+CD25+ T-cells. DCs treated with anti-histone H1 Ab expressed lower levels of CD80/CD86, interleukin (IL)-1β, and IL-6. The addition of anti-histone H1 Ab to LAK cells culture decreased the percentages of NKR-P1 populations and down-regulated levels of inducible nitric oxide synthase (iNOS), IL-2, and interferon (IFN)-γ in RT-PCR. The cytotoxicity of LAK cells and NK cells was lower after treated with anti-histone H1 Ab compared to treat with control IgG. We found that the blockade of histone H1 modulated DCs toward tolerogenic status, decreased the cytotoxicity of LAK and NK cells, and induced CD4+CD25+ T-cells. We also focus upon the significance of histone H1 on DCs in terms of the intracellular signalling pathway of DCs. Our immunostaining and immunoblot studies demonstrated that histone H1 was detected in cytoplasm and culture supernatants upon the activation of DCs. Histone H1 blockage by anti-histone H1 Ab down-regulated the intracellular activation of mitogen-activated protein kinases (MAPKs) (p38) and IkBα of DCs, and inhibited DC activity in the proliferation of CD4+ T cells. On the other hand, the addition of histone H1 without endotoxin stimulation up-regulated major histocompatibility complex class (MHC) II, the CD80 and CD86 surface markers of DCs and the activation of MAPKs (p38 and extracellular-regulated kinase (ERK) 1/2) and IkBα. These results suggest that the translocation of histone H1 from nuclei to cytoplasm and the release of their own histone H1 are necessary for the maturation of DCs and the activation for T lymphocytes. Recent experimental studies suggest that stem cells from bone marrow to liver allograft play an important role of immunological tolerance and regeneration in the donor graft. Additionally, nuclear proteins have been reported to enhance migration of stem cells and subsequent regeneration. Therefore, I have been investigating the effect of histone H1 on stem cells. In the experimental setting of liver transplantation, the expression of histone H1 in donor graft can be observed exclusively in tolerogeneic OLT while no hepatic expression of histone H1 was observed in donor grafts of rejector OLT. Therefore, I firstly performed in vitro studies demonstrating the effect of histone H1 on immunosuppression potential and migration ability of ASCs. Our in vitro studies showed that histone H1 does not alter immunological status but that histone H1 enhanced wound healing and migration ability accompanied with increased IL-6 expression. In the present study, the role of histone H1 on post-transplant liver regeneration is also discussed. In conclusion, these results suggest that the use of anti-histone H1 Abs might be a useful strategy for the development of a form of immunosuppression and histone H1 may be useful for induction of ASCs in tissue engineering and future potential ASCs therapies for transplantation.