CysLT2受体拮抗剂HAMI3379抑制LPS诱导小鼠小胶质瘤细胞系的炎性反应

目的探究半胱氨酰白三烯2(CysLT2)受体拮抗剂HAMI3379对LPS诱导小鼠小胶质细胞(BV-2)炎性反应的调控作用及其可能的作用机制。方法体外培养BV-2,将BV-2分为对照组、LPS(100 ng/mL)组、HAMI3379(0.01、0.1和1μmol/mL)组和LPS+HAMI3379组。CCK-8法检测BV-2细胞的增殖;ELISA检测细胞上清液中炎性因子IL-1β、TNF-α、IL-10的含量;Western-blot检测PKCα、IKBα、NF-κB p50和p65蛋白的表达。结果LPS能够激活BV-2细胞,促进其细胞的增殖(P<0.05);显著增加细胞上清液中炎性因子IL-1β、TNF-α的分泌,减少IL-10的分泌(P<0.05);且显著上调PKCα、IKBα、p65蛋白的表达水平(P<0.05)。CysLT2受体拮抗剂HAMI3379能够显著减轻上述变化(P<0.05)。结论CysLT2受体拮抗剂HAMI3379能够抑制LPS激活BV-2细胞,抑制炎性反应,其作用机制可能与抑制PKCα/NF-κB信号通路有关。     

Physical association and functional relationship between protein kinase Cζ and the actin cytoskeleton

Protein kinase C (PKC) was initially identified as a serine/threonine protein kinase dependent on calcium and phospholipids and shown to be involved in intracellular signaling pathways. PKC isoforms have been classified into four groups: Ca²⁺-dependent conventional PKC α, βI, βII, γ; Ca²⁺-independent, novel PKC δ, ?, η, θ; atypical PKCζ, λ, ι which are not activated by Ca²⁺ or diacylglycerol, and the recently discovered PKCμ. We reported that activation of the ζ PKC isoform is an important step in interleukin-2 (IL-2)-mediated proliferation (Gómez, J., Pitton, C., García, A., Martínez, A., Silva, A. and Rebollo, A., Exp. Cell Res. 1995. 218: 105.). ζPKC is also required for mitogenic activation of fibroblasts and for the maturation pathway activated by insulin and Ras. Contradictory results have been reported regarding the subcellular redistribution of ζPKC upon activation. We report here, using confocal microscopy, that IL-2 induces expression, translocation and association of ζPKC to a structure coincident with the actin cytoskeleton. Furthermore, we show that ζPKC has a role in maintaining the integrity of the actin cytoskeletal structure in IL-2-stimulated cells. On the contrary, ζPKC is not involved in the actin cytoskeleton organization when cells are maintained in IL-4, confirming our previous results showing that IL-4-induced signal transduction is PKC independent.     

The influence of HIV on CD127 expression and its potential implications for IL-7 therapy

Interleukin-7 (IL-7) is critical for early T-cell development and plays an important role in T-cell homeostasis, differentiation and function. Signalling via the IL-7 receptor is dependent on the expression of its components, IL-7Rα (CD127) and IL-2Rγ (CD132) and is mediated in part by alterations in CD127 expression levels in different cell subsets. Naïve and memory T-cells express high levels of CD127, while effector cells are CD127^lo and retention of the receptor is thought to influence the development of memory cells. Reduced expression of CD127 has been associated with markers of disease severity in HIV infection and other chronic viral infections as well as in various cancers. In HIV infection, decreased CD127 expression on T-cells is correlated with reduced CD4⁺ T-cell counts, increased viral replication and immune activation. The loss of IL-7 activity, due to decreased CD127 expression, may contribute to the observed loss of CD8⁺ cytotoxic T lymphocyte (CTL) activity in HIV infection. The downregulation of CD127 expression in HIV infection may be due to host (e.g. IL-7, IL-4, immune activation) and/or viral (e.g. HIV-tat) factors and mechanisms of receptor regulation may differ by cell type. In addition, the expression of a soluble form of CD127 (sCD127) has been shown to be increased in HIV infection. This protein may affect IL-7 activity in vivo and therefore may have implications for IL-7-based therapies which are currently being tested in clinical trials. Understanding how CD127 is regulated during HIV infection will provide insight for the development of novel therapeutics to improve immune function and anti-viral T-cell activity.     

