Immunosenescence increases the rate of acceptance of kidney allotransplants in elderly recipients through exhaustion of CD4 T-cells

Compromised immunity is the hallmark of ageing. Paradoxically, it may be “an ally” in facilitating acceptance of allogeneic grafts in the elderly. In this retrospective study we looked for biomarkers of immunosenescence that distinguish elderly recipients less prone to reject kidney allografts.Recruited kidney recipients aged ≥60 or <60 were designated ‘elderly’ and ‘young’, respectively. Both age-groups were divided according to the history of acute rejection. The phenotype, length of telomeres, expression of FoxP3 and proliferative responses were assessed in CD4⁺ and CD8⁺ T-cell subsets. In addition, IL6, IL10 and TGFβ were measured on the level of mRNA and serum protein.Acute-rejection-free history in elderly transplant recipients was associated with short telomeres, a decreased proportion of CD28⁺ T-cells associated with CMV-seropositivity and low proliferation of CD4⁺ T-cells. In contrast, elderly recipients who experienced acute rejection kept preserved telomere length, had a higher number of functional CD4⁺CD28⁺ cells and exhibited vigorous proliferation in vitro. These differences were not found in the young group.The major conclusion of this study is that the impaired condition of CD4⁺ T-cells, so-called immunosenescence, renders transplant recipients less responsive to an allogeneic kidney graft, an effect that was limited to transplant recipients of >60 years of age.     

Characterization of the rapamycin-sensitive phosphoproteome reveals that Sch9 is a central coordinator of protein synthesis

The target of rapamycin complex 1 (TORC1) is an essential multiprotein complex conserved from yeast to humans. Under favorable growth conditions, and in the absence of the macrolide rapamycin, TORC1 is active, and influences virtually all aspects of cell growth. Although two direct effectors of yeast TORC1 have been reported (Tap42, a regulator of PP2A phosphatases and Sch9, an AGC family kinase), the signaling pathways that couple TORC1 to its distal effectors were not well understood. To elucidate these pathways we developed and employed a quantitative, label-free mass spectrometry approach. Analyses of the rapamycin-sensitive phosphoproteomes in various genetic backgrounds revealed both documented and novel TORC1 effectors and allowed us to partition phosphorylation events between Tap42 and Sch9. Follow-up detailed characterization shows that Sch9 regulates RNA polymerases I and III, the latter via Maf1, in addition to translation initiation and the expression of ribosomal protein and ribosome biogenesis genes. This demonstrates that Sch9 is a master regulator of protein synthesis.     

Role of AMPK in pancreatic beta cell function

Pharmacological activation of AMP activated kinase (AMPK) by metformin has proven to be a beneficial therapeutic approach for the treatment of type II diabetes. Despite improved glucose regulation achieved by administration of small molecule activators of AMPK, the potential negative impact of enhanced AMPK activity on insulin secretion by the pancreatic beta cell is an important consideration. In this review, we discuss our current understanding of the role of AMPK in central functions of the pancreatic beta cell, including glucose-stimulated insulin secretion (GSIS), proliferation, and survival. In addition we discuss the controversy surrounding the role of AMPK in insulin secretion, underscoring the merits and caveats of methods used to date.     

Prophylactic immune tolerance induced by changing the ratio of antigen-specific effector to regulatory T cells

Summary.  Background : Gene and protein replacement therapies for inherited protein deficiencies such as hemophilia or lysosomal storage disorders are limited by deleterious immune responses directed against their respective therapeutic proteins. Therefore, the development of protocols preventing such responses is key to providing successful long-term therapy. Objectives : We sought to develop a protocol, utilizing a drug/peptide cocktail, that would effectively shift the antigen-specific CD4+ T-cell population, tipping the balance from effector T cells (Teffs) towards regulatory T cells (Tregs). Methods : Treg-deficient (DO11.10-tg Rag2^−/−) BALB/c mice were used to screen for an optimal protocol addressing the aforementioned goal and to study the mechanisms underlying in vivo changes in T-cell populations. Muscle-directed gene transfer to hemophilia B mice was also performed in order to test the optimal protocol in a therapeutically relevant setting. Results: Specific antigen administration (4-week repeated dosing) combined with rapamycin and interleukin-10 led to substantial reductions in Teffs, via activation-induced cell death, and induced CD4+CD25+FoxP3+ Tregs to a large extent in multiple organs. The proportion of apoptotic T cells also increased over time, whereas Teffs and Tregs were differentially affected. When applied to a model of protein deficiency (gene therapy for hemophilia B), the protocol successfully prevented inhibitor formation, whereas non-specific immunosuppression was only marginally effective. Conclusions : It is feasible to provide a short-term, prophylactic protocol allowing for the induction of immune tolerance. This protocol may provide a marked advance in efforts seeking to improve clinical outcomes in disorders involving therapeutic protein replacement.     

