Glucocorticoids down-regulate dendritic cell function in vitro and in vivo

Exogenous glucocorticoid hormones are widely used as therapeutical agents, whereas endogenous glucocorticoids may act as physiological immunosuppressants involved in the control of immune and inflammatory responses. The optimal activation of T lymphocytes requires two distinct signals: the major histocompatibility complex-restricted presentation of the antigen and an additional co-stimulatory signal provided by the antigen-presenting cells. There is ample evidence that, among the cells able to present the antigen, the dendritic cells (DC) have the unique property to activate antigen-specific, naive T cells in vitro and in vivo, and are therefore required for the induction of primary immune responses. In this work, we tested whether glucocorticoids affected the capacity of DC to sensitize naive T cells. Our data show that, in vitro, the steroid hormone analog dexamethasone (Dex) affects the viability of DC, selectively downregulates the expression of co-stimulatory molecules on viable DC, and strongly reduces their immunostimulatory properties. In vivo, a single injection of Dex results in impaired antigen presenting function, a finding which correlates with reduced numbers of splenic DC. These results show that glucocorticoids regulate DC maturation and immune function in vitro and in vivo and suggest that this mechanism may play a role in preventing overstimulation of the immune system.     

再生柞蚕丝素蛋白对人骨髓间充质干细胞体外扩增的支持作用

大量的研究表明家蚕丝素蛋白具有良好的生物相容性。而对于柞蚕丝素蛋白在医用生物领域的研究报道在国内外尚较少。本研究选择再生柞蚕丝素蛋白为研究对象，观察了人骨髓间充质干细胞（hBMSCs）在再生柞蚕丝素膜上的粘附、生长及表面抗原的变化。结果在1h观察再生柞蚕丝素对hBMSCs的粘附力几乎与胶原相同，明显优于家蚕丝素和聚苯乙烯培养板。MTT法检测结果显示在第4d hBMSCs在再生柞蚕丝素膜上的增殖明显高于其他各组。电镜观察结果显示hBMSCs在再生柞蚕丝素膜上能够很好的粘附、生长，细胞间能相互连接形成片状结构。流式细胞仪检测再生柞蚕丝素蛋白对hBMSCs表面抗原的表达亦无明显影响。本研究结果显示再生柞蚕丝素蛋白体外支持hBMSCs的粘附、生长，具有良好的细胞相容性。     

兔骨髓间充质干细胞来源的心肌(样)细胞的诱导分化研究

目的体外诱导骨髓间充质干细胞(Mesenchymal stem cells,MSCs)向肌源性细胞分化,探索诱导后的MSCs移植于心肌梗死区的存活和分化情况。方法提取、分离、培养兔的MSCs。经5-氮胞苷诱导后,进行免疫组化,电镜观察。4',6二乙酞基-2-苯基吲哚(DAPI)标记MSCs,建立兔心肌梗死模型。实验动物随机分两组:实验组(n=10)在心梗区域注入经诱导后的MSCs;对照组(n=10)在心梗区域注入不含MSCs的培养液。移植4周后,进行病理标本观察和免疫组化检测。结果5-氮胞苷诱导MSCs4周,部分细胞表达肌钙蛋白T(troponin T),电镜观察到肌丝形成。MSCs在体外用DAPI标记,用荧光显微镜观察细胞发蓝色荧光。移植4周后,在实验组中用荧光显微镜观察可见梗死区组织标本中可见DAPI标记带蓝色荧光的供体细胞核,移植细胞表达troponin T。结论MSCs经5-氮胞苷诱导后可向心肌细胞转化。移植细胞可在心肌存活,并向心肌细胞(样)转化。     