Autocrine regulation of T-lymphocyte proliferation: differential induction of IL-2 and IL-2 receptor.

Three stimuli were used to compare the signals necessary for interleukin (IL-2) receptor expression and IL-2 production: triggering of the T-cell antigen receptor/CD3 complex (Ti/CD3) by CD3 antibodies, activation of protein kinase C (PKC) by phorbol esters, and elevation of intracellular calcium levels by calcium ionophore. The salient observations were that IL-2 responsiveness, which reflects IL-2 receptor expression, and T-cell proliferation which requires both IL-2 production and IL-2 receptor expression, are not co-ordinately regulated. Firstly, a low threshold of CD3 activation or a brief (1 hr) exposure of T cells to maximal CD3 stimulation is sufficient to induce IL-2 responsiveness, but higher levels of activation for a prolonged period are necessary to ensure a T-cell proliferative response. Secondly, in response to optimal T-cell stimulation there is a short (2-4 day) period of T-cell proliferation followed by a prolonged phase of IL-2 responsiveness (10-14 days). Differences in the kinetics and signalling requirements for IL-2 receptor expression and IL-2 production, regulated at the level of mRNA expression, provide a molecular basis for these observations. A major difference between induction of IL-2 production and IL-2 receptor expression is that the dual signals of calcium and PKC are necessary for IL-2 production, but a sole stimulus of PKC is sufficient for IL-2 receptor expression. Also, a low level stimulation of PKC will induce IL-2 receptor expression but higher levels of PKC stimulation are required for IL-2 production. As a consequence, triggering of a single receptor, namely the Ti/CD3 complex, results in IL-2 responsiveness, but an additional signal that activates PKC is necessary for IL-2 production. These observations suggest that a Ca2+/PKC dual signal model does not explain completely the signal transduction pathways that regulate T-cell growth. Moreover, precise regulatory mechanisms have evolved to control the homeostasis of the autocrine proliferative response of a T-cell population.     

Regulation of CD69 expression on human natural killer cells: differential involvement of protein kinase C and protein tyrosine kinases

Human peripheral blood natural killer (NK) cells (CD56⁺, CD16⁺, CD3_ε^? lymphocytes) express CD69 after their stimulation by interleukin-2 (IL-2) or interferon-α (IFN-α). This activation antigen represents a triggering surface molecule in NK cell clones as its stimulation triggers the cytolytic machinery of these cells. However, the mechanisms regulating the expression of CD69 in NK cells are unknown despite the functional relevance of CD69 in NK cell activation. Thus, we have analyzed the role of protein kinase C (PKC) and protein tyrosine kinases (PTK) in the expression of CD69 on purified NK cells activated by IL-2, IFN-α, anti FcγRIII (CD16) monoclonal antibodies or by K562 target cells. We found that CD69 is induced on NK cells not only by IL-2 and IFN-α but also by activation of the CD 16 pathway, the interaction with NK target cells and the direct activation of PKC by phorbol 12-myristate 13-acetate (PMA), indicating that CD69 induction is associated to different NK activation pathways. The treatment with the PKC inhibitor staurosporine abolished the induction of CD69 induced by PMA or K562. However, it did not significantly affect CD69 induction by IL-2, IFN-α or CD 16 cross-linking. This demonstrates that whereas PKC can play a central role in the regulation of CD69 expression in some instances (response to K562 cells or PMA), it does not participate in others (response to IL-2, IFN-α or anti CD16 monoclonal antibodies). On the other hand genistein, a competitive inhibitor of PTK enzymes, blocked the expression of CD69 induced by activation of NK cells via IL-2 or IFN-α receptors, CD16 and K562 receptor(s), indicating that stimulation of PTK is a common step in the signal transduction events leading to the induction of CD69 antigens after the activation of NK cells via these receptors.     