雷帕霉素抑制血管紧张素Ⅱ诱导的血管内皮细胞增生

目的研究阻断PI3K-p70S6K和Ras-p42／p44MAPK信号通路对血管紧张素Ⅱ(ANGⅡ)诱导的脐静脉内皮细胞(HUVEC)增殖及细胞周期进程的影响。方法ANGⅡ联合不同浓度雷帕霉素刺激体外培养的HUVEC,3H-胸腺嘧啶核苷掺入法和3H-亮氨酸掺入法测定细胞DNA和蛋白质合成,流式细胞术检测细胞周期变化,免疫印迹(Western blot)检测细胞信号蛋白p70S6K (p70 ribosomal protein S6 kinase),ERK2(extracellular signal regulated kinase)及细胞周期蛋白CyclinD1、CyclinA、和CyclinBt表达的变化。结果雷帕霉素抑制ANGⅡ诱导的血管内皮细胞蛋白质和DNA的合成,并呈剂量依赖性,雷帕霉素抑制ANGⅡ诱导的p70S6K和CyclinD1的表达,阻滞细胞于G1期(P<0．01),而不影响ERK2、CyclinA和CyclinBt的表达。结论PI3K-p70S6K信号通路在ANGⅡ诱导的HUVEC增殖及细胞周期进程中起关键作用,雷帕霉素免疫抑制靶点p70S6K可应用于干预血管内皮细胞的增殖。     

两组免疫抑制方案用于肾移植的对比研究

目的通过两组免疫抑制方案在肾移植中的临床应用,评估新型免疫抑制剂雷帕霉素预防急性排斥反应(AR)的疗效和安全性。方法回顾分析肾移植患者的临床资料,按术后免疫抑制方案的不同,随机分为两组:采用雷帕霉素(RPM,首次剂量6.0 mL,维持剂量2.0 mL/d)+环孢素A(CsA,5~6 mg.kg-1.d-1)+泼尼松(Pred)25例为SRL组,采用霉酚酸酯(MMF)+CsA(6~8 mg.kg-1.d-1)+Pred 35例为MMF组。比较两组用药后的血肌酐(SCr)、AR发生率及药物的不良反应。结果在SCr水平、AR发生率方面,MMF组与SRL组无统计学意义(P>0.05);两组在随访期间均未见严重感染发生;除SRL组高脂血症的发生率明显升高外,两组药物不良反应无统计学意义。结论SRL组抗排斥反应的疗效及安全性与MMF组相似,可作为肾移植抗排斥反应治疗方案推广使用。     

Blockade of CD154-CD40 pathway induces interleukin-10 dependent T regulatory type 1 like cells

Several subsets of T-regulatory （Tr） cells with distinct phenotypes and distinct mechanisms of action have been identified. These include Tr type 1 （Trl） cells; Th3 cells, which primarily secrete transforming growth factor （TGF）-β; and CD4^＋CD25^＋ T cells, which inhibit immune responses through cell to cell contact.1 It has been shown that CD4^＋CD25^＋ immunoregulatory T cells induced by the blockade of CD154-CD40 pathway are tolerant to alloantigen, resulting in secondary mixed lymphocyte reaction （MLR） hyporesponsiveness in vitro and tolerance to alloantigen in vivo. Previous studies mainly paid attention to CD4^＋CD25^＋ immunoregulatory T cells induced by CD154-CD40 blockade, but it was unclear whether CD154-CD40 blockade might induce Trl or Tr1-like cells.     

Rapamycin Modulates the Maturation of Rat Bone Marrow-derived Dendritic Cells

The purpose of the study was to observe the effect of rapamycin （RAPA） on the differentiation and maturation of rat bone marrow-derived dendritic cells （BMDCs） in vitro. BMDCs from Wistar rats were cultured with granulocyte-macrophage colony-stimulating factor plus interleukin-4 in the presence or absence of RAPA （20 ng/mL）, and stimulated with lipopolysaccharide （LPS） for 24 h before cells and supernatants were collected. Surface phenotype of BMDCs was flow-cytometrically detected to determine the expression of maturation markers, MHC class Ⅱ and CD86. Supernatants were analyzed for the production of IL-12 and IFN-γ cytokines by using ELISA. BMDCs were co-cultured with T cells from Lewis rats and mixed lymphocyte reaction was assessed by MTT method. The morphology of BMDCs stimulated with LPS remained immature after RAPA pretreatment. RAPA significantly decreased the CD86 expression, impaired the IL-12 and IFN-γ production of BMDCs stimulated with LPS, and inhibited the proliferation of allogeneic T cells. In conclusion, RAPA can inhibit the maturation of BMDCs stimulated with LPS in terms of the morphology, surface phenotype, cytokine production, and ability of BMDCs to stimulate the proliferation of allogeneic T cells in vitro.