可溶性HLA-G1与NK-92细胞表面ILT2及KIR2DL4受体相互作用的研究

 目的 探讨可溶性 HLA-G1（sHLA-G1）对人 NK-92 细胞杀伤活性的抑制与细胞表面免疫球蛋白样转录分子 2（ILT2）和杀伤细胞免疫球蛋白样受体 2DL4（KIR2DL4）受体的关系。 方法 ①通过原核表达技术获得 sHLA-G1 重组蛋白（重组蛋白），并采用蛋白质印迹法进行鉴定。②取 NK-92 细胞，加入终浓度 20 μg/ml 的重组蛋白分别培养 10、30 min，再分别加入抗 HLA-G1/G5、抗ILT2 和抗 KIR2DL4 抗体，采用流式细胞术检测各组 NK-92 细胞表面 sHLA-G1 和 ILT2、KIR2DL4 受体表达阳性率；以 NK-92 细胞单独培养作为对照组。③以人白血病 K562 细胞为靶细胞，以经不同方式处理的 NK-92 细胞为效应细胞，效靶比为5:1，共同培养 2 h，采用流式细胞术检测 NK-92 细胞对 K562 细胞的杀伤率。NK-92 细胞处理方式为单纯重组蛋白处理（分别加入终浓度为 0、10、20 μg/ml 的重组蛋白培养 30 min）和表面受体封闭 + 重组蛋白处理（分别加入抗 ILT2、抗 KIR2DL4、抗 LT2 + 抗 KIR2DL4 抗体培养 30 min，再分别加入终浓度为 0、10、20 μg/ml 的重组蛋白培养 30 min）。 结果 ①蛋白质印迹分析表明所获重组蛋白为带有组氨酸标签的特异蛋白。②NK-92 细胞与 20 μg/ml 重组蛋白共培养 30 min 后，sHLA-G1 表达阳性率明显高于而 ILT2、KIR2DL4 受体表达阳性率均明显低于对照组（均 P < 0.05）。③以终浓度 0、10、20 μg/ml 的重组蛋白处理的 NK-92 细胞对 K562 细胞的杀伤率分别为 39.79% ± 2.00%、27.79% ± 0.75%、21.36% ± 0.67%（两两比较，均 P < 0.01）；单独封闭 ILT2 受体，杀伤率分别为 23.09% ± 1.63%、21.13% ± 0.38%、18.42% ± 0.47%（两两比较，均 P < 0.01）；单独封闭 KIR2DL4 受体，杀伤率分别为 30.74% ± 0.44%、26.03% ± 0.38%、21.15% ± 0.35%（两两比较，均 P < 0.01）。 结论 sHLA-G1 通过与 NK-92 细胞表面 ILT2 和 KIR2DL4 受体直接结合而抑制 NK-92 细胞的杀伤活性。     

终末糖基化产物对培养的人脐静脉内皮细胞粘附分子表达的影响

目的：探讨终末糖基化产物在糖尿病动脉粥样硬化（AS）形成中的作用机理。 方法： 分离正常人脐静脉内皮细胞（HUVECs），将终末糖基化终产物（AGE）修饰的人血清白蛋白（AGE-HSA）、人血清白蛋白（HSA）与HUVECs在体外共同培养，并用荧光单克隆抗体染色，流式细胞仪定量检测细胞间粘附分子-1（ICAM-1）、血管细胞粘附分子-1（VCAM-1）的表达。 结果： 正常人HUVEC表达ICAM-1和VCAM-1。AGE-HSA能以时间和剂量依赖的方式上调ICAM-1、VCAM-1的表达（P<0.05），而HSA对HUVECs上述粘附分子的表达均无影响。 结论： AGE能上调HUVECs粘附分子的表达，从而促进AS时单核/巨噬细胞的浸润。     

腺病毒编码人TRP2修饰DC诱发抗小鼠黑色素瘤免疫的研究

目的比较腺病毒载体(Ad)介导人和小鼠酪氨酸酶相关蛋白2(tyrosinase-relatedpro-tein2,TRP2)修饰小鼠骨髓来源的树突状细胞(BM-DC)诱发抗小鼠黑色素瘤免疫的差异。方法Ad编码人或小鼠TRP2(AdhTRP2或AdmTRP2)体外感染小鼠BM-DC并体内皮下免疫C57BL/6小鼠,7d后取出被免疫小鼠脾细胞行体内细胞毒性T淋巴细胞杀伤试验(invivoCTL)和细胞内IFN-γ染色(ICS)分析CTL的杀伤活性和IFN-γ的产生;或给免疫后小鼠皮下接种小鼠B16.F10黑色素瘤细胞,观察荷瘤小鼠的成活情况。结果invivoCTL和ICS分析显示,AdhTRP2/BM-DC免疫小鼠,其6hCTL杀伤率为(98.7±1.2)%,IFN-γ产生的CD8+T细胞占总CD8+T细胞的(1.25±0.21)%;而AdmTRP2/BM-DC免疫的小鼠,其6hCTL杀伤率和产生IFN-γ的CD8+T细胞比例分别为(28.6±6.3)%和(0.24±0.06)%。荷瘤试验表明,AdhTRP2/BM-DC免疫小鼠后1周皮下接种106B16.F10细胞,观察3个月100%的小鼠无瘤生长;而接种5×104B16.F10细胞至AdmTRP2/BM-DC免疫1周的小鼠,3个月后小鼠成活率仅为40%。结论Ad介导异种(人)TRP2较自身(小鼠)TRP2修饰的BM-DC更为有效地打破肿瘤免疫耐受、诱导强烈的抗黑色素瘤免疫反应,是一种高效的以DC为基础的肿瘤疫苗。     

Does Hemopoietic Stem Cell Transplantation Have a Role in Treatment of Severe Rheumatoid Arthritis?