Interleukin (IL)-2 activation of p21ras in murine myeloid cells transfected with human IL-2 receptor beta chain.

The T cell growth factor interleukin-2 (IL-2) induces p21ras activation in T lymphocytes. To determine whether the IL-2 receptor (IL-2R) can regulate p21ras when expressed in a non-T cell environment we have examined the ability of IL-2 to activate p21ras in 32D murine myeloid progenitor cells transduced with human IL-2R beta chains. These cells are denoted beta 53 cells. 32D cells normally proliferate in response to IL-3 but the expression of the IL-2R beta chain confers IL-2 responsiveness to the cells. Our data show that IL-3 is able to activate p21ras in the parental 32D cells and both IL-2 and IL-3 can stimulate p21ras in the IL-2R-expressing beta 53 clone of 32D. In T lymphocytes, activation of protein kinase C (PKC) with phorbol esters is sufficient to stimulate p21ras. However, in 32D and beta 53 cells activation of PKC with phorbol esters does not result in p21ras activation even though these cells express functional PKC. It appears, therefore, that a PKC-mediated pathway for p21ras regulation exists in T lymphocytes but not in 32D cells. The IL-2R can couple to p21ras independently of the concomitant presence of the PKC pathway for p21ras regulation. These data imply that multiple intracellular mechanisms may exist to regulate p21ras and that cells of different lineages may differ with regard to p21ras regulation.     

Multiple signal transduction pathways activated through the T cell receptor for antigen.

The T cell receptor for antigen (TCR) is a multichain complex on the surface of T lymphocytes which binds peptide antigen and transduces a transmembrane signal leading to IL-2 secretion. Engagement of the TCR leads to activation of a tyrosine phosphorylation pathway and a phospholipase C (PLC) pathway leading to activation of protein kinase C (PCK). Currently available data suggest that the primary event in signal transduction is tyrosine kinase activation, since when this pathway is inhibited, PLC activation is blocked and there is no production of IL-2. The nature of the tyrosine kinase which initiates the signaling cascade is currently unknown. The CD4/CD8 associated kinase p56lck clearly plays a role in tyrosine phosphorylation, but it is clearly not the only tyrosine kinase involved. Studies demonstrating physical association of p59lyn with the TCR implicate fyn as an important candidate for the TCR tyrosine kinase. The protein tyrosine phosphatase CD45 also plays a critical early role in signal transduction since in cells where it is deficient, neither tyrosine kinase activation nor later signaling events are seen. The importance of the PLC/PKC pathway is illustrated by the fact that activation of this pathway alone may lead to IL-2 production. However, there may also be other mechanisms which can generate an IL-2 response. Two proteins known to be involved in growth regulation--p21ras and c-raf--have now been shown to be downstream targets of the PLC/PKC pathway.     

IL-2 linked to a peptide from influenza hemagglutinin enhances T cell activation by affecting the antigen-presentation function of bone marrow-derived dendritic cells

Chimeric proteins containing antigen linked to cytokines haveshown some promise as vaccine candidates but little is knownof their mechanism of action, particularly at the level of theantigen-presenting cell. We have investigated this using a chimericprotein in which an immunodominant T cell epitope from influenzahemagglutinin peptide (HA), recognized in the context of I-E^d,was fused to IL-2. Immature murine dendritic cells (DC) derivedfrom bone marrow (BMDC) were used to present the chimeric proteinto a T cell hybridoma with TCR specific for the HA peptide (A5cell line). HA–IL-2 was found to induce significantlyhigher T cell activation than HA alone. Although the inclusionof IL-2 and HA separately did increase the response of A5 cellscompared to HA alone, they were not as effective as the HA–IL-2chimeric protein. When an antibody known to block IL-2 receptor chain (CD25) was included, A5 activation was reduced, suggestinga role for the receptor in this process. Expression of CD25on A5 cells was low during activation, implying that the effectwas mediated by CD25⁺ BMDC. Antigen uptake and processing ofHA–IL-2 by BMDC was required since fixing BMDC, priorto antigen exposure, greatly reduced their ability to activateA5 cells. The function of CD25 on DC is currently unknown. Ourresults suggest this receptor may play a role in antigen uptakeand subsequent T cell activation by receptor-mediated endocytosisof antigen attached to IL-2. This finding that may have implicationsfor the development of a new generation of vaccines.     

