地塞米松对PMA诱导CD18表达的抑制作用

目的:研究GC抑制CD18表达的作用。方法:选用PMA刺激下的U937细胞为实验模型,运用定量RT-PCR、Northern杂交检测U937细胞CD18 mRNA的表达水平。结果:Dex能明显抑制PMA诱导CD18 mRNA的表达,这种抑制作用具有明显的剂量依赖性,GR的拮抗剂RU38486能够明显扭转Dex的抑制作用。结论:Dex通过GR介导能在转录水平上抑制PMA诱导的CD18 mRNA的表达,该作用可能与糖皮质激素受体(GR)在转录水平拮抗NF-κB有关。     

糖皮质激素受体在离体中性粒细胞粘附中的作用

本文通过给予地塞米松（Ｄｅｘ）和糖皮质激素受体（ＧＲ）阻断剂ＲＵ３８４８６研究ＧＲ在大鼠中性粒细胞（ＰＭＮ）粘附过程中作用。结果提示：Ｄｅｘ可以明显抑制ＰＭＮ的粘附，有浓度依赖性；在去肾上腺大鼠给予不同浓度ＲＵ３８４８６未发现对ＰＭＮ粘附有明显影响；若同时以一定的浓度比给予Ｄｅｘ和ＲＵ３８４８６（Ｄｅｘ：ＲＵ３８４８６）则显示Ｄｅｘ抑制ＰＭＮ粘附程度与ＧＲ数量有依赖关系。     

糖皮质激素通过抑制p38MAPK信号通路缓解大鼠内毒素性急性肺损伤

目的： 研究糖皮质激素对内毒素导致的急性肺损伤的影响及作用机制。方法: 成年雄性SD大鼠被随机分为6组：对照组（control 组,n=6）;LPS组（n=24）;地塞米松＋LPS组（Dex＋LPS组,n=24）;糖皮质激素受体拮抗剂RU486组（RU486组,n=6）;RU486+LPS组（n=24）以及RU486＋Dex＋LPS组（n=24）。除对照组和RU486组外,其余4组在注射LPS后1、3、6、12 h又被分为4个亚组。分别检测各组大鼠支气管肺泡灌洗液（BALF）中TNF-α和IL-6的浓度,肺组织的病理变化,以及肺组织中p38MAPK的活化状态和MKP-1的表达情况。另外又分别比较了LPS组与RU486＋LPS组、Dex＋LPS组与RU486＋Dex＋LPS组大鼠48 h的死亡率。结果: 注射LPS后,BALF中TNF-α 和IL-6的浓度明显升高（P<0.05）,HE染色显示肺组织内广泛炎症反应。而这些现象在应用RU486后变得更加严重,并且RU486＋LPS组的死亡率也明显高于LPS组(P<0.05)。地塞米松能明显缓解LPS导致的肺损伤,糖皮质激素受体(GR)参与此作用。另外,在注射LPS后,肺组织中磷酸化的p38MAPK的表达明显升高,而MKP-1的表达则明显受到抑制。地塞米松能显著降低p38MAPK的磷酸化,这一作用也是GR依赖的。结论: 糖皮质激素活化GR诱导肺组织中MKP-1的表达,进而抑制p38MAPK的活化,从而发挥其抗炎作用,缓解LPS诱导的肺损伤。     

阻断糖皮质激素受体的雏鸡抵抗地塞米松诱导的免疫抑制作用

给予雏鸡地塞米松（Dex）10mg～75mg／kg后24h，诱导脾淋巴细胞产生IL－2和IFN诱生的活性，T、B细胞对Con-A的反应性，以及免疫器官（脾脏、胸腺及法氏囊）重量与体重比值均降低（p＜0．01）。用50mg／kg的RU486阻断GR后，对Dex诱导的免疫抑制无明显地逆转作用，表现为阻断GR后，给予（10～75）mg／kg的Dex24h，上述免疫参数仍明显低于正常雏鸡（P＜0．01），与只给予Dex的雏鸡相比较，无明显差异（P＞0．05）。用25mg／kg的RU486阻断GR，对Dex诱导的免疫抑制作用具有明显地逆转作用，阻断GR后再给予（10～75）mg／kg的Dex后24h，上述免疫参数明显高于只给予Dex的雏鸡（P＜0．01）。若给予10mg／kg或25mg／kg的Dex时，上述免疫参数接近正常水平，表明Dex对雏鸡的免疫抑制作用主要由GR所介导，给予适当量的RU486阻断GR的功能，有利于雏鸡抵抗糖皮质激素诱导的免疫抑制作用。     

