S1P1受体ERY保守基序突变对FTY720诱导其内化的影响

1型1-磷酸鞘氨醇受体(S1P1)是淋巴细胞表面的重要受体。为研究S1P1中ERY保守基序与FTY720诱导其内化的关系,以HA-S1P1-Myc-EGFP-N1为模板,应用重叠PCR的方法,将S1P1第142位的Arg(R)突变为Asn(N),连同N端HA标签一起,克隆入pcDNA3.1(+)真核表达载体。同时PCR扩增野生型S1P1,克隆入pcDNA3.1(+)中。限制性酶切消化、PCR和测序鉴定后,经Polyfect转染入HEK293细胞。G418筛选出稳定细胞株。100 nmol/L FTY720处理12 h后,抗HA-PE抗体染色,用流式细胞仪检测S1P1在HEK293细胞上的表达情况。结果显示HA-S1P1(WT)-pcDNA3.1(+)和HA-S1P1(R142N)-pcDNA3.1(+)载体被成功构建,HA-S1P1(WT)和HA-S1P1(R142N)蛋白表达在HEK293稳定细胞株的表面。FTY720能诱导HA-S1P1(WT)内化,但不能诱导HA-S1P1(R142N)内化。提示FTY720诱导S1P1内化与ERY保守基序有关。     

环孢素A诱导妊娠失败模型孕鼠外周母-胎免疫耐受

目的探讨环孢素A(cyclosporin A,CsA)能否诱导妊娠失败模型CBA/J×DBA/2孕鼠外周母-胎免疫耐受。方法分别使用CBA/J×DBA/2及CBA/J×BALB/c作为妊娠失败模型和正常妊娠模型,CBA/J小鼠于妊娠第4天(着床期)腹腔注射不同剂量(0、5、10、15mg/kg)CsA,妊娠第9天和第14天时分别采用单向混合淋巴细胞反应分析孕鼠外周脾脏免疫细胞对父系抗原的增殖能力,并用RT-PCR分析细胞IL-2mRNA含量以研究脾脏细胞母-胎免疫耐受状态;妊娠第14天观察两组的胚胎吸收率。结果(1)于妊娠第4天腹腔注射5、10、15mg/kg CsA后,妊娠失败模型胚胎吸收率分别下降至2.86%、5.75%及11.24%,明显低于对照组(P<0.001,P<0.01,P<0.01);而对妊娠成功模型胚胎吸收率无显著性影响(P>0.05)。(2)混合淋巴细胞反应研究显示,于妊娠第4天腹腔注射CsA,可使妊娠第9、14天的妊娠失败模型孕鼠外周脾脏免疫细胞对父系抗原的增殖能力显著下降(P均<0.01);RT-PCR分析显示,孕鼠脾细胞受父系抗原刺激后IL-2转录显著下降(P均<0.01)。结论于孕早期腹腔注射CsA可诱导妊娠失败模型孕鼠外周免疫细胞对父系抗原的特异性免疫耐受,从而使自然流产模型孕鼠的妊娠结局达到正常妊娠水平,提示CsA可能成为治疗妊娠失败的有效药物。     

FTY720诱导1型1-磷酸鞘氨醇受体内化与其保守基序的关系研究

目的:研究FTY720诱导1型1-磷酸鞘氨醇受体(S1P1)内化与后者保守基序之间的关系.方法:以HA-S1P1(WT)-Myc-EGFP-N1融合表达载体为模板,应用重叠PCR的方法,将S1P1保守基序ERY突变为ENY,构建HA-S1P1(R142N)-Myc-EGFP-N1融合表达载体.测序鉴定后,经Polyfect转染入HEK293细胞.G418筛选出稳定细胞株.100 nmol/L FTY720处理3、6、12小时后,荧光显微镜下观察S1P1在HEK293细胞上的表达情况.结果:HA-S1P1(R142N)-Myc-EGFP-N1载体被成功构建,S1P1(WT)和S1P1(R142N)蛋白表达在HEK293稳定细胞株的表面,FTY720能诱导S1P1(WT)内化,但不能诱导S1P1(R142N)内化.结论:FTY720诱导S1P1内化与ERY保守基序有关.     