Based on animal models and limited clinical experience, there is considerable interest in use of high-dose immunosuppression followed by hemopoietic stem cell transplantation as treatment for severe rheumatoid arthritis. Because of its relatively low treatment-related mortality and morbidity, autologous transplantation is a more attractive option than allogeneic transplantation for initial clinical trials, even though anecdotal reports suggest that allogeneic transplantation has a greater likelihood of bringing about long-term disease control. The approach remains experimental with many unanswered questions such as the value and safety of high-dose therapy without transplantation, the need for T cell purging, the possible deleterious effects of post-transplant hemopoietic growth factors and the potential of mini allogeneic transplantation (a process whereby intense immunosuppression is combined with less intense myelosuppression). To achieve quick progress it is essential that clinical trials be carefully designed with all cases being reported to the Autoimmune Disease Stem Cell Project Database.     

Aberrant T cell responses to myelin antigens during clinical exacerbation in patients with multiple sclerosis

Multiple sclerosis (MS) is a demyelinating disease of presumed T cell autoimmunity against self myelin. We hypothesized that if myelin-reactive T cells are associated with the disease processes, they may undergo activation and expansion during acute exacerbation. In this study, we examined the precursor frequency, epitope recognition and cytokine profile of myelin-reactive T cells in 14 relapsing/remitting MS patients during exacerbation and remission. The study revealed that T cells recognizing the immunodominant peptides of candidate myelin antigens, including myelin basic protein (MBP), proteolipid protein and myelin oligodendrocyte glycoprotein, occurred at increased precursor frequency during acute exacerbation. The T cell responses to MBP focused on the immunodominant regions (residues 83-99 and 151-170) during exacerbation and shifted toward other epitopes of MBP at the time of remission. Furthermore, there was a marked increase in the production of T(h)1 cytokines among T cell lines obtained during exacerbation compared to those obtained during remission. The study demonstrated that myelin-reactive T cells underwent selective activation and expansion during acute MS exacerbation. In contrast, myelin-reactive T cells found during remission in the same patients generally resembled those identified in healthy controls with some discrepancies. The findings suggest potential association of aberrant myelin-reactive T cell responses with acute exacerbation in MS, which may reflect transient activation of myelin-reactive T cell populations of pathogenic potential.     

The mechanisms of coronary restenosis: insights from experimental models

Since its introduction into clinical practice, more than 20 years ago, percutaneous transluminal coronary angioplasty (PTCA) has proven to be an effective, minimally invasive alternative to coronary artery bypass grafting (CABG). During this time there have been great improvements in the design of balloon catheters, operative procedures and adjuvant drug therapy, and this has resulted in low rates of primary failure and short-term complications. However, the potential benefits of angioplasty are diminished by the high rate of recurrent disease. Up to 40% of patients undergoing angioplasty develop clinically significant restenosis within a year of the procedure. Although the deployment of endovascular stents at the time of angioplasty improves the short-term outcome, 'in-stent' stenosis remains an enduring problem. In order to gain an insight into the mechanisms of restenosis, several experimental models of angioplasty have been developed. These have been used together with the tools provided by recent advances in molecular biology and catheter design to investigate restenosis in detail. It is now possible to deliver highly specific molecular antagonists, such as antisense gene sequences, to the site of injury. The knowledge provided by these studies may ultimately lead to novel forms of intervention. The present review is a synopsis of our current understanding of the pathological mechanisms of restenosis.     

High frequency of circulating gamma delta T cells with dominance of the v(delta)1 subset in a healthy population

TCR gamma delta(+) cells constitute <5% of all circulating T cells in healthy, adult Caucasians, and V(delta)1(+) cells constitute a minority of these cells. In contrast to TCR alpha beta(+) cells, their repertoire is selected extrathymically by environmental antigens. Although increased frequencies of V(delta)1(+) cells are found in several diseases, their function remains obscure. Here we show that the frequency of peripheral blood gamma delta T cells in healthy West Africans is about twice that of Caucasians, mainly due to a 5-fold increase in V(delta)1(+) cells, which is consequently the dominant subset. No age dependency of V(delta)1 frequencies was identified and the V(delta)1(+) cells in the African donors did not show preferential V(gamma) chain usage. Analysis of the CDR3 region size did not reveal any particular skewing of the V(delta)1 repertoire, although oligoclonality was more pronounced in adults compared to children. The proportions of CD8(+), CD38(+) and CD45RA(hi)CD45RO(-) cells within the V(delta)1(+) subset were higher in the African than in the European donors, without obvious differences in expression of activation markers. No significant correlations between levels of V(delta)1(+) cells and environmental antigens or immunological parameters were identified. Taken together, the evidence argues against a CDR3-restricted, antigen-driven expansion of V(delta)1(+) cells in the African study population. Our study shows that high frequencies of TCR gamma delta(+) cells with dominance of the V(delta)1(+) subset can occur at the population level in healthy people, raising questions about the physiological role of V(delta)1(+) T cells in the function and regulation of the immune system.