Induction of suppressive allogeneic regulatory T cells via rabbit antithymocyte polyclonal globulin during homeostatic proliferation in rat kidney transplantation

Experimental studies have shown that rabbit antithymocyte polyclonal globulin (ATG) can expand human CD4+CD25++Foxp3+ cells (Tregs). We investigated the major biological effects of a self‐manufactured rabbit polyclonal anti‐rat thymoglobulin (rATG) in vitro, as well as its effects on different peripheral T‐cell subsets. Moreover, we evaluated the allogeneic suppressive capacity of rATG‐induced Tregs in an experimental rat renal transplant model. Our results show that rATG has the capacity to induce apoptosis in T lymphocyte lymphocytes as a primary mechanism of T‐cell depletion. Our in vivo studies demonstrated a rapid but transient cellular depletion of the main T cell subsets, directly proportional to the rATG dose used, but not of the effector memory T cells, which required significantly higher rATG doses. After rATG administration, we observed a significant proliferation of Tregs in the peripheral blood of transplanted rats, leading to an increase in the Treg/T effector ratio. Importantly, rATG‐induced Tregs displayed a strong donor‐specific suppressive capacity when assessed in an antigen‐specific allogeneic co‐culture. All of these results were associated with better renal graft function in rats that received rATG. Our study shows that rATG has the biological capacity immunomodulatory to promote a regulatory alloimmune milieu during post‐transplant homeostatic proliferation.     

氧化苦参碱通过免疫调节保护刀豆蛋白A诱导的小鼠免疫性肝损伤

目的:本文旨在研究氧化苦参碱(OMT)对刀豆蛋白A(Con A)所致小鼠免疫性肝损伤的保护作用。方法:Balb/C小鼠随机分为5组,分别为正常组,模型组,氧化苦参碱低、高剂量(60,120 mg·kg-1)组和双环醇(156 mg·kg-1)阳性药组。连续给药5 d,末次给药30 min后,除正常组外,其余各组均尾静脉注射Con A(15 mg·kg-1)建立肝损伤模型。造模8 h后,检测血清中丙氨酸氨基转移酶(ALT),天门冬氨酸氨基转移酶(AST),总胆红素(TBIL)的表达。采用Luminex多因子检测的方法,检测血清干扰素-γ(IFN-γ),肿瘤坏死因子-α(TNF-α),白细胞介素-4(IL-4),IL-6,IL-10,IL-27表达,苏木精-伊红(HE)染色观察肝组织病理改变。流式细胞术检测小鼠脾淋巴细胞CD4+IL-17A的表达,CD4+CD25+Fox P3+调节性T细胞(Treg)亚群的比例。结果:与正常组比较,Con A模型组ALT,AST,TBIL表达明显增高(P0.05,P0.01)。与模型组比较,双环醇和OMT低高剂量组均可明显降低ALT活性(P0.05,P0.01)。OMT高剂量可明显抑制AST表达(P0.05),OMT低高剂量均可抑制TBIL表达(P0.05),其余各组无统计学差异。各给药组均能不同程度缓解肝脏病理改变,减少炎性细胞浸润。OMT高剂量组血清IL-10,IL-27水平与模型组比较显着升高(P0.05)。流式细胞术检测结果显示,OMT高剂量组可明显降低CD4+IL-17A表达(P0.05),上调CD4+CD25+Fox P3+Treg比例(P0.05)。结论:OMT对Con A诱导小鼠免疫性肝损伤具有较好的保护作用,抑制CD4+IL-17A的表达,上调CD4+CD25+Fox P3+Treg比例可能是其主要的作用机制。     

Implications of uterine NK cells and regulatory T cells in the endometrium of infertile women

A range of studies have shown that the complex process of implantation and an establishment of a pregnancy also involves immune factors. Disturbances in these underlying immune mechanisms might lead to implantation and pregnancy failure and may be involved in the pathogenesis of unexplained infertility. Several studies have reported that imbalances in uterine NK (uNK) cell abundance are associated with infertility; however, controversies exist. An increased amount of CD56⁺ uNK cells along with a decrease in CD16⁺ uNK cells have been associated with normal fertility in some studies. Very few studies of FoxP3⁺ regulatory T cells (Tregs) in the pre-implantation endometrium have been performed. Results are sparse and controversial, studies reporting both increased and decreased numbers of Tregs, respectively, in women suffering from infertility. In conclusion, studies imply that uNK cells, Tregs and HLA-G carry pivotal roles regarding the establishment of a healthy pregnancy, and that abnormal immune mechanisms involving these parameters may be associated with infertility. However, more research in early phases of the reproductive cycle, such as investigating the conditions in the endometrium before implantation, is needed to further clarify the underlying mechanisms.     

Mechanisms and biomarkers of immune quiescence in kidney transplantation

This review discusses the current understanding of biomarkers of immune quiescence based on reviews of published literature in kidney transplant operational tolerance and mechanistic studies based on a better characterization of the stable, well-functioning renal allograft.     