S1PR2和S1PR3通路激活Rac1参与HGF诱导的血管内皮屏障保护作用

目的观察肝细胞生长因子(hepatocyte growth factor,HGF)介导的1-磷酸鞘氨醇受体2(S1PR2)和1-磷酸鞘氨醇受体3(S1PR3)通路是否通过激活Ras相关C3肉毒素底物1(Rac1)增加血管内皮屏障保护功能。方法培养人肺动脉内皮细胞,应用小RNA干扰技术静默S1PR2/3后,给与HGF处理并应用GTP酶沉降及Western blot检测技术检测人肺血管内皮细胞GTP-Rac1活性变化。结果静默S1PR2或S1PR3后,给与HGF处理,GTP-Rac1活性较S1PR2或S1PR3未静默组明显减弱。结论 HGF介导的S1PR2和S1PR3通路通过激活Rac1增加血管内皮屏障保护功能。     

H_2S抑制高浓度ATP诱导的SH-SY5Y细胞凋亡与P2X_7受体的相关性研究

目的:研究H_2S对高浓度ATP诱导的SH-SY5Y细胞凋亡的保护作用和可能的机制。方法:人神经母细胞瘤SH-SY5Y细胞、HEK 293和HEK 293-hP2X_7R细胞,分为对照组,Na HS组,KN-62组,ATP组,ATP+Na HS组和ATP+KN-62组。倒置显微镜观察细胞形态变化,CCK-8法检测细胞活力,Hoechst 33258核染色分析细胞凋亡,流式细胞术检测细胞凋亡率,Western Blot和RT-PCR法分别检测Caspase-3、Bcl-2在蛋白和mRNA水平的表达。结果:与对照组比较,6 mmol/L ATP处理3 h后SH-SY5Y细胞损伤明显,活力降低至62.7%±3.8%(P0.01),而凋亡率升高至30.75%±5.1%(P0.01)。与ATP组比较,用200μmol/L Na HS和500 nmol/L KN-62预处理30 min,SH-SY5Y细胞活力分别升高至90.1%±3.8%和84.6%±3.1%(P0.05),凋亡率则分别降低至14.73%±3.4%和18.32%±3.1%(P0.01)。ATP组SH-SY5Y细胞内Caspase-3表达上调,Bcl-2表达下调,但Na HS和KN-62可抑制Caspase-3表达,促进Bcl-2表达。与对照组和HEK293细胞比较,用2 mmol/L ATP分别处理HEK 293、HEK 293-h P2X7R细胞3 h,可见HEK 293-h P2X7R细胞内Caspase-3表达上调(P0.01)。与ATP组比较,200μmol/L Na HS预处理30 min,HEK 293-h P2X7R细胞内Caspase-3表达明显下调(P0.01)。HEK 293细胞Caspase-3表达在各组无差异(P0.05)。结论:H2S对高浓度ATP诱导的SH-SY5Y细胞凋亡具有抑制作用,且呈浓度依赖性,其作用机制可能与P2X7R相关。     

嘌呤P2Y受体激动剂ADPβS对脊髓来源小胶质细胞产生IL-1β、IL-6和TNF-α的刺激作用

目的:观察嘌呤P2Y受体激动剂ADPβS对脊髓背角来源小胶质细胞炎症因子IL-1β、IL-6和TNF-α表达和释放的影响。方法:培养新生SD大鼠脊髓背角小胶质细胞,PCR检测ADPβS作用下小胶质细胞IL-1β、IL-6和TNF-α在mRNA水平表达变化;ELISA检测ADPβS作用下小胶质细胞IL-1β、IL-6和TNF-α释放变化。结果:与正常对照组相比,ADPβS(10μmol/L)可以刺激脊髓背角小胶质细胞Iba-1、IL-1β、IL-6和TNF-αmRNA表达上调。P2Y_(12)受体拮抗剂MRS2395和P2Y_(13)受体拮抗剂MRS2211部分阻断ADPβS刺激小胶质细胞IL-1β、IL-6和TNF-αmRNA表达上调,MRS2395和MRS2211联合预处理几乎全部阻断ADPβS刺激小胶质细胞Iba-1、IL-1β、IL-6和TNF-αmRNA表达上调。结论:P2Y_(12)/P2Y_(13)受体激活可以促进脊髓背角小胶质细胞激活和IL-1β、IL-6和TNF-αmRNA表达上调及释放。     

mTOR/P70S6K/HIF-1α信号通路在脂多糖诱导Caco-2细胞屏障损伤中的作用及机制

目的:探讨缺氧诱导因子1α(hypoxia-inducible factor-1α,HIF-1α)在脂多糖(lipopolysaccharide,LPS)诱导的Caco-2细胞屏障损伤中的作用,并探究哺乳动物雷帕霉素靶蛋白(mammalian rapamycin target protein,mTOR)/P70核糖体蛋...     