Protein tyrosine kinases couple the interleukin-2 receptor to p21ras

The T cell growth factor interleukin-2 (IL-2) induces p21^ras activation in T lymphocytes. We have previously shown that a protein kinase C (PKC)-mediated pathway for p21^ras regulation exists in T cells and that the IL-2 receptor (IL-2R) can couple to p21^ras independently of the presence of the PKC pathway for p21^ras regulation. Our data show that in conditions where cellular protein tyrosine kinases (PTK) were efficiently down-regulated by pretreatment with the specific PTK inhibitor herbimycin, the IL-2-induced activation of p21^ras was blocked. Herbimycin did not inhibit the PKC-mediated pathway for p21^ras regulation. Thus, the data indicate that PTK are involved in the coupling of the IL-2R to p21^ras.     

Immunohistochemical analysis of oral lichen-planus-like eruption in graft-versus-host disease after allogeneic bone marrow transplantation

Immunohistochemical analysis of oral lichen-planus-like eruption (LPLE) in graft-versus-host disease (GVHD) using monoclonal antibodies (MoAbs) was performed on five patients after allogeneic bone marrow transplantation (BMT) for leukemia. In the mucosal lesions of LPLE in GVHD, the major population of infiltrated lymphocytes in the areas of upper lamina propria (Lp), basal cell layer (Bc), and epithelium above the basal cell layer (Ep) were T-cells (Leu-1+, Leu-4+) and expressed the phenotype associated with suppressor/cytotoxic T-cells (Leu-2a+) rather than helper/inducer T-cells (Leu-3a+). Some of the infiltrated lymphocytes in the areas of Lp, Bc, and satellite cell necrosis (SCN) bore interleukin-2 (IL-2) receptor. HLA-DR antigen was expressed on keratinocytes in the LPLE lesions. Immunoelectron micrographs showed various degrees of degeneration of keratinocytes to which Leu-2a+ cells attached, whereas those with accidentally attached Leu-3a+ cells preserved normal structures. These findings suggest that cellular immunity mediated by cytotoxic T-cells may play a major role in the pathogenesis of oral LPLE in GVHD.     

Ligation of RARgamma inhibits proliferation of phytohaemagglutinin-stimulated T-cells via down-regulating JAK3 protein levels

The mechanisms whereby Vitamin A regulates the immune system are poorly understood. We have shown previously that retinoic acids, the Vitamin A derivatives, promote both apoptosis of neglected thymocytes and the activation-induced cell death of peripheral T-cells via ligating the nuclear retinoid receptor (RAR) gamma. In the present study, we found that human peripheral T-cells express RARalpha and gamma, but not RARbeta. Increasing concentrations of 9-cis RA inhibited phytohaemagglutinin (PHA)-induced proliferation of T-cells, an effect that could be mimicked only by addition of RARgamma agonists and could be inhibited by an RARgamma antagonist. Interleukin-2 (IL-2) produced is known to mediate PHA-induced proliferation of T lymphocytes. Ligation of RARgamma did not affect the PHA-induced high affinity IL-2 receptor expression, slightly reduced the PHA-induced IL-2 production, but interfered with the IL-2-mediated signal transduction resulting in inhibition of PHA-induced phosphorylation of retinoblastoma protein and of up-regulation of Bcl-2. Janus kinases JAK1 and JAK3 play a determinant role in IL-2-dependent signal transduction. Ligation of RARgamma did not affect the levels of JAK1, but prevented IL-2-induced expression of JAK3 resulting in inhibition of PHA-induced phosphorylation of Stat5 molecules. Our data suggest that the previously observed toxic effect of high concentrations of retinoids on the immune system might be mediated via formation of 9-cis RA, which via ligation of RARgamma not only induces cell death in immature thymocytes, but inhibits proliferation of T-cells as well.     