Preclinical and clinical studies for transplant tolerance via the mixed chimerism approach

Based upon observations in murine models, we have developed protocols to induce renal allograft tolerance by combined kidney and bone marrow transplantation (CKBMT) in non-human primates (NHP) and in humans. Induction of persistent mixed chimerism has proved to be extremely difficult in major histocompatibility complex (MHC)-mismatched primates, with detectable chimerism typically disappearing within 30–60?days. Nevertheless, in MHC mismatched NHP, long-term immunosuppression-free renal allograft survival has been achieved reproducibly, using a non-myeloablative conditioning approach that has also been successfully extended to human kidney transplant recipients. CKBMT has also been applied to the patients with end stage renal disease with hematologic malignancies. Renal allograft tolerance and long-term remission of myeloma have been achieved by transient mixed or persistent full chimerism. This review summarizes the current status of preclinical and clinical studies for renal and non-renal allograft tolerance induction by CKBMT. Improving the consistency of tolerance induction with less morbidity, extending this approach to deceased donor transplantation and inducing tolerance of non-renal transplants, are critical next steps for bringing this strategy to a wider range of clinical applications.     

Mesenchymal stromal cells for tolerance induction in organ transplantation

The primary challenge in organ transplantation continues to be the need to suppress the host immune system long-term to ensure prolonged allograft survival. Long-term non-specific immunosuppression can, however, result in life-threatening complications. Thus, efforts have been pursued to explore novel strategies that would allow minimization of maintenance immunosuppression, eventually leading to transplant tolerance. In this scenario, bone marrow-derived mesenchymal stromal cells (MSC), given their unique immunomodulatory properties to skew the balance between regulatory and memory T cells, have emerged as potential candidates for cell-based therapy to promote immune tolerance. Here, we review our initial clinical experience with bone marrow-derived MSC in living-donor kidney transplant recipients and provide an overview of the available results of other clinical programs with MSC in kidney and liver transplantation, highlighting hurdles and success of this innovative cell-based therapy.     

Regulatory T cell abundance and activation status before and after priming with HIVIS-DNA and boosting with MVA-HIV/rgp140/GLA-AF may impact the magnitude of the vaccine-induced immune responses

Background

Little is known about regulatory CD4 T cells (Tregs) in the context of HIV vaccines. Tregs can be differentiated into resting (FoxP3⁺CD45RA⁺ – rTregs), activated (FoxP3^HighCD45RA^? – aTregs) and memory (FoxP3^LowCD45RA^? – mTregs). Tregs, as CD4 T cells, are also frequent targets for HIV infection. We studied how the abundance and phenotypes of Tregs in terms of activation status and expression of HIV-1 binding molecules would have changed during vaccination in healthy volunteers participating in a phase IIa HIV vaccine clinical trial. Subjects were primed three times with HIVIS-DNA and boosted twice with MVA-CMDR-HIV alone (n?=?12) or MVA-CMDR combined with protein CN54rgp140 (n?=?13). The proportions of β7 integrin in all CD4 T cells and in the Tregs subset decreased moderately after the final vaccination (p?=?0.001 and p?=?0.033, respectively) and the rTregs proportion within the total Tregs were also decreased after the final vaccination (p?=?0.038). All these proportions returned to normal values within the three months after the final vaccination. The magnitude of HIV-Envelope-specific IFNγ?+?T cells after vaccination (r?=?0.66; p?=?0.021) correlated directly with the proportion of Tregs, and correlated inversely correlated with ratios of Th17/Tregs (r?=??0.75; p?=?0.0057) and Th17/mTregs (r?=??0.78; p?=?0.0065). Higher titers of IgG gp140 antibodies were observed in subjects with higher mTregs proportions (r?=?0.52; p?=?0.022). Interestingly, pre-vaccination levels of mTregs correlated with vaccine-induced Env-binding antibodies (r?=?0.57; p?=?0.01) and presence of neutralizing antibodies (r?=?0.61; p?=?0.01), while the pre-vaccination Th17/mTregs ratio correlated inversely with the magnitude of cellular IFN-γ ELISpot responses (r?=??0.9; p?=?0.002). Taken together, these results suggest that pre- and post-vaccination Tregs, their activation status, the Th17/Tregs ratio and other host factors affecting Treg abundance, have an impact on the magnitude of HIV vaccine-induced immune responses. Moreover, the DNA-HIVIS/MVA-HIV regimen, alone or in combination with CN54rgp140 induced moderate and temporary alterations of the Tregs activation status. We also show a decrease in expression of the HIV-1 ligand β7 integrin on Tregs and all CD4 T cells.     

Biomarkers of immune tolerance in liver transplantation

The liver exhibits intrinsic immune tolerogenic properties that contribute to a unique propensity toward spontaneous acceptance when transplanted, both in animal models and in humans. Thus, in contrast to what happens after transplantation of other solid organs, several years following liver transplantation a significant subset of patients are capable of maintaining normal allograft function with histological integrity in the absence of immunosuppressive drug treatment. Significant efforts have been put into identifying sensitive and specific biomarkers of tolerance in order to stratify liver transplant recipients according to their need for immunosuppressive medication and their likelihood of being able to completely discontinue it. These biomarkers are currently being validated in prospective clinical trials of immunosuppression withdrawal both in Europe and in the United States. These studies have the potential to transform the clinical management of liver transplant recipients by mitigating, at least in part, the burden of lifelong immunosuppression.