FTY720, sphingosine 1-phosphate receptor modulator, ameliorates experimental autoimmune encephalomyelitis by inhibition of T cell infiltration

FTY720, a sphingosine 1-phosphate receptor modulator, induces a marked decrease in the number of peripheral blood lymphocytes and exerts immunomodulating activity in various experimental allograft and autoimmune disease models. In this study, we evaluated the effect of FTY720 and its active metabolite, （S）-enantiomer of FTY720-phosphate [（S）-FTY720-P] on experimental autoimmune encephalomyelitis （EAE） in rats and mice. Prophylactic administration of FTY720 at 0.1 to 1 mg/kg almost completely prevented the development of EAE, and therapeutic treatment with FTY720 significantly inhibited the progression of EAE and EAE-associated histological change in the spinal cords of LEW rats induced by immunization with myelin basic protein. Consistent with rat EAE, the development of proteolipid protein-induced EAE in SJL/J mice was almost completely prevented and infiltration of CD4^＋ T cells into spinal cord was decreased by prophylactic treatment with FTY720 and （S）-FTY720-P. When FTY720 or （S）-FTY720-P was given after establishment of EAE in SJL/J mice, the relapse of EAE was markedly inhibited as compared with interferon-β, and the area of demyelination and the infiltration of CD4^＋ T cells were decreased in spinal cords of EAE mice. Similar therapeutic effect by FTY720 was obtained in myelin oligodendrocyte glycoprotein-induced EAE in C57BL/6 mice. These results indicate that FTY720 exhibits not only a prophylactic but also a therapeutic effect on EAE in rats and mice, and that the effect of FTY720 on EAE appears to be due to a reduction of the infiltration of myelin antigen-specific CD4^＋ T cells into the inflammation site. Cellular ＆ Molecular Immunology. 2005;2（6）：439-448.     

The role of the lysophospholipid sphingosine 1-phosphate in immune cell biology

Sphingosine 1-phosphate (S1P) has been shown to be a bioactive lipid mediator intimately involved in mediating a variety of immunological processes. In particular, S1P regulates lymphocyte cell trafficking between the lymphatic system and the blood. The lysophospholipid signals mainly through five related G protein-coupled receptor subtypes, termed S1P₁ to S1P₅. S1P₁ seems to play an essential role in cell trafficking, as this receptor subtype promotes the egress of T and B cells from secondary lymphatic organs. This S1P₁-mediated migratory response is a consequence of different S1P levels in the serum and lymphatic organs. In addition to its direct effects on lymphocyte motility, S1P strengthens cell barrier integrity in sinus-lining endothelial cells, thereby reducing lymphocyte egress out of lymph nodes. Furthermore, S1P modulates cytokine profiles in T and dendritic cells, resulting in an elevated differentiation of T helper-2 cells during the T cell activation process. It is of interest that the mode of molecular action of the novel immunomodulator FTY720 interferes with the signaling of S1P. After phosphorylation, FTY720 shares structural similarity with S1P, but in contrast to the natural ligand, phosphorylated FTY720 induces a prolonged internalization of S1P₁, resulting in an impaired S1P-mediated migration of lymphocytes.     

Role of sphingosine 1-phosphate receptor type 1 in lymphocyte egress from secondary lymphoid tissues and thymus