The role of protein kinase C in the regulation of extracellular signal-regulated kinase by the T cell antigen receptor

The aim of this study was to explore the role of protein kinase C (PKC) in the activation of mitogen-activated protein kinases (MAPK) in T lymphocytes. The MAPK extracellular signal-regulated kinase-2 (ERK2) is activated in response to phorbol esters which stimulate PKC, by transient expression of a constitutively active ras mutant, by cell activation via the G protein-coupled type 1 muscarinic acetylcholine receptor (HM1R) or in response to triggering of the T cell antigen receptor (TCR). The relative contribution of PKC to TCR and HM1R regulation of ERK2 was explored by examining the effects of a PKC inhibitor (Ro 31-8425) on ERK2 activation. The data demonstrate that phorbol ester and HM1R regulation of ERK2 was prevented by the PKC inhibitor, but that the inhibitor had no effect on ERK2 activation induced by expression of a constitutively active ras mutant p21v-Ha-ras. Furthermore, the TCR stimulates both PKC and p21^ras but TCR regulation of ERK2 was only weakly suppressed by the PKC inhibitor. These data indicate that PKC has a potential but not a predominant role in TCR regulation of ERK2.     

Involvement of LFA-1/ICAM-2 adhesive interactions and PKC in activation-induced cell death following SEB rechallenge.

Ligation of T-cell receptor (TCR) causes mature T cells to proliferate or, on re-exposure to antigen, can cause them to die by activation-induced cell death (AICD). In proliferative responses, costimulatory and adhesive interactions are required and activation of protein kinase C (PKC) has been shown to be essential. Whether or not interactions involving costimulatory signals and PKC have a role in facilitating AICD remains unclear. Here we have examined the role of CD28/B7 and leucocyte function associated antigen-1 (LFA-1)/intracellular adhesion molecule (ICAM) mediated interactions in AICD triggered by staphylococcal enterotoxin B (SEB) in murine lymph node T cells. We show that, after a primary proliferative response to SEB, LFA-1/ICAM-2 adhesive interactions can play a part in AICD following SEB rechallenge, while B7 and ICAM-1 mediated interactions are not essential for this process. In addition, using a highly selective PKC inhibitor, Ro31.8425, we show that PKC activation is essential for the regulation of AICD by SEB rechallenge.     

The role of protein kinase C in early activation vs. growth of T lymphocytes

Protein kinase C (PKC) has been implicated in the signaling of a number of cellular responses including activation of T cells. In an approach to study the role of PKC in both early activation and interleukin 2 (IL2)-dependent growth, we have used in vivo phosphorylation of endogenous substrates as a marker for PKC activation. In the present report the requirements for CD3-specific activation of PKC are defined, and it is shown that the conditions required for optimal activation coincide with the induction of a proliferative response. Moreover, it is also shown that IL2 receptor interactions induce only low levels of PKC substrate phosphorylation and that IL2 does not cooperate with CD3-specific signals on the level of PKC activation.     

Activation of Human T Lymphocytes by Phorbol-12,13-Dibutyrate and Ionomycin

The calcium ionophore ionomycin and the phorbol ester phorbol-12,13-dibutyrate (PDBu) are shown to have a synergistic effect upon interleukin 2 (IL-2) production, interleukin 2 receptor expression, and T-lymphocyte proliferation. The proliferative response was inhibited by addition of a monoclonal antibody directed against the IL-2R (Tac antigen) demonstrating that PDBu and ionomycin induce T-cell growth through an IL-2-dependent autocrine pathway. Sequential stimulation with PDBu and ionomycin failed to induce IL-2 production, IL-2R expression, and consequently proliferation of the T cells, indicating that T-cell activation requires simultaneous activation of protein kinase C (PKC) and elevation of cytosolic calcium. Exposure of T cells to both agents for different times resulted in IL-2 production, IL-2R expression, and proliferation in proportion to the duration of incubation with at least 4 h required for maximal T-cell activation. Further, in the presence of PDBu maximal T-cell activation was found to require stimulation with ionomycin for 4 h, indicating that a sustained increase in free cytoplasmic calcium of several hours' duration is essential for T-cell activation. In contrast T cells incubated with ionomycin were induced to produce IL-2 and express IL-2Rs upon brief exposure to PDBu with a 2-h incubation period being sufficient for maximal T-cell activation. Thus transient activation of PKC seems to be sufficient for activation of the IL-2 gene and IL-2R gene. However, maximal T-cell activation requires activation of PKC for at least 2 h.     

Histamine H1 receptor-stimulated interleukin 8 and granulocyte macrophage colony-stimulating factor production by bronchial epithelial cells requires extracellular signal-regulated kinase signaling via protein kinase C

BACKGROUND: Histamine stimulates the release of several cytokines, such as interleukin (IL)-8 and granulocyte macrophage colony-stimulating factor, from bronchial epithelial cells. However, the functional individual histamine receptor subtype and intracellular signaling in bronchial epithelial cells are poorly defined. METHODS: Using human primary epithelial cells and the NCI-H292 cell line, we examined the expression of histamine receptor subtypes and histamine-induced second messenger. We also evaluated the involvements of mitogen-activated protein kinase, protein kinase C (PKC) and epidermal growth factor receptor in cytokine expression caused by histamine. RESULTS: Histamine H1 receptor (H1R) was the only subtype expressed in both types of cells. Histamine elevated intracellular calcium ion without affecting cAMP levels. Histamine induced the phosphorylation of extracellular signal-regulated kinase (ERK) 1/2. Histamine also phosphorylated PKC and myristoylated alanine-rich C kinase substrate. Ro-31-8220, a PKC inhibitor, and PD98059, a mitogen-activated protein/ERK kinase inhibitor, suppressed the histamine-induced ERK activation and the production of granulocyte macrophage colony-stimulating factor and IL-8. On the contrary, histamine had no effect on the phosphorylation of epidermal growth factor receptor, and its specific inhibitor AG1478 failed to inhibit the histamine-induced ERK activation. Olopatadine, an H1 antagonist, completely blocked the histamine-related responses, whereas H2 and H3 antagonists did not. Histamine also augmented the IL-8 production caused by IL-4 or tumor necrosis factor-alpha. CONCLUSIONS: The H1R-PKC-ERK pathway may play crucial roles in eliciting cytokine production from bronchial epithelial cells stimulated by histamine, leading to airway inflammation.     

Harnessing the tumour-derived cytokine, CSF-1, to co-stimulate T-cell growth and activation

Aberrant growth factor production is a prevalent mechanism in tumourigenesis. If T-cells responded positively to a cancer-derived cytokine, this might result in selective enhancement of function within the tumour microenvironment. Here, we have chosen colony-stimulating factor-1 (CSF-1) as a candidate to test this concept. CSF-1 is greatly overproduced in many cancers but has no direct effects upon T-lymphocytes, which do not express the c-fms-encoded CSF-1 receptor. To confer CSF-1-responsiveness, we have expressed the human c-fms gene in immortalized and primary T-cells. Addition of soluble CSF-1 resulted in synergistic enhancement of IL-2-driven T-cell proliferation. CSF-1 also co-stimulated the production of interferon (IFN)-gamma by activated T-cells. These effects required Y809 of the CSF-1R and activation of the Ras-MEK-MAP kinase cascade, but were independent of PI3K signalling. T-cells that express c-fms are also responsive to membrane-anchored CSF-1 (mCSF-1) which, unlike its soluble counterpart, could co-stimulate IL-2 production. CSF-1 promoted chemotaxis of c-fms-expressing primary human T-cells and greatly augmented proliferation mediated by a tumour-targeted chimeric antigen receptor, with preservation of tumour cytolytic activity. Taken together, these data establish that T-cells may be genetically modified to acquire responsiveness to CSF-1 and provide proof-of-principle for a novel strategy to enhance the effectiveness of adoptive T-cell immunotherapy.