糖皮质激素对TNF引起的中性粒细胞粘附的影响

我们的工作曾发现Dex对大鼠PMN(中性粒细胞)与玻璃珠粘附有明显的抑制作用,其作用可被Ru 486所逆转。本实验试图观察Dex对TNF(肿瘤坏死因子)引起的PMN粘附的影响,及给予Ru 486阻断糖皮质     

糖皮质激素及其受体对细胞数量稳态调节的作用

糖皮质激素(GC)/糖皮质激素受体(GR)能够抑制体内多种细胞的增殖,近年来还发现GC/GR对多种凋亡诱导因子导致的细胞凋亡具有拮抗作用。我们因此提出GC/GR可能通过上述作用来维持细胞数量的稳定,这种对细胞数量的稳态调节可能是GC/GR对机体稳态调节的一个重要方面。本文结合我们自身的工作综述了GC/GR抑制细胞增殖和抗凋亡的作用,并简述了其作用机制的研究进展。这方面的研究有助于充分了解GC的生理和药理作用以及副作用产生的机制,有助于临床合理用药。     

超抗原SEB对角质形成细胞糖皮质激素受体的作用研究

目的探讨超抗原金黄色葡萄球菌肠毒素B(SEB)对人永生化角质形成细胞(Ha Ca T细胞)糖皮质激素受体表达及核转移的影响。方法采用不同浓度SEB作用于体外培养的Ha Ca T细胞,RT-PCR、Western blot分别检测Ha Ca T细胞糖皮质激素受体α、β(GRα、GRβ)m RNA、蛋白的表达;随后用SEB预处理Ha Ca T细胞,地塞米松再作用Ha Ca T细胞8 h后,免疫荧光法检测Ha Ca T细胞GRα细胞内分布情况。结果 SEB作用Ha Ca T细胞后,其GRαm RNA、蛋白表达无明显变化,GRβm RNA、蛋白表达随SEB的浓度增高呈上升趋势,且在SEB质量浓度为100 ng/ml时达到最高值。10-6mol/L地塞米松作用8 h后能够诱导Ha Ca T细胞GRα由胞浆向胞核转移,该效应能够维持到24 h。与地塞米松组Ha Ca T细胞内GRα分布出现向核内转移现象不同,地塞米松+SEB组部分细胞GRα分布仍局限于胞质,并未出现核转移现象。结论 SEB可能通过诱导角质形成细胞GRβ表达上调及抑制地塞米松诱导的GRα由胞浆向胞核转移参与炎症性皮肤病外用糖皮质激素抵抗。     

糖皮质激素受体阻断对大鼠内毒素血症时肠系膜微循环变化的影响

以Ru_(486)阻断糖皮质激素受体(GR),观察了静脉注射内毒素引起的肠系膜微循环变化以及地塞米松预处理的保护作用。实验结果提示:1.内毒素血症时内源性糖皮质激素就有通过其受体介导的微循环保护作用;2.糖皮质激素不仅在应激情况下,即使在正常情况下可能就有抑制白细胞活化作用;3.大剂量糖皮质激素对内毒素休克有一定的防治作用,这一作用至少部分地是由GR所介导的。     

糖皮质激素对肿瘤坏死因子引起的中性粒细胞粘附的影响

我们的工作曾发现地塞米松(Dex)对大鼠中性粒细胞(PMN)的粘附具有明显的抑制作用,其作用可被Ru486所逆转。本实验采用大鼠PMN与玻璃珠粘附及大鼠PMN与大鼠主动脉离体培养的内皮细胞粘附的模型,观察Dex对TNF作用的影响。结果如下:PMN与玻璃珠粘附的粘附率分别为:对照组30.80±19.89%,     

皮质酮对大鼠脊髓背角星形胶质细胞活动的影响

目的:探讨皮质酮(corticosterone,CORT)对培养的大鼠脊髓背角星形胶质细胞活性的调节作用。方法:培养纯化新生SD大鼠脊髓背角星形胶质细胞,荧光双重标记技术检测培养的星形胶质细胞糖皮质激素受体(glucocorticoid receptor,GR)及胶质纤维酸性蛋白(glial fibrillary acidic protein,GFAP)共表达;免疫印迹技术检测星形胶质细胞GFAP表达的变化;高效液相色谱法(high performance liquid chromatography,HPLC)检测星形胶质细培养液中谷氨酸含量。结果:培养的脊髓背角星形胶质细胞均表达GR;CORT孵育3 h可降低脊髓背角星形胶质细胞GFAP表达,GR拮抗剂RU38486可阻断CORT的作用;但CORT对星形胶质细胞谷氨酸释放无显著影响。结论:CORT可降低脊髓背角星形胶质细胞GFAP表达,但对谷氨酸释放无显著影响。     

大剂量糖皮质激素减轻大鼠创伤性脑水肿的受体机制

以创作性脑水肿的大鼠模型对作者提出的药理剂量的糖皮质激素通过低亲和力糖皮质激素受体的介导发挥治疗作用的假说作了验证。结果发现，只有当血浆地塞米松浓度达到１０＾－６ｍｏｌ／Ｌ时才能使脑水肿减轻，这减轻作用可被糖皮质激素受体的竞争性拮抗剂ＲＵ４８６所逆转，符合于我们的假说。     

地塞米松对人卵巢癌HO-8910细胞ERK和p38活性的快速作用

目的:观察人工合成糖皮质激素地塞米松 (Dex)对人卵巢癌细胞系HO-8910中丝裂原激活的蛋白激酶 (MAPK)家族成员ERK1/2和p38活性的影响。方法:Westernblot测定ERK和p38活性。结果:10^-7mol/LDex在 5min内即可引起ERK1和ERK2活性下降,30min作用最明显,分别比对照降低 41%和 54 % (均P <0.01);之后回升,4h后活性达对照水平;该作用具有激素浓度 (10^-10-10^-6 mol/L)依赖性。Dex还可在 5min内增加p38活性,15min作用最显著,比对照增加 84% (P <0.01),1h后达对照水平。这些作用不能被糖皮质激素受体 (GR)拮抗剂RU486所阻断。结论:Dex能够以GR非依赖性方式,快速抑制HO-8910细胞ERK1/2活性和促进p38活性,可能参与其抑制细胞增殖作用.     

兔体外循环中糖皮质激素受体变化及应用大剂量糖皮质激素的效应

本文应用兔体外循环（ＣＰＢ）模型研究ＣＰＢ中糖皮质激素受体（ＧＲ）的变化及早期应用大剂量糖皮质激素（ＧＣ）的效应。结果发现，兔胸腺高亲和力ＧＲ数目在ＣＰＢ６０ｍｉｎ较ＣＰＢ前显著下降（－３５％），ＣＰＢ中血浆ＧＣ浓度显著升高，同时伴有血浆磷脂酶Ａ２（ＰＬＡ２）活性和肺血管外含水量（ＥＶＬＷ／ＢＦＤＬ）显著升高；在ＣＰＢ前５ｍｉｎ静注琥珀酸钠氢化考的松２０ｍｇ／ｋｇ，虽使胸腺ＧＲ水平进一步下降（－６９％），但能显著提高ＣＰＢ期间血浆ＧＣ浓度，并能显著抑制血浆ＰＬＡ２活性和ＥＶＬＷ／ＢＦＤＬ的升高。提示ＣＰＢ能引起ＧＲ水平下降，从而降低ＧＣ效应；ＣＰＢ术中早期应用大剂量ＧＣ能在ＣＰＢ中ＧＲ减少的情况下维持或提高ＧＣ的效应，但其作用很可能并非完全通过高亲和力ＧＲ介导。     

Glucocorticoid-mediated regulation of thymic dendritic cell function.

The possible effects of glucocorticoids (GC) on the biology of thymic dendritic cells (DC) have been analyzed. Both DC and GC seem to be involved in intrathymic T cell selection but possible relationships, if any, between them remain currently unknown. For the first time, we have proved the expression of GC receptors in thymic DC. Moreover, our data demonstrate that in vitro dexamethasone (Dex) treatment barely affects the viability of mature thymic DC, which are largely resistant to its apoptotic effect. Dex-treated thymic DC also show a slightly reduced surface expression of some adhesion and co-stimulatory molecules in correlation with diminished allostimulatory properties. Furthermore, the production of both IL-1beta and tumor necrosis factor (TNF)-alpha, but not that of IL-6 and IL-10, diminished in the mixed leukocyte reaction established with Dex-treated thymic DC. However, the addition of recombinant rat IL-1beta and TNF-alpha, alone or in combination, did not recover the allostimulatory capacity. Taken together, these results support certain GC-mediated regulation of the activity of thymic DC which could be relevant for the biology of the thymus gland.     

A role for anti-CD45RB monoclonal antibody treatment upon dendritic cells

Selective interference with CD45RB isoform by monoclonal antibody (anti-CD45RBmAb) reliably induces donor-specific tolerance. Dendritic cells (DCs) are the most potent antigen-presenting cells that are capable of activating na?ve T cells. The purposes of the present study were to investigate the roles of anti-CD45RBmAb on the phenotypes and functioning of DCs and to further illustrate the mechanism of anti-CD45RBmAb-inducing immunologic tolerance. DCs from C57BL/6 mice were cultured and treated with various doses of anti-CD45RB monoclonal antibody. Cell phenotype, cycle and phagocytic ability were detected by flow cytometry. The production of IL-10 and IL-12 in the supernatants of mature DCs was measured with ELISA. Exosomes (Dex) were recovered from the supernatant of DCs cultured for 6 days in depleted medium, and effects of DCs and Dex on the ability of T-cell proliferation were detected by mixed lymphocyte culture. Anti-CD45RBmAb could inhibit DCs maturation in a dose-dependent manner, and the effects of exosomes (Dex) on DCs enhance or inhibition proliferation of T cells were also in a dose-dependent manner. Anti-CD45RBmAb could profoundly inhibit the maturation and functioning of DCs and generate tolerogenic dendritic cells (tDCs) as well as Dex, suggesting mechanistic contributions to tolerance development from the DCs through interactions with T cells.     

Dexamethasone inhibits the antigen presentation of dendritic cells in MHC class II pathway

Glucocorticoids (GC) are physiological inhibitors of inflammatory responses and are widely used as anti-inflammatory and immunosuppressive agents in treatment of many autoimmune and allergic diseases. In the present study, we demonstrated that one of the mechanisms by which GC can suppress the immune responses is to inhibit the differentiation and antigen presentation of dendritic cells (DC). DC were differentiated from murine bone marrow hematopoietic progenitor cells by culture with GM-CSF and IL-4 with or without dexamethasone (Dex). Our data showed that Dex, in a dose dependent manner, down-regulated surface expression of CD86, CD40, CD54 and MHC class II molecules by DC, but the expression of MHC class I, CD80, CD95 and CD95L were not affected. In addition, Dex-treated DC showed an impaired function to activate alloreactive T cells and to secrete IL-Ibeta and IL-12p70. Moreover, Dex inhibited DC to present antigen by MHC class II pathway. However, the endocytotic activity of DC was not affected. The inhibitory effect of Dex on the expression of costimulatory molecules and the antigen-presenting capacity of DC could be blocked by the addition of RU486, a potent steroid hormone antagonist, suggesting the requirement of binding to cytosolic receptors in the above-described action of Dex. Since DC have the unique property to present antigen to responding naive T cells and are required in the induction of a primary response, the functional suppression of DC by Dex may be one of the mechanisms by which GC regulate immune responses in vivo.     

Suppression of the antigenic response of murine bone marrow B cells by physiological concentrations of glucocorticoids.

Data presented here indicate that the immature B cells of murine bone marrow (BM) may be as sensitive to glucocorticoids (GC) as are immature thymocytes, since physiological levels of the steroids significantly inhibited the response of these cells to trinitrophenylated lipopolysaccharide (TNP-LPS) in short-term culture. The in vitro response of B cells of the marrow to TNP-LPS was reduced more than 50% by concentrations of corticosterone and cortisol analogous to that found in plasma during stress and trauma. The more potent synthetic GC, dexamethasone (DX), caused a 50-80% decrease in plaque-producing cells at concentrations of 10(-6) and 10(-8) M. The same pattern of inhibition was noticed regardless of whether DX was added 24 hr prior or up to 48 hr after addition of antigen to culture. However, no inhibition in the response of B cells was noted when DX was added 72-96 hr after stimulation of the cultures. These effects were found to be specific for GC since neither testosterone nor progesterone at physiological concentrations inhibited the response, while the glucocorticoid receptor antagonist RU 38486 provided protection. A greater than 80% reduction in the proportion of B cells present in the DX-treated cultures was noted after 5 days, corresponding to the 80% inhibition of plaque-forming cell production observed at that time. This reduction in B cells was rapid since almost 40% of the B220+ cells were depleted within 12 hr of DX addition. These data indicate that physiological levels of GC can readily inhibit the capacity of BM to respond to antigen by depleting the cultures of immature B cells.