Circulation of mature lymphocytes between blood and secondary lymphoid tissues plays a central role in the immune system. Homing of lymphocytes from blood into secondary lymphoid tissues beyond high endothelial venules is highly dependent on the interaction between the chemokines CCL19, CCL21, CXCL12, and CXCL13, and their receptors CCR7, CXCR4 and CXCR5. However, the molecular mechanism（s） of lymphocyte egress from secondary lymphoid tissues to lymph remained unclear. We have found a new class of immunomodulator, FTY720 by chemical modification of vegetative wasp-derived natural product, ISP-I （myriocin）. FTY720 has been shown to be highly effective in experimental allograft and autoimmune disease models. A striking feature of FTY720 is the induction of a marked decrease in peripheral blood lymphocytes at doses that show immunomodulating activity in these models. The reduction of circulating lymphocytes by FTY720 is caused by sequestration of lymphocytes into secondary lymphoid tissues and thymus. FTY720 is rapidly converted to （S）-enantiomer of FTY720-phosphate [（S）-FTY720-P] by sphingosine kinase 2 in vivo. （S）-FTY720-P acting as a potent agonist of S1P receptor type 1 （S1P1）, induces long-term down-regulation of S1P1 on lymphocytes, and thereby inhibits the migration of lymphocytes toward S1P. Thus, it is presumed that FTY720-induced lymphocyte sequestration is due to the inhibition of S1P/S1P1-dependent lymphocyte egress from secondary lymphoid tissues and thymus by its active metabolite （S）-FTY720-P. Throughout the analysis of the mechanism of action of FTY720, it is clarified that S1P/S1P1 interaction plays an important role for lymphocyte egress from secondary lymphoid tissues and thymus.     

FTY720 induces apoptosis in B16F10-NEX2 murine melanoma cells,limits metastatic development in vivo,and modulates the immune system

OBJECTIVE:

Available chemotherapy presents poor control over the development of metastatic melanoma. FTY720 is a compound already approved by the Food and Drug Administration for the treatment of patients with multiple sclerosis. It has also been observed that FTY720 inhibits tumor growth in vivo (experimental models) and in vitro (animal and human tumor cells). The aim of this study was to evaluate the effects of FTY720 on a metastatic melanoma model and in tumor cell lines.

METHODS:

We analyzed FTY720 efficacy in vivo in a syngeneic murine metastatic melanoma model, in which we injected tumor cells intravenously into C57BL/6 mice and then treated the mice orally with the compound for 7 days. We also treated mice and human tumor cell lines with FTY720 in vitro, and cell viability and death pathways were analyzed.

RESULTS:

FTY720 treatment limited metastatic melanoma growth in vivo and promoted a dose-dependent decrease in the viability of murine and human tumor cells in vitro. Melanoma cells treated with FTY720 exhibited characteristics of programmed cell death, reactive oxygen species generation, and increased β-catenin expression. In addition, FTY720 treatment resulted in an immunomodulatory effect in vivo by decreasing the percentage of Foxp3+ cells, without interfering with CD8+ T cells or lymphocyte-producing interferon-gamma.

CONCLUSION:

Further studies are needed using FTY720 as a monotherapy or in combined therapy, as different types of cancer cells would require a variety of signaling pathways to be extinguished.     

Involvement of Sphingosine 1-Phosphate （S1P） Receptor Type 1 and Type 4 in Migratory Response of Mouse T Cells toward S1P

Sphingosine 1-phosphate （S1P）, a pleiotropic lysophospholipid, regulates signal transduction pathway via Gprotein-coupled receptors termed S1P1-5 in several types of the cells including lymphocytes. Higher levels of S1P4 mRNA as well as S1P1 mRNA are expressed in lymphoid tissues such as the spleen, thymus, lymph nodes, and Payer＇s patches. In contrast to S1P1 that plays an essential role in lymphocyte egress, little is known about the role of S1P4 in immune system. In this study, we found that S1P at 10 to 100 nM significantly induced the cell migration and the significant levels of S1P1 and S1P4 mRNA were expressed in mouse CD4 T cells, D10.G4.1 mouse Th2 cells, and EL-4.IL-2 mouse thymoma cells. In D10.G4.1 and EL-4.IL-2 cells, S1P-induced migration was almost completely inhibited by pretreatment with pertussis toxin, Clostoridium difficile toxin B, and （S）-enantiomer of FTY720-phosphate, a potent agonist at S1P1 and S1P4. The members of the Rho family small GTPase, Cdc42 and Rac were activated by S1P stimulation in these cells. The transfection with dominant negative or constitutively active forms of Cdc42 and Rac revealed that the activation of both Cdc42 and Rac is essential for S1P-induced migration of these cells. The immunoprecipitation assays using CHO cells co-expressing both S1P4 and S1P1 receptors indicated that S1P4 and S1P1 are associated on the cell surface. These results suggest that the association of S1P4 and S1PI plays an important role in migratory response of mouse T cells toward S1P.     

Inhibition of RhoA and mTORC2/Rictor by Fingolimod (FTY720) induces p21-activated kinase 1, PAK-1 and amplifies podosomes in mouse peritoneal macrophages

Macrophage functions in the immune response depend on their ability to infiltrate tissues and organs. The penetration between and within the tissues requires degradation of extracellular matrix (ECM), a function performed by the specialized, endopeptidase- and actin filament- rich organelles located at the ventral surface of macrophage, called the podosomes. Podosome formation requires local inhibition of small GTPase RhoA activity, and depends on Rac 1/Rho guanine nucleotide exchange factor 7, β-PIX and its binding partner the p21-activated kinase (PAK-1). The activity of RhoA and Rac 1 is in turn regulated by mTOR/mTORC2 pathway. Here we showed that a fungus metabolite Fingolimod (FTY720, Gilenya), which is clinically approved for the treatment of multiple sclerosis, down-regulates Rictor, which is a signature molecule of mTORC2 and dictates its substrate (actin cytoskeleton) specificity, down-regulates RhoA, up-regulates PAK-1, and causes amplification of podosomes in mouse peritoneal macrophages.     

The sphingosine-1-phosphate receptor agonist FTY720 and its phosphorylated form affect the function of CD4+CD25+ T cells in vitro

The sphingosine-1-phosphate receptor agonist FTY720 and FTY720-P have a wide variety of fundamental functions. Many studies have demonstrated that CD4+CD25+ regulatory T (Treg) cells engage in the maintenance of immunological self-tolerance by actively suppressing self-reactive lymphocytes. Although FTY720 has also recently shown to possess an additional effect that increases the functional activity of Treg cells, the mechanism leading to the enhanced Treg activity after FTY720 treatment is still not clear. We isolated Treg cells, which were co-cultured with FTY720 or FTY720-P. The proliferation of co-cultured Treg cells was detected by the cell counting kit-8. The changes of the phenotype CD25+ and forkhead box P3 (Foxp3)+ of co-cultured Treg cells were measured by flow cytometry. The levels of IL-10 and TGF-β1 in the supernatants were detected by Elisa. Cytokine mRNA expressions in co-cultured Treg cells were analyzed by real-time quantitative PCR. Mixed lymphocyte reaction assay examined the suppressive function. We found that neither FTY720 nor FTY720-P affected the proliferation of co-cultured Treg cells. The percentages of CD25+ and Foxp3+ were enhanced in the high-dose FTY720-P group. The levels of TGF-β1 in the supernatants were enhanced in the high-dose FTY720 group. Medium and high-dose FTY720-P also enhanced the levels of TGF-β1. TGF-β1 and Foxp3 mRNA expression were upregulated in the high-dose FTY720-P group. The proliferation of effector T (Teff) cells was suppressed significantly in the medium and high-dose FTY720-P group at a Treg/Teff cell ratio of 1:1. At a ratio of 1:1, the proliferation of Teff cells was also suppressed in the high-dose FTY720 group. It can be concluded that high-dose FTY720-P can enhance the immune function of co-cultured Treg cells, and that medium-dose FTY720-P and high-dose FTY720 could partly enhance the function. The reason may be attributed to enhanced levels of TGF-β1 and Foxp3.     

S1P receptor antagonists fingolimod and siponimod do not improve the outcome of experimental autoimmune myasthenia gravis mice after disease onset

Myasthenia gravis (MG) is an autoimmune disease characterized by muscle weakness and fatigue in the presence of circulating antibodies against components of the neuromuscular junction. Most patients have a good prognosis, but some are refractory to standard‐of‐care immunosuppressive treatment and suffer from recurrent myasthenic crises. Functional sphingosine‐1‐phosphate (S1P) antagonists like fingolimod and siponimod (BAF312) are successfully used for the treatment of multiple sclerosis, and fingolimod was shown to prevent the development of myasthenic symptoms in experimental autoimmune myasthenia gravis (EAMG), the standard model of MG. Here, we investigated whether fingolimod or siponimod improves outcome in EAMG mice when administered after disease onset, modeling the clinical setting in human MG. Both S1P antagonists inhibited lymphocyte egress, resulting in peripheral lymphopenia. After stimulation, there were differences in T‐cell responses, but no change in either antibody titers or total or antigen‐specific plasma cell populations after treatment. Most importantly, disease incidence and severity were not influenced by fingolimod or siponimod therapy. Although fingolimod and siponimod did lead to subtle changes in T‐cell responses, they had no significant effect on antibody titers and disease severity. In conclusion, our data show no evidence of a therapeutic potential for S1P receptor antagonists in MG